HomeMy WebLinkAboutItem 10e - 2025 Urban Water Management Plan and Water Shortage Contingency Plan
STAFF REPORT
PUBLIC WORKS SERVICES DEPARTMENT
DATE: June 16, 2026
TO: Honorable Mayor and City Council
FROM: Paul Cranmer, Public Works Services Director
By: Rebecca Cardenas, Management Analyst
SUBJECT: RESOLUTION NO. 7702 ADOPTING THE CITY OF ARCADIA’S 2025 URBAN
WATER MANAGEMENT PLAN AND WATER SHORTAGE CONTINGENCY
PLAN
CEQA: Exempt
Recommendation: Adopt
SUMMARY
To comply with the California Urban Water Management Planning Act, the City of
Arcadia is required to adopt an Urban Water Management Plan (“UWMP”) every five
years. The UWMP is a planning document that supports the City’s long-range water
resources planning to ensure adequate water supplies are available to meet existing
and future water demands. A water supplier must have a current UWMP on file to be
eligible for any water grant or loan administered by the State Department of Water
Resources (“DWR”).
The 2025 UWMP provides an assessment of Arcadia’s water service reliability, and
describes and evaluates sources of water supply, efficient uses of water, demand
management measures, and other relevant information and programs. In addition,
the plan includes an evaluation of frequent and severe periods of droughts, as
described in the Drought Risk Assessment, and requires the preparation and
adoption of a Water Shortage Contingency Plan (“WSCP”). This is especially important
in years when drought conditions are anticipated.
Resolution No. 7702 Adopting the 2025 Urban Water Management Plan
and Water Shortage Contingency Plan
June 16, 2026
Page 2 of 6
It is recommended that the City Council adopt Resolution No. 7702, adopting the City
of Arcadia’s 2025 Urban Water Management Plan and Water Shortage Contingency
Plan.
BACKGROUND
The Urban Water Management Planning Act (“Act”) of 1983 requires every urban
water supplier that provides more than 3,000 acre-feet of water annually or serves
more than 3,000 urban water connections, to submit an UWMP every five years. Since
the original Act, subsequent legislative requirements have been incorporated into
the California Water Code to expand the scope of water management planning. The
UWMP requires demonstration of water supply reliability in normal, single dry years,
multiple dry years, and other adverse conditions. As stipulated in Senate Bill 606, the
2025 UWMP must be adopted by July 1, 2026, and submitted to the DWR within 30
days of adoption.
There are a number of requirements for the 2025 UWMP that build upon updates
introduced in prior UWMP cycles. The required chapters in the 2025 UWMP update
include:
• Urban Water Management Plan Introduction and Overview
The City’s 2025 Plan was prepared consistent with the recommended
organization provided in the DWR’s Final “Urban Water Management Plan
Guidebook 2025.”
• Plan Preparation
The City’s Plan has been prepared as an “individual” plan rather than a
“regional” plan to provide information specific to the City to best inform its
employees, management, and customers. Information presented in the City’s
2025 Plan is provided on a “Fiscal Year” basis, which is from July 1 through June
30 of the following year.
• Service Area Description
The City provides water service to a majority of the City of Arcadia and
encompasses an area of approximately 11 square miles. The City of Arcadia is
positioned in the north-central area of the San Gabriel Valley, extending
Resolution No. 7702 Adopting the 2025 Urban Water Management Plan
and Water Shortage Contingency Plan
June 16, 2026
Page 3 of 6
northward into the southerly slopes of the San Gabriel Mountains, and lies
northeast of the City of Los Angeles.
• Water Use Characterization
The City provides water service to individual “water use sectors.” These water
use sectors include single-family residential, multi-family residential,
commercial, and landscape.
• SB X7-7 Baselines, 2020 Targets, and 2025 Reporting
SB X7-7 required urban water suppliers, including the City, to develop a “2020
Water Use Target” to assist the State of California to achieve the 20%
reduction. The 2020 Water Use Target represents the amount of water each
person should use per day (i.e. gallons per capita per day or “GPCD”) by the
year 2020. The City previously determined its 2020 Water Use Target during
the preparation of its 2015 Plan by completing standardized tables (or the SB
X7-7 Verification Form) to demonstrate compliance with the Water
Conservation Act of 2009. The City’s 2020 Water Use Target was 238 GPCD.
• Normal-Year Water Supply Characterization
Details regarding the City’s groundwater supplies from the Main Basin and
Raymond Basin is provided. Information regarding basin location,
adjudication, management, water levels, water quality, water rights, and
historical production is provided.
• Water Service Reliability and Drought Risk Assessment
The reliability of the City’s water supply sources, including a review of water
supply constraints, is provided in the 2025 UWMP. A single dry year or a five
consecutive year drought period will not compromise the City’s ability to
provide a reliable supply of water to its customers. The City’s Drought Risk
Assessment assumes a five consecutive year drought from FY 2025-26 through
FY 2029-30, and includes a review of water supplies, water uses, and water
supply reliability for each water supply source during this period.
Resolution No. 7702 Adopting the 2025 Urban Water Management Plan
and Water Shortage Contingency Plan
June 16, 2026
Page 4 of 6
• Water Shortage Contingency Plan
The City’s WSCP outlines how the City will respond in the event of a water
supply shortage. The UWMP incorporates this WSCP and details specific
response actions for varying levels of water shortage.
• Demand Management Measures
The City has implemented “Demand Management Measures” to reduce its
water demands and achieve its water use targets, which includes adoption of
an ordinance to prevent water waste.
• Plan Adoption, Submittal, and Implementation
The City has completed all necessary requirements listed by the Department
of Water Resources to ensure full compliance with the California Urban Water
Management Planning Act.
DISCUSSION
Key requirements among the 2025 UWMP is for the City to demonstrate compliance
with Senate Bill X7-7 the Water Conservation Act of 2009, also known as the “20% by
2020” requirement. Enacted in 2009, this legislation called for a statewide 20% per
capita water use reduction in the span of 10 years by 2020. The City previously
determined its 2020 Water Use Target during the preparation of its 2015 UWMP by
completing standardized tables (or the SB X7-7 Verification Form) to demonstrate
compliance with the Water Conservation Act of 2009. The City’s 2020 Water Use
Target was 238 GPCD. The City’s per-capita water use during Fiscal Year 2019-20 was
230 GPCD. The City’s per-capita water use during Fiscal Year 2019-20 met the 2020
Water Use Target. The table below shows the Senate Bill X7-7 2020 target was met:
Resolution No. 7702 Adopting the 2025 Urban Water Management Plan
and Water Shortage Contingency Plan
June 16, 2026
Page 5 of 6
On June 1, 2026, and June 8, 2026, a notice of public hearing for the UWMP was
published in the City’s local adjudicated newspaper. The 2025 UWMP and WSCP are
available for public review on the City website at ArcadiaCA.gov/UWMP and physical
copies are located at the Public Works Services Department. To date, no comments
have been received.
The City’s 2025 UWMP and WSCP have been prepared in accordance with all
legislative requirements and in the format required by the DWR. Therefore, it is
recommended that, upon conclusion of the public hearing, the City Council adopt
Resolution No. 7702 adopting the City’s 2025 Urban Water Management Plan and
Water Shortage Contingency Plan.
ENVIRONMENTAL ANALYSIS
The update to the Urban Water Management Plan is exempt from the California
Environmental Quality Act (“CEQA”), under Section 15282 (v) of the California
Environmental Quality Act Guidelines.
FISCAL IMPACT
There is no fiscal impact in adopting Resolution No. 7702.
RECOMMENDATION
It is recommended that the City Council find that the following resolution is
categorically exempt pursuant to the California Environmental Quality Act (“CEQA”);
and adopt Resolution No. 7702 adopting the City of Arcadia’s 2025 Urban Water
Management Plan and Water Shortage Contingency Plan.
Resolution No. 7702 Adopting the 2025 Urban Water Management Plan
and Water Shortage Contingency Plan
June 16, 2026
Page 6 of 6
Attachments: Resolution No. 7702
2025 Urban Water Management Plan and Water Shortage
Contingency Plan
2025 Urban Water Management Plan Appendices
M AY 2026 FINAL D RAFT
99999.92100\45048348.1
City of Arcadia
2025
Urban Water Management Plan
99999.92100\45048348.1
TABLE OF CONTENTS
Page
i
CHAPTER 1 ............................................................................................................................ 1-1
URBAN WATER MANAGEMENT PLAN INTRODUCTION AND OVERVIEW ............................... 1-1
UPDATED GUIDANCE FOR 2025 URBAN WATER MANAGEMENT PLANS ........................ 1-4
SUBMITTAL TABLES .......................................................................................................... 1-5
INCLUSION OF SUBMITTAL TABLES .................................................................... 1-5
OPTIONAL PLANNING TOOL ............................................................................... 1-6
RECOMMENDED UWMP ORGANIZATION ....................................................................... 1-6
UWMPS IN RELATION TO OTHER EFFORTS ...................................................................... 1-7
SPECIFIC CONSIDERATIONS ................................................................................ 1-7
DEPARTMENT OF WATER RESOURCES’ REVIEW PROCESS .............................................. 1-9
UWMPS AND GRANT OR LOAN ELIGIBILITY ..................................................................... 1-9
TIPS FOR URBAN WATER MANAGEMENT PLAN PREPARES ........................................... 1-10
CHAPTER 2 ............................................................................................................................ 2-1
PLAN PREPARATION ............................................................................................................. 2-1
BASIS FOR PREPARING A PLAN ........................................................................................ 2-2
SUPPLIERS WITH BOTH WHOLESALE AND RETAIL SALES .................................... 2-3
PUBLIC WATER SYSTEMS .................................................................................... 2-4
INDIVIDUAL OR REGIONAL PLANS ................................................................................... 2-5
REGIONAL REPORTING ........................................................................................ 2-5
FISCAL OR CALENDAR YEAR AND UNITS OF MEASURE .................................................... 2-6
FISCAL OR CALENDAR YEAR ................................................................................ 2-6
UNITS OF MEASURE ............................................................................................ 2-6
COORDINATION AND OUTREACH .................................................................................... 2-6
WHOLESALE AND RETAIL COORDINATION ......................................................... 2-7
COORDINATION WITH OTHER AGENCIES AND THE COMMUNITY ..................... 2-7
NOTICE TO CITIES AND COUNTIES ...................................................................... 2-8
SUBMITTAL TABLES .......................................................................................................... 2-9
SUBMITTAL TABLE 2-1: PWSs ............................................................................. 2-9
SUBMITTAL TABLE 2-2: PLAN TYPE IDENTIFICATION ........................................ 2-10
SUBMITTAL TABLE 2-3: SUPPLIER INFORMATION ............................................ 2-11
SUBMITTAL TABLE 2-4: WATER SUPPLIER INFORMATION EXCHANGE ............ 2-12
CHAPTER 3 ............................................................................................................................ 3-1
SERVICE AREA DESCRIPTION ................................................................................................. 3-1
GENERAL DESCRIPTION .................................................................................................... 3-2
SERVICE AREA BOUNDARY MAPS .................................................................................... 3-3
SERVICE AREA CLIMATE ................................................................................................... 3-4
SERVICE AREA POPULATION AND DEMOGRAPHICS ........................................................ 3-6
SERVICE AREA POPULATION ............................................................................... 3-6
OTHER SOCIAL, ECONOMIC, AND DEMOGRAPHIC FACTORS ............................. 3-8
TABLE OF CONTENTS
(Continued)
Page
ii
3-8
LAND USES WITHIN SERVICE AREA .................................................................................. 3-9
SUBMITTAL TABLES ........................................................................................................ 3-10
SUBMITTAL TABLE 3-1: POPULATION - CURRENT AND PROJECTED ................. 3-10
CHAPTER 4 ............................................................................................................................ 4-1
WATER USE CHARACTERIZATION .......................................................................................... 4-1
NON-POTABLE VERSUS POTABLE WATER USE ................................................................ 4-2
PAST, CURRENT, AND PROJECTED WATER USE BY SECTOR ............................................. 4-2
WATER-USE SECTORS LISTED IN WATER CODE .................................................. 4-4
OPTIONAL WATER-USE SECTORS IN ADDITION TO THOSE LISTED IN
WATER CODE ...................................................................................................... 4-6
PAST WATER USE ................................................................................................ 4-6
CURRENT WATER USE ......................................................................................... 4-6
PROJECTED WATER USE ...................................................................................... 4-7
DISTRIBUTION SYSTEM WATER LOSS ............................................................................. 4-24
PREVIOUS FIVE YEARS DISTRIBUTION SYSTEM LOSSES .................................... 4-24
PROGRESS TOWARD MEETING THE WATER LOSS PERFORMANCE
STANDARD ........................................................................................................ 4-25
SUBMITTAL TABLES ........................................................................................................ 4-26
TABLE 4-1: TOTAL USES FOR POTABLE AND NON-POTABLE WATER-
ACTUAL ............................................................................................................. 4-27
TABLE 4-2: TOTAL USES OF POTABLE AND NON-POTABLE WATER—
PROJECTED ........................................................................................................ 4-28
TABLE 4-3: INCLUSION IN WATER-USE PROJECTIONS ...................................... 4-29
OPTIONAL TABLE 4-4: PASSIVE WATER SAVINGS PROJECTION ........................ 4-29
TABLE 4-5: WATER LOSS AUDIT REPORTING .................................................... 4-30
TABLE 4-6: PROGRESS TOWARD 2028 WATER LOSS STANDARD ..................... 4-31
CHAPTER 5 ............................................................................................................................ 5-1
SB X7-7 BASELINE, 2020TARGETS, 2025 REPORTING ............................................................. 5-1
REPORTING REQUIREMENTS FOR WHOLESALE SUPPLIERS ............................................. 5-2
REPORTING REQUIREMENTS FOR RETAIL SUPPLIERS ...................................................... 5-2
SUPPLIER WAS NOT AN URBAN RETAIL WATER SUPPLIER ................................. 5-3
SUPPLIER MET 2020 TARGET IN 2020 ................................................................. 5-3
SUPPLIER DID NOT MEET 2020 TARGET IN 2020—NO CHANGE TO
SERVICE AREA ..................................................................................................... 5-4
SUPPLIER DID NOT MEET 2020 TARGET—CHANGE TO SERVICE AREA
SINCE 2020 .......................................................................................................... 5-4
FUNDING ELIGIBILITY .......................................................................................... 5-4
NEXUS TO STATE WATER BOARD URBAN WATER-USE OBJECTIVES (NOT
REQUIRED FOR UWMPs) ..................................................................................... 5-5
TABLE OF CONTENTS
(Continued)
Page
iii
SUBMITTAL TABLES .......................................................................................................... 5-7
CHAPTER 6 ............................................................................................................................ 6-1
NORMAL YEAR WATER SUPPLY CHARACTERIZATION ............................................................ 6-1
WATER SUPPLY ANALYSIS OVERVIEW ............................................................................. 6-2
SPECIFIC ANALYSIS APPLICABLE TO ALL WATER SUPPLY SOURCES .................... 6-4
SPECIAL CONSIDERATIONS ................................................................................. 6-6
WATER SUPPLY CHARACTERIZATION ............................................................................... 6-7
PURCHASED OR IMPORTED WATER ................................................................... 6-7
GROUNDWATER................................................................................................ 6-10
SURFACE WATER ............................................................................................... 6-38
STORMWATER .................................................................................................. 6-39
WASTEWATER AND RECYCLED WATER............................................................. 6-39
DESALINATED WATER OPPORTUNITIES ............................................................ 6-46
WATER EXCHANGES AND TRANSFERS .............................................................. 6-47
SUPPLY FROM STORAGE ................................................................................... 6-49
OTHER ............................................................................................................... 6-49
FUTURE WATER PROJECTS ................................................................................ 6-49
ENERGY USE ................................................................................................................... 6-50
SUBMITTAL TABLES ........................................................................................................ 6-54
TABLE 6-1: GROUNDWATER VOLUME PUMPED ............................................... 6-54
TABLE 6-2: WASTEWATER COLLECTED WITHIN SERVICE AREA ........................ 6-55
TABLE 6-3: WASTEWATER TREATMENT AND OUTCOMES WITHIN UWMP
SERVICE AREA ................................................................................................... 6-56
TABLE 6-4: RECYCLED WATER DIRECT BENEFICIAL USES WITHIN SERVICE
AREA .................................................................................................................. 6-57
TABLE 6-5: 2020 UWMP RECYCLED WATER-USE PROJECTION
COMPARED TO 2025 ACTUAL ........................................................................... 6-58
TABLE 6-6: METHODS TO ENCOURAGE FUTURE RECYCLED WATER USE ......... 6-59
TABLE 6-7: EXPECTED FUTURE WATER SUPPLY PROJECTS OR PROGRAMS ..... 6-60
TABLE 6-8: WATER SUPPLIES—ACTUAL ............................................................ 6-60
OPTIONAL TABLE 6-8DS: SOURCE DESALINATION BY SUPPLIER ...................... 6-62
TABLE 6-9: WATER SUPPLIES—PROJECTED ...................................................... 6-63
CHAPTER 7 ............................................................................................................................ 7-1
WATER SERVICE RELIABILITY AND DROUGHT RISK ASSESSMENT .......................................... 7-1
CONSTRAINTS ON WATER SOURCES CONSIDERATIONS .................................................. 7-2
SERVICE RELIABILTY - CONSTRAINTS ON WATER SOURCES ............................... 7-3
WATER SERVICE RELIABILITY ASSESSMENT ..................................................................... 7-4
WSRA YEAR-TYPE CHARACTERIZATION .............................................................. 7-8
WSRA SUPPLY AND DEMAND COMPARISON ..................................................... 7-9
WSRA DESCRIPTION OF MANAGEMENT TOOLS AND OPTIONS ....................... 7-11
TABLE OF CONTENTS
(Continued)
Page
iv
DROUGHT RISK ASSESSMENT ........................................................................................ 7-13
DRA, DATA, METHODS, AND BASIS FOR WATER SHORTAGE CONDITIONS ...... 7-14
DRA INDIVIDUAL WATER SOURCE RELIABILITY ................................................ 7-16
DRA TOTAL WATER SUPPLY AND USE COMPARISON ....................................... 7-19
OPTIONAL PLANNING TOOL WORKBOOK ...................................................................... 7-19
SUBMITTAL TABLES ........................................................................................................ 7-20
OPTIONAL TABLE 7-1: BASIS OF WATER-YEAR DATA (WSRA) .......................... 7-20
TABLE 7-2: NORMAL-YEAR SUPPLY AND USE COMPARISON ............................ 7-21
TABLE 7-3: SINGLE-DRY-YEAR SUPPLY AND USE COMPARISON ....................... 7-22
TABLE 7-4: MULTIPLE DRY YEARS SUPPLY AND USE COMPARISON ................. 7-23
TABLE 7-5: FIVE-YEAR DROUGHT RISK ASSESSMENT ........................................ 7-24
CHAPTER 8 ............................................................................................................................ 8-1
WATER SHORTAGE CONTINGENCY PLAN .............................................................................. 8-1
WATER SUPPLY RELIABILITY ANALYSIS ............................................................................ 8-3
ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES ............................ 8-4
DECISION-MAKING PROCESS .............................................................................. 8-5
DATA AND METHODOLOGIES ............................................................................. 8-6
SIX STANDARD WATER SHORTAGE LEVELS ...................................................................... 8-8
SHORTAGE RESPONSE ACTIONS ...................................................................................... 8-9
SUPPLY AUGMENTATION .................................................................................. 8-10
DEMAND REDUCTION ....................................................................................... 8-12
OPERATIONAL CHANGES .................................................................................. 8-16
ADDITIONAL MANDATORY RESTRICTIONS ....................................................... 8-17
EMERGENCY RESPONSE PLAN .......................................................................... 8-17
SEISMIC RISK ASSESSMENT AND MITIGATION PLAN ........................................ 8-18
SHORTAGE RESPONSE ACTION EFFECTIVENESS ............................................... 8-21
COMMUNICATION PROTOCOLS .................................................................................... 8-23
COMPLIANCE AND ENFORCEMENT ............................................................................... 8-24
LEGAL AUTHORITIES....................................................................................................... 8-26
FINANCIAL CONSEQUENCES OF WSCP .......................................................................... 8-27
MONITORING AND REPORTING ..................................................................................... 8-28
WSCP REFINEMENT PROCEDURES ................................................................................. 8-29
SPECIAL WATER FEATURE DISTINCTION ........................................................................ 8-30
PLAN ADOPTION, SUBMITTAL, AVAILABILITY, AND AMENDMENT PROCEDURES......... 8-31
RESOURCES AND REFERENCES....................................................................................... 8-32
SUBMITTAL TABLES ........................................................................................................ 8-32
TABLE 8-1: CROSS REFERENCE FOR STANDARD VS. SUPPLIER SHORTAGE
LEVELS ............................................................................................................... 8-33
TABLE 8-2: SUPPLY AUGMENTATION AND OTHER ACTION .............................. 8-34
TABLE 8-3: DEMAND-REDUCTION ACTIONS ..................................................... 8-35
TABLE OF CONTENTS
(Continued)
Page
v
CHAPTER 9 ............................................................................................................................ 9-1
DEMAND MANAGEMENT MEASURES ................................................................................... 9-1
DEMAND MANAGEMENT MEASURES FOR RETAIL SUPPLIERS ........................................ 9-2
IMPLEMENTATION OVER THE PAST FIVE YEARS ................................................. 9-2
IMPLEMENTATION TO ACHIEVE WATER USE TARGETS ...................................... 9-5
REQUIRED DEMAND MANAGEMENT MEASURES ............................................... 9-5
DEMAND MANAGEMENT MEASURES FOR WHOLESALE SUPPLIERS ............................. 9-12
CHAPTER 10 ........................................................................................................................ 10-1
PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION ..................................................... 10-1
PLAN COMPLETION TIMELINE ....................................................................................... 10-2
NOTICE OF PLAN PREPARATION .................................................................................... 10-2
NOTICE OF PUBLIC HEARING ......................................................................................... 10-3
PUBLIC HEARING AND ADOPTION ................................................................................. 10-4
PLAN SUBMITTAL ........................................................................................................... 10-5
SUBMITTING A UWMP AND WATER SHORTAGE CONTINGENCY PLAN TO
DWR .................................................................................................................. 10-6
ELECTRONIC DATA SUBMITTAL......................................................................... 10-6
SUBMITTING A UWMP, INCLUDING WSCP, TO THE CALIFORNIA STATE
LIBRARY ............................................................................................................. 10-7
SUBMITTING A UWMP TO CITIES AND COUNTIES ............................................ 10-7
PUBLIC AVAILABILITY ..................................................................................................... 10-8
NOTIFICATION TO PUBLIC UTILITIES COMMISSION ....................................................... 10-8
PLAN IMPLEMENTATION ............................................................................................... 10-9
AMENDING AN ADOPTED UWMP OR WATER SHORTAGE CONTINGENCY PLAN .......... 10-9
AMENDING A UWMP OR WSCP ........................................................................ 10-9
AMENDING A WATER SHORTAGE CONTINGENCY PLAN ................................ 10-10
CALIFORNIA DEPARTMENT OF WATER RESOURCES REVIEW OF SUBMITTED
PLANS ........................................................................................................................... 10-10
SUBMITTAL TABLES ...................................................................................................... 10-11
SUBMITTAL TABLE 10-1: NOTIFICATION TO CITIES AND COUNTIES ............... 10-11
TABLE OF CONTENTS
(Continued)
vi
LIST OF TABLES
Table 2-1 Public Water Systems ................................................................................................................... 2-9
Table 2-2 Plan Type Identification .............................................................................................................. 2-10
Table 2-3 Supplier Information ................................................................................................................... 2-11
Table 2-4 Water Supplier Information Exchange........................................................................................ 2-1 2
Table 3-1: Population - Current and Projected ............................................................................................ 3-10
Table 4-1 Total Uses for Potable and Non-Potable Water - Actual ............................................................ 4-27
Table 4-2 Total Uses for Potable and Non-Potable Water - Projected ....................................................... 4-28
Table 4-3 Inclusion in Water-Use Projections ............................................................................................. 4-29
Table 4-4 Passive Savings Projection .......................................................................................................... 4-29
Table 4-5 Water Loss Audit Reporting ........................................................................................................ 4-30
Table 4-6 Progress Toward 2028 Water Loss Standard .............................................................................. 4-31
Table 5-1 SB X7-7 2020 Target Progress ....................................................................................................... 5-7
Table 6-1 Groundwater Volume Pumped ................................................................................................... 6 -54
Table 6-2 Wastewater Collected Within Service Area ................................................................................ 6-55
Table 6-3 Wastewater Treatment and Outcomes Within UWMP Service Area ......................................... 6-56
Table 6-4 Recycled Water Direct Beneficial Uses Within Service Area ...................................................... 6-57
Table 6-5 2020 UWMP Recycled Water-Use Projection Compared to 2025 Actual .................................. 6-58
Table 6-6 Methods to Encourage Future Recycled Water Use ................................................................... 6-59
Table 6-7 Expected Future Water Supply Projects or Programs ................................................................ 6-60
Table 6-8 Water Supplies—Actual .............................................................................................................. 6-62
Table 6-9 Water Supplies—Projected ......................................................................................................... 6-63
Table 7-1 Basis of Water-Year Data (Reliability Assessment) ..................................................................... 7-20
Table 7-2 Normal-Year Supply and Use Comparison .................................................................................. 7-21
Table 7-3 Single-Dry-Year Supply and Use Comparison ............................................................................. 7-22
Table 7-4 Multiple Dry Years Supply and Use Comparison ........................................................................ 7-23
Table 7-5 Five-Year Drought Risk Assessment ............................................................................................ 7-24
Table 8-1 Cross-Reference for Standard vs. Supplier Shortage Levels ....................................................... 8-33
Table 8-2 Supply Augmentation and Other Actions ................................................................................... 8-34
Table 8-3 Demand-Reduction Actions ........................................................................................................ 8-35
Table 10-1 Notification to Cities and Counties ........................................................................................... 10-11
TABLE OF CONTENTS
(Continued)
vii
LIST OF FIGURES
Figure 1 Water Service Area
Figure 2 Water Service Area and City Boundaries
Figure 3 Main Basin Location
Figure 4 Raymond Basin Location
TABLE OF CONTENTS
(Continued)
viii
LIST OF APPENDICES
Appendix A DWR Standardized Tables
Appendix B Completed Plan Checklist
Appendix C Demonstration of Reduced Imported Water Reliance
Appendix D Notification Letters and Notices of Public Hearing
Appendix E Climate Change Considerations (Cal-Adapt Data)
Appendix F Long Beach Judgment
Appendix G Main Basin Judgment
Appendix H Raymond Basin Adjudication
Appendix I Draft Recycled Water Feasibility Study
Appendix J Water Conservation Plan
Appendix K City of Arcadia Local Hazard Mitigation Plan
Appendix L Los Angeles County All-Hazard Mitigation Plan
Appendix M Water Rate Structure
Appendix N Ordinance 2327 and Resolution 7430
Appendix O Resolution Adopting 2025 UWMP and WSCP
TABLE OF CONTENTS
(Continued)
ix
LIST OF ACRONYMS
AB Assembly Bill
AF Acre-feet
AFY Acre-feet per year
Annual Assessment Annual Water Supply and Demand Assessment
AWWA American Water Works Association
BPOU Baldwin Park Operable Unit
CECs Constituents of emerging concern
Central District Central Basin Municipal Water District
CII Commercial, Industrial, and Institutional
CIMIS California Irrigation Management Information System
City City of Arcadia
CWC California Water Code
CWEA Cooperative Water Exchange Agreement
DACs Disadvantaged Communities
DMMs Demand Management Measures
DOF Department of Finance
DPW Department of Public Works
DRA Drought Risk Assessment
DWR Department of Water Resources
ERP Emergency Response Plan
ETo Evapotranspiration
FY Fiscal Year
GCMs General Circulation Models
GIS Geographical Information Systems
GPCD Gallons per capita per day
GSP Groundwater Sustainability Plan
HERO Home Energy Renovation Opportunity
JPL Jet Propulsion Laboratory
JWPCP Joint Water Pollution Control Plant
Key Well Baldwin Park Key Well
kWh Kilowatt Hours
LACSD Los Angeles County Sanitation District
LAEEF Los Angeles County Environmental Education Fair
LARWQCB Los Angeles Regional Water Quality Control Board
M&I Municipal and Industrial
Main Basin Main San Gabriel Basin
MGD Million Gallons Per Day
mg/l Milligrams per liter
MSL Mean seal level
MWD Metropolitan Water District of Southern California
NASA National Aeronautics and Space Administration
NCP National Contingency Plan
NDMA N-nitrosodimethylamine
OSY Operating Safe Yield
TABLE OF CONTENTS
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x
Plan Urban Water Management Plan
PCE Perchloroethylene
PHET Premium High Efficiency Toilet
RCP Representative Concentration Pathway
RDA Main Basin Resource Development Assessment
RDA II Main Basin Water Resource Development Assessment for
Stormwater Augmentation Program
RDM Robust Decision Making
ROD Records of Decision
RRA Risk and Resilience Assessment
San Gabriel District San Gabriel Valley Municipal Water District
SB Senate Bill
SCAG Southern California Association of Governments
SCE Southern California Edison
SGMA Sustainable Groundwater Management Act of 2014
SJCWRP San Jose Creek Water Reclamation Plant
SNMP San Gabriel Valley Salt and Nutrient Management Plan
SWP State Water Project
SWRCB-DDW State Water Resources Control Board - Division of Drinking Water
TCE Trichloroethylene
TDS Total Dissolved Solids
Three Valleys District Three Valleys Municipal Water District
Upper Water Upper San Gabriel Valley Municipal Water District
USEPA U.S. Environmental Protection Agency
UWMP Urban Water Management Plan
VOCs Volatile Organic Compounds
WNWRP Whittier Narrows Water Reclamation Plant
WQA Water Quality Authority
WRCC Western Regional Climate Center
WRD Water Replenishment District of Southern California
WSAP
WSRA
Water Supply Allocation Plan
Water Supply Reliability Assessment
WSCP Water Shortage Contingency Plan
WUCA Water Utility Climate Alliance
WUE Water Use Efficiency
TABLE OF CONTENTS
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2025 Urban Water Management Plan
City of Arcadia Page 1-1
CHAPTER 1
URBAN WATER MANAGEMENT PLAN INTRODUCTION AND OVERVIEW
LAY DESCRIPTION - INTRODUCTION
An urban water supplier is defined (pursuant to Section 10617 of the California Water
Code1) as “a supplier, either publicly or privately owned, providing water for municipal
purposes either directly or indirectly to more than 3,000 customers or supplying more than
3,000 acre-feet of water annually. An urban water supplier includes a supplier or
contractor for water, regardless of the basis of right, which distributes or sells for ultimate
resale to customers.”
The City of Arcadia (City) is classified as an urban water supplier because it serves more
than 3,000 customers (i.e. individual metered accounts) and it supplies more than 3,000
acre-feet of water annually to its customers for municipal purposes.
In accordance with the “Urban Water Management Planning Act”, which was enacted by
the California Legislature in 1983, every urban water supplier (including the City) is
required to prepare and adopt an Urban Water Management Plan (UWMP), periodically
review its UWMP, and incorporate updated and new information into an updated UWMP
at least once every five years.
The City’s most recent update was its 2020 UWMP (or 2020 Plan) which was submitted
to, and approved by, the California Department of Water Resources (DWR). Urban water
suppliers (including the City) are required to complete and submit their 2025 UWMPs to
DWR by July 1st, 2026.
1 References to CWC Sections in this 2025 UWMP were obtained from https://leginfo.legislature.ca.gov/
2025 Urban Water Management Plan
City of Arcadia Page 1-2
The current requirements for preparing the UWMP are included in California Water Code
(CWC) Sections 10608 through 10657. The City’s 2025 UWMP (or 2025 Plan) was
prepared consistent with the CWC and the recommended organization provided in
DWR’s Final “Urban Water Management Plan Guidebook 2025” (Final 2025
UWMP Guidebook), dated January 2026.
The UWMP provides urban water suppliers (including the City) with a reliable
management action plan for long-term resource planning to ensure adequate water
supplies are available to meet existing and future water supply needs. In addition, the
2025 Plan incorporates water supply reliability determinations resulting from potential
prolonged drought, regulatory revisions, and/or changing climatic conditions.
The City’s 2025 Plan consists of the following Chapters:
Chapter 1 Urban Water Management Plan Introduction and Overview
Chapter 2 Plan Preparation
Chapter 3 Service Area Description
Chapter 4 Water Use Characterization
Chapter 5 SB X7-7 Baselines, 2020 Targets, and 2025 Reporting
Chapter 6 Normal-Year Water Supply Characterization
Chapter 7 Water Service Reliability and Drought Risk Assessment
Chapter 8 Water Shortage Contingency Plan
Chapter 9 Demand Management Measures
Chapter 10 Plan Adoption, Submittal, and Implementation
A lay description is presented at the beginning of each of these Chapters.
2025 Urban Water Management Plan
City of Arcadia Page 1-3
LAY DESCRIPTION – CHAPTER 1
URBAN WATER MANAGEMENT PLAN INTRODUCTION AND OVERVIEW
Chapter 1 (Urban Water Management Plan Introduction and Overview) of the City’s 2025
Plan discusses and provides the following:
x An overall lay description of the 2025 Plan, including California Water Code and
Urban Water Management Plan Act requirements, is provided. The City is required
to prepare an Urban Water Management Plan.
x The City’s 2025 Plan was prepared consistent with the recommended organization
provided in DWR’s Final “Urban Water Management Plan Guidebook 2025”,
dated January 2026. A description regarding the organization of the 2025 Plan,
including a summary of each Chapter, is provided. The City’s Water Shortage
Contingency Plan (discussed in Chapter 8) is also included in the 2025 Plan.
x The 2025 Plan incorporates DWR’s water use and supply tables (standardized
Submittal Tables) for the reporting and submittal of UWMP data. Relevant
Submittal Tables are included at the end of each Chapter in this 2025 Plan and in
Appendix A.
x The City’s coordination efforts with other planning agencies are discussed,
including coordination efforts with Upper San Gabriel Valley Municipal Water
District and the Southern California Association of Governments
x The City’s eligibility to receive grants and loans administered by the State of
California and/or DWR, as a result of preparing the 2025 Plan, is discussed.
x Information is provided which demonstrates the City’s prior, continued, and
projected reduction on imported water supplies obtained (either directly or
indirectly) from the Sacramento-San Joaquin Delta (Delta). The City has reduced
its reliance on the imported water supplies for Fiscal Year 2014-15, Fiscal Year
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City of Arcadia Page 1-4
2019-2020, and Fiscal Year 2024-25. In addition, the City is projected to continue
reducing its reliance on the imported water supplies through Fiscal Year 2049-50.
x The checklist developed by DWR and used by the City to incorporate the specific
UWMP requirements is discussed. The completed checklist is provided in
Appendix B.
UPDATED GUIDANCE FOR 2025 URBAN WATER MANAGEMENT PLANS
The City’s 2025 Plan was prepared consistent with the recommended organization
provided in DWR’s Final “Urban Water Management Plan Guidebook 2025”,
dated January 2026. DWR provided the following updated guidance for the preparation
of the 2025 Plans (in comparison to the preparation of the 2020 Plans):
x There have been minor changes to the Water Code since the 2020 Plans were
submitted; primarily, several definitions have been added (none of these change
the requirements for 2025 Plans).
x DWR and the State Water Resources Control Board are using the same criteria
to determine when a water supplier with multiple Public Water Systems is
considered an Urban Water Supplier subject to UWMP requirements.
x DWR has updated its submittal tables to reflect the current reporting year, improve
accuracy of reporting, and more clearly identify information required by Water
Code and optional information.
x There has been no change to the Water Code regarding water loss standard
reporting since the 2020 Plans were submitted. However, water suppliers can
report progress toward compliance with their 2028 Water Loss Standard in the
2025 Plans (see Table 4-6).
x The State Water Resources Control Board has adopted regulations for the use of
direct potable reuse (DPR) since the 2020 Plan reporting. To allow for reporting
2025 Urban Water Management Plan
City of Arcadia Page 1-5
of DPR, minor changes have been made to the supply and demand tables in the
2025 Plans.
x While projections for lower-income housing were required in the 2020 Plans,
additional guidance has been provided for optional reporting of the method used
to project water use for lower-income housing.
x In previous years, the guidance for reporting water placed into storage did not
differentiate between long-term storage (i.e., water placed into storage one year
but extracted in a future year) and short-term storage (i.e., water that is placed
into storage and extracted the same year). When a water supplier reports water
placed into storage and then reports it was retrieved in the same year (short-term
storage) it can cause a double counting error. Additional guidance has been
provided recommending that water suppliers do not report water into and out of
short-term storage.
SUBMITTAL TABLES
INCLUSION OF SUBMITTAL TABLES
CWC 10644.
(a)(2) The plan, or amendments to the plan, submitted to the department … shall include any
standardized forms, tables, or displays specified by the department.
The City’s 2025 Plan includes the completion of DWR’s standardized Submittal
Tables for the reporting and submittal of UWMP data. Relevant Submittal Tables are
included at the end of each Chapter in this 2025 Plan. In addition, all Submittal Tables
are provided collectively in Appendix A.
2025 Urban Water Management Plan
City of Arcadia Page 1-6
OPTIONAL PLANNING TOOL
DWR has created an optional “Planning Tool Worksheet” for water suppliers to review
and assess monthly water use trends. DWR has deemed the tool as optional and the
City is not required by DWR to use the tool.
RECOMMENDED UWMP ORGANIZATION
The City’s 2025 Urban Water Management Plan (2025 Plan) was prepared consistent
with the recommended organization provided in DWR’s Final “Urban Water Management
Plan Guidebook 2025” (Final 2025 UWMP Guidebook), dated January 2026. The City’s
2025 Plan consists of the following Chapters:
Chapter 1 Urban Water Management Plan Introduction and Overview
Chapter 2 Plan Preparation
Chapter 3 Service Area Description
Chapter 4 Water Use Characterization
Chapter 5 SB X7-7 Baselines, 2020 Targets, and 2025 Reporting
Chapter 6 Normal-Year Water Supply Characterization
Chapter 7 Water Service Reliability and Drought Risk Assessment
Chapter 8 Water Shortage Contingency Plan
Chapter 9 Demand Management Measures
Chapter 10 Plan Adoption, Submittal, and Implementation
Pursuant to CWC requirements, the City’s 2025 Plan incorporates DWR’s water use and
supply tables (standardized Submittal Tables) for the reporting and submittal of UWMP
data. DWR’s standardized Submittal Tables are provided within the body of the 2025
Plan text as well as in Appendix A.
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City of Arcadia Page 1-7
The City’s 2025 Plan also provides supporting documents (appendices) including
notification letters of the Plan update, public notice of the Plan hearing, and adoption
resolution from the City’s governing body. Further discussions regarding these supporting
documents are provided within the individual Chapters of the City’s 2025 Plan.
UWMPS IN RELATION TO OTHER EFFORTS
The City is a sub-agency of Upper San Gabriel Valley Municipal Water District (Upper
Water), a wholesale water agency. Upper Water prepared a 2025 Plan which is
incorporated in the City’s 2025 UWMP by reference. In addition, the City provided its 2025
UWMP to Upper Water which includes water use projections in five-year increments for
a normal year, a single dry year, and a five consecutive year drought over the next 25
years.
SPECIFIC CONSIDERATIONS
1.4.1.1 DEMONSTRATION OF CONSISTENCY WITH THE DELTA PLAN
FOR PARTICIPANTS IN COVERED ACTIONS
Pursuant to DWR, an urban water supplier that anticipates participating in or receiving
water from a proposed project (or “covered action”) such as a multi-year water transfer,
conveyance facility, or new diversion that involves transferring water through, exporting
water from, or using water in the Sacramento-San Joaquin Delta (Delta) should provide
information in their Plans for use in demonstrating consistency with Delta Plan Policy WR
P1, “Reduce Reliance on the Delta Through Improved Regional Water Self-Reliance”. In
addition, pursuant to California Code of Regulations, Title 23, § 5003:
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City of Arcadia Page 1-8
(c)(1) Water suppliers that have done all of the following are contributing to
reduced reliance on the Delta and improved regional self-reliance and are
therefore consistent with this policy:
(A) Completed a current Urban or Agricultural Water Management Plan
(Plan) which has been reviewed by the California Department of Water
Resources for compliance with the applicable requirements of Water Code
Division 6, Parts 2.55, 2.6, and 2.8;
(B) Identified, evaluated, and commenced implementation, consistent with
the implementation schedule set forth in the Plan, of all programs and
projects included in the Plan that are locally cost effective and technically
feasible which reduce reliance on the Delta; and
(C) Included in the Plan, commencing in 2015, the expected outcome for
measurable reduction in Delta reliance and improvement in regional self-
reliance. The expected outcome for measurable reduction in Delta reliance
and improvement in regional self-reliance shall be reported in the Plan as
the reduction in the amount of water used, or in the percentage of water
used, from the Delta watershed. For the purposes of reporting, water
efficiency is considered a new source of water supply, consistent with Water
Code section 1011(a).
The City has reduced its reliance on the imported water supplies for FY 2014-15, FY
2019-20, and FY 2024-25. In addition, the City is projected to continue reducing its
reliance on the imported water supplies through FY 2049-50. A further discussion which
demonstrates the City’s measurable reduction in imported water reliance and
improvement in regional self-reliance is provided in Appendix C.
1.4.1.2 PERMITTING FOR OCEAN DESALINATION PROJECTS
The City is currently not considering the development of a desalinated water project.
However, as discussed in Section 6.2.6, there may be opportunities for use of desalinated
ocean water as a potential water supply source in the future, if needed, through
coordination with other agencies that have ocean desalination programs.
2025 Urban Water Management Plan
City of Arcadia Page 1-9
DEPARTMENT OF WATER RESOURCES’ REVIEW PROCESS
Section 10.5 discusses the process for a water supplier to submit the completed 2025
Plan to DWR, including electronic submittal through DWR’s online Water Use Efficiency
Data (WUEdata) portal. DWR will subsequently review the 2025 Plans to ensure that
they address the California Water Code requirements. Following DWR’s review, water
suppliers will be notified of the results of the review via a formal review letter. These
review letters will also be available to the public on DWR’s WUEdata portal. In cases
where DWR finds that a Plan does not properly address item(s) in the Water Code,
DWR will reach out to the water supplier to discuss needed corrections and correction
procedures.
UWMPS AND GRANT OR LOAN ELIGIBILITY
CWC 10608.56.
(a) On and after July 1, 2016, an urban retail water supplier is not eligible for a water grant or loan
awarded or administered by the state unless the supplier complies with this part.
(c) Notwithstanding subdivision (a), the department shall determine that an urban retail water
supplier is eligible for a water grant or loan even though the supplier has not met the per capita
reductions required pursuant to Section 10608.24, if the urban retail water supplier has
submitted to the department for approval a schedule, financing plan, and budget, to be included
in the grant or loan agreement, for achieving the per capita reductions. The supplier may
request grant or loan funds to achieve the per capita reductions to the extent the request is
consistent with the eligibility requirements applicable to the water funds.
(e) Notwithstanding subdivision (a), the department shall determine that an urban retail water
supplier is eligible for a water grant or loan even though the supplier has not met the per capita
reductions required pursuant to Section 10608.24, if the urban retail water supplier has
submitted to the department for approval documentation demonstrating that its entire service
area qualifies as a disadvantaged community.
(f) The department shall not deny eligibility to an urban retail water supplier or agricultural water
supplier in compliance with the requirements of this part and Part 2.8 (commencing with Section
10800), that is participating in a multiagency water project, or an integrated regional water
2025 Urban Water Management Plan
City of Arcadia Page 1-10
management plan, developed pursuant to Section 75026 of the Public Resources Code, solely
on the basis that one or more of the agencies participating in the project or plan is not
implementing all of the requirements of this part or Part 2.8 (commencing with Section 10800).
CWC 10656.
An urban water supplier is not eligible for a water grant or loan awarded or administered by the
state unless the urban water supplier complies with this part.
California Code of Regulations Title 23 Division 2 Chapter 5.1 Article 1, Section 596.1
(b)(2) “disadvantaged community” means a community with a median household income that is
less than 80 percent of the statewide annual median household income.
Pursuant to DWR’s Final 2025 UWMP Guidebook:
“For a Supplier to be eligible for any water grant or loan administered by DWR, the
Supplier must have a current UWMP on file that has been determined by DWR to
address the requirements of the Water Code. A current UWMP must also be maintained
by the Supplier throughout the term of any grant or loan administered by DWR. A
UWMP may also be required to be eligible for other State funding, depending on the
conditions that are specified in the funding guidelines. Suppliers are encouraged to
seek guidance on the specifics of any State funding source from the respective funding
agencies.”
The City’s 2025 UWMP has been prepared to meet eligibility requirements for grants and
loans administered by the State and/or DWR.
TIPS FOR URBAN WATER MANAGEMENT PLAN PREPARERS
The City’s 2025 Plan (which includes the City’s 2025 Water Shortage Contingency Plan
(WSCP)) is considered an update to the City’s 2020 UWMP. However, the 2025 Plan
2025 Urban Water Management Plan
City of Arcadia Page 1-11
and the WSCP are considered stand-alone documents. As discussed in Section 1.3, the
City’s 2025 Plan was prepared consistent with the recommended organization provided
in DWR’s Final 2025 UWMP Guidebook. The City’s 2025 Plan was also prepared based
on the tips provided in DWR’s Final 2025 UWMP Guidebook including the use of
information from previous Plans and following the required Plan notification and adoption
process.
In addition, a checklist of specific UWMP requirements is included in Appendix B. The
checklist includes the page number where the required elements are addressed to assist
in DWR’s review of the submitted Plan.
2025 Urban Water Management Plan
City of Arcadia Page 2-1
CHAPTER 2
PLAN PREPARATION
LAY DESCRIPTION – CHAPTER 2
PLAN PREPARATION
Chapter 2 (Plan Preparation) of the City’s 2025 Plan discusses and provides the following:
x The basis for preparing an Urban Water Management Plan is provided. The City
is required to prepare the 2025 Plan because it is an “urban water supplier” (the
City serves more than 3,000 customers and it supplies more than 3,000 acre-feet
of water annually to its customers for municipal purposes)
x The City is a “Public Water System” and is regulated by the State Water Resources
Control Board - Division of Drinking Water. The City’s Public Water System number
is provided in Table 2-1.
x The City’s Plan has been prepared as an “individual” plan rather than a “regional”
plan in an effort to provide information specific to the City to best inform its
employees, management and customers.
x Information presented in the City’s 2025 Plan is provided on “fiscal year” basis
which is from July 1 through June 30 of the following year.
x Water quantities presented in the City’s 2025 Plan are provided on an “acre-foot”
basis.
x The City’s coordination and outreach efforts with wholesale water agencies, other
retail water agencies, and the community are described. The City coordinated the
preparation of its 2025 Plan with the cities of Monrovia, Pasadena, and Sierra
Madre, California American Water Company, Golden State Water Company, Main
2025 Urban Water Management Plan
City of Arcadia Page 2-2
San Gabriel Basin Watermaster, San Gabriel Valley Water Company, Sunny Slope
Water Company, Upper Water, and Los Angeles County.
x The City’s notification process to the cities and county within which the City
provides water supplies to is discussed.
As discussed in Section 1.3, the City’s 2025 Plan was prepared consistent with the
recommended organization provided in DWR’s Final 2025 UWMP Guidebook.
Pursuant to CWC requirements, the City’s 2025 Plan incorporates DWR’s water use and
supply tables (standardized Submittal Tables) for the reporting and submittal of UWMP
data.
BASIS FOR PREPARING A PLAN
CWC 10617.
"Urban water supplier" means a supplier, either publicly or privately owned, providing water for
municipal purposes either directly or indirectly to more than 3,000 customers or supplying more
than 3,000 acre-feet of water annually. An urban water supplier includes a supplier or contractor
for water, regardless of the basis of right, which distributes or sells for ultimate resale to customers.
This part applies only to water supplied from public water systems subject to Chapter 4
(commencing with Section 116275) of Part 12 of Division 104 of the Health and Safety Code.
CWC 10618.12.
(t) “Urban retail water supplier” means a water supplier, either publicly or privately owned, that
directly provides potable municipal water to more than 3,000 end users or that supplies more
than 3,000 acre-feet of potable water annually at retail for municipal purposes.
(w) “Urban wholesale water supplier” means a water supplier, either publicly or privately owned,
that provides more than 3,000 acre- feet of water annually at wholesale for potable municipal
purposes.
CWC 10620.
2025 Urban Water Management Plan
City of Arcadia Page 2-3
(b) Every person that becomes an urban water supplier shall adopt an urban water management
plan within one year after it has become an urban water supplier.
CWC 10621.
(a) Each urban water supplier shall update its plan at least once every five years on or before July
1, in years ending in six and one, incorporating updated and new information from the five
years preceding each update.
The City’s 2025 Plan was prepared in accordance with the UWMP Act which was
established in 1983. The UWMP Act requires every “urban water supplier” to prepare
and adopt a Plan, to periodically review its Plan at least once every five years and make
any amendments or changes which are indicated by the review. An “Urban Water
Supplier” is defined as a supplier, either publicly or privately owned, providing water for
municipal purposes either directly or indirectly to more than 3,000 customers or supplying
more than 3,000 acre-feet of water annually.
Section 10621(a) of the CWC states, “Each urban water supplier shall update its plan at
least once every five years on or before July 1, in years ending in six and one,
incorporating updated and new information from the five years preceding each update”.
As a result, DWR requires the 2025 Plans be submitted by July 1, 2026.
The City is an “urban water supplier” pursuant to Section 10617 of the CWC and directly
serves potable water to more than 3,000 customers and supplies more than 3,000 acre-
feet per year (AFY) at retail for municipal purposes. The City’s 2025 Plan is an update to
the City’s 2020 Plan.
SUPPLIERS WITH BOTH WHOLESALE AND RETAIL SALES
The City is a retail water supplier (and not a wholesale water supplier). The City’s 2025
Plan was prepared based on the CWC requirements pertaining to retail water suppliers.
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City of Arcadia Page 2-4
The City relies on water supplies from wholesale water suppliers which are discussed
in Section 2.4.1.
PUBLIC WATER SYSTEMS
California Health and Safety Code 116275.
(h) "Public water system" means a system for the provision of water for human consumption
through pipes or other constructed conveyances that has 15 or more service connections or
regularly serves at least 25 individuals daily at least 60 days out of the year.
Pursuant to CWC requirements, the City’s 2025 Plan incorporates DWR’s standardized
Submittal Tables for the reporting and submittal of UWMP data. The Submittal Tables are
provided within the body of the 2025 Plan text as well as in Appendix A. The City also
submitted the UWMP data (from the Submittal Tables) electronically through DWR’s
Online Submittal Tool.
In addition, the City is a Public Water System and is regulated by the State Water
Resources Control Board - Division of Drinking Water (SWRCB-DDW). The SWRCB-
DDW requires water agencies provide the number of connections, water usage, and other
information annually. The information provided to SWRCB-DDW indicates the City serves
potable water to more than 3,000 customers and supplies more than 3,000 AFY. Table
2-1 provides the City’s Public Water System name and number. As indicated in Table 2-
1, the City serves only a single Public Water System.
2025 Urban Water Management Plan
City of Arcadia Page 2-5
INDIVIDUAL OR REGIONAL PLANS
The City has developed its 2025 Plan reporting solely on its service area to address all
requirements of the California Water Code. The City’s 2025 Plan was not developed as
a Regional Plan.
As shown in Table 2-2, the City’s 2025 Plan is an “Individual UWMP”. The City has
developed its 2025 Plan reporting solely for its service area to address all requirements
of the California Water Code, including water use targets and baselines pursuant to SB
X7-7 Water Conservation Act of 2009 reporting (discussed further in Chapter 5). The City
notified and coordinated with appropriate regional agencies and constituents (See
Section 2.4).
REGIONAL REPORTING
CWC 10620.
(d)(1) An urban water supplier may satisfy the requirements of this part by participation in area
wide, regional, watershed, or basin wide urban water management planning where those
plans will reduce preparation costs and contribute to the achievement of conservation and
efficient water use.
As indicated in Table 2-2, the City’s 2025 Plan was developed as an “Individual UWMP”
and not part of a Regional Plan or Regional Alliance.
2025 Urban Water Management Plan
City of Arcadia Page 2-6
FISCAL OR CALENDAR YEAR AND UNITS OF MEASURE
CWC 10608.20.
(a)(1) Urban retail water suppliers…may determine the targets on a fiscal or calendar year basis.
FISCAL OR CALENDAR YEAR
The data provided in the City’s 2025 Plan is reported on a fiscal year basis, unless noted
otherwise, as shown in Table 2-3. A fiscal year begins on July 1st of every year.
UNITS OF MEASURE
As shown in Table 2-3, the data provided in the City’s 2025 Plan is reported in units AF,
unless noted otherwise.
COORDINATION AND OUTREACH
CWC 10631.
(h) An urban water supplier that relies upon a wholesale agency for a source of water shall provide
the wholesale agency with water use projections from that agency for that source of water in
five-year increments to 20 years or as far as data is available. The wholesale agency shall
provide information to the urban water supplier for inclusion in the urban water supplier’s plan
that identifies and quantifies, to the extent practicable, the existing and planned sources of
water as required by subdivision (b), available from the wholesale agency to the urban water
supplier over the same five-year increments, and during various water-year types in
accordance with subdivision (f). An urban water supplier may rely upon water supply
information provided by the wholesale agency in fulfilling the plan informational requirements
of subdivisions (b) and (f).
2025 Urban Water Management Plan
City of Arcadia Page 2-7
WHOLESALE AND RETAIL COORDINATION
The City is a sub-agency of Upper Water, a wholesale agency. As indicated in Table 2-
4, the City has provided its 2025 Plan to Upper Water which includes water use
projections in five-year increments for normal, single dry, and five consecutive year
drought conditions over the next 25 years.
COORDINATION WITH OTHER AGENCIES AND THE
COMMUNITY
CWC 10620.
(d)(3) Each urban water supplier shall coordinate the preparation of its plan with other appropriate
agencies in the area, including other water suppliers that share a common source, water
management agencies, and relevant public agencies, to the extent practicable.
CWC 10642.
Each urban water supplier shall encourage the active involvement of diverse social, cultural, and
economic elements of the population within the service area prior to and during the preparation of
both the plan…
The City is a retail water supplier that serves customers in the City of Arcadia. The City
is required to coordinate the preparation of the Plan with appropriate agencies in the area,
including appropriate water suppliers that share a common source. Therefore, the City
coordinated the preparation of its 2025 Plan with the Main San Gabriel Basin
Watermaster, Upper Water, City of Monrovia, City of Pasadena, City of Sierra Madre, San
Gabriel Valley Water Company, Golden State Water Company, California American
Water Company, and Sunny Slope Water Company. As discussed in Section 10.2, the
City notified these agencies, as well as the cities and county within which the City provides
water supplies, at least sixty (60) days prior to the public hearing of the preparation of the
2025 Urban Water Management Plan
City of Arcadia Page 2-8
2025 Plan and invited them to participate in the development of the 2025 Plan. A copy of
the notification letters sent to these agencies is provided in Appendix D.
NOTICE TO CITIES AND COUNTIES
CWC 10621.
(b) Every urban water supplier required to prepare a plan pursuant to this part shall, at least 60
days before the public hearing on the plan required by Section 10642, notify any city or county
within which the supplier provides water supplies that the urban water supplier will be reviewing
the plan and considering amendments or changes to the plan.
As discussed in Section 10.2, notification was provided to the cities and county within
which the City provides water supplies that the City was reviewing and considering
amendments (updates) to the previous 2020 Plan, and as a result prepare the 2025 Plan.
Notification was provided on March 4, 2026, at least 60 days prior to the public hearing
(see Appendix D).
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City of Arcadia Page 2-9
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 2 are provided
below.
SUBMITTAL TABLE 2-1: PWSs
Table 2-1 Public Water Systems
CA1910003 City of Arcadia 15,564 13,294
15,564 13,294Total
Public Water System
Number
Public Water System
Name
Number of Municipal
Connections 2025
Submittal Table 2-1 Retail: Public Water Systems
Add additional rows as needed
NOTES: Units are in acre-feet (AF)
Volume of Water
Supplied 2025 (AF)
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported
in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table
2-3.
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City of Arcadia Page 2-10
SUBMITTAL TABLE 2-2: PLAN TYPE IDENTIFICATION
Table 2-2 Plan Type Identification
2025 Urban Water Management Plan
City of Arcadia Page 2-11
SUBMITTAL TABLE 2-3: SUPPLIER INFORMATION
Table 2-3 Supplier Information
2025 Urban Water Management Plan
City of Arcadia Page 2-12
SUBMITTAL TABLE 2-4: WATER SUPPLIER INFORMATION
EXCHANGE
Table 2-4 Water Supplier Information Exchange
Submittal Table 2-4 Retail: Water Supplier Information Exchange
Water Code Section 10631(h)
The retail Supplier has informed the following wholesale supplier(s) of
projected water use.
Wholesale Water Supplier Name
Add additional rows as needed
Upper San Gabriel Valley Municipal Water District
NOTES:
2025 Urban Water Management Plan
City of Arcadia Page 3-1
CHAPTER 3
SERVICE AREA DESCRIPTION
LAY DESCRIPTION – CHAPTER 3
SERVICE AREA DESCRIPTION
Chapter 3 (Service Area Description) of the City’s 2025 Plan discusses and provides the
following:
x A description of the City’s service area is provided. The City provides water service
to a majority of the City of Arcadia and encompasses an area of approximately 11
square miles. The City of Arcadia is in the north-central area of the San Gabriel
Valley extending northward into the southerly slopes of the San Gabriel Mountains
and which lies northeast of the City of Los Angeles.
x The City’s water service area encompasses an area of approximately 11 square
miles. The location of the City’s water service area is provided in Figure 1.
x A description regarding the City’s water service area climate is provided. The
monthly historical average temperatures (including minimum and maximum),
monthly historical average rainfall, and monthly evapotranspiration (ETo) in the
vicinity of the City’s service area is summarized. The sources of the climate
information are also discussed.
x The population within the City’s water service area is discussed and projected. The
sources of the population information are also discussed. The City provides water
service to an area with a current population of about 54,700. The City is projected
to have a population of about 66,900 by Fiscal Year 2049-50.
x A discussion of land use information used by the City to develop the 2025 Plan is
provided. The City reviewed the current and projected land uses within its service
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City of Arcadia Page 3-2
area. The City also reviewed data provided by the Southern California Association
of Governments, the Department of Finance, and the United States Census
Bureau and prepared for counties, cities, and unincorporated areas within
Southern California.
GENERAL DESCRIPTION
CWC 10631.
(a) Describe the service area of the supplier, including current and projected population, climate,
and other social, economic, and demographic factors affecting the supplier’s water
management planning. The projected population estimates shall be based upon data from the
state, regional, or local service agency population projections within the service area of the
urban water supplier and shall be in five-year increments to 20 years or as far as data is
available. The description shall include the current and projected land uses within the existing
or anticipated service area affecting the supplier’s water management planning. Urban water
suppliers shall coordinate with local or regional land use authorities to determine the most
appropriate land use information, including, where appropriate, land use information obtained
from local or regional land use authorities, as developed pursuant to Article 5 (commencing
with Section 65300) of Chapter 3 of Division 1 of Title 7 of the Government Code.
The City of Arcadia is a residential community encompassing approximately 11 square
miles, in the north-central area of the San Gabriel Valley extending northward into the
southerly slopes of the San Gabriel Mountains and which lies northeast of the City of Los
Angeles.
The City was incorporated in 1903, and in 1914 its citizens agreed to develop a municipal
water system. A bond issue was passed and by 1916 the City had purchased an existing
water company, drilled wells, built reservoirs and installed thousands of feet of water main
as well as fire hydrants and water meters.
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In 1918, the State of California granted the City a domestic water supply permit. Since
then, the City has improved its water system by drilling additional wells, building new
reservoirs, constructing booster pumps, and installing many miles of water mains. These
improvements were funded through two bond issues. The last bond was redeemed in
1966, and since then, all additional improvements have been funded by water sales,
developers and federal grants.
The City provides water service to a majority of the City of Arcadia and encompasses an
area of approximately 11 square miles, as shown in Figure 1. The City currently derives
its water supply from groundwater wells that produce water from two groundwater basins;
the Main San Gabriel Basin and the Raymond Basin, with the Main San Gabriel Basin as
the City’s primary groundwater source. The City is also a sub-agency of Upper Water, a
wholesale water agency and can purchase treated, imported water. A discussion of the
City’s sources of water supply is provided in Chapter 6.
SERVICE AREA BOUNDARY MAPS
As discussed in Section 3.1, the City’s service area covers approximately 11 square miles
encompassing the majority of the City of Arcadia. A service area boundary map is
provided on Figure 1. The City’s water service area boundary relative to the City of
Arcadia’s municipal boundary is also provided in Figure 2.
The City’s service area boundary was originally created in a Geographical Information
Systems (GIS) shape file format and converted into a KML format. To the extent
information was available, metadata was included in the KML file (including map
projection, contact information, start and end dates for which the map is valid, constraints,
attribute table definitions, and digitizing base).
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SERVICE AREA CLIMATE
CWC 10631.
(a) Describe the service area of the supplier, including … “climate…”
CWC 10630.
It is the intention of the Legislature, in enacting this part, to permit levels of water management
planning commensurate with the numbers of customers served and the volume of water supplied,
while accounting for impacts from climate change.
The monthly historical average temperatures (including minimum and maximum),
monthly historical average rainfall, and monthly evapotranspiration in the vicinity of the
City’s service area is summarized in the tabulation below. Historical climate information
was obtained from the Western Regional Climate Center (WRCC), Los Angeles County
Department of Public Works (DPW), and from DWR’s California Irrigation Management
Information System (CIMIS).
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Service Area Climate Information
Month
Average
Temperature
Average Min.
Temperature
Average Max.
Temperature
Average Total
Precipitation ETo
(F) (F) (F) (Inches) (Inches)
January 54.9 43.1 66.7 4.3 2.15
February 56.4 44.5 68.2 4.5 2.54
March 58.3 46.4 70.3 3.4 3.85
April 61.6 49.3 73.9 1.3 4.61
May 64.6 52.7 76.5 0.5 5.21
June 69.2 56.3 82.2 0.1 6.00
July 74.6 60.5 88.7 0.0 6.58
August 75.3 60.9 89.6 0.1 6.38
September 73.4 59.2 87.6 0.4 4.95
October 67.6 54.0 81.2 0.7 3.55
November 60.9 47.7 74.1 1.6 2.48
December 55.4 43.6 67.3 3.2 1.90
Annual 64.4 51.5 77.3 19.9 50.22
Source:
Historical average monthly precipitation and temperature information was obtained from the Western Regional Climate Center
(http://www.wrcc.dri.edu/) and is based on data collected from Station 046719 (Pasadena, CA) from 1893 through 2015. Historical
monthly average ETo information was obtained from the California Irrigation Management Information Systems
(http://wwwcimis.water.ca.gov) and is based on data collected from Station 159 (Monrovia).
The historical average rainfall in the vicinity of the City’s service area is 19.9 inches. The
City’s service area in the San Gabriel Valley has a dry climate and summers can reach
average maximum daily temperatures in the high 80s. Although changes in climatic
conditions may have an impact (as discussed in Section 4.5), the projected water supply
demands will be based on average year, single dry year and a five consecutive year
drought, based on historical data and projected demands. Precipitation within the vicinity
of the City’s service area is discussed further in Section 7.2.
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A discussion of the City’s sources of supply, how those sources may be impacted by
climate change, and the proactive actions the City and other local/regional water
managers may take to address the potential climate change on water supplies is provided
in Section 4.2.5.6.
SERVICE AREA POPULATION AND DEMOGRAPHICS
SERVICE AREA POPULATION
CWC 10631.
(a) Describe the service area of the supplier, including current and projected population… The
projected population estimates shall be based upon data from the state, regional, or local
service agency population projections within the service area of the urban water supplier and
shall be in five-year increments to 20 years or as far as data is available.
The City provides water service to an area with a current population of about 54,700.
Table 3-1 presents the current and projected population of the area encompassed by the
City’s service area from FY 2024-25 to FY 2049-50. The City is projected to have a
population of about 66,900 by FY 2049-50.
A GIS analysis using census tracts was performed to estimate the current population (FY
2024-25) within the City’s service area. The City’s service area is comprised of individual
census tracts which represent smaller statistical areas for which population data is
available. The smaller census tracts were combined to more accurately represent the
total area within the City’s service area.
Current census tract information was obtained in a GIS format from the advanced
demographics dataset developed by Esri which includes source material supplied by
the U.S. Census Bureau and the U.S. Census Bureau's American Community Survey.
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The City’s service area boundary in a GIS format was overlayed on the census tract GIS
layer. Each census tract located within the City’s service area was identified (including
the entire census tract or a portion of). For a census tract located entirely within the
service area, the entire population (i.e. 100 percent) associated with the census tract was
incorporated. For a census tract located partially within the service area, the portion (or
percentage) of the census tract located geographically within the service area was
determined through GIS. The percentage was then applied to the census tract’s
population in order to estimate the population of the census tract within the service area.
The total population within the City’s service area was then estimated based on the sum
of the populations within these census tracts.
The projected total population within the City’s service area was based on growth rate
projections included in the Southern California Association of Governments (SCAG)
“Connect SoCal 2024, Demographics and Growth Forecast” report dated April 2024. The
SCAG report incorporates demographic trends, existing land use, general plan land use
policies, and input and projections through the year 2050 from the Department of Finance
(DOF) and the U.S. Census Bureau for counties, cities and unincorporated areas within
Southern California. Annual growth rate projections within the City’s service area were
estimated based on the SCAG report and applied to the City’s current population to
estimate projected populations through 2050.
The City’s service area is almost built out with predominantly single and multi-family
residential units and some commercial, institutional, and industrial establishments.
Moving forward, the City will continue planning for the Regional Housing Needs
Assessment (RHNA) allocations and future planned developments including the addition
of apartment units and accessory dwelling units (ADUs) as the means of affordable
housing.
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Pursuant to the California State Housing Law, every jurisdiction (including the City of
Arcadia) is required to plan for its RHNA allocation in the Housing Element of its General
Plan. RHNA is a representation of future housing needs for all income levels in a
jurisdiction. SCAG’s “6th Cycle Final RHNA Allocation” was adopted March 2021 (and
modified in July 2021) and covers the planning period from October 2021 through October
2029. The total RHNA allocation of housing within the City of Arcadia through 2029 is
3,214 units (including 1,102 “very-low” income units, 570 “low” income units, 605
“moderate” income units, and 937 “above moderate” income units). The City of Arcadia
must identify adequate sites and establish policies and programs that will accommodate
the estimated growth, however the City of Arcadia is not obligated to produce, construct,
or develop these allocated units. However, the population projections in the City’s 2025
Plan incorporate anticipated RHNA allocations.
OTHER SOCIAL, ECONOMIC, AND DEMOGRAPHIC FACTORS
CWC 10631.
(a) Describe the service area of the supplier, including… other social, economic, and
demographic factors affecting the supplier’s water management planning.
No other demographic factors than previously described affect significantly the City’s
water management planning. However, increased population will have an impact on water
demand.
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LAND USES WITHIN SERVICE AREA
CWC 10631.
(a) ...The description shall include the current and projected land uses within the existing or
anticipated service area affecting the supplier’s water management planning. Urban water
suppliers shall coordinate with local or regional land use authorities to determine the most
appropriate land use information, including, where appropriate, land use information obtained
from local or regional land use authorities…
The City reviewed the current and projected land uses within its service area during the
preparation of this 2025 Plan. Information regarding current and projected land uses is
included in the City of Arcadia’s General Plan. The existing land uses within the City’s
service area include residential (single-family and multi-family), commercial, and open
space. The projected land uses within the City’s service area are expected to remain
similar to the existing land uses. In addition, although mostly built-out, the projected
population within the City’s service area is anticipated to increase (as discussed in
Section 3.4). A discussion of the existing and projected water uses for the individual water
use sectors within the City’s service area, which includes the different land uses, is
provided in Section 4.2. As discussed in Section 2.4, the City coordinated the preparation
of the 2025 Plan with the City of Arcadia, the County of Los Angeles, and other agencies.
As discussed in Section 3.4, the City obtained data from the Southern California
Association of Governments document entitled “Connect SoCal 2024, Demographics and
Growth Forecast”, dated April 2024. Projected populations in the City’s service area were
based on growth rate projections developed by SCAG. The data provided by SCAG
incorporates demographic trends, existing land use, general plan land use policies, and
input and projections through the year 2050 from the Department of Finance and the U.S.
Census Bureau for counties, cities and unincorporated areas within Southern California.
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SUBMITTAL TABLES
The applicable standardized Submittal Table referenced within Chapter 3 is provided
below.
SUBMITTAL TABLE 3-1: POPULATION - CURRENT AND
PROJECTED
Table 3-1 Population - Current and Projected
2025 2030 2035 2040 2045 2050(opt)
54,700 60,303 65,903 66,233 66,564 66,897
Submittal Table 3-1 Retail: Population - Current and Projected
Water Code Section 10631(a)
Population
Served
NOTES:
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City of Arcadia Page 4-1
CHAPTER 4
WATER USE CHARACTERIZATION
LAY DESCRIPTION – CHAPTER 4
WATER USE CHARACTERIZATION
Chapter 4 (Water Use Characterization) of the City’s 2025 Plan discusses and provides
the following:
x The City provides water service to individual “water use sectors”. These water use
sectors include single-family residential, multi-family, commercial, and landscape.
Individual descriptions for these water use sectors are provided in Section 4.2.1.
x The City’s total water demands (including potable water) over the past 15 years
have ranged from 11,621 AFY to 17,452 AFY, with an average of 14,341 AFY. The
City currently measures its water use through meter data and billing records.
x The City conducts an annual water loss audit to identify distribution system water
losses. Water losses can result from pipeline leaks and inaccurate metering due
to faulty meters. Water loss estimates are incorporated into the City’s projected
water demands.
x The City’s current and projected water demands are provided in five-year
increments over the next 25 years are provided (through Fiscal Year 2049-50) as
shown on Table 4-3.
x The City’s water demand projections incorporate passive savings from water
savings which are the result of implementation of codes, water conservation
standards, and/or ordinances.
x The projected water demands for lower income households are identified and are
included in the City’s total projected water demands.
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City of Arcadia Page 4-2
x The City’s sources of water supply and how those sources may be impacted by
climate change are discussed. The proactive actions the City and other
local/regional water managers may take to address the potential climate change
impacts on water supplies are also discussed.
NON-POTABLE VERSUS POTABLE WATER USE
The Water Code requires a description and quantification of water uses within the City’s
service area, including both non-potable and potable water. Recycled water (non-potable)
uses are addressed in Section 6.2.5, (although the City currently has none); however, a
summary is provided in Table 4-1 and Table 4-2. Furthermore, Chapter 4 addresses the
City’s potable water demands.
PAST, CURRENT, AND PROJECTED WATER USE BY SECTOR
CWC 10635.
(a) Every urban water supplier shall include, as part of its urban water management plan, an
assessment of the reliability of its water service to its customers during normal, dry, and
multiple dry water years. This water supply and demand assessment shall compare the total
water supply sources available to the water supplier with the long-term total projected water
use over the next 20 years, in five-year increments, for a normal water year, a single dry water
year, and a drought lasting five consecutive water years. The water service reliability
assessment shall be based upon the information compiled pursuant to Section 10631,
including available data from state, regional, or local agency population projections within the
service area of the urban water supplier.
CWC 10631.
(d)(1) For an urban retail water supplier, quantify, to the extent records are available, past and
current water use, over the same five-year increments described in subdivision (a), and
projected water use, based upon information developed pursuant to subdivision (a),
identifying the uses among water use sectors, including, but not necessarily limited to, all of
the following…
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City of Arcadia Page 4-3
(2) The water use projections shall be in the same five-year increments described in subdivision
(a).
(4)(A) Water use projections, where available, shall display and account for the water savings
estimated to result from adopted codes, standards, ordinances, or transportation and land
use plans identified by the urban water supplier, as applicable to the service area.
(4)(B) To the extent that an urban water supplier reports the information described in
subparagraph (A), an urban water supplier shall do both of the following:
(i) Provide citations of the various codes, standards, ordinances, or transportation and
land use plans utilized in making the projections.
(ii) Indicate the extent that the water use projections consider savings from codes,
standards, ordinances, or transportation and land use plans. Water use projections that do
not account for these water savings shall be noted of that fact.
The City’s current and projected water demands are provided in five-year increments over
the next 25 years (through FY 2049-50) in Tables 4-1 and 4-2. The City’s total water
demands were projected based on a review of the “2020 Water Use Target” pursuant to
SB X7-7 calculations (discussed in Section 5.2), current water use factors based on
recent water demands, Urban Water Use Objective standards (discussed in Section
5.2.6), and the total population projections based on land use trends within the City
(discussed in Section 3.4).
The City provides water service to individual “water use sectors” as identified by the
California Water Code. The water use sectors supplied by the City are discussed in
Section 4.2.1. The water use for each of these sectors during FY 2024-25 is provided in
Table 4-1. The projected water use for each individual water use sector through FY 2049-
50 is provided in Table 4-2 and is based on the percentage breakdown of water use from
each individual water use sector in FY 2024-25 (the percentages were then applied to the
projected total water use).
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City of Arcadia Page 4-4
WATER-USE SECTORS LISTED IN WATER CODE
CWC 10631.
(d)(1) For an urban retail water supplier, quantify, to the extent records are available, past and
current water use, over the same five-year increments described in subdivision (a), and
projected water use, based upon information developed pursuant to subdivision (a),
identifying the uses among water use sectors, including, but not necessarily limited to, all of
the following:
(A) Single-family residential.
(B) Multifamily.
(C) Commercial.
(D) Industrial.
(E) Institutional and governmental.
(F) Landscape.
(G) Sales to other agencies.
(H) Saline water intrusion barriers, groundwater recharge, or conjunctive use, or any
combination thereof.
(I) Agricultural.
(J) Distribution system water loss.
As shown in Table 4-1, the City’s service area includes the following water use sectors
listed in the California Water Code:
x Single-family residential
(A single-family dwelling unit is a lot with a free-standing building containing one
dwelling unit that may include a detached secondary dwelling. )
x Multi-family
(Multiple dwelling units are contained within one building or several buildings within
one complex. )
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x Commercial
(Commercial users are defined as water users that provide or distribute a product
or service)
x Institutional (and governmental)
(Institutional users are defined as water user dedicated to public service.
Institutional users include, among other users, higher education institutions,
schools, courts, churches, hospitals, government facilities, and nonprofit research
institutions.
x Landscape
(Landscape connections supply water solely for landscape irrigation. Landscapes
users may be associated with multi-family, commercial, industrial, or
institutional/governmental sites, but are considered a separate water use sector if
the connection is solely for landscape irrigation. Landscape water demands are
included in retail demands.)
x Distribution system losses
(Distribution system losses represent the potable water losses from the
pressurized water distribution system and water storage facilities, up to the point
of delivery to the customers. Additional information is discussed in Section 4.2.4)
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OPTIONAL WATER-USE SECTORS IN ADDITION TO THOSE
LISTED IN WATER CODE
The City’s service area includes other water uses for fire hydrant uses. However, the
City’s service area does not include other water demand sectors which are not listed in
the California Water Code (including exchanges, transfers, wetlands or wildlife habitat,
and surface water storage).
PAST WATER USE
Chapter 6 provides a discussion of the sources of water supply the City uses to meet its
water demands. Section 6.1 provides a tabulation of the City’s historical annual water
demands for each water supply source. Over the past 15 years, the City’s total water
demands have ranged from 11,621 AFY to 17,452 AFY, with an average of 14,341 AFY.
In addition, the City previously experienced a five consecutive year drought within its
service area from FY 2011-12 to FY 2015-16. The City also reviewed its historical water
demands to determine the projected water demands and water supply reliability
(discussed in Chapter 7). The City is able to provide sufficient water supplies to meet the
projected water demands of its customers, including during a five consecutive year
drought period.
CURRENT WATER USE
CWC 10631.
(d)(1) For an urban retail water supplier, quantify, to the extent records are available, past… water
use… based upon information developed pursuant to subdivision (a), identifying the uses
among water use sectors…
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The City currently measures its water use through meter data and billing records. The
water use for the City’s individual water use sectors during FY 2024-25 are provided in
Table 4-1. Recycled water uses are addressed separately in Section 6.5; however, a
summary of projected recycled water uses is provided in Table 4-2.
DWR has created an optional “Planning Tool Worksheet” for water suppliers to review
and assess monthly water use trends. DWR has deemed the tool as optional and the
City is not required by DWR to use the tool. Section 6.1 provides a tabulation of the City’s
historical annual water uses for each water supply source. During the past 15 years, the
City experienced a five consecutive year drought within its service area from FY 2011-12
to FY 2015-16. Historical records indicate the City’s annual water demands had been
greater prior to FY 2011-12. The City has been able to provide sufficient water supplies
to its customers, including during long-term droughts and years with historically high water
demands. In addition, the City has been able to provide water service to meet maximum
day water demands for these years, including during the summer months. A further
discussion regarding the reliability of the City’s water supply sources is provided in
Chapter 7.
PROJECTED WATER USE
4.2.5.1 GENERAL GUIDANCE ON PROJECTIONS
CWC 10631.
(d)(1) For an urban retail water supplier, quantify, to the extent records are available, … projected
water use, based upon information developed pursuant to subdivision (a), identifying the
uses among water use sectors…
CWC 10633.
The plan shall provide, to the extent available, information on recycled water...and shall include
all of the following:...
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City of Arcadia Page 4-8
(e) The projected use of recycled water within the supplier’s service area at the end of 5, 10, 15,
and 20 years, and a description of the actual use of recycled water in comparison to uses
previously projected pursuant to this subdivision...
CWC 10635.
(a) Every urban water supplier shall include, as part of its urban water management plan, an
assessment of the reliability of its water service to its customers during normal, dry, and
multiple dry water years. This water supply and demand assessment shall compare the total
water supply sources available to the water supplier with the long-term total projected water
use over the next 20 years, in five-year increments, for a normal water year, a single dry water
year, and a drought lasting five consecutive water years. The water service reliability
assessment shall be based upon the information compiled pursuant to Section 10631,
including available data from state, regional, or local agency population projections within the
service area of the urban water supplier.
CWC 10631.
(h) An urban water supplier that relies upon a wholesale agency for a source of water shall provide
the wholesale agency with water use projections from that agency for that source of water in
five-year increments to 20 years or as far as data is available…
As discussed above, the City’s current and projected water demands are provided in five-
year increments over the next 25 years (through FY 2049-50) in Tables 4-1 and 4-2. The
City’s total water demands were projected based on a review of the “2020 Water Use
Target” pursuant to SB X7-7 calculations (discussed in Section 5.2), current water use
factors based on recent water demands, Urban Water Use Objective standards
(discussed in Section 5.2.6), and the total population projections based on land use trends
within the City (discussed in Section 3.4). Chapter 6 provides a discussion of the sources
of water supply the City will use to meet the projected water demands (including recycled
water use). The City’s projected water demands and water supplies during a normal year,
a single dry year, and a five consecutive year drought are provided in Chapter 7.
Because the City relies on wholesale water supplies, the City has provided its 2025 Plan
to Upper Water as discussed in Section 2.4.1.
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4.2.5.2 WATER-USE PROJECTIONS BY SECTOR
CWC 10631.
(d)(1) For an urban retail water supplier, quantify, to the extent records are available … projected
water use based upon information developed pursuant to subdivision (a),
The City provides water service to individual “water use sectors” as identified by the
California Water Code. The water use sectors supplied by the City are discussed in
Section 4.2.1. The water use for each of these sectors during FY 2024-25 is provided in
Table 4-1. The projected water use for each individual water use sector through FY 2049-
50 is provided in Table 4-2 and is based on the percentage breakdown of water use from
each individual water use sector in FY 2024-25 (the percentages were then applied to the
projected total water use).
4.2.5.3 STANDARDS, CODES, ORDINANCES, AND PLANS
CWC 10631.
(d)(4)(A) Water use projections, where available, shall display and account for the water savings
estimated to result from adopted codes, standards, ordinances, or transportation and
land use plans identified by the urban water supplier, as applicable to the service area.
(d)(4)(B) To the extent that an urban water supplier reports the information described in
subparagraph (A), an urban water supplier shall do both of the following:
(i) Provide citations of the various codes, standards, ordinances, or transportation and
land use plans utilized in making the projections.
(ii) Indicate the extent that the water use projections consider savings from codes,
standards, ordinances, or transportation and land use plans. Water use projections that
do not account for these water savings shall be noted of that fact.
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The City’s projected water demands are provided in five-year increments over the next
25 years (through FY 2049-50) in Table 4-2. The City’s projected water demands and
water supplies during a normal year, a single dry year, and a five consecutive year
drought are provided in Chapter 7. The projected water demands for each of the City’s
water use sectors are provided in Table 4-2. As discussed in the following Section, the
City’s water demand projections incorporate “passive savings” which are the result of
implementation of codes, standards, and/or ordinances.
4.2.5.4 RETAIL ONLY
The City’s total water demands were projected based on a review of the “2020 Water Use
Target” pursuant to SB X7-7 calculations (discussed in Section 5.2), current water use
factors based on recent water demands, Urban Water Use Objective standards
(discussed in Section 5.2.6), and the total population projections based on land use trends
within the City (discussed in Section 3.4). The projected water demands for the water use
sectors were based on the percentage breakdown of water demands from each individual
water use sector in FY 2024-25 (the percentages were then applied to the projected total
water demands). A discussion of the City’s water supplies from Upper Water, a
wholesaler, are discussed in Section 6.2. As discussed in Section 2.4.1, the City has
coordinated its water demand projections with Upper Water for each water use sector.
The City’s water demand projections incorporate water savings from “passive savings”
which are the result of implementation of codes, standards, and/or ordinances. The City’s
”Water Conservation Plan”, which was created through Ordinance No. 1930, which was
adopted in 1991 and subsequently expanded upon by the adoption of Ordinance No.
2327 in 2015 (discussed in Chapter 9.1.3), includes methods for current and ongoing
reduction in water use and water waste. Prior to adoption of Ordinance No. 2327, the
City’s water use rate ranged from approximately 272 gallons per capita day to 317 gallons
per capita day (from FY 1995-96 through FY 2004-05). As identified in Section 5.2.2, the
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City of Arcadia Page 4-11
City’s actual water use rate during FY 2019-20 was 230 gallons per capita per day which
is a decrease of up to 87 gallons per capita per day from the recent historical water use
and includes passive savings. The City’s projected water demands, incorporate water
use targets less than its established SB X7-7 water use target for 2020 and incorporate
ongoing water passive savings and reduced water use. As indicated in Table 4-3,
estimated future water savings have been considered as part of the City’s water use
projections.
4.2.5.5 LOWER-INCOME HOUSEHOLDS
CWC 10631.1.
(a) The water use projections required by Section 10631 shall include projected water use for
single-family and multifamily residential housing needed for lower income households, as
defined in Section 50079.5 of the Health and Safety Code, as identified in the housing element
of any city, county, or city and county in the service area of the supplier.
(b) It is the intent of the Legislature that the identification of projected water use for single-family
and multifamily residential housing for lower income households will assist a supplier in
complying with the requirement under Section 65589.7 of the Government Code to grant a
priority for the provision of service to housing units affordable to lower income households.
California Health and Safety Code 50079.5.
(a) "Lower income households" means persons and families whose income does not exceed the
qualifying limits for lower income families… In the event the federal standards are discontinued,
the department shall, by regulation, establish income limits for lower income households for all
geographic areas of the state at 80 percent of area median income, adjusted for family size and
revised annually.
The City’s water demands projections provided in Table 4-2 include projected water
demands for lower income single-family and multi-family households. A lower income
household is defined as a household with an income less than 80 percent of the “area
median income”, adjusted for family size. For the purpose of this evaluation, the entire
Los Angeles County was used for the “area median income”. The total number of lower
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City of Arcadia Page 4-12
income households within the City’s service area was estimated based on billing records
provided by the City, a review of the City of Arcadia’s General Plan, a review of median
household income range statistics provided by the US Census Bureau
(https://data.census.gov/cedsci/), and a review of GIS maps of Disadvantaged Communities2
(DACs), including block groups, tracts, and places, provided by DWR. The estimated
number of lower income households located within the City’s service area is 33.5 percent
of the total number of households. As indicated in Table 4-2, the total projected residential
(single family and multi-family) water demands within the City in 2050 is estimated at
about 16,388 AFY. Based on a 33.5 percent use factor of total residential water demands,
the projected water demand for lower income households will be about 5,496 AFY by FY
2049-50. The projected water demands for lower income households were included in
the City’s total projected water demands, as indicated in Table 4-3.
4.2.5.6 CLIMATE CHANGE CONSIDERATIONS
CWC 10630.
It is the intention of the Legislature, in enacting this part, to permit levels of water management
planning commensurate with the numbers of customers served and the volume of water supplied,
while accounting for impacts from climate change.
CWC 10635.
(b) Every urban water supplier shall include, as part of its urban water management plan, a drought
risk assessment… (and) shall include each of the following…
(4) Considerations of the historical drought hydrology, plausible changes on projected supplies
and demands under climate change conditions, anticipated regulatory changes, and other
locally applicable criteria.
2 GIS information for DACs is based on data from the US Census showing census block groups, tracts, and
places identified as disadvantaged communities (less than 80 percent of the State's median household
income) or severely disadvantaged communities (less than 60 percent of the State's median household
income).
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City of Arcadia Page 4-13
Climate is defined as “the average course or condition of the weather at a place usually
over a period of years as exhibited by temperature, wind velocity and precipitation”.3 A
change in the climate which produces a greater amount of precipitation (i.e. more runoff
and/or snowpack) and lower temperatures is generally a benefit to water supplies.
However, drought conditions which may result in decreased precipitation, decreased
runoff, and increased temperature may adversely affect an urban water supplier’s ability
to meet demands by potentially impacting supplies. Consequently, the focus of impacts
of climate change is on these adverse consequences.
Section 6.2 of this Plan describes the City’s sources of water supply, management
practices associated with those sources, and the long-term reliability of those sources.
Section 7.3 includes a Drought Risk Assessment which considers the potential impacts
of climate change to the City’s water supply sources. Chapter 8 provides a detailed
discussion of the City’s Water Shortage Contingency Plan, including but not limited to,
the six standard water shortage levels in the event climate change results in a reduction
to water supplies associated with a periodic drought condition. The following is a
discussion of the City’s sources of supply, how those sources may be impacted by climate
change, and the proactive actions the City and other local/regional water managers may
take to address the potential climate change impacts on water supplies.
Imported Water Supplies
The City can receive treated imported water as discussed in Section 6.2.1 and relies on
the Main Basin Watermaster and Raymond Basin Management Board to manage the
groundwater supplies of the Main Basin and Raymond Basin. Consequently, the City
directly and/or indirectly relies on Metropolitan Water District of Southern California
3 Climate, www.merriam-webster.com.
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City of Arcadia Page 4-14
(MWD) for those imported water supplies. MWD has prepared a Regional 2025 Urban
Water Management Plan which includes a discussion (Section 2.6 in MWD’s 2025
UWMP) of the reliability of its water supplies and the impacts of climate change and is
incorporated by reference in this Plan. Furthermore, the City is a sub-agency of the Upper
Water which has also provided a discussion of climate change considerations and that
discussion is included by reference. The following is a brief summary of MWD’s efforts:
Resource Planning
x MWD has established the Robust Decision Making (RDM) approach to identify
vulnerabilities to its water supplies. Climate change information was applied to
MWD’s simulated water supply scenarios to demonstrate the vulnerability of water
supplies to climate change.
x MWD altered the inflow hydrology scenarios on the Colorado River simulation
model to reflect modified inflow to MWD’s Colorado River aqueduct.
Knowledge Sharing and Research Support
x MWD is an active and founding member of the Water Utility Climate Alliance
(WUCA) which includes 12 nationwide partners collaborating on climate change
considerations. As such, MWD shares agency actions on climate change and
adaptation. WUCA has also released numerous research papers on climate
change.
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Implementation of Programs and Policies
x MWD’s programs include the use of solar energy, use of ride share programs, and
reduction of greenhouse emissions. Collectively these actions are intended to
impact the effects of climate change.
Groundwater Supplies – Main Basin
The City relies on groundwater produced from the Main Basin as discussed in Section
6.2.2. The Main Basin (which is included as a subbasin of the San Gabriel Valley Basin,
Basin Number 4-13 pursuant to DWR Bulletin 118) has been identified by DWR as a very
low-priority groundwater basin partially due to the fact it is adjudicated. In that regard, the
Main Basin is actively managed by the Main Basin Watermaster and those management
activities are described in detail in Section 6.2.2.
Recognizing the potential impacts of climate change on the Main Basin groundwater
supplies (decreased local runoff and replenishment, along with increased groundwater
production, may lead to decreased groundwater levels), the City has used climate tools
available on the California Energy Commission’s Cal-Adapt website (https://cal-adapt.org/)
to identify potential future climate change cycles for the Main Basin. The Cal-Adapt
website has been developed by the Geospatial Innovation Facility at the University of
California, Berkeley with funding and advisory oversight by the California Energy
Commission and California Strategic Growth Council.
To address the uncertainty in future greenhouse gas emissions, Cal-Adapt has developed
a Representative Concentration Pathway 4.5 (RCP 4.5) scenario and a Representative
Concentration Pathway 8.5 (RCP 8.5) scenario. RCP 4.5 represents a scenario in which
greenhouse gas emissions peak around 2040, then decline and stabilize. RCP 8.5
represents a scenario in which emissions continue to strongly rise through 2050 and
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plateau around 2100. RCP 4.5 is a “medium” emissions scenario that models a future in
which there is an effort made by societies to reduce greenhouse gas emissions, whereas
RCP 8.5 is a “business-as-usual” scenario. For the City’s climate change analysis, the
RCP 4.5 scenario was selected.
The Cal-Adapt climate tools also incorporate several General Circulation Models (GCMs),
which represent physical processes in the atmosphere, ocean, and land surface. These
GCMs projected future climates under conditions such as warm/dry, cooler/wetter, and
average simulations. For the City’s climate change analysis, the average condition GCM
(CanESM2) was selected.
The climate tools available on the Cal-Adapt website were used to simulate projected
annual precipitation and annual average maximum temperature in the Main Basin. An
electronic boundary of the Main Basin was submitted online through the Cal-Adapt
website in a “KML” file format (i.e. Google Earth format) and data using several of the
available climate tools was generated.
Based on the data generated by the Cal-Adapt simulations (see Appendix E), the average
annual rainfall in the Main Basin is projected to be 21.7 inches through 2099, compared
to historical average of 20.1 inches (from 1961 through 1990). In addition, the average
maximum temperature is projected to be 84.7 degrees Fahrenheit compared to a
historical average of 78.3 degrees Fahrenheit. Although there may be more precipitation
in the future, it may be more likely to fall as rainfall compared to snowfall. The simulations
do not denote the duration or intensity of storms contributing to the annual precipitation.
Notwithstanding, the San Gabriel River watershed includes a complex and interconnected
series of dams, reservoirs and replenishment basins to capture stormwater runoff. In an
average to below average year of precipitation, over 95 percent of the precipitation in the
watershed is retained within the watershed and is not lost to the ocean. Consequently,
most if not all precipitation (whether it is rain or snowfall) likely will be captured for use in
2025 Urban Water Management Plan
City of Arcadia Page 4-17
the Main Basin area and not adversely impacted by a potentially higher average annual
temperature.
Recognizing these potential impacts to local hydrology resulting from climate change and
the resultant impacts to the groundwater supplies, the Main Basin Watermaster has taken
(and may reinstate as needed) the following proactive actions to anticipate and
circumvent the potential impacts of climate change. These actions will enable the City to
rely on the Main Basin as a reliable source of supply.
Judgment Amendments
Since FY 2011-12 the Main Basin Watermaster has become more pro-active by
implementing provisions of the Judgment, and developing and instituting new studies,
programs and plans to address the drought conditions as they progressively worsened.
As a direct result of a multiple-year drought (from 2006 to 2009), the 2012 Judgment
Amendments provided Watermaster with increased management flexibility and
adaptability; and provided more discretion in making Basin management decisions. A
key component of the Judgment Amendments was the new Water Resource
Development Assessment (RDA) to be levied on all production. The RDA was designed
to help address the potential future unavailability of imported replenishment water
supplies, by allowing the Watermaster to collect RDA funds and purchase replenishment
water for storage in the Basin to offset a future Replacement Water obligation (discussed
in Section 6.2.2).
Storm Water Capture
During FY 2011-12, the Watermaster convened an Ad Hoc Committee on storm water
capture to help address the local drought conditions that resulted in the historic low Key
Well (representing groundwater elevation in the Main Basin) elevation in 2009. The Ad
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City of Arcadia Page 4-18
Hoc Committee performed extensive research and coordinated closely with the Los
Angeles County, Department of Public Works (DPW) to identify and prioritize several
potential new and enhanced storm water capture projects.
Reduce Operating Safe Yield
The adjudicated water rights in the Main Basin are approximately 200,000 AF. Through
adoption of an annual Operating Safe Yield the Main Basin Watermaster has the ability
to reduce the amount of water rights available to Producers before they must pay an
assessment for expensive imported water. The Operating Safe Yield has previously been
set at 150,000 AF ten years in a row which has been about 75 percent of the adjudicated
total. This action provides producers with an economic incentive to reduce demands.
Cyclic Storage
Cyclic Storage allows a producer who anticipates a Replacement Water obligation to also
pre-purchase imported water and store it in the Main Basin to meet its future Replacement
Water obligation. The use of Cyclic Storage helps increase groundwater levels, however,
wet Replacement Water deliveries are deferred. Consequently, Cyclic Storage water will
be applied to Replacement Water obligations for the short-term (one to three years),
significantly reducing actual deliveries of Replacement Water. Therefore, with significant
amounts of water stored in Cyclic Storage, setting “lower” Operating Safe Yields will have
almost no short-term impacts on Basin water levels/supplies.
Conservation
Watermaster passed Resolution No. 03-14-260 declaring “drought conditions” and
encouraged all Basin water producers to adopt reduced pumping and water conservation
activities at the retail level. Due to conservation efforts in the Main Basin, production
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decreased from 242,900 AF in FY 2012-13 to 168,400 AF in FY 2022-23, a total of 74,500
AF. Groundwater production was 189,300 AF in FY 2024-25. With less water being
pumped from the Main Basin, this has helped maintain groundwater levels in the Main
Basin.
Recycled Water for Replenishment
The Main Basin Watermaster has declared its support for a new recycled water supply
project for Main Basin replenishment. When completed, the project could supply up to
100 percent of the overall imported replenishment water requirements.
Basinwide Low Water Vulnerability Assessment
During FY 2013-14, the Main Basin Watermaster initiated an evaluation of the potential
impacts to groundwater production wells and local potable water supplies. The
Watermaster also updated the basinwide information on water purveyor inter-connections
in the event water supply from groundwater wells are reduced.
In-Lieu Program
During FY 2014-15, the Main Basin Watermaster re-instated the In-Lieu Program, where
Watermaster funded a Producer’s cost difference to take direct delivery of MWD imported
water “in-lieu” of pumping from its groundwater wells. The In-Lieu Program provided
imported water to the Basin, and preserved groundwater supply in the Basin.
Stormwater Augmentation Program
During FY 2015-16, the Main Basin Watermaster evaluated other ways to help manage
the Main Basin water supplies. While Southern California remained in extreme drought,
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northern California received above-average precipitation. As a result, replenishment
water was made available. The Watermaster determined that during the previous five
consecutive year drought from FY 2011-12 through 2015-16, nearly 400,000 acre-feet
had been pumped from the Basin and not replaced by local rainfall and local runoff
replenishment.
The Water Resource Development Assessment for Stormwater Augmentation Program
(RDA II) was developed by the Main Basin Watermaster to help manage Main Basin water
supplies under the perceived “worst case” hydrologic conditions, which was assumed to
be two additional consecutive five-year droughts, using the same hydrologic conditions
as the recent FY 2011-12 through 2015-16 severe drought. Based upon ten (10)
additional consecutive years of drought, the new RDA II Program is intended to purchase
imported replenishment water (when available), for stormwater augmentation, to maintain
the Baldwin Park Key Well (Key Well) elevation above 180 feet by the end of the tenth
year. This Key Well elevation essentially ensures continued Main Basin water supply to
the Main Basin Producers under a worst case, 15-year sustained drought. The RDA II
Program has an assessment of $175 per AF on all FY 2024-25 production and is planned
to be $175 per AF on all FY 2025-26 production, with a potential to increase in the next
three to five years. Main Basin Watermaster will use the RDA II funds to purchase
untreated imported water to replenish the Basin for the “general benefit” of all Producers
within the Main Basin. The RDA II untreated imported water will supplement local
stormwater replenishment, enhance overall Main Basin conditions, and have “no right of
recovery” using a water right, by any Main Basin producer.
Funding for the RDA II Program is based on the current year’s production. For example,
assessments on FY 2024-25 production were levied in August 2025 and received by
Watermaster by September 20, 2025. Main Basin Watermaster has entered into a Letter
Agreement with Upper Water, MWD and Three Valleys District where Watermaster can
purchase pre-delivered water over 10 years. This pre-delivered MWD water is purchased
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out of MWD’s Cyclic Storage account, and will be paid for by the Main Basin Watermaster,
primarily using funds from the Resource Development Assessments from Upper Water
and Three Valleys District producers.
Groundwater Supplies – Raymond Basin
The City relies on groundwater produced from the Raymond Basin as discussed in
Section 6.2.2. The Raymond Basin (Basin Number 4-23 pursuant to DWR Bulletin 118)
has been identified by DWR as a very low-priority groundwater basin partially due to the
fact it is adjudicated. In that regard, the Raymond Basin is actively managed by the
Raymond Basin Management Board and those management activities are described in
detail in Section 6.2.2.
Recognizing the potential impacts of climate change on the Raymond Basin groundwater
supplies (decreased local runoff and replenishment, along with increased groundwater
production, may lead to decreased groundwater levels), the City has used climate tools
available on the California Energy Commission’s Cal-Adapt website (https://cal-adapt.org/)
to identify potential future climate change cycles for the Raymond Basin. The Cal-Adapt
website has been developed by the Geospatial Innovation Facility at the University of
California, Berkeley with funding and advisory oversight by the California Energy
Commission and California Strategic Growth Council.
To address the uncertainty in future greenhouse gas emissions, Cal-Adapt has developed
a RCP 4.5 scenario and a RCP 8.5 scenario. RCP 4.5 represents a scenario in which
greenhouse gas emissions peak around 2040, then decline and stabilize. RCP 8.5
represents a scenario in which emissions continue to strongly rise through 2050 and
plateau around 2100. RCP 4.5 is a “medium” emissions scenario that models a future in
which there is an effort made by societies to reduce greenhouse gas emissions, whereas
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RCP 8.5 is a “business-as-usual” scenario. For the City’s climate change analysis, the
RCP 4.5 scenario was selected.
The Cal-Adapt climate tools also incorporate several GCMs, which represent physical
processes in the atmosphere, ocean, and land surface. These GCMs projected future
climates under conditions such as warm/dry, cooler/wetter, and average simulations. For
the City’s climate change analysis, the average condition GCM (CanESM2) was selected.
The climate tools available on the Cal-Adapt website were to simulate projected annual
precipitation and annual average maximum temperature in the Raymond Basin. An
electronic boundary of the Raymond Basin was submitted online through the Cal-Adapt
website in a “KML” file format (i.e. Google Earth format) and data using several of the
available climate tools was generated.
Based on the data generated by the Cal-Adapt simulations (see Appendix E), the average
annual rainfall in the Raymond Basin is projected to be 26.1 inches through 2099,
compared to historical average of 24.3 inches (from 1961 through 1990). In addition, the
average maximum temperature is projected to be 82.7 degrees Fahrenheit compared to
a historical average of 76.3 degrees Fahrenheit. Although there may be more precipitation
in the future, it may be more likely to fall as rainfall compared to snowfall. The simulation
does not denote the duration or intensity of the storms contributing to the annual
precipitation. Notwithstanding, the San Gabriel River watershed (including the Rio Hondo,
which is a distributary of the San Gabriel River) includes a complex and interconnected
series of dams, reservoirs and replenishment basins to capture stormwater runoff. In an
average to below average year of precipitation, over 95 percent of the precipitation in the
watershed is retained within the watershed and is not lost to the ocean. Consequently,
most if not all precipitation (whether it is rain or snowfall) likely will be captured and not
adversely impacted by a potentially higher average annual temperature.
2025 Urban Water Management Plan
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Recognizing these potential impacts to local hydrology resulting from climate change and
the resultant impacts to the groundwater supplies, the Raymond Basin Management
Board has taken (and may reinstate as needed) the following proactive actions to
anticipate and circumvent the potential impacts of climate change. These actions will
enable the City to continue use rely on the Raymond Basin as a reliable source of supply.
Temporary Reduction of Allowed Production
Historical prolonged droughts have caused groundwater levels to decrease resulting in
the Raymond Basin Management Board to temporarily reduce the amount of groundwater
which may be produced. The decreased production is designed to promote recovery of
groundwater levels. At such time the groundwater levels have recovered the program
may be suspended, but can be reinstated as needed in the event groundwater levels
decrease in the future.
Recognizing allowed pumping is limited, the City along with other Raymond Basin
producers have taken steps to reduce water demands to address the potential gap
between supply and demand in the event demands cannot be entirely reduced. The City
has production facilities in the Main Basin and has the ability to shift production, if needed.
In addition, the City has a treated water connection and has access to MWD water as an
additional source of supply.
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DISTRIBUTION SYSTEM WATER LOSS
CWC 10631(d)(3).
(d)(3)(A) The distribution system water loss shall be quantified for each of the five years preceding
the plan update, in accordance with rules adopted pursuant to Section 10608.34.
(B) The distribution system water loss quantification shall be reported in accordance with a
worksheet approved or developed by the department through a public process. The water
loss quantification worksheet shall be based on the water system balance methodology
developed by the American Water Works Association.
(C) In the plan due July 1, 2021, and in each update thereafter, data shall be included to show
whether the urban retail water supplier met the distribution loss standards enacted by the
board pursuant to Section 10608.34.
PREVIOUS FIVE YEARS DISTRIBUTION SYSTEM LOSSES
Distribution system water losses represent the potable water losses from the pressurized
water distribution system and water storage facilities, up to the point of delivery to the
customers. Sources of distribution system water loss can include: inaccurate metering
due to faulty meters; water use not metered such as firefighting, flushing of the water
system; and pipeline leaks.
The California Water Code Section 10608.34 requires “On or before January 1, 2024,
and on or before January 1 of each year thereafter, each urban retail water supplier shall
submit a completed and validated water loss audit report for the previous calendar year
or the previous fiscal year...” The water loss audits must follow American Water Works
Association (AWWA) guidance and be validated by a certified water audit validator. The
City’s water loss audits were prepared and validated pursuant to DWR requirements. The
annual water loss audit reports submitted by retail water agencies in California, including
the City, are available on DWR’s WUEdata website (https://wuedata.water.ca.gov/awwa_plans).
2025 Urban Water Management Plan
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The City’s annual water loss audits identify real water losses (e.g. leaks and main failures)
and apparent water losses (e.g. customer meter inaccuracies, systematic data handling
errors in customer billing systems, and unauthorized consumption). The City’s distribution
system water losses are based on the sum of the real and apparent water losses. The
City’s average distribution system water losses represent approximately 8.0 percent of its
total water demands. This average water loss factor was incorporated into the City’s total
potable water demand projections (Tables 4-2 and 4-3).
PROGRESS TOWARD MEETING THE WATER LOSS
PERFORMANCE STANDARD
Consistent with the California Code of Regulations, Title 23, Sections 980 through 986,
retail water suppliers are required to comply with Real Water Loss Performance
Standards by January 1, 2028 (pursuant to SWRCB requirements). Until then, a supplier
may, when calculating its Urban Water Use Objective (discussed further in Section 5.2.6),
use real losses reported in the water loss audits provided to the Department of Water
Resources (discussed in Section 4.3.1), rather than the standard-based budget
calculated according to the equation described Section 970 of the California Code of
Regulations.
Pursuant to the California Water Code Section 10631(d)(3)(C), a retail water supplier is
required to provide data in its 2025 Plan demonstrating whether the retail water supplier
met its Water Loss Performance Standard. The California Code of Regulations includes
the following methods for compliance:
• Retail suppliers may have met their Real Water Loss Performance Standard if their
2025 or 2026 annual water loss audits (currently not available) show actual real water
loss at or below the standard (California Code of Regulations Section 981[b]).
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City of Arcadia Page 4-26
• Retail suppliers may still meet the Real Water Loss Performance Standard if, by
January 1, 2028, their 2027 annual water loss audit shows actual real water loss at
or below the standard (California Code of Regulations Section 981[a] and [b]).
• Apparent Water Loss Performance Standards are evaluated at the time compliance
with the Real Water Loss Performance Standard is assessed (California Code of
Regulations Section 981[d]).
The City’s 2025 water loss audit is due by January 1, 2027 and was not available during
the preparation, completion, and submittal of the City’s 2025 Plan. However, Table 4-6
presents the City’s Real and Apparent Water Loss Performance Standard, as well as
the real and apparent water losses included in the City’s most recent water loss audit.
The City will continue to improve data collection for assessing and reducing water
losses while performing proactive measures to minimize real losses. City field personnel
are trained to spot leaks and verify if water from fire hydrants is metered, permitted, or
if the water is taken without authorization.
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 4 are provided
below.
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TABLE 4-1: TOTAL USES FOR POTABLE AND NON-POTABLE
WATER-ACTUAL
Table 4-1 Total Uses for Potable and Non-Potable Water – Actual
Use Type
Drop down list
May select each use multiple times
These are the only use types that will be
recognized by the WUEdata online submittal tool
Potable or Non-
Potable
(OPTIONAL)
Drop down list
Volume (AF)
Single Family Potable 7,010
Multi-Family Potable 1,863
Commercial Potable 2,284
Institutional/Governmental Potable 937
Other (optional) Fire Hydrants Potable 1
Landscape Potable 135
Distribution System Water Loss Potable 1,064
13294
0
13,294Total
Submittal Table 4-1 Retail: Total Uses for Potable and Non-Potable Water — Actual
Water Code Section 10631(d)(1)
NOTES:
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in
Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
2025 Actual Water Use
Add additional rows as needed
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
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TABLE 4-2: TOTAL USES OF POTABLE AND NON-POTABLE
WATER—PROJECTED
Table 4-2 Total Uses for Potable and Non-Potable Water – Projected
Use Type
Drop down list
May select each use multiple times
These are the only Use Types that will be
recognized by the WUEdata online submittal tool
Potable or Non-Potable
(OPTIONAL)
Drop down list
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 opt (AF)
Single Family Potable 7,790 8,513 8,556 8,599 8,642
Multi-Family Potable 2,070 2,262 2,273 2,285 2,296
Commercial Potable 2,538 2,774 2,788 2,802 2,816
Institutional/Governmental Potable 1,041 1,138 1,144 1,150 1,155
Other (optional) Fire Hydrants Potable 1111 1
Landscape Potable 151 164 165 166 167
Distribution System Water Loss Potable 1,182 1,292 1,298 1,305 1,311
14,773 16,144 16,225 16,308 16,388
0000 0
14,773 16,144 16,225 16,308 16,388
Add additional rows as needed.
Submittal Table 4-2 Retail: Total Uses for Potable, and Non-Potable Water — Projected
Water Code Section 10631(d)(1)
Projected Water Use
(Report To the Extent that Records are Available)
Additional Description
(as needed)
NOTES:
Total
DWR NOTES: Units of measure (AF, CCF, MG ) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of
measure selected in Submittal Table 2-3.
Subtotal Non-Potable
Subtotal Potable
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TABLE 4-3: INCLUSION IN WATER-USE PROJECTIONS
Table 4-3 Inclusion in Water-Use Projections
OPTIONAL TABLE 4-4: PASSIVE WATER SAVINGS
PROJECTION
DWR has deemed Table 4-4 to be optional.
Table 4-4 Passive Savings Projection
Are Future Water Savings Included in Projections?
Drop down list (y/n) Yes
If "Yes" to above, state the section or page number, in the cell to the right,
where citations of the codes, ordinances, or otherwise are utilized in demand
projections are found.
Optional Suppliers may complete Optional Submittal Table 4-4 R to quantify
the expected savings.
Section 4.2.5
and Chapter
8
Are Lower Income Residential Demands Included In Projections?
Drop down list (y/n)Yes
Optional If the method for accounting Lower Income Residential Demands has
been included, provide page number where this accounting can be found.
Submittal Table 4-3 Retail: Inclusion in Water Use Projections
Water Code Section 10631 (a), 10631 (d)(4)(A), and 10631 (d)(4)(B)
NOTES:
DWR NOTES: Additional guidance is provided in Appendix K.
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TABLE 4-5: WATER LOSS AUDIT REPORTING
Table 4-5 Water Loss Audit Reporting
Public Water System ID #
Reported in Table 2-1 R Reporting Period
Submitted to DWR Water
Loss Audit Program
(yes/no)
2020 No
2021 No
2022 Yes
2023 No
2024 No
Submittal Table 4-5 Retail: Water Loss Audit Reporting
Water Code Section 10631(d)(3)(A)
CA1910003
DWR NOTES: Suppliers will provide a link to the WUEdata submittals of their
Water Loss Audit Reports.
NOTES: The City has also prepared Water Loss Audits representing Calendar
Year 2020, Calendar Year 2021, and Fiscal Year 2024-25 and will be submitting
these audits to DWR.
Report submittal status for all five years for each Public Water System as
available.
Add rows as needed
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TABLE 4-6: PROGRESS TOWARD 2028 WATER LOSS
STANDARD
Table 4-6 Progress Toward 2028 Water Loss Standard
2028 Real Water Loss
Standard per Unit per
day
Units for Real
Water Loss
Drop down list
Number of Units
(Connections or
Miles corresponding
with units selected)
Volume of Total Real
Loss
(from AWWA Water
Loss Audit)
(AF)
2028 Apparent
Water Loss
Standard per Unit
per Day
Units for
Apparent Water
Loss
Number of
Connections
Volume of Total
Apparent Loss
(from AWWA Water
Loss Audit)
(AF)
CA1910003 Yes 19.0
Gallons per
Service
Connection per
Day (GPSCD)
14958 792.144 47.3 44.4
Gallons per
Service
Connection per
Day (GPSCD)
14958 162.426 9.7
Gallons per
Service
Connection per
Day (GPSCD)
Gallons per
Service
Connection per
Day (GPSCD)
Submittal Table 4-6 Retail: Progress Towards 2028 Water Loss Standard
Water Code Section 10631(d)(3)(C)
NOTES: Information used to complete the table above was based on the Water Loss Audit from FY 2022-23. The City has also prepared Water Loss Audits representing Calendar Year 2020, Calendar Year 2021, and Fiscal Year 2024-25 and will be
submitting these audits to DWR.
Apparent Water Loss
Did the Water Board Calculate
a Water Loss Standard for this
Public Water System? (y/n)
If no, Supplier will not
complete this row.
Real Water Loss
Water Board's Calculated Water Loss Standards
DWR NOTES: Units of measure (AF, CCF, MG) for Water Loss MUST remain consistent with units reported in Submittal Table 2-3. The units reported in Submittal Table 2-3 are used in this table 's calculations.
Public Water
System ID #
Reported in
Submittal Table 2-
1 R
Add additional rows as needed.
Most Recent AWWA Water Loss Audit
Real Water
Loss Per Unit
per Day
Most Recent AWWA Water Loss Audit
Apparent Water
Loss Per Unit per
Day
State Water Board Standard State Water Board Standard
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City of Arcadia Page 5-1
CHAPTER 5
SB X7-7 BASELINE, 2020TARGETS, 2025 REPORTING
LAY DESCRIPTION – CHAPTER 5
SB X7-7 BASELINES, 2020 TARGETS, AND 2025 REPORTING
Chapter 5 (SB X7-7 Baselines, 2020 Targets, and 2025 Reporting of the City’s 2025 Plan
discusses and provides the following:
x The Water Conservation Act of 2009 (or SB X7-7) required the State of
California achieve a 20 percent reduction in urban water use by the year 2020.
x SB X7-7 required urban water suppliers, including the City, to develop a “2020
Water Use Target” to assist the State of California to achieve the 20 percent
reduction. The 2020 Water Use Target represents the amount of water each
person should use per day (i.e. gallons per capita per day or GPCD) by the year
2020.
x The City previously determined its 2020 Water Use Target during the preparation
of its 2015 Plan by completing standardized tables (or the SB X7-7 Verification
Form) to demonstrate compliance with the Water Conservation Act of 2009. The
City’s 2020 Water Use Target was 238 GPCD.
x The City’s per-capita water use during Fiscal Year 2019-20 was 230 GPCD. The
City’s confirmed 2020 Water Use Target was 238 GPCD. The City’s per-capita
water use during Fiscal Year 2019-20 met the 2020 Water Use Target.
2025 Urban Water Management Plan
City of Arcadia Page 5-2
REPORTING REQUIREMENTS FOR WHOLESALE SUPPLIERS
CWC 10608.12.
(aj) “Urban wholesale water supplier,” means a water supplier, either publicly or privately owned,
that provides more than 3,000 acre-feet of water annually at wholesale for potable municipal
purposes.
CWC 10608.36.
Urban wholesale water suppliers shall include in the urban water management plans required
pursuant to Part 2.6 (commencing with Section 10610) an assessment of their present and
proposed future measures, programs, and policies to help achieve the water use reductions
required by this part.
The City is not a wholesale agency and is not required by DWR to complete Section 5.1.
REPORTING REQUIREMENTS FOR RETAIL SUPPLIERS
CWC 10608.40.
Urban water retail suppliers shall report to the department on their progress in meeting their urban
water use targets as part of their urban water management plans submitted pursuant to Section
10631.
CWC 10608.12.
(af) “Urban retail water supplier” means a water supplier, either publicly or privately owned, that
directly provides potable municipal water to more than 3,000 end users or that supplies more
than 3,000 acre-feet of potable water annually at retail for municipal purposes.
The Water Conservation Act of 2009 (or SB X7-7) required the State of California achieve
a 20 percent reduction in urban water use by the year 2020. SB X7-7 required urban
2025 Urban Water Management Plan
City of Arcadia Page 5-3
water suppliers, including the City, to develop a “2020 Water Use Target” to assist the
State of California to achieve the 20 percent reduction. The 2020 Water Use Target
represents the amount of water each person should use per day (i.e. gallons per capita
per day or GPCD) by the year 2020.
The City previously determined its 2020 Water Use Target during the preparation of its
2015 Plan by completing standardized tables (or the SB X7-7 Verification Form) to
demonstrate compliance with the Water Conservation Act of 2009. The City’s SB X7-7
Verification Form was also included in its 2020 Plan. The City’s 2020 Water Use Target
was 238 GPCD.
SUPPLIER WAS NOT AN URBAN RETAIL WATER SUPPLIER
Section 5.2.1 is not applicable to the City.
The City was an urban retail water supplier during and before the 2020 Plan cycle.
SUPPLIER MET 2020 TARGET IN 2020
The City previously calculated its “2020 Water Use Target” in its 2015 Plan pursuant to
the methodology provided by DWR. The City’s 2020 Water Use Target was confirmed to
be 238 GPCD.
As discussed in the City’s 2020 Plan, the annual gross water use by the City during FY
2019-20 was 13,935 AF. In addition, the estimated population within the City’s service
area for FY 2019-20 was 53,998. As a result, the City’s per-capita water use during FY
2019-20 was 230 GPCD. As shown in Table 5-1, the City’s per-capita water use during
FY 2019-20 met the 2020 Water Use Target. The City also demonstrated compliance with
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City of Arcadia Page 5-4
the 2020 Water Use Target by completing the SB X7-7 2020 Compliance Form (included
in the 2020 Plan).
SUPPLIER DID NOT MEET 2020 TARGET IN 2020—NO
CHANGE TO SERVICE AREA
Section 5.2.3 is not applicable to the City.
As indicated in Section 5.2.2, the City previously met its 2020 Water Use Target as part
of the 2020 Plan.
SUPPLIER DID NOT MEET 2020 TARGET—CHANGE TO
SERVICE AREA SINCE 2020
Section 5.2.4 is not applicable to the City.
As indicated in Section 5.2.2, the City previously met its 2020 Water Use Target as part
of the 2020 Plan. In addition, the City has not had any changes to its service area since
2020.
FUNDING ELIGIBILITY
CWC 10608.56.
(a) On and after July 1, 2016, an urban retail water supplier is not eligible for a water grant or loan
awarded or administered by the state unless the supplier complies with this part.
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City of Arcadia Page 5-5
If a retail water supplier does not achieve its 2020 Water Use Target, the retail water
supplier is not eligible to receive a water grant or loan from the State of California until it
complies. The following two exceptions to this are provided:
x Water Code Section 10608.56(c) states that a water supplier shall be eligible for a
water loan or grant if it “has submitted to the department for approval a schedule,
financing plan, and budget, to be included in the grant or loan agreement, for
achieving the per-capita reductions.”
x Water Code Section 10608.56(e) states that a water supplier can also be eligible
for a water loan or grant if it “has submitted to the department for approval
documentation demonstrating that its entire service area qualifies as a
disadvantaged community.”
As indicated in Section 5.2.2, the City previously met its 2020 Water Use Target as part
of the 2020 Plan.
NEXUS TO STATE WATER BOARD URBAN WATER-USE
OBJECTIVES (NOT REQUIRED FOR UWMPs)
SWRCB’s “Making Conservation A Way of Life Regulation” (under the California Code of
Regulations, Title 23, Section 965 et seq) requires urban retail water suppliers to annually
calculate and comply with an Urban Water Use Objective (UWUO); carry out commercial,
industrial, and institutional (CII) performance measures; and provide progress reports.
The regulation is expected to reduce inefficient water use and protect water supplies from
the effects of rising temperatures and drier conditions due to climate change.
The Urban Water Use Objective is the sum of standard-based water use budgets for
efficient residential indoor use, residential outdoor use, CII landscapes with dedicated
irrigation meters (DIMs), and real water losses. Each budget is the product of the
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City of Arcadia Page 5-6
applicable standard and the water supplier’s unique characteristics (e.g., population).
Water suppliers will be assessed for compliance with their overall objective, not each
standards-based budget.
The residential indoor water use standard is based on 55 GPCD (until December 31,
2024), 47 GPCD (from January 1, 2025 to January 1, 2030), and 42 GPCD (beginning
January 1, 2030). The residential outdoor water standard is based on a landscape
efficiency factor (representing plant factors and irrigation efficiency) of 0.80 (until June 30,
2035), 0.63 (from July 1, 2035 to June 30, 2040), and 0.55 (beginning July 1, 2040). The
standard for commercial, industrial, and institutional (CII) landscapes is based on a
landscape efficiency factor of 0.80 (until June 30, 2035), 0.63 (from July 1, 2035 to June
30, 2040), and 0.45 (beginning July 1, 2040). Urban retail water suppliers are also
required to comply with real water loss standards by January 1, 2028.
DWR has indicated that compliance with the Urban Water Use Objective requirements
are under the authority of the SWRCB and that the requirements are not part of Urban
Water Management Plan content requirements. However, the SWRCB uses the 2020
Water Use Targets as a back stop for the Urban Water Use Objective calculations. The
Urban Water Use Objectives, together with excluded demands, are to be more efficient
than the 2020 Water Use Targets.
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City of Arcadia Page 5-7
SUBMITTAL TABLES
The applicable standardized Submittal Table referenced within Chapter 5 is provided
below.
Table 5-1 SB X7-7 2020 Target Progress
2025 Urban Water Management Plan
City of Arcadia Page 6-1
CHAPTER 6
NORMAL YEAR WATER SUPPLY CHARACTERIZATION
LAY DESCRIPTION – CHAPTER 6
NORMAL-YEAR WATER SUPPLY CHARACTERIZATION
Chapter 6 (Normal-Year Water Supply Characterization) of the City’s 2025 Plan
discusses and provides the following:
x The City’s water supply sources include groundwater pumped from the Main Basin
and Raymond Basin, and treated, imported surface water from Metropolitan Water
District of Southern California purchased through Upper San Gabriel Valley
Municipal Water District.
x The City’s main source of water supply is groundwater pumped from the Main
Basin.
x A tabulation of the City’s historical water supplies is provided in Section 6.1.
x A discussion regarding the City’s imported water supplies from Upper San Gabriel
Valley Municipal Water District is provided. Information regarding imported water
connections, capacities, reliability, and historical production is provided.
x A discussion regarding the City’s groundwater supplies from the Main Basin and
Raymond Basin is provided. Information regarding basin location, adjudication,
management, water levels, water quality, water rights, and historical production is
provided.
x The City’s proposed future projects to maximize its water supply resources are
discussed.
x The City’s “energy intensity” is discussed and represents the quantity of energy
consumed, measured in kilowatt hours, divided by the volume of water, measured
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City of Arcadia Page 6-2
in acre-feet over a one-year period. The total energy intensity associated with the
City’s water management processes was estimated during FY 2024-25.
In this Chapter, the City will identify and describe each of its sources of water supply. In
addition, the City will describe the following:
x Management of each water supply source;
x Current provisions of a basin adjudication or Groundwater Sustainability Plan
(GSP), as applicable, pertaining to management of groundwater supplies;
x Measures the City is taking to develop potential new sources of water supply (as
applicable); and
x Opportunities for exchanges and transfers on a long- or short-term basis.
The characterization of the City’s water supply sources will account for the anticipated
availability during a normal year, a single dry year, a five consecutive year drought, along
with projections through FY 2049-50.
WATER SUPPLY ANALYSIS OVERVIEW
CWC 10631.
(b) Identify and quantify, to the extent practicable, the existing and planned sources of water
available to the supplier over the same five-year increments described in subdivision (a),
providing supporting and related information, including all of the following:
(1) A detailed discussion of anticipated supply availability under a normal water year, single dry
year, and droughts lasting at least five years, as well as more frequent and severe periods of
drought, as described in the drought risk assessment. For each source of water supply,
consider any information pertinent to the reliability analysis conducted pursuant to Section
10635, including changes in supply due to climate change.
(2) When multiple sources of water supply are identified, a description of the management of each
supply in correlation with the other identified supplies.
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City of Arcadia Page 6-3
(3) For any planned sources of water supply, a description of the measures that are being
undertaken to acquire and develop those water supplies.
CWC 10631.
(h) … The wholesale agency shall provide information to the urban water supplier for inclusion in
the urban water supplier’s plan that identifies and quantifies, to the extent practicable, the
existing and planned sources of water as required by subdivision (b), available from the
wholesale agency to the urban water supplier over the same five-year increments, and during
various water-year types in accordance with subdivision (f). An urban water supplier may rely
upon water supply information provided by the wholesale agency in fulfilling the plan
informational requirements of subdivisions (b) and (f).
The City’s water supply sources include groundwater pumped from the Main Basin and
Raymond Basin, and treated, imported surface water from Metropolitan Water District of
Southern California purchased through Upper San Gabriel Valley Municipal Water
District. The City’s main source of water supply is groundwater pumped from the Main
Basin. A tabulation of the City’s historical water supplies is provided below.
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Fiscal Year
System Water Supply Sources (AF)
Total
Groundwater Purchased Water
East Raymond
Basin
West Raymond
Basin
Main San
Gabriel Basin
MWD Imported
Water
2010-11 3,544 1,632 9,840 0 15,016
2011-12 3,526 1,157 11,716 0 16,399
2012-13 2,006 1,930 13,276 0 17,211
2013-14 1,449 1,899 14,104 0 17,452
2014-15 2,051 1,265 12,010 0 15,326
2015-16 1,887 1,022 9,460 0 12,369
2016-17 2,658 460 10,229 0 13,346
2017-18 1,783 534 12,100 0 14,416
2018-19 2,311 508 10,754 0 13,574
2019-20 1,837 536 11,562 0 13,935
2020-21 2,216 678 12,116 0 15,009
2021-22 2,179 621 11,480 0 14,280
2022-23 1,734 641 9,245 0 11,621
2023-24 2,060 286 9,528 0 11,873
2024-25 2,167 772 10,355 0 13,294
Source: Data provided by the City
SPECIFIC ANALYSIS APPLICABLE TO ALL WATER SUPPLY
SOURCES
The section below provides a discussion of the following information to the extent
practical:
x The City’s existing and planned sources of water supply are identified;
x Each source of supply is quantified in five-year increments through FY 2049-50;
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City of Arcadia Page 6-5
x The anticipated supply availability under normal, single dry, and five consecutive
dry years, and any other water year conditions included in the Drought Risk
Assessment (see Chapter 7) are described;
x The management of each water supply in correlation with other identified supplies
is described.
x Information pertinent to the reliability analysis, including climate change effects, is
considered.
The City historically has relied on Main Basin and Raymond Basin, and treated, imported
surface water from Metropolitan Water District of Southern California purchased through
Upper San Gabriel Valley Municipal Water District. The following descriptions summarize
the City’s sources of supply (detailed descriptions are provided in Section 6.2).
Existing and Planned Sources of Supply
Purchased Treated Imported Water
The City has historically purchased treated imported water from the Upper Water, as
described in Section 6.2.1. In addition, Section 6.2.1 provides a detailed discussion of the
existing and planned supply of the treated imported water, including a description of the
management and reliability of those treated imported water supplies. Table 6-8
summarizes the actual treated imported water supply for FY 2024-25. In addition, Table
6-9 summarizes the projected water supply, in five-year increments, through FY 2049-50
under varying water supply conditions.
Groundwater
The City has historically pumped groundwater from the Main Basin and Raymond Basin
as described in Section 6.2.2. In addition, Section 6.2.2 provides a detailed discussion of
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City of Arcadia Page 6-6
the existing and planned supply of the groundwater, including a description of the
management and reliability of those groundwater supplies. Table 6-8 summarizes the
actual groundwater supplies for FY 2024-25. In addition, Table 6-9 summarizes the
projected water supply, in five-year increments, through FY 2049-50 under varying water
supply conditions.
Surface Water
The City does not use surface water supplies to meet its water demands.
Storm Water
The City has historically received groundwater from the Main Basin and Raymond Basin.
Management and use of the stormwater runoff from the San Gabriel River watershed,
which is crucial to groundwater management, is described in Section 6.2.4. However, the
City currently does not have its own program to beneficially use stormwater runoff as a
direct source of supply.
SPECIAL CONSIDERATIONS
The City considered the issues described below when developing its planned sources of
water supply.
6.1.2.1 CLIMATE CHANGE EFFECTS
Climate change has the possibility of impacting the availability of planned water supplies,
particularly during a drought period. Section 4.2.5.6 of this Plan provides a discussion
regarding climate change effects on the City’s various sources of supply.
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City of Arcadia Page 6-7
6.1.2.2 REGULATORY CONDITIONS AND PROJECT DEVELOPMENT
The City has considered the implications of emerging regulatory conditions and project
development on the availability of planned water supplies. Section 1.4 provides a
discussion of the reduced reliance on imported water supplies as well as the proposed
Pure Water Southern California recycled water project.
6.1.2.3 OTHER LOCALLY APPLICABLE CRITERIA
There are no locally applicable criteria which applies to the City.
6.1.2.4 WHOLESALE AND RETAIL SUPPLIERS COORDINATION
Because the City relies on wholesale water supplies, the City has provided its 2025 Plan
to Upper San Gabriel Valley Municipal Water District as discussed in Section 2.4.1.
WATER SUPPLY CHARACTERIZATION
PURCHASED OR IMPORTED WATER
UPPER SAN GABRIEL VALLEY MUNICIPAL WATER DISTRICT
The City can purchase treated, imported water from Metropolitan Water District of
Southern California through Upper San Gabriel Valley Municipal Water District. MWD
imports water from the Colorado River through the Colorado River Aqueduct, owned and
operated by MWD, and the State Water Project, which utilizes the California Aqueduct for
transmission to Southern California. Water delivered to Upper Water’s sub-agencies can
be treated at MWD’s Weymouth Treatment Plant located in the City of La Verne.
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City of Arcadia Page 6-8
The City can purchase treated, imported water directly from its USG-6 (20 cubic feet per
second) connection. The City’s purchases of treated, imported water from Upper Water
over the past five years has been tabulated in Section 6.1. Over the past five years, the
City has not purchased water from Upper Water. The City’s projected purchases of
treated, imported water from Upper Water, over the next 25 years in five-year increments,
is provided in Table 6-9.
The City‘s treated imported water supplies from MWD, through Upper Water, may be
impacted during a multi-year drought or other conditions which limits MWD from delivering
sufficient water supplies to all of its member agencies, and consequently to the City. In
anticipation of such a reduction in supplies, MWD developed a Water Supply Allocation
Plan (WSAP) which is briefly described below. The WSAP provides a means of equitably
providing reduced water supplies to each of MWD’s member agencies for up to 10 levels
of reduction representing up to a 50 percent reduction.
During calendar year 2007, critically dry conditions impacted MWD’s water supply
sources. In addition, a ruling in the Federal Courts in August 2007 provided protective
measures for the Delta Smelt (and subsequently other aquatic species) in the
Sacramento-San Joaquin River Delta resulting in restrictions on the availability of State
Water Project water. As a result, MWD adopted a Water Supply Allocation Plan in
February 2008 to allocate available water supplies to its member agencies. MWD revised
the WSAP in December 2014.
The WSAP establishes ten different shortage levels and a corresponding Allocation to
each member agency. Based on the shortage levels established by MWD, the WSAP
provides a separate reduced Allocation to a member agency for its 1) Municipal and
Industrial (M&I) retail demand and 2) replenishment demand. The WSAP formula
considers historical local water production, full service treated water deliveries,
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City of Arcadia Page 6-9
agricultural deliveries and water conservation efforts when calculating each member
agency’s Allocation.
In general, the WSAP process calculates total historical member agency demand. That
historical demand is then compared to member agency projected local supply for a
specific Allocation year. The balance required from MWD, less an Allocation reduction
factor, is the member agency’s “Water Supply Allocation” of imported water from MWD.
When a member agency reduces its local demand through conservation or other means,
the Allocation of imported water will increase. Depending on MWD’s available supply,
MWD can establish a specific WSAP shortage level. The shortage level causes a regional
reduction and calculates an allocation for each of its member agency. Additional
information about MWD’s WSAP is provided in MWD’s Regional 2025 UWMP which is
incorporated by reference. The following is a summary of MWD’s water shortage levels:
Level 1 – Regional Percent Reduction of 5%
Level 2 – Regional Percent Reduction of 10%
Level 3 – Regional Percent Reduction of 15%
Level 4 – Regional Percent Reduction of 20%
Level 5 – Regional Percent Reduction of 25%
Level 6 – Regional Percent Reduction of 30%
Level 7 – Regional Percent Reduction of 35%
Level 8 – Regional Percent Reduction of 40%
Level 9 – Regional Percent Reduction of 45%
Level 10 – Regional Percent Reduction of 50%
In response to a fourth consecutive year of below average rainfall and critically dry
conditions, MWD declared a WSAP Allocation Level 3 for fiscal year 2015-16, which
represented a regional reduction of 15 percent. MWD rescinded the WSAP for fiscal year
2016-17 and has not reinstated the WSAP since that time.
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GROUNDWATER
CWC 10631.
(b)(4) If groundwater is identified as an existing or planned source of water available to the
supplier, all of the following information:
(A) The current version of any groundwater sustainability plan or alternative adopted pursuant to
Part 2.74 (commencing with Section 10720), any groundwater management plan adopted by
the urban water supplier, including plans adopted pursuant to Part 2.75 (commencing with
Section 10750), or any other specific authorization for groundwater management for basins
underlying the urban water supplier’s service area.
(B) A description of any groundwater basin or basins from which the urban water supplier pumps
groundwater. For basins that a court or the board has adjudicated the rights to pump
groundwater, a copy of the order or decree adopted by the court or the board and a description
of the amount of groundwater the urban water supplier has the legal right to pump under the
order or decree. For a basin that has not been adjudicated, information as to whether the
department has identified the basin as a high- or medium-priority basin in the most current
official departmental bulletin that characterizes the condition of the groundwater basin, and a
detailed description of the efforts being undertaken by the urban water supplier to coordinate
with groundwater sustainability agencies or groundwater management agencies listed in
subdivision (c) of Section 10723 to maintain or achieve sustainable groundwater conditions in
accordance with a groundwater sustainability plan or alternative adopted pursuant to Part 2.74
(commencing with Section 10720).
(C) A detailed description and analysis of the location, amount, and sufficiency of groundwater
pumped by the urban water supplier for the past five years. The description and analysis shall
be based on information that is reasonably available, including, but not limited to, historic use
records.
(D) A detailed description and analysis of the amount and location of groundwater that is projected
to be pumped by the urban water supplier. The description and analysis shall be based on
information that is reasonably available, including, but not limited to, historic use records.
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MAIN SAN GABRIEL BASIN
Main Basin - Sustainable Groundwater Management Act
The Main San Gabriel Basin (Main Basin) is a sub-basin of the San Gabriel Valley Basin
pursuant to DWR Bulletin 118, Basin Number 4-013. Pursuant to the Sustainable
Groundwater Management Act of 2014 (SGMA), the Main Basin was named as an
adjudicated groundwater basin and is exempt from the requirements of developing a
Groundwater Sustainability Plan and subsequently was designated a very-low-priority
basin in DWR’s 2019 SGMA Basin Prioritization report. In compliance with SGMA, the
Main Basin Watermaster submits its Annual Report to DWR.
Main Basin - Adjudication
Main Basin – Long Beach Judgment
On May 12, 1959, the Board of Water Commissioners of the City of Long Beach, the
Central Basin Municipal Water District (Central District), and the City of Compton, as
plaintiffs, filed an action against San Gabriel and 24 other producers of groundwater from
the San Gabriel Valley as defendants. This action sought a determination of the rights of
the defendants in and to the waters of the San Gabriel River system and to restrain the
defendants from an alleged interference with the rights of plaintiffs and persons
represented by the Central District in such waters. After six years of study and negotiation
a Stipulation for Judgment was filed on February 10, 1965, and the Judgment (Long
Beach Judgment) was entered on September 24, 1965. Under the terms of the Long
Beach Judgment, the water supply of the San Gabriel River system was divided at
Whittier Narrows between San Gabriel Valley upstream and the coastal plain of Los
Angeles County downstream. A copy of the Long Beach Judgment can be found in
Appendix F. During water year 2018-19, the Water Replenishment District of Southern
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City of Arcadia Page 6-12
California (WRD) intervened in the Long Beach Judgment for the purpose of assuming
all of the requirements of the Plaintiffs and the City of Long Beach, Central District, and
the City of Compton were dismissed from their collective responsibilities by the Court.
Under the terms of the Long Beach Judgment, the area downstream from Whittier
Narrows (Lower Area), the plaintiffs and those they represent, are to receive a quantity of
usable water annually from the San Gabriel River system comprised of usable surface
flow, subsurface flow at Whittier Narrows and water exported to the Lower Area. This
annual entitlement is guaranteed by the area upstream of Whittier Narrows (Upper Area),
the defendants, and provision is made for the supply of Make-up Water by the Upper Area
for years in which the guaranteed entitlement is not received by the Lower Area.
Make-up Water is imported water purchased by the Main Basin Watermaster and
delivered to agencies in Central District to satisfy obligations under the Long Beach
Judgment. The entitlement of the Lower Area varies annually, dependent upon the
10-year average annual rainfall in the San Gabriel Valley for the 10 years ending with the
year for which entitlement is calculated.
The detailed operations described in the Long Beach Judgment are complex and requires
continuous compilation of data so that annual determinations can be made to assure
compliance with the Long Beach Judgment. In order to do this, a three-member
Watermaster was appointed by the Court, one representing the Upper Area parties
nominated by and through Upper Water, one representing the Lower Area parties
nominated by and through WRD, and one jointly nominated by Upper Water and WRD.
This three-member board is known as the San Gabriel River Watermaster (River
Watermaster).
The River Watermaster meets periodically during the year to adopt a budget, to review
activities affecting water supply in the San Gabriel River system area, to compile and
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review data, to make determinations of usable water received by the Lower Area, and to
prepare its annual report to the Court. The River Watermaster has rendered annual
reports for the water years 1963-64 through 2024-25 and operations of the river system
under that Court Judgment and through the administration by the River Watermaster have
been satisfactory since its inception.
One major result of the Long Beach Judgment was to leave the Main Basin free to
manage its water resources so long as it meets its downstream obligation to the Lower
Area under the terms of the Long Beach Judgment. Upper Water intervened in the Long
Beach case as a defendant to enforce the provisions of a Reimbursement Contract, which
was incorporated into the Long Beach Judgment to assure that any Make-up Water
obligations under the terms of the Long Beach Judgment would be satisfied.
Main Basin – Main Basin Judgment
The Upper Area then turned to the task of developing a water resources management
plan to optimize the conservation of the natural water supplies of the area. Studies were
made of various methods of management of the Main Basin as an adjudicated area and
a report thereon was prepared for the Upper San Gabriel Valley Water Association, an
association of water producers in the Main Basin. After due consideration by the
Association, Upper Water was requested to file as plaintiff, and did file, an action on
January 2, 1968, seeking an adjudication of the water rights of the Main Basin and its
Relevant Watershed. After several years of study (including verification of annual water
production) and negotiations, a stipulation for entry of Judgment was approved by a
majority of the parties, by both the number of parties and the quantity of rights to be
adjudicated. Trial was held in late 1972 and the Judgment (Main Basin Judgment) was
entered on January 4, 1973. The Main Basin Judgment was most recently amended on
June 21, 2012. A copy of the Main Basin Judgment can be found in Appendix G.
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Under the terms of the Main Basin Judgment, all rights to the diversion of surface water
and production of groundwater within the Main Basin and its Relevant Watershed were
adjudicated. The Main Basin Judgment provides for the administration of the provisions
of the Main Basin Judgment by a nine-member Main Basin Watermaster. Six of those
members are nominated by water producers (producer members) and three members
(public members) are nominated by the Upper Water and the San Gabriel Valley
Municipal Water District (San Gabriel District), which overlie most of the Basin. The nine-
member board employs a staff, an attorney and a consulting engineer. The Main Basin
Watermaster holds public meetings on a regular monthly basis throughout the year.
The Main Basin Judgment does not restrict the quantity of water, which parties may
extract from the Main Basin. Rather, it provides a means for replacing all annual
extractions in excess of a Party's annual right to extract water with Supplemental Water.
The Main Basin Watermaster annually establishes an Operating Safe Yield for the Main
Basin which is then used to allocate to each Party its portion of the Operating Safe Yield
which can be produced free of a Replacement Water Assessment. If a producer extracts
water in excess of its right under the annual Operating Safe Yield, it must pay an
assessment for Replacement Water, which is sufficient to purchase one acre-foot of
Supplemental Water to be spread in the Main Basin for each acre-foot of excess
production. All water production is metered and is reported quarterly to the Main Basin
Watermaster.
In addition to Replacement Water Assessments, the Main Basin Watermaster levies an
Administration Assessment to fund the administration of the Main Basin management
program under the Court Judgment and a Makeup Obligation Assessment in order to fulfill
the requirements for any makeup Obligation under the Long Beach Judgment and to
supply fifty percent of the administration costs of the River Watermaster service. The
Main Basin Watermaster levies an In-lieu Assessment and may levy special
Administration Assessments.
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Water rights under the Main Basin Judgment are transferable by lease or purchase so
long as such transfers meet the requirements of the Judgment. There is also provision
for Cyclic Storage Agreements by which Parties and non-parties may store imported
supplemental water in the Main Basin under such agreements with the Main Basin
Watermaster pursuant to uniform rules and conditions and Court approval.
The Main Basin Judgment provides that the Main Basin Watermaster will, insofar as
practicable, spread imported water in the Main Basin to maintain the groundwater
elevation at the Key Well above 200 feet. Under the terms of the Long Beach Judgment,
any excess surface flows that pass through the Main Basin at Whittier Narrows to the
Lower Area (which is then conserved in the Lower Area through percolation to
groundwater storage) is credited to the Upper Area as Usable Surface Flow.
Main Basin - Description
The Main San Gabriel Basin is located within the San Gabriel Valley, which is located in
southeastern Los Angeles County and is bounded on the north by the San Gabriel
Mountains; on the west by the San Rafael and Merced Hills, on the south by the Puente
Hills and the San Jose Hills, and on the east by a low divide between the San Gabriel
River system and the Upper Santa Ana River system, as shown on Figure 3.
The San Gabriel River and its distributary, the Rio Hondo, drain an area of about 490
square miles upstream of Whittier Narrows. Whittier Narrows is a low gap between the
Merced and Puente Hills, just northwest of the City of Whittier, through which the San
Gabriel River and the Rio Hondo flow to the coastal plain of Los Angeles County. Whittier
Narrows is a natural topographic divide and a subsurface restriction to the movement of
groundwater between the Main Basin and the Coastal Plain. The approximately 490
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square miles of drainage area upstream of Whittier Narrows consists of about 167 square
miles of valley lands and about 323 square miles of mountains and foothills.
The Main Basin includes essentially the entire valley floor of the San Gabriel Valley with
the exception of the Raymond Basin and Puente Basin. The boundaries of the Main
Basin are the Raymond Basin on the northwest, the base of the San Gabriel Mountains
on the north, the groundwater divide between San Dimas and La Verne and the lower
boundary of the Puente Basin on the east, and the common boundaries between Upper
Water and Central District through Whittier Narrows on the southwest. The common
water supply of the Main Basin does not include the Raymond Basin, the area northerly
of Raymond Hill Fault, which was adjudicated in the Pasadena v. Alhambra case
(Superior Court of the County of Los Angeles, 1944). The Puente Basin, although
tributary to the Main Basin, is not included in the Main Basin administered by the Main
Basin Watermaster.
The Main Basin (administered by the Main Basin Watermaster) is a large groundwater
basin replenished by stream runoff from the adjacent mountains and hills, by rainfall
directly on the surface of the valley floor, subsurface inflow from Raymond Basin and
Puente Basin, and by return flow from water applied for overlying uses. Additionally, the
Main Basin is replenished with imported water. The Main Basin serves as a natural
storage reservoir, transmission system and filtering medium for wells constructed therein.
There are three municipal wholesale water districts overlying and/or partially overlying the
Main Basin. The three districts are Upper Water, San Gabriel District, and Three Valleys
Municipal Water District (Three Valleys District).
Urbanization of the San Gabriel Valley began in the early part of the twentieth century,
but until the 1940s, agricultural land use occupied more area than residential and
commercial land use. After World War II, agricultural areas reduced rapidly and tend to
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be located in the easterly portion of the Main Basin and along power transmission rights
of way adjacent to the San Gabriel River. Agricultural plots are discontinuous and
relatively small. There are several major industrial areas adjacent to the San Gabriel
River and within other portions of the valley. The greatest area of land use in the valley
is for residential and commercial purposes. DWR Bulletin 118 does not identify the Main
Basin as being in overdraft.
Main Basin - Geology
The Main Basin consists of a roughly bowl-shaped depression of bedrock, filled over
millions of years with alluvial deposits. This bowl-shaped depression is relatively deep;
the elevation at the base of the groundwater reservoir declines from about 800 feet above
mean sea level (MSL) in the vicinity of San Dimas, at the northeast corner of the Main
Basin, to about 2,200 feet below MSL in the vicinity of South El Monte (DWR, 1966, Plate
II).
Most of the alluvium deposited within this depression is debris from the San Gabriel
Mountains, washed and blown down from the side of the mountains over time. This
process has also resulted in the materials of the Main Basin varying in size from relatively
coarse gravel nearer the mountains to fine and medium-grained sand containing silt and
clay as the distance from the mountains increases. The principal water-bearing
formations of the Main Basin are unconsolidated and semi-consolidated sediments, which
vary in size from coarse gravel to fine-grained sands. The interstices between these
alluvial particles throughout the Main Basin fill with water and transmit water readily to
wells. The thickness of the water-bearing materials in the Main Basin ranges from 200 to
300 feet in the northeastern portion of the Main Basin near the mountains (DPW, 1934,
page 141) to nearly 4,000 feet in the South El Monte area (DWR, 1966, page 31).
The soils overlying the Main Basin average about six feet in depth. Soil depths are
generally greater at the perimeter of the valley and decrease toward the center along the
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San Gabriel River. These soils are residual, formed in place through chemical,
mechanical and plant weathering processes. The infiltration rates of these soils are
greater along the natural channels and their adjacent flood plains. Lower infiltration rates
are found in the perimeter areas of the valley. Since the valley is mostly urbanized, a
significant portion of the area has been paved and many miles of stream channel have
been lined for flood control purposes, thus decreasing infiltration of water through
streambeds. Detailed basin geology is discussed in the report entitled “Planned
Utilization of Ground Water Basins, San Gabriel Valley, Appendix A: Geo-hydrology”
(DWR, 1966).
Main Basin - Hydrology
The total fresh water storage capacity of the Main Basin is estimated to be about 9.5
million acre-feet. Of that, about 1,100,000 acre-feet have been used historically in Main
Basin operations. The change in groundwater elevation at the Baldwin Park Key Well4
Key Well (Key Well) is representative of changes in groundwater in the Main Basin. One
foot of elevation change at the Key Well is roughly the equivalent of about 8,000 acre-
feet of water storage. The historical high groundwater elevation was recorded at over
329.1 feet in April 1916, at which time Main Basin storage was estimated to be about
8,700,000 acre-feet. The historical low was recorded in November 2018 at 169.4 feet, at
which time Main Basin storage was estimated to be about 7,400,000 acre-feet. The Key
Well hydrograph illustrates the cyclic nature of basin recharge and depletion. The
hydrograph also illustrates the dramatic recharge capability of the Main Basin during wet
periods.
4 The Baldwin Key Well is a water-level monitoring well located in the City of Baldwin Park used to
determine when imported water may or may not be spread in the Basin.
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Generally, water movement in the Main Basin is from the San Gabriel Mountains on the
north to Whittier Narrows to the southwest. Groundwater movement in the northern and
northeastern regions of the Main Basin is affected by faulting. For example, the Raymond
Fault located in the northwesterly portion of the Main Basin separates the Raymond Basin
from the Main Basin.
The Main Basin is an unconfined aquifer. Although clay deposits appear mixed with the
soils in several locations in the Main Basin and there are various clay lenses throughout
the Main Basin, they do not coalesce to form a single impermeable barrier for the
movement of subsurface water. The Main Basin therefore operates as a single,
unconfined aquifer. As previously mentioned, a thorough discussion of basin
hydrogeology is contained in the report “Planned Utilization of Ground Water Basins, San
Gabriel Valley, Appendix A: Geo-hydrology” (DWR, 1966).
Within the Main Basin there are a number of identified sub-basins. These include the
Upper San Gabriel Canyon Basin, Lower San Gabriel Canyon Basin, Glendora Basin,
Foothill Basin, Way Hill Basin and San Dimas Basin. In addition, the Puente Basin is
tributary to the Main Basin from the southeast, between the San Jose and Puente Hills,
but is not included in the Main Basin adjudication.
Main Basin – Groundwater Replenishment
The major sources of recharge to the Main Basin are direct penetration of rainfall on the
valley floor, percolation of runoff from the mountains, percolation of imported water and
return flow from applied water. Rainfall occurs predominantly in the winter months and is
more intense at higher elevations and closer to the San Gabriel Mountains.
The magnitude of annual recharge from direct penetration of local rainfall and return flow
from applied water is not easily quantifiable. Percolation of runoff from the mountains
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and valley floor along with percolation of imported water has only been estimated. The
DPW maintains records on the amount of local and imported water conserved in water
spreading facilities and stream channels.
The San Gabriel River bisects the Main Basin. The San Gabriel River originates at the
confluence of its west and east forks in the San Gabriel Mountains. It flows through the
San Gabriel Canyon and enters the Main Basin at the mouth of the canyon north of the
City of Azusa. The San Gabriel River flows southwesterly across the valley to Whittier
Narrows, a distance of about 15 miles. It exits San Gabriel Valley at Whittier Narrows,
and transverses the Coastal Plain in a southerly direction to reach the Pacific Ocean at
Alamitos Bay near the City of Long Beach.
The San Gabriel River is joined and fed by tributary creeks and washes. In the Main
Basin these include: Big Dalton Wash, which originates in the San Gabriel Mountains;
Walnut Creek, which originates at the northeast end of the San Jose Hills; and San Jose
Creek, which originates in the San Gabriel Mountains, but which travels around the
southerly side of the San Jose Hills through the Puente Narrows before joining the San
Gabriel River just above Whittier Narrows.
The channel of the San Gabriel River bifurcates in the upper middle portion of the Main
Basin, forming a channel to the west of and parallel to the San Gabriel River, known as
the Rio Hondo. Tributaries draining the westerly portion of the Main Basin, including
Sawpit Wash, Santa Anita Wash, Eaton Canyon Wash, Rubio Wash and Alhambra Wash,
all of which originate in the San Gabriel Mountains or the foothills, feed the Rio Hondo.
The Santa Anita Wash, Eaton Canyon Wash, Rubio Wash and Alhambra Wash all cross
the Raymond Basin area before entering the Main Basin. The channel of the Rio Hondo
passes through Whittier Narrows westerly of the San Gabriel River, and then flows
southwesterly to join the Los Angeles River on the Coastal Plain.
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To protect residents of the San Gabriel Valley from flooding that can result during periods
of intensive rainfall, the DPW and the U.S. Army Corps of Engineers (Corps of Engineers)
have constructed an extensive system of dams, debris basins, reservoirs and flood
control channels. The dams and reservoirs also operate as water conservation facilities.
The dams and reservoirs that control the flow of the San Gabriel River and the Rio Hondo
include: Cogswell Reservoir on the west fork of the San Gabriel River, San Gabriel
Reservoir at the confluence of the west and east forks of the San Gabriel River, Morris
Reservoir near the mouth of the San Gabriel Canyon, Santa Fe Reservoir in the northerly
portion of the Main Basin and Whittier Narrows Reservoir at the southwestern end of the
San Gabriel Valley.
Many of the stream channels tributary to the San Gabriel River have been improved with
concrete banks (walls) and concrete-lined bottoms. These stream channel improvements
have significantly reduced the area of previous stream channels and reduce Main Basin
recharge. A number of off-stream groundwater replenishment facilities have been
established along these stream channels to offset such reductions in recharge. Some of
these facilities are accessible to imported water supplies, while some facilities receive
only local runoff.
The paths of the surface streams are mirrored in the soils and in the direction of
groundwater movement in the Main Basin. The tributary creeks and washes, carrying
smaller amounts of water, generally flow toward the center of the San Gabriel Valley,
while the direction of flow of the major streams, the San Gabriel River and the Rio Hondo,
is from the mountains in the north to Whittier Narrows in the southwest. In similar fashion,
the primary direction of groundwater movement in the Main Basin is from the north to the
southwest, with contributing movement generally from the east and west toward the
center of the Main Basin. The greatest infiltration and transmissivity rates of soils in the
Main Basin are from north to south, with the maximum rates found in the center of the
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valley along the stream channels. Generally, the Main Basin directs groundwater to the
southwest through Whittier Narrows.
The Main San Gabriel Basin has a freshwater storage capacity of about 8.7 million acre-
feet when the Key Well groundwater elevation is at 329.1 feet, of which about 125 feet of
elevation change, or about 1,000,000 acre-feet, has been used for historical Basin
operations. Local runoff is stored in a series of reservoirs operated by DPW and diverted
into spreading grounds to replenish the groundwater supply. Groundwater recharge
occurs every year and is exhibited as increasing water levels. High rainfall years can be
identified as increases in the groundwater level of 30 feet or more in one year.
In addition to groundwater replenishment with local storm runoff, the Watermaster
maintains records of each producer’s water rights and annual production. Although there
is no limit on the quantity of water that may be produced, production in excess of a water
right is subject to a Replacement Water assessment. Watermaster uses funds collected
from producers’ overproduction to purchase imported water from municipal water districts.
Upper Water and Three Valleys District obtain their water from MWD. San Gabriel District
has its own contract for State Water Project (SWP) water. Watermaster coordinates
purchase and delivery of imported water to replenish the ground water basin, thus
offsetting the producers’ overproduction and making the Basin whole.
Groundwater Management Plan
The Main Basin has been adjudicated and management of the local water resources
within the Main Basin is based on that adjudication. Management of the water resources
in the Main Basin is based upon Watermaster services under two Court Judgments:
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River Watermaster5 and Main Basin Watermaster6. The City is a party to both Judgments
and as such participates in these cases. The City also participates in the Main Basin
management described in the Main Basin Watermaster document entitled “Five-Year
Water Quality and Supply Plan.”
The following sections provide a description of the two Judgments and the Five-Year
Water Quality and Supply Plan that make up the groundwater management plan for the
Main Basin. In addition, this section describes Upper Water’s and San Gabriel Basin
Water Quality Authority’s (WQA) policies to promote groundwater basin clean-up.
Operations of the Groundwater Basin
Through the Long Beach Judgment and the Main Basin Judgment, operations of the Main
Basin are optimized to conserve local water to meet the needs of the parties of the Main
Basin Judgment.
Typically, water producers within Upper Water rely upon groundwater from Main Basin
for their water supply. The City of Alhambra has agreed to receive treated, imported
water as part of the Cooperative Water Exchange Agreement (CWEA) to reduce the
groundwater extractions from the western portion of the Main Basin and the associated
drawdown concerns.
Imported water for groundwater replenishment is delivered through the flood control
channels and diverted and spread at spreading grounds through Main Basin
Watermaster’s agreement with DPW. Groundwater replenishment utilizes imported water
5 Board of Water Commissioners of the City of Long Beach, et al., v. San Gabriel Valley Water Company,
et al., Los Angeles County Case No. 722647, Judgment entered September 24, 1965.
6 Upper San Gabriel Valley Municipal Water District v. City of Alhambra, et al., Los Angeles County Case
No. 924128, Judgment entered January 4, 1973.
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and is considered Replacement Water under the terms of the Main Basin Judgment. In
addition, it can be stored in the Main Basin through Cyclic Storage agreements,
authorized by terms of the Main Basin Judgment, but such stored water may be used only
to supply Supplemental Water to the Main Basin Watermaster.
The Main Basin Watermaster has entered into a Cyclic Storage Agreement with each of
the three municipal water districts. One is with MWD and Upper Water, which permits
MWD to deliver and store imported water in the Main Basin in an amount not to exceed
200,000 acre-feet for future Replacement Water use. The second Cyclic Storage
Agreement is with Three Valleys District and permits Three Valleys District to deliver and
store up to 50,000 acre-feet for future Replacement Water use. The third is with San
Gabriel District and permits San Gabriel District to deliver and store up to 50,000 acre-
feet for future Replacement Water use.
Imported Makeup Water has been delivered to lined stream channels and conveyed to
the Lower Area. Makeup Water is required to be delivered to the Lower Area by the
Upper Area when the Lower Area entitlement under the Long Beach Judgment exceeds
the usable water received by the Lower Area. Imported water is used to fulfill the Makeup
Water Obligation when the amount of Makeup Water cannot be fulfilled by reimbursing
the Lower Area interests for their purchase of recycled water. The amount of recycled
water for which reimbursement may be made as a delivery of Makeup Water is limited by
the terms of the Long Beach Judgment to the annual deficiency in Lower Area Entitlement
water or to 14,735 acre-feet, whichever is the lesser quantity.
Salt and Nutrient Management Plan
On February 9, 2009, the State Water Board adopted Resolution 2009-0011 that created
the “Recycled Water Policy”. The Recycled Water Policy recognized that “…collapse of
the Bay Delta ecosystem, climate change, and continuing population growth have
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combined with a severe drought on the Colorado River, and failing levees in the Delta, to
create a new reality that challenges California’s ability to provide the clean water need for
a healthy environment, a healthy population and a healthy economy, both now and in the
future.” The Recycled Water Policy encourages appropriate water recycling, water
conservation and use of stormwater to increase water supplies within California.
The primary goal of the San Gabriel Valley Salt and Nutrient Management Plan (SNMP)
is to assist the Main Basin Watermaster and participating/potential stakeholders to comply
with the Recycled Water Policy regarding the use of the recycled water from municipal
wastewater treatment facilities as a safe source of water supply, while maintaining the
water quality objectives for salt and nutrients in the Basin Plan established by the Los
Angeles Regional Water Quality Control Board. The primary objective of the SNMP is to
comply with the specific requirements described in the Recycled Water Policy. They
include:
1) Characterization of the Main Basin,
2) Identification of sources of salt, nutrients, and constituents of emerging concern
(CECs) (when deemed necessary by the Recycled Water Policy) and their fate and
transport,
3) Estimation of salt, nutrients, and CECs (if necessary) loadings and assimilative
capacities,
4) Identification of water recycling and stormwater recharge/use goals and objectives,
5) Verification of compliance with Resolution No. 68-16 through antidegradation
analyses, and
6) Development of a monitoring plan to verify compliance with the Basin water quality
objectives.
The SNMP reviewed the geology, hydrology and hydrogeology of the San Gabriel Basin,
along with the institutional and management structure for the San Gabriel Basin. Total
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dissolved solids (TDS), Nitrate, Sulfate, and Chloride were identified as the primary
constituents of concern. Sources of loading (precipitation, subsurface inflow, infiltration of
applied water, storm runoff and untreated imported water replenishment) and unloading
(groundwater pumping and subsurface outflow) were included in a spreadsheet computer
model, along with average water quality data for TDS, Nitrate, Sulfate, and Chloride, on
an annual basis.
The SNMP proposed to use the Main Basin Watermaster’s existing Title 22 water quality
monitoring program for groundwater and San Gabriel River water, with increased
frequencies of monitoring for Total Dissolved Solids and nitrate, to satisfy the monitoring
plan requirement of the SNMP. The following are recommendations for on-going salt and
nutrient management in the San Gabriel Basin:
x Regularly update the SNMP spreadsheet data so that impacts of potential future
projects on salt and nutrient loading may be evaluated.
x Continue to collect water quality data throughout the San Gabriel Basin.
x Continue to meet with stakeholders on a regular basis to coordinate San Gabriel
Basin management activities with an emphasis on stormwater runoff
replenishment and continued use of SWP water for groundwater replenishment
In-Lieu Program
During calendar year 2014, the ability to deliver Supplemental Water (State Water Project
water and Colorado River water) to replenish the Basin was severely limited.
Consequently, during fiscal year 2014-15, Watermaster developed and implemented a
program to have Producers purchase additional treated imported water for direct delivery
in-lieu of pumping groundwater (In-Lieu Program), in an effort to reduce the amount of
groundwater pumped from the Basin. The Watermaster uses the In-Lieu Assessment on
all production to fund the additional direct cost incurred by a producer participating in the
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In-Lieu Program. Watermaster has implemented this program during fiscal year 2014-15
and 2015-16.
Supplemental Water Reliability Storage Program (RDA)
The 2012 Main Basin Judgment Amendments provided the Main Basin Watermaster with
increased management flexibility and adaptability; and provided more discretion in
making Basin management decisions. A key component of the Judgment Amendments
was the new Water Resource Development Assessment to be levied on all production.
The Supplemental Water Reliability Storage Program provides a process for the Main
Basin Watermaster to generate funds to purchase and store Supplemental Water in the
Basin to be used (applied) when there are limitations on the availability of Supplemental
Water from the Responsible Agencies. As a result of the severe long-term drought
conditions resulting in significant reductions on the quantity of local water replenishment
to the Basin, the Main Basin Watermaster expanded RDA into the Supplemental Water
Stormwater Augmentation Program described below.
Supplemental Water Stormwater Augmentation Program
The Water Resource Development Assessment for Stormwater Augmentation Program
was developed by the Main Basin Watermaster to help manage Basin water supplies
under the perceived “worst case” hydrologic conditions, which was assumed to be two
additional consecutive 5-year droughts, using the same hydrologic conditions as the
recent FY 2011-12 through 2015-16 severe drought. Based upon ten (10) additional
consecutive years of drought, the new RDA II Program is intended to purchase imported
replenishment water (when available), for stormwater augmentation, to maintain the
Baldwin Park Key Well (Key Well) elevation above 180 feet by the end of the tenth year.
This Key Well elevation essentially ensures continued Basin water supply to the Basin
Producers under a worst case, 15-year sustained drought. The RDA II Program has an
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assessment of $175/AF on all FY 2024-25 production and is planned to also be $175/AF
on all FY 2025-26 production with a potential to increase in the next three to five years.
The Main Basin Watermaster will use the RDA II funds to purchase untreated imported
water to replenish the Main Basin for the “general benefit” of all Producers within the Main
Basin. Unlike the original RDA (Supplemental Water Replenishment Storage Program),
which is a Watermaster pre-purchase of Replacement Water, the RDA II untreated
imported water will supplement local stormwater replenishment, enhance overall Basin
conditions, and have “no right of recovery” using a water right, by any Main Basin
producer.
MWD Letter Agreement
Since 2017, Watermaster, Upper Water, the Three Valleys District, and MWD entered
into a series of letter agreements to pre-deliver untreated imported water in support of
Basin management programs (Letter Agreement). Through these agreements, MWD has
delivered a cumulative total of 405,517.5 acre-feet of imported water. While deliveries
have varied depending on hydrological conditions and local stormwater capture, these
agreements have provided a critical means of supplementing the Basin’s supplies over
time.
During fiscal year 2023–24, Watermaster and Upper Water entered into a fourth
agreement with MWD to pre-deliver an additional 87,000 acre-feet of untreated imported
water during calendar year 2024. In addition, Watermaster and Three Valleys District
entered into a separate agreement with MWD to pre-deliver about 35,000 acre-feet during
calendar year 2024. During fiscal year 2024–25, Watermaster and Upper Water entered
into a fifth agreement with MWD to pre-deliver an additional 86,000 acre-feet of untreated
imported water during calendar year 2025.
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Three Year Purchased Water Plan
On June 21, 2012, the Superior Court of the State of California for the County of Los
Angeles (Court) approved certain proposed Judgment amendments. Some of these
Judgment amendments help Watermaster address Supplemental Water supply
concerns. One of the amendments, Exhibit H(3)(d), requires that “…on or before
November 1 of each year, Watermaster shall prepare and distribute to the Responsible
Agencies a three-year projection of its Supplemental Water purchases from each agency.
Watermaster shall, to the extent feasible, coordinate the tentative schedule for delivery
and payment of those purchases with each agency.”
Judgment Amendment, Section 45(b)(7), allows Watermaster to “…levy an Assessment
on all Pumping, as determined through Rules and Regulations … to support the purchase,
financing, and/or development of new or additional Supplemental Water sources, in
cooperation with one or more Responsible Agencies as appropriate.” Section 45(b)(7)
established the “Water Resource Development Assessment” for the purchase or
development of additional Supplemental Water supplies. Based on these Judgment
amendments, Main Basin Watermaster also amended its Rules and Regulations to
include a policy/criteria to develop the “Three-Year Purchased Water Plan” (Three-Year
Plan). Under Section 26(d)(5) of the Rules and Regulations, the first priority for spreading
of Supplemental Water is “…Supplemental Water ordered by Watermaster from
Responsible Agencies for direct delivery to the Basin as Replacement Water…”.
Recognizing many Producers currently pre-purchase Supplemental Water for delivery
into their Cyclic Storage accounts, those pre-purchases are considered to have the same
priority as Replacement Water.
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Exhibit M of Watermaster’s amended Rules and Regulations7 provides the policy/criteria
for the “Three-year Purchased Water Plan,” and requires Main Basin Watermaster to
estimate Supplemental Water purchases from the Responsible Agencies for each of the
three subsequent years. The policy/criteria indicate estimated Supplemental Water
purchases may be based on the following:
1) The first year shall be, at a minimum, the total Replacement Water requirement for the
three Responsible Agencies (Upper Water, San Gabriel District, and Three Valleys.
2) The second and third years may be estimated as follows:
a) Operating Safe Yield (OSY) established by Watermaster for the current fiscal year
and next succeeding years;
b) Alternative projections of the OSY;
c) Evaluation of potential wet, average, and dry hydrologic conditions;
d) Future groundwater production provided by or estimated for each producer; and
e) Depending on Basin conditions, Watermaster may consider additional factors as
necessary.
As a result of the negotiated pre-delivery of significant MWD imported replenishment
water by Watermaster, and subsequently transferred by MWD to Upper Water and Three
Valleys District, the above policy/criteria has been superseded by this delivery of imported
water to supplement local rainfall and runoff replenishment.
Five-Year Water Quality and Supply Plan
The Main Basin Watermaster was created in 1973 to resolve water issues that had arisen
among water users in the San Gabriel Valley. Main Basin Watermaster’s mission was to
generally manage the water supply of the Main Basin. During the late 1970s and early
7 https://www.watermaster.org/about-us (Rules and Regulations)
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1980s, significant groundwater contamination was discovered in the Main Basin. The
contamination was caused in part by past practices of local industries that had carelessly
disposed of industrial solvents referred to as Volatile Organic Compounds (VOCs) as well
as by agricultural operations that infiltrated nitrates into the groundwater. Cleanup efforts
were undertaken at the local, state, and federal level.
Local water agencies adopted a joint resolution in 1989 regarding water quality issues
that stated Main Basin Watermaster should coordinate local activities aimed at preserving
and restoring the quality of groundwater in the Main Basin. The joint resolution also called
for a cleanup plan. In 1991, the Court granted Main Basin Watermaster the authority to
control pumping for water quality purposes. Accordingly, Main Basin Watermaster added
Section 28 to its Rules and Regulations regarding water quality management. The new
responsibilities included development of a Five-Year Water Quality and Supply Plan8,
updating it annually, submitting it to the California Regional Water Quality Control Board,
Los Angeles Region, and making it available for public review by November 1 of each
year.
Main Basin Watermaster prepares and annually updates the Five-Year Water Quality and
Supply Plan in accordance with the requirements of the Section 28 Rules and
Regulations. The objective is to coordinate groundwater-related activities so that both
water supply and water quality in the Main Basin are protected and improved. Many
important issues are detailed in the Five-Year Plan, including how Main Basin
Watermaster plans to:
1. Monitor groundwater supply and quality;
2. Develop projections of future groundwater supply and quality;
8 https://www.watermaster.org/reports
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3. Ensure adequate supplemental water is available for groundwater
replenishment;
4. Review and cooperate on cleanup projects, and provide technical assistance
to other agencies;
5. Assure that pumping does not lead to further degradation of water quality in the
Basin;
6. Address Perchlorate, N-nitrosodimethylamine (NDMA), and other emerging
contaminants in the Basin;
7. Develop a cleanup and water supply program consistent with the U.S.
Environmental Protection Agency (USEPA) plans for its San Gabriel Basin
Superfund sites; and
8. Coordinate and manage the design, permitting, construction, and performance
evaluation of the Baldwin Park Operable Unit (BPOU) cleanup and water
supply plan.
The Main Basin Watermaster, in coordination with Upper Water, has worked with state
and federal regulators, along with local water companies to clean up water supplies.
Section 28 of the Main Basin Watermaster’s Rules and Regulations require all producers
(including the City) to submit an application to 1) construct a new well, 2) modify an
existing well, 3) destroy a well, or 4) construct a treatment facility. The Main Basin
Watermaster prepares a report on the implications of the proposed activity. As a party to
the Main Basin Judgment, the City reviews a copy of these reports and is provided the
opportunity to submit comments on the proposed activity before the Main Basin
Watermaster Board takes final action.
Water Quality Authority 406 Plan
The WQA was established by the State Legislature on February 11, 1993 to develop,
finance and implement groundwater treatment programs in the Main Basin. Section 406
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of the WQA Act requires the WQA “to develop and adopt a basinwide groundwater quality
management and remediation plan” that is required to be consistent with the EPA’s
National Contingency Plan (“NCP”) and Records of Decision (“ROD”) and all requirement
of the Los Angeles Regional Water Quality Control Board (“LARWQCB”). According to
the WQA Act, the Section 406 Plan, which is incorporated in this Plan by reference, must
include:
1) Characterization of Basin contamination;
2) A comprehensive cleanup plan;
3) Strategies for financing the design, construction, operation and
maintenance of groundwater cleanup facilities;
4) Provision for a public information program; and
5) Coordination of activities with federal, state, and local entities.
WQA reviews and adopts the Section 406 Plan on an annual basis and as necessary,
makes revisions according to changing regulatory, political and/or funding environments.
In support of the Section 406 Plan, WQA also adopts an annual FY budget (July 1 through
June 30) which includes all projects (actual or planned) WQA is facilitating through its
participation during that time period. The budget identifies the various funding sources,
and combinations thereof, to ensure full funding for each project (capital and/or O&M) can
be achieved.
Main Basin – Historical and Projected Basin Production
The City’s currently produces groundwater from the Main Basin. The City’s share of the
Operating Safe Yield is 4.23099 percent. Over the past five years, the City has produced
9,425 AFY to 12,116 AFY (see Table 6-1), with an average of 10,545 AFY from the Main
Basin. The City’s projected production from the Main Basin, over the next 25 years in five-
year increments, is provided in Table 6-9.
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As discussed above, the Main Basin is managed by the Main Basin Watermaster. The
most recent amendments to the Main Basin Judgment were made in June 2012.
Historical fluctuation of the Key Well elevation illustrates that since the Main Basin was
adjudicated in 1973, it generally operated between an elevation 250 feet and 200 feet
above MSL. Furthermore, at an elevation of 169 feet above MSL at the Key Well, which
represents the historical low, the Main Basin has about 7,400,000 acre-feet of available
storage. During the period of management under the Judgment, significant drought
events have occurred from 1969 to 1977, 1983 to 1991, 1998 to 2004, 2006 to 2009, and
2011 to 2015. In each drought cycle the Main Basin has been managed to maintain water
levels.
RAYMOND BASIN
Raymond Basin - Sustainable Groundwater Management Act
The Raymond Basin is identified as Basin Number 4-013 pursuant to DWR Bulletin 118.
The Sustainable Groundwater Management Act of 2014, identifies the Raymond Basin
as an adjudicated groundwater basin, is exempt from the requirements of developing a
Groundwater Sustainability Plan and subsequently was designated a very-low-priority
basin in DWR’s 2019 SGMA Basin Prioritization report. In compliance with SGMA, the
Raymond Basin Management Board submits its Annual Report to DWR.
Raymond Basin - Adjudication
In 1937, the City of Pasadena filed suit to adjudicate water rights of the Raymond Basin.
A copy of the Raymond Basin adjudication is located in Appendix H. DWR was retained
to prepare a Report of Referee which described the geology and hydrogeology of the
Raymond Basin and identified the Safe Yield of the Raymond Basin as 21,900 acre-feet.
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In 1950, the City of Pasadena requested the Safe Yield of the Raymond Basin to be re-
determined. Subsequently, the Court issued a Modification of Judgment on April 29, 1955
increasing the Safe Yield of the Raymond Basin to 30,622 acre-feet. This is referred to
as the “Decreed Right of 1955” and water rights for all parties are provided. On January
17, 1974, the second modification of the Raymond Basin Judgment was signed allowing
Parties credit for spreading of canyon diversions in spreading grounds in the vicinity of
the Arroyo Seco, Eaton Wash and Santa Anita Creek Canyon. On March 26, 1984, the
third modification of the Raymond Basin Judgment was signed establishing the Raymond
Basin Management Board as the Watermaster for the Raymond Basin.
The Raymond Basin Judgment adjudicated groundwater rights based on a long-term
average yield of the Raymond Basin. The Raymond Basin Judgment allows a party to
exceed its Decreed Right by no more than 10 percent, which will be deducted from the
following year’s total allowable extraction. Conversely, a party is not allowed to carryover
more than 10 percent of its Decreed Right to a subsequent year.
Raymond Basin – Description
The Raymond Basin is located in Los Angeles County about 10 miles north-easterly of
downtown Los Angeles. Raymond Basin is a wedge in the northwesterly portion of the
San Gabriel Valley and is bounded on the north by the San Gabriel Mountains, on the
west by the San Rafael Hills and is separated from the Main San Gabriel Basin on the
southeast by the Raymond Fault. The Raymond Basin is divided into an eastern unit,
which is the Santa Anita sub-area, and the Western unit which is the Pasadena sub-area
and the Monk Hill Basin. The location of the Raymond Basin and the subareas, as shown
on Figure 4, the surface area of Raymond Basin is about 40.9 square miles. The principal
streams in the Raymond Basin are the Arroyo Seco, Eaton Wash and Santa Anita Wash.
The Arroyo Seco drains to the Los Angeles River, while Eaton Wash and Santa Anita
Wash drain to the Rio Hondo, a distributary of the San Gabriel River.
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The geology of the Raymond Basin is described in detail in the “Report of Referee”
prepared in 1943 by the State of California Division of Water Resources. The Raymond
Basin is roughly triangular in shape. Its northern boundary, about twelve miles in length,
is formed by a portion of the southerly front of the San Gabriel Mountains. The western
boundary of the Raymond Basin is about eight miles long and is also composed of the
same Basement Complex rocks which form the mountains and are continuous at depth,
together with a small area of marine Tertiary sediment at the southern end. The Raymond
Fault, the southern boundary of the triangle, crosses the Valley floor for a distance of
about nine miles, connecting a granitic spur from the mountains at the eastern end of the
Raymond Basin with Tertiary sediments outcropping in its southwestern corner.
The Raymond Fault separates Raymond Basin from the Main San Gabriel Basin. The
fault zone is not completely impervious and groundwater can flow across this boundary
into the Main Basin, particularly in the northeasterly portion of the boundary. The source
of natural groundwater supply to the Raymond Basin is direct rainfall, percolation from
surface runoff from the northern and western sides, and presumably underground
percolation of water from the mountain mass to the alluvium.
DWR describes the hydrogeology of the Raymond Basin in its Bulletin 118 report, Basin
Number 4-023. According to the report, the water-bearing materials of the Raymond
Basin are dominated by unconsolidated Quaternary alluvial gravel, sand, and silt
deposited by streams flowing out of the San Gabriel Mountains. Younger alluvium
typically follows active streambeds and reaches a maximum thickness of about 150 feet.
Older alluvium generally thickens southward from the mountain front, reaching a
maximum of about 1,140 feet near Pasadena, then thins to about 200 feet near the
Raymond Fault. However, confined groundwater conditions have existed locally in the
Raymond Basin, particularly along the Raymond Fault near Raymond Hill where layers
of finer grained sediments become more abundant.
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The Raymond Fault trends east-northeast and acts as a groundwater barrier along the
southern boundary of the Raymond Basin. This fault acts as a complete barrier along its
western end and becomes a less effective barrier at its eastward end. East of Santa Anita
Wash, this fault ceases to be an effective barrier and the flow of groundwater southward
into the Main Basin becomes essentially unrestricted. A north-trending divide paralleling
the Eaton Wash separates both surface and subsurface water flow in the eastern portion
of the Raymond Basin. The water level is higher on the eastern side of this divide, ranging
from 300 feet higher in the north to about 50 feet higher in the south. Monk Hill, an
emergent mound of consolidated bedrock within the Raymond Basin, causes
groundwater to flow around it, but does not appreciably change the regional flow pattern.
Groundwater elevation contour maps for the Raymond Basin are presented in the
Raymond Basin Annual Reports9.
Natural recharge to the Raymond Basin is mainly from direct percolation of precipitation
and percolation of ephemeral stream flow from the San Gabriel Mountains in the north.
The principal streams bringing surface inflow are the Arroyo Seco, Eaton Creek and
Santa Anita Creek. Some stream runoff is diverted into spreading grounds and some is
impounded behind small dams allowing the water to infiltrate and contribute to
groundwater recharge of the Raymond Basin. An unknown amount of underflow enters
the Raymond Basin from the San Gabriel Mountains through fracture systems.
No recent estimates of available groundwater storage have been made for in the
Raymond Basin. DWR (1971) study estimated the available stored water to be 1,000,000
acre-feet in 1970, leaving about 450,000 acre-feet of storage space available.
9 https://www.raymondbasin.org/reports
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Groundwater quality within the Raymond Basin is generally good quality with regards to
most constituents except for high fluoride concentrations in the foothills and high nitrate
concentrations in the Monk Hill and Pasadena Subareas. Volatile Organic Compounds
including Trichloroethylene (TCE) and Tetrachloroethylene (PCE) have been detected in
the Raymond Basin (particularly near the Arroyo Seco). In 1997, Perchlorate was first
detected in several monitoring wells at the National Aeronautics and Space
Administration’s (NASA) Jet Propulsion Laboratory (JPL) Superfund Site. Additionally,
the Raymond Basin Management Board monitors for Hexavalent Chromium and other
constituents to manage water quality effectively in the Raymond Basin.
Raymond Basin - Historical Production
The Decreed Right of 1955 provided the City with water rights to 2,118.0 AFY from the
Pasadena Subarea and with water rights to 3,526.0 AFY from the Santa Anita Subarea.
Due to recent multiple dry year conditions, the Raymond Basin Management Board has
phased in a 30 percent reduction requirement over five years for all Decreed Rights to
the Pasadena Subarea, beginning fiscal year 2009-10. As a result, the City’s current
adjusted right to the Pasadena Subarea is 1,482.6 AFY (0.7 x 2,118.0 AFY). The
Raymond Basin Management Board also implemented the 500-foot level limitation for all
Decreed Rights to the Santa Anita Subarea in 2013. As a result, the City’s adjusted right
to the Santa Anita Subarea is 2,321.0 AFY. The City’s total adjusted water right in the
Raymond Basin is 3,803.6 AFY (1,482.6 AFY + 2,321.0 AFY). Over the past five years,
the City has produced 2,345 AFY to 2,939 AFY (see Table 6-1), with an average of 2,671
AFY from the Raymond Basin. The City’s projected production from the Raymond Basin,
over the next 25 years in five-year increments, is provided in Table 6-9.
SURFACE WATER
The City does not use surface water supplies to meet its water demands.
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STORMWATER
The City does not directly use stormwater to meet its water demands.
WASTEWATER AND RECYCLED WATER
CWC 10633R.
The plan shall provide, to the extent available, information on recycled water and its potential for
use as a water source in the service area of the urban water supplier. The preparation of the plan
shall be coordinated with local water, wastewater, groundwater, and planning agencies that
operate within the supplier’s service area, and shall include all of the following:
(a) A description of the wastewater collection and treatment systems in the supplier’s service area,
including a quantification of the amount of wastewater collected and treated and the methods
of wastewater disposal.
(b) A description of the quantity of treated wastewater that meets recycled water standards, is
being discharged, and is otherwise available for use in a recycled water project.
(c) A description of the recycled water currently being used in the supplier’s service area, including,
but not limited to, the type, place, and quantity of use.
(d) A description and quantification of the potential uses of recycled water, including, but not
limited to, agricultural irrigation, landscape irrigation, wildlife habitat enhancement, wetlands,
industrial reuse, potable reuse, and other appropriate uses, and a determination with regard
to the technical and economic feasibility of serving those uses.
(e) The projected use of recycled water within the supplier’s service area at the end of 5, 10, 15,
and 20 years, and a description of the actual use of recycled water in comparison to uses
previously projected pursuant to this subdivision.
(f) A description of actions, including financial incentives, which may be taken to encourage the
use of recycled water, and the projected results of these actions in terms of acre-feet of
recycled water used per year.
(g) A plan for optimizing the use of recycled water in the supplier’s service area, including actions
to facilitate the installation of dual distribution systems, to promote recirculating uses, to
facilitate the increased use of treated wastewater that meets recycled water standards, and
to overcome any obstacles to achieving that increased use.
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Discussion of wastewater collection, treatment, and recycled water use is included in this
chapter. Municipal recycled water is municipal wastewater that has been treated at a
municipal wastewater facility in a manner specified by the SWRCB-DDW to a specified
quality to enable it to be used again for a beneficial purpose. Municipal wastewater must
meet two requirements; it must be reused beneficially pursuant to Title 22 of the California
Code of Regulations and it must be reused in accordance with a Regional Water Quality
Control Board permit. Title 22 of the California Code of Regulations defines beneficial
reuse of recycled water as “...the use of recycled water that has been transported from
the point of treatment or production to the point of use without an intervening discharge
to water of the State....”
The City currently does not have access to recycled water supplies due to the lack of
infrastructure to convey recycled water to the City. Subject to the availability of recycled
water, the City would construct transmission and distribution facilities to deliver recycled
water to customers within its service area. Additional information regarding the potential
use of recycled water is provided below.
6.2.5.1 RECYCLED WATER COORDINATION
CWC 10633.
The plan shall provide, to the extent available, information on recycled water and its potential for
use as a water source in the service area of the urban water supplier. The preparation of the plan
shall be coordinated with local water, wastewater, groundwater, and planning agencies that
operate within the supplier’s service area…
The City does not have access to recycled water due to the lack of infrastructure to convey
recycled water supplies to the City. However, the City is a sub-agency, and is located
within the service area, of Upper Water, which provides recycled water service.
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Upper Water has developed a recycled water program to provide direct delivery of
recycled water to serve non-potable demands in the southerly-most portion of its service
area, thereby offsetting reliance on imported water supplies. Upper Water’s recycled
water program is in various stages ranging from completed projects to planned and
conceptual options. Recycled water supply is obtained from the two water reclamation
plants described in the Section 6.2.5.2.
6.2.5.2 WASTEWATER COLLECTION, TREATMENT, AND DISPOSAL
CWC 10633.
(a) A description of the wastewater collection and treatment systems in the supplier’s service
area, including a quantification of the amount of wastewater collected and treated and the
methods of wastewater disposal.
Wastewater generated by the City is treated by the Sanitation Districts of Los Angeles
County (LACSD). Wastewater is collected within the City’s local sewer collection system.
The City’s local sewers tie into one of LACSD’s regional trunk sewers crossing through
the City. The regional trunk sewer lines deliver wastewater to one or more water
reclamation plants owned by LACSD for treatment. The water reclamation plants are not
located within the City’s service area. The water reclamation plants serving the City
include the Whittier Narrows Water Reclamation Plant (WNWRP), the San Jose Creek
Water Reclamation Plant (SJCWRP), and the A.K. Warren Water Resource Facility
(formerly known as the Joint Water Pollution Control Plant), however, the percentage
breakdown between these three plants in treating the City’s wastewater in unknown.
LACSD estimates approximately 69 gallons of wastewater is generated per person per
day within LACSD’s service area. Based on a 2025 population of approximately 54,700
within the City, the estimated amount of wastewater collected within the City’s service
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area is approximately 4,227 AFY, as shown in Table 6-2. As indicated previously and in
Table 6-3, wastewater is not treated or disposed within the City’s service area.
The WNWRP began operations in 1962 and has a treatment capacity of about 15 million
gallons per day (MGD). During FY 2018-19, about 7.1 MGD of recycled water produced
at the WNWRP is used at 29 different reuse sites. The WNWRP provides coagulated,
filtered and disinfected tertiary effluent. All wastewater treated at the WNWRP meets
recycled water standards. Approximately 99 percent of treated water at the WNWRP is
reused in a recycled water project. The method of disposal when treated recycled water
is not used (non-recycled) is discharge to the San Gabriel River/Rio Hondo and eventually
flows to the ocean.
The SJCWRP, which began operations in 1971, has a treatment capacity of about 100
MGD and provides coagulated, filtered and disinfected tertiary effluent. Consequently,
approximately 24 percent of treated water effluent from the SJCWRP would be available
for subsequent recycled water projects. The SJCWRP plant serves a largely residential
population of approximately 1 million people. The method of disposal when treated
recycled water is not used (non-recycled) is discharge to the San Gabriel River/Rio Hondo
and eventually flows to the ocean.
The A.K. Warren Water Resource Facility, which began operation in 1928 in the City of
Carson, currently has a treatment capacity of about 400 MGD. The treatment level is
primary and secondary treatment with disinfection. The plant serves a population of
approximately 4.8 million people. Solids collected in primary and secondary treatment are
processed in anaerobic digestion tanks where bacteria break down organic material and
produce methane gas. Treated wastewater is ultimately disinfected prior to being
discharged to the Pacific Ocean. All water discharged to the ocean is monitored to ensure
compliance with applicable local, state, and federal standards for discharge water.
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6.2.5.3 RECYCLED WATER SYSTEM DESCRIPTION
CWC 10633.
(c) A description of the recycled water currently being used in the supplier’s service area,
including, but not limited to, the type, place, and quantity of use.
The City currently does not have access to recycled water supplies due to the lack of
infrastructure to convey recycled water to the City. Subject to the availability of recycled
water, the City would consider transmission and distribution facilities to deliver recycled
water to customers within its service area. However, the City prepared the “Draft Recycled
Water Feasibility Study” in November 2006 (See Appendix I), which identified potential
recycled water customers within the City.
6.2.5.4 CURRENT, PROJECT, AND PROJECTED RECYCLED WATER
USES
CWC 10633.
(b) A description of the recycled water currently being used in the supplier’s service area,
including, but not limited to, the type, place, and quantity of use. A description of the quantity
of treated wastewater that meets recycled water standards, is being discharged, and is
otherwise available for use in a recycled water project.
(d) A description and quantification of the potential uses of recycled water, including, but not
limited to, agricultural irrigation, landscape irrigation, wildlife habitat enhancement, wetlands,
industrial reuse, groundwater recharge, indirect potable reuse, and other appropriate uses,
and a determination with regard to the technical and economic feasibility of serving those
uses.
(e) The projected use of recycled water within the supplier’s service area at the end of 5, 10, 15,
and 20 years, and a description of the actual use of recycled water in comparison to uses
previously projected pursuant to this subdivision.
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The City’s “Draft Recycled Water Feasibility Study”, November 2006, identified potential
recycled water customers within the City based on recycled water use for large-volume
irrigation purposes (e.g. municipal parks, fields, golf courses, etc.). Recycled water use
factors were applied to overall water demands for these customers to determine the
potential recycled water demands. A proposed recycled distribution water pipeline route
was based on maximizing recycled water demands and minimizing pipeline and
infrastructure costs (See Appendix I).
Although the City has identified potential uses for recycled water, the City does not
anticipate it will have access to recycled water supplies over the next 25 years due to the
lack of infrastructure to convey recycled water to the City. Therefore, Table 6-4 and Table
6-5 are intentionally blank.
6.2.5.5 ACTIONS TO ENCOURAGE AND OPTIMIZE FUTURE
RECYCLED WATER USE
CWC 10633.
The plan shall provide, to the extent available, information on recycled water and its potential for
use as a water source in the service area of the urban water supplier. The preparation of the plan
shall be coordinated with local water, wastewater, groundwater, and planning agencies that
operate within the supplier’s service area, and shall include all of the following:
(g) A plan for optimizing the use of recycled water in the supplier’s service area, including actions
to facilitate the installation of dual distribution systems, to promote recirculating uses, to
facilitate the increased use of treated wastewater that meets recycled water standards, and
to overcome any obstacles to achieving that increased use.
Due to the lack of infrastructure to convey recycled water to the City, the City is not
planning or expanding recycled water use in the future within a specified timeframe, as
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indicated in Table 6-6. Methods by the City to encourage and optimize future recycled
water use are provided below.
The City’s “Draft Recycled Water Feasibility Study” identified potential funding sources.
Funding for construction, operation, maintenance, and replacement of facilities for the
proposed City’s recycled water distribution system would be obtained from federal, state,
and local sources, including City revenues.
The City’s “Draft Recycled Water Feasibility Study” also identified potential recycled water
customers within the City (e.g. municipal parks, fields, golf courses, etc.) and a proposed
recycled distribution water pipeline route was based on maximizing recycled water
demands and minimizing pipeline and infrastructure costs. The Study also identified
recycled water facilities, including recycled water distribution pipelines, booster pumps,
reservoirs, and backflow prevention assemblies, and identified potential funding sources
for these facilities. Although the proposed recycled water project is not projected to
change any land use or planning designations of the proposed recycled customers,
implementation of the proposed facilities may cause temporary and/or permanent
changes to the physical environment during construction. However, the Study indicates
mitigation measures are available for any potential air quality, water quality, hydrology,
soils, traffic, land use, and aesthetics impacts from implementation of the proposed
facilities.
The City’s “Draft Recycled Water Feasibility Study” identified LACSD’s WNWRP as the
preferred source of recycled water (although all WNWRP recycled water is currently
used). The WNWRP supplies recycled water to Upper Water’s Phase IIA recycled water
system (Whittier Narrows, Rosemead Extension, and the South El Monte Recycled Water
Expansion Project).
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Upper Water provides wholesale deliveries of recycled water to member agencies. Upper
Water supplies treated recycled water through Upper Water’s Phase I (Rose Hills), Phase
IIA (Whittier Narrows, Rosemead, and South El Monte), Phase IIB (City of Industry), and
La Puente Valley County Water District recycled water projects. Upper Water will continue
to study future recycled water expansion projects, including recycled water deliveries to
the City of Arcadia.
DESALINATED WATER OPPORTUNITIES
CWC 10631.
(g) Describe the opportunities for development of desalinated water, including, but not limited to,
ocean water, brackish water, and groundwater, as a long-term supply.
Main Basin
Groundwater produced from the Main Basin is low in TDS and does not require
desalination. The SWRCB-DDW recommended TDS level is 500 milligrams per liter
(mg/L) and water can be provided for long-term domestic use with TDS concentrations of
up to 1,000 mg/L. Recent water quality data indicates the TDS values for the City’s
groundwater wells are less than 500 mg/L. Due to the high quality (low TDS
concentration) of the groundwater, the City does not need to investigate the use of
desalination to develop or reestablish a new long-term supply. The City is currently not
considering the development of a desalinated water project. However, there may be
opportunities for use of desalinated ocean water as a potential water supply source in the
future, if needed, through coordination with other agencies that have ocean desalination
programs.
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Raymond Basin
The City pumps groundwater from the Raymond Basin which is low in TDS and does not
require desalination. The SWRCB-DDW recommended level is 500 milligrams per liter
and water can be provided for long-term domestic use with TDS concentrations of up to
1,000 mg/L. Recent water quality data indicates the TDS values for the City’s groundwater
wells are less than 500 mg/L. Due to the low TDS concentration of the groundwater from
the Raymond Basin, the City does not need to investigate the use of desalination as a
long-term supply. However, there may be opportunities for use of desalinated ocean
water as a potential water supply source in the future, through coordination with other
agencies that have ocean desalination programs.
WATER EXCHANGES AND TRANSFERS
CWC 10631.
(c) Describe the opportunities for development of desalinated water, including, but not limited to,
ocean water, brackish water, and groundwater, as a long-term supply.
6.2.7.1 EXCHANGES
Pursuant to DWR’s 2025 Final Guidebook, “Water exchanges are typically water
delivered by one water user to another water user, with the receiving water user providing
water in return at a specified time or when the conditions of the parties’ agreement are
met. Water exchanges can be strictly a return of water on a basis agreed upon by the
participants or it can include payment and the return of water.”
The City does not have any current or planned water exchange opportunities.
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6.2.7.2 TRANSFERS
As a Party to the Main Basin Judgment, the City can pump from the Main Basin. The Main
Basin Judgment does not restrict the quantity of groundwater that can be produced, but
provides for a Replacement Water assessment for production in excess of water rights.
In addition, the City has entered into a Cyclic Storage agreement, described in Section
6.2.2, with the Main Basin Watermaster to store imported water in the Main Basin for a
period of up to five years to be used to offset a future Replacement Water requirement.
6.2.7.3 EMERGENCY INTERTIES
The City has emergency interties (or interconnections) with other water agencies that
serve as short-term emergency exchange opportunities. Emergency interconnections are
distribution system interconnections between water agencies for use during critical
situations where one system or the other is temporarily unable to provide sufficient
potable water to meet its water demands and/or fire protection needs. An emergency
interconnection will allow a water system to continue serving water during critical
situations such as local water supply shortages as a result of earthquakes, fires,
prolonged power outages, and droughts. The City has the ability to receive water from
interconnections with the following water agencies:
x Golden State Water Company (8-inches, two way)
x Sunny Slope Water Company (6-inches, two way)
x San Gabriel Valley Water Company (4-inches, two way)
x California American Water Company (8-inches, two way)
x MWD – USG-6 Connection (one way- in)
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SUPPLY FROM STORAGE
Section 6.2.8 is not applicable. The City does not remove water from either surface
storage or underground storage for use (including surface water placed into storage in a
given year and retrieved in the following year).
OTHER
The City does not rely on any additional water supply sources.
FUTURE WATER PROJECTS
CWC 10631.
(f) Include a description of all water supply projects and water supply programs that may be
undertaken by the urban water supplier to meet the total projected water use, as established
pursuant to subdivision (a) of Section 10635. The urban water supplier shall include a detailed
description of expected future projects and programs that the urban water supplier may
implement to increase the amount of the water supply available to the urban water supplier in
normal and single-dry water years and for a period of drought lasting five consecutive water
years. The description shall identify specific projects and include a description of the increase
in water supply that is expected to be available from each project. The description shall include
an estimate with regard to the implementation timeline for each project or program.
In partnership with the City of Sierra Madre, the City is currently developing a new joint
well project (Goldring Well) located at the City of Arcadia Public Works Services
Department property. This project is expected to yield over 2,000 gpm (with 1,000 gpm
going to the City of Arcadia) from the Main Basin. The project is estimated to be completed
by 2027.
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The 2016 City of Arcadia Water Master Plan Update report also identified potential
reservoir, pipeline, and booster station projects.
In addition to Decreed Rights in the Raymond Basin and groundwater extraction from the
Main Basin, the City has the ability to obtain supplemental water supplies from the
following sources:
x Cyclic storage provisions allow producers, including the City, to store supplemental
water within the Main Basin for the purpose of supplying replacement water.
x The City can receive direct deliveries of treated imported water through its MWD
connection, USG-6, which has a capacity of 20 cubic feet per second (about
14,500 acre-feet per year if used continuously). The City does not typically use
service connection USG-6 because the City’s current collective groundwater
supplies are sufficient to meet water demands.
ENERGY USE
CWC 10631.2.
(a) In addition to the requirements of Section 10631, an urban water management plan shall
include any of the following information that the urban water supplier can readily obtain:
(1) An estimate of the amount of energy used to extract or divert water supplies.
(2) An estimate of the amount of energy used to convey water supplies to the water treatment
plants or distribution systems.
(3) An estimate of the amount of energy used to treat water supplies.
(4) An estimate of the amount of energy used to distribute water supplies through its distribution
systems.
(5) An estimate of the amount of energy used for treated water supplies in comparison to the
amount used for nontreated water supplies.
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(6) An estimate of the amount of energy used to place water into or withdraw from storage.
(7) Any other energy-related information the urban water supplier deems appropriate.
“Energy intensity” is defined as the quantity of energy consumed, measured in kilowatt
hours (kWh), divided by the volume of water, measured in AF for a water management
process over a one-year period. The information used to calculate the estimated energy
intensity associated with the City’s water system is provided below. The energy intensity
information is based on readily obtainable energy and water use data for the following
water management processes: 1) extraction or diversion of water supplies; 2) placement
into storage; 3) conveyance to distribution; 4) treatment; and 5) water system distribution.
The City has tabulated its energy intensity using readily obtainable energy consumption
data obtained from monthly electricity bills from Southern California Edison (SCE) for the
whole water system and the corresponding water use data obtained from available water
meter readings. The City has reported the energy intensity associated with the water
management processes which occur within its operational control. Because the City does
not track individual energy usage for each water management process identified above,
the City has estimated the energy intensity using the a “total utility approach” (i.e. sum of
all water management processes). The total energy consumed was approximately
10,785,416 kWh during FY 2024-25. Although the total energy consumption reported
includes electricity usage for general administration (e.g. at City Hall) which is not
associated with any water management processes, the general administration energy
usage is considered negligible compared to overall water system use and has not been
netted out.
2025 Urban Water Management Plan
City of Arcadia Page 6-52
The total volume of water entering the potable water system was approximately 13,294
AF during FY 2024-25 and is consistent with the total volume of water provided in Table
4-1.
The total energy intensity associated with the City’s water management processes is
estimated at 2,490 kWh per million gallons. The energy intensity data and calculations
based on the “total utility approach” are provided in Table O-1B below.
The City’s water management processes do not include “consequential hydropower
generation” where the energy generation is a direct consequence of water delivery (i.e.
all water passing through the energy generation devices is delivered to users). The City’s
water management processes do not include “non-consequential hydropower generation”
where the energy generation is not a direct consequence of water delivery (i.e. energy
could be generated even if no water was being delivered to water users). In addition, the
City’s water management processes do not include any substantial “self-generated
energy sources” including solar, wind, geothermal, biomass, co-generation, and diesel
generator sources.
2025 Urban Water Management Plan
City of Arcadia Page 6-53
Table O-1B. Recommended Energy Reporting — Total Utility Approach
Water Delivery Product
drop down list
(If delivering more than one type of product recommend
using Table O-1C)
Retail Potable
Deliveries
Start Date of Reporting Period 7/1/2024
End Date of Reporting Period 6/30/2025
Is upstream embedded energy in the values reported?No
Units of Measure for Water AF Total Utility
See DWR NOTES Hydropower Net Utility
13,294 13,294
10,785,416 10,785,416
2,490 - 2,490
Quantity of Self-Generated Renewable Energy
0kWh
Data Quality (Estimate, Metered Data, Combination of Estimates and Metered Data)
Combination of Estimates and Metered Data
Data Quality Narrative:
Narrative:
Energy Intensity (kWh/vol. converted to MG)
Optional Submittal Table O-1B: Recommended Energy Reporting - SINGLE DELIVERY PRODUCT - TOTAL UTILITY
APPROACH
The total energy consumed was identified based on Southern California Edison (SCE) billing records. Although the total energy consumed includes
electricity usage for general administration (which is not an identified water management process), general administration energy use is considered to be
negligible compared to overall water system use and has not been netted out.
Only for Water Delivery Products Under the Urban Water Supplier's Operational
Control
Sum of All Water
Management Processes Non-Consequential Hydropower
DWR NOTES:
Total Utility:The volume of water entered in the “Total Utility” column should equal the volume of water entering the distribution system (ex cluding
recycled water); in most cases, this is the total volume calculated in UWMP Table 4-1: 2025 Actual Total Uses for Potable and Non-Potable Water. Note if
recycled water is included in your Submittal Table 4-1, you must exclude it from your volume in this table.
NOTES:
The total energy consumption includes energy associated with operating groundwater production wells and booster pumps to deliver water in the
distribution system. Energy consumption is associated with operating groundwater water treatment. Energy consumption is also associated with plant
lighting and air conditioning, and operating the Supervisory Control and Data Acquisition (SCADA) system and chlorination injection pumps.
Volume of Water Entering Process
Energy Consumed (kWh)
2025 Urban Water Management Plan
City of Arcadia Page 6-54
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 6 are provided
below.
TABLE 6-1: GROUNDWATER VOLUME PUMPED
Table 6-1 Groundwater Volume Pumped
2025 Urban Water Management Plan
City of Arcadia Page 6-55
TABLE 6-2: WASTEWATER COLLECTED WITHIN SERVICE
AREA
Table 6-2 Wastewater Collected Within Service Area
2025 Urban Water Management Plan
City of Arcadia Page 6-56
TABLE 6-3: WASTEWATER TREATMENT AND OUTCOMES
WITHIN UWMP SERVICE AREA
Table 6-3 Wastewater Treatment and Outcomes Within UWMP Service Area
2025 Urban Water Management Plan
City of Arcadia Page 6-57
TABLE 6-4: RECYCLED WATER DIRECT BENEFICIAL USES
WITHIN SERVICE AREA
Table 6-4 Recycled Water Direct Beneficial Uses Within Service Area
2025 Urban Water Management Plan
City of Arcadia Page 6-58
TABLE 6-5: 2020 UWMP RECYCLED WATER-USE
PROJECTION COMPARED TO 2025 ACTUAL
Table 6-5 2020 UWMP Recycled Water-Use Projection Compared to 2025 Actual
2025 Urban Water Management Plan
City of Arcadia Page 6-59
TABLE 6-6: METHODS TO ENCOURAGE FUTURE RECYCLED
WATER USE
Table 6-6 Methods to Encourage Future Recycled Water Use
2025 Urban Water Management Plan
City of Arcadia Page 6-60
TABLE 6-7: EXPECTED FUTURE WATER SUPPLY PROJECTS
OR PROGRAMS
Table 6-7 Expected Future Water Supply Projects or Programs
TABLE 6-8: WATER SUPPLIES—ACTUAL
As discussed in Section 6.2, the City’s water supply sources consist of treated imported
water purchased from Metropolitan Water District of Southern California through Upper
Water (see Section 6.2.1) and groundwater from the Main and Raymond Basins (see
Section 6.2.2). The actual quantities of the water supply sources available to the City
during FY 2024-25 are summarized in Table 6-8. The reliable quantities of projected water
supply sources available to the City in five-year increments through FY 2049-50 during
normal or average years are summarized in Table 6-9. The reliability of these sources of
2025 Urban Water Management Plan
City of Arcadia Page 6-61
supply are addressed in Section 7.2.3, including during normal years, single dry years,
and five consecutive year droughts.
The order of use of the City’s projected reliable water supplies from FY 2024-25 through
FY 2049-50 in five-year increments is based on historical practices, water supply
availability, and the cost of water. It is anticipated the City will initially use groundwater
produced from the Main Basin and the Raymond Basin. The City will also use treated
imported water, if needed. It is important to note that the Main Basin is adjudicated (as
discussed in Section 6.2.2) and that there is no limit to the amount of groundwater which
can be produced annually. Consequently, in the event treated imported water may be
limited, the City has the flexibility to increase groundwater production from the Main Basin.
The City’s projected quantities of treated imported water supplies are based on historical
long-term averages and available supplies during previous dry year conditions. The City’s
projected quantities of groundwater supplies from Main Basin are based on meeting the
remainder of the City’s total water demands. As noted above, in the event treated
imported water may be limited, the City has the flexibility to increase groundwater
production from the Main Basin. Consequently, it is anticipated the City will have sufficient
water supplies available to meet projected demands.
2025 Urban Water Management Plan
City of Arcadia Page 6-62
Table 6-8 Water Supplies—Actual
OPTIONAL TABLE 6-8DS: SOURCE DESALINATION BY
SUPPLIER
As discussed in Section 6.2.6, the City is currently not considering the development of a
desalinated water project. As a result, optional Table 6-8DS is not included.
Water Supply
Drop down list
May use each category multiple
times. These are the only water
supply categories that will be
recognized by the WUEdata online
submittal tool
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
Actual Volume
(AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Groundwater (not desalinated) East Raymond Basin Potable 2,167
Groundwater (not desalinated) West Raymond Basin Potable 772
Groundwater (not desalinated) Main Basin Potable 10,355
Purchased or Imported Water MWD Potable 0
13,294 0
00
13,294 0
Submittal Table 6-8 Retail: Water Supplies — Actual
Water Code Section 10631(b)
2025
NOTES:
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies
the unit of measure selected in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
Add additional rows as needed
Total
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
2025 Urban Water Management Plan
City of Arcadia Page 6-63
TABLE 6-9: WATER SUPPLIES—PROJECTED
Table 6-9 Water Supplies—Projected
Water Supply
Reasonably
Available
Volume
(AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume
(AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Groundwater (not
desalinated)
East
Raymond
Basin
Potable 2,300 2,300 2,300 2,300 2,300
Groundwater (not
desalinated)
West
Raymond
Basin
Potable 800 800 800 800 800
Groundwater (not Main Basin Potable 11,673 13,044 13,125 13,208 13,288
Purchased or Imported
Water MWD Potable 0 0 0 0 0
14,773 0 16,144 0 16,225 0 16,308 0 16,388 0
00 0 0000000
14,773 0 16,144 0 16,225 0 16,308 0 16,388 0
Submittal Table 6-9 Retail: Water Supplies — Projected
Water Code Section 10631 (b)
Projected Water Supply (Report to the Extent Practicable)
Drop down list
May use each category
multiple times. These are the
only water supply categories
that will be recognized by the
WUEdata online submittal
tool
Additional
Detail on
Water
Supply
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
2050 (opt)
Add additional rows as needed
Total
NOTES:
2030 2035 2040 2045
Subtotal Non-Potable
Subtotal Potable
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
2025 Urban Water Management Plan
City of Arcadia Page 7-1
CHAPTER 7
WATER SERVICE RELIABILITY AND DROUGHT RISK ASSESSMENT
LAY DESCRIPTION – CHAPTER 7
WATER SERVICE RELIABILITY AND DROUGHT RISK ASSESSMENT
Chapter 7 (Water Service Reliability and Drought Risk Assessment) of the City’s 2025
Plan discusses and provides the following:
x FY 2019-20 represents an “average” or “normal” water year for the City in which
the total amount of rainfall was similar to the historical average rainfall.
x A “single dry” year for the City was represented in FY 2017-18, in which the total
amount of rainfall was below the historical average rainfall.
x A “five consecutive year drought” period for the City is represented from FY 2011-
12 to FY 2015-16, where the total amount of rainfall during each of these years
was less than the historical average rainfall.
x The City’s current and projected water supplies available during normal years in
five-year increments over the next 25 years are provided (through Fiscal Year
2049-50) as shown on Table 7-2.
x The City’s current and projected water supplies available during single dry years
in five-year increments over the next 25 years are provided (through Fiscal Year
2049-50) as shown on Table 7-3.
x The City’s current and projected water supplies available during each year of a five
consecutive year drought in five-year increments over the next 25 years are
provided (through Fiscal Year 2049-50) as shown on Table 7-4.
x The reliability of the City’s water supply sources, including a review of water supply
constraints, is provided. A single dry year or a five consecutive year drought period
2025 Urban Water Management Plan
City of Arcadia Page 7-2
will not compromise the City’s ability to provide a reliable supply of water to its
customers.
x A Drought Risk Assessment is provided which includes an assessment of the
City’s water supply reliability over a five consecutive year drought period. The
City’s DRA assumes a five consecutive year drought from FY 2025-26 through FY
2029-30 and includes a review of water supplies, water uses, and water supply
reliability for each water supply source during this period. The City’s water system
has experienced a prior five consecutive year drought with no limitation to its
collective water supplies. However, the cost of those water supplies may have
increased based on the mix of water supplies which are used. Consequently, the
City has the ability to enact varying water shortage levels (see Chapter 8) to help
educate its customers and provide an economic incentive for the retail customers
to reduce their water consumption.
CONSTRAINTS ON WATER SOURCES CONSIDERATIONS
CWC 10631.
(b)(1) A detailed discussion of anticipated supply availability under a normal water year, single dry
year, and droughts lasting at least five years, as well as more frequent and severe periods
of drought, as described in the drought risk assessment. For each source of water supply,
consider any information pertinent to the reliability analysis conducted pursuant to Section
10635, including changes in supply due to climate change.
Water Code Section 10634
The plan shall include information, to the extent practicable, relating to the quality of existing
sources of water available to the supplier over the same five-year increments as described in
subdivision (a) of Section 10631, and the manner in which water quality affects water management
strategies and supply reliability.
Water Code Section 10635
2025 Urban Water Management Plan
City of Arcadia Page 7-3
(b)(2) A determination of the reliability of each source of supply under a variety of water shortage
conditions. This may include a determination that a particular source of water supply is fully
reliable under most, if not all, conditions.
Water Code Section 10635
(b)(4) Considerations of the historical drought hydrology, plausible changes on projected supplies
and demands under climate change conditions, anticipated regulatory changes, and other
locally applicable criteria.
This section of the City’s UWMP describes the City’s ability to meet retail customer water
demands by analyzing a variety of factors which affect the City’s water supply. This
section assesses the City’s water service reliability during average years, single dry
years, and during a five consecutive year drought period to meet the water needs of its
customers. This section also includes the discussion of a Drought Risk Assessment which
provides a mechanism for the City to evaluate the risk to its water supply under a drought
lasting for the next five consecutive years.
SERVICE RELIABILITY - CONSTRAINTS ON WATER SOURCES
The City’s sources of supplies consist of groundwater pumped from the Main Basin and
Raymond Basin, and treated, imported surface water from Metropolitan Water District of
Southern California purchased through Upper Water, as described in Section 6.2.
Although all of these supplies are managed, the following constraints may occur which
the City has considered in this reliability analysis.
Main Basin
The City produces groundwater from the Main Basin. The groundwater historically had
been impacted by contamination. However, the City has developed and implemented
appropriate treatment (blending and/or treatment facilities) which have been approved by
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City of Arcadia Page 7-4
SWRCB-DDW. These groundwater supplies are considered reliable both from a water
quality and quantity standpoint.
Raymond Basin
The City produces groundwater from the Raymond Basin. The groundwater historically
had been impacted by contamination. However, the City has developed and implemented
appropriate treatment (blending and/or treatment facilities) which have been approved by
SWRCB-DDW. These groundwater supplies are considered reliable both from a water
quality and quantity standpoint.
Imported Water
The City also receives treated surface water from MWD through Upper Water. Water
quality from MWD relating to supply reliability is addressed separately in MWD’s 2025
Regional Urban Water Management Plan.
WATER SERVICE RELIABILITY ASSESSMENT
CWC 10635.
(a) Every urban water supplier shall include, as part of its urban water management plan, an
assessment of the reliability of its water service to its customers during normal, dry, and
multiple dry water years. This water supply and demand assessment shall compare the total
water supply sources available to the water supplier with the long-term total projected water
use over the next 20 years, in five-year increments, for a normal water year, a single dry water
year, and a drought lasting five consecutive water years. The water service reliability
assessment shall be based upon the information compiled pursuant to Section 10631,
including available data from state, regional, or local agency population projections within the
service area of the urban water supplier.
2025 Urban Water Management Plan
City of Arcadia Page 7-5
Information regarding the reliability of the City’s water supplies is based on the historical
precipitation data in the San Gabriel Valley. Historical annual precipitation in the San
Gabriel Valley is discussed in Section 3.3 and is based on historical data collected from
Station 159 (Monrovia). Furthermore, Section 4.2.5.6 of this Plan notes that potential
future climate change impacts may result in an increase in the average annual
precipitation within the City’s service area, thus indicating use of historical data is a
reasonable and conservative approach. As indicated in Section 3.3, the historical average
rainfall in the vicinity of the City’s service area is 19.9 inches. FY 2019-20 represents an
average or normal water year for the City in which the total amount of rainfall was similar
to the historical average rainfall. A single dry year for the City was represented in FY
2017-18, in which the total amount of rainfall was below the historical average rainfall. A
five consecutive year drought period for the City is represented from FY 2011-12 to FY
2015-16, where the total amount of rainfall during each of these years was less than the
historical average rainfall. Table 7-1 summarizes these “base years” for average, single
dry, and five consecutive year drought and provides the total amount of water supplies
available to the City during those base years. The following discussion assesses the
water service reliability of the City’s water supply sources.
Water Service Reliability - Imported Water
The City’s treated imported water supplies from MWD, through Upper Water, may be
impacted during a multi-year drought or other conditions which limits MWD from delivering
sufficient water supplies to all of its member agencies, and consequently to the City. In
anticipation of such a reduction in supplies, MWD developed a WSAP which is briefly
described below. The WSAP provides a means of equitably providing reduced water
supplies to each of MWD’s member agencies for up to 10 levels of reduction representing
up to a 50 percent reduction.
2025 Urban Water Management Plan
City of Arcadia Page 7-6
During calendar year 2007, critically dry conditions impacted MWD’s water supply
sources. In addition, a ruling in the Federal Courts in August 2007 provided protective
measures for the Delta Smelt (and subsequently other aquatic species) in the
Sacramento-San Joaquin River Delta resulting in restrictions on the availability of State
Water Project water. As a result, MWD adopted a WSAP in February 2008 to allocate
available water supplies to its member agencies. MWD revised the WSAP in December
2014.
The WSAP establishes ten different shortage levels and a corresponding Allocation to
each member agency. Based on the shortage levels established by MWD, the WSAP
provides a separate reduced Allocation to a member agency for its 1) Municipal and
Industrial (M&I) retail demand and 2) replenishment demand. The WSAP formula
considers historical local water production, full service treated water deliveries,
agricultural deliveries and water conservation efforts when calculating each member
agency’s Allocation.
In general, the WSAP process calculates total historical member agency demand. That
historical demand is then compared to member agency projected local supply for a
specific Allocation year. The balance required from MWD, less an Allocation reduction
factor, is the member agency’s “Water Supply Allocation” of imported water from MWD.
When a member agency reduces its local demand through conservation or other means,
the Allocation of imported water will increase. Depending on MWD’s available supply,
MWD can establish a specific WSAP shortage level. The shortage level causes a regional
reduction and calculates an allocation for each of its member agency. Additional
information about MWD’s WSAP is provided in MWD’s Regional 2025 UWMP which is
incorporated by reference. The following is a summary of MWD’s water shortage levels:
Level 1 – Regional Percent Reduction of 5%
Level 2 – Regional Percent Reduction of 10%
2025 Urban Water Management Plan
City of Arcadia Page 7-7
Level 3 – Regional Percent Reduction of 15%
Level 4 – Regional Percent Reduction of 20%
Level 5 – Regional Percent Reduction of 25%
Level 6 – Regional Percent Reduction of 30%
Level 7 – Regional Percent Reduction of 35%
Level 8 – Regional Percent Reduction of 40%
Level 9 – Regional Percent Reduction of 45%
Level 10 – Regional Percent Reduction of 50%
In response to a fourth consecutive year of below average rainfall and critically dry
conditions, MWD declared a WSAP Allocation Level 3 for fiscal year 2015-16, which
represented a regional reduction of 15 percent. MWD rescinded the WSAP for fiscal year
2016-17 and has not reinstated the WSAP since that time.
Water Service Reliability - Groundwater
Main Basin
The Main Basin groundwater supplies are managed by the Main Basin Watermaster, as
discussed in Section 6.2.2. During a normal year (FY 2019-20), the City met about 83
percent of its total demands with supplies from the Main Basin. During a single dry year
(FY 2017-18), the City met about 84 percent of its total demands with supplies from the
Main Basin. During a five consecutive year drought period (FY 2011-12 to FY 2015-16),
the City met between 71 and 81 percent of its total demands with supplies from the Main
Basin.
2025 Urban Water Management Plan
City of Arcadia Page 7-8
Raymond Basin
The Raymond Basin groundwater supplies are managed by the Raymond Basin
Management Board, as discussed in Section 6.2.2. During a normal year (FY 2019-20),
the City met about 17 percent of its total demands with supplies from the Raymond Basin.
During a single dry year (FY 2017-2018), the City met about 16 percent of its total
demands with supplies from the Raymond Basin. During a five consecutive year drought
period (FY 2011-12 to FY 2015-16), the City met between 19 and 29 percent of its total
demands with supplies from the Raymond Basin.
Water Service Reliability Summary
Table 7-1 shows the water supplies during the base years (for average year, single dry
year and a five consecutive year drought). As a result of the City’s diverse water supply
portfolio, water supplies may be re-apportioned during a five consecutive year drought to
meet the City’s water demands.
WSRA YEAR-TYPE CHARACTERIZATION
7.2.1.1 TYPES OF YEARS
The City’s base years for an average year, a single dry year, and a five consecutive year
drought are discussed in Section 7.2 and are summarized in Table 7-1. As indicated in
Chapter 6, the City’s water supplies sources have been sufficient in meeting the City’s
historical water demands during an average year, a single dry year, and a five consecutive
year drought. An average year was based on a historical year during the past 15 years
with a total precipitation similar to the historical average precipitation in the vicinity of the
City’s service area. Because a single dry year or a five consecutive year drought period
will not compromise the City’s ability to provide a reliable supply of water to its customers,
2025 Urban Water Management Plan
City of Arcadia Page 7-9
a single dry year in this Plan was selected based one of the driest years during the past
15 years. The five consecutive year drought period was based on a period of five
consecutive dry years during the past 15 years.
As indicated in Section 3.3, the historical average rainfall in the vicinity of the City’s service
area is 19.9 inches. FY 2019-20 represents an average or normal water year for the City
in which the total amount of rainfall was similar to the historical average rainfall. A single
dry year for the City was represented in FY 2017-18, in which the total amount of rainfall
was less than the historical average rainfall. A five consecutive year drought period for
the City is represented from FY 2011-12 to FY 2015-16, where the total amount of rainfall
during each of these years was less than the historical average rainfall. Table 7-1
summarizes these “base years” for an average year, a single dry year, and a five
consecutive year drought period and provides the total amount of water supplies available
to the City during those base years.
7.2.1.2 SOURCES FOR WATER DATA
The monthly historical average temperatures (including minimum and maximum),
monthly historical average rainfall, and monthly ETo in the vicinity of the City’s service
area are discussed in Section 3.3 Historical climate information was obtained from the
WRCC, DPW, and from DWR’s CIMIS.
WSRA SUPPLY AND DEMAND COMPARISON
CWC 10635.
(a) Every urban water supplier shall include, as part of its urban water management plan, an
assessment of the reliability of its water service to its customers during normal, dry, and
multiple dry water years. This water supply and demand assessment shall compare the total
water supply sources available to the water supplier with the long-term total projected water
use over the next 20 years, in five-year increments, for a normal water year, a single dry water
2025 Urban Water Management Plan
City of Arcadia Page 7-10
year, and a drought lasting five consecutive water years. The water service reliability
assessment shall be based upon the information compiled pursuant to Section 10631,
including available data from state, regional, or local agency population projections within the
service area of the urban water supplier.
The City primarily obtains its water supplies from groundwater wells located in the Main
Basin. As discussed in Section 7.3 and shown in Table 7-2, Table 7-3, and Table 7-4,
each of the City’s water supply sources share the same base years. As previously
discussed in Section 7.2.1, a single dry year or a five consecutive year drought period will
not compromise the City’s ability to provide a reliable supply of water to its customers.
The City’s projected normal year water demands over the next 25 years are discussed in
Section 4.2.6.The ratio of total water supplies (including potable and recycled water
supplies) available to the City during a historical normal year in FY 2019-20 (or 13,935
AF) and during a historical single dry year in FY 2017-18 (or 14,416 AF) was used to
estimate the City’s projected water demands during single dry years. The ratio of water
supplies available to the City during a historical normal year in FY 2019-20 (or 13,935 AF)
and a historical five consecutive year drought period from FY 2011-12 to FY 2015-16 (or
16,399 AF, 17,211 AF,17,452 AF, 15,326 AF, and 12,369 AF, respectively) was used to
estimate the City’s projected water demands during a five consecutive year drought
period. The City’s projected dry year water supplies over the next 25 years were based
on the minimum supplies needed by the City to meet projected single-dry year demands.
Table 7-2, Table 7-3, and Table 7-4 summarize the City’s projected water demands and
supplies over the next 25 years in five-year increments, including during normal years,
single dry years, and a five consecutive year drought periods. These tables indicate the
City can meet water demands during normal years, single dry years, and a five
consecutive year drought periods over the next 25 years.
2025 Urban Water Management Plan
City of Arcadia Page 7-11
7.2.2.1 NORMAL YEAR
Table 7-2 summarizes the City’s projected water demands and supplies over the next 25
years in five-year increments during normal years. Table 7-2 indicates the City can meet
water demands during normal years over the next 25 years.
7.2.2.2 SINGLE DRY YEAR
Table 7-3 summarizes the City’s projected water demands and supplies over the
next 25 years in five-year increments during single dry years. Table 7-3 indicates the City
can meet water demands during single dry years over the next 25 years.
7.2.2.3 FIVE CONSECUTIVE DRY YEARS
Table 7-4 summarizes the City’s projected water demands and supplies over the next 25
years in five-year increments during five consecutive year drought periods. Table 7-4
indicates the City can meet water demands during five consecutive year drought periods
over the next 25 years.
WSRA DESCRIPTION OF MANAGEMENT TOOLS AND
OPTIONS
CWC 10620.
(f) An urban water supplier shall describe in the plan water management tools and options used
by that entity that will maximize resources and minimize the need to import water from other
regions.
2025 Urban Water Management Plan
City of Arcadia Page 7-12
Main Basin
As noted in Section 6.2.2, the Main Basin is managed by the Main Basin Watermaster.
During the period of management under the Judgment, significant drought events have
occurred. In each drought cycle the Main Basin has been managed to maintain water
levels. Therefore, based on historical and on-going management practices, the City will
be able to rely on the Main Basin for adequate supply over the next 25 years under single
dry years and a five consecutive year drought periods.
Section 6.2.2 provides a description of the management of groundwater resources in the
Main Basin, as well as information on basin management. Chapter 6 also demonstrates
the management structure of the Main Basin provides a reliable source of groundwater
supply for the City during a normal year, a single-dry year and a five consecutive year
drought. Historical data indicates the Main Basin has been well managed for the full period
of the adjudication, resulting in a stable and reliable water supply. Basin management
changes are discussed in Section 6.2.2, and include increased direct use of recycled
water (see Section 6.2.5) and the planned use of treated recycled water for groundwater
replenishment in the Main Basin to reduce the need to import water from other regions.
Therefore, the groundwater supplies in the Main Basin are deemed reliable.
Raymond Basin
As noted in Section 6.2.2, the Raymond Basin is managed by the Raymond Basin
Management Board. During the period of management under the Judgment, significant
drought events have occurred. In each drought cycle the Raymond Basin has been
managed to maintain water levels. Therefore, based on historical and on-going
management practices, the City will be able to rely on the Raymond Basin for adequate
supply over the next 25 years under single dry years and a five consecutive year drought
periods.
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Section 6.2.2 provides a description of the management of groundwater resources in the
Raymond Basin, as well as information on basin management. Chapter 6 also
demonstrates the management structure of the Raymond Basin provides a reliable
source of groundwater supply for the City during a normal year, a single-dry year and a
five consecutive year drought. Historical data indicates the Raymond Basin has been well
managed for the full period of the adjudication, resulting in a stable and reliable water
supply. Therefore, the groundwater supplies in the Raymond Basin are deemed reliable.
DROUGHT RISK ASSESSMENT
CWC 10612.
“Drought Risk Assessment” means a method that examines water shortage risks based on the driest
five-year historic sequence for the agency’s water supply, as described in subdivision (b) of Section
10635.
CWC 10635.
(b) Every urban water supplier shall include, as part of its urban water management plan, a
drought risk assessment for its water service to its customers as part of information considered
in developing the demand management measures and water supply projects and programs
to be included in the urban water management plan. The urban water supplier may conduct
an interim update or updates to this drought risk assessment within the five-year cycle of its
urban water management plan update. The drought risk assessment shall include each of the
following:
(1) A description of the data, methodology, and basis for one or more supply shortage
conditions that are necessary to conduct a drought risk assessment for a drought period
that lasts five consecutive water years, starting from the year following when the
assessment is conducted.
(2) A determination of the reliability of each source of supply under a variety of water shortage
conditions. This may include a determination that a particular source of water supply is
fully reliable under most, if not all, conditions.
(3) A comparison of the total water supply sources available to the water supplier with the
total projected water use for the drought period.
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(4) Considerations of the historical drought hydrology, plausible changes on projected
supplies and demands under climate change conditions, anticipated regulatory changes,
and other locally applicable criteria.
The City’s sources of supplies consist of groundwater pumped from the Main Basin and
Raymond Basin, and treated, imported surface water from Metropolitan Water District of
Southern California purchased through Upper Water. The following discussion provides
a Drought Risk Assessment which assesses the City’s water supply reliability over a five
consecutive year drought period. The City’s DRA incorporates a five consecutive year
drought from FY 2025-26 through FY 2029-30 and includes a review of water supplies,
water uses, and water supply reliability.
DRA, DATA, METHODS, AND BASIS FOR WATER SHORTAGE
CONDITIONS
The City’s DRA was prepared using historical production data from the City’s water supply
sources. The following assumptions were considered during the preparation of the City’s
DRA for each year of the five consecutive year drought.
x The five consecutive year drought period associated with the 2025 Plan is based
on five consecutive dry years from FY 2025-26 through FY 2029-30
x The projected water supplies available during each year of this five consecutive
year drought are assumed to be identical to the water supplies produced during
each year between FY 2011-12 and FY 2015-16 (which represents the most recent
and historical five consecutive year drought).
x The projected demands during this five consecutive year drought are based on
water demands from FY 2019-20 (a normal year) which were adjusted based on
projected population over the next five years along with the ratio of the normal year
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demands to actual demands over each year of the most recent and historical five
consecutive year drought period (from FY 2011-12 and FY 2015-16).
x The projected demands were compared to the projected supplies to identify
potential water supply deficits which may require implementation of the Water
Shortage Contingency Plan (discussed further in Chapter 8).
The following methodologies were considered during the preparation of the City’s DRA
during for each year of the five consecutive year drought:
x Drought Year 1: The region had experienced an average to above average year
of precipitation in the prior year. Water use in the prior year had been below
average due to a reduce need for outdoor water use, the groundwater basin had
been replenished from above average local stormwater runoff, and imported water
supplies were not restricted.
x Drought Year 2: The region experienced a second year of below average
precipitation and runoff. Retail customers increased water use for outdoor irrigation
to compensate for lack of precipitation. Groundwater and imported water supplies
have not been impacted.
x Drought Year 3: The region experienced a third year of below average precipitation
and runoff. Retail customers increased water use for outdoor irrigation to
compensate for lack of precipitation. Groundwater and imported water supplies
have not been impacted. However, there is an increased demand on both
groundwater and treated imported water.
x Drought Year 4: The region experienced a fourth year of below average
precipitation and runoff. Groundwater supplies have not been impacted. However,
there is an increased demand on groundwater.
x Drought Year 5: Fifth year of below average precipitation and runoff. Groundwater
supplies have not been impacted. However, there is an increased demand on
groundwater.
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DRA INDIVIDUAL WATER SOURCE RELIABILITY
The City’s DRA incorporates a five consecutive year drought based on five consecutive
dry years commencing in FY 2025-26. The quantity of water supplies available for each
year during this five consecutive year drought period included in the City’s DRA is
assumed to be the same as the quantity of water supplies produced by the City (i.e.
demands) during the most recent and historical five consecutive year drought which
occurred from FY 2011-12 through FY 2015-16. Production data for those years have
been tabulated in Section 6.1. The following describes the anticipated reliability of each
water source for each year of the five consecutive year drought based on recent
experience.
Groundwater – Main Basin
The City receives water supplies from the Main Basin which is actively managed by the
Main Basin Watermaster, as described in Section 6.2.2. Each year the Main Basin
Watermaster reviews water supply conditions including local rainfall, groundwater levels,
local stormwater runoff available for replenishment, imported water availability and the
amount of imported water stored in the groundwater basin for future demands. The
Watermaster identifies the annual amount of groundwater which may be pumped (such
as an Operating Safe Yield) before more expensive imported water would need to be
purchased from MWD through the Upper Water to replenish the Basin for all production
in excess of the water rights. Regardless of the annual safe yield adopted there is never
a restriction on the amount of water which may be pumped from the Main Basin, only the
cost of producing the groundwater is impacted. The Main Basin Watermaster is not
restricted as to when or how much untreated imported water be delivered to the Main
Basin, only that it ultimately be delivered. In addition, the City has established an
untreated imported water (cyclic) storage account in the Main Basin which the City may
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draw upon to offset its potential future production in excess of its water rights. In doing
so, the City reduces its need to purchase untreated imported water in the future in the
midst of a drought when imported water supplies may be limited. The quantity of
groundwater used (and reliably available) during the most recent and historical five
consecutive year drought period have been tabulated in Section 6.1. During this period,
the City was able to increase its production of its groundwater supplies from an
adjudicated and managed groundwater basin. The City also had the ability to
systematically implement aspects of its Water Shortage Contingency Plan (see Chapter
8). As a result of these collective actions (and experience during prior consecutive five-
year droughts), the City does not anticipate a water supply shortage from the Main Basin.
Groundwater- Raymond Basin
The City receives water supplies from the Raymond Basin which is actively managed by
the Raymond Basin Management Board, as described in Section 6.2.2. The Raymond
Basin is adjudicated; however, the City’s water rights are fixed each year. Consequently,
the City cannot produce in excess of its own water rights or rights it may have leased from
others. The City also has access to water supplies from Main Basin and treated imported
water. The quantity of groundwater used (and reliably available) during the most recent
and historical five consecutive year drought period have been tabulated in Section 6.1.
The City manages its water supply portfolio to optimize the water supplies available each
year and to avoid a water supply shortage. The City also had the ability to systematically
implement aspects of its Water Shortage Contingency Plan (see Chapter 8). As a result
of these collective actions (and experience during prior consecutive five-year droughts),
the City does not anticipate a water supply shortage.
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Imported Water
The City obtains imported water from the Metropolitan Water District of Southern
California through Upper Water. Section 6.2.1 describes the planning conducted by the
Metropolitan Water District of Southern California regarding treated imported water
supplies available to the City. The reliability of MWD’s supplies is also discussed in its
2025 Regional UWMP and is incorporated by reference. The City purchases treated
imported water which is delivered directly within its distribution system. The City’s
purchases of treated, imported water over the past 15 years have been tabulated in
Section 6.1. In the event of a drought which limits imported water supplies, the City will
rely on its groundwater production and will pay the applicable assessments to purchase
untreated imported water to be delivered in the future when supplies are available.
The imported water purchases by the City during the most recent and historical five
consecutive year drought period have been tabulated in Section 6.1. Because the City’s
DRA assumes the most recent and historical five consecutive year drought scenario will
be repeated over the next five years, it is assumed the quantity of treated imported water
supplies purchased during the most recent and historical five consecutive year drought
scenario will be available. Furthermore, this constitutes the minimum amount of treated
imported water which may be available in a future five consecutive year drought absent
MWD’s programs which it has since implemented.
Summary
The City’s water system has experienced a prior five consecutive year drought with no
limitation to its collective water supplies. However, the cost of those water supplies may
have increased based on the mix of supplies which are used. Consequently, the City has
the ability to enact varying Demand Management Measures (see Chapter 9) to help
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educate its customers and provide an economic incentive for the retail customers to
reduce their water consumption.
DRA TOTAL WATER SUPPLY AND USE COMPARISON
Gross water use for the projected five consecutive year drought is shown on Table 7-5.
Section 7.3.2 describes the water source reliability for each source of supply the City will
rely on during a five consecutive year drought. The annual quantities are summed and
are also provided on Table 7-5. The most important aspect of the City’s water supplies is
the groundwater which can be produced from a managed groundwater basin without
restriction on the amount the City is allowed to produce. However, for the purposes of the
City’s DRA, as a worst-case scenario, the City has considered no water supply
augmentation (as indicated in Table 7-5) from its groundwater supplies. When necessary,
the City can implement various water shortage levels of its Water Shortage Contingency
Plan (as discussed in Chapter 8) in order to reduce its water demands. The total water
supplies available to the City shown in Table 7-5 are based on the quantity of supplies
produced by the City (i.e. demands) during the most recent historical five consecutive
drought period (from FY 2011-12 through FY 2015-16). As shown in Table 7-5, assuming
no additional water supply benefits will be available from groundwater supplies, the City
can implement various stages of its Water Shortage Contingency Plan to balance water
demands with available supplies during each year of the projected five consecutive year
drought.
OPTIONAL PLANNING TOOL WORKBOOK
DWR has deemed the “Planning Tool Worksheet” as optional and the City is not required
by DWR to use the tool. The City has provided sufficient water supplies to its customers,
including during long-term droughts and years with historically high water demands. The
City has also been able to provide water service to meet maximum day water demands
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for these years, including during the summer months. The City obtains the majority of its
water supplies from managed groundwater basins which are not subject to seasonal
fluctuation. Consequently, an evaluation regarding water supplies on a monthly basis was
not considered.
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 7 are provided
below.
OPTIONAL TABLE 7-1: BASIS OF WATER-YEAR DATA (WSRA)
Table 7-1 Basis of Water-Year Data (Reliability Assessment)
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TABLE 7-2: NORMAL-YEAR SUPPLY AND USE COMPARISON
Table 7-2 Normal-Year Supply and Use Comparison
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals
(autofill from Submittal
Table 6-9 R)
14,773 16,144 16,225 16,308 16,388
Use totals
(autofill from Submittal
Table 4-2 R)
14,773 16,144 16,225 16,308 16,388
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply
augmentation benefit
WSCP - use reduction
savings benefit
Revised Surplus/(shortfall)
OPTIONAL Planned WSCP Actions
Submittal Table 7-2 Retail: Normal Year Supply and Use Comparison
Water Code Section 10635 (a)
NOTES:
DWR NOTES : Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported
in Submittal Table 2-3.
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TABLE 7-3: SINGLE-DRY-YEAR SUPPLY AND USE
COMPARISON
Table 7-3 Single-Dry-Year Supply and Use Comparison
Supply totals 15,283 16,701 16,785 16,871 16,954
Use totals 15,283 16,701 16,785 16,871 16,954
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply
augmentation benefit
WSCP - use reduction
savings benefit
Revised
Surplus/(shortfall)
2050 (AF)
DWR NOTES : Units of measure (AF, CCF, MG) must remain consistent throughout the
UWMP as reported in Submittal Table 2-3.
NOTES
Submittal Table 7-3 Retail: Single Dry Year Supply and Use Comparison
Water Code Section 10635(a)
OPTIONAL Planned WSCP Actions
2030 (AF)2035 (AF)2040 (AF)2045 (AF)
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City of Arcadia Page 7-23
TABLE 7-4: MULTIPLE DRY YEARS SUPPLY AND USE
COMPARISON
Table 7-4 Multiple Dry Years Supply and Use Comparison
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 17,385 18,998 19,094 19,191 19,286
Use totals 17,385 18,998 19,094 19,191 19,286
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 18,246 19,939 20,039 20,142 20,241
Use totals 18,246 19,939 20,039 20,142 20,241
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 18,501 20,218 20,320 20,424 20,524
Use totals 18,501 20,218 20,320 20,424 20,524
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 16,248 17,755 17,844 17,936 18,024
Use totals 16,248 17,755 17,844 17,936 18,024
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 13,113 14,330 14,402 14,475 14,546
Use totals 13,113 14,330 14,402 14,475 14,546
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Submittal Table 7-4 Retail: Multiple Dry Years Supply and Use Comparison
Water Code Section 10635(a)
OPTIONAL Planned WSCP Actions
Third year
Fifth year
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table
2-3.
OPTIONAL Planned WSCP Actions
OPTIONAL Planned WSCP Actions
OPTIONAL Planned WSCP ActionsFourth year
NOTES:
First year
OPTIONAL WSCP Actions Second year
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TABLE 7-5: FIVE-YEAR DROUGHT RISK ASSESSMENT
Table 7-5 Five-Year Drought Risk Assessment
2026 Total
Total Water Use (AF) 15,993
Total Supplies (AF) 16,399
Surplus/Shortfall w/o WSCP Action 406
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)
Revised Surplus/(shortfall)
2027 Total
Total Water Use (AF) 17,150
Total Supplies (AF) 17,211
Surplus/Shortfall w/o WSCP Action 61
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)
Revised Surplus/(shortfall)
2028 Total
Total Water Use (AF) 17,760
Total Supplies (AF) 17,452
Surplus/Shortfall w/o WSCP Action (308)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF) 308
Revised Surplus/(shortfall) 0
2029 Total
Total Water Use (AF) 15,922
Total Supplies (AF) 15,326
Surplus/Shortfall w/o WSCP Action (596)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF) 596
Revised Surplus/(shortfall) 0
2030 Total
Total Water Use (AF) 13,113
Total Supplies (AF) 12,369
Surplus/Shortfall w/o WSCP Action (744)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF) 744
Revised Surplus/(shortfall) 0
NOTES:
DWR NOTES: Units of measure (AF, CCF, MG) must remain
consistent throughout the UWMP as reported in Submittal Table
2-3.
Submittal Table 7-5 Retail: Five-Year Drought Risk
Assessment
Water Code Section 10635(b)(3)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
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City of Arcadia Page 8-1
CHAPTER 8
WATER SHORTAGE CONTINGENCY PLAN
LAY DESCRIPTION – CHAPTER 8
WATER SHORTAGE CONTINGENCY PLAN
Chapter 8 (Water Shortage Contingency Plan) of the City’s 2025 Plan discusses and
provides the following:
x The City’s Water Shortage Contingency Plan is a detailed approach which
presents how the City intends to act, or respond, in the case of an actual water
shortage contingency.
x Preparation of the City’s “Annual Water Supply and Demand Assessment” (or
Annual Assessment) is discussed. The City is required to submit annually an
Annual Assessment. The Annual Assessment includes a review of the City’s
“unconstrained” water demands for the current year and for a potential upcoming
single dry year. Unconstrained water demands represent the City’s water
demands prior to any “response actions” the City may invoke pursuant to the City’s
Water Shortage Contingency Plan.
x The City will manage water supplies to minimize the adverse impacts of water
shortages. The City’s plan for water usage during periods of shortage is designed
to incorporate six standard water shortage levels corresponding to progressive
ranges from up to a 10, 20, 30, 40, and 50 percent shortage, and greater than a
50 percent shortage.
x For each declared water supply shortage level, customers will be required to
reduce their consumption by the percentage specified in the corresponding water
supply shortage level.
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x For each declared water supply shortage level, the City has established response
actions to reduce demand on water supplies and to reduce any shortage gaps in
water supplies. These demand reduction actions include irrigation and other
outdoor use restrictions, rate structure changes, and other water use prohibitions.
x The operational changes the City will consider in addressing water shortages on a
short-term basis are discussed and include improved monitoring, analysis, and
tracking of customer water usage to enforce demand reduction measures.
x The City’s Emergency Response Plan is summarized. The Emergency Response
Plan provides the management, procedures, and designated actions the City and
its employees will implement during emergency situations (including catastrophic
water shortages) resulting from natural disasters, system failures, and other
unforeseen circumstances.
x The preparation of the City’s seismic risk assessment and mitigation plan is
discussed. The locations of earthquake faults in the vicinity of the City’s water
service area are provided.
x The effectiveness of the shortage response actions for each of the City’s standard
water shortage levels is presented. The City has been able to provide sufficient
water supplies to its customers, including during long-term droughts and years with
historically high water demands.
x The communication protocols implemented by the City when it declares any water
shortage level are presented.
x The compliance and enforcement procedures associated with City’s standard
water shortage levels are presented.
x The legal authorities associated with City’s standard water shortage levels are
presented.
x The financial consequences associated with City’s standard water shortage levels
are presented.
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x The City will evaluate the need for revising the Water Shortage Contingency Plan
in order to resolve any water shortage gaps, as necessary. The steps necessary
for the City to adopt and amend its Water Shortage Contingency Plan are
presented.
The following Water Shortage Contingency Plan includes references to Chapters and
Sections from the City of Arcadia’s 2025 Urban Water Management Plan:
WATER SUPPLY RELIABILITY ANALYSIS
CWC 10632.
(a)(1) The analysis of water supply reliability conducted pursuant to Section 10635.
CWC 10632.5.
(a) In addition to the requirements of paragraph (3) of subdivision (a) of Section 10632, beginning
January 1, 2020, the plan shall include a seismic risk assessment and mitigation plan to
assess the vulnerability of each of the various facilities of a water system and mitigate those
vulnerabilities.
The City’s sources of supply were discussed in Section 6.2 of the 2025 Plan and consist
of groundwater from Main and Raymond Basins, and treated imported water purchased
from MWD through Upper Water. The Main and Raymond Basins are adjudicated and
groundwater supplies are managed. The reliability of the various sources of supply are
discussed in Chapter 7 of the 2025 Plan. Imported water supplies (treated) may be
impacted in the event MWD implements its WSAP due to a water supply shortage. A
seismic risk assessment and mitigation plan is discussed in Section 8.4.6.
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ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES
CWC 10632.
(a) Every urban water supplier shall prepare and adopt a water shortage contingency plan as
part of its urban water management plan that consists of each of the following elements
CWC 10632.
(a)(2) The procedures used in conducting an annual water supply and demand assessment that
include, at a minimum, both of the following:
(A) The written decision-making process that an urban water supplier will use each year to
determine its water supply reliability.
(B) The key data inputs and assessment methodology used to evaluate the urban water supplier’s
water supply reliability for the current year and one dry year, including all of the following:
(i) Current year unconstrained demand, considering weather, growth, and other
influencing factors, such as policies to manage current supplies to meet demand
objectives in future years, as applicable.
(ii) Current year available supply, considering hydrological and regulatory conditions
in the current year and one dry year. The annual supply and demand assessment
may consider more than one dry year solely at the discretion of the urban water
supplier.
(iii) Existing infrastructure capabilities and plausible constraints.
(iv) A defined set of locally applicable evaluation criteria that are consistently relied
upon for each annual water supply and demand assessment.
(v) A description and quantification of each source of water supply.
CWC 10632.1.
An urban water supplier shall conduct an annual water supply and demand assessment pursuant
to subdivision (a) of Section 10632 and, on or before July 1 of each year, submit an annual water
shortage assessment report to the department with information for anticipated shortage, triggered
shortage response actions, compliance and enforcement actions, and communication actions
consistent with the supplier’s water shortage contingency plan. An urban water supplier that relies
on imported water from the State Water Project or the Bureau of Reclamation shall submit its
annual water supply and demand assessment within 14 days of receiving its final allocations, or
by July 1 of each year, whichever is later.
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By July 1st of every year, the City is required to submit an “Annual Water Supply and
Demand Assessment” (Annual Assessment) in accordance with DWR’s guidance and
requirements. The Annual Assessment includes a review of the City’s unconstrained
water demands (i.e. water demands prior to any projected response actions the City may
trigger under this Water Shortage Contingency Plan) for the current year and the
upcoming (potential single dry) year. The Annual Assessment also includes information
regarding anticipated shortages, triggered shortage response actions, compliance and
enforcement actions, and communication actions consistent with the City’s Water
Shortage Contingency Plan.
For each Annual Assessment, the City plans to prepare a preliminary assessment which
evaluates the adequacy of its water supplies for the current and upcoming years by April
of each year. The preliminary assessment will include a review of water supplies for at
least a single dry year.
During the preparation of each Annual Assessment, the City will evaluate the adequacy
of its water supplies for the current and upcoming years. The evaluation will include a
review of water supplies for at least a single dry year.
DECISION-MAKING PROCESS
The City produces groundwater from the Main Basin as its primary source of water supply
and that basin is managed on a fiscal year basis. Consequently, during the third quarter
of each fiscal year the City will review its water demands from the initial six months along
with the current groundwater basin conditions and local hydrology. This information will
be used to help develop the Annual Assessment. A draft of the Annual Assessment will
be circulated internally within the City for peer review and comment. Based on comments
received, a redraft will be prepared and provided to City managers during the Spring of
each year. The draft will subsequently be provided to the General Manager for final
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review. If necessary, a final draft of the Annual Assessment will be provided to the City
Council for review and included in the agenda as part of a City meeting such that it can
be approved and any recommended specific shortage response actions may be enacted.
The final Annual Assessment will be provided to DWR no later than July 1 of each year.
The Annual Assessments will be instrumental in providing guidance to the City for
decisions regarding potential declarations of a water supply shortage and implementation
of water reduction stages, instituting mandatory water restrictions, promoting water use
efficiency and conservation programs, water rates and drought rate surcharges, and the
necessity of pursuing alternative water supplies. This process will help ensure adequate
water supplies resources are available to the City.
DATA AND METHODOLOGIES
The key data inputs and methodologies which will be evaluated by the City during the
preparation of the Annual Assessment will include the following:
1) Evaluation Criteria: The locally applicable evaluation criteria used to prepare the
Annual Assessment will be identified. The evaluation criteria will include, but is
not limited to, an analysis of current local hydrology (including rainfall and
groundwater levels), current water demands, a review of water system
improvement plans which may impact infrastructure availability, and water quality
regulations which may impact groundwater availability.
2) Water Supply: A description of each available water supply source will be provided.
The descriptions will include a quantification of each available water supply source
and will be based on review of current production capacities, historical production,
Urban Water Management Plans, and prior water supply studies (including Water
Supply Assessments and/or Master Plans).
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3) Unconstrained Water Demand: The potential unconstrained water demands during
the current year and the upcoming (potential single dry) year will be reviewed. The
review will include factors such as weather, existing and projected land uses and
populations, actual customer consumption and water use factors, monthly Urban
Water Supplier Monthly Reports, existing water shortage levels (see Section 8.3),
and existing water conservation ordinances (see Section 9.1).
4) Planned Water Use for Current Year Considering Dry Subsequent Year: The water
supplies available to meet the demands during the current year and the upcoming
(potential single dry) year will be considered and identified by each type of supply.
The evaluation will include factors such as estimated water demands, weather,
groundwater basin operating safe yields, water quality results, existing available
pumping capacities, imported water allocations, contractual obligations, regulatory
issues, use of emergency interconnections, and the costs associated with
producing each water supply source.
5) Infrastructure Considerations: The capabilities of the water distribution system
infrastructure to meet the water demands during the current year and the upcoming
(potential single dry) year will be considered. Available production capacities (e.g.
groundwater well capacities) and distribution system water losses (see Section
4.3) will be reviewed. In addition, capital improvement and replacement projects,
as well as potential projects which may increase water system and production
capacities (see Section 6.2.10), will be considered.
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SIX STANDARD WATER SHORTAGE LEVELS
CWC 10632.
(a)(3)(A) Six standard water shortage levels corresponding to progressive ranges of up to 10, 20,
30, 40, and 50 percent shortages and greater than 50 percent shortage. Urban water
suppliers shall define these shortage levels based on the suppliers’ water supply
conditions, including percentage reductions in water supply, changes in groundwater
levels, changes in surface elevation or level of subsidence, or other changes in
hydrological or other local conditions indicative of the water supply available for use.
Shortage levels shall also apply to catastrophic interruption of water supplies, including,
but not limited to, a regional power outage, an earthquake, and other potential
emergency events.
(a)(3)(B) An urban water supplier with an existing water shortage contingency plan that uses
different water shortage levels may comply with the requirement in subparagraph (A) by
developing and including a cross-reference relating its existing categories to the six
standard water shortage levels.
The City has a legal responsibility to provide water utility services, including water for
residential, commercial, industrial, public authority, and for public fire hydrants and private
fire services. The City will manage water supplies prudently to minimize the adverse
impacts of water shortages. The City’s plan for water usage during periods of shortage is
designed to provide a minimum of 50 percent of normal supply during a severe or
extended water shortage. Water shortage trigger mechanisms have been established to
ensure that this policy is implemented.
For each declared water supply shortage level, customers will be required to reduce their
water consumption by the percentage specified in the corresponding water supply
shortage level.
The City’s water conservation plan previously established eight (8) water shortage levels.
A copy of City’s water conservation plan is provided in Appendix J. In accordance with
the California Water Code in which urban water suppliers are required to define six
standard water shortage level, the City has developed the crosswalk illustrated below
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(also included in the City’s 2020 Plan) that translated the City’s previously established
shortage levels to the mandated standard shortage levels. Table 8-1 also provides a
cross-reference between the City’s previously established shortage levels and the
mandated standard shortage levels.
Corresponding Relationships Between Supplier's Established Shortage Levels and
the WSCP Mandated Shortage Levels
Established
Level
Supply
Condition/Shortage
WSCP
Standard
Level
Shortage Level
1
1 to 10%
2 10% 2 10 to 20%
3 11 to 15% 3 20 to 30%
4 16 to 20% 4 30 to 40 %
5 21 to 25%
5 40 to 50 %
6 26 to 30% 6 > 50 %
7 31 to 40%
8 41 to 50%
SHORTAGE RESPONSE ACTIONS
CWC 10632.
(a)(4) Shortage response actions that align with the defined shortage levels and include, at a
minimum, all of the following:
(A) Locally appropriate supply augmentation actions.
(B) Locally appropriate demand reduction actions to adequately respond to shortages.
(C) Locally appropriate operational changes.
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(D) Additional, mandatory prohibitions against specific water use practices that are in addition to
state-mandated prohibitions and appropriate to the local conditions.
(E) For each action, an estimate of the extent to which the gap between supplies and demand will
be reduced by implementation of the action.
SUPPLY AUGMENTATION
As discussed in Chapter 6, the City’s sources of water supply include groundwater
produced from the Main Basin and Raymond Basin and imported surface water
purchased from MWD through Upper Water. As noted in Section 8.2, the City is required
to annually prepare and submit an Annual Assessment which will include a review of
water supplies available to meet water demands for the current and upcoming years. If
the City is currently in, or considers entering into, one of the standard water shortage
levels identified in Section 8.3, the City will consider the water supply augmentation
actions described below.
For each water shortage level discussed in Section 8.3, the City will consider
supplementing its existing water supplies through purchase of additional imported water
supplies. Due to previous critically dry conditions, MWD developed the “Water Supply
Allocation Plan” whereby available supplies are equitably allocated to its member
agencies, including Upper Water. The WSAP establishes ten different shortage levels
and a corresponding drought allocation to each member agency. Based on the shortage
level established by MWD, the WSAP provides a reduced drought allocation to a member
agency for its Municipal and Industrial retail demand. The ratio of MWD water supply
drought allocation to local water supply will change based on the WSAP stage. The MWD
drought allocation can be used to make Full Service water deliveries at the Tier 1 rate up
to a Tier 1 allocation. Any Full Service water delivered in excess of a drought allocation
is subject to a penalty rate in addition to the normal rate paid for the water.
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In addition to the WSAP, MWD describes supply augmentation actions in its Regional
2025 UWMP, which is incorporated by reference. MWD’s primary first response to any
gap between core supplies (from the State Water Project and Colorado River) and
demand is to make optimal use of its supply augmentation options, consisting of drawing
from flexible supply programs and storage reserves. MWD has developed and actively
manages a portfolio of water supply programs including water transfer, storage, and
exchange agreements. MWD pursues voluntary water transfer and exchange programs
to help mitigate supply/demand imbalances and provide additional dry-year supply
sources. In addition, MWD has developed significant storage capacity in reservoirs,
conjunctive use, and other groundwater storage programs totaling approximately 6.0
million AF. Based on MWD’s historical and on-going water supply and storage programs
and management practices, the City can potentially rely on purchased imported water
supplies from MWD through Upper Water for adequate supply augmentation in response
to each of the standard water shortage levels identified in Section 8.3.
The City will consider supplementing its existing water supplies through production of
additional groundwater from the Main Basin. As noted in Section 6.2.2, the Main Basin is
managed by the Main Basin Watermaster. During the period of management under the
Main Basin Judgment, significant drought events have occurred. In each drought cycle
the Main Basin has been managed to maintain water levels. Parties to the Main Basin
Judgment, including the City, are authorized to produce groundwater in excess of their
rights and pay assessments for such production to the Main Basin Watermaster. The
assessments are used to purchase untreated imported water to replenish the Main Basin.
The Main Basin Watermaster purchases untreated imported water to replenish the Main
Basin from MWD through Upper Water. An additional potential source of replenishment
water is recycled water. Groundwater quality is carefully monitored and managed by the
Main Basin Watermaster. Treatment facilities and/or blend plans have been developed
by water agencies to meet potable water standards and to prevent the spread of any
groundwater contamination. Groundwater quality in the Main Basin is not expected to
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impact potable supplies or constrain supply reliability. Based on historical and on-going
management practices, the City will be able to continue relying on the Main Basin for
adequate supplies in response to each of the standard water shortage levels identified in
Section 8.3.
DEMAND REDUCTION
The City may establish water shortage response actions to reduce demand on water
supplies. These demand reduction actions include irrigation and other outdoor use
restrictions, rate structure changes, and other water use prohibitions. Depending on the
percent reduction in the City’s water supply and corresponding water shortage level,
regulations are made to conserve water and reduce the shortage gap in normal supply
levels. Many demand reduction actions, identified as voluntary or mandatory conservation
measures, are applicable to all levels of water shortages. The structure of water shortage
levels are designed to strongly encourage customers with high per capita usage to
achieve proportionally greater reduction than those with low usage. Violations of these
demand reduction actions will be considered waste and an unreasonable use of water.
Table 8-3 describes each demand reduction action and its effect on reducing the shortage
gap.
Upon adoption of a water supply shortage stage, as described Table 8-1, the restrictions
and mandatory water reduction demands will be effective immediately. A full listing of the
restrictions/prohibitions associated with each shortage level is provided below.
Water Shortage Level 1
(a) There shall be no hose washing of sidewalks, walkways, driveways, or parking
areas.
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(b) There shall be no hose washing of a motor vehicle, except where the hose is
fitted with a shut-off nozzle or similar device that causes the hose to cease
dispensing water immediately when not in use.
(c) No water shall be used to clean, fill or maintain levels in decorative fountains
unless such water is part of a recirculating system.
(d) No restaurant, hotel, cafe, cafeteria, bar or other public place where food or
beverage is served or offered for sale, shall serve drinking water to any
customer unless expressly requested by the customer.
(e) No hotel or motel shall launder towels and linens of an occupied guestroom on
a daily basis, unless expressly requested by the guest. The hotel or motel shall
prominently display a notice in each guestroom of the guest's option not to have
towels and linens laundered daily.
(f) No customer of the Water Division shall permit water to leak from any facility
on his premises.
(g) No lawn, landscape, or other turf areas shall be watered or irrigated between
the hours of 9:00 a.m. and 6:00 p.m. Pacific time.
(h) No lawn, landscape, or other turf areas shall be watered or irrigated during and
within 48 hours after measurable rainfall.
(i) No lawn, landscape, or other turf areas shall be watered or irrigated more than
3 days per week, or such other number of days as the City Council may
prescribe by resolution from time to time10. The three days per week shall be
Tuesday, Thursday, and Saturday or such other days as the City Council may
prescribe by resolution from time to time. Notwithstanding the foregoing, upon
written application to and approval by the City's Public Works Services Director,
an owner of property used primarily for commercial, industrial or institutional
10 Pursuant to Resolution No. 7430 adopted by City Council in May 2022, no lawn, landscape, or other turf
areas shall be watered or irrigated more than two (2) days per week (on Tuesday and Saturday). From May
to October, outdoor watering of lawn, landscape or other turf areas shall be limited to no more than 10
minutes per station on each day allowed. Resolution No, 7430 is provided in Appendix N.
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purposes may irrigate lawn, landscape or other turf areas of such property such
number of days per week as approved by the Public Works Services Director
if such owner provides evidence, to the satisfaction of the Public Works
Services Director, that the owner has reduced overall bi-monthly water use for
such property by at least twenty-five percent (25%) from the same bi-monthly
period in 2013, or by such other measurement of reduction adopted by
resolution of the City Council from time to time11.
(j) No lawn, landscape or other turf areas shall be watered in a wasteful manner.
For example, in a manner that causes runoff such that water flows onto
adjacent property, non-irrigated areas, private and public walkways, roadways,
parking lots, or structures.
(k) Additional restrictions and conservation measures may be adopted from time
to time by resolution of the City Council and shall become effective upon their
adoption. Any and all such restrictions and measures shall be subject to all
enforcement provisions, including without limitation fines and penalties, as are
otherwise applicable to the provisions set forth in this Section.
Water Shortage Level 2
No use of water may be made contrary to the provisions of Water Shortage Level 1. No
customer shall make, cause use or permit the use of water from the Water Division for
any purpose in an amount in excess of eighty percent (80%) of the amount used during
the base period as defined in this Urgency Ordinance.
11 Pursuant to Resolution No. 7430 adopted by City Council in May 2022, an owner of property used
primarily for commercial, industrial, or institutional purposes may not irrigate non-functional turf areas. "Non-
functional turf' means turf that is solely ornamental and not regularly used for human recreational purposes
or for civic or community events. Resolution No, 7430 is provided in Appendix N.
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Water Shortage Level 3
No use of water may be made contrary to the provisions of Water Shortage Level 1. No
customer shall make, cause, use or permit the use of water from the Water Division for
any purpose in an amount in excess of seventy percent (70%) of the amount used during
the base period as defined in this Urgency Ordinance.
Water Shortage Level 4
No use of water may be made contrary to the provisions of Water Shortage Level 1. No
customer shall make, cause, use or permit the use of water from the Water Division for
any purpose in an amount in excess of sixty percent (60%) of the amount used during the
base period as defined in this Urgency Ordinance.
Water Shortage Level 5
No use of water may be made contrary to the provisions of Water Shortage Level 1. No
customer shall make, cause, use or permit the use of water from the Water Division for
any purpose in an amount in excess of fifty percent (50%) of the amount used during the
base period as defined in this Urgency Ordinance.
Water Shortage Level 6
No use of water may be made contrary to the provisions of Water Shortage Level 1. No
customer shall make, cause, use or permit the use of water from the Water Division for
any purpose in an amount more than fifty (50%) of the amount used during the base
period as defined in this Urgency Ordinance.
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OPERATIONAL CHANGES
During a water supply shortage situation, the City will manage its water supply resources
to provide sufficient water supplies capable of meeting the demands of its customers.
Section 8.4.1 describes the City’s water supply sources and water supply augmentation
actions available. Section 8.4.2 describes the City’s standard water shortage levels and
associated demand reduction measures. The supply augmentation actions and demand
reduction measures, when implemented, may potentially result in short-term operational
changes which are necessary to allow the City to utilize all available water supply sources
in response to water shortage situations.
As noted in Section 8.2, the City is required to annually prepare and submit an Annual
Assessment which will include a review of the water supplies available to meet water
demands for the current and upcoming years. Preparation of the Annual Assessment will
assist the City in determining any potential operational changes. In addition, the City’s
standard water shortage levels and the associated demand reduction measures, in
conjunction with the City’s existing Demand Management Measures (discussed in
Chapter 9), will be essential to the City in reducing water demands during any water
shortage period. The operational changes the City will consider in addressing non-
catastrophic water shortages on a short-term basis include the following:
x Improved monitoring, analysis, and tracking of customer water usage to enforce
demand reduction measures
x Optimized production from existing available water supply sources
x Potential use of emergency supply sources, including emergency interconnections
x Potential blending of water supply resources
x Improved monitoring, maintenance, and repairs to reduce water distribution
system losses
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ADDITIONAL MANDATORY RESTRICTIONS
The mandatory restrictions which are implemented by the City to reduce customer
demands are discussed in Section 8.4.2. There are no additional mandatory restrictions
planned at this time.
EMERGENCY RESPONSE PLAN
Catastrophic water shortages are incorporated in the City’s standard water shortage
levels (identified in Section 8.3) and the associated demand reduction measures
(described in Section 8.4.2). In addition to the water supply augmentation actions
(Section 8.4.1) and potential operational changes (Section 8.4.3) which the City may
consider in order to continue providing sufficient water supplies, the City will review and
implement any necessary steps included in its “Emergency Response Plan”.
The City’s Emergency Response Plan (ERP), updated in 2021, provides the
management, procedures, and designated actions the City and its employees will
implement during emergency situations (including catastrophic water shortages) resulting
from natural disasters, system failures and other unforeseen circumstances. The City’s
ERP (which is incorporated by reference) provides the guidelines for evaluating an
emergency situation, procedures for activating an emergency response, and details of
the different response phases in order to ensure that customers receive a reliable and
adequate supply of potable water. The scope of the ERP includes emergencies which
directly affect the water system and the ability to maintain safe operations (such as a
chlorine release, and earthquake or a threat of contamination). The ERP also
incorporates the following:
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x Strategies and resources to improve resilience, including physical and
cybersecurity
x Plans and procedures for responding to a natural hazard or malevolent act
x Actions and equipment to lessen the impact of a natural hazard or malevolent act
x Strategies to detect natural hazards or malevolent act
The City will review the ERP for procedures regarding the utilization of alternative water
supply sources in response to water supply shortages, including during the standard
water shortage levels. The City will also review applicable procedures described in the
ERP regarding any necessary temporary shutdown of water supply facilities, including
appropriate regulatory and public notifications.
SEISMIC RISK ASSESSMENT AND MITIGATION PLAN
CWC 10632.5.
(a) In addition to the requirements of paragraph (3) of subdivision (a) of Section 10632, beginning
January 1, 2020, the plan shall include a seismic risk assessment and mitigation plan to
assess the vulnerability of each of the various facilities of a water system and mitigate those
vulnerabilities.
(b) An urban water supplier shall update the seismic risk assessment and mitigation plan when
updating its urban water management plan as required by Section 10621.
(c) An urban water supplier may comply with this section by submitting, pursuant to Section 10644,
a copy of the most recent adopted local hazard mitigation plan or multihazard mitigation plan
under the federal Disaster Mitigation Act of 2000 (Public Law 106-390) if the local hazard
mitigation plan or multihazard mitigation plan addresses seismic risk.
The City prepared a “Local Hazard Mitigation Plan” in 2022. The Hazard Mitigation Plan
identifies effective ways to assess the significant natural hazards (including earthquakes)
that may affect the City and its residents. The Hazard Mitigation Plan provides resources,
information, and strategies to reduce the City’s vulnerability to these hazards, while
providing guidance for the coordination of mitigation activities throughout the City. The
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Hazard Mitigation Plan includes mitigation projects necessary to reduce seismic risk to
the City’s water distribution system facilities (including its distribution system pipelines,
groundwater wells, booster pumps, and storage reservoirs) and potential disruptions in
providing water service. The City’s Hazard Mitigation Plan is provided in Appendix K.
The County of Los Angeles prepared a “All-Hazards Mitigation Plan” in 2025 which
identified methods to assess significant natural hazards (including earthquakes) affecting
areas throughout Los Angeles County, and the mitigation strategies necessary to reduce
risks, including seismic risk. The County’s All-Hazards Mitigation Plan is provided in
Appendix L.
The California Geological Survey has published the locations of numerous faults which
have been mapped in the Southern California region. Although the San Andreas fault is
the most recognized and is capable of producing an earthquake with a magnitude greater
than 8 on the Richter scale, some of the lesser-known faults have the potential to cause
significant damage. The locations of these earthquake faults in the vicinity of the City’s
water service area are provided in the figure below. The faults that are located in close
proximity to and could potentially cause significant shaking in the City’s water service area
include the San Andreas fault, the Walnut Creek fault, the Whittier fault, the San Jose
fault, the Raymond fault, the Cucamonga fault, the Chino fault, the Sierra Madre fault,
and the East Montebello fault.
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Location of Earthquake Faults
Source: https://maps.conservation.ca.gov/cgs/fam/App/
The California Geological Survey provides earthquake hazard maps12 based on the
Modified Mercalli Intensity (MMI) scale, which measures earthquake shaking intensity and
its impacts on people, objects, and buildings. The area within the City’s service area has
an MMI of approximately 9.6 calculated based on the level of shaking that has a 2 percent
chance of being exceeded in 50 years (or the level of shaking with an approximate 2,500-
year average repeat time). An MMI at this intensity (violent shaking) can result in
buildings shifted off foundations, cracked, or tilted, the ground cracked, and underground
pipes broken. As discussed in Section 8.4.5, the City has prepared an Emergency
Response Plan which provides the management, procedures, and designated actions the
12 https://conservation.ca.gov/cgs/sh/earthquake-shaking-potential
City’s Service Area
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City and its employees will implement during emergency situations resulting from natural
disasters, including during earthquakes, to ensure that customers receive a reliable and
adequate supply of potable water. The City’s ERP is referenced herein.
SHORTAGE RESPONSE ACTION EFFECTIVENESS
The effectiveness of the shortage response actions for each of the standard water
shortage levels identified in Section 8.3 is evident in the City’s historical ability to meet its
customer’s water demands in response to a water supply shortage. In addition, the City
imposes water consumption regulations and restrictions, and supports local agencies in
efforts to enforce regulations and prohibitions on water use. The effectiveness of each of
the City’s shortage response actions, in order to reduce any potential gaps between
supply and demand, has been quantified in the expected demand reduction provided in
Table 8-2 and Table 8-3.
Section 6.1 provides a tabulation of the City’s historical annual water demands for each
water supply source. During the past 15 years, the City experienced a five-year
consecutive drought within its service area from FY 2011-12 to FY 2015-16. Throughout
this extended dry year period, the City’s annual water production ranged from 12,369 AF
to 17,452 AF, with an average of approximately 15,751 AF. In addition, historical records
indicate the City previously produced a maximum of up to 18,668 AF during FY 2006-07.
The City has been able to provide sufficient water supplies to its customers, including
during long-term droughts and years with historically high water demands. In addition, the
City has been able to provide water service to meet maximum day water demands for
these years, including during the summer months.
The City’s water demands during the most recent five years (from FY 2020-21 to FY 2024-
25) averaged approximately 13,215 AFY. Due to conservation efforts and demand
management measures (discussed in Chapter 9), the City’s recent water demands have
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been significantly less than its historical water demands, including during long-term
droughts. The City’s projected water demands (during normal, single dry, and multiple
dry years) are provided in Section 7.2.3 and are anticipated to incorporate similar
reductions in water use rates as a result of the shortage response actions, ongoing
conservation efforts, and demand management measures. Because the City’s projected
water demands are similar to or less than its historical water demands, it is anticipated
the City will be able to continue providing sufficient water supplies to its customers to
meet projected water demands, including during long-term droughts. In addition, as
discussed in Section 8.4.1, based on historical and on-going management practices, the
City will be able to continue relying on its water supply sources from the Main Basin and
Raymond Basin for adequate supply augmentation in response to each of the standard
water shortage levels identified in Section 8.3.
Based on the City’s ability in meeting water demands during past water supply shortages,
adopted water shortage levels, adjusted operating safe yields, and long-term droughts, it
is anticipated that the City will be able to continue providing sufficient water supplies to
its customers during any of its standard water shortage levels. Although adequate
supplies are anticipated, the cost of those water supplies may become incrementally more
expensive. The City will enact varying levels of its water shortage contingency plan to
encourage retail customers to reduce water consumption and at the same time reduce
the need to use the more expensive water supplies. Notwithstanding, the effectiveness
of each of the City’s shortage response actions, in order to reduce any potential gaps
between supply and demand, has been quantified in the expected demand reduction
provided in Table 8-2 and Table 8-3. The effectiveness of the City’s shortage response
actions is based on the City’s water demands prior to 2015 (unconstrained demands).
The City reduced its water demands in 2015 in response to the Governor’s April 1, 2015
Executive Order B-29-15 which mandated statewide reduction in water use of 25 percent.
During this period, the City was able to reduce its water demands by approximately 29
percent. This historical water demand reduction was used to estimate the extent of water
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use reductions for the City’s Water Shortage Stages. The City’s Water Shortage Levels
1, 2, 3, 4, 5, and 6 are expected to reduce water demands by up to 10%, 20%, 30%, 40%,
50%, and greater than 50%, respectively.
Emergency regulations previously adopted by the SWRCB pursuant to Executive Order
N-7-22 (issued on March 28, 2022 by California Governor Gavin Newsom) required urban
water suppliers to implement Level 2 of their Water Shortage Contingency Plans meant
to address up to a 20% shortage of water supplies. The regulations also required urban
water suppliers to establish a ban on irrigating non-functional turf at commercial,
industrial, and institutional properties (including grass in front of or next to large industrial
or commercial buildings). The ban did not include watering turf that is used for recreation
or other community purposes, water used at residences or water to maintain trees.
Pursuant to Executive Order N-5-23 issued on March 24, 2023 by California Governor
Gavin Newsom, the requirement for urban water suppliers to implement Level 2 of their
Water Shortage Contingency Plans was removed. As of June 5, 2024, SWRCB statewide
water conservation emergency regulations have expired and there are no current
statewide water conservation emergency regulations.
COMMUNICATION PROTOCOLS
CWC 10632.
(a)(5) Communication protocols and procedures to inform customers, the public, interested
parties, and local, regional, and state governments, regarding, at a minimum, all of the
following:
(A) Any current or predicted shortages as determined by the annual water supply and
demand assessment described pursuant to Section 10632.1.
(B) Any shortage response actions triggered or anticipated to be triggered by the annual
water supply and demand assessment described pursuant to Section 10632.1.
(C) Any other relevant communications.
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The City is required to submit an “Annual Water Supply and Demand Assessment”
(Annual Assessment) in accordance with DWR’s guidance and requirements. The Annual
Assessment will include a review of the City’s unconstrained water demands (i.e. water
demands prior to any projected response actions the City may trigger under this WSCP)
for the current year and the upcoming (potential single dry) year. The City will also include
information regarding anticipated shortages, triggered shortage response actions,
compliance and enforcement actions, and communication actions consistent with the
City’s WSCP. See Section 8.2 for further discussion regarding the Annual Assessment.
The City will evaluate the projected supply and demand for water by its customers and
shall recommend to the City Council the extent of the conservation required by the
customers of the Water Division. The City Council will discuss the appropriate phase of
water conservation be implemented, modified or rescinded. The City will publish
information regarding the adoption of any resolution declaring a water shortage level in
a daily newspaper of general circulation. The information provided will include the
declared shortage level, response action associated with each shortage level, and any
other relevant information relating to the resolution.
COMPLIANCE AND ENFORCEMENT
CWC 10632.
(a)(6) For an urban retail water supplier, customer compliance, enforcement, appeal, and
exemption procedures for triggered shortage response actions as determined pursuant to
Section 10632.2.
It is unlawful and a misdemeanor for any customer to fail to comply with any provisions
of the regulations and restrictions on water use set forth in the City’s Ordinance. The City
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has implemented a three-step enforcement plan for the Phase I Prohibitions. Customers
violating the mandatory prohibitions will be subject to the procedures and/or penalties as
outlined below.
First Violation: For the first violation by any customer of the Water Division of any of the
provisions discussed in Section 8.4.2, a surcharge penalty, in addition to the current water
rate, is imposed in an amount equal to two times the current water rate for those billing
units used in excess of base.
Second Violation: For the second violation by any customer of the Water Division of any
of the provisions discussed in Section 8.4.2, a surcharge penalty, in addition to the current
water rate, is imposed in an amount equal to three times the current water rate for those
billing units used in excess of base.
Third Violation: For the third violation by any customer of the Water Division of any of the
provisions discussed in Section 8.4.2, a surcharge penalty, in addition to the current water
rate, is imposed in an amount equal to four times the current water rate for those billing
units used in excess of base.
If any customer fails to comply with any provision of the regulations and restrictions on
water use set forth in the City’s Ordinance, the Water Division may reduce the amount of
water provided to that customer to the level which that customer would be using said
water if he were complying with the provisions. The reduction in water supplies may be
applied in lieu of, or in addition to, any other penalties provided in this Chapter, in the
discretion of the Water Division, and will be applied without regard to the status or nature
of the customer.
The following procedural requirements shall apply with regard to an appeal:
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(a) An appeal may be filed within ten (10) working days after a final decision by the
Water Division to the Water Appeals Board. The appeal should state the grounds
upon which it is based, and what remedy, if any, the Appellant seeks.
LEGAL AUTHORITIES
CWC 10632.
(a)(7)(A) A description of the legal authorities that empower the urban water supplier to implement
and enforce its shortage response actions specified in paragraph (4) that may include,
but are not limited to, statutory authorities, ordinances, resolutions, and contract
provisions.
(B) A statement that an urban water supplier shall declare a water shortage emergency in
accordance with Chapter 3 (commencing with Section 350) of Division 1. [see below]
(C) A statement that an urban water supplier shall coordinate with any city or county within which
it provides water supply services for the possible proclamation of a local emergency, as
defined in Section 8558 of the Government Code.
CWC Division 1, Section 350
The governing body of a distributor of a public water supply, whether publicly or privately owned
and including a mutual water company, shall declare a water shortage emergency condition to
prevail within the area served by such distributor whenever it finds and determines that the
ordinary demands and requirements of water consumers cannot be satisfied without depleting the
water supply of the distributor to the extent that there would be insufficient water for human
consumption, sanitation, and fire protection.
In the event that the demand of water consumers cannot be satisfied without depleting a
substantial amount of water supply needed for human consumption, sanitation, and fire
protection, the City shall declare a water shortage emergency (in accordance with Water
Code Chapter 3 commencing with Section 350 of Division 1 regarding water shortage
emergencies). The City shall coordinate with any city or county within its service area for
possible declaration of a local emergency, as defined in Section 8588 of the Government
Code.
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The City’s Ordinance No. 2327 implements measures to ensure sufficient water supplies
are available for sanitation, fire suppression, and domestic use. The City adopted
Ordinance No. 2036 which added three water shortage levels, exceeding the State’s
requirement. The City incorporated more shortage levels to provide additional flexibility
and prevent over-mandated water conservation by its customers.
FINANCIAL CONSEQUENCES OF WSCP
CWC 10632.
(a)(8) A description of the financial consequences of, and responses for, drought conditions,
including, but not limited to, all of the following:
(A) A description of potential revenue reductions and expense increases associated with
activated shortage response actions described in paragraph (4).
(B) A description of mitigation actions needed to address revenue reductions and expense
increases associated with activated shortage response actions described in paragraph (4).
(C) A description of the cost of compliance with Chapter 3.3 (commencing with Section 365) of
Division 1. [retail urban suppliers only]
During periods of water supply shortages, state-mandated water use restrictions, or
emergency conditions, the City may require its customers to reduce demands below
levels projected under the current water rate structure. Under any of these circumstances,
the City may experience a decrease in revenues that may result in insufficient funds to
meet projected expenses.
The City’s Water Fund, commonly referred to as “financial reserves”, is comprised of an
Operating Fund and Equipment Fund. The Water Fund is available to be used for water
system expenditures to make up for shortfalls in water revenue. Based on the Cost of
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City of Arcadia Page 8-28
Service Study, the City targets an Operating Fund equivalent to 90 days of operating
expenses and has historically maintained an Equipment Fund (Facilities Reserve).
Revenue collected as a result of penalties imposed (discussed in Section 8.6) shall be
used for, but not limited to the purchase of imported water, increasing water supplies,
maintenance of the City's water system, and water conservation efforts including public
education.
MONITORING AND REPORTING
CWC 10632.
(a)(9) For an urban retail water supplier, monitoring and reporting requirements and procedures
that ensure appropriate data is collected, tracked, and analyzed for purposes of monitoring
customer compliance and to meet state reporting requirements.
The City employs a Management Analyst who is responsible for responding to reports of
water waste or noncompliance. Upon receiving public reports, work orders will be
generated and two written notices, which will include a date by which a customer must
resolve violations, will be physically left at the property and sent by mail. In addition,
courtesy phone calls may be made to follow up with the violator. The SFR water meter
will be data logged showing hourly use over 7 days after the mailed deadline. If the violator
is nonresponsive after review of the data log, then a citation will be issued for $100.
Subsequent violations may receive citations up to $500.
2025 Urban Water Management Plan
City of Arcadia Page 8-29
WSCP REFINEMENT PROCEDURES
CWC 10632.
(a)(10) Reevaluation and improvement procedures for systematically monitoring and evaluating the
functionality of the water shortage contingency plan in order to ensure shortage risk
tolerance is adequate and appropriate water shortage mitigation strategies are
implemented as needed.
The City’s Water Shortage Contingency Plan has been prepared as an adaptive
management plan. As discussed in Section 8.9, the City will monitor and report on the
implementation of the Water Shortage Contingency Plan. The City will review the
implementation results for any current or potential shortage gaps between water supplies
and demands. The City will evaluate the need for revising the Water Shortage
Contingency Plan in order to resolve any shortage gaps, as necessary. The City will
consider the following potential revisions in the event of a potential shortage gap:
x Implementation of additional public outreach, education, and communication
programs (in addition to the programs discussed in Chapter 9).
x Implementation of more stringent water use restrictions under the standard water
shortage levels (discussed in Section 8.4)
x Implementation of stricter enforcement actions and penalties (discussed in Section
8.6)
x Improvements to the water supply augmentation responses (discussed in Section
8.4.1), as well as any associated operational changes (discussed in Section 8.4.3)
which may be required
x Incorporation of additional actions recommended by City staff or other interested
parties
2025 Urban Water Management Plan
City of Arcadia Page 8-30
The City will use the monitoring and reporting data to evaluate the ability for these
potential revisions to resolve any shortage gaps which may occur within the standard
water shortage levels.
This Water Shortage Contingency Plan is adopted as part of the City’s 2025 Urban Water
Management Plan adoption process discussed in Section 10.3. It is anticipated the City
will review, revise, and adopt an updated Water Shortage Contingency Plan as part of
preparing its 2030 Urban Water Management Plan as necessary. However, the City will
continue to review the monitoring and reporting data, and if needed, update the Water
Shortage Contingency Plan more frequently. Any updates to the City’s Water Shortage
Contingency Plan will include a public hearing and adoption process by the City Council
(see Section 8.12).
SPECIAL WATER FEATURE DISTINCTION
CWC 10632.
(b) For purposes of developing the water shortage contingency plan pursuant to subdivision (a), an
urban water supplier shall analyze and define water features that are artificially supplied with
water, including ponds, lakes, waterfalls, and fountains, separately from swimming pools and
spas, as defined in subdivision (a) of Section 115921 of the Health and Safety Code.
The City’s Water Shortage Contingency Plan defines “decorative water features” as water
features which are artificially supplied with water, including ponds, lakes, waterfalls, and
fountains, but excluding pools and spas. In general, there are additional health and safety
considerations in the water supplied to pools and spas compared to decorative water
features. As a result, the City’s Water Shortage Contingency Plan has reviewed the
response actions, enforcement actions, and monitoring and reporting programs
separately for decorative water features and for pools and spas, as applicable. As noted
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City of Arcadia Page 8-31
under Water Shortage Level 1, “No water shall be used to clean, fill or maintain levels in
decorative fountains unless such water is part of a recirculating system”.
PLAN ADOPTION, SUBMITTAL, AVAILABILITY, AND AMENDMENT
PROCEDURES
CWC 10632.
(c) The urban water supplier shall make available the water shortage contingency plan prepared
pursuant to this article to its customers and any city or county within which it provides water
supplies no later than 30 days after adoption of the water shortage contingency plan.
The City’s Water Shortage Contingency Plan is adopted as part of the City’s 2025 Urban
Water Management Plan adoption process discussed in Chapter 10. The process for
adopting the City’s Water Shortage Contingency Plan includes the following:
x The City will conduct a public hearing and make the Water Shortage Contingency
Plan available for public inspection.
x The City will provide notification of the time and place of the public hearing to any
city or county in which water is provided.
x The City will publish notice of public hearing in a newspaper once a week, for two
successive weeks (with at least five days between publication dates).
x The City Council will adopt the 2025 Urban Water Management Plan and the Water
Shortage Contingency Plan
x As part of submitting the 2025 Urban Water Management Plan to DWR, the City
will also submit the Water Shortage Contingency Plan (electronically through
DWR’s online submittal tool) within 30 days of adoption and by July 1, 2026. The
City will submit a copy of the Water Shortage Contingency Plan to the California
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City of Arcadia Page 8-32
State Library and to any city or county in which water is provided within 30 days of
adoption. In addition, the City will make the Water Shortage Contingency Plan
available for public review within 30 days of adoption.
If there are any subsequent amendments required, the process for adopting an amended
Water Shortage Contingency Plan includes the following:
x The City will conduct a public hearing and make the amended Water Shortage
Contingency Plan available for public inspection.
x The City Council will adopt the amended Water Shortage Contingency Plan
x The City will submit the amended Water Shortage Contingency Plan to DWR
(electronically through DWR’s online submittal tool) within 30 days of adoption
Additional information regarding the adoption, submittal, and availability of the City’s
Water Shortage Contingency Plan (and 2025 Urban Water Management Plan) is provided
in Chapter 10.
RESOURCES AND REFERENCES
DWR’s Final 2025 UWMP Guidebook provides a listing of resources and references
which can be helpful during the preparation of a Water Shortage Contingency Plan.
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 8 are provided
below.
2025 Urban Water Management Plan
City of Arcadia Page 8-33
TABLE 8-1: CROSS REFERENCE FOR STANDARD VS.
SUPPLIER SHORTAGE LEVELS
Table 8-1 Cross-Reference for Standard vs. Supplier Shortage Levels
2025 Urban Water Management Plan
City of Arcadia Page 8-34
TABLE 8-2: SUPPLY AUGMENTATION AND OTHER ACTION
Table 8-2 Supply Augmentation and Other Actions
Yes
Volume or
Percentage
Drop down
Shortage Gap
Reduction Value
(May be a range)
(AF)
1 Transfers Volume 0 Not applicable (see Notes)
2 Transfers Volume 0 Not applicable (see Notes)
3 Transfers Volume 0 Not applicable (see Notes)
4 Transfers Volume 0 Not applicable (see Notes)
5 Transfers Volume 0 Not applicable (see Notes)
6 Transfers Volume 0 Not applicable (see Notes)
Submittal Table 8-2 Retail: Supply Augmentation and Other Actions
Water Code Section 10632(a)(4)(A),(C) and (E)
Add additional rows as needed
NOTES: The City will consider increased production from the Main Basin using existing facilities to address increased demands.
As noted on Table 8-3, the City plans to implement demand reduction measures in the event water supplies from existing
sources are not sufficient to meet anticipated demands.
Is the Supplier completing this table using the standard six levels? (yes/no)
How much is this going to reduce the
shortage gap?
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
Shortage
Level
Supply Augmentation Methods and
Other Actions by Water Supplier
Drop down list
These are the only categories that will
be accepted by the WUEdata online
submittal tool
Additional Explanation or Reference
(OPTIONAL)
2025 Urban Water Management Plan
City of Arcadia Page 8-35
TABLE 8-3: DEMAND-REDUCTION ACTIONS
Table 8-3 Demand-Reduction Actions
Yes
Volume or
Percentage
Drop down
Shortage Gap
Reduction Value
(May be a range)
(AF)
1 Landscape - Restrict or prohibit
runoff from landscape irrigation Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Other - Require automatic shut of
hoses Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Landscape - Limit landscape
irrigation to specific days Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Pursuant to Resolution No. 7430 adopted by City
Council in May 2022, no lawn, landscape, or
other turf areas shall be watered or irrigated
more than two (2) days per week (on Tuesday
and Saturday).
Yes
1 Landscape - Limit landscape
irrigation to specific times Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
No lawn, landscape, or other turf areas shall be
watered or irrigated between the hours of 9:00
a.m. and 6:00 p.m. Pacific time.
Yes
1 Landscape - Prohibit certain types
of landscape irrigation Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Pursuant to Resolution No. 7430 adopted by City
Council in May 2022, an owner of property used
primarily for commercial, industrial, or
institutional purposes may not irrigate non-
functional turf areas.
Yes
1 Landscape - Other landscape
restriction or prohibition Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
No irrigation during and within 48 hrs of
measurable rainfall Yes
Is the Supplier completing this table using the standard six levels? (yes/no)
Submittal Table 8-3 Retail: Demand Reduction Actions
Water Code Section 10632(a)(4)(B),(D), and (E)
Add additional rows as needed
How much is this going to reduce the
shortage gap?
Shortage
Level
Demand Reduction Actions
Drop down list
These are the only categories that will
be accepted by the WUEdata online
submittal tool. Select those that apply.
Additional Explanation or Reference
(OPTIONAL)
Penalty, Charge,
or Other
Enforcement?
For Retail Suppliers
Only
Drop Down List
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City of Arcadia Page 8-36
1 CII - Lodging establishment must
offer opt out of linen service Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 CII - Restaurants may only serve
water upon request Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1
Water Features - Restrict water use
for decorative water features, such
as fountains
Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1
Other - Customers must repair
leaks, breaks, and malfunctions in a
timely manner
Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Other - Prohibit use of potable
water for washing hard surfaces Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
2Other Volume
Collective reduction
from all Shortage
Level 2 actions is up
to 3,442 AF
All actions under Shortage Level 1 Yes
3Other Volume
Collective reduction
from all Shortage
Level 3 actions is up
to 5,163 AF
All actions under Shortage Level 2 Yes
4Other Volume
Collective reduction
from all Shortage
Level 4 actions is up
to 6,884 AF
All actions under Shortage Level 3 Yes
5Other Volume
Collective reduction
from all Shortage
Level 5 actions is up
to 8,605 AF
All actions under Shortage Level 4 Yes
6Other Volume
Collective reduction
from all Shortage
Level 6 actions is
greater than 8,605
AF
All actions under Shortage Level 5 Yes
NOTES:
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
2025 Urban Water Management Plan
City of Arcadia Page 9-1
CHAPTER 9
DEMAND MANAGEMENT MEASURES
LAY DESCRIPTION – CHAPTER 9
DEMAND MANAGEMENT MEASURES
Chapter 9 (Demand Management Measures) of the City’s 2025 Plan discusses and
provides the following:
x The City has implemented “Demand Management Measures” to reduce its water
demands and achieve its water use targets (discussed in Chapter 5)
x The City’s Demand Management Measures include adoption of an ordinance to
prevent water waste.
x The City’s Demand Management Measures include metering of all customer
connections, including separate metering for single-family residential, commercial,
industrial, large landscape and institutional/governmental facilities.
x The City’s Demand Management Measures include conservation pricing. The
City’s current water rate structure is tiered to promote water conservation by
customers.
x The City’s Demand Management Measures include public education and outreach
programs regarding water conservation.
x The City’s Demand Management Measures include various actions to assess and
manage water distribution system losses.
x Additional Demand Management Measures including rebate, conservation, and
educational programs are discussed.
x A summary of the Demand Management Measures the City has implemented over
the past five (5) years is provided. The City met the 2020 Water Use Target
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City of Arcadia Page 9-2
(discussed in Chapter 5) through the implementation of these Demand
Management Measures.
DEMAND MANAGEMENT MEASURES FOR RETAIL SUPPLIERS
CWC 10631.
(e) Provide a description of the supplier’s water demand management measures. This
description shall include all of the following:
(1)(A) For an urban retail water supplier, as defined in Section 10608.12, a narrative description
that addresses the nature and extent of each water demand management measure
implemented over the past five years. The narrative shall describe the water demand
management measures that the supplier plans to implement to achieve its water use
targets pursuant to Section 10608.20.
(B) The narrative pursuant to this paragraph shall include descriptions of the following water
demand management measures:
(i) Water waste prevention ordinances.
(ii) Metering.
(iii) Conservation pricing.
(iv) Public education and outreach.
(v) Programs to assess and manage distribution system real loss.
(vi) Water conservation program coordination and staffing support.
(vii) Other demand management measures that have a significant impact on water use as
measured in gallons per capita per day, including innovative measures, if implemented.
IMPLEMENTATION OVER THE PAST FIVE YEARS
The City is committed to implementing water conservation programs and works
collaboratively with Upper Water to provide water conservation programs for its residents.
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City of Arcadia Page 9-3
As a sub-agency of Upper Water, the City’s residents have the benefit of participating in
Upper Water’s conservation efforts. The highlights of DMM implementation over the past
five years are described below.
As discussed in Section 9.1.3.1, the City has adopted and implemented Ordinance No.
2327 and Resolution 7430 concerning outdoor irrigation and prohibited water uses. New
restrictions on outdoor irrigation and prohibited water uses were adopted.
As discussed in Section 9.1.3.2, the City metered all customer connections, including
separate metering for single-family residential, commercial, large landscape, and
institutional/governmental facilities during the past five years. Furthermore, if there was
new development within the City, each facility was individually metered. Service charges
for the City are based on the customers’ connection size.
As discussed in Section 9.1.3.3, The City’s Mandatory Water Conservation Program
contains penalties for overuse of water during drought times that are based on the various
stages enacted upon by resolutions passed by the Arcadia City Council. The City
maintains a tiered rate structure for residential customers to promote water conservation.
A water rate sheet showing current rates is provided in Appendix M.
As discussed in Section 9.1.3.4, The City informs and educates its customers on water
conservation through its quarterly newsletters, water bills, bill stuffers, biannual postcards,
social media websites, and the City’s website. The City participates in numerous
workshops throughout the year to promote water conservation (e.g. rain harvesting, leak
detection, etc.) Upper Water partners with the Discovery Science Center and THINK
Together to provide a free water conservation and sustainable watershed curriculum
program for fourth through sixth graders at schools within Upper Water. In 2020, the
program was proposed to expand to provide online options, as well as adding a seventh-
grade curriculum.
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City of Arcadia Page 9-4
As discussed in Section 9.1.3.5, the City utilizes WaterSmart Software that sends
customized monthly to quarterly consumption reports to residents. WaterSmart can alert
customers of irregular use, which may be caused by a leak. The City distributed water
conservation literature that alerted customers to be on the lookout for water system leaks
and to correct them promptly.
As a part of normal operation and maintenance of the water system, City staff performed
preventive maintenance. This included regular checks on valves and meters, and pipeline
maintenance. The City monitored the water system for losses by comparing water
production to water sales.
As described in Section 9.1.3.6, the City employs a Management Analyst who manages
the City’s water conservation program, completing state mandated reports, enforcing
ordinance, seeking grants, and conducting public outreach. The City plans to continue to
provide water conservation programs and staffing support.
As discussed in Section 9.1.3.7, the City participates in a regional rebate program, which
is available to the City’s residential and commercial customers. There are rebates
available for indoor plumbing including high efficiency clothes washers and toilets.
Rebates are also available for outdoor plumbing including those for weather-based
irrigation controllers, rotating sprinkler nozzles, and replacement of irrigated lawn with
drought tolerant plants or other approved landscape options. The City’s commercial
customers are offered rebates for retrofitting certain high water-use fixtures/equipment
with more water efficient models. The City plans to continue implementation of the
programs described to promote water conservation.
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City of Arcadia Page 9-5
IMPLEMENTATION TO ACHIEVE WATER USE TARGETS
CWC 10631.
(e)(1)(A) For an urban retail water supplier, as defined in Section 10608.12, a narrative
description that addresses the nature and extent of each water demand management
measure implemented over the past five years. The narrative shall describe the water
demand management measures that the supplier plans to implement to achieve its
water use targets pursuant to Section 10608.20.
As indicated in Section 5.2.2, the City previously met its 2020 Water Use Target as part
of the 2020 Plan. The City met the 2020 Water Use Target through the implementation of
the Demand Management Measures discussed in Section 9.1.3. Continued
implementation of these Demand Management Measures will assist the City in meeting
water use targets and objectives.
REQUIRED DEMAND MANAGEMENT MEASURES
9.1.3.1 WATER WASTE PREVENTION ORDINANCES
The City adopted Ordinance No. 2327 in April 2015 concerning outdoor irrigation and
prohibited water uses. The water demand reduction actions associated with Ordinance
No. 2327 are included under Water Shortage Level 1 described in Section 8.4.2.
As part of Ordinance No. 2327, the City Council is able to adjust the number of days per
week in which lawn, landscape, or other turf areas can be watered or irrigated. In May
2022, the City adopted Resolution No. 7430 which includes the following updated
provisions:
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City of Arcadia Page 9-6
x In winter (November through April) no lawn, landscape, or other turf areas shall be
watered or irrigated more than two (2) days per week, or such other number of
days as the City Council may prescribe by resolution from time to time. The two
days per week shall be Tuesday and Saturday or such other days as the City
Council may prescribe by resolution from time to time.
x In summer (May through October) no lawn, landscape, or other turf areas shall be
watered or irrigated more than two (2) days per week, or such other number of
days as the City Council may prescribe by resolution from time to time. The two
days per week shall be Tuesday and Saturday or such other days as the City
Council may prescribe by resolution from time to time. Furthermore, outdoor
watering of lawn, landscape or other turf areas shall be limited to no more than 10
minutes per station on each day allowed for such watering.
x Notwithstanding the foregoing, an owner of property used primarily for commercial,
industrial, or institutional purposes may not irrigate non-functional turf areas. "Non-
functional turf' means turf that is solely ornamental and not regularly used for
human recreational purposes or for civic or community events. Non-functional turf
does not include sports fields and turf that is regularly used for human recreational
purposes or for civic or community events.
Copies of the resolution and ordinance are provided in Appendix N.
The City’s service crews and meter readers also report wasteful uses of water, and
residents are contacted regarding leaks and significant sprinkler run-off.
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City of Arcadia Page 9-7
9.1.3.2 METERING
CWC 526.
(a) Notwithstanding any other provision of law, an urban water supplier that, on or after January
1, 2004, receives water from the federal Central Valley Project under a water service contract
or subcontract… shall do both of the following:
(1) On or before January 1, 2013, install water meters on all service connections to residential
and nonagricultural commercial buildings… located within its service area.
CWC 527.
(a) An urban water supplier that is not subject to Section 526 shall do both of the following:
(1) Install water meters on all municipal and industrial service connections located within its
service area on or before January 1, 2025.
The City is fully metered for all customer sectors, including separate meters for single-
family residential, multifamily residential, commercial, institutional and governmental
facilities. Furthermore, if there is new development within the City, each facility is
individually metered. Service charges for the City are based on the customers’ connection
size. The City’s system effectively promotes water conservation by being completely
metered. The City is continuing to install radio frequency read meters. Further information
regarding the City’s service fees and conservation pricing is provided in Section 9.1.3.3.
9.1.3.3 CONSERVATION PRICING
The City’s Mandatory Water Conservation Program, as outlined in its Municipal Code,
contains penalties for overuse of water during drought times that are based on the various
stages enacted upon by resolutions passed by the Arcadia City Council.
The City’s water rate structure consists of two components; a monthly service charge and
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City of Arcadia Page 9-8
a monthly water rate. The monthly water rate includes three tiers for single family
residential customers and two tiers for multi-family residential customers. The City’s rate
structure is designed to proportionately allocate a greater share of the costs of service to
those whose higher water usage generates additional costs to the water utility and
promotes efficient water usage and conservation. A water rate sheet showing current
rates is provided in Appendix M.
In addition, Upper Water implements conservation pricing to encourage subagencies to
conserve water. Additional information regarding Upper Water's conservation pricing can
be found in its 2025 Plan and is incorporated by reference.
9.1.3.4 PUBLIC EDUCATION AND OUTREACH
The City informs its customers about water conservation through its public information
programs. The City has a quarterly newsletter that is sent to the City’s customers, which
provides information about water conservation on a seasonal basis. The City also prints
water conservation messages periodically on its customer’s water bills. In addition, the
City’s “Hot Sheet”, which is mailed with the City’s water bills (a two-sided, one-page
leaflet), is also used to remind residents of useful water conservation tips, purposely
focused on a bimonthly basis either on indoor or outdoor conservation practices. The City
mails biannual postcards informing its customers of the City’s Seasonal Watering
Schedules. Lastly, the City is active on social media websites and the City’s website
contains additional useful information.
The City periodically holds public workshops to promote water conservation. The City
provides rainwater harvesting workshops and hosts an annual Earth Day workshop on
water conservation. The City’s Water Conservation Program also hosts free workshops
on leak detection to promote awareness during national Fix-a-Leak Week. In addition,
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City of Arcadia Page 9-9
the City annually participates in the Wyland Foundation’s National Mayor’s Challenge for
Water Conservation to spread awareness on good household water efficiency habits.
The City customers can also receive public information about water conservation through
Upper Water’s various public information programs. Upper Water offers conservation
brochures, posters, activity booklets, public outreach display and workshops. Upper
Water also raises awareness about water conservation through paid advertising, press
releases, news ads and media events. The City participates annually in Upper Water’s
annual Water 101 Forum, a large-scale educational event focused on water conservation.
Furthermore, the City along with the Los Angeles County Office of Education and Los
Angeles County of Public Works participate in the annual Los Angeles County
Environmental Education Fair (LAEEF), held at the Arboretum which is located in the City
of Arcadia. City staff is able to continue its dissemination of water conservation
information and related take home items by manning booths and speaking with area
residents, school-age children and educators.
The City’s customers receive educational tools regarding water conservation through
Upper Water’s school educational programs. Upper Water partners with the Discovery
Science Center and THINK Together to provide a free water conservation and sustainable
watershed curriculum program for fourth through sixth graders at schools within Upper
Water. The City’s customers may also participate in educational school programs through
MWD, which has extensive educational programs that includes schools within the City’s
boundaries.
Upper Water directly offers school education programs in an effort to raise awareness of
water issues. Upper Water started its school education programs in September 1992 and
the materials and presentations meet state education framework requirements. The
following is a list of Upper Water’s school educational programs:
2025 Urban Water Management Plan
City of Arcadia Page 9-10
x “Water is Life” Art Contest
x Watershed Restoration Program
x Sustainable Watershed Education Program
9.1.3.5 PROGRAMS TO ASSESS AND MANAGE DISTRIBUTION
SYSTEM REAL LOSS
The City’s estimated water system losses are discussed in Section 4.3. The City
continues installing radio frequency read meters to provide secure and accurate meter
data collection. The City repairs leaks within its distribution system on an as-needed
basis. The City closely monitors its water production and consumption use tabulating the
amount of “unaccounted for water”. The City has replaced many of its water meters with
newer models, significantly reducing the water loss compared to previous years. The
City’s current estimated “unaccounted for water” is less than one percent of the water
demand. The City calculates the amount of “unaccounted for water” by finding the
difference between the amount of water the City pumped and the amount of water sold
to its customers. This program is effective in maintaining distribution systems that deliver
water effectively and efficiently with the least amount of water loss. The amount of water
conserved through the City’s system water audits, leak detection and repair program can
be estimated by evaluating the average amount of “unaccounted for water”.
The City monitors customer’s water use through its computerized billing system. The City
utilizes WaterSmart Software that sends customized monthly to quarterly consumption
reports to residents. The City’s billing system automatically audits customer’s water bills
and flags those bills that show unusual or high consumption. The City’s billing system
alerts the City when a customer’s bill is flagged for high consumption and a customer can
make a request to have a service representative inspect their system to make necessary
repairs. In addition, City staff can review water usage bills to determine if “excessive water
2025 Urban Water Management Plan
City of Arcadia Page 9-11
use” occurred and can help customers individually determine the reason for the
“excessive water use.
The City will continue these programs to assess and manage distribution system real
losses.
9.1.3.6 WATER CONSERVATION PROGRAM COORDINATION AND
STAFFING SUPPORT
The City’s Management Analyst is responsible for all aspects of environmental issues
including water conservation measures for residents and business owners. The City’s
Management Analyst coordinates public water awareness materials, public outreach
events, seek grants, completing state mandated reports, speaks with residents/business
owners who contact the City for water conservation information, and participates in the
active dissemination of Upper Water efforts such as the High Efficiency Clothes Washer
Rebate Program. The City has staff whose primary function is water conservation. Duties
include outreach to various customer classes, response to customer inquiries,
complaints, and provide assistance to business customers in achieving water use
reduction. Staff will also work with field crews to enforce water conservation regulations.
As a member of Upper Water, the City can utilize Upper Water’s water conservation
coordinator to promote water conservation issues and programs within the City. The water
conservation coordinator does research on water management practices and advises
retail water purveyors on water conservation matters. Upper Water’s water conservation
coordinator is effective at informing the public on water awareness and is involved in
public information programs and school education programs.
The water conservation coordinator employed by Upper Water promotes water
conservation issues and programs. The position was created in 1992 as a full-time
2025 Urban Water Management Plan
City of Arcadia Page 9-12
position. The water conservation coordinator does research on water managements
practices and advises the Upper Water Board Members and its subagencies, including
the City, on water conservation matters. More information about Upper Water’s
conservation coordinator can be found in its 2025 Plan, which is incorporated by
reference.
9.1.3.7 OTHER DEMAND MANAGEMENT MEASURES
Rebate Programs
Upper Water, in partnership with MWD, implement region-wide rebate programs through
MWD’s SoCal Water$mart program. As a sub-agency of Upper Water, the City currently
offers rebates to qualifying residential customers for high-efficiency washing machines,
high-efficiency toilets, energy star dishwashers, weather-based irrigation controllers, rain
barrels and pool covers. The rebate application, along with a list of qualifying appliances,
are listed on MWD’s “Be Water Wise” website.
DEMAND MANAGEMENT MEASURES FOR WHOLESALE SUPPLIERS
CWC 10631.
(e) Provide a description of the supplier’s water demand management measures. This
description shall include all of the following:
(2) For an urban wholesale water supplier, as defined in Section 10608.12, a narrative
description of the items in clauses (ii), (iv), (vi), and (vii) of subparagraph (B) of paragraph
(1), and a narrative description of its distribution system asset management and wholesale
supplier assistance programs.
2025 Urban Water Management Plan
City of Arcadia Page 9-13
The City is not a wholesale agency and is not required by DWR to complete Section 9.2.
2025 Urban Water Management Plan
City of Arcadia Page 10-1
CHAPTER 10
PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION
LAY DESCRIPTION – CHAPTER 10
PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION
Chapter 10 (Plan Adoption, Submittal, and Implementation) of the City’s 2025 Plan
discusses and provides the following:
x The steps the City has performed to adopt and submit its 2025 Plan are detailed
x The steps the City has performed to adopt and submit its Water Shortage
Contingency Plan are detailed
x The City coordinated the preparation of its 2025 Plan with the Main San Gabriel
Basin Watermaster, Upper Water, City of Monrovia, City of Pasadena, City of
Sierra Madre, San Gabriel Valley Water Company, Golden State Water Company,
California American Water Company, and Sunny Slope Water Company. The City
notified these agencies at least sixty (60) days prior to the public hearing of the
preparation of the 2025 Plan and invited these agencies to participate in the
development of the 2025 Plan.
x The City provided a notice of the public hearing to the same agencies regarding
the time, date, and place of the public hearing.
x The City published a newspaper notification of the public hearing, once a week for
two successive weeks
x The City conducted a public hearing to discuss and adopt the City’s 2025 Plan and
City’s Water Shortage Contingency Plan.
x Within 30 days of adoption, the City submitted the 2025 Plan and Water Shortage
Contingency Plan to the California Department of Water Resources.
2025 Urban Water Management Plan
City of Arcadia Page 10-2
x Within 30 days of adoption, the City submitted all data tables associated with the
2025 Plan to the California Department of Water Resources.
x Within 30 days of adoption, the City submitted a copy of the 2025 Plan to the State
of California Library.
x Within 30 days of adoption, the City submitted a copy of the 2025 Plan (and Water
Shortage Contingency Plan) to the County of Los Angeles Registrar/Recorders
office and the City Clerk’s Office.
x Within 30 days after submittal of the 2025 Plan to the California Department of
Water Resources, the City made the 2025 Plan (including the Water Shortage
Contingency Plan) available at the City Clerk’s Office and on the City’s website.
x The steps the City will perform to amend the 2025 Plan and/or the Water Shortage
Contingency Plan, if necessary, are provided.
PLAN COMPLETION TIMELINE
The data provided in the City’s 2025 Plan and the Water Shortage Contingency Plan is
provided on a FY basis through June 30, 2025 (as discussed in Section 2.5).
NOTICE OF PLAN PREPARATION
CWC 10621.
(b) Every urban water supplier required to prepare a plan shall … at least 60 days prior to the
public hearing on the plan … notify any city or county within which the supplier provides
waters supplies that the urban water supplier will be reviewing the plan and considering
amendments or changes to the plan.
2025 Urban Water Management Plan
City of Arcadia Page 10-3
As discussed in Section 2.4.2., the City coordinated the preparation of the 2025 Plan with
the Main San Gabriel Basin Watermaster, Upper Water, City of Monrovia, City of
Pasadena, City of Sierra Madre, San Gabriel Valley Water Company, Golden State Water
Company, California American Water Company, and Sunny Slope Water Company. The
City notified these agencies, as well as to the cities and county within which the City
provides water supplies, at least sixty (60) days prior to the public hearing of the
preparation of the 2025 Plan and invited them to participate in the development of the
Plan. A copy of the notification letters sent to these agencies is provided in Appendix D.
NOTICE OF PUBLIC HEARING
CWC 10642.
…Prior to adopting either, the urban water supplier shall make both the plan and the water
shortage contingency plan available for public inspection and shall hold a public hearing or
hearings thereon. Prior to any of these hearings, notice of the time and place of the hearing shall
be published within the jurisdiction of the publicly owned water supplier pursuant to Section 6066
of the Government Code. The urban water supplier shall provide notice of the time and place of
a hearing to any city or county within which the supplier provides water supplies.
Government Code 6066.
Publication of notice pursuant to this section shall be once a week for two successive weeks.
Two publications in a newspaper published once a week or oftener, with at least five days
intervening between the respective publication dates not counting such publication dates, are
sufficient. The period of notice commences upon the first day of publication and terminates at the
end of the fourteenth day, including therein the first day.
The City provided a notice of the public hearing to the County of Los Angeles Registrar
Recorder, Main San Gabriel Basin Watermaster, Upper Water, City of Monrovia, City of
Pasadena, City of Sierra Madre, San Gabriel Valley Water Company, Golden State Water
Company, California American Water Company, and Sunny Slope Water Company. The
notice includes the time and place of the public hearing. Copies of the notice of the public
2025 Urban Water Management Plan
City of Arcadia Page 10-4
hearing are provided in Appendix D. Table 10-1 summarizes the agencies which were
provided notifications by the City.
The City encouraged the active involvement of the population within its service area prior
to and during the preparation of the Plan. Pursuant to Section 6066 of the Government
Code, the City published a notice of public hearing in the newspaper during the weeks of
June 1, 2026 and June 8, 2026. A notice of public hearing was also provided to the City
Clerk’s office and was posted throughout the City of Arcadia and on the City’s website. A
copy of the published notice is provided in Appendix D. To ensure the draft 2025 Plan
and the draft Water Shortage Contingency Plan were available for review, the City placed
a copy at the City Clerk’s Office located at City Hall, at the Public Works Services Center
located at 11800 Goldring Road, and made a copy available for review on its website at
www.ArcadiaCA.gov/UWMP.
PUBLIC HEARING AND ADOPTION
CWC 10642.
Each urban water supplier shall encourage the active involvement of diverse social, cultural, and
economic elements of the population within the service area prior to and during the preparation
of both the plan and the water shortage contingency plan. Prior to adopting either, the urban
water supplier shall make both the plan and the water shortage contingency plan available for
public inspection and shall hold a public hearing or hearings thereon…. After the hearing or
hearings, the plan or water shortage contingency plan shall be adopted as prepared or as
modified after the hearing or hearings.
Government Code Section 7291
…every local public agency… serving a substantial number of non- English-Speaking people,
shall employ a sufficient number of qualified bilingual persons in public contact positions or as
interpreters to assist those in such positions, to ensure provision of information and services in
the language of the non-English-speaking person.
2025 Urban Water Management Plan
City of Arcadia Page 10-5
Prior to adopting the draft 2025 Plan and draft the Water Shortage Contingency Plan, the
City held a public hearing on June 16, 2026 which included input from the community
regarding the City’s draft 2025 Plan and the draft Water Shortage Contingency Plan.
Following the public hearing, the City adopted both the draft 2025 Plan and the draft Water
Shortage Contingency Plan (included in Chapter 8). A copy of the resolution adopting
the 2025 Plan and the Water Shortage Contingency Plan is provided in Appendix O.
PLAN SUBMITTAL
CWC 10621.
(e) .Each urban water supplier shall update and submit its 2025 plan to the department by July
1, 2026…
CWC 10635.
(c) The urban water supplier shall provide that portion of its urban water management plan
prepared pursuant to this article to any city or county within which it provides water supplies
no later than 60 days after the submission of its urban water management plan.
CWC 10644.
(a) (1) An urban water supplier shall submit to the department, the California State Library, and
any city or county within which the supplier provides water supplies a copy of its plan no
later than 30 days after adoption.
The City’s submittal process for its 2025 Plan and the Water Shortage Contingency Plan
is discussed below.
2025 Urban Water Management Plan
City of Arcadia Page 10-6
SUBMITTING A UWMP AND WATER SHORTAGE
CONTINGENCY PLAN TO DWR
Within 30 days of adoption of the 2025 Plan by the City Council, the City submitted the
adopted 2025 Plan (including the Water Shortage Contingency Plan) to DWR. The 2025
Plan and Water Shortage Contingency Plan were submitted through DWR’s “Water Use
Efficiency (WUE) Data Portal” website.
DWR developed a checklist which was used by the City to assist DWR with its
determination that the City’s 2025 Plan has addressed the requirements of the California
Water Code. The City has completed the DWR checklist by indicating where the required
CWC elements can be found within the City’s 2025 Plan (See Appendix B).
ELECTRONIC DATA SUBMITTAL
CWC 10644.
(a)(2) The plan, or amendments to the plan, submitted to the department …shall be submitted
electronically and shall include any standardized forms, tables, or displays specified by the
department.
Within 30 days of adoption of the 2025 Plan, the City submitted all data tables associated
with the 2025 Plan through DWR’s “Water Use Efficiency Data Portal” website.
2025 Urban Water Management Plan
City of Arcadia Page 10-7
SUBMITTING A UWMP, INCLUDING WSCP, TO THE
CALIFORNIA STATE LIBRARY
Within 30 days of adoption of the 2025 Plan by the City Council, a copy (CD or hardcopy)
of the 2025 Plan was submitted to the State of California Library. A copy of the letter to
the State Library will be maintained in the City’s file. The 2025 Plan will be mailed to the
following address if sent by regular mail:
California State Library
Government Publications Section
Attention: Coordinator, Urban Water Management Plans
P.O. Box 942837
Sacramento, CA 94237-0001
The 2025 Plan will be mailed to the following address if sent by courier or overnight
carrier:
California State Library
Government Publications Section
Attention: Coordinator, Urban Water Management Plans
900 N Street
Sacramento, CA 95814
SUBMITTING A UWMP TO CITIES AND COUNTIES
Within 30 days of adoption of the 2025 Plan (including the Water Shortage Contingency
Plan) by the City Council, a copy of the 2025 Plan was submitted to the County of Los
Angeles Registrar / Recorders office and the City Clerk’s Office. A copy of the letter to the
County of Los Angeles will be maintained in the City’s file.
2025 Urban Water Management Plan
City of Arcadia Page 10-8
PUBLIC AVAILABILITY
CWC 10645.
(a) Not later than 30 days after filing a copy of its plan with the department, the urban water
supplier and the department shall make the plan available for public review during normal
business hours.
(b) Not later than 30 days after filing a copy of its water shortage contingency plan with the
department, the urban water supplier and the department shall make the plan available for
public review during normal business hours.
Within 30 days after submittal of the 2025 Plan to DWR, the City made the 2025 Plan
(including the Water Shortage Contingency Plan) available at the City Clerk’s Office
located at City Hall during normal business hours and on the City’s website.
NOTIFICATION TO PUBLIC UTILITIES COMMISSION
CWC 10621.
(c) An urban water supplier regulated by the Public Utilities Commission shall include its most
recent plan and water shortage contingency plan as part of the supplier’s general rate case
filings.
The City is not regulated by the California Public Utilities Commission.
2025 Urban Water Management Plan
City of Arcadia Page 10-9
PLAN IMPLEMENTATION
CWC 10643.
An urban water supplier shall implement its plan adopted pursuant to this chapter in accordance
with the schedule set forth in its plan.
The City will implement any schedules set forth in the adopted 2025 Plan.
AMENDING AN ADOPTED UWMP OR WATER SHORTAGE CONTINGENCY
PLAN
CWC 10621.
(d) The amendments to, or changes in, the plan shall be adopted and filed in the manner set
forth in Article 3 (commencing with Section 10640).
CWC 10644.
(a)(1) Copies of amendments or changes to the plans shall be submitted to the department, the
California State Library, and any city or county within which the supplier provides water
supplies within 30 days after adoption.
The City’s amendment process for its 2025 Plan is discussed below.
AMENDING A UWMP OR WSCP
If the City amends the adopted 2025 Plan, the City will conduct a similar notification and
public hearing process for the amended 2025 Plan as discussed in Sections 10.2, 10.3,
and 10.4. The amended Plan will undergo adoption by the City’s governing board. Within
2025 Urban Water Management Plan
City of Arcadia Page 10-10
30 days of adoption, the amended Plan will then be submitted to DWR, the State of
California Library, the County of Los Angeles Registrar / Recorders office, and the City
Clerk’s Office.
AMENDING A WATER SHORTAGE CONTINGENCY PLAN
CWC 10644.
(a) If an urban water supplier revises its water shortage contingency plan, the supplier shall
submit to the department a copy of its water shortage contingency plan prepared…no later
than 30 days after adoption, in accordance with protocols for submission and using electronic
reporting tools developed by the department.
If the City amends the adopted 2025 Plan (including the Water Shortage Contingency
Plan), the amended Plan (and Water Shortage Contingency Plan) will undergo adoption
by the City’s governing board. Within 30 days of adoption, the amended Plan (and Water
Shortage Contingency Plan) will then be submitted to DWR, the State of California
Library, the County of Los Angeles Registrar / Recorders office, and the City Clerk’s
Office.
CALIFORNIA DEPARTMENT OF WATER RESOURCES REVIEW OF
SUBMITTED PLANS
As discussed in Section 1.5, DWR will review the 2025 Plans to ensure that they address
the California Water Code requirements. Following DWR’s review, water suppliers will
be notified of the results of the review via a formal review letter. These review letters
will also be available to the public on DWR’s WUEdata portal. In cases where DWR
finds that a Plan does not properly address item(s) in the Water Code, DWR will reach
out to the water supplier to discuss needed corrections and correction procedures.
2025 Urban Water Management Plan
City of Arcadia Page 10-11
SUBMITTAL TABLES
The applicable standardized Submittal Tables referenced within Chapter 10 are provided
below.
SUBMITTAL TABLE 10-1: NOTIFICATION TO CITIES AND
COUNTIES
Table 10-1 Notification to Cities and Counties
City Name 60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
Arcadia Yes Yes
Monrovia Yes Yes
Sierra Madre Yes Yes
Pasadena Yes Yes
County Name
Drop Down List
60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
Los Angeles County Yes Yes
Submittal Table 10-1 Retail: Notification to Cities and
Counties
Water Code Section 10621(b) and 10642
Add additional rows as needed
Add additional rows as needed
NOTES:
Service Layer Credits: Sources: Esri, HERE,
Garmin, USGS, Intermap, INCREMENT P,
NRCan, Esri Japan, METI, Esri China (Hong
Kong), Esri Korea, Esri (Thailand), NGCC, (c)
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CITY OF ARCADIA
WATER SERVICE AREA
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FIGURE 1
Service Layer Credits: Sources: Esri, HERE,
Garmin, USGS, Intermap, INCREMENT P,
NRCan, Esri Japan, METI, Esri China (Hong
Kong), Esri Korea, Esri (Thailand), NGCC, (c)
OpenStreetMap contributors, and the GIS User
Community
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Arcadia
El Monte
Irwindale
Monrovia
Pasadena
Sierra Madre
Temple City
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CITY OF ARCADIA
WATER SERVICE AREA
AND CITY BOUNDARIES
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FIGURE 2
City of Arcadia
City Boundary
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UV57
UV71
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Document Path: J:\jn2741\Arcadia_SGBasin_Location.mxd
CITY OF ARCADIA
MAIN SAN GABRIEL BASIN LOCATION Ü01.53
Miles
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3
Basin Boundary
Water System Boundary
Santa Anita
Subarea
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Subarea
Pasadena
Subarea
UV710
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UV110
UV134
§¨¦210
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Document Path: J:\jn2741\Arcadia_RaymondBasin_Location.mxd
CITY OF ARCADIA
RAYMOND BASIN LOCATION Ü012
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Basin Boundary
Water System Boundary
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX A
DWR STANDARDIZED TABLES
CA1910003 City of Arcadia 15,564 13,294
15,564 13,294Total
Public Water System
Number
Public Water System
Name
Number of Municipal
Connections 2025
Submittal Table 2-1 Retail: Public Water Systems
Add additional rows as needed
NOTES: Units are in acre-feet (AF)
Volume of Water
Supplied 2025 (AF)
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported
in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table
2-3.
Select
One
Name of Regional Alliance or
RUWMP (Drop Down List)
NOTES:
Submittal Table 2-2: Plan Identification
Type of Plan
Individual UWMP
If Water Supplier is also a member of a SB X7-7
Regional Alliance, select name from the drop-
down.
Regional Urban Water Management Plan (RUWMP)
If Supplier selected RUWMP, select name from
the drop-down.
Supplier is a wholesale supplier
Supplier is a retail supplier
UWMP Tables are in calendar years
UWMP Tables are in fiscal years
Unit AF
Submittal Table 2-3: Supplier Identification
Type of Supplier (select one or both)
Fiscal or Calendar Year (select one)
If using fiscal years provide month and date that the fiscal
year begins (mm/dd)
Units of measure used in UWMP
(Select from the drop down list).
07/01
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent
throughout the UWMP as reported in Submittal Table 2-3.
NOTES:
cal o
Submittal Table 2-4 Retail: Water Supplier Information Exchange
Water Code Section 10631(h)
The retail Supplier has informed the following wholesale supplier(s) of
projected water use.
Wholesale Water Supplier Name
Add additional rows as needed
Upper San Gabriel Valley Municipal Water District
NOTES:
2025 2030 2035 2040 2045 2050(opt)
54,700 60,303 65,903 66,233 66,564 66,897
Submittal Table 3-1 Retail: Population - Current and Projected
Water Code Section 10631(a)
Population
Served
NOTES:
Use Type
Drop down list
May select each use multiple times
These are the only use types that will be
recognized by the WUEdata online submittal tool
Potable or Non-
Potable
(OPTIONAL)
Drop down list
Volume (AF)
Single Family Potable 7,010
Multi-Family Potable 1,863
Commercial Potable 2,284
Institutional/Governmental Potable 937
Other (optional) Fire Hydrants Potable 1
Landscape Potable 135
Distribution System Water Loss Potable 1,064
13294
0
13,294Total
Submittal Table 4-1 Retail: Total Uses for Potable and Non-Potable Water — Actual
Water Code Section 10631(d)(1)
NOTES:
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in
Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
2025 Actual Water Use
Add additional rows as needed
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
Use Type
Drop down list
May select each use multiple times
These are the only Use Types that will be
recognized by the WUEdata online submittal tool
Potable or Non-Potable
(OPTIONAL)
Drop down list
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF)2050 opt (AF)
Single Family Potable 7,790 8,513 8,556 8,599 8,642
Multi-Family Potable 2,070 2,262 2,273 2,285 2,296
Commercial Potable 2,538 2,774 2,788 2,802 2,816
Institutional/Governmental Potable 1,041 1,138 1,144 1,150 1,155
Other (optional) Fire Hydrants Potable 1 1 1 1 1
Landscape Potable 151 164 165 166 167
Distribution System Water Loss Potable 1,182 1,292 1,298 1,305 1,311
14,773 16,144 16,225 16,308 16,388
0000 0
14,773 16,144 16,225 16,308 16,388
Add additional rows as needed.
Submittal Table 4-2 Retail: Total Uses for Potable, and Non-Potable Water — Projected
Water Code Section 10631(d)(1)
Projected Water Use
(Report To the Extent that Records are Available)
Additional Description
(as needed)
NOTES:
Total
DWR NOTES: Units of measure (AF, CCF, MG ) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of
measure selected in Submittal Table 2-3.
Subtotal Non-Potable
Subtotal Potable
Are Future Water Savings Included in Projections?
Drop down list (y/n) Yes
If "Yes" to above, state the section or page number, in the cell to the right,
where citations of the codes, ordinances, or otherwise are utilized in demand
projections are found.
Optional Suppliers may complete Optional Submittal Table 4-4 R to quantify
the expected savings.
Section 4.2.5
and Chapter
8
Are Lower Income Residential Demands Included In Projections?
Drop down list (y/n)Yes
Optional If the method for accounting Lower Income Residential Demands has
been included, provide page number where this accounting can be found.
Submittal Table 4-3 Retail: Inclusion in Water Use Projections
Water Code Section 10631 (a), 10631 (d)(4)(A), and 10631 (d)(4)(B)
NOTES:
DWR NOTES: Additional guidance is provided in Appendix K.
Public Water System ID #
Reported in Table 2-1 R Reporting Period
Submitted to DWR Water
Loss Audit Program
(yes/no)
2020 No
2021 No
2022 Yes
2023 No
2024 No
Submittal Table 4-5 Retail: Water Loss Audit Reporting
Water Code Section 10631(d)(3)(A)
CA1910003
DWR NOTES: Suppliers will provide a link to the WUEdata submittals of their
Water Loss Audit Reports.
NOTES: The City has also prepared Water Loss Audits representing Calendar
Year 2020, Calendar Year 2021, and Fiscal Year 2024-25 and w ill be submitting
these audits to DWR.
Report submittal status for all five years for each Public Water System as
available.
Add rows as needed
2028 Real Water Loss
Standard per Unit per
day
Units for Real
Water Loss
Drop down list
Number of Units
(Connections or
Miles corresponding
with units selected)
Volume of Total Real
Loss
(from AWWA Water
Loss Audit)
(AF)
2028 Apparent
Water Loss
Standard per Unit
per Day
Units for
Apparent Water
Loss
Number of
Connections
Volume of Total
Apparent Loss
(from AWWA Water
Loss Audit)
(AF)
CA1910003 Yes 19.0
Gallons per
Service
Connection per
Day (GPSCD)
14958 792.144 47.3 44.4
Gallons per
Service
Connection per
Day (GPSCD)
14958 162.426 9.7
Gallons per
Service
Connection per
Day (GPSCD)
Gallons per
Service
Connection per
Day (GPSCD)
Submittal Table 4-6 Retail: Progress Towards 2028 Water Loss Standard
Water Code Section 10631(d)(3)(C)
NOTES: Information used to complete the table above was based on the Water Loss Audit from FY 2022-23. The City has also prepared Water Loss Audits representing Calendar Year 2020, Calendar Year 2021, and Fiscal Year 2024-25 and will be
submitting these audits to DWR.
Apparent Water Loss
Did the Water Board Calculate
a Water Loss Standard for this
Public Water System? (y/n)
If no, Supplier will not
complete this row.
Real Water Loss
Water Board's Calculated Water Loss Standards
DWR NOTES: Units of measure (AF, CCF, MG) for Water Loss MUST remain consistent with units reported in Submittal Table 2-3. The units reported in Submittal Table 2-3 are used in this table's calculations.
Public Water
System ID #
Reported in
Submittal Table 2-
1 R
Add additional rows as needed.
Most Recent AWWA Water Loss Audit
Real Water
Loss Per Unit
per Day
Most Recent AWWA Water Loss Audit
Apparent Water
Loss Per Unit per
Day
State Water Board Standard State Water Board Standard
Actual 2025 GPCD
(From SB X7-7
Compliance Form)
Did Supplier meet
the 2020 Target in
2025?
No Individual
Target 238 230 Yes NA
Submittal Table 5-1 Retail: SB X7-7 2020 Target Progress
Water Code Section 10608.40
NOTES:
Did Supplier
Achieve Targeted
Reduction for
2020?
Actual 2020
GPCD2020 Target
Regional
Alliance Target
or Individual
Target?
Drop down list
DWR NOTES:
Suppliers calculating a 2025 GPCD will need to complete and submit SB X 7-7 Compliance Tables to verify the use of SB X7-7
Methodologies.
Suppliers that were part of a merger or consolidation since 2020 see Chapter 5 and Appendix P for guidance.
Check the box if the Supplier was not an Urban Water Supplier during or before the 2020 UWMP reporting cycle.
Proceed to the next table.
Only for suppliers that did not meet
the Target in 2020
See DWR NOTES below. Was Supplier part of
a merger or
consolidation since
2020?
Groundwater Type
Drop Down List
May use each category
multiple times
Potable or
Non-Potable
(OPTIONAL)
Drop down list
Location or Basin Name 2021 (AF) 2022 (AF) 2023 (AF) 2024 (AF)2025 (AF)
Alluvial Basin Potable East Raymond Basin 2216 2179 1734 2060 2167
Alluvial Basin Potable West Raymond Basin 678 621 641 286 772
Alluvial Basin Potable Main Basin 12116 11480 9245 9528 10355
15,010 14,280 11,620 11,874 13,294
Add additional rows as needed
Submittal Table 6-1 Retail: Groundwater Volume Pumped
Water Code Section 10631(4) and 10631(4)(c)
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table
identifies the unit of measure selected in Submittal Table 2-3.
NOTES
Total
Check the box if the Supplier does not pump groundwater.
Proceed to the next table.
Check the box if all or part of the groundwater described below is desalinated. (OPTIONAL)
Name of Wastewater
Collection Agency
Wastewater
Volume
Metered or
Estimated?
OPTIONAL
Drop Down List
Volume of
Wastewater Collected
from UWMP Service
Area 2025 (AF)
Name of Wastewater
Treatment Plant (WWTP) and
Place ID Number
Drop down list
Is WWTP
Located Within
UWMP Area?
Drop Down List
LACSD Estimated 123
Whittier Narrows Water
Reclamation Plant, Place ID
235826
No
LACSD Estimated 821
San Jose Creek Water
Reclamation Plant, Place ID
260156
No
LACSD Estimated 3,283
A.K. Warren Water Resource
Facility, Place ID 234156 No
4,227
Check the box if there is no wastewater collection system.
Proceed to the next table.
NOTES:
Submittal Table 6-2 Retail: Wastewater Collected Within Service Area
Water Code Section 10633(a)
Percentage of 2025 service area population served by wastewater collection system
(OPTIONAL)
Percentage of 2025 service area served by wastewater collection system (OPTIONAL)
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in
Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
Additional Guidance : See Appendix M, Section M.21 for detailed guidance on this table.
Wastewater Collection Recipient of Collected Wastewater
Total Wastewater Received from UWMP
Service Area in 2025:
Add additional rows as needed
Treatment
Level
Drop down list
Volume
(AF)
Treatment
Level
Drop down list
Volume
(AF)
Treatment
Level
Drop down list
Volume
(AF)
Treatment
Level
Drop down list
Volume
(AF)
Treatment
Level
Drop down list
Volume
(AF)
Name of other
entity
0- 0 0 0 0 0
Submittal Table 6-3 Retail: Wastewater Treatment and Outcomes Within UWMP Service Area
Water Code Section 10633(b)
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
IPR: Indirect Potable Reuse would have the treatment level of its end use requirement in the Level of Treatment drop-down.
Additional Guidance: See Appendix M, Section M.21 for detailed guidance on this table.
Water Recycled Outside
of UWMP Service Area
(enter data as applicable)
Effluent Discharge that is
not a Permitted Recycled
Water Use
(enter data as applicable)
Required Discharge for
Instream Flow
(enter data as applicable)
Delivered to Another Entity for Additional
Treatment
(enter data as applicable)
Add additional rows as needed
2025 Outcomes of Treated Wastewater
Check the box if no wastewater is treated or disposed of within the UWMP service area.
Proceed to the next table.
Does This
Plant Treat
Wastewater
Generated
Outside the
UWMP Service
Area?
(OPTIONAL)
Drop down list
Wastewater
Treatment Plant
Name and Place ID
Number
Drop down list
Total 2025
Volume of
Water
Treated
(AF)
NOTES:
Total
2025 Volume
of Wastewater
Received from
UWMP Service
Area
(As Reported
in Submittal
Table 6-2 R)
(AF)
Water Recycled Within
UWMP Service Area
(enter data as applicable)
Volume Narrative page number
(OPTIONAL)
0000000
0000000
0000000 0
Check box if recycled water is not used and is not planned for use within the service area of the supplier. The supplier will only complete the column on "Potential
Recycled Water Use" and submit an accompanying narrative on the feasibility of that potential recycled water use.
Submittal Table 6-4 Retail: Recycled Water Direct Beneficial Uses Within Service Area
Water Code Section 10633 (c),(d),(e)
Potential Recycled Water Use
Name(s) of Facility/ies Producing (Treating) the Recycled Water (OPTIONAL) :
Name of Supplier Operating the Recycled Water Distribution System (OPTIONAL) :
Volume of Supplemental Water Added in 2025 (OPTIONAL) :
Source of 2025 Supplemental Water (OPTIONAL) :
Total
Use Type
Drop down list
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop down list
Additional Information
(as needed)
Add additional rows as needed
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal
Table 2-3.
Additional Guidance: See Appendix M, Section M.21 for detailed guidance on this table.
Potential recycled water use: a description of the feasibility of these uses must be included in the narrative.
Multiple Producers: If you have multiple recycled water producers, submit a separate table for each.
NOTES:
2050 (AF)2025 (AF)2030 (AF)2035
(AF)
2040
(AF)
2045
(AF)
Subtotal Potable
Subtotal Non-Potable
2020 Projection
for 2025 (AF)
2025 Actual
Use (AF)
00
Submittal Table 6-5 Retail: 2020 UWMP Recycled Water Use Projection
Compared to 2025 Actual
Water Code Section 10633(e)
Check the box if recycled water was not used in 2025 nor previously
projected for use in 2020.
Proceed to the next table.
Add additional rows as needed
NOTES:
Total
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported
in Submittal Table 2-3. This table identifies the unit of measure reported in Submittal Table
2-3
Additional Guidance: See Appendix M, Section M.21 for detailed guidance on this table.
Use Type
Drop Down list
Section 6.2.5
Name of Action Description
Expected Increase in Recycled
Water Use (AF)
0
0
Total (AF)
DWR NOTES:
Units of measure (AF, CCF, MG) MUST remain consistent with units reported in Submittal Table 2-3. This table identifies the unit of measure
selected in Submittal Table 2-3.
The unit conversion to Acre Feet addresses the Water Code's requirement that this value be provided in acre-feet.
NOTES:
Submittal Table 6-6 Retail: Methods to Encourage Future Recycled Water Use
Water Code Section 10633(f)
Check the box if the Supplier does not plan to expand recycled water use in the future. Supplier will not complete
the table below but will provide narrative explanation.
Provide page location of narrative in the UWMP
Add additional rows as needed
Unit Conversion to AF
Planned Implementation
Year
Section 6.2.10
Drop Down
List
(yes/no)
If Yes, Supplier Name
New Groundwater
Well (Goldring)Yes City of Sierra Madre New Main Basin well Potable 2027 All Year Types 1,600
Planned for Use
in Year Type
Drop Down List
NOTES:
Submittal Table 6-7 Retail: Expected Future Water Supply Projects or Programs
Water Code Section 10631(f)
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of measure
reported in Submittal Table 2-3.
Check the box if some or all of the supplier's future water supply projects or programs are not compatible with this table and are
described in a narrative format.
Check the box if there are no expected future water supply projects or programs that provide a quantifiable increase to the agency's
water supply.
Proceed to the next table.
Planned
Implementation
Year
Add additional rows as needed
Joint Project with other
suppliers?Expected
Increase in
Water Supply
to Supplier
(This may be
a range) (AF)
Provide page location of narrative in the UWMP
Name of Future
Projects or Programs
Additional Description
(as needed)
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
Water Supply
Drop down list
May use each category multiple
times. These are the only water
supply categories that will be
recognized by the WUEdata online
submittal tool
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
Actual Volume
(AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Groundwater (not desalinated) East Raymond Basin Potable 2,167
Groundwater (not desalinated) West Raymond Basin Potable 772
Groundwater (not desalinated) Main Basin Potable 10,355
Purchased or Imported Water MWD Potable 0
13,294 0
00
13,294 0
Submittal Table 6-8 Retail: Water Supplies — Actual
Water Code Section 10631(b)
2025
NOTES:
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies
the unit of measure selected in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
Add additional rows as needed
Total
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
Water Supply
Reasonably
Available
Volume
(AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume
(AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total
Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Groundwater (not
desalinated)
East
Raymond
Basin
Potable 2,300 2,300 2,300 2,300 2,300
Groundwater (not
desalinated)
West
Raymond
Basin
Potable 800 800 800 800 800
Groundwater (not Main Basin Potable 11,673 13,044 13,125 13,208 13,288
Purchased or Imported
Water MWD Potable 0 0 0 0 0
14,773 0 16,144 0 16,225 0 16,308 0 16,388 0
0000000000
14,773 0 16,144 0 16,225 0 16,308 0 16,388 0
Submittal Table 6-9 Retail: Water Supplies — Projected
Water Code Section 10631 (b)
Projected Water Supply (Report to the Extent Practicable)
Drop down list
May use each category
multiple times. These are the
only water supply categories
that will be recognized by the
WUEdata online submittal
tool
Additional
Detail on
Water
Supply
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
2050 (opt)
Add additional rows as needed
Total
NOTES:
2030 2035 2040 2045
Subtotal Non-Potable
Subtotal Potable
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
Water Delivery Product
drop down list
(If delivering more than one type of product recommend
using Table O-1C)
Retail Potable
Deliveries
Start Date of Reporting Period 7/1/2024
End Date of Reporting Period 6/30/2025
Is upstream embedded energy in the values reported?No
Units of Measure for Water AF Total Utility
See DWR NOTES Hydropower Net Utility
13,294 13,294
10,785,416 10,785,416
2,490 - 2,490
Quantity of Self-Generated Renewable Energy
0kWh
Data Quality (Estimate, Metered Data, Combination of Estimates and Metered Data)
Combination of Estimates and Metered Data
Data Quality Narrative:
Narrative:
Optional Submittal Table O-1B: Recommended Energy Reporting - SINGLE DELIVERY PRODUCT - TOTAL UTILITY
APPROACH
The total energy consumed was identified based on Southern California Edison (SCE) billing records. Although the total energy consumed includes
electricity usage for general administration (which is not an identified water management process), general administration energy use is considered to be
negligible compared to overall water system use and has not been netted out.
Only for Water Delivery Products Under the Urban Water Supplier's Operational
Control
Sum of All Water
Management Processes Non-Consequential Hydropower
DWR NOTES:
Total Utility:The volume of water entered in the “Total Utility” column should equal the volume of water entering the distribution system (excluding
recycled water); in most cases, this is the total volume calculated in UWMP Table 4-1: 2025 Actual Total Uses for Potable and N on-Potable Water. Note if
recycled water is included in your Submittal Table 4-1, you must exclude it from your volume in this table.
NOTES:
The total energy consumption includes energy associated with operating groundwater production wells and booster pumps to deliver water in the
distribution system. Energy consumption is associated with operating groundwater water treatment. Energy consumption is also associated with plant
lighting and air conditioning, and operating the Supervisory Control and Data Acquisition (SCADA) system and chlorination injection pumps.
Volume of Water Entering Process
Energy Consumed (kWh)
Energy Intensity (kWh/vol. converted to MG)
% of Average Supply
Average Year 2020 100%
Single-Dry Year 2018 103.5%
Consecutive Dry Years 1st Year 2012 117.7%
Consecutive Dry Years 2nd Year 2013 123.5%
Consecutive Dry Years 3rd Year 2014 125.2%
Consecutive Dry Years 4th Year 2015 110.0%
Consecutive Dry Years 5th Year 2016 88.8%
13935
14416
Year Type
Base Year
If not using a
calendar year, type
in the last year of
the fiscal, water
year, or range of
years, for example,
water year 2024-
2025, use 2025
Optional Submittal Table 7-1 Retail: Basis of Water Year Data (Reliability Assessment)
Available Supplies if
Year Type Repeats
Check the box if quantification of available supplies
is not compatible with this table and is provided
elsewhere in the UWMP.
Location: [insert location from UWMP]
Volume Available (AF)
Quantification of available supplies is provided in this
table as either volume only, percent only, or both.
16399
17211
NOTES:
17452
15326
12369
DWR NOTES: Supplier may use multiple versions of Submittal Table 7-1 R if different water sources have different base
years and the supplier chooses to report the base years for each water source separately. If a Supplier uses multiple
versions of Submittal Table 7-1 R, in the "Note" section of each submittal table, state that multiple versions of Submittal
Table 7-1 R are being used and identify the particular water source that is being reported in each submittal table.
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This
table reports the units of measure reported in Submittal Table 2-3.
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF)2050 (AF)
Supply totals
(autofill from Submittal
Table 6-9 R)
14,773 16,144 16,225 16,308 16,388
Use totals
(autofill from Submittal
Table 4-2 R)
14,773 16,144 16,225 16,308 16,388
Surplus/(shortfall)0 0 0 0 0
WSCP - supply
augmentation benefit
WSCP - use reduction
savings benefit
Revised Surplus/(shortfall)
OPTIONAL Planned WSCP Actions
Submittal Table 7-2 Retail: Normal Year Supply and Use Comparison
Water Code Section 10635 (a)
NOTES:
DWR NOTES : Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported
in Submittal Table 2-3.
Supply totals 15,283 16,701 16,785 16,871 16,954
Use totals 15,283 16,701 16,785 16,871 16,954
Surplus/(shortfall)0 0 0 0 0
WSCP - supply
augmentation benefit
WSCP - use reduction
savings benefit
Revised
Surplus/(shortfall)
2050 (AF)
DWR NOTES : Units of measure (AF, CCF, MG) must remain consistent throughout the
UWMP as reported in Submittal Table 2-3.
NOTES
Submittal Table 7-3 Retail: Single Dry Year Supply and Use Comparison
Water Code Section 10635(a)
OPTIONAL Planned WSCP Actions
2030 (AF)2035 (AF)2040 (AF)2045 (AF)
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF)2050 (AF)
Supply totals 17,385 18,998 19,094 19,191 19,286
Use totals 17,385 18,998 19,094 19,191 19,286
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 18,246 19,939 20,039 20,142 20,241
Use totals 18,246 19,939 20,039 20,142 20,241
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 18,501 20,218 20,320 20,424 20,524
Use totals 18,501 20,218 20,320 20,424 20,524
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 16,248 17,755 17,844 17,936 18,024
Use totals 16,248 17,755 17,844 17,936 18,024
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Supply totals 13,113 14,330 14,402 14,475 14,546
Use totals 13,113 14,330 14,402 14,475 14,546
Surplus/(shortfall) 0 0 0 0 0
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Submittal Table 7-4 Retail: Multiple Dry Years Supply and Use Comparison
Water Code Section 10635(a)
OPTIONAL Planned WSCP Actions
Third year
Fifth year
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table
2-3.
OPTIONAL Planned WSCP Actions
OPTIONAL Planned WSCP Actions
OPTIONAL Planned WSCP ActionsFourth year
NOTES:
First year
OPTIONAL WSCP Actions Second year
2026 Total
Total Water Use (AF)15,993
Total Supplies (AF)16,399
Surplus/Shortfall w/o WSCP Action 406
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)
Revised Surplus/(shortfall)
2027 Total
Total Water Use (AF)17,150
Total Supplies (AF)17,211
Surplus/Shortfall w/o WSCP Action 61
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)
Revised Surplus/(shortfall)
2028 Total
Total Water Use (AF)17,760
Total Supplies (AF)17,452
Surplus/Shortfall w/o WSCP Action (308)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)308
Revised Surplus/(shortfall) 0
2029 Total
Total Water Use (AF)15,922
Total Supplies (AF)15,326
Surplus/Shortfall w/o WSCP Action (596)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)596
Revised Surplus/(shortfall) 0
2030 Total
Total Water Use (AF)13,113
Total Supplies (AF)12,369
Surplus/Shortfall w/o WSCP Action (744)
WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF)744
Revised Surplus/(shortfall) 0
NOTES:
DWR NOTES: Units of measure (AF, CCF, MG) must remain
consistent throughout the UWMP as reported in Submittal Table
2-3.
Submittal Table 7-5 Retail: Five-Year Drought Risk
Assessment
Water Code Section 10635(b)(3)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
OPTIONAL Planned WSCP Actions (use reduction and supply
augmentation)
Standard
Shortage
Levels
Percent
Shortage Range
Suppliers
Shortage
Levels
Percent
Shortage
Range
1 Up to 10% 1, 2 Up to 10%
2 Up to 20% 3, 4 Up to 20%
3 Up to 30% 5, 6 Up to 30%
4 Up to 40% 7 Up to 40%
5 Up to 50% 8 Up to 50%
6 >50% 8 50%
Submittal Table 8-1: Cross-reference for Standard vs
Supplier Shortage Levels
Water Code Section 10632(a)(3)(B)
Check the box if the Supplier uses the
Standard six levels of water shortage.
Proceed to the next table.
NOTES:
Yes
Volume or
Percentage
Drop down
Shortage Gap
Reduction Value
(May be a range)
(AF)
1 Transfers Volume 0 Not applicable (see Notes)
2 Transfers Volume 0 Not applicable (see Notes)
3 Transfers Volume 0 Not applicable (see Notes)
4 Transfers Volume 0 Not applicable (see Notes)
5 Transfers Volume 0 Not applicable (see Notes)
6 Transfers Volume 0 Not applicable (see Notes)
Submittal Table 8-2 Retail: Supply Augmentation and Other Actions
Water Code Section 10632(a)(4)(A),(C) and (E)
Add additional rows as needed
NOTES: The City will consider increased production from the Main Basin using existing facilities to address increased demands.
As noted on Table 8-3, the City plans to implement demand reduction measures in the event water supplies from existing
sources are not sufficient to meet anticipated demands.
Is the Supplier completing this table using the standard six levels? (yes/no)
How much is this going to reduce the
shortage gap?
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
Shortage
Level
Supply Augmentation Methods and
Other Actions by Water Supplier
Drop down list
These are the only categories that will
be accepted by the WUEdata online
submittal tool
Additional Explanation or Reference
(OPTIONAL)
Yes
Volume or
Percentage
Drop down
Shortage Gap
Reduction Value
(May be a range)
(AF)
1 Landscape - Restrict or prohibit
runoff from landscape irrigation Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Other - Require automatic shut of
hoses Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Landscape - Limit landscape
irrigation to specific days Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Pursuant to Resolution No. 7430 adopted by City
Council in May 2022, no lawn, landscape, or
other turf areas shall be watered or irrigated
more than two (2) days per week (on Tuesday
and Saturday).
Yes
1 Landscape - Limit landscape
irrigation to specific times Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
No lawn, landscape, or other turf areas shall be
watered or irrigated between the hours of 9:00
a.m. and 6:00 p.m. Pacific time.
Yes
1 Landscape - Prohibit certain types
of landscape irrigation Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Pursuant to Resolution No. 7430 adopted by City
Council in May 2022, an owner of property used
primarily for commercial, industrial, or
institutional purposes may not irrigate non-
functional turf areas.
Yes
1 Landscape - Other landscape
restriction or prohibition Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
No irrigation during and within 48 hrs of
measurable rainfall Yes
1 CII - Lodging establishment must
offer opt out of linen service Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 CII - Restaurants may only serve
water upon request Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1
Water Features - Restrict water use
for decorative water features, such
as fountains
Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1
Other - Customers must repair
leaks, breaks, and malfunctions in a
timely manner
Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
1 Other - Prohibit use of potable
water for washing hard surfaces Volume
Collective reduction
from all Shortage
Level 1 actions is up
to 1,721 AF
Yes
2Other Volume
Collective reduction
from all Shortage
Level 2 actions is up
to 3,442 AF
All actions under Shortage Level 1 Yes
3Other Volume
Collective reduction
from all Shortage
Level 3 actions is up
to 5,163 AF
All actions under Shortage Level 2 Yes
4Other Volume
Collective reduction
from all Shortage
Level 4 actions is up
to 6,884 AF
All actions under Shortage Level 3 Yes
5Other Volume
Collective reduction
from all Shortage
Level 5 actions is up
to 8,605 AF
All actions under Shortage Level 4 Yes
6Other Volume
Collective reduction
from all Shortage
Level 6 actions is
greater than 8,605
AF
All actions under Shortage Level 5 Yes
Is the Supplier completing this table using the standard six levels? (yes/no)
Submittal Table 8-3 Retail: Demand Reduction Actions
Water Code Section 10632(a)(4)(B),(D), and (E)
Add additional rows as needed
How much is this going to reduce the
shortage gap?
Shortage
Level
Demand Reduction Actions
Drop down list
These are the only categories that will
be accepted by the WUEdata online
submittal tool. Select those that apply.
Additional Explanation or Reference
(OPTIONAL)
NOTES:
Penalty, Charge,
or Other
Enforcement?
For Retail Suppliers
Only
Drop Down List
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
City Name 60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
Arcadia Yes Yes
Monrovia Yes Yes
Sierra Madre Yes Yes
Pasadena Yes Yes
County Name
Drop Down List
60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
Los Angeles County Yes Yes
Submittal Table 10-1 Retail: Notification to Cities and
Counties
Water Code Section 10621(b) and 10642
Add additional rows as needed
Add additional rows as needed
NOTES:
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX B
COMPLETED PLAN CHECKLIST
Retail
(x = required)
Wholesale
(x = required
)
Order 2025 Guidebook Location Water Code Section Summary as Applies to UWMP Subject
Relevant
Submittal Table 2025 UWMP Location
x x 1 Chapter 1 10615
A plan shall describe and evaluate sources of supply, reasonable and practical efficient uses, reclamation
and demand management activities.Introduction and overview n/a Chapter 1 Lay Description
x x 1 Chapter 1 10630.5
Each plan shall include a simple description of the Supplier’s plan including water availability, future
requirements, a strategy for meeting needs, and other pertinent information. Additionally, a Supplier may
also choose to include a simple description at the beginning of each chapter.
Plan preparation n/a Beginning of each Chapter
x x 2.1 Section 2.1 10620(b) Every person that becomes a Supplier shall adopt UWMP within one year after it has become a Supplier. Plan preparation n/a Section 2.1
x n/a 2.5 Section 2.5 10644
Supplier shall report the Public Water Systems number, volume of delivered water, and number of
connections that are included in this UWMP.Plan preparation 2-1 Sections 2.1 and 2.5
x x 2.5 Section 2.5 10644
Supplier shall report if this UWMP is an individual UWMP and whether the Supplier belongs to a regional
UWMP or regional alliance.Plan preparation 2-2 Sections 2.2 and 2.5
x x 2.5 Section 2.5 10644
Supplier shall report whether the data is in fiscal or calendar years and the units of measure used for
reporting water volumes.Plan preparation 2-3 Sections 2.3 and 2.5
x x 2.4 Section 2.4 10642
Provide supporting documentation that the Supplier has encouraged active involvement of diverse social,
cultural, and economic elements of the population within the service area prior to and during the
preparation of the plan and contingency plan.
Plan preparation n/a Section 2.4
x x 2.4 Section 2.4.2 10620(d)(3)
Coordinate the preparation of its plan with other appropriate agencies in the area, including other
Suppliers that share a common source, water management agencies, and relevant public agencies, to the
extent practicable.
Plan preparation n/a Section 2.4.2
x n/a 2.4 Section 2.4.1 10631(h)
Retail Suppliers will include documentation that they have provided their Wholesale Supplier(s)—if
any—with water use projections from that source.Plan preparation 2-4 R Sections 2.4.1 and 2.5
n/a x 2.4 Section 2.4.1 10631(h)
Wholesale Suppliers will provide their Suppliers with identification and quantification of the existing and
planned sources of water available from the Wholesale Supplier to the Supplier during various water year
types.
Plan preparation 2-4 W n/a
x x 3 Chapter 3.0 10631(a) Describe the Supplier service area.System description n/a Section 3.1 and 3.2
x x 3.3 Section 3.3 10631(a) Describe the climate of the Supplier’s service area. System description n/a Section 3.3
x x 3.4 Section 3.4.1 10631(a)
Provide the current and projected service area populations for 2030, 2035, 2040, 2045 and optionally
2050.System description 3-1 Sections 3.4 and 3.6
x x 3.4 Section 3.4.2 10631(a)
Describe other social, economic, and demographic factors affecting the Supplier’s water management
planning.System description n/a Section 3.4.2
x x 3.5 Section 3.5 10631(a)
Describe the land uses within the service area… include the current and projected land uses within the
existing or anticipated service area affecting the Supplier’s water management planning. Describe the
land uses within the service area.
System description and
baselines n/a Section 3.5
x Optional 4.2 Sections 4.2.3 and 4.2.4 10631(d)(1) Quantify past, current, and projected water use, identifying the uses among water use sectors. System water use 4-1 and 4-2 Sections 4.2 and 4.4
x Optional 4.3 Section 4.3.1 10631(d)(3)(A) Report the distribution system water loss for each of the five years preceding the plan update. System water use 4-5 Sections 4.3 and 4.4
x n/a 4.3 Section 4.3.2 10631(d)(3)(C) Retail Suppliers shall provide data to show the distribution loss standards were met. System water use 4-6 Sections 4.3 and 4.4
x n/a 4.2 Section 4.2.5.4 10631.1(a)
Include projected water use needed for lower income housing projected in the service area of the
Supplier.System water use 4-3 Sections 4.2.5.5 and 4.4
x n/a 4.2 Section 4.2.5.3 10631(d)(4)(A)
In projected water use, include estimates of water savings from adopted codes, plans, and other policies
or laws.System water use 4-3 Section 4.2.5.3
x n/a 4.2 Section 4.2.5.3 10631(d)(4)(B) Provide citations of codes, standards, ordinances, or plans used to make water use projections. System water use 4-3 Sections 4.2.5.3 and 9.1
x n/a 4.2 Section 4.2.5.3 10631(d)(4)(B)(ii)
To the extent that a Supplier reports the information described in subparagraph (A), an urban water
Supplier shall… Indicate the extent that the water use projections consider savings from codes,
standards, ordinances, or transportation and land use plans. Water use projections that do not account
for these water savings shall be noted of that fact.
System water use 4-3 Section 4.2.5.3
x x 4.2 Section 4.2.5.6 10635(b) Demands under climate change considerations must be included as part of the drought risk assessment. System water use n/a Section 4.2.5.6
n/a x 5.1 Section 5.1 10608.36
Wholesale Suppliers shall include an assessment of present and proposed future measures, programs,
and policies to help their Retail Suppliers achieve targeted water use reductions.Baselines and targets n/a n/a
x n/a 5.2 Section 5.2 10608.4
Retail Suppliers shall report on their compliance in meeting their water use targets. Reporting requirements
will vary depending on whether the Supplier:
- Was considered an urban retail water supplier in 2020,
- Met its 2020 target in 2020, or
- Was part of a merger or consolidation since 2020.
Chapter 5 Subsections 5.2.1, 5.2.2, and 5.2.3 address each of these situations.
Baselines and targets 5-1 Sections 5.2 and 5.3
x x 6.1 Section 6.1 10631(b)(2)
When multiple sources of water supply are identified, describe the management of each supply in
relationship to other identified supplies.System supplies n/a Sections 6.1 and 6.2
x x 6.1 Sections 6.1 and 6.2 10631(b)(1)
Provide a discussion of anticipated supply availability under a normal, single dry year, and a drought
lasting five years, as well as more frequent and severe periods of drought, including changes in supply
due to climate change.
System supplies n/a Sections 6.1, 6.2, 7.1, and 7.2
x x 6.2 Section 6.2.2 10631(b)(4)(C)
Indicate whether groundwater is an existing or planned source of water available to the Supplier. If
groundwater is identified as an existing or planned source of water… (include) a detailed description and
analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past five
years.
Water supplies and recycled
water 6-1 Sections 6.2.2 and 6.4
x x 6.2 Section 6.2.2 10631(b)(4)(A)
Indicate whether a groundwater sustainability plan or groundwater management plan has been adopted
by the Supplier or if there is any other specific authorization for groundwater management. Include a
copy of the plan or authorization.
System supplies n/a Section 6.2.2
x x 6.2 Section 6.2.2 10631(b)(4)(B) Describe the groundwater basin.System supplies n/a Section 6.2.2
x x 6.2 Section 6.2.2 10631(b)(4)(B)
Indicate if the basin has been adjudicated and include a copy of the court order or decree and a
description of the amount of water the Supplier has the legal right to pump.System supplies n/a Section 6.2.2
x x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… (include) information as to whether DWR has identified the basin as a high- or
medium-priority basin in the most current official departmental bulletin…
Water supplies and recycled
water n/a Section 6.2.2
x x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… describe efforts by the Supplier to coordinate with sustainability or
groundwater agencies to achieve sustainable groundwater conditions.
Water supplies and recycled
water n/a Section 6.2.2
x x 6.2 Section 6.2.2. 10631(b)(4)(C)
If groundwater is identified as an existing or planned source of water… (include) a detailed description
and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past
five years.
System supplies n/a Section 6.2.2
x x 6.2 Section 6.2.2 10631(b)(4)(D)
Provide a detailed description and analysis of the amount and location of groundwater that is projected to
be pumped.System supplies 6-9 Section 6.2.2
x x 6.1 Section 6.1 10631(b)
Identify and quantify the existing and planned sources of water available for 2025, 2030, 2035, 2040,
2045 and optionally 2050.System supplies 6-8 and 6-9 Section 6.4
x x 6.2 Section 6.2.7 10631(c) Describe the opportunities for exchanges or transfers of water on a short-term or long-term basis. System supplies n/a Section 6.2.7
x n/a 6.2 Section 6.2.5 10633(a)
Describe the wastewater collection and treatment systems in the Supplier’s service area with quantified
amount of collection and treatment and the disposal methods.
System supplies (recycled
water)6-2 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(b)
Describe the quantity of treated wastewater that meets recycled water standards, is being discharged,
and is otherwise available for use in a recycled water project.
System supplies (recycled
water)6-3 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(c) Describe the recycled water currently being used in the Supplier's service area.
System supplies (recycled
water)6-4 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(d)
Describe and quantify the potential uses of recycled water and provide a determination of the technical
and economic feasibility of those uses.
System supplies (recycled
water)6-4 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(e)
Describe the projected use of recycled water within the Supplier's service area at the end of 5, 10, 15,
and 20 years, and describe the actual use of recycled water in comparison to uses previously projected.
System supplies (recycled
water)6-4 and 6-5 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(f)
Describe the actions that may be taken to encourage the use of recycled water and the projected results
of these actions in terms of acre-feet of recycled water used per year.
System supplies (recycled
water)6-6 Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.5 10633(g) Provide a plan for optimizing the use of recycled water in the Supplier's service area.
System supplies (recycled
water)n/a Sections 6.2.5 and 6.4
x x 6.2 Section 6.2.6 10631(g) Describe desalinated water project opportunities for long-term supply. System supplies 6-7 Section 6.2.6
x x 6.2 Section 6.2.10 10631(f)
Describe the expected future water supply projects and programs that may be undertaken by the water
Supplier to address water supply reliability in average, single-dry, and for a period of drought lasting five
consecutive water years.
System supplies 6-7 Sections 6.2.10 and 6.4
x x 6.3 Section 6.3 and Appendix O 10631.2(a) The UWMP must include energy information, as stated in the code, that a Supplier can readily obtain.System suppliers, energy
intensity
O-1A, O-1B, O-1C,
and O-2 Section 6.3
x 7.1 Section 7.1 10634
Provide information on the quality of existing sources of water available to the Supplier and the manner
in which water quality affects water management strategies and supply reliability.
Water supply reliability
assessment n/a Section 7.2
x x 7.2 Section 7.2 10635(a)
Service Reliability Assessment: Assess the water supply reliability during normal, dry, and a drought
lasting five consecutive water years by comparing the total water supply sources available to the Supplier
with the total projected water use over the next 20 years.
Water supply reliability
assessment 7-2, 7-3, and 7-4 Sections 7.3 and 7.4
x x 7.2 Section 7.2.3 10620(f)
Describe water management tools and options to maximize resources and minimize the need to import
water from other regions.
Water supply reliability
assessment n/a Section 7.2.3
x x 7.3 Section 7.3 10635(b)
Provide a drought risk assessment as part of information considered in developing the demand
management measures and water supply projects.
Water supply reliability
assessment n/a Section 7.3
x x 7.3 Section 7.3 10635(b)(1)
Include a description of the data, methodology, and basis for one or more supply shortage conditions that
are necessary to conduct a drought risk assessment for a drought period that lasts five consecutive years.
Water supply reliability
assessment n/a Section 7.3
x x 7.3 Section 7.3 10635(b)(2)
Include a determination of the reliability of each source of supply under a variety of water shortage
conditions.
Water supply reliability
assessment n/a Section 7.3
x x 7.3 Section 7.3 10635(b)(3)
Include a comparison of the total water supply sources available to the Supplier with the total projected
water use for the drought period.
Water supply reliability
assessment 7-5 Section 7.3
x x 7.3 Section 7.3 10635(b)(4)
Include considerations of the historical drought hydrology, plausible changes on projected supplies and
demands under climate change conditions, anticipated regulatory changes, and other locally applicable
criteria.
Water supply reliability
assessment n/a Section 7.3
x x 8 Chapter 8 10632(a) Provide a water shortage contingency plan (WSCP) with specified elements below.
Water shortage contingency
planning n/a Chapter 8
x x 8 Chapter 8 10632(a)(1) Provide an analysis of water supply reliability (from Guidebook Chapter 7) in the WSCP.
Water shortage contingency
planning n/a Chapter 8
x x 8.2 Section 8.2 10632(a)(2)(A)
Provide the written decision-making process and other methods that the Supplier will use each year to
determine its water reliability.
Water shortage contingency
planning n/a Section 8.2
x x 8.2 Section 8.2 10632(a)(2)(B)
Provide data and methodology to evaluate the Supplier’s water reliability for the current year and one dry
year pursuant to factors in the code.
Water shortage contingency
planning n/a Section 8.2
x x 8.3 Section 8.3 10632(a)(3)(A)
Define six standard water shortage levels of 10%, 20%, 30%, 40%, 50% shortage, and greater than
50% shortage. These levels shall be based on supply conditions, including percent reductions in supply,
changes in groundwater levels, changes in surface elevation, or other conditions. The shortage levels
shall also apply to a catastrophic interruption of supply.
Water shortage contingency
planning n/a Section 8.3
x x 8.3 Section 8.3 10632(a)(3)(B)
Suppliers with an existing WSCP that uses different water shortage levels must cross reference their
categories with the six standard categories.
Water shortage contingency
planning 8-1 Sections 8.3 and 8.14
x x 8.4 Section 8.4 10632(a)(4)(A)
Suppliers with WSCPs that align with the defined shortage levels must specify locally appropriate supply
augmentation actions.
Water shortage contingency
planning 8-2 Sections 8.4.1 and 8.14
x x 8.4 Section 8.4 10632(a)(4)(B) Specify locally appropriate demand reduction actions to adequately respond to shortages.
Water shortage contingency
planning 8-3 Sections 8.4.2 and 8.14
x x 8.4 Section 8.4 10632(a)(4)(C) Specify locally appropriate operational changes.
Water shortage contingency
planning 8-2 Section 8.4.3
x x 8.4 Section 8.4 10632(a)(4)(D)
Specify additional mandatory prohibitions against specific water use practices that are in addition to State-
mandated prohibitions are appropriate to local conditions.
Water shortage contingency
planning Table 8-3 Section 8.4.4
x x 8.4 Section 8.4 10632(a)(4)(E)
Estimate the extent to which the gap between supplies and demand will be reduced by implementation of
the action.
Water shortage contingency
planning 8-2 and 8-3 Sections 8.4.7 and 8.14
x x 8.4 Section 8.4.6 10632.5 The UWMP shall include a seismic risk assessment and mitigation plan.
Water shortage contingency
plan n/a Section 8.4.6
x x 8.5 Section 8.5 10632(a)(5)(A)
Suppliers must describe that they will inform customers, the public and others regarding any current or
predicted water shortages.
Water shortage contingency
planning n/a Section 8.5
x x 8.5 Section 8.5
10632(a)(5)(B),
10632(a)(5)(C)
Suppliers must describe that they will inform customers, the public and others regarding any shortage
response actions triggered or anticipated to be triggered and other relevant communications.
Water shortage contingency
planning n/a Section 8.5
x n/a 8.6 Section 8.6 10632(a)(6) Retail Supplier must describe how it will ensure compliance with and enforce provisions of the WSCP.Water shortage contingency
planning n/a Section 8.6
x x 8.7 Section 8.7 10632(a)(7)(A) Describe the legal authority that empowers the Supplier to enforce shortage response actions.
Water shortage contingency
planning n/a Section 8.7
x x 8.7 Section 8.7 10632(a)(7)(B)
Provide a statement that the Supplier will declare a water shortage emergency per Water Code
Chapter 3. Water Shortage Emergencies .
Water shortage contingency
planning n/a Section 8.7
x x 8.7 Section 8.7 10632(a)(7)(C)
Provide a statement that the Supplier will coordinate with any city or county within which it provides
water for the possible proclamation of a local emergency.
Water shortage contingency
planning n/a Section 8.7
x x 8.8 Section 8.8 10632(a)(8)(A)
Describe the potential revenue reductions and expense increases associated with activated shortage
response actions.
Water shortage contingency
planning n/a Section 8.8
x x 8.8 Section 8.8 10632(a)(8)(B)
Provide a description of mitigation actions needed to address revenue reductions and expense increases
associated with activated shortage response actions.
Water shortage contingency
planning n/a Section 8.8
x n/a 8.8 Section 8.8 10632(a)(8)(C)
Retail Suppliers must describe the cost of compliance with Water Code Chapter 3.3, Excessive Residential
Water Use During Drought .
Water shortage contingency
planning n/a Section 8.8
x n/a 8.9 Section 8.9 10632(a)(9)
Retail Suppliers must describe the monitoring and reporting requirements and procedures that ensure
appropriate data are collected, tracked, and analyzed for purposes of monitoring customer compliance.
Water shortage contingency
planning n/a Section 8.9
x x 8.10 Section 8.10 10632(a)(10)
Describe reevaluation and improvement procedures for monitoring and evaluation the WSCP to ensure
risk tolerance is adequate and appropriate water shortage mitigation strategies are implemented.
Water shortage contingency
planning n/a Section 8.10
x n/a 8.11 Section 8.11 10632(b)
Analyze and define water features that are artificially supplied with water, including ponds, lakes,
waterfalls, and fountains, separately from swimming pools and spas.
Water shortage contingency
planning n/a Section 8.11
x x 8.12 Section 8.12 10632(c)
Make available the WSCP to customers and any city or county where it provides water within 30 days
after adoption of the plan.
Water shortage contingency
planning n/a Sections 8.12 and 10.6
x n/a 9.1 Sections 9.1 10631(e)(1)
Retail Suppliers shall provide a description of the nature and extent of each demand management
measure implemented over the past five years. The description will address specific measures listed in
code.
Demand management
measures n/a Section 9.1.1
n/a x 9.2 Sections 9.2 10631(e)(2)
Wholesale Suppliers shall describe specific demand management measures listed in code, their
distribution system asset management program, and Supplier assistance program.
Demand management
measures n/a n/a
x n/a 10 Chapter 10 10608.26(a)
Retail Suppliers shall conduct a public hearing to discuss adoption, implementation, and economic impact
of water use targets (recommended to discuss compliance).
Plan adoption, submittal, and
implementation n/a Sections 10.3 and 10.4
x x 10.2 Section 10.2.1 10621(b)
Notify, at least 60 days prior to the public hearing, any city or county within which the Supplier provides
water that the Supplier will be reviewing the UWMP and considering amendments or changes to the plan.
Plan adoption, submittal, and
implementation 10-1 Section 10.2
x x 10.4 Section 10.4 10621(f) Each urban water Supplier shall update and submit its 2025 plan to DWR by July 1, 202 6.Plan adoption, submittal, and
implementation n/a Section 10.5
x x 10.2
Sections 10.2.2, 10.3, and
10.5 10642 Provide supporting documentation that the Supplier made the UWMP and WSCP available for public
inspection, published notice of the public hearing, and held a public hearing about the UWMP and WSCP.
Plan adoption, submittal, and
implementation n/a Sections 10.2, 10.3, and 10.4
x x 10.2 Section 10.2.2 10642
The Supplier is to provide the time and place of the hearing to any city or county within which the
Supplier provides water.
Plan adoption, submittal, and
implementation 10-1 Section 10.3
x x 10.3 Section 10.3.2 10642 Provide supporting documentation that the UWMP and WSCP has been adopted as prepared or modified.
Plan adoption, submittal, and
implementation n/a Sections 10.4 and 10.9
x x 10.4 Section 10.4 10644(a)
Provide supporting documentation that the Supplier has submitted their UWMP to the California State
Library.
Plan adoption, submittal, and
implementation n/a Section 10.5.3
x x 10.4 Section 10.4 10644(a)(1)
Provide supporting documentation that the Supplier has submitted their UWMP to any city or county
within which the Supplier provides water no later than 30 days after adoption.
Plan adoption, submittal, and
implementation n/a Section 10.5.4
x x 10.4 Sections 10.4.1 and 10.4.2 10644(a)(2) The UWMP, or amendments to the UWMP, submitted to DWR shall be submitted electronically.Plan adoption, submittal, and
implementation n/a Sections 10.5 and 10.9
x x 10.7 Section 10.7.2 10644(b) If revised, submit a copy of the WSCP to DWR within 30 days of adoption.
Plan adoption, submittal, and
implementation n/a Section 10.9
x x 10.5 Section 10.5 10645(a)
Provide supporting documentation that, not later than 30 days after filing a copy of its UWMP with DWR,
the Supplier has or will make the plan available for public review during normal business hours.
Plan adoption, submittal, and
implementation n/a Section 10.6
x x 10.5 Section 10.5 10645(b)
Provide supporting documentation that, not later than 30 days after filing a copy of its WSCP with DWR,
the Supplier has or will make the plan available for public review during normal business hours.
Plan adoption, submittal, and
implementation n/a Section 10.6
x x 10.6 Section 10.6 10621(c)
If Supplier is regulated by the Public Utilities Commission, include its plan and contingency plan as part of
its general rate case filings.
Plan adoption, submittal, and
implementation n/a Section 10.7
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX C
DEMONSTRATION OF REDUCED IMPORTED WATER
RELIANCE
DEMONSTRATION OF CONSISTENCY WITH THE DELTA PLAN FOR
PARTICIPANTS IN COVERED ACTIONS
(2015 THROUGH 2050)
CITY OF ARCADIA
Introduction
Pursuant to the California Department of Water Resources (DWR), an urban water
supplier that anticipates participating in or receiving water from a proposed project (or
“covered action”) such as a multi-year water transfer, conveyance facility, or new
diversion that involves transferring water through, exporting water from, or using water in
the Sacramento-San Joaquin Delta (Delta) should provide information in their 2015, 2020,
2025 Urban Water Management Plans (UWMPs) for use in demonstrating consistency
with Delta Plan Policy WR P1, “Reduce Reliance on the Delta Through Improved
Regional Water Self-Reliance”. In addition, pursuant to California Code of Regulations,
Title 23, § 5003:
(c)(1) Water suppliers that have done all of the following are contributing to reduced
reliance on the Delta and improved regional self-reliance and are therefore consistent with
this policy:
(A) Completed a current Urban or Agricultural Water Management Plan (Plan)
which has been reviewed by the California Department of Water Resources for
compliance with the applicable requirements of Water Code Division 6, Parts 2.55,
2.6, and 2.8;
(B) Identified, evaluated, and commenced implementation, consistent with the
implementation schedule set forth in the Plan, of all programs and projects
included in the Plan that are locally cost effective and technically feasible which
reduce reliance on the Delta; and
(C) Included in the Plan, commencing in 2015, the expected outcome for
measurable reduction in Delta reliance and improvement in regional self-reliance.
The expected outcome for measurable reduction in Delta reliance and
improvement in regional self-reliance shall be reported in the Plan as the reduction
in the amount of water used, or in the percentage of water used, from the Delta
watershed. For the purposes of reporting, water efficiency is considered a new
source of water supply, consistent with Water Code section 1011(a).
The City is member agency of the Upper San Gabriel Valley Water District, which in turn
is a member agency of the Metropolitan Water District of Southern California (MWD). As
noted in MWD’s document entitled “Infeasibility of Accounting Supplies from the Delta
Watershed for Metropolitan’s Member Agencies and their Customers” (which is included
in MWD’s 2025 Regional UWMP, Appendix 10 (provided as Attachment 1 below), “...
Metropolitan and its members as well as their customers are measurably reducing
reliance on the Delta and improving regional self-reliance, both as an amount of water
used and as a percentage of water used.”
In addition, MWD’s 2025 Regional UWMP indicates “...in accordance with UMWP
requirements, Metropolitan’s member agencies and their customers (many of them, retail
agencies) also report demands and supplies for their service areas in their respective
UWMPs. The data reported by those agencies are not additive to the regional totals
shown in Metropolitan’s UWMP; rather, their reporting represents subtotals of the regional
total and should be considered as such for the purposes of determining reduced reliance
on the Delta…While the demands that Metropolitan’s member agencies and their
customers report in their UWMPs are a good reflection of the demands in their respective
service areas, they do not adequately represent each water supplier’s contributions to
reduced reliance on the Delta. In order to calculate and report their reliance on water
supplies from the Delta watershed, water suppliers that receive water from the Delta
through other regional or wholesale water suppliers would need to determine the amount
of Delta water that they receive from the regional or wholesale supplier. Two specific
pieces of information are needed to accomplish this: first is the quantity of demands on
the regional or wholesale water supplier that accurately reflect a supplier’s contributions
to reduced reliance on the Delta, and second is the quantity of a supplier’s demands on
the regional or wholesale water supplier that are met by supplies from the Delta
watershed…For water suppliers that make investments in regional projects or programs
it may be infeasible to quantify their demands on the regional or wholesale water supplier
in a way that accurately reflects their individual contributions to reduced reliance on the
Delta.” Nonetheless, the City has taken proactive measures to help reduce regional
reliance on imported water supplies and is discussed in the following sections.
Reduced Reliance Calculation Tables
Pursuant to DWR guidance, Tables C-1 through C-4 were prepared to show the potential
reduction of reliance on imported water supplies for the City. The City has used these
tables to demonstrate its reduced regional reliance on imported water supplies, but not
specifically Delta Watershed supplies. For each of the tables, a “Baseline year” was
selected. Water demands during subsequent years (from 2015 through 2050 in five-year
increments) were compared to water demands during the Baseline year. Table C-1
considers the population and service area water demands, and a demand in gallons per
capita per day (GPCD) water use rate was calculated for each of the years following the
Baseline year. The calculated reduction in GPCD from the Baseline year was then
translated to an estimated amount of water saved as a result of water conservation
measures. Table C-2 references the estimated amount of water saved from Table C-1
and shows the City’s water demand without water use efficiency in effect.
A method of showing reduced regional reliance on imported water supplies is to show
increased regional self-reliance. Table C-3 lists water supply sources that contribute to
regional self-reliance, including water use efficiency (from Table C-1 and C-2) and
groundwater recharge activities. Regional self-reliance is expressed both in terms of acre
feet (AF) and as a percentage.
The calculation of reduced regional reliance on imported water supplies is shown on
Table C-4. Table C-4 also shows the percent change in imported water supplies relative
to the City’s total supply. A negative percent change of imported water supplies indicates
the City has reduced regional reliance on imported water supplies.
Since the Baseline year, the City has decreased its reliance on imported water supplies
in 2015, 2020, 2025, and anticipates doing so through 2050.
The City has reduced regional reliance on imported water supplies through the following:
x The demand in GPCD for the "Baseline year" was compared to the GPCDs in
subsequent years (from 2015 through 2050, in five-year increments). The reduced
GPCD multiplied by the population in these subsequent years is indicative of the
potential reduced regional reliance on imported water supplies and is included in
Table C-1.
x To the extent the Main Basin Watermaster has, or plans to, use recycled water to
replenish the Main Basin, the City’s proportional share (up to the total
replenishment water obligation) will be included in Table C-1.
These categories of reduced regional reliance on imported water supplies are discussed
below. The sum of the increased regional self-reliance and the sum of the reduced
regional reliance on imported water demand resulting from these categories is reflected
on Table C-3 and Table C-4, respectively, and is reflective of the City’s overall reduced
reliance.
Reduced GPCD
Section 6.2.2 of the City’s 2025 UWMP describes the management of the Main Basin.
The City relies on groundwater produced from the Main Basin, which is adjudicated and
managed by the Main Basin Watermaster. To the extent the City historically (baseline
during 2011) has produced groundwater in excess of its water rights, it has paid
assessments to the Main Basin Watermaster which are then used to purchase untreated
imported water from the Upper San Gabriel Valley Municipal Water District (Upper Water),
which is in turn purchased water from the Metropolitan Water District of Southern
California. The untreated imported water subsequently is delivered to replenish the Main
Basin and to supplement local storm water replenishment. In addition, the City can
purchase treated imported water from Upper Water which is ultimately provided by the
Metropolitan Water District of Southern California.
Chapter 9 of this 2025 UWMP describes the Demand Management Measures which the
City has implemented to reduce the amount water used by its customers. In addition,
Chapter 6 of the 2025 UWMP describes the groundwater basin management measures
implemented by the Main Basin Watermaster. Collectively these actions translate to a
reduction in the GPCD usage rate which is described further in Chapter 5 of the 2025
UWMP. These actions directly impact total water demands, and consequently, the
quantity of imported water which may be required. Absent the proactive measures taken
by the City, it is anticipated there may have been a greater demand on imported water
supplies.
Pursuant to DWR guidance, reduced reliance on imported water supplies can be
demonstrated by first selecting a “Baseline” water demand, represented by total potable
water demands during 2011. Table C-1 summarizes the “Baseline” water usage by the
City in 2011 (assuming demand reduction efforts had not been implemented); actual
water usage in 2015, 2020, and 2025; and projected water usage through 2050 in five-
year increments. Furthermore, it is assumed that as of 2011 the City was already
exceeding its water rights and was required to fund the purchase of untreated imported
water. Table C-2 demonstrates that, if water conservation measures had not been
implemented by the City, there may have been a greater reliance on untreated imported
water supplies during subsequent years as compared to the Baseline year. However, as
discussed below and shown in Table C-1, the reduced water demands have resulted in
reduced regional reliance on imported water supplies as compared to the Baseline year.
The City’s potable water demand during 2011, along with the corresponding service area
population, were used to determine the Baseline GPCD. Subsequently, the actual
demands for 2015, 2020, and 2025 were compared to the calculated population to obtain
the recent GPCD which includes the water conservations measures which have been
implemented (those demand management measures are described in Chapter 9 of the
2025 UWMP). The “Water Supplies Contributing to Regional Self-Reliance" are also
provided in Table C-3. The differences between the Baseline GPCD and the 2015, 2020,
2025 GPCDs are effectively considered a demonstration of the reduced regional reliance
on imported water supplies with the understanding that any potential increased demand
by the City resulting from increased population could have been required from imported
water supplies, absent the City’s new water supplies which contribute to self-reliance. A
similar methodology is used for the projected potable water demands (2025 UWMP Table
4-2) and populations (2025 UWMP Table 3-1).
Recycled Water for Groundwater Replenishment
In addition to the historical actions the City has taken in conjunction with groundwater
management agencies, the City is involved in a regional program to deliver recycled water
to the San Gabriel Valley to replenish the Main San Gabriel Basin. The Metropolitan Water
District of Southern California is developing its “Regional Recycled Water Program”
(RRWP). MWD is partnering with the Los Angeles County Sanitation Districts (LACSD)
to investigate the viability of providing up to 150 million gallons per day (MGD)
(approximately 168,000 AFY) of advanced treated wastewater from LACSD’s Joint Water
Pollution Control Plant located in Carson, California (Carson Plant). The RRWP would
deliver purified water from the Carson Plant through up to 60 miles of transmission
pipelines to groundwater basins within MWD’s service area, including the Main Basin.
The purified water would be used in various locations within MWD’s service area for
groundwater recharge, groundwater storage, and industrial facilities. In addition, purified
water could potentially be treated further at two of MWD’s existing water treatment plants
for direct potable reuse. The locations of the proposed pipeline alignments are provided
in the figure below.
Regional Recycled Water Program Location
Source: https://www.mwdh2o.com/building-local-supplies/pure-water-southern-california/
MWD began construction of a $17 million small-scale demonstration plant (0.5 MGD) in
late 2017 which was completed in October 2019. The results of the demonstration plant
will allow MWD and others to determine whether expansion to a full-scale plant is
beneficial. Once approved the full-scale plant, associated pipelines and ancillary facilities
would take approximately 11 years to construct at an estimated cost of over $3 billion.
Pursuant to MWD’s “Regional Recycled Water Program Conceptual Planning Studies
Report”, February 2019, the proposed Pure Water project would potentially provide
60,000 to 80,000 AFY to replenish the Main Basin. A portion of the replenished recycled
water may be designated as Replacement Water (see Section 6.2.2 of the 2025 UWMP)
and will offset all State Water Project water (on an AF for AF basis) which historically has
been used to replenish the Main Basin groundwater supplies and is essential to sound
basin management. Furthermore, some of the replenished recycled water may be used
for general Basin benefit which will result in higher groundwater levels and potentially
enable the Operating Safe Yield to be established at a higher amount than had no
deliveries occurred. For the Main Basin, MWD has entered into a letter of intent with
Upper Water for at least 35,000 AFY and with Three Valleys District for at least 6,500
AFY, and will potentially provide up to 60,000 to 80,000 AFY, collectively.
For the purposes of this Plan and to illustrate the anticipated benefits the Pure Water
project will have for reduced regional reliance on imported water supplies, it is assumed
20,000 AFY from the Pure Water project will be replenished in the Main Basin
commencing in the year 2035 and up to 40,000 AFY will be replenished commencing in
the year 2040 and thereafter. The recharged water hypothetically assigned to the City is
based on projected groundwater use less the City’s share of the Main Basin's current
Operating Safe Yield (150,000 AFY). The balance is production in excess of water rights
and subject to replenishment; 50 percent of that amount is assumed to be delivered from
the Pure Water project in 2035 and 100 percent in 2040 and thereafter. Because all SWP
water deliveries will be offset through the Pure Water project, Table C-3 includes 50
percent of the City’s Replacement Water requirement in 2035 (under Advanced Water
Technologies) and all of the Replacement Water requirement in 2040 and thereafter.
The decrease in GPCD compared to the Baseline year has resulted in an overall decrease
in reliance on water supplies from imported water supplies. As shown in Table C-4, the
percentage of water supplies from imported water supplies relative to the City’s total
supply has decreased, and is projected to decrease, from the percentage in the Baseline
year.
Metropolitan Water District of Southern California
In addition, as the wholesale provider, the Metropolitan Water District of Southern
California has included a detailed discussion regarding measurable reduction in Delta
reliance in Appendix 10 of its 2025 Regional Urban Water Management Plan. That
discussion is included by reference and also included in Attachment 1 of this Plan.
Table C-1: Optional Calculation of Water Use Efficiency -To be completed if Water Supplier does not specifically estimate Water Use Efficiency as a supply
Service Area Water Use Efficiency Demands
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Service Area Water Demands with Water Use Efficiency Accounted For 16,399 12,369 13,935 13,294 14,773 16,144 16,225 16,308 16,388
Non-Potable Water Demands
Potable Service Area Demands with Water Use Efficiency Accounted For 16,399 12,369 13,935 13,294 14,773 16,144 16,225 16,308 16,388
Total Service Area Population
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Service Area Population 54,000 55,342 53,998 54,700 60,303 65,903 66,233 66,564 66,897
Water Use Efficiency Since Baseline
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Per Capita Water Use (GPCD)271 200 230 217 219 219 219 219 219
Change in Per Capita Water Use from Baseline (GPCD) (72) (41) (54) (52) (52) (52) (52) (52)
Estimated Water Use Efficiency Since Baseline 4,438 2,463 3,318 3,540 3,870 3,889 3,906 3,927
Table C-2: Calculation of Service Area Water Demands Without Water Use Efficiency
Total Service Area Water Demands
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Service Area Water Demands with Water Use Efficiency Accounted For 16,399 12,369 13,935 13,294 14,773 16,144 16,225 16,308 16,388
Reported Water Use Efficiency or Estimated Water Use Efficiency Since Baseline 4,438 2,463 3,318 3,540 3,870 3,889 3,906 3,927
Service Area Water Demands without Water Use Efficiency Accounted For 16,399 16,806 16,398 16,611 18,313 20,014 20,114 20,214 20,315
Table C-3: Calculation of Supplies Contributing to Regional Self-Reliance
Water Supplies Contributing to Regional Self-Reliance
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Water Use Efficiency - 4,438 2,463 3,318 3,540 3,870 3,889 3,906 3,927
Water Recycling
Stormwater Capture and Use
Advanced Water Technologies (Pure Water - Main Basin)1 - - - - - 3,349 6,779 6,862 6,942
Conjunctive Use Projects
Local and Regional Water Supply and Storage Projects
Other Programs and Projects the Contribute to Regional Self-Reliance
Water Supplies Contributing to Regional Self-Reliance - 4,438 2,463 3,318 3,540 7,218 10,667 10,768 10,869
Service Area Water Demands without Water Use Efficiency
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Service Area Water Demands without Water Use Efficiency Accounted For 16,399 16,806 16,398 16,611 18,313 20,014 20,114 20,214 20,315
Change in Regional Self Reliance
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Water Supplies Contributing to Regional Self-Reliance - 4,438 2,463 3,318 3,540 7,218 10,667 10,768 10,869
Change in Water Supplies Contributing to Regional Self-Reliance 4,438 2,463 3,318 3,540 7,218 10,667 10,768 10,869
Percent Change in Regional Self Reliance
(As Percent of Demand w/out WUE)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Percent of Water Supplies Contributing to Regional Self-Reliance 0.0% 26.4% 15.0% 20.0% 19.3% 36.1% 53.0% 53.3% 53.5%
Change in Percent of Water Supplies Contributing to Regional Self-Reliance 26.4% 15.0% 20.0% 19.3% 36.1% 53.0% 53.3% 53.5%
Table C-4: Calculation of Reliance on Water Supplies from the Delta Watershed
Water Supplies from the Delta Watershed
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
CVP/SWP Contract Supplies
Delta/Delta Tributary Diversions
Transfers and Exchanges
Other Water Supplies from the Delta Watershed (Untreated)2 5,369 3,114 5,216 4,008 5,327 3,349 - - -
Total Water Supplies from the Delta Watershed 5,369 3,114 5,216 4,008 5,327 3,349 - - -
Service Area Water Demands without Water Use Efficiency
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Service Area Water Demands without Water Use Efficiency Accounted For 16,399 16,806 16,398 16,611 18,313 20,014 20,114 20,214 20,315
Change in Supplies from the Delta Watershed
(Acre-Feet)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Water Supplies from the Delta Watershed 5,369 3,114 5,216 4,008 5,327 3,349 - - -
Change in Water Supplies from the Delta Watershed (2,255) (153) (1,361) (43) (2,020) (5,369) (5,369) (5,369)
Percent Change in Supplies from the Delta Watershed
(As a Percent of Demand w/out WUE)
Baseline
(2011)2015 2020 2025 2030 2035 2040 2045
2050
(Optional)
Percent of Water Supplies from the Delta Watershed 32.7% 18.5% 31.8% 24.1% 29.1% 16.7% 0.0% 0.0% 0.0%
Change in Percent of Water Supplies from the Delta Watershed -14.2% -0.9% -8.6% -3.7% -16.0% -32.7% -32.7% -32.7%
1
2
The Pure Water Southern California Project is anticipated to meet all of the City's water replenishment obligations in the Main Basin. Based on the City's production less the City's share (4.23099%) of the Main Basin's
Operating Safe Yield (150,000 AFY). It is assumed that 50% of the recharged water will be available in 2035 before Pure Water is fully operational in 2040.
Represents imported untreated water to satisfy replenishment obligations due to Main Basin overproduction. Based on the City's production less water available to the City from Pure Water and less the City's share
(4.23099%) of the Operating Safe Yield (150,000 AFY).
Appendix 10
QUANTIFYING REGIONAL SELF-RELIANCE AND
REDUCED RELIANCE ON WATER SUPPLIES FROM THE
DELTA WATERSHED
$WWDFKPHQW
Metropolitan’s Reduced Delta Reliance Reporting A.10-1
Appendix 10
METROPOLITAN’S
REDUCED DELTA RELIANCE REPORTING
A.10.1 Background
Under the Sacramento-San Joaquin Delta Reform Act of 2009, state and local public
agencies proposing a covered action in the Delta,1 prior to initiating the implementation of
that action, must prepare a written certification of consistency with detailed findings as to
whether the covered action is consistent with applicable Delta Plan policies and submit that
certification to the Delta Stewardship Council.2 Anyone may appeal a certification of
consistency, and if the Delta Stewardship Council grants the appeal, the covered action
may not be implemented until the agency proposing the covered action submits a revised
certification of consistency, and either no appeal is filed, or the Delta Stewardship Council
denies the subsequent appeal.3
An urban water supplier that anticipates participating in or receiving water from a proposed
covered action such as a multi-year water transfer, conveyance facility, or new diversion
that involves transferring water through, exporting water from, or using water in the Delta
should provide information in their 2015 and subsequent Urban Water Management Plans
(UWMPs) that can then be used in the covered action process to demonstrate consistency
with Delta Plan Policy WR P1, Reduce Reliance on the Delta Through Improved Regional
Water Self-Reliance (WR P1).4
WR P1 details what is needed for a covered action to demonstrate consistency with
reduced reliance on the Delta and improved regional self-reliance. WR P1 subsection (a)
states that:
(a) Water shall not be exported from, transferred through, or used in the Delta if all of
the following apply:
(1) One or more water suppliers that would receive water as a result of the
export, transfer, or use have failed to adequately contribute to reduced
reliance on the Delta and improved regional self-reliance consistent with all of
the requirements listed in paragraph (1) of subsection (c);
(2) That failure has significantly caused the need for the export, transfer, or use;
and
(3) The export, transfer, or use would have a significant adverse environmental
impact in the Delta.
WR P1 subsection (c)(1) further defines what adequately contributing to reduced reliance
on the Delta means in terms of (a)(1) above.
1 Water Code, § 85057.5; Cal. Code Regs. tit. 23, § 5001.
2 Water Code, § 85225; Delta Plan, App. D.
3 Water Code, §§ 85225.10-85225.25; Delta Plan, App. D.
4 Cal. Code Regs., tit. 23, § 5003.
A.10-2 Metropolitan’s Reduced Delta Reliance Reporting
(c)(1) Water suppliers that have done all the following are contributing to reduced reliance
on the Delta and improved regional self-reliance and are therefore consistent with this
policy:
(A) Completed a current Urban or Agricultural Water Management Plan (Plan)
which has been reviewed by the California Department of Water Resources for
compliance with the applicable requirements of Water Code Division 6, Parts
2.55, 2.6, and 2.8;
(B) Identified, evaluated, and commenced implementation, consistent with the
implementation schedule set forth in the Plan, of all programs and projects
included in the Plan that are locally cost effective and technically feasible which
reduce reliance on the Delta; and
(C) Included in the Plan, commencing in 2015, the expected outcome for
measurable reduction in Delta reliance and improvement in regional self-
reliance. The expected outcome for measurable reduction in Delta reliance and
improvement in regional self-reliance shall be reported in the Plan as the
reduction in the amount of water used, or in the percentage of water used, from
the Delta watershed. For the purposes of reporting, water efficiency is
considered a new source of water supply, consistent with Water Code section
1011(a).
The analysis and documentation provided below include all of the elements described in
WR P1(c)(1) that need to be included in a water supplier’s UWMP to support a certification
of consistency for a future covered action.
A.10.2 Summary of Expected Outcomes for Reduced Reliance on the Delta
As stated in WR P1(c)(1)(C), the policy requires that, commencing in 2015, UWMPs
include expected outcomes for measurable reduction in Delta reliance and improved
regional self-reliance. WR P1 further states that those outcomes shall be reported in the
UWMP as the reduction in the amount of water used, or in the percentage of water used,
from the Delta.
The expected outcomes for Metropolitan’s Delta reliance and regional self-reliance were
developed using the approach and guidance described in Appendix C of DWR’s Urban
Water Management Plan Guidebook 2025 (Guidebook Appendix C) issued in 2025.
The data used in this analysis represent the total regional efforts of Metropolitan and its
member agencies and their customers (many of them, retail agencies) and were developed
in conjunction with Metropolitan’s member agencies as part of the UWMP coordination
process as described in Chapter 5 of Metropolitan’s UWMP. In accordance with UWMP
requirements, Metropolitan’s member agencies and their customers (many of them, retail
agencies) also report demands and supplies for their service areas in their respective
UWMPs. The data reported by those agencies are not additive to the regional totals shown
in Metropolitan’s UWMP; rather, their reporting represents subtotals of the regional total
and should be considered as such for the purposes of determining reduced reliance on the
Delta.
Metropolitan’s Reduced Delta Reliance Reporting A.10-3
While the demands that Metropolitan’s member agencies and their customers report in their
UWMPs are a good reflection of the demands in their respective service areas, they do not
adequately represent each water supplier’s contributions to reduced reliance on the Delta.
In order to calculate and report their reliance on water supplies from the Delta watershed,
water suppliers that receive water from the Delta through other regional or wholesale water
suppliers would need to determine the amount of Delta water that they receive from the
regional or wholesale supplier. Two specific pieces of information are needed to
accomplish this: first is the quantity of demands on the regional or wholesale water supplier
that accurately reflect a supplier’s contributions to reduced reliance on the Delta, and
second is the quantity of a supplier’s demands on the regional or wholesale water supplier
that are met by supplies from the Delta watershed.
For water suppliers that make investments in regional projects or programs it may be
infeasible to quantify their demands on the regional or wholesale water supplier in a way
that accurately reflects their individual contributions to reduced reliance on the Delta. Due
to the extensive, long-standing and successful implementation of regional demand
management and local resource incentive programs in Metropolitan’s service area, this
infeasibility holds true for Metropolitan’s members as well as their customers. For
Metropolitan’s service area, reduced reliance on supplies from the Delta watershed can
only be accurately accounted at the regional level, as is demonstrated in this analysis.
The following provides a summary of the near-term (2030) and long-term (2050) expected
outcomes for Metropolitan’s Delta reliance and regional self-reliance. The results show that
as a region, Metropolitan and its members as well as their customers are measurably
reducing reliance on the Delta and improving regional self-reliance, both as an amount of
water used and as a percentage of water used.
Expected Outcomes for Regional Self-Reliance
x Near-term (2030) – Normal water year regional self-reliance is expected to increase by
601 TAF from the 2010 baseline; this represents an increase of almost 20 percent of
2030 normal water year retail demands (Table A.10-2).
x Long-term (2050) – Normal water year regional self-reliance is expected to increase by
more than 1.02 MAF from the 2010 baseline, this represents an increase of more than
20 percent of 2050 normal water year retail demands (Table A.10-2).
Expected Outcomes for Reduced Reliance on Supplies from the Delta Watershed
x Near-term (2030) – Normal water year reliance on supplies from the Delta watershed
decreased by 466 TAF from the 2010 baseline, this represents a decrease of more than
6 percent of 2030 normal water year retail demands (Table A.10-3).
x Long-term (2050) – Normal water year reliance on supplies from the Delta watershed
decreased by 537 TAF from the 2010 baseline, this represents a decrease of just over
9 percent of 2050 normal water year retail demands (Table A.10-3).
A10.3 Demonstration of Reduced Reliance on the Delta
The methodology used to determine Metropolitan’s reduced Delta reliance and improved
regional self-reliance is consistent with the approach detailed in DWR’s UWMP Guidebook
Appendix C, including the use of narrative justifications for the accounting of supplies and
A.10-4 Metropolitan’s Reduced Delta Reliance Reporting
the documentation of specific data sources. Some of the key assumptions underlying
Metropolitan’s demonstration of reduced reliance include:
x All data were obtained from the current 2025 UWMP or previously adopted UWMPs and
represent average or normal water year conditions.
x All analyses were conducted at the service area level, and all data reflect the total
contributions of Metropolitan and its members as well as their customers.
x No projects or programs that are described in the UWMPs as “Projects Under
Development” were included in the accounting of supplies.
Baseline and Expected Outcomes
In order to calculate the expected outcomes for measurable reduction in Delta reliance and
improved regional self-reliance, a baseline is needed to compare against. This analysis
uses a normal water year representation of 2010 as the baseline, which is consistent with
the approach described in the Guidebook Appendix C. Data for the 2010 baseline were
taken from Metropolitan’s 2005 UWMP as the UWMPs generally do not provide normal
water year data for the year that they are adopted (i.e., 2005 UWMP forecasts begin in
2010, 2010 UWMP forecasts begin in 2015, and so on).
Consistent with the 2010 baseline data approach, the expected outcomes for reduced Delta
reliance and improved regional self-reliance for 2015, 2020, and 2025 were taken from
Metropolitan’s 2010, 2015, and 2020 UWMPs respectively. Expected outcomes for 2030-
2050 are from the current 2025 UWMP. Documentation of the specific data sources and
assumptions are included in the discussions below.
Service Area Demands Without Water Use Efficiency
In alignment with the Guidebook Appendix C, this analysis uses normal water year
demands, rather than normal water year supplies to calculate expected outcomes in terms
of the percentage of water used. Using normal water year demands serves as a proxy for
the amount of supplies that would be used in a normal water year, which helps alleviate
issues associated with how supply capability is presented to fulfill requirements of the Act
versus how supplies might be accounted for to demonstrate consistency with WR P1.
Because WR P1 considers water use efficiency savings a source of water supply, water
suppliers such as Metropolitan that explicitly calculate and report water use efficiency
savings in their UWMP will need to make an adjustment to properly reflect normal water
year demands in the calculation of reduced reliance. As explained in the Guidebook
Appendix C, water use efficiency savings must be added back to the normal year demands
to represent demands without water use efficiency savings accounted for; otherwise the
effect of water use efficiency savings on regional self-reliance would be overestimated.
Table A.10-1 shows the results of this adjustment for Metropolitan. Supporting narratives
and documentation for all of the data shown in Table A.10-1 are provided below.
Metropolitan’s Reduced Delta Reliance Reporting A.10-5
Table A.10-1
Demands without Water Use Efficiency Accounted For
Total Service Area Water Demands
(Acre-Feet)
Baseline
(2010) 2015 2020 2025 2030 2035 2040 2045 2050
Service Area Demands with Water Use Efficiency Accounted For 4,628,000 4,563,000 4,163,000 3,763,000 3,798,000 3,879,000 3,920,000 3,945,000 3,972,000
Reported Water Use Efficiency 865,000 936,000 1,056,000 1,162,000 1,171,000 1,223,000 1,289,000 1,357,000 1,419,000
Service Area Demands without Water Use Efficiency
Accounted For
5,493,000
5,499,000
5,219,000
4,925,000
4,969,000
5,102,000
5,209,000
5,302,000
5,391,000
Service Area Demands without Water Use Efficiency
The service area demands shown in Table A.10-1 represent the total retail water demands
for Metropolitan’s service area and include municipal and industrial demands, agricultural
demands, seawater barrier demands, and storage replenishment demands. These demand
types and the modeling methodologies used to calculate them are described in Chapter 2.2
and Appendix 1 of Metropolitan’s UWMP.
Water Use Efficiency
The water use efficiency numbers shown in Table A.10-1 represent the total water use
efficiency savings (conservation) for Metropolitan’s region, including savings from active,
code-based, price-effect and pre-1990 sources. These sources of water use efficiency and
the methodologies used to calculate them are described in Chapter 2.2, Chapter 3.4,
Chapter 3.7 and Appendix 1 of Metropolitan’s UWMP.
The demand and water use efficiency data shown in Table A.10-1 were collected from the
following sources:
x Baseline (2010) values – Metropolitan’s 2005 UWMP, Table 2-6: Metropolitan Regional
Water Demand Average Year
x 2015 values – Metropolitan’s 2010 UWMP, Table 2-8: Metropolitan Regional Water
Demands Average Year
x 2020 values – Metropolitan’s 2015 UWMP, Table 2-3: Metropolitan Regional Water
Demands Average Year
x 2025 values – Metropolitan’s 2020 UWMP, Table 2-3: Metropolitan Regional Water
Demands Normal Water Year
x 2030-2050 values – Metropolitan’s 2025 UWMP, Table 2-1: Metropolitan Regional
Water Demands Normal Water Year
Supplies Contributing to Regional Self-Reliance
For a covered action to demonstrate consistency with the Delta Plan, WR P1 subsection
(c)(1)(C) states that water suppliers must report the expected outcomes for measurable
improvement in regional self-reliance. Table A.10-2 shows expected outcomes for supplies
contributing to regional self-reliance both in amount and as a percentage. The numbers
shown in Table A.10-2 represent efforts to improve regional self-reliance for Metropolitan’s
entire service area and include the total contributions of Metropolitan and its members as
A.10-6 Metropolitan’s Reduced Delta Reliance Reporting
well as their customers. Supporting narratives and documentation for the all of the data
shown in Table A.10-2 are provided below.
The results shown in Table A.10-2 demonstrate that Metropolitan’s service area is
measurably improving its regional self-reliance. In the near-term (2030), the expected
outcome for normal water year regional self-reliance increases by 601 TAF from the 2010
baseline; this represents an increase of almost 20 percent of 2030 normal water year retail
demands. In the long-term (2050), normal water year regional self-reliance is expected to
increase by more than 1.0 MAF from the 2010 baseline; this represents an increase of
20 percent of 2050 normal water year retail demands.
Table A.10-2
Supplies Contributing to Regional Self-Reliance
Water Supplies Contributing to Regional Self-Reliance
(Acre-Feet)
Baseline
(2010) 2015 2020 2025 2030 2035 2040 2045 2050
Water Use Efficiency 865,000 936,000 1,056,000 1,162,000 1,171,000 1,223,000 1,289,000 1,357,000 1,419,000
Water Recycling 316,000 348,000 436,000 550,000 520,000 608,000 641,000 648,000 656,000
Stormwater Capture and Use 100,000 103,000 110,000 80,000 76,000 73,000 70,000 71,000 72,000
Advanced Water Technologies 111,000 101,000 194,000 194,000 200,000 215,000 218,000 220,000 222,000
Conjunctive Use Projects 1,416,000 1,429,000 1,303,000 1,255,000 1,222,000 1,239,000 1,244,000 1,243,000 1,242,000
Local and Regional Water Supply and Storage Projects 252,000 224,000
261,000
257,000
97,000
96,000
96,000
95,000
94,000
Other Programs and Projects that Contribute to Regional Self-Reliance 875,000 1,250,000 1,200,000 1,250,000 1,250,000 1,250,000 1,250,000 1,250,000 1,250,000
Water Supplies Contributing to Regional Self-Reliance
3,935,000
4,391,000
4,560,000
4,748,000
4,536,000
4,704,000
4,808,000
4,884,000
4,955,000
Service Area Demands without Water Use Efficiency
(Acre-Feet)
Baseline
(2010) 2015 2020 2025 2030 2035 2040 2045 2050
Service Area Demands without Water Use Efficiency Accounted For 5,493,000 5,499,000 5,219,000 4,925,000 4,969,000 5,102,000 5,209,000 5,302,000 5,391,000
Change in Regional Self Reliance
(Acre-Feet)
Baseline
(2010) 2015 2020 2025 2030 2035 2040 2045 2050
Water Supplies Contributing to Regional Self-Reliance 3,935,000 4,391,000 4,560,000 4,748,000 4,536,000 4,704,000 4,808,000 4,884,000 4,955,000
Change in Supplies Contributing to Regional Self-Reliance NA 456,000 625,000 813,000 601,000 769,000 873,000 949,000 1,020,000
Percent Change in Regional Self Reliance
(As Percent of Demand w/out WUE)
Baseline
(2010) 2015 2020 2025 2030 2035 2040 2045 2050
Percent of Supplies Contributing to Regional Self-Reliance 71.6% 79.9% 87.4% 96.4% 91.3% 92.2% 92.3% 92.1% 91.9%
Change in Percent of Supplies Contributing to Regional Self-Reliance NA 8.2% 15.7% 24.8% 0 20.6% 20.7% 20.5% 0
Water Use Efficiency
The water use efficiency information shown in Table A.10-2 is taken directly from
Table A.10-1 above.
Water Recycling
The water recycling values shown in Table A.10-2 reflect the total recycled water
production in Metropolitan’s service area as described in Chapter 3.5 and Appendix 2 of
Metropolitan’s UWMP.
Stormwater Capture and Use
The stormwater capture and use data shown in Table A.10-2 include supplies from local
surface water production as described in Chapter 1.4 and Appendix 2 of Metropolitan’s
UWMP.
These values do not include production from regional storage reservoirs; storage in these
reservoirs is comprised of previously stored water from sources already reflected in
Metropolitan’s Reduced Delta Reliance Reporting A.10-7
Tables A.10-2 and A.10-3. These regional storage resources are generally used to provide
additional regional self-reliance in dry years, which is not reflected in this normal water year
analysis. The regional storage reservoirs and their yields are described in Chapter 3.6,
Appendix 2 and Appendix 3 of Metropolitan’s UWMP.
The stormwater capture and use values shown in Table A.10-2 also do not include
stormwater capture that is used to recharge local groundwater basins. Stormwater capture
for groundwater recharge supports production of groundwater in the region, and for the
purposes of this analysis that production is already captured in Table A.10-2 under
conjunctive use projects.
Advanced Water Technologies
The advanced water technologies data shown in Table A.10-2 include total groundwater
recovery and seawater desalination production in Metropolitan’s service area as described
in Chapter 3.5 and Appendix 2 of Metropolitan’s UWMP.
Conjunctive Use Projects
The values for conjunctive use projects shown in Table A.10-2 represent total groundwater
production in the region as described in Chapter 1.4 and Appendix 2 of Metropolitan’s
UWMP.
The conjunctive use projects numbers shown in Table A.10-2 do not include production
from regional groundwater conjunctive use programs. As described in the stormwater
capture and use discussion above, these regional storage programs rely on previously
stored water from sources already reflected in Tables A.10-2 and A.10-3 and are generally
used to provide additional regional self-reliance in dry years. The regional groundwater
conjunctive use programs and their yields are described in Chapter 3.6 and Appendix 3.
Local and Regional Water Supply and Storage Programs
The data for local and regional water supply and storage programs shown in Table A.10-2
include supplies from the Los Angeles Aqueduct. This supply is described in Chapter 1.4
and Appendix 2 of Metropolitan’s UWMP.
The local and regional supply numbers shown in Table A.10-2, except for “Other Programs
and Projects that Contribute to Regional Self-Reliance” which is discussed below, were
obtained from the following sources:
x Baseline (2010) values – Metropolitan’s 2005 UWMP, Table 2-6: Metropolitan Regional
Water Demand Average Year
x 2015 values – Metropolitan’s 2010 UWMP, Table 2-8: Metropolitan Regional Water
Demands Average Year
x 2020 values – Metropolitan’s 2015 UWMP, Table 2-3: Metropolitan Regional Water
Demands Average Year
x 2025 values – Metropolitan’s 2020 UWMP, Table 2-3: Metropolitan Regional Water
Demands Normal Water Year
x 2030-2050 values – Metropolitan’s 2025 UWMP, Table 2-1: Metropolitan Regional
Water Demands Normal Water Year
A.10-8 Metropolitan’s Reduced Delta Reliance Reporting
Other Programs and Projects that Contribute to Regional Self-Reliance
Other programs and projects that contribute to regional self-reliance shown in Table A.10-2
include current programs from the Colorado River Aqueduct. Colorado River supplies
include Metropolitan’s basic Colorado River apportionment, as well as supplies that result
from existing and committed programs, including those from the IID-MWD Conservation
Program, the implementation of the Quantification Settlement Agreement (QSA), related
agreements, and the exchange agreement with SDCWA. Colorado River Aqueduct
supplies and programs are described in Chapter 3.1 and Appendix 3 of Metropolitan’s
UWMP.
The values shown in Table A.10-2 for other programs and projects that contribute to
regional self-reliance come from the following sources:
x Baseline (2010) values – Metropolitan’s 2005 UWMP, Table A.3-7: Maximum Expected
Colorado River Aqueduct Deliveries Year 2010 (Average Year)
x 2015 values – Metropolitan’s 2010 UWMP, Table A.3-7: Maximum Expected Colorado
River Aqueduct Deliveries Year 2015 (Average Year)
x 2020 values – Metropolitan's 2015 UWMP, Table A.3-7: Maximum Expected Colorado
River Aqueduct Deliveries Year 2020 (Average Year)
x 2025 values – Metropolitan’s 2020 UWMP, Table A.3-7: Maximum Expected Colorado
River Aqueduct Deliveries Year 2025 (Normal Water Year)
x 2030-2050 values – Metropolitan’s 2025 UWMP, Table A.3-7: Maximum Expected
Colorado River Aqueduct Deliveries Years 2030, 2035, 2040, 2045, 2050 (Normal
Water Year)
Reliance on Water Supplies from the Delta Watershed
In order for a covered action to demonstrate consistency with the Delta Plan, WR P1
subsection (c)(1)(C) requires that water suppliers report the expected outcomes for
measurable reductions in supplies from the Delta watershed either as an amount or as a
percentage. This analysis provides both calculations. Based on the methodology described
in Guidebook Appendix C, and consistent with the approach of this analysis in not including
projects under development, this accounting does not include any supplies from potential
future covered actions. Table A.10-3 shows the expected outcomes for reliance on supplies
from the Delta watershed for Metropolitan’s service area. Supporting narratives and
documentation for the all of the data shown in Table A.10-3 are provided below.
The results shown in Table A.10-3 demonstrate that Metropolitan’s service area is
measurably reducing its Delta reliance. In the near-term (2030), the expected outcome for
normal water year reliance on supplies from the Delta watershed decreased by 466 TAF
from the 2010 baseline; this represents a decrease of 6 percent of 2030 normal water year
retail demands. In the long-term (2050), normal water year reliance on supplies from the
Delta watershed decreased by 537 TAF from the 2010 baseline; this represents a decrease
of just over 9 percent of 2050 normal water year retail demands.
Metropolitan’s Reduced Delta Reliance Reporting A.10-9
Table A.10-3
Reliance on Water Supplies from the Delta Watershed
CVP/SWP Contract Supplies
The CVP/SWP contract supplies shown in Table A.10-3 include Metropolitan’s SWP Table
A and Article 21 supplies. These supplies are described in Chapter 3.2 and Appendix 3 of
Metropolitan’s UWMP.
The values shown in Table A.10-3 do not include Desert Water Agency/Coachella Valley
Water District SWP contract supplies. These supplies are exchanged with Desert Water
Agency and Coachella Valley Water District for an equal amount of Colorado River water,
which is reflected in the Colorado River Aqueduct supplies shown in Table A.10-2. In
addition, Desert Water Agency and Coachella Valley Water District should include their
SWP contract supplies in their own accountings of reduced reliance. Additional information
on these exchange agreements can be found in Chapter 3.2 and Appendix 3 of
Metropolitan’s UWMP.
These values also do not include supplies from San Luis Carryover storage or Central
Valley storage programs because storage in these programs comprises previously stored
water from sources already reflected in Table A.10-3. These storage programs are
generally used to provide additional regional self-reliance in dry years, which is not
reflected in this normal water year analysis. The Central Valley storage projects and their
yields are described in Chapter 3.3, and Appendix 3. San Luis Carryover storage is
described in Chapter 3.2 and Appendix 3.
Transfers and Exchanges of Supplies from the Delta Watershed
The transfers and exchanges of supplies from the Delta watershed shown in Table A.10-3
include supplies from the San Bernardino Valley MWD Program, Yuba River Accord
Purchase Program, the San Gabriel Valley MWD Program, Irvine Ranch Water District
Storage and Exchange Program, and other generic SWP and Central Valley transfers and
exchanges. These programs are described in Chapter 3.2 and Appendix 3 of Metropolitan’s
UWMP.
Water Supplies from the Delta Watershed
(Acre-Feet)
Baseline
(2010)2015 2020 2025 2030 2035 2040 2045 2050
CVP/SWP Contract Supplies 1,472,000 1,029,000 984,000 1,133,000 949,000 924,000 901,000 877,000 877,000
Delta/Delta Tributary Diversions - - - - - - - - -
Transfers and Exchanges of Supplies from the Delta Watershed 20,000 44,000 91,000 58,000 77,000 77,000 78,000 78,000 78,000
Other Water Supplies from the Delta Watershed - - - - - - - - -
Total Water Supplies from the Delta Watershed 1,492,000 1,073,000 1,075,000 1,191,000 1,026,000 1,001,000 979,000 955,000 955,000
Service Area Demands without Water Use Efficiency
(Acre-Feet)
Baseline
(2010)2015 2020 2025 2030 2035 2040 2045 2050
Service Area Demands without Water Use Efficiency Accounted For 5,493,000 5,499,000 5,219,000 4,925,000 4,969,000 5,102,000 5,209,000 5,302,000 5,391,000
Change in Supplies from the Delta Watershed
(Acre-Feet)
Baseline
(2010)2015 2020 2025 2030 2035 2040 2045 2050
Water Supplies from the Delta Watershed 1,492,000 1,073,000 1,075,000 1,191,000 1,026,000 1,001,000 979,000 955,000 955,000
Change in Supplies from the Delta Watershed NA (419,000) (417,000) (301,000) (466,000) (491,000) (513,000) (537,000) (537,000)
Percent Change in Supplies from the Delta Watershed
(As a Percent of Demand w/out WUE)
Baseline
(2010)2015 2020 2025 2030 2035 2040 2045 2050
Percent of Supplies from the Delta Watershed 27.2% 19.5% 20.6% 24.2% 20.6% 19.6% 18.8% 18.0% 17.7%
Change in Percent of Supplies from the Delta Watershed NA -7.6% -6.6% -3.0% -6.5% -7.5% -8.4% -9.1% -9.4%
A.10-10 Metropolitan’s Reduced Delta Reliance Reporting
Supplies from the Delta Watershed shown in Table A.10-3 are from the following sources:
x Baseline (2010) values – Metropolitan’s 2005 UWMP, Table A.3-7: California Aqueduct
Program Capabilities Year 2010 (Average Year)
x 2015 values – Metropolitan’s 2010 UWMP, Table A.3-7: California Aqueduct Program
Capabilities Year 2015 (Average Year)
x 2020 values – Metropolitan’s 2015 UWMP, Table A.3-7: California Aqueduct Program
Capabilities Year 2020 (Average Year)
x 2025 values – Metropolitan’s 2020 UWMP, Table A.3-7: California Aqueduct Program
Capabilities Year 2025 (Normal Water Year)
x 2030-2050 values – Metropolitan’s 2025 UWMP, Table A.3-7: California Aqueduct
Program Capabilities Years 2030, 2035, 2040, 2045, 2050 (Normal Water Year)
A.10.4 UWMP Implementation
In addition to the analysis and documentation described above, WR P1 subsection (c)(1)(B)
requires that all programs and projects included in the UWMP that are locally cost-effective
and technically feasible, which reduce reliance on the Delta, are identified, evaluated, and
implemented consistent with the implementation schedule. WR P1 (c)(1)(B) states that:
(B) Identified, evaluated, and commenced implementation, consistent with the
implementation schedule set forth in the Plan, of all programs and projects included
in the Plan that are locally cost effective and technically feasible which reduce
reliance on the Delta[.]
In accordance with Water Code Chapter 10631(f), water suppliers must already include in
their UWMP a detailed description of expected future projects and programs that they may
implement to increase the amount of water supply available to them in normal and single-
dry water years and for a period of drought lasting five consecutive years. The UWMP
description must also identify specific projects, include a description of the increase in
water supply that is expected to be available from each project, and include an estimate
regarding the implementation timeline for each project or program.
Chapter 3 of Metropolitan’s UWMP summarizes the implementation plan and continued
progress in developing a diversified water portfolio to meet the region’s water needs.
Water Use Efficiency
The water use efficiency numbers used in this analysis include the total water use
efficiency savings (conservation) for the service area, including savings from active, code-
based, price-effect and pre-1990 savings. The specific water use efficiency programs and
their implementation are described in Chapter 3.4 of Metropolitan’s UWMP.
Water Recycling
The water recycling values used in this analysis reflect the total recycled water production
in Metropolitan’s service area. Water recycling programs and implementation are discussed
in Chapter 3.5 of Metropolitan’s UWMP. In addition, individual project-level details are
provided in Appendix 5.
Metropolitan’s Reduced Delta Reliance Reporting A.10-11
Stormwater Capture and Use
The stormwater capture and use data used in this analysis include supplies from local
surface water production. Local surface water production and its implementation are
discussed in Appendix 2 of Metropolitan’s UWMP.
Advanced Water Technologies
The advanced water technologies data used in this analysis include total groundwater
recovery and seawater desalination production in Metropolitan’s service. Groundwater
recovery and seawater desalination programs and implementation are described in
Chapter 3.5 of Metropolitan’s UWMP. In addition, individual project-level details are
provided in Appendix 5.
Conjunctive Use Projects
The values for conjunctive use projects used in this analysis represent total groundwater
production in the region. Groundwater production and its implementation are discussed in
Appendix 2 of Metropolitan’s UWMP.
Local and Regional Water Supply and Storage Programs
The data for local and regional water supply and storage programs shown in this analysis
include supplies from the Los Angeles Aqueduct. This program and its implementation are
described in Appendix 2 of Metropolitan’s UWMP.
Other Programs and Projects that Contribute to Regional Self-Reliance
Other programs and projects that contribute to regional self-reliance used in this analysis
include current programs from the Colorado River Aqueduct. Colorado River supplies
include Metropolitan’s basic Colorado River apportionment, as well as supplies that result
from existing and committed programs, including those from the IID-MWD Conservation
Program, the implementation of the Quantification Settlement Agreement (QSA), related
agreements, and the exchange agreement with SDCWA. Colorado River Aqueduct
programs and their implementation are described in Chapter 3.1 and Appendix 3 of
Metropolitan’s UWMP.
CVP/SWP Contract Supplies
The CVP/SWP contract supplies shown in this analysis include Metropolitan’s SWP Table
A and Article 21 supplies. These supplies and their implementation are described in
Chapter 3.2 and Appendix 3 of Metropolitan’s UWMP.
Transfers and Exchanges of Supplies from the Delta Watershed
The transfers and exchanges of supplies from the Delta watershed shown in this analysis
include supplies from the San Bernardino Valley MWD Program, Yuba River Accord
Purchase Program, the San Gabriel Valley MWD Program, Irvine Ranch Water District
Storage and Exchange Program, and other generic SWP and Central Valley transfers and
exchanges. These programs and their implementation are described in Chapter 3.2 and
Appendix 3 of Metropolitan’s UWMP.
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX D
NOTIFICATION LETTERS AND NOTICES OF PUBLIC
HEARING
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX E
CLIMATE CHANGE CONSIDERATIONS (CAL- ADAPT
DATA)
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX F
LONG BEACH JUDGMENT
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX G
MAIN BASIN JUDGMENT
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX H
RAYMOND BASIN ADJUDICATION
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX I
DRAFT RECYCLED WATER FEASIBILITY STUDY
DRAFT
City of Arcadia
Recycled Water Feasibility Study
November 2006
November 29, 2004
Prepared for:
City of Arcadia
Stetson Engineers Inc.
861 Village Oaks Drive, Covina, California 91724
Phone:(626) 967-6202, Fax: (626) 331-7065
Covina, CA San Rafael, CA Mesa, AZ
Recycled Water Deamnd /2
Demand No. Customer Name Address
1 Arcadia High 180 Campus Dr. 46 27 0.025 0.061 0.184 128
2 Baldwin Stocker Elementary 422 W Lemon Ave. 5 3 0.003 0.007 0.020 14
3 Camino Grove School 700 Camino Grove 6 3 0.003 0.008 0.023 16
4 Dana Middle School 1401 S. First Ave. 9 6 0.005 0.012 0.037 26
5 First Ave Middle School 301 S. First Ave. 12 7 0.006 0.015 0.046 32
6 Foothills Middle School 171 E. Sycamore Ave. 5 3 0.003 0.007 0.020 14
7 Highland Oaks Elementary 10 Virginia Dr. 3 2 0.002 0.005 0.014 10
8 Holly Ave Elementary 360 W. Duarte Rd. 14 8 0.008 0.019 0.057 39
9 Hugo Reid Elementary 1000 Hugo Reid Dr. 1 1 0.001 0.001 0.004 3
10 Hugo Reid Primary 1000 Hugo Reid Dr. 4 2 0.002 0.005 0.015 10
11 Longley Way Elementary 2601 S. Longley Wy. 7 4 0.004 0.010 0.029 20
12 Rancho High/Serendipity School 120 - 150 S. Third Ave. 5 3 0.002 0.006 0.018 13
13 Holly Angels School Campus Dr. & Holly Ave. 2 1 0.001 0.002 0.007 5
14 Serendipity School (Part of No. 12) 120 - 150 S. Third Ave. 0 0 0.000 0.000 0.000 0
15 Santa Anita Golf Course 405 S. Santa Anita Ave. 156 109 0.097 0.243 0.730 507
16 Santa Anita Park (Race Track) 285 W. Huntington Dr. 162 121 0.108 0.271 0.812 564
17 LA County & State Arboretum S. Baldwin Ave. 93 79 0.070 0.176 0.528 367
18 Arcadia County Park 78 W Huntington Dr. 125 106 0.095 0.237 0.712 495
19 Baldwin Stocker Park 422 W. Lemon Ave. 5 5 0.004 0.010 0.031 22
20 Bicentennial Park 526 E. Longden Ave. 1 1 0.001 0.003 0.008 6
21 Bonita Park 207 Bonita St. 0 0 0.000 0.000 0.001 0
22 Camino Grove Park 1420 S. Sixth Ave. 2 2 0.002 0.004 0.012 8
23 Civic Center Athletic Field 240 W. Huntington Dr. 8 7 0.006 0.016 0.048 33
24 Eisenhower Memorial Park 601 N. Second Ave. 20 17 0.015 0.037 0.112 78
25 Fairview Avenue Park 542 Fairview Ave. 3 3 0.002 0.006 0.018 12
26 Forest Avenue Park 132 W. Forest Ave. 1 1 0.001 0.003 0.008 6
27 Highland Oaks Park 10 W. Virginia Rd. 6 5 0.004 0.011 0.032 22
28 Hugo Reid Park 1153 De Anza Pl. 10 9 0.008 0.019 0.057 40
29 Longden Avenue Park 1179 E. Longden Ave. 0 0 0.000 0.000 0.000 0
30 Newcastle Park 143 W. Colorado Blvd. 8 7 0.006 0.016 0.047 33
31 Orange Grove Park 670 W. Orange Grove Ave. 0 0 0.000 0.001 0.002 1
32 Par-3 Golf Course 620 E. Live Oak Ave. 44 31 0.028 0.069 0.207 144
33 Tierra Verde Park 200 E. Camino Real Ave. 7 6 0.006 0.014 0.042 29
34 Tripolis Friendship Park 1003 S. Golden West Ave. 3 2 0.002 0.005 0.015 11
35 Wilderness Park 2240 N. Highland Oaks Dr. 8 7 0.006 0.016 0.047 33
36 Santa Anita Median 105 N Santa Anita Ave. 47 47 0.042 0.104 0.313 218
37 Baldwin Median 460 N Baldwin Ave. 15 15 0.013 0.033 0.098 68
38 Hungtington Median 32 E Huntington Dr. 17 17 0.015 0.038 0.115 80
39 Live Oak Median 43 E Live Oak Ave. 5 5 0.005 0.011 0.034 24
40 Fashing Car Wash 425 N Santa Anita Ave. 37 24 0.021 0.053 0.160 111
41 Calco Farms 11921 Goldring Rd. 15 12 0.011 0.028 0.084 58
42 Caltrans 223 N Fifth Avenue 4 4 0.003 0.009 0.026 18
43 Caltrans 4 E Forest Ave 12 12 0.011 0.027 0.082 57
44 Caltrans 170 W Forest Ave 7 7 0.007 0.017 0.050 35
45 Caltrans 900 N Michillinda Ave 1 1 0.001 0.001 0.004 3
46 Caltrans 1015 N Old Ranch Road 1 1 0.001 0.003 0.010 7
47 Caltrans 1009 San Carlos Road 5 5 0.005 0.012 0.036 25
Total 948 740 0.661 1.652 4.956 3,442
Hi-Lited Totals (Customers Along Proposed Recycled Water Pipeline Route)644 0.575 1.438 4.315 2,996
/1 Values shown are actual metered usage Jan. 1999 and Jan. 2004. Supplied by City Of Arcadia staff.
/2 Demand Reduction Factors: Schools 40%, Golf Courses 30%, Parks 15%, Arboretum 15%, Race Track 25%, Car Wash 35%, and Calco Farms 15%. Medians and
Caltrans not reduced. Maximum Day Demand = 2.5 X Average Day Demand. Maximum Peak Hour Demand = 3 X Maximum Day Demand
Water Demand /1 (AFY)Annual Average (AFY)
Proposed Recycled Water Users Within City Of Arcadia
Average Day (MGD)
Max Day Demand
(MGD)
Max Peak Hour
Demand (MGD)
Max Peak Hour
Demand (GPM)
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX J
WATER CONSERVATION PLAN
Footnotes:
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CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX K
CITY OF ARCADIA LOCAL HAZARD MITIGATION
PLAN
City of Arcadia
Local Hazard
Mitigation Plan
May 11, 2022
City of Arcadia
Local Hazard Mitigation Plan 2022
Table of Contents
Introduction
Section 1 - Executive Summary 1-1
Section 2 - Resolution adoption by Council 2-1
Section 3 - FEMA Crosswalk & Approval Letter 3-1
Section 4 - Community Profile 4-1
Section 5 - Planning Process 5-1
Section 6 - Risk Assessment 6-1
Section 7 Natural Hazards 7
Section 7.1 - Earthquake 7.1
Section 7.2 - Flood 7.2
Section 7.3 Slope Failure Debris/Mud Flow 7.3
Section 7.4 - Windstorm 7.4
Section 7.5 - Wildfire 7.5
Section 7.6 - Drought 7.6
Section 8 - Human Caused Hazards 8
Section 8.1 - Hazardous Materials 8.1
Section 8.2 - Terrorism 8.2
Section 8.3 Train Accident 8.3
Section 9 - Mitigation Strategy 9-1
Section 10 - Plan Maintenance 10-1
Appendix
Appendix A - Economic Analysis A-1
Appendix B - Acronyms B-1
Local Hazard Mitigation Plan 2022
Section 1 Executive Summary
1-1
Five -Year Action Plan Matrix
The City of Arcadia Local Hazards Mitigation Action Plan includes resources and
information to assist City residents, public and private sector organizations, and others
interested in participating in planning for local hazards. The mitigation plan provides a
list of activities that may assist City of Arcadia in reducing risk and preventing loss from
future hazardous events. The action items address multi-hazard issues, as well as
activities for earthquakes, flooding, debris flow / Slope Failures, windstorms, wildfires,
drought, hazardous materials, transportation emergencies and terrorism
How is the Plan Organized?
The Mitigation Plan contains a five-year action plan matrix, background on the purpose
and methodology used to develop the mitigation plan, a profile of City of Arcadia,
sections on hazards that occur within the City, and a number of appendices.
Who Participated in Developing the Plan?
The City of Arcadia Local Hazard Mitigation Action Plan is the result of a collaborative
, public agencies, non-profit organizations, the
private sector, and regional and state organizations. Public participation played a key
role in development of goals and action items. A meeting was held with stakeholders in
the City, and two public meetings
development. A Hazard Mitigation Committee guided the process of developing the
plan.
What is the Plan Mission?
The mission of the City of Arcadia Local Hazard Mitigation Plan is to promote sound
public policy designed to protect citizens, critical facilities, infrastructure, private
property, and the environment from potential hazards. This can be achieved by
increasing public awareness, documenting the resources for risk reduction and loss-
prevention, and identifying activities to guide the City towards building a safer, more
sustainable community.
What are the Plan Goals?
organizations, and citizens can take to work toward mitigating risk from hazards. The
goals are stepping-stones between the broad direction of the mission statement and the
specific recommendations outlined in the action items.
Protect Life and Property
Implement activities that assist in protecting lives by making homes, businesses,
infrastructure, critical facilities, and other property more resistant to losses from
natural hazards.
Reduce losses and repetitive damages for chronic hazard events while promoting
insurance coverage for catastrophic hazards.
Improve hazard assessment information to make recommendations for
discouraging new development in high hazard areas and encouraging preventative
measures for existing development in areas vulnerable to hazards.
Local Hazard Mitigation Plan 2022
Section 1 Executive Summary
1-2
Public Awareness
Develop and implement education and outreach programs to increase public
awareness of the risks associated with natural hazards.
Provide information on tools; partnership opportunities, and funding resources to
assist in implementing mitigation activities.
Natural Systems
Balance natural resource management, and land use planning with local hazard
mitigation to protect life, property, and the environment.
Preserve, rehabilitate, and enhance natural systems to serve local hazard
mitigation functions.
Partnerships and Implementation
Strengthen communication and coordinate participation among and within public
agencies, citizens, non-profit organizations, business, and industry to gain a
vested interest in implementation.
Encourage leadership within public and private sector organizations to prioritize
and implement local and regional hazard mitigation activities.
Emergency Services
Establish policy to ensure mitigation projects for critical facilities, services, and
infrastructure.
Strengthen emergency operations by increasing collaboration and coordination
among public agencies, non-profit organizations, business, and industry.
Coordinate and integrate hazard mitigation activities, where appropriate, with
emergency operations plans and procedures.
How are the Action Items Organized?
The action items are a listing of activities in which City agencies and citizens can be
engaged in to reduce risk. The action items are organized within the following matrix,
which lists all of the multi-hazard and hazard-specific action items included in the
mitigation plan. Data collection, research, and the public participation process resulted in
the development of these action items (see Section 9). The matrix includes the following
information for each action item:
Coordinating Organization
The coordinating organization is the public agency with regulatory responsibility
to address hazards, or that is willing and able to organize resources, find
appropriate funding, or oversee activity implementation, monitoring, and
evaluation. Coordinating organizations may include local, county, or regional
agencies that are capable of or responsible for implementing activities and
programs.
Time line
Action items include both short and long-term activities. Each action item
Local Hazard Mitigation Plan 2022
Section 1 Executive Summary
1-3
includes an estimate of the time line for implementation. Short-term action items
are activities which City agencies are capable of implementing with existing
resources and authorities within one to two years. Long-term action items may
require new or additional resources or authorities, and may take between one and
five years (or more) to implement.
Ideas for Implementation
Each action item includes ideas for implementation and potential resources, which
may include grant programs or human resources.
Plan Goals Addressed
The plan goals addressed by each action item are included as a way to monitor
and evaluate how well the mitigation plan is achieving its goals once
implementation begins. The plan goals are organized into the following five
areas:
1. Protect Life and Property
2. Public Awareness
3. Natural Systems
4. Partnerships and Implementation
5. Emergency Services
Constraints
Constraints may apply to some of the action items. These constraints may be a
lack of city staff, lack of funds, or vested property rights, which might expose the
City to legal action as a result of adverse impacts on private property.
How Will the Plan be Implemented, Monitored, and Evaluated?
The Plan Maintenance Section of this document details the formal process that will
Local Hazards Mitigation Plan remains an active and
relevant document. The plan maintenance process includes a schedule for monitoring
and evaluating the Plan annually and producing a plan revision every five years. This
section describes how the City will integrate public participation throughout the plan
maintenance process. Finally, this section includes an explanation of how the City of
Improvement Plans, and Building & Safety Codes.
Plan Adoption
Adopti
body is one of the prime requirements for approval of the plan. Once the plan is
reviewed Local
Hazard Mitigation Plan. The local agency governing body has the responsibility and
authority to promote sound public policy regarding hazards. The City Council will
periodically need to re-adopt the plan as it is revised to meet changes in the hazard risks
and exposures in the community. The approved Local Hazard Mitigation Plan will be
significant in the future growth and development of the community.
Local Hazard Mitigation Plan 2022
Section 1 Executive Summary
1-4
Coordinating Body
The
coordinating implementation of Plan action items and undertaking the formal review
process. The City Manager will assign representatives to the Hazard Mitigation
Committee and assign a Project Manager.
Convener
Local Hazard Mitigation Plan, and the
Hazard Mitigation Committee will take responsibility for plan implementation. The
Project Manager will serve as a convener to facilitate the Hazard Mitigation Committee
meetings, and will assign tasks such as updating and presenting the Plan to the members
of the committee. Plan implementation and evaluation will be a shared responsibility
among all of the Local Hazard Committee Members.
Implementation through Existing Programs
The City of Arcadia addresses statewide planning goals and legislative requirements
through its General Plan, Capital Improvement Plans, Fire Codes, City Building & Safety
Codes and other related documents. The Local Hazard Mitigation Plan provides a series
of recommendations that are closely related to the goals and objectives of these existing
planning programs. City of Arcadia will have the opportunity to implement
recommended mitigation action items through existing programs and procedures.
Economic Analysis of Mitigation Projects
The Federal Emergency Management Agency's approaches to identify costs and benefits
associated with hazard mitigation strategies or projects fall into two general categories:
benefit/cost analysis and cost-effectiveness analysis. Conducting benefit/cost analysis for
a mitigation activity can assist communities in determining whether a project is worth
undertaking now, in order to avoid disaster-related damages later. Cost-effectiveness
analysis evaluates how best to spend a given amount of money to achieve a specific goal.
Determining the economic feasibility of mitigating hazards can provide decision makers
with an understanding of the potential benefits and costs of an activity, as well as a basis
upon which to compare alternative projects.
Formal Review Process
Local Hazard Mitigation Plan will be evaluated on an annual basis
to determine the effectiveness of programs, and to reflect changes in land development or
programs that may affect mitigation priorities. The evaluation process includes a firm
schedule and time line, and identifies the local agencies and organizations participating in
plan evaluation. The Project Manager or designee will be responsible for contacting the
Hazard Mitigation Committee members and organizing the annual meeting. Committee
members will be responsible for monitoring and evaluating the progress of the mitigation
strategies in the Plan.
Local Hazard Mitigation Plan 2022
Section 1 Executive Summary
1-5
Continued Public Involvement
The City of Arcadia is dedicated to involving the public directly in the continual review
and updates of the Hazard Mitigation Plan. Copies of the plan will be catalogued and
. The
existence and location of these copies will be publicized in City newsletters. In addition,
locations of the Plan and any proposed changes will be posted on the City website. This
site will also contain an email address and phone number to which people can direct their
comments and concerns.
Changes to Priorities
The City of Arcadia updated its Local Hazard Mitigation Plan in 2012. There have been
no changes in priorities since the adoption of the plan.
Local Hazard Mitigation Plan 2022
Section 2 Resolution Adoption by Council
2-1
On May 3, 2022 this plan was adopted by the Arcadia City Council. The staff
report and Resolution are included in this section.
DATE: May 3, 2022
TO:Honorable Mayor and City Council
FROM:Barry R. Spriggs, Fire Chief
By: Chen Suen, Deputy Fire Chief
Maria Lourdes A. Taylor, Sr. Management Analyst
SUBJECT:RESOLUTION NO. 7429 APPROVING THE CITY OF ARCADIA LOCAL
HAZARD MITIGATION PLAN
Recommendation: Adopt
SUMMARY
Local governments are required to have an approved Local Hazard Mitigation Plan in
place to receive pre-disaster and post-disaster mitigation federal funding. The City has
updated its Plan to address modern threats to the community and to adhere to federal
standards and guidelines. Therefore, it is recommended that the City Council adopt
Resolution No. 7429, approving the City of Arcadia’s Local Hazard Mitigation Plan, prior
to its submittal to the Federal Emergency Management Agency (“FEMA”) for final
approval.
BACKGROUND
The Disaster Mitigation Act of 2000 was a law enacted by the federal government that
places emphasis on hazard mitigation planning for local municipalities. The law requires
local governments to develop and adopt a Local Hazard Mitigation Plan (“LHMP”) with
final approval given by FEMA. An LHMP is a document that identifies potential natural
and human-caused disasters specific to a community and contains information to assist
the community, its residents, and other interested parties to plan for local hazards.
Essentially, FEMA requires a local government to update their LHMP every five years.
The City of Arcadia’s previous LHMP was adopted in 2013. For this most recent LHMP
update, City staff began working with FEMA in 2017 with the final draft subsequently
approved by FEMA in April 2022.
On April 5, 2022, after completing its review of the LHMP, FEMA advised staff that the
plan was eligible for final approval pending its adoption by the City. Upon City Council’s
approval of the LHMP, formal adoption documentation will be forwarded to FEMA to
satisfy the final requirement of the review process.
Adopt Resolution 7429
Arcadia Local Hazard Mitigation Plan 2022
May 3, 2022
Page 2 of 4
DISCUSSION
After a disaster strikes, repair and construction efforts are often undertaken to restore
infrastructure to pre-disaster conditions. Although such efforts expedite a return to normal
functioning, the replications of pre-disaster conditions could result in a cycle of damage,
reconstruction, and repeated damage. Hazard mitigation planning ensures such cycles
are broken and that post-disaster repairs and reconstruction result in vulnerability
reduction.
While disasters may be unpreventable, the devasting effects may be reduced or
eliminated through well-organized public education and awareness efforts, preparedness,
and mitigation. For those hazards that cannot be fully mitigated, the community must be
prepared to provide efficient and effective response and recovery services.
The mission of the LHMP is to promote sound public policy designed to protect residents,
critical facilities, infrastructure, private property, and the environment from natural and
human caused hazards. This mission will be achieved by increasing public awareness,
documenting resources for risk reduction and loss prevention, and identifying activities
that will guide the City toward building a safer, more sustainable community.
The document was prepared through a concerted and collaborative effort of City
departments, citizens in the community, and major stakeholders in the region. All City
departments met regularly, coordinated resources, and compiled information required for
the document. Public workshops were held to gather ideas and opinions on community
mitigation goals and activities. In addition, a stakeholder meeting was conducted, which
was attended by emergency service coordinators within the region, representatives from
the Arcadia Unified School District, American Red Cross, Santa Anita Racetrack, civic
groups, and the Arcadia Chamber of Commerce.
The end-product is a comprehensive City of Arcadia Local Hazard Mitigation Plan. Over
100 pages in length, excluding appendices and maps, the document reviews action items
from the previous LHMP and evaluates if those goals have been met. It also discusses
in detail nine (9) possible natural and human-caused hazards that could impact the City,
which include the following:
1) Earthquake
2) Flood
3) Slope Failure Debris/Mud Flow
4) Windstorm
5) Wildfire
6) Drought
7) Hazardous Materials
8) Terrorism
Adopt Resolution 7429
Arcadia Local Hazard Mitigation Plan 2022
May 3, 2022
Page 3 of 4
9) Train Accident
The LHMP includes a description, risk analysis, and mitigation strategies for each hazard.
For example, the earthquake section of the document discusses: the definition of an
earthquake; earthquakes in Southern California and in Arcadia; earthquake hazard
assessment and a list of the nearby fault lines that affect Arcadia; risk analysis of the
probability of an earthquake with a magnitude of 5.0 or greater occurring in the next five
(5), 10, 20, and 50 years; the City’s current mitigation of earthquake hazards; and a
resource directory pertaining to earthquake preparedness and mitigation. Other sections
follow similar patterns.
The adoption of Resolution No. 7429 by the City Council is the final requirement in the
plan approval process. The document has already been approved by the California Office
of Emergency Services (“Cal-OES”). Additionally, the document has been approved by
FEMA, pending the formal adoption by the City Council. Upon City Council’s adoption,
the document will be available for public review in the City Manager’s Office, City Clerk’s
Office, and the Arcadia Public Library. A copy will also reside on the City’s website.
ENVIRONMENTAL IMPACT
The LHMP is subject to a statutory exemption pursuant to Section 15252 of the California
Environmental Quality Act guidelines because it is a feasibility and planning study.
Additionally, the document is consistent with the City’s General Plan in implementing
certain Public Safety Element goals, objectives, and policies outlined in Resolution No.
7429.
FISCAL IMPACT
Adoption of Resolution No. 7429 has no direct fiscal impact to the City. Arcadia will have
the opportunity to implement recommended mitigation action items through existing
programs and procedures.
Failure to adopt an LHMP will forfeit the City’s eligibility to receive federal funding for both
pre-disaster and post-disaster mitigation projects.
RECOMMENDATION
It is recommended that the City Council adopt Resolution No. 7429 approving the City
of Arcadia’s Local Hazard Mitigation Plan.
Adopt Resolution 7429
Arcadia Local Hazard Mitigation Plan 2022
May 3, 2022
Page 4 of 4
Attachments: Resolution 7429
City of Arcadia Local Hazard Mitigation Plan
3
STATE OF CALIFORNIA )
COUNTY OF LOS ANGELES ) SS:
CITY OF ARCADIA )
I, GENE GLASCO, City Clerk of the City of Arcadia, hereby certifies that the
foregoing Resolution No. 742 was passed and adopted by the City Council of the City of
Arcadia, signed by the Mayor and attested to by the City Clerk at a regular meeting of said
Council held on the 3rd of May, 2022 and that said Resolution was adopted by the following
vote, to wit:
AYES: Danielson, Tay, Verlato, Cheng, and Beck
NOES: None
ABSENT: None
_________________________
City Clerk of the City of Arcadia
Local Hazard Mitigation Plan 2022
Section 3 FEMA Crosswalk and Approval Letter
3-1
On May 11, 2022, this plan was approved by FEMA. The approval letter and
crosswalk are included in this section.
U.S. Department of Homeland Security
FEMA Region 9
1111 Broadway, Suite 1200
Oakland, CA 94607
www.fema.gov
May , 2022
Barry Spriggs
Fire Chief
Arcadia Fire Department
710 S. Santa Anita Ave.
Arcadia, CA 91006
Dear Chief Spriggs:
The City of Arcadia Local Hazard Mitigation Plan 2022 was officially adopted by the City of
Arcadia on May 3, 2022 and submitted for review and approval to the Federal Emergency
Management Agency (FEMA). The review is complete, and FEMA finds the plan to be in
conformance with the Code of Federal Regulations, Title 44, Part 201, Section 6 (44 C.F.R.
201.6).
This plan approval ensures the City of Arcadia’s continued eligibility for funding under FEMA’s
Hazard Mitigation Assistance programs, including the Hazard Mitigation Grant Program
(HMGP), the Building Resilient Infrastructure and Communities program (BRIC), and the Flood
Mitigation Assistance (FMA) program. All requests for funding are evaluated individually
according to eligibility and other program requirements. Approved hazard mitigation plans may
also be eligible for points under the National Flood Insurance Program’s Community Rating
System (CRS).
FEMA’s approval is for a period of five years, effective starting the date of this letter. Prior to
May , 2027, the City of Arcadia must review, revise, and submit their plan to FEMA for
approval to maintain eligibility for grant funding. The enclosed plan review tool provides
additional recommendations to incorporate into future plan updates.
If you have any questions regarding the planning or review processes, please contact the FEMA
Region 9 Hazard Mitigation Planning Team at fema-r9-mitigation-planning@fema.dhs.gov.
Sincerely,
Kathryn Lipiecki
Director, Mitigation Division
FEMA Region 9
Enclosure (1)
City of Arcadia Plan Review Tool, dated May , 2022
www.fema.gov
City of Arcadia Hazard Mitigation Plan Approval Notice
May , 2022
Page 2 of 2
cc: Alison Kearns, Planning and Implementation Branch Chief, FEMA Region 9
Jennifer Hogan, State Hazard Mitigation Officer, California Governor’s Office of
Emergency Services
Victoria LaMar-Haas, Hazard Mitigation Planning Chief, California Governor’s Office of
Emergency Services
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 1
REGION IX LOCAL HAZARD MITIGATION PLAN REVIEW TOOL
Last Updated: April 12, 2021
The Local Hazard Mitigation Plan Review Tool demonstrates how the Local Hazard Mitigation Plan meets
the regulation in 44 CFR §201.6 and offers State and FEMA Mitigation Planners an opportunity to
provide feedback to the community.
• The Regulation Checklist provides a summary of FEMA’s evaluation of whether the plan has
addressed all requirements.
• The Plan Assessment identifies the plan’s strengths as well as documents areas for future
improvement. This section also includes a list of resources for implementation of the plan.
• The Multi-Jurisdiction Summary Sheet is a mandatory worksheet for multi-jurisdictional plans
that is used to document which jurisdictions are eligible to adopt the plan.
• The Hazard Identification and Risk Assessment Matrix is a tool for plan reviewers to identify if
all components of Element B are met.
Jurisdiction:
City of Arcadia, California
Title of Plan:
City of Arcadia Local Hazard Mitigation
Plan
Date of Plan:
December 31, 2019
Local Point of Contact:
Barry Spriggs
Address:
710 S. Santa Anita Ave.
Arcadia, CA 91006
Title:
Fire Chief
Agency:
Arcadia Fire Department
Phone Number:
626 574 5107
E-Mail:
bspriggs@ArcadiaCA.gov
State Reviewer(s):
Karen McCready-Hoover
(916) 845-8177
karen.mccready-hoover@caloes.ca.gov
Title:
Emergency Services Coordinator
Date:
April 13, 2021
Date Received at State Agency 1/9/20, 6/24/20, 3/12/21, 3/17/21, 4/7/21
Date Sent to FEMA 4/13/21
FEMA Reviewer(s):
Emily Breen
Title:
Community Planner
Date:
May 3, 2021
Date Received in FEMA Region IX April 13, 2021
Date(s) Revisions Requested May 24, 2021, April 1, 2022
Date Approvable Pending Adoption (APA)April 5, 2022
Date Approved May 11, 2022
2 FEMA Region IX Local Mitigation Plan Review Tool
SECTION 1:
REGULATION CHECKLIST
INSTRUCTIONS:The Regulation Checklist must be completed by FEMA. The purpose of the
Checklist is to identify the location of relevant or applicable content in the plan by element/sub-
element and to determine if each requirement has been ‘Met’ or ‘Not Met.’ The ‘Required
Revisions’ summary at the bottom of each element must be completed by FEMA to provide a
clear explanation of the revisions that are required for plan approval. Required revisions must
be explained for each plan sub-element that is ‘Not Met.’ Sub-elements should be referenced
in each summary by using the appropriate numbers (A1, B3, etc.), where applicable.
Requirements for each Element and sub-element are described in detail in the Local Plan
Review Guide in Section 4, Regulation Checklist.
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
ELEMENT A. PLANNING PROCESS
A1. Does the plan document the planning
process, including how it was prepared
and who was involved in the process for
each jurisdiction? (Requirement
§201.6(c)(1))
a. Does the plan provide
documentation of how the plan was
prepared? This documentation must
include the schedule or timeframe and
activities that made up the plan’s
development as well as the planning
team members who were involved.
P 5-1 & 5-2
X
b. Does the plan list the jurisdiction(s)
participating in the plan that are
seeking approval?
P 1-3
X
c. Does the plan identify who
represented each jurisdiction on the
planning team? At a minimum, it must
identify the jurisdiction represented
and the person’s position or title and
agency within the jurisdiction.)
P 5-1 & 5-2
X
A2. Does the plan document an
opportunity for neighboring communities,
local and regional agencies involved in
hazard mitigation activities, agencies that
have the authority to regulate
development as well as other interests to
be involved in the planning process?
(Requirement §201.6(b)(2))
a. Does the plan document an
opportunity for stakeholders from
neighboring communities, local, and
regional agencies involved in hazard
mitigation activities, agencies that
have the authority to regulate
development, as well as other
interested parties to be involved in the
planning process?
P 5-3
X
b. Does the plan identify how the
stakeholders were invited to
participate in the process?
P 5-3
X
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 3
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
A3. Does the plan document how the
public was involved in the planning
process during the drafting stage?
(Requirement §201.6(b)(1))
a. Does the plan document how the
public was given the opportunity to be
involved in the planning process?
P 5-3, 6-1
X
b. Does the plan document how the
public’s feedback was incorporated
into the plan?
P 1-1, 5-3,
6-1 X
A4. Does the plan describe the review and incorporation of existing plans, studies,
reports, and technical information? (Requirement §201.6(b)(3))
P 5-3 to 5-4,
P 7.1-10,
7.2-7, 7.3-8,
7.4-9, 7.5-
10
X
A5. Is there discussion of how the community(ies) will continue public participation
in the plan maintenance process? (Requirement §201.6(c)(4)(iii))
P 1-5, 10-3 X
A6. Is there a description of the method
and schedule for keeping the plan current
(monitoring, evaluating and updating the
mitigation plan within a 5-year cycle)?
(Requirement §201.6(c)(4)(i))
a. Does the plan identify how, when,
and by whom the plan will be
monitored (how will implementation
be tracked) over time?
P 1-3 to 1-
4, 10-1 to
10-2 X
b. Does the plan identify how, when,
and by whom the plan will be
evaluated (assessing the effectiveness
of the plan at achieving stated purpose
and goals) over time?
P 1-3 to 1-4,
10-1 to 10-2
X
c. Does the plan identify how, when,
and by whom the plan will be updated
during the 5-year cycle?
P 1-3 to 1-4,
10-2 to 10-3 X
ELEMENT A: REQUIRED REVISIONS
ELEMENT B. HAZARD IDENTIFICATION AND RISK ASSESSMENT
(Reviewer: See Section 4 for assistance with Element B)
B1. Does the plan include a description of
the type, location, and extent of all
natural hazards that can affect each
jurisdiction(s)? (Requirement
§201.6(c)(2)(i))
a. Does the plan include a general
description of all natural hazards that
can affect each jurisdiction?
P 6-1
X
b. Does the plan provide rationale for
the omission of any natural hazards
that are commonly recognized to
affect the jurisdiction(s) in the planning
area?
P 6-1
X
c. Does the plan include a description
of the type of all natural hazards that
can affect each jurisdiction?
P 7.1-1,
7.2-1 to 7.2-
2, 7.3-1,
7.4-1, 7.5-1,
7.6-1
X
4 FEMA Region IX Local Mitigation Plan Review Tool
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
d. Does the plan include a description
of the location for all natural hazards
that can affect each jurisdiction?
P 7.1-10,
7.1-4, 7.2-
4, 7.2-8,
7.2-9, 7.3-
6, 7.3-9,
7.4-5, 7.5-
11, 7.6-1
X
e. Does the plan include a description
of the extent for all natural hazards
that can affect each jurisdiction?
P 7.1-1 to
7.1-4, 7.2-
3, 7.3-1,
7.4-1 to
7.4-4, 7.5-
3 to 7.5-6,
7.6-1 to
7.6-3, 7.6-
8
X
B2. Does the plan include information on
previous occurrences of hazard events
and on the probability of future hazard
events for each jurisdiction? (Requirement
§201.6(c)(2)(i))
a. Does the plan include information
on previous occurrences of hazard
events for each jurisdiction?
P 7.1-1 to
7.1-3, 7.2-2
to 7.2-4,
7.3-2 to 7.3-
4, 7.4-3 to
7.4-4, 7.5-2
to 7.5-4,
7.5-6, 7.6-2
to 7.6-6
X
b. Does the plan include information
on the probability of future hazard
events for each jurisdiction?
P 7.1-5, 7.2-
4, 7.2-8,
7.2-9, 7.3-5
to 7.3-6,
7.4-4, 7.5-6,
7.6-8
X
B3. Is there a description of each
identified hazard’s impact on the
community as well as an overall summary
of the community’s vulnerability for each
jurisdiction? (Requirement
§201.6(c)(2)(ii))
a. Is there a description of each
hazard’s impacts on each jurisdiction
(what happens to structures,
infrastructure, people, environment,
etc.)?
P 7.1-1 to
7.1.-3, 7.1-5
to 7.1-9,
7.2-3, 7.2-5
to 7.2-6,
7.3-2 to 7.3-
4, 7.3-6 to
7.3-7, 7.4-3
to 7.4.9,
7.5-1, 7.5-4,
7.6-6 to 7.6-
7
X
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 5
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
b. Is there a description of each
identified hazard’s overall vulnerability
(structures, systems, populations, or
other community assets defined by the
community that are identified as being
susceptible to damage and loss from
hazard events) for each jurisdiction?
P 7.1-5 to
7.1-9, 7.2-
5 to 7.2-7,
7.3.4, 7.3-
6 to 7.3-8,
7.4.3-
7.4.9, 7.5-
1, 7.5-5,
7.5-7, 7.5-
10 to 7.5-
11, 7.6-10
X
B4. Does the plan address NFIP insured structures within the jurisdiction that have
been repetitively damaged by floods? (Requirement §201.6(c)(2)(ii))
7.2-4 X
ELEMENT B: REQUIRED REVISIONS
ELEMENT C. MITIGATION STRATEGY
C1. Does the plan document each
jurisdiction’s existing authorities, policies,
programs and resources and its ability to
expand on and improve these existing
policies and programs? (Requirement
§201.6(c)(3))
a. Does the plan document each
jurisdiction’s existing authorities,
policies, programs and resources?
P 9-6 to 9-9
X
b. Does the plan document each
jurisdiction’s ability to expand on and
improve these existing policies and
programs?
P 9-7 to 9-9
X
C2. Does the plan address each jurisdiction’s participation in the NFIP and continued
compliance with NFIP requirements, as appropriate? (Requirement §201.6(c)(3)(ii))
P 7.2-4
X
C3. Does the plan include goals to reduce/avoid long-term vulnerabilities to the
identified hazards? (Requirement §201.6(c)(3)(i))
P 1-1 to 1-3
X
C4. Does the plan identify and analyze a
comprehensive range of specific
mitigation actions and projects for each
jurisdiction being considered to reduce
the effects of hazards, with emphasis on
new and existing buildings and
infrastructure? (Requirement
§201.6(c)(3)(ii))
a. Does the plan identify and analyze a
comprehensive range of specific
mitigation actions and projects to
reduce the impacts from hazards?
9-1 to 9-6
X
b. Does the plan identify mitigation
actions for every hazard posing a
threat to each participating
jurisdiction?
9-1 to 9-6
X
c. Do the identified mitigation actions
and projects have an emphasis on new
and existing buildings and
infrastructure?
P 9-1, 9-2,
9-4, 9-6 X
6 FEMA Region IX Local Mitigation Plan Review Tool
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
C5. Does the plan contain an action plan
that describes how the actions identified
will be prioritized (including cost benefit
review), implemented, and administered
by each jurisdiction? (Requirement
§201.6(c)(3)(iv)); (Requirement
§201.6(c)(3)(iii))
a. Does the plan explain how the
mitigation actions will be prioritized
(including cost benefit review)?
P 9-1, 10-2
X
b. Does the plan identify the position,
office, department, or agency
responsible for implementing and
administering the action, potential
funding sources and expected
timeframes for completion?
P 9-1 to 9-4,
9-6
X
C6. Does the plan describe a process by
which local governments will integrate the
requirements of the mitigation plan into
other planning mechanisms, such as
comprehensive or capital improvement
plans, when appropriate? (Requirement
§201.6(c)(4)(ii))
a. Does the plan identify the local
planning mechanisms where hazard
mitigation information and/or actions
may be incorporated?
P1-4,9-6 to
9-7, 10-1 to
10-2 X
b. Does the plan describe each
community’s process to integrate the
data, information, and hazard
mitigation goals and actions into other
planning mechanisms?
P 9-6 to 9-7,
10-1 to 10-2
X
c. The updated plan must explain how
the jurisdiction(s) incorporated the
mitigation plan, when appropriate, into
other planning mechanisms as a
demonstration of progress in local
hazard mitigation efforts.
P 9-6 to 9-7,
10-1 to 10-2
X
ELEMENT C: REQUIRED REVISIONS
ELEMENT D. PLAN REVIEW, EVALUATION, AND IMPLEMENTATION
(Applicable to plan updates only)
D1. Was the plan revised to reflect changes in development? (Requirement
§201.6(d)(3))
P 4-1, 4-4 X
D2. Was the plan revised to reflect progress in local mitigation efforts?
(Requirement §201.6(d)(3))
P 5-4 to 5-9 X
D3. Was the plan revised to reflect changes in priorities? (Requirement §201.6(d)(3)) P 1-5 X
ELEMENT D: REQUIRED REVISIONS
ELEMENT E. PLAN ADOPTION
E1. Does the plan include documentation that the plan has been formally adopted
by the governing body of the jurisdiction requesting approval? (Requirement
§201.6(c)(5))
P 2-1
X
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 7
1. REGULATION CHECKLIST
Regulation (44 CFR 201.6 Local Mitigation Plans)
Location in
Plan
(section
and/or
page number)
Met Not
Met
E2. For multi-jurisdictional plans, has each jurisdiction requesting approval of the
plan documented formal plan adoption? (Requirement §201.6(c)(5))
NA
ELEMENT E: REQUIRED REVISIONS
OPTIONAL: HIGH HAZARD POTENTIAL DAM RISKS (Applicable to jurisdictions interested in becoming sub
applicants to FEMA’s Rehabilitation of High Hazard Potential Dams (HHPD) Grant Program only)
HHPD1. Did Element A4 (planning process) describe the incorporation of existing
plans, studies, reports, and technical information for high hazard potential dams?
HHPD2. Did Element B3 (risk assessment) address HHPDs?
HHPD3. Did Element C3 (mitigation goals) include mitigation goals to reduce long-
term vulnerabilities from high hazard potential dams that pose an unacceptable risk
to the public?
HHPD4. Did Element C4-C5 (mitigation actions) address HHPDs prioritize mitigation
actions to reduce vulnerabilities from high hazard potential dams that pose an
unacceptable risk to the public?
REQUIRED REVISIONS
ELEMENT F. ADDITIONAL STATE REQUIREMENTS
(Optional for State Reviewers only; not to be completed by FEMA)
F1.
F2.
ELEMENT F: REQUIRED REVISIONS
8 FEMA Region IX Local Mitigation Plan Review Tool
SECTION 2:
PLAN ASSESSMENT
A. Plan Strengths and Opportunities for Improvement
This section provides a discussion of the strengths of the plan document and identifies areas
where these could be improved beyond minimum requirements.
Element A: Planning Process
Strengths:
1) The City did a nice job of involving the public through both a public meeting and surveys.
2) The City clearly incorporates the review of existing studies, reports, and technical
information into the plan.
Opportunities for Improvement:
1) In future plans, please provide documentation such as sign-in sheets or # of surveys
received that evidence how the public was given the opportunity to be involved in the HMP
development process.
2) With respect to monitoring plan implementation, in future plans, consider describing the
system by which the status of actions will be tracked – this could be as simple as a
spreadsheet or a more complex web-based tool.
3) In addition to the avenues for public involvement listed in the plan, consider celebrating
successes with the community, such as sharing with the public when the plan is approved,
or when a mitigation action is successfully completed, through avenues such as websites,
newsletters, or social media.
Element B: Hazard Identification and Risk Assessment
Strengths:
1) The plan contains succinct and clear descriptions of the hazards that can affect the City,
and comprehensive descriptions of potential impacts and previous occurrences.
Opportunities for Improvement:
1) The plan includes a well-developed community profile section. In future plans, consider
weaving these community aspects in with the discussion of vulnerabilities for each hazard.
This was done nicely with wildfire hazard – connecting development growth into Wildland
Urban Interface areas and the vulnerabilities associated with wildfire. Are there other
unique sectors of communities within Arcadia that are particularly vulnerable to the other
hazards potentially impacting the city?
2) In some cases, only certain areas of a community may be at risk to an identified hazard,
while in other cases, the whole community may be equally at risk to a particular hazard. In
future plans, if the whole city is at equal risk to a hazard, please note this explicitly in the
plan.
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 9
Element C: Mitigation Strategy
Strengths:
1) The plan does an excellent job listing existing authorities, policies, programs and
resources and directly addresses how the jurisdiction could expand and improve.
Opportunities for Improvement:
1) It is important that mitigation actions and strategies be clear and actionable. While the
mitigation strategies included in the current plan are adequate, they are somewhat broad
which could make implementation challenging. In future plans, consider crafting strategies
that are more detailed and actionable, such as the items listed under the ‘ideas for
implementation’.
Element D: Plan Update, Evaluation, and Implementation (Plan Updates Only)
Strengths:
1) The plan comprehensively and clearly addresses changes in development and how these
changes increase vulnerabilities, particularly in the Wildland Urban Interface.
Opportunities for Improvement:
1) None at this time.
10 FEMA Region IX Local Mitigation Plan Review Tool
B. Resources for Implementing and Updating Your Approved Plan
This resource section is organized into three categories:
1) Guidance and Resources
2) Training Topics and Courses
3) Funding Sources
Guidance and Resources
Local Mitigation Planning Handbook
https://www.fema.gov/media-library/assets/documents/31598
Level Up! Podcast Series on Hazard Mitigation
https://www.georgetownclimate.org/articles/level-up-audio-project.html
Beyond the Basics
http://mitigationguide.org/
Mitigation Ideas
https://www.fema.gov/media-library/assets/documents/30627
Plan Integration: Linking Local Planning Efforts
https://www.fema.gov/media-library/assets/documents/108893
Coastal Plan Alignment Compass
https://resilientca.org/topics/plan-alignment/
Integrating Disaster Data into Hazard Mitigation Planning
https://www.fema.gov/media-library/assets/documents/103486
Integrating Historic Property and Cultural Resource Considerations into Hazard Mitigation
Planning
https://www.fema.gov/ar/media-library/assets/documents/4317
Guides to Expanding Mitigation
https://www.fema.gov/about/organization/region-2/guides-expanding-mitigation
Community Rating System User Manual
https://www.fema.gov/media-library/assets/documents/8768
U.S. Climate Resilient Toolkit
https://toolkit.climate.gov/
2018 National Climate Assessment
https://nca2018.globalchange.gov/
Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation
http://ipcc-wg2.gov/SREX/images/uploads/SREX-All_FINAL.pdf
FY15 Hazard Mitigation Assistance Unified Guidance
https://www.fema.gov/media-library/assets/documents/103279
A Guide to Supporting Engagement and Resiliency in Rural Communities
https://www.fema.gov/sites/default/files/documents/fema_rural-guide_jan-2021.pdf
Guide to Virtual Hazard Mitigation Planning Meetings
https://www.mass.gov/doc/guide-to-virtual-hazard-mitigation-planning-
meetings/download#:%7E:text=Guide%20to%20Virtual%20Hazard%20Mitigation%20Planning%20Meetings.%
20This,valuable%20input%20into%20the%20mitigation%20planning%20process,%20from
FEMA Region IX Local Hazard Mitigation Plan Review Tool (Version 4/12/2021) 11
Training
More information at https://training.fema.gov/emi.aspx or through your State Training Officer
Mitigation Planning
IS-318 Mitigation Planning for Local and Tribal Communities
https://training.fema.gov/is/courseoverview.aspx?code=is-318
IS-393 Introduction to Hazard Mitigation
https://training.fema.gov/is/courseoverview.aspx?code=is-393.a
G-318 Preparing and Reviewing Local Plans
G-393 Mitigation for Emergency Managers
Hazard Mitigation Assistance (HMA) Grant Programs
IS-212.b Introduction to Unified HMA
http://www.training.fema.gov/is/courseoverview.aspx?code=IS-212.b
IS-277 Benefit Cost Analysis Entry Level
http://www.training.fema.gov/is/courseoverview.aspx?code=IS-277
E-212 HMA: Developing Quality Application Elements
E-213 HMA: Application Review and Evaluation
E-214 HMA: Project Implementation and Programmatic Closeout
E-276 Benefit-Cost Analysis Entry Level
GIS and Hazus-MH
IS-922 Application of GIS for Emergency Management
http://www.training.fema.gov/is/courseoverview.aspx?code=IS-922
E-190 ArcGIS for Emergency Managers
E-296 Application of Hazus-MH for Risk Assessment
E-313 Basic Hazus-MH
Floodplain Management
E-273 Managing Floodplain Development through the NFIP
E-278 National Flood Insurance Program/ Community Rating System
Potential Funding Sources
Hazard Mitigation Grant Program
POC: FEMA Region IX and State Hazard Mitigation Officer
Website: https://www.fema.gov/hazard-mitigation-grant-program
Building Resilient Infrastructure and Communities Grant Program
POC: FEMA Region IX and State Hazard Mitigation Officer
Website: https://www.fema.gov/grants/mitigation/building-resilient-infrastructure-communities
Flood Mitigation Assistance Grant Program
POC: FEMA Region IX and State Hazard Mitigation Officer
Website: https://www.fema.gov/flood-mitigation-assistance-grant-program
Emergency Management Performance Grant Program
POC: FEMA Region IX
Website: https://www.fema.gov/emergency-management-performance-grant-program
12
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Local Hazard Mitigation Plan 2022
Section 4 Community Profile
4-1
Why Plan for Hazards in City of Arcadia?
Hazards can impact citizens, property, environment, and the economy of City of Arcadia.
Earthquakes, flood, Slope Failures, windstorms, wildfires, drought, hazardous materials,
transportation emergencies and terrorism have exposed City of Arcadia residents and
businesses to the financial and emotional costs of recovering after disasters. The risk
associated with hazards increases as more people move to areas affected by those
hazards.
-
land remaining for development; population density continues to increase when low-
density housing is replaced with medium and high-density development projects.
The inevitability of hazards, and the growing population and activity within the City
create an urgent need to develop strategies, coordinate resources, and increase public
awareness to reduce risk and prevent loss from future hazardous events. Identifying the
risks posed by hazards, and developing strategies to reduce the impact of a hazardous
event can assist in protecting the life and property of communities. Local residents and
businesses can work together with the City to create a Local Hazard Mitigation Plan that
addresses the potential impacts of hazard events.
Geography and the Environment
City of Arcadia has an area of 11.3 square miles and is located in Greater Los Angeles
County area. Elevations in the City range from a high of 1,200 feet to a low of 300 feet.
The terrain of the city is from the valley floor sweeping to the foothills.
Community Profile
The 11.3 square mile City of Arcadia
Located in the western San Gabriel Valley south of the San Gabriel Mountains, Arcadia,
also known as the "Community of Homes", is a picturesque, affluent, largely built out
community, with an outstanding public school system. The Los Angeles County
Arboretum, Westfield Mall at Santa Anita, Santa Anita Race Track, Arcadia County
Park, and the Santa Anita Golf Course annually attract a substantial number of visitors
into Arcadia from Southern California. With its rich history and quality of development,
Arcadia will remain a premier community.
Transportation
The 210 freeway serves the City, and the major arterial highways are Santa Anita Avenue
and Baldwin Avenue, which run north to south and Huntington Drive (Route 66), Live
Oak Avenue, Duarte Road, Foothill Boulevard and Longden Avenue, which run east to
west.
The City also has a light rail transportation system running through the center of town.
Los Angeles County Metropolitan Transportation Authority operates the Metro Gold
Line light rail system. The Gold Line operates a 31 mile light rail between Azusa and
East Los Angeles. There is a station in the center of town with parking for 300 vehicles.
The estimated weekday ridership of the Gold Line is 49,500 riders.
The MTA also operates various bus lines within the City of Arcadia.
Local Hazard Mitigation Plan 2022
Section 4 Community Profile
4-2
Major Rivers
The nearest major river is the Los Angeles River (or San Gabriel River). This River does
not have any potential impact on the City of Arcadia. Normally this river channel is dry
and only carries a significant water flow during a major rainstorm. The river channel is a
concrete channel and part of the Los Angeles County Flood Control District.
Climate
Temperatures in the City of Arcadia range from 40 degrees in the winter months to 100
degrees in the summer months. However the temperatures can vary over a wide range,
particularly when the Santa Ana winds blow, bringing higher temperatures and very low
humidity. Temperatures rarely exceed 110 degrees F in the summer months (June -
September), and rarely drop below 30 F in the winter months (November-March).
The City of Arcadia over the last seventy years of recorded rainfall has had a low of 5.27
inches of rainfall in 1947 to a high of 41.23 in 1969. Rainfall in the city averages
eighteen inches of rain per year.
Furthermore, actual rainfall in Southern California tends to fall in large amounts during
sporadic and often heavy storms rather than consistent storms at somewhat regular
intervals. In short, rainfall in Southern California might be characterized as feast or
famine within a single year. Because the metropolitan basin is largely built out, water
originating in higher elevation communities can have a sudden impact on adjoining
communities that have a lower elevation.
Minerals and Soils
The characteristics of the minerals and soils present in City of Arcadia indicate the
potential types of hazards that may occur. Rock hardness and soil characteristics can
determine whether or not an area will be prone to geologic hazards such as earthquakes,
liquefaction and Slope Failures.
Arcadia is located at the foothills of the San Gabriel Mountains in the Transverse Ranges
Geomorphic province of Southern California. The City overlays two groundwater basins:
The Raymond Water Basin on the north and the San Gabriel Water Basin on the south.
The basins are separated by the northeast trending Raymond Fault, which acts as a
hydrological barrier, and defines the boundary between the two.
The Raymond Basin is an alluvial valley covering approximately 40 square miles and is
bordered by the San Gabriel Mountains on the north, San Rafael Hills on the west, and
the Raymond Fault on the south and east. The general east-west trend of the San Gabriel
Mountains, the north-south trend of the San Rafael Hills, and northeast trend of the
Raymond Fault result in the basin having a triangular form.
The limits of the San Gabriel Valley are generally defined on the north by the San
Gabriel Mountains and the Raymond Fault, on the west by the Repetto and Merced Hills,
on the south by the Puente Hills, and on the east by the San Jose Hills. The total area of
Local Hazard Mitigation Plan 2022
Section 4 Community Profile
4-3
the alluvial valley is approximately 167 square miles. Arcadia is located at the extreme
northwest portion of the San Gabriel Valley.
Bedrock:
The bedrock geology of the Raymond Basin and vicinity consists of a complex array of
granitic and metagranitic rocks of pre-Cretaceous age. Although outcrops are typically
fractured, the granitic bedrock underlying the alluvial sediment at the base of the basin is
not considered water bearing.
Older and Younger Alluvium:
Total alluvial thickness is as much as 1,100 feet in the Raymond Basin and as much as
1,900 feet in the San Gabriel Basin. The older alluvium is distributed throughout the
entire basin and its water transmitting properties vary depending upon the degree to
which it has been weathered and/or cemented. Older alluvium consists primarily of sand,
gravel and boulders with minor interbedded clay layers.
Younger alluvium consists predominantly of sand, gravel and boulders, is less
consolidated than the older alluvium and yields water more readily and consistently.
Faulting and Ground Water Barriers:
Major faults in the vicinity of Arcadia include the Sierra Madre Fault Zone and the
Raymond Fault. The Raymond Fault is the most geohydrologically significant fault in
Arcadia. The fault acts as a barrier impeding ground water movement from the Raymond
Basin into the Main San Gabriel Basin to the south. The barrier effect is reflected by
significant differences in ground water level across the fault. In addition, artesian
conditions and ponded surface water have been observed north of the fault during periods
Concerns:
Based on the Raymond Fault creating a ground water barrier the area located to the north
of the fault can be prone to the occurrence of liquefaction or has the potential for
permanent ground displacement. The steep foothills of the San Gabriel Mountains have a
potential of the earthquake-induced Slope Failures or the permanent ground displacement
in the north part of Arcadia.
Other Significant Geologic Features
The City of Arcadia, like most of the Los Angeles Basin, lies over the area of one or
more known earthquake faults, and potentially many more unknown faults, particularly
so-called lateral or blind thrust faults.
The major faults that have the potential to affect the greater Los Angeles Basin, and
therefore the City of Arcadia are: San Andreas, Newport Inglewood, Palos Verdes,
Whittier, Santa Monica, Raymond, and Sierra Madre.
In addition, many areas in the Los Angeles Basin have sandy soils that are subject to
liquefaction and land movement.
Local Hazard Mitigation Plan 2022
Section 4 Community Profile
4-4
Population and Demographics
City of Arcadia has an estimated population of about 59,000 in an area of 11.3 square
miles.
has increased annually at a rate of 4.3% since 2010.
The increase of people living in City of Arcadia creates more community exposure, and
changes how agencies prepare for and respond to hazards. For example, more people
living on the urban fringe increase the risk of wildfire. Wildfire has an increased chance
of starting due to human activities in the urban/rural interface, and has the potential to
injure more people and cause more property damage.
Furthermore, increased density can affect risk. For example, narrower streets are more
difficult for emergency service vehicles to navigate, the higher ratio of residents to
emergency responders affects response times, and homes located closer together increase
the chances of fires spreading.
The ethnic and cultural diversity suggests a need to address multi-cultural needs and
services.
Vulnerable populations, including seniors, disabled citizens, women, and children, those
people may be disproportionately impacted by disasters.
Land and Development
including residential, commercial and industrial areas. This plan is one of the City's most
important tools in addressing environmental challenges including transportation, air
quality, growth management, conservation of natural resources, clean water, and open
spaces.
The environment of most Los Angeles County cities is nearly identical with that of their
immediate neighbors and the transition from one incorporated municipality to another is
seamless to most people. Seamless too are the exposures to the hazards that affect all of
Southern California.
Housing and Community Development
In the City of Arcadia, the demand for housing outstrips the available supply, and the
recent low interest rates have further fueled a pent up demand. There are more single
family homes in the City in comparison to the number of apartments and condominiums.
The development of condominiums has increased significantly along with the
development of mixed-use properties.
Employment and Industry
Employment and Industry - The City of Arcadia has a very broad employment base.
There are major retail, industrial, office, and specialty employers throughout the City.
Local Hazard Mitigation Plan 2022
Section 4 Community Profile
4-5
The major employers in the City include the Santa Anita Race Track, Methodist Hospital
of Southern California, and the Westfield at Santa Anita.
The City of Arcadia also lies within a "Sixty Mile Circle" centered on Los Angeles, a
dynamic concentration of population, employment, business, industry and finance. Two-
thirds of the State's 100 largest corporations are headquartered within the circle.
Additionally, several federal and state highways, two nearby rail lines, and three
international airports, as well as the 210 Freeway passing through Arcadia, provide ready
access to regional, national and international markets.
Mitigation activities are needed at the business level to ensure the safety and welfare of
workers and limit damage to industrial infrastructure. Employees are highly mobile,
commuting from surrounding areas to industrial and business centers. This creates a
greater dependency on roads, communications, accessibility and emergency plans to
reunite people with their families. Before a disastrous event occurs large and small
businesses can develop strategies to prepare, respond efficiently, and prevent loss of life
and property.
Transportation and Commuting Patterns
The City of Arcadia is located in the Los Angeles Metropolitan Statistical Area
(LAMSA)
The I-210 Foothill Freeway traverses the City of Arcadia, connecting the city to east and
north valleys of Los Angeles County, and the I-605 San Gabriel Freeway is located four
-mile road system
includes 37 miles of arterial highways, 113 miles of local roads, and 37 bridges.
Private automobiles are the dominant means of transportation in Southern California and
in the City of Arcadia. However, the City of Arcadia meets its public transportation
needs utilizing the numerous local public transportation options available in the region.
The Los Angeles County Metropolitan Transportation Authority (LACMTA) and
Foothill Transit operate a total of 11 bus routes and one light rail line through the city.
Additionally, the Arcadia Transit offers Arcadia residents convenient, affordable transit
within the city limits and to five (5) designated medical facilities located beyond the city
limits. The City participates in regional efforts to improve air quality by promoting
rideshare alternatives to its employees.
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Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-1
The City of Arcadia Local Hazard Mitigation Plan integrates a cross-section of citizen
input throughout the planning process. To accomplish this goal, the City of Arcadia
Hazard Mitigation Advisory Committee developed a public participation process through
three components: (1) developing a planning committee; (2) conducting stakeholder
interviews to target the specialized knowledge of individuals working with populations or
areas at risk from natural hazards; and (3) conducting one public workshops to identify
common concerns and ideas regarding hazard mitigation and to discuss specific goals and
actions of the mitigation plan.
Integrating public participation during the development of the City of Arcadia Local
Hazards Mitigation Plan has ultimately resulted in increased public awareness. Through
citizen involvement, the mitigation plan reflects community issues, concerns, and new
ideas and perspectives on mitigation opportunities and plan action items.
Local Hazard Mitigation Plan Committee
The first step in reviewing and updating the Local Hazard Mitigation Plan was to develop
a committee comprised of at least one member of each department within the City. Table
B.1 lists the committee members and their department at the beginning of the review.
Table B.2 lists the current committee members and their department.
Initial Local Hazard Mitigation Planning Committee Table B.1
Name Title Department
Barry Spriggs Battalion Chief - Project Manager Fire
Todd Morehead Fire Captain Fire
Paul Foley Police Captain Police
Jackie Mercado Management Analyst Public Works
Ryan Wright Assistant Recreation Director Recreation and Community Services
Roger Hiles Library Services Manager Library and Museum Services
Vanina
Rynkiewicz Purchasing Officer Administrative Services
Jim Kasama Planning and Community Development Director Development Services
Laena Shakarian Management Analyst City Manager's Office
Current Local Hazard Mitigation Planning Committee Table B.2
Name Title Department
Barry Spriggs Fire Chief - Project Manager Fire
Tom Devlin Battalion Chief Fire
Charlie Tuggle Fire Captain Fire
Tom Cullen Lieutenant Police
Carmen Masud Senior Management Analyst Public Works
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-2
Candice Cheung Assistant Recreation Director
Recreation and Community
Services
Roger Hiles Library Services Manager Library and Museum Services
Vanina
Rynkiewicz Purchasing Officer Administrative Services
Lisa Flores Planning and Community Development
Director Development Services
Jennifer Brutus Senior Management Analyst City Manager's Office
Meetings
Members of the Committee had several meetings amongst themselves, with employees
with special areas of expertise, and with outside representatives. Though not every
meeting was logged the following list gives a brief synopsis of the meetings and their
content.
January 18, 2017 to February 25, 2017
There were many meetings amongst only two individuals that did not get logged. The
meetings were often between the project leader and another committee member to ensure
the timely completion of a specific task. They also entailed preparation for upcoming
stakeholder, committee, and community meetings.
January 11, 2017
The City of Arcadia Local Hazard Mitigation Plan Committee assembled and provided an
overview to the committee about the current Natural Hazard Mitigation Plan and the
review process that was about to be undertaken.
The project Manager introduced the planning committee. Each committee member
described the department they represented. The goals from the current NHMP were
reviewed and assessed as to their completion. Various tasks were assigned to each
member of the committee. The committee agreed on the need to add drought, hazardous
materials, and terrorism to the new LHMP.
February 8, 2017
The Committee met and the project manager discussed the following:
Committee Members completed Worksheet #1 Identifying the hazards and
Worksheet #2 Asset Identification Checklist.
Committee members reviewed the base map from the previous plan and added an
additional 12 critical facilities to the base map including the Gold Line Light Rail.
Methods to gain community input were discussed including a community
meeting, stakeholder meeting and advertising the process through the City Hot
Sheet and Quarterly Newsletter.
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-3
March 17, 2017
The Committee met and the project manager discussed the following:
LHMP hazards were discussed in the February meeting. The committee decided
to group the hazards into two large categories, natural and human caused. The
natural hazards addressed by the plan are: Wildfire, Earthquake, Flood,
Windstorm, Debris Flow/Landslide, Drought.
The human caused hazards will be Hazardous Materials, Transportation and
Terrorism
Dates were set for the public meeting and the stakeholder meeting. The public
meeting will be April 10, 2017 and the Stakeholder Meeting will be April 12,
2017.
Mitigation items for the hazards were also discussed at this meeting.
October 2018
Project manager met with Arcadia Public Works Services Division and updated base
maps and hazard maps for the community.
February 12, 2019
The LHMP Committee met and were asked to provide feedback to develop mitigation
goals for the new plan. Feedback from the committee was obtained the following week
and the mitigation goals for the plan were finalized.
Community Meeting
Community members were invited to a meeting to review the current and new hazards
the City is including in the mitigation plans. This was an opportunity for the community
to learn what the City is doing and also for members of the community to provide their
input on the hazards that they felt necessary to plan for. The committee also provided a
questionnaire to the attendees in order to gain further input.
The meeting was announced to the public following the Cities regular announcement
procedures. The meeting information was published in the newspaper and on the City
website
Meeting was conducted on:
April 10, 2017 at 1900hrs in the Council Chambers Conference Room
Stakeholders Meeting
Stakeholders were invited to a meeting on April 12, 2017 at Fire Station 106 to review
the current and new hazards the City is including in the mitigation plans. This was an
opportunity for the organizations to learn what the City is doing and also to provide their
input on the hazards that they felt necessary to plan for. The committee also provided a
questionnaire to the stakeholders in order to gain further input.
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-4
The following stakeholders were all contacted about the meeting via phone and or email.
Mitigation Plan Stakeholders Table B.3
Arcadia Methodist Hospital
American Red Cross
Sierra Madre Fire Department
Monrovia Fire and Rescue
Arcadia Unified School District
Chamber of Commerce
Santa Anita Racetrack
Westfield Shopping Towne
SoCal Edison
SoCal Gas Company
CalTrans
Office of Civil Defense Disaster Management
Metro Goldline
Review of the 2012 Local Hazard Mitigation Plan
An important part of the planning process is to evaluate the plan that was approved by the
City Council and FEMA in 2012. During its meetings the Local Hazard Mitigation Plan
Committee reviewed the sections of the plan. Both the multi hazard goals and the
specific hazard goals were reviewed to see if they had been achieved during the five-year
period or if the goals were still a work in progress.
The hazards that were addressed in the 2012 plan were also looked at. The eight
hazards: Earthquake, Landslide/Debris Flow, Flood, Wildfire, Windstorm, Drought,
Terrorism, Hazardous Materials were considered to still be hazards to the community.
Action Items from the 2012 Natural Hazard Mitigation Plan
The following action items were placed into three categories based on the 2012 Local
Hazard Mitigation Plan Committee s recommendations. The LHMP Committee
considered ease, cost, and importance of completion. The following three categories rank
the achievability of each action item; category one action items being the action items to
be completed first, and respectively category three being the last.
Category One
Flood A
Enhance the City of Arcadia s dam failure preparedness.
Ideas for Implementation:
Incorporate dam inundation maps into the EOP. - Completed
Coordinating Organization: Fire Department
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-5
Funding Source: Fire Department
Timeline: Within the next six months
Constraints: Limited staff time
Wildfire A
Enhance emergency services to increase the efficiency of wildfire response.
Ideas for Implementation:
Continue to update the City of Arcadia Brush Plan. Updated Summer 2021
Develop, approve, and promote fire protection agreements and partnerships.
Updated June 2021
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Ongoing
Constraints: none
Wildfire B
Continue to educate the public on wildfire safety.
Ideas for Implementation
Continue to utilize the Arcadia Fire Department Brush Clearance Inspection
Program. - Completed
Continue to utilize the Arcadia Fire Prevention Bureau public service
announcements. Completed and Ongoing
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Ongoing
Constraints: Funding
Multi Hazard A & B
Multi Hazard A
Continue to develop and implement programs that encourage Arcadia residents and
business owners to prepare for an emergency or disaster situation.
Multi Hazard B
Create and maintain communication vehicles through which the City can communicate
with the public on both an outgoing and incoming basis.
Implementation Ideas:
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-6
Work with City departments to develop and distribute informational pamphlets
concerning specific areas of emergency and disaster preparedness. - Ongoing
Work with City departments and the School District to provide age-appropriate
emergency preparedness information to students. - Ongoing
Promote emergency/disaster preparedness to the local business community by
reaching out to local merchants and to the Chamber of Commerce. Conducted
safety presentations
As appropriate, work with the Fire and Police Departments to update the
preparedness information contained on the City website. In the event of a
significant local disaster use the website to inform the public on a timely basis of
the status of the emergency, evacuation plans and any other information that is
pertinent to their well-being. On an ongoing basis advise the public that the
website will be used to relay important information in the event of an emergency.
used to relay information to residents and businesses by way of telephone in the
event of a significant disaster. Entered into contract in 2016
Be prepared to implement in a timely fashion, a telephone hotline that residents
can call for information and a distribution system that can be used in coordination
with other methods to relay critical information. Changed from hotline to
links to information on city website.
Keep City employees informed about the need to be prepared for an emergency
both at home and at work and
recall policy. Completed and ongoing
Coordinating Organization: City Manager s Office
Funding:
Office, Fire Department, Police Department, Public Works
Services Department
Timeline: Ongoing
Constraints: Staff time
Multi Hazard C
Develop an evacuation plan for future disastrous events.
Ideas for implementation:
Establish procedures for notifying residents in the event that a mandatory
evacuation is necessary. - Completed
Determine primary and alternate routes for the safe evacuation of residents.
Integrate the evacuation routes data into the Ci
Operations Plan. Completed and Evacuation annex was evaluated after
being put into use during 2020 Bobcat Fire.
Develop a plan to coordinate the restriction of inbound traffic into the hazard area.
- Completed
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-7
Coordinating Organization: City of Arcadia Development Services, Fire and
Police Departments
Funding Source: General Fund
Timeline: Within the next one year
Constraints: Limited staff time, cost
Category Two
Landslide A
Improve the capabilities of managing debris from Landslide events by developing a
debris management strategy for the City of Arcadia.
Ideas for implementation:
Determine the necessary equipment and personnel needed to develop a
coordinated response to managing debris. Completed debris management
plan annex in City Emergency Operations Plan
Identify local debris removal sites and routes to expedite the process of debris
removal. - Ongoing
Coordinating Organization: City of Arcadia Public Works Services
Funding Source: Public Works
Timeline: Within the next three years
Constraints: Limited staff time, lack of equipment needed to
manage debris, cost associated with purchasing
equipment.
Windstorm A
Identify and implement projects to reduce the damage caused by trees during a
windstorm.
Ideas for Implementation:
Continue regular tree trimming procedures:
o Continue four-year tree trimming grid for optimum effectiveness to
maintain healthy trees.
o Ensure trees in the public right-of-way are trimmed to maintain a clearance
from all electric power lines as specified in the California Code of
Regulations and the California Public Utilities Commission
o Continue to remove trees that are dead, diseased, or dying.
o Continue the Crown Restoration Program to preserve the health of large
aging trees
o Ensure proper tree trimming techniques as approved by the Professional
Arborist Association
o Provide public education materials to residents to make them aware of the
need to regularly maintain and trim their own trees
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-8
o Update Urban Forest Master Plan to include type of trees to plant, when to
plan, where easement trees will be placed, and how and when they will be
maintained.
o Completed and updated regularly
Create and include a coordination plan with Southern California Edison to
determine power line maintenance program and emergency procedures for fallen
power lines. - Completed and updated regularly
Create an emergency contact list for mutual aid or other responsible agencies to be
added to the EOP. Completed and updated regularly
Coordinating Organization: Public Works Services Department
Funding Source: General Fund and Gas Tax
Timeline: Ongoing
Constraints: Limited staff time and capital resources to fund
Tree Trimming Contractors
Status Ongoing
Hazardous Materials A
Ideas for Implementation:
-Mat policy and incorporate it into the EOP. - Completed
and ongoing
Update known hazardous material storage locations. - Completed and ongoing
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Annually
Constraints: Staff time for updating policies
Terrorism A
Create a Standing Operating Guideline for City personnel responding to a terrorist
incident.
Implementation Ideas:
Meet with representation from the appropriate City departments to develop a SOG
that will outline the guidelines for the safest and most efficient way to respond
and operate during a terrorist incident. Completed and Ongoing.Terrorism
annex added to Emergency Operations Plan.
Coordinating Organization: Police Department
Funding Source: General Fund, Police, Fire, and Public Works budgets
Timeline: One year
Constraints: Limited staff time
Local Hazard Mitigation Plan 2022
Section 5 Planning Process
5-9
Category Three
Multi Hazard D
Integrate new earthquake, wildfire, Landslide, and flood hazard mapping data for the City
of Arcadia and improve technical analysis of earthquake hazards.
Ideas for Implementation:
Develop the City of Arcadia earthquake HAZUS data using more localized data
including the building inventory to improve accuracy of the vulnerability
assessment for the City Arcadia. Not completed
Conduct risk analysis incorporating HAZUS data and hazard maps using GIS
technology to identify risk sites and further assist in prioritizing mitigation
activities and assessing the adequacy of current land use requirements. Not
completed
Coordinating Organization: Development Services
Funding: Unfunded; possibly EOC
Timeline: Within the next three years
Constraints: Funding for a HAZUS computer; staff time
Drought
Identify and implement projects to reduce the impact of drought.
Ideas for Implementation:
Conserve water resources by:
o Improving leak detection capability of the Public Works Services Staff
o Continuing to provide water audits for indoor/outdoor uses
o ater Management Plan to ensure water supply
in the future
o Funding Capital Improvement Projects to improve the reliability and
o Develop and implement a Tiered Water Rate Pricing Structure
o Completed - City Public Works developed Drought Master Plan
Coordinating Organization: Public Works Services Department
Funding Source: Water Fund (revenue generated from billing for water
service)
Timeline: Short Term (within the next five years)
Constraints: Limited staff time, resistance from public and lack of
public participation.
Local Hazard Mitigation Plan 2022
Section 6 Risk Assessment
6-1
What is a Risk Assessment?
Conducting a risk assessment can provide information on the location of hazards, the
value of existing land and property in hazard locations, and an analysis of the risk to life,
property, and the environment that may result from hazardous events. The following
steps were taken into consideration during the risk assessment.
Hazard Identification
This is the description of the geographic extent, potential intensity, and the probability of
occurrence of a given hazard. In the plan approved in 2012, the hazards that were
identified were earthquake, landslide, windstorm, wildfire, flooding, drought, terrorism,
and hazardous materials.
Part of the planning process was to survey residents and stakeholders to see what they felt
to be hazards that could affect the City of Arcadia. In addition to the above eight
hazards, the surveys indicated that one additional hazard could adversely affect the City
of Arcadia. The one additional hazard is transportation. The main reason to add
transportation is that since the adoption of the previous plan, a countywide light rail mass
transportation system has been extended to and through Arcadia.
There are many possible hazards listed by FEMA in Guide 386-2, Understanding Your
Risks. This Local Hazard Mitigation Plan will only address those hazards listed above.
All of the hazards were considered but many were ruled out based on the survey
completed by stakeholders and looking back through historical data for this community.
Profiling Hazard Events
This process describes the causes and characteristics of each hazard, how it has affected
the City of Arcadia in the past, and what part of the City's population, infrastructure, and
environment has historically been vulnerable to each specific hazard. The hazards
impacting the City of Arcadia can be divided into two broad categories. The categories
are natural caused hazards and human caused hazards. A profile of each hazard is
provided in each hazard specific section. For a full description of the history of hazard
specific events, please see the appropriate hazard chapter.
Vulnerability Assessment/Inventorying Assets
This is a combination of hazard identification with an inventory of the existing (or
planned) property development(s) and population(s) exposed to a hazard. Critical
facilities are of particular concern because these entities provide essential products and
services to the general public that are necessary to preserve the welfare and quality of life
in the City and fulfill important public safety, emergency response, and/or disaster
recovery functions. The critical facilities have been identified, mapped, and are
illustrated in the City base map. In addition, this plan includes a community issues
summary in each hazard section to identify the most vulnerable and problematic areas in
the City, including critical facilities, and other public and private property.
Local Hazard Mitigation Plan 2022
Section 6 Risk Assessment
6-2
Risk Analysis
Estimating potential losses involves assessing the damage, injuries, and financial costs
likely to be sustained in a geographic area over a given period of time. Risk Analysis
discusses the possible effect of hazards on parts of the City including but not limited to:
bridges, critical infrastructure, dams, businesses, and residential areas.
Assessing Vulnerability/ Analyzing Development Trends
This step provides a general description of land uses and development trends within the
community so that mitigation options can be considered in land use planning and future
land use decisions. This plan provides comprehensive description of the character of the
City of Arcadia in the Community Profile. This description includes the geography and
environment, population and demographics, land use and development, housing and
community development, employment and industry, and transportation and commuting
patterns. Analyzing these components of City of Arcadia can help in identifying
potential problem areas and can serve as a guide for incorporating the goals and ideas
contained in this mitigation plan into other community development plans.
Maps can be found at the back of each hazard specific section for which they are
appropriate.
*Infrastructure and critical facilities maps have been withheld due to security concerns
post 9-11.
Note: The information on the maps in this plan was derived from City of Arcadia's
GIS. Care was taken in the creation of these maps, but is provided "as is" City of
Arcadia cannot accept any responsibility for any errors, omissions or positional
accuracy, and therefore, there are no warranties that accompany these products
(the maps). Although information from land surveys may have been used in the
creation of these products, in no way does this product represent or constitute a
land survey. Users are cautioned to field verify information on this product before
making any decisions.
Hazard assessments are subject to the availability of hazard-specific data. Gathering data
for a hazard assessment requires a commitment of resources on the part of participating
organizations and agencies. Each hazard-specific section of the plan includes a section
on hazard identification using data and information from City, County or State agency
sources.
Regardless of the data available for hazard assessments, there are numerous strategies the
City can take to reduce risk. These strategies are described in the action items detailed in
the Mitigation Strategy section of this Plan. Mitigation strategies can further reduce
disruption to critical services, reduce the risk to human life, and alleviate damage to
personal and public property and infrastructure. Action items throughout the hazard
sections provide recommendations to collect further data to map hazard locations and
conduct hazard assessments.
Local Hazard Mitigation Plan 2022
Section 6 Risk Assessment
6-3
Federal Requirements for Risk Assessment
Recent federal regulations for hazard mitigation plans outlined in 44 CFR Part 201
include a requirement for risk assessment. This risk assessment requirement is intended
to provide information that will help communities to identify and prioritize mitigation
activities that will reduce losses from the identified hazards. There are nine hazards
profiled in the mitigation plan, including earthquakes, earth movements, flooding,
wildfires, windstorms, drought, terrorism, transportation and hazardous materials. The
Local
Hazard Mitigation Plan meets those criteria is outlined in Table 3-2 below.
Table 3-2. Federal Criteria for Risk Assessment
Section 322 Plan
Requirement
How is this addressed?
Identifying Hazards Each hazard section includes an inventory of the best
available data sources that identify hazard areas. To
the extent GIS data are available, the City developed
maps identifying the location of the hazard in the City.
The Executive Summary and the Risk Assessment
sections of the plan include a list of the hazard maps.
Profiling Hazard Events Each hazard section includes documentation of the
history, and causes and characteristics of the hazard in
the City.
Assessing Vulnerability:
Identifying Assets
Where data is available, the vulnerability assessment
for each hazard addressed in the mitigation plan
includes an inventory of all publicly owned land within
hazardous areas. Each hazard section provides
information on vulnerable areas in the City in the
Community Issues section.
Assessing Vulnerability:
Estimating Potential Losses:
The Risk Assessment Section of this mitigation plan
identifies key critical facilities and lifelines in the City
and includes a map of these facilities. Vulnerability
assessments have been completed for the hazards
addressed in the plan, and quantitative estimates were
made for each hazard where data was available.
Assessing Vulnerability:
Analyzing Development
Trends
The City of Arcadia Profile Section of this plan
provides a description of the development trends in the
City, including the geography and environment,
population and demographics, land use and
development, housing and community development,
employment and industry, and transportation and
commuting patterns.
Critical Facilities and Infrastructure
Facilities critical to government response and recovery activities (i.e., life safety and
property and environmental protection) include: 911 centers, emergency operations
centers, police and fire stations, public works facilities, communications centers, sewer
Local Hazard Mitigation Plan 2022
Section 6 Risk Assessment
6-4
and water facilities, hospitals, light rail lines, bridges and roads, shelters, and facilities
that, if damaged, could cause serious secondary impacts may also be considered
"critical." A hazardous material facility is one example of this type of critical facility.
Critical and essential facilities are those facilities that are vital to the continued delivery
recover from the emergency. These facilities may include: buildings such as the jail, law
enforcement center, public services building, community corrections center, the
courthouse, and juvenile services building and other public facilities such as schools.
The attached charts/maps illustrate the critical facilities, essential facilities, public
infrastructure, and emergency transportation routes within the City of Arcadia.
Summary
Hazard mitigation strategies can reduce the impacts concentrated at large employment
and industrial centers, public infrastructure, and critical facilities. Hazard mitigation for
industries and employers may include developing relationships with emergency
management services and their employees before disaster strikes, and establishing
mitigation strategies together. Collaboration among the public and private sector to
create mitigation plans and actions can reduce the impacts of disasters.
Local Hazard Mitigation Plan 2022
Section 7 Natural Hazards
7
When developing the Local Hazard Mitigation Plan for the City of Arcadia, the
committee decided to place the hazards into two broad categories. The categories are
Natural Hazards and Human Caused Hazards. Section 7 of the plan covers Natural
Hazards. The hazards are:
Section 7.1 Earthquake
Section 7.2 Flood
Section 7.3 Slope Failure - Debris/Mud Flow
Section 7.4 Windstorm
Section 7.5 Wildfire
Section 7.6 Drought.
All data tables and maps included in this section were updated during the revision of this
plan.
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-1
Definition of an Earthquake
A shaking or trembling of the earth that is volcanic or tectonic in origin.1
Earthquake Related Hazards
Ground shaking, slope failures, liquefaction, and amplification are the specific hazards
associated with earthquakes. The severity of these hazards depends on several factors,
including soil and slope conditions, proximity to the fault, earthquake magnitude, and the
type of earthquake.
Ground Shaking
Ground shaking is the motion felt on the earth's surface caused by seismic waves
generated by the earthquake. It is the primary cause of earthquake damage. The strength
of ground shaking depends on the magnitude of the earthquake, the type of fault, and the
distance from the epicenter. Buildings on poorly consolidated and thick soils will
typically see more damage than buildings on consolidated soils and bedrock.
Earthquake Induced Slope failures
Earthquake induced slope failures are secondary earthquake hazards that occur from
ground shaking. Many communities in Southern California have a high likelihood of
encountering such risks, especially in areas with steep slopes. Map 7-3 identifies the
areas vulnerable to slope failures within the city of Arcadia.
Liquefaction
Liquefaction occurs when ground shaking causes wet granular soils to change from a
solid state to a liquid state. This results in the loss of soil strength and the soil's ability to
support weight. Buildings and their occupants are at risk when the ground can no longer
support these buildings and structures. Many communities in Southern California are
built on ancient river bottoms and have sandy soil. In some cases, this ground may be
subject to liquefaction, depending on the depth of the water table. Map 7-3 also identifies
areas vulnerable to liquefaction within the city of Arcadia.
Amplification
Soils and soft sedimentary rocks near the earth's surface can modify ground shaking
caused by earthquakes. One of these modifications is amplification. Amplification
increases the magnitude of the seismic waves generated by the earthquake. The amount
of amplification is influenced by the thickness of geologic materials and their physical
properties. Buildings and structures built on soft and unconsolidated soils can face
greater risk. Amplification can also occur in areas with deep sediment filled basins and
on ridge tops.
History of Earthquakes in Southern California
The most recent significant earthquake event affecting Southern California was the 2019
Ridgecrest Earthquake. The Ridgecrest earthquake sequence included a magnitude-6.4
foreshock on July 4, followed by a magnitude-7.1 mainshock nearly 34 hours later. The
earthquakes resulted in one death, 25 people injured and approximately 5.3 billion dollars
in damages.ii
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-2
The most impactful to the L.A. Basin was the 6.7 magnitude Northridge Earthquake that
occurred on January 24, 1994. 57 people were killed, and more than 1,500 people
seriously injured. For days afterward, thousands of homes and businesses were without
electricity, tens of thousands had no gas, and nearly 50,000 had little or no water.
Approximately 15,000 structures were moderately to severely damaged, which left
thousands of people temporarily homeless. About 66,500 buildings were inspected.
Nearly 4,000 were severely damaged and over 11,000 were moderately damaged. Several
collapsed bridges and overpasses created commuter havoc on the freeway system.
Ground shaking caused extensive damage, but earthquake triggered liquefaction and
dozens of fires also caused additional severe damage. This extremely strong ground
motion in large portions of Los Angeles County resulted in record economic losses.
The earthquake occurred early in the morning on a holiday. This circumstance
considerably reduced the potential effects. Many collapsed buildings were unoccupied,
and most businesses were not yet open. The direct and indirect economic losses ran into
the tens of billions of dollars.
Historical and geological records show that California has a long history of seismic
events. Southern California is probably best known for the San Andreas Fault, a 400-
mile-long fault running from the Mexican border to a point offshore, west of San
Geologic studies show that over the past 1,400 to 1,500 years large
earthquakes have occurred at about 130-year intervals on the southern San Andreas Fault.
As the last large earthquake on the southern San Andreas occurred in 1857, that section
of the fault is considered a likely location for an earthquake within the next few
decades.iii
San Andreas is only one of dozens of known earthquake faults that crisscross Southern
California. Some of the better-known faults include the Newport-Inglewood, Whittier,
Chatsworth, Elsinore, Hollywood, Los Alamitos, and Palos Verdes faults. Beyond the
surface of Southern California. One such blind fault was involved in the Whittier
Narrows earthquake in October 1987.
Although the most famous of the faults, the San Andreas, is capable of producing an
earthquake with a magnitude of 8+
the potential to inflict greater damage on the urban core of the Los Angeles Basin.
Seismologists believe that a 6.0 earthquake on the Newport-Inglewood would result in far
Andreas is relatively remote from the urban centers of Southern California. Refer to the
following table 7.1-1 of Earthquake Events in the Southern California Region.
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-3
Table: 7.1-1 Southern California Earthquakes with a Magnitude 5.0 or Greater since 1960
1971 San Fernando 1992 Landers 2001 Anza
1973 Point Mugu 1992 Big Bear 2003 Big Bear
1986 North Palm Springs 1994 Northridge 2004 Parkfield
1987 Whittier Narrows 1999 Hector Mine 2008 Chino Hills
2010 Baja California 2014 La Habra 2019 Ridgecrest
History of Earthquakes in the City of Arcadia
The most recent large-scale destruction to strike Arcadia was during the 1994 earthquake.
it is estimated that the event directly or indirectly affected about 3% of the City's 53,000
residents. The City sought and received a County, State, and Presidential Disaster
Declaration to obtain assistance for its recovery effort. Even though the earthquake was
respond and repair large-scale damage without the assistance of the county, state, and
federal government.
Even though a lesser known fault line, the Raymond Fault, is only predicted to have a
major rupture about once every 4500 years it still crosses right through the City of
Arcadia, and there are even a couple of schools sitting directly on the Fault itself. The last
major rupture of the Raymond Fault occurred sometime in the last 2000 years. However,
the most recent notable seismic activity of the Fault occurred in the southern area of
Pasadena with a magnitude of 5.0. Even though there were only a few minor injuries and
slight damage reported, the Raymond Fault still has the potential to cause severe damage
to the City of Arcadia and its residents.
A more well know fault that crosses through the north end of Arcadia is the Sierra Madre
Fault Line. Though its last major rupture occurred in the Holocene era and it is predicted
to have major seismic activity about once every several thousand years it could still cause
great damage to the City of Arcadia and its neighboring communities.
Although the Clamshell-Sawpit Canyon Fault does not cross directly through Arcadia it
should still be considered a great threat to the community. On June 28, 1991 seismic
activity of about a 5.8 magnitude occurred on the Clamshell-Sawpit Canyon Fault, an
offshoot of the Sierra Madre fault zone in the San Gabriel Mountains. ivBecause of its
depth and moderate size, it caused no surface rupture, but it did trigger rockslides that
blocked some of the local mountain roads. Roughly $40 million in property damage
occurred in the San Gabriel Valley; unreinforced masonry buildings were hardest hit, and
many brick chimneys collapsed. Two deaths resulted from this earthquake -- one person
was killed in Arcadia, and one person in Glendale died from a heart attack. In all, at least
100 others were injured, though the injuries were mostly minor. v
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-4
Earthquake Hazard Assessment
The San Gabriel Valley is littered with both surface and blind fault lines. Though the
Raymond and Sierra Madre Fault Lines cross directly through the City of Arcadia there
are many other faults that pose a great risk to the community including but not limited to
the Clamshell-Sawpit, San Gabriel, and San Andreas Faults.
Many organizations, in partnership with other state and federal agencies, have undertaken
a rigorous program in California to identify seismic hazards and risks including active
fault identification, bedrock shaking, tsunami inundation zones, ground motion
amplification, liquefaction, and earthquake induced slope failures. Seismic hazard maps
have been published and are available for many communities in California through the
State Division of Mines and Geology. Map 7-1 illustrate the known earthquake faults in
the San Gabriel Valley, and Arcadia.
The City of Arcadia is at risk from many fault lines throughout California. The following
Table 7.1-2 shows the distance between the fault line and the City of Arcadia.
Table 7.1-2 Distances and Estimated Earthquake Strengths for Regional Faults
Fault Name Approximate Distance from
Arcadia
Maximum Credible Earthquake
(MCE)
Sierra Madre 0 miles 6.7 MCE
Raymond 0 miles 6.5 MCE
Clamshell-Sawpit 1 mile 6.5 MCE
San Gabriel 4 miles 7.0 MCE
Verdugo 8 miles 6.7 MCE
Whittier-North Elsinore 10 miles 7.0 MCE
Elysian Park 11 miles 6.7 MCE
Santa Monica-Hollywood 13 miles 6.6 MCE
San Jose 14 miles 6.5 MCE
Chino 18 miles 6.7 MCE
San Andreas (Mojave section) 21 miles 7.1 MCE
Cucamonga 22 miles 7.0 MCE
Newport-Inglewood 23 miles 6.9 MCE
Oak Ridge 24 miles 6.9 MCE
Newport-Inglewood (offshore) 26 miles 6.9 MCE
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-5
Probability
The U.S.G.S. in March 2015 published Version 3 of the Uniform California Earthquake
Rupture Forecast (UCERF).vi This document lists the probability and magnitude of an
earthquake occurring in many regions of California including the Los Angeles Region.
Below is the table for the Los Angeles Region:
Magnitude Greater or Equal
Than To Average Repeat Time
30 Year Likelihood or one or
more events
5 1.4 100%
6 10 96%
6.7 40 60%
7 61 46%
7.5 109 31%
8 532 7%
Risk Analysis
Risk analysis involves estimating the damage and costs likely to be experienced in a
geographic area over a period of time. Factors included in assessing earthquake risk
include population and property distribution in the hazard area, the frequency of
earthquake events, slope failure susceptibility, buildings, infrastructure, and disaster
preparedness of the region. This type of analysis can generate estimates of the damages to
the region due to an earthquake event in a specific location.
Damages from a large earthquake almost anywhere in Southern California are likely to
run into the billions of dollars. Although building codes are some of the most stringent in
the world, tens of thousands of older existing buildings were built under less rigid codes.
many building owners have retrofitted their buildings, hundreds of pre-1933 buildings
still have not been brought up to current standards. All existing uncensored masonry
buildings in the City of Arcadia have been seismically retrofitted to comply with the
"1990 Revised Model Ordinance for the Seismic Retrofit of Hazardous unreinforced
Masonry Buildings" as developed by the State of California Seismic Safety Commission.
Economic Impact
The City of Arcadia has a total assessed valuation of $15,676,471,562. This can be
further broken into:
Residential properties valued at $12,959,501,963
Commercial properties valued at $ 1,524,210,934
Other properties valued at $ 1,192,758,665
Arcadia s Current Mitigation of Earthquake Hazards
Earthquake damage occurs because humans have built structures that cannot withstand
severe shaking. Buildings, airports, schools, and lifelines (highways and utility lines)
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-6
suffer damage in earthquakes and can cause death or injury to humans. The welfare of
homes, major businesses, and public infrastructure is very important. Addressing the
reliability of buildings, critical facilities, and infrastructure, and understanding the
potential costs to government, businesses, and individuals as a result of an earthquake,
are challenges faced by the city.
Dams
There is a total of 103 dams in Los Angeles County, owned by 23 agencies or
organizations, ranging from the Federal government to Homeowner Associations.vii
These dams hold billions of gallons of water in reservoirs.
There are portions of the City that are located within the flood hazard areas (or
inundation areas) of three (3) dams, including the Eaton Wash Dam in East Pasadena, the
Santa Anita Dam, which is located in the Angeles National Forest above Arcadia, and the
Sawpit Dam, which is located in Monrovia. A portion of the Sierra Madre Dam hazard
area is also located within the City boundary but the dam was recently modified and no
longer poses a potential threat to the City. For further information on dams and flood
waters please see Section 7.2 Flooding Hazards.
Infrastructure and Communication
Residents in the City of Arcadia commute frequently by automobiles and public
transportation such as buses and light rail. An earthquake can greatly damage bridges
and roads, hampering emergency response efforts and the normal movement of people
and goods. Damaged infrastructure strongly affects the economy of the community
because it disconnects people from work, school, food, and leisure, and separates
businesses from their customers and suppliers.
Bridge Damage
Even modern bridges can sustain damage during earthquakes, leaving them unsafe for
use. Some bridges have failed completely due to strong ground motion. Bridges are a
vital transportation link - with even minor damages making some areas inaccessible.
Because bridges vary in size, materials, location and design, any given earthquake will
affect them differently. Bridges built before the mid-1970' s have a significantly higher
risk of suffering structural damage during a moderate to large earthquake compared with
those built after 1980 when design improvements were made.
The FHWA requires that bridges on the National Bridge Inventory be inspected every 2
years. CalTrans checks when the bridges are inspected because they administer the
Federal funds for bridge projects. Even though the bridges in the City of Arcadia are
state, county, or privately owned (including railroad bridges) all of the inspected bridges
earned a Satisfactory rating or better. Prior to the opening of the Goldline Light Rail
Extension through Arcadia in 2016
way were rebuilt to current building code standards.
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-7
Damage to Lifelines
Lifelines are the connections between communities and outside services. They include
water and gas lines, transportation systems, electricity, and communication networks.
Ground shaking and amplification can cause pipes to break open, power lines to fall,
roads and railways to crack or move, and radio and telephone communication to cease.
Disruption to transportation makes it especially difficult to bring in supplies or services.
Lifelines need to be usable after an earthquake to allow for rescue, recovery, and
rebuilding efforts and to relay important information to the public.
Disruption of Critical Services
Critical facilities include police stations, fire stations, hospitals, shelters, and other
facilities that provide important services to the community. These facilities and their
services need to be functional after an earthquake event. Many critical facilities are
housed in older buildings that are not up to current seismic codes. However, all critical
public buildings in Arcadia have been built to code and are considered seismically sound.
Individual Preparedness
Because the potential for earthquake occurrences and earthquake related property damage
is relatively high in the City of Arcadia, increasing individual preparedness is a
significant need. Strapping down heavy furniture, water heaters, and expensive personal
property, as well as being earthquake insured, and anchoring buildings to foundations are
just a few steps individuals can take to prepare for an earthquake. The residents and
business owners of Arcadia can visit any fire station to obtain literature on earthquake
preparedness and survival.
Fire
Downed power lines or broken gas mains can trigger fires. Major incidents will demand
a larger share of resources, and initially smaller fires and problems will receive little or
insufficient resources in the initial hours after a major earthquake event. Loss of
electricity may cause a loss of water pressure in some communities, further hampering
firefighting ability. In the event of an earthquake the Arcadia Fire Department has an
Earthquake Policy. The policy states: when and where off-duty personnel should report,
initial tasks of on duty personnel, and provides initial assignments for determining the
amount of damage the City and its occupants suffered. The City of Arcadia also has a
Disaster Recall Policy encompassing all departments which details when and where City
Employees are to report and the responsibilities of each person.
Debris
After damage to a variety of structures, much time is spent cleaning up brick, glass,
wood, steel or concrete building elements, office and home contents, and other materials.
The City of Arcadia has a debris management annex in its Emergency Operations Plan.
City staff is also working with Los Angeles County Public Works on a Debris
Management Plan for the entire county of Los Angeles.
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-8
Buildings
The built environment is susceptible to damage from earthquakes. Buildings that
collapse can trap and bury people. Lives are at risk and the cost to clean up the damages
is great. In most California communities, including the city of Arcadia, many buildings
were built before 1993 when building codes were not as strict. In addition, retrofitting is
not required except under certain conditions and can be expensive. Therefore, the
number of buildings at risk remains high. The California Seismic Safety Commission
makes annual reports on the progress of the retrofitting of unreinforced masonry
buildings. All unreinforced masonry buildings both publicly and privately owned in are
Arcadia have been retrofitted to meet current standards.
City of Arcadia Codes
Implementation of earthquake mitigation policy most often takes place at the local
government level. The City of Arcadia Development Services Department enforces
building codes pertaining to earthquake hazards. The City of Arcadia has adopted the
2019 California Building Code. Therefore, all earthquake hazard mitigation measures
specified in the Code are enforced by the City of Arcadia for new and remodeled
buildings and structures. This ensures that all buildings be built and remodeled at the
most current seismic standards.
Generally, these codes seek to discourage development in areas that could be prone to
flooding, slope failure, wildfire and / or seismic hazards; and where development is
permitted, that the applicable construction standards are met. Developers in hazard-prone
areas may be required to retain a qualified professional engineer to evaluate level of risk
on the site and recommend appropriate mitigation measures.
The City of Arcadia also requires that site-specific seismic hazard investigations be
performed for new essential facilities, major structures, hazardous facilities, and special
occupancy structures such as schools, hospitals, and emergency response facilities.
Businesses/Private Sector
Seismic activity can create economic loss that presents a burden to large and small shop
owners who may have difficulty recovering from their losses. When a company is forced
to stop production for just a day, the economic loss can be tremendous. In fact, of all
businesses which close following a disaster, more than forty-three percent never reopen,
and an additional twenty-nine percent close for good within the next two years.viii The
disaster planning toolkit to help guide businesses in preparing for and dealing with the
adverse effects of natural hazards. The kit integrates protection from natural disasters
into the company's risk reduction measures to safeguard employees, customers, and the
investment itself. The guide helps businesses secure human and physical resources
during disasters and helps to develop strategies to maintain business continuity before,
during, and after a disaster occurs.
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-9
Hospitals
in response to the moderate Magnitude 6.6 Sylmar Earthquake in 1971 when four major
hospital campuses were severely damaged and evacuated. Two hospital buildings
collapsed killing forty-seven people. Three others were killed in another hospital that
nearly collapsed.
In approving the Act, the Legislature noted that:
Hospitals, that house patients who have less than the capacity of normally healthy
persons to protect themselves, and that must be reasonably capable of providing services
to the public after a disaster, shall be designed and constructed to resist, insofar as
practical, the forces generated by earthquakes, gravity and winds. (Health and Safety
Code Section 129680)
When the Hospital Act was passed in 1973, the State anticipated that, based on the
regular and timely replacement of aging hospital facilities, the majority of hospital
years. However,
hospital buildings were not, and are not, being replaced at that anticipated rate. In fact,
orthridge Earthquake,
expanded the scope of the 1973 Hospital Act. Under SB 1953, all hospitals are required,
as of January 1, 2008, to survive earthquakes without collapsing or posing the threat of
significant loss of life. The 1994 Act further mandates that all existing hospitals be
seismically evaluated, and retrofitted, if needed, by 2030, so that they are in substantial
compliance with the Act (which requires that the hospital buildings be reasonably capable
of providing services to the public after disasters). SB 1953 applies to all urgent care
facilities (including those built prior to the 1973 Hospital Act) and affects approximately
2,500 buildings on 475 campuses.
Community Issues Summary
One fault line runs diagonally through Arcadia. A large earthquake on that fault would
impact:
City owned roadways, water infrastructure and radio repeater site.
Interstate 210
Metro Gold Line Light Rail
One middle school
Two elementary schools
A Regional Mall
A horse racing track with a capacity for over 50,000 patrons
A major natural gas distribution line feeding the San Gabriel Valley runs through
Arcadia and crosses the fault line
Local Hazard Mitigation Plan 2022
Section 7.1 Earthquake
7.1-10
Works Cited
1 http://pubs.usgs.gov/gip/earthq3/when.html
iiAnalysis of recent Ridgecrest, California earthquake sequence reveals complex,
damaging fault systems, California Institute of Technology (October 17, 2019)
iii http://pubs.usgs.gov/gip/earthq3/when.html
iv (Haukson, 1994
v http://www.data.scec.org/chrono_index/sierrama.html
vi
March 2015
viiSource: Los Angeles County Public Works Department, March 2004
viiiInstitute for Business and Home Safety Resources (April 2001),
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-1
Definition of Flooding
A rising and overflowing of a body of water especially onto normally dry land.i
Flood Related Hazards
Flooding occurs when climate, geology, and hydrology combine to create conditions where
water flows outside of its usual course. While the City of Arcadia has some of these conditions,
it has been fortunate enough to have no experience of flooding in the City.
Winter Rainfall
Over the last 125 years, the average annual rainfall in Los Angeles has been 14.9 inches. But the
only 4.35 inches in 2001-2002 to 38.2 inches in 1883-1884. In fact, in only fifteen of the past
125 years, has the annual rainfall been within plus or minus 10% of the 14.9 inch average. And
in only 38 years has the annual rainfall been within plus or minus 20% of the 14.9 inch average.
This makes the Los Angeles basin a land of extremes in terms of annual precipitation. The City
of Arcadia is centrally located in the San Gabriel Valley. It is up against the San Gabriel
Mountains or hills, which could increase the collection of rainwater.
Monsoons
Another relatively regular source for heavy rainfall, particularly in the mountains and adjoining
cities is from summer tropical storms.
Riverine Flooding
Riverine flooding is the overbank flooding of rivers and streams. The natural processes of
riverine flooding add sediment and nutrients to fertile floodplain areas. Flooding in large river
systems typically results from large-scale weather systems that generate prolonged rainfall over a
wide geographic area, causing flooding in hundreds of smaller streams, which then drain into the
major rivers.
Shallow Area Flooding
Shallow area flooding is a special type of riverine flooding. FEMA defines shallow flood
hazards as areas that are inundated by the 100-year flood with flood depths of only one to three
feet. These areas are generally flooded by low velocity sheet flows of water.
100-Year Flood
The 100-year flooding event is the flood having a one percent chance of being equaled or
exceeded in magnitude in any given year. Contrary to popular belief, it is not a flood occurring
once every 100 years. The 100-year floodplain is the area adjoining a river, stream, or
watercourse covered by water in the event of a 100-year flood.
Urban Flooding
As land is converted from fields or woodlands to roads and parking lots, it loses its ability to
absorb rainfall. Urbanization of a watershed changes the hydrologic systems of the basin.
Heavy rainfall collects and flows faster on impervious concrete and asphalt surfaces. The water
moves from the clouds, to the ground, and into streams at a much faster rate in urban areas.
Adding these elements to the hydrological systems can result in flood waters that rise very
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-2
rapidly and peak with violent force.
Dam Failure Flooding
Loss of life and damage to structures, roads, and utilities may result from a dam failure.
Economic losses can also result from a lowered tax base and lack of utility profits. These effects
could certainly accompany the failure of one of the major dams surrounding the City of Arcadia.
There are no
located within the flood hazard areas (or inundation areas) of three (3) dams, including the Eaton
Wash Dam in East Pasadena, the Santa Anita Dam, which is located in the Angeles National
Forest above Arcadia, and the Sawpit Dam, which is located in Monrovia.
History of Flooding in Southern California
There are a number of rivers in the Southern California region, but the river with the best
recorded history is the Los Angeles River. The flood history of the Los Angeles River is
generally indicative of the flood history of much of Southern California.
Records show that since 1811, the Los Angeles River has flooded 30 times, on average once
every 6.1 years. But averages are deceiving, for the Los Angeles basin goes through periods of
drought and then periods of above average rainfall. Between 1889 and 1891 the river flooded
every year, and from 1941 to 1945, the river flooded 5 times. Conversely, from 1896 to 1914, a
period of 18 years, and again from 1944 to 1969, a period of 25 years, the river did not have
serious floods.ii
A Sample of Major Floods of the Los Angeles River Table 7.2
1825 L.A. River changed its course back from the Ballona wetlands to San Pedro
1861-62 Heavy flooding. Fifty inches of rain falls during December and January.
1867 Floods create a large, temporary lake out to Ballona Creek.
1884 Heavy flooding caused river to change course, turning east to Vernon & then south to San Pedro.
1914 Heavy flooding. Great damage to the harbor.
1934 Moderate flood starting January 1. Forty dead in La Canada.
1938 Great County-wide flood with 4 days of rain. Most rain on day 4.
1941-44 L.A. River floods five times.
1969 One heavy flood after 9 day storm. One moderate flood.
1979 Los Angeles experiences severe flooding and mudslides.
1980 Flood tops banks of river in Long Beach. Sepulveda Basin spillway almost opened.
1983 Flooding kills six people.
1992 15 year flood. Motorists trapped in Sepulveda basin. Six people dead.
1994 Heavy flooding
Sources: http://www.lalc.k12.ca.us/target/units/river/tour/hist.html and (http://www.losangelesalmanac.com/topics/History/hi01i.htm)
While the City of Arcadia is 15 miles east of Los Angeles, it is not so far away as to not be
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-3
affected by the heavy rains that brought flooding to Los Angeles. In addition, the towering
mountains that give the Los Angeles region its spectacular views also bring a great deal of rain
out of the storm clouds that pass through. Because the mountains are so steep, the rainwater
moves rapidly down the slopes and across the coastal plains on its way to the ocean.
surround three sides of the valley, seldom reach heights above
three thousand feet. The western San Gabriel Mountains, in
contrast, have elevations of more than seven thousand feet. These
higher ridges often trap eastern-moving winter storms. Although
downtown Los Angeles averages just fifteen inches of rain a year,
some mountain peaks in the San Gabriels receive more than forty
iii
Naturally, this rainfall moves rapidly downstream, often with severe consequences for anything
in its path. In extreme cases, flood-generated debris flows will roar down a canyon at speeds near
40 miles per hour with a wall of mud, debris and water tens of feet high.
In Southern California, stories of floods, debris flows, persons buried alive under tons of mud
and rock and persons swept away to their death in a river flowing at thirty-five miles an hour are
without end. No catalog of chaos could contain all the losses suffered by man and his
possessions from the Regions Rivers and streams.
Arcadia and surrounding areas are, like most of Southern California, subject to
unpredictable seasonal rainfall. Most years, the scant winter rains are barely sufficient to turn the
hills green for a few weeks, but every few years the region is subjected to periods of intense and
sustained precipitation that sometimes results in localized flooding. Natural (Storm) Flooding In
Southern California, storm flooding is difficult to predict, and thus plan for, because rainfall
varies from year to year. Flood hazards related to storm events generally are described in terms
of a 100- or 500-year flood. A 100-year flood is defined as a major flood event that has a one
percent or greater chance of occurring during any one year. Flood hazard planning practices
addresses such storms, as well as 500-year events. These floods are considered severe; however,
these floods can be reasonably predicted and therefore reasonably mitigated. As noted above, the
Los Angeles County Department of Public Works has constructed regional flood and debris
control facilities throughout the region, including the flood control channels in Arcadia that
direct runoff water through the City into regional facilities to the south. A system of spreading
basins manages storm water runoff and helps recharge groundwater basins. Locally, the City
maintains approximately four miles of subsurface storm drains that flow into the regional
channels. Due to the combination of these two systems, no areas in Arcadia lie within a 100-year
iv
The City has experienced Urban Flooding.
storm. The water overflowed onto the City streets but caused little to no damage to any public or
private property. Once the rainfall lessened, the sewer system was able once again channel the
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-4
water through and away from the City. The 2010 City of Arcadia General Plan under Chapter 8
superior storm draining and flood control facilities
that minimize the risk of flooding. The goal is achieved through the following policies:
Policy S-
prone to localized ponding and flooding.
Policy S-2.2: Continue rigorous maintenance of storm drainage and flood control
Policy S-2.3: Require that new development projects retain as much runoff as possible on
the development site to reduce flow volumes into the storm drain system, allow for
requirements (consistent with the National Pollutant Discharge Elimination Systems
program, or NPDES) and employ Best Management Practices (BMPs).
Policy S-2.4: Support efforts of the Los Angeles County Department of Public Works and
other agencies responsible for the maintenance of dams and reservoirs above Arcadia to
improve conditions of the facilities and reduce the risk of inundation resulting from dam
or reservoir failure.
National Flood Insurance Program
The City of Arcadia does not participate in the National Flood Insurance Program.
Flooding Hazard Assessment
The most current FEMA map confirms that the City of Arcadia is rated area X, areas to be
outside the .2% annual chance floodplain and in area D, areas in which flood hazards are
undetermined but possible. Due to the fact Arcadia does not have areas considered to be flood
prone the City does not have recurring loss properties. However, there are portions of the City
that are located within the inundation areas of three (3) dams, including the Morris S. Jones
Reservoir in East Pasadena, the Santa Anita Dam, which is located in the Angeles National
Forest above Arcadia, and the Sawpit Dam, which is located in Monrovia. See Map 7.2a for
flood inundation areas.
Risk Analysis
Risk analysis is the third and most advanced phase of a hazard assessment. It builds upon the
hazard identification and vulnerability assessment. A flood risk analysis for the City of Arcadia
should include two components: (1) the life and value of property that may incur losses from a
flood event (defined through the vulnerability assessment); and (2) the number and type of flood
events expected to occur over time. Within the broad components of a risk analysis, it is
possible to predict the severity of damage from a range of events. Flow velocity models can
assist in predicting the amount of damage expected from different magnitudes of flood events.
The data used to develop these models is based on hydrological analysis of landscape features.
Changes in the landscape, often associated with human development, can alter the flow velocity
and the severity of damage that can be expected from a flood event.
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-5
Using GIS technology and flow velocity models, it is possible to map the damage that can be
expected from flood events over time. It is also possible to pinpoint the effects of certain flood
events on individual properties.
Economic Impact
There are four dam inundation zones that impact the City of Arcadia. As mentioned in this
section, the zones are Morris S. Jones Reservoir Inundation Area, Santa Anita Dam Inundation
Area, and Sawpit Dam Inundation. The assessed valuation for the three areas are as follows:
Sawpit Dam Inundation Area $276,166,986
Santa Anita Dam Inundation Area $669,813,106
Morris Jones Reservoir $271,501,566
Community Flood Issues
What is Susceptible to Damage during a Flood Event?
The largest impact on communities from flood events is the loss of life and property. During
certain years, property losses resulting from flood damage are extensive. Property loss from
floods strikes both private and public property. Because the City of Arcadia does not lie in a
flood plain, the damage to property in the City has been minimal since incorporation.
Property Loss Resulting from Flooding Events
The type of property damage caused by flood events depends on the depth and velocity of the
flood waters. Faster moving flood waters can wash buildings off their foundations and sweep
cars downstream. Pipelines, bridges, and other infrastructure can be damaged when high waters
combine with flood debris. Extensive damage can be caused by basement flooding and landslide
damage related to soil saturation from flood events. Most flood damage is caused by water
saturating materials susceptible to loss (i.e., wood, insulation, wallboard, fabric, furnishings,
floor coverings, and appliances). In many cases, flood damage to homes renders them unlivable.
Business/Industry
Flood events impact businesses by damaging property and by interrupting business. Flood
events can cut off customer access to a business as well as close a business for repairs. A quick
response to the needs of businesses affected by flood events can help a community maintain
economic vitality in the face of flood damage. Responses to business damages can include
funding to assist owners in elevating or relocating flood-prone business structures.
Public Infrastructure
Publicly owned facilities are a key component of daily life for all citizens of the county. Damage
to public water and sewer systems, transportation networks, flood control facilities, emergency
facilities, and offices can hinder the ability of the government to deliver services. Government
can take action to reduce risk to public infrastructure from flood events, as well as craft public
policy that reduces risk to private property from flood events.
Roads
During natural hazard events, or any type of emergency or disaster, dependable road connections
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-6
are critical for providing emergency services. The Public Works Services Department maintains
roads systems in the City of Arcadia. Federal, state, county, and city governments all have a
stake in protecting roads from flood damage. Road networks often traverse floodplain and
floodway areas. Transportation agencies responsible for road maintenance are typically aware of
roads at risk from flooding.
Bridges
Bridges are key points of concern during flood events because they are important links in road
networks and can inhibit the flow of water during flood events. The bridges in the City of
Arcadia are state, county, city, or privately owned. A state-designated inspector must inspect all
state, county, and city bridges every two years; but private bridges are not inspected, and can be
very dangerous. The inspections are rigorous, looking at everything from seismic capability to
erosion and scour.
Storm Water Systems
Local drainage problems are common throughout the City of Arcadia. While the City does not
have a drainage master plan, Public Works staff is aware of local drainage threats. The problems
are often present where storm water runoff enters culverts or goes underground into storm
sewers. Inadequate maintenance can also contribute to the flood hazard in urban areas.
Water/Wastewater Treatment Facilities
There is one sanitary district that services the City of Arcadia (Los Angeles County Sanitation).
There are also four (4) water service companies and or districts in the City of Arcadia. This
number includes the water service provided to the residents by the City of Arcadia.
Wastewater Management
Arcadia's sewer system is a series of privately owned lateral connections from individual
businesses and residences, which connect to larger City-owned main lines - then to subsequently
larger trunk lines, which then take Arcadia's sanitary and industrial wastes to treatment plants
operated by the LA County Sanitation District. These wastes are treated to varying degrees and
either used for specific industrial purposes such as freeway irrigation or power (plant)
generation, or discharged in to water bodies of the State, where they flow to the Pacific Ocean.
Water Districts
All of the water districts in the City as well as the City Public Works Services Department are in
the process of replacing old cast iron pipes with more ductile iron pipes, which will be more
resilient in disaster situations. During a disaster, water districts in the region work together to
provide water for the city of Arcadia residents.
Water Quality
The City of Arcadia is committed to making sure that water from the water supply as well as
storm water, which make its way into the water conveyance system, are safe and reliable by
complying with all Federal and State water standards. The City of Arcadia water supply is
always tested to make sure there are no harmful constituents.
Local Hazard Mitigation Plan 2022
Section 7.2 Flood
7.2-7
Community Issues Summary
Flood is not a high hazard for the City of Arcadia. This statement is based on lack of a history of
flooding within the City of Arcadia along with what is depicted on the most current FEMA map.
The details from the most current FEMA map can be found on page 7.2-4 under the heading
"Flood Hazard Assessment" The City of Arcadia does not have areas considered to be flood
prone and does not have recurring loss properties.
Works Cited
i http://www.merriam-webster.com/
ii. http://www.lalc.k12.ca.us/target/units/river/tour/hist.html
iii. Gumprecht, Blake, 1999, Johns Hopkins University Press, Baltimore, MD.
iv City of Arcadia General Plan Chapter 8 Safety Element, Flooding Section
City of Arcadia
Flood Hazards Map
MAP 7-2.1
Monrovia
El Monte
Temple City
Irwindale
Sierra Madre
Pasadena
Los Angeles
County
Las Tunas Dr
Camino Real
Huntington Dr
0 1,000 2,000 3,000 4,000 Feet
Mapped by: Hogle-Ireland Inc., 2010.
Source: Federal Emergency Management Agency (FEMA),
September 26, 2008. National Flood Hazards Layer (NFHL).
FEMA Map Service Center: Web Page, <http://msc.fema.gov>
Base Map Features
City Boundary
Sphere of Influence
Freeway
Railroad
City Road
Water Feature
Flood Hazard Zones
Areas of 0.2% annual chance flood.
Areas in which flood hazards are undetermined, but possible.
Areas determined to be outside the 0.2% annual chance floodplain.
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Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-1
Definition of a Slope Failure
Slope failure, also referred to as mass wasting, is the. downslope movement of rock
debris and soil in response to gravitational stresses. Three major types of mass wasting
are classified by the type of downslope movement: falls, slides, and flows.1
Slope Failure Hazards
Slope Failure
and flows. Slope Failures can be initiated by rainfall, earthquakes, volcanic activity,
changes in groundwater, disturbance and change of a slope by fabricated construction
activities, or any combination of these factors.
The size of a Slope Failure usually depends on the geology and the initial cause of the
Slope Failure. Slope Failures vary greatly in their volume of rock and soil, the length,
width, and depth of the area affected, frequency of occurrence, and speed of movement.
Some characteristics that determine the type of Slope Failure are slope of the hillside,
moisture content, and the nature of the underlying materials. Slope Failures are given
different names, depending on the type of failure and their composition and
characteristics.
Slides move in contact with the underlying surface. These movements include rotational
slides, where sliding material moves along a curved surface, and translational slides,
where movement occurs along a flat surface. These slides are generally slow moving and
can be deep. Slumps are small rotational slides that are generally shallow. Slow-moving
Slope Failures can occur on relatively gentle slopes and can cause significant property
damage, but they are far less likely to result in serious injuries than rapidly moving Slope
Failures.2
exceeds the strength of the earth materials that compose the slope. They can move slowly
(millimeters per year), or they can move quickly and disastrously, as is the case with
debris-flows. Debris-flows can travel down a hillside of speeds up to 200 miles per hour
(more commonly, 30 50 miles per hour), depending on the slope angle, water content,
and type of earth and debris in the flow. These flows are initiated by heavy, usually
sustained, periods of rainfall, but sometimes can happen because of short bursts of
concentrated rainfall in susceptible areas. Burned areas charred by wildfires are
particularly susceptible to debris flows, given certain soil characteristics and slope
3
A debris or mudflow is a river of rock, earth, and other materials, including vegetation
that is saturated with water. This high percentage of water gives the debris flow a very
rapid rate of movement down a slope. Debris flows often with speeds greater than 20
mile per hour and can often move much faster.4 This high rate of speed makes debris
flows extremely dangerous to people and property in its path.
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-2
History of Slope Failures in Southern California
Slope Failures are a serious geologic hazard in almost every state in America. Nationally,
Slope Failures cause 25 to 50 deaths each year.5 The best estimate of direct and indirect
costs of Slope Failure damage in the United States range between $1 and $2 billion
annually.6 As a seismically active region, California has had significant number of
locations impacted by Slope Failures. Some Slope Failures result in private property
damage; other Slope Failures impact transportation corridors, fuel and energy conduits,
and communication facilities. They can also pose a serious threat to human life.
Below is a list of some of the major Slope Failures and their results in recent Southern
Californian history.
1963 Baldwin Hills Dam Failure.
On December 14, the 650-foot long by 155-foot high earth fill dam gave way and sent
360 million gallons of water in a fifty-foot high wall cascading onto the community
below, killing five persons, and damaging 50 million (1963 dollars) dollars in property.
1971 Upper and Lower Van Norman Dams, San Fernando, California
Earthquake-induced Slope Failures. Cost estimate $302.4 million (2000 dollars). Damage
due to the February 9, 1971, magnitude 7.5 San Fernando, California, earthquake. The
earthquake of February 9 severely damaged the Upper and Lower Van Norman Dams.7
1971 Juvenile Hall, San Fernando, California
Slope Failures caused by the February 9, 1971, San Fernando, California, earthquake
Cost, $266.6 million (2000 dollars). In addition to damaging the San Fernando Juvenile
Hall, this 1.2 km-long slide damaged trunk lines of the Southern Pacific Railroad, San
Fernando Boulevard, Interstate Highway 5, an electrical converter station, and several
pipelines and canals.8
1978 Bluebird Canyon Orange County, California
October 2, 1978. Cost estimate $52.7 million (2000 dollars). Sixty houses destroyed or
damaged. Unusually heavy rains in March of 1978 may have contributed to initiation of
the Slope Failure. Although the 1978 slide area was approximately 3.5 acres, it is
suspected to be a portion of a larger, ancient Slope Failure.9
1978-1979, 1980 San Diego County, California
Experienced major damage from storms in 1978, 1979, and 1979-80, as did neighboring
areas of Los Angeles and Orange County, California. One hundred and twenty Slope
Failures were reported to have occurred in San Diego County during those two years.
Rainfall for the rainy seasons of 1978-79 and 1979-80 was 14.82 and 15.61 inches (37.6
and 39.6 cm) respectively, compared to a 125-year average (1850-1975) of 9.71 inches
(24.7 cm). Significant Slope Failures occurred in the Friars Formation; a unit that was
noted as slide-prone in the Seismic Safety Study for the City of San Diego. Of the nine
Slope Failures that caused damage in excess of $1 million, seven occurred in the Friars
Formation, and two in the Santiago Formation in the northern part of San Diego
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-3
County.10
1994 Northridge, California, earthquake Slope Failures
As a result of the magnitude 6.7 Northridge, California, earthquake, more than 11,000
Slope Failures occurred over an area of 10,000 km2. Most were in the Santa Susana
Mountains and in mountains north of the Santa Clara River Valley. Destroyed dozens of
homes, blocked roads, and damaged oil-field infrastructure.
March 1995 Los Angeles and Ventura Counties, Southern California
Above normal rainfall triggered damaging debris flows, deep-seated Slope Failures, and
flooding. Several deep-seated Slope Failures were triggered by the storms, the most
notable was the La Conchita Slope Failure, which in combination with a local debris
flow, destroyed or badly damaged 11 to 12 homes in the small town of La Conchita,
about 20 km west of Ventura. There also was widespread debris-flow and flood damage
to homes, commercial buildings, and roads and highways in areas along the Malibu coast
that had been devastated by wildfire two years before.11
June 2005 Bluebird Canyon, Laguna Beach, California
In the early morning of June 1, 2005, a Slope Failure began moving in the Bluebird
Canyon area of Laguna Beach, California. No rainfall or earthquake activity occurred
during or immediately before the Slope Failure movement. This movement is almost
certainly related to the extremely heavy winter rains that occurred from December
through February. Rainfall from the winter season has been slowly percolating
downward through the soil and is gradually raising ground-water levels. As ground water
rises, slopes can become unstable and begin to move, even if no rain is presently
occurring.12
January 2005 La Conchita, California
On January 10, 2005, a Slope Failure struck the community of La Conchita in Ventura
County, California, destroying or seriously damaging 36 houses and killing 10 people.
Although rainfall intensities were not extreme, moderate- to high-intensity rainfall
persisted for more than two weeks, and the Slope Failure occurred at the culmination of
this 15-day high-rainfall period. 13
January February 2010 La Cañada Flintridge, California
Heavy winter storms hit the hills of La Cañada Flintridge in the early months of the year.
The area had already been devastated in the summer of 2009 with one of the largest
wildfires in modern history. The loss of so much vegetation combined with the downpour
of rains caused significant mudslides to the area. Over 500 homes evacuated, about fifty
homes were damaged, and another twenty were red tagged. Initial estimates of damage
were in excess of $20 million (2010 dollars).
January 2018 Montecito, CA
A heavy winter storm hit the mountains above Montecito and Carpenteria California in
January of 2018. The area had burned during the devastating Thomas Fire in December
of 2017 which burned 115,000 acres. The mudflow caused 21 reported deaths.
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-4
Approximately 163 people were hospitalized with various injuries, including four in
critical condition. The mudflows caused at least $177 million (2018 dollars) in property
damage, cost at least $7 (2018 dollars) million in emergency responses, and another $43
(2018 dollars) million to clean up.
History of Slope Failures in Cities in the San Gabriel Valley
December 2008 Sierra Madre, CA. In May 2008, over 600 acres of mountainside north
of our neighboring city of Sierra Madre burned again in the Santa Anita II Fire. Portions
of their hillside communities were inundated with mud and debris following the rains in
the winter of 2008 and 2009.
November 2013 Monrovia, CA. In May of 2013, approximately 213 acres above the
city of Monrovia were burned in the Madison Fire. In the fall of that year, the foothills of
City of Monrovia experienced mud and debris flows in the neighborhoods up against the
foothills.
November 2014 Glendora/Azusa, CA. In January of 2014, the Colby Fire burned 1,192
acres above the cities of Azusa and Glendora approximately 14 miles from the City of
Arcadia. In November and December of 2014 both communities developed mudflow
action plans and placed the plans into action and during periods of heavy rain during late
fall and winter.
November 2016 Duarte/Azusa CA. In June of 2016, the Fish Fire burned 3,700 acres
in the foothills above Duarte and Azusa, CA 4 miles from the City of Arcadia. In
November and December of 2016 both communities developed mudflow action plans
and placed the plans into action and during periods of heavy rain during late fall and
winter.
History of Slope Failures in Arcadia
January February 2000
In the wake of the December 27, 2000, Santa Anita Wildfire heavy rains brought
mudslides to the north end of Arcadia. The Arcadia City Council appropriated $334,000
to purchase K-rail, fill sandbags, clear debris basins, among numerous other costs in
response, minimal damage occurred to private properties. 14
January 2005
Heavy rainstorms triggered as many as 18 mudslides in Santa Anita Canyon, two of
which were enormous events that buried the roadway under mounds of debris. The first
major slide deposited about 6,000 cubic yards of debris on the road. A Forest Service Fire
Station had to be shut down due to lack of access and a pack station owner said that the
road closures had devastated her business financially. 15
Slope Failure Hazard Assessment
Locations at risk from Slope Failures or debris flows include areas with one or more of
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-5
the following conditions:
1. On or close to steep hills.
2. Steep road-cuts or excavations.
3. Existing Slope Failures or places of known historic Slope Failures (such sites
often have tilted power lines, trees tilted in various directions, cracks in the
ground, and irregular-surfaced ground).
4. Steep areas where surface runoff is channeled, such as below culverts, V-shaped
valleys, canyon bottoms, and steep stream channels.
5. Fan-shaped areas of sediment and boulder accumulation at the outlets of canyons.
6. Canyon areas below hillsides and mountains that have recently (within 1-6 years)
been subjected to a wildland fire.
On December 27, 1999, a fire occurred in the Angeles National Forest north of the City
of Arcadia that resulted in the burning of over 500 acres of chaparral. The U.S. Forestry
Service classified this as a medium intensity fire that burned off vegetation at the surface
level, however left the root structures intact. Initial estimates are that the natural recovery
process will take between four to ten years for full restoration of the vegetation and
chaparral.
In the interim, the burn area is barren of vegetation. The soil is composed of loose gravel
and dirt and due to burn, which creates a coating, having a water repelling effect. This
means that the normal absorption and stability of the soil is diminished. With the lack of
vegetation and water repellency of the soil, geologists and hydrologists surveying the
area forecast the likelihood of natural soil erosion and runoff with or without rainfall.
The City of Arcadia anticipated that with rainfall, flooding and mudslides were likely.
The degree of flooding or mudslides depended upon the amount and intensity of rainfall;
however, experts believe that one-half inch of rain falling over a short period of time
could be sufficient to create a problem.
Several residences were identified as being threatened to varying degrees by mudslides
and flooding due to their proximity to the mountainside and the watersheds where water
and debris naturally flowed. Furthermore, several streets possessed the potential of being
impacted by flooding, mud, and debris flow.
The Public Works Services Department created an action plan to coincide with the
overall city emergency operations plan in preparation for the anticipated flood, mud, and
debris programs.
Probability
Once a wildfire occurs the next greatest concern for the foothill community that
experiences the wildfire is a Slope Failure or debris flow when the winter rains arrive.
Looking at other data from debris flows in Los Angeles County, once a wildfire burns
through an area, that location is an area of concern for the next five years. A significant
rainstorm in the year following a wildfire creates the highest degree of probability of
Slope Failure or debris flow. This probability is directly tied to a wildfire occurring in
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-6
the months leading up to the rainy season. The communities of Monrovia, Duarte, Azusa
and Glendora, California all experienced significant Slope Failure or debris flows in the
winter months after the Madison, Fish and Colby Fires. With the foothills above Arcadia
experiencing a wildfire every 4.5 years as outlined in the Wildfire section of this report,
the probability of Slope Failure or debris flows in the fire impacted areas could also be
every 4.5 years.
Risk Analysis
Vulnerability assessment for Slope Failures will assist in predicting how different types
of property and population groups will be affected by a hazard.16 Data that includes
specific Slope Failure-prone and debris flow locations in the city can be used to assess
the population and total value of property at risk from future Slope Failure occurrences.
indicator of hill slope stability. The City uses a 20% or greater threshold to identify
potentially unstable hill slopes. The Mt. Wilson and El Monte seismic hazard maps,
which are published by the California Department of Conservation, Division of Mines,
show that the extreme northeast section of the City is the only portion of the City with the
potential for Slope Failures. Although the acreage has not been calculated, it accounts for
a very small part of the City.
While a quantitative vulnerability assessment (an assessment that describes number of
lives or amount of property exposed to the hazard) has not yet been conducted for City of
Arcadia Slope Failure events, there are many qualitative factors that point to potential
vulnerability. Slope Failures can impact major transportation arteries, blocking residents
from essential services and businesses.
Past Slope Failure events have caused property damage or significantly impacted City
residents and continuing to map City Slope Failure and debris flow areas will help in
preventing future loss.
Factors included in assessing Slope Failure risk include population and property
distribution in the hazard area, the frequency of Slope Failure or debris flow occurrences,
slope steepness, soil characteristics, and precipitation intensity. This type of analysis
could generate estimates of the damages to the City due to a specific Slope Failure or
debris flow event. At the time of publication of this plan, data was insufficient to conduct
a risk analysis and the software needed to conduct this type of analysis was not available.
To view potential areas for Slope Failures, see the Slope Failure and Debris Flow Map 7-
3
Economic Impact
The City of Arcadia has a total assessed valuation of $15,676,471,562. This can be
further broken into:
Residential properties valued at $12,959,501,963
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-7
Commercial properties valued at $1,524,210,934
Other properties valued at $ 1,192,758,665
A Slope Failure or debris flow could only affect a small portion of the City of Arcadia.
Until further studies are run, no more specific information is available.
Arcadia s Current Mitigation of Slope Failure Hazards
Slope Failures can affect utility services, transportation systems, and critical lifelines.
Communities may suffer immediate damages and loss of service. Disruption of
infrastructure, roads, and critical facilities may also have a long-term effect on the
economy. Utilities, including potable water, wastewater, telecommunications, natural gas,
and electric power, are all essential to service community needs. Loss of electricity has
the most widespread impact on other utilities and on the whole community. Natural gas
pipes as small as an inch or two may also be at risk of breaking during Slope Failure
movements.
Roads and Bridges
Losses incurred from Slope Failure hazards in the City of Arcadia have been associated
with roads. The City of Arcadia Public Works Services Department is responsible for
responding to slides that inhibit the flow of traffic or are damaging a road/bridge.
Lifelines and Critical Facilities
Lifelines and critical facilities should remain accessible, if possible, during a hazardous
event. The impact of closed transportation arteries may be increased if the closed road or
bridge is critical for hospitals and other emergency facilities. Therefore, inspection and
repair of critical transportation facilities and routes is essential and should receive high
priority. Losses of power and phone service are also potential consequences of Slope
Failure events. Due to heavy rains, soil erosion in hillside areas can be accelerated,
resulting in loss of soil support beneath high voltage transmission towers in hillsides and
remote areas. Flood events can also cause Slope Failures, which can have serious
impacts on gas lines that are located in vulnerable soils.
Slope Failure Building/Zoning Codes
building and zoning codes. The codes outline standards for development within the
hillside area of the City. Generally, the ordinance requires geotechnical and engineering
geologic studies for developments proposed on slopes of 20 percent or greater. More
detailed surface and subsurface investigations shall be warranted if indicated by the
geotechnical and geologic studies. This may include soils, vegetation, geologic
formations, and drainage patterns. Site evaluations may also occur where stability might
be lessened by proposed grading/filling or land clearing.
Residential Areas
Even minor amounts of rain and mud flow have the potential to cause extensive damage
to homes and properties. In order to assist the residents of Arcadia, the City provides free
sandbags to help in their mitigation activities.
Local Hazard Mitigation Plan 2022
Section 7.3 Slope Failure
7.3-8
Community Issues Summary
The hillsides above the residences in the WUI area of Arcadia are very steep. In the past
rainstorms following a wildland fire have created slope failures and debris flows in the
residential areas.
Works Cited
1 Geosciences, Idaho State University
3 Ibid.
4 Barrows, Alan and Smith, Ted, DMG Note 13,
http://www.consrv.ca.gov/cgs/information/publications/cgs_notes/note_33/
5 Mileti, Dennis, Disasters by Design: A Reassessment of Natural Hazards in the United
States (1999) Joseph Henry Press, Washington D.C.
6 Brabb, E.E., and B.L Harrod. (Eds) Slope Failures: Extent and Economic Significance.
Proceedings of the 28th International Geological Congress Symposium on Slope Failures.
(1989) Washington D.C., Rotterdam: Balkema.
7 Ibid.
8 Ibid
9 Ibid.
10 Ibid.
11Ibid.
12 http://www.usgs.gov/homepage/Slope Failure_laguna.asp
13 http://pubs.usgs.gov/of/2005/1067/pdf/OF2005-1067.pdf
14Pasadena Star News, Feb 24, 2000
15 Pasadena Star News, Jan 29, 2005 Pg. A1 and A4
16 Burby, R. (Ed.) Cooperating With Nature (1998) Washington D.C.: Joseph Henry
Press.
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LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-1
Definition of a Windstorm
A storm marked by high wind with little or no precipitation
Windstorm Related Hazards
Santa Ana Winds
Santa Ana winds are generally defined as warm, dry winds that blow from the east or northeast
(offshore). These winds occur below the passes and canyons of the coastal ranges of Southern
California and in the Los Angeles basin. Santa Ana winds often blow with exceptional speed in
the Santa Ana Canyon (the canyon from which it derives its name). Forecasters at the National
Weather Service offices in Oxnard and San Diego usually place speed minimums on these winds
and reserve the use of "Santa Ana" for winds greater than 25 knots.1 These winds accelerate to
speeds of 35 knots as they move through canyons and passes, with gusts to 50 or even 60 knots.
The complex topography of Southern California combined with various atmospheric conditions
creates numerous scenarios that may cause widespread or isolated Santa Ana events. Commonly,
Santa Ana winds develop when a region of high pressure builds over the Great Basin (the high
plateau east of the Sierra mountains and west of the Rocky mountains including most of Nevada
and Utah). Clockwise circulation around the center of this high-pressure area forces air down
slope from the high plateau. The air warms as it descends toward the California coast at the rate
of 5 degrees F per 1000 feet due to compressional heating. Thus, compressional heating provides
the primary source of warming. The air is dry since it originated in the desert, and it dries out
even more as it is heated.2
These regional winds typically occur from October to March, and, according to most accounts,
are named either for the Santa Ana River Valley where they originate or for the Santa Ana
Canyon, southeast of Los Angeles, where they pick up speed.
Tornados
Tornadoes are spawned when there is warm, moist air near the ground, cool air aloft, and winds
that speed up and change direction. An obstruction, such as a house, in the path of the wind
causes it to change direction. This change increases pressure on parts of the house, and the
combination of increased pressures and fluctuating wind speeds creates stresses that frequently
cause structural failures.
In order to measure the intensity and wind strength of a tornado, Dr. T. Theodore Fujita
developed the Fujita Tornado Damage Scale. This scale compares the estimated wind velocity
with the corresponding amount of suspected damage. The scale measures six classifications of
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-2
The chart below depicts the Fujita Tornado Damage Scale:
Scale
Wind
Estimate
(mph)
Typical Damage
F0 < 73 Light damage. Some damage to chimneys and TV antennas;
breaks twigs off trees; pushes over shallow-rooted trees.
F1 73-112
Moderate damage. Peels surface off roofs; windows broken; light
trailer houses pushed or overturned; some trees uprooted or
snapped; moving automobiles pushed off the road. 74 mph is the
beginning of hurricane wind speed.
F2 113-157
Considerable damage. Roofs torn off frame houses leaving strong
upright walls; weak buildings in rural areas demolished; trailer
houses destroyed; large trees snapped or uprooted; railroad
boxcars pushed over; light object missiles generated; cars blown
off highway.
F3 158-206
Severe damage. Roofs and some walls torn off frame houses;
some rural buildings completely demolished; trains overturned;
steel-framed hangar-warehouse-type structures torn; cars lifted off
the ground; most trees in a forest uprooted snapped, or leveled.
F4 207-260
Devastating damage. Whole frame houses leveled, leaving piles
of debris; steel structures badly damaged; trees debarked by small
flying debris; cars and trains thrown some distances or rolled
considerable distances; large missiles generated.
F5 261-318
Incredible damage. Whole frame houses tossed off foundations;
steel-reinforced concrete structures badly damaged; automobile-
sized missiles generated; trees debarked; incredible phenomena
can occur.
F6-
F12
319 to
sonic
Inconceivable damage. Should a tornado with the maximum wind
speed in excess of F5 occur, the extent and types of damage may
not be conceived. A number of missiles such as iceboxes, water
heaters, storage tanks, automobiles, etc. will create serious
secondary damage on structures.
Source: http://weather.latimes.com/tornadoFAQ.asp
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-3
Microbursts
Unlike tornados, microbursts are strong, damaging winds, which strike the ground and often give
the impression a tornado has struck. They frequently occur during intense thunderstorms. The
origin of a microburst is downward moving air from a thunderstorm's core. However, unlike a
tornado, they affect only a rather small area.
Tornados, like those that occur every year in the Midwest and Southeast parts of the United
States, are a rare phenomenon in most of California, with most tornado-like activity coming from
microbursts.
History of Windstorms in Southern California
While the effects of Santa Ana Winds are often overlooked, it should be noted that in 2003, two
deaths in Southern California were directly related to the fierce condition. A falling tree struck
one woman in San Diego.3 The second death occurred when a flying pickup truck cover
launched by the Santa Ana Winds hit a passenger in a vehicle.4
Windstorms in Arcadia
December 1988 - Windstorm
Fifty- to sixty-mile per hour winds blew through Arcadia. Over forty trees were uprooted, power
lines were knocked down, structures were damaged, and there was even a 150-gallon diesel fuel
spill when a semi-fuel line was ripped apart by a fallen street sign. Some residents were
left without power for days and about 200 lost telephone services. City officials said it would
take about a week to 10 days to clean up all the debris. 5
January 2003 Windstorm
Eighty- to one hundred-mile an hour winds swept through Arcadia causing major damage to the
south end of the City. Twenty-nine Edison power poles were knocked down and another six
suffered severe damage; all needing to be replaced by metal poles. More than 250,000 people
were without power. Businesses suffered damage, lost customers, and product spoiled. One
business owner said he lost over $500 in spoiled food that required refrigeration and at least
twenty-five regular customers. 6
October 2009 -Windstorm
High winds with gusts up to eighty miles per hour blew through Southern California. Although
Arcadia received less damage than some other southland cities, power lines were damaged and
caused 16,000 Edison customers in and around Arcadia to be without electricity. 7
December 2011 Windstorm
High north winds with gusts up to 70 miles per hour blew through the San Gabriel Valley. For a
period of time the entire community of Arcadia was without electrical power and many major
transportation arteries were blocked with down trees and wires. The City of Arcadia activated its
Emergency Operations Center and declared a local emergency. The EOC remained fully
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-4
activated through December 5, 2011. Many residents were without electrical service for up to
one week. The City of Arcadia opened up a warming/charging center for residents during the
event. Emergency crews worked through the first week clearing trees from roadways to gain
emergency access. Public works crews worked through January 2012 clearing debris piles in the
public right of ways. The total cost to the City of Arcadia for response to and recover from the
incident was approximately $2,800.000.
Windstorm Hazard Assessment
A windstorm event in the region can range
from short term microburst activity lasting
only minutes to a long duration Santa Ana
wind condition that can last for several days
as in the case of the January 2003 Santa Ana
wind event. Windstorms in the City of
Arcadia area can cause extensive damage
including heavy tree stands, exposed coastal
properties, road and highway infrastructure,
and critical utility facilities.
The map shows clearly the direction of
the Santa Ana winds as they travel from
the stable, high-pressure weather system
called the Great Basin High through the
canyons and towards the low-pressure
system off the Pacific. Clearly the area of
the City of Arcadia is in the direct path of the ocean-bound Santa Ana winds.
Probability
When looking at damaging wind events, it is important to look at the frequency they have
occurred in order to estimate the probability of an event taking place in the future. After the
2011 Windstorm event, Scott Sukup of the NOAA/NWS Oxnard, CA office wrote a paper titled
Downslope Wind E
strong north to NNE flow over the San Gabriel Mountain Range are a very rare phenomenon.
From October 1979 through March 2014, there were only nine events with documented wind
damage in this area. Of these nine events, the 1 December 2011 and 6 January 1997 events were
the only events to produce widespread damage across most of the foothill and valley areas south
of the SGM. It is estimated that extreme events such as these occur about once every 10-20
years, while less significant events occur once every 3-5 years.8
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-5
Risk Analysis
With an analysis of the
can deduce the common windstorm impact areas including impacts on life, property, utilities,
infrastructure, and transportation. Additionally, if a windstorm disrupts power to local
residential communities, the American Red Cross and City resources might be called
upon for care and shelter duties. Displacing residents and utilizing City resources for shelter
staffing and disaster cleanup can cause an economic hardship on the community.
Life and Property
Based on the history of the region, windstorm events can be expected, perhaps annually, across
widespread areas of the region, which can be adversely impacted during a windstorm event.
This can result in the involvement of City of A
wide-ranging windstorm or microburst tornadic activity. Both residential and commercial
structures with weak reinforcement are susceptible to damage. Wind pressure can create a direct
and frontal assault on a structure, pushing walls, doors, and windows inward. Conversely,
passing currents can create lift suction forces that pull building components and surfaces
outward. With extreme wind forces, the roof or entire building can fail causing considerable
damage. Such damage occurred to property on December 2011 when severe windstorm knocked
down power lines, disrupted traffic and electrical service.
Debris carried along by extreme winds can directly contribute to loss of life and indirectly to the
failure of protective building envelopes, siding, or walls. When severe windstorms strike a
community, downed trees, power lines, and damaged
property can be major hindrances to emergency
response and disaster recovery.
The Beaufort scale below, coined and developed by Sir Francis Beaufort in 1805, illustrates the
effect that varying wind speed can have on sea swells and structures:
Beaufort
Force
Speed
(mph) Wind Description - State of Sea - Effects on Land
0 Less 1 Calm - Mirror-like - Smoke rises vertically
1 1-3 Light - Air Ripples look like scales; No crests of foam - Smoke drift shows direction of wind, but
wind vanes do not
2 4-7 Light Breeze - Small but pronounced wavelets; Crests do not break - Wind vanes move; Leaves
rustle; You can feel wind on the face
3 8-12 Gentle Breeze - Large Wavelets; Crests break; Glassy foam; A few whitecaps - Leaves and small
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-6
twigs move constantly; Small, light flags are extended
4 13-18 Moderate Breeze - Longer waves; Whitecaps - Wind lifts dust and loose paper; Small branches
move
5 19-24 Fresh Breeze - Moderate, long waves; Many whitecaps; Some spray - Small trees with leaves begin
to move
6 25-31 Strong Breeze - Some large waves; Crests of white foam; Spray - Large branches move; Telegraph
wires whistle; Hard to hold umbrellas
7 32-38 Near Gale - White foam from breaking waves blows in streaks with the wind - Whole trees move;
Resistance felt walking into wind
8 39-46 Gale - Waves high and moderately long; Crests break into spin drift, blowing foam in well marked
streaks - Twigs and small branches break off trees; Difficult to walk
9 47-54 Strong Gale - High waves with wave crests that tumble; Dense streaks of foam in wind; Poor
visibility from spray - Slight structural damage
10 55-63 Storm - Very high waves with long, curling crests; Sea surface appears white from blowing foam;
Heavy tumbling of sea; Poor visibility - Trees broken or uprooted; Considerable structural damage
11 64-73
Violent Storm - Waves high enough to hide small and medium sized ships; Sea covered with
patches of white foam; Edges of wave crests blown into froth; Poor visibility - Seldom experienced
inland; Considerable structural damage
12 >74 Hurricane - Sea white with spray. Foam and spray render visibility almost non-existent -
Widespread damage. Very rarely experienced on land.
Source: http://www.compuweather.com/decoder-charts.html
Utilities
Historically, falling trees have been the major cause of power outages in the region. Windstorms
such as strong microbursts and Santa Ana Wind conditions can cause flying debris and downed
utility lines. For example, tree limbs breaking in winds of only 45 mph can be thrown over 75
feet. As such, overhead power lines can be damaged even in relatively minor windstorm events.
Falling trees can bring electric power lines down to the pavement, creating the possibility of
lethal electric shock. Rising population growth and new infrastructure in the region creates a
higher probability for damage to occur from windstorms as more life and property are exposed to
risk.
Infrastructure
Windstorms can damage buildings, power lines, and other property and infrastructure due to
falling trees and branches. During wet winters, saturated soils cause trees to become less stable
and more vulnerable to uprooting from high winds.
Windstorms can result in collapsed or damaged buildings or blocked roads and bridges, damaged
traffic signals, streetlights, and parks, among others. Roads blocked by fallen trees during a
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-7
windstorm may have severe consequences to people who need access to emergency services.
Emergency response operations can be complicated when roads are blocked or when power
supplies are interrupted. Industry and commerce can
suffer losses from interruptions in electric services and
from extended road closures. They can also sustain
direct losses to buildings, personnel, and other vital
equipment. There are direct consequences to the local
economy resulting from windstorms related to both
physical damages and interrupted services.
Increased Fire Threat
Perhaps the greatest danger from windstorm activity in
Southern California comes from the combination of
the Santa Ana winds with the major fires that occur
every few years in the urban/wildland interface. With
the Santa Ana winds driving the flames, the speed and
reach of the flames is even greater than in times of calm wind conditions. The higher fire hazard
raised by a Santa Ana wind condition requires that even more care and attention be paid to
proper brush clearances on property in the wildland/urban interface areas.
Transportation
Windstorm activity can have an impact on local transportation in addition to the problems caused
by downed trees and electrical wires blocking streets and highways. During periods of
extremely strong Santa Ana winds, major highways can be temporarily closed to truck and
recreational vehicle traffic. However, typically these disruptions are not long lasting, nor do they
carry a severe long-term economic impact on the region.
Existing Windstorm Mitigation in Arcadia
As stated, one of the most common problems associated with windstorms is power outage. High
winds commonly occur during winter storms, and can cause trees to bend, sag, or fail (tree limbs
or entire trees), coming into contact with nearby distribution power lines. Fallen trees can cause
short-circuiting and conductor overloading. Wind-induced damage to the power system causes
power outages to customers, incurs cost to make repairs, and in some cases can lead to ignitions
that start wild land fires.
One of the strongest and most widespread existing mitigation strategies pertains to tree
clearance. Currently, California State Law requires utility companies to maintain specific
clearances (depending on the type of voltage running through the line) between electric power
lines and all vegetation.
Enforcement of the following California Public Resource Code Sections provides guidance on
tree pruning regulations:9
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-8
4293: Power Line Clearance Required
4292: Power Line Hazard Reduction
4291: Reduction of Fire Hazards Around Buildings
4171: Public Nuisances
The following pertain to tree pruning regulations and are taken from the California Code of
Regulations:
Title 14: Minimum Clearance Provisions
Sections 1250-1258
General Industry Safety Orders
Title 8: Group 3: Articles 12, 13, 36, 37, 38
California Penal Code Section 385
Finally, the following California Public Utilities
Commission section has additional guidance:
California Public Utilities Commission
General Order 95: Rule 35
Homeowner Liability
Failure to allow a utility company to comply with the law can result in liability to the
homeowner for damages or injuries resulting from a vegetation hazard. Many insurance
companies do not cover these types of damages if the policy owner has refused to allow the
hazard to be eliminated.
The power companies, in compliance with the above regulations, collect data about tree failures
and their impact on power lines. This mitigation strategy assists the power company in preventing
future tree failure. From the collection of this data, the power company can advise residents as to
the most appropriate vegetative planting and pruning procedures.
Economic Impact
The City of Arcadia has a total assessed valuation of $15,676,471,562. This can be further
broken into:
Residential properties valued at $12,959,501,963
Commercial properties valued at $ 1,524,210,934
Other properties valued at $ 1,192,758,665
A windstorm would only influence a specific portion of the city and each event would be unique.
A more detailed projected economic impact cannot be obtained. The impact of a wind driven
wildfire will be discussed under the section devoted to a wildfire hazard.
1http://www.treesaregood.com/tree
care/avoiding_conflicts.asp
LOCAL HAZARD MITIGATION PLAN 2022
Section 7.4 WINDSTORM
7.4-9
Community Issues Summary
A windstorm within Arcadia can create local impacts with power outages in neighborhoods and
trees down blocking traffic. Major streets blocked by trees would also impact traffic within
neighboring communities. Several major power lines that feed the San Gabriel Valley run
through Arcadia and have been impacted by previous windstorms.
Works Cited:
1 http://nimbo.wrh.noaa.gov/Sandiego/snawind.html
2 Ibid
3 www.cbsnews.com, January 8, 2003
4 www.cbsnews.com/stories/2003/01/06/national/
5 Arcadia Tribune 12/11/1988 Pg A1-A2
6 Pasadena Star News 01/08/2003 Pg A1-A4
7 www.nbclosangeles.com/news/loacl-beat/Fierce-Wind-Storm-Rips-Through-Southern
8 DAMAGING DOWNSLOPE WIND EVENTS IN THE SAN GABRIEL VALLEY OF SOUTHERN
CALIFORNIA SCOTT SUKUP NOAA/NWS, Oxnard, California
9 www.cpuc.ca.gov/js.asp
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-1
Definition of a Wildfire
A sweeping and destructive conflagration especially in a wilderness or a rural area.i
Wildfire Related Hazards
There are three categories of interface fire:ii The classic wildland/urban interface exists
where well-defined urban and suburban development presses up against open expanses of
wildland areas. The mixed wildland/urban interface is characterized by isolated homes,
subdivisions, and small communities situated predominantly in wildland settings. The
occluded wildland/urban interface exists where islands of wildland vegetation occur
inside a largely urbanized area. Certain conditions must be present for significant
interface fires to occur. The most common conditions include hot, dry and windy
weather; the inability of fire protection forces to contain or suppress the fire; the
occurrence of multiple fires that overwhelm committed resources; and a large fuel load
(dense vegetation). Once a fire has started, several conditions influence its behavior,
including fuel topography, weather, drought and development.
Southern California has two distinct areas of risk for wildland fire. The foothills and
lower mountain areas are covered with scrub brush or chaparral. The higher elevations of
mountains also have heavily forested terrain. The lower elevations covered with
chaparral create one type of exposure.
The Interface
One challenge Southern California faces regarding the wildfire hazard is from the
increasing number of houses being built on the urban/wildland interface. Every year the
growing population has expanded further and further into the hills and mountains,
including forestlands. The increased "interface" between urban/suburban areas and the
open spaces created by this expansion has produced a significant increase in threats to life
and property from fires and has pushed existing fire protection systems beyond original
or current design and capability. Property owners in the interface are not aware of the
problems and threats they face. Therefore, many owners have done very little to manage
or offset fire hazards or risks on their own property. Furthermore, human activities
increase the incidence of fire ignition and potential damage.
Fuel
Fuel is the material that feeds a fire and is a key factor in wildfire behavior. Fuel is
classified by volume and by type. Volume is described in terms of "fuel loading," or the
amount of available vegetative fuel. The type of fuel also influences wildfire. Chaparral
is a primary fuel of Southern California wildfires. Chaparral communities experience
long dry summers and receive most of their annual precipitation from winter rains.
Although chaparral is often considered as a single species, there are two distinct types:
hard chaparral and soft chaparral. Within these two types are dozens of different plants,
each with its own particular characteristics.
Topography
Topography influences the movement of air, thereby directing a fire course. For
example, if the percentage of uphill slope doubles, the rate of spread in wildfire will
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-2
likely double. Gulches and canyons can funnel air and act as chimneys, which intensify
fire behavior and cause the fire to spread faster. Solar heating of dry, south-facing slopes
produces up slope drafts that can complicate fire behavior. Unfortunately, hillsides with
hazardous topographic characteristics are also desirable residential areas in many
communities. This underscores the need for wildfire hazard mitigation and increased
education and outreach to homeowners living in interface areas.
Weather
Weather patterns combined with certain geographic locations can create a favorable
climate for wildfire activity. Areas where annual precipitation is less than 30 inches per
year are extremely fire susceptible.iii High-risk areas in Southern California share a hot,
dry season in late summer and early fall when high temperatures and low humidity favor
fire activity. The so- they
flow down to Southern California from Utah, create a particularly high risk, as they can
rapidly spread what might otherwise be a small fire.
Drought
Recent concerns about the effects of climate change, particularly drought, are
contributing to concerns about wildfire vulnerability. The term drought is applied to a
period in which an unusual scarcity of rain causes a serious hydrological imbalance.
Unusually dry winters, or significantly less rainfall than normal, can lead to relatively
drier conditions and leave reservoirs and water tables lower. Drought leads to problems
with irrigation and may contribute to additional fires, or additional difficulties in fighting
fires.
Development
Growth and development in scrubland and forested areas is increasing the number of
human-made structures in Southern California interface areas. Wildfire has an effect on
development, yet development can also influence wildfire. Owners often prefer homes
that are private, have scenic views, are nestled in vegetation and use natural materials. A
private setting may be far from public roads, or hidden behind a narrow, curving
driveway. These conditions, however, make evacuation and firefighting difficult. The
scenic views found along mountain ridges can also mean areas of dangerous topography.
Natural vegetation contributes to scenic beauty, but it may also provide a ready trail of
fuel leading a fire directly to the combustible fuels of the home itself.
History of Wildfires in California
Large fires have been part of the Southern California Landscape. Five of the top ten fires
based on acreage in California have occurred since 2003. On the next page is the top ten
list.
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-3
Table 7.5-1 Ten Largest Wildfires in California Based on Acreage.
Fire Name Date County Acres
August Complex August 200
Mendocino,
Humboldt,
Trinity,
Tehama,
Glenn, Lake
& Colusa
1,032,649
Mendocino
Complex July 2018
Colusa, Lake,
Mendocino &
Glenn
459,123
SCU Lightning
Complex August 2020
Stanislaus,,
Santa Clara,
Alameda,
Contra costa,
San Joaquin 396,624
Creek Fire
September
2020
Fresno &
Madrea 377,693
LNU Lightning
Complex August 2020
Sonoma,
Lake, Napa,
Yolo &
solano
363,220
North Complex August 2020 Butte, Plumas
& Yuba 318,930
Thomas December-17
Ventura &
Santa
Barbara
287,893
Cedar October-03 San Diego 273,246
Rush August-12 Lassen
271,911 CA /
43,666 NV
Rim August-13 Tuolumne 257,314
CALFIRE 11/3/2020
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-4
History of Wildfires in and near Arcadia
Bobcat Fire
In September 2020 the Bobcat Fire began at the Cogswell Reservoir area of the Angeles
National Forest. Throughout the next week fire burned toward the City of Arcadia. One
week after the Bobcat Fire started, it had reached the ridge line directly above the City of
Arcadia. Three hundred homes were evacuated as a precaution. Due to firefighting
efforts, no homes were damaged within Arcadia. All the displaced residents were
allowed back into their homes four days later. In total the Bobcat Fire burned for more
than three weeks and consumed over 116,000 acres within the Angeles National Forest.
Santa Anita II Fire
In April 2008 the Santa Anita II Fire began on Santa Anita Canyon Road and burned
West to the foothills above Sierra Madre, CA. Over 600 acres burned, one out building
was lost, and four minor injuries to personnel fighting the fire. Over 400 people had to
be evacuated from the community of Sierra Madre as the fire raged dangerously close to
homes. The fire consumed almost 600 acres and was contained in about a week.
Madison Fire
In April 2013 the Madison Fire took place in foothills above the community of Monrovia
immediately adjacent to the City of Arcadia. When the fire was contained 213 acres had
been consumed and no property was damaged.
Colby Fire
In January of 2014 the Colby Fire took place in the foothill above the communities of
Azusa and Glendora in the East end of the San Gabriel Valley. The fire burned more
than 1,992 acres and destroyed 15 properties including 5 residences.
Fish Fire
In June of 2016 the Fish Fire broke out above the community of Duarte in the San
Gabriel Valley. 3,700 acres were burned in the fire and there was no reported damage to
structures.
Station Fire
In late August 2009, an arsonist started a fire in the hills above La Cañada Flintridge,
California. The flames raged for over two months and experts stated that the embers
wo
160,577 acres (251 sq. mi), 209 structures destroyed, including 89 homes, and the lives of
two LA County Firefighters The blaze threatened 12,000 structures in the National Forest
and the nearby communities of La Cañada Flintridge, Glendale, Acton, La Crescenta,
Littlerock and Altadena, as well as the Sunland and Tujunga neighborhoods of the City of
Los Angeles. The blaze is the 15th largest in California history.
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-5
Wildfire Hazard Assessment
Wildfire hazard areas are commonly identified in regions of the wildland/urban interface.
Ranges of the wildfire hazard are further determined by the ease of fire ignition due to
natural or human conditions and the difficulty of fire suppression. The wildfire hazard is
also magnified by several factors related to fire suppression/control such as the
surrounding fuel load, weather, topography, and property characteristics. Generally,
hazard identification rating systems are based on weighted factors of fuels, weather and
topography. Table 11.3 illustrates a rating system to identify wildfire hazard risk (with a
score of 3 equaling the most danger and a score of 1 equaling the least danger.)
Sample Hazard Identification Rating System Table Table 7.5-2
Category Indicator Rating
Roads and Signage Steep; narrow; poorly signed 3
One or two of the above 2
Meets all requirements 1
Water Supply None, except domestic 3
Hydrant, tank, or pool over 500 feet away 2
Hydrant, tank, or pool within 500 feet 1
Location of the
Structure
Top of steep slope with brush/grass below 3
Mid-slope with clearance 2
Level with lawn, or watered groundcover 1
Exterior Construction Combustible roofing, open eaves, Combustible siding 3
One or two of the above 2
Non-combustible roof, boxed eaves, non-combustible
siding
1
In order to determine the "base hazard factor" of specific wildfire hazard sites and
interface regions, several factors must be taken into account. Categories used to assess
the base hazard factor include: topographic location, characteristics, and fuels;
site/building construction and design; site/region fuel profile (landscaping); defensible
space; accessibility; fire protection response; and water availability.
The use of Geographic Information System (GIS) technology in recent years has been a
great asset to fire hazard assessment, allowing further integration of fuels, weather, and
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-6
topography data for such ends as fire behavior prediction, watershed evaluation,
mitigation strategies, and hazard mapping.
Probability
Southern California and Los Angeles County have an extensive history of wildfires.
Between 1993 and today, there have be wildland fires in the foothills of Arcadia on
numerous occasions. These include:
Year Fire Name Acerage
1993 Kinneloa 5700
1999 Santa Anita I 100
2002 Chantry Rd 11
2008 Santa Anita II 600
2009 Station Fire 160,577
2013 Madison 213
2017 Norumbega 5
2021 Chantry Flats 3
2021 Bobcat 116,000
These fires took place either above Arcadia or an immediate neighbors of Sierra Madre
and Monrovia. This averages out to a significant wildland fire once every 4.5 years.
Risk Analysis
Southern California residents are served by a variety of local fire departments as well as
county, state and federal fire resources. Data that includes the location of interface areas
in the county can be used to assess the population and total value of property at risk from
wildfire and direct these fire agencies in fire prevention and response.
Key factors included in assessing wildfire risk include ignition sources, building
materials and design, community design, structural density, slope, vegetative fuel, fire
occurrence and weather, as well as occurrences of drought. Refer to Map 7-5 to see the
wildfire hazard ratings in the City of Arcadia.
The National Wildland/Urban Fire Protection Program has developed the
Wildland/Urban Fire Hazard Assessment Methodology tool for communities to assess
their risk to wildfire. For more information on wildfire hazard assessment refer to
http://www.Firewise.org.
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-7
Growth and Development in the Interface
The hills and mountainous areas of Southern California are considered to be interface
areas. The development of homes and other structures is encroaching onto the wildland
and is expanding the wildland/urban interface. The interface neighborhoods are
characterized by a diverse mixture of varying housing structures, development patterns,
ornamental and natural vegetation and natural fuels.
In the event of a wildfire, vegetation, structures and other flammables can merge into
unwieldy and unpredictable events. Factors important to the fighting of such fires
include access, firebreaks, proximity of water sources, distance from a fire station and
available firefighting personnel and equipment. Reviewing past wildland/urban interface
fires shows that many structures are destroyed or damaged for one or more of the
following reasons: Combustible roofing material; Wood construction; Structures with no
defensible space; Fire department with poor access to structures; Subdivisions located in
heavy natural fuel types; Structures located on steep slopes covered with flammable
vegetation; Limited water supply; and Winds over 30 miles per hour.
Economic Impact
The assess valuation of the Wildland Interface Area is $829,408,125.00. This is for all of
the properties located in the Interface area as depicted on Map 7-5. A fire impacting the
area on a small scale would obviously result in less of an economic impact.
Current Mitigation in Arcadia
Buildings
Often times the reason structures are lost or damaged in wildland urban interface fires is
due to wood shake roof coverings. The City of Arcadia Municipal Code 8130.18 has been
implemented to reduce the risk of fire to structures in the City.
Arcadia Municipal Code 8130.18
The roof covering on any structure regulated by this code shall have a minimum
class A rating in the Wildland Interface Fire Area Boundaries and a class A or B
rating in all other areas outside the Wildland Interface Fire Area Boundaries of
the City. Pressure treated or untreated wood shakes and wood shingles shall not
be installed on any building or structure located in the Wildland Interface Fire
Area Boundaries. (See Map 7-5).
The City of Arcadia implements Title 19 California Health and Safety Code and the City
of Arcadia Municipal Codes to ensure the fire safety in building construction and
materials.
Equipment
The Arcadia Fire Department has outfitted all of their stations with new engines capable
of producing Compressed Air Foam systems (CAFs). CAFs enable firefighters to pre-
treat homes with retardant foam in the event of a fire nearby. It also enables firefighters
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-8
to extinguish fires using less water, thus putting less demand on an already inundated
water system.
Operations
On Red Flag Warning days the Arcadia Fire Department often staffs extra personnel and
makes patrols in areas with high probability of wildfire ignition.
In the event a wildland fire does occur in or around the City of Arcadia the Fire
Department has created a Brush and Structure Pre-Fire Plan. The plan includes maps of
the City with vital information required for operations on a wildland fire. Information
includes but is not limited to: location of hydrants, potential staging areas, potential
command posts, safe refuge zones, schools, and other critical information for use in the
event of a wildland urban interface fire in or near the City of Arcadia.
Road Access
Road access is a major issue for all emergency service providers. As development
encroaches into the rural areas of the county, the number of houses without adequate
turn-around space is increasing. In many areas, there is not adequate space for
emergency vehicle turnarounds in single-family residential neighborhoods, causing
emergency workers to have difficulty doing their jobs because they cannot access houses.
As fire trucks are large, firefighters are challenged by narrow roads and limited access,
when there is inadequate turn around space, the fire fighters can only work to remove the
occupants, but cannot safely remain to save the threatened structures. However, pre-
planning, evacuation notices, and road closures help to assist firefighters with mobility in
the event of a fire.
Water Supply
Firefighters in remote and rural areas are faced by limited water supply and lack of
hydrant taps. Rural areas are characteristically outfitted with small diameter pipe water
systems, inadequate for providing sustained firefighting flows.
In the City of Arcadia all new water main lines are eight inch and fire hydrant laterals are
six inch. However, older pipes that were installed years ago do not meet the size
standards and may be only four inches. Older pipes are upgraded as funds become
available or as an opportunity arises and are addressed in sections of our Water Master
Plan. They are also addressed completely in Section 7 (Domestic Water System) in City
Water Standards. Replacement of older pipes is ongoing. Fire hydrants in Arcadia are
spaced at 300 feet in both commercial and residential areas. Though there are some areas
where spacing is greater, Public Works adds hydrants and adjusts spacing as lines are
replaced. Most hydrants in the City are supplied at about one hundred psi. However, the
City has a minimum pressure of twenty psi that each hydrant is to be supplied at all times.
The water system is gravity fed and will supply water to hydrants for at least two hours in
the event the City is without power.
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-9
Interface Fire Education Programs and Enforcement
The biggest concern during a wildland urban interface fire is loss of life and property.
Mitigation of loss to life and property begins with the residents and their pre-plans. To
assist the residents in planning for a wildland urban interface fire the Arcadia Fire
Department implemented an Annual Brush Clearance Program. The program begins by
mailing a pamphlet detailing fire hazard reduction and safety guidelines. The pamphlet
includes information about maintaining a defensible space, use of fire resistive building
materials, planning escape routes, and preparations in the event of a fire near their home.
The program is continued by Fire Department inspections of homes. Every May,
firefighters asses the defensible space and specific hazards in order to further mitigate
loss of life and property. The inspections also help to familiarize firefighters with the area
to further assist them in the event of a fire.
The Arcadia Fire Department Prevention Bureau has also produced various public safety
announcements about smoke alarms, wildfire safety, holiday safety, and the use of fire
extinguishers. The videos are played on the Arcadia City channel and are designed to
help educate the public on fire safety.
Federal Programs
The role of the federal land managing agencies in the wildland /urban interface is
reducing fuel hazards on the lands they administer; cooperating in prevention and
education programs; providing technical and financial assistance; and developing
agreements, partnerships and relationships with property owners, local protection
agencies, states and other stakeholders in wildland/urban interface areas. These
relationships focus on activities before a fire occurs, which render structures and
communities safer and better able to survive a fire occurrence.
Federal Emergency Management Agency (FEMA) Programs, FEMA is directly
responsible for providing fire suppression assistance grants and, in certain cases, major
disaster assistance and hazard mitigation grants in response to fires. The role of FEMA in
the wildland /urban interface is to encourage comprehensive disaster preparedness plans
and programs, increase the capability of state and local governments and provide for a
greater understanding of FEMA programs at the federal, state and local levels.iv
U.S. Forest Service
The U. S. Forest Service (USFS) is involved in a fuel-loading program implemented to
assess fuels and reduce hazardous buildup on forestlands. The USFS is a cooperating
agency and, while it has little to no jurisdiction in the lower valleys, it has an interest in
preventing fires in the interface, as fires often burn up the hills and into the higher
elevation US forest lands.
Other Mitigation Programs and Activities
Some areas of the country are facing wildland/urban issues collaboratively. These are
model programs that include local solutions. Summit County, Colorado, has developed a
hazard and risk assessment process that mitigates hazards through zoning requirements.
In California, the Los Angeles County Fire Department has retrofitted more than 100 fire
Local Hazard Mitigation Plan 2022
Section 7.5 Wildfires
7.5-10
engines with fire retardant foam capability and Orange County is evaluating a pilot
insurance grading and rating schedule specific to the wildland/urban interface. All are
examples successful programs that demonstrate the value of pre-suppression and
prevention efforts when combined with property owner support to mitigate hazards
within the wildland/urban interface.
Community Issues Summary
Radio repeater sites are in the WUI area of Arcadia. These serve radios within Arcadia
and neighboring communities. There are four reservoir locations within the WUI area of
Arcadia
Works Cited
i http://www.merriam-webster.com/
ii Planning for Natural Hazards: The Oregon Technical Resource Guide, (July
2000) Department of Land Conservation and Development
iii Planning for Natural Hazards: The Oregon Technical Resource Guide, (July
2000), Department of Land Conservation and Development
iv Source: National Interagency Fire Center, Boise ID and California Division of
Forestry, Riverside Fire Lab.
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Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-1
Definition of Drought
There are four different ways that drought can be defined:
Meteorological a measure of departure of precipitation from normal. Due to climatic
differences, what is considered a drought in one location may not be a drought in another
location.
Agricultural refers to a situation when the amount of moisture in the soil no longer meets the
needs of a particular corp.
Hydrological occurs when surface and subsurface water supplies are below normal.
Socioeconomic refers to the situation that occurs when physical water shortage begins to affect
people.
Location of Impact
Drought has the potential to impact all areas of the City of Arcadia.
Concept of Drought
Drought is an insidious hazard of nature. Although it has different definitions, it originates from
a deficiency of precipitation over an extended period of time, usually a season or more. This
deficiency results in a water shortage for some activity, group, or environmental sector. Drought
should be considered relative to some long-term average condition of balance between
precipitation and evapo-transpiration (i.e., evaporation + transpiration) in a particular area, a
condition often percei
occurrence, delays in the start of the rainy season, occurrence of rains in relation to principal
crop growth stages) and the effectiveness of the rains (i.e., rainfall intensity, number of rainfall
events). Other climatic factors such as high temperature, high wind, and low relative humidity
are often associated with it in many regions of the world and can significantly aggravate its
severity. Drought should not be viewed as merely a physical phenomenon or natural event. Its
impacts on society result from the interplay between a natural event (less precipitation than
expected resulting from natural climatic variability) and the demand people place on water
supply. Human beings often exacerbate the impact of drought. Recent droughts in both
developing and developed countries and the resulting economic and environmental impacts and
A five-year drought has parched soils, lowered reservoirs and weakened forests. If the past is
any guide, the dry spell could go on for decades.
One dry year does not normally constitute a drought in California, but serves as a reminder of the
need to pl its
reservoirs, groundwater basins, and inter-regional conveyance facilities mitigates the effect of
short-term dry periods for most water users. Hydrologic conditions constituting a drought for
water users in one location may not constitute a drought for water users elsewhere, or for water
users having a different water supply. Individual water suppliers may use criteria such as
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-2
rainfall/runoff, amount of water in storage, or expected supply from a water wholesaler to define
their water supply conditions.
Drought is a gradual phenomenon. Although droughts are sometimes characterized as
emergencies, they differ from typical emergency events. Most natural disasters, such as floods
or forest fires, occur relatively rapidly and afford little time for preparing for disaster response.
Droughts occur slowly, over a multiyear period. There is no universal definition of when a
drought begins or ends. Impacts of drought are typically felt first by those most reliant on annual
rainfall ranchers engaged in dry land grazing, rural residents relying on wells in low-yield rock
formations, or small water systems lacking a reliable source. Criteria used to identify statewide
drought conditions do not address these localized impacts. Drought impacts increase with the
length of a drought, as carry-over supplies in reservoirs are depleted and water levels in
groundwater basins decline.
Past California Droughts
Droughts exceeding three years are relatively rare in Northern California, the source of much of
-34 drought established the criteria commonly
used in designing storage capacity and yield of large Northern California reservoirs.
reconstruct data through the study of tree rings (called dendrochronology). Information on the
thickness of annual growth rings can be used to infer the wetness of the season. Site-specific
approaches to supplementing the historical record can include age-dating dry land plant remains
now submerged in place by rising water levels, or sediment and pollen studies. For example, a
1994 study of relict tree stumps rooted in present-day lakes, rivers, and marshes suggested that
California sustained two epic drought periods, extending over more than three centuries. The
first epic drought lasted more than two centuries before the year 1112; the second drought lasted
more than 140 years before 1350. In this study, the researcher used drowned tree stumps rooted
in Mono Lake, Tenaya Lake, West Walker River, and Osgood Swamp in the central Sierra
Nevada. These investigations indicate that California has been subject to droughts more severe
and more prolonged than those witnessed in the brief historical record.
Between 1986 and 1992, California endured one of its longest droughts ever observed. Drought
worsened in 1988 as much of the United States also suffered from severe drought. In California,
the six-year drought ended in late 1992 after a significant El Niño event.
Between 2007 and 2009, California saw three years of drought conditions, the 12th worst
drought period in the state's history, and the first drought for which a statewide proclamation of
emergency was issued. This period of drought also saw greatly reduced water diversions from
the state water project. The summer of 2007 saw some of the worst wildfires in Southern
California history
Between 2011 and 2017 California was in a statewide drought. In January 2014, California
Governor Brown issued a drought emergency proclamation. The actions taken by the City of
Arcadia during this time period are
section later in this document.
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-3
Extent of Drought
The Drought Severity Classification Table below describes the significance of each drought
category
Source: https://www.weather.gov/riw/drought_index
The following maps show the extent of drought between 2015 and 2020. The City of Arcadia is
located in Los Angeles County in the State of California. Los Angeles County is circled in each
map. The maps can be found at: https://droughtmonitor.unl.edu/Maps/MapArchive.aspx.
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-4
2015
https://droughtmonitor.unl.edu/Maps/MapArchive.aspx
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-5
2017
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-6
2020
Impacts of Drought
Drought produces a complex web of impacts that spans many sectors of the economy and
reaches well beyond the area experiencing physical drought. This complexity exists because
water is integral to our ability to produce goods and provide services.
Impacts are commonly referred to as direct or indirect. Reduced crop, rangeland, and forest
productivity; increased fire hazard; reduced water levels; increased livestock and wildlife
mortality rates; and damage to wildlife and fish habitat are a few examples of direct impacts. The
consequences of these impacts illustrate indirect impacts. For example, a reduction in crop,
rangeland, and forest productivity may result in reduced income for farmers and agribusiness,
increased prices for food and timber, unemployment, reduced tax revenues because of reduced
expenditures, increased crime, foreclosures on bank loans to farmers and businesses, migration,
and disaster relief programs. Direct or primary impacts are usually biophysical. Conceptually
speaking, the more removed the impact from the cause, the more complex the link to the cause.
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-7
In fact, the web of impacts becomes so diffuse that it is very difficult to come up with financial
estimates of damages. The impacts of drought can be categorized as economic, environmental, or
social.
Many economic impacts occur in agriculture and related sectors, including forestry and fisheries,
because of the reliance of these sectors on surface and subsurface water supplies. In addition to
obvious losses in yields in both crop and livestock production, drought is associated with
increases in insect infestations, plant disease, and wind erosion. Droughts also bring increased
problems with insects and diseases to forests and reduce growth. The incidence of forest and
range fires increases substantially during extended droughts, which in turn places both human
and wildlife populations at higher levels of risk.
Income loss is another indicator used in assessing the impacts of drought because so many
sectors are affected. Reduced income for farmers has a ripple effect. Retailers and others who
provide goods and services to farmers face reduced business. This leads to unemployment,
increased credit risk for financial institutions, capital shortfalls, and loss of tax revenue for local,
state, and federal government. Less discretionary income affects the recreation and tourism
industries. Prices for food, energy, and other products increase as supplies are reduced. In some
cases, local shortages of certain goods result in the need to import these goods from outside the
stricken region. Reduced water supply impairs the navigability of rivers and results in increased
transportation costs because products must be transported by rail or truck. Hydropower
production may also be curtailed significantly.
Environmental losses are the result of damages to plant and animal species, wildlife habitat, and
air and water quality; forest and range fires; degradation of landscape quality; loss of
biodiversity; and soil erosion. Some of the effects are short-term and conditions quickly return
to normal following the end of the drought. Other environmental effects linger for some time or
may even become permanent. Wildlife habitat, for example, may be degraded through the loss
of wetlands, lakes, and vegetation. However, many species will eventually recover from this
temporary aberration. The degradation of landscape quality, including increased soil erosion,
may lead to a more permanent loss of biological productivity of the landscape. Although
environmental losses are difficult to quantify, growing public awareness and concern for
environmental quality has forced public officials to focus greater attention and resources on these
effects.
Social impacts mainly involve public safety, health, conflicts between water users, reduced
quality of life, and inequities in the distribution of impacts and disaster relief. Many of the
impacts specified as economic and environmental have social components as well. Population
out-migration is a significant problem, often stimulated by greater availability of food and water
elsewhere. Migration is usually to urban areas within the stressed area or to regions outside the
drought area; migration may even be to adjacent countries, creating refugee problems. However,
when the drought has abated, these persons seldom return home, depriving rural areas of
valuable human resources necessary for economic development. For the urban area to which
they have immigrated, they place ever-increasing pressure on the social infrastructure, possibly
leading to greater poverty and social unrest.
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-8
Probability of Drought
Probability is the likelihood of a hazard occurring in the future. The graph below shows
approximately four droughts between 2000 and 2020 in Los Angeles County. The drought
between
2014-2017 was severe.
Source: National Weather Service https://droughtmonitor.unl.edu/Data/Timeseries.aspx
Below is a table listing the frequency and severity of drought in Los Angeles County. Based on
the table, Los Angeles County has experienced three years of Exceptional Drought in the past 20
years. Therefore, the County has the potential to experience an Exceptional Drought once every
6.7 years. Climate change might increase or decrease this probability in the future.
Year Drought Condition Year Drought Condition
2001 None 2011 None
2002 Moderate Drought 2012 Moderate Drought
2003 Abnormally Dry 2013 Severe Drought
2004 Abnormally Dry 2014 Exceptional Drought
2005 None 2015 Exceptional Drought
2006 Abnormally Dry 2016 Exceptional Drought
2007 Severe Drought 2017 Abnormally Dry
2008 Moderate Drought 2018 Severe Drought
2009 Severe Drought 2019 Abnormally Dry
2010 None 2020 Abnormally Dry
https://droughtmonitor.unl.edu/Maps/MapArchive.aspx
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-9
On the site listed above National Weather Service Forecast Offices were used for the Area Type
and Los Angeles, CA (LOX) was used as the Area. The data compared the readings from the
first week in December between 2001 and 2020.
r
Raymond Basin and direct delivery of treated imported water from Metropolitan Water District.
The reliability of the water supply for the City is primarily dependent upon the management of
the Main San Gabriel Basin and Raymond Basin. The management of both basins is based on
their adjudication. The City pumps groundwater from both basins and can rely on the water
supply sources of both basins in an average water year, a single-dry water year and during
multiple-dry water years.
California Drought Legislation
The State of California delegates drought planning to local authorities. However, in light of the
current drought conditions for the past three (3) years, the California Legislature passed Senate
Bill 7x-7 of 2009, and the Governor signed it into law in November 2009. This comprehensive
step towards ensuring a reliable water supply for future generations, as well as restoring the
Sacramento-San Joaquin Delta and other ecologically sensitive areas. More importantly, the law
is directed at water conservation and includes the requirement that the State reduce urban per
capita water use by twenty (20) percent by the year 2020.
Mitigating drought taking actions in advance of drought to reduce its long-term risk can
involve a wide range of tools. These tools include policies, activities, plans, and programs.
The California Urban Water Management Planning Act, which became effective on January 1,
1985, requires every Urban Water Supplier to prepare and adopt an Urban Water Management
Plan and to periodically review its Management Plan every five (5) years and make any
amendments or changes which are indicated by review. The primary objective of the Act is to
direct urban water suppliers to evaluate their existing water conservation efforts and, to the
extent practicable, to review and implement alternative and supplemental water conservation
measures. As such, the City has adopted and implemented the Urban Water Management Plan
and continues to update it on a regular basis as required by law.
This Management Plan details demand management measures implemented by the City to
increase and encourage water conservation in the community. Many demand management
measures are in cooperation with the Upper San Gabriel Valley Municipal Water District in
In the event of a water shortage or water emergency, the City has also established a Water
Conservation Plan (Plan) in the Arcadia Municipal Code:
ARTICLE VII. - PUBLIC WORKS,
CHAPTER 5. - WATER RATES, SERVICE CHARGES AND REGULATIONS
Local Hazard Mitigation Plan 2022
Section 7.6 Drought
7.6-10
PART 5. - REGULATIONS
DIVISION 3. - WATER CONSERVATION PLAN
The Plan is intended for the conservation of available water supply to minimize the adverse
impacts of a drought or water supply emergency conditions. Specifically, the Plan implements
water rationing in eight (8) phases, reducing water usage by a certain percentage in each phase.
To further mitigate the impacts of drought, the City is also exploring conservation pricing in
order to encourage and enhance water conservation efforts.
claration, the
Arcadia City Council adopted Resolution No. 7009 in February 2014 to implement a voluntary
Water Conservation Program to reduce water use by 20 percent. After several months of voluntary
conservation Statewide, the target reduction percentage was far from being met. Therefore, in July
2014, the State Water Resources Control Board adopted emergency water conservation regulations
consisting of the following elements: water restrictions on outdoor water use for all Californians;
a requirement that water suppliers implement their Water Shortage Contingency Plans; and the
requirement that water suppliers provide monthly data on water production.
In order to comply with the regulations, the Arcadia City Council adopted Resolution No. 7044 on
These regulations
are still in effect as of the writing of this plan.
Community Issues Summary
The City of Arcadia has its own water company and draws water from the water table beneath
the community. A prolonged drought may impact our ability to obtain water from the aquifer. A
prolonged drought would also change the susceptibility of the wildland fuel bed surrounding the
north end of Arcadia making it more prone to a wildfire.
Local Hazard Mitigation Plan 2022
Section 8 Human Caused Hazards
8
When developing the Local Hazard Mitigation Plan for the City of Arcadia, the
committee decided to place the hazards into two broad categories. The categories are
Natural Hazards and Human Caused Hazards. Section 8 of the plan covers Human
Caused Hazards. The hazards are:
Section 8.1 Hazardous Materials Release
Section 8.2 Terrorism Event
Section 8.3 Train Accident
All data tables and maps included in this section were updated during the revision of this
plan.
Local Hazard Mitigation Plan 2022
Section 8.1 Hazardous Materials Release
8.1-1
Description of Hazard
Hazardous waste/materials are widely used at and/or created by facilities such as hospitals,
wastewater treatment plants, water treatment plants and industrial manufacturing warehouses.
Several household products such as cleaning supplies and paint are also considered hazardous
materials. Hazardous materials include:
Explosives
Flammable, nonflammable, and poisonous gases
Flammable liquids
Flammable, spontaneously combustible, and dangerous when wet solids
Oxidizers and organic peroxides
Poisons and infectious substances
Radioactive materials
Corrosive materials.
Both mobile and external hazardous materials releases can spread and affect a wide area, through
the release of plumes of chemical, biological, or radiological elements or leaks or spills.
Conversely, internal releases are more likely to be confined to the structure the material is stored
in. Chemical may be corrosive or otherwise damaging over time. A hazardous materials release
could also result in fire or explosion. Contamination may be carried out of the immediate area of
the incident by people, vehicles, wind, and water. Weather conditions can increase the size and
intensity of the hazardous materials release. Topography such as h hills and canyons can
increase the size of the release or make it more difficult to contain.
Location and Extent of Hazard in Arcadia
Over 160 business owners within Arcadia are required to submit a hazardous materials business
plan with the local Certified Unified Program Agencies. In addition to being present at known
businesses, hazardous materials are transported within and through Arcadia on a daily basis.
History of Hazardous Materials Releases in Arcadia
Most releases that have occurred in Arcadia have been minor releases and easily mitigated in
compliance with industry standards in accordance with State and Federal regulations. There
have been no significant historical events to report to date.
Local Hazard Mitigation Plan 2022
Section 8.2 Terrorism Event
8.2-1
Description of Hazard
There is no single, universally accepted definition of terrorism, and it can be interpreted in many
ways. The term usually refers to intentional, criminal malicious acts. Terrorism is defined in the
Code of Federal
persons or property to intimidate or coerce a government, the civilian population , or any
or the
purposes of this plan, terrorism refers to the use of weapons of mass destruction, including
biological, chemical, nuclear, and radiological weapons; arson, incendiary, explosive, and armed
attacks; and industrial sabotage and intentional hazardous materials releases. Many of these
incidents can be well-planned, coordinated attacks with multiple suspects, or the result of a lone
individual on a rampage.
Location and Extent of Hazard
Terrorism can occur throughout the entire city but due to terrori
most likely happen in more populous areas where more devastation, hear, and chaos will ensue
History of Terrorism Events in Arcadia
The city has little-to-no experience of terrorist events.
Local Hazard Mitigation Plan 2022
Section 8.3 Train Accident
8.3-1
Definition of Train Accident
Train accidents are defined as any accidents involving public or private trains carrying
passengers or cargo along the rail corridor. Train accidents, like other transportation accidents,
are less likely to lead to a state or federal disaster declaration, than other hazards previously and
afore mentioned.
Train Accident Related Hazards
In September 2015, train service was re-established in the City of Arcadia. The Los Angeles
County Metropolitan Transit Authority extended a light rail commuter line through Arcadia
connecting communities in the eastern San Gabriel Valley with Downtown Los Angeles.
Train accidents are localized, and the incidents result in limited impacts at the community level.
However, if the train is in a highly populated death and injuries can occur.
With the exception of the light rail line, no other rail lines run through the City of Arcadia. The
closest freight line is the Burlington Northern Santa Fe Railway located 4 miles south of Arcadia
in the City of El Monte.
Train Accident Hazard Assessment
There is only one at grade crossing for the light rail train running through the City of Arcadia. A
portion of the light rail in Arcadia is located in the center divider of the 210 Freeway.
Neighboring communities have had a few events involving big rig trucks that have come off the
210 Freeway and ended up on the train tracks
Train accidents can occur anytime during the year.
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-1
The following action items have been placed into three categories based on the Local
Hazard Mitigation Plan Committees recommendations. The LHMP Committee
considered ease, cost, and importance of completion. The following three categories rank
the achievability of each action item; category one action items being the action items to
be completed first, and respectively category three being the last.
Category One
Wildfire A
Continue to maintain a separation between flammable vegetation and structures within
the Wildland Urban Interface.
Implementation Ideas:
Continue annual brush safety inspections
Adopt new standards on building construction for hardening of structures in the
wildland urban interface.
Look into funding options for vegetation clearance on public infrastructure in the
wildland-urban interface
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Ongoing
Constraints: Funding
Wildfire B
Work with partner agencies to limit the threat of a wind driven wildland fire to the
community.
Implementation Ideas:
Incorporate SCE Public Safety Power Shutoff plans and grid maps into City of Arcadia
Base Map.
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Ongoing
Constraints: Funding
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-2
Earthquake A
Work to ensure minimal interruption in city services in the event of an earthquake
Implementation Ideas
Integrate Earthquake Early Warning Systems into Fire Station Alerting
Integrate Earthquake Early Warning Systems into operation of city water wells and
pumping stations
Secure equipment within City facilities to protect employees and citizens.
Coordinating Organization Public Works Services / Fire Department
Funding Source Operating Budget / Mitigation Grants
Timeline Ongoing
Constraints Funding
Earthquake B
Adopt and enforce current building safety and seismic regulations
Implementation Ideas
Adopt and incorporate new versions of Building and Fire Codes
Coordinating Organization Fire Department / Development Services
Funding Source Operating Budget
Timeline During next code update cycle
Constraints None
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-3
Multi Hazard A
Create and maintain communication mediums through which the City can communicate
with the public on both an outgoing and incoming basis.
Implementation Ideas:
Continue to Update and Enhance methods to communicate with the public. Look
into process to be able to provide Wireless Emergency Alerts to the community.
Coordinating Organization: City Manager s Office
Funding:
Office, Fire Department, Police Department, Public Works
Services Department
Timeline: Ongoing
Constraints: Staff time
Multi Hazard B
Work on lessening the impact a loss of electrical power would have on the community.
Implementation Ideas:
Update and maintain the back-up power that is available for key city
infrastructure in the event of a power disruption to windstorm, wildfire,
earthquake, etc.
Coordinating Organization: City of Arcadia Public Works Services
Funding Source: Public Works
Timeline: Within the next three years
Constraints: Cost associated with purchasing equipment.
Category Two
Slope Failure A
Improve the capabilities of managing debris from Slope Failure events by developing a
debris management strategy for the City of Arcadia.
Ideas for implementation:
Work with L.A. County Department of Public Works on establishing a regional
Debris Management Plan.
Coordinating Organization: City of Arcadia Public Works Services. L.A. County
Department of Public Works
Funding Source: Public Work Agencies
Timeline: Within the next three years
Constraints: Limited staff time,
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-4
Windstorm A
Identify and implement projects to reduce the damage caused by trees during a
windstorm.
Ideas for Implementation:
Continue regular tree trimming procedures:
o Continue four-year tree trimming grid for optimum effectiveness to
maintain healthy trees.
o Ensure trees in the public right-of-way are trimmed to maintain a clearance
from all electric power lines as specified in the California Code of
Regulations and the California Public Utilities Commission
o Continue to remove trees that are dead, diseased, or dying.
o Continue the Crown Restoration Program to preserve the health of large
aging trees
o Ensure proper tree trimming techniques as approved by the Professional
Arborist Association
o Provide public education materials to residents to make them aware of the
need to regularly maintain and trim their own trees
o Update Urban Forest Master Plan to include type of trees to plant, when to
plan, where easement trees will be placed, and how and when they will be
maintained.
Coordinating Organization: Public Works Services Department
Funding Source: General Fund and Gas Tax
Timeline: Ongoing
Constraints: Limited staff time and capital resources to fund
Tree Trimming Contractors
Hazardous Materials A
Reduce the threat of a Hazardous Materials Release in Arcadia.
Implementation Ideas:
Provide information to residents on Local Household Hazardous Materials
Collection Events
Update known hazardous material storage locations.
Coordinating Organization: Fire Department
Funding Source: Fire Department
Timeline: Annually
Constraints: Staff time for updating policies
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-5
Terrorism A
Lessen the impact that a terrorist event would have city infrastructure.
Implementation Ideas:
Strengthen City Facilities and Networks to prevent physical and cyber attacks
Coordinating Organization: Police Department
Funding Source: General Fund, Police, Fire, and Public Works budgets
Timeline: One year
Constraints: Limited staff time
Terrorism B
Lessen the impact that a terrorist event would have on the community.
Implementation Ideas:
Develop a Stop the Bleed Campaign and provide stop the bleed materials in City
Buildings
Coordinating Organization: Fire Department
Funding Source: General Fund, Grants budgets
Timeline: One year
Constraints: Limited staff time
Transportation A
Reduce the frequency of vehicle coming into contact with Metro Gold Line Train while
travelling along with 210 Freeway
Implementation Ideas:
Work with CALTRANS to aid in increasing the height of the barrier wall
separating the Gold Line right of way from the 210 Freeway to protect the light
rail right of way from vehicles losing control and ending up on the tracks.
Coordinating Organization: Development Services Department
Funding Source: State of California
Timeline: Within next three years
Constraints: Lengthy approval process
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-6
Category Three
Drought A
Identify and implement projects to reduce the impact of drought.
Implementation Ideas:
Conserve water resources by:
o Improving leak detection capability of the Public Works Services Staff
o Continuing to provide water audits for indoor/outdoor uses
o
in the future
o Funding Capital Improvement Projects to improve the reliability and
o Develop and implement a Tiered Water Rate Pricing Structure
Coordinating Organization: Public Works Services Department
Funding Source: Water Fund (revenue generated from billing for water
service)
Timeline: Short Term (within the next five years)
Constraints: Limited staff time, resistance from public and lack of
public participation.
Capability Assessment
carry out mitigation efforts.
The capabilities are divided into the four categories of Planning and Regulatory,
Administrative and Technical, Financial and, Education and Outreach.
Planning and Regulatory
Plans
Yes/No
Year
Does the plan address hazards? Does the
plan identify projects to include in the
mitigation strategy? Can the plan be used
to implement mitigation actions?
City Master Plan (General Plan)
Yes
2010 Safety element of plan discusses hazards
Capital Improvement Plan
Yes
2020
Plan can be used to implement mitigation
actions
Economic Development Plan
Yes
2010 No
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-7
Local Emergency Operations Plan
Yes
2013 The EOP address various hazards
Continuity of Operations plan No
Transportation Plan Yes Does not address hazards
Stormwater Management Plan
Yes
2015 Yes
Community Wildfire Protection Plan No
Building Code, Permitting and Inspections
Yes/No
Year Are Codes Adequately enforced?
Building Code
Yes
2019 Yes
Building Code Effectiveness grading schedule
(BCEGS) Score
Yes
2019 Score is 2 for residential and commercial
Fire Department ISO Rating
Yes
2018 Class I rating
Land Use Planning and Ordinances
Yes/No
Year
Is the ordinance an effective measure for
reducing hazard impacts? Is the ordinance
adequately administered and enforced?
Zoning Ordinance Yes Yes, yes
Subdivision Ordinance Yes Yes, Yes
Natural hazard specific ordinance
(stormwater, steep slope, wildfire) Yes Yes, yes
Floor Insurance Rate Maps No City does not participate in program.
How can Planning and Regulatory be expanded? This can be expanded by incorporating
the plan into the upcoming General Plan update.
Administrative and Technical
Administrative Yes/No
Describe capability. Is coordination
effective?
Planning Commission Yes
Mitigation Planning Committee Yes
Consists of representatives from each city
department
Maintenance programs to reduce
risk (e.g., tree trimming, clearing
drainage systems) Yes Arcadia Public Works have plans in place.
Mutual aid agreements Yes
Fire and Law have automatic and mutual aid
agreements in place. Coordination is
effective.
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-8
Staff
Yes/No
FT/PT
Is staffing adequate to enforce regulations?
Is staff trained on hazards and mitigation?
Is coordination between agencies and staff
effective?
Chief Building Official Yes FT Yes
Emergency Manager Yes PT Staff is trained and coordination takes place
Community Planner Yes FT
Civil Engineer Yes FT
GIS Coordintor Yes PT
Staff from various departments handle GIS
needs for their respective departments
Technical Yes/No
Describe capability. Has capability been
used to assess/mitigate risk in the past?
Warning systems/services
(Reverse 911, outdoor warning
signals) Yes
Reverse 911. System has been used to
educate, warn and evacuate public.
Grant writing Yes
City staff has been assigned to apply for
grants. City staff can apply for FEMA
mitigation grants and other funding to be
used for mitigation activities.
HAZUS analysis No
How can these capabilities be expanded and improved to reduce risk? One method to
increase in the above area is to get a dedicated GIS coordinator within the city to make
the data easily available to all staff. These GIS capabilities can be used for mitigation
planning, grant applications and coordination.
Financial
Funding Resource
Access /
Eligibility
(Yes/No)
Has the funding resource been
used in the past and for what
type of activities? Could the
resource be used to fund future
mitigation actions?
Capital improvements project
funding Yes
Funding used for annual
maintenance projects, drought
mitigation and wildfire response
equipment
Authority to levy taxes for
specific purposes Yes
Fees for water, sever, gas or
electric services. Yes
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-9
Impact fees for new
development No
Incur debt through general
obligation bonds and/or special
tax bonds Yes
Obligation bond passed for build
grade separation for light rail
commuter line.
Community Development Block
Grant Yes
Other federal funding programs Yes SHSGP Recipient
How can these capabilities be expanded and improved to reduce risk? One method to use
is to pursue additional grant opportunities for mitigation activities.
Education and Outreach
Program/Organization Yes/No
Describe program/organization
and how relates to disaster
resilience and mitigation. Could
the program/organization help
implement future mitigation
activities?
Local citizen group or non-profit
organizations focused on
environmental protection,
emergency preparedness, access
and functional needs
populations, etc. Yes
City partners with American Red
Cross for preparedness
outreaches
Ongoing public education or
information program (e.g.
responsible water use, fire
safety, household preparedness,
environmental education) Yes
Public education is conducted
through social media, city
newsletters, safety
demonstrations and information
tables at city events.
Natural disaster or safety related
school programs Yes
City annually participates in
Great Shakeout with community
partners
Firewise Communities
certification No
How can these capabilities be expanded and improved to reduce risk? One way to
expand and/or improve would be to look into opportunities to educate the public on the
hazards present in the community and ways individuals can mitigate those hazards to
protect their homes and businesses.
Local Hazard Mitigation Plan 2022
Section 9 Action Items
9-10
Local Hazard Mitigation Plan 2022
Section 10 Plan Maintenance Process
10-1
The plan maintenance section of this document details the formal process that will ensure
Local Hazards Mitigation Plan remains an active and relevant
document. The plan maintenance process includes a schedule for monitoring and
evaluating the Plan annually and producing a plan revision every five years. This section
describes how the city will integrate public participation throughout the plan maintenance
process. Finally, this section includes an explanation of
government intends to incorporate the mitigation strategies outlined in this Plan into
existing planning mechanisms such as the City General Plan, Capital Improvement Plans,
and Building and Safety Codes.
Monitoring and Implementing the Plan
Plan Adoption
The City Manager or designee will be responsible for submitting it to the State Hazard
Mitigation Officer at The California Office of Emergency Services (CAL OES). CAL
OES will then submit the plan to the Federal Emergency Management Agency (FEMA)
for review. This review will address the federal criteria outlined in FEMA Interim Final
Rule 44 CFR Part 201. Upon acceptance by FEMA, The City Council will be
This
governing body has the authority to promote sound public policy regarding local hazards.
Coordinating Body
The
coordinating implementation of Plan action items and undertaking the formal review
process. The City Manager will assign representatives to the Hazard Mitigation
Committee and assign a Project Manager.
Convener
Hazard Mitigation Committee will take responsibility for plan implementation. The
Project Manager will serve as a convener to facilitate the Hazard Mitigation Committee
meetings, and will assign tasks such as updating and presenting the Plan to the members
of the committee. Plan implementation and evaluation will be a shared responsibility
among all of the Local Hazard Committee Members.
Implementation through Existing Programs
The City of Arcadia addresses statewide planning goals and legislative requirements
through its General Plan, Capital Improvement Plans, City Building and Safety Codes
and other city documents. The Local Hazard Mitigation Plan provides a series of
recommendations - many of which are closely related to the goals and objectives of
existing planning programs.
The 2012 Local Hazard Mitigation Plan was referenced in the 2013 update of the City of
adopted/referenced into any other City of Arcadia plans since its 2012 adoption.
Local Hazard Mitigation Plan 2022
Section 10 Plan Maintenance Process
10-2
During fiscal year 2021
will be updated. At that time staff will work toward adopting the Local Hazard
Mitigation Plan into the Safety Element.
The goals and action items in the mitigation plan may be achieved through activities
recommended in the city's Capital Improvement Plans (CIP). Various city departments
develop CIP plans, and review them on an annual basis.
Economic Analysis of Mitigation Projects
FEMA's approaches to identify the costs and benefits associated with natural hazard
mitigation strategies, measures, or projects fall into two general categories: benefit/cost
analysis and cost-effectiveness analysis.
Conducting benefit/cost analysis for a mitigation activity can assist communities in
determining whether a project is worth undertaking now, in order to avoid disaster-
related damages later.
Cost-effectiveness analysis evaluates how best to spend a given amount of money to
achieve a specific goal. Determining the economic feasibility of mitigating natural
hazards can provide decision-makers with an understanding of the potential benefits and
costs of an activity, as well as a basis upon which to compare alternative projects.
Given federal funding, the City of Arcadia will use a FEMA-approved benefit/cost
analysis approach to identify and prioritize mitigation action items. For other projects
and funding sources, the Hazard Mitigation Advisory Committee will use other
approaches to understand the costs and benefits of each action item and develop a
prioritized list. For more information regarding economic analysis of mitigation action
items, please see Appendix A of the Plan.
Evaluating and Updating the Plan
Formal Review Process
Local Hazards Mitigation Plan will be evaluated on an annual basis
to determine the effectiveness of programs, and to reflect changes in land development or
programs that may affect mitigation priorities. The evaluation process includes a firm
schedule and time line, and identifies the local agencies and organizations participating in
plan evaluation. The convener or designee will be responsible for contacting the Hazard
Mitigation Advisory Committee members and organizing the annual meeting.
The committee will review the goals and action items to determine their relevance to
changing situations in the city, as well as changes in State or Federal policy, and to
ensure they are addressing current and expected conditions. The committee will also
review the risk assessment portion of the Plan to determine if this information should be
updated or modified, given any new available data. The coordinating organizations
responsible for the various action items will report on the status of their projects, the
Local Hazard Mitigation Plan 2022
Section 10 Plan Maintenance Process
10-3
success of various implementation processes, difficulties encountered, success of
coordination efforts, and which strategies should be revised.
Continued Public Involvement
The City of Arcadia is dedicated to involving the public directly in review and updates of
the Local Hazard Mitigation Plan.
The public will also have the opportunity to provide feedback about the Plan. Copies of
the Plan will be catalogued and kept at all of the appropriate agencies in the city. The
existence and location of these copies will be publicized in the quarterly city newsletter
"Arcadia Community News", which reaches every household in the city
In addition, copies of the plan and any proposed changes will be posted on the city
website. This site will also contain an email address and phone number to which people
can direct their comments and concerns.
A public meeting will also be held after each annual evaluation or when deemed
necessary by the City Manager. The meetings will provide the public a forum for which
they can express its concerns, opinions, or ideas about the Plan.
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-1
Benefit/cost analysis is a key mechanism used by the California Office of Emergency Services,
the Federal Emergency Management Agency, and other state and federal agencies in evaluating
hazard mitigation projects, and is required by the Robert T. Stafford Disaster Relief and
Emergency Assistance Act, Public Law 93-288, as amended.
This appendix outlines several approaches for conducting economic analysis of natural hazard
mitigation projects. It describes the importance of implementing mitigation activities, different
approaches to economic analysis of mitigation strategies, and methods to calculate costs and
benefits associated with mitigation strategies. Information in this section is derived in part from:
The Interagency Hazards Mitigation Team, State Hazard Mitigation Plan, (Oregon State Police
Office of Emergency Management, 2000), and Federal Emergency Management Agency
Publication 331, Report on Costs and Benefits of Natural Hazard Mitigation.
This section is not intended to provide a comprehensive description of benefit/cost analysis, nor
is it intended to provide the details of economic analysis methods that can be used to evaluate
local projects. It is intended to one (1) raise benefit/cost analysis as an important issue, and two
(2) provide some background on how economic analysis can be used to evaluate mitigation
projects.
Why Evaluate Mitigation Strategies?
Mitigation activities reduce the cost of disasters by minimizing property damage, injuries, and
the potential for loss of life, and by reducing emergency response costs, which would otherwise
be incurred.
Evaluating the Local Hazard Mitigation Plan provides decision-makers with an understanding of
the potential benefits and costs of an activity, as well as a basis upon which to compare
alternative projects. Evaluating mitigation projects is a complex and difficult undertaking, which
is influenced by many variables. First, natural disasters affect all segments of the communities
they strike, including individuals, businesses, and public services such as fire, police, utilities,
and schools.
Second, while some of the direct and indirect costs of disaster damages are measurable, some of
the costs are non-financial and difficult to quantify in dollars. Third, many of the impacts of such
-
social and economic consequences.
While not easily accomplished, there is value, from a public policy perspective, in assessing the
positive and negative impacts from mitigation activities, and obtaining an instructive benefit/cost
comparison. Otherwise, the decision to pursue or not pursue various mitigation options would
not be based on an objective understanding of the net benefit or loss associated with these
actions.
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-2
What are Some Economic Analysis Approaches for Mitigation Strategies?
The approaches used to identify the costs and benefits associated with natural hazard mitigation
strategies, measures, or projects fall into two general categories: benefit/cost analysis and cost-
effectiveness analysis. The distinction between the two methods is the way in which the relative
costs and benefits are measured. Additionally, there are varying approaches to assessing the
value of mitigation for public sector and private sector activities.
Benefit/Cost Analysis
Benefit/cost analysis is used in local hazard mitigation to show if the benefits to life and property
protected through mitigation efforts exceed the cost of the mitigation activity. Conducting
benefit/cost analysis for a mitigation activity can assist communities in determining whether a
project is worth undertaking now, in order to avoid disaster related damages later. Benefit/cost
analysis is based on calculating the frequency and severity of a hazard, avoided future damages,
and risk.
In benefit/cost analysis, all costs and benefits are evaluated in terms of dollars, and a net
benefit/cost ratio is computed to determine whether a project should be implemented (i.e., if net
benefits exceed net costs, the project is worth pursuing). A project must have a benefit/cost ratio
greater than one in order to be pursued.
Cost-Effectiveness Analysis
Cost-effectiveness analysis evaluates how best to spend a given amount of money to achieve a
specific goal. This type of analysis, however, does not necessarily measure costs and benefits in
terms of dollars. Determining the economic feasibility of mitigating hazards can also be
organized according to the perspective of those with an economic interest in the outcome. Hence,
economic analysis approaches are covered for both public and private sectors as follows.
Investing in public sector mitigation activities
Evaluating mitigation strategies in the public sector is complicated because it involves estimating
all of the economic benefits and costs regardless of who realizes them, and potentially to a large
number of people and economic entities. Some benefits cannot be evaluated monetarily, but still
affect the public in profound ways. Economists have developed methods to evaluate the
economic feasibility of public decisions that involve a diverse set of beneficiaries and nonmarket
benefits.
Investing in private sector mitigation activities
Private sector mitigation projects may occur on the basis of one of two approaches: it may be
mandated by a regulation or standard, or it may be economically justified on its own merits. A
building or landowner, whether a private entity or a public agency, required to conform to a
mandated standard may consider the following options: Request cost sharing from public
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-3
agencies; Dispose of the building or land either by sale or demolition; Change the designated use
of the building or land and the hazard mitigation compliance requirement; Evaluate the most
feasible alternatives and initiate the most cost effective hazard mitigation alternative.
The sale of a building or land triggers another set of concerns. For example, real estate
disclosure laws can be developed which require sellers of real property to disclose known
defects and deficiencies in the property, including earthquake weaknesses and hazards to
prospective purchasers. Correcting deficiencies can be expensive and time consuming,
but their existence can prevent the sale of the building. Conditions of a sale regarding the
deficiencies and the price of the building can be negotiated between a buyer and seller.
How can an Economic Analysis be Conducted?
Benefit/cost analysis and cost-effectiveness analysis are important tools in evaluating whether or
not to implement a mitigation activity. A framework for evaluating alternative mitigation
activities is outlined below:
1. Identify the Alternatives: Alternatives for reducing risk from natural hazards can
include structural projects to enhance disaster resistance, education and outreach, and
acquisition or demolition of exposed properties, among others. Different mitigation
project can assist in minimizing risk to hazards, but do so at varying economic costs.
2. Calculate the Costs and Benefits: Choosing economic criteria is essential to
systematically calculating costs and benefits of mitigation projects and selecting the most
appropriate alternative. Potential economic criteria to evaluate alternatives include:
- Determine the project cost: This may include initial project development costs,
and repair and operating costs of maintaining projects over time.
- Estimate the benefits: Projecting the benefits or cash flow resulting from a
project can be difficult. Expected future returns from the mitigation effort depend
on the correct specification of the risk and the effectiveness of the project, which
may not be well known. Expected future costs depend on the physical durability
and potential economic obsolescence of the investment. This is difficult to
project. These considerations will also provide guidance in selecting an
appropriate salvage value. Future tax structures and rates must be projected.
Estimating the costs and benefits of a hazard mitigation strategy can be a complex process.
Employing the services of a specialist can assist in this process.
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-4
Financing alternatives must be researched, and they may include retained
earnings, bond and stock issues, and commercial loans.
- Consider costs and benefits to society and the environment: These are not easily
measured, but can be assessed through a variety of economic tools including
existence value or contingent value theories. These theories provide quantitative
data on the value people attribute to physical or social environments. Even
without hard data, however, impacts of structural projects to the physical
environment or to society should be considered when implementing mitigation
projects.
- Determine the correct discount rate: Determination of the discount rate can just
be the risk-ime
preference and also a risk premium. Inflation should also be considered.
3. Analyze and Rank the Alternatives: Once costs and benefits have been quantified,
economic analysis tools can rank the alternatives. Two methods for determining the best
alternative given varying costs and benefits include: net present value and internal rate of
return.
- Net present value: Net present value is the value of the expected future returns
dollars. If the net present value is greater than the project costs, the project may be
determined feasible for implementation. Selecting the discount rate, and
identifying the present and future costs and benefits of the project calculates the
net present value of projects.
- Internal Rate of Return: Using the internal rate of return method to evaluate
mitigation projects provides the interest rate equivalent to the dollar returns
expected from the project. Once the rate has been calculated, it can be compared
to rates earned by investing in alternative projects. Projects may be feasible to
implement when the internal rate of return is greater than the total costs of the
project.
Once the mitigation projects are ranked on the basis of economic criteria, decision-
makers can consider other factors, such as risk; project effectiveness; and economic,
environmental, and social returns in choosing the appropriate project for implementation.
How are Benefits of Mitigation Calculated?
Economic Returns of Local Hazard Mitigation
The estimation of economic returns, which accrue to building or land owners as a result of
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-5
natural hazard mitigation, is difficult. Owners evaluating the economic feasibility of mitigation
should consider reductions in physical damages and financial losses. A partial list follows:
- Building damages avoided
- Content damages avoided
- Inventory damages avoided
- Rental income losses avoided
- Relocation and disruption expenses avoided
ded
These parameters can be estimated using observed prices, costs, and engineering data. The
difficult part is to correctly determine the effectiveness of the hazard mitigation project and the
resulting reduction in damages and losses. Equally as difficult is assessing the probability that an
event will occur. The damages and losses should only include those that will be borne by the
owner. The salvage value of the investment can be important in determining economic
feasibility. Salvage value becomes more important as the time horizon of the owner declines.
This is important because most businesses depreciate assets over a period of time.
Additional Costs of Disasters
Property owners should also assess changes in a broader set of factors that can change as a result
negative, and include changes in the following:
- Commodity and resource prices
- Availability of resource supplies
- Commodity and resource demand changes
- Building and land values
- Capital availability and interest rates
- Availability of labor
- Economic structure
- Infrastructure
- Regional exports and imports
- Local, state, and national regulations and policies
- Insurance availability and rates
Changes in the resources and industries listed above are more difficult to estimate and require
models that are structured to estimate total economic impacts. Total economic impacts are the
sum of direct and indirect economic impacts. Total economic impact models are usually not
combined with economic feasibility models. Many models exist to estimate total economic
impacts of changes in an economy. Decision makers should understand the total economic
impacts of natural disasters in order to calculate the benefits of a mitigation activity. This
suggests that understanding the local economy is an important first step in being able to
understand the potential impacts of a disaster, and the benefits of mitigation activities.
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-6
Additional Considerations
Conducting an economic analysis for potential mitigation activities can assist decision-makers in
choosing the most appropriate strategy for their community to reduce risk and prevent loss from
natural hazards. Economic analysis can also save time and resources from being spent on
inappropriate or unfeasible projects. Several resources and models are listed on the following
page that can assist in conducting an economic analysis for hazard mitigation activities.
Benefit/cost analysis is complicated, and the numbers may divert attention from other important
issues. It is important to consider the qualitative factors of a project associated with mitigation
that cannot be evaluated economically. There are alternative approaches to implementing
mitigation projects. Many communities are looking towards developing multi-objective projects.
With this in mind, opportunity rises to develop strategies that integrate local hazard mitigation
with projects related to watersheds, environmental planning, community economic development,
and small business development, among others. Incorporating natural hazard mitigation with
other community projects can increase the viability of project implementation.
Assessed Values of City of Arcadia
The total assessed value for the City of Arcadia is $15,676,471,562. The nine hazards that could
impact the City of Arcadia, would affect the city in various ways. Of all the hazards, only two
would impact a specific area. Wildfire and Flooding. Four separate impact areas were looked at.
One for the wildfire impact area and three separate dam inundation areas.
Earthquake, Windstorm, Drought, Terrorism, Transportation, Debris Flow/Landslide, and
Hazardous Materials Release hazards have the potential to impact any or all areas of the City of
Arcadia so there was no separate study completed for those areas. The chart below indicated the
assessed value in the City of Arcadia broken into entire city, residential property, commercial
property and other. The chart also displays the assessed valuation in the dam inundation areas
and the wildfire hazard area.
Area
Assessed
Valuation
Entire City 15,676,471,562
Residential 12,959,501,963
Commercial 1,524,210,934
Other 1,192,758,665
Sawpit Dam Inundation Area 276,166,986
Sierra Madre & Santa Anita Dam Inundation Area 669,813,106
Morris S. Jones Reservoir Inundation Area 271,501,566
Wildland Interface 829,408,125
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-7
Resources
CUREe Kajima Project, Methodologies For Evaluating The Socio-Economic Consequences Of
Large Earthquakes, Task 7.2 Economic Impact Analysis, Prepared by University of California,
Berkeley Team, Robert A. Olson, VSP Associates, Team Leader; John M. Eidinger, G&E
Engineering Systems; Kenneth A. Goettel, Goettel and Associates Inc.; and Gerald L. Horner,
Hazard Mitigation Economics Inc., 1997.
Federal Emergency Management Agency, Benefit/Cost Analysis of Hazard Mitigation Projects,
Riverine Flood, Version 1.05, Hazard Mitigation Economics Inc., 1996.
Federal Emergency Management Agency Report on Costs and Benefits of Natural Hazard
Mitigation. Publication 331, 1996.
Goettel & Horner Inc., Earthquake Risk Analysis Volume III: The Economic Feasibility of
Seismic Rehabilitation of Buildings in The City of Portland, Submitted to the Bureau of
Buildings, City of Portland, August 30, 1995.
Goettel & Horner Inc., Benefit/Cost Analysis of Hazard Mitigation Projects Volume V,
Horner, Gerald, Benefit/Cost Methodologies for Use in Evaluating the Cost Effectiveness of
Proposed Hazard Mitigation Measures, Robert Olson Associates, Prepared for Oregon State
Police, Office of Emergency Management, July 1999.
Interagency Hazards Mitigation Team, State Hazard Mitigation Plan, (Oregon State Police
Office of Emergency Management, 2000).
Risk Management Solutions, Inc., Development of a Standardized Earthquake Loss Estimation
Methodology, National Institute of Building Sciences, Volume I and II, 1994.
VSP Associates, Inc., A Benefit/Cost Model for the Seismic Rehabilitation of Buildings,
Volumes 1 & 2, Federal Emergency Management Agency, FEMA, Publication Numbers 227 and
228, 1991.
VSP Associates, Inc., Benefit/Cost Analysis of Hazard Mitigation Projects: Section 404 Hazard
Mitigation Program and Section 406 Public Assistance Program, Volume 3: Seismic Hazard
Mitigation Projects, 1993.
Local Hazard Mitigation Plan 2022
Economic Analysis
APPENDIX A
Appendix A-8
VSP Associates, Inc., Seismic Rehabilitation of Federal Buildings: A Benefit/Cost Model,
Volume 1, Federal Emergency Management Agency, FEMA, Publication Number 255, 1994.
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-1
This list is taken from the Emergency Management Glossary from the California Office
of Emergency Services Website.
A - B
A&W - Alert and Warning
AA - Administering Agency
AAR - After Action Report
AFN - Access & Functional Needs
AFO - Area Field Office
ANG - Army National Guard
AO - Administrative Order
AR - Atmospheric River
ARB - Air Resources Board
ARC - American Red Cross
ARP - Accidental Risk Prevention
ATC-20 - Applied Technology Council-20
ATC-21 - Applied Technology Council-21
BCP - Budget Change Proposal
BOC - Business Operations Center
BSA - California Bureau of State Audits
C
CA-ESF - California Emergency Support Function
CAER - Community Awareness & Emergency Response
CalARP - California Accidental Release Prevention
CalBO - California Building Officials
CalEPA - California Environmental Protection Agency
CalREP - California Radiological Emergency Plan
CalSCIP California Statewide Communications Interoperability Plan
CalSIEC California Statewide Interoperability Executive Committee
CALSTARS - California State Accounting Reporting System
CARES - California Animal Response Emergency System
CalTRANS - California Department of Transportation
CBO - Community Based Organization
CCC - California Conservation Corps
CD - Civil Defense
CDE - California Department of Education
CDF - California Department of Forestry and Fire Protection
CDFA - California Department of Forest & Agriculture
CDHS California Department of Health Services
CDMG - California Division of Mines and Geology
CDPH - California Department of Public Health
CDSS - California Department of Social Services
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-2
CEC - California Energy Commission
CEPEC - California Earthquake Prediction Evaluation Council
CESRS - California Emergency Services Radio System
CGD - California Geological Survey
CHIP - California Hazardous Identification Program
CHMIRS - California Hazardous Materials Incident Reporting System
CHP - California Highway Patrol
CLETS - California Law Enforcement Telecommunications System
CMD - California Military Department
CMAS California Multiple Award Schedules
CNG California National Guard
CONOPS - Continuity of Operations
COOP - Continuity of Operations Plan
CSTI - California Specialized Training Institute
CSWC California State Warning Center
CTD Communications and Technology Development Division (of OES)
CUEA - California Utilities Emergency Association
CUPA - Certified Unified Program Agency
D
DAD - Disaster Assistance Division (of the state Office of Emergency Svcs)
DFO - Disaster Field Office
DCPP - Diablo Canyon Power Plant
DGS - California Department of General Services
DGS-PD Dept General Services Procurement Division
DGS-TD Dept. General Services Telecommunications Division
DHS Federal Department of Homeland Security
DHS-RHB - California Department of Health Services, Radiological Health Branch
DMORT Disaster Mortality Assistance Team
DO - Duty Officer
DOC - Department Operations Center
DOD - Department of Defense
DOE - Department of Energy (U.S.)
DOF - California Department of Finance
DOJ - California Department of Justice
DPA - California Department of Personnel Administration
DPH - Department of Public Health
DPIG - Disaster Preparedness Improvement Grant
DR - Disaster Response
DRCC - Disaster Recovery Center
DRCC Disaster Resistant California Conference
DSA - Division of the State Architect
DSR - Damage Survey Report
DSS - Department of Social Services
DSW - Disaster Service Worker
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-3
DSTC CA Department of Toxic Substance Control
DWR - California Department of Water Resources
E - H
EAS - Emergency Alerting System
EDIS - Emergency Digital Information System
EDO - Executive Duty Officer
EERI - Earthquake Engineering Research Institute
EF - Emergency Function
EMA - Emergency Management Assistance
EMAC Emergency Management Assistance Compact
EMAP - Emergency Management Accreditation Program
EMI - Emergency Management Institute
EMMA - Emergency Managers Mutual Aid
EMPG Emergency Management Performance Grant
EMS - Emergency Medical Services
EO - Executive Order
EOC - Emergency Operations Center
EOP - Emergency Operations Plan
EPA - Environmental Protection Agency (U.S.)
EPEDAT - Early Post Earthquake Damage Assessment Tool
EPI - Emergency Public Information
EPIC - Emergency Public Information Council
ESC - Emergency Services Coordinator
ESF - Emergency Support Function
FAY - Federal Award Year
FCO Federal Coordinating Officer
FDAA - Federal Disaster Assistance Administration
FEAT -
FEMA - Federal Emergency Management Agency
FFY - Federal Fiscal Year
FIR - Final Inspection Reports
FIRM - Flood Insurance Rate maps
FIRESCOPE - Firefighting Resources of California Organized for Potential
Emergencies
FMA - Flood Management Assistance
FMAG Fire Management Assistance Grant
FSA - Federal Staging Area
FSR - Feasibility Study Report
FY - Fiscal Year
GEOEC
GIS - Geographical Information System
GOAR
GO-BIZ - California Governor's Office of Business & Economic Development
HAZMAT - Hazardous Materials
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-4
HAZMIT - Hazard Mitigation
HAZUS - Hazards-United States (an earthquake damage assessment prediction tool)
HCD - Housing and Community Development
HEICS - Hospital Emergency Incident Command System
HEPG - Hospital Emergency Planning Guidance
HIA - Hazard Identification & Analysis Unit
HMEP - Hazardous Materials Emergency Preparedness
HMGP - Hazard Mitigation Grant Program
HSEEP Homeland Security Exercise and Evaluation Program
HSGP Homeland Security Grant Program
I - O
IA - Individual Assistance
IAP - Incident Action Plan
IDE - Initial Damage Estimate
IC - Incident Commander
ICE - U.S. Immigration &Customs Enforcement
ICP Incident Command Post
ICS - Incident Command System
IFG - Individual & Family Grant (program)
IPA - Information and Public Affairs (of state Office of Emergency Services)
IHP - Individuals & Households Program
IMAT - Incident Management Assistance Team
IND - Improvised Nuclear Device
IOF - Initial Operating Facility
IRG - Incident Response Geographic Information System
IRT Incident Response Team
JEOC Joint Emergency Operations Center
JFO Joint Field Office
JIC Joint Information Center
JIS - Joint Information System
JRIES Joint Regional Information Exchange System
LAC Local Assistance Center
LAN - Local Area Network
LEMA - Law Enforcement Mutual Aid
LEPC - Local Emergency Planning Committee
LEVS Law Enforcement and Victims Services Branch (of OES)
MAC Group - Multiagency Coordination Group
MARAC - Mutual Aid Regional Advisory Council
MHID - Multi-hazard Identification
MHOAC - Medical Health Operational Area Coordinator
MOA - Memorandum of Agreement
MOU - Memorandum of Understanding
NBC - Nuclear, Biological, Chemical
NDRF - National Disaster Recovery Framework
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-5
NEMA - National Emergency Management Agency
NEMIS - National Emergency Management Information System
NFIP - National Flood Insurance Program
NGO - Non-Governmental Organization
NIMS - National Incident Management System
NIMSCAST - National Incident Management System Compliance Assistance Support
Tool
NOAA - National Oceanic and Atmospheric Association
NPP - Nuclear Power Plant
NRF - National Response Framework
NSF - National Science Foundation
NWS - National Weather Service
OA - Operational Area
OASIS - Operational Area Satellite Information System
OCC - Operations Coordination Center
OCD - Office of Civil Defense
OCJP Office of Criminal Justice Planning
OEP - Office of Emergency Planning
OES -
OHS Homeland Security
OPI Office of Public Information (of OES)
ORT - Operational Readiness Team
OSHPD - Office of Statewide Health Planning and Development
OSPR - Oil Spill Prevention and Response
P - R
PA - Public Assistance
PC - Personal Computer
PDA - Preliminary Damage Assessment
PFO Principle Federal Official
PIO - Public Information Officer
POD - Point of Distribution
POST - Police Officer Standards and Training
PPA/CA - Performance Partnership Agreement/Cooperative Agreement (FEMA)
PRA Public Records Act
PSA - Public Service Announcement
PSC - Public Safety Communications (OES)
PSRSPC Public Safety Radio Strategic Planning Committee
PSPS - Public Safety Power Shutoff
PTAB - Planning and Technological Assistance Branch
PTR - Project Time Report
PUC - Public Utilities Comission
RA - Regional Administrator (OES)
RADEF - Radiological Defense (program)
RAMP - Regional Assessment of Mitigation Priorities
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-6
RAPID - Railroad Accident Prevention & Immediate Deployment
RDD - Radiological Dispersal Device
RDMHS - Regional Disaster Medical Health Coordinator
RDO - Radiological Defense Officer
RDMHC - Regional Disaster Medical Health Coordinator
REOC - Regional Emergency Operations Center
REPI - Reserve Emergency Public Information
RES - Regional Emergency Staff
RIMS - Response Information Management System
RMP - Risk Management Plan
RPU - Radiological Preparedness Unit (OES)
RRCC - Regional Response Coordination Center
RRT - Regional Response Team
RSF - Recovery Support Function
RTTAC Regional Terrorism Threat Assessment Center
S - W
SA - Special Agent
SAA State Authorized Agency
SAM - State Administrative Manual
SAP - Safety Assessment Program
SAR - Search & Rescue
SARA - Superfund Amendments & Reauthorization Act
SAVP - Safety Assessment Volunteer Program
SBA - Small Business Administration
SCO -
SCO State Coordinating Officer
SEP - State Emergency Plan
SEMS - Standardized Emergency Management System
SEPIC - State Emergency Public Information Committee
SESC - Senior Emergency Services Coordinator
SHSGP State Homeland Security Grant Program
SITREP - Situation Report
SLA - State and Local Assistance
SOC - State Operations Center
SONGS - San Onofre Nuclear Generating Station
SOP - Standard Operating Procedure
SPR - Stakeholder Preparedness Review
SSA - Supervisory Special Agent
SSA - State Staging Area
STAC - State Threat Assessment Center
STTAC State Terrorism Threat Assessment Center
SWAT - Special Weapons & Tactics
SWEPC - Statewide Emergency Planning Committee
TA - Technical Assistance
Local Hazard Mitigation Plan 2022
Acronyms
Appendix B
Appendix B-7
T&E Training and Exercise
TEC - Travel Expense Claim
THIRA - Threat Hazards & Identification Risk Assessment
TICP Tactical Interoperable Communications Plan
TLO - Terrorism Liaison Officer
TRU - Transuranic
TTT - Train the Trainer
TTX - Tabletop Exercise
UASI - Urban Area Security Initiative
UC - Unified Command
UCG - Unified Coordination Group
UOC - Utilities Operations Center
UPA - Unified Program Account
UPS - Uninterrupted Power Source
USA - United States Army
USAF - United States Air Force
USBP - United States Border Patrol
USCG - United States Coast Guard
USDOT - United States Department of Transportation
USFS - United States Forest Service
USGAO - United States Government Accountability Office
USMC - United States Marine DCorps
USN - United States Navy
USAR - Urban Search and Rescue
USGS - United States Geological Survey
VAL - Volunteer Agency Liasion
VOAD - Voluntary Organizations Active in Disasters
WAR Week Ahead Report
WAN - Wide Area Network
WIPP - Waste Isolation Pilot Project
WSCA - Western States Contracting Alliance
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX L
LOS ANGELES COUNTY ALL-HAZARD MITIGATION
PLAN
Page 1 of 204
2025 County of Los Angeles
All-Hazards Mitigation Plan
Chief Executive %SœJN -%SœJN of Emergency Management
Page 1 of 204
County of Los Angeles
All-Hazards Mitigation Plan
Page 1 of 204
Acknowledgement
The Los Angeles County Board of Supervisors gratefully acknowledges the following
agencies/jurisdictions who contributed to the development of this plan.
County Departments
Aging and Disabilities
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Beaches and Harbors
Economic Opportunity
Health Services
Human Resources
Parks and Recreation
Public Health
Public Social Services
Public Works
Regional Planning
Fire (LACoFD)
Internal Services
Sheriff (LASD)
Disaster Management Area Coordinators
State of California
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California State Council on Developmental Disabilities (SCCD)
External Partners
Access Services
Alzheimer’s Association
Catholic Charities
City of Beverly Hills
City of Long Beach
Disability Community Resource Center
Eastern Los Angeles Regional Center
Emergency Network Los Angeles
Habitat for Humanity
Harbor Regional Center
Lanterman Regional Center
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Los Angeles County Sanitation Districts
Los Angeles County Metropolitan
Transportation Authority
Los Angeles Regional Food Bank
Neighborhood Legal Services of Los Angeles
County
Puente Hills Habitat Preservation Authority
South Central Los Angeles Regional Center
Westside Regional Center
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Los Angeles County Department of Public Works
County of Los Angeles
All-Hazards Mitigation Plan
Page 3 of 204
Table of Contents
Acknowledgement ................................................................................................................. 1
Letter of Promulgation ........................................................................................................... 2
1 _plaLqJpVa_-qliamNA_L1JaiN ................................................................................ 6
1.1 Purpose ...................................................................................................................... 7
1.2 Scope ......................................................................................................................... 7
1.3 Legal Authority and Requirements ......................................................................... 7
1.4 Plan Organization ..................................................................................................... 8
2 Planning Process ............................................................................................................. 9
2.1 Overview of the Planning Process ........................................................................ 10
2.2 Stakeholder Engagement ...................................................................................... 13
2.3 Public Involvement and Outreach ........................................................................ 18
2.4 Review and Incorporation of Existing Plans and Reports .................................. 19
3 a^^q_Vpy-laœ]N ........................................................................................................ 22
3.1 Los Angeles County Overview .............................................................................. 23
3.2 Geography and Land Use ..................................................................................... 24
3.3 Social Vulnerability ................................................................................................. 25
3.4 Economy and Critical Infrastructure ..................................................................... 28
3.5 Climate and Environmental Conditions ............................................................... 29
3.6 Regional Collaboration and Planning Efforts ...................................................... 30
3.7 Implications for Hazard Mitigation Planning ....................................................... 31
4 Climate Change ............................................................................................................ 32
4.1 Climate Change Overview .................................................................................... 33
4.2 _pNTlApV_T]V^ApNUA_TNV_paA|AlL-laœ]Nm ............................................... 34
4.3 Climate Mitigation Strategies ................................................................................ 36
4.4 Climate Change Conclusion ................................................................................. 37
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5 Integrating Access and Functional Needs (AFN) into Hazard Mitigation .............. 38
5.1 AFN Introduction .................................................................................................... 39
5.2 Inclusion of AFN and Vulnerable Populations in Planning ................................ 39
5.3 Assessment of AFN Needs .................................................................................... 40
5.4 Coordination with AFN Support Agencies .......................................................... 42
5.5 AFN Conclusion ...................................................................................................... 42
6 A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p ............................................................... 43
6.1 A|AlLLN_pVœJApVa_%vNlvVNw ............................................................................. 44
6.2 :V]LœlN ..................................................................................................................... 49
6.3 Earthquake .............................................................................................................. 57
6.4 Extreme Heat ........................................................................................................... 67
6.5 Drought .................................................................................................................... 74
6.6 Flooding .................................................................................................................. 82
6.7 Dam Failure ............................................................................................................. 92
6.8 Land Movement .................................................................................................... 102
6.9 Tsunami .................................................................................................................. 114
6.10 Severe Wind and Tornado ............................................................................... 120
6.11 Mass Violence .................................................................................................... 130
6.12 Cybersecurity Incidents .................................................................................... 135
6.13 Transportation Incidents ................................................................................... 142
6.14 Public Health Emergencies .............................................................................. 147
7 Mitigation Strategy ...................................................................................................... 152
7.1 Mitigation Strategy Overview .............................................................................. 153
7.2 Mitigation Goals and Objectives ........................................................................ 153
7.3 Existing Mitigation Capabilities .......................................................................... 155
7.4 LN_pVœJApVa_A_L_A]ymVmaS"VpVTApVa_1plApNTVNm ......................................... 172
County of Los Angeles
All-Hazards Mitigation Plan
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7.5 Status of Previous Mitigation Efforts ................................................................... 184
7.6 Prioritization and Implementation of Mitigation Actions ................................. 186
7.7 Integration with Other Plans ............................................................................... 189
7.8 Mitigation Action Plan .......................................................................................... 191
8 Plan Maintenance ........................................................................................................ 196
8.1 Community Participation in Plan Maintenance ................................................. 197
8.2 "a_VpalV_TvA]qApVa_A_L"AV_pN_A_JN......................................................... 198
8.3 Criteria for Updating the Hazard Mitigation Plan ............................................. 199
8.4 Plan Update ........................................................................................................... 200
8.5 Integration with Other Plans ............................................................................... 201
9 Plan Adoption .............................................................................................................. 202
9.1 Plan Adoption Overview ...................................................................................... 203
Appendices ......................................................................................................................... 204
County of Los Angeles
All-Hazards Mitigation Plan
Page 6 of 204
1 _plaLqJpVa_-qliamN
and Scope
County of Los Angeles
All-Hazards Mitigation Plan
Page 7 of 204
1.1 Purpose
The 2025 All-Hazard Mitigation Plan (AHMP) was developed in collaboration with a
wide range of stakeholders representing County Departments and other external
mpA\NUa]LNlmSla^JVpVNm]aJA]qpV]VpVNm_a_-TavNl_^N_pA] alTA_V|ApVa_m A_L mpApN
agencies. The purpose of this AHMP is to form the strategic-level foundation for hazard
mitigation efforts undertaken by the County of Los Angeles. The 2025 AHMP is an
update to the 2020 version of the plan and seeks to maintain the County’s continuing
commitment to hA|AlL^VpVTApVa_AmAJlVpVJA]mpNiV_lNLqJV_TUA|AlLlVm\m^A\V_T
Ja^^q_VpVNmmASNlA_LIqV]LV_TJaq_pywVLNlNmV]VN_JN
1.2 Scope
A|AlL^VpVTApVa_VmLNœ_NLV_pUNaLNaSNLNlA]0NTq]ApVa_m0 Am¬A_ymqmpAV_NL
action taken to reduce or eliminate the long-term risk to human life and property from
UA|AlLm3UVm"-VLN_pVœNmA_Lilaœ]NmUA|AlLmA_A]y|NmpUNiNai]NA_LJlVtical
V_SlAmplqJpqlNAplVm\A_LilavVLNmAmNlVNmaS^VpVTApVa_mplApNTVNmAV^NLAplNLqJV_T
hazard risk. The plan also describes actions to integrate vulnerable communities
including people with Access and Functional Needs (AFN) into hazard mitigation
planning and other efforts. The AHMP is intended to function as a strategic plan for
UA|AlL^VpVTApVa_A_LwUV]N_apA_N^NlTN_Jyi]A_Ja^i]N^N_pmpUN!am_TN]Nm
County Operational Area Emergency Operations Plan. This plan contains mitigation
strategies for County-owned facilities or other areas under the jurisdiction of the
County of Los Angeles. Hazard mitigation strategies for incorporated cities within Los
Angeles County may be found in that city’s hazard mitigation plan.
1.3 Legal Authority and Requirements
Historically local hazard mitigation planning has been driven by federal law. The
Disaster Mitigation Act (DMA) of 2000 amended the Robert T. Stafford Disaster Relief
and Emergency Assistance Act of 1988 with new requirements for hazard mitigation.
The DMA aSN^iUAmV|NLpUN_NNLSalmpApNplVIA]A_L]aJA]N_pVpVNmpaJ]amN]y
coordinate on hazard mitigation efforts and formed the legal basis for the Federal
Emergency Management Agency’s (FEMA) current mitigation plan requirements in
order to utilize Hazard Mitigation Assistance grant programs. This plan was prepared
County of Los Angeles
All-Hazards Mitigation Plan
Page 8 of 204
pursuant to the requirements set forth in the DMA of 2000 and other FEMA hazard
mitigation policy guidance.
1.4 Plan Organization
The AHMP is organized into nine (9) mNJpVa_mNxJ]qLV_TpUNiiN_LVJNm including:
1.Introduction: VmJqmmNmpUNiqliamNmJaiNA_L]NTA]AqpUalVpyaSpUNi]A_
2.Planning Process: Describes the planning process that was undertaken by the
Hazard Mitigation Planning Committee to create this updated 2025 AHMP.
3.a^^q_Vpy-laœ]N %vNlvVNwmpUNq_VkqNTNaTlAiUVJJ]V^ApVJN_vVla_^N_pA]
and socioeconomic factors that make up Los Angeles County and their
implications for hazard mitigation planning.
4.Climate Change: Outlines the impacts of climate change in Los Angeles County
and potential mitigation and adaptation measures.
5.Integrating AFN into Hazard Mitigation: Discusses strategies for integrating
people with Access and Functional Needs (AFN) into prevention and hazard
mitigation efforts.
6.A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p LN_pVœNmA_Lilaœ]Nmnine (9)
natural and four (4) human-caused hazards that may impact Los Angeles County
including: wV]LœlNNAlpUkqA\NNxplN^NUNApLlaqTUpŔaaLV_TLA^SAV]qlN
]A_L^avN^N_ppmq_A^VmNvNlNwV_LA_Lpal_ALa^AmmvVa]N_JNJyINlmNJqlVpy
V_JVLN_pmplA_mialpApVa_V_JVLN_pmA_LiqI]VJUNA]pUN^NlTN_JVNm
7.Mitigation Strategy: Delineates the overall strategy for the County’s hazard
^VpVTApVa_NSSalpmV_J]qLV_TTaA]mA_LaI[NJpVvNmNxVmpV_T^VpVTApVa_JAiAIV]VpVNm
and an analysis of mitigation actions.
8.Plan Maintenance: Outlines how the plan will be maintained annually ahead of
pUN_NxpSq]]i]A_qiLApNV_œvNyNAlm
9.Plan Adoption: Discusses updates to the plan and implementation following
plan adoption.
a]]awV_TpUNmNmNJpVa_mpUNlNAlNA_ALLVpVa_A]six (6) appendices with supporting
^ApNlVA]mmqJUAmUA|AlL^Aim^NNpV_T^V_qpNmSla^i]A__V_T^NNpV_Tm A_L
information about the public engagement efforts during the planning process.
County of Los Angeles
All-Hazards Mitigation Plan
Page 9 of 204
2 Planning Process
County of Los Angeles
All-Hazards Mitigation Plan
Page 10 of 204
2.1 Overview of the Planning Process
The 2025 Los Angeles County All-Hazard Mitigation Plan (AHMP) update builds upon
the robust all-hazard planning framework established by the 2020 All-Hazards
"VpVTApVa_-]A_wUV]NV_JalialApV_T_Nw^NpUaLa]aTVNmmpA\NUa]LNlN_TATN^N_p
and compliance requirements. The planning process for this update emphasized
V_J]qmVvVpy plA_miAlN_Jy A_L pUN V_pNTlApVa_ aS N^NlTV_T J]V^ApN ALAipApVa_
considerations.
3UVmi]A__V_TilaJNmmSa]]awNLAmplqJpqlNLiUAmNLAiilaAJUA]VT_NLwVpU"¯m
!aJA]"VpVTApVa_-]A__V_T-a]VJyqVLN 0lNkqVlN^N_pmA_LTqVLA_JN
Sla^pUNA]VSal_VAavNl_al¯m%SœJNaS^NlTN_Jy1NlvVJNmA]%1 3UVmAiilaAJU
began witUila[NJpV_VpVApVa_wUNlNpUNmJaiNpV^N]V_NA_LmpA\NUa]LNlmwNlNLNœ_NL
Stakeholder and public engagement were prioritized to ensure representation from
LVvNlmN Tlaqim V_J]qLV_T UVmpalVJA]]y q_LNllNilNmN_pNL Ja^^q_VpVNmA_LJ]V^ApN-
vulnerable populations.
Data Ja]]NJpVa_A_LA_A]ymVm]NvNlATNLqiLApNLUA|AlLJ]V^ApNA_Lvq]_NlAIV]VpyLApA
Sla^]aJA]mpApNA_LSNLNlA]maqlJNmilavVLV_TASaq_LApVa_SalN_UA_JNLlVm\A_L
vq]_NlAIV]VpyAmmNmm^N_pmA|AlLilaœ]NmwNlNqiLApNLpaV_J]qLNJ]V^ApNila[NJpVa_m
and cascading impact scenarios. Mitigation strategies were revised and prioritized with
a renewed focus on climate resilience and nature-based solutions. Strategies were also
developed incorporating people with access and functional needs throughout each
comia_N_paSpUN"-V_A]]y^NpUaLmSal^a_VpalV_TA_LNvA]qApVa_aS^VpVTApVa_
NSSalpmwNlNLNœ_NLV_pUNi]A_^AV_pN_A_JNA_LV^i]N^N_pApVa_mplApNTy3AI]N-1
provides a timeline of the major plan update tasks and milestones over the planning
process.
Table 2-1 AMHP Planning Timeline
Date 3Am\m Peo ple Involved
February
2025
0NvVNwNLpUN"-A_LVLN_pVœNL
components that require update.
OEM AHMP Project
Team
Collected and reviewed existing
LaJq^N_pmV_J]qLV_TpUN3UlNApA_L
A|AlLLN_pVœJApVa_A_L0Vm\
Assessment (THIRA) along with resources
for people with access and functional
OEM AHMP Project
Team
County of Los Angeles
All-Hazards Mitigation Plan
Page 11 of 204
Date 3Am\m People Involved
needs and people experiencing
homelessness.
February 2025
Met with state Hazard Mitigation
Planning Team.
OEM AHMP Project
3NA^A]%1
Mitigation Division
LN_pVœNLpUNV_VpVA]]VmpaSmpA\NUa]LNlm
and ensured organizations that work with
and represent people with access and
functional needs were engaged in the
planning process. External stakeholders
V_J]qLN_NVTUIalV_TJa^^q_VpVNm]aJA]
A_LlNTVa_A]ATN_JVNmA_LapUNlm
OEM AHMP Project
Team
Conducted 2025 AHMP Kickoff Meetings
with internal stakeholders.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqiA]
OES Mitigation Division
NpNl^V_NLUA|AlLmpaINilaœ]NL
V_J]qLV_TIapU_ApqlA]VNwV]L]A_LœlN
NAlpUkqA\NNpJ A_LUq^A_-JAqmNLVN
JyINlmNJqlVpypNllalVm^NpJ
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
Group
Drafted initial sections of the 2025 AHMP. OEM AHMP Project
Team
Shared drafts of initial sections with
internal and external stakeholders for
their review.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
Met with internal and external
stakeholders to obtain feedback on draft
plan elements.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
County of Los Angeles
All-Hazards Mitigation Plan
Page 12 of 204
Date 3Am\m Peo ple Involved
March
2025
Developed the Public Outreach
Engagement Plan to collect feedback
from the public on the public draft of the
2025 AHMP.
OEM AHMP Project
3NA^A]%1
Mitigation Division
Drafted subsequent sections of the 2025
AHMP including updating existing
mitigation actions and developing new
mitigation actions as needed.
OEM AHMP Project
Team
Shared drafts of the subsequent sections
with internal and external stakeholders
for their review.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
Met with internal and external
stakeholders to obtain feedback on
subsequent draft plan elements.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
April/May
2025
lASpNLœ_A]mNJpVa_maSpUN "-
and produced a Final Draft AHMP.
OEM AHMP Project
Team
Shared Final Draft of the AHMP with
internal and external stakeholders for
their review.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
Met with internal and external
stakeholders to obtain feedback on
subsequent Final Draft AHMP.
OEM AHMP Project
3NA^_pNl_A]aq_py
1pA\NUa]LNllaqi
External Stakeholder
laqiA]%1
Mitigation Division
Produced Final AHMP. OEM AHMP Project
Team
County of Los Angeles
All-Hazards Mitigation Plan
Page 13 of 204
2.2 Stakeholder Engagement
Inclusive stakeholder involvement was essential to the planning process. The County
N_mqlNL IlaAL lNilNmN_pApVa_ A_L iAlpVJViApVa_ Ja_mVmpN_p wVpUpUN´:Ua]N
a^^q_VpyiilaAJU´aqp]V_NLV_pUN%iNlApVa_A]lNA^NlTN_Jy%iNlApVa_m
Plan (OAEOP). Key stakeholders that comprised the Hazard Mitigation Advisory
Committee included:
•aq_pyLNiAlp^N_pmmqJUAmIqp_ap]V^VpNLpa-qI]VJ:al\m-qI]VJNA]pUA_L
Regional Planning.
• Cities within the operational area (OA) and neighboring communities through
Disaster Management Area Coordinators (DMACs) and city representation.
•Non-TavNl_^N_pA] alTA_V|ApVa_m #%m V_J]qLV_T N_vVla_^N_pA] A_L
disability advocacy groups.
• Special District partners managing critical infrastructure.
• Representatives of academia and school districts.
• Community representatives from Access and Functional Needs (AFN)
populations and historically underrepresented populations.
0NTq]Al^NNpV_Tmwal\mUaimA_LSaJqmTlaqimwNlNUN]LpaTApUNlV_iqpA_LlNœ_N
mitigation strategies. Stakeholders were contacted and invited to participate in the
2025 AHMP planning process through email (please see email template in Appendix
B-3). Stakeholder SNNLIAJ\wAmLaJq^N_pNLA_LV_JalialApNLV_papUNi]A_N_mqlV_T
diverse perspectives informed the process. Tables 2-2 and 2-3 includes a list of
representatives of each agency that contributed to the planning process.
Table 2-2 Hazard Mitigation Advisory Committee – _pNl_A]1pA\NUa]LNllaqi
Department/
Agency
Name Title Planning Contribution
Los Angeles County
%SœJNaS
Emergency
Management (OEM
AHMP Project
Team)
Michael
Morin
Emergency
Management
Coordinator
q_JpVa_NLAm]NALi]A__Nlm
]NLi]A__V_T^NNpV_Tm
LlASpNLi]A_lNvVNwNL
mitigation actions submitted
by departments. Matthew
Topoozian
Emergency
Management
Coordinator
County of Los Angeles
All-Hazards Mitigation Plan
Page 14 of 204
Department/
Agency
Name Title Planning Contribution
Karen Haro Emergency
Management
Coordinator
Girma
Wollela
Emergency
Management
Coordinator
Los Angeles County
Department of
Aging and
Disabilities
Mike Tsao Administrative
Deputy
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Henry
Lopez
Program
Manager
Carin
Anderson
Administrative
Services
Manager
Keilah
Kelso
Administrative
Services
Manager
Los Angeles County
Chief Executive
%SœJN– Anti-
0AJVm^VvNlmVpy
and Inclusion
Initiative
Cesar
Sanchez
Senior Analyst ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Chief Executive
%SœJN– Homeless
Initiative
Onnie
Williams III
Principal Analyst ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Chief Sustainability
%SœJN
Matthew
Gosner
Climate
Resilience
%SœJNl
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
County of Los Angeles
All-Hazards Mitigation Plan
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Department/
Agency
Name Title Planning Contribution
Los Angeles County
Department of
Beaches and
Harbors
Katharine
de la Cruz
Administrative
Services
Manager
Attended planning ^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Vanessa
Huerta
1ASNpy%SœJNl
Los Angeles County
Department of
Economic
Opportunity
Maritza
Dubie
Human Services
Administrator
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Department of
Health Services
Elaine
Forsyth
Senior Nursing
Instructor
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Isabel
Sanchez
Disaster
Services
Specialist
Los Angeles County
Department of
Human Resources
Kevin
Halbritter
Deputy
Compliance
%SœJNl
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Department of
Parks and
Recreation
Ramon
Bernal
Disaster
Services Analyst
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Department of
Public Health
Elizabeth
Rubin
Epidemiologist ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Department of
Public Social
Services
Manuel
Gutierrez
Disaster
Services Analyst
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
County of Los Angeles
All-Hazards Mitigation Plan
Page 16 of 204
Department/
Agency
Name Title Planning Contribution
Los Angeles County
Department of
Public Works
Joseph
Marble
Disaster
Services Analyst
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Loni Eazell Disaster
Services
Specialist
Los Angeles County
Department of
Regional Planning
Thuy Hua Supervising
Planner
ppN_LNLi]A__V_T^NNpV_Tm
reviewed section LlASpmA_L
provided feedback.
Edgar De
La Torre
Principal
Regional
Planner
Los Angeles County
Fire Department
Nick
Duvally
Deputy Fire
Chief
ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Internal Services
Department
Juan-Raul
Cardenas
GIS Analyst ppN_LNLi]A__V_T^NNpV_Tm
lNvVNwNLmNJpVa_LlASpmA_L
provided feedback.
Los Angeles County
Sheriff’s
Department
Jordan
Kennedy
Sergeant ppN_LNLi]A__V_T^NNpV_Tm
reviewed section LlASpmA_L
provided feedback.
Table 2-3 Hazard Mitigation Advisory Committee – External 1pA\NUa]LNllaqi
Department/Agency Planning Contribution
Access Services ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Alzheimer’s Association California ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
A]VSal_VAavNl_al¯m%SœJNof Emergency Services ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Catholic Charities ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
County of Los Angeles
All-Hazards Mitigation Plan
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Department/Agency Planning Contribution
City of Beverly Hills Emergency Management Division
ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
City of Long Beach Disaster Preparedness & Emergency Communications
ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
City of Los Angeles Emergency Management Department
ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disability Community Resource Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA
ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Disaster Management Area aalLV_ApallNA Attended i]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Eastern Los Angeles Regional Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Emergency Network Los Angeles ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLsection LlASpmA_LilavVLNLSNNLIAJ\
Habitat for Humanity ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
County of Los Angeles
All-Hazards Mitigation Plan
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Department/Agency Planning Contribution
Harbor Regional Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Lanterman Regional Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
!am_TN]Nmaq_py%SœJNaSEducation ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Los Angeles County Sanitation Districts ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Los Angeles Metropolitan Transportation Authority ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Los Angeles Regional Food Bank ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Neighborhood Legal Services of Los Angeles County
ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Puente Hills Habitat Preservation Authority ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
South Central Los Angeles Regional Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_LilavVLNLSNNLIAJ\
Westside Regional Center ppN_LNLi]A__V_T^NNpV_TmlNvVNwNLmNJpVa_LlASpmA_Lprovided feedback.
2.3 Public Involvement and Outreach
-qI]VJaqplNAJUNSSalpmAV^NLpaSampNlplA_miAlN_JyV_J]qmVvVpyA_LSalpVSyiqI]VJplqmp
The County engaged the public during the planning process through multiple media
formats to share information and collect feedback taking into account language and
other access and functional needs. A rolling outreach strategy was used to ensure that
AmNAJUmNJpVa_wAmLlASpNLA_LlNvVNwNLIyi]A__V_TmpA\NUa]LNlmVpwAmJa_JqllN_p]y
^ALNAvAV]AI]NSaliqI]VJJa^^N_pAly3aAJJa^i]VmUpUVmNAJUmNJpVa_wAmiampNL to
the Los Angeles County Hazard Mitigation Program website as it was completed by the
planning team. A survey designed to gauge community perceptions of hazard risks and
mitigation priorities was used on the website (Appendix D). This approach ensured that
the public was a key partner in every step of the planning process and had a voice as
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each section was being developed by the planning team. A social media campaign
using all LA County OEM social media channels was initiated to direct the public to the
survey.
3a ALLlNmm NkqVpy pAlTNpNL aqplNAJU NSSalpm SaJqmNL a_ N_TATV_T UVmpalVJA]]y
q_LNllNilNmN_pNL Ja^^q_VpVNm A_L # iaiq]ApVa_m qmV_T ^q]pV]V_TqA] A_L
AJJNmmVI]N^ApNlVA]mA_LJq]pqlA]]yAiilailVApNpNJU_VkqNmmVLNSla^iqI]VJaqplNAJU
stakeholders that wal\wVpUallNilNmN_piNai]NwVpUAJJNmmA_LSq_JpVa_A]_NNLm
iNai]N NxiNlVN_JV_T Ua^N]Nmm_Nmm A_L A LVvNlmN AllAy aS Jq]pqlA] Tlaqim wNlN
targeted to participate in the Hazard Mitigation Advisory Committee. These measures
ensured that the public had meaningful opportunities to participate in shaping the
plan.
2.4 Review and Incorporation of Existing Plans and Reports
The planning process included a comprehensive review of existing documents and
protocols to ensure consistency and alignment. The 2020 All-Hazards Mitigation Plan
mNlvNLAmpUNSaq_LApVa_A]LaJq^N_pSalpUVmqiLApNLLVpVa_A]]y\NyJa_JNipmSla^
the 2023 Operational Area Emergency Operations Plan (OA%- mqJUAm^NlTN_Jy
1qiialpq_JpVa_m1m A_LLVmAmpNl^A_ATN^N_pAlNAmwNlNV_pNTlApNL3UN!am
Angeles County Climate Vulnerability Assessment provided valuable insights into
J]V^ApNlVm\mA_LmaJVA]mN_mVpVvVpywUV]N]aJA]]V^ApNJpVa_-]A_mN_mqlNLA]VT_^N_p
with mq_VJViA]J]V^ApNALAipApVa_V_VpVApVvNmqlpUNl^alNpUN41303UlNAp
A_LA|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p ilavVLNLJlVpVJA]LApASalVLN_pVSyV_T
Nva]vV_TpUlNApmA_LJAiAIV]VpypAlTNpmN_UA_JV_TpUNAJJqlAJyA_LlN]NvA_JNaSpUN
plan. The demographic data from the 2020 U.S. Census was utilized to ensure an
AJJqlApNlNilNmN_pApVa_aS!am_TN]Nmaq_pyµmiaiq]ApVa__awNmpV^ApNLApavNl
^V]]Va_lNmVLN_pm3UNLN^aTlAiUVJIlNA\Law_V_J]qLNmÈVmiA_VJal!ApV_aÈ
:UVpN ÈmVA_ ÈSlVJA_^NlVJA_ A_L È apUNl wVpU avNlÈ miNA\V_T A
]A_TqATN apUNl pUA_ _T]VmU Ap Ua^N N^iUAmV|V_T pUN _NNL Sal ^q]pV]V_TqA] A_L
culturally appropriate outreach.
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Table 2-4 xVmpV_T-]A_m"AimA_L0Nialpm
-]A_"Aial0Nialp Information to be Incorporated into the 2025 Updated AHMP
Los Angeles County Operational Area Emergency Operations Plan (2023)
Used to inform Section 6A|AlLLN_pVœJApVa_A_LRisk Assessment and Section 7: Mitigation Strategy
Los Angeles County 2035 General Plan (2024) Safety element mitigation policies used to inform Section 7 – Mitigation Strategy
Los Angeles County Comprehensive Floodplain Management Plan (2021)
Used to inform Section 6A|AlLLN_pVœJApVa_A_LRisk Assessment and Section 7: Mitigation Strategy SalN]N^N_pmlN]ApNLpaŔaaLUA|AlLm
County of Los Angeles Floodplain Management Plan Progress Report from (2024)
Used to inform Section 6A|AlLLN_pVœJApVa_A_LRisk Assessment and Section 7: Mitigation Strategy SalN]N^N_pmlN]ApNLpaŔaaLUA|AlLm
County of Los Angeles Repetitive Loss Area Analysis Progress Report (2021)
Used to inform Section 6A|AlLLN_pVœJApVa_A_LRisk Assessment and Section 7: Mitigation Strategy SalN]N^N_pmlN]ApNLpaŔaaLUA|AlLm
Los Angeles County 2045 Climate Action Plan (2024) Used to inform Section 6A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p1NJpVa_7"VpVTApVa_1plApNTyA_LSection 4: Climate Change for elements related to hazard risk posed by climate change
Los Angeles County Fire Department Fire Plan (2023)
Used to inform Section 6A|AlLLN_pVœJApVa_A_LRisk Assessment and Section 7: Mitigation Strategy SalN]N^N_pmlN]ApNLpawV]L]A_LœlNUA|AlLm
Our County: Los Angeles Countywide Sustainability Plan (2019)
Used to inform Section 6A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p1NJpVa_7"VpVTApVa_1plApNTyA_LSection 4: Climate Change for elements related to hazard risk posed by climate change
Los Angeles County Homeless Initiative Strategy Plan (2022)
Used to inform vulnerable populations information across all sections of the plan.
Disability Among Adults in Los Angeles County (2019)
Used to inform vulnerable populations information across all sections of the plan.
Southern California Earthquake Data Center’s Earthquake Catalogs (Current as of 2025)
Historical seismic information used in Section 6: A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p
County of Los Angeles
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-]A_"Aial0Nialp Information to be Incorporated into the 2025 Updated AHMP
Maritime Tsunami Response Playbooks: Background Information and Guidance for Response and Hazard Mitigation Use (2016)
Historical tsunami information used in Section 6: A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p
FEMA Flood Insurance 1pqLy!am_TN]Nmaq_pyA]VSal_VA
VmpalVJA]ŔaaLV_Sal^ApVa_qmNLV_1NJpVa_6: A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p
U.S. Geological Survey (USGS): Rainfall and Landslides in Southern California (2015)
Historical landslide information used in Section 6: A|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p
Burn Scar Information and Maps VmpalVJA]œlNV_Sal^ApVa_qmNLV_1NJpVa_6: Hazard LN_pVœJApVa_A_L0Vm\mmNmm^N_p
County of Los Angeles
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3 Community -laœ]N
County of Los Angeles
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3.1 Los Angeles County Overview
Los Angeles County is the
most populous county in
pUN 4_VpNL 1pApNm
encompassing a diverse
AllAy aS Ja^^q_VpVNm
]A_LmJAiNm A_L
infrastructure. According to
the most recent census
LApA !am _TN]Nm aq_py
has a population of
approximately 10 million
residents of which more than 1 million reside in unincorporated areas. The County’s
LN^aTlAiUVJm TNaTlAiUVJ SNApqlNm A_L NJa_a^VJ AJpVvVpVNm ilNmN_p IapU q_VkqN
aiialpq_VpVNmA_LmVT_VœJA_pJUA]]N_TNmSalUA|AlL^VpVTApVa_i]A__V_T3UVmqiLApNL
communipy ilaœ]N V_pNTlApNm V_mVTUpm Sla^ pUN %iNlApVa_al Area Emergency
Operations Plan (OA%- A_LlNŔNJpmJUA_TNmV_iaiq]ApVa_plN_LmV_SlAmplqJpqlN
LNvN]ai^N_pA_LJ]V^ApNlVm\m
The County Operational Area (OA) consists of all political subdivisions within the
TNaTlAiUVJA]Iaq_LAlVNmaS!am_TN]Nmaq_pypN_Ja^iAmmNmœvNmqiNlvVmalVA]
LVmplVJpmNVTUpVmAmpNl"A_ATN^N_plNAm"m V_JalialApNLJVpVNmmJUaa]
districpmA_LAiilaxV^ApN]ymiNJVA]LVmplVJpm
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3.2 Geography and Land Use
1iA__V_TavNlmkqAlN
^V]Nm !am _TN]Nm aq_py
SNApqlNm LVvNlmN pNllAV_
including coastal plains
vA]]Nym ^aq_pAV_m Vm]A_Lm
and deserts. The County’s
varied geography includes
multiple microclimates that
V_ŔqN_JNVpmNxiamqlNpa
_ApqlA] UA|AlLm mqJU Am
NAlpUkqA\Nmpmq_A^VmwV]LœlNmŔaaLmA_L]A_Lm]VLNm4lIA_AlNAmiAlpVJq]Al]ypUN
VpyaS!am_TN]NmA_LVpmmqllaq_LV_T^Nplaia]VpA_lNTVa_AlNLN_mN]yiaiq]ApNL
A_LUNAvV]yLNvN]aiNL_Ja_plAmplqlA]A_Lq_V_JalialApNLAlNAm often face unique
vulnerabilities due to limited infrastructure and resources. Rural areas include the
_TN]Nm A_L !am -ALlNm #ApVa_A] alNmpm wUVJU UAvN m^A]] Ja^^q_VpVNm
JA^iTlaq_LmA_LLAyqmNAlNAm3UNlNAlNA]mapwaVm]A_LmwVpUV_pUNaq_py1A_pA
ApA]V_AA_L1A_]N^N_pN3UNaq_pyA]maV_J]qLNmAmVT_VœJA_pA^aq_paSWildland
Urban Interface (WUI) areas where residential and commercial development meets
underdeveloped wildland with vegetative fuels. Land use within the County is equally
LVvNlmNwVpUA^VxaSlNmVLN_pVA]Ja^^NlJVA]V_LqmplVA]ATlVJq]pqlA]A_LaiN_spaces.
Recent urban development in densely populated areas has increased impervious
mqlSAJNm]V\NJa_JlNpNA_LAmiUA]pwUVJUlNpAV_UNApA_LJlNAp NqlIA_UNApVm]A_Lm (UHI)
that are much hotter than nearby rural areas3UVmiUN_a^N_a_N]NvApNmpN^iNlApqlNm
especially in low-V_Ja^NJa^^q_VpVNm]AJ\V_TTlNN_miAJNmSalJaa]V_TLLVpVa_A]]y
urbanization affects stormwater management by reducing natural drainage and
NxAJNlIApV_TŔaaLV_TlVm\mV_]aw-lying areas.
3UNmN plN_Lm q_LNlmJalN pUN _NNL Sal mqmpAV_AI]N i]A__V_T mplApNTVNm mqJU Am
ila^apV_TTlNN_V_SlAmplqJpqlNN_UA_JV_Tmpal^wApNlmympN^mA_L^VpVTApV_TUNAp
Vm]A_LmpUlaqTUplNNi]A_pV_TA_LlNŔNJpVvN^ApNlVA]m3UNaq_py¯mLVvNlmN]A_LqmN
must be carefully managed to reduce vulnerabilities while supporting economic
growth and environmental sustainability.
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3.3 Social Vulnerability
Social vulnerability is a crucial component to Los Angeles County’s hazard mitigation
i]A__V_T3UN aq_py Vm Ua^N pa A LVvNlmN iaiq]ApVa_ wVpU LVmiAlVpVNm V_ V_Ja^N
UaqmV_T mpAIV]Vpy A_L AJJNmm pa lNmaqlJNmThe Los Angeles County Anti-0AJVm^
VvNlmVpyA_L_J]qmVa_0 _VpVApVvNJlNApNLAJa^ilNUN_mVvN kqVpy xi]alNl
which is a geospatial tool that explores multiple equity data points across Los Angeles
County. The ARDI Equity Explorer includes varioum]AyNlmpUApvVmqA]V|NmaJVA]NkqVpy
economVJaiialpq_VpyUaqmV_TA_LUa^N]Nmm_NmmUNA]pU[qmpVJNIqV]pN_vVla_^N_p
and disaster recovery data. The public can access this data at
ceo.lacounty.gov/ardi/tools. Maps created using data from the ARDI Equity Explorer
are in Appendix A-8.
The US Centers for Disease Control and
-lNvN_pVa_ LNœ_Nm maJVA]
vulnerability as a community’s capacity to
prepare for and respond to the stress of
hazardous events ranging from natural
disasters to human caused threats. The
CDC’s Social Vulnerability Index (Figure
3.1) is designed to identify and quantify
communities experiencing social
vulnerability.
The most recent CDC Social Vulnerability
Index score from 2022 for Los Angeles
County indicated a high level of
vulnerability across four themes:
maJVaNJa_a^VJ mpApqm UaqmNUa]L
JUAlAJpNlVmpVJmlAJVA]A_LNpU_VJ^V_alVpy
mpApqmA_LUaqmV_TpyiNplA_mialpApVa_
Vulnerable populations VLN_pVœNLSal!am_TN]Nmaq_pypUApwV]]INJa_mVLNlNLV_pUN
AHMP include:
Figure 3.1 CDC Social Vulnerability Index (CDC 2022)
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x Low-_Ja^N 0NmVLN_pm:
Individuals living below or near
the poverty line are often
disproportionately affected by
LVmAmpNlmLqNpa]V^VpNLœ_A_JVA]
resources for emergency
ilNiAlNL_Nmm lNmia_mN A_L
recovery.
x People with Access and
Functional Needs (AFN):
Individuals with Access and
Functional needs have increased
challenges in ilNiAlNL_Nmm
NvAJqApVa_ mUN]pNlV_T AJJNmmV_T
emergency services and recovery.
Access and Functional Needs
include but are not limited to
people who have any combination
in varying degree of: physical
disabilities V_pN]]NJpqA]disabilities
developmental disabilities ^N_pA]
health-lN]ApNL VmmqNm vVmqA]
V^iAVl^N_pm UNAlV_T
impairments/deaf ^aIV]Vpy
impairmentsor chronic
conditions. AFN also include
a]LNl ALq]pm V_SA_pm A_L JUV]LlN_people ]VvV_T V_ V_mpVpqpVa_A]V|NL mNppV_Tm
people living below tUNiavNlpy]V_NalNxiNlVN_JV_TUa^N]Nmm_Nmmpeople with
]V^VpNL _T]VmU ilaœJVN_Jy al AlN _a_-_T]VmU miNA\Nlm alpeople who are
transportation disadvantaged.
x People Experiencing Homelessness (PEH): With an estimated over
individuals NxiNlVN_JV_T Ua^N]Nmm_Nmm pUVm iaiq]ApVa_ Vm iAlpVJq]Al]y Ap lVm\
during extreme weather events and other disasters.
x Immigration Status: Fear of engaging with government services based on
immigration status can prevent residents from accessing critical resources.
Figure 3. 3 Breakdown of Language at Home in Los Angeles County
(OAEOP 2023)
Figure 3.2 ŝƐĂďŝůŝƚLJ^ƚĂƟƐƟĐƐŝŶ>ŽƐŶŐĞůĞƐŽƵŶƚLJ (OAEOP 2023)
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x !V^VpNL_T]VmU-laœJVN_JyOver 40% of residents speak a language other
pUA__T]VmUApUa^NUVTU]VTUpV_TpUN_NNLSal^q]pV]V_TqA]A_L Jq]pqlA]]y
appropriate outreach efforts. Language accessibility is critical to ensure all
residents and visitors can obtain information and services during a disaster. See
Figure 3.3 for a breakdown of languages spoken at home in Los Angeles County
not including American Sign Language.
3UNœTqlNIN]awUVTU]VTUpmJNlpAV_vAlVAI]NmV_!am_TN]Nmaq_pypUAp^AyV_JlNAmN
vq]_NlAIV]Vpy pa N^NlTN_JVNm A_L LVmAmpNlm 3a ALLlNmm pUNmN vq]_NlAIV]VpVNm pUN
County’s mitigation planning includes equitable strategies designed to reduce risk and
e_UA_JNlNmV]VN_JNA^a_TpUNmNiaiq]ApVa_m3AlTNpNLaqplNAJUV^ilavNLAJJNmmpa
lNmaqlJNm ilNiAlNL_Nmm NLqJApVa_ NvN_pm A_L Ja]]AIalApVa_ wVpU Ja^^q_Vpy
organizations are integral to these efforts.
Figure 3.4 Los Angeles County Vulnerability Variables (OAEOP 2023)
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The Federal Emergency Management Agency (FEMA) maintains the National Risk
_LNxA^AiiV_Tpaa]pUApAmmNmmNmiammVI]NUA|AlLmA[qlVmLVJpVa_VmmqmJNipVI]Npa
in combination with the amount of loss that could result from those hazards. Los
Angeles County ranks as the community with the most risk in the United States
AJJalLV_T pa pUN " #ApVa_A] 0Vm\ _LNxJJalLV_T pa pUN #ApVa_A] 0Vm\ _LNx
UA|AlLmwVpUpUNUVTUNmplVm\Sal!am_TN]Nmaq_pyV_J]qLNNAlpUkqA\NwV]LœlNm
NxplN^NUNApŔaaLV_TUVTUwV_LmA_L]A_Lm]VLNm
3.4 Economy and Critical Infrastructure
!am _TN]Nm aq_py Vm A T]aIA] NJa_a^VJ UqI UampV_T V_LqmplVNmmqJUAm
N_pNlpAV_^N_p pNJU_a]aTy ^A_qSAJpqlV_T A_L V_pNl_ApVa_A] plALN3UN -alp aS !am
Angeles and the Port of Long Beach collectively form one of the world’s busiest trade
TApNwAym q_LNlscoring the importance of protecting critical infrastructure from
hazards including those exacerbated by climate change. Critical facilities provide
mNlvVJNmA_LSq_JpVa_mNmmN_pVA]paAJa^^q_VpyNmiNJVA]]yLqlV_TA_LASpNlALVmAmpNl
Common types of crVpVJA]SAJV]VpVNmV_J]qLNIqpAlN_ap]V^VpNLpaœlNmpApVa_mia]VJN
mpApVa_mUamiVpA]mmJUaa]mA_LqpV]VpVNmlVpVJA]SAJV]VpVNm^AyA]maV_J]qLNi]AJNmpUAp
JA_INqmNLSalmUN]pNlV_TJaa]V_TJN_pNlmmpATV_TiqliamNmalapUNl]AlTNiqI]VJ
gathering spots such as community centers and libraries. Critical facilities include those
operated by non-governmental and business partners vital for redevelopment or
Figure 3.5 & DEĂƟŽŶĂůZŝƐŬ/ŶĚĞdž (2025)
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NJa_a^VJmNJqlVpy:UN_pUNmNAlNASSNJpNLIyALVmAmpNlpUNaq_py ilavVLNm
businesses and workers impacted by the disaster with vital information and resources.
This allows them to maneuver effectively through disaster response toward recovery
using its network of job centers and business hubs.
Other critical infrastructure includes the facilities and industries that enable all facets of
maJVNpypaSq_JpVa_V_J]qLV_TIqp_ap]V^VpNLpapUNSa]]awV_TJa^^q_Vpy]VSN]V_Nm
x Safety and Security3UN ^ylVAL aS ]aJA] ]Aw N_SalJN^N_p œlN A_L lNmJqN
N^NlTN_Jy^A_ATN^N_pmJUaa]mA_LapUNlTavNl_^N_pmNlvVJNmpUAp^AV_pAV_
public safety and security.
x Communications: The interconnected network of infrastructure owners and
aiNlApalmaSJa^^q_VJApVa_mmympN^mmqJUAmV_pNl_NppN]NiUa_NJN]]q]AlA_L
apUNlJa^^q_VJApVa_mpawNlmJAI]NmApN]]VpNA_L^alN
x 3lA_mialpApVa_ #Npwal\m: The County’s extensive network of laALwAym
UVTUwAymlAV]wAymplA_mVpmympN^mand airports is essential for daily operations
and disaster response.
x Energy Systems: -awNlTN_NlApVa_SAJV]VpVNmN_NlTyLVmplVIqpVa__Npwal\mA_L
pipelines are vulnerable to multiple types of hazards and threats.
x Water and Wastewater Systems: Drought conditions and aging infrastructure
at the over 220 different water agencies in Los Angeles County pose risks to
water availability and quality.
x Healthcare Facilities: Over 100 hospitals and numerous clinics serve the
aq_py lNkqVlV_T laIqmp Ja_pV_TN_Jy i]A_m pa ^AV_pAV_ aiNlApVa_m LqlV_T
disasters.
x Food and Shelter: 3UNvAmpmympN^aSSaaLilaLqJpVa_VNATlVJq]pqlN
LVmplVIqpVa_A_LlNpAV]A]a_TwVpUJa^^q_VpyUaqmV_TalmUN]pNlV_T
3.5 Climate and Environmental Conditions
!am_TN]Nmaq_pySAJNmNmJA]ApV_TlVm\mSla^J]V^ApNJUA_TNmVT_VœJA_p]yV^iAJpV_T
Vpm N_vVla_^N_p NJa_a^y A_L Ja^^q_VpVNm 3UNmN JUA]]N_TNm V_J]qLN lVmV_T
pN^iNlApqlNmila]a_TNLLlaqTUpm^alNSlNkqN_pA_LmNvNlNNxplN^NwNApUNlNvN_pm
and their cascading effects. These risks highlight the critical need for adaptive planning
pailapNJpvq]_NlAI]Niaiq]ApVa_mV_SlAmplqJpqlNA_L_ApqlA]lNmaqlJNm NyJ]V^ApN-
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related considerations referenced in the Los Angeles County Climate Action Plan that
will be addressed in this AHMP includeIqpAlN_ap]V^VpNLpa:
x Extreme Weather Events: Extreme temperatures in the Los Angeles region are
NxiNJpNLpaV_JlNAmN
apULlyA_LwNpNxplN^NmAlNila[NJpNLpaV_pN_mVSy]NALV_T
to longer dry periods than historically experienced. These dry periods are expected
paINSa]]awNLIymVT_VœJA_p]ywNppNlJa_LVpVa_mV_J]qLV_TAp^amiUNlVJ lVvNlm
IlV_TV_T^alNV_pN_mNlAV_SA]]3UVmiAppNl_^AylNmq]pV_V_JlNAmNLwApNlmJAlJVpy
^qLm]VLNmA_LŔaaLV_T
x Sea-!NvN] 0VmN: Coasta]Ja^^q_VpVNmAlNApUNVTUpN_NLlVm\aSŔaaLV_TA_L
NlamVa_pUlNApN_V_TUa^NmIqmV_NmmNmA_LJlVpVJA]V_SlAmplqJpqlN Sea level rise can
NxAJNlIApNpUNV^iAJpmaSUVTUpVLNmmpal^mqlTNmA_LUNAvyilNJViVpApVa_A_L
JA_]NALpaV_JlNAmNLJaAmpA]ŔaaLV_TA_LmUalN]V_NNlamVa_
x _JlNAmV_T :V]LœlN 0Vm\ ]V^ApN JUA_TN UAm V_pN_mVœNL wV]LœlN mNAma_m
particularly in the County’s mountainouswV]L]A_LqlIA_V_pNlSAJN:4 and new
and undeveloped regions. :V]LœlNmAlNila[NJpNLpaV_JlNAmNV_SlNkqN_JyA_L
V_pN_mVpyV_J]qLV_TV_ma^NAlNAm_apUVmpalVJA]]yV^iAJpNLIywV]LœlN
_lNmia_mNpUNaq_pyUAmilValVpV|NLV_pNTlApV_TJ]V^ApNALAipApVa_mplApNTVNmV_pa
VpmUA|AlL^VpVTApVa_i]A__V_TAmaqp]V_NLV_pUN]V^ApN9q]_NlAIV]VpymmNmm^N_pA_L
the OAEOP.
3.6 Regional Collaboration and Planning Efforts
Los Angeles County’s size and complexity necessitates collaboration with numerous
[qlVmLVJpVa_mATN_JVNmA_LJa^^q_VpyalTA_V|ApVa_m3UNaq_pyVmLNmVT_ApNLAmpUN
Operational Area Coordinator and functions as an intermediate level in the State of
California’s Standardized Emergency Management System (SEMS). In accordance with
1"1pUNaq_pymNlvNmAmpUNJa^^q_VJApVa_mA_LJaalLV_ApVa_]V_\INpwNN_]aJA]
governments within Los Angeles County and the state government. Partnerships with
AJALN^VJ V_mpVpqpVa_m _a_-ilaœpm A_L ilVvApN mNJpal mpA\NUa]LNlm support data
Ja]]NJpVa_iqI]VJN_TATN^N_pA_LV__avApVvN^VpVTApVa_mplApNTVNmLLVpVa_A]]ypUN
County has also adopted Emergency Support Functions (ESFs) as the primary
emergency management coordination structure. ESFs group function-miNJVœJ
stakeho]LNlmwUawV]]JaalLV_ApNpUlaqTUaqpA]]iUAmNmaSN^NlTN_Jy^A_ATN^N_p
County of Los Angeles
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including function-miNJVœJ ^VpVTApVa_ AJpVvVpVNm al ^alN V_Sal^ApVa_ a_ lNTVa_A]
N^NlTN_Jy^A_ATN^N_pJa]]AIalApVa_A_Li]A__V_TlNSNlN_JNpUNOAEOP.
3.7 Implications for Hazard Mitigation Planning
Understanding the community is a critical aspect in hazard mitigation planning. This
Ja^^q_Vpyilaœ]NwV]]V_Sal^\NyJa_mVLNlApVa_mV_mqImNkqN_pmNJpVa_maSpUN"-
including but not limited to the following:
x Targeted Outreach: Include vulnerable populations and the business
community in the planning process through equitable public outreach.
x _SlAmplqJpqlN 0NmV]VN_JN -lValVpV|N pUN ilapNJpVa_ aS JlVpVJA] V_SlAmplqJpqlN
V_J]qLV_TialpmA_LplA_mialpApVa__Npwal\mN_NlTymympN^mA_LwApNlA_L
wAmpNwApNlmympN^mA^a_TapUNlm
x Climate Adaptation: Develop strategies to mitigate the impacts of climate
JUA_TNSaJqmV_Ta_qlIA_UNApVm]A_LmmNA-]NvN]lVmNA_LwV]LœlNlVm\m
x 0NTVa_A]aalLV_ApVa_ Strengthen direct collaboration within the OA between
pUN aq_py ]aJA] [qlVmLVJpVa_m miNJVA] LVmplVJpm q_VœNL mJUaa] LVmplVJpm pUN
business community and cross-sector non-governmental partners to enhance
AwAlN_NmmilNiAlNL_NmmA_LlNmia_mNJAiAIV]Vties.
x Transparent & Open Communication: _mqlNJa^^q_VJApVa_mAlNAJJNmmVI]N
and clear to advance public trust and safety. Develop dashboards to
demonstrate progress.
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4 Climate Change
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4.1 Climate Change Overview
Climate change refers to the changing effect of the Earth's J]V^ApNmympN^avNlpV^N
V_J]qLV_TJUA_TNmV_pN^iNlApqlNilNJViVpApVa_A_LwV_LiAppNl_m]V^ApNJUA_TN
had mVT_VœJA_pV^iAJpma_!am_TN]Nmaq_pyASSNJpV_TvAlVaqmAmiNJpm aS ]VSN
N_vVla_^N_p V_SlAmplqJpqlN A_L mqmpAV_AI]N LNvN]ai^N_p A_L ilNmN_pmincreasing
lVm\mSla^A^i]VœNLUA|AlLmA_LJUA_TV_TIAmN]V_NmNTmNA]NvN] V_papUNSqpqlN. The
lApNaSJ]V^ApNJUA_TNUAmmVT_VœJA_p]yAJJN]NlApNLavNlpUNlast three decades and
trends continues. This plan addresses the effects of climate change related to disasters
wVpUV_pUNaq_pyA_LmplApNTVNmpa^VpVTApNlVm\mSaJqmV_Ta_ilNiAlNL_NmmlNmV]VN_JN
and equity.
]V^ApNJUA_TNJa_plVIqpNmpa^alNSlNkqN_pA_LV_pN_mNLVmAmpNlmmqJUAmŔaaLm
wV]LœlNm LlaqTUp A_L NxJNmmVvN UNAp 0VmV_T pN^iNlApqlNm A_L JUA_TV_T wNApUNl
patterns pose UNA]pUlVm\m]V\NUNAp-lN]ApNLV]]_NmmNmlNmiVlApalyVmmqNmA_LpUNmilNAL
of diseases. Hazard mitigation efforts aim to reduce the impacts and effects of greater
hazards due to climate change. The economic impact of climate change has been
mqImpA_pVA] ASSNJpV_T V_LqmplVNm mqJU Am ATlVJq]pqlN paqlVm^ A_L V_mqlA_JN with
increasing risks due to accelerating climate changes.
Greenhouse Gas (GHG) emissions are the main driver of J]V^ApNJUA_TNwUVJUJAqmNm
V_JlNAmNLSlNkqN_JyLqlApVa_A_LmNvNlVpyaSNxplN^NwNApUNlA_LJ]V^ApN-related
LVmAmpNlm]V^ApNJUA_TNNxAJNlIApNmAVlia]]qpVa_]NALV_TpaiaalAVlkqA]VpyA_L
health issues. GHG emissions from lNmVLN_pVA]IqV]LV_TmJa^^NlJVA]A_Linstitutional
SAJV]VpVNm^A_qSAJpqlV_TV_LqmplVNmA_LJa_mplqJpVa_N_NlTyV_LqmplVNm oil and natural
gas systems. plA_mialpApVa_fossil N_NlTywV]LœlNmA_LapUNlsources contribute to
increased particulate matter and other pollutants in the air.
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4.2 _pNTlApV_T]V^ApNUA_TNV_paA|AlL-laœ]Nm
Integrating climate change into
UA|AlLilaœ]NmV_va]vNmAmmNmmV_TpUN
current and future impacts of climate
change on various hazards and
incorporating this information into
planning and mitigation strategies.
This section highlights how climate
change relates to these hazards and
how the county is addressing climate
change through hazard mitigation
efforts which help protect the county’s
residents and economies from the
adverse effects of climate changes and climate-A^i]VœNLevents.
4.2.1 Extreme Heat
Increasing temperatures and high heat events is one of the most conspicuous results
of and a direct correlation between GHG pollution and climate change. Excessive
pN^iNlApqlNmV_pUN!am_TN]NmlNTVa_AlNNxiNJpNLpaV_JlNAmNmVT_VœJA_p]y^alN
very hot days and warm nights. In addition to increasing baseline temperatures and
NxplN^NUNApLqNpaJ]V^ApNJUA_TNUNApVm]A_LmNxAJNlIApNpN^iNlApqlNmA_LUVTU
heat events. As development occurs and darker paved surfaces replace open land and
vNTNpApVa_ pUNmN AlNAm INJa^N wAl^Nl Sal^V_T A_ ¬Vm]A_L aS UNAp !am_TN]Nm
County experiences more frequent and excessive heat due to climate change. This is
currently a major risk and with unmitigated GHG emissions increasing heat will lead to
even greater health issqNmV_JlNAmNLN_NlTyLN^A_LSalJaa]V_TA_LapUNlmplAV_ma_
infrastructure.
4.2.2 Flooding
]aaLV_TV_!am_TN]Nmaq_pyaJJqlmLqNpaNxplN^NlAV_SA]]NvN_pmJAqmV_TŔAmU
ŔaaLmlVvNlV_NŔaaLV_TA_LV_JlNAmNLmqlSAJNwApNlaAmpA]AlNAmV_!am_TN]Nm
County are vulnerable to sea-]NvN]lVmN1!0 wUVJUNxAJNlIApNmJaAmpA]UA|AlLm]V\N
ŔaaLmmpal^mqlTNmA_LJUla_VJNlamVa_%pUNllN]ApNLUA|AlLmV_J]qLNŔaaLV_T_NAl
Figure 4.1 Sources of GHG Emissions from within Los Angeles County (LA County
ϮϬϮϰ͖ϮϬϰϱůŝŵĂƚĞĐƟŽŶWůĂŶͿ
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pUN ^aqpUm aS mplNA^m A_L JUA__N]m ]A_Lm]VLNm A_L mNAwApNl wN]] V_plqmVa_ 1!0
NxAJNlIApNmpUNV^iAJpmaSUVTUpVLNmmpal^mqlTNmA_LUNAvyilNJViVpApVa_ŔaaLV_T
and continued SLR will lead to more life safety concerns and increased damage to
property and infrastructure.
4.2.3 Drought
-la]a_TNLLlaqTUpmUAvNINJa^N^alNJa^^a_ASSNJpV_TpUNwApNlmqii]y
ATlVJq]pqlNA_LNJamympN^maS!am_TN]Nmaq_pylyA_LwNpNxplN^Nm AlN
projected to increase and are likely to cause drier periods than what the region has
historically experienced.
1aqpUNl_A]VSal_VAila[NJpNLpaTNpLlVNlwUV]N#alpUNl_A]VSal_VAwV]]V_JlNAmNV_
temperature. This will result in loss of snowpack within the Sierra Nevada Mountain
lA_TN^NA_V_T]NmmwApNlSalA]]A]VSal_VA_mV_J]qLV_TSAl^NlmlNmVLN_pmA_LqpV]ities.
The State Water Resource Control Board proclaimed several water conservation
N^NlTN_JylNTq]ApVa_mLqNpamNvNlNLlaqTUpJa_LVpVa_mpUAplNkqVlNmJa^^NlJVA]
V_LqmplVA]A_LlNmVLN_pVA]Ja_mNlvApVa_NSSalpm-laJ]A^ApVa_mV_J]qLN
x January 4, 2022:State Water Board adopted the prohibited wasteful water
uses emergency regulation
x May 24, 2022:the State Water Board adopted the emergency regulation to
ban decorative grass watering like non-functional turf irrigation
x December 7, 2022:the State Water Board readopted the prohibited
wAmpNSq]wApNlqmNmN^NlTN_JylNTq]ApVa_
x May 26, 2023:the State Water Board readopted the emergency regulation
to ban decorative grass watering.
4.2.4 :V]LœlN
wV]LœlNVmA_q_i]A__NLA_Lq_Ja_pla]]NLœlNV_A_AlNAaSJa^IqmpVI]NvNTNpApVa_
3UNmNœlNmJA_NAmV]ymilNALINya_LpUN_ApqlA]AlNAmilV^AlV]yV_va]vV_TA_LUAvNA
iapN_pVA]paJAqmNLA^ATNmaqpmVLNaSpUNiNlV^NpNl:V]LœlNilaIAIV]VpyLNiN_Lman
]aJA]wNApUNlJa_LVpVa_maqpLaalAJpVvVpVNmA_LA_yilNJNLV_TJa_LVpVa_mNT]apmaS
lAV_]NALV_TpavNTNpApVa_TlawpUA_LpUN_LlyV_TJa_LVpVa_m A_LAiapN_pVA]VT_VpVa_
NT]VTUp_V_TmplV\NAlma_LNIlVmIql_V_TN]NJplVJA]NkqVi^N_pSAV]qlN JAlpAV]iViN
NpJ 3UNSlNkqN_JyA_LV_pN_mVpyaSwV]LœlNmUAmV_JlNAmNLLlVvN_ Iy UVTUNl
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pN^iNlApqlNm]awNlilNJViVpApVa_]awNllN]ApVvNUq^VLVpyA_Lila]a_TNLLlaqTUpm
3UNmN NvN_pm UAvN JAqmNL ]amm aS ]VSN LNmplay A_Lal LA^ATN pailaiNlpy
V_SlAmplqJpqlNpUNN_vVla_^N_pA_LiamNTlNApNllVm\mLqNpaUVmpalVJA]LNvN]ai^N_p
patterns. The pV^N]V_NaS^A[alwV]LœlNNvN_pmA_LAJlNATNIql_NLV_!am_TN]Nm
County is listed at Section 6.2 of the plan.
4.3 Climate Mitigation Strategies
Los Angeles County is actively addressing climate change and implementing hazard
mitigation strategies to reduce its impacts and build long-term resilience. The County
SAJNmV_JlNAmV_TlVm\mSla^NxJNmmVvNUNApwV]LœlNmLlaqTUpmŔaaLmA_LmNA-level rVmN
A]]aSwUVJUpUlNApN_Ja^^q_VpVNmV_SlAmplqJpqlNA_L_ApqlA]lNmaqlJNm
3a ALLlNmm ^A_y aS pUNmN JUA]]N_TNm pUN aq_py UAm LNvN]aiNL Ja^ilNUN_mVvN
J]V^ApNi]A_mA_LmplApNTVNmpUApV_pNTlApNJ]V^ApNALAipApVa_mqmpAV_AI]N]A_LqmN
N^NlTN_JyilNiAlNL_NmmA_LN_vVla_^N_pA]Ja_mNlvApVa_
yN_SalJV_T IqV]LV_T
JaLNmV_vNmpV_T V_TlNN_V_SlAmplqJpqlNA_LmplN_TpUN_V_TJa^^q_VpyilNiAlNL_Nmm
Los Angeles County aims to minimize risks and enhance disaster resilience. These
efforts align with state and federal climate policies and are designed to protect both
current and future generations while encouraging a more sustainable and livable
environment for all.
4.3.1 Climate Resilience Plans and Actions
x Los Angeles County 2045 Climate Action Plan (2045 CAP): Establishes
aggressive targets to reduce greenhouse gas emissions and achieve carbon
neutrality by 2045.
x :ApNla_mNlvApVa_ËlaqTUp0NmV]VN_JN"NAmqlNm Implements mandatory
wApNllNmplVJpVa_mila^apNmlAV_wApNl UAlvNmpV_TA_LNxiA_LmTlaq_LwApNl
recharge and water recycling projects.
x :V]LœlN"VpVTApVa_Ë9NTNpApVa_"A_ATN^N_p-laTlA^m Enforces Wildland
4lIA__pNlSAJN:4 JaLNmV_JlNAmNmSalNmp^A_ATN^N_ppNJU_VkqNmaligned
with Traditional Ecological Knowledge (TEK) principles and practices of our
native indigenous communities A_L mplN_TpUN_m œlN-resistant building and
landscape requirements.
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x lNN_ _SlAmplqJpqlN Ë 4lIA_ aa]V_T _VpVApVvNm Expands tree planting
aligned with TEK principles and practicesV_vNmpVTApNmlN^avV_TUAlLiAvNL
mqlSAJNm A_L i]A_pV_T Tlaq_LJavNl qpV]V|Nm A_L ila^apNm iqI]VJ Jaa]V_T
JN_pNlmA_LUa^NUNApilNiAlNL_NmmA_LN_JaqlATNmpUNqmN aSlNŔNJpVvN
¬Jaa]laaœ_TA_LmqlSAJNmpa^VpVTApNpUNqlIA_UNApVm]A_L4 NSSNJt.
x Heat Action Plan: Develops strategies to reduce the adverse health impacts of
NxJNmmVvNUNAppUlaqTUiqI]VJmUALNmplqJpqlNmJaa]V_TJN_pNlmIqV]LV_TJaLNm
and increased public awareness campaigns for all susceptible to extreme heat.
3UNmNmplApNTVJAJpVa_mlNŔNJp!am_TN]Nmaq_py¯mJa^^Vp^N_ppapAJ\]V_TJ]V^ApN
JUA_TN
yV_pNTlApV_TilaAJpVvNia]VJVNmindigenous-V_Sal^NLilAJpVJNmcommunity-
LlVvN_ma]qpVa_mA_LlNmV]VN_pV_SlAmplqJpqlN!am_TN]Nmaq_pyVm_apa_]y^VpVTApV_T
current risks but also preparing for a future where communities can thrive in an ever-
changing dynamic environment.
4.4 Climate Change Conclusion
3UlaqTUilaAJpVvNia]VJVNmA_LJa^^q_VpyN_TATN^N_p!am_TN]Nmaq_pymplVvNm
pa _AvVTApN pUN Ja^i]NxVpVNm aS A JUA_TV_T J]V^ApN A_L mASNTqAlL Vpm iNai]N
N_vVla_^N_pV_SlAmplqJpqlNA_LNJa_a^VNm3UVmAiilaAJUUN]im^V_V^V|NpUNlVm\mA_L
impacts associated with climate-related hazards. Addressing climate change in hazard
^VpVTApVa_UN]iN_UA_JNmASNlUNA]pUVNlA_L^alNmqmpAV_AI]NJa^^q_VpVNm
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5 Integrating Access and
Functional Needs (AFN)
into Hazard Mitigation
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5.1 AFN Introduction
Modern hazard mitigation planning increasingly recognizes that resilient communities
must address the needs of all residents —including those with access and functional
_NNLm# VmpalVJA]]yV_LVvVLqA]mwVpULVmAIV]VpVNm VNV_J]qLV_TIqp_ap]V^VpNLpa
yaqpU pUamN NJa_a^VJA]]y LNilNmmNL ilNT_A_p NpJ JUla_VJ UNA]pU Ja_LVpVa_m
]A_TqATNIAllVNlmalplA_mialpApVa_LVmALvA_pATNmUAvNbeen underrepresented in
emergency planning. As evidenced by the best practices for stakeholder inclusion and
furpUNl mqiialpNL Iy _ApVa_A] ilNiAlNL_Nmm SlA^Nwal\m V_pNTlApV_T#
considerations leads to plans that are more inclusive and effective. By proactively
N_TATV_T#iaiq]ApVa_mA_LmqiialpATN_JVNmV_NvNlyiUAmNSla^preparedness
pUlaqTUlNJavNlyAUA|AlL^VpVTApVa_i]A_JA_lNLqJN]ammNmV^ilavNNvAJqApVa_A_L
mUN]pNlV_TaqpJa^NmA_LIqV]LplqmpINpwNN_N^NlTN_Jy^A_ATN^N_pATN_JVNmA_L
the communities they serve.
5.2 Inclusion of AFN and Vulnerable Populations in Planning
^A[alJa^ia_N_paSNSSNJpVvN^VpVTApVa_i]A__V_TVmA¬wUa]NJa^^q_VpyAiilaAJU
Incorporating AFN voices into the planning process is crucial because these
stakeholders offer real-world insights into the challenges they face during
emergencies. Key stNimpapUVmilaJNmmV_J]qLNIqpAlN_ap]V^VpNLpa
x 1pA\NUa]LNl _TATN^N_p Ensure that representatives from disability
ALvaJAJyTlaqimJa^^q_Vpy-IAmNLalTA_V|ApVa_mA_LmNlvVJNilavVLNlmmqJU
as local health departments and transportation agencies) are engaged early in
pUNi]A__V_TilaJNmm3UNVlœlmpUA_LNxiNlVN_JNmUN]iVLentify practical barriers
that might otherwise be overlooked.
x Public Participation: _JalialApV_T iqI]VJ mpA\NUa]LNlm pUlaqTU ^NNpV_Tm
mqlvNymA_LapUNlaqplNAJUpaJAipqlNpUNLVvNlmN_NNLmaS#iaiq]ApVa_m
This input is vital to overcoming historical marginalization and ensuring that
mitigation actions are relevant and equitable to the entire population.
x Ongoing Interagency Collaboration: Develop a hazard mitigation planning
advisory committee and interagency working groups that include AFN
stakeholders. These groups can guide both the planning process and the review
aSNxVmpV_Ti]A_mN_mqlV_TpUAp#VmmqNmAlNSq]]yV_pNTlApNLSla^pUN outset.
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5.2.1 Integrating AFN into the Overall AHMP
Integrating AFN considerations is not a stand-A]a_N pAm\ Vp ^qmp IN V_pNl]AJNL
throughout the entire hazard mitigation planning process. This includes:
x 0Vm\mmNmm^N_pmIncorporate AFN data into all risk assessments to ensure that
pUNmiNJVœJvq]_NlAIV]VpVNmaSpUNmNiaiq]ApVa_mAlNlNŔNJpNLV_UA|AlL^AimA_L
vulnerability index data.
x Mitigation Strategy Development:Ensure that every mitigation action is
NxA^V_NLSalVpmV^iAJpa_#iaiq]ApVa_malNxA^i]NwUN_i]A__V_TSal
ŔaaLJa_pla]alwV]LœlNilNvN_pVa_ila[NJpmlNvVNwUawpUNmNila[NJpmJA_IN
improved to meet the needs of people with access and functional needs.
x -]A_ 0NvVNw A_L 4iLApNEnsure planning processes include regular AFN
review and updates. Includes but not limited to:
o Surveys of community needs
o Consultations with AFN advisory groups
o Integration of new technological or infrastructural solutions
x q_LV_T A_L 0NmaqlJN ]]aJApVa_Clearly identify funding streams and
resource commitments for AFN-miNJVœJila[NJpm3UVmJaq]LV_va]vNpAlTNpNL
TlA_pmSla^SNLNlA]ilaTlA^mNTA|AlL"VpVTApVa_mmVmpA_JN mpApNSq_LV_T
LNLVJApNLpaAJJNmmVI]NV_SlAmplqJpqlNV^ilavN^N_pmA_L]aJAl resources such
as the Productivity Investment Fund that can be accessed to improve the
NSSNJpVvN_NmmA_LNSœJVN_JyaSaq_pyaiNlApVa_m
5.3 Assessment of AFN Needs
Understanding the specific needs of AFN populations requires both quantitative and
qualitative approaches:
x ApAa]]NJpVa_A_L0Vm\mmNmm^N_pUse existing resourcesJa^^q_Vpy
mqlvNymoutreach and risk assessments to help identify the number and types
of individuals with AFN at the local community level. Evaluate the regional
TNaTlAiUVJLVmplVIqpVa_vq]_NlAIV]VpVNmA_LmiNJVSVJlNkqVlN^N_pmbefore and
after emergencies.
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x lA^Nwal\mSal_A]ymVmAdopt structured methodologies such as C-MIST
a^^q_VJApVa_"AV_pAV_V_TNA]pU_LNiN_LN_JN1qiialp1ASNpyA_L
Transportation) to assess/ document AFN requirements.
x C-MIST Explanation
o Communication_LVvVLqA]mwVpUUNAlV_TvVmVa_JaT_VpVvNalmiNNJU
limitations may require alternative communication methods to receive
or express information during emergencies.
o Medical / Health Needs: People with complex medical conditions rely
a_^NLVJApVa_m^NLVJA]NkqVi^N_palmiNJVA]V|NLJAlNpa^AV_pAV_
their health and prevent complications.
o Independence3UamNwUaqmN^aIV]VpyLNvVJNmAmmVmpVvNpNJU_a]aTy
or service animals need uninterrupted access to maintain their
independence and daily functions.
o Supervision & Safety: Some individuals require continuous support for
mASNpyJa^SalpalN^apVa_A]wN]]-INV_TV_J]qLV_TpUamNwVpU^N^aly
VmmqNmimyJUVAplVJJa_LVpVa_malV_pN]]NJpqA]LVmAIV]VpVNm
o Transportation: Individuals without personal transportation or with
^aIV]Vpy]V^VpApVa_m_NNLAJJNmmVI]NA_LlN]VAI]NaipVa_mNmiNJVA]]yV_
emergencies and evacuations.
x _pNTlApV_T9q]_NlAIV]VpymmNmm^N_pmLeverage tools from local climate
vulnerability assessments and hazard mitigation plan reviews to identify areas
where AFN populations overlap with high-lVm\|a_NmNTS]aaLi]AV_m
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wildfire-prone areas). This integration helps prioritize mitigation actions in
regions where vulnerable populations are most exposed.
5.4 Coordination with AFN Support Agencies
Effective mitigation planning requires robust coordination with both governmental and
nongovernmental agencies that serve AFN populations. Best practices include:
x Formal Partnerships: Establish relationships and partnerships with agencies
mqJUAmiqI]VJUNA]pULNiAlp^N_pmmaJVA]mNlvVJNmplA_mialpApVa_AqpUalVpVNm
community-IAmNLalTA_V|ApVa_mA_LLVmAIV]VpyALvaJAJyalTA_V|ApVa_m3UNmN
iAlp_NlmUVimN_mqlNpUAppUNlNVmJ]NAla_Toing communication and that roles
A_LlNmia_mVIV]VpVNmAlNLN]V_NApNLINSalNLqlV_TA_LASpNlLVmAmpNlm
x Joint Training and Exercises: a_LqJplNTq]Al[aV_p^NNpV_TmA_LNxNlJVmNm
that include AFN components and identify additional resources to support the
needs of the AFN community. These actions will help prepare all stakeholders to
work together during a crisis and help identify gaps in current plans.
x Outreach and Information Dissemination: _mqlNpUApA]]V_Sal^ApVa_IapU
pre-V_JVLN_p ilNiAlNL_Nmm ^NmmATNm lNmia_mN ^NAmqlNm A_L iamp-incident
recovery plans are accessible to all audiences. This includes using multiple
]A_TqATNm vAlVaqm Ja^^q_VJApVa_ Sal^Apm NT ]AlTN-ilV_p AqLVa mVT_-
]A_TqATNA_LLVTVpA]Sal^Apm A_LJq]pqlA]]yAiilailVApN^NmmATV_TpalNAJUA]]
segments of the community.
5.5 AFN Conclusion
UA|AlL^VpVTApVa_i]A_IqV]LmASaq_LApVa_SalAlNmV]VN_pV_J]qmVvNJa^^q_Vpy
y
ensuring that AFN and other vulnerable populations are included in every phase of
i]A__V_TSla^V_VpVA]mpA\NUa]LNlN_TATN^N_ppapUNLNvN]ai^N_p aS pAV]alNL
mitigation AJpVa_mA_LJaalLV_ApNLlNmia_mNmplApNTVNmJa^^q_VpVNmJA_^V_V^V|N
disaster impacts and foster long-term resilience. Drawing on best practices from
_ApVa_A]SlA^Nwal\mA_L]aJA]i]A__V_TTqVLNmA_LIyV^i]N^N_pV_T-compliant
shelter operations emergency managers can create a plan that truly serves every
member of the community. This inclusive approach not only saves lives and property
during disasters but also strengthens community trust and the overall effectiveness of
emergency management efforts.
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All-Hazards Mitigation Plan
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6 A|AlLLN_pVœJApVa_A_L
Risk Assessment
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Page 44 of 204
6.1 A|AlLLN_pVœJApVa_%vNlvVNw
3UNUA|AlLVLN_pVœJApVa_A_LlVm\AmmNmm^N_pilaJNmmprovide a foundation for Los
_TN]Nmaq_py¯mUA|AlL^VpVTApVa_i]A__V_TNSSalpmIyVLN_pVSyV_T ilaœ]V_T A_L
AmmNmmV_TpUNlVm\mAmmaJVApNLwVpU_ApqlA]pNJU_a]aTVJA]A_LUq^A_-caused hazards.
This section builds on the framework established in the 2020 HazalL"VpVTApVa_-]A_
incorporating insights from the 2023 Operational Area Emergency Operations Plan
(OA%- pUN4 Los Angeles 3UlNApA_LA|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p
(THIRA) pUN Los Angeles County Climate Vulnerability Assessmentthe State of
A]VSal_VAA|AlL"VpVTApVa_-]A_1"- and the Federal Emergency Management
Agency (FEMA) National Risk Index.
Based on these sources hazards were included and addressed in the 2025 AHMP
AJJalLV_TpapUNVlSlNkqN_JymNvNlVpyA_LV^iAJppa!am_TN]Nmaq_pymNNIN]aw
Table 6-1. Hazards that did not meet the threshold of moderate risk will not be
prioritized within the plan. LLVpVa_A]]y pUlNN _Nw _ApqlA] UA|AlLm xplN^N NAp
laqTUpA_L1NvNlN:V_L3al_ALa and four human-caused hazards "Amm9Va]N_JN
yINl_JVLN_pm3lA_mialpApVa__JVLN_pmA_L-qI]VJNA]pU^NlTN_JVNm are included
in the 2025 AHMP.
Table 6-1 Hazard Inclusion/ Omission
Hazard Comment
Earthquake Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
:V]LœlN Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Heat Wave Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Tornado Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpy A_L V^iAJp pa !am _TN]Nm aq_py Tornado is
incorporated with the Severe Wind/ Tornado hazard ilaœ]N.
Land Movement Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
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Hazard Comment
Lightning Hazard is included in the plan due to its high SlNkqN_Jy
mNvNlVpy A_L V^iAJp pa !am _TN]Nm aq_py Lightening is
incorporated wVpUpUN:V]LœlNand Flooding hazard ilaœ]Nm.
Flooding HazAlLVmV_J]qLNLV_pUNi]A_LqNpaVpmSlNkqN_JymNvNlVpyA_L
impact to Los Angeles County. 3UN ]aaLV_T UA|AlL ilaœ]N
incorporates both Riverine and Coastal Flooding.
Drought HazAlLVmV_J]qLNLV_pUNi]A_LqNpaVpmSlNkqN_JymNvNlVpyA_L
impact to Los Angeles County.
Strong Wind Hazard is included in the i]A_LqNpaVpmSlNkqN_JymNvNlVpyA_L
impact to Los Angeles County. Strong Wind is incorporated
with the Severe Wind and 3al_ALaUA|AlLilaœ]N
Tsunami HazAlLVmV_J]qLNLV_pUNi]A_LqNpaVpmSlNkqN_JymNvNlVpyA_L
impact to Los Angeles County.
Winter Weather Hazard is omitted from the plan due to its minimal SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Hail Hazard is omitted from the plan due to its minimal SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Avalanche Hazard is omitted from the plan due to its minimal SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Cold Wave Hazard is omitted from the plan due to its lack of SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Hurricane Hazard is omitted from the plan due to its lack of SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Ice Storm Hazard is omitted from the plan due to its lack of SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
Volcanic Activity Hazard is omitted from the plan due to its lack of SlNkqN_Jy
mNvNlVpyA_LV^iAJppa!am_TN]Nmaq_py
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!am_TN]Nmaq_pySAJNmAwVLNlA_TNaSUA|AlLmLqNpaVpmTNaTlAiUVJLVvNlmVpy
iaiq]ApVa_LN_mVpyA_LNJa_a^VJmVT_VœJA_JN3UNSa]]awV_TUA|AlLmwNlNVLN_pVœNL
A_LilValVpV|NLSla^pUNilNvVaqm]y^N_pVa_NLmaqlJNmIAmNLa_UVmpalVJA]aJJqllN_JNm
popN_pVA]V^iAJpmA_LSqpqlNlVm\m
1.:V]LœlN
2. Earthquake
3. Extreme Heat
4. Drought
5. Flooding
6. Dam Failure
7. Land Movement
8. Tsunami
9. Severe Wind and Tornado
10. Mass Violence
11. Cybersecurity Incidents
12. Transportation Incidents
13. Public Health Emergencies
^a_TpUNmNUA|AlLmsix wNlNVLN_pVœNLpaINiapN_pVA]]yNxAJNlIApNLIyJ]V^ApN
change V_J]qLV_TwV]LœlNNxplN^NUNApLlaqTUpŔaaLV_T]A_L^avN^N_pA_LmNvNlN
wind and tornadoes. Additional human-caused hazards were included based on the
30V_J]qLV_T^AmmvVa]N_JNJyINlmNJqlVpyV_JVLN_pmplA_mialpApVa_V_JVLN_pm
and public health emergencies. The results of the public Personal Disaster Impact
1qlvNyvA]VLApNLpUAppUNmNUA|AlLmAlNaSmVT_VœJA_pJa_JNl_paJaq_pylNmVLN_pmA risk
assessment table comparing hazards to critical infrastructure is in Appendix C.
Table 6-2 UA_TNmV_NvN]ai^N_pA_L9q]_NlAIV]Vpy
Hazard Change (Increase/ Decrease) 0NAma_
Earthquake No Change While new construction adheres to
modern seismic codes aging
infrastructure in high seismic zones
remain vulnerable. Continued
population growth in older
neighborhoods with limited
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Hazard Change (Increase/ Decrease) 0NAma_
lNplaœppV_TV_JlNAmNmavNlA]]
exposure.
:V]LœlN
(Lightning)
Increase in Vulnerability Urban expansion into Wildland-
Urban Interface (WUI) areas has
increased the number of homes at
risk. Post 2020 development in
UVTUœlNmNvNlVpy|a_NmUAm
Ja_pV_qNLpUaqTULNSN_mVI]N
miAJNlNTq]ApVa_mA_L_NwœlN-
safe planning are improving
resilience for new builds.
Extreme Heat Increase in Vulnerability -aiq]ApVa_LN_mVpyurban heat
islands and development in inland
valleys increases exposure. Older
multi-family units without air
conditioning remain a concern.
More outdoor workers and people
experiencing homelessness (PEH)
add to vulnerable population.
Land
Movement
Stable to Slight Increase Most new development avoids
known landslide-prone areas due
to zoning and geotechnical review.
awNvNl climate-driven
precipitation variability and
wV]LœlNmJa_pV_qNpaLNmpAIV]V|N
slopes in developed areas.
Flooding
(Lightning)
Increase in Vulnerability New impervious surfaces from
development increase stormwater
lq_aSS%]LNlŔaaLJa_pla]
infrastructure is strained under
UNAvVNl^alNSlNkqN_plAV_NvN_pm.
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All-Hazards Mitigation Plan
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Hazard Change (Increase/ Decrease)0NAma_
Drought Increase in Vulnerability Continued population growth and
water demand in arid and semi-
arid zones has outpaced gains in
conservation. Agricultural
vulnerability persists in high desert
areas.
Severe Wind
and Tornado
Increase in Vulnerability Los Angeles County is
experiencing more frequent and
V_pN_mNwV_LNvN_pmV_J]qLV_T
tornadoes. As urban development
NxiA_LmplNNJA_aiVNmA_L
overhead utilities in densely
developed areas continue to
contribute to cascading hazards. In
lNmia_mNNSSalpmAlNq_LNlwAypa
underground utility lines in high-
risk areas.
Tsunami Stable Revised tsunami inundation maps
UAvNlNœ_NLpUNAp-risk zones. New
developments in coastal areas are
largely outside the updated hazard
areas or comply with stricter
coastal building codes.
Dam Failure Stable/ Slight Increase While no new major dams have
INN_Ja_mplqJpNLV_lNJN_pyNAlm
downstream development
continues to increase population
and critical infrastructure exposure
within inundation zones.
County of Los Angeles
All-Hazards Mitigation Plan
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Countytytytyyyytyyyyyyyyyyyyyyyyyy ooofofofofooofofoffofofofoooofooffoofofoffooffofofofooffofffofffoooooooofooooooofooooooooooooooooooooooooooooooofooooooooooooooooooooo LoLos As Angengelesles
AllAAllAAAAAAAAAAA-HazHaazHazazazazazazzzazazzzHazazzzaazazazaazazzzzzzazzzazaazaazzaaaaaaaaarararardardrdrdaarardardrdarardardardardararararaaaardrrardrdrrrrrrrrrddrrrrrrrrss Msititigatgationon PlaPlan
6.2 :V]LœlN
6.2.1 Nature
:V]LœlNmAlNSAmp-^avV_T q_Ja_pla]]NL
œlNmpUApJa_mq^NvNTNpApVa_A_LlAiVL]y
milNALaSpN_pUlNApN_V_T]VvNmmplqJpqlNm
A_L V_SlAmplqJpqlN 3UNmN œlNm JA_ IN
VT_VpNL Iy _ApqlA] JAqmNm mqJU Am
]VTUp_V_T al Uq^A_ AJpVvVpVNm V_J]qLV_T
unattended ca^iœlNm Law_NL iawNl
]V_NmA_LAlma_3UNV_JlNAmV_TSlNkqN_Jy
LqlApVa_A_LV_pN_mVpyaSwV]LœlNmV_!am
Angeles County are possibly linked to the
JUA_TV_T J]V^ApN wVpU UappNl
pN^iNlApqlNm ila]a_TNL LlaqTUpm A_L
reduced humidity levels making the
rNTVa_UVTU]ymqmJNipVI]NpaœlNm
AJpalm_ŔqN_JV_T:V]LœlN
NUAvVal
x Topography: Fires spread
more rapidly on steep slopes
and are often driven by the
Santa Ana winds.
x Fuel LoadN_mNLly
vegetation and high tree mortality increase fire intensity.
x Weather ConditionsVTUpN^iNlApqlNmmpla_TwV_LmA_L]awUq^VLVpy
N]NvApNSVlNlVm\wVpUpUNJUA_TV_TJ]V^ApNJa_plVIqpV_TpaA]N_TpUN_NLSVlN
season.
County of Los Angeles
All-Hazards Mitigation Plan
Page 50 of 204
:V]LœlNmA]maJlNApNmNJa_LAlyUA|AlLmmqJUAmiaalAVlkqA]Vpy]A_Lm]VLNmŔaaLV_T
A_L LNIlVm Ŕawm—especially in areas with recent burn scars where vegetation loss
increases soil instability.
6.2.2 Location
!am_TN]Nmaq_pyVma_NaSpUN^ampwV]LœlN-prone regions in the United States.
Based on the Department of Forestry and Fire Protection (CAL FIRE) Fire Hazard
1NvNlVpy ?a_N 1? ^Aim mVT_VœJA_p wV]LœlN lVm\ NxVmpm V_ pUN 1A_pA "a_VJA
"aq_pAV_m1A_AIlVN]"aq_pAV_m-A]am9NlLNmV]]mA_LPuente Hills. The 2024 THIRA
and Los Angeles County Climate Vulnerability Assessment identify an increasing risk to
communities located in or near these high-risk areas.
!am_TN]Nmaq_pyUAmpUlNNilV^AlywV]LœlN^A_ATN^N_p|a_Nm
x NLNlA]0Nmia_mVIV]VpylNAm0m Lands administered or controlled by
the federal government where federal agencies have administrative and
protection responsibility for wildfires.
x 1pApN0Nmia_mVIV]VpylNAm10m Wildland areas where CAL FIRE is
responsible for suppression efforts.
x !aJA]0Nmia_mVIV]VpylNAm!0m Developed regions where local
ATN_JVNmmqJUAm!am_TN]Nmaq_pyVlNNiAlp^N_p!a ilavVLN
fire protection.
alAINppNlvVmqA]lNilNmN_pApVa_aSpUVm:V]LœlNA|AlLwVpUV_pUN!aq_pyi]A__V_T
AlNAi]NAmNlNSNlN_JNiiN_LVx_J]qLNLV_iiN_LVxAlNmNvNlA]VlNA|AlL
Severity Zone maps for reference.
6.2.3 Extent
JJalLV_Tpa!0¯mVlNA|AlL1NvNlVpy?a_N1? ^Aim!am_TN]Nmaq_py
contains:
x 386.06 square miles (8.11%) classified as Very High Fire Hazard Severity
?a_N1? V_!aJA]0Nmia_mVIV]VpylNAm!0m
x 625.01 square miles (13.13%) classified as Very High (FHSZ) in State
0Nmia_mVIV]VpylNAm10m.
:V]LœlNmiamNAmVT_VœJA_ppUlNAp_apa_]ypUlaqTUpUNV^^NLVApNLA^ATNpUNyJAqmN
pa]VvNmilaiNlpyA_L_ApqlA]lNmaqlJNmIqpA]mapUlaqTUpUNmNJa_LAlyUA|AlLmpUAp
Ja_pV_qNASpNlpUNŔA^NmAlNNxpV_TqVmUNL
_pUNASpNl^ApUaSAœlNJa^^q_VpVNmaSpN_SAJNV_JlNAmNLlVm\maSŔAmUŔaaLmLNIlVm
Ŕawm A_L LNTlALNL AVl kqA]Vpy3UNmN iamp-œlN V^iAJpm JA_ Ja^iaq_L pUN V_VpVA]
LNmplqJpVa_i]AJV_TALLVpVa_A]mplAV_a_V_SlAmplqJpqlNUNA]pUmympN^mA_LlNJavery
efforts.
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6.2.4 History
!am _TN]Nm aq_py UAm NxiNlVN_JNL _q^Nlaqm LNvAmpApV_T wV]LœlNm V_ lNJN_p
LNJALNmV_J]qLV_T
x Canyon Fire (1968) –
ql_NLAJlNmLNmplayNLUa^NmA_L]NL
to mass evacuations.
x Old Topanga Fire (1993) – a_mq^NL AJlNmLNmplayV_T
structures and causing three fatalities.
x Sayre Fire (2008) – NmplayNLmplqJpqlNmV_J]qLV_TavNl^aIV]N
homes.
x Station Fire (2009) – 3UN]AlTNmpSVlNV_!am_TN]Nmaq_pyUVmpaly
Iql_V_T AJlNmLNmplayV_TmplqJpqlNmA_LJAqmV_Tpwa
firefighter fatalities.
x Woolsey Fire (2018) –
ql_NLAJlNmLNmplayNLmplqJpqlNm
and resulted in three fatalities.
x Bobcat Fire (2020) – 1JalJUNL AJlNmLNmplayV_TmplqJpqlNm
and damaging numerous infrastructures in the Angeles National Forest.
x Palisades Fire (2025) – 0Nmq]pNLV_mVT_VSVJA_pLNmplqJpVa_A_L]ammaS]VSN
Iql_V_TAJlNmLNmplayNLAiilaxV^ApN]ymplqJpqlNmA_L
causing 12 civilian fatalities.
x Eaton Fire (2025) – 0Nmq]pNLV_mVT_VSVJA_pLNmplqJpVa_A_L]ammaS]VSN
Iql_V_TAJlNmLNmplayV_TAiilaxV^ApN]ymplqJpqlNmA_L
causing 17 civilian fatalities.
3UNmNœlNmUVTU]VTUppUNV_JlNAmV_TSlNkqN_JyA_LV_pN_mVpyaSwV]LœlNmN^iUAmV|V_T
the urgent need for stronger mitigation and preparedness efforts.
3UN!am_TN]Nmaq_pyAlNAUAmNxiNlVN_JNLSNLNlA]]yLNJ]AlNLwV]LœlNmA_LAlN
shown in the table below. 3UNlNUAvNINN__ampApNilaJ]A^ApVa_mSalwV]LœlNmV_pUN
]AmpœvNyNAlm
NLNlA]]yNJ]AlNL:V]LœlNVlN"A_ATN^N_pmmVmpA_JNNJ]AlApVa_V_!amAngeles County
from 1/1/2020 to 3/28/2025
Date Incident Name No. Category
1/8/2025 A]VSal_VA:V]LœlNmA_L
Winds 4856 Federal Declaration
1/8/2025 California Eaton Fire 5550 Fire Management Assistance Declaration
1/8/2025 California Hurst Fire 5551 Fire Management Assistance Declaration
1/7/2025 California Palisades Fire 5549 Fire Management Assistance Declaration
12/10/2024 California Franklin Fire 5548 Fire Management Assistance Declaration
9/11/2024 California Bridge Fire 5537 Fire Management Assistance Declaration
10/16/2020 A]VSal_VA:V]LœlNm 4569 Federal Declaration
9/13/2020 California Bobcat Fire 5374 Fire Management Assistance Declaration
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6.2.5 Probability
:VpUmNvNlA]TqAlA_pNNLwV]LœlNmNAJUyNAlpUNilaIAIV]VpyaSwV]LœlNVT_VpVa_V_!am
_TN]Nmaq_pyVmTlALqA]]yV_JlNAmV_TLlVvN_]AlTN]yIyJ]V^ApNJUA_TNThere is a
È JUA_JN aS A œlN aJJqllV_T NAJU yNAl wVpUV_ pUN TNaTlAiUVJi]A__V_T AlNA
VmpalVJA]]ywV]LœlNmaJJqllNLINpwNN_ q_NA_L#avN^INlIqplNJN_pyNAlmUAvN
shown a year-laq_LœlNmNAma_LqNpaUappNlLlVNlJa_LVpVa_mA_L^alNV_pN_mN
weather variability.
!a_TNl Lly iNlVaLm lNLqJNL Uq^VLVpy A_L V_JlNAmNL pN^iNlApqlNmJaqi]NLwVpU
historic drought and vegetation die-aSSUAvNJlNApNLJlVpVJA]]yLlySqN]INLm3UNmN
NvN_pm^A\NNvN_m^A]]VT_VpVa_maqlJNmJAiAI]NaSTN_NlApV_T^A[alwV]LœlNm
Santa Ana wV_LmJa_pV_qNpamNlvNAmA^A[alAJJN]NlA_pJa_plVIqpV_TpalAiVLœlN
milNALA_LmNvNlNœlNINUAvVal:UN_Ja^IV_NLwVpUqlIA_N_JlaAJU^N_pV_paœlN-
ila_N AlNAm pUNmN Ja_LVpVa_m N]NvApN IapU pUN SlNkqN_Jy A_L LNmplqJpVvN_Nmm aS
wV]LœlNm
Projections from the 2024 THIRA and the LA County Climate Vulnerability Assessment
Ja_œl^pUApwV]LœlNilaIAIV]VpywV]]Ja_pV_qNpalVmNq_]NmmmVT_VœJA_pSqN]lNLqJpVa_
]A_L qmN i]A__V_T A_L J]V^ApN ALAipApVa_ mplApNTVNm AlN V^i]N^N_pNL AJlamm A]]
jurisdictions.
The 2024 THIRA estimates that:
x Over 1.2 million residents live in high-risk wildfire zones.
x Communities near the Wildland-Urban Interface (WUI) are at the greatest
lVm\NmiNJVA]]ypUamNwVpU]V^VpNLNvAJqApVa_laqpNmA_LpUNJJNmmA_L
Functional Needs community.
x 9q]_NlAI]Niaiq]ApVa_mV_J]qLV_TmN_Valm]aw-V_Ja^NUaqmNUa]LmA_L
iNai]NwVpULVmAIV]VpVNmSAJNUNVTUpN_NLJUA]]N_TNmLqlV_TNvAJqApVa_m.
6.2.6 Vulnerability
!am_TN]Nmaq_pySAJNmUVTUwV]LœlNvq]_NlAIV]VpyLqNpaVpmNxpN_mVvN:V]L]A_L-
4lIA__pNlSAJN:4 wVpUavNl^V]]Va_lNmVLN_pmpUAp]VvNV_9NlyHigh Fire Hazard
Severity Zones (FHSZs). These communities are particularly susceptible because many
Ua^Nm ]AJ\ LNSN_mVI]N miAJN œlN-lNmVmpA_p Ja_mplqJpVa_ al ALNkqApN N^NlTN_Jy
access.
9q]_NlAI]N iaiq]ApVa_m V_J]qLV_T Iqp _ap ]V^VpNL pa mN_Valm V_LVvVLqA]m wVpU
LVmAIV]VpVNm ]aw-V_Ja^NUaqmNUa]LmA_LpUamNLNiN_LN_pa_N]NJplVJA]^NLVJA]
NkqVi^N_p SAJN mVT_VœJA_p NvAJqApVa_ A_L UNA]pU lVm\m LqlV_T wV]LœlN NvN_pm
especially in WUI communities with limited ingress/egress and high fuel loads.
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Contextual Overview
Very High FHSZ in LRA jurisdiction includes dense hillside residential areas under local
œlNAqpUalVpylNmia_mVIV]Vpy3UNmNAlNma^NaSpUN^ampvq]_NlAI]NJa^^q_VpVNmLqN
papNllAV_vNTNpApVa_A_LJa_mplAV_NLN^NlTN_JyAJJNmm
lVpVJA]V_SlAmplqJpqlNVmA]maAplVm\wVpUwV]LœlNNxiamqlNpUlNApN_V_TœlNmpApVa_m]Aw
N_SalJN^N_p SAJV]VpVNm UamiVpA]m qpV]VpVNm plA_mialpApVa_ JallVLalm A_L N^NlTN_Jy
Ja^^q_VJApVa_mympN^mVmlqipVa_papUNmNNmmN_pVA]mNlvVJNmLqlV_TwV]Lœre events
can compound vulnerabilities and delay response and recovery. For a better
understanding of critical infrastructure at risk please see Appendix C.
Total Facilities Affected:
x 9NlyVTU!0: 120
x VTU10: 8
x 9NlyVTU10: 76
:VpUpUNJa_pV_qNLNxiA_mVa_aSLNvN]ai^N_pmV_paœlN-ila_NAlNAmUAmmVT_VœJA_p]y
V_JlNAmNLwV]LœlNlVm\"A_yUa^NmV_pUN:4]AJ\ilaiNlLNSN_mVI]NmiAJNA_LœlN-
lNmVmpA_pIqV]LV_T^ApNlVA]m^A\V_TpUN^iAlpVJq]Al]yvq]_NlAI]NLLVpVa_A]]y]V^Vped
evacuation routes in some WUI communities create challenges for emergency
lNmia_mNA_LNvAJqApVa_m1plVJpNl|a_V_T]AwmIqV]LV_TlNTq]ApVa_mA_LvNTNpApVa_
management policies are the best practices to reduce risk.
14-091%0!1303
0 %:#
Supervisorial District Population in High-0Vm\
Wildfire Zones
Percentage of District
Population
District 1 150,000 12%
District 2 75,000 6%
District 3 425,000 30%
District 4 250,000 20%
District 5 500,000 32%
County of Los Angeles
All-Hazards Mitigation Plan
Page 54 of 204
Department/
Agency
9NlyVTU1?
!0
VTU1?10 9NlyVTU1?
10
Animal Care and
Control 1 0 1
Fire Department 39 1 14
Health Services 1 0 0
Library 7 1 2
LACMA / NHM 1 0 0
%SœJNaS
Education 3 0 3
Other County
%SœJNm 0 0 0
-Al\mË
0NJlNApVa_ 13 1 12
Public Health 52 4 41
Public :al\m 0 0 0
Sheriff’s
Department 3 1 3
:V]LœlNmpUlNApN_NmmN_pVA]V_SlAmplqJpqlNV_J]qLV_T
x Transportation: Damage to roads and bridges affects evacuation and
emergency response.
x Utilities-awNl]V_NmTAmiViN]V_NmA_LwApNlV_SlAmplqJpqlNV_J]qLV_T
LA^mAlNvq]_NlAI]NpaSVlNLA^ATN
x Emergency Services: Public safety and healthcare facilities near wildfire-
prone areas face operational disruptions.
x Public Services-Al\m]VIlAlVNmmJUaa]mA_LapUNliqI]VJAlNAmJaq]LIN
lost or damaged.
County of Los Angeles
All-Hazards Mitigation Plan
Page 55 of 204
#NwN^NlTV_TiAppNl_mmqTTNmppUApJ]V^ApNJUA_TN^AyINV_ŔqN_JV_TwV]LœlNlVm\m
in Los Angeles County through:
x Extending fire seasons: VmpalVJA]]yiNA\SVlNmNAma_aJJqllNLSla^ q_N
pa#avN^INlIqpSVlNmAlN_awmpAlpV_TA_Lburning year-round.
x Increasing fuel dryness: Higher temperatures and prolonged droughts
lNLqJNvNTNpApVa_^aVmpqlN]NvN]m^A\V_TSVlNm^alNV_pN_mN
x 0AVmV_TSVlNSlNkqN_JyappNlLlVNlJa_LVpVa_mJa_plVIqpNpa^alN
SlNkqN_pVT_VpVa_miAlpVJq]Al]yV_:4AlNAm.
Extent of Exposure
x Total Area Exposed : 243.72 sq mi
x Supervisorial Districts (SD) Impacted:
o SD3: 117.95 sq mi (27.29%)
o SD5: 95.61 sq mi (3.36%)
o SD1: 16.23 sq mi (4.60%)
o SD4: 9.10 sq mi (4.27%)
o SD2: 4.83 sq mi (1.33%)
alAINppNlvVmqA]lNilNmN_pApVa_aSpUVm:V]LœlNA|AlLwVpUV_pUN!aq_pyi]A__V_T
AlNAi]NAmNlNSNlN_JNiiN_LVx for several Fire Hazard Severity Zone maps.
6.2.7 Impacts
^iAJpmSaliAmpœlNmvAlyLNiN_LV_Ta_ scope and severityV_J]qLV_TpUN A_qAly
œlNmV_J]qLV_TpUN-A]VmALNmA_LApa_VlNmlNmq]pNLV_wVLNmilNALLNmplqJpVa_
AJlamm !am_TN]Nm aq_py Iql_V_T avNl AJlNm A_L LNmplayV_T ^alN pUA_
mplqJpqlNm Ja^IV_NL wVpU _NAl]y JVvV]VA_ SApA]VpVNm3UNmN NvN_pm JAqmNL
cascading impacts mqJU Am ila]a_TNL iawNl aqpATNm LNTlALNL wApNl ilNmmqlN
ASSNJpV_TœlNœTUpV_TA_LlNmVLN_pVA]mqii]yA_LavNlwUN]^NLN^NlTN_JymNlvVJNm
Transportation routes and communications infrastructure were disrupted.
a^^q_VpVNmNmiNJVA]]yV_pUN:V]L]A_L-Urba__pNlSAJN:4 NxiNlVN_JNL^A[al
NJa_a^VJ]ammNmLqNpapUNLNmplqJpVa_aSUa^NmIqmV_NmmNmA_LiqI]VJSAJV]VpVNm
Post-œlN UA|AlLm ]V\N LNIlVm Ŕawm A_L ]A_Lm]VLNm SqlpUNl Ja^iaq_LNLlNJavNly
JUA]]N_TNm wVpU wApNl V_SlAmplqJpqlN Ja_pA^V_ApVa_ A_Lsedimentation requiring
N^NlTN_Jy lN^NLVApVa_ 3UN mJaiN A_L mNvNlVpy aS pUNmN œlNm q_LNlmJalN pUN
increasing vulnerability of critical infrastructure and the urgent need for enhanced
mitigation strategies across high-risk zones.
County of Los Angeles
All-Hazards Mitigation Plan
Page 56 of 204
Problem Statement
Many hillside communities within LRA Very High FHSZ zones face critical access and
wApNlmqii]yVmmqNmLqlV_TœlNm3UNmNAlNAmaSpN_V_J]qLNATV_TmplqJpqlNmA_L_Allaw
laALmJa^i]VJApV_TœlNœTUpV_TA_LNvAJqApVa__vNmp^N_pmV_LNSN_mVI]NmiAJN]aJal
JaLNN_SalJN^N_pA_LJa^^q_VpywV]LœlNilapNJpVa_i]A__V_TAlNvVpA]pamAvV_T]VvNm
and minimizing losses.
6.2.8 Mitigation and Preparedness
Los Angeles County is implementing a multi-ATN_JyAiilaAJUpa^VpVTApNwV]LœlNlVm\m
Key strategies include:
x Community Wildfire Protection Plans (CWPPs): Strengthening fire
prevention measures in high-risk areas.
x Community Preparedness: Educating residents on wildfire readiness
pUlaqTUaqplNAJUJA^iAVT_mN^NlTN_JyA]NlpmympN^mA_L_NVTUIalUaaL
preparedness programs.
x NSN_mVI]N1iAJN0NkqVlN^N_pmEnforcing brush clearance around
structures.
x Enhanced Building Codes: Promoting fire-resistant materials for new
developments.
x 9NTNpApVa_"A_ATN^N_pReducing fuel loads through prescribed burns
and hazardous tree removal.
x Evacuation Planning: ^ilavV_TJaalLV_ApVa_INpwNN_%"!1
!aA_LapUNl[qlVmLVJpVa_mpaN_mqlNJ]NAlNvAJqApVa_ia]VJVNmA_L
procedures.
LLVpVa_A]LNpAV]ma_pUNaq_py¯milaAJpVvNA_La_TaV_TNSSalpmpalNLqJNwV]LœlNlVm\
including long-pNl^ i]A__V_T V_SlAmplqJpqlN UAlLN_V_T A_L Ja^^q_Vpy-based
V_VpVApVvNmVm]aJApNLV_pUNLNLVJApNLmNJpVa_pVp]NL¬"VpVTApVa_1plApNTVNm
6.2.9 Summary
:V]LœlNmlN^AV_a_NaSpUN^ampmVT_VœJA_pUA|AlLmV_!am_TN]Nmaq_pyiamV_TlVm\m
pa]VSNilaiNlpyA_LJlVpVJA]V_SlAmplqJpqlN3UNNxiA_mVa_aSLNvN]ai^N_pV_pa:4
AlNAmV_JlNAmV_TœlNmNvNlVpyLqNpaJ]V^ApNJUA_TNA_La_TaV_TJUA]]N_TNmwVph
NvAJqApVa_ A_L ^VpVTApVa_ lNkqVlN ilaAJpVvN JaalLV_ApNL NSSalpm AJlamm ATN_JVNm
1plN_TpUN_V_TœlNilNvN_pVa_ia]VJVNmV^ilavV_TN^NlTN_JylNmia_mNJaalLV_ApVa_
A_L V_pNTlApV_T J]V^ApN ALAipApVa_ ^NAmqlNm AlN NmmN_pVA] pa N_UA_JV_T wV]LœlN
resilience for Los Angeles County.
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All-Hazards Mitigation Plan
Page 57 of 204
6.3 Earthquake
6.3.1 Nature
Earthquakes occur due to the sudden release
aSN_NlTyV_pUNAlpUµmJlqmpTN_NlApV_T
seismic waves that cause ground shaking.
3UNmNNvN_pmaSpN_plVTTNlNLIy^avN^N_p
A]a_TSAq]p]V_NmvAlyV_V_pN_mVpyLNiN_LV_T
a_SAJpalmmqJUAm^AT_VpqLNLNipUA_L
proximity to populated areas. In addition to
pUNV_VpVA]mUA\V_TmNJa_LAlyUA|AlLmmqJUAm
mqlSAJN SAq]pV_T ]VkqNSAJpVa_ ]A_Lm]VLNm
tsunamis A_L ASpNlmUaJ\m JA_ walmN_ pUN
LA^ATN !am _TN]Nm aq_py ]aJApNL V_ A
UVTU]yAJpVvNmNVm^VJlNTVa_SAJNmmVT_VœJA_p
risks from thNmN_ApqlA]NvN_pm_NJNmmVpApV_T
extensive mitigation efforts and
preparedness planning.
x The most common effects of
NAlpUkqA\Nm V_J]qLN vVa]N_p mUA\V_T
mplqJpqlA]LA^ATNA_LLVmlqipVa_mpaV_SlAmplqJpqlN
x 1NJa_LAlyNSSNJpmJA_V_J]qLNIqpAlN_ap]V^VpNLpaqpV]VpVNmaqpATNmplASSVJ
Ja_TNmpVa_A_LplA_mialpApVa_mympN^mINV_TV^iAmmAI]NA_LA_V_JlNAmNaSSVlN
lVm\mSla^Ila\N_TAmA_LwApNl]V_Nm
CouCCCCouCouCouCouCouCououououCouCoCooouCuntnntntyntytytyntynnnnnnnnn ofoffoffof LoLoLos As As As As A AAAAs AsAs As As Angengengengeeeengengegengengengengengegengegengeeeegeengengeengengeggengngennnglesleslesesleslesesleslesleslesleslesslesesleslesslesessesleseseslsseseeesees
AllAllAAllAllAllAllAllAllAlllAllAlAlAlllAllAAAllAllAlAlAAl------------HazazHazHazHazHazHazazzHazHazHazazHazHazazHaHaHazHazHazazazHazazHazHazazzzzzHaardardardardardardardardardardardardrdardardardardrdardarddarddardaaardaardaarddardarddrdrdardardrdaa MsMsMsMsMsMsMsMsMsMMsMMsMsMMsMsMsMsMsMsMsMMsMs MMMs MMs Ms MsMsMs MssMsss Msitiitiiiitiititiiiitiiititiitiitititiitttttitittiititittitiiitiitiggatgatttgatattgattgatgatggagatgatgatgatttgggatgagatttgattataggagiiiionionnioniononiononionioniononniiononnnioonnnooonioonniioionnio aPlaPlalaPlaPlaaPlaPlaaPllPlPlaPlalPPlaPlaPlaPllPlPlPlPlPlPlPlaPlaPlaaPPlaPlaPlPaaPlaPllaPlnnnnnnnnnnnnnnnnn
County of Los Angeles
All-Hazards Mitigation Plan
Page 58 of 204
x AlpUkqA\NmaJJqlwVpU]Vpp]Npa_awAl_V_T^A\V_TilNiAlNL_NmmNmmN_pVA]Sal
minimizing loss of life and property.
6.3.2 Location
!am_TN]Nmaq_pyVma_NaSpUN^ampmNVm^VJA]]yAJpVvNlNTVa_mV_pUN4_VpNL1pApNm
with multiple active fault systems capable of generating destructive earthquakes.
Major faults include:
x San Andreas Fault – Capable of M 8.0+
x Newport-Inglewood Fault – M 7.4
x Malibu Coast Fault System – M 6.7
x San Fernando Fault – M 6.6
x Santa Monica Fault – M 7.0
x Whittier Fault – M 7.2
x Sierra Madre Fault – M 6.0-7.0
For a better visual representation of this Earthquake Hazard within LA County planning
AlNAi]NAmNlNSNlN_JNiiN_LVxfor earthquake fault maps.
6.3.3 Extent
JJalLV_Tpa41Na]aTVJA]1qlvNypUNlNAlNpwapyiNmaSNAlpUkqA\N^NAmqlN^N_pm
magnitude (Mw) and intensity (i). Magnitude is a measure of the energy released at the
source of the earthquake. Intensity scale help measure impact on people and
structures.
AlpUkqA\NV^iAJpVmIAmNLa_^AT_VpqLNmJA]NVmAmSa]]awm:
x Great—"wÁ
x Major—Mw = 7.0 – 7.9
x Strong—Mw = 6.0 – 6.9
x Moderate—Mw = 5.0 – 5.9
x Light—Mw = 4.0 – 4.9
x Minor—Mw = 3.0 – 3.9
x Micro—Mw < 3
County of Los Angeles
All-Hazards Mitigation Plan
Page 59 of 204
"aLVœNL"Nlcalli Intensity 1JA]NVmSla^pa;wUVJUlNSNlmAm_apSN]pA_L;Am
extreme.
Figure 6.3.1 "aLVœNL"Nlcalli Intensity Scale
Over 75% of unincorporated Los Angeles County is at risk for severe to extreme
shaking in a future earthquake.
3UNlNTVa_µmLN_mNqlIA_N_vVla_^N_pJa^IV_NLwVpUATV_TV_SlAmplqJpqlNV_JlNAmNm
the likelihood of extensive damage and prolonged recovery times.
Faults running beneath critical V_SlAmplqJpqlNJallVLalmV_J]qLV_TSlNNwAymA_LiawNl
TlVLmiamNAmVT_VœJA_ppUlNAppaiqI]VJmASNpyA_LNJa_a^VJmpAIV]Vpy of the planning
area.
County of Los Angeles
All-Hazards Mitigation Plan
Page 60 of 204
6.3.4 History
!am_TN]Nmaq_pyUAmA]a_TUVmpalyaSLNmplqJpVvNNAlpUkqA\NmwVpUma^NaSpUN
earliest recorded events dating back to the early 19th century. The San Juan Capistrano
AlpUkqA\N aS " wAm A^a_T pUN œlmp pa IN LaJq^N_pNLJAqmV_TpUN
collapse aS"VmmVa_1A_ qA_AiVmplA_aA_LlNmq]pV_TV_SApA]VpVNm%vNlpUNyNAlm
pUNJaq_pyUAmNxiNlVN_JNL_q^NlaqmmVT_VœJA_pkqA\NmV_J]qLV_TpUNLNvAmpApV_T
alp3N[a_AlpUkqA\N" pUN1A_Nl_A_LaAlpUkqA\N" A_L
the infamous #alpUlVLTNAlpUkqA\N" wUVJUJAqmNLIV]]Va_mV_LA^ATNm
and led to widespread infrastructure failures. There have been no federal declarations
or state proclamations for earthquakes V_pUN]AmpœvNyNAlm
"A[alAlpUkqA\NmV_!am_TN]Nmaq_py– Present)
Date Magnitude Name / Location Notable Impact
NJN^INl
1812 7.5
San Juan
Capistrano
Earthquake
Destroyed Mission San Juan
AiVmplA_a\V]]NLiNai]N
NJN^INl
1812 7.1 West Ventura
Earthquake
AqmNLmVT_VœJA_pmUA\V_TV_
Southern California.
A_qAly 7.9 Fort Tejon
Earthquake
Largest earthquake on the San
_LlNAmAq]plqipqlNL
miles.
q]y 7.5 Kern County
Earthquake
Strong shaking felt in Los
_TN]Nm^A[alLA^ATNpa
A\NlmœN]L
NIlqAly 6.6 San Fernando
Earthquake
LNApUm¸ ^V]]Va_V_
LA^ATNmJa]]AimNaS9NpNlA_m
Hospital.
%JpaINl 5.9 Whittier Narrows
Earthquake
LNApUmV_[qlVNm¸
million in damages.
NIlqAly
1990 5.7 Upland Earthquake V_[qlVNm¸^V]]Va_V_
damages.
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All-Hazards Mitigation Plan
Page 61 of 204
6.3.5 Probability
Trends in Seismic Activity
Over 163 earthquakes of M 5.0 or greater have been recorded in Southern California
since 1812.
3UN1A__LlNAmAq]plN^AV_mpUNTlNApNmpmNVm^VJUA|AlLwVpUA ÈJUA_JNaSA_"
6.7+ event in the next 30 years.
qpqlNAlpUkqA\N%JJqllN_JN
The U.S. Geological Survey (USGS) estimates the following probabilities for a major
earthquake in Los Angeles County in the next 30 years:
x 60% chance of an M 6.7+ earthquake
x 46% chance of an M 7.0+ earthquake
x 31% chance of an M 7.5+ earthquake
6.3.6 Vulnerability
3UN Jaq_py¯m vq]_NlAIV]Vpy pa NAlpUkqA\Nm NxpN_Lm INya_L iUymVJA] V_SlAmplqJpqlN
ASSNJpV_TVpmlNmVLN_pmA_LNmmN_pVA]mNlvVJNm%]LNlIqV]LV_TmiAlpVJq]Al]yq_lNV_SalJNL
masonry and soft-mpaly mplqJpqlNm AlN Ap UVTU lVm\ aS Ja]]AimN iamV_T mVT_VœJA_p
q_N 5.6 Sierra Madre
Earthquake
LNApU½V_[qlVNm¸
million in damages.
A_qAly 6.7 Northridge
Earthquake
LNApUmV_[qlVNm¸
IV]]Va_V_LA^ATNmSlNNwAym
collapsed.
q]y 5.5 Chino Hills
Earthquake
V_[qlVNm^V_almplqJpqlA]
damage.
"AlJU 5.1 La Habra
Earthquake
NwV_[qlVNm¸^V]]Va_V_
damages.
q]y 7.1 Ridgecrest
Earthquake
Widespread damage in
1aqpUNl_A]VSal_VA
infrastructure impacts.
County of Los Angeles
All-Hazards Mitigation Plan
Page 62 of 204
dangers to residents and businesses. 1NVm^VJlNplaœppV_TNAl]ywAl_V_TmympN^mA_L
mplVJpNlIqV]LV_TJaLNmUAvNV^ilavNLlNmV]VN_JNIqp vulnerabilities remain in older
structures and critical infrastructure.
lVpVJA]_SlAmplqJpqlNAp0Vm\
x Highways, bridges, and transportation routes: A major earthquake could
mNvNlN]yLVmlqip^aIV]Vpyshipment of goods and services while also delaying
emergency response and evacuations. "A[alUVTUwAymmqJUAmIqp_ap]V^VpNL
to the I- -41---- -A_L-105 could be impacted.
x Energy grids and water system: Disruptions could leave millions without
power and clean water.
x Hospitals and emergency services: UamiVpA]mA_LœlNmpApVa_mV_pUN
Los Angeles County could suffer functional impairments.
x Unreinforced masonry and soft-story buildings: Many older structures are
highly susceptible to collapse during strong ground shaking.
aq_py1iNJVœJlVpVJA]AJV]VpVNmSSNJpNL
x Fire Department: 314 facilities (93.18%)
x Public Works: 201 facilities (87.39%)
x Health Services: 56 facilities (85.71%)
x Public Health: 37 facilities (92.50%)
x Libraries: 78 branches (89.66%)
x Parks: 179 (97.79%)
x Education: 70 (85.37%)
!am_TN]Nmaq_py]VNmAppUNV_pNlmNJpVa_aS^q]pVi]N^A[alSAq]p]V_NmV_J]qLV_TpUN
1A__LlNAmAq]pJJalLV_TpapUNUA|AlL^AplVxpUNlVm\aSvVa]N_pTlaq_LmUA\V_TVm
ilNvA]N_p Jaq_pywVLN iAlpVJq]Al]y V_ qlIA_ JN_pNlm A_L lNTVa_m wVpU JlVpVJA]
infrastructure. The potential consequences of violent seismic shaking include
wVLNmilNALmplqJpqlA]LA^ATNLVmlqipVa_aSmNlvVJNmNJa_a^VJ]ammNmA_LUq^A_
casualties.
-aiq]ApVa_mAp0Vm\
x The THIRA estimates over 2 ^V]]Va_lNmVLN_pmJaq]LINmVT_VœJA_p]yV^iAJpNLV_
A^A[almNVm^VJNvN_piAlpVJq]Al]ypUamNV_UVTU-risk seismic zones.
County of Los Angeles
All-Hazards Mitigation Plan
Page 63 of 204
x People Experiencing Homelessness (PEH) populations: ½ unhoused
individuals in Los Angeles County live in areas at risk of violent shaking.
x Low-income and individuals with access and functional needs (AFN): For more
details on impacted population please see Section 5.
Extent of Exposure
x Total Area Exposed mk^V
x Supervisorial Districts (SD) Impacted:
o SD5 mk^V È
o SD3: 379.41 sq mi (87.99%)
o SD1: 349.17 sq mi (98.95%)
o SD2: 362.95 sq mi (99.99%)
o SD4: 210.92 sq mi (99.10%)
6.3.7 Impacts
Los Angeles County has a long history of experiencing damaging earthquakes due to
Vpm]aJApVa_A]a_T^q]pVi]NAJpVvNSAq]pmympN^mV_J]qLV_TpUN1A__LlNAm#Nwialp-
_T]NwaaLA_L:UVppVNlSAq]pmVmpalVJNAlpUkqA\NmmqJUAmpUN1A_Nl_A_La
(M6.6) and 1994 Northridge (M6.7) events caused catastrophic losses. The San
Nl_A_LaNAlpUkqA\NlNmq]pNLV_ LNApUmpUNJa]]AimNaSUamiVpA]mplqJpqlNmA_L
avNl¸ ^V]]Va_V_LA^ATNmwUV]NpUN#alpUlVLTNNAlpUkqA\NJAqmNL LNApUm
^alNpUA_V_[qlVNmA_LA_NmpV^ApNL¸IV]]Va_V_NJa_a^VJ]ammNmV_J]qLV_T
widespread infrastructure failures such as collapsed freeways and damaged utility
systems.
Impacts from future major seismic events are projected to be even more severe due to
iaiq]ApVa_LN_mVpyATV_TV_SlAmplqJpqlNA_LV_JlNAmV_TLNvN]ai^N_pV_mNVm^VJA]]y
vulnerable areas. Over 75% of unincorporated Los Angeles County is at risk of severe
to extreme ground shaking. Current estimates suggest that a large-magnitude
NAlpUkqA\NJaq]LLVmi]AJNqipa^V]]Va_iNai]NV_[qlNal\V]]pUaqmA_LmA_LlNmq]p
V_avNl¸IV]]Va_V_Ja^IV_NLNJa_a^VJ]ammNmV_J]qLV_T¸IV]]Va_V_ilaiNlpy
LA^ATNA_L¸IV]]Va_V_IqmV_NmmV_pNllqipVa_m
County of Los Angeles
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3UN aq_py¯m JlVpVJA] mympN^m iawNl wApNl plA_mialpApVa_ UNA]pUJAlN A_L
Ja^^q_VJApVa_mAlNNmiNJVA]]yvq]_NlAI]N^A[alNAlpUkqA\NJaq]LV^iAVlqipa
UamiVpA]m A_L œlN mpApVa_m A_L LVmlqip JlVpVJA] V_SlAmplqJpqlN Sal ^V]]Va_m
Population mwVpUUNVTUpN_NLvq]_NlAIV]VpyV_J]qLNpUN ½iNai]NNxiNlVN_JV_T
Ua^N]Nmm_Nmm pUamN wVpU AJJNmm A_L Sq_JpVa_A] _NNLm A_L lNmVLN_pm aS a]LNl
unreinforced masonry and soft-story structures.
:VpUaqpmqSœJVN_p^VpVTApVa_ASqpqlNNAlpUkqA\NJaq]LlNmq]pV_JAmJALV_TSAV]qlNm
across multiple sectors and prolong the County’s recovery for years. These risks
UVTU]VTUp pUN qlTN_Jy Sal Ja_pV_qNL V_vNmp^N_p V_ mNVm^VJ lNplaœppV_T mplVJpNl
enforcemN_paSIqV]LV_TJaLNmNxiA_LV_TmpApNwVLNNAl]ywAl_V_TmympN^m A_L
equitable preparedness programs targeting at-risk vulnerable populations.
x Casualties and injuries: NiN_LV_Ta_pUNpV^NaSLAyA_L]aJApVa_pUaqmA_Lm
could be injured or killed in a severe earthquake.
x Economic disruption: mVT_VœJA_pNAlpUkqA\NJaq]LUA]pIqmV_NmmaiNlApVa_m
LA^ATNmqii]yJUAV_mA_LSalJNpUaqmA_LmV_paq_N^i]ay^N_p
x Housing displacement: _NmpV^ApNL^V]]Va_lNmVLN_pmJaq]LINLVmi]AJNL
with tens of thousands requiring emergency sheltering.
Economic Impact
A major earthquake in Los Angeles County Jaq]LlNmq]pV_avNl¸IV]]Va_V_NJa_a^VJ
]ammNm wVpUApapA]aS¸plV]]Va_-dollar exposure. Losses can include:
x ¸IV]]Va_V_IqmV_NmmV_pNllqipVa_m
x ¸ IV]]Va_V_]ampNJa_a^VJAJpVvVpy
x ¸IV]]Va_V_ilaiNlpyLA^ATNm
Problem Statement
The pervasive exposure of Los Angeles County to violent earthquake shaking presents
AmympN^VJpUlNAppaiqI]VJmASNpyNJa_a^VJmpAIV]VpyA_LNmmN_pVA]mNlvVJNm#NAl]yA]]
major departments and infrastructure elements are located within high-shaking hazard
|a_Nm3UN NxpN_mVvN lNAJU AJlamm A]] œvN 1qiNlvVmalVA] VmplVJpm 1 A^i]VœNm pUN
JUA]]N_TN UVTU]VTUpV_T pUN qlTN_p _NNL Sal lNplaœppV_T iqI]VJNLqJApVa_
ilNiAlNL_NmmilaTlA^mA_LlNmV]VN_pLNmVT_ia]VJVNmAV]qlNpaALLlNmmpUVmUA|AlL
could lead to catastrophic loss of life and functionality in the event of a major seismic
event.
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6.3.8 Mitigation and Preparedness
Efforts to reduce earthquake risks in Los Angeles County include strengthening
IqV]LV_T JaLNm N_UA_JV_T N^NlTN_Jy ilNiAlNL_Nmm A_L lNplaœppV_T vq]_NlAI]N
structures.
NyNSSalpmpa^VpVTApNNAlpUkqA\NlVm\mV_J]qLN
x 1plN_TpUN_V_TIqV]LV_TJaLNmA_LN_SalJV_TlNplaœppV_T]Awm
x Upgrading critical infrastructure
x Expanding public education and early warning systems
x Enhancing emergency response planning
y ilaAJpVvN]y V^i]N^N_pV_T pUNmN ^NAmqlNm !am_TN]Nm aq_pyAV^m pa lNLqJN
JAmqA]pVNmV_SlAmplqJpqlNLA^ATNA_LNJa_a^VJ]ammNmV_SqpqlNmNVm^VJNvN_pm
1NVm^VJ0NplaœppV_T-laTlA^m
x 1aSpmpalylNplaœpilaTlA^: Mandates seismic upgrades for older apartment
buildings.
x Non-LqJpV]NJa_JlNpNIqV]LV_TlNplaœpm: Strengthens older commercial and
residential structures.
x amiVpA]m A_L N^NlTN_Jy SAJV]VpVNm lNplaœppV_T: Ensures critical services
remain operational post-earthquake.
-a]VJyA_L0NTq]Apaly"NAmqlNm
x Assembly Bill (AB) 1857: Strengthens building standards for multi-story
structures.
x AB 2681: Requires cities and counties to inventory vulnerable buildings.
x Updated California Building Code (CBC): Enforces stricter seismic design
criteria for new construction.
x Public Education: 3NAJUV_TpalaiavNlA_La]L%_pUNUaqmNUa]L
ilNiAlNL_NmmJUNJ\]VmpNLqJApNlNmVLN_pma_N^NlTN_JylNmia_mNlNplaœppV_T
and disaster preparedness.
x Early Warning/ ShakeAlert System: Provides real-time earthquake early warnings
to residents via mobile alerts and public messaging.
x Public earthquake drills: Annual Great California ShakeOut encourages
preparedness.
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6.3.9 Summary
!am_TN]Nmaq_pylN^AV_mApUVTUlVm\SalLNvAmpApV_TNAlpUkqA\NmwVpUmJVN_pVœJ
ila[NJpVa_mV_LVJApV_TAmpla_T]V\N]VUaaLaSAmVT_VœJA_pmNVm^VJNvN_pV_pUNJa^V_T
LNJALNm 3UN lNTVa_ UAm NxiNlVN_JNL _q^Nlaqm UVmpalVJ NAlpUkqA\Nm A_L pUN
potential for future large-scale disasters remains ever-present. While advances in
N_TV_NNlV_T N^NlTN_Jy ilNiAlNL_Nmm A_L ^VpVTApVa_ NSSalpm UAvN V^ilavNL
lNmV]VN_JN JUA]]N_TNm iNlmVmp iAlpVJq]Al]y lNTAlLV_T ATV_T V_SlAmplqJpqlN A_L
vulnerable communities. ConpV_qNLV_vNmp^N_pmV_lNplaœppV_TiqI]VJNLqJApVa_A_L
NAl]ywAl_V_TmympN^mwV]]INJlVpVJA]V_^V_V^V|V_TJAmqA]pVNmNJa_a^VJ]ammNmA_L
recovery challenges in future earthquakes.
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CouCouCouCouCCouCouCouCououCoCouCouCouCououCououCouCouCouCouCouCouCouCououCouuCCooCouCouCouCououCoCoCouCoCoCouCCCouCCoouuCCoooCoCoCCounnntntyntynntyntyntntyntyntytyntyntyntyntytyntyntyntyntyynnntyntyntynntytyntyntyntytnntynntntyntyntntyyntntnntyyntntytyyntyntyynntynnnnntynnynnttyttyyyyyyyy ofofofofofofoffofofofofoffofofofoofoofofofofofoofofofoffofofofofofofffofofofoffofofoooofooooofofofofoffofffofofooooof LoLoLoLLoLoLoLoLoLoLoLoLLoLoLLooLoLoLoLLoLoLoLLoLLoLLoLoLoLoLoLoLoLooLooLoLLoLoLooLoLooLLLooLooooLoLLLoLoLoLLLLooLooLoooLLLoLLoooLooooLLoLoooLLooLLLooLoLLLLLoLLLs As As Ass s As AAs As As As As As AsAsAsAsAsAsAAs As s As AAAAsAs AAs As As As As A As As As As As AsAAs As As Ass sAs As AAsAsAss AsAs AssAAs AssAsAsAss AssAss AssAAAAAss AAAnnggeengnnnnnnnnnnnnnnnnnnnnnles
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6.4 Extreme Heat
6.4.1 Nature
Extreme heat refers to prolonged periods of
UVTU pN^iNlApqlNm aSpN_ AJJa^iA_VNL Iy
UVTUUq^VLVpyiamV_TmVT_VœJA_pUNA]pUlVm\m
such as heat exhaustion and heat stroke. The
urban heat island (UHI)NSSNJp ilNvA]N_p V_
LN_mN]yIqV]pAlNAm]V\N!am_TN]Nmaq_py
V_pN_mVœNmpUNmNJa_LVpVa_mIyAImalIV_T
and retaining heat. The changing climate
conditions through time in the region
exacerbate for the rising of daily temperature
and for the increasing of extreme heat days
in the County. This leads pa UNA]pU VmmqNm
inJlNAmN N_NlTy LN^A_L A_L mplAV_ a_
infrastructure.
6.4.2 Location
Los Angeles County is particularly susceptible to extreme heat due to its diverse
geography and urban density. ]]aS!am_TN]Nmaq_py^AyNxiNlVN_JNNxplN^NUNAp
nonetheless i_]A_LlNTVa_mV_J]qLV_TpUNvA]]NymA_LUVTULNmNlpAlNAmNxiNlVN_JN
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higher temperatures compared to coastal areas.The urban heat island (UHI) effect can
increase temperatures in cities and developed areas than the less developed areas.
Urban centers with extensive concrete and asphalt surfaces further amplify heat
lNpN_pVa_Ja_plVIqpV_TpaN]NvApNLpN^iNlApqlNm and increased UHI effect in the county.
6.4.3 Extent
The severity of heat events in Los Angeles County has been increasing. Projections
V_LVJApNAmVT_VœJA_plVmNV_pUNSlNkqN_JyA_LV_pN_mVpyaSUNApwAvNmwVpUV_]A_LAlNAm
potentially experiencing temperatures exceeding 110°F. The urban heat island effect
JA_JAqmNqlIA_AlNAmpaINmNvNlA]LNTlNNmwAl^NlpUA_pUNVllqlA]Jaq_pNliAlpm
exacerbating the impact of heat waves. The chart below shows the levels of heat wave
impacts qmNL pa ^NAmqlN UNApwAvN mNvNlVpy NAp0Vm\ A_ NxiNlV^N_pA] ^NAmqlN
developeLIypUN#:1V_Ja]]AIalApVa_wVpUpUNJ]AmmVœNmUNApNvN_pmIypUNVl
impact on human health. It ranges from Green (0) which is little or no risk to Magenta
wUVJU^NA_mNxplN^NUNApwVpU_aavNl_VTUplN]VNS
Category Figure 6.4.1 0Vm\aSNAp-0N]ApNL^iAJpm
lNN_
0 Little to no risk from expected heat.
Yellow
1
Minor - This level of heat affects primarily those individuals extremely
mN_mVpVvNpaUNApNmiNJVA]]ywUN_aqpLaalmwVpUaqpNSSNJpVvNJaa]V_TA_Lal
adequate hydration.
Orange
2
Moderate - This level of heat ASSNJpm ^amp V_LVvVLqA]m mN_mVpVvN pa UNAp
especially those without effective cooling and/or adequate hydration.
Impacts possible in some health systems and in heat-sensitive industries.
0NL
3
Major - This level of heat affects anyone without effective cooling and/or
ALNkqApNUyLlApVa_^iAJpm]V\N]yV_ ma^NUNA]pUmympN^mUNAp-sensitive
industries and infrastructure.
Magenta
4
Extreme - This level of rare and/or long-duration extreme heat with little to no
overnight relief affects anyone without effective cooling and/or adequate
UyLlApVa_^iAJpm]V\N]yV_^ampUNA]pUmympN^mUNAp-sensitive industries and
infrastructure.
EĂƟŽŶĂůtĞĂƚŚĞƌ^ĞƌǀŝĐĞ ;Et^Ϳ, 2024
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qTqmpINV_TpUNUappNmp^a_pUaSpUNyNAlpUAppUNi]A__V_TAlNANxiNlVN_JNmpUN
Figure 6.4.2 IN]awmUawmpUNAvNlATNUVTUpN^iNlApqlNSalqTqmpV_!am
_TN]Nmaq_pymmUaw_pUNpN^iNlApqlNvAlVNmIy]aJApVa_IqplN^AV_mUVTUNl
than average monthly temperature.
Figure 6.4.2͕DĞĂŶDĂdždĞŵƉĞƌĂƚƵƌĞĨŽƌƵŐƵƐƚϮϬϮϰ͕EĂƟŽŶĂůtĞĂƚŚĞƌ^ĞƌǀŝĐĞ
6.4.4 History
NJAqmN aS pUN JUA_TV_T J]V^ApN Ja_LVpVa_m A_L pUN TNaTlAiUVJA]]aJApVa_!am
Angeles County has been experiencing extreme heat waves in the past years. It has a
UVmpalyaSNxplN^NUNApNvN_pmwVpUpN^iNlApqlNmSlNkqN_p]ylNAJUV_TLNTlNNmal
^alNNmiNJVA]]yLqlV_TpUNmq^^Nl^a_pUm_ma^NJAmNmpUNmNNxplN^NUNApNvN_pm
are record-breaking heat waves surpassing their all-time highs.
Extreme Heat events include:
x August 2020:mNvNlNUNApwAvN]NLpawVLNmilNALiawNlaqpATNmASSNJpV_T
_NAl]y lNmVLN_pm
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x September 2020:The San Fernando Valley recorded a record high
temperature of 121°F.
x August 2022:A record-breaking heatwave in late summer exceeded 100°F
x September 2024:A severe September heatwave pushed temperatures 10-
ÑAIavN_al^A]UVppV_TÑV_!a_T
NAJU
The History of Extreme heat events highlight the increasing trend of extreme heat
occurrences in the region. There have been no federal declarations or state
ilaJ]A^ApVa_m Sal NxplN^N UNAp V_ pUN ]Amp œvN yNAlmEven though there were no
LNJ]AlNLNxplN^NUNApN^NlTN_JVNmpUNJaq_pyUAmVmmqNLmNvNlA]UNApA]NlpmA_L
taken measures to protect residents from the impacts of heat waves during these
periods.
6.4.5 Probability
xplN^NUNApNvN_pmAlNA_A__qA]aJJqllN_JNV_!am_TN]Nmaq_pypUaqTUmNvNlVpy
aSmqJUNvN_pmvAlyiNlyNAlIAmNLa_apUNlJa_LVpVa_mmqJUAm]#V ño. Climate models
project a substantial increase in the likelihood of extreme heat events in Los Angeles
County. By mid-JN_pqlypUNJaq_pyJaq]LNxiNlVN_JN^alNpUA_œvN^A[alUNApwAvNm
A__qA]]y wVpU ma^N ^aLN]m mqTTNmpV_T qi pa pN_Sa]L V_JlNAmNm V_ SlNkqN_Jy3UVm
heightened probability necessitates proactive mitigation and adaptation strategies.
Figure 6.4.3,ǀĞƌĂŐĞdĞŵƉĞƌĂƚƵƌĞϭϵϬϬ-2025, NOAA, NCEI, 2025.
6.4.6 Vulnerability
xplN^NUNApiamNmAmVT_VœJA_pA_LTlawV_TpUlNAppa!am_TN]Nmaq_pywUNlN
lVmV_TpN^iNlApqlNmqlIA_UNApVm]A_LmA_LwVLNmilNALmaJVA]vq]_NlAIV]VpyV_pNlmNJp
3UamN^ampAplVm\V_J]qLNpUNN]LNl]y]aw-V_Ja^NUaqmNUa]Lm]AJ\V_TAVlJa_LVpVa_V_T
County of Los Angeles
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iNai]NNxiNlVN_JV_TUa^N]Nmm_Nmm- V_LVvVLqA]mwVpUAJJNmmA_LSq_JpVa_A]_NNLm
# A_LpUNaq_py¯m]AlTNiaiq]ApVa_aSaqpLaalA_L_a_-air-conditioned indoor
workers. Infrastructure is also strainedN]NJplVJVpyLN^A_LmiV\NmLqlV_TUNApwAvNm
often overwhelming the power grid and triggering outages. Water systems experience
V_JlNAmNLLN^A_LA_LNvAialApVa_]ammNmwUV]NlaALwAymA_LlAV]]V_NmAlNmqI[NJppa
buckling or operational delays. In recent yNAlm!am_TN]Nmaq_pyUAmNxiNlVN_JNL
severNJa_mNkqN_JNmSla^ila]a_TNLUNApNvN_pmlNV_SalJV_TpUNqlTN_p_NNLSalUNAp
resilience strategies targeting both people and critical services.
Los Angeles County–1iNJVœJ^iAJpmA_LApA
x lNmVLN_pm NxiNlVN_JNL iawNl aqpATNm LqlV_T pUN qTqmp
heatwave.
x ÈaSpUNaq_py¯m^V]NmaSUVTU-voltage transmission lines are exposed
to moderate to high extreme heat risk.
x ^V]]Va_ lNmVLN_pm AlN Ja_mVLNlNL UVTU]y vq]_NlAI]N LqN pa ATN V_Ja^N
LVmAIV]VpyalJUla_VJUNA]pUJa_LVpVa_m
x %vNlaqpLaalwal\NlmAlNApN]NvApNLlVm\SalUNAp-related illness and
injury.
x Thousands of heat-related emergency visits occurred during multi-day heat
events in 2020 and 2022especially in neighborhoods with limited shade and
high surface temperatures.
x 50+ cooling centers have been activated across the County during recent
heatwaves to support at-risk populations.
x VTU UNAp Ja_plVIqpNm pa walmN_NL AVl kqA]Vpy V_JlNAmNL wV]LœlN m^a\N
NxiamqlN A_L NJa_a^VJ ]ammNm LqN pa V_SlAmplqJpqlN LA^ATN ilaLqJpVvVpy
LNJ]V_NA_LlVmV_TUNA]pUJAlNJampm
6.4.7 Impacts
!am_TN]Nmaq_pyUAmSAJNLmVT_VœJA_pA_LTlawV_TV^iAJpmSla^ NxplN^N
UNApwAvNmavNlpUNiAmppwaLNJALNm_qTqmpAila]a_TNLUNApwAvNJAqmNL
la]]V_T I]AJ\aqpm ASSNJpV_T _NAl]y Jqmpa^Nlm avNlwUN]^NLpUNmpApN¯m
N]NJplVJA]TlVLA_LSarced the activation of emergency conservation protocols. That
mA^Nmq^^NlpUN1A_Nl_A_La9A]]NyUVpÑ]NALV_TpawVLNmilNALmplAV_a_
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HVAC systems and increased emergency room visits for heat-related illnesses. The
2022 and 2024 heatwaves brought similar conditions—temperatures over 100°F across
pUNlNTVa_]NLpa]aJA]V|NLplA_mSal^NlSAV]qlNmAmiUA]pIqJ\]V_TA_LmplAV_a_wApNl
delivNlymympN^mLqNpaN]NvApNLLN^A_LqlV_TpUNmNNvN_pmaqpLaalwal\NlmpUN
N]LNl]yA_L]aw-income residents without access to cooling systems were among the
^ampASSNJpNLJa_a^VJAJpVvVpywAmLVmlqipNLwVpUlNialpmaS IqmV_Nmm J]amqlNm
service delaymA_LV_JlNAmNLUNA]pUJAlNJampm_!a_T
NAJUlNAJUNLAlNJalL
ÑJAqmV_TAmiV\NV_N]NJplVJVpyLN^A_LA_LplVTTNlV_TN^NlTN_JyN_NlTyA]Nlpm
across Southern California. Heat-related deaths and hospitalizations have also trended
qiwAlL iAlpicularly in neighborhoods with low tree canopy and high impervious
surfaces. These impacts underscore the need for resilient infrastructure and targeted
adaptation strategies to safeguard health and essential services.
6.4.8 Mitigation and Preparedness
The most effective way to reduce the negative impacts of an extreme heat event is to
develop a comprehensive heat response plan that has individual strategies to
effectively manage heat waves during peak seasons of the year. The plan might include
SalNJAmpV_TA_L^a_VpalV_TNLqJApVa_A_LAwAlN_NmmA_LUNApwAvNlNmia_mN.
To address extreme heat!am_TN]Nmaq_pyUAmV^i]N^N_pNLmNvNlA]^NAmqlNm
x Cooling Centers: Establishment of air-conditioned public spaces where
residents can seek relief during heatwaves. These centers are facilities such as
]VIlAlVNm Ja^^q_Vpy JN_pNlm A_L mN_Val JN_pNlm 0NmVLN_pm JA_]aJApNpUN
nearest cooling center using resources provided by the county. Additional
resources can be found at ŚƚƚƉƐ͗ͬͬƌĞĂĚLJ͘ůĂĐŽƵŶƚLJ͘ŐŽǀͬŚĞĂƚͬ
x 4lIA_ lNN_V_T _VpVApVvNm -laTlA^mAV^NLApV_JlNAmV_TTlNN_miAJNm
i]A_pV_T plNNm A_L JlNApV_T iAl\m pa ilavVLN mUALN A_L lNLqJNA^IVN_p
temperatures. These efforts help mitigate the urban heat island effect.
x Public Awareness Campaigns: Educational initiatives to inform residents about
UNAplVm\milNvN_pVa_mplApNTVNmA_LlNmaqlJNmAvAV]AI]NLqlV_TNxplN^NUNAp
NvN_pm3UNmNJA^iAVT_mN^iUAmV|NpUNV^ialpA_JNaSUyLlApVa_lNJaT_V|V_T
heat-lN]ApNLV]]_Nmmmy^ipa^mA_LqpV]V|V_TJaa]V_g centers.
x
qV]LV_TaLNmA_L0NTq]ApVa_m Incorporation of heat-mitigating designs and
^ApNlVA]mV__NwJa_mplqJpVa_mA_LlNplaœpmmqJUAmJaa]laaSmA_LlNŔNJpVvN
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iAvN^N_pmpalNLqJNUNApAImalipVa_3UNmN^NAmqlNmAV^pa]awNlV_Laal
temperatures and decrease reliance on air conditioning.
3UNmN mplApNTVNm AlN LNmVT_NL pa lNLqJN UNAp NxiamqlN ilapNJpvq]_NlAI]N
iaiq]ApVa_mA_LN_UA_JNJa^^q_VpylNmV]VN_JNATAV_mpNxplN^NUNApNvN_pm
6.4.9 Summary
Extreme heat iamNmATlawV_TpUlNAppa!am_TN]Nmaq_pywVpUV_JlNAmV_TSlNkqN_Jy
and intensity of heat waves exacerbated by urban heat island (UHI) effects.
Understanding these impacts of extreme heat A_LpA\V_TAiilailVApNilNJAqpVa_m
residents of Los Angeles County can protect themselves and their communities from
this growing climate hazard. 3UN Jaq_py UAm q_LNlpA\N_ vAlVaqm ^VpVTApVa_ NSSalpm
V_J]qLV_T pUN NmpAI]VmU^N_p aS Jaa]V_T JN_pNlm qlIA_ TlNN_V_Tila[NJpm iqI]VJ
NLqJApVa_JA^iAVT_mA_Lthe implementation of heat-conscious building practices.
%_TaV_TALAipApVa_A_LilaAJpVvNi]A__V_TAlNNmmN_pVA]pamASNTqAlLiqI]VJUNA]pU
V_SlAmplqJpqlNA_LpUNN_vVla_^N_pSla^pUNALvNlmNNSSNJpmaSNxplN^NUNAp
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6.5 Drought
6.5.1 Nature
Drought is a prolonged period of below-
average precipitation that leads to water
mUalpATNm V^iAJpV_T ATlVJq]pqlN NJamympN^m
and urban water supplies. Unlike other natural
LVmAmpNlmLlaqTUpLNvN]aimTlALqA]]y^A\V_T
Vp LVSœJq]p pa ilNLVJp A_L ^VpVTApN _ !am
_TN]Nmaq_pyLlaqTUpmAlNAlNJqllV_TVmmqN
due to the region’s arid climate and
dependence on imported water supplies.
laqTUpmNvNlVpyVmLNpNl^V_NLIyVpmLqlApVa_
V_pN_mVpy TNaTlAiUVJ NxpN_p A_L wApNl
demand. Climate change is exacerbating these
SAJpalm]NALV_TpaUappNlpN^iNlApqlNm
lNLqJNL ilNJViVpApVa_ A_L V_JlNAmNL
evaporation rates.:V]LœlNmAlNalso projected
to increase in frequency and intensity during
drought season.
3UNlNAlNSaqlJa^^a_J]AmmVœJApVa_maSLlaqTUp
x Meteorological Drought: A prolonged period of below-normal precipitation.
CCouCouuCouuntyntyntntyntynty offofofofofo LLoLLoLo AsAs As Asngenggeengelesesleslelles
AAlAllAllAAAll-HazHHazHazardardardardddardardsMMs Ms Mss Miitiitiitiitigatgatggatiionoion PlPlPlPlPlaPlaPlalaannnnn
County of Los Angeles
All-Hazards Mitigation Plan
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x Hydrological Drought: A reduction in surface and groundwater levels due to
ila]a_TNLilNJViVpApVa_LNœJVpm
x Agricultural Drought: A lack of soil moisture that affects crop growth and
livestock sustainability.
x Socioeconomic Drought:When water shortages impact drinking water
mqii]VNmmA_VpApVa_iqI]VJmNlvVJNmA_LNJa_a^VJAJpVvVpVNm
6.5.2 Location
Drought is regional in nature and typically affects the entire Los Angeles County
planning area. Given the county’s reliance on imported water from the Sierra Nevada
m_awiAJ\A_LpUNa]alALa0VvNllNLqJNLAvAV]AIV]VpyaSpUNmNmaqlJNmmVT_VœJA_p]y
increases vulnerability.
6.5.3 Extent
laqTUpVmAlNJqllV_T_ApqlA]UA|AlLpUApJA_mNvNlN]yV^iAJpATlVJq]pqlNwApNlmqii]y
NJamympN^m A_L Ja^^q_VpVNm 3a ^a_Vpal A_L Ja^^q_VJApN LlaqTUpJa_LVpVa_m
AJlammpUN4_VpNL1pApNmpUN#ApVa_A]laqTUp"VpVTApVa_N_pNl #" V_
partnership with the U.S. Department of Agriculture (USDA) and the National Oceanic
A_L p^amiUNlVJ L^V_VmplApVa_ #% ilaLqJNm wNN\]y 41 laqTUp "a_Vpal
^Aim3UNmN^AimJApNTalV|NLlaqTUpJa_LVpVa_mV_paœvN]NvN]mIAmNLa_V_pN_mVpy
LqlApVa_A_LV^iAJpa_vAlVaqmmNJpalmV_J]qLV_TATlVJq]pqlNwApNllNmaqlJNmA_L
public health.
AJU LlaqTUp JApNTaly lNŔNJpm A LVSSNlN_p ]NvN] aS mNvNlVpy Sla^ mUalp-term dry
Ja_LVpVa_mpUAp^Aym]awJlaiTlawpUpa]a_T-pNl^wVLNmilNALwApNlmUalpATNmpUAp
lNkqVlNN^NlTN_JylNmia_mN3UNmNJ]AmmVœJApVa_mUN]iLNJVmVa_-^A\NlmSAl^NlmA_L
water managers respond appropriately to emerging or ongoing drought conditions.
See Figure 6.5.1 below for more information.
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Drought Categories and Associated Impacts:
CATEGORY DESCRIPTION POSSIBLE IMPACTS
D4 EXCEPTIONAL
DROUGHT
x džĐĞƉƟŽŶĂůĂŶĚǁŝĚĞƐƉƌĞĂĚĐƌŽƉͬƉĂƐƚƵƌĞůŽƐƐĞƐ
x ƌŝƟĐĂůƐŚŽƌƚĂŐĞƐŽĨǁĂƚĞƌŝŶƌĞƐĞƌǀŽŝƌƐ͕ƐƚƌĞĂŵƐ͕ĂŶĚ
ǁĞůůƐ
x tĂƚĞƌĞŵĞƌŐĞŶĐŝĞƐĂŶĚƉŽƐƐŝďůĞŵĂŶĚĂƚŽƌLJƌĂƟŽŶŝŶŐ
x ^ĞǀĞƌĞŝŵƉĂĐƚƐŽŶĞĐŽƐLJƐƚĞŵƐĂŶĚǁŝůĚůŝĨĞŚĂďŝƚĂƚƐ
D3 EXTREME
DROUGHT
x DĂũŽƌĂŐƌŝĐƵůƚƵƌĂůůŽƐƐĞƐĂŶĚƉĂƐƚƵƌĞĨĂŝůƵƌĞ
x tŝĚĞƐƉƌĞĂĚǁĂƚĞƌƐŚŽƌƚĂŐĞƐ
x tĂƚĞƌƵƐĞƌĞƐƚƌŝĐƟŽŶƐůŝŬĞůLJĞŶĨŽƌĐĞĚ
x /ŶĐƌĞĂƐĞĚƌŝƐŬŽĨǁŝůĚĮƌĞƐĂŶĚŚĞĂƚ-ƌĞůĂƚĞĚƐƚƌĞƐƐ
D2 SEVERE
DROUGHT
x ƌŽƉĂŶĚƉĂƐƚƵƌĞůŽƐƐĞƐďĞĐŽŵŝŶŐůŝŬĞůLJ
x tĂƚĞƌƐŚŽƌƚĂŐĞƐďĞĐŽŵŝŶŐĐŽŵŵŽŶ
x >ŽĐĂůŐŽǀĞƌŶŵĞŶƚƐŵĂLJŝŵƉůĞŵĞŶƚǁĂƚĞƌƌĞƐƚƌŝĐƟŽŶƐ
x ,LJĚƌŽƉŽǁĞƌŐĞŶĞƌĂƟŽŶĂŶĚŝƌƌŝŐĂƟŽŶƉŽƚĞŶƟĂůůLJ
ŝŵƉĂĐƚĞĚ
D1 MODERATE
DROUGHT
x EŽƟĐĞĂďůĞĚĂŵĂŐĞƚŽĐƌŽƉƐĂŶĚƉĂƐƚƵƌĞƐ
x tĂƚĞƌůĞǀĞůƐŝŶƐƚƌĞĂŵƐĂŶĚƌĞƐĞƌǀŽŝƌƐďĞŐŝŶƚŽĚĞĐůŝŶĞ
x sŽůƵŶƚĂƌLJǁĂƚĞƌ-ƵƐĞƌĞƐƚƌŝĐƟŽŶƐŵĂLJďĞƌĞƋƵĞƐƚĞĚ
x ^ŽŵĞƐƚƌĞƐƐŽŶĮƐŚĂŶĚǁŝůĚůŝĨĞƉŽƉƵůĂƟŽŶƐ
D0 ABNORMALLY
DRY
x ĂƌůLJƐŝŐŶƐŽĨĚƌŽƵŐŚƚ͕ǁŝƚŚƐŚŽƌƚ-ƚĞƌŵĚƌLJŶĞƐƐƐůŽǁŝŶŐ
ƉůĂŶƟŶŐĂŶĚĐƌŽƉŐƌŽǁƚŚ
x /ĨŝŵƉƌŽǀŝŶŐůŝŶŐĞƌŝŶŐǁĂƚĞƌĚĞĮĐŝƚƐĂƐĂƌĞĂƌĞĐŽǀĞƌƐ
ĨƌŽŵĚƌŽƵŐŚƚ
x WĂƐƚƵƌĞƐŽƌǀĞŐĞƚĂƟŽŶŵĂLJƐŚŽǁƐŝŐŶƐŽĨĚĞůĂLJĞĚ
ƌĞĐŽǀĞƌLJ
Figure 6.5.1 Drought Categories and Associated Impacts
3UNmN J]AmmVœJApVa_m _ap a_]y help guide resources and planning but also raise
awareness about the broader consequences of prolonged dryness. Understanding the
extent and severity of drought helps ensure timely response and mitigation efforts at
]aJA]mpApNA_LSNLNlA]]NvN]m
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6.5.4 History
!am_TN]Nmaq_pyUAmNxiNlVN_JNL^q]pVi]NmVT_VœJA_pLlaqTUpmwVpUma^N]AmpV_T
several years. There have been no federal declarations or state proclamations for
LlaqTUpV_pUN]AmpœvNyNAlm
Figure 6.5.2, U.S. Drought Monitor, 2025
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Notable historical drought periods include:
1. 1917-1921 – A widespread drought affecting most of California.
2. 1976-1977 – One of the driest two-year periods in recorded history.
3. 1987-1992 – A six-year drought that severely impacted water supplies and
agriculture.
4. 2007-2009 – A prolonged drought leading to state-imposed water restrictions.
5. 2011-2017 –3UN ^amp mNvNlN LlaqTUp V_ ^aLNl_ UVmpaly lNmq]pV_T V_
groundwater depletion and mandatory conservation measures.
6. 2020-2022 –A]VSal_VA NxiNlVN_JNL A mVT_VœJA_p LlaqTUp wVpU !am _TN]Nm
aq_pyNxiNlVN_JV_T´AI_al^A]]yLly´Ja_LVpVa_m
7. 2024-2025 – Los Angeles County is continuing to experience abnormally dry
Ja_LVpVa_mwVpU]awNlAverage rainfalls and arid conditions.
3UNJUAlpAIavNpUNPalmer Drought Severity Indexshows how drought conditions
have been changing since 1895. The Palmer Drought Severity Index measures how dry
or wet an area is by comparing rainfall and temperature to long-term averages. It gives
a number (positive or negative) showing drought severity or excess moisture.
Los Angeles County was in some form of drought for 376 consecutive weeks from
NJN^INlq_pV]"AlJUThe State and the County passed several
resolutions and regulations at different times to mitigate drought impacts like water
Figure 6͘ϱ͘ϯ͕EKƌŽƵŐŚƚ^ĞǀĞƌŝƚLJ/ŶĚĞdž͕ϮϬϮϰ
County of Los Angeles
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conservation regulations. There were no federally declared drought disasters in the
AlNAV_pUNiAmpœvNyNAlmV_pUNi]A__V_TAlNA
6.5.5 Probability
Climate scientists predict that Los Angeles County and the rest of Southern California
wV]]TNpLlVNlwUV]NNorthern California will get hotter. Rising temperatures contribute
paUVTUNlNvAialApVa_lApNmA_LLNJ]V_V_Tm_awiAJ\V_pUN1VNllA#NvALAAJlVpVJA]
source of water for Southern California. The frequency of extreme droughts is expected
paV_JlNAmNlNLqJing available water resources and heightening competition between
qlIA_ATlVJq]pqlA]A_LN_vVla_^N_pA]_NNLmLong-term droughts have a 100% of
occurring every ten-years wVpU iapN_pVA] Sal ]a_TNl A_L ^alN LNmplqJpVvN LlaqTUp
events due to climate change.
6.5.6 Vulnerability
Los Angeles County’s 10 million residents face growing vulnerabilities during
ila]a_TNLLlaqTUpmwVpUavNl ÈaSJa^^q_VpywApNlmympN^mNxUVIVpV_TAp]NAmpa_N
drought-lN]ApNLlVm\mqJUAmlN]VA_JNa_AmV_T]NmaqlJNalATV_TV_SlAmplqJpqlN3UN
County’s dependence on imported water—serving over 60% of residents—increases
exposure to supply disruptions from reduced Sierra Nevada snowpack and Colorado
River allocations. ]]lNmVLN_pmA_LvVmVpalmaS Los Angeles County areaffected by water
shortages during a prolonged drought conditions.
Vulnerabilities include:
x Low-income householdsaSpN_]AJ\V_TwApNl-NSœJVN_pAii]VA_JNmA_LJaa]V_T
systems.
x Agricultural industry wVpU avNl AJlNm aS VllVTApNL SAl^]A_L V_ pUN
County is at risk of reduced water allocation and drying pastures for livestock.
x Wildland-urban interface (WUI) communitieswUNlNavNl^V]]Va_lNmVLN_pm
SAJNUNVTUpN_NLwV]LœlNlVm\LqNpaLlyvNTNpApVa_A_L]V^VpNLœlNœTUpV_TwApNl
supply.
x Critical infrastructure operations may be impacted by a range of factors from
reduced hydropower availability when reservoir levels decrease to power
station cooling challenges.
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These vulnerabilities illustrate the far-lNAJUV_TJlamm-sector impacts of drought on the
aq_py¯mNJa_a^yN_vVla_^N_pA_L^ampAp-risk communities.
6.5.7 Impacts
%vNlpUNiAmpœvNyNAlm!am_TN]Nmaq_pyUAmNxiNlVN_JNLV_pN_mVSyV_TLlaqTUp
Ja_LVpVa_m^Al\NLIylVmV_TpN^iNlApqlNmlNLqJNLm_awiAJ\A_Lpersistent water
mUalpATNm
y ÈaSpUNaq_py¯mJa^^q_VpywApNlmympN^mmUawNLAp]NAmpa_N
LlaqTUp vq]_NlAIV]Vpy V_J]qLV_T lN]VA_JN a_ A mV_T]N wApNl maqlJN al ATV_T
V_SlAmplqJpqlN-qI]VJUNA]pUV^iAJpmUAvNA]maN^NlTNLwVpUJAmNmaS9A lley fever
lNialpNLV_]V_\NLpaLlymaV]A_LLqmpNxiamqlNyLlaiawNllNLqJpVa_mLqlV_T
LlaqTUpiNlVaLmV_JlNAmNLlN]VA_JNa__ApqlA]TAmJa_plVIqpV_TpaN]NvApNLN_NlTy
JampmSallNmVLN_pm3UNmNJa^iaq_LV_TV^iAJpmUAvNmplAV_NLwApNlmqii]yUNalth
mympN^mA_LV_SlAmplqJpqlNlNV_SalJV_TLlaqTUpAmA^A[alA_LTlawV_TUA|AlLSal!am
Angeles County.
6.5.8 Mitigation and Preparedness
3aJa^IApV_JlNAmV_TLlaqTUplVm\m!am_TN]Nmaq_pyUAmV^i]N^N_pNL wApNl
Ja_mNlvApVa_ia]VJVNmV_SlAmplqJpqlNV_vNmp^N_pmA_LN^NlTN_JylNmia_mN^NAmqlNm
Key strategies include:
Water Management and Conservation
x Expanding water recycling and desalination programs to reduce reliance on
imported water.
x Implementing drought-tolerant landscaping initiatives to lower residential and
commercial water use.
x _SalJV_TwApNlNSœJVN_JylNTq]ApVa_mSal_NwLNvN]ai^N_pmA_Lupgrading older
properties with water-saving strategies.
Infrastructure Improvements
x Enhancing groundwater recharge projects to increase local water storage.
x Upgrading stormwater capture systems to maximize water retention during rainy
seasons.
x Developing new water storage facilities to provide additional supply resilience.
Community Preparedness and Public Awareness
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x Launching county-wide conservation campaigns to encourage sustainable water
use.
x _JlNAmV_Tœ_A_JVA]V_JN_pVvNmSalwApNl-NSœJVN_pAii]VA_JNmA_LVllVTApVa_mympN^m
x Strengthening emergency drought response plans to ensure equitable water
distribution during crises.
6.5.9 Summary
Drought remains a persistent and growing threat to Los Angeles County’s water
security and economic stability. Climate change projections indicate more frequent
A_LmNvNlNLlaqTUpmi]AJV_TTlNApNlmplAV_a_wApNlmqii]ymympN^miqI]VJUNA]pUA_L
agriculture. By implementing proactive water management mplApNTVNm V_vNmpV_T V_
V_SlAmplqJpqlN lNmV]VN_JN A_L ila^apV_T Ja^^q_Vpy AwAlN_Nmm pUN aq_py JA_
mitigate the long-term impacts of drought and ensure sustainable water resources for
future generations.
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Couountyty ofo Lo AAAAAAAAAAAAAAAs AsAAAAAAAAAAAAAAAAAAngengnngngnnnnngengegegegegegeengengngengnngngegggegggggggeegeggggegeeggeeeeeeeeeeeeeelesleslesllleslessesesleslesleleleslesleseseslesleseeseseselesleseseleseslleleeeeessleseeseleslessssssssessssssss
AllllAlllAlAlA-Hazazzardardardardddrdrddddrdddrdddrddrddddddddrdddddddddrddrddddds MMMMMMMMMMitiitiitiitiitittitititititttitgatgatgationnionionnn PlaPPllllaPlaPPllaaPlaPPPlaPnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
6.6 Flooding
6.6.1 Nature
Flooding is a persistent and increasingly severe
UA|AlL V_ !am _TN]Nm aq_py LlVvN_ Iy UNAvy
lAV_SA]]mpal^mqlTNmpal^wApNlLlAV_ATNA_LlVmV_T
mNA ]NvN]m 3UN Jaq_py¯m Ja^i]Nx UyLla]aTy wUVJU
V_J]qLNmlVvNlmJlNN\mA_LA_NxpN_mVvNqlIA_ŔaaL
co_pla] mympN^ Vm UVTU]y mqmJNipVI]N pa avNlŔaw
events when precipitation exceeds drainage capacity.
3UNNSSNJpmaSJ]V^ApNJUA_TNAlNNxAJNlIApV_TŔaaL
lVm\m Iy V_pN_mVSyV_T mpal^m A]pNlV_T ilNJViVpApVa_
iAppNl_mA_LV_JlNAmV_TmNA]NvN]m]NALV_TpaTreater
JaAmpA]V_q_LApVa_A_LV_]A_LŔAmUŔaaLm
Unlike other regions that experience seasonal
ŔaaLV_TLqNpam_aw^N]pŔaaLV_TV_!am_TN]Nm
County primarily occurs during winter storms and
Ap^amiUNlVJlVvNlNvN_pmwUVJUIlV_TV_pN_mNlAV_SA]]
and lightning over short periods.
x 3UNlNTVa_¯mUVTULNTlNNaSqlIA_V|ApVa_Ja_plVIqpNmpaŔAmUŔaaLV_TAmiAvNL
mqlSAJNmilNvN_p_ApqlA]AImalipVa_aSwApNl]NALV_TpalAiVLlq_aSSA_LmplNNp
ŔaaLV_T
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x
ql_mJAlmSla^lNJN_pwV]LœlNmSqlpUNlJa^iaq_LŔaaLlVm\mIylNLqJV_T
vNTNpApVa_ JavNl LNmpAIV]V|V_T UV]]mVLNm A_L V_JlNAmV_T pUN ]V\N]VUaaL aS ]A_L
movement.
]aaLV_TA]maJlNApNmmNJa_LAlyUA|AlLmV_J]qLV_TNlamVa_V_SlAmplqJpqlNLA^ATN
wApNlJa_pA^V_ApVa_A_LplA_mialpApVa_LVmlqipVa_m1pal^wApNllq_aSSJA_avNlwUN]^
wAmpNwApNlplNAp^N_pSAJV]VpVNm]NALV_TpaUA|AlLaqmmiV]]m!A_Lm]VLNmA_L^qLŔawm
in post-wV]LœlNAlNAmiamNALLVpVa_A]lVm\mpaUa^NmlaALmA_LJlVpVJA]V_SlAmplqJpqlN
3UNmN Ja^iaq_LV_T pUlNApm UVTU]VTUp pUN qlTN_p _NNL Sal Ja^ilNUN_mVvN ŔaaL
^VpVTApVa_NSSalpmpailapNJpJa^^q_VpVNmV_SlAmplqJpqlNA_LpUNN_vVla_^N_p
6.6.2 Location
]aaLUA|AlLmAlNTNaTlAiUVJA]]ywVLNmilNALwVpU^alNpUA_mkqAlN^V]NmaS]A_L
located within the 100- and 500-yNAlŔaaLi]AV_mVmpalVJA]]ymVT_VœJA_pNvN_pmmqJUAm
pUNA_LŔaaLmAmwN]]Am^alNlNJN_pmpal^mV_A_LUAvNJAqmNL
mqImpA_pVA]LA^ATNpaV_SlAmplqJpqlNplVTTNlNLNvAJqApVa_mA_LJUA]]N_TNL]a_T-term
recovery efforts. SocVA]]yvq]_NlAI]Niaiq]ApVa_mV_J]qLV_Ta]LNlALq]pmV_LVvVLqA]m
wVpUAJJNmmA_LSq_JpVa_A]_NNLmA_L]aw-V_Ja^NUaqmNUa]LmSAJNLVmilaialpVa_ApN
V^iAJpm LqN pa ]V^VpNL œ_A_JVA] lNmaqlJNm V_ALNkqApN V_mqlA_JN JavNlATN A_L
reduced access to services. 3UNaq_py¯mŔaaLJa_pla]mympN^V_J]qLNmJa_JlNpNlVvNl
JUA__N]m]NvNNmmpal^LlAV_mLNIlVmIAmV_mA_LlNmNlvaVlmUAmUN]iNL^VpVTApNma^N
ŔaaL lVm\m Iqp lN^AV_m vq]_NlAI]N pa UVTU-intensity storms that exceed design
capacities.
Major Flood-Prone Areas:
x !am_TN]Nm0VvNl1A_AIlVN]0VvNlA_L1A_pA]AlA0VvNl3UNmN^A[alwApNlwAym
AlNila_NpaavNlŔawLqlV_TNxplN^Nmpal^NvN_pmiAlpVJq]Al]yLqlV_T]#V`a
years.
x Ballona Creek and Malibu Creek: These urban watersheds experience rapid runoff
A_LŔAmUŔaaLV_TNmiNJVA]]yV_LNvN]aiNLAlNAm
x aapUV]]m9A]]NymA_L0NJN_p
ql_1JAllNAm-amp-wV]LœlNlNTVa_mSAJNUNVTUpN_NL
lVm\aSŔAmUŔaaLmA_LLNIlVmŔawmSa]]awV_Tmpal^m
x _pN]aiN9A]]Ny_LNmNlplNTVa_mmpal^wApNliaa]mV_papN^ialAly]A\NmJAqmV_T
ŔaaLNLlaALwAymA_LV_SlAmplqJpqlNLA^ATN
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x Coastal Communities: Rising sea levels and storm surges threaten beachfront
ilaiNlpVNmUAlIalmA_LIqmV_NmmNm
Urban areas are particularly vulnerable due to impervious surfaces and outdated
LlAV_ATNmympN^mqlV_TV_pN_mNmpal^m_NVTUIalUaaLmV_aw_paw_!am_TN]Nm
1aqpU!A_LpUN1A_Nl_A_La9A]]NySlNkqN_p]yNxiNlVN_JNmplNNpŔaaLV_TA_LplASœJ
disruptia_mLN^a_mplApV_TpUN]V^VpApVa_maSNxVmpV_TV_SlAmplqJpqlNV_UA_L]V_T^aLNl_
storm events.
For a better visual representation of this Flooding Hazard within the LA County
i]A__V_TAlNAi]NAmNlNSNlN_JNiiN_LVx for ŔaaLA_LV_q_LApVa_^Aim.
6.6.3 Extent
!am_TN]Nmaq_pySAJNmAmVT_VœJA_pA_LNva]vV_TŔaaLlVm\wVpUV^iAJpmlA_TV_T
Sla^]aJA]V|NLqlIA_V_q_LApVa_pawVLNmilNALlVvNlV_NŔaaLV_TA_LLNmplqJpVvNLNIlVm
Ŕawm]pUaqTUpUNaq_pyUAmV_vNmpNLUNAvV]yV_ŔaaLJa_pla]V_SlAmplqJpqlN
inc]qLV_T A_ NxpN_mVvN _Npwal\ aS LA^m A_L LNIlVm IAmV_m pUNmN mympN^m AlN
increasingly strained and cannot fully eliminate the threat. A growing number of
lNmVLN_pmAlNNxiamNLpaLA_TNlaqmŔaaLV_TNAJUyNAlAmVpqApVa_^ALNwalmNIypUN
limitations of aging infrastructure and the complexities of urban hydrology. Intense
lAV_SA]]NvN_pmNmiNJVA]]ypUamNAmmaJVApNLwVpUAp^amiUNlVJlVvNlmAlNaJJqllV_T^alN
SlNkqN_p]y A_L wVpU TlNApNl mNvNlVpy aSpN_ avNlwUN]^V_T LlAV_ATN mympN^m A_L
lNmq]pV_TV_mNvNlNŔooding of streets and neighborhoods. Compounding this risk are
Iql_mJAlmSla^lNJN_pwV]LœlNmwUVJUUNVTUpN_pUN]V\N]VUaaLaS^qLm]VLNmA_LLNIlVm
ŔawmpUAppUlNApN_IapU]VSNA_LilaiNlpymJ]V^ApNiAppNl_mmUVSpA_LNxplN^NwNApUNl
events become ^alNJa^^a_pUNŔaaLvq]_NlAIV]VpyaS!am_TN]Nmaq_pyJa_pV_qNm
to deepen across its diverse geography.
Flood severity is typically measured using the 100-year and 500-yNAlŔaaLlNJqllN_JN
V_pNlvA]mwUVJUV_LVJApNAÈA_LÈA__qA]ilaIAIV]VpyaSŔaaLV_TlNmiNJpVvN]y
3UNmNLNmVT_ApVa_mTqVLNŔaaLi]AV_^A_ATN^N_pA_L^VpVTApVa_NSSalpm
Key Flood Hazard Statistics in Los Angeles County:
x mkqAlN^V]Nm È aS]A_LUAvNAÈA__qA]ŔaaLilaIAIV]Vpy
x mkqAlN^V]NmÈ UAvNAÈA__qA]ŔaaLilaIAIV]Vpy
County of Los Angeles
All-Hazards Mitigation Plan
Page 85 of 204
Key Flood Hazard Statistics for Unincorporated Los Angeles County:
x mkqAlN^V]NmÈ UAvNAÈŔaaLilaIAIV]Vpy
x mkqAlN^V]NmÈ UAvNAÈŔaaLilaIAIV]Vpy
As climate change accelerates sea-]NvN]lVmNA_LNxplN^NlAV_SA]]NvN_pmpUNmNŔaaL-
ila_NAlNAm^AyNxiA_LASSNJpV_T^alNlNmVLN_pmV_SlAmplqJpqlNA_LIqmV_NmmNm
!%%"-3%#!#0
Area 0.2% Annual Flood
Probability 1% Annual Flood Probability
Los Angeles County 243.32 sq. mi. (5.11%) 4.19 sq. mi. (0.09%)
Unincorporated LA County 64.77 sq. mi. (2.13%) 1.23 sq. mi. (0.04%)
6.6.4 History
!am_TN]Nmaq_pyUAmNxiNlVN_JNL_q^NlaqmmNvNlNŔaaLNvN_pm^A_yaSwUVJU
UAvNJAqmNLJApAmplaiUVJLA^ATNpaV_SlAmplqJpqlNilaiNlpyA_LUq^A_]VSN%vNlpUN
LNJALNmJ]V^ApNvAlVAIV]VpylAiVLqlIA_V|ApVa_A_LA_ATV_TŔaaLJa_pla]mympN^UAvN
leLpalNiNApNLŔaaLV_TLVmAmpNlmThere have been no federal declarations or state
ilaJ]A^ApVa_mSalNAlpUkqA\NmV_pUN]AmpœvNyNAlm
N]awAlNma^NaSpUN^ampmVT_VœJA_pUVmpalVJA]A_LlNJN_pŔaaLNvN_pmASSNJpV_TpUN
region.
Notable Flood and Lightning Events in Los Angeles County:
x 1938 Los Angeles Floods%_NaSpUNLNAL]VNmpŔaaLmV_Jaq_pyUVmpalyJAqmNLIy
wNN\m aS pallN_pVA] lAV_SA]] lNmq]pV_T V_ avNl LNApUm pUN LNmplqJpVa_ aS
pUaqmA_LmaSUa^NmA_LwVLNmilNALV_SlAmplqJpqlNLA^ATNiAlpVJq]Al]ypaIlVLTNm
and roadways.
x 1969 Winter StormsNAvylAV_m]NLpa^AmmVvNLNIlVmŔawmV_pUN1A_AIlVN]
"aq_pAV_mmNvNlNqlIA_ŔaaLV_TAJlamm!am_TN]NmA_L^q]pVi]NLA^IlNAJUNm
prompting major evacuations.
x 1992-1993 El Niño FloodsmNlVNmaSmpal^mplVTTNlNL]A_Lm]VLNmŔAmUŔaaLV_T
A_L^A[alJaAmpA]NlamVa_wVpUmVT_VœJA_pLA^ATNpa-AJVœJaAmpVTUwAyA_L
residential areas.
x :V_pNl1pal^m0-4305): Record-IlNA\V_TlAV_SA]]]NLpamVT_VœJA_pqlIA_
ŔaaLV_T laAL J]amqlNm A_L ^qLm]VLNm wVpU mNvNlN V^iAJpm AJlamm ^q]pVi]N
communities.
County of Los Angeles
All-Hazards Mitigation Plan
Page 86 of 204
x October 2021: Los Angeles County experienced a rare and intense thunderstorm
wVpUAmVT_VœJA_pA^aq_paS]VTUp_V_T
x September 2022 Hurricane KayiAJVœJUqllVJA_NpUApJAqmNLmVT_VœJA_plAV_SA]]
A]a_TwVpUlVm\aS^qLŔawmJaAmpA]ŔaaLV_TA_LJaAmpA]NlamVa_
x A_qAlyp^amiUNlVJ0VvNlvN_p0-4683): Heavy rainfall overwhelmed
mpal^LlAV_mJAqmV_TmVT_VœJA_pŔaaLV_TV_a]]ywaaL
A]LwV_V]]mA_L]aw-lying
V_]A_LAlNAm]NALV_TpaNvAJqApVa_mA_LV_SlAmplqJpqlNLA^ATN
x NIlqAly!am_TN]Nm]aaLm0-4699): A series of intense storms caused
wVLNmilNALŔAmUŔaaLV_TSlNNwAyJ]amqlNmA_L]A_Lm]VLNmLN^a_mplApV_T pUN
increasing vulnerability of the county's urban areas to extreme precipitation events.
x qTqmp3laiVJA]1pal^V]Aly0-4750): Several locations in the mountains
of Southern California received over 10 inches of rainfall which set daily and/or
^a_pU]ylAV_SA]]lNJalLmV_^A_y]aJApVa_mV_1aqpUNl_A]VSal_VAV_J]qLV_TwVpUV_
!am_TN]Nmaq_pypA]maJlNApNLmVT_VœJA_ppUlNApaSŔAmUA_LlVvNlV_NŔaaLV_T
prompted the evacuation of numerous vulnerable communities near burn scars in
the region.
x NJN^INl-AJVœJ1pal^1pal^mqlTNmA_LNxplN^NJaAmpA]ŔaaLV_T]NLpa
mVT_VœJA_pNlamVa_A]a_TpUNJaAmp]V_NiAlpVJq]Al]yV^iAJpV_T"AlV_ALN]0Ny!a_T
NAJUA_L9N_VJN
NAJU
x February - "AlJUp^amiUNlVJ0VvNl1pal^0-4769): One of the most
V_pN_mNlAV_SA]]NvN_pmV_lNJN_pUVmpalylNmq]pV_TV_mNvNlNŔAmUŔaaLm^qLm]VLNm
A_LiawNlaqpATNmwVpU^A_yUa^NmA_LIqmV_NmmNmmqmpAV_V_TŔaaLLA^ATN
6.6.5 Probability
]aaLlNJqllN_JNV_!am_TN]Nmaq_pyVmV_ŔqN_JNLIyIapU_ApqlA]J]V^ApNvAlVAIV]Vpy
A_LpUNV_JlNAmV_TNSSNJpmaSJ]V^ApNJUA_TNVmpalVJA]]ymNvNlNŔaaLV_TVm^amp]V\N]y
LqlV_Tmpla_T]#V`aNvN_pmwUVJUaJJqlAiilaxV^ApN]yNvNlypayNAlmAnd can
persist for several months to multiple years. These events bring elevated precipitation
]NvN]mA_LV_JlNAmNpUN]V\N]VUaaLaSIapUV_]A_LA_LJaAmpA]ŔaaLV_T
mJ]V^ApNJUA_TNAJJN]NlApNmpUNSlNkqN_JyA_LV_pN_mVpyaSŔaaL-generating events
AlNNxiNJpNLpaV_JlNAmNA]pNlV_TplALVpVa_A]lNJqllN_JNV_pNlvA]mA_LNxiA_LV_TpUN
areas at risk. 3UNlNVmA ÈJUA_JNaSAŔaaLV_TNvN_paJJqllV_TNAJUyNAlwVpUV_T!am
Angeles County.
County of Los Angeles
All-Hazards Mitigation Plan
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Key climate-related drivers include:
x Sea-!NvN]0VmN-la[NJpNLpalVmNIyV_JUNmpaavNlSNNpIy V_JlNAmV_TpUN
lVm\aSpVLA]A_Lmpal^mqlTNŔaaLV_TV_JaAmpA]Ja^^q_VpVNm
x p^amiUNlVJ 0VvNl vN_pm JJalLV_T pa pUN 30 pUNmN NvN_pm AlN
INJa^V_T^alNSlNkqN_pA_LV_pN_mN]NALV_TpaN]NvApNLŔAmUŔaaLA_LLNIlVm
ŔawlVm\m
x El Niño Cycles1pV]]NxiNJpNLNvNlypayNAlmIqpwVpUV_JlNAmNLvAlVAIV]VpyA_L
mpal^V_pN_mVpypUApJA_avNlwUN]^]aJA]LlAV_ATNA_LŔaaLJa_pla]mympN^m.
3UNmN Nva]vV_T Ja_LVpVa_m JUA]]N_TN NxVmpV_T ŔaaLi]AV_ ^Aim A_LLNmVT_
Ammq^ipVa_mUVTU]VTUpV_TpUN_NNLSalALAipVvNi]A__V_TqiLApNLlVm\^aLN]mA_L
Ja_pV_qNLV_vNmp^N_pV_lNmV]VN_pV_SlAmplqJpqlNA_LŔaaL^VpVTApVa_mplApNTVNm
6.6.6 Vulnerability
!am_TN]Nmaq_pySAJNmwVLNmilNALA_L]AyNlNLvq]_NlAIV]VpVNmpaŔaaLV_TmUAiNL
by a combination of environmental exposure and complex social factors. Physical
vulnerability is pronounced in areas located within FEMA-designated Special Flood
A|AlLlNAm1m iamp-wV]LœlNIql_mJAlmA_L]aw-lying urban drainage basins
pUApAlNila_NpaŔaaLV_TawNvNlpUNLNTlNNaSlVm\VmmVT_VœJA_p]yUNVTUpN_NLSal
JNlpAV_iaiq]ApVa_mwUa^Ay]AJ\pUNlNmaqlJNmalJAiAJVpypailNiAlNSallNmia_Lpa
and reJavNl Sla^ ŔaaL NvN_pm 1aJVA]]y vq]_NlAI]N Tlaqim V_J]qLV_T a]LNl ALq]pm
V_LVvVLqA]m wVpU LVmAIV]VpVNm al AJJNmm A_L Sq_JpVa_A] _NNLm # ^aIV]N Ua^N
lNmVLN_pmiNai]NNxiNlVN_JV_TUa^N]Nmm_NmmA_L]aw-V_Ja^NUaqmNUa]LmAlN^alN
likely to reside in structurally vulnerable housing.
According to the 2021 Los Angeles County Comprehensive Floodplain Management
-]A_^alNpUA_AkqAlpNlaSlNmVLN_pm]VvV_TwVpUV_pUN-yNAlŔaaLi]AV_NAl_]Nmm
pUA_¸A__qA]]yq_LNlmJalV_TpUNLVmilaialpVa_ApNNJa_a^VJIqlLN_SAJNLIy
those least able to absorb the costs of recovery. Climate vulnerability data further
LN^a_mplApNmpUAp^AlTV_A]V|NLJa^^q_VpVNmV_ŔaaL-exposed areas face elevated
lVm\mLqNpaŔaaLV_TNvN_pm3UNvq]_NlAIV]Vpy]A_LmJAiNVmSqlpUNlJa^i]VJApNLIyA
shortage of affalLAI]NŔaaL-lNmV]VN_pmplqJpqlNmA_LA_V_JlNAmV_T_q^INlaSlNmVLN_pm
living in areas newly exposed due to climate-driven changes in precipitation and runoff
patterns.
County of Los Angeles
All-Hazards Mitigation Plan
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6.6.7 Impacts
Flooding in Los Angeles County leads to a broad range of direct and cascading impacts
a_ iNai]N V_SlAmplqJpqlN N_vVla_^N_p A_L pUN NJa_a^y 3UN aq_py¯m NxpN_mVvN
_Npwal\ aS JlVpVJA] SAJV]VpVNm V_J]qLV_T UamiVpA]m œlN mpApVa_m wAmpNwApNl plNAp^N_p
p]A_pmmJUaa]mA_LiawNlmqImpApVa_m3UNmNAlNAmSAJNlNJqllV_TNxiamqlNwVpUV_
both 100- and 500-yNAlŔaaLi]AV_mA^ATNpapUNmNSAJV]VpVNm_apa_]yJa^ila^VmNm
their physical integrity but also threatens their functionality during emergency
response operations.
]aaLV_TaSpN_LVmlqipm]VSN]V_NmNlvVJNmmqJUAmN]NJplVJVpyiapAI]NwApNlmA_VpApVa_
A_LplA_mialpApVa_wVpUlqlA]A_Lq_V_JalialApNLAlNAmSAJV_TpUNTlNApNmpJUA]]N_TNm
palAiVLlNmpalApVa_"aIV]NUa^NmSlNkqN_p]yJa_JN_plApNLV_]aw-lying or under-
LlAV_NL _NVTUIalUaaLm AlN NmiNJVA]]y mqmJNipVI]N pa ŔaaL LA^ATN LqN pa
Ja_mplqJpVa_]V^VpApVa_mA_LV_ALNkqApNilapNJpVvN^NAmqlNm-lNvVaqmŔaaLNvN_pm
UAvNlNmq]pNLV_mVT_VœJA_pLNIlVmŔawmlaALJ]amqlNmplAV_mpaiiATNmA_LLA^ATN
to public and private structures.
-lV^Aly9q]_NlAIV]VpVNmË^iAJpm
x %vNlmplqJpqlNmAlNNmpV^ApNLpaINLA^ATNLV_A-yNAlŔaaLNvN_pwVpU
papA]LA^ATNmNxJNNLV_T¸^V]]Va_V_ilaiNlpy]ammNmV_q_V_JalialApNL!am
Angeles County.
x LLVpVa_A]]y^alNpUA_JlVpVJA]SAJV]VpVNmAlNNxiamNLV_pUN -yNAlŔaaLi]AV_
while 70 are within the 100-yNAlŔaaLi]AV_V_J]qLV_TplA_mialpApVa_AmmNpmqpV]VpVNm
N^NlTN_JymNlvVJNmA_LUA|AlLaqm^ApNlVA]mSAJV]VpVNm
x A 100-yNAlŔaaLNvN_pJaq]LLVmi]AJNavNlApUaqmA_LiNai]NwVpU^A_ylNkqVlV_T
mUN]pNlV_TmqiialpA_LlNJavNlyNSSalpm
x iilaxV^ApN]y pa_maSIqV]LV_T-related debris could be generated by a 100-
yNAl ŔaaL NvN_p wVpU J]NA_-qilNkqVlV_T^alNpUA_plqJ\]aALmiamV_T
]aTVmpVJA]N_vVla_^N_pA]A_LiqI]VJUNA]pUJUA]]N_TNm
x 28.6% of households in the 100-yNAlŔaaLi]AV_AlNNJa_a^VJA]]yLVmALvA_pATNL
NAl_V_Tq_LNl¸iNlyNAl]V^VpV_TpUNVlAIV]VpypaNvAJqApNlNJavNlaliAySal
mitigation improvements.
x ]AlTNmUAlNaSŔaaL-prone properties are either uninsured or underinsured. The
AvNlATNŔaaLV_mqlA_JNJ]AV^iAyaqpVm¸wUVJUVma_]yAIaqpÈaSpUN
County of Los Angeles
All-Hazards Mitigation Plan
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ŚĂƌƚƐ^ŽƵƌĐĞ͗ >ŽƵŶƚLJWƵďůŝĐtŽƌŬƐ͖ϮϬϮϭ ŽƵŶƚLJŽŵƉƌĞŚĞŶƐŝǀĞ&ůŽŽĚWůĂŶ
AvNlATNlNi]AJN^N_pJampaSmplqJpqlNmV_pUNŔaaLi]AV_—V_LVJApV_TmVT_VœJA_pTAim
V_œ_A_JVA]lNmV]VN_JN
x :V]LœlNIql_mJAlmA_Liamp-œlNUyLlaiUaIVJmaV]mmVT_VœJA_p]yV_JlNAmNŔaaLA_L
LNIlVm Ŕaw lVm\m iAlpVJq]Al]y V_ SaapUV]] A_L JA_ya_ Ja^^q_VpVNm 3UVm UA|AlL
continues to grow in severity with climate-LlVvN_œlNmNAma_m
6.6.8 Mitigation and Preparedness
!am_TN]Nmaq_py¯mŔaaL^VpVTApVa_mplApNTylNLqJNmUA|AlLNxiamqlNN_UA_JNm
Ja^^q_VpylNmV]VN_JNA_Lmqiialpm]a_T-term climate adaptation. Grounded in FEMA’s
#ApVa_A] "VpVTApVa_ lA^Nwal\ A]%1 i]A__V_T TqVLA_JN A_L ]aJA] ia]VJy pUN
County implements both structural and non-structural measures to address current and
SqpqlNŔaaLlVm\malNAJpVa_mV_J]qLNlNTq]Al^AV_pN_A_JNA_LpAlTNpNLqiTlALNmpa
Estimated Damage to Critical Facilities in Unincorporated Areas from 100-Year Flood
Sector Number of Facilities
Affected
Average % of Total 9A]qN
Damaged
Structure Content
Safety & Security 1 7.56 10.24
Food, Water & Sheltering 9 6.72 18.73
Health & Medical 0 N/A N/A
Energy 1 23.90 47.79
Communications 0 N/A N/A
Transportation 59 1.41 8.86
Hazardous Materials 0 N/A N/A
Total/Average 70 9.90 21.40
Estimated Damage to Critical Facilities in Unincorporated Areas from 500-Year Flood
Sector Number of Facilities Affected
Average % of Total 9A]qN
Damaged
Structure Content
Safety & Security 4 28.39 37.56
Food, Water & Sheltering 41 7.73 27.01
Health & Medical 0 N/A N/A
Energy 1 23.90 47.79
Communications 2 5.00 16.00
Transportation 107 3.38 19.74
Hazardous Materials 30 10.00 15.00
Total/Average 185 13.07 27.18
County of Los Angeles
All-Hazards Mitigation Plan
Page 90 of 204
mpal^wApNlV_SlAmplqJpqlNlNmpalApVa_aSŔaaLi]AV_mA_LV_pNTlApVa_aSŔaaLUA|AlL
data into land use planning. The County also prioritizes the protection of critical
SAJV]VpVNm A_L vq]_NlAI]N UaqmV_T pUlaqTU mVpN lNplaœpm ilaiNlpy AJkqVmVpVa_ A_L
e]NvApVa_ilaTlA^m-qI]VJaqplNAJUVmJa_LqJpNLpUlaqTUAIV]V_TqA]-accessible
-laTlA^Sal-qI]VJ_Sal^ApVa_wUVJUila^apNmŔaaLmASNpyAwAlN_NmmN^NlTN_Jy
ilNiAlNL_NmmA_LiAlpVJViApVa_V_pUN#ApVa_A]]aaL_mqlA_JN-laTlA^#-
To ensure that mitigation is both data-driven and community-JN_pNlNLpUNaq_py
qpV]V|NmJ]V^ApNila[NJpVa_mA_L"¯m?41^aLN]V_TpaV_Sal^V_vNmp^N_pmwUV]N
coordinating with regional partners to align local actions with broader watershed
strategies. Key components of the approach include:
x 4iTlALV_T Jq]vNlpm LNIlVm IAmV_m A_L LlAV_ATN mympN^m pa ^A_ATN V_JlNAmNL
runoff
x Promoting low-impact development (LID) and incorporating green infrastructure in
urban design
x Updating ordinances and the General Plan to discourage development in high-risk
areas
x Maintaining inventories of repetitive loss areas and prioritizing resources for the
most vulnerable populations
This comprehensive strategy ensures Los Angeles County not only meets federal and
mpApNmpA_LAlLmIqpALvA_JNmŔaaLlVm\lNLqJpVa_V_AwAypUApmASNTqAlLmiNai]N
ilaiNlpyA_L_ApqlA]mympN^mSalpUNSqpqlN
6.6.9 Summary
Flooding is one of the most persistent and complex natural hazards in Los Angeles
aq_pyV_pN_mVœNLIyJ]V^ApNJUA_TNqlIA_V|ApVa_A_LATV_TV_SlAmplqJpqlN3UN!am
_TN]Nm aq_py lNTVa_ NxiNlVN_JNm A lA_TN aS ŔaaL pyiNmincluding stormwater
lq_aSSŔAmUŔaaLV_TJaAmpA]V_q_LApVa_A_Liamp-wV]LœlNLNIlVmŔawm3UNmNNvN_pm
are most common during winter storms and atmospheric river systems. High-density
LNvN]ai^N_pNxpN_mVvNiAvNLmqlSAJNmA_LœlN-damaged hillsides contribute to rapid
lq_aSSA_LV_JlNAmNLavNlA]]ŔaaLvq]_NlAIV]VpylNAmA]a_TIqp_ap]V^VpNLpa pUN!am
_TN]Nm1A_AIlVN]A_L1A_pA]AlA0VvNlmAmwN]]AmJaAmpA] Ja^^q_VpVNm A_L
SaapUV]]lNTVa_mAlNiAlpVJq]Al]yAplVm\
County of Los Angeles
All-Hazards Mitigation Plan
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Los Angeles County’s mitigation strategy is proactive and multifaceted. It includes
V_SlAmplqJpqlNqiTlALNm_ApqlN-IAmNLma]qpVa_m]A_LqmNia]VJyqiLApNmA_LiqI]VJ
NLqJApVa_alNilValVpVNmSaJqma_ilapNJpV_TJlVpVJA]SAJV]VpVNmlNLqJV_TNxiamqlNVn
high-lVm\UaqmV_TA_Lila^apV_TJa^^q_VpylNmV]VN_JN-]A__V_TNSSalpmAlNmqiialpNL
Iy"¯m?41lVm\^aLN]V_TA_L]aJA]J]V^ApNila[NJpVa_mNmiVpNilaTlNmm^alN
pUA_ lNmVLN_pmlN^AV_AplVm\Sla^^A[alŔaaLNvN_pmlNV_SalJV_TpUN_NNLfor
Ja_pV_qNLV_vNmp^N_pV_Ja^ilNUN_mVvNŔaaLlVm\lNLqJpVa_AJlammpUNJaq_py
6.6.10 National Flood Insurance Program (NFIP) Repetitive Loss
(RL)
JJalLV_TpapUN!am_TN]Nmaq_py-qI]VJ:al\mpUNlNAlN 0NiNpVpVvN!amm0!
properties in 28 RL areas of Unincorporated Los Angeles County as of 2025and 8
Severe Repetitive Loss Properties (SRLP). A Repetitive Loss (RL) property is any insurable
IqV]LV_TSalwUVJUpwaal^alNJ]AV^maS^alNpUA_¸wNlNiAVLIypUN#ApVa_A]
Flood Insurance Program (NFIP) in any rolling 10-year period since 1978. Updated
location information about RL properties in Unincorporated Los Angeles County were
not avai]AI]NLqlV_TpUNLlASpV_TaSpUVmi]A_IqpVmINV_Tœ_A]V|NLA_LwV]]INV_J]qLNL
in subsequent hazard mitigation efforts. Data from 2011 showed that 24 RL properties
were located in the SFHA. ppUNpV^NpUN!am_TN]Nmaq_py-qI]VJ:al\mmpApNL¬pUN
^A[alVpyaSpUNlNiNpVpVvN]ammNmAlNAmmaJVApNLwVpU]aJA]V|NLqlIA_LlAV_ATNŔaaL
ilaI]N^mNvN_SalilaiNlpVNmwVpUV_A"-LNmVT_ApNLŔaaL|a_N3UN!am_TN]Nm
County Public Works oversees RL mitigation projects.
County of Los Angeles
All-Hazards Mitigation Plan
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AAAllAllAllAlAllAllAllAlAllAllAllAllAAAAAAAAAlAAAlllllAAAAAAAAAAAllAllAAAAAAAlAlAllllAAllAAAAAllllAAAAAAAlll----------------HazHazHazHHazHazHHHHazHazaHazaazHazHazHHHazHazHHazHHazazazHaHazHazazaHHazHazHaHazHazHHHHaHHHHHHHazHzHHHazzzzzHHHazzzzzzHHHHHaazHHazHaHHaHHaHazHazzHHHHHHHHaHaaazazazzzzzHHHHaHaHHaHazazzHazHazHzazazzzHazHHHaHHaHaHaazHazzHHazazHazazardardardardardardddardddddardardardardarddrdrdardardardardardardardarardaardardardardardaardaradaddrdaaaaaaardddrdaaaaaaaaararrrdrdrdddardrdardaaaaaaararardddardaardrardrddardaaraaaarrdardrddrdardrdardardrddaddardardardardrdddardardardardardardrdssMsMsMMsMMMMMMMsMMsMMssMsMMMMsMsMMMsMsMsMsMMMMMMMMMMMMMMMMssssMMsMMsMMsMssMMMMsMMMMMssMssMsMsMsMMMssssMsMsMMsMsMsMsMsMsMsssMsMsMssssMMMsMs Ms Ms Ms Mss MMMMs MMitiiiitiititiititiitiiitiittiititiiiitttiititttiiittititiiiiitttiiiititiittitiitiitttttitiiititiitiiittitititiitiitittiitiitiitiititiitiitiiitititititiitiitititi tttttttttttgatggggagaagaagatatatgatgatgatgatggggagaaagagatgggagaggagaattgatagataggagagatatgatggaaatatgatgatggatgatggatgatgattggaggagagatgggatgatatgatgatggatagatgatgagatgagataagiiiioninioniononnnniiononnniiiiionnnonnionnionioonionnioniioononnnnnnooonionioonononionnnionononionioonnionionionionionionnioonnioooooonononnnnionooononnnnoonnnnnn PPPPPlaPlaPlalaPlaPlaPlaPlalalPlPPPPPPPPPlPlPlalPlaPPPPlalPPPPPPPlallPPPPPlllnnnnnnnnnnnnnnnnnn
6.7 Dam Failure
6.7.1 Nature
Dam failure refers to the structural collapse of a
dam that results in the sudden and uncontrolled
release of stored water. Such failures can occur
due to age-lN]ApNL LNpNlValApVa_ V_ALNkqApN
miV]]wAy JAiAJVpy mplqJpqlA] LA^ATN Sla^
mNVm^VJ AJpVvVpy al ŔaaLV_T A_L iaal
maintenance. The catastrophic release of water
from a dam failure has the potential to cause
human JAmqA]pVNmmVT_VœJA_pNJa_a^VJ]ammA_L
environmental destruction. This type of disaster
is particularly dangerous because it can occur
mqLLN_]y]NAvV_T]Vpp]NpV^NSalNvAJqApVa_al
emergency response efforts.
3UN ^AT_VpqLN aS ŔaaLV_T Sla^ LA^ SAV]qlN
often exceeds the capacity of downstream
JUA__N]m JAqmV_T lAiVL V_q_LApVa_ aS
mqllaq_LV_T AlNAm 3UVm ŔaaLV_T JA_ ]NAL pa
NxpN_mVvN ilaiNlpy LA^ATN NlamVa_
V_SlAmplqJpqlNLNmplqJpVa_A_LJa_pA^V_ApVa_aS
watelmqii]VNmLLVpVa_A]]ymNJa_LAlyUA|AlLm
mqJUAm]A_Lm]VLNmA_LLNIlVmŔawmJA_IN
plVTTNlNLJa^iaq_LV_TpUNLVmAmpNl¯mV^iAJp
The structural stress on dams may rise as dams
ATNA_LJ]V^ApNvAlVAIV]VpyV_JlNAmNmpUNSlNkqN_JyaSNxplN^NilNJViVpApVan events.
Planning efforts include both dams and debris basins. To simplify language of the plan
both reservoir dams and storm water debris basins will be referred to as dams.
County of Los Angeles
All-Hazards Mitigation Plan
Page 93 of 204
6.7.2 Location
Los Angeles County has over 90 dams regulated by the California Department of Water
Resources’ Division of Safety of Dams (DSOD). Fifteen (15) of these dams and eighteen
(18) debris basins are owned and operated by the Los Angeles County Public Works
-: _pUNA]VSal_VA!NTVm]ApqlN^A_LApNLpUApA]]mpApN-jurisdictional dams
NxJ]qLV_TpUamNJ]AmmVœNLAm!awA|AlL LNvN]aiLA^IlNAJUV_q_LApVa_^AimA_L
Emergency Action Plans (EAPs) approved by DSOD and Cal OES.
"A_yaSpUNmNLA^mAlN]aJApNL_NAlUVTU]yiaiq]ApNLAlNAmV_JlNAmV_TpUNiapN_pVA]
for human and economic impacts during a failure event. Seventy (70) dams are
J]AmmVœNLAmVTUalxplN^N]yVTUUA|AlLiapN_pVA]LA^m^NA_V_TpUNVlSAV]qlNJaq]L
result V_mVT_VœJA_p]ammaS]VSNA_LwVLNmilNALilaiNlpyLA^ATN
3UN:UVppVNl#AllawmA^lNJ]AmmVœNLAmpUN41l^yalimaS_TV_NNlm¯41
highest-ilValVpyLA^mASNpyJa_JNl_iamNma_NaSpUNTlNApNmplVm\mLqNpaVpmiapN_pVA]
paŔaaLUVTU]yiaiq]ApNLAlNAmSla^-VJa0VvNlApa!a_T
NAJU41 UAm
determined that an extreme storm event has a 1 in 900 (0.1%) chance of causing
catastrophic failure annually. Mitigation actions related to County-owned dams are
prioritized based on their hazard level and potential to impact populated areas.
For a better visual representation of this Dam Failure Hazard within the LA County
i]A__V_TAlNAplease reference Appendix A for all the County owned dams and debris
basins maps.
6.7.3 Extent
The Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam
Incidents and Failures (FEMA P- JApNTalV|Nm LA^ UA|AlLm V_pa Saql
J]AmmVœJApVa_m
x Low Hazard"V_V^A]LA^ATNNxiNJpNL_a]ammaS]VSN
x 1VT_VœJA_pA|AlL: Potential for property damage and economic disruption.
x High Hazard!V\N]ypalNmq]pV_]ammaS]VSNA_LmVT_VœJA_pLA^ATNpaJlVpVJA]
infrastructure.
x xplN^N]yVTUA|AlL1%]AmmVœJApVa_ : Could cause large-scale fatalities
A_LV_q_LApNAlNAmwVpUavNllNmVLN_pm
VvN_pUNiaiq]ApVa_LN_mVpyaS!am_TN]Nmaq_pyALA^SAV]qlNJ]AmmVœNLAmVTUal
xplN^N]yVTUA|AlLwaq]L]V\N]yJAqmNmqImpA_pVA]Uq^A_JAmqA]pVNmLVmi]AJNN_pVlN
Ja^^q_VpVNmA_LV_ŔVJpmNvNlNNJa_a^VJA_LN_vVla_^N_pA]LA^ATNTable 6-3 and
6-4 below shows a list of dams and debris basins owned by PW along with their hazard
J]AmmVœJApVa_m-apN_pVA]^VpVTApVa_AJpVa_mLNmJlVINLV_pUVm"-AlNa_]yAii]VJAI]N
to the dams and debris basins owned by PW and implementation of these actions are
the responsibility of the PW Stormwater Engineering Division – Dams Section.
County of Los Angeles
All-Hazards Mitigation Plan
Page 94 of 204
Table 6-3: Los Angeles County PW Dam Hazard Status
Dam Name Hazard Status >ŽĐĂƟŽŶ
ŝŐĂůƚŽŶ džƚƌĞŵĞůLJ,ŝŐŚ 'ůĞŶĚŽƌĂ͕
ŝŐ^ĂŶƚĂŶŝƚĂ džƚƌĞŵĞůLJ,ŝŐŚ DŽŶƌŽǀŝĂ͕
ŝŐdƵũƵŶŐĂEŽ͘ϭ džƚƌĞŵĞůLJ,ŝŐŚ dƵũƵŶŐĂ͕
ŽŐƐǁĞůů džƚƌĞŵĞůLJ,ŝŐŚ njƵƐĂ͕
ĞǀŝůƐ'ĂƚĞ džƚƌĞŵĞůLJ,ŝŐŚ >ĂŶĂĚĂ&ůŝŶƚƌŝĚŐĞ͕
>ŝǀĞKĂŬ džƚƌĞŵĞůLJ,ŝŐŚ >ĂsĞƌŶĞ͕
DŽƌƌŝƐ džƚƌĞŵĞůLJ,ŝŐŚ njƵƐĂ͕
WĂĐŽŝŵĂ džƚƌĞŵĞůLJ,ŝŐŚ WĂĐŽŝŵĂ͕
WƵĚĚŝŶŐƐƚŽŶĞ džƚƌĞŵĞůLJ,ŝŐŚ ^ĂŶŝŵĂƐ͕
WƵĚĚŝŶŐƐƚŽŶĞŝǀĞƌƐŝŽŶ ,ŝŐŚ >ĂsĞƌŶĞ͕
^ĂŶŝŵĂƐ džƚƌĞŵĞůLJ,ŝŐŚ >ĂsĞƌŶĞ͕
^ĂŶ'ĂďƌŝĞůEŽ͘ϭ džƚƌĞŵĞůLJ,ŝŐŚ njƵƐĂ͕
^ĂǁƉŝƚ džƚƌĞŵĞůLJ,ŝŐŚ DŽŶƌŽǀŝĂ͕
^ŝĞƌƌĂDĂĚƌĞ ,ŝŐŚ ^ŝĞƌƌĂDĂĚƌĞ͕
dŚŽŵƉƐŽŶƌĞĞŬ džƚƌĞŵĞůLJ,ŝŐŚ ůĂƌĞŵŽŶƚ͕
Table 6-4: Los Angeles County PW Debris Basin Hazard Status
Debris Basin Name Hazard Status >ŽĐĂƟŽŶ
ĂŝůĞLJĞďƌŝƐĂƐŝŶ ,ŝŐŚ ^ŝĞƌƌĂDĂĚƌĞ͕
ŝŐĂůƚŽŶĞďƌŝƐĂƐŝŶ ,ŝŐŚ 'ůĞŶĚŽƌĂ͕
ůĂŶĐŚĂƌĚĞďƌŝƐĂƐŝŶ ,ŝŐŚ dƵũƵŶŐĂ͕
ƌĂŶĚĞďƌŝƐĂƐŝŶ ,ŝŐŚ 'ůĞŶĚĂůĞ͕
ĂƚŽŶtĂƐŚĞďƌŝƐĂƐŝŶ džƚƌĞŵĞůLJ,ŝŐŚ WĂƐĂĚĞŶĂ͕
>ĂdƵŶĂĞďƌŝƐĂƐŝŶ džƚƌĞŵĞůLJ,ŝŐŚ ^ƵŶsĂůůĞLJ͕
>ĂŐƵŶĂZĞŐƵůĂƟŶŐĂƐŝŶ ^ŝŐŶŝĮĐĂŶƚ ůŚĂŵďƌĂ͕
>ŝƩůĞĂůƚŽŶĞďƌŝƐĂƐŝŶ džƚƌĞŵĞůLJ,ŝŐŚ 'ůĞŶĚŽƌĂ͕
>ŽǁĞƌ^ƵŶƐĞƚĞďƌŝƐĂƐŝŶ ,ŝŐŚ ƵƌďĂŶŬ͕
DŽƌŐĂŶĞďƌŝƐĂƐŝŶ ,ŝŐŚ 'ůĞŶĚŽƌĂ͕
ZƵďŝŽĞďƌŝƐĂƐŝŶ ,ŝŐŚ ůƚĂĚĞŶĂ͕
^ĂŶƚĂŶŝƚĂĞďƌŝƐĂƐŝŶ >Žǁ ƌĐĂĚŝĂ͕
^ĂǁƉŝƚĞďƌŝƐĂƐŝŶ džƚƌĞŵĞůLJ,ŝŐŚ DŽŶƌŽǀŝĂ͕
County of Los Angeles
All-Hazards Mitigation Plan
Page 95 of 204
Debris Basin Name Hazard Status >ŽĐĂƟŽŶ
^ĐŚŽŽůŚŽƵƐĞĞďƌŝƐĂƐŝŶ ,ŝŐŚ >ŽƐŶŐĞůĞƐ͕
^ŝĞƌƌĂDĂĚƌĞsŝůůĂ džƚƌĞŵĞůLJ,ŝŐŚ ^ŝĞƌƌĂDĂĚƌĞ͕
^ƚĞǀĞŶƐŽŶZĂŶĐŚ ,ŝŐŚ ^ƚĞǀĞŶƐŽŶZĂŶĐŚ͕
^ƚŽƵŐŚĞďƌŝƐĂƐŝŶ džƚƌĞŵĞůLJ,ŝŐŚ ƵƌďĂŶŬ͕
tŝůƐŽŶĞďƌŝƐĂƐŝŶ ,ŝŐŚ >ŽƐŶŐĞůĞƐ͕
6.7.4 History
Los Angeles County has experienced one of the deadliest dam failures in U.S. history:
x St. Francis Dam Failure (March 12-
o Released 12.4 billion gallons of water
o At least 411 fatalities
o Devastated towns from San Francisquito Canyon to Ventura County
o Resulted in sweeping changes to California dam safety regulations and the
creation of state oversight for civil engineers
:UV]N_a^A[alLA^SAV]qlNmUAvNaJJqllNLV_lNJN_pLNJALNmJa_JNl_mavNlATV_T
LA^V_SlAmplqJpqlNmNVm^VJlVm\mA_LV_JlNAmV_TJ]V^ApNvAlVAIV]VpyUAvNlAVmNLA]Al^m
AIaqpSqpqlNlVm\m1pqLVNmV_LVJApNpUAp^A_yA]VSal_VALA^mV_J]qLV_TpUamNV_!am
_TN]Nm aq_py lNkqVlN mplqJpqlA] qiLApNm pa wVpUmpA_L ^aLNl_UyLla]aTVJA]
conditions and potential seismic activity. There have been no federal declarations or
mpApNilaJ]A^ApVa_mSalLA^SAV]qlNV_pUN]AmpœvNyNAlm
6.7.5 Dam Coordination
Los Angeles County Public Works JaalLV_ApNmwVpU]aJA]mpApNA_LSNLNlA]ATN_JVNmpa
^VpVTApNŔaaLlVm\UA|AlLmpaLaw_mplNA^Ja^^q_VpVNmSla^VpmL A^mppUN]aJA]]NvN]
PW works with cities and public agencies during development of Emergency Action
-]A_m- 3UVmilavVLNm]aJA]mpA\NUa]LNlmwVpUpUNaiialpq_VpypalNvVNwpUN-
ilavVLNSNNLIAJ\A_LJa_œl^lNmia_mVIV]VpVNmA_Lla]NmLqlV_TA_-AJpVvApVa_p
request from local [qlVmLVJpVa_mPW ^Ay ilavVLN paqlm aS Vpm LA^ SAJV]VpVNm wUNlN
information on dam safety and the potential hazards associated with dam failures are
shared.
ppUNmpApN]NvN]PW works with the DSOD to meet compliance with state dam safety
mpA_LAlLm A_L ŔaaL ^A_ATN^N_p Ap A]] aSPW’s dams. This includes annual dam
County of Los Angeles
All-Hazards Mitigation Plan
Page 96 of 204
V_miNJpVa_mlNvVNwAiilavA]A_LavNlmVTUpaSLA^Ja_mplqJpVa_ila[NJpmlNvVNwaS
LA^mASNpy^a_VpalV_TA_LavNlmVTUpaSapUNlLA^mASNpylNTq]ApalyAJpVvVpVNmPW also
JaalLV_ApNmwVpUvAlVaqmmpApNATN_JVNmV_J]qLV_T1%A]%1A_LA]plA_mLqlV_T
development of EAPs.
ppUNSNLNlA]]NvN]PW works with the Federal Energy Regulatory Commission (FERC)
pa^NNpJa^i]VA_JNwVpUmpApNLA^SNLNlA]mpA_LAlLmA_LŔaaL^A_ATN^N_pApPW’s
1A_ AIlVN] A^ wUVJU Vm q_LNl 0 [qlVmLVJpVa_ 3UVm V_J]qLNm A__qA] LA^
V_miNJpVa_mlNvVNwAiilavA]A_LavNlmVTUpaSLA^Ja_mplqJpVa_ila[NJpmlNvVNwaS
LA^mASNpy^a_VpalV_T-JaalLV_ApVa_A_LavNlmVTUpaSapUNlLA^mASNpylNTq]Apaly
activities. PW also coordinates with the United States Army Corps of Engineers (USACE)
on operations of interconnected dam facilities and emergency response planning for
USACE facilities that may be in the pathway of dam failure impacts.
Information Sharing
PW ilavVLNmJlVpVJA]V_Sal^ApVa_palN]NvA_p]aJA]mpApNA_LSNLNlA]mpA\NUa]LNlmpa
address hazard mitigation related to dam safety. This includes:
x Emergency Action Plans (EAPs): -maqp]V_NpUNla]NmlNmia_mVIV]VpVNmA_L
procedures to follow in the event of a dam emergency. The EAPs include
V_q_LApVa_^AimwUVJUmUawAlNAmpUApwaq]LINASSNJpNLIyALA^SAV]qlN
helping to identify populations at risk. These plans are shared with stakeholders
to ensure a coordinated response. Due to the sensitive nature of information
Ja_pAV_NLwVpUV_pUN-mpUNyAlNJa_œLN_pVA]A_L_aplN]NAmNLpapUNTN_NlA]
public.
x Inundation Maps: Inundation maps are critical tools for identifying areas and
populations at risk in the event of a dam failure. They also indicate potential
V^iAJpm a_ JlVpVJA] V_SlAmplqJpqlN SAJV]VpVNm mqJU Am UamiVpA]m mJUaa]m A_L
transportation networks. These maps are shared with relevant stakeholders
recognized in the EAP and are available to the general public through the DSOD
Dam Breach Inundation Map Web Publisher.
6.7.6 Probability
Los Angeles County contains over 90 state-[qlVmLVJpVa_A]LA^mwVpUAiilaxV^ApN]y
J]AmmVœNLAmVTUalxplN^N]yVTUA|AlLIypUNA]VSal_VAVvVmVa_aS1ASNpyaSA^m
1% ^NA_V_T pUNVl SAV]qlN Jaq]L lNmq]p V_ ]amm aS ]VSN A_LmVT_VœJA_p ilaiNlpy
damage.
County of Los Angeles
All-Hazards Mitigation Plan
Page 97 of 204
]pUaqTUJa^ilNUN_mVvNSAV]qlNilaIAIV]VpVNmAlN_apiqI]VmUNLSalNAJULA^"
and DSOD guidance suggest that the general annual probability of failure for High
A|AlLLA^m_ApVa_wVLNlA_TNmSla^ÈpaÈalV_paV_
depending on ^AV_pN_A_JNATNmNVm^VJvq]_NlAIV]VpyA_LapUNlmVpN-miNJVœJSAJpalm
Applying this range to Los Angeles County:
x 3UN ATTlNTApN A__qA] ilaIAIV]Vpy aS A mVT_VœJA_p LA^ SAV]qlN NvN_p V_ pUN
county—across one or more of the 70 high-risk dams—is estimated at between
ÈA_L ÈA__qA]]ySAJpalV_TJq^q]ApVvNNxiamqlNA_LLVSSNlN_pUA|AlL
J]AmmVœJApVa_m1qJUAmNAlpUkqA\NalŔaaLlN]ApNL
x ]V^ApNJUA_TNATV_TV_SlAmplqJpqlNA_LmNVm^VJAJpVvVpyV_!am_TN]Nmaq_py
increase systemic risk across multiple structures simultaneously.
_mq^^AlywUV]NpUNV_LVvVLqA]]V\N]VUaaLaSSAV]qlNSalA_ya_NLA^VmvNly]awpUN
overall countywide probability of at least one major dam failure event is low but still
wAllA_pmJa_pV_qNLvVTV]A_JN^AV_pN_A_JNA_LN^NlTN_Jyi]A__V_T
6.7.7 Vulnerability
A catastrophic dam failure in Los Angeles County could have severe consequences for
Uq_LlNLm aS pUaqmA_Lm aS lNmVLN_pm3UN LN_mN]y iaiq]ApNL _ApqlNaSpUNJaq_py
combined with the location of several large dams near residential and commercial
AlNAmV_JlNAmNmpUNiapN_pVA]SalwVLNmilNALLVmi]AJN^N_p]ammaS]VSNA_LNJa_a^VJ
LA^ATN3UN30VLN_pVœNm^q]pVi]NUVTU-risk zones where dam failure could
lNmq]pV_NxpN_mVvNŔaaLV_TA_L^AmmNvAJqApVa_m
x High-lVm\LA^mA^a_TapUNlmiamNAmVT_VœJA_ppUlNAppaLN_mN]yiaiq]ApNL
communities. A breach in any of these dams could inundate entire
_NVTUIalUaaLmASSNJpV_T^alNpUA_ lNmVLN_pmV_]aw-lying areas and
ŔaaLi]AV_m
x 1aJVA]]y vq]_NlAI]N iaiq]ApVa_m V_J]qLV_T N]LNl]y V_LVvVLqA]mpUN#
Ja^^q_VpyiNai]NNxiNlVN_JV_TUa^N]Nmm_Nmm]aw-V_Ja^NJa^^q_VpVNmA_L
non-English-speaking residents face heightened risks during evacuations and
lNJavNlyLqNpa]V^VpNL^aIV]Vpyœ_A_JVA]Ja_mplAV_pmA_LAJJNmmpalNmaqlJNm
x LqJApVa_A]A_LUNA]pUJAlNV_mpVpqpVa_mAlNAplVm\wVpUmNvNlA]mJUaa]mUamiVpA]m
and long-pNl^JAlNSAJV]VpVNm]aJApNLV_ŔaaL-prone areas. A major dam failure
Jaq]L lNmq]p V_ mJUaa] J]amqlNm LVmi]AJN^N_p aS mpqLN_pm A_LLVmlqipVa_ aS
healthcare services.
County of Los Angeles
All-Hazards Mitigation Plan
Page 98 of 204
x vAJqApVa_A_LN^NlTN_JymUN]pNlV_TLN^A_Lmwaq]LINmqImpA_pVA]lNkqVlV_T
the rapid mobilization of resources to support displaced residents. Temporary
mUN]pNlmN^NlTN_Jy^NLVJA]mNlvVJNmA_Llogistical support would need to be
activated to accommodate evacuees.
!am_TN]Nmaq_pylN]VNmUNAvV]ya_LA^mA_LlNmNlvaVlmSalwApNlmpalATNŔaaL
Ja_pla]A_Lmqii]ylNTq]ApVa_ApAmplaiUVJLA^SAV]qlNiamNmA_AJqpNpUlNAppa]VSN
A_LilaiNlpyNmiNJVA]]yV_]aw-]yV_TUVTU]yiaiq]ApNLLaw_mplNA^AlNAm
Extent of Exposure
x Total Area Exposed : 490.64 sq mi
x Supervisorial Districts (SD) Impacted:
o SD5: 223.88 sq mi (7.97%)
o SD1: 162.25 sq mi (45.98%)
o SD2: 66.57 sq mi (18.32%)
o SD3: 25.76 sq mi (5.97%)
o SD4: 12.17 sq mi (5.72%)
x Critical Facilities Affected:
o Fire Department: 112 (33.22%)
o Public Works: 92 (40.00%)
o Health Services: 29 (44.62%)
o Public Health: 17 (42.50%)
o Libraries: 30 (34.48%)
o Parks: 65 (35.50%)
o Education: 34 (41.46%)
Problem Statement
Dam SAV]qlNwUV]NlAlNJA_UAvNJApAmplaiUVJJa_mNkqN_JNmV_LN_mN]yiaiq]ApNL
Law_mplNA^ AlNAm :VpU mVT_VœJA_p ialpVa_m aS JlVpVJA] V_SlAmplqJpqlN NxiamNL—
particularly in SD1 and SD5—i]A__V_T Sal N^NlTN_Jy NvAJqApVa_m NAl]y wAl_V_T
mympN^mV_SlAmplqJpqlNUAlLN_V_TA_LLaw_mplNA^LNvN]ai^N_plNTq]ApVa_VmJlVpVJA]
to saving lives and reducing loss.
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A failure or breach of a High Hazard Potential Dam (HHPD) in Los Angeles County
waq]L lNmq]p V_ JApAmplaiUVJ Ja_mNkqN_JNm Sal Law_mplNA^ Ja^^q_VpVNm wVpU pUN
greatest vulnerabilities concentrated in densely populated urban areas. Rapid and
^AmmVvN ŔaaLV_T waq]L ]V\N]y V_q_LApN lNmVLN_pVA] _NVTUIalUaaLm Ja^^NlJVA]
LVmplVJpmA_LV_LqmplVA]|a_NmwVpUV_^V_qpNmpaUaqlmLNiN_LV_Ta_ilaxV^VpyA_L
topography. Critical infrastructure—V_J]qLV_TUamiVpA]mœlNA_Lia]VJNmpApVa_mmJUaa]m
and major transportation corridors—waq]L IN mNvNlN]y V^iAJpNL LVmlqipV_T
N^NlTN_JymNlvVJNmA_LNvAJqApVa_laqpNm3UaqmA_LmaSiNai]NV_J]qLV_Tvq]_NlAI]N
iaiq]ApVa_mmqJUAmpUamNwVpUJJNmmA_Lq_JpVa_A]#NNLm# N]LNl]ylNmVLN_pm
and low-V_Ja^N UaqmNUa]Lm wauld face immediate life-pUlNApN_V_T Ja_LVpVa_m
LVmi]AJN^N_pA_L]V^VpNLAJJNmmpa^NLVJA]JAlNalmUN]pNlJa_a^VJ]ammNmwaq]LIN
Ja^iaq_LNLIyLA^ATNpaqpV]VpVNmV_J]qLV_TiawNlmqImpApVa_mA_LwApNlmympN^m
potentially leaving large swaths of the region without essential services. The sheer scale
aSLNvAmpApVa_Sla^ALA^SAV]qlNNmiNJVA]]yApSAJV]VpVNmmqJUAm:UVppVNl#Allawmal
AmpAVJA^q_LNlmJalNmpUNJlVpVJA]V^ialpA_JNaSJa_pV_qNLlVm\lNLqJpVa_NAl]y
wAl_V_TmympN^mA_LLA^lNUAIV]Vtation efforts.
6.7.8 Data Limitations
A limitation of this AHMP is that planning efforts only covered PW-owned dams in Los
Angeles County. Future mitigation planning should include other dam owners and
operators in Los Angeles County such as the US Army Corps of Engineers. The data on
high-hazard dams reviewed during the 2025 AHMP planning process was generally
suitable for the analysis required. Future opportunities for obtaining additional data to
be considered in the next update to the plan should:
x Incorporate more current information as it becomes available.
x Assess any new or updated EAPs for dams owned by Los Angeles County.
x Identify and review more current structural or condition assessment data to
inform future risk assessments.
x Involve other dam owners within Los Angeles County in future planning efforts.
6.7.9 Impacts
A dam failure in Los Angeles County would have catastrophic and immediate
Ja_mNkqN_JNmSal]VSNilaiNlpyA_LJlVpVJA]V_SlAmplqJpqlNiAlpVJq]Al]yV_pUNLN_mN]y
populated downstream areas. The sudden release of impounded water from a High or
Extremely HVTUA|AlLLA^Jaq]LV_q_LApN_NVTUIalUaaLmwVpUV_^V_qpNmA]]awV_T
]Vpp]Npa_apV^NSalNvAJqApVa_"alNpUA_ lNmVLN_pm]VvNwVpUV_VLN_pVœNLLA^
V_q_LApVa_ |a_Nm ^A_y aS wUa^ AlN V_ maJVA]]y vq]_NlAI]N iaiq]ApVa_m—including
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V_LVvVLqA]mwVpU]V^VpNL^aIV]Vpy]aw-V_Ja^NUaqmNUa]LmA_LiNai]NNxiNlVN_JV_T
homelessness—making rapid evacuation and sheltering especially challenging.
County-owned high hazard potential dams and their locations are listed in Table 6-3.
Inundation maps for County-owned high hazard potential dams are listed in Appendix
A-7.
Critical infrastructure is also at mVT_VœJA_plVm\amiVpA]mœlNmpApVa_m]AwN_SalJN^N_p
SAJV]VpVNm N^NlTN_Jy aiNlApVa_m JN_pNlm mJUaa]m A_L wAmpNwApNlplNAp^N_pi]A_pm
]aJApNL V_ Law_mplNA^ |a_Nm ^Ay IN LA^ATNL al lN_LNlNL V_aiNlAI]N mNvNlN]y
disrupting emergency response and life-sustaining services. Major transportation
laqpNmmqJUAmV_pNlmpApNmlAV]]V_NmA_LAlpNlVA]laALmJaq]LINmqI^NlTNLalwAmUNL
aqpV^iNLV_TlNmJqNA_LlNJavNlyNSSalpmLLVpVa_A]]yiawNlmqImpApVa_m wApNl
LVmplVIqpVa__Npwal\mA_LpN]NJa^^q_VJApVons infrastructure could suffer cascading
SAV]qlNmJa_plVIqpV_TpawVLNmilNALaqpATNmA_Lila]a_TNLlNJavNlyiNlVaLm
The economic consequences of dam failure would be immense. Beyond property
LA^ATN IqmV_Nmm aiNlApVa_m V_ V_q_LApNL AlNAm waq]L UA]p ]NALV_T pa ]amm aS
N^i]ay^N_ppAxlNvN_qNA_LNJa_a^VJAJpVvVpy_LqmplVA]|a_NmNmiNJVA]]ypUamN_NAl
^A[al ŔaaL Ja_trol reservoirs or channels) could potentially release hazardous
^ApNlVA]mVSavNlwUN]^NLiamV_TmNJa_LAlyN_vVla_^N_pA]A_LiqI]VJUNA]pUUA|AlLm
NIlVm AJJq^q]ApVa_ mNLV^N_pApVa_ A_L Ja_pA^V_ApVa_ Jaq]L mNvNlN]y V^iAJp
NJamympN^mwApNlkqA]VpyA_LŔaaLJa_pla]V_SlAmplqJpqlNLaw_mplNA^Ja^i]VJApV_T
both emergency cleanup and long-term environmental recovery.
VvN_pUNmJA]NaSiapN_pVA]V^iAJpmLA^SAV]qlNVmJa_mVLNlNLAmpAI]N]aw-probability
but high-Ja_mNkqN_JNUA|AlLV_!am_TN]Nmaq_pylNkqVlV_TJa_pV_qNLV_vNmp^N_p
V_mplqJpqlA]^VpVTApVa_N^NlTN_JyilNiAlNL_NmmA_LiqI]VJAwAlN_NmmpalNLqJNpUN
severity of its effects.
6.7.10 High Hazard Potential Dams Goals
aA]_UA_JNlNmV]VN_JNAJlammLA^LNIlVmIAmV_V_SlAmplqJpqlNV_J]qLV_TUVTU-
UA|AlLiapN_pVA]LA^mA_LapUNlJlVpVJA]SAJV]VpVNmwVpUV_LA^V_q_LApVa_|a_Nm
aA]Encourage structural reinforcement or lNplaœpmSalATV_TA_Lvq]_NlAI]NLA^m
aA]Ensure all dams/ debris basins have updated Emergency Action Plans (where
applicable) and updated dam inundation mapping consistent with state standards.
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6.7.11 Mitigation and Preparedness
Los Angeles County and state agencies have implemented various mitigation efforts to
reduce the risks associated with dam failures:
x 1plqJpqlA]0NV_SalJN^N_pm4iTlALV_TmiV]]wAymmplN_TpUN_V_TNAlpUN_LA^m
A_LV^i]N^N_pV_TmNVm^VJlNplaœppV_T^NAmqlNm
x Emergency Action Plans (EAPs): Mandated by DSOD for all High and
Extremely High hazard dams to guide evacuation and response efforts.
x Early Warning Systems: ^ilavNL ŔaaL ^a_VpalV_T A_L Aqpa^ApNL A]Nlp
systems to notify at-risk communities in real-time.
6.7.12 High Hazard Potential Dam Prioritization
The risk assessment within the 2025 AHMP considers the county planning area’s
vulnerability and potential impacts related to HHPDs. Mitigation actions and planning
efforts that are related to mitigating long-term vulnerabilities to County-owned HHPDs
will automatically be given a HIGH priority as described in the overall mitigation action
prioritization criteria in Section 7.6. The County Departments responsible for
V^i]N^N_pV_T pUN AmmaJVApNL ^VpVTApVa_ AJpVa_m A]a_T wVpU pUNilValVpy iapN_pVA]
funding saqlJNA_LNxiNJpNLpV^NSlA^NAlN]VmpNLV_1NJpVa_
6.7.13 Summary
Los Angeles County has 90 state-[qlVmLVJpVa_A]LA^mwVpUJ]AmmVœNLAmVTUal
xplN^N]yVTUUA|AlL^NA_V_TpUNVlSAV]qlNJaq]LlNmq]pV_wVLNmilNAL]ammaS]VSNA_L
NJa_a^VJLNvAmpApVa_:UV]NlNTq]ApalyavNlmVTUpUAmV^ilavNLLA^mASNpy ATV_T
infrAmplqJpqlNmNVm^VJpUlNApmA_LV_JlNAmNLmpal^V_pN_mVpylN^AV_ JUA]]N_TNm
a_pV_qNLV_vNmp^N_pV_lNplaœpmNAl]ywAl_V_TmympN^mA_LN^NlTN_Jyi]A__V_TVm
essential to mitigating the risk of catastrophic dam failures.
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6.8 Land Movement
6.8.1 Nature
Land movement refers to the downward
^avN^N_p aS laJ\ maV] al LNIlVm A]a_T A
slope due to gravity. This process can occur
mqLLN_]yalTlALqA]]yavNlpV^NLNiN_LV_T
on contributing factors such as soil
Ja^iamVpVa_ m]aiN mpAIV]Vpy A_L NxpNl_A]
triggers. Land movement encompass a
variety of movement types including
^qLŔawm laJ\SA]]m LNIlVm Ŕawm ]A_L
m]q^im ]A_L mqImVLN_JN A_L maV]
^avN^N_p _ !am _TN]Nm aq_py pUN
diverse topography and geological
formations make certain areas more prone to
land ^avN^N_piAlpVJq]Al]yLqlV_TiNlVaLm
aS V_pN_mN ilNJViVpApVa_ mNVm^VJ AJpVvVpy al
human land-qmN^aLVœJApVa_m
Climate change exacerbates land movement
by increasing the frequency and intensity of
NxplN^N wNApUNl NvN_pm mqJU Am UNAvy lAV_SA]] A_L ŔaaLV_T wUVJUJA_]NALpa
accelerated erosion and heightened landslide risks.
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!A_L^avN^N_paSpN_aJJqlV_Ja_[q_JpVa_wVpUapUNl_ApqlA]UA|AlLmNxAJNlIApV_T
their impact. Some of the primary contributing factors include:
x Seismic ActivityAlpUkqA\NmJA_LNmpAIV]V|Nm]aiNm]NALV_Tpa]A_L^avN^N_p
A_LlaJ\SA]]m3UNSalJNaSmNVm^VJmUA\V_TJA_JAqmNmqLLN_SAV]qlNmiAlpVJq]Al]yV_
areas with pre-existing instability.
x NAvy0AV_SA]]A_L]aaLV_T: The likelihood of land movement increases after
mqJJNmmVvNmpal^m-la]a_TNLalV_pN_mNlAV_SA]]mApqlApNmmaV]lNLqJV_TVpmJaUNmVa_
and triggering slope failures.
x Coastal Erosion:AvNmA_Lmpal^mqlTNNlaLNJaAmpA]J]VSSm]NALV_TpaV_mpAIV]Vpy
A_LNvN_pqA]Ja]]AimNiAlpVJq]Al]yV_AlNAmmqJUAmaq_pyINAJUNmA_LJaAmpA]
Ja^^q_VpVNm^A_yaSwUVJUUAvNilNvVaqm]yNxiNlVN_JNLmVT_VœJA_pNlamVa_
x :V]LœlNm!ammaSvNTNpApVa_LqNpaœlNmlNLqJNmpUNmaV]¯mAIV]VpypalNpAV_^aVmpqlN
making slopes more susceptible to erosion and land movement during subsequent
rain events.
x Burn Scars:V]LœlNIql_mJAlmmVT_VœJA_p]yN]NvApNpUNlVm\aS]A_L^avN^N_pIy
mplViiV_TpUN]A_LaSmpAIV]V|V_TvNTNpApVa_lNAmASSNJpNLIy^A[alœlNmmqJUAmpUN
:aa]mNyVlN
aIJApVlN
lVLTNVlN Apa_VlN A_L
Palisades Fire (2025) have shown increased susceptibility to land movement due to
reduced soil stability and rapid runoff during rainstorms.
6.8.2 Location
Los Angeles County is home to multiple regions susceptible to land movement due to
mpNNim]aiNmq_mpAI]NTNa]aTyA_LwNApUNliAppNl_m3UNA]VSal_VANa]aTVJA]1qlvNy
(CGS) Landslide Susceptibility Map highlights high-risk areas. For a better visual
replNmN_pApVa_aSpUN!A_L"avN^N_pA|AlLwVpUV_pUN!aq_pyi]A__V_TAlNA
please reference Appendix A for maps that show areas that are susceptible to land
movement and recent burn scars.
Potential land movement areas include (but are not limited to):
x Santa Monica Mountains
x San Gabriel Mountains
x Sierra Pelona Mountains
x Baldwin Hills
x Puente Hills
x Palos Verdes Hills
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3UNmN AlNAm AlN iAlpVJq]Al]y vq]_NlAI]N LqN pa pUNVl mpNNi pNllAV_m wNA\ laJ\
Sal^ApVa_m A_L UVmpaly aS m]aiN ^avN^N_pLLVpVa_A]]y Uq^A_AJpVvVpVNm mqJU Am
TlALV_T NxJAvApVa_ A_L Ja_mplqJpVa_ V_ pUNmN lNTVa_m JA_ SqlpUNl LNmpAIV]V|N pUN
Tlaq_LV_JlNAmV_TpUN]V\N]VUaaLaS]A_L^avN^N_plNAmV^iAJpNLIyiAmpwV]LœlNm
\_aw_AmIql_mJAlmAlNA]maUVTU]ymqmJNipVI]Npa]A_L^avN^N_pAmpUN]ammaS
vegetation reduces soil stability and increases erosion risks during heavy rains. This is
particulal]yJa_JNl_V_TV_wV]LœlN-prone areas such as the Santa Monica Mountains and
pUNSaapUV]]maSpUN1A_AIlVN]"aq_pAV_mwUNlNiamp-œlN ]A_L ^avN^N_p UAvN
UVmpalVJA]]yJAqmNLmVT_VœJA_pLA^ATN
6.8.3 Extent
3UNNxpN_paS]A_L^avN^N_pV_!am_TN]NmVmmVT_VœJA_pA_LvAlVNLV_ŔqN_JNLIyVpm
q_VkqNTNa]aTVJA]mNppV_TJJalLV_TpapUN1!A_Lm]VLN1qmJNipVIV]Vpy"Ai
approximately 750 square miles (15.75%) of Los Angeles County fall within high-risk
landslide zones. The highest concentrations of deep-seated landslide susceptibility are
distributed as follows:
Table 6-5 Landslide Susceptibility Map
Area High-0Vm\!A_Lm]VLN?a_Nm
mk^V]Nm
Percentage of Total Land
Area
Los Angeles County 750.02 15.75%
Unincorporated Areas 577.63 18.99%
Supervisorial District 1 17.29 7.02%
Supervisorial District 2 2.73 1.68%
Supervisorial District 3 114.61 26.58%
Supervisorial District 4 105.12 23.89%
Supervisorial District 5 509.31 18.14%
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6.8.4 History
!A_L^avN^N_pUAvNUVmpalVJA]]yJAqmNLmVT_VœJA_pLA^ATNV_!am_TN]Nmaq_py
aSpN_lNmq]pV_TV_ilaiNlpyLNmplqJpVa_V_SlAmplqJpqlNLA^ATNA_LlaALJ]amqlNmThere
UAvNINN__aSNLNlA]LNJ]AlApVa_malmpApNilaJ]A^ApVa_mSalLA^SAV]qlNV_pUN]AmpœvN
years. Some of the most notable events include:
x 1956 – Portuguese Bend Landslide: A massive landslide on the Palos Verdes
Peninsula began in 1956 and remains active today. The movement of land has
LVmi]AJNLUa^NmA_LV_SlAmplqJpqlNUVTU]VTUpV_TpUNlNTVa_¯ma_TaV_TTNa]aTVJ
instability.
x 1994 – #alpUlVLTN AlpUkqA\N-Induced Land movement: The earthquake
plVTTNlNL^alNpUA_^avV_TNvN_pmilV^AlV]yV_pUN1A_pA1qmA_A"aq_pAV_m
A_L1A_AIlVN]"aq_pAV_mJAqmV_TNxpN_mVvNlaALA_LmplqJpqlA]LA^ATN
x March 1995 – -AJVœJ -A]VmALNm !A_Lm]VLN: Heavy rains weakened the coastal
I]qSSm]NALV_TpaA-foot-wVLNJa]]AimNpUApIqlVNLiAlpaSpUN-AJVœJaAmp
Highway under 30 feet of debris.
x March 2005 – Sunset Mesa Landslide: A slope failure near Malibu caused over
JqIVJyAlLmaSLNIlVmpaI]aJ\laALwAymA_LLA^ATNilaiNlpy
x July 2023 – -NAlplNN!A_N!A_L"avN^N_p0a]]V_TV]]mmpApNm : A sudden
m]aiNSAV]qlNlNmq]pNLV_pUNLVmi]AJN^N_paSUa^NmwUVJUwNlNlNL-tagged due
to structural instability.
x September 2024 – JJN]NlApNL!A_L"avN^N_pV_0A_JUa-A]am9NlLNm: A
mVT_VœJA_pV_JlNAmNV_]A_L^avN^N_pwVpUJNlpAV_AlNAmmUVSpV_TqipaSaqlV_JUNm
iNlwNN\pawAlLpUNaJNA_pUlNApN_V_TlaALmA_LavNl lNmVLN_pVA]ilaiNlpVNm
6.8.5 Types of Land Movement
Debris Flow"qLŔaw1aV]"avN^N_p
NIlVmŔawV_va]vNmpUNlAiVL^avN^N_paSALN_mN^VxpqlNaSwApNlmaV]laJ\A_L
alTA_VJ ^ApNlVA] Law_ A m]aiN 3UVm ilaJNmm JA_ UAvN mVT_VœJA_pV^iAJpma_
]A_LmJAiNmNJamympN^mA_LUq^A_V_SlAmplqJpqlN
NIlVmŔawmAlNJUAlAJpNlV|NLIypUNVlŔqVL-like behavior and ability to transport large
aI[NJpmmqJUAmIaq]LNlmA_LplNNm3UNyJA_plAvN]ApUVTUmiNNLm^A\V_TpUN^UVTU]y
LNmplqJpVvN3UNJa^iamVpVa_aSALNIlVmŔawJA_vAlyIqpVppyiVJA]]yV_J]qdes:
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x Water: A crucial component that facilitates movement.
x 1aV]A_L0aJ\3UNmNilavVLNpUNIq]\aSpUN^ApNlVA]V_ALNIlVmŔaw
x Organic Material: Includes vegetation and other natural debris that get caught in
pUNŔaw
"qLŔawm AlN lAiVLmovements of water-saturated earth materials that can cause
mVT_VœJA_pLA^ATNpaIapU_ApqlA]N_vVla_^N_pmA_LUq^A_mNpp]N^N_pm"qLŔawm
AlNJUAlAJpNlV|NLIypUNVlŔqVL-]V\N^apVa_wUVJUaJJqlmwUN_maV]laJ\mA_LLNIlVm
become saturated with water. 3UVmmApqlApVa_lNLqJNmpUNSlVJpVa_INpwNN_iAlpVJ]Nm
A]]awV_TpUN^Ammpa^avNLaw_UV]]q_LNlpUNV_ŔqN_JNaSTlAvVpy NyJUAlAJpNlVmpVJm
include:
x 1iNNLA_L9a]q^N"qLŔawmJA_plAvN]ApmiNNLmqipa ^V]NmiNlUaqlA_L
JA_JAlly]AlTNva]q^NmaS^ApNlVA]V_J]qLV_TlaJ\mplNNmA_LNvN_vNUVJ]Nm
x Consistency: 3UNJa_mVmpN_JyaSA^qLŔawJA_vAlySla^ApUVJ\vVmJaqmm]qllypa
AwApNlyŔaw3UVmLNiN_Lma_pUNilaialpVa_aSwApNlpama]VL^ApNlVA]m
x Path: "qLŔawmpyiVJA]]ySa]]awNxVmpV_TLlAV_ATNiAppNl_mmqJUAmlVvNlJUA__N]m
A_LvA]]NymIqpJA_A]maJAlvN_NwiApUm]NALV_Tpaq_ilNLVJpAI]NA_LwVLNmilNAL
damage.
1aV]^avN^N_pVmA_ApqlA]ilaJNmmpUApmVT_VœJA_p]yV^iAJpmpUNN_vVla_^N_pA_L
human activities. It involves the displacement of soil particles due to various natural and
human caused factors. Key characteristics include:
x Landslides: %SpN_ aJJqllV_T V_ UV]]y AlNAm ]A_Lm]VLNm V_va]vN pUN Law_wAlL
movement of rock and soil. They can be sudden and fast-^avV_T^A\V_TpUN^
particularly dangerous.
x Soil Creep: 3UVmVmAm]awA_LTlALqA]^avN^N_paSmaV]Law_Am]aiNaSpN_
q__apVJNLq_pV]mVT_VœJA_pLA^ATNaJJqlm
x 1aV]!VkqNSAJpVa_qlV_TA_NAlpUkqA\NmApqlApNLmaV]JA_pN^ialAlV]y]amNVpm
mplN_TpUA_LINUAvN]V\NA]VkqVLJAqmV_TmplqJpqlNmpamV_\alpV]p
Causes
_!am_TN]Nmaq_pymNvNlA]SAJpalmJa_plVIqpNpapUNaJJqllN_JN aS LNIlVm
Ŕawm^qLŔawmmaV]^avN^N_p
x NAvy0AV_SA]]A_L1pal^vN_pm_pN_mNA_Lila]a_TNLlAV_SA]]aSpN_AmmaJVApNL
wVpUmpal^mJA_mApqlApNpUNmaV]lNLqJV_TVpmmpAIV]VpyA_LplVTTNlV_TLNIlVmŔawm
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3UNlNTVa_µm"NLVpNllA_NA_J]V^ApNwVpUwNpwV_pNlmA_LLlymq^^NlmJlNApNm
conditions conducive to such events.
x :V]LœlNm!am_TN]Nmaq_pySlNkqN_p]yNxiNlVN_JNmwV]LœlNmwUVJUJA_Iql_
and destabilize vegetation that normally helps hold soil in place. The loss of
vNTNpApVa_V_JlNAmNmpUNlVm\aSmaV]NlamVa_A_LJa_mNkqN_p]yLNIlVmŔawmLqlV_T
subsequent rainfalls.
x Steep Terrain: 3UN Jaq_pyµm ^aq_pAV_aqm pNllAV_ V_J]qLV_T AlNAm ]V\N aq_py
^aq_pAV_aqmAlNAmVmiAlpVJq]Al]yila_NpaLNIlVmŔaw3UNmpNNim]aiNmSAJV]VpApN
the rapid movement of debris downhill.
x Soil Composition: NlpAV_maV]pyiNmmqJUAmJ]Ay-lVJUmaV]mJA_INJa^NUVTU]y
q_mpAI]NwUN_mApqlApNLwVpUwApNl^A\V_TpUN^^alNmqmJNipVI]NpaLNIlVmŔaw
x Human Activity: 4lIA_LNvN]ai^N_plaALJa_mplqJpVa_A_LLNSalNmpApVa_JA_
A]pNl_ApqlA]]A_LmJAiNmA_LNxAJNlIApNJa_LVpVa_mpUAp]NALpaLNIlVmŔaw
x Seismic Activity: !am_TN]Nmaq_pyVmmVpqApNLV_AUVTU]yAJpVvNmNVm^VJ|a_N
^A\V_T Vp ila_N pa NAlpUkqA\Nm 1NVm^VJ AJpVvVpy JA_ ]NAL pa maV] ]VkqNSAJpVa_
]A_Lm]VLNmA_LTlaq_LmUA\V_TA]]Ja_plVIqpV_TpamaV]LVmi]AJN^N_p
!A_L1qImVLN_JN
Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to
various natural and human-V_LqJNLSAJpalm3UVmUA|AlLJA_UAvNmVT_VœJA_pV^iAJpma_
pUNN_vVla_^N_pV_SlAmplqJpqlNA_LJa^^q_VpVNm
lNLqJpVa_V_]A_LN]NvApVa_Vma_NaSpUN^amp_apVJNAI]NSNApqlNmaS]A_LmqImVLN_JN
]NALV_TpamVT_VœJA_pJUA_TNmV_pUN]A_LmJAiN3UVmiUN_a^N_a_JA_aJJqlLqNpa
_ApqlA]ilaJNmmNmmqJUAmpUNLVmma]qpVa_aS]V^Nmpa_NAmwN]]AmUq^A_AJpVvVpVNmlike
pUN NxJNmmVvN NxplAJpVa_ aS Tlaq_LwApNl aV] al _ApqlA] TAm qlpUNl^alN ]A_L
mqImVLN_JNV_JlNAmNmpUNlVm\aSŔaaLV_TINJAqmNpUN]awNlN]NvApVa_JA_]NALpaiaal
LlAV_ATNA_LwApNlAJJq^q]ApVa_mpUNTlaq_LmV_\mVpaSpN_lNmq]pmV_pUNSal^Apion
aSLNilNmmVa_mœmmqlNmA_LmV_\Ua]NmwUVJUJA_LlA^ApVJA]]yA]pNlpUNTNaTlAiUyA_L
infrastructure of the area.
x Depressions: Are sunken or low-]yV_TAlNAma_pUNAlpU¯mmqlSAJNaSpN_Sal^NLIy
natural or man-made processes.
x Fissures: lNA]a_T_AllawJlAJ\al]V_NAlaiN_V_TV_pUNAlpU¯mJlqmp
x 1V_\Ua]NmAre holes in the ground causes by the collapse or sinking of surface
material into an underlying void.
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Causes
x laq_LwApNlxplAJpVa_One of the primary causes of land subsidence in Los
Angeles County is the excessive extraction of groundwater. As water is pumped out
aSq_LNlTlaq_LAkqVSNlmpUNTlaq_LAIavNJA_mV_\almNpp]N]NALV_T pa
subsidence.
x %V]A_LAmxplAJpVa_The removal of oil and natural gas from beneath the earth's
surface also contributes to land subsidence. This extraction can create voids and
lNLqJNilNmmqlNV_mqIpNllA_NA_]AyNlmJAqmV_TpUNTlaq_LpamV_\
x Natural Soil Compaction: %vNlpV^N_ApqlA]ilaJNmmNmmqJUAmmaV]Ja^iAJpVa_
can lead to gradual subsidence. In areas with loose or q_Ja_ma]VLApNLmaV]mpUN
wNVTUpaSavNl]yV_T^ApNlVA]mJa^iAJpmpUNTlaq_LlNmq]pV_TV_A]awNlV_TaSpUN
land surface.
Rock Falls
Rock falls are a natural geological phenomenon where rock fragments break free from
a steep slope or cliff and tumble downward. These events can range from small
iNII]NmLVm]aLTV_Tpa^AmmVvNIaq]LNlmJlAmUV_TLaw_wVpUmVT_VœJA_p SalJN A_L
impact.
Rock falls are characterized by:
x Speed and Suddenness: 0aJ\ SA]]m aJJql kqVJ\]y A_L wVpUaqp ^qJU wAl_V_T
making them particularly dangerous.
x 9AlVNL1V|NmThe size of the falling material can range from small pebbles to large
Iaq]LNlmV^iAJpV_TpUNmNvNlVpyaSpUNNvN_p
x Path Predictability: :UV]NpUNV_VpVA]plVTTNliaV_pVmaSpN_VLN_pVœAI]NpUNiApUaS
descent can be unpredictable due to varying terrain and obstacles.
Causes
The primary causes of rock falls include:
x Weathering and Erosion: %vNlpV^NwNApUNlV_TilaJNmmNmmqJUAmSlNN|N-thaw
JyJ]NmJUN^VJA]wNApUNlV_TA_LpUNAJpVa_aSwApNlJA_wNA\N_laJ\mplqJpqlNm
lamVa_JA_q_LNl^V_NpUNIAmNaSm]aiNm^A\V_TlaJ\m^alNmqmJNipVI]NpaSA]]V_T
x Seismic Activity: Los Angeles County is located in a seismically active region.
AlpUkqA\NmJA_LVm]aLTNlaJ\mSla^J]VSSmA_LmpNNim]aiNmplVTTNlV_TlaJ\SA]]m
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x NAvy0AV_SA]]_pN_mNalila]a_TNLlAV_SA]]JA_mApqlApNpUNTlaq_LV_JlNAmV_T
the weight and pressure on rock faces. This saturation can lead to the loosening and
collapse of rocks.
x Human Activity: a_mplqJpVa_^V_V_TA_LapUNlUq^A_AJpVvVpVNmJA_LNmpAIV]V|N
rock formations. The vibrations from heavy machinery and blasting can initiate rock
falls.
6.8.6 Probability
!A_Lm]VLNmA_LapUNl]A_L^avN^N_pNvN_pmUAiiN_V_!am_TN]Nmaq_pySAVl]yaSpN_
NmiNJVA]]yASpNlUNAvylAV_alV_AlNAmpUAplNJN_p]yUALwV]LœlNmalAlNila_Npam]VLV_T
x 1^A]]]A_Lm]VLNm]V\NLNIlVmŔawm AlN^amp]V\N]yLqlV_TyNAlmwVpUUNAvylAV_
NmiNJVA]]y]#V`ayNAlm3UNmNUAiiN_NvNlypayNAlmpUNlNVmÈpa È
chance each year during those cycles.
x In high-lVm\|a_Nm]V\NmpNNi^aq_pAV_m]aiNmwVpUAUVmpalyaS^avN^N_p
probability is 1–ÈJUA_JNiNlyNAlNmiNJVA]]ySa]]awV_T^q]pV-year wet periods
al^A[alwV]LœlNm
x Some areas of the County have been experiencing continuous sliding.
6.8.7 Vulnerability
!A_L ^avN^N_p iamN lVm\m pa ]VSN ilaiNlpy A_L NmmN_pVA] V_SlAmplqJpqlN3UN
THIRA projects that approximately 1.2 million residents in Los Angeles County could
be directly or indirectly affected by land movement. The most at-risk populations
include:
x 0NmVLN_pmaSUV]]mVLNA_LJA_ya_Ja^^q_VpVNmmqJUAm"A]VIq3aiA_TAA_LpUN
Palos Verdes Peninsula.
x Homeowners in coastal bluff areas that are facing erosion-driven slope failures.
x a^^q_VpVNmV_wV]LœlNIql_mJAlAlNAmwUNlNpUN]ammaSvNTNpApVa_V_JlNAmNm
landslide probability during heavy rains.
x The Access and Functional Needs (AFN) community who may face challenges in
evacuating or leaving landslide-prone areas.
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Contextual Overview
Los Angeles County’s diverse topography includes many hillside communities
susceptible to deep-mNApNL]A_Lm]VLNmNmiNJVA]]yASpNlwV]LœlNalUNAvylAV_3UNmN
hazards can isolate Ja^^q_VpVNmLA^ATNilaiNlpyA_LLVmlqip]VSN]V_Nm
Extent of Exposure
x Total Area Exposed : 284.57 sq mi
x Supervisorial Districts (SD) Impacted:
o SD5: 151.96 sq mi (5.41%)
o SD3: 90.23 sq mi (20.93%)
o SD4: 25.94 sq mi (12.20%)
o SD1: 13.77 sq mi (3.90%)
o SD2: 2.68 sq mi (0.74%)
x Critical Facilities Affected:
o Fire Department: 41 (12.17%)
o Public Works: 32 (13.91%)
o Health Services: 12 (18.46%)
o Public Health: 4 (10.00%)
o Libraries: 9 (10.34%)
o Parks: 27 (14.92%)
o Education: 8 (9.76%)
Problem Statement
!A_Lm]VLNmiamNAmNlVaqmlVm\paUV]]mVLNJa^^q_VpVNmA_LAJJNmmlaqpNmNmiNJVA]]yV_
AlNAmlNJavNlV_TSla^wV]LœlNqllN_pLNvN]ai^N_pA_LlaALV_SlAmplqJpqlN^Ay_ap
be resilient against slope failure. Mitigation actions should include slope stabilizApVa_
pAlTNpNLIqyaqpmallN]aJApVa_mA_LNAl]ywAl_V_TmympN^m
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6.8.8 Impacts
Los Angeles County's diverse landscape and dense population make it highly
mqmJNipVI]NpapUNNSSNJpmaS]A_L^avN^N_pASSNJpV_TJlVpVJA]V_SlAmplqJpqlNA_LlAVmV_T
mVT_VœJA_pNJa_a^VJmaJVA]A_LmASNpyJa_JNl_m
3lA_mialpApVa_#Npwal\m
!am_TN]Nmaq_pyµmNxpN_mVvNplA_mialpApVa__Npwal\VmvVpA]SalLAV]yJa^^qpNm
TaaLmplA_mialpA_LN^NlTN_JymNlvVJNm!A_L^avN^N_pJA_mNvNlN]yV^iAJppUNmN
systems:
x 0aALA^ATNAqmNmJ]amqlNmhazardous driving conditions and costly repairs
AmmNN_A__qA]]ya_-AJVœJaAmpVTUwAy- A_L^A_yapUNl]aJA]laALm
x Bridge Compromise SSNJpm mplqJpqlA] V_pNTlVpy _NJNmmVpApV_T J]amqlNm A_L
expensive reconstructions.
x Public Transit Disruptions^iAJpmplAV_plAJ\mA_LIqmlaqpNm]NALV_TpaLN]Aym
and service interruptions.
x 0AV] 1ympN^m3lAJ\ ^VmA]VT_^N_p JA_ JAqmN LN]Aym A_L iapN_pVA] LNlAV]^N_pm
affecting both passenger and freight lines.
Water Supply Systems
The county's water delivery system is complex and vulnerable to land movement:
x Compromised Pipelines !NALm pa lqipqlNm al ]NA\m LVmlqipV_T mqii]y A_L
requiring major repairs.
x 0NmNlvaVl^iAJp: Landslides can affect water quality and storage capacity.
Energy Infrastructure
!A_L^avN^N_piamNmlVm\mpa!am_TN]Nmaq_pyµmN_NlTyV_SlAmplqJpqlNV_J]qLV_T
x ]NJplVJA] lVL 9q]_NlAIV]VpVNmLand movement can damage power lines and
mqImpApVa_mJAqmV_TaqpATNm
x Am-ViN]V_N0Vm\m1aV]mUVSpmJA_lNmq]pV_TAm]NA\malNxi]amVa_mN_LA_TNlV_T
safety.
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Communication Systems
0N]VAI]NJa^^q_VJApVa_VmJlVpVJA]A_L]A_L^avN^N_pJA_LVmlqip
x Telecommunication Towers: Structural damage can impair cellular and internet
services.
x Underground Cables: AlpUmUVSpmJA_LA^ATNJAI]NmASSNJpV_TJa__NJpVvVpy
Emergency Services Facilities
x Hospitals and Fire Stations: mmN_pVA] Sal N^NlTN_Jy lNmia_mN Iqp mplqJpqlA]
LA^ATNJaq]LV^iNLNaiNlApVa_mq_LNlmJalV_TpUN_NNLSallNmV]VN_pJa_mplqJpVa_
and strategic planning.
Economic Impacts
x Infrastructure Damage: !NALmpaJamp]ylNiAVlmA_L^AV_pN_A_JNaSlaALmIlVLTNm
and buildings.
x Property Loss: a^Naw_Nlm SAJN œ_A_JVA] ]ammNm LqN pa ilaiNlpy LA^ATN al
devaluation.
Environmental Impacts
x Ecosystem Disruption: Soil movement can lead to habitat loss A_LASSNJp]aJA]ŔalA
and fauna.
x Increased Pollution: lamVa_JA_lNmq]pV_mNLV^N_plq_aSSLNTlALV_TwApNlkqA]Vpy
in rivers and oceans.
For a better visual representation of the Land Movement Hazard within the LA County
i]A__V_T AlNA i]NAmN lNSNlN_JN iiN_LVx for maps that show areas that are
susceptible to land movement and recent burn scars.
6.8.9 Mitigation Strategies
3alNLqJNpUNV^iAJpaS]A_L^avN^N_p!am_TN]Nmaq_pyUAmV^i]N^N_pNLmNvNlA]
^VpVTApVa_A_LilNiAlNL_NmmmplApNTVNmV_J]qLV_T
x !A_L4mNA_LNvN]ai^N_p0NTq]ApVa_mRestricting development in high-risk
landslide zones to prevent new structures from being built on unstable terrain.
x _SlAmplqJpqlN 0NmV]VN_JNReinforcing existing infrastructure through slope
mpAIV]V|ApVa_ila[NJpmlNpAV_V_TwA]]mA_LV^ilavNLLlAV_ATNmympN^m
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x 1pAIV]V|ApVa_ 0NTq]ApVa_mImplementing stricter grading and excavation
regulations to minimize the destabilization of slopes.
x Public Awareness Campaigns: _UA_JV_T ]A_Lm]VLN NAl]y _apVœJApVa_m Iy
monitoring potential movement areas and precipitation thresholds.
x Evacuation Planning: Developing evacuation plans for at-lVm\ Ja^^q_VpVNm
ensuring residents receive timely alerts and clear guidance.
x Public Education: Conducting public education campaigns to inform residents
about recognizing landslide warning signs and preparedness measures.
x Operational Area Coordination_JlNAmV_TJaalLV_ApVa_AJlammmpApNSNLNlA]A_L
%SœJN aS ^NlTN_Jy "A_ATN^N_p aSœJVA]m wVpU ]aJA] [qlVmLVJpVa_m pa V^ilavN
forecasting and response efforts.
6.8.10 Summary
!A_L^avN^N_plN^AV_mAmVT_VœJA_pUA|AlLV_!am_TN]Nmaq_pyiAlpVJq]Al]yV_
mpNNiA_LJaAmpA]lNTVa_m3UN-A]am9NlLNm-N_V_mq]A1A_pA"a_VJA"aq_pAV_mA_L
1A_AIlVN]"aq_pAV_mAlNA^a_TpUN^ampvq]_NlAI]NAlNAmwith climate change and
human activities exacerbating risks. By implementing land-qmN lNTq]ApVa_m
V_SlAmplqJpqlNlNV_SalJN^N_pmA_LN^NlTN_JylNmia_mNV^ilavN^N_pmpUNaq_pyJA_
enhance resilience and reduce losses in the future. Local governments and
communities must actively monitor and manage contributing factors to effectively
mitigate the impacts of land subsidence.
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6.9 Tsunami
6.9.1 Nature
This section characterizes tsunamis as
high-N_NlTy ]a_T-wavelength ocean
waves generated primarily by
mVT_VœJA_p aSSmUalN mNVm^VJ NvN_pm
(such as subduction zone
NAlpUkqA\Nm mqI^AlV_N ]A_Lm]VLNm
or volcanic eruptions. In the context of
!am _TN]Nm aq_py pmq_A^Vm
represent a relatively infrequent but
potentially high-impact hazard that
could produce rapid coastal
inundation and surge impacts.
Characteristics:
x 3lVTTNlNL^AV_]yIyLVmpA_p]AlTN-
magnitude seismic events.
x Features long wavelengths and prolonged arrival times.
x AiAI]NaSilaLqJV_TlAiVLLNNiV_q_LApVa_A]a_T]aw-lying coastal areas.
x _mq^^Alypmq_A^VmAlNLy_A^VJ_ApqlA]iUN_a^N_AwVpUpUNiapN_pVA]paJAqmN
mqLLN_JaAmpA]ŔaaLV_TA_LLA^ATNVSAplVTTNlV_TNvN_paJJqlm
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6.9.2 Location
3UN qiLApNL pmq_A^V UA|AlL ilaœ]N SaJqmNm a_ pUN JaAmpA]areas of Los Angeles
County. The new zone map—developed using enhanced modeling techniques and
updated coastal geomorphology data—UVTU]VTUpmAlNAmA]a_TpUN-AJVœJmUalN]V_NpUAp
AlNAplVm\3UNmNV_J]qLNlNTVa_mAL[AJN_ppapUN!am_TN]Nm
AmV_iAlpmaS!ang
NAJU1A_pA"a_VJA
AyA_LapUNl]aw-elevation coastal zones.
For a better visual representation of Tsunami Inundation zones within the LA County
i]A__V_TAlNAi]NAmNlNSNlN_JNiiN_LVxAfor A¬3mq_A^V_q_LApVa_lNAmap.
Important Details:
x Coastal segments from the western margins of the Los Angeles Basin extending to
the border with Orange County.
%vNlA]]pUNcoastal areas aS!am_TN]Nmaq_pycontaining our communities and
infrastructureface heightened exposure.
6.9.3 Extent
4mV_T pUN ]ApNmp UyLlaLy_A^VJ A_L V_q_LApVa_ ^aLN]V_T pUN qiLApNL pmq_A^V
inundation (zone)^AiilavVLNmAlNœ_NLvVNwaSpUNNxpN_paSiapN_pVA]ŔaaLV_T3UN
^AiV]]qmplApNmUawpmq_A^VwAvNmJaq]LilaiATApNV_]A_LmUawV_T lNvVmNL
boundaries that account for current sea-level conditions and future sea-level rise
projections.
Highlights:
x _q_LApVa_LNipUmA_LlNAJUUAvNINN_lNJA]Jq]ApNLwVpUma^NAlNAmiapN_pVA]]y
experiencing water levels up to several feet in depth.
x 3UNV_]A_LlNAJUaSŔaaLV_TvAlVNmIy]aJA]paiaTlAiUywVpUŔAp]aw-lying areas
showing the greatest potential for impacts^iAJpNLAlNAmV_J]qLNIqpAlN_ap
]V^VpNLpa!a_T
NAJU3UNialpmaS!a_T
NAJUA_L!am_TN]Nm"AlV_ALN]0Ny
Venice and Santa Monica.
x lVpVJA]V_SlAmplqJpqlNwVpUV_pUNqiLApNL|a_NmUAmINN_VLN_pVœNLpailValVpV|N
mitigation and evacuation routes for planning.
_NmmN_JNpUNNxpN_paSpmq_A^VV^iAJpmVm_aw^AiiNL^alNilNJVmN]yaSSNlV_T]aJA]
decision-^A\NlmAJ]NAlNlvVNwaSiapN_pVA]ŔaaLV_TLNipUmA_LLVmpA_JNmV_]A_L.
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6.9.4 History
VmpalVJA]]ymVT_VœJA_ppmq_A^VNvN_pmV_pUN!am_TN]NmlNTVa_AlNlAlNpUaqTU
distant seismic events (for example: the 1960 Chilean tsunamialpUN^amplNJN_p
Tonga tsunami) have been known to produce measurable impacts. Historical records
combined with geological studies indicate that while tsunamis have occurred in the
iAmppUNVlSlNkqN_JyVm]awJa^iAlNLpaapUNlUA|AlLmawNvNlpUNlNTVa_¯milaxV^Vpy
to major tectonic boundaries necessitates ongoing vigilance.
Historical Context:
x Past events have been sporadic but can serve as valuable lessons for preparedness.
x VmpalVJA] V_q_LApVa_ lNJalLm A_L mNLV^N_p mpqLVNm Ja_œl^ pUAppmq_A^Vm UAvN
reached the Los Angeles coast in prehistory.
x Lessons learned from past minor events underscore the importance of maintaining
updated hazard maps.
3UqmwUV]NUVmpalVJA]pmq_A^VNvN_pmAlNV_SlNkqN_ppUNyilavVLNAJlVpVJA]Ja_pNxpSal
understanding future risks and guiding preparedness measures. There have been no
SNLNlA]LNJ]AlApVa_malmpApNilaJ]A^ApVa_mSalpmq_A^VV_pUN]AmpœvNyNAlm
6.9.5 Probability
The probability of a tsunami affecting Los Angeles County is generally low when
Ja^iAlNL pa ^alN SlNkqN_p UA|AlLm ]V\N NAlpUkqA\Nm al ŔaaLm #NvNlpUN]Nmm pUN
potential for a distance source pmq_A^VTN_NlApNLIyALVmpA_plarge seismic event
remains a realistic risk. Updated probabilistic assessments—incorporating recent
seismic data and tsunami modeling V_LVJApNpUApwUV]NpUNavNlA]]]V\N]VUaaLVm]awpUN
consequences in the event of a tsunami can be severe.
Probability Considerations:
x Low annual probability but high consequence if an event occurs !am_TN]Nm
County has about a 2% annual chance.
x Distance source events from subduction zones across the ocean contribute most to
the risk.
x Continuous monitoring and updated modeling are essential to reassess the risk
over time.
x _mq^^AlypUNilaIAIV]VpyaSApmq_A^VlN^AV_m]awIqpLqNpapUNiapN_pVA]Sal
high-V^iAJpaqpJa^NmVpwAllA_pmJa_pV_qaqmmpqLyA_LilNiAlNL_Nmm
County of Los Angeles
All-Hazards Mitigation Plan
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6.9.6 Vulnerability
aAmpA]vq]_NlAIV]VpyV_!am_TN]Nmaq_pyVmmVT_VœJA_p]yV_ŔqN_JNLIySAJpalmmqJU
Am qlIA_ LN_mVpy ]aw-N]NvApVa_ pNllAV_ ATV_T V_SlAmplqJpqlN A_L maJVa-economic
conditions. The updated tsunami zone map now better delineates areas where these
vulnelAIV]VpVNmAlN^ampila_aq_JNLUVTU]VTUpV_TJa^^q_VpVNmpUAp^AyUAvN]V^VpNL
evacuation routes and fewer resources to recover from rapid inundation. Iaqp
iNai]N]VvNV_iAlpmaS!am_TN]Nmaq_pypUApJaq]LINŔaaLNLIyApmq_A^V"A_y
people a]mawal\V_pUNmNJaAmpA]AlNAmA_LAlaq_Lq_UaqmNLV_LVvVLqA]m]VvN
pUNlN^A\V_TpUN^NmiNJVA]]yAplVm\INJAqmNpUNy^Ay_apUAvNNAmyAJJNmmpamUN]pNl
or transportation.
3aqlVm^ALLmNvN_^alNiNai]NpapUNmNAlNAmNmiNJVA]]yLqlV_TIqmywNN\N_Lmal
Ua]VLAym-]AJNm]V\N1A_pA"a_VJAJA_mNNqipavVmVpalmALAyLqlV_TiNA\
times. This makes evacuating harder if a tsunami warning is issued. Roads near the
coast ca_kqVJ\]yINJa^NJlawLNLA_LvVmVpalm^Ay_ap\_awpUNINmpwAypa]NAvN
3lASœJJaq]Lm]awLaw_N^NlTN_Jyi]A_mmaVp¯mV^ialpA_ppaUAvNJ]NAlmVT_mNAl]y
wAl_V_TmA_LTaaLplASœJJa_pla]paUN]iiNai]NTNppamASNpykqVJ\]y
Factors:
x High population density in low-lying coastal areas.
x lVpVJA]V_SlAmplqJpqlNNTUamiVpA]mqpV]VpVNm ialpmA_LmUViiV_T transportation
networks) located within the inundation zones.
x Socio-economic and language barriers that may hinder effective emergency
response.
x Limited natural barriers in some coastal segments.
x Vulnerable communities include those with high population densities and critical
infrastructure near the coast.
4]pV^ApN]ypUNvq]_NlAIV]VpyaSpUNlNTVa_VmJa^iaq_LNLIyIapUiUymVJA]NxiamqlNm
A_LmaJVA]SAJpalmq_LNlmJalV_TpUN_NNLSalpAlTNpNL^VpVTApVa_NSSalpm
Contextual Overview
aAmpA]Ja^^q_VpVNmV_!am_TN]Nmaq_pyV_J]qLV_TialpmA_LpaqlVmp|a_NmAlNAp
risk from tsunamis. These rare but highly destructive events can inundate coastal
infrastructure with little warning.
County of Los Angeles
All-Hazards Mitigation Plan
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Extent of Exposure
x Total Area Exposed : 32.89 sq mi
x Supervisorial Districts (SD) Impacted:
o SD4: 15.83 sq mi (7.43%)
o SD3: 12.59 sq mi (2.92%)
o SD2: 2.03 sq mi (0.56%)
x Critical Facilities Affected:
o Fire Department: 16 (4.75%)
o Public Works: 9 (3.91%)
o Health Services: 3 (4.62%)
o Public Health: 1 (2.50%)
o Libraries: 5 (5.75%)
o Parks: 13 (7.26%)
o Education: 3 (3.66%)
Problem Statement
3mq_A^Vm JA_ JAqmN lAiVL A_L JApAmplaiUVJ JaAmpA] ŔaaLV_T :VpU JlVpVJA] JaAmpA]
V_SlAmplqJpqlNA_LlNmVLN_pVA]AlNAmNxiamNLNmiNJVA]]yV_1A_L1pUNlNVmA_NNL
SallaIqmpNvAJqApVa_i]A__V_TvNlpVJA]NvAJqApVa_mUN]pNlmA_LJa^^q_VpyaqplNAJU
to enhance preparedness and reduce vulnerability.
6.9.7 Impacts
1Uaq]L A pmq_A^V aJJql pUN iapN_pVA] V^iAJpm a_ !am _TN]Nm aq_py Jaq]L IN
extensive. Parts of Los Angeles County that could be impacted by a Tsunami are Marina
N]0Ny-alpaS!am_TN]Nm-alpaS!a_T
NAJUA_LapUNlbeach communities in low
lying areas. 3UNqiLApNLV^iAJpAmmNmm^N_pmlNŔNJpiammVI]NmJN_AlVamlA_TV_TSla^
mVT_VœJA_pilaiNlpyLA^ATNpa]ammaS]VSNA_L]a_T-term economic disruption. The new
zone map aids in quantifying these impacts by providing detailed inundation depths
and spatia]NxpN_pmpUNlNIyA]]awV_TSalINppNllVm\Ja^^q_VJApVa_A_Li]A__V_T
County of Los Angeles
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Potential Impacts:
x 1NvNlNŔaaLV_TaSJaAmpA]V_SlAmplqJpqlNA_LlNmVLN_pVA]AlNAm
x VmlqipVa_aSplA_mialpApVa_qpV]VpymNlvVJNmA_LN^NlTN_JylNmia_mNaiNlApVa_m
x Ja_a^VJ]ammNmV_\NymNJpalmmqJUAmpaqlVm^mUViiV_TA_L]aJA]Ja^^NlJN
x 1aJVA] V^iAJpm V_J]qLV_T LVmi]AJN^N_p ]amm aS ]VvN]VUaaLm A_L JUA]]N_TNm V_
emergency sheltering.
_mUalppUNiapN_pVA]V^iAJpmaSApmq_A^VAlNSAl-lNAJUV_T _NJNmmVpApV_T laIqmp
^VpVTApVa_NvAJqApVa_A_LlNJavNlyi]A__V_Tpa^V_V^V|NUAl^
For a better visual representation of Tsunami Inundation zones within the LA County
i]A__V_TAlNAi]NAmNlNSNlN_JNiiN_LVx for A¬3mq_A^V_q_LApVa_lNA^Ai.
6.9.8 Summary
The updated tsunami section for the 2025 AHMP V_JalialApNm pUN ]ApNmp mJVN_pVœJ
œ_LV_TmA_L^AiiV_TpNJU_VkqNmpailavVLNA^alNilNJVmNq_LNlmpA_LV_TaSpmq_A^V
lVm\m V_ !am_TN]Nm aq_py
y V_pNTlApV_T A_ qiLApNL V_q_LApVa_ |a_N ^Ai pUN
lNvVmVa_ J]AlVœNm pUN miApVA] NxpN_p aS iapN_pVA] ŔaaLVng and highlights the
vulnerabilities in coastal communities. This comprehensive update is designed to
guide decision-^A\NlmV_N_UA_JV_TilNiAlNL_NmmpAlTNpV_T^VpVTApVa_mplApNTVNmA_L
strengthening community resilience.
Ny3A\NAwAym
x Nature: Tsunamis are infrequent but high-energy events capable of rapid coastal
inundation.
x Location & Extent: 3UNqiLApNL|a_N^AiVLN_pVœNmvq]_NlAI]NJaAmpA]AlNAmwVpU
lNvVmNLV_]A_LŔaaLNxpN_pm
x History & Probability: VmpalVJA]NvN_pmAlNlAlNUawNvNldistance events remain
a realistic risk.
x 9q]_NlAIV]Vpy Ë ^iAJpm High population density and critical infrastructure in
JaAmpA]|a_NmA^i]VSylVm\wVpUiapN_pVA]SalmNvNlNNJa_a^VJA_LmaJVA]LVmlqipVa_
3UVmqiLApNLmNJpVa_VmV_pN_LNLpamNlvNAmAJlVpVJA]paa]Salia]VJy^A\NlmN^NlTN_Jy
^A_ATNlmA_LJa^^q_VpympA\NUa]LNlmAmpUNywal\paTNpUNlpalNLqJNpUN]a_T-term
risks associated with tsunamis and enhance overall regional resilience.
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CouCoCoCoCCCooCCCCoCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCntytyyyyyyyyyyyyyy ofofooofofofofofffofofffofofffofofoooooofofofoooooffoooooooo LoLoLoLoooLoLoLooLoLooLoLLoLoLLoooLoLoLoLoLLLooLoLLLoooooLoLoooooLLLooLoooooosAsAAsAsAsAsAAsssAAAAAAAsssAsssAsAssAsAAAAAAAAssssssAsAsAsAAAssAs AsAAs Angengengngenngngengngenngenngnnngengengengngngngngenngngengngnnngngngngnngngnnngggggggggggggggggggleslesesesessesssesessssesssessseseseessesesssesessseeeesseseseeesseeeesesessssssssss
AAAAllAAAAAAAAAAAAA-Hazards MMMMMMMMMMMMMMMMMMMMMMitiititiitiittitiitiitiiiititiitititittitiiitiitititittittititiititittittttittttitiitititttitttiittttiiiititiiiiittititiittittiitiitiitittiiitiititttiiiiititiiitttiitiittttttittttttiittggatgatgggggggggionoonnononioniononionionioionononionoonononononooonooonooooooonnnnnnnnnnnnnnn Plaaannnnn
6.10 Severe Wind and Tornado
6.10.1 Nature
Severe wind and tornadoes pose
mVT_VœJA_ppUlNApmpa]VSNilaiNlpyA_L
V_SlAmplqJpqlN pUaqTU pUNy LVSSNl V_
frequency and intensity within Los Angeles
aq_py 1NvNlN wV_L NvN_pm iAlpVJq]Al]y
1A_pA _A wV_Lm AlN A lNJqllV_T _ApqlA]
hazard that can cause widespread
LA^ATN V_J]qLV_T Law_NL iawNl ]V_Nm
plNN SA]]m A_L mplqJpqlA]damage. These
winds originate from high-pressure
mympN^mavNlpUNlNAp
AmV_Sq__N]V_TLly
and warm air through mountain passes into
the coastal and valley regions at high
speNLm LLVpVa_A]]y mpal^-LlVvN_ wV_Lm
^VJlaIqlmpmstraight-line winds and gust
fronts associated with severe weather can
JlNApNUA|AlLaqmJa_LVpVa_maSpN_]NALV_T
paplA_mialpApVa_LVmlqipVa_mœlNUA|AlLm
and prolonged power outages.
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3al_ALaNm wUV]N lN]ApVvN]y lAlN V_ pUN lNTVa_ UAvN INN_ lNJalLNLA_LJA_JAqmN
localized but intense damage. These violent windstorms form when unstable
Ap^amiUNlVJ Ja_LVpVa_m ilaLqJN lapApV_T qiLlASpm lNmq]pV_T V_A Sq__N] J]aqL pUAp
contacts the ground.
6.10.2 Location
Severe wind events affect the entire Los Angeles County planning area wVpU pUN
mpla_TNmpaJJqllN_JNmV_JA_ya_iAmmNmvA]]NymA_LJaAmpA]lNTVa_mThe Santa Ana
wV_LmAlN^ampV_pN_mNV_pUNSA]]A_LwV_pNl^a_pUmiAlpVJq]Al]yV^iAJpV_TAlNAmin the
9A]]NyA_L foothill communities of the County. Storm-LlVvN_wV_Lma_pUNapUNlUA_L
can impact any part of the county and vary in intensity based on weather patterns.
3UNmN wV_Lm JA_ lNAJU miNNLm aS pa ^iU ma^NpV^Nm NxJNNLV_T pUamN
pUlNmUa]Lm]NALV_TpamVT_VœJA_pLA^ATN
Tornadoes are more sporadic in occurrence and can develop in various parts of the
Jaq_pyiAlpVJq]Al]yV_]aw]A_LAlNAmwUNlNmNvNlNpUq_LNlmpal^mUAvNpUNiapN_pVA]pa
form rotating systems.
6.10.3 Extent
Winds and breezes are common occurrences in LA County. As wind speeds increase
so does the potential for a catastrophic event. Hot dry winds can reach high speeds as
pUNyLNmJN_LSla^pUNV_]A_LLNmNlplNTVa_mJlNApV_T_apa_]yJlVpVJA]wV_LNvN_pmIqp
almaNxplN^N]yLA_TNlaqmœlNJa_LVpVa_mA_LJa_plVIqpV_TpapUNmilNALaSwV]LœlNm
3UNwV_LmAlNJ]AmmVœNLV_pUN
NAqSalp:V_L1JA]NmNNFigure 6.10.1 below. Beaufort
wind scale is an empirical scale that relates wind speed to observed conditions at sea
or land. It uses numerical scale from 1-12 to describe wind force based on visual
observations of the effects of the wind and gives quantitative measures of the wind. For
NxA^i]NaVmLNmJlVINLAm®JA]^¯AmNA]V\NA^VllalwUV]NLNmJlVINLAmUqllVJAne
force with devastating conditions.
3al_ALaNm AlN J]AmmVœNL qmV_T pUN _UA_JNL q[VpA Scale Figure 6.10.2. The
_UA_JNLq[VpA 1JA]NVmmiNJVœJA]]yqmNLpalApNpUNV_pN_mVpyaSpal_ALamIAmNL
a_pUNLA^ATNpUNyJAqmNLA^ATNV_LVJApalm mqJUAmIqV]LV_TpyiNmA_LplNNmp
ranges from EF-0 to EF- wVpUV_JlNAmV_T_q^INlmV_LVJApNmpla_TNlpal_ALamA_d
more severe damage. While tornadoes in the region typically do not exceed EF-1
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V_pN_mVpypUNyJA_mpV]]ilaLqJNLA^ATV_TwV_LmAIavN^iUJAiAI]NaSpNAlV_T
laaSmaSSIqV]LV_TmqilaapV_TplNNmA_LavNlpql_V_TvNUVJ]Nm
Beaufort Wind Scale:
Force
Wind
(Knots)
WMO
Classification
Appearance of Wind Effects
On the Water On Land
0 Less
than 1 Calm Sea surface smooth and
mirror-like
A]^m^a\NlVmNm
vertically
1 1-3 Light Air 1JA]ylVii]Nm_aSaA^JlNmpm
Smoke drift indicates
wV_LLVlNJpVa_mpV]]wV_L
vanes
2 4-6 Light Breeze 1^A]]wAvN]NpmJlNmpmT]Ammy
no breaking
:V_LSN]pa_SAJN]NAvNm
lqmp]NvA_NmINTV_pa
move
3 7-10 Gentle
Breeze
!AlTNwAvN]NpmJlNmpmINTV_
paIlNA\mJAppNlNLwUVpNJAim
Leaves and small twigs
Ja_mpA_p]y^avV_T]VTUp
flags extended
4 11-16 Moderate
Breeze
Small waves 1-4 ft. becoming
]a_TNl_q^NlaqmwUVpNJAim
qmp]NAvNmA_L]aamN
iAiNl]VSpNLm^A]]plNN
branches move
5 17-21 Fresh Breeze
Moderate waves 4-8 ft taking
]a_TNlSal^^A_ywUVpNJAim
some spray
Small trees in leaf begin
to sway
6 22-27 Strong
Breeze
Larger waves 8-Sp
wUVpNJAimJa^^a_^alN
spray
Larger tree branches
^avV_Twhistling in
wires
7 28-33 Near Gale
1NAUNAimqiwAvNm-Sp
white foam streaks off
breakers
:Ua]NplNNm^avV_T
resistance felt walking
against wind
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8 34-40 Gale
Moderately high (18-25 ft)
wAvNmaSTlNApNl]N_TpU
edges of crests begin to
IlNA\V_pamiV_LlVSpSaA^
blown in streaks
3wVTmIlNA\V_TaSSplNNm
generally impedes
progress
9 41-47 Strong Gale
High waves (23-Sp mNA
INTV_mpala]]LN_mNmplNA\m
aSSaA^milAy^AylNLqJN
visibility
Slight structural damage
aJJqlmm]ApNblows off
roofs
10 48-55 Storm
Very high waves (29-41 ft)
wVpUavNlUA_TV_TJlNmpmmNA
white with densely blown
SaA^UNAvyla]]V_T]awNlNL
visibility
Seldom experienced on
]A_LplNNmIla\N_al
qilaapNL´Ja_mVLNlAI]N
mplqJpqlA]LA^ATN´
11 56-63 Violent Storm
Exceptionally high (37-52 ft)
wAvNmSaA^iApJUNmJavNl
mNAvVmVIV]Vpy^alNlNLqJNL
12 64+ Hurricane
VlSV]]NLwVpUSaA^wAvNm
avNl SpmNAJa^i]NpN]y
wUVpNwVpULlVvV_TmilAy
visibility greatly reduced
Figure 6.10.1 ĞĂƵĨŽƌƚtŝŶĚ^ĐĂůĞ
County of Los Angeles
All-Hazards Mitigation Plan
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Enhanced Fujita Scale:
THE ENHANCED FUJITA SCALE (EF SCALE)
03# 1NJa_Lqmp"- "
EF 0 65-85 MPH !VTUp
lA_JUNmIla\N_
minor roof damage
EF 1 86-110 MPH Moderate: Roofs
LA^ATNLplNNmqilaapNL
EF 2 111-135 MPH Considerable: Roofs torn
aSS]AlTNplNNmLaw_
EF 3 136-165 MPH 1NvNlNa^NmLNmplayNL
cars lifted
EF 4 166-200 MPH Devastating: Houses
]NvN]NLLNIlVmAVlIal_N
EF 5 Over 200 MPH Incredible: Homes swept
away total destruction
6.10.4 History
Los Angeles County has experienced multiple severe wind events and occasional
tornadoes in recent history wUVJUJAqmNLLNmplqJpVa_mA_LwV]LœlNm. There have been
no federal declarations or state proclamations for Severe Wind & Tornadoes in the last
œvNyNAlm Some notable incidents include:
x November-December 2011: wV_LNvN_pJAqmNL^alNpUA_¸ ^V]]Va_V_
damages and severely impacted several foothill communities and
unincorporated areas.
x December 2019: An EF-pal_ALapaqJUNLLaw_V_1aqpU!am_TN]NmJAqmV_T
minor roof damage and downing power lines.
x January 2021: mNvNlNwV_Lmpal^V^iAJpNLpUNlNTVa_]NALV_TpaLA^ATN
across multiple communities and emergency response efforts to clear roadways.
x September 2021: An EF-0 tornado developed near the community Lake of Los
_TN]NmÈ_aLA^ATNwAmlNialpNL
Figure 6.10.2 Enhanced Fujita Scale
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x April 2023: An EF-0 tornado recorded in Cerritos causing tree damage.
x March 2023 (0 ): An EF- pal_ALa mplqJ\ "a_pNIN]]a a_N aS pUN
mpla_TNmp pal_ALaNm lNJalLNL V_ pUN AlNA JAqmV_T mVT_VœJA_p LA^ATN pa
commercial structures and vehicles.
x May 2023: An EF-0 tornado occurred near the communities of Carson and
Compton damaging buildings and vehicles.
x August 2023 (0 ): Tropical Storm Hillary impacting Los Angeles
County.
x February 2024: Strong winds impacting across Eastern Santa Monica Mountain
and Santa Clarita Valley.
x March 2024: Strong winds impacting areas around San Gabriel Valley.
x January 2025 (0 ): A mNvNlNwV_Lmpal^V^iAJpNLpUNlNTVa_]NALV_T
to a -apN_pVA]]yA_TNlaqm1VpqApVa_-1 lNLŔATJa_LVpVa_m1NvNlA]œlNm
Ila\NaqpV_pUNAlNAwUVJUNxUVIVpNLNxplN^NœlNINUAvValJAqmV_TwVLNmilNAL
destruction.
x March 2025 (0 ): miAlpaSAmpal^NvN_pA_ EF-0 tornado struck Pico
0VvNlAA]VSal_VAAp A^with wind speeds reaching up to 85 mph.
6.10.5 Probability
1NvNlNwV_LNvN_pmAlNAlNTq]AlaJJqllN_JNV_!am_TN]Nmaq_py wVpU A Uigh
probabilityÈJUA_JN recurring annually. Santa Ana winds are particularly common
LqlV_TpUNJaa]Nl^a_pUmA_LJ]V^ApNiAppNl_mmqTTNmppUApNxplN^NwV_LNvN_pm^Ay
become more frequent due to changing weather dynamics. Because wind events and
pal_ALam AlN ]aJA]V|NL V_ _ApqlN ilaIAIV]Vpy vAly Sla^ a_N AlNApaA_apUNlA_LVm
LVSœJq]ppaLNpNl^V_NiNlJN_pATNaSUAiiN_V_TV_a_NAlNATornadoes remain a low-
probability hazard10% chance in the planning areaUawNvNlTVvN_iAmpaJJqllN_JNm
they cannot be ruled out entirely. Atmospheric conditions capable of producing
pal_ALaNm^AyAlVmNLqlV_TmNvNlNpUq_LNlmpal^miAlpVJq]Al]yV_wV_pNlmpal^mympN^m
that generate strong wind shear. While the likelihood of an EF-2 or stronger tornado is
^V_V^A]pUNiapN_pVA]Sal]aJA]V|NLLA^ATNlN^AV_m The Santa Ana winds occur ten to
twenty-œvNpV^NmA__qA]]yA_LJA_]AmpSalmNvNlA]LAymiamV_TAlNJqllV_TpUlNApaS
damage and disruption in Los Angeles County.
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6.10.6 Vulnerability
SNvNlNwV_LA_Lpal_ALaNmJA_INNxpN_mVvNASSNJpV_TIapUV_SlAmplqJpqlNA_LiqI]VJ
safety. High-wV_LNvN_pmiamNAlVm\paJlVpVJA]V_SlAmplqJpqlNiAlpVJq]Al]yiawNl]V_Nm
Ja^^q_VJApVa_ mympN^m A_L plA_mialpApVa_ _Npwal\m
qV]LV_TmNmiNJVA]]y a]LNl
structures and ^aIV]NUa^NmAlNvq]_NlAI]NpawV_L-lN]ApNLLA^ATNV_J]qLV_TlaaS
SAV]qlNmwV_LawIlNA\ATNA_LmplqJpqlA]Ja]]AimN
_ALLVpVa_paiUymVJA]LA^ATNmNvNlNwV_LNvN_pmJA_JAqmNmVT_VœJA_pNJa_a^VJ
LVmlqipVa_m-la]a_TNLiawNlaqpATNmV^iAJpIqmV_NmmNmUNA]pUJAlNSAJV]VpVNm A_L
emergency response services. Road closures and debris blockages hinder mobility and
commercNwUV]NwV_L-LlVvN_wV]LœlNmAmNJa_LAlyUA|AlLaS1A_pA_AwV_LmJA_
lead to devastating losses.
-qI]VJmASNpyVmA]maA^A[alJa_JNl_wVpUlVm\maSŔyV_TLNIlVmvNUVJ]NAJJVLN_pm
avNlpql_NLvNUVJ]Nm and respiratory issues caused by airborne dust and pollutants
stirred up by high winds.
Severe wind and tornado events disproportionately impact certain populations and
infrastructure in Los Angeles County due to both geographic exposure and
maJVaNJa_a^VJvq]_NlAIV]VpVNm3UNmNUA|AlLmJA_LVmlqipJlVpVJA]mNlvVJNmNxAJNlIApN
existing inequa]VpVNmA_LmVT_VœJA_p]yLA^ATNmplqJpqlNm_apIqV]ppawVpUmpA_LNxplN^N
wind conditions.
9q]_NlAI]N-aiq]ApVa_m
%qpaSpUNJaq_py¯mNmpV^ApNL^V]]Va_lNmVLN_pmpUNSa]]awV_Tiaiq]ApVa_mAlN
considered especially vulnerable:
x Older Adults (65+): Approx. 1.6 million residents (15.5%)—more likely to suffer
injury or health complications during wind-related power outages and
evacuation events.
x Access and Functional Needs (AFN) Populations: Estimated 1.7 million
V_LVvVLqA]m È V_J]qLV_T pUamN wVpU LVmAIV]VpVNm ]V^VpNL ^aIV]Vpy al
communication barriers.
x Low-Income Households: Over 13% of households fall below the poverty line
and may lack the resources for structural mitigation or relocation during
prolonged outages.
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x -Nai]N xiNlVN_JV_T a^N]Nmm_Nmm - %vNl V_LVvVLqA]m
!1 Jaq_p Ap LVlNJp lVm\ Sla^ SA]]V_T LNIlVm A_L ]AJ\ aS mUN]pNl LqlV_T
windstorms.
x "aIV]Na^N0NmVLN_pmiilaxV^ApN]yq_VpmJaq_pywVLNJa_JN_plApNL
in inland valleys and foothill communities that are highly exposed to Santa Ana
winds.
x UV]LlN_4_LNlTN laq_LJaq_pywVLNvq]_NlAI]NpalNmiVlApaly
complications from airborne particulates and debris stirred by strong winds.
x Ja_a^VJ ^iAJp
qmV_Nmm LVmlqipVa_m V_JlNAmNL V_mqlA_JN J]AV^mA_LpUN
Jampm aS N^NlTN_Jy lNmia_mN A_L lNJavNly ALL œ_A_JVA] IqlLN_m pa ]aJA]
communities.
lVpVJA]_SlAmplqJpqlNAp0Vm\
Severe wind and tornado events can cause widespread cascading failures in vital
mympN^mV_J]qLV_T
x -awNl _SlAmplqJpqlN !am _TN]Nm aq_py Ja_pAV_m avNl ^V]Nm aS
overhead power lines vulnerable to high-wV_LLA^ATNA_LœlNVT_VpVa_
x "NLVJA]AJV]VpVNm%vNl ]VJN_mNLUamiVpA]mA_LUNA]pUJ]V_VJm^A_ylN]VA_p
on uninterrupted power and access for vulnerable patient populations.
x Transportation Corridors: Major highways (I- - 41- A_L avNl
IlVLTNmiAlpVJq]Al]yV_JA_ya_A_LSaapUV]]AlNAmAlNmqmJNipVI]NpaaImplqJpVa_
by fallen trees and debris.
x Communication Towers: Over 800 critical telecom sites serve the county’s
emergency communications and can be disrupted by high wind gusts.
x 1JUaa]miilaxV^ApN]yiqI]VJ –12 schools and 100+ college campuses
face operational disruptions from power outages or infrastructure damage
during events.
6.10.7 Impacts
1NvNlNwV_LA_Lpal_ALaNvN_pmiamNmVT_VœJA_ppUlNApmpaJlVpVJA]V_SlAmplqJpqlNiqI]VJ
mASNpyA_LJa^^q_VpyaiNlApVa_mV_!am_TN]Nmaq_pyVTUwV_LmmqJUAmpUamN
LqlV_T1A_pA_ANvN_pmlNTq]Al]yLA^ATNiawNl]V_NmqilaapplNNmA_LLVmAI]N
County of Los Angeles
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plA_mialpApVa_ JallVLalm _apAI]N NxA^i]N aJJqllNL V_ A_qAly wUN_
wVLNmilNAL wV_Lmpal^m JAqmNL iawNl aqpATNm Sal ^alN pUA_ Jqmpa^Nlm
V_J]qLV_T AiilaxV^ApN]y !am _TN]Nm NiAlp^N_p aS :ApNlA_L-awNl
!:- Jqmpa^Nlm A_L avNl 00 Southern California Edison (SCE) customers.
qlV_TpUVmmA^NiNlVaLwV]LœlNmNxAJNlIApNLIypUNmpla_TwV_LmV^iAJpNLmNvNlA]
^NLVJA] SAJV]VpVNm LVmlqipV_T JlVpVJA] UNA]pU mNlvVJNm A_L lNkqVlV_T pUN N^NlTN_Jy
relocation of patients.
3al_ALaNmwUV]NlAlNUAvNA]maLN^a_mplApNLLNmplqJpVvNJAiAJVpyV_]aJA]V|NLAlNAm
_"AlJU A_-pal_ALapaqJUNLLaw_V_-VJa0VvNlALaw_V_TiawNl]V_NmA_L
plNNm A_L aImplqJpV_T laALwAym UVTU]VTUpV_T pUN iapN_pVA] Salpal_ALVJ AJpVvVpy pa
impact urban communities. These hazards not only endanger life and property but also
pUlNApN_NJa_a^VJJa_pV_qVpyA_LpUNSq_JpVa_V_TaSN^NlTN_JymNlvVJNmiAlpVJq]Al]y
in vulnerable neighborhoods and areas with aging infrastructure.
6.10.8 Mitigation and Preparedness
Efforts to mitigate the effects of severe wind and tornadoes should focus on improving
mplqJpqlA] lNmV]VN_JN N_UA_JV_T NAl]y wAl_V_Ts and alerts A_L V_JlNAmV_T iqI]VJ
awareness of such events.
Severe Wind and Tornado Mitigation
x Strengthening building codes to require wind-resistant design features.
Promoting the use of wind-resistant materials and construction techniques in
new developments.
x Conducting regular tree-trimming and vegetation management to reduce
infrastructure damage risks.
x 0NplaœppV_TA_LlNV_SalJV_TJlVpVJA]V_SlAmplqJpqlNmqJUAmiawNl]V_NmA_LqpV]Vpy
mympN^mpawVpUmpA_LUVTU-wind conditions.
x Implementing public education campaigns on windstorm preparedness and
safety measures.
x Leveraging early warning alerting and ilNiAlNL_Nmm ^NmmATV_T Am wN]] Am
integrating emergency messaging with local broadcast and mobile networks.
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6.10.9 Summary
1NvNlNwV_LA_Lpal_ALaNmpUaqTULVSSNlV_TV_SlNkqN_JylN^AV_iapN_pVA]UA|AlLmSal
Los Angeles County. Santa Ana winds and storm-driven gusts regularly impact the
lNTVa_JAqmV_TLA^ATNpaV_SlAmplqJpqlNA_LV_JlNAmV_TwV]LœlNlVm\m:UV]Npal_ALaNm
alNlAlNpUNVlaJJAmVa_A]aJJqllN_JN_NJNmmVpApNmilNiAlNL_NmmA_L^VpVTApVa_NSSalpm
y V^i]N^N_pV_T mpla_TNl IqV]LV_T JaLNm lNV_SalJV_T JlVpVJA] V_SlAmplqJpqlN A_L
enhancing preparedness and iqI]VJAwAlN_NmmpUNJaq_pyJA_lNLqJNVpmvq]_NlAIV]Vpy
to these hazards helps to better protect its residents from potential hazards of severe
winds and tornado and improve community resilience.
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6.11 Mass Violence
6.11.1 Nature
3UVmmNJpVa_aqp]V_NmpUNLNœ_V_T
JUAlAJpNlVmpVJm aS ^Amm vVa]N_JN
wUVJU V_J]qLNm V_pN_pVa_A] UVTU-
V^iAJp V_JVLN_pm mqJU Am pNllalVm^
AJpVvNmUaapNlNvN_pmvNUVJ]N-
lA^^V_TmA_LapUNlJaalLV_ApNL
attacks. Understanding the nature of
these events is critical for
developing effective mitigation
strategies.
x Mass violence includes both
pAlTNpNL AppAJ\m NT
ideologically motivated
terrorism) and opportunistic
AJpm NT AJpVvN mUaapNlm al
violent assaults in public
spaces).
x 3UNmNV_JVLN_pmAlNJUAlAJpNlV|NLIypUNVl]awwAl_V_TpV^NUVTU]NpUA]VpyA_L
potential to incite widespread fear and panic.
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x Acts of mass violence
may be perpetrated by
V_LVvVLqA]mm^A]]Tlaqim
or well-organized
_Npwal\m A_L JA_
V_va]vN œlNAl^m
Nxi]amVvNm vNUVJ]Nm al
biological agents.
x These attacks often aim
to disrupt societal
Sq_JpVa_m LA^ATN
V_SlAmplqJpqlN al Nxi]aVp
vulnerabilities in soft
pAlTNpm mqJU Am mJUaa]m
i]AJNmaSwalmUVial
entertainment venues.
_mq^^AlypUN_ApqlNaS^Amm
violence lies in its deliberate
V_pN_ppaV_ŔVJpUAl^a_Tlaqim
A_L LVmlqip iqI]VJ alLNl
making strong mitigation
measures essential for
protecting life and property of
Los Angeles County.
6.11.2 Extent
The potential extent of mass
violence is characterized by its
ability to cause widespread
LVmlqipVa_A_LmVT_VœJA_p]ammaS
life and property.
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x Events can result in many casualties and severe physical and psychological
impacts.
x Mass violence can LVmlqip NmmN_pVA] mNlvVJNm mplAV_ N^NlTN_Jy lNmia_mN
mympN^mA_LJlNApNJAmJALV_TmaJVaNJa_a^VJNSSNJpm
x 3UNavNlA]]LVmlqipVa_^AyNxpN_LSAlINya_LpUNV^^NLVApNmJN_NASSNJpV_T
broader community resilience.
_ NmmN_JN wUV]N pUNmN NvN_pm ^Ay IN lAlN pUNVl NxpN_mVvN V^iAJpm _NJNmmVpApN
comprehensive planning and resilient infrastructure.
6.11.3 History
VmpalVJA]LApAV]]qmplApNmpUAp^AmmvVa]N_JNUAmNva]vNLavNlpV^NwVpUNAl]VNlNvN_pm
shaping current mitigation strategies and more recent incidents underscoring
emerging vulnerabilities. Previous mitigation and other plans referenced events such
as large-scale terrorist attacks and active shooter incidents.
x 0NJN_pNvN_pmV_pUN]AmpœvNyNAlmV_J]qLNUVTU-ilaœ]NAJpVvNmUaapNlV_JVLN_pm
Ap mJUaa]m iqI]VJ plA_mialpApVa_ UqIm A_L Ja^^NlJVA] JN_pNlmAmwN]]Am
vehicle-ramming attacks in urban areas.
%vNlA]]pUNUVmpalVJA]plN_LmUawmpUApwUV]NSlNkqN_JylN^AV_m]awpUNmNvNlVpyaS
mass violence i_JVLN_pmUAmNmJA]ApNL_NJNmmVpApV_TJa_pV_qA]qiLApNmpa^VpVTApVa_
strategies.
6.11.4 Location
"AmmvVa]N_JNV_JVLN_pmpN_LpaaJJqlV_AlNAmwUNlNiNai]N_ApqlA]]yJa_TlNTApN
V_J]qLV_TqlIA_JN_pNlmplA_mialpApVa_UqImNLqJApVa_A]and religious V_mpVpqpVa_m
mUaiiV_TJN_pNlmA_LiqI]VJevents and venues.
x -qI]VJmiAJNmmqJUAmplA_mVpmpApVa_mmpALVq^m^A]]m and other locations where
]AlTN_q^INlaSiNai]NAmmN^I]N are considered higher-risk areas.
x Critical infrastructure locationlike government buildings and commercial
centerare often targeted.
x Certain events may also occur in areas lacking adequate physical security or
surveillance.
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3UqmVLN_pVSyV_TA_LmNJqlV_TUVTU-density locations is a key focus for mitigating the
effects of mass violence.
6.11.5 Probability
3UNilaIAIV]VpyaS^AmmvVa]N_JNV_JVLN_pmVmLVSœJq]ppailNLVJpilNJVmN]yUawNvNlpUN
potential for occurrence is recognized as a persistent low-SlNkqN_JyUVTU-impact risk
that requires constant vigilance.
x Such incidents are statistically rare yet present a disproportionate risk due to
their catastrophic consequences.
x Threat assessments and intelligence reports indicate that evolving tactics may
increase probability over time.
x a_pV_qaqm^a_VpalV_TA_LqiLApNLpUlNApA_A]ymNmNTvVA30ilaJNmmNm
are essential in quantifying risk levels.
_ mq^^Aly wUV]N ^Amm vVa]N_JN NvN_pm AlN _ap Ja^^a_ pUNVl V_UNlN_p
unpredictability and high severity demand that communities prepare as if an incident
could occur at any time.
6.11.6 Vulnerability
Mass vVa]N_JNLNiN_Lma_AvAlVNpyaSSAJpalmV_J]qLV_TiUymVJA]V_SlAmplqJpqlNLNmVT_
iqI]VJAwAlN_NmmmNJqlVpyilNiAlNL_NmmA_LV_pNlATN_JyJaalLV_ApVa_
x Critical vulnerabilities include open public spaces with minimal physical barriers
or limited or ineffective safety / security protocols in place.
x ௗAimV_plAV_V_TA_LilNiAlNL_NmmA^a_TœlmplNmia_LNlmJA_NxAJNlIApNpUN
situation during an active incident.
x Social vulnerabilities—such as communication gaps or lack of multilingual
emergency information—may hinder rapid response and community resilience.
3Uqm lNLqJV_T vq]_NlAIV]Vpy V_va]vNm V_vNmpV_T V_ V_SlAmplqJpqlN UAlLN_V_T laIqmp
mNJqlVpy ^NAmqlNm lNTq]Al plAV_V_T NxNlJVmNm A_L NSSNJpVvN iqI]VJ Ja^^q_VJApVa_
strategies.
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6.11.7 Impacts
3UNV^iAJpmaS^AmmvVa]N_JNNvN_pmAlN^q]pVSAJNpNLlife safetyJa^^q_VpympAIV]Vpy
and the local economy.
x ^^NLVApN V^iAJpm V_J]qLN SApA]VpVNm V_[qlVNm A_L plAq^A A^a_T ASSNJpNL
populations.
x 1NJa_LAly V^iAJpm ^Ay N_Ja^iAmm ila]a_TNL LVmlqipVa_ aS ]aJA] mNlvVJNm
NJa_a^VJLaw_pql_mA_L]AmpV_TimyJUa]aTVJA]NSSNJpma_Ja^^q_VpVNm
x Long-term consequences can involve extensive resource allocation for recovery
A_L^VpVTApVa_SqlpUNlmplAV_V_TiqI]VJmympN^m
"AmmvVa]N_JNV_ŔVJpmV^^NLVApNUAl^A_LaSpN_plVTTNlmAJUAV_aSmNJa_LAlyV^iAJpm
that complicate community recovery and strain long-term resilience efforts.
6.11.8 Summary
_Ja_J]qmVa_^VpVTApV_TpUNUA|AlLmaS^AmmvVa]N_JNlNkqVlNmA_V_pNTlApNL^q]pV-
]AyNlNL AiilaAJU pUAp miA_m ilNvN_pVa_ ilNiAlNL_Nmmresponse and recovery.
Communities must implement measures to secure high-lVm\ ]aJApVa_m qiTlALN
iUymVJA] A_L LVTVpA] mNJqlVpy N_UA_JN V_pNlATN_Jy JaalLV_ApVa_ A_L Ja_pV_qaqm]y
update training and threat assessments.
x "VpVTApVa_mplApNTVNmV_J]qLNiUymVJA]mNJqlVpyN_UA_JN^N_pmNTIAllVNlmA_L
mqlvNV]]A_JN lNTq]AlAJpVvNmUaapNlLlV]]mV^ilavNLN^NlTN_JyJa^^q_VJApVa_
mympN^mA_LJaalLV_ApNL]AwN_SalJN^N_pA_LiqI]VJUNA]pUlNmia_mNm
x Investment in resilience-building measures and community outreach helps to
N_mqlNpUApV_pUNNvN_paSA_V_JVLN_pJa^^q_VpVNmJA_lNJavNlkqVJ\]yA_L
effectively.
This section underscores that while mass violence NvN_pmAlNlAlNpUNVliapN_pVA]Sal
high impact demands rigorous preparedness and adaptive mitigation strategies to
safeguard lives and maintain community functionality.
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6.12 Cybersecurity Incidents
6.12.1 Nature
Cybersecurity incidents refer to
disruptive events affecting digital
networks and systems. These events
involve the unauthorized electronic
or physical access of information
systems that jeopardizes or disrupts
pUN V_pNTlVpy Ja_œLN_pVA]Vpy al
availability of information. Cyber
incidents can range from minor
targeted data breaches to large-
scale ransomware attacks and
distributed denial-of-service (DDoS)
events that compromise critical
infrastructure. Common types of
JyINlmNJqlVpyV_JVLN_pmV_J]qLNIqp
are not limited to:
x Data Breaches:3UN Ja^ila^VmN q_AqpUalV|NL LVmJ]amqlN al q_AqpUalV|NL
acquisition of information.
CouContytyttyyntyy offofofo LoLoLoLLLoLLLLLooLLLosAs AsAs As AsAsAs AsAs As As As As AA AAs AAAAAAAAAAAAAngengengngengengengengengengngegngengengengengengngegegeenggngegengeegngennglesleslesesleslesllesleslesleslesleseslesleesesleslesessesleseslleselel
AllAA-HazHazHazHHHHHazHazHazzzHaaardardardrdardardrddardddddardddardddrdds Ms Ms Ms Ms Ms MsMsMMs Ms MsMMsMMMMs MMMMMs MMMs Ms MMs Ms MMs Mitiitiitiitiitititiitiitiitiiititiititiitttitiiititittgatgatgatgagatgatgatgatgatgatgatgatgatatgatgatgatggagatgagatagggggattaaaaioiononionionionionionnnionionionionionnnnononionnoonnonnonnoionoonnoonoononionnononniooonnnnooooonooononnnnnn PlPlPlPlPlPlPlPllPPPllPPlPlPPPPPlPllPlaPlaPPPPPlPlaPPPPlPlPPPPPPPlaaPPPPllPlPlaPPPllaPPPnn
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x Malware: "A]VJVaqm UAlLwAlN œl^wAlN al maSpwAlN pUAp Vm V_pN_pVa_A]]y
included or inserted in a system for a harmful purpose.
x 0A_ma^wAlN A type of malicious software designed to lock access to a system
until a ransom payment is received. Note that ransom payment is not a
guarantee that system access will be restored by the threat actor.
x Denial of Service (DoS): _AppAJ\^NA_ppamUqpLaw_A^AJUV_Nal_Npwal\
rendering it inaccessible to its intended users.
x Distributed Denial of Service (DDos): A DoS attack that uses numerous hosts
to perform the attack.
x Insider Threats: :UN_ A_ V_mVLNl NT A_ N^i]ayNN al vN_Lal qmNm pUNVl
AqpUalV|NLAJJNmmwVppV_T]yalq_wVppV_T]ypaLaUAl^paA_alTA_V|ApVa_
x -UVmUV_TppAJ\m The fraudulent practice of sending emails purporting to be
from reputable senders in order to induce individuals to reveal information or
download malware by clicking on a link.
Key characteristics of a cybersecurity incident include:
0AiVL%_mNp Impacts to operations can occur suddenly and evolve quickly.
x Sophistication: Can be highly sophisticated with state or non-state actors
involved.
x yIlVL ppAJ\m May involve both cyber and physical components due to
interdependencies.
x Non-Malicious Incidents: Technological failures that cause similar impacts to
cybersecurity incidents may also occur due to non-malicious reasons such as a
software or hardware issue.
Understanding the inherent digital nature and complex characteristics of these
incidents is critical to developing effective prevention and mitigation strategies.
6.12.2 Location
4_]V\NplALVpVa_A]UA|AlLmpUApUAvNAiUymVJA]TNaTlAiUVJSaapilV_p JyINlmNJqlVpy
V_JVLN_pmAlNV_UNlN_p]yplA_mIaq_LAlyawNvNlpUNVlNSSNJpm^A_VSNmp]aJA]]ypUlaqTU
the disruption of critical services and systems and necessitate regionally coordinated
preparedness and response efforts.
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qlVmLVJpVa_A]0N]NvA_JN
x Impact local government networks and county infrastructure.
x Affect public and private sector systems within Los Angeles County.
x Disrupt critical infrastructure such as utilities and cause cascading impacts.
x _va]vN JyINl _aLNm pUAp wUV]N T]aIA]]y LVmplVIqpNL Ja_vNlTNa_ lNTVa_A]
networks.
Critical Sectors Impacted:
x Hospitals and healthcare facilities.
x FinancialIA_\V_TaliAyla]]systems.
x Transportation providers and systems.
x 4pV]VpVNmmqJUAmN]NJplVJVpyTAmA_LwApNl
x Emergency response and public safety agencies.
6.12.3 Extent
The extent of cybersecurity incidents is measured not only by the volume of
Ja^ila^VmNLLApAalœ_A_JVA]]ammIqpA]maIypUNiapN_pVA]LVmlqipVa_paNmmN_pVA]
services and critical infrastructure.
Scope of Impacts:
x Rapid spread across interconnected digital systems.
x Potential for cascading failures that disrupt multiple sectors.
x Economic losses that may run into millions of dollars.
Measurable Factors:
x Number of systems compromised.
x Downtime of critical infrastructure and services.
x Financial costs from remediation and lost productivity.
The extensive reach of cybersecurity incidents—both in terms of economic impact and
service disruption—highlights the need for robust digital defenses Ja_pV_qVpy aS
aiNlApVa_mi]A__V_TIAJ\qimympN^mA_LlNLq_LA_JVNmLVmAmpNllNJavNlymplApNTVNm
and regional cyber response coordination.
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6.12.4 History
VmpalVJA]]y JyINlmNJqlVpy V_JVLN_pm UAvN Nva]vNL Sla^ Vma]ApNL IlNAJUNm pa
coordinated attacks that leverage global networks. Early cybersecurity incidents
focused on data theft and vandalism. More recent attacks have grown increasingly
sophisticated and targeted critical infrastructure or use complex ransomware. Cyber
threat actors include state-sponsored groups along with non-state groups such as
criminal enterprises and terrorist organizations. Recent years have seen cybersecurity
incidents affecting ]AlTNJalialApVa_miqI]VJN_pVpVNmV_J]qLV_T]aJA]TavNl_^N_pmA_L
critical infrastructure sectors. Previous major cybersecurity incidents have included:
x !am_TN]Nmaq_py1qiNlValaqlp0A_ma^wAlNppAJ\Resulted in
pUNmUqpLaw_aS_NAl]yNvNlyJaqlpmympN^A^q]pV-LAyJ]amqlNaSpUNJaqlpA_L
cascading impacts to operations.
x amiVpA]laqippAJ\A major hospital company experienced an attack
that caused IT and phone system outages and disrupted patient care at several
Los Angeles County hospitals.
x 3N]NJa^^q_VJApVa_ _Lqmply ppAJ\m: A series of attacks against
telecommunications providers in the United States resulted in compromised
customer data.
x VpyppAJ\A cybersecurity incident at a city within Los Angeles County
JAqmNLJVpy3mympN^mpaINpA\N_aSŔV_N
x vVApVa__LqmplyppAJ\m A series of cybersecurity incidents targeting
the airports and airlines caused transportation system disruptions.
The historical progression from rudimentary attacks to highly coordinated
cybersecurity incidents underscores the growing importance of proactive risk
management in the digital realm.
6.12.5 Probability
The probability of cybersecurity incidents occurring is increasing as digital
interconnectivity expands and as attackers continue to innovate their methods.
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0Vm\Trends:
x Rapid expansion of the Internet of Things (IoT) pUN _Npwal\ aS V_pNl_Np-
connected devices ranging from smart refrigerators to autonomous vNUVJ]Nm has
added new attack vectors to the threat landscape.
x Increasing sophistication of cybercriminal methods including zero-LAyNxi]aVpm
a previously unknown cybersecurity vulnerability.
x Growing frequency of reported incidents nationally and globally.
Contributing Factors:
x Inadequate cybersecurity measures in legacy systems still being used by
organizations.
x Underinvestment in cyber defense infrastructure or cybersecurity expertise.
x Greater digital reliance in everyday operations without proper continuity of
operations planning.
VvN_JqllN_pplN_LmA_LpNJU_a]aTVJA]LNvN]ai^N_pmpUN]V\N]VUaaLaSJyINlmNJqlVpy
V_JVLN_pmlN^AV_mUVTU_NJNmmVpApV_Ta_TaV_TvVTV]A_JNA_LN_UA_JNLilNiAlNL_Nmm
measures. mJyINlmNJqlVpyV_JVLN_pmJa_pV_qNpaV_JlNAmNV_SlNkqN_JypUNiapN_pVA]
for an incident to cause cascading and widespread impacts to critical infrastructure
increases as well.
6.12.6 Vulnerability
Vulnerability in the context of cybersecurity refers to the susceptibility of digital systems
paAppAJ\3UVmVmV_ŔqN_JNLIyIapUpNJU_a]aTVJA]A_LalTA_V|ApVa_A]SAJpalmV_J]qLV_T
Iqp _ap ]V^VpNL pa aqpLApNL maSpwAlN al qmN aS ]NTAJy mympN^m V_mqSœJVN_p iApJU
^A_ATN^N_pV_ALNkqApNmNT^N_pApVa_A_LLNSN_mN-in-LNipUmplApNTVNmA_L]AJ\aS
cybersecurity training among personnel. Organizational challenges also contribute to
JyINlmNJqlVpyvq]_NlAIV]VpyV_J]qLV_TIqp_ap]V^VpNLpaIqLTNpJa_mplAV_pmgaps in
JaalLV_ApVa_ A_L lAiVL pNJU_a]aTy ALaipVa_ wVpUaqp JallNmia_LV_T mNJqlVpy
protocols.
JJalLV_TpapUN3UlNApA_LA|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p30
avNliNai]N^AyIN ASSNJpNLIy A]AlTN-scale cybersecurity incident with
cascading impacts to utilities. Over of those impacted in the THIRA scenario
are estimated to UAvN AJJNmm A_L Sq_JpVa_A] _NNLm A_L avNl iNai]Nare
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estimated to have ]V^VpNL_T]VmUilaœJVN_JyNiN_LV_Ta_pUNqpV]VpVNmASSNJpNLIy
the V_JVLN_pAwVLNmilNALA^aq_paSpUNiaiq]ApVa_Jaq]LINwVpUaqpqpV]VpymNlvVJN
for an extended period. Addressing these vulnerabilities is essential to reduce the risk
and potential disruption aSJyINlmNJqlVpyV_JVLN_pmJA]]V_TSalIapUpNJU_VJA]qiTlALNm
and improved interagency coordination.
6.12.7 Impacts
3UNV^iAJpmaSJyINlmNJqlVpyV_JVLN_pmAlN^q]pVSAJNpNLASSNJpV_TNJa_a^VJmpAIV]Vpy
iqI]VJmASNpyA_LJlVpVJA]V_SlAmplqJpqlNaiNlApVa_m
Direct Impacts:
x VmlqipVa_ aS JlVpVJA] mNlvVJNm NT UNA]pUJAlN N^NlTN_Jy lNmia_mN
plA_mialpApVa_NpJ).
x Extended duration Continuity of Government or Continuity of Operations event.
x Financial losses due to ransom payments remediation costsA_LiapN_pVA]]NTA]
fees.
x Losscompromisealq_AqpUalV|NLlN]NAmN of sensitive data.
Indirect impacts:
x Erosion of public trust in digital services and affected institutions.
x AmJALV_TNSSNJpma_iUymVJA]V_SlAmplqJpqlNNTiawNlTlVLwApNlmympN^m
wAmpNwApNlNpJ
x Long-term economic repercussions from reduced competitiveness.
x 3UNmVT_VœJA_pV^iAJpm—both direct and cascading—of cybersecurity incidents
necessitate comprehensive mitigation and recovery strategies that address both
technical and socioeconomic dimensions.
6.12.8 Summary
_ mq^^Aly JyINlmNJqlVpy V_JVLN_pm lNilNmN_p A_ Nva]vV_T A_L JlVpVJA] pUlNAp pUAp
intersects with multiple aspects of community resilience and safety.
Ny3A\NAwAym
x yINlV_JVLN_pmAlNLy_A^VJmaiUVmpVJApNLA_LSAl-reaching in impact
x They affect local systems despite their global nature
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x Historical trends and increasing digital dependency heighten both probability
and vulnerability
x ^iAJpmNxpN_LINya_Lœ_A_JVA]]ammpaV_J]qLNmNlvVJNLVmlqipVa_A_L
cascading infrastructure failures
yINlmNJqlVpy V_JVLN_pm LN^A_L A ilaAJpVvN JaalLV_ApNL lNmia_mN pUAp V_pNTlApNm
robust technical defenses with cross-sector planning and recovery efforts. By
q_LNlmpA_LV_T pUN _ApqlN mJaiN A_L iapN_pVA] Ja_mNkqN_JNm aSpUNmN V_JVLN_pm
communities can build more resilient digital and physical infrastructures to safeguard
against this growing threat.
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6.13 Transportation Incidents
6.13.1 Nature
This section describes the inherent characteristics of transportation incidents that can
LVmlqippUNJa_pV_qaqmŔawaSiNai]NTaaLmA_LN^NlTN_Jy mNlvVJNmAJlamm!am
Angeles County. Transportation incidents can be triggered by a variety of factors
V_J]qLV_T _ApqlA] NvN_pm Uq^A_ Nllal A_L LN]VINlApN AJpmOther characteristics
include:
x Affected Modes of Transportation: Incidents can involve any mode of
transportation such as multi-vNUVJ]N Ja]]VmVa_m UA|AlLaqm ^ApNlVA] miV]]m lAV]
LNlAV]^N_pmAvVApVa_incidentsA_L^AlVpV^NLVmlqipVa_m
x Cascading Impacts: Disruptions to the transportation system often have the
potential to trigger cascading failures due to the interconnected design of
UVTUwAymlAV]_Npwal\mAVlialpmA_Lseaports.
x Contributing Factors: Incidents may INV_ŔqN_JNLIyIapUilNLVJpAI]NSAJpalm
NTrush-Uaql Ja_TNmpVa_ A_L q_ilNLVJpAI]N aJJqllN_JNm NT NxplN^N
weather or infrastructure failure).
6.13.2 Location
3UNJaq_py¯m_Npwal\N_Ja^iAmmNmUVTUwAymlAV]AVlialpmialpmA_L]aJA]laALmpUAp
are critical to regional mobility and commerce.
CCCouCouCntynty ofo LoLos As Angengeeeeleslesleslelele
AllAl-Hazazardars MMMs Mitigatggiononnn PlaPlaPlPlPlPnn
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x Freeways: Los Angeles County boasts an extensive freeway system with over
^V]NmaSUVTU-capacity roads including corridors such as I- - -
I-A_L-210.
x Major Transportation Hubs: The County is home to three commercial airports
including Los Angeles International Airport (LAX)Long Beach Municipal Airport
(LGB)and the Hollywood Burbank Airport (BUR) along with several general
AvVApVa_AVlialpm3UNaq_pyaw_mA_LaiNlApNm
lAJ\NppVN]LVlialp
a^ipa_:aaL]NyVlialp1A_AIlVN]9A]]NyVlialpN_NlA]:V]]VA^ ax
VlœN]LA_L:UVpN^A_VlialpThe -alpmaS!am_TN]NmA_L!a_T
NAJUwUVJU
are two of the busiest ports in the United States and vital for national and
international tradeAlNA]maV_!am_TN]Nmaq_pyLLVpVa_A]]y!am_TN]Nm
Union Station serves as the largest passenger rail station on the west coast.
x %pUNl3lA_mialpApVa_#Npwal\mThe county includes robust passenger rail
busA_LiAlAplA_mVp mympN^mA]a_TwVpUSlNVTUplAV]mympN^memerging mobility
options such as taxis and rideshare servicesand enhanced bicycle networks.
3UVmJa^ilNUN_mVvN_Npwal\VmpUNIAJ\Ia_NSalLAV]yJa^^qpV_T SlNVTUp
^avN^N_pA_LN^NlTN_JylNmia_mNAJlammpUNlNTVa_
6.13.3 Extent
The scope of transportation incidents spans multiple modes of travel and can have
widespread consequences across the county’s integrated infrastructure.Road incidents
may include multi-vNUVJ]N Ja]]VmVa_m UA|AlLaqm ^ApNlVA] miV]]m A_L laALwAy œlNm
impacting multiple vehicles with potential delays in emergency responses.
x 0AV]LVmlqipVa_mJA_V^iNLNJa^^qpNlA_LSlNVTUpmNlvVJNmV^iAJpV_TIapU]aJA]
transit and regional connectivity.
x Air and maritime incidents—such as delays at major airports or disruptions at port
facilities—JA_mVT_VœJA_p]yASSNJpJa^^NlJNmqii]yJUAV_mA_LiqI]VJmASNpy
x Cascading effects across interconnected transportation modes may exacerbate
Ja_TNmpVa_A_LmplAV_ALLVpVa_A]V_SlAmplqJpqlNmympN^mmqJUAmiawNlwApNl
and emergency communications.
The extensive and interdependent nature of these networks means that an incident in
a_NAlNAJA_kqVJ\]yV_ŔqN_JN^q]pVi]NplA_mialpApVa_mympN^m
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6.13.4 History
Los Angeles County has a long record of transportation-related incidents that have
disrupted mobility and commerce.
x 9V_JN_p3Ua^Am
lVLTNVlN A semi-truck carrying lithium-ion batteries
avNlpql_NLA_LJAqTUpœlNJAqmV_TpUNIlVLTNpaINJ]amNLSalmNvNlA]LAym
x 2023 I-10 Freeway Fire: œlNV_AiA]]NpyAlLIN]awpUN-10 freeway in
Downtown Los Angeles caused an eight-day closure for repairs and major
cascading disruptions.
x 2020 Delta Air Lines Flight 89 Fuel Drop: 1Ualp]yASpNlpA\NaSSSla^!;A
Boeing 777 encountered engine problems and conducted a fuel dump over
iaiq]ApNLAlNAmV_[qlV_TavNl iNai]Na_pUNTlaq_L
x UApmwalpU"Npla]V_\NlAV]^N_p A Metrolink passenger train collided
wVpUA4_Va_-AJVœJSlNVTUpplAV_V_[qlV_TavNliNai]NA_LJAqmV_T LNApUm
x 2007 Newhall Pass Tunnel Fire: A multi-vehicle collision involving over 30
vNUVJ]NmJAqmNLAœlNwVpUV_pUNpq__N]V_[qlV_TiNai]NA_LJAqmV_TLNApUm
The historical record reinforces the need to learn from previous events to enhance
future preparedness and resilience.
6.13.5 Probability
The likelihood of transportation incidents in Los Angeles County remains elevated due
to several converging factors V_J]qLV_TIqp_ap]V^VpNLpa
x VTULAV]yplASœJva]q^Nma_SlNNwAymA_LAlpNlVA]mV_JlNAmNpUNlVm\aS^q]pV-
vehicle accidents and congestion-related incidents.
x Aging infrastructure—V_J]qLV_TIlVLTNmlaALmqlSAJNmA_LlAV]mympN^m—creates
AiNlmVmpN_plVm\aSSAV]qlNiAlpVJq]Al]yq_LNlNxplN^NwNApUNlJa_LVpVa_mA_L
during peak usage periods.
x 3UNJaq_py¯mla]NAmA^A[alUqISalSlNVTUpA_LJa^^qpNlplASœJ^NA_mpUApNvN_
minor incidents can escalate rapidly into larger disruptions.
x The frequent movement of hazardous materials and the increasing reliance on
just-in-time delivery systems further elevate the risk of incidents with potentially
severe consequences.
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3aTNpUNlpUNmNSAJpalmJa_plVIqpNpaAJa_mVmpN_p]yUVTUilaIAIV]VpyaSplA_mialpApVa_
incidents impacting the region.
6.13.6 Vulnerability
The vulnerability of Los Angeles County’s transportation system is compounded by its
interdependent design and its critical role in the regional economy.
x Limited redundancy in key corridors means that a disruption on one freeway or
rail line can quickly overload alternate routes.
x TV_T A_L avNlIqlLN_NL V_SlAmplqJpqlN Vm ]Nmm lNmV]VN_p pa NxplN^N NvN_pm
leading to longer recovery times after incidents.
x The county’s economic dependence on uninterrupted transportation for daily
Ja^^qpV_T A_L Ja^^NlJVA] SlNVTUp V_JlNAmNm NxiamqlN pa mVT_VœJA_p ]ammNm
during disruptions.
x a^i]Nx V_pNlLNiN_LN_JVNm INpwNN_ plA_mialpApVa_ mympN^m N^NlTN_Jy
mNlvVJNmA_LapUNlJlVpVJA]mNJpalm^A\NpUN_Npwal\UVTU]ymN_mVpVvN pa
cascading failures.
3UVm mympN^VJ vq]_NlAIV]Vpy JA]]m Sal JaalLV_ApNL ^q]pV-agency efforts to bolster
resilience and implement proactive mitigation measures.
6.13.7 Impacts
Transportation incidents can produce both immediate and long-lasting effects on
iqI]VJmASNpyJa^^NlJNA_LavNlA]]kqA]VpyaS]VSN
1.3lASœJ A_L "aIV]Vpy Disruptions can lead to severe congestion affecting
Uq_LlNLmaSpUaqmA_LmaSJa^^qpNlmA_LSlNVTUpvNUVJ]NmLN]AyV_TN^NlTN_Jy
services and disrupting daily operations.
2.Economic Loss: Interruptions in the movement of goods and people can result
V_ mqImpA_pVA] œ_A_JVA] ]ammNm V^iAJpV_T ]aJA] IqmV_NmmNm A_LpUN IlaALNl
regional economy.
3.Public Safety: Extended delays in emergency response and Emergency
Medical Services (EMS) transport times.
4.Cascading Disruptions: _V_JVLN_pV_a_N^aLNNTA^A[alUVTUwAy
J]amqlN JA_lVii]NpUlaqTUpUNplA_mialpApVa__Npwal\ASSNJpV_TlAV]AVlA_L
maritime operations simultaneously and complicating recovery efforts.
These impacts highlight the critical need for robust mitigation strategies to manage
both direct and indirect consequences of transportation incidents.
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6.13.8 Summary
Los Angeles County’s transportation network is among the most extensive and complex
V_ pUN _ApVa_ mNlvV_T ^V]]Va_m aS lNmVLN_pm A_L q_LNliV__V_T AvVpA]NJa_a^VJ
NJamympN^ 3UN LVvNlmN plA_mialpApVa_ ^aLNm wUV]N SAJV]VpApV_T ^aIV]Vpy A_L
Ja^^NlJNA]maJlNApNvq]_NlAIV]VpVNmLqNpaavNl]AiiV_TV_SlAmplqJpqlNA_LUVTUplASœJ
volumes.
x TV_T V_SlAmplqJpqlN Jaqi]NL wVpU pUN Ja_pV_qaqm ^avN^N_p aS UA|AlLaqm
^ApNlVA]mA_LpUNV_JlNAmV_TilNmmqlNmaS LAV]yqmATNJa_plVIqpNmpaAUVTU
probability of incidents.
x Historical data demonstrate that even localized incidents can have far-reaching
V^iAJpm V_J]qLV_T ila]a_TNL plASœJ Ja_TNmpVa_ NJa_a^VJ LVmlqipVa_m A_L
public safety challenges.
_Ja_J]qmVa_^VpVTApV_TplA_mialpApVa_V_JVLN_plVm\mV_!am_TN]Nmaq_pylNkqVlNm
A_V_pNTlApNLJaq_pywVLNAiilaAJUpUApJa^IV_NmV_SlAmplqJpqlNqiTlALNmN_UA_JNL
N^NlTN_Jy lNmia_mN A_L ilaAJpVvN ^AV_pN_A_JN mplApNTVNm LLlNmmV_T pUNmN
challenges Vm NmmN_pVA] pa mASNTqAlL iqI]VJ mASNpy N_mqlN NJa_a^VJ mpAIV]Vpy A_L
maintain the region’s critical mobility infrastructure.
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6.14 Public Health Emergencies
6.14.1 Nature
Public health emergencies in Los
Angeles County encompass a broad
miNJplq^ aS iapN_pVA] UA|AlLm
including infectious disease
aqpIlNA\m N_vVla_^N_pA] UNA]pU
UA|AlLm A_L UN^VJA]
Va]aTVJA]
0ALVa]aTVJA] #qJ]NAl xi]amVvNm
(CBRNE) hazards. Given the county's
LVvNlmN iaiq]ApVa_ qlIA_ LN_mVpy
A_L NJa_a^VJ mVT_VœJA_JN iqI]VJ
health hazards require a coordinated
response among government
ATN_JVNmUNA]pUJAlNV_mpVpqpVa_mA_L
community partners.
Public health emergencies refer to
V_JVLN_pmpUApiamNAmVT_VœJA_p
threat to the health of a population.
These includeIqpAlN_ap]V^VpNLpa:
x -A_LN^VJmNT%9-_ŔqN_|A
x
VapNllalVm^NT_pUlAx1^A]]iaxIapq]Vm^)
CouCouCouCouCouCouCouCouCouCouCCoooCouCouCouCCouCouCCouCouCououCouCoCooCouoCouCoooCoCouuoouCuouCCntyntyntyntyyntyyntnttyntynnnnnnntntytynn ofofoffoffofffffffffofooffffo LoLoLoLooooooLoLoLLLLooLoLLLLoooLoLLLoooooLoLLoooLLLooooooLLLLoooLLLLLLLoooooLLLLLLLoooLLLooooooLLLoooooooooLLLoooooooLLLooooooLLoooooooLooooooooLLLooooooooooLoooooooooooooooooooooooLooLoooosAsAAAsssAAsAAsAAAsAsAAsAAssAAsAsAsAsAsAsssAAAAsssAsAAsAsAsAAsAsAAAAAssAAAssAAAAAAAAAAAAsAssAAAAssAAsssssAsAAsAsAsAssssAssAAAAAAAAAsAAAAAAAAAAAAAsssAAAAAAAAAAssssssssAAAAAAAAAssssssssssssAAAAAAsAAAs s AAs As ngnngnggeeeegeengnnnggnggngeeeegegeeeegennnggngngggegegeeeeeegenggggggeeeeengennnnnnngggggggngengengegengengennngengengegggeeengengenngengengeggennnnnngegnnnngennngngeeennnnnneeeeengnnngeegennneeeennneeeeneeengellllllllllllllelesslleseeeeeeeeeeeesssslesesesllleeeeleeesesleslesesesssslleeeesleslesesssesslessleslelllesesssssslesslesesesesessssesss
AAAAAAAAAAlAlllAlllAAAAAAAAAAll-------HaHaHaHazazazazzzzzzzzzzHzHaaHaHaHHHaazHaHaHaaazzHaHaaradardardardrdarddrdddardardardardaardrdrdrdadarrrddrddsss MMMMMMMMMMMMMMMMMMMMMMMMsMMMsMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMssMs MMMMMMMMMMMMsMMMsMsMMMMMsMMMMMMssMMMMMMMMMMMsssMMMMMMsssMMMMMMMMMMssss MMMMMMMMsssMMMMMMMssMMMMsMMMMMMMMssssssMss s s Ms MMMMMMsssssMMMMMs MMMMMMMssssss MMMMMMMMs MMMMMMMsss MMMMMMMMMMMMMMMssMMMMMMMMMMMMMMMMsssssMMMMMMMMMMitiitittiitiiiiiitiiititiitiiittttiiiittttiititiiittitititiiiiiiiiiitgatgagatgatgatgatgggggaatgatgggggagggagagggggggggggggaaaaaatgatgatgatgatgggaaaaaaaaaatattggggggggggaaaaaaaaaaatggggaaaaaaatatatattattttgggaaaaaatatataattttaaaatatatatttttgggaaaataaataatattttgaagaggaaaaaattttgaaaaaattatatattataatattaaaattaaaagaagiiiiiooooonononoionononnniioononoonononononnoonononnonononononoonionononooonioiononooionionioniooooioooionioioiiooniiiooiiioooonioiiooiionionionnniionn PPPPPPPPlaPlaPPPPPPPPPPPPPPPPPPPPPPPn
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x Vector-Ial_NLVmNAmNmNT:Nmp#V]N9Vlqm?V\A
x Foodborne and waterborne illnesses
x Chemical and radiological exposure
x Climate-lN]ApNLUNA]pUpUlNApmNTNxplN^NUNApiaalAVlkqA]VpywV]LœlNm
The County of Los Angeles Department of Public Health (DPH) and the Emergency
"NLVJA]1NlvVJNmTN_Jy"1 Ja]]AIalApNpa^a_VpalpUlNApmilNvN_paqpIlNA\mA_L
mitigate impacts when emergencies arise.
6.14.2 Location and Extent
Los Angeles CountyUa^NpaavNl9.7 ^V]]Va_lNmVLN_pmVmpUN^ampiaiq]aqmJaq_py
in the United States. Its diverse geography VNqlIA_JaAmpA]^aq_pAV_aqmA_LlqlA])
and demography lead to a range of public health vulnerabilities.
-qI]VJUNA]pUN^NlTN_JVNmJA_alVTV_ApNSla^]aJA]lNTVa_A]_ApVa_A] al T]aIA]
maqlJNmV^iAJpV_TmiNJVœJ_NVTUIalUaaLmalpUNN_pVlNJaq_py3UNNxpN_paSiqI]VJ
health threats varies based on:
x 3UN_ApqlNaSpUNpUlNApmqJUAmplA_m^VmmVa_Ly_A^VJmalAvAV]AIV]VpyaS^NLVJA]
countermeasures.
x Population density (higher risks in urban centers for communicable diseases)
x Access to healthcare infrastructure
x _vVla_^N_pA]Ja_LVpVa_mAVlia]]qpVa_NxplN^NUNApNvN_pm
6.14.3 History
Public health emergencies in Los Angeles County have included:
x 2022 Monkeypox Outbreak
o iilaxV^ApN]y JAmNmwNlNlNialpNLV_!am_TN]Nmaq_py
x COVID-19 Pandemic (2020–Present)
o %vNl ^V]]Va_ JAmNm UamiVpA]V|ApVa_m A_L LNApUm
reported in the county alone.
x 2018 Hepatitis A Outbreak
o -lV^AlV]y ASSNJpV_T q_UaqmNL iaiq]ApVa_m lNkqVlV_T ^Amm vAJJV_ApVa_
efforts.
x 2016-2017 West Nile Virus Outbreaks
o Multiple cases of mosquito-borne infections leading to severe illness and
fatalities.
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x 2015-2016 Zika Virus Outbreak
o No cases of local mosquito-Ial_NplA_m^VmmVa_IqppUNlNwNlNJAmNm
lNialpNLV_pUNaq_pywVpUINV_TplAvN]-related.
x 2015 Meningococcal Disease Cluster
o An outbreak among men who have sex with men (MSM) led to a targeted
vaccination campaign.
x #_ŔqN_|A-A_LN^VJ
o 3UaqmA_LmaSUamiVpA]V|ApVa_mmJUaa]mA_LIqmV_NmmNmASSNJpNL
6.14.4 Probability and Emerging Risks
3UN3UlNApA_LA|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p30 VLN_pVœNm that
pandemics and bioterrorism remain high-probability threats. Future public health risks
also include:
x Emergence of infectious diseases driven by global travel and climate change.
x Increased incidence of heat-related illnesses amid rising temperatures.
x Increased prevalence of respiratory diseases due to declining air quality.
x Rise of antimicrobial-resistant infections due to overuse of antibiotics.
The County of Los Angeles DPH continually assesses health threats and updates
preparedness plans to address evolving concerns.
6.14.5 Vulnerability and Systemic Impacts
Certain populations in Los Angeles County may be disproportionately affected by
public health emergencies:
x At-lVm\iaiq]ApVa_m^AyINLVSSNlN_pSalLVSSNlN_pUA|AlLmINSalNLqlV_TA_L
after an emergency. It is important to assess each hazard in turn to identify those
who may be disproportionately affected to improve preparedness and response
efforts.
-qI]VJUNA]pUN^NlTN_JVNmmplAV_pUNUNA]pUJAlNmympN^LVmlqipNJa_a^VJAJpVvVpyA_L
create mental health burdens. The 2024 THIRA report noted that:
x Healthcare infrastructure overload is a major concern during pandemics.
x Potential economic loss from business closures during a prolonged public
health crisis could exceed billions of dollars.
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6.14.6 Mitigation Strategies and Preparedness Efforts
Los Angeles County employs several mitigation and preparedness strategies:
x Mass Vaccination Campaigns
o __qA] Ŕq mUapm %9- vAJJV_ApVa_m A_L aqpIlNA\-miNJVœJ
immunization efforts.
x Points-of-Dispensing (POD) sites
o Disease Surveillance & Early Warning Systems
x Syndromic surveillance for emerging threats.
o Targeted sampling surveillance.
x Healthcare Infrastructure Strengthening
o Expanding hospital capacity Sal^NLVJA]mqlTN and emergency medical
resources.
x Community Outreach & Public Health Education
o Disseminating critical information in multiple languages.
x Emergency Stockpiles (Strategic National Stockpile(SNS))
o Ni]ay^N_paSA_pVIVapVJmA_pVvVlA]mA_LiNlma_A]ilapNJpVvNNkqVi^N_p
(PPE) in crisis situations.
x Coordination with Federal & State Agencies
o Collaboration wVpU"A_LpUNA]VSal_VANiAlp^N_paS-qI]VJ
Health to enhance response capabilities.
x Anthrax Threat Simulations
o The County of Los Angeles Metro system assessed as a high-risk area for
bioterrorism response.
6.14.7 Summary
-qI]VJ UNA]pU N^NlTN_JVNm iamN mVT_VœJA_p JUA]]N_TNm paLos Angeles County
V^iAJpV_TUNA]pUJAlNmympN^mvq]_NlAI]Niaiq]ApVa_mA_LNJa_a^VJmpAIV]Vpy:UV]N
the COVID-iA_LN^VJilavVLNLA^A[almplNmmpNmpSallNmia_mNNSSalpma_TaV_T
ilNiAlNL_NmmmqlvNV]]A_JNA_L^VpVTApVa_mplApNTVNmAV^pailapNJplNmVLN_pmSla^
future threats.
Ny3A\NAwAym
x Los Angeles County SAJNm LVvNlmN UNA]pU pUlNApm V_J]qLV_T iA_LN^VJm
IVapNllalVm^A_LJ]V^ApN-related illnesses.
County of Los Angeles
All-Hazards Mitigation Plan
Page 151 of 204
x Vulnerable populations may suffer disproportionate impacts during public
health crises.
x -lNiAlNL_NmmNSSalpmSaJqma_mqlvNV]]A_JNvAJJV_ApVa_N^NlTN_JylNmia_mN
and coordination with federal and state partners.
x qpqlNpUlNApmV_J]qLNN^NlTV_TV_SNJpVaqmLVmNAmNmUNAp-lN]ApNLV]]_NmmNmA_L
antimicrobial resistance.
yJa_pV_qV_TV_vNmp^N_pmV_iqI]VJUNA]pUilNiAlNL_NmmLos Angeles County aims to
reduce risks and strengthen resilience against future health emergencies.
County of Los Angeles
All-Hazards Mitigation Plan
Page 152 of 204
7 Mitigation Strategy
County of Los Angeles
All-Hazards Mitigation Plan
Page 153 of 204
7.1 Mitigation Strategy Overview
The Mitigation Strategy section of the All-Hazard Mitigation Plan (AHMP) presents Los
Angeles County’s strategic blueprint for reducing risks and vulnerabilities posed over
pUN]a_TpNl^AmmaJVApNLwVpUpUNUA|AlLmVLN_pVœNLV_pUNA|AlLLN_pVœJApVa_And
0Vm\ mmNmm^N_p mNJpVa_ 3UN mplApNTVNm VLN_pVœNL V_ pUVm mNJpVa_ LlVvN ^VpVTApVa_
activities based on existing capabilities while also identifying areas of potential future
V_vNmp^N_p pa IqV]L lNmV]VN_JN AJlamm Ja^^q_VpVNm JlVpVJA] SAJV]VpVNm A_L apher
infrastructure within Los Angeles County.
7.2 Mitigation Goals and Objectives
Mitigation goals are the long-term vision that the County hopes to achieve by
V^i]N^N_pV_TpUNvAlVaqm^VpVTApVa_mplApNTVNmLNmJlVINLV_pUVm"-AmwN]]AmpUN
broad guidelines that have shaped mitigation strategy development.
x aA] Protect life, property, infrastructure, the environment, and the
economy pUlaqTUNkqVpAI]N^VpVTApVa_mplApNTVNmAV^NLAplNLqJV_TlVm\m
of natural and human-caused hazards.
o Objective 1-_pNTlApNvq]_NlAI]Niaiq]ApVa_mV_J]qLV_TiNai]NwVpU
JJNmm A_L q_JpVa_A] #NNLm # V_pa pUN V^i]N^N_pApVa_ aS A_y
potential mitigation actions.
o Objective 1-2: Implement mitigation strategies that enhance resilience to
LVmAmpNlV^iAJpmAJlammlNmVLN_pVA]AlNAmJa^^NlJVA]AlNAmV_SlAmplqJpqlN
high-UA|AlLiapN_pVA]LA^mA_LapUNlJlVpVJA]SAJV]VpVNm
o Objective 1- _Sal^ mplApNTVJ V_vNmp^N_pm V_ J]V^ApN ALAipApVa_
LNvN]ai^N_p A_L lNLNvN]ai^N_p pUAp AlN JN_pNlNL V_ NkqVpy A_L
resilience.
x aA]_UA_JNJa^^q_Vpy-wide partnerships in hazard mitigation across
all levels of government, the private sector, and the public.
o Objective 2-1: Build a culture of disaster resilience and awareness of local
UA|AlLmpUlaqTUiqI]VJN_TATN^N_pNLqJApVa_A_LaqplNAJU
o Objective 2-2: Strengthen direct coordination among Los Angeles
County Operational Area partners to unify efforts for mitigation activities.
o Objective 2-3: Utilize a whole community approach to address disparities
V_aqpJa^NmiamNLIypUNUA|AlLmVLN_pVœNLV_pUVm"-
x aA] Enhance planning, response, and recovery through hazard
VLN_pVœJApVa_AmmNmm^N_p^VpVTApVa_A_LlNmV]VN_JNAJpVvVpVNm
County of Los Angeles
All-Hazards Mitigation Plan
Page 154 of 204
o Objective 3-1: Establish and maintain coordination between hazard
mitigation activities and other emergency management functions.
o Objective 3-2: Integrate hazard mitigation activities into preparedness for
future large-scale planned events within Los Angeles County.
x aA]_mqlNN]VTVIV]VpySal"TlA_pSq_LV_Tpa^AxV^V|NNkqVpAI]N
investment in hazard mitigation actions.
o Objective 4-1: Continue to meet all requirements for existing hazard
mitigation grant programs used by the County.
o Objective 4-2: Expand the County’s ability to participate in grant
programs not currently utilized by the County.
7.2.1 Changes in Mitigation Goals
The AHMP Advisory Committee reviewed the 2020 AHMP goals and updated them to
lNŔNJppUN^ampJqllN_pCaq_pyJa_JNl_mA_LilValVpVNm3UNlNSalNpUN "-has
introduced new goals and objectives to build a more resilient community. Table 7-1
IN]aw Ja^iAlNmpUN "-TaA]mwVpUilNvVaqm"-TaA]mA]]apUNl
goals above are new goals and objectives developed by the AHMP Advisory
Committee.
Mitigation priorities change through time depending on the type of disaster impacting
!am_TN]Nmaq_pyvq]_NlAIV]VpypUNmplApNTVNmV^i]N^N_pNLAmwN]]AmapUNl_NNLm
of the community. Priorities are also made based on current countywide Threat and
Ha|AlLLN_pVœJApVa_A_L0Vm\mmNmm^N_p30 mpqLVNm#ApVa_A] 0Vm\ _LNx
mmNmm^N_p1pApNA|AlL"VpVTApVa_-]A_1"- A_L other local plans and guides. The
previous 2020 AHMP integrated hazard data into several operational plans including
but not li^VpNLpapUNN_NlA]-]A_%iNlApVa_A]lNA^NlTN_Jy%iNlApVa_m-]A_
%%- amongst others. Addressing these changes will help to address Los Angeles
County hazard priorities and to have mitigation strategies focused on the hazards that
impact the region at most. The plan also added additional hazards and addressed a
larger vulnerable population.
Table 7-"VpVTApVa_aA]4iLApNm
aA]mLLlNmmNLV_
2020 AHMP
aA]mSal -2030
Planning Period
Changes
Build a culture and
practice disaster
resilience
Goal 2 (see above). aA]NxiA_LNL
previous goal
integrated as an
County of Los Angeles
All-Hazards Mitigation Plan
Page 155 of 204
aA]mLLlNmmNLV_
2020 AHMP
aA]mSal -2030
Planning Period
Changes
objective under Goal 2
in the current AHMP.
NppNli]A_SallNmia_L
paA_LlNJavNlSla^
hazards and disasters
V_J]qLV_TJ]V^ApNJUA_TN
LlaqTUpNAlpUkqA\N
LA^SAV]qlNŔaaL
]A_Lm]VLNpmq_A^VA_L
wV]LœlNpUApASSNJp!am
Angeles County.
Goal 3 (see above). Previous goal replaced
with new goal.
More successfully adapt
to hazards and disasters
V_J]qLV_TJ]V^ApNJUA_TN
LlaqTUpNAlpUkqA\N
LA^SAV]qlNŔaaL
]A_Lm]VLNpmq_A^VA_L
wV]LœlNpUApASSNJp!am
Angeles County.
Goal 1 (see above). Previous goal replaced
with new goal.
7.3 Existing Mitigation Capabilities
The mitigation strategies developed as part of this AHMP seek to maximize existing
^VpVTApVa_JAiAIV]VpVNmVLN_pVœNLAmJqllN_p]yAvAV]AI]NwVpUV_pUN!am_TN]Nmaq_py
%iNlApVa_A]lNA3UNmNNxVmpV_TJAiAIV]VpVNmUAvNINN_qiLApNLpalNŔNJpJUA_TNmV_
humA_pNJU_VJA]œ_A_JVA]]NTA]lNTq]ApalyNLqJApVa_A_LaqplNAJUlNmaqlJNmmV_JN
the 2020 AHMP.
County of Los Angeles
All-Hazards Mitigation Plan
Page 156 of 204
7.3.1 qpUalVpVNm-a]VJVNmA_L!NTA]0NTq]Apaly0NmaqlJNm
There are several NxVmpV_TAqpUalVpVNmia]VJVNmA_LapUNl]NTA]allNTq]ApalylNmaqlJNm
applicable to hazard mitigation efforts in Los Angeles County. From the County Code
aS%lLV_A_JNmpaJa^i]NpNLi]A_mpUNmNSal^pUNJal_Nlmpa_NaSUA|AlL^VpVTApVa_
activities by provVLV_T A Saq_LApVa_ laapNL V_ LApA lNmNAlJU i]A__V_T 3NJU_VJA]
Ecological Knowledge (TEK) provided by our state and locally recognized indigenous
Ja^^q_VpVNmA_LN]NJpNLaSœJVA]m¯AqpUalVpyThe County aims to expand and improve
upon pUNmNVLN_pVœNLJAiAIV]VpVNmIyALaipV_TpUVm"-a_JNAiilavNLV_papUN
Safety Element of the Los Angeles County General Plan. This action will contribute to
the County’s ability to be considered for an additional cost-share on Public Assistance
projects through the California Disaster Assistance Act. Table 7-2 provides an overview
aSNxVmpV_TJAiAIV]VpVNmlN]ApNLpaAqpUalVpVNmia]VJVNmA_L]NTA]lNTq]ApalylNmaqlJNm
Table 7-2 qpUalVpVNm-a]VJVNmA_L!NTA]0NTq]Apaly0NmaqlJNm
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
Los Angeles
County
Operational
Area
Emergency
Operations
Plan (2023)
Establishes the coordinated
emergency management system
within the Los Angeles County
%iNlApVa_A]lNApailNiAlNSal
lNmia_LpaA_LlNJavNlSla^pUN
effects of large-scale emergencies
lNTAlL]NmmaSJAqmN]aJApVa_al
complexity.
All-Hazard No
Los Angeles
County General
Plan (2024)
Provides the policy framework for
how and where the
unincorporated County will grow
through the year 2035.
All-Hazard Yes
Los Angeles
County
Comprehensive
Floodplain
0NvVNwmNxVmpV_TŔaaLi]AV_
management programs in the
County and recommends
enhancements to them through 35
Flood
Land
Movement
Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 157 of 204
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
Management
Plan (2021)
mitigation actions. This plan is
currently being reviewed and
updated with completion targeted
for early 2026.
Los Angeles
County
Comprehensive
Floodplain
Management
Plan Repetitive
Loss Area
Analysis (2021)
Analyzes Repetitive Los Areas
within Los Angeles County and
Sq]œ]]ma^^q_Vpy0ApV_T1ympN^
requirements.
Flood
Land
Movement
Yes
County of Los
Angeles
Floodplain
Management
Plan Progress
Report (2024)
Provides an annual update on the
implementation of the action plan
VLN_pVœNLV_pUNa^ilNUN_mVvN
Floodplain Management Plan and
on the implementation and
evaluation of outreach projects.
Flood
Land
Movement
Yes
County of Los
Angeles
Repetitive Loss
Area Analysis
Progress Report
(2023)
Provide an annual update on the
implementation of the action plan
VLN_pVœNLV_pUNRepetitive Loss
Area Analysis to ensure there is a
continuing and responsive
planning process.
Flood Yes
Los Angeles
County Fire
Plan (2023)
NmJlVINmpUNwV]LœlN
N_vVla_^N_pUVmpalyA_LilN-œlN
management strategies to
N_UA_JNpUNilapNJpVa_aS]VvNm
ilaiNlpyA_L_ApqlA]lNmaqlJNm
Sla^wV]L]A_LœlN
:V]LœlN Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 158 of 204
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
Los Angeles
County 2045
Climate Action
Plan (2024)
Delineates the County’s path
toward
meeting the goals of the Paris
Agreement and achieving carbon
neutrality for unincorporated
Los Angeles County.
:V]LœlN
Extreme
Heat
Drought
Flooding
Yes
Our County:
Los Angeles
Countywide
Sustainability
Plan (2019)
Outlines how local governments
and stakeholders can enhance the
well-being of all County
communities while adapting to
climate change and reducing
damage to the natural
N_vVla_^N_piAlpVJq]Al]ySaJqmV_T
on communities disproportionately
burdened by pollution.
:V]LœlN
Extreme
Heat
Drought
Flooding
Yes
Los Angeles
County
Floodplain
Management
Ordinance
Aims to minimize public and
ilVvApN]ammNmlNmq]pV_TSla^ŔaaL
conditions via uniformly applied
lNTq]ApVa_mV_ŔaaLila_N
^qLŔawalŔaaLlN]ApNLNlamVa_
areas.
Flood
Land
Movement
Yes
Los Angeles
County Code –
Title 32: Fire
Code
To build a new structure (or an
addition equal to or greater than
ÈaSNxVmpV_TmkqAlNSaapATN
the Los Angeles County Fire Code
lNkqVlNmlNvVNwaSVpm]aJApVa_pyiN
aSJa_mplqJpVa_paiaTlAiUym]aiN
amount and arrangement of
vNTNpApVa_A_LavNlA]]site
:V]LœlN Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 159 of 204
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
settings—in order to create
defensible space necessary for
NSSNJpVvNœlNilapNJpVa_aSUa^Nm
in High Fire Severity Zones.
Los Angeles
County Code –
Title 22:
Planning and
Zoning
Establishes the regulations
governing land use and
LNvN]ai^N_pA_LLNœ_Nm|a_V_T
for unincorporated Los Angeles
County. Includes the Hillside
Management Area Ordinance
UAipNl pUN0NmVLN_pVA]
NmVT_1pA_LAlLm%lLV_A_JNA_L
the Hillside Design Guidelines.
These include requirements for
development in Hillside
"A_ATN^N_plNAmwUVJUAlN
LNœ_NLAmAlNAmwVpU Èal
greater natural slopes. The
TqVLN]V_NmV_J]qLNmiNJVœJA_L
measurable design techniques that
JA_INAii]VNLpalNmVLN_pVA]
commerciA]V_LqmplVA]A_LapUNl
types of projects.
:V]LœlN
Earthquake
Land
Movement
Yes
Los Angeles
County Code –
Title 31: Green
Building
Standards
Code
Enhances the design and
construction of buildings via
building concepts with positive (or
reduced negative) environmental
V^iAJpmA_LN_JaqlATNm
sustainable construction practices
Extreme
Heat
Drought
Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 160 of 204
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
AJlammi]A__V_TA_LLNmVT_
N_NlTyNSœJVN_JywApNl
Ja_mNlvApVa_^ApNlVA]A_L
lNmaqlJNNSœJVN_JyA_L
environmental air quality.
Los Angeles
County Brush
Clearance
Program
Legally declares both improved
and unimproved properties a
iqI]VJ_qVmA_JNA_LwUNlN
_NJNmmAlylNkqVlNmpUNJ]NAlA_JN
of hazardous vegetation thereby
creating defensible space for
NSSNJpVvNœlNilapNJpVa_aS
ilaiNlpy]VSNA_LpUNN_vVla_^N_p
The Brush Clearance Program is a
joint effort between the County of
Los Angeles Fire Department and
the County of Los Angeles
Department of Agricultural
Commissioner/Weights and
Measurem:NNLA|AlLA_L-Nmp
Abatement Bureau (Weed
Abatement Division).
:V]LœlN Yes
Los Angeles
County Code –
Title 26:
Building Code
Provides minimum standards to
regulate pUNLNmVT_Ja_mplqJpVa_
V_mpA]]ApVa_kqA]VpyaS^ApNlVA]m
qmNaJJqiA_Jy]aJApVa_A_L
^AV_pN_A_JNaSA]]IqV]LV_Tm
mplqJpqlNmTlALV_TA_LJNlpAV_
equipment. Regulates construction
Earthquake
:V]LœlN
Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 161 of 204
Authority,
Policy, or
0NmaqlJN
Description Hazards
Addressed
Potential to
Affect
Development
near a known active earthquake
SAq]pUAipNl1NJpVa_ pUN
materials and construction
methods for construction in a
Wildland-Urban Interface (WUI)
VlNlNAUAipNl mplqJpqlA]
design as it relates to earthquake
UA|AlLmUAipNl1NJpVa_
16 lNiAVlaSJNlpAV_IqV]LV_TmV_
High Earthquake Damage Areas
UAipNl NAlpUkqA\NUA|AlL
reduction for concrete tilt-up
buildings (Chapter 95) and
unreinforced masonry buildings
UAipNl A^a_TapUNlm3UN
Building Code also includes
provisions for emergency housing
during a proclaimed emergency.
7.3.2 Human and Technical Resources
Existing human and technical resources across County Departments enable the
aq_pypai]A_^A_ATNJa_LqJpA_LNxNJqpNVpmwVLNlA_TNaSUA|AlL^VpVTApVa_
activities. The resources below represent a high degree of expertise in all facets of
hazard mitigation available to support mitigation activities. The County aims to
NxiA_LA_LV^ilavNqia_pUNmNVLN_pVœNLJAiAIV]VpVNmIyNxiA_LV_Tpotential
hazard training opportunities available to the Los Angeles County Operational Area.
LLVpVa_A]]yAmvAlVaqmmpecial events are scheduled in Los Angeles County over the
_NxpœvNyNAlmpUNaq_pyshould seek to expand coordination and technical
resources lN]ApNLpa^AmmvVa]N_JNJyINlA_LapUNlmiNJVA]NvN_p-related hazards.
County of Los Angeles
All-Hazards Mitigation Plan
Page 162 of 204
Table 7-3 provides an overview of existing capabilities related to human and technical
resources.
Table 7-3 q^A_A_L3NJU_VJA]0NmaqlJNm
0NmaqlJN Department/Agency -lV_JViA]JpVvVpVNm0N]ApNLpaA|AlL
Mitigation
Emergency
Management
Coordinator(s)
Los Angeles County
%SœJNaS^NlTN_Jy
Management
x Maintains and updates the Los
Angeles County Operational Area
Emergency Operations Plan and Los
Angeles County All-Hazard
Mitigation Plan.
x Coordinates local response and
recovery activities in the Emergency
Operation Center A_LV_pUNœN]L
x Wal\mJ]amN]ywVpU]aJA] mpApNA_L
federal partners to support planning
trainingNxNlJVmNiqI]VJV_Sal^ApVa_
and resource coordination.
_TV_NNlm
Building
_miNJpalm
Code
Enforcement
%SœJNlm VlN
"AlmUA]]mA_L
Other Technical
Staff
Los Angeles County
Public Works and Fire
Department
x %vNlmNNmpUNNSSNJpVvNNSœJVN_pSAVl
and safe enforcement of County of
Los Angeles Building and Fire
Codes.
_TV_NNlm
Construction
Project
"A_ATNlmA_L
Other Technical
Staff
Los Angeles County
Public Works
x Provides direct (or contract) JVvV]
mplqJpqlA]A_L^NJUA_VJA]
N_TV_NNlV_TmNlvVJNm including
Ja_plAJpila[NJpA_LJa_mplqJpVa_
management.
_TV_NNlm
Project
Los Angeles County
Public Works
x Maintains and operates a wide range
of local equipment and facilities and
assists members of the public by
County of Los Angeles
All-Hazards Mitigation Plan
Page 163 of 204
0NmaqlJN Department/Agency -lV_JViA]JpVvVpVNm0N]ApNLpaA|AlL
Mitigation
"A_ATNlm
Equipment
OiNlApalm
Maintenance and
Construction
StaffA_L%pUNl
Technical Staff
ilavVLV_TmqSœJVN_pJ]NA_SlNmUwApNl
reliable mNwNlmNlvVJNmmplNNp
^AV_pN_A_JNmpal^LlAV_ATN
mympN^mmplNNpJ]NA_V_TmplNNp]VTUpm
A_LplASœJmVT_A]m
Floodplain
Administrator
Los Angeles County
Public Works
x _SalJNmpUNŔaaLi]AV_^A_ATN^N_p
ordinance ensuring that
development proposals do not
V_JlNAmNŔaaLlVm\A_LpUAp_Nw
developments are not located below
the 100-yNAlŔaaL]NvN]_ALLVpVa_
pUNŔaaLi]AV_AL^V_VmplApalVm
responsible for planning and
^A_ATV_TŔaaLlVm\lNLqJpVa_
projects throughout Los Angeles
County.
-]A__Nlm
_TV_NNlm A_L
Technical Staff
Los Angeles County
Department of
Regional Planning
x Develops and maintains the Los
_TN]Nmaq_pyN_NlA]-]A_
including the Safety Element.
x Develops area plans based on the
Los Angeles County General Plan to
ilavVLN^alNmiNJVœJTqVLA_JNSal
pUNLNvN]ai^N_paS^alNmiNJVœJ
areas.
x 0NvVNwmilaiamNLLNvN]ai^N_p
JAiVpA]V^ilavN^N_pmA_LapUNl
physical projects involving property
for consistency and conformity with
the Los Angeles County General
Plan.
x Anticipates and acts on the need for
Aii]VJAI]N_Nwi]A_mia]VJVNmA_L
code changes.
County of Los Angeles
All-Hazards Mitigation Plan
Page 164 of 204
0NmaqlJN Department/Agency -lV_JViA]JpVvVpVNm0N]ApNLpaA|AlL
Mitigation
x ii]VNmpUNAiilavNLi]A_mia]VJVNm
JaLNilavVmVa_mA_LapUNl
regulations to proposed land uses.
Procurement
Services
Manager
Los Angeles County
Internal Services
Department
x Provides a full range of municipal
œ_A_JVA]mNlvVJNmand administers
several licensing measures.
Comptroller
Personnel
Los Angeles County
Auditor – Controller
x -lavVLNmœ_A_JVA]and grant services.
County Counsel
Personnel
Los Angeles County
Counsel
x Provides legal services for the
County.
Fire Department
Personnel
Los Angeles County
Fire Department
x -lavVLNmœlNilapNJpVa_mNlvVJNm
V_J]qLV_TlNmia_mNœlNilNvN_pVa_
and mitigation activities for the
County.
Sheriff’s
Department
Personnel
Los Angeles County
Sheriff’s Department
x Provides law enforcement services in
the County.
7.3.3 Financial Resources and Programs
3UNlN AlN ^A_y NxVmpV_T œ_A_JVA] lNmaqlJNm TlA_p ilaTlA^m A_LapUNlSq_LV_T
mechanisms that enable current and future hazard mitigation activities. Sources for
these resources and programs vary widely from local funding out of the County’s
General Fund to state and federal programs that aim to help local jurisdictions
accomplish their hazard mitigation goals. The amount of funding available is variable
and project-miNJVœJSal^A_yaSpUNmNilaTlA^m1V^V]Al]yTlA_pAwAlLmAlNIAmNLa_
pUNmiNJVœJila[NJpmpUApAlNVLN_pVœNLAmpUNIAmVmSalpUNTlA_pAii]VJApVa_3AI]N-4
ilavVLNm A_ avNlvVNw aS NxVmpV_T JAiAIV]VpVNm lN]ApNL pa œ_A_JVA] lNmaqlJNm A_L
programs.
County of Los Angeles
All-Hazards Mitigation Plan
Page 165 of 204
Table 7-4 V_A_JVA]0NmaqlJNmA_L-laTlA^m
0NmaqlJNal
Program Administrator Purpose
General Fund
Chief
Executive
%SœJN
-laTlA^aiNlApVa_mA_LmiNJVœJila[NJpm
General
Obligation Bonds
Auditor -
Controller
General obligation bonds are appropriately
used for the construction and/or acquisition of
improvements to real property broadly
available to residents and visitors. Such facilities
include but are not limited to: ]VIlAlVNm
UamiVpA]m iAl\miqI]VJmASNpySAJV]VpVNmA_L
cultural and educational facilities.
Special Tax and
Revenue Bonds Controller
0NvN_qNIa_LmAlNqmNLpaœ_A_JNJAiVpA]
projects that:
1. HAvNA_VLN_pVœNLIqLTNpAlymplNA^Sal
lNiAy^N_pNTmiNJVœNLSNNmpAx
lNJNVipm
2. Generate project revenue but rely on a
broader pledge of general fund revenues to
lNLqJNIallawV_TJampmal
3. Finance the acquisition and installation of
equipment for the local jurisdiction’s
general governmental purposes.
Vegetation
Management
Program
Cal FIRE
Cost-sharing program between Cal FIRE and
private landowners which focuses on the use of
ilNmJlVINLœlNA_L/or ^NJUA_VJA]^NA_mSal
ALLlNmmV_TwV]L]A_LœlNSqN]UA|AlLmA_LapUNl
resource management issues on State
Responsibility Area (SRA) lands.
:V]LœlN
Emergency and
Mitigation Funds
Cal FIRE Administers funding from FEMA Bureau of
Land "A_ATN^N_p and U.S. Forest Service for
County of Los Angeles
All-Hazards Mitigation Plan
Page 166 of 204
0NmaqlJNal
Program Administrator Purpose
certain types of wV]LœlN emergency and
mitigation funding.
California
Residential
Mitigation
Program
California
Earthquake
Authority
Created by the California Earthquake Authority
A_LpUNavNl_al¯m%SœJNaS^NlTN_Jy
1NlvVJNm¬Earthquake Brace + Bolt: Funds to
Strengthen Your Foundation” is the œlmp
incentive program offered by the California
Residential Mitigation Program.
Public Health
Emergency
Preparedness
Cooperative
Agreement
Center for
Disease
Control and
Prevention
Funds are intended to upgrade state and local
public health jurisdictions’ preparedness and
response to IVapNllalVm^ outbreaks of
infectious LVmNAmNm and other public health
threats and emergencies.
Hazard Mitigation
Grant Program
(HMGP)
FEMA
Administered by the California Governor’s
%SœJNaS^NlTN_Jy1NlvVJNmA]%1 "-
supports pre- and post-disaster mitigation
plans and projects available to California
communities after a presidentially declared
disaster has occurred in California.
Pre-Disaster
Mitigation (PDM)
Grant Program
FEMA
Available annually as a nationally competitive
A]%1TlA_ppUN-"lA_p-laTlA^
supports pre-disaster mitigation plans and
projects.
Flood Mitigation
Assistance (FMA)
Grant Program
FEMA
Available annually as a nationally competitive
A]%1TlA_ppUN-"lA_p-laTlA^
supports pre-disaster mitigation plans and
projects.
Homeland
Security FEMA Builds and sustains preparedness technical
assistance activities in support of the four
County of Los Angeles
All-Hazards Mitigation Plan
Page 167 of 204
0NmaqlJNal
Program Administrator Purpose
Preparedness
Technical
Assistance
Program
Ua^N]A_LmNJqlVpy^VmmVa_AlNAmVN
ilNvN_pVa_ilapNJpVa_lNmia_mNlNJavNly A_L
homeland security program management.
Assistance to
VlNœTUpNlm Grant
Program
FEMA/U.S.
Fire
Administration
-lavVLNmNkqVi^N_pilapNJpVvNTNAl
N^NlTN_JyvNUVJ]NmplAV_V_TA_LapUNl
resources needed to protect the public and
emergency personnel from œlN and related
UA|AlLmvAV]AI]NpaœlNLNiAlp^N_pmA_L
_a_ASœ]VApNLN^NlTN_Jy^NLVJA]mNlvVJNm
providers.
Land and Water
Conservation
Funds
U.S.
Department of
the Interior
Supports the protection of federal public lands
and waters and voluntary conservation on
private land.
Community
Action for a
Renewed
Environment
U.S.
Environmental
Protection
Agency (EPA)
Offers means by which communities may
organize/take action to reduce toxic pollution
NTV_mpal^wApNlNpJ pUlaqTUœ_A_JVA]A_L
technical assistance. Communities create
partnerships that implement solutions to
reduce releases of toxic pollutants and that
minimize toxic exposures.
Clean Water
State Revolving
Fund
EPA
A loan program that provides low-cost
œ_A_JV_T to eligible entities on state and tribal
lands for water quality ila[NJpmV_J]qLV_TA]]
types of non-iaV_pmaqlJNwApNlmUNL
ilapNJpVa_allNmpalApVa_NmpqAly^A_ATN^N_p
ila[NJpmA_L^alNplALVpVa_A]^q_VJViA]
wastewater treatment projects.
County of Los Angeles
All-Hazards Mitigation Plan
Page 168 of 204
0NmaqlJNal
Program Administrator Purpose
Community Block
Grant Program
Entitlement
Communities
Grants
U.S.
Department of
Housing and
Urban
Development
JkqVmVpVa_aSlNA]ilaiNlpylN]aJApVa_A_L
LN^a]VpVa_lNUAIV]VpApVa_aSlNmVLN_pVA]A_L
non-lNmVLN_pVA]mplqJpqlNmJa_mplqJpVa_aS
iqI]VJSAJV]VpVNmA_LV^ilavN^N_pmNT
wApNlmNwNlSAJV]VpVNmmplNNpmneighborhood
JN_pNlmNpJ and the conversion of school
buildings for eligible purposes.
High Hazard
Potential Dams
(HHPD) Grant
Program
FEMA
PlavVLNm pNJU_VJA] i]A__V_T LNmVT_ A_L
construction assistance in the form of grants for
the rehabilitation of eligible high hazard
potential dams.
State and Local
Cybersecurity
Grant Program
FEMA
Provides funding to eligible entities to address
cybersecurity risks and threats to information
mympN^maw_NLalaiNlApNLIyala_INUA]SaS
mpApN]aJA]alplVIA]TavNl_^N_pm.
7.3.4 Education and Outreach Resources
Engagement with the communities of Los Angeles County is an important component
aS^VpVTApVa_NSSalpm3UNaq_pyaS!am_TN]NmUAm^q]pVi]N^NpUaLmSal^ApmA_L
venues to conduct outreach with community members and provide education on the
hazard landscape in Los Angeles County. These activities ensure mitigation efforts align
with community goals and include community input. Table 7-5 shows a list of existing
resources for education and outreach.
Table 7-5 LqJApVa_A_L%qplNAJU0NmaqlJNm
0NmaqlJNal
Program
Agencies Potentially
Involved Purpose
Preparedness
Fairs
%SœJNaS^NlTN_Jy
"A_ATN^N_pVlN
Engage with community
members to provide education
County of Los Angeles
All-Hazards Mitigation Plan
Page 169 of 204
0NmaqlJNal
Program
Agencies Potentially
Involved Purpose
NiAlp^N_p1UNlVSS¯m
NiAlp^N_p-qI]VJ:al\m
Board of Supervisors
on hazards found in Los
Angeles County and
emergency preparedness for
homes and businesses.
Personal Disaster
Impact Surveys
%SœJNaS^NlTN_Jy
Management
Receive input and feedback on
the hazard landscape from
community members in Los
Angeles County to inform the
2025 AHMP.
AHMP Draft
Review Surveys
%SœJNaS^NlTN_Jy
Management
Receive input and feedback on
sections of the AHMP from
community members in Los
Angeles County.
Homeless
Outreach
Services Team
(HOST)
1UNlVSS¯mNiAlp^N_p
Homelessness Services
Organizations
Conduct outreach to People
Experiencing Homelessness in
AlNAmila_NpawV]LœlNmal
ŔaaLV_TIAmNLa_wNApUNl
conditions.
Community
Emergency
Response Teams
(CERT)
Fire Department
Educate community members
about disaster preparedness
and response in their
communities.
Explorer
Programs
VlNNiAlp^N_p1UNlVSS¯m
Department
Educate youth about disaster
preparedness and response in
their communities.
Youth Climate
Commission UVNS1qmpAV_AIV]Vpy%SœJN
Educate and obtain input from
youth on climate change
impacts and mitigation efforts.
County of Los Angeles
All-Hazards Mitigation Plan
Page 170 of 204
7.3.5 National Flood Insurance Program Participation
The National Flood Insurance Program (NFIP) is administered by FEMA and provides
ASSalLAI]N ŔaaL V_mqlA_JN pa iAlpVJViApV_T Ja^^q_VpVNm pUlaqTUA _Npwal\ aS
insurance providers. NFIP regulations must be enforced in Special Flood Hazard Areas
(SFHAs). Flood insurance is required for structures in SFHAs with federally backed loans
NT^amp^alpTATNm1^A]]
qmV_NmmL^V_VmplApVa_1
]aA_m A_L"TlA_pm
A]a_TwVpUA_ymplqJpqlNmwVpU1
]aA_mlNTAlL]NmmaSŔaaL|a_N]aaLV_mqlA_JNVm
required to IN^AV_pAV_NLSalpUN]VSNaSpUNSNLNlA]]yIAJ\NL]aA_A_LV_iNliNpqVpy
lNTAlL]NmmaSJUA_TNV_aw_NlmUViV_pUNJAmNaS"TlA_pm
The Los Angeles County Board of Supervisors adopted the County Floodway
%lLV_A_JN!am_TN]Nmaq_pyaLN3Vp]NUAipNl V_"AlJU3UVm
alLV_A_JNV_J]qLNLpUNœlmpaq_py]aaLwAy"AimA_LiAvNLpUNwAySalpUNaq_py
to begin participation in NFIP on behalf of unincorporated residents. The County’s
participation means that residents (owners and renters) in the unincorporated
Ja^^q_VpVNm wVpUV_ !am_TN]Nm aq_py AlN N]VTVI]N Sal #- ŔaaLV_mqlA_JNA_L
NLNlA]ŔaaLLVmAmpNlAmmVmpA_JN3UNœlmp"]aaL_mqlA_JN0ApN"Aim0"m
INJA^NNSSNJpVvNa_NJN^INl1V_JNpUNaq_pyUAmJa_pV_qNLlaIqmp
participation in NFIP. The FEMA FIRMs were digitized in September 2008 and have
been revised over the years by numerous Letters of Map Change and by large-scale
Physical Map Revisions for the Ballona Creek watershed and several watersheds in the
1A_pA"a_VJA"aq_pAV_m3lVq_SalNN\3aiA_TAA_ya_A_LapUNlm V_NJN^INl
pUN !am _TN]Nm aq_py JaAmp]V_N V_ ilV] A_Lthe Santa Clara River
watershed in June 2021. These maps are available to the public on the Los Angeles
County Public Works (PW) website at dpw]AJaq_pyTavŔaaL|a_N
Los Angeles County also participates in the NFIP’s Community Rating System (CRS)
program. The CRS program is a voluntary program for communities that engage in
Ja^^q_Vpy ŔaaLi]AV_ ^A_ATN^N_p AJpVvVpVNm wUVJU NxJNNL pUN ^V_V^q^ #-
standards. CRS communipVNmIN_NœpSla^ALVmJaq_pa_ŔaaLV_mqlA_JNlApNmA_L
V^ilavNLŔaaLi]AV_^A_ATN^N_pilaTlA^m01qmNmAJ]AmmlApV_TmympN^INpwNN_
A_LpaLNpNl^V_NŔaaLV_mqlA_JNilN^Vq^lNLqJpVa_mSallNmVLN_pmmaSilV]
!am_TN]Nmaq_pyVmA]Amm01Ja^^q_VpypUNlNSalNUa^Naw_NlmA_L
County of Los Angeles
All-Hazards Mitigation Plan
Page 171 of 204
lN_pNlmwUa]VvNV_A1JA_lNJNVvNqipaAÈLVmJaq_pa_pUNVlŔaaLV_mqlA_JN
policies.
3UN aq_py¯m V^i]N^N_pApVa_ A_L N_SalJN^N_p aS ]aJA] ŔaaLi]AV_^A_ATN^N_p
regulations for development in SFHAs are covered in Los Angeles County Building
aLNmwVpUpUN^amplNJN_pqiLApNJa^i]NpNLV_3Vp]NUAipNlV_J]qLNm
requirements for dNvN]ai^N_pwVpUV_ŔaaLUA|AlLAlNAm%pUNllN]NvA_palLV_A_JNm
V_J]qLNapUNlJUAipNlmV_3Vp]N
qV]LV_TaLN A]a_TwVpU3Vp]Nm]NJplVJA]aLN
3Vp]N-]q^IV_TaLN 3Vp]N"NJUA_VJA]aLN 3Vp]N0NmVLN_pVA]aLN A_L
Title 33 (Existing Building Code). Implementation and enforcement are also covered in
the Los Angeles County Subdivision Code (Title 21) and Planning and Zoning Code
(Title 22). The NFIP for unincorporated communities is administered by the Department
of Public Works (L-: 1pal^wApNl _TV_NNlV_T VvVmVa_ wUVJU mNlvNm Am pUN
aq_py¯mŔaaLi]AV_^A_ATNlJaalLV_ApNmwVpU!-:¯m
qV]LV_TA_L1ASNpyA_L!A_L
Development Divisions and with the Los Angeles County Department of Regional
Planning in their enforcement of the aq_py¯mŔaaLi]AV_^A_ATN^N_plNTq]ApVa_mA_L
iAlpVJViApNmV_"¯ma^^q_VpymmVmpNL9VmVpmwUVJUpyiVJA]]yaJJqla_A -year
cycle.
LACPW continues to enforce NFIP regulations for building permit applications
LNpNl^V_NLIy
qV]LV_TA_L1ASNpyaSœJVA]mpaINmqImpA_pVA]V^ilavN^N_pallNiAVlaS
substantial damage. Los Angeles County also requires all residential buildings
undertaking sqImpA_pVA]V^ilavN^N_ppaUAvNpUNVl]awNmpŔaalN]NvApNLSaapAIavN
the 100-yNAlŔaaLN]NvApVa_LLVpVa_A]]y!am_TN]Nmaq_pyJa_LqJpNLA0NiNpVpVvN
!ammlNA_A]ymVmV_wUVJUmNlvNmAmAmiNJVœJi]A_SallNLqJV_TLA^ATNSla^
ŔaaLV_TV_lepetitive loss areas.
SpNlA_NvN_p-qI]VJ:al\mmpASSAmmNmmpUNq_V_JalialApNLAlNAIqV]LV_TmwVpUV_pUN
extent of the event. The assessment will identify the buildings that appear to have
damages affecting 50 percent or greater of the building. SmqJUAIqV]LV_TVmV_Ŕood-
ila_NAlNAmVLN_pVœNLIy"¯m]aaL_mqlA_JN0ApN"Aimaq_py^Aim]aaLwAy
"AimalmmNmmal¯m"Aim alVLN_pVœNLIy-qI]VJ:al\mpaINV_A0NiNpVpVvN!ammlNA
will undergo further evaluation by Public Works staff on whether the building meets
"¯mLNœ_VpVa_aSmqImpA_pVA]V^ilavN^N_pmqImpA_pVA]LA^ATN11 A building
pUAp ^NNpm "¯m 11 LNœ_VpVa_ wV]] IN lNkqVlNL pa UAvN pUNN_pVlN IqV]LV_T
upgraded to meet National Flood Insurance Program (NFIP) standards ( Title 44aLN
County of Los Angeles
All-Hazards Mitigation Plan
Page 172 of 204
aSNLNlA]0NTq]ApVa_m1NJpVa_ . !am_TN]Nmaq_pyaLN3Vp]N1NJpVa_
requires the County to enforce as a minimum the current Federal Flood Plain
"A_ATN^N_p0NTq]ApVa_mLNœ_NLV_ Title 44aLNaSNLNlA]0NTq]ApVa_m1NJpVa_
SalIqV]LV_TmmplqJpqlNmA_LTlALV_T]aJApNLV_wUa]NalV_iAlpV_ŔaaLUA|AlL
areas. (Ord. 2013-Í%lL- Í%lL - ÍiAlp
1995.)
7.4 LN_pVœJApVa_A_L_A]ymVmaS"VpVTApVa_Strategies
-apN_pVA]^VpVTApVa_AJpVa_mwNlNVLN_pVœNLSalNAJUUA|AlLVLN_pVœNLV_1NJpVa_6 in an
effort to ensure as comprehensive a mitigation strategy as possible. Multiple mitigation
options were then analyzed against the goals and objectives delineated in this section
with a focus on new and existing buildings. A combination of new and ongoing
^VpVTApVa_ AJpVa_m AV^NL Ap lNLqJV_T pUN NSSNJpm aS pUN VLN_pVœNL UA|AlLm wNlN
compiled into the list of mitigation actions in the following subsection. This list includes
AwVLNlA_TNaSiapN_pVA]pyiNmaS^VpVTApVa_AJpVa_mV_J]qLV_T
x Local Plans and Regulations.
x Structure and Infrastructure Projects.
x Natural Systems Protection.
x Education and Awareness Programs.
A notable update to the 2025 AHMP was the integration of human-caused threats and
corresponding potential mitigation actions. The AHMP Planning Team also reviewed
FEMA’s Mitigation Ideas document to incorporate national best practices in the list of
potential mitigation actions.
County of Los Angeles
All-Hazards Mitigation Plan
Page 173 of 204
7.4.1 Mitigation Strategies
01 Title: 1qiialpA_LxiA_Laq_pywVLN9NTNpApVa_"A_ATN^N_pA_LVlN
Prevention Efforts
1aqlJN Los Angeles County Fire Department
Type: Natural Systems Protection
Description: Conduct passive protection measures such as
creating defensible space buffers around residential and
non-residential structures through the removal of
ŔA^^AI]N vNTNpApVa_ ^A_ATV_T A_Lal lNLqJV_T
UA|AlLaqm SqN]m JlNApV_T œlNIlNA\m œlN-resistive
landmJAiV_T A_L Ja_mplqJpVa_ A_L J]NAlV_T LNAL
vNTNpApVa_ A^a_T apUNlm _TATN V_LVTN_aqm
Ja^^q_VpVNmpaV_Sal^vNTNpApVa_^A_ATN^N_pA_LœlN
prevention practices aligned with Traditional Ecological
Knowledge (TEK).
Hazard: :V]LœlN
Hazard: Severe
Wind/Tornado
02 Title: _UA_JN a^^q_Vpy _TATN^N_p V_ :V]LœlN -lapNJpVa_ A_L
Prevention
1aqlJN Los Angeles County Department of Regional Planning
Type: Education and Awareness Programs
Description: _TATNlNmVLN_pmA_LIqmV_NmmNmV_UVTUœlN
risk communities to educate them on community-focused
^VpVTApVa_ A_L lVm\ lNLqJpVa_ mplApNTVNm N^NlTN_Jy
ilNiAlNL_NmmA_LNvAJqApVa_lNALV_NmmA_Laiialpq_VpVNm
paTNpV_va]vNLV_œlNmASNpy-related community initiatives.
Engage indigenous communities to inform protection and
prevention practices aligned with Traditional Ecological
Knowledge (TEK).
Hazard: :V]LœlN
Hazard: Severe
Wind/Tornado
County of Los Angeles
All-Hazards Mitigation Plan
Page 174 of 204
03 Title: Perform Post-Fire Flooding, Debris Flow, and Mud ]aw 0Vm\
Assessments and Mitigation Activities
1aqlJN Los Angeles County Department of Public Works
Type: Structure and Infrastructure Projects
Description: a]]awV_T A wV]LœlN AmmNmm Iql_ mJAl Sal
mVT_VœJA_p^qLA_LLNIlVmŔawlVm\mpailaLqJN^qLA_L
LNIlVmŔawiUAmN^AimSalœlmplNmia_LV_TATN_JVNmpa
prepare for potential evacuations. Recommend mitigation
mplApNTVNmpailNvN_p^qLA_LLNIlVmŔawVmpacts.
Hazard: :V]LœlN
Hazard: Flooding
04 Title: Strengthen Operational Continuity Capabilities for Critical Facilities
1aqlJN Los Angeles County NiAlp^N_p-qI]VJNA]pUA^a_TapUNlm
Type: Structure and Infrastructure Projects
Description: Conduct robust continuity planning to ensure
the continued performance of essential functions in the
event critical facilities are impacted by various hazards.
Build capabilities that support operational continuity such
as alternate or uninterrupted power mqii]y wal\SalJN
development and cross-plAV_V_T N^NlTN_Jy
Ja^^q_VJApVa_mA_LLApAIAJ\qialSAV]avNlUAlLwAlN
Hazard: :V]LœlN
Hazard: Extreme Heat
Hazard: Severe
Wind/Tornado
Hazard: Cyber Incidents
County of Los Angeles
All-Hazards Mitigation Plan
Page 175 of 204
05 Title: Incorporate Hazards in Local Planning, Land Use, and Development
Codes
1aqlJN Los Angeles County Department of Public Works and Regional Planning
Type: Local Planning and Regulations
Description: NvN]ai ^AV_pAV_ A_L ]NvNlATN
opportunities to strengthen relevant ordinances that
TavNl_ ]A_L qmN IqV]LV_T JaLNm A_L LNvN]ai^N_p V_
high-risk hazard areas. Incorporate mitigation actions in
Ja^^q_Vpyi]A__V_TmqJUAma^^q_Vpy:V]LœlN-]A_m
Flood MA_ATN^N_p-]A_mA_LpUNaq_pyN_NlA]-]A_
among many others.
Hazard: :V]LœlN
Hazard: AlpUkqA\N
Hazard: Land Movement
Hazard: Severe
Wind/Tornado
Hazard: Flooding
06 Title: Increase Public Awareness of Climate Change Effects on Local
Hazards
1aqlJN Los Angeles County UVNS1qmpAV_AIV]Vpy%SœJN
Type: Education and Awareness Programs
Description: Engage with communities on ways climate
change impacts various natural hazards along with
mitigation actions and available resources for climate
adaptation and resilience. Efforts should focus on how
communities can take action or support existing County
programs including funding available to the public. Public
N_TATN^N_pNSSalpmmUaq]LINAJJNmmVI]NN_mqlNiNai]N
with Access and Functional Needs are included in
aqplNAJU A_L qmN ^ApNlVA]m wVpU ^q]pVi]N ]A_TqATN
options.
Hazard: :V]LœlN
Hazard: Extreme Heat
Hazard: Drought
Hazard: Land Movement
Hazard: Severe
Wind/Tornado
Hazard: Flooding
County of Los Angeles
All-Hazards Mitigation Plan
Page 176 of 204
07 Title: Expand Stormwater Management, Drainage, and Outlet Planning
1aqlJN Los Angeles County Department of Public Works
Type: Local Planning and Regulations
Description: Continue robust stormwater management
programs. Conduct studies to inform measures to improve
aqp]NpA_LLlAV_ATNi]A__V_TA_LilNvN_pŔaaLLA^ATN
to communities in high-risk areas. These efforts should also
ilNvN_p ŔaaL LA^ATN pa aq_py-maintained roadwAym
including evacuation egress and emergency services
V_TlNmmwUV]NmqiialpV_TiapN_pVA]Tlaq_LwApNllNJUAlTN
Hazard: Flooding
Hazard: Drought
Hazard: Transportation
Incident
08 Title: Construct and Maintain Localized Flood Control Improvements
1aqlJN Los Angeles County Department of Public Works
Type: Structural and Infrastructure Projects
Description: "AV_pAV_NxVmpV_TŔaaLJa_pla]^NJUA_Vm^m
Iy LlAV_ATN mympN^ ^AV_pN_A_JN mNLV^N_p A_L LNIlVm
J]NAlA_JN A_L apUNl AJpVa_m !NvNlATN aiialpq_VpVNm pa
Ja_mplqJpŔaaLJa_pla]V^ilavN^N_pm
Hazard: Flooding
County of Los Angeles
All-Hazards Mitigation Plan
Page 177 of 204
09 Title: Preserve Floodplains as Public Use Open Spaces
1aqlJN Los Angeles County NiAlp^N_paS-qI]VJ:al\mA^a_TapUNlm
Type: Natural Systems Protections
Description: Preserve and expand public use open spaces
that capture stormwater with the aim of reducing localized
ŔaaLV_TwUV]NA]mailavVLV_TTlNN_miAJNA_L
recreational opportunities to communities. Prioritize
ŔaaLi]AV_mA_LwApNlmUNLmV_aq_py-owned public use
aiN_miAJNm_NAlŔaaLlVm\AlNAm4mNmpal^wApNlINmp
management practices in projects involving open spaces
to support natural water collection and conservation.
_JalialApN ŔaaLi]AV_ ilNmNlvApVa_ V_pa SqpqlN iAl\
improvements.
Hazard: Flooding
10 Title: Harden Critical Facilities and Infrastructure from Seismic Damage
1aqlJN Los Angeles County Department of Public Works
Type: Structure and Infrastructure Projects
Description: Conduct seismic assessments to prioritize
lNplaœppV_TA_LapUNlmNVm^VJ^VpVTApVa_AJpVa_mmqJUAm
bracing or seismic shutoff valves. Efforts should focus on
JlVpVJA]SAJV]VpVNmSalJa^^q_Vpy]VSN]V_NmmqJUAmUamiVpA]m
iqI]VJmASNpySAJV]VpVNmqpV]Vpy mVpNmUVTU-hazard potential
LA^mA_LplA_mialpApVa_AmmNpmVNIlVLTNmlaALwAym
AVlialpmA_LapUNlm
Hazard: AlpUkqA\N
Hazard: Land Movement
Hazard: Dam Failure
County of Los Angeles
All-Hazards Mitigation Plan
Page 178 of 204
11 Title: Prevent Impacts to the Transportation System
1aqlJN Los Angeles County Department of Public Works
Type: Structure and Infrastructure Projects
Description: Hazard impacts to the transportation system
in Los Angeles County have far-reaching potential for
cascading effects across multiple lifelines. Mitigation
activities for multiple hazards should focus on preventing
or lessening impacts to transportation. Activities may
include stabilization efforts along County-maintained
laALmlNV_SalJV_TplA_mialpApVa_AmmNpmalapUNlmNVm^VJ
mitigation actions.
Hazard: AlpUkqA\N
Hazard: Land Movement
Hazard: Transportation
Incident
12 Title: Continue SSalpmpa_UA_JNA^1ASNpyA_L0NLqJN!a_T-Term
9q]_NlAIV]VpVNmwVpUVTUA|AlL-apN_pVA]A^m
1aqlJN Los Angeles County Department of Public Works
Type: Structure and Infrastructure Projects
Description: Upgrade infrastructure to ensure the long-
term integrity and safe operation of County-owned dam
facilities. Potential actions could include strengthening of
LA^m mNLV^N_p ^A_ATN^N_p AJpVvVpVNm lNTq]Al
V_miNJpVa_m Ja_pV_qaqm ^AV_pN_A_JN V_pNTlApV_T
ALvA_JNLpNJU_a]aTVNmA_LN^NlTN_JyilNiAlNL_Nmm
efforts.
Hazard: AlpUkqA\N
Hazard: Dam Failure
County of Los Angeles
All-Hazards Mitigation Plan
Page 179 of 204
13 Title: mmNmm:ApNl0NmV]VN_JNV_!am_TN]Nmaq_py
1aqlJN Los Angeles County Department of Public Works
Type: Local Planning and Regulations
Description: Conduct assessments and studies to monitor
the water supply and develop recommendations for other
water systems. Identify potential secondary water sources
or other contingency measures for ensuring water system
resilience during drought conditions.
Hazard: Drought
14 Title: Expand Drought-Tolerant Landscaping and Design
1aqlJN !am_TN]Nmaq_pyUVNS1qmpAV_AIV]Vpy%SœJNA_LNiAlp^N_paS0NTVa_A]
Planning
Type: Natural Systems Protection
Description: Integrate drought mitigation into landscaping
and design measures undertaken by the County. Prioritize
native and drought-tolerant plants when selecting
]A_LmJAiV_TLNmVT_m4mNiNl^NAI]N^ApNlVA]mSaliAvNlm
LlVvNwAymwA]\wAymA_LlaALwAympalNLqJNlunoff and
promote groundwater recharge that incorporate
indigenous- informed practices aligned with Traditional
Ecological Knowledge (TEK).
Hazard: Drought
County of Los Angeles
All-Hazards Mitigation Plan
Page 180 of 204
15 Title: LLlNmm4lIA_NApm]A_LmIy_vNmpV_TV_lNN__SlAmplqJpqlN
and Cooling Strategies
1aqlJN !am_TN]Nmaq_pyUVNS1qmpAV_AIV]Vpy%SœJNNiAlp^N_paS0NTVa_A]
-]A__V_TNiAlp^N_paSJa_a^VJ%iialpq_VpyNiAlp^N_paS-qI]VJNA]pUA_L
NiAlp^N_paS-qI]VJ:al\mA^a_TapUNlm
Type: Local Planning and Regulations
Description: Increase shade cover provided by vegetation
such as planting native and drought-tolerant trees along
wVpU m^A]]Nl i]A_pm mqJU Am mUlqIm TlAmmNm A_L
groundcover. Increase the tree canopy in County parks
and open concrete or asphalt spaces in the public right of
way or County-owned parking lots. Conduct assessments
to identify communities considered urban heat islands that
are at highest need for an increase in tree canopy or other
heat mitigation activities. Advance cooling strategies such
as Ja_mplqJpV_T mUALNmplqJpqlNm V_mpA]]V_T mi]AmU iALm
aiNlApV_TJaa]V_TJN_pNlm^aLNl_V|V_TAVlJa_LVpVa_V_T
mympN^m A_L NxiA_LV_T pUN AvAV]AIV]Vpy aS Jaa] laaœ_T
V_SlAmplqJpqlN pUAp lNŔNJpm UNAp AwAy Sla^ IqV]LV_Tm
Ensure mitigation actions address heat impacts faced by
people with Access and Functional Needs. Many of these
AJpVa_mUAvNAmNJa_LAlyIN_Nœp^VpVTApV_TpUNNSSNJpmaS
J]V^ApNJUA_TNIyila^apV_TJAlIa_mNkqNmplApVa_pUN
capture and storage of CO2 from the atmosphere.
LLVpVa_A]]yV_Jleasing green space and shade cover in
urban areas can advance environmental justice.
Hazard: Extreme Heat
County of Los Angeles
All-Hazards Mitigation Plan
Page 181 of 204
16 Title: _JlNAmNaAmpA]0NmV]VN_JN-lNvN_plamVa_A_L-lapNJp1UalN]V_Nm
1aqlJN !am_TN]Nmaq_pyUVNS1qmpAV_AIV]Vpy%SœJNA_LDepartment of Beaches
and Harbors
Type: Natural Systems Protection
Description: Conduct activities to replace sediment lost
due to erosion or coastal storms. Assess the need for other
sediment protection measures such as planting certain
types of vegetation. Consider activities that prevent wind
from blowing sand off beaches and impacts from storm
surge in high-risk areas. These actions help protect coastal
roadways and other infrastructure along with ensuring
recreation opportunities remain for residents and visitors.
Hazard: Flooding
Hazard: Tsunami
17 Title: Conduct Multi-Discipline Training and Exercise Programs
1aqlJN !am _TN]Nm aq_py 1UNlVSS¯m NiAlp^N_p A_L %SœJN aS ^NlTN_Jy
Management
Type: Education and Awareness Programs
Description: Identify opportunities for joint training and
exercises for mass violence and cyber incident response
AJlammLVmJVi]V_NmaS]AwN_SalJN^N_pœlNA_LN^NlTN_Jy
^NLVJA] mNlvVJNm ^NLVJA] NxA^V_Nl ilVvApN mNJpal A_L
others. Each training and exercise should include mass
violence rescue and evacuation techniques for AFN
populations.
Hazard: "Amm9Va]N_JN
Hazard: Cyber Incidents
County of Los Angeles
All-Hazards Mitigation Plan
Page 182 of 204
18 Title: Strengthen Partnerships and Coordination Among Local Agencies
1aqlJN !am _TN]Nm aq_py 1UNlVSS¯m NiAlp^N_p A_L %SœJN aS ^NlTN_Jy
Management
Type: Education and Awareness Programs
Description: Expand collaborative agreements with other
agencies to share resources during large-scale
emergencies. Strengthen partnerships with local agencies
for resource sharing. Enhance response capabilities
during major incidents.
Hazard: "Amm9Va]N_JN
Hazard: Cyber Incidents
19 Title: _JalialApN"Amm9Va]N_JN-lNvN_pVa_A_L"VpVTApVa_SSalpmV_pa
Special Event Planning
1aqlJN !am _TN]Nm aq_py 1UNlVSS¯m NiAlp^N_p A_L %SœJN aS ^NlTN_Jy
Management
Type: Education and Awareness Programs
Description: Use physical security measures such as
Ia]]AlLm wApNl-œ]]NL IAllVJALNm vNUVJ]N IAllVNlm A_L
others. Identify mitigation measures for upcoming special
NvN_pmmqJUAmpUN:al]Lqi1qiNl
aw]A_L%]y^iVJm
Conduct special event training on topics such as crowd
^A_ATN^N_p mialpV_T NvN_p mASNpy A_L mpALVq^
evacuation. Incorporate Family Assistance Center
readiness into special event planning.
Hazard: "Amm9Va]N_JN
County of Los Angeles
All-Hazards Mitigation Plan
Page 183 of 204
20 Title: xplN^NNAp0Vm\LqJApVa_A_L1ASNpy%qplNAJUSal0NmVLN_pmA_L
9q]_NlAI]N:al\Nlm
1aqlJN !am_TN]Nmaq_pyUVNS1qmpAV_AIV]Vpy%SœJNNiAlp^N_paSJa_a^VJ
%iialpq_VpyNiAlp^N_paS-qI]VJNA]pUA_LNiAlp^N_paS-qI]VJ:al\m
Type: Education and Awareness Programs
Description: Implement outreach and education to
workers in low-wage and high hazard industries in LA
County that are disproportionately impacted by extreme
heat. Partner with organizations providing services to
people with Access and Functional Needs on heat
response strategies. Expand awareness of cooling centers
and other heat respite options for unhoused populations.
Increase workforce development opportunities to expand
the availability of green infrastructure.
Hazard: Extreme Heat
21 Title: _JlNAmNVN]L0Nmia_mNA_LaalLV_ApVa_AiAIV]VpVNm
1aqlJN !am _TN]Nm aq_py 1UNlVSS¯m NiAlp^N_p A_L %SœJN aS ^NlTN_Jy
Management
Type: Education and Awareness Programs
Description: _UA_JN œN]L JaalLV_ApVa_ JAiAIV]VpVNm Ap
large-scale planned events and no-notice incidents such
AmwV]LœlNm^AmmvVa]N_JNA_LapUNlm-apN_pVA]AJpVa_m
could include investments in new redundant
Ja^^q_VJApVa_m mympN^m lNmia_mN vNUVJ]Nm A]Nlp A_L
wAl_V_T JAiAIV]VpVNm A_L apUNl œN]L aiNlApVa_m
equipment.
Hazard: :V]LœlN
Hazard: "Amm9Va]N_JN
County of Los Angeles
All-Hazards Mitigation Plan
Page 184 of 204
22 Title: Strengthen Public Health Prevention and Preparedness Measures
1aqlJN !am_TN]Nm aq_py %SœJN aS ^NlTN_Jy "A_ATN^N_p NiAlp^N_p aS
-qI]VJNA]pUNiAlp^N_paSNA]pU1NlvVJNmA_LVlNNiAlp^N_p
Type: Education and Awareness Programs
Description: Continue and expand mass vaccination and
immunization efforts. Coordinate healthcare surge
preparedness and response efforts. Conduct disease
mqlvNV]]A_JN^a_VpalNAl]ywAl_V_TmympN^mA_L
coordinate outbreak response. Educate communities and
businesses about health implications related to wildœlN
recovery and hazardous materials. Liaise with health
system partners to understand hospital surge capacity
within the County. Maintain and deploy emergency
stockpiles. Incorporate potential climate change-related
infectious disease implications into public health
preparedness planning.
Hazard: Public Health
Emergencies
7.5 Status of Previous Mitigation Efforts
Table 7-6 below shows the status of mitigation strategies described in the 2020 AHMP.
NiAlp^N_pmUAvN^ALNmVT_VœJA_pilaTlNmma_ma^NaSpUNmN^VpVTApVa_mplApNTVNm
iAlpVA]]yIqp_apSq]]yJa^i]NpV_Tma^NaSpUNmNNSSalpmmmqJUNAJUmplApNTySla^pUN
2020 AHMP have been rolled into the mitigation strategies described in this section.
Table 7-6 Status of Mitigation Efforts
2020 AHMP Strategy Status 2025 AHMP Strategy
Red Flag Warning Public
Outreach
Not
Completed/
Ongoing
Enhance Community Engagement
V_:V]LœlN-lapNJpVa_A_L
Prevention
County of Los Angeles
All-Hazards Mitigation Plan
Page 185 of 204
2020 AHMP Strategy Status 2025 AHMP Strategy
Vegetation Management
Program
Not
Completed/
Ongoing
Support and Expand Countywide
Vegetation Management and Fire
Prevention Efforts
Fireproof Coating of Critical
Facilities
Not
Completed/
Ongoing
Enhance Community Engagement
V_:V]LœlN-lapNJpVa_A_L
Prevention
Auxiliary Power for Critical
Facilities
Not
Completed/
Ongoing
Strengthen Operational Continuity
Capabilities for Critical Facilities
Earthquake-Resistant Ductile
Iron Pipes Replacement
Not
Completed/
Ongoing
Harden Critical Facilities and
Infrastructure from Seismic
Damage
Watershed Ecosystem
Restoration
Not
Completed/
Ongoing
Preserve Floodplains as Public Use
Open Spaces
Green Streets / Living Streets Not
Completed/
Ongoing
Expand Drought-Tolerant
Landscaping and Design
Coordinated Data Collection
and Database Systems
Not
Completed/
Ongoing
Strengthen Partnerships and
Resource Coordination Among
Local Agencies
Brush Clearance Program Not
Completed/
Ongoing
Support and Expand Countywide
Vegetation Management and Fire
Prevention Efforts
Wildland Urban-Interface
Ordinance
Not
Completed/
Ongoing
Incorporate Hazards in Local
-]A__V_T!A_L4mNA_L
Development Codes
Urban Forest Management
Plan
Not
Completed/
Ongoing
Address Urban Heat Islands by
Investing in Green Infrastructure
and Cooling Strategies
County of Los Angeles
All-Hazards Mitigation Plan
Page 186 of 204
2020 AHMP Strategy Status 2025 AHMP Strategy
a^^q_Vpy:V]LœlN-lapNJpVa_
Plans
Not
Completed/
Ongoing
Incorporate Hazards in Local
-]A__V_T!A_L4mNA_L
Development Codes
Pre-Disaster Professional
Support
Not
Completed/
Ongoing
Strengthen Operational Continuity
Capabilities for Critical Facilities
Fuel Trailer Project Not
Completed/
Ongoing
Strengthen Operational Continuity
Capabilities for Critical Facilities
7.6 Prioritization and Implementation of Mitigation Actions
Potential mitigation actions were prioritized using the FEMA National Risk Index (NRI)
score and information from the 2024 Los _TN]Nm3UlNApA_LA|AlLLN_pVœJApVa_A_L
0Vm\ mmNmm^N_p 30 wUVJU IapU ALLlNmm UA|AlLm Iy SlNkqN_Jy mNvNlVpy A_L
impact. Both the NRI and THIRA follow established processes and use a standardized
risk assessment methodology. The NRI incorporates multiple variables including
physical impacts posed by hazards in addition to social vulnerability data that
communicates risks miNJVœJpaAJNlpAV_Ja^^q_Vpy3AI]N7-7 provides an overview of
the NRI results for Los Angeles County across 18 hazards. Hazards rated as Relatively
!aw#apii]VJAI]Nal#a0ApV_TwNlN_apV_J]qLNLV_pUVm"- Am pUNy AlN
q_Ja^^a_V_SlNkqN_JyV_!am_TN]Nmaq_pyA]]apUNlUA|AlLmAlNJovered in this
plan.
Table 7-7 "#ApVa_A]0Vm\_LNxA|AlLm
Hazard #01JalN
(out of 100.0)
Score Description Covered in
Plan?
Earthquake 100.0 Very High Yes | Section 6.3
:V]LœlN 99.9 Very High Yes | Section 6.2
Extreme Heat 98.4 Relatively High Yes | Section 6.4
Tornado 97.6 Relatively High Yes | Section 6.10
County of Los Angeles
All-Hazards Mitigation Plan
Page 187 of 204
Hazard #01JalN
(out of 100.0)
Score Description Covered in
Plan?
Landslide 96.3 Relatively High Yes | Section 6.8
Lightning 95.0 Relatively High Yes | Section 6.2/
6.6
Riverine Flooding 90.8 Relatively Moderate Yes | Section 6.6
Drought 73.8 Relatively Moderate Yes | Section 6.5
Strong Wind 73.5 Relatively Moderate Yes | Section 6.10
Tsunami 63.5 Relatively Moderate Yes | Section 6.10
Winter Weather 48.6 Relatively Low Not Prioritized
Hail 48.1 Relatively Low Not Prioritized
Coastal Flooding 43.3 Very Low Not Prioritized
Avalanche 33.7 Very Low Not Prioritized
Cold Wave 0.0 No Rating Not Prioritized
Hurricane N/A Not Applicable Not Prioritized
Ice Storm N/A Not Applicable Not Prioritized
Volcanic Activity N/A Not Applicable Not Prioritized
The THIRA is a process that communities undertake to assess risk and set capability
targets to focus their preparedness efforts and strengthen response and recovery
capabilities. There are three primary focuses of the THIRA: threat and hazard
VLN_pVœJApVa_V^iAJpmA_A]ymNmpUApV_J]qLNpUNmiNJVœJLN^aTlAiUVJm aS pUN
Ja^^q_VpyA_LALNmJlVipVa_aSNxVmpV_TlNmia_mNA_LlNJavNlyJAiAIV]VpVNm3UN
Los Angeles/Long Beach THIRA was reviewed as part of this hazard mitigation planning
effort and all threApm A_L UA|AlLm VLN_pVœNL wNlN V_J]qLNL Am iAlp aS pUVm "-
LLVpVa_A]]ypUN30¯mVLN_pVœJApVa_aSmNvNlA]Uq^A_-caused threats with potential
paV^iAJp!am_TN]Nmaq_pyV_ŔqN_JNLpUNLNJVmVa_paV_J]qLNmqJUpUlNApmV_pUVm
AHMP. Table 7-8 mUawmAJlammwA]\aSpUNUA|AlLmA_LpUlNApmVLN_pVœNLV_pUN30
and their corresponding sections in this AHMP.
County of Los Angeles
All-Hazards Mitigation Plan
Page 188 of 204
Table 7-8 30A_L "-lammwA]\
30
Hazard/Threat Name
2025 AHMP Hazard/Threat
Name
Covered in Plan?
Biological Attack Public Health Emergencies Yes | Section 6.14
Complex Coordinated
Terrorist Attack
Mass Violence Yes | Section 6.11
Cyber Attack Cyber Incident Yes | Section 6.12
Earthquake Earthquake Yes | Section 6.3
Flood Flooding Yes | Section 6.6
Pandemic – Human Public Health Emergencies Yes | Section 6.14
Radiological Attack Public Health Emergencies Yes | Section 6.14
Transportation Accident Transportation Incident Yes | Section 6.13
:V]LœlN :V]LœlN Yes | Section 6.2
Additional criteria used to prioritize potential mitigation actions also included the
following components:
x JpVa_mpUApilValVpV|NNkqVpyA_LV_pNTlApNvq]_NlAI]Niaiq]ApVa_mV_J]qLV_T
people with AFN.
x -apN_pVA]IN_NœpmaSpUNAJpVa_pailNvN_pA^A[alUA|AlL
x Actions that have social support to build a culture and practice of resilience.
x ampaSpUNAJpVa_vNlmqmpUNiapN_pVA]IN_NœppailNvN_pA^A[alUA|AlL
x Availability of funding and actions that support grant requirements.
x Political support to remedy or prevent a major health or safety hazard.
x JpVa_mpUApAlNpNJU_VJA]]y]NTA]]yN_vVla_^N_pA]]yA_LNJa_a^VJA]]ySNAmVI]N
x Actions that the County has the administrative capabilities to implement.
x Actions that are related to mitigating long-term vulnerabilities to County-
owned High Hazard Potential Dams will automatically be given a HIGH priority.
7.6.1 Priority Levels
x High-Priority Mitigation Actions: are essential and require immediate
AppN_pVa_ pa ALLlNmm JlVpVJA] lVm\m A_L mASNTqAlL ]VSN ilaiNlpy al NmmN_pVA]
systems.
County of Los Angeles
All-Hazards Mitigation Plan
Page 189 of 204
x Medium-Priority Mitigation Actions: AlNV^ialpA_pIqp]NmmqlTN_pmqiialpV_T
overall risk reduction and resilience goals while allowing for planned
implementation.
x Low-Priority Mitigation Actions: address lower-risk concerns or long-term
objectives and can be deferred without immediate impact to safety or core
functions.
7.6.2 Changes in Criteria
The 2014 Los Angeles County AHMP’s Mitigation Action Matrix was prioritized using
pUN 1aJVA] 3NJU_VJA] L^V_VmplApVvN -a]VpVJA] !NTA] _vVla_^N_pA] A_L Ja_a^VJ
13-! ^NpUaLwUVJU"UALlNJa^^N_LNLAmAilValVpV|ApVa_ilaJNLqlNV_pUN
early to mid-2000s. The 2020 AHMP replaced the use of STAPLEE with a more
streamlined prioritization process that included the following:
x 3alN^NLyalilNvN_pA^A[alUNA]pUmASNpyUA|AlLA^VpVTApVa_ila[NJp^qmp
have political support.
x 3aIqV]LAJq]pqlNA_LilAJpVJNaSLVmAmpNllNmV]VN_JNA^VpVTApVa_ila[NJp^qmp
have social support.
x 3a^NNp""TlA_pJlVpNlVAA^VpVTApVa_ila[NJp^qmp INpNJU_VJA]]y
]NTA]]yN_vVla_^N_pA]]yA_LNJa_a^VJA]]y SNAmVI]NA_LpUN[qlVmLVJpVa_^qmp
have the administrative capabilities to implement it.
This prioritization method used in the 2020 AHMP has been adapted and incorporated
into the prioritization criteria described previously in Section 7.6.
7.7 Integration with Other Plans
The County of Los Angeles ensures that mitigation is a countywide effort with multiple
departments contributing to critical activities that reduce hazard risks. These actions
are captured in other discipline-miNJVœJi]A_mV_ALLVpVa_papUN"-V_J]qLV_TpUamN
listed in Table 7-9.
County of Los Angeles
All-Hazards Mitigation Plan
Page 190 of 204
Table 7-9 AHMP Integration with Other Plans
Plan Authored By Hazard(s) Covered
in Plan?
Comprehensive
Floodplain
Management Plan
Los Angeles County
Department of Public
Works
Flood Yes
Repetitive Loss Area
Analysis Report
Los Angeles County
Department of Public
Works
Flood Yes
Climate Action Plan Los Angeles County
Department of Regional
Planning
:V]LœlN
Extreme Heat
Flooding
Drought
Yes
Sustainability Plan Los Angeles County Chief
1qmpAV_AIV]Vpy%SœJN
:V]LœlN
Extreme Heat
Flooding
Drought
Yes
County Fire Plan Los Angeles County Fire
Department
:V]LœlN Yes
County of Los Angeles
All-Hazards Mitigation Plan
Page 191 of 204
7.8 Mitigation Action Plan
Table 7-10 lNilNmN_pmA"VpVTApVa_JpVa_-]A_palNLqJNlVm\maSpUNUA|AlLmVLN_pVœNLV_pUVm"-#apAI]y^A_y
County departments include discipline-miNJVœJ^VpVTApVa_AJpVa_mwVpUV_apUNllN]ApNLi]A_m^N_pVa_NLV_pUNAIavN
section. Some actions that mitigate risk of natural hazards that are covered elsewhere may not be explicitly listed or may
INlNSNllNLpaV_TN_NlA]pNl^mwUV]NmiNJVœJLNpAV]mAlNAvAV]AI]NV_apUNllN]ApNLi]A_m
Table 7-10 Mitigation Action Plan
Action
No.
Priority Hazard
Action Name
Potential
Funding
Source
Expected
Time
Frame
Lead
Agencies
01 HIGH
:V]LœlN Support and Expand Countywide
Vegetation Management and Fire
Prevention Efforts
HMGP Annual !aPW
Severe
Wind/Tornado
02 HIGH
:V]LœlN Enhance Community
_TATN^N_pV_:V]LœlN
Protection and Prevention
HMGP Quarterly !a0-
%"!1 Severe
Wind/Tornado
03 HIGH
:V]LœlN Perform Post-VlN]aaLV_T
NIlVm]awA_L"qL]aw0Vm\
Assessments and Mitigation
Activities
"-" Annual PW !a
OEM
Flooding
04 HIGH
:V]LœlN 4111- Annual %"PW
-Extreme Heat
County of Los Angeles
All-Hazards Mitigation Plan
Page 192 of 204
Action
No.
Priority Hazard
Action Name
Potential
Funding
Source
Expected
Time
Frame
Lead
Agencies
Severe
Wind/Tornado
Strengthen Operational
Continuity Capabilities for Critical
Facilities
!a
!11
Cyber Incidents
05 HIGH
:V]LœlN
Incorporate Hazards in Local
-]A__V_T!A_L4mNA_L
Development Codes
"-" 1-3 Years 0-PW
AlpUkqA\N
Land Movement
Severe
Wind/Tornado
Flooding
06 MEDIUM
:V]LœlN
Increase Public Awareness of
Climate Change Effects on Local
Hazards
"-lai Annual 0- 1%
CEO Extreme Heat
Drought
Land Movement
1evere
Wind/Tornado
Flooding
County of Los Angeles
All-Hazards Mitigation Plan
Page 193 of 204
Action
No.
Priority Hazard
Action Name
Potential
Funding
Source
Expected
Time
Frame
Lead
Agencies
07
HIGH
Flooding Expand Stormwater
"A_ATN^N_plAV_ATNA_L
Outlet Planning
FMA 1-5 Years PW
Drought
Transportation
Incident
08 HIGH Flooding Construct and Maintain Localized
Flood Control Improvements
FMA 1-5 Years PW
09 MEDIUM Flooding Preserve Floodplains as Public
Use Open Spaces
"-lai 1-5 Years PW0--0
10 HIGH
AlpUkqA\N Harden Critical Facilities and
Infrastructure from Seismic
Damage
HMGP 1-5 Years PW1
Land Movement
Dam Failure
11 MEDIUM
AlpUkqA\e Prevent Impacts to the
Transportation System
HMGP 1-5 Years PWLASD
Land Movement
Transportation
Incident
County of Los Angeles
All-Hazards Mitigation Plan
Page 194 of 204
Action
No.
Priority Hazard
Action Name
Potential
Funding
Source
Expected
Time
Frame
Lead
Agencies
12 HIGH AlpUkqA\N Conduct Seismic Strengthening
at County-Owned Dams
"- 1-5 Years PW
Dam Failure
13 MEDIUM Drought Assess Water Resilience in Los
Angeles County
Prop 4 1-5 Years PW0-
14 MEDIUM Drought Expand Drought-Tolerant
Landscaping and Design
Prop 4 1-5 Years -0 0-
PW1%
15 HIGH Extreme Heat
Address Urban Heat Islands by
Investing in Green Infrastructure
and Cooling Strategies
Prop 4 1-5 Years 1% 0-
% -
PW-0
16 HIGH
Flooding _JlNAmNaAmpA]0NmV]VN_JN
-lNvN_plamVa_A_L-lapNJp
Shorelines
"-lai 1-5 Years 1%
PW Tsunami
17 HIGH "Amm9Va]N_JN Conduct Multi-Discipline Training
and Exercise Programs
41SHSP 1-5 Years !1 %"
LACoFD Cyber Incidents
18 MEDIUM
"Amm9Va]N_JN Strengthen Partnerships and
Resource Coordination Among
Local Agencies
4111- 1-5 Years !1 %"
LACoFD
Cyber Incidents
County of Los Angeles
All-Hazards Mitigation Plan
Page 195 of 204
Action
No.
Priority Hazard
Action Name
Potential
Funding
Source
Expected
Time
Frame
Lead
Agencies
19 MEDIUM "Amm9Va]N_JN
Incorporate Mass Violence
Prevention and Mitigation Efforts
into Special Event Planning
4111- 1-5 Years !1 %"
LACoFD
20 HIGH Extreme Heat
Extreme Heat Risk Education and
Safety Outreach for Residents
and Vulnerable Workers
Prop 4 1-5 Years 1% %
-PW
DAD
21 HIGH
Public Health
Emergencies
Strengthen Robust Public Health
Prevention and Preparedness
Measures
41 11-
----
1-5 Years - %"
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22 MEDIUM :V]LœlN Increase Field Response and
Coordination Capabilities
4111- 1-5 Years !1 %"
LACoFD "Amm9Va]N_JN
Agency Key:
CEO = Los Angeles County UVNSxNJqpVvN%SœJN
1%À!am_TN]Nmaq_pyUVNS1qmpAV_AIV]Vpy%SœJN
DAD=!am_TN]NmNiAlp^N_paSTV_TA_LVmAIV]VpVNm
DBH = Los _TN]Nmaq_pyNiAlp^N_paS
NAJUNmA_LAlIalm
%À!am_TN]Nmaq_pyNiAlp^N_paSJa_a^VJ%iialpq_Vpy
1À!am_TN]Nmaq_pyNiAlp^N_paSNA]pU1NlvVJNm
-À!am_TN]Nmaq_pyNiAlp^N_paS-qI]VJNA]pU
-0À!am_TN]Nmaq_pyNiAlp^N_paS-Al\mA_L0NJlNApVa_
PW = Los Angeles County Public Works
0-À!am_TN]Nmaq_pyNiAlp^N_paS0NTVa_A]-]A__V_T
1À!am_TN]Nmaq_py_pNl_A]1NlvVJNmNiAlp^N_p
!aÀ!am_TN]Nmaq_pyVlNNiAlp^N_p
!1À!am_TN]Nmaq_py1UNlVSS¯mNiAlp^N_p
OEM = Los Angeles County UVNS xNJqpVvN %SœJN- %SœJN aS
^NlTN_Jy"A_ATN^N_t
lA_p-laTlA^ Ny
FMA = Flood Mitigation Assistance
HMGP = Hazard Mitigation Grant Program
HPP = Hospital Preparedness Program
PHEP = Public Health Emergency Preparedness
SHSP = State Homeland Security Program
UASI = Urban Area Security Initiative
County of Los Angeles
All-Hazards Mitigation Plan
Page 196 of 204
8 Plan Maintenance
County of Los Angeles
All-Hazards Mitigation Plan
Page 197 of 204
8.1 Community Participation in Plan Maintenance
3UNA|AlL"VpVTApVa_-]A_wV]]INlNvVNwNLlNTq]Al]yAJ\_aw]NLTV_TpUNLy_A^VJ
nature of hazard landscapes and the evolving understanding of risks. Stakeholders’
N_TATN^N_pwV]]INilValVpV|NLpUlaqTUaqppUNLNvN]ai^N_pA_L^a_VpalV_TilaJNmm
fostering transparency and accountability.
3a^AV_pAV_plA_miAlN_JyA_LJa^^q_VpyV_va]vN^N_ppUNaq_pyUAmaqp]V_NLmNvNlA]
measures for continued public participation:
x Public Access to Hazard Mitigation Documents: A copy of the 2025 AHMP will
be maintained on the Los Angeles County Hazard Mitigation Program website
along with contact information. Los Angeles County OEM will notify the public
aSA_yJUA_TNmalqiLApNmV_J]qLV_T^VpVTApVa_ila[NJpmVLN_pVœNLV_pUN plan
AmpUNyAlNV^i]N^N_pNLvVAmaJVA]^NLVAA_LplALVpVa_A]]aJA]^NLVAJUA__N]m
x Annual Public Engagement Opportunities: Los Angeles County OEM will
endeavor to hold multiple in-person public engagement opportunities for
hazard mitigation to keep the public informed of progress on hazard mitigation
ila[NJpmaIpAV_a_TaV_TiqI]VJSNNLIAJ\A_LNLqJApNpUNiqI]VJAIaqppUN
County’s hazard mitigation efforts.
x Online Portal: A Los Angeles County Hazard Mitigation Program website will be
established to provide the public with more information on hazard mitigation
and project updates. This portal will serve as a mechanism to obtain continuous
public feedback as projects are implemented and offers access to mitigation
resources.
x Standing Advisory Committee: The Hazard Mitigation Advisory Committee will
be expanded to a standing status and will meet at least once per year or more
often as determined necessary to support hazard mitigation projects. The
standing Hazard Mitigation Advisory Committee will be comprised of
representatives from diverse community groups to provide ongoing input and
oversight of hazard mitigation efforts. The standing Hazard Mitigation Advisory
Committee will also serve as an important forum for future updates of the AHMP.
These activities ensure that the community remains informed and actively engaged in
the plan’s implementation and maintenance.
County of Los Angeles
All-Hazards Mitigation Plan
Page 198 of 204
8.2 MonitoringEvaluationA_L"AV_pN_A_JN
To ensure the continued effectiveness of this All-A|AlL "VpVTApVa_ -]A_ "-
effective monitoring and evaluation will be conducted throughout the plan
implementation period. Regular assessments will monitor progress and evaluate the
achievements of the intended outcomes. Performance metrics will be developed to
kqA_pVSypUNV^iAJpaSNAJU^VpVTApVa_AJpVa_A]]awV_TSalLApALlVvN_AL[qmp^N_pmA_L
lNœ_N^N_pm
The plan will be reviewed annually to assess progress on mitigation actions. Annual
review will include the following elements:
x __qA] 0NvVNw :al\mUNNpm vNly yNAl ! aq_py %" wV]] N^AV] NAJU
member of the Hazard Mitigation Advisory Committee an Annual Review
:al\mUNNppaJa^i]NpNmmUaw_V_iiN_LVxpUN__qA]0NvVNw:al\mUNNp
lNŔNJpmpUN"!aJA]A|AlL"VpVTApVa_-]A_0NvVNw3aa]A_LV_J]qLNs the
Sa]]awV_T mNJpVa_m i]A__V_T ilaJNmm UA|AlL ilaœ]N lVm\ AmmNmm^N_p A_L
mitigation strategy. Each member of the Hazard Mitigation Advisory Committee
will email completed worksheets back to LA County OEM to review. LA County
%"wV]]mq^^AlV|NpUNmNœ_LV_TmA_LN^AV]pUN^aqppapUNJa^^VppNN
LLVpVa_A]]ypUNœ_LV_TmSla^pUNlNvVNwwal\mUNNpmwV]]INilNmN_pNLpapUN
full Hazard Mitigation Advisory Committee at its next regular meeting.
x "VpVTApVa_-laTlNmm-la[NJp0Nialpm Mitigation actions will be monitored and
updated using the Mitigation Project Progress Report. During each annual
lNvVNwNAJULNiAlp^N_palATN_JyJqllN_p]yAL^V_VmpNlV_TA^VpVTApVa_ila[NJp
will submit a progress report to LA County OEM. For projects that are being
Sq_LNLIyA"^VpVTApVa_TlA_p"kqAlpNl]ylNialpm^AyINqmNLAmpUN
ilNSNllNL lNialpV_T paa] m mUaw_ V_ iiN_LVx pUN ilaTlNmmlNialp wV]]
LVmJqmmpUNJqllN_pmpApqmaSpUN^VpVTApVa_ila[NJpincluding any changes made
pa pUN ila[NJp VLN_pVSy V^i]N^N_pApVa_ ilaI]N^m A_L LNmJlVINAiilailVApN
strategies to overcome them.
x Post-_JVLN_p"VpVTApVa_0NvVNwFollowing a major disaster event impacting
!am_TN]Nmaq_pyAiamp-disaster review will be initiated by LA County OEM
to evaluate the need to update the AHMP based on the circumstances of the
LVmAmpNlA_LV_JalialApNA_ymiNJVœJ^VpVTApVa_AJpVa_mlNkqired due to the
County of Los Angeles
All-Hazards Mitigation Plan
Page 199 of 204
V_JVLN_pS!aq_py%"œ_LmpUApA_qiLApNpapUN"-Vm_NNLNLpUN
Hazard Mitigation Advisory Committee will be convened to begin drafting the
update.
8.3 Criteria for Updating the Hazard Mitigation Plan
The All-A|AlLm"VpVTApVa_-]A_"- VmlNkqVlNLpaINqiLApNLNvNlyœvNyNAlmV_
compliance with the Disaster Mitigation Act of 2000 (DMA 2000) and FEMA guidance
(44 CFR § 201.6). The update process is not merely an administrative requirement but
a critical mechanism to evaluate the plan’s effectiveness in reducing risk and guiding
mitigation strategies.
0NvVNwaS-AmpJpVa_mA_LSSNJpVvN_Nmm
The update process begins with a thorough review of the mitigation actions outlined
in the previous plan. This includes:
x vA]qApV_TpUNV^i]N^N_pApVa_mpApqmaSNAJUAJpVa_Ja^i]NpNLV_ilaTlNmm_ap
started).
x Assessing the impact and effectiveness of completed actions in reducing hazard
risk.
x NpNl^V_V_TVSpUNaI[NJpVvNmAlNmpV]]lN]NvA_pallNkqVlN^aLVœJApVa_IAmNLa_
new data or circumstances.
2. Integration of New Data and Changing Conditions
x A|AlLilaœ]NmA_LlVm\AmmNmm^N_pmAlNqiLApNLwVpU_NwUA|AlLNvN_pLApA
J]V^ApNmJVN_JNA_LJUA_TNmV_LNvN]ai^N_pal]A_LqmN
x Demographic shifts and infrastructure changes are reviewed to reassess
vulnerability.
x 3NJU_a]aTVJA]ALvA_JN^N_pmalV^ilavNL^aLN]V_Tpaa]mNTA|qm#ApVa_A]
0Vm\_LNx AlNV_JalialApNLpalNœ_NlVm\A_A]ymVm
a^^q_VpyA_L1pA\NUa]LNl_iqp
The update process must actively include community participation to maintain
plA_miAlN_JyA_LN_mqlNpUNi]A_lNŔNJpm]aJA]ilValVpVNm3UVmV_J]qLNm
County of Los Angeles
All-Hazards Mitigation Plan
Page 200 of 204
x Public workshops and surveys.
x Targeted outreach to vulnerable populations including those with Access and
Functional Needs (AFN).
x NNLIAJ\Sla^aq_pyLNiAlp^N_pmJVpVNm#%mA_LlNTVa_A]iAlp_Nlm
4. Performance Evaluation and Metrics
To ensure effectivenesspUNi]A_^AV_pN_A_JNmplApNTyV_J]qLNm
x Annual progress reports that monitor implementation progress and identify
barriers.
x Metrics to evaluate the reduction of risk or exposure over time.
x Documentation of lessons learned from real events and exercises to inform
changes.
0NvVmVa_aSaA]m%I[NJpVvNmA_LJpVa_m
AmNLa_pUNNvA]qApVa_œ_LV_TmpUNi]A_¯mTaA]mA_L^VpVTApVa_AJpVa_mAlNlNvVmNLpa
V^ilavN A]VT_^N_pwVpUJqllN_pJAiAIV]VpVNmlVm\]NvN]m A_LSq_LV_Taiialpq_VpVNm
Each updated action includes:
x Clear responsibilities.
x Realistic timelines.
x Evaluation metrics to measure future success.
8.4 Plan Update
3UN !"-V_J]qLNmA_qiLApNL^NpUaLa]aTySalSqpqlNlNvVmVa_m N_mqlV_T
Ja^i]VA_JNwVpUSNLNlA]A_LmpApNTqVLN]V_NmSq]]i]A_qiLApNwV]]aJJqlNvNlyœvN
years.
x "- 4iLApN VJ\aSSLA County OEM will convene the Hazard
"VpVTApVa_LvVmalya^^VppNNSalA^NNpV_TpalNvVNwpUNwal\mUNNpœ_LV_Tm
and endeavor to begin the process of updating the AHMP in approximately
November 2028. The planning process should begin a minimum of 18 months
prior to the plan’s expiration. !aq_py%"V_Ja_mq]pApVa_wVpUpUNA|AlL
"VpVTApVa_LvVmalya^^VppNNwV]]LNvN]aiAwal\i]A_SalpUNqiLApNJa_LqJp
County of Los Angeles
All-Hazards Mitigation Plan
Page 201 of 204
lNmNAlJUA_LlNvVNwlN]NvA_pLaJq^N_pApVa_LNpNl^V_NUA|AlLmpaINV_J]qLNL
V_pUN"-A_LINTV_pUNilaJNmmpaLlASpA_qiLApNL"-
x Plan Submission and Adoption: %_JNqiLApNLpUNi]A_VmmqI^VppNLpaA]
%1A_L"SallNvVNw4ia_Ja_LVpVa_A]AiilavA]Vp^qmpINALaipNLIy
the Los Angeles County Board of Supervisors and participating jurisdictions to
maintain eligibility for FEMA Hazard Mitigation Assistance (HMA) grants.
8.5 Integration with Other Plans
Los Angeles County is committed to ensuring that hazard mitigation planning is not a
mpA_LA]a_NNSSalpIqpASq]]yV_pNTlApNLJa^ia_N_paSIlaALNlaq_py i]A__V_T
V_VpVApVvNm
ymplApNTVJA]]ywNAvV_TpUNTaA]maI[NJpVvNmA_LAJpVa_maSpUN]]-Hazards
Mitigation Plan (AHMP) into a variety of local and regional plans such as the General
-]A_ AiVpA] ^ilavN^N_p -]A_m ]V^ApN JpVa_ A_L LAipApVa_-]A_m A_L
departmental strategic plansthe County promotes a more cohesive and effective
approach to building long-term resilience. This integration is achieved through
a_TaV_TJa]]AIalApVa_wVpUaq_pyLNiAlp^N_pmJVpVNmA_LlNTVa_A]ATN_JVNmpaA]VT_
]A_L qmN V_SlAmplqJpqlN LNvN]ai^N_p A_L N^NlTN_Jy ilNiAlNL_Nmm NSSalpm wVpU
VLN_pVœNLUA|AlLlVm\m^Iedding hazard mitigation principles into existing policies
and planning mechanisms ensures that they become an inherent part of decision-
^A\V_TilaJNmmNmila[NJpSq_LV_TilValVpV|ApVa_A_L]a_T-term investment strategies
ultimately reducing vulnerabilities and enhancing the resilience of communities across
Los Angeles County.
The Los Angeles County AHMP will be shared across all jurisdictions within the
operational area. Those jurisdictions will have the opportunity to incorporate the 2025
AHMP into their established planning process. The Hazard Mitigation Advisory
a^^VppNNwV]]AmmNmmpUNi]A_ApAyNAl]yIAmVmAJ\_aw]NLTV_TpUNLy_A^VJ_ApqlNaS
hazard landscapes and the evolving understanding of risks. The OEM Hazard
Mitigation Program will make the AHMP available for all county departments to
incorporate into departmental i]A__V_T NSSalpm A_L apUNl lN]NvA_p LaJq^N_pm
produced by Los Angeles County departments.
County of Los Angeles
All-Hazards Mitigation Plan
Page 202 of 204
9 Plan Adoption
County of Los Angeles
All-Hazards Mitigation Plan
Page 203 of 204
9.1 Plan Adoption Overview
Plan Adoption addressed Element F of the Local Mitigation Plan Regulation Checklist
under single jurisdiction plan requirement.
The Los Angeles County Board of Supervisors ofœcially adopted the 2025 All Hazard
Mitigation Plan (AHMP) through a formal resolution on September 9, 2025. A scanned
copy of the resolution is included in Appendix F. The Los Angeles County Ofœce of
Emergency Management (OEM) will retain the resolution for its records, while copies
will be submitted to both Cal OES and FEMA.
This Plan adoption completes the mitigation planning process and department
agencies, stakeholders, and community’s commitment to the goals and actions. It also
recognizes the current planning process and acknowledges changes from the past œve
years and validates the priorities for hazard mitigation actions. It makes the community
eligible for certain FEMA assistance that can fund some mitigation actions.
After being adopted by the Los Angeles County Board of Supervisors, the 2025 AHMP
transitions into the implementation phase. The success of the plan hinges on the
integrating its mitigation strategies and actions into the local plans and policies. The
mitigation action items collectively establish a robust framework to guide the County’s
hazard mitigation strategies over the next œve years. To ensure these strategies are
effective, actionable and well aligned with the county’s long term resilience goals, the
Planning Advisory Committee has set clear objectives. Their prioritized approach
focuses on seamlessly blending mitigation actions with current policies, plans, and
emphasizing collaboration and coherence throughout.
County of Los Angeles
All-Hazards Mitigation Plan
Page 204 of 204
Appendices
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX M
WATER RATE STRUCTURE
City of Arcadia
Utility Rates & Service Charges
The following tables present the City of Arcadia’s 2026 water and sewer rates. Effective January
1, 2026, the City will transition from bi-monthly billing to monthly billing. Seasonal summer
and winter allotments have also been eliminated.
Monthly Meter Charge
240 W. HunƟngton Drive | PO Box 60021 | Arcadia, California 91066-6021 (626) 254-2700 Billing | (626) 254-2700 Customer Service
Single-Family Residential Water Rates
Monthly Service Charge - ($/Month)
Meter Size (In Inches) 5/8" 3/4" 1" 1-1/2" 2" 3" 4" 6"8”10"
Meter Charge $21.31 $21.31 $26.54 $39.61 $55.30 $91.91 $144.21 $274.96 $431.86 $641.06
The table below shows the monthly water service charge by meter size. Most city
have a 5/8-inch to 1-inch
The table below shows the water consumption charge, which is the amount each customer pays
per hundred cubic (HCF) of water used. One HCF equals 748
Monthly Water Rates
Single Family Residential
Tier 1: 0-8 Tier 2: 9-26 Tier 3: >26
$2.61 $3.03 $3.53
HCF x Per Dwelling Unit
Tier 1 6
Tier 2 6 +
Multi-Family Residential Water Rates
Water Rates ($/HCF)
Tier 1 $2.59
Tier 2 $2.93
Multi-Family monthly water rates and tiers based on the number of dwelling units in each
multi-family complex.
Example:
A multi-family residential complex with 10 dwelling units is allocated 60 HCF per month under Tier 1
(6 HCF × 10 dwelling units). Any usage above 60 HCF will be billed under Tier 2.
Commercial, Governmental, Institution, & Irrigation Water Rates
Water Rates ($/HCF)
Commercial $2.75
Governmental, Institution & Irrigation $3.18
Monthly Private Fireline Charges, ($/Month)
Meter Size (In Inches) 5/8" 3/4" 1" 1-1/2" 2" 3" 4" 6" 8” 10"
Meter Charge $7.50 $7.50 $7.50 $7.50 $7.50 $16.66 $32.45 $89.13 $186.89 $333.93
Monthly Private Fireline Charges
240 W. HunƟngton Drive | PO Box 60021 | Arcadia, California 91066-6021 (626) 254-2700 Billing | (626) 254-2700 Customer Service
Monthly Sewer Charges and Rates
Residential Sewer Charges and Rates- ($/Month)
Single Family Multi-Family – Per Dwelling Unit Residential Sewer Only
$9.05 $9.05 $9.05
Service Fee
Metered Water $3.18 per HCF
Deposit (Refundable) $1,681.26
Hydrant Permit $46.06
Meter Relocation $79.65
Meter Installation $159.29
Meter Reread $142.41 per month
Hydrant Rental $32.45 per month
Meter Rental $91.91 per month
Eddy Valve Rental $25.00 per month
Fire Hydrant Service for Construction, Outside Agencies, & Private Use
Service Fees adopted December 2025/ ResoluƟon No. 7663
Commercial, Government, & Institution Sewer Charges and Rates- ($/Month)
Commercial, Government, & Institution $9.05 + $0.67*
*Variable per HCF Billed Water Usage
240 W. HunƟngton Drive | PO Box 60021 | Arcadia, California 91066-6021 (626) 574-2700 Billing | (626) 254-2700 Customer Service
How to Reach Us For more information regarding the City of Arcadia’s utility billing and payment options please visit www.ArcadiaCA.gov/utilityrates or contact us at the following: Utility Billing wb@ArcadiaCA.gov (626) 254-2700 Public Works Services Department publicworks@ArcadiaCA.gov (626) 254-2700 Water Conservation publicworks@ArcadiaCA.gov (626) 574-3000
Other Utility Services Charges
Service Fees adopted April 2025/ ResoluƟon No. 7628
Service Fee
Water Meter Re-Read 1st = No Charge; 2nd in a year =$61.00
Water Meter Turn-Off/On for Property Repairs 1st = No Charge; 2nd in a year =$61.00
Water Meter Turn-On after Services Turned Off (change of ownership/transfer) $122.00 per account; $305.00 after hours
Water Turn-Off Notice for Failure to Test Backflow Prevention Device $141.00
Water Turn-Off / Turn-On for Non-payment
$159.00 during business hours;
$305.00 after business after hours;
* plus 2x monthly water rate for delinquent accounts
Unauthorized Use of Fire Hydrant $147.00 plus cost of water used
Hydrant Flow Test (Performed with Water Model) $285.00 per test
Hydrant Flow Test (Performed in Field) $471.00 per test
Flow Test Meter or Meter Accuracy Test $219.00 per test
Request to Check Water Quality $287.00 plus Laboratory Costs
Standpipe Inspection $275.00
Bacteriological Test for New Development $122.00 plus laboratory costs
Backflow Test and Inspection (New Construction) $273.00
Backflow Administrative Fee $43.00 annual fee
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX N
ORDINANCE NO. 2327 AND RESOLUTION NO. 7430
CITY OF ARCADIA
2025 URBAN WATER MANAGEMENT PLAN
APPENDIX O
RESOLUTION ADOPTING 2025 UWMP AND WSCP