Agenda packet — Glendora City Council, June 9, 2026 (part 5 of 7)

The purpose of the annual evaluation will be to ensure consideration and implementation of the LHMP and document progress to inform future LHMP updates. Future updates to the LHMP will account for any new hazard vulnerabilities, special circumstances, or new information that becomes available. Issues that arise during the annual LHMP evaluation that require changes to the risk assessment, mitigation strategy, and other components of the plan, will be incorporated into the next update of the LHMP in 2030. The questions identified above would remain valid during the preparation of the 2030 plan update.

Glendora Local Hazard Mitigation Plan
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FIVE-YEAR UPDATE
The intent of the five-year update process will be to add new planning process methods, community profile data, hazard data and events, vulnerability analyses, mitigation actions, and goals to the adopted plan so that the LHMP will always be current and up to date. Based on the needs identified by the Planning Team and incorporating information from the annual monitoring and maintenance activities, the update will, at a minimum, include the elements below:
 The update process will be convened 18 months prior to expiration of the existing plan through a Planning Team identified by the City’s Project Management Team.  The hazard risk assessment will be reviewed and updated using the best available information and technologies.
 Based on new/updated information provided by facility owners and available funding, the evaluation of critical facilities and mapping will be updated and improved.  The mitigation actions will be reviewed and revised to account for any actions completed, deferred, or changed to account for changes in the risk assessment or new City policies identified under other planning mechanisms, as appropriate (such as the City’s General Plan).  The draft update will be sent to appropriate agencies for comment.  The public will be given an opportunity to comment prior to adoption.  The City Council will adopt the updated LHMP.

6.2 ADOPTION
The LHMP update will be presented to both the Glendora Planning Commission and the City Council prior to transmittal to Cal OES and FEMA for review. The Glendora City Council is responsible for adopting the LHMP. This formal adoption should take place every five years. Once the plan has received FEMA Approval Pending Adoption, the City Council will be requested to adopt the plan. Upon adoption, the Project Management Team will transmit the adopted plan and resolution to Cal OES.

6.3 INCORPORATION INTO EXISTING PROGRAMS AND

PLANNING MECHANISMS
The effectiveness of the nonregulatory LHMP depends on the implementation of the plan and incorporation of the mitigation action items into City plans, policies, and programs. The City’s General Plan is an integral part of this plan. The City, through updating the General Plan Safety Element concurrent with the LHMP, has planned for the impact of hazards. The LHMP process has allowed the City to review the goals and policies contained in the General Plan Safety Element and identified mitigation actions that will further implement these policies. The City views the Glendora Local Hazard Mitigation Plan
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General Plan and the LHMP as complementary planning documents that work together to achieve the goal of risk and vulnerability reduction to Glendora citizens and property. Many of the ongoing recommendations identified in the mitigation strategy further the goals and policies of the General Plan and other adopted plans. Further, as part of the Safety Element update, the City will acknowledge the LHMP and will continue to incorporate it by reference.

The plan includes a range of action items that, if implemented, would reduce loss from hazard events in the City. Together, the mitigation action items in the LHMP provide the framework for activities that the City may choose to implement over the next five years. The City has prioritized the plan’s goals and identified actions that will be implemented (resources permitting) through existing plans, policies, and programs. In addition to the General Plan, the City will coordinate the recommendations of the LHMP with other existing plans and programs, which include, but are not limited to:
 Glendora General Plan Updates
 County of Los Angeles All-Hazards Mitigation Plan
 Capital Improvement Program
 Glendora Municipal Code
 California Environmental Quality Act Review
As a guidance document, implementation of the mitigation actions can be accomplished most effectively by integrating the LHMP into ongoing programs, policies, and practices. Additional opportunities to integrate the mitigation actions include the following:
 Integration of mitigation actions in emergency response and post-disaster recovery planning.  Ongoing education and outreach programs to increase staff, residents, business owners, employees, and overall community awareness of the risks and opportunities to implement mitigation actions associated with natural hazards.
 Continued coordination with the City and other partner agencies and organizations on emergency operations and training opportunities.
 Continued consideration of hazard implications and opportunities to implement hazard mitigation as City plans, policies, procedures, and practices are prepared and updated.

The LHMP Project Managers (Public Safety Management Analyst and Principal Planner) are responsible for overseeing the plan’s implementation and maintenance through the City’s existing programs. The Public Safety Management Analyst, Principal Planner, or designated appointee will assume lead responsibility for facilitating LHMP implementation and maintenance meetings.

Although the Police Department will have primary responsibility for review, coordination, and promotion, plan implementation and evaluation will be a shared responsibility among all Glendora Local Hazard Mitigation Plan
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departments identified as lead departments in the mitigation action plan. The City will reference and incorporate this LHMP into all relevant planning documents, programs, decisions, processes, and regulations. The LHMP will be reviewed and considered by internal City departments, as applicable plans or programs are drafted or updated in the future. Opportunities to integrate the mitigation action plan into other planning mechanisms and documents will be identified as part of the annual plan monitoring and maintenance described in Section 6.1. 2015 NATURAL HAZARD MITIGATION PLAN PAST INCORPORATION EFFORTS The hazard mitigation actions identified in the City’s previously adopted 2015 Natural Hazard Mitigation Plan were incorporated into existing programs and other planning mechanisms when appropriate. Several successful integrations of the 2015 LHMP are outlined in Table 5-3, as previous mitigation actions marked “completed.” For example, the City implemented Mitigation Reference Number Earthquake 1 and 2 by including seismic hazard mapping data and evacuation information into the LHMP Update and General Plan Safety Element update, as required by State law. Mitigation Reference Number Dam Failure 1 was implemented by including the new dam inundation maps approved by the Division of Safety of Dams into the into the LHMP Update and General Plan Safety Element update. Additionally, the City implemented Mitigation Reference Number Multi-Hazard 9 by reviewing applicable development projects for compliance with existing ordinances, including the Model Water Efficient Landscaping Ordinance and Storm Water and Runoff Pollution Control Ordinance.

6.4 CONTINUED PUBLIC INVOLVEMENT
The City recognizes the need for continued public involvement throughout the five-year planning period to keep community members and partner agencies updated on the LHMP, including socially vulnerable populations. The public will continue to be informed on LHMP actions through regular updates to the City websites and through annual progress reports. The adopted LHMP will remain permanently available for review on the City’s website, with contact information for interested parties to direct comments and concerns. Additionally, the City will ensure continued public involvement through the promotion of hazard and emergency preparedness education, interagency coordinated outreach efforts, public disaster fairs, drills and other hazard awareness campaigns as included in applicable Mitigation Actions in Section 5.0, Hazard Mitigation Strategy.

These mitigation actions include outreach and communication methods designed to appeal to the entire community, including targeted outreach to socially vulnerable populations. All public feedback will be reviewed and considered for incorporation (if deemed appropriate) into the next LHMP update. Additionally, coordination and implementation of individual mitigation actions will involve direct coordination and interaction with the public, such as those involving targeted support to vulnerable or underserved populations, programs to assist property owners and renters to implement risk reduction improvements, and working with Homeowners Associations, property managers, and property owners. Implementation of these mitigation actions will provide additional opportunities for continued public involvement and assist in determining how best to implement Glendora Local Hazard Mitigation Plan
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mitigation actions, assess the effectiveness of the mitigation actions, and identify additional opportunities for mitigation actions to be considered in the next update. Upon initiation of the LHMP update, the Planning Team will review feedback and outreach efforts, which will be analyzed and incorporated into a new public involvement strategy based on the needs and capabilities of the City at the time of the update. At a minimum, this strategy will include the use of the City website, email distribution lists, and social media, as well as coordination with partner agencies and organizations, and will include specific outreach to vulnerable populations.

6.5 POINT OF CONTACT
Primary point of contact for the LHMP:

Julie Linger, P.E., T.E.

Business Services Manager
City of Glendora
150 S. Glendora Avenue
Glendora, CA 91741
(626) 852-4880
[email protected]
Glendora Local Hazard Mitigation Plan
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Section 7.0 | References
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California Department of Conservation, Division of Mines and Geology, Seismic Hazard Zone Report for the Glendora, Azusa, San Dimas, and Baldwin Park 7.5-Minute Quadrangles, Los Angeles County, California, 1998.

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Glendora Local Hazard Mitigation Plan
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Glendora Local Hazard Mitigation Plan
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Federal Emergency Management Agency, The National Dam Safety Program, May 3, 2019, accessed https://www.fema.gov/sites/default/files/2020-08/national-dam-safety_biennialreport-2016-2017.pdf, July 19, 2023.

Federal Emergency Management Agency, Local Mitigation Planning Handbook, May 2023.

Fernandes, S. and Hernández, C., LA Is Drenched. Here's How The Storm Is Impacting The Area, https://laist.com/news/climate-environment/los-angeles-storm-what-you-need-toknow, accessed June 19, 2024.

Gauthier, R., Los Angeles Times, Los Angeles prepares for rainstorms, https://www.latimes.com/local/la-me-ln-los-angeles-rain-storms-photosphotogallery.html, accessed November 21, 2024.

Governor Gavin Newsom, Governor Newsom Eases Drought Restrictions, https://www.gov.ca.gov/2023/03/24/governor-newsom-eases-drought-restrictions/, accessed June 5, 2024.

Guinyard, T., Lopez, A., and Lloyd J., Glendora Police: Evacuate Before It's Too Late, February 2014, https://www.nbclosangeles.com/news/local/mud-debris-flows-reported-inglendora/1972470/, accessed June 13, 2024.

Kiewit, Dams by Kiewit, https://www.linkedin.com/posts/kiewit_dams-by-kiewit-activity7034553427934265344-P1-Z, accessed November 21, 2024.

LADWP, LADWP Crews Prepared as Heavy Rain and Wind Storm Forecasted, Reminds Public to Stay Away from Downed Power Lines, https://www.ladwpnews.com/ladwp-crewsprepared-as-heavy-rain-and-wind-storm-forecasted-reminds-public-to-stay-away-fromdowned-power-lines/ accessed November 21, 2024.

Glendora Local Hazard Mitigation Plan
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Lodevico-To'o, Hazel, Glendora City Manager Estimates $300,000 in Wind Damages, http://glendora.patch.com/articles/glendora-city-manager-estimates-300-000-in-winddamages, published December 7, 2011, accessed June 14, 2024.

Los Angeles County Fire Museum, Timeline of Significant Dates, https://www.lacountyfiremuseum.com/lacofd-timeline/, accessed June 13, 2024.

Los Angeles Homeless Services Authority, Homeless Count By City in the LA CoC, https://www.lahsa.org/homeless-count/dashboards/hc24-localities-dashboard, accessed September 10, 2024.

Margolis, J. and Ujiiye, T., Bridge Fire explodes to 47K acres; more than 30 homes destroyed, https://laist.com/news/climate-environment/bridge-fire-angeles-national-forestevacuations, accessed November 21, 2024 McMillan, R., SoCal Edison warns of possible power shutoffs as powerful Santa Ana winds increase fire threat, https://abc7.com/wind-power-shutoffs-socal-edison-fire/14029054/, accessed June 19, 2024.

Metro Gold Line Foothill Extension Construction Authority, Foothill Gold Line News, https://foothillgoldline.org/dual_content/sign-up-for-e-news/, accessed February 25, 2025.

National Inventory of Dams, Dams of the Nation, https://nid.sec.usace.army.mil/#/, accessed June 4, 2024.

National Oceanic and Atmospheric Administration, Climate Data Online Search: Santa Fe Dam California, CA US, https://www.ncei.noaa.gov/cdoweb/datasets/GHCND/stations/GHCND:USR0000CSFD/detail, accessed June 18, 2024.

National Oceanic and Atmospheric Administration, Climate Variability: Oceanic Niño Index, https://www.climate.gov/news-features/understanding-climate/climate-variability-oceanicnino-index, published August 30, 2009, accessed June 13, 2024.

National Oceanic and Atmospheric Administration, El Niño and La Niña: Frequently asked questions, https://www.climate.gov/news-features/understanding-climate/elni%C3%B1o-and-la-ni%C3%B1a-frequently-askedquestions#:~:text=El%20Ni%C3%B1o%20and%20La%20Ni%C3%B1a%20are%20oppo site%20phases%20of%20a,for%20El%20Ni%C3%B1o%2DSouthern%20Oscillation, accessed June 19, 2024.

National Oceanic and Atmospheric Administration, El Niño/Southern Oscillation (ENSO) Diagnostic Discussion,
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.s html, published June 13, 2024, accessed June 19, 2024.

National Oceanic and Atmospheric Administration, Storm Events Database, https://www.ncdc.noaa.gov/stormevents/, accessed Jun 10, 2024.

Glendora Local Hazard Mitigation Plan
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National Oceanic and Atmospheric Administration, What are El Niño and La Niña?, https://oceanservice.noaa.gov/facts/ninonina.html, accessed June 10, 2024.

National Weather Service Climate Prediction Center, U.S. Seasonal Drought Outlook, https://www.cpc.ncep.noaa.gov/products/expert_assessment/season_drought.png, accessed February 25, 2025.

National Weather Service, A History of Significant Weather Events in Southern California, https://www.weather.gov/media/sgx/documents/weatherhistory.pdf, March 2024.

National Weather Service, Heat Watch vs. Warning, https://www.weather.gov/safety/heat-ww, accessed June 13, 2024.

National Weather Service, NWS Heat Index,
https://www.weather.gov/images/safety/heatindexchart-650.jpg, accessed June 14, 2024.

National Weather Service, Saffir-Simpson Hurricane Wind Scale, https://www.nhc.noaa.gov/aboutsshws.php, accessed June 14, 2024.

National Weather Service, What Constitutes a Severe Thunderstorm, https://www.weather.gov/bmx/outreach_svr, accessed June 13, 2024.

Paulson, Chase, Roberts, and Moody, National Water Summary 1988-89-- Hydrologic Events and Floods and Droughts, 1991.

Southern California Association of Governments, SCAG 6th Cycle Final RHNA Allocation Plan, 2021.

Southern California Earthquake Center, Earthquake Information, https://scedc.caltech.edu/earthquake/faults.html, accessed on June 11, 2024.

Southern California Earthquake Data Center, Significant Earthquakes and Faults, http://scedc.caltech.edu/significant/index.html, accessed June 12, 2024.

Southern California Edison, Public Safety Power Shutoffs, https://www.sce.com/safety/wildfire/psps, accessed March 20, 2019.

The Glendora Press-Gleaner, Glendora Escapes with Minor Damage as Rain Floods Southland Area, March 4, 1938, https://ccdl.claremont.edu/digital/collection/cwd/id/4756, accessed June 10, 2024.

Glendora Local Hazard Mitigation Plan
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APPENDIX A
City Adoption Resolution

PLACEHOLDER FOR RESOLUTION

APPENDIX B
Planning Process Documentation

D e N o v o P l a n n i n g G r o u p
A L a n d U s e P l a n n i n g , D e s i g n , a n d E n v i r o n m e n t a l F i r m

GLENDORA

LOCAL HAZARD MITIGATION PLAN UPDATE
HAZARD MITIGATION PLANNING TEAM MEETING #1
Wednesday, June 28, 2023
10:00 am – 12:00 pm
AGENDA

1. Introductions

2. Roles and Responsibilities
a. Data needs
b. Planning Team meetings

3. Project and LHMP Goals

4. Purpose and Requirements of the LHMP
a. What is Hazard Mitigation and a Hazard Mitigation Plan? b. Plan requirements
c. LHMP process
d. LHMP process – risk assessment

5. Confirm Hazards and Identify Community Assets
a. 2015 LHMP hazards
b. Identify community assets

6. Next Steps
a. Planning Team
b. Plan development

7. Questions/Additional Discussion

Planning Team Meetings:
• July 26, 2023; 10:00 am – 12:00 pm
• August 23, 2023; 10:00 am – 12:00 pm
• October 25, 2023; 10:00 am – 12:00 pm
Local Hazard
Mitigation Plan
Planning Team Meeting #1
June 28, 2023
CityOfGlendora.org
2 AGENDA
• Introductions
• Roles and responsibilities
• Project and LHMP goals
• Purpose and requirements of the LHMP
• LHMP Process
• Confirm hazards and identify community assets
• Next steps
3 ROLES AND RESPONSIBILITIES
• Our Job
• Facilitate the process
• Provide LHMP technical
expertise
• Maintain schedule
• Do the heavy work
• Ensure FEMA-compliant plan
• What We Ask of You
• Participate
• Assist with outreach
• Provide agency-specific
information, local insight and
expertise
• Meet internal deadlines
• Ensure plan is feasible and
meets needs
4 ROLES AND RESPONSIBILITIES
• Data Needs
• Plans/studies
• Policies/programs
• Technical data
• Intrinsic/historic knowledge
• Photos
• Asset inventory for loss estimates
• Any additional relevant information
5 ROLES AND RESPONSIBILITIES
• Planning Team Meetings
• Meeting #1 – June 28: process; confirm hazards and identify community assets
• Meeting #2 – July 26: hazard profiles & mapping; risk assessment • Meeting #3 – August 23: capabilities assessment; mitigation goals and actions
• Meeting #4 – October 25: refine mitigation actions and prioritization

7 PROJECT AND LHMP GOALS
• 2015 LHMP Mitigation Goals
• Protect life and property
• Enhance public awareness
• Preserve natural systems
• Encourage partnerships and implementation
• Strengthen emergency services
• Any revisions/modifications? Other goals?

12 CONFIRM HAZARDS
• 2015 LHMP Hazards
• Earthquakes
• Flood
• Wildfire
• Landslide
• Dam Failure
• Windstorm
Climate change and risks will need to be integrated into the update 13 IDENTIFY COMMUNITY ASSETS
• Assets are anything important to the character and function of a community
• People, including underserved communities and socially vulnerable populations
• Structures, including new and existing buildings
• Community lifelines and other critical facilities
• Natural, historic and cultural resources
• Economy and other activities that have value to the community

16 NEXT STEPS
• Plan Development
• Confirm LHMP template
• Update community profile
• Update/prepare hazard profiles and mapping
• Confirm outreach strategy
17 Questions/Additional Discussion?

Local Hazard
Mitigation Plan
Planning Team Meeting #2
July 26, 2023
CityOfGlendora.org
2 AGENDA
• Hazards to be Profiled
• Critical Facilities
• Problem/Issue Statements
• Capabilities Assessment
• Review Existing Mitigation Actions
• Public Involvement Update
• Next Steps

5 CRITICAL FACILITIES
• Risk assessment will look at what facilities are in hazard zones • Considers their replacement cost and value to the community • Mitigation strategies reflect vulnerabilities of critical facilities • Strengthen existing vulnerable facilities
• Avoid building new ones in at-risk areas
6 Critical Facilities
• Current Plan
• City Hall
• Police Department
• Fire Station No. 85
• Fire Station No. 86
• Fire Station No. 151
• Additions/Revisions
• Schools
• Hospitals - dialysis centers, urgent care
• Community Facilities
• La Fetra
• Teen Center
• Library
• Legion building
• Infrastructure – water/wastewater
• Others?

8 CAPABILITIES ASSESSMENT
• Two components
• Inventory of existing resources and tools to accomplish mitigation and reduce long-term vulnerability, and understanding of ability to use them effectively • Identification of gaps, conflicts, and/or weaknesses that may need to be addressed through mitigation
• Types of capabilities
• Planning and regulatory
• Administrative and technical
• Financiald
• Education and outreach
9 CAPABILITIES ASSESSMENT
• Planning and regulatory
• Ordinances
• Policies
• Local laws and state statutes
• Plans and program that guide and manage growth
• Questions to consider:
• 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? • How can the capabilities be expanded and improved to reduce risk? 10 CAPABILITIES ASSESSMENT
• Administrative and technical
• City staff – skills/tools and capacity
• Public and private resources
• Ability to access and coordinate resources effectively • Questions to consider:
• Is coordination effective?
• Is staffing adequate to enforce regulations?
• Is staff trained on hazards and mitigation?
• Is coordination between agencies and staff effective? • Has the capability been used to assess/mitigate risk in the past? • How can the capabilities be expanded and improved to reduce risk? 11 CAPABILITIES ASSESSMENT
• Financial
• Resources have or eligible to use to fund mitigation
• Staff time, existing operating budgets, impact fees
• Local, state and federal funding sources
• Questions to consider:
• Has the funding resource been used in the past and for what types of activities?
• Could the resource be used to fund future mitigation actions? • How can the capabilities be expanded and improved to reduce risk? 12 CAPABILITIES ASSESSMENT
• Education and outreach
• Programs and methods in place to implement mitigation actions and communicate hazard-related information
• Fire safety programs, education programs
• Public information or communication activities
• Questions to consider:
• Could the program/organization help to implement future mitigation activities?
• How can the capabilities be expanded and improved to reduce risk?

14 REVIEW EXISTING MITIGATION ACTIONS
• Mitigation actions – reduce or eliminate long-term risk • Different from actions to prepare or respond to an event • Mitigation activities lessen or eliminate the need for preparedness or response resources
• Emphasis on the impact or vulnerabilities – not on the hazard itself

16 NEXT STEPS
• Planning Team
• Provide any information or resources to Julie Linger
• Distribute/Advertise Survey and The Prepare Fair
• Send links or screenshots to Julie and/or Starla
• Attend Meeting #3 August 23, 2023
17 NEXT STEPS
• Plan Development
• Finalize draft hazard profiles and mapping
• Prepare and conduct outreach
• Initiate risk assessment
• Complete capabilities assessment
18 Questions/Additional Discussion?

Safety Element and LHMP Survey Social Media Posts
guide development of the LHMP and Safety Element. Please visit https://www.cityofglendora.org/departments/community-development/advanced-planningcommunity-engagement to learn more and to take the survey.

Nixle:

Glendora is updating its Local Hazard Mitigation Plan and Safety Element! The City has an online survey to understand the community's concerns on natural hazard events such as earthquakes and wildfires, and human-caused events such as hazardous spills. Please visit https://www.surveymonkey.com/r/FPNX2TK to take the survey and help the community prepare and respond to those hazards.

City of Glendora Local Hazard Mitigation Plan & Safety Element Update 1 / 28

89.57% 146

28.22% 46

6.75% 11
Q1 Do you... (Check all that apply)
Answered: 163 Skipped: 1
Total Respondents: 163
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Live in
Glendora
Work in
Glendora
Visit
Glendora, bu...

ANSWER CHOICES RESPONSES
Live in Glendora
Work in Glendora
Visit Glendora, but live and work elsewhere
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 2 / 28

0.61% 1

2.45% 4

7.98% 13

24.54% 40

22.70% 37

16.56% 27

23.93% 39

1.23% 2
Q2 What is your age group?
Answered: 163 Skipped: 1
TOTAL 163
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Under 18
18-24
25-34
35-44
45-54
55-64
65+
Prefer not to
answer

ANSWER CHOICES RESPONSES
Under 18
18-24
25-34
35-44
45-54
55-64
65+
Prefer not to answer
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 3 / 28
Q3 Which of the following types of hazards have you or someone in your household experienced while residing and/or working in Glendora? Answered: 163 Skipped: 1
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Wildfire
High
Winds/Santa...

Earthquake
ground shaking
Heavy rain
Extreme heat
Dam/reservoir
failure
Flood
Drought
Hazardous
materials...

Landslide/mudfl
ow
Power outage
None
Other (please
specify)
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 4 / 28

68.71% 112

77.30% 126

71.78% 117

82.21% 134

81.60% 133

0.61% 1

6.13% 10

58.90% 96

1.84% 3

11.04% 18

78.53% 128

0.00% 0

5.52% 9
Total Respondents: 163

ANSWER CHOICES RESPONSES
Wildfire
High Winds/Santa Anas
Earthquake ground shaking
Heavy rain
Extreme heat
Dam/reservoir failure
Flood
Drought
Hazardous materials incidents/spills
Landslide/mudflow
Power outage
None
Other (please specify)
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 5 / 28
Q4 How concerned are you that the following hazards will happen in or impact Glendora? Please check ONE response for each hazard.

Answered: 164 Skipped: 0
Wildfire
High
Winds/Santa...

Earthquake
ground shaking
Heavy rain
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 6 / 28
Extreme heat
Dam/reservoir
failure
Flood
Drought
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 7 / 28
Hazardous
materials...

Landslide/mudfl
ow
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 8 / 28

40.24%
66 29.88%
49 20.12%
33 7.32%
12 2.44%
4 164 3.98

18.87%
30 32.70%
52 27.67%
44 15.09%
24 5.66%
9 159 3.44

23.93%
39 30.06%
49 26.99%
44 14.72%
24 4.29%
7 163 3.55

8.54%
14 28.66%
47 32.32%
53 17.68%
29 12.80%
21 164 3.02

24.69%
40 29.01%
47 22.22%
36 12.96%
21 11.11%
18 162 3.43

6.83%
11 8.07%
13 18.01%
29 31.68%
51 35.40%
57 161 2.19

6.17%
10 10.49%
17 23.46%
38 32.72%
53 27.16%
44 162 2.36

27.16%
44 23.46%
38 25.93%
42 16.67%
27 6.79%
11 162 3.48

5.00%
8 7.50%
12 22.50%
36 32.50%
52 32.50%
52 160 2.20

7.98%
13 14.72%
24 22.70%
37 34.36%
56 20.25%
33 163 2.56

24.54%
40 26.99%
44 25.15%
41 19.02%
31 4.29%
7 163 3.48

17.65%
9 1.96%
1 15.69%
8 5.88%
3 58.82%
30 51 2.14
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Extremely … Very Conce… Concerned Somewhat …
Not Concer…

EXTREMELY

CONCERNED
VERY

CONCERNED

CONCERNED SOMEWHAT

CONCERNED
NOT

CONCERNED

TOTAL WEIGHTED

AVERAGE
Wildfire
High Winds/Santa
Anas
Earthquake ground
shaking
Heavy rain
Extreme heat
Dam/reservoir
failure
Flood
Drought
Hazardous
materials
incidents/spills
Landslide/mudflow
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 9 / 28
Q5 What do you believe is the likelihood that these hazards will occur in or impact the City of Glendora? Please check ONE for each hazard.

Answered: 164 Skipped: 0
Wildfire
High
Winds/Santa...

Earthquake
ground shaking
Heavy rain
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 10 / 28
Extreme heat
Dam/reservoir
failure
Flood
Drought
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 11 / 28
Hazardous
materials...

Landslide/mudfl
ow
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 12 / 28

46.95%
77 32.93%
54 10.37%
17 8.54%
14 1.22%
2 164 4.38

46.34%
76 32.32%
53 13.41%
22 7.93%
13 0.00%
0 164 4.33

35.98%
59 34.15%
56 20.12%
33 8.54%
14 1.22%
2 164 4.17

22.56%
37 34.15%
56 26.83%
44 14.63%
24 1.83%
3 164 3.98

46.88%
75 28.75%
46 17.50%
28 3.75%
6 3.13%
5 160 4.33

2.53%
4 4.43%
7 23.42%
37 27.85%
44 41.77%
66 158 4.21

4.35%
7 11.18%
18 27.33%
44 36.65%
59 20.50%
33 161 3.98

38.65%
63 30.06%
49 18.40%
30 10.43%
17 2.45%
4 163 4.23

1.26%
2 6.92%
11 22.64%
36 40.25%
64 28.93%
46 159 4.08

6.88%
11 20.63%
33 30.63%
49 31.25%
50 10.63%
17 160 3.87

37.04%
60 39.51%
64 17.90%
29 3.09%
5 2.47%
4 162 4.22

13.33%
6 2.22%
1 20.00%
9 2.22%
1 62.22%
28 45 4.56
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Extremely … Very Likely Likely Somewhat …
Not Likely

EXTREMELY
LIKELY
VERY
LIKELY

LIKELY SOMEWHAT
LIKELY
NOT
LIKELY

TOTAL WEIGHTED

AVERAGE
Wildfire
High Winds/Santa Anas
Earthquake ground shaking
Heavy rain
Extreme heat
Dam/reservoir failure
Flood
Drought
Hazardous materials
incidents/spills
Landslide/mudflow
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 13 / 28
Q6 Rank the hazards based on the likelihood of potential threat to Glendora with 1 being the HIGHEST threat and 10 being the LOWEST threat.

Answered: 164 Skipped: 0
Wildfire
High
Winds/Santa...

City of Glendora Local Hazard Mitigation Plan & Safety Element Update 14 / 28
Earthquake
ground shaking
Heavy rain
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 15 / 28
Extreme heat
Dam/reservoir
failure
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 16 / 28
Flood
Drought
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 17 / 28
Hazardous
materials...

Landslide/mudfl
ow
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 18 / 28
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
1 (highest) 2 3 4
5 6 7 8
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 19 / 28

57.93%
95 16.46%
27 9.15%
15 6.10%
10 4.27%
7 1.83%
3 0.61%
1 1.22%
2 1.22%
2 1.22%
2 21.74%
35 26.09%
42 15.53%
25 11.18%
18 8.70%
14 7.45%
12 4.35%
7 1.86%
3 2.48%
4 0.62%
1 21.74%
35 16.77%
27 21.74%
35 11.18%
18 13.04%
21 6.21%
10 4.35%
7 1.86%
3 0.62%
1 2.48%
4 10.69%
17 13.21%
21 16.98%
27 21.38%
34 15.72%
25 10.06%
16 5.66%
9 3.77%
6 1.89%
3 0.63%
1 24.22%
39 18.01%
29 22.36%
36 13.04%
21 11.18%
18 3.11%
5 1.86%
3 1.86%
3 2.48%
4 1.86%
3 1.88%
3 2.50%
4 5.00%
8 7.50%
12 12.50%
20 7.50%
12 10.00%
16 9.38%
15 15.00%
24 28.75%
46 5.03%
8 3.77%
6 9.43%
15 9.43%
15 13.84%
22 10.69%
17 15.09%
24 10.69%
17 12.58%
20 9.43%
15 25.32%
40 13.29%
21 11.39%
18 10.13%
16 14.56%
23 8.23%
13 7.59%
12 5.70%
9 1.90%
3 1.90%
3 1.88%
3 0.63%
1 1.25%
2 4.38%
7 22.50%
36 5.00%
8 13.13%
21 13.13%
21 15.00%
24 23.13%
37 4.46%
7 2.55%
4 15.29%
24 14.65%
23 12.10%
19 10.83%
17 12.10%
19 13.38%
21 8.28%
13 6.37%
10 26.25%
42 17.50%
28 18.13%
29 5.63%
9 13.75%
22 4.38%
7 3.75%
6 5.63%
9 1.88%
3 3.13%
5 16.67%
6 0.00%
0 2.78%
1 0.00%
0 16.67%
6 2.78%
1 8.33%
3 0.00%
0 0.00%
0 52.78%
19 5 6 7 8
9 10 (lowest)
1 (HIGHEST)
2 3 4 5 6 7 8 9 10
(LOWEST)
Wildfire
High Winds/Santa
Anas
Earthquake
ground shaking
Heavy rain
Extreme heat
Dam/reservoir
failure
Flood
Drought
Hazardous
materials
incidents/spills
Landslide/mudflow
Power outage
Other
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 20 / 28

22.97% 34

77.03% 114
Q7 Is there a hazard not listed above that you think is a wide scale threat to Glendora?
Answered: 148 Skipped: 16
TOTAL 148
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Yes
No

ANSWER CHOICES RESPONSES
Yes
No
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 21 / 28

9.15% 15

50.00% 82

23.17% 38

9.76% 16

6.10% 10

1.83% 3
Q8 How prepared is your household to deal with a hazard event likely to occur in Glendora?
Answered: 164 Skipped: 0
TOTAL 164
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Not at all
Prepared
Somewhat
Prepared
Adequately
Prepared
Well Prepared
Very Well
Prepared
Not Sure

ANSWER CHOICES RESPONSES
Not at all Prepared
Somewhat Prepared
Adequately Prepared
Well Prepared
Very Well Prepared
Not Sure
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 22 / 28

77.64% 125

22.36% 36
Q9 Have you taken actions to make your home, business, or neighborhood more resistant to hazards (such as anchored furniture and service utilities, maintain functioning smoke detectors, regularly trimmed trees, annually cut-down dry weeds to reduce fire hazards, etc.)?
Answered: 161 Skipped: 3
TOTAL 161
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Yes
No

ANSWER CHOICES RESPONSES
Yes
No
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 23 / 28
Q10 Choose the top 3 ways you prefer to receive information about how to make your home and neighborhood more resistant to hazards? Answered: 164 Skipped: 0
None of the
above
Auto-dial
information...

Books and/or
magazines
Community
Emergency...

Chamber of
Commerce
City/Agency
newsletters
City/Agency
website
Community
safety events
County website
Direct mail
Email
Fair booths
and/or...

Faith-based
institutions
Fire Department
Informational
brochures
Law enforcement
National
Weather Serv...

Non-governmenta
l organizati...

City of Glendora Local Hazard Mitigation Plan & Safety Element Update 24 / 28
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Public
awareness...

Public library
Public
meetings,...

Radio based
media (news ...

Schools and
academic...

Social media
(Twitter,...

State/Federal
website
TV based media
(news and...

Word of mouth
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 25 / 28

2.44% 4

8.54% 14

6.71% 11

14.63% 24

5.49% 9

26.22% 43

28.66% 47

13.41% 22

3.05% 5

20.73% 34

37.80% 62

4.27% 7

1.83% 3

6.71% 11

9.15% 15

4.88% 8

7.32% 12

0.00% 0

10.37% 17

3.66% 6

10.37% 17

6.71% 11

2.44% 4

34.15% 56

0.61% 1

5.49% 9

1.22% 2
Total Respondents: 164

ANSWER CHOICES RESPONSES
None of the above
Auto-dial information from “911” center
Books and/or magazines
Community Emergency Response Training (CERT) classes
Chamber of Commerce
City/Agency newsletters
City/Agency website
Community safety events
County website
Direct mail
Email
Fair booths and/or festivals
Faith-based institutions
Fire Department
Informational brochures
Law enforcement
National Weather Service website
Non-governmental organizations (Red Cross)
Public awareness campaigns (Flood Awareness Week; the Great Shakeout) Public library
Public meetings, workshops, and/or classes
Radio based media (news and public service announcements) Schools and academic institutions
Social media (Twitter, Facebook, LinkedIn, Instagram)
State/Federal website
TV based media (news and public service announcements)
Word of mouth
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 26 / 28

86.50% 141

67.48% 110

73.62% 120

44.79% 73

4.29% 7
Q11 How can your City, County or other Agencies help you become better prepared for disaster? Choose all that apply.

Answered: 163 Skipped: 1
Total Respondents: 163
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Provide
effective...

Offer training
and educatio...

Provide
community...

Create
awareness of...

Other (please
specify)

ANSWER CHOICES RESPONSES
Provide effective emergency notifications and communications in a disaster Offer training and education to residents and business owners on how to reduce risk Provide community outreach regarding emergency preparedness and evacuation procedures Create awareness of special needs and vulnerable populations Other (please specify)
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 27 / 28
Q12 Please utilize the space below to provide any additional comments regarding local hazards, disasters, and preparedness.

Answered: 21 Skipped: 143
City of Glendora Local Hazard Mitigation Plan & Safety Element Update 28 / 28

43.04% 68

56.96% 90
Q13 Would you like to review and comment on the drafts of the Glendora Local Hazard Mitigation Plan and Safety Element?
Answered: 158 Skipped: 6
TOTAL 158
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Yes
No

ANSWER CHOICES RESPONSES
Yes
No

Hazard Planning
in Glendora
Focus Group Meetings
April 2024
CityOfGlendora.org

Hazard Examples
Earthquakes
Landslides
Floods
Lighting Storms
Extreme Heat
Extreme Cold
Wildfires
Windstorms
Drought
Pests
Disease
Cyber Attacks

Hazards Identified
Earthquakes
Landslides/Mudflow
Floods & Dam Failure
Heavy Rain Storms
Extreme Heat
Extreme Cold
Wildfires
Santa Ana Winds
Drought

Thank You!
For additional information and updates:
https://www.cityofglendora.org/departments/communitydevelopment/advanced-planning-community-engagement Emergency preparedness website:
https://www.cityofglendora.org/departmentsservices/police/emergency-preparedness Smart911: Create a profile at
https://www.smart911.com/smart911/ref/reg.action?pa=glendorapd What is the LHMP Planning Process?

18 IDENTIFY COMMUNITY ASSETS
• Assets are anything important to the character and function of a community
• People, including underserved communities and socially vulnerable populations
• Structures, including new and existing buildings
• Community lifelines and other critical facilities
• Natural, historic and cultural resources
• Economy and other activities that have value to the community

Mitigation Examples 1
• Local plans and regulations
– General Plan
– Zoning ordinances
– Subdivision regulations
– Building codes
– Capital improvement programs
– Structure and infrastructure projects
– Acquisition, relocation, elevation of flood-prone structures – Levees and floodwalls
– Seismic retrofitting
– Strengthening critical facilities
– Burying utility lines
– Stormwater diversion, retention, or detention
20 Mitigation Examples 2
• Natural Systems Protection
– Floodplain protection
– Wetlands preservation
– Coastal or riverine setbacks
– Sediment and erosion control
– Forest and vegetative management
– Education and Awareness Programs
– Risk communication
– Community events
– Brochures/written materials
– Website with maps/information
– Educational programs
21 APPENDIX E
COUNTY OF LOS ANGELES’ ALL-HAZARDS MITIGATION PLAN

Page 1 of 204 ends

2025 County of Los Angeles
All-Hazards Mitigation Plan
Chief Executive Office - Office of Emergency Management County of Los Angeles
All-Hazards Mitigation Plan

Page 1 of 204 ends

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
Chief Executive Office
Chief Sustainability Office
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
California Governor’s Office of Emergency Services (Cal OES) 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
Los Angeles County Office of Education
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
Cover Photo Credits: Los Angeles County Chief Executive Office, Countywide Communications Branch; Los Angeles County Department of Public Works
County of Los Angeles
All-Hazards Mitigation Plan

Page 3 of 204 ends

Table of Contents
Acknowledgement ................................................................................................................. 1 Letter of Promulgation ........................................................................................................... 2 1 Introduction, Purpose, and Scope ................................................................................ 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 Community Profile ........................................................................................................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 Integrating Climate Change into Hazard Profiles ...............................................34

4.3 Climate Mitigation Strategies................................................................................36

4.4 Climate Change Conclusion .................................................................................37 County of Los Angeles
All-Hazards Mitigation Plan

Page 4 of 204 ends

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 Hazard Identification and Risk Assessment ...............................................................43

6.1 Hazard Identification Overview.............................................................................44

6.2 Wildfire.....................................................................................................................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 Identification and Analysis of Mitigation Strategies .........................................172 County of Los Angeles
All-Hazards Mitigation Plan

Page 5 of 204 ends

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 Monitoring, Evaluation, and Maintenance.........................................................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 ends

1 Introduction, Purpose,
and Scope
County of Los Angeles
All-Hazards Mitigation Plan

Page 7 of 204 ends

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 stakeholders from cities, local utilities, non-governmental organizations, and state 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 hazard mitigation as a critical step in reducing hazard risks, making communities safer, and building countywide resilience.

1.2 Scope
Hazard mitigation is defined in the Code of Federal Regulations (CFR) as “any sustained action taken to reduce or eliminate the long-term risk to human life and property from hazards.” This AHMP identifies and profiles hazards, analyzes the people and critical infrastructure at risk, and provides a series of mitigation strategies aimed at reducing 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 hazard mitigation and, while not an emergency plan, complements the Los Angeles 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 of 2000 emphasized the need for state, tribal, and local entities to closely 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 ends

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) sections, excluding the Appendices, including:

1. Introduction: Discusses the purpose, scope, and legal authority of the plan.

2. Planning Process: Describes the planning process that was undertaken by the Hazard Mitigation Planning Committee to create this updated 2025 AHMP.

3. Community Profile: Overviews the unique geographic, climatic, environmental, 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. Hazard Identification and Risk Assessment: Identifies and profiles nine (9) natural and four (4) human-caused hazards that may impact Los Angeles County including: wildfire, earthquake, extreme heat, drought, flooding, dam failure, land movement, tsunami, severe wind and tornado, mass violence, cybersecurity incidents, transportation incidents, and public health emergencies.

7. Mitigation Strategy: Delineates the overall strategy for the County’s hazard mitigation efforts including goals and objectives, existing mitigation capabilities, and an analysis of mitigation actions.

8. Plan Maintenance: Outlines how the plan will be maintained annually ahead of the next full plan update in five years.

9. Plan Adoption: Discusses updates to the plan and implementation following plan adoption.

Following these sections, there are an additional six (6) appendices with supporting materials such as hazard maps, meeting minutes from planning meetings, and information about the public engagement efforts during the planning process.

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2 Planning Process
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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 Mitigation Plan, while incorporating new methodologies, stakeholder engagement, and compliance requirements. The planning process for this update emphasized inclusivity, transparency, and the integration of emerging climate adaptation considerations.

This planning process followed a structured, phased approach aligned with FEMA’s Local Mitigation Planning Policy Guide (2022), 44 CFR requirements, and guidance from the California Governor’s Office of Emergency Services (Cal OES). This approach began with project initiation where the scope, timeline, and stakeholders were defined.

Stakeholder and public engagement were prioritized to ensure representation from diverse groups, including historically underrepresented communities and climatevulnerable populations.

Data collection and analysis leveraged updated hazard, climate, and vulnerability data from local, state, and federal sources, providing a foundation for enhanced risk and vulnerability assessments. Hazard profiles were updated to include climate projections 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 component of the AHMP. Finally, methods for monitoring and evaluation of mitigation efforts were defined in the plan maintenance and implementation strategy. Table 2-1 provides a timeline of the major plan update tasks and milestones over the planning process.

Table 2-1 AMHP Planning Timeline
Date Tasks People Involved
February
2025
Reviewed the 2020 AHMP and identified
components that require update.

OEM AHMP Project
Team
Collected and reviewed existing
documents, including the Threat and
Hazard Identification and Risk
Assessment (THIRA) along with resources
for people with access and functional
OEM AHMP Project
Team
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Date Tasks People Involved
needs and people experiencing
homelessness.

February
2025
Met with state Hazard Mitigation
Planning Team.

OEM AHMP Project
Team, Cal OES
Mitigation Division
Identified the initial list of stakeholders
and ensured organizations that work with
and represent people with access and
functional needs were engaged in the
planning process. External stakeholders
include neighboring communities, local
and regional agencies, and others.

OEM AHMP Project
Team
Conducted 2025 AHMP Kickoff Meetings
with internal stakeholders.

OEM AHMP Project
Team, Internal County
Stakeholder Group, Cal
OES Mitigation Division
Determined hazards to be profiled
including both natural (i.e., wildland fire,
earthquake, etc.) and human-caused (i.e.,
cybersecurity, terrorism, etc.).

OEM AHMP Project
Team, Internal County
Stakeholder Group,
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
Team, Internal County
Stakeholder Group,
External Stakeholder
Group, Cal OES
Mitigation Division
Met with internal and external
stakeholders to obtain feedback on draft
plan elements.

OEM AHMP Project
Team, Internal County
Stakeholder Group,
External Stakeholder
Group, Cal OES
Mitigation Division
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Date Tasks People 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
Team, Cal OES
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
Team, Internal County
Stakeholder Group,
External Stakeholder
Group, Cal OES
Mitigation Division
April/May
2025
Drafted final sections of the 2025 AHMP
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
Team, Internal County
Stakeholder Group,
External Stakeholder
Group, Cal OES
Mitigation Division
Produced Final AHMP. OEM AHMP Project
Team
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2.2 Stakeholder Engagement
Inclusive stakeholder involvement was essential to the planning process. The County ensured broad representation and participation, consistent with the "Whole Community Approach" outlined in the 2023 Operational Area Emergency Operations Plan (OAEOP). Key stakeholders that comprised the Hazard Mitigation Advisory Committee included:
• County departments such as, but not limited to, Public Works, Public Health, and Regional Planning.
• Cities within the operational area (OA) and neighboring communities through Disaster Management Area Coordinators (DMACs) and city representation. • Non-governmental organizations (NGOs), including environmental and 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.

Regular meetings, workshops, and focus groups were held to gather input and refine 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 feedback was documented and incorporated into the plan, ensuring 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 – Internal Stakeholder Group Department/
Agency
Name Title Planning Contribution
Los Angeles County
Office of
Emergency
Management (OEM
AHMP Project
Team)
Michael
Morin
Emergency
Management
Coordinator
Functioned as lead planners,
led planning meetings,
drafted plan, reviewed
mitigation actions submitted
Matthew by departments.

Topoozian
Emergency
Management
Coordinator
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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
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Henry
Lopez
Program
Manager
Carin
Anderson
Administrative
Services
Manager
Keilah
Kelso
Administrative
Services
Manager
Los Angeles County
Chief Executive
Office – AntiRacism, Diversity,
and Inclusion
Initiative
Cesar
Sanchez
Senior Analyst Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Chief Executive
Office – Homeless
Initiative
Onnie
Williams III
Principal Analyst Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Chief Sustainability
Office
Matthew
Gosner
Climate
Resilience
Officer
Attended planning meetings,
reviewed section drafts, and
provided feedback.

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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 meetings,
reviewed section drafts, and
provided feedback.

Vanessa
Huerta
Safety Officer
Los Angeles County
Department of
Economic
Opportunity
Maritza
Dubie
Human Services
Administrator
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Department of
Health Services
Elaine
Forsyth
Senior Nursing
Instructor
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Isabel
Sanchez
Disaster
Services
Specialist
Los Angeles County
Department of
Human Resources
Kevin
Halbritter
Deputy
Compliance
Officer
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Department of
Parks and
Recreation
Ramon
Bernal
Disaster
Services Analyst
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Department of
Public Health
Elizabeth
Rubin
Epidemiologist Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Department of
Public Social
Services
Manuel
Gutierrez
Disaster
Services Analyst
Attended planning meetings,
reviewed section drafts, and
provided feedback.

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Department/
Agency
Name Title Planning Contribution
Los Angeles County
Department of
Public Works
Joseph
Marble
Disaster
Services Analyst
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Loni Eazell Disaster
Services
Specialist
Los Angeles County
Department of
Regional Planning
Thuy Hua Supervising
Planner
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Edgar De
La Torre
Principal
Regional
Planner
Los Angeles County
Fire Department
Nick
Duvally
Deputy Fire
Chief
Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Internal Services
Department
Juan-Raul
Cardenas
GIS Analyst Attended planning meetings,
reviewed section drafts, and
provided feedback.

Los Angeles County
Sheriff’s
Department
Jordan
Kennedy
Sergeant Attended planning meetings,
reviewed section drafts, and
provided feedback.

Table 2-3 Hazard Mitigation Advisory Committee – External Stakeholder Group Department/Agency Planning Contribution
Access Services Attended planning meetings, reviewed section drafts, and provided feedback.

Alzheimer’s Association
California
Attended planning meetings, reviewed section
drafts, and provided feedback.

California Governor’s Office
of Emergency Services
Attended planning meetings, reviewed section
drafts, and provided feedback.

Catholic Charities Attended planning meetings, reviewed section drafts, and provided feedback.

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Department/Agency Planning Contribution
City of Beverly Hills
Emergency Management
Division
Attended planning meetings, reviewed section
drafts, and provided feedback.

City of Long Beach Disaster
Preparedness & Emergency
Communications
Attended planning meetings, reviewed section
drafts, and provided feedback.

City of Los Angeles
Emergency Management
Department
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disability Community
Resource Center
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area A
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area B
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area C
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area D
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area E
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area F Attended planning meetings, reviewed section drafts, and provided feedback.

Disaster Management Area
Coordinator, Area G
Attended planning meetings, reviewed section
drafts, and provided feedback.

Disaster Management Area
Coordinator, Area H
Attended planning meetings, reviewed section drafts, and provided feedback.

Eastern Los Angeles
Regional Center
Attended planning meetings, reviewed section
drafts, and provided feedback.

Emergency Network Los
Angeles
Attended planning meetings, reviewed section
drafts, and provided feedback.

Habitat for Humanity Attended planning meetings, reviewed section drafts, and provided feedback.

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Department/Agency Planning Contribution
Harbor Regional Center Attended planning meetings, reviewed section drafts, and provided feedback.

Lanterman Regional Center Attended planning meetings, reviewed section drafts, and provided feedback.

Los Angeles County Office of
Education
Attended planning meetings, reviewed section
drafts, and provided feedback.

Los Angeles County
Sanitation Districts
Attended planning meetings, reviewed section
drafts, and provided feedback.

Los Angeles Metropolitan
Transportation Authority
Attended planning meetings, reviewed section
drafts, and provided feedback.

Los Angeles Regional Food
Bank
Attended planning meetings, reviewed section
drafts, and provided feedback.

Neighborhood Legal
Services of Los Angeles
County
Attended planning meetings, reviewed section
drafts, and provided feedback.

Puente Hills Habitat
Preservation Authority
Attended planning meetings, reviewed section
drafts, and provided feedback.

South Central Los Angeles
Regional Center
Attended planning meetings, reviewed section
drafts, and provided feedback.

Westside Regional Center Attended planning meetings, reviewed section drafts, and provided feedback.

2.3 Public Involvement and Outreach
Public outreach efforts aimed to foster transparency, inclusivity, and fortify public trust.

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 as each section was drafted and reviewed by planning stakeholders, it was concurrently made available for public commentary. To accomplish this, each section was posted 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 County of Los Angeles
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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.

To address equity, targeted outreach efforts focused on engaging historically underrepresented communities and AFN populations, using multilingual and accessible materials and culturally appropriate techniques. Aside from public outreach, stakeholders that work with or represent people with access and functional needs, people experiencing homelessness, and a diverse array of cultural groups were 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 served as the foundational document for this update. Additionally, key concepts from the 2023 Operational Area Emergency Operations Plan (OAEOP), such as Emergency Support Functions (ESFs) and disaster management areas, were integrated. The Los Angeles County Climate Vulnerability Assessment provided valuable insights into climate risks and social sensitivity, while local Climate Action Plans ensured alignment with municipal climate adaptation initiatives. Furthermore, the 2021 UASI THIRA (Threat and Hazard Identification and Risk Assessment) provided critical data for identifying evolving threats and capability targets, enhancing the accuracy and relevance of the plan. The demographic data from the 2020 U.S. Census was utilized to ensure an accurate representation of Los Angeles County's population, now estimated at over 10 million residents. The demographic breakdown includes 48% Hispanic or Latino, 26% White, 15% Asian, 8% African American, and 3% other, with over 40% speaking a language other than English at home, emphasizing the need for multilingual and culturally appropriate outreach.

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Table 2-4 Existing Plans, Maps, and Reports
Plan, Map, or Report Information to be Incorporated into the 2025 Updated AHMP
Los Angeles County
Operational Area
Emergency Operations
Plan (2023)
Used to inform Section 6: Hazard Identification and
Risk 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 6: Hazard Identification and
Risk Assessment and Section 7: Mitigation Strategy
for elements related to flood hazards
County of Los Angeles
Floodplain Management
Plan Progress Report from
(2024)
Used to inform Section 6: Hazard Identification and
Risk Assessment and Section 7: Mitigation Strategy
for elements related to flood hazards
County of Los Angeles
Repetitive Loss Area
Analysis Progress Report
(2021)
Used to inform Section 6: Hazard Identification and
Risk Assessment and Section 7: Mitigation Strategy
for elements related to flood hazards
Los Angeles County 2045
Climate Action Plan (2024)
Used to inform Section 6: Hazard Identification and
Risk Assessment, Section 7: Mitigation Strategy, and
Section 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 6: Hazard Identification and
Risk Assessment and Section 7: Mitigation Strategy
for elements related to wildland fire hazards
Our County: Los Angeles
Countywide Sustainability
Plan (2019)
Used to inform Section 6: Hazard Identification and
Risk Assessment, Section 7: Mitigation Strategy, and
Section 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:

Hazard Identification and Risk Assessment.

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Plan, Map, or Report 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:

Hazard Identification and Risk Assessment.

FEMA Flood Insurance
Study, Los Angeles
County, California (2020)
Historical flood information used in Section 6:

Hazard Identification and Risk Assessment.

U.S. Geological Survey
(USGS): Rainfall and
Landslides in Southern
California (2015)
Historical landslide information used in Section 6:

Hazard Identification and Risk Assessment.

Burn Scar Information and
Maps
Historical fire information used in Section 6: Hazard
Identification and Risk Assessment.

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3 Community Profile
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3.1 Los Angeles County Overview
Los Angeles County is the
most populous county in
the United States,
encompassing a diverse
array of communities,
landscapes, and
infrastructure. According to
the most recent census
data, Los Angeles County
has a population of
approximately 10 million
residents of which more than 1 million reside in unincorporated areas. The County’s demographics, geographic features, and economic activities present both unique opportunities and significant challenges for hazard mitigation planning. This updated community profile integrates insights from the 2023 Operational Area Emergency Operations Plan (OAEOP) and reflects changes in population trends, infrastructure development, and climate risks.

The County Operational Area (OA) consists of all political subdivisions within the geographical boundaries of Los Angeles County. It encompasses five supervisorial districts, eight Disaster Management Areas (DMAs), 88 incorporated cities, 80 school districts, and approximately 142 special districts.

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3.2 Geography and Land Use
Spanning over 4,000 square
miles, Los Angeles County
features diverse terrain,
including coastal plains,
valleys, mountains, islands,
and deserts. The County’s
varied geography includes
multiple microclimates that
influence its exposure to
natural hazards, such as
earthquakes, tsunamis, wildfires, floods, and landslides. Urban areas, particularly the City of Los Angeles and its surrounding metropolitan region, are densely populated and heavily developed. In contrast, rural and unincorporated areas often face unique vulnerabilities due to limited infrastructure and resources. Rural areas include the Angeles and Los Padres National Forests, which have small communities, campgrounds, and day use areas. There are also two islands within the County, Santa Catalina and San Clemente. The County also includes a significant amount of Wildland Urban Interface (WUI) areas where residential and commercial development meets underdeveloped wildland with vegetative fuels. Land use within the County is equally diverse, with a mix of residential, commercial, industrial, agricultural, and open spaces.

Recent urban development in densely populated areas has increased impervious surfaces like concrete and asphalt, which retain heat and create urban heat islands (UHI) that are much hotter than nearby rural areas. This phenomenon elevates temperatures, especially in low-income communities lacking green spaces for cooling. Additionally, urbanization affects stormwater management by reducing natural drainage and exacerbating flooding risks in low-lying areas.

These trends underscore the need for sustainable planning strategies, such as promoting green infrastructure, enhancing stormwater systems, and mitigating heat islands through tree planting and reflective materials. The County’s diverse land use 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 planning. The County is home to a diverse population with disparities in income, housing stability, and access to resources. The Los Angeles County Anti-Racism, Diversity, and Inclusion (ARDI) Initiative created a comprehensive Equity Explorer, which is a geospatial tool that explores multiple equity data points across Los Angeles County. The ARDI Equity Explorer includes various layers that visualize social equity, economic opportunity, housing and homelessness, health, justice, built environment, 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
Prevention (CDC) defines social
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:
socioeconomic status, household
characteristics, racial and ethnic minority
status, and housing type/transportation.

Vulnerable populations identified for Los Angeles County that will be considered in the AHMP include:

Figure 3.1 CDC Social Vulnerability Index (CDC 2022)
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• Low-Income Residents:

Individuals living below or near
the poverty line are often
disproportionately affected by
disasters due to limited financial
resources for emergency
preparedness, response, and
recovery.
• People with Access and
Functional Needs (AFN):

Individuals with Access and
Functional needs have increased
challenges in preparedness,
evacuation, sheltering, accessing
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, intellectual disabilities,
developmental disabilities, mental
health-related issues, visual
impairments, hearing
impairments/deaf, mobility
impairments, or chronic
conditions. AFN also include
older adults, infants and children, people living in institutionalized settings, people living below the poverty line or experiencing homelessness, people with limited English proficiency or are non-English speakers, or people who are transportation disadvantaged.
• People Experiencing Homelessness (PEH): With an estimated over 75,000 individuals experiencing homelessness, this population is particularly at risk during extreme weather events and other disasters.
• 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 Disability Statistics in Los Angeles County (OAEOP 2023) County of Los Angeles
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• Limited English Proficiency: Over 40% of residents speak a language other than English at home, highlighting the need for multilingual and culturally 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.

The figure below highlights certain variables in Los Angeles County that may increase vulnerability to emergencies and disasters. To address these vulnerabilities, the County’s mitigation planning includes equitable strategies designed to reduce risk and enhance resilience among these populations. Targeted outreach, improved access to resources, preparedness education events, and collaboration with community organizations are integral to these efforts.

Figure 3.4 Los Angeles County Vulnerability Variables (OAEOP 2023) County of Los Angeles
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The Federal Emergency Management Agency (FEMA) maintains the National Risk Index, a mapping tool that assesses 18 possible hazards a jurisdiction is susceptible to 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 according to the FEMA National Risk Index. According to the National Risk Index, hazards with the highest risk for Los Angeles County include earthquake, wildfires, extreme heat, flooding, high winds, and landslides.

3.4 Economy and Critical Infrastructure
Los Angeles County is a global economic hub, hosting industries such as entertainment, technology, manufacturing, and international trade. The Port of Los Angeles and the Port of Long Beach collectively form one of the world’s busiest trade gateways, underscoring the importance of protecting critical infrastructure from hazards including those exacerbated by climate change. Critical facilities provide services and functions essential to a community, especially during and after a disaster.

Common types of critical facilities include but are not limited to fire stations, police stations, hospitals, schools, and utilities. Critical facilities may also include places that can be used for sheltering, cooling centers, staging purposes, or other large public 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 FEMA National Risk Index (2025)
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economic security. When these are affected by a disaster, the County provides 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 society to function, including but not limited to the following community lifelines:
• Safety and Security: The myriad of local law enforcement, fire and rescue, emergency management, schools, and other government services that maintain public safety and security.
• Communications: The interconnected network of infrastructure owners and operators of communications systems such as internet, telephone, cellular and other communications towers, cable, satellite, and more. • Transportation Networks: The County’s extensive network of roadways, highways, railways, transit systems, and airports is essential for daily operations and disaster response.
• Energy Systems: Power generation facilities, energy distribution networks, and pipelines are vulnerable to multiple types of hazards and threats. • 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.
• Healthcare Facilities: Over 100 hospitals and numerous clinics serve the County, requiring robust contingency plans to maintain operations during disasters.
• Food and Shelter: The vast system of food production (i.e., agriculture), distribution, and retail along with community housing or sheltering.

3.5 Climate and Environmental Conditions
Los Angeles County faces escalating risks from climate change, significantly impacting its environment, economy, and communities. These challenges include rising temperatures, prolonged droughts, more frequent and severe extreme weather events, and their cascading effects. These risks highlight the critical need for adaptive planning to protect vulnerable populations, infrastructure, and natural resources. Key climate- County of Los Angeles
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related considerations referenced in the Los Angeles County Climate Action Plan that will be addressed in this AHMP include, but are not limited to:
• Extreme Weather Events: Extreme temperatures in the Los Angeles region are expected to increase. Both dry and wet extremes are projected to intensify, leading to longer dry periods than historically experienced. These dry periods are expected to be followed by significantly wetter conditions, including atmospheric rivers bringing more intense rainfall. This pattern may result in increased water scarcity, mudslides, and flooding.
• Sea-Level Rise: Coastal communities are at heightened risk of flooding and erosion, threatening homes, businesses, and critical infrastructure. Sea level rise can exacerbate the impacts of high tides, storm surges, and heavy precipitation, and can lead to increased coastal flooding and shoreline erosion. • Increasing Wildfire Risk: Climate change has intensified wildfire seasons, particularly in the County’s mountainous, wildland urban interface (WUI), and new and undeveloped regions. Wildfires are projected to increase in frequency and intensity including in some areas not historically impacted by wildfire.

In response, the County has prioritized integrating climate adaptation strategies into its hazard mitigation planning, as outlined in the Climate Vulnerability Assessment and the OAEOP.

3.6 Regional Collaboration and Planning Efforts
Los Angeles County’s size and complexity necessitates collaboration with numerous jurisdictions, agencies, and community organizations. The County is designated as the Operational Area Coordinator and functions as an intermediate level in the State of California’s Standardized Emergency Management System (SEMS). In accordance with SEMS, the County serves as the communications and coordination link between local governments within Los Angeles County and the state government. Partnerships with academic institutions, non-profits, and private sector stakeholders support data collection, public engagement, and innovative mitigation strategies. Additionally, the County has also adopted Emergency Support Functions (ESFs) as the primary emergency management coordination structure. ESFs group function-specific stakeholders who will coordinate throughout all phases of emergency management, County of Los Angeles
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including function-specific mitigation activities. For more information on regional emergency management collaboration and planning, reference the OAEOP.

3.7 Implications for Hazard Mitigation Planning
Understanding the community is a critical aspect in hazard mitigation planning. This community profile will inform key considerations in subsequent sections of the AHMP including but not limited to the following:
• Targeted Outreach: Include vulnerable populations and the business community in the planning process through equitable public outreach. • Infrastructure Resilience: Prioritize the protection of critical infrastructure, including ports and transportation networks, energy systems, and water and wastewater systems, among others.
• Climate Adaptation: Develop strategies to mitigate the impacts of climate change, focusing on urban heat islands, sea-level rise, and wildfire risks. • Regional Coordination: Strengthen direct collaboration within the OA between the County, local jurisdictions, special districts, unified school districts, the business community and cross-sector non-governmental partners to enhance awareness, preparedness, and response capabilities.
• Transparent & Open Communication: Ensure communications are accessible, 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 climate system over time, including changes in temperature, precipitation, and wind patterns. Climate change had significant impacts on Los Angeles County, affecting various aspects of life, environment, infrastructure, and sustainable development, and presents increasing risks from amplified hazards and changing baselines (e.g., sea level) into the future. The rate of climate change has significantly accelerated over the last three decades and trends continues. This plan addresses the effects of climate change related to disasters within the County and strategies to mitigate risks, focusing on preparedness, resilience and equity.

Climate change contributes to more frequent and intense disasters, such as floods, wildfires, drought and excessive heat. Rising temperatures and changing weather patterns pose health risks, like heat-related illnesses, respiratory issues, and the spread 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 substantial, affecting industries such as agriculture, tourism, and insurance with increasing risks due to accelerating climate changes.

Greenhouse Gas (GHG) emissions are the main driver of climate change, which causes increased frequency, duration, and severity of extreme weather and climate-related disasters. Climate change exacerbates air pollution, leading to poor air quality and health issues. GHG emissions from residential buildings, commercial and institutional facilities, manufacturing industries and construction, energy industries, oil and natural gas systems. transportation, fossil energy, wildfires and other sources contribute to increased particulate matter and other pollutants in the air.

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4.2 Integrating Climate Change into Hazard Profiles
Integrating climate change into
hazard profiles involves assessing the
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-amplified events.

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 temperatures in the Los Angeles region are expected to increase significantly more very hot days and warm nights. In addition to increasing baseline temperatures and extreme heat due to climate change, heat islands exacerbate temperatures and high heat events. As development occurs and darker paved surfaces replace open land and vegetation, these areas become warmer forming an “island” of heat. Los Angeles 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 issues, increased energy demand for cooling, and other strains on infrastructure.

4.2.2 Flooding
Flooding in Los Angeles County occurs due to extreme rainfall events causing flash floods, riverine flooding, and increased surface water. Coastal areas in Los Angeles County are vulnerable to sea- level rise (SLR), which exacerbates coastal hazards like floods, storm surges, and chronic erosion. Other related hazards include flooding near Figure 4.1 Sources of GHG Emissions from within Los Angeles County (LA County 2024; 2045 Climate Action Plan)
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the mouths of streams and channels, landslides, and seawater well intrusion. SLR exacerbates the impacts of high tides, storm surges, and heavy precipitation flooding, and continued SLR will lead to more life safety concerns and increased damage to property and infrastructure.

4.2.3 Drought
Prolonged droughts have become more common, affecting the water supply, agriculture, and ecosystems of Los Angeles County. Dry and wet extremes are projected to increase and are likely to cause drier periods than what the region has historically experienced.

Southern California projected to get drier, while Northern California will increase in temperature. This will result in loss of snowpack within the Sierra Nevada Mountain range, meaning less water for all Californians including farmers, residents, and utilities.

The State Water Resource Control Board proclaimed several water conservation emergency regulations due to severe drought conditions that requires commercial, industrial, and residential conservation efforts. Proclamations include:
• January 4, 2022: State Water Board adopted the prohibited wasteful water uses emergency regulation
• May 24, 2022: the State Water Board adopted the emergency regulation to ban decorative grass watering like non-functional turf irrigation • December 7, 2022: the State Water Board readopted the prohibited wasteful water uses emergency regulation,
• May 26, 2023: the State Water Board readopted the emergency regulation to ban decorative grass watering.

4.2.4 Wildfire
A wildfire is an unplanned and uncontrolled fire in an area of combustible vegetation.

These fires can easily spread beyond the natural areas primarily involving and have a potential to cause damages outside of the perimeter. Wildfire probability depends on local weather conditions, outdoor activities and any preceding conditions (e.g., lots of rain leading to vegetation growth and then drying conditions), and a potential ignition (e.g., lightning strike, arson, debris burning, electrical equipment failure, car tailpipe, etc.). The frequency and intensity of wildfires has increased driven by higher County of Los Angeles
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temperatures, lower precipitation, lower relative humidity, and prolonged droughts.

These events have caused loss of life, destroy and/or damage to property, infrastructure, the environment and pose greater risks due to historical development patterns. The timeline of major wildfire events and acreage burned in Los Angeles 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 faces increasing risks from excessive heat, wildfires, droughts, floods, and sea-level rise, all of which threaten communities, infrastructure, and natural resources.

To address many of these challenges, the County has developed comprehensive climate plans and strategies that integrate climate adaptation, sustainable land use, emergency preparedness, and environmental conservation. By enforcing building codes, investing in green infrastructure, and strengthening community preparedness, 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
• Los Angeles County 2045 Climate Action Plan (2045 CAP): Establishes aggressive targets to reduce greenhouse gas emissions and achieve carbon neutrality by 2045.
• Water Conservation & Drought Resilience Measures: Implements mandatory water restrictions, promotes rainwater harvesting, and expands groundwater recharge and water recycling projects.
• Wildfire Mitigation & Vegetation Management Programs: Enforces Wildland Urban Interface (WUI) codes, increases forest management techniques, aligned with Traditional Ecological Knowledge (TEK) principles and practices of our native indigenous communities, and strengthens fire-resistant building and landscape requirements.

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• Green Infrastructure & Urban Cooling Initiatives: Expands tree planting aligned with TEK principles and practices, investigates removing hard (paved) surfaces, and planting groundcover, utilizes and promotes public cooling centers and home heat preparedness, and encourages the use of reflective “cool” roofing and surfaces to mitigate the urban heat island (UHI) effect. • Heat Action Plan: Develops strategies to reduce the adverse health impacts of excessive heat through public shade structures, cooling centers, building codes, and increased public awareness campaigns for all susceptible to extreme heat.

These strategic actions reflect Los Angeles County’s commitment to tackling climate change. By integrating proactive policies, indigenous-informed practices, communitydriven solutions, and resilient infrastructure, Los Angeles County, is not only mitigating current risks but also preparing for a future where communities can thrive in an everchanging dynamic environment.

4.4 Climate Change Conclusion
Through proactive policies and community engagement, Los Angeles County strives to navigate the complexities of a changing climate and safeguard its people, environment, infrastructure and economies. This approach helps minimize the risks and impacts associated with climate-related hazards. Addressing climate change in hazard mitigation help enhance safer, healthier, and more sustainable communities.

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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 needs (AFN). Historically, individuals with disabilities (i.e. including but not limited to, youth, those economically depressed, pregnant, etc.), chronic health conditions, language barriers, or transportation disadvantages have been underrepresented in emergency planning. As evidenced by the best practices for stakeholder inclusion and further supported by national preparedness frameworks, integrating AFN considerations leads to plans that are more inclusive and effective. By proactively engaging AFN populations and support agencies in every phase, from preparedness through recovery, a hazard mitigation plan can reduce losses, improve evacuation and sheltering outcomes, and build trust between emergency management agencies and the communities they serve.

5.2 Inclusion of AFN and Vulnerable Populations in Planning A major component of effective mitigation planning is a “whole community” approach.

Incorporating AFN voices into the planning process is crucial because these stakeholders offer real-world insights into the challenges they face during emergencies. Key steps to this process include, but are not limited to:
• Stakeholder Engagement: Ensure that representatives from disability advocacy groups, community-based organizations, and service providers (such as local health departments and transportation agencies) are engaged early in the planning process. Their firsthand experiences help identify practical barriers that might otherwise be overlooked.
• Public Participation: Incorporating public stakeholders through meetings, surveys, and other outreach to capture the diverse needs of AFN populations.

This input is vital to overcoming historical marginalization and ensuring that mitigation actions are relevant and equitable to the entire population. • 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 of existing plans, ensuring that AFN issues are fully integrated from the outset.

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5.2.1 Integrating AFN into the Overall AHMP
Integrating AFN considerations is not a stand-alone task; it must be interlaced throughout the entire hazard mitigation planning process. This includes:
• Risk Assessments: Incorporate AFN data into all risk assessments to ensure that the specific vulnerabilities of these populations are reflected in hazard maps and vulnerability index data.
• Mitigation Strategy Development: Ensure that every mitigation action is examined for its impact on AFN populations. For example, when planning for flood control or wildfire prevention projects, review how these projects can be improved to meet the needs of people with access and functional needs. • Plan Review and Update: Ensure 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 • Funding and Resource Allocation: Clearly identify funding streams and resource commitments for AFN-specific projects. This could involve targeted grants from federal programs (e.g., Hazard Mitigation Assistance), state funding dedicated to accessible infrastructure improvements, and local resources such as the Productivity Investment Fund that can be accessed to improve the effectiveness and efficiency of County operations.

5.3 Assessment of AFN Needs
Understanding the specific needs of AFN populations requires both quantitative and qualitative approaches:
• Data Collection and Risk Assessment: Use existing resources, community surveys, outreach and risk assessments to help identify the number and types of individuals with AFN at the local community level. Evaluate the regional geographic distribution, vulnerabilities, and specific requirements before and after emergencies.

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• Frameworks for Analysis: Adopt structured methodologies such as C‐MIST (Communication, Maintaining Health, Independence, Support, Safety, and Transportation) to assess/ document AFN requirements.
• C-MIST Explanation
o Communication: Individuals with hearing, vision, cognitive, or speech limitations may require alternative communication methods to receive or express information during emergencies.
o Medical / Health Needs: People with complex medical conditions rely on medications, medical equipment, or specialized care to maintain their health and prevent complications.
o Independence: Those who use mobility devices, assistive technology, or service animals need uninterrupted access to maintain their independence and daily functions.
o Supervision & Safety: Some individuals require continuous support for safety, comfort, or emotional well-being, including those with memory issues, psychiatric conditions, or intellectual disabilities. o Transportation: Individuals without personal transportation or with mobility limitations need accessible and reliable options, especially in emergencies and evacuations.
• Integrating Vulnerability Assessments: Leverage tools from local climate vulnerability assessments and hazard mitigation plan reviews to identify areas where AFN populations overlap with high‐risk zones (e.g., flood plains, County of Los Angeles
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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:
• Formal Partnerships: Establish relationships and partnerships with agencies such as public health departments, social services, transportation authorities, community-based organizations, and disability advocacy organizations. These partnerships ensure that there is clear, ongoing communication and that roles and responsibilities are delineated before, during, and after disasters. • Joint Training and Exercises: Conduct regular joint meetings, and exercises 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. • Outreach and Information Dissemination: Ensure that all information, both pre-incident preparedness messages, response measures and post-incident recovery plans are accessible to all audiences. This includes using multiple languages, various communication formats (e.g., large-print, audio, signlanguage, and digital formats), and culturally appropriate messaging to reach all segments of the community.

5.5 AFN Conclusion
A hazard mitigation plan builds a foundation for a resilient, inclusive community. By ensuring that AFN and other vulnerable populations are included in every phase of planning, from initial stakeholder engagement to the development of tailored mitigation actions and coordinated response strategies, communities can minimize disaster impacts and foster long-term resilience. Drawing on best practices from national frameworks and local planning guides, and by implementing ADA-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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6 Hazard Identification and
Risk Assessment
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6.1 Hazard Identification Overview
The hazard identification and risk assessment process provide a foundation for Los Angeles County’s hazard mitigation planning efforts by identifying, profiling, and assessing the risks associated with natural, technological, and human-caused hazards.

This section builds on the framework established in the 2020 Hazard Mitigation Plan, incorporating insights from the 2023 Operational Area Emergency Operations Plan (OAEOP), the 2024 Los Angeles Threat and Hazard Identification and Risk Assessment (THIRA), the Los Angeles County Climate Vulnerability Assessment, the State of California Hazard Mitigation Plan (SHMP), and the Federal Emergency Management Agency (FEMA) National Risk Index.

Based on these sources hazards were included and addressed in the 2025 AHMP according to their frequency, severity and impact to Los Angeles County, see below Table 6-1. Hazards that did not meet the threshold of moderate risk will not be prioritized within the plan. Additionally, three new natural hazards (Extreme Heat, Drought, and Severe Wind/Tornado) and four human-caused hazards (Mass Violence, Cyber Incidents, Transportation Incidents, and Public Health Emergencies) 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 frequency, severity, and impact to Los Angeles County.

Wildfire Hazard is included in the plan due to its high frequency, severity, and impact to Los Angeles County.

Heat Wave Hazard is included in the plan due to its high frequency, severity, and impact to Los Angeles County.

Tornado Hazard is included in the plan due to its high frequency, severity, and impact to Los Angeles County. Tornado is
incorporated with the Severe Wind/ Tornado hazard profile.

Land Movement Hazard is included in the plan due to its high frequency, severity, and impact to Los Angeles County.

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Hazard Comment
Lightning Hazard is included in the plan due to its high frequency, severity, and impact to Los Angeles County. Lightening is incorporated with the Wildfire and Flooding hazard profiles.

Flooding Hazard is included in the plan due to its frequency, severity, and impact to Los Angeles County. The Flooding hazard profile incorporates both Riverine and Coastal Flooding.

Drought Hazard is included in the plan due to its frequency, severity, and impact to Los Angeles County.

Strong Wind Hazard is included in the plan due to its frequency, severity, and impact to Los Angeles County. Strong Wind is incorporated with the Severe Wind and Tornado hazard profile.

Tsunami Hazard is included in the plan due to its frequency, severity, and impact to Los Angeles County.

Winter Weather Hazard is omitted from the plan due to its minimal frequency, severity, and impact to Los Angeles County.

Hail Hazard is omitted from the plan due to its minimal frequency, severity, and impact to Los Angeles County.

Avalanche Hazard is omitted from the plan due to its minimal frequency, severity, and impact to Los Angeles County.

Cold Wave Hazard is omitted from the plan due to its lack of frequency, severity, and impact to Los Angeles County.

Hurricane Hazard is omitted from the plan due to its lack of frequency, severity, and impact to Los Angeles County.

Ice Storm Hazard is omitted from the plan due to its lack of frequency, severity, and impact to Los Angeles County.

Volcanic Activity Hazard is omitted from the plan due to its lack of frequency, severity, and impact to Los Angeles County.

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Los Angeles County faces a wide range of hazards due to its geographic diversity, population density, and economic significance. The following hazards were identified and prioritized from the previously mentioned sources based on historical occurrences, potential impacts, and future risks:

1. Wildfire

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
Among these hazards, six were identified to be potentially exacerbated by climate change including wildfire, extreme heat, drought, flooding, land movement, and severe wind and tornadoes. Additional human-caused hazards were included based on the 2024 THIRA including mass violence, cybersecurity incidents, transportation incidents, and public health emergencies. The results of the public Personal Disaster Impact Survey validated that these hazards are of significant concern to county residents. A risk assessment table comparing hazards to critical infrastructure is in Appendix C.

Table 6-2 Changes in Development and Vulnerability
Hazard Change (Increase/ Decrease) Reason
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) Reason
retrofitting increases overall
exposure.

Wildfire
(Lightning)
Increase in Vulnerability Urban expansion into WildlandUrban Interface (WUI) areas has increased the number of homes at
risk. Post 2020 development in
high fire severity zones has
continued, though defensible
space regulations and new firesafe planning are improving resilience for new builds.

Extreme Heat Increase in Vulnerability Population density, urban 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.

However, climate-driven
precipitation variability and
wildfires continue to destabilize
slopes in developed areas.

Flooding
(Lightning)
Increase in Vulnerability New impervious surfaces from
development increase stormwater
runoff. Older flood control
infrastructure is strained under
heavier, more frequent rain events.

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Hazard Change (Increase/ Decrease) Reason
Drought Increase in Vulnerability Continued population growth and water demand in arid and semiarid 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
intense wind events, including
tornadoes. As urban development
expands, tree canopies and
overhead utilities in densely
developed areas continue to
contribute to cascading hazards. In
response, efforts are underway to
underground utility lines in highrisk areas.

Tsunami Stable Revised tsunami inundation maps
have refined the at-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 been constructed in recent years,
downstream development
continues to increase population
and critical infrastructure exposure
within inundation zones.

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6.2 Wildfire

6.2.1 Nature
Wildfires are fast-moving, uncontrolled
fires that consume vegetation and rapidly
spread, often threatening lives, structures,
and infrastructure. These fires can be
ignited by natural causes, such as
lightning, or human activities, including
unattended campfires, downed power
lines, and arson. The increasing frequency,
duration, and intensity of wildfires in Los
Angeles County are possibly linked to the
changing climate, with hotter
temperatures, prolonged droughts, and
reduced humidity levels making the
region highly susceptible to fires.

Factors Influencing Wildfire Behavior
• Topography: Fires spread
more rapidly on steep slopes
and are often driven by the
Santa Ana winds.
• Fuel Load: Dense, dry
vegetation and high tree mortality increase fire intensity. • Weather Conditions: High temperatures, strong winds, and low humidity elevate fire risk, with the changing climate contributing to a lengthened fire season.

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Wildfires also create secondary hazards such as poor air quality, landslides, flooding, and debris flows—especially in areas with recent burn scars where vegetation loss increases soil instability.

6.2.2 Location
Los Angeles County is one of the most wildfire-prone regions in the United States.

Based on the Department of Forestry and Fire Protection (CAL FIRE) Fire Hazard Severity Zone (FHSZ) maps, significant wildfire risk exists in the Santa Monica Mountains, San Gabriel Mountains, Palos Verdes Hills, and Puente 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.

Los Angeles County has three primary wildfire management zones:
• Federal Responsibility Areas (FRAs): Lands administered or controlled by the federal government where federal agencies have administrative and protection responsibility for wildfires.
• State Responsibility Areas (SRAs): Wildland areas where CAL FIRE is responsible for suppression efforts.
• Local Responsibility Areas (LRAs): Developed regions where local agencies, such as Los Angeles County Fire Department (LACoFD), provide fire protection.

For a better visual representation of this Wildfire Hazard within the LA County planning area, please reference Appendix A. Included in Appendix A are several Fire Hazard Severity Zone maps for reference.

6.2.3 Extent
According to CAL FIRE’s Fire Hazard Severity Zone (FHSZ) maps, Los Angeles County contains:
• 386.06 square miles (8.11%) classified as Very High Fire Hazard Severity Zone (FHSZ) in Local Responsibility Areas, LRAs.
• 625.01 square miles (13.13%) classified as Very High (FHSZ) in State Responsibility Areas, SRAs.

Wildfires pose a significant threat not only through the immediate damage they cause to lives, property, and natural resources, but also through the secondary hazards that continue after the flames are extinguished.

In the aftermath of a fire, communities often face increased risks of flash floods, debris flows, and degraded air quality. These post-fire impacts can compound the initial destruction, placing additional strain on infrastructure, health systems, and recovery efforts.

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6.2.4 History
Los Angeles County has experienced numerous devastating wildfires in recent decades, including:
• Canyon Fire (1968) – Burned 22,000 acres, destroyed 147 homes, and led to mass evacuations.
• Old Topanga Fire (1993) – Consumed 16,516 acres, destroying 388 structures and causing three fatalities.
• Sayre Fire (2008) – Destroyed 489 structures, including over 600 mobile homes.
• Station Fire (2009) – The largest fire in Los Angeles County history, burning 160,577 acres, destroying 209 structures, and causing two firefighter fatalities.
• Woolsey Fire (2018) – Burned 96,949 acres, destroyed 1,643 structures, and resulted in three fatalities.
• Bobcat Fire (2020) – Scorched 115,796 acres, destroying 171 structures and damaging numerous infrastructures in the Angeles National Forest. • Palisades Fire (2025) – Resulted in significant destruction and loss of life, burning 23,707 acres, destroyed approximately 6,833 structures, and causing 12 civilian fatalities.
• Eaton Fire (2025) – Resulted in significant destruction and loss of life, burning 14,021 acres, destroying approximately 9,418 structures, and causing 17 civilian fatalities.

These fires highlight the increasing frequency and intensity of wildfires, emphasizing the urgent need for stronger mitigation and preparedness efforts.

The Los Angeles County area has experienced federally declared wildfires and are shown in the table below. There have been no state proclamations for wildfires in the last five years.

Federally Declared Wildfire/Fire Management Assistance Declaration in Los Angeles County from 1/1/2020 to 3/28/2025
Date Incident Name No. Category
1/8/2025 California Wildfires and
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 California Wildfires 4569 Federal Declaration 9/13/2020 California Bobcat Fire 5374 Fire Management Assistance Declaration County of Los Angeles
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6.2.5 Probability
With several guaranteed wildfires each year, the probability of wildfire ignition in Los Angeles County is gradually increasing, driven largely by climate change. There is a 100% chance of a fire occurring each year within the geographic planning area.

Historically, wildfires occurred between June and November, but recent years have shown a year-round fire season due to hotter, drier conditions and more intense weather variability.

Longer dry periods, reduced humidity, and increased temperatures, coupled with historic drought and vegetation die-off, have created critically dry fuel beds. These events make even small ignition sources capable of generating major wildfires.

Santa Ana winds continue to serve as a major accelerant, contributing to rapid fire spread and severe fire behavior. When combined with urban encroachment into fireprone areas, these conditions elevate both the frequency and destructiveness of wildfires.

Projections from the 2024 THIRA and the LA County Climate Vulnerability Assessment confirm that wildfire probability will continue to rise unless significant fuel reduction, land use planning, and climate adaptation strategies are implemented across all jurisdictions.

The 2024 THIRA estimates that:
• Over 1.2 million residents live in high-risk wildfire zones. • Communities near the Wildland-Urban Interface (WUI) are at the greatest risk, especially those with limited evacuation routes, and the Access and Functional Needs community.
• Vulnerable populations, including seniors, low-income households, and people with disabilities, face heightened challenges during evacuations.

6.2.6 Vulnerability
Los Angeles County faces high wildfire vulnerability due to its extensive WildlandUrban Interface (WUI), with over 1.2 million residents that live in Very High Fire Hazard Severity Zones (FHSZs). These communities are particularly susceptible because many homes lack defensible space, fire-resistant construction, or adequate emergency access.

Vulnerable populations including (but not limited to): seniors, individuals with disabilities, low-income households, and those dependent on electrical medical equipment, face significant evacuation and health risks during wildfire events, 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 fire authority responsibility. These are some of the most vulnerable communities due to terrain, vegetation, and constrained emergency access.

Critical infrastructure is also at risk, with wildfire exposure threatening fire stations, law enforcement facilities, hospitals, utilities, transportation corridors, and emergency communication systems. Disruption to these essential services during wildfire 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:
• Very High LRA: 120
• High SRA: 8
• Very High SRA: 76
With the continued expansion of developments into fire-prone areas has significantly increased wildfire risk. Many homes in the WUI lack proper defensible space and fireresistant building materials, making them particularly vulnerable. Additionally, limited evacuation routes in some WUI communities create challenges for emergency response and evacuations. Stricter zoning laws, building regulations, and vegetation management policies are the best practices to reduce risk.

SUPERVISORIAL DISTRICT BREAKDOWN
Supervisorial District Population in High-Risk
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%
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Department/
Agency
Very High FHSZ
(LRA)
High FHSZ (SRA) Very High FHSZ
(SRA)
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
Office of
Education 3 0 3
Other County
Offices 0 0 0
Parks &
Recreation 13 1 12
Public Health 52 4 41
Public Works 0 0 0
Sheriff’s
Department
3 1 3
Wildfires threaten essential infrastructure, including:
• Transportation: Damage to roads and bridges affects evacuation and emergency response.
• Utilities: Power lines, gas pipelines, and water infrastructure, including dams, are vulnerable to fire damage.
• Emergency Services: Public safety and healthcare facilities near wildfireprone areas face operational disruptions. • Public Services: Parks, libraries, schools, and other public areas could be lost or damaged.

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New emerging patterns suggest that climate change may be influencing wildfire risks in Los Angeles County through:
• Extending fire seasons: Historically, peak fire season occurred from June to November, but fires are now starting and burning year-round. • Increasing fuel dryness: Higher temperatures and prolonged droughts reduce vegetation moisture levels, making fires more intense. • Raising fire frequency: Hotter, drier conditions contribute to more frequent ignitions, particularly in WUI areas.

Extent of Exposure
• Total Area Exposed: 243.72 sq mi
• 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%)
For a better visual representation of this Wildfire Hazard within the LA County planning area, please reference Appendix A for several Fire Hazard Severity Zone maps.

6.2.7 Impacts
Impacts for past fires vary depending on scope and severity, including the January 2025 fires, including the Palisades and Eaton Fires, resulted in widespread destruction across Los Angeles County, burning over 37,000 acres and destroying more than 16,000 structures combined, with nearly 30 civilian fatalities. These events caused cascading impacts such as prolonged power outages, degraded water pressure affecting firefighting and residential supply, and overwhelmed emergency services.

Transportation routes and communications infrastructure were disrupted.

Communities, especially in the Wildland-Urban Interface (WUI), experienced major economic losses due to the destruction of homes, businesses, and public facilities.

Post-fire hazards like debris flows and landslides further compounded recovery challenges, with water infrastructure contamination and sedimentation requiring emergency remediation. The scope and severity of these fires underscore the increasing vulnerability of critical infrastructure and the urgent need for enhanced mitigation strategies across high-risk zones.

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Problem Statement
Many hillside communities within LRA Very High FHSZ zones face critical access and water supply issues during fires. These areas often include aging structures and narrow roads, complicating firefighting and evacuation. Investments in defensible space, local code enforcement, and community wildfire protection planning are vital to saving lives and minimizing losses.

6.2.8 Mitigation and Preparedness
Los Angeles County is implementing a multi-agency approach to mitigate wildfire risks.

Key strategies include:
• Community Wildfire Protection Plans (CWPPs): Strengthening fire prevention measures in high-risk areas.
• Community Preparedness: Educating residents on wildfire readiness through outreach campaigns, emergency alert systems, and neighborhood preparedness programs.
• Defensible Space Requirements: Enforcing brush clearance around structures.
• Enhanced Building Codes: Promoting fire-resistant materials for new developments.
• Vegetation Management: Reducing fuel loads through prescribed burns and hazardous tree removal.
• Evacuation Planning: Improving coordination between OEM, LASD, LACoFD, and other jurisdictions to ensure clear evacuation policies and procedures.

Additional details on the County’s proactive and ongoing efforts to reduce wildfire risk, including long-term planning, infrastructure hardening, and community-based initiatives, is located in the dedicated section titled “Mitigation Strategies.”

6.2.9 Summary
Wildfires remain one of the most significant hazards in Los Angeles County, posing risks to life, property, and critical infrastructure. The expansion of development into WUI areas, increasing fire severity due to climate change, and ongoing challenges with evacuation and mitigation require proactive, coordinated efforts across agencies.

Strengthening fire prevention policies, improving emergency response coordination, and integrating climate adaptation measures are essential to enhancing wildfire resilience for Los Angeles County.

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6.3 Earthquake

6.3.1 Nature
Earthquakes occur due to the sudden release
of energy in the Earth's crust, generating
seismic waves that cause ground shaking.

These events, often triggered by movement
along fault lines, vary in intensity depending
on factors such as magnitude, depth, and
proximity to populated areas. In addition to
the initial shaking, secondary hazards such as
surface faulting, liquefaction, landslides,
tsunamis, and aftershocks can worsen the
damage. Los Angeles County, located in a
highly active seismic region, faces significant
risks from these natural events, necessitating
extensive mitigation efforts and
preparedness planning.
• The most common effects of
earthquakes include violent shaking,
structural damage, and disruptions to infrastructure.
• Secondary effects can include, but are not limited to, utilities outages, traffic congestion and transportation systems being impassable, and an increase of fire risks, from broken gas and water lines.

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• Earthquakes occur with little to no warning, making preparedness essential for minimizing loss of life and property.

6.3.2 Location
Los Angeles County is one of the most seismically active regions in the United States, with multiple active fault systems capable of generating destructive earthquakes.

Major faults include:
• San Andreas Fault – Capable of M 8.0+
• Newport-Inglewood Fault – M 7.4
• Malibu Coast Fault System – M 6.7
• San Fernando Fault – M 6.6
• Santa Monica Fault – M 7.0
• Whittier Fault – M 7.2
• Sierra Madre Fault – M 6.0-7.0
For a better visual representation of this Earthquake Hazard within LA County planning area, please reference Appendix A for earthquake fault maps.

6.3.3 Extent
According to US Geological Survey, there are two types of earthquake measurements, 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.

Earthquake impact is based on magnitude scale is as follows:
• Great—Mw > 8,
• Major—Mw = 7.0 – 7.9
• Strong—Mw = 6.0 – 6.9
• Moderate—Mw = 5.0 – 5.9
• Light—Mw = 4.0 – 4.9
• Minor—Mw = 3.0 – 3.9
• Micro—Mw < 3
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Modified Mercalli Intensity Scale is from I to XII, which refers I, as not felt and XII as extreme.

Figure 6.3.1 Modified Mercalli Intensity Scale
Over 75% of unincorporated Los Angeles County is at risk for severe to extreme shaking in a future earthquake.

The region's dense urban environment, combined with aging infrastructure, increases the likelihood of extensive damage and prolonged recovery times.

Faults running beneath critical infrastructure corridors, including freeways and power grids, pose a significant threat to public safety and economic stability of the planning area.

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6.3.4 History
Los Angeles County has a long history of destructive earthquakes, with some of the earliest recorded events dating back to the early 19th century. The San Juan Capistrano Earthquake of 1812 (M 7.5) was among the first to be documented, causing the collapse of Mission San Juan Capistrano and resulting in 40 fatalities. Over the years, the county has experienced numerous significant quakes, including the devastating 1857 Fort Tejon Earthquake (M 7.9), the 1971 San Fernando Earthquake (M 6.6), and the infamous 1994 Northridge Earthquake (M 6.7), which caused billions in damages and led to widespread infrastructure failures. There have been no federal declarations or state proclamations for earthquakes in the last five years.

Major Earthquakes in Los Angeles County (1812 – Present) Date Magnitude Name / Location Notable Impact
December 8,
1812

7.5 San Juan
Capistrano
Earthquake
Destroyed Mission San Juan
Capistrano, killed 40 people.

December 21,
1812

7.1 West Ventura
Earthquake
Caused significant shaking in
Southern California.

January 9, 1857 7.9 Fort Tejon
Earthquake
Largest earthquake on the San
Andreas Fault; ruptured 225
miles.

July 21, 1952 7.5 Kern County
Earthquake
Strong shaking felt in Los
Angeles; major damage to
Bakersfield.

February 9, 1971 6.6
San Fernando
Earthquake
65 deaths, $553 million in
damages, collapse of Veterans
Hospital.

October 1, 1987 5.9
Whittier Narrows
Earthquake
8 deaths, 200 injuries, $358
million in damages.

February 28,
1990

5.7 Upland Earthquake 30 injuries, $12.7 million in
damages.

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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.

The San Andreas Fault remains the greatest seismic hazard, with a 59% chance of an M

6.7+ event in the next 30 years.

Future Earthquake Occurrence
The U.S. Geological Survey (USGS) estimates the following probabilities for a major earthquake in Los Angeles County in the next 30 years:
• 60% chance of an M 6.7+ earthquake
• 46% chance of an M 7.0+ earthquake
• 31% chance of an M 7.5+ earthquake

6.3.6 Vulnerability
The county’s vulnerability to earthquakes extends beyond physical infrastructure, affecting its residents and essential services. Older buildings, particularly unreinforced masonry and soft-story structures, are at high risk of collapse, posing significant June 28, 1991 5.6
Sierra Madre
Earthquake
1 death, 100+ injuries, $40
million in damages.

January 17, 1994 6.7 Northridge
Earthquake
57 deaths, 8,700 injuries, $40
billion in damages, freeways
collapsed.

July 29, 2008 5.5
Chino Hills
Earthquake
8 injuries, minor structural
damage.

March 28, 2014 5.1
La Habra
Earthquake
Few injuries, $10 million in
damages.

July 6, 2019 7.1 Ridgecrest
Earthquake
Widespread damage in
Southern California,
infrastructure impacts.

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dangers to residents and businesses. Seismic retrofitting, early warning systems, and stricter building codes have improved resilience, but vulnerabilities remain in older structures and critical infrastructure.

Critical Infrastructure at Risk
• Highways, bridges, and transportation routes: A major earthquake could severely disrupt mobility, shipment of goods and services while also delaying emergency response and evacuations. Major highways such as, but not limited to the I-5, I-10, US-101, CA-60, CA-14, I-405, I-710, and I-105 could be impacted. • Energy grids and water system: Disruptions could leave millions without power and clean water.
• Hospitals and emergency services: 325 hospitals and 1,299 fire stations in the Los Angeles County could suffer functional impairments. • Unreinforced masonry and soft-story buildings: Many older structures are highly susceptible to collapse during strong ground shaking.

County Specific Critical Facilities Affected:
• Fire Department: 314 facilities (93.18%)
• Public Works: 201 facilities (87.39%)
• Health Services: 56 facilities (85.71%)
• Public Health: 37 facilities (92.50%)
• Libraries: 78 branches (89.66%)
• Parks: 179 (97.79%)
• Education: 70 (85.37%)
Los Angeles County lies at the intersection of multiple major fault lines, including the San Andreas Fault. According to the hazard matrix, the risk of violent ground shaking is prevalent countywide, particularly in urban centers and regions with critical infrastructure. The potential consequences of violent seismic shaking include widespread structural damage, disruption of services, economic losses, and human casualties.

Populations at Risk
• The THIRA estimates over 2 million residents could be significantly impacted in a major seismic event, particularly those in high-risk seismic zones.

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• People Experiencing Homelessness (PEH) populations: 75,000+ unhoused individuals in Los Angeles County live in areas at risk of violent shaking. • Low-income and individuals with access and functional needs (AFN): For more details on impacted population please see Section 5.

Extent of Exposure
• Total Area Exposed: 3,041.91 sq mi
• Supervisorial Districts (SD) Impacted:
o SD5: 1,950.78 sq mi (69.50%)
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 its location along multiple active fault systems, including the San Andreas, NewportInglewood, and Whittier faults. Historic earthquakes such as the 1971 San Fernando (M6.6) and 1994 Northridge (M6.7) events caused catastrophic losses. The San Fernando earthquake resulted in 65 deaths, the collapse of hospital structures, and over $550 million in damages, while the Northridge earthquake caused 57 deaths, more than 8,700 injuries, and an estimated $40 billion in economic losses, including 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 population density, aging infrastructure, and increasing development in seismically 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 earthquake could displace up to 2.2 million people, injure or kill thousands, and result in over $200 billion in combined economic losses, including $113 billion in property damage and $68 billion in business interruptions.

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The County’s critical systems; power, water, transportation, healthcare, and communications, are especially vulnerable. A major earthquake could impair up to 325 hospitals and 1,299 fire stations and disrupt critical infrastructure for millions.

Populations with heightened vulnerability include the 75,000+ people experiencing homelessness, those with access and functional needs, and residents of older, unreinforced masonry and soft-story structures.

Without sufficient mitigation, a future earthquake could result in cascading failures across multiple sectors and prolong the County’s recovery for years. These risks highlight the urgency for continued investment in seismic retrofitting, stricter enforcement of building codes, expanding statewide early warning systems, and equitable preparedness programs targeting at-risk vulnerable populations. • Casualties and injuries: Depending on the time of day and location, thousands could be injured or killed in a severe earthquake.
• Economic disruption: A significant earthquake could halt business operations, damage supply chains, and force thousands into unemployment. • Housing displacement: An estimated 2.2 million residents could be displaced, with tens of thousands requiring emergency sheltering.

Economic Impact
A major earthquake in Los Angeles County could result in over $200 billion in economic losses, with a total of $118 trillion-dollar exposure. Losses can include:
• $68 billion in business interruptions
• $51 billion in lost economic activity
• $113 billion in property damages
Problem Statement
The pervasive exposure of Los Angeles County to violent earthquake shaking presents a systemic threat to public safety, economic stability, and essential services. Nearly all major departments and infrastructure elements are located within high-shaking hazard zones. The extensive reach across all five Supervisorial Districts (SD) amplifies the challenge, highlighting the urgent need for retrofitting, public education, preparedness programs, and resilient design policies. Failure to address this hazard 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 building codes, enhancing emergency preparedness, and retrofitting vulnerable structures.

Key efforts to mitigate earthquake risks include:
• Strengthening building codes and enforcing retrofitting laws • Upgrading critical infrastructure
• Expanding public education and early warning systems
• Enhancing emergency response planning
By proactively implementing these measures, Los Angeles County aims to reduce casualties, infrastructure damage, and economic losses in future seismic events.

Seismic Retrofitting Programs
• Soft story retrofit program: Mandates seismic upgrades for older apartment buildings.
• Non-ductile concrete building retrofits: Strengthens older commercial and residential structures.
• Hospitals and emergency facilities retrofitting: Ensures critical services remain operational post-earthquake.

Policy and Regulatory Measures
• Assembly Bill (AB) 1857: Strengthens building standards for multi-story structures.
• AB 2681: Requires cities and counties to inventory vulnerable buildings. • Updated California Building Code (CBC): Enforces stricter seismic design criteria for new construction.
• Public Education: Teaching to Drop, Cover and Hold On; the household preparedness checklist, educate residents on emergency response, retrofitting, and disaster preparedness.
• Early Warning/ ShakeAlert System: Provides real-time earthquake early warnings to residents via mobile alerts and public messaging.
• Public earthquake drills: Annual Great California ShakeOut encourages preparedness.

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6.3.9 Summary
Los Angeles County remains at high risk for devastating earthquakes, with scientific projections indicating a strong likelihood of a significant seismic event in the coming decades. The region has experienced numerous historic earthquakes, and the potential for future large-scale disasters remains ever-present. While advances in engineering, emergency preparedness, and mitigation efforts have improved resilience, challenges persist, particularly regarding aging infrastructure and vulnerable communities. Continued investments in retrofitting, public education, and early warning systems will be critical in minimizing casualties, economic losses, and recovery challenges in future earthquakes.

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6.4 Extreme Heat

6.4.1 Nature
Extreme heat refers to prolonged periods of
high temperatures, often accompanied by
high humidity, posing significant health risks
such as heat exhaustion and heat stroke. The
urban heat island (UHI) effect, prevalent in
densely built areas like Los Angeles County,
intensifies these conditions by absorbing
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 to health issues,
increase energy demand, and strain on
infrastructure.

6.4.2 Location
Los Angeles County is particularly susceptible to extreme heat due to its diverse geography and urban density. All of Los Angeles County may experience extreme heat, nonetheless inland regions, including the valleys and high desert areas experience County of Los Angeles
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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 retention, contributing to elevated temperatures and increased UHI effect in the county.

6.4.3 Extent
The severity of heat events in Los Angeles County has been increasing. Projections indicate a significant rise in the frequency and intensity of heat waves, with inland areas potentially experiencing temperatures exceeding 110°F. The urban heat island effect can cause urban areas to be several degrees warmer than their rural counterparts, exacerbating the impact of heat waves. The chart below shows the levels of heat wave impacts used to measure heatwave severity. HeatRisk, an experimental measure developed by the NWS in collaboration with the CDC, classifies heat events by their impact on human health. It ranges from Green (0) which is little or no risk to Magenta (4), which means extreme heat with no overnight relief.

Category Figure 6.4.1 Risk of Heat-Related Impacts
Green
0 Little to no risk from expected heat.

Yellow
1 Minor - This level of heat affects primarily those individuals extremely sensitive to heat, especially when outdoors without effective cooling and/or adequate hydration.

Orange
2 Moderate - This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration.

Impacts possible in some health systems and in heat-sensitive industries.

Red
3 Major - This level of heat affects anyone without effective cooling and/or adequate hydration. Impacts likely in some health systems, heat-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 hydration. Impacts likely in most health systems, heat-sensitive industries and infrastructure.

National Weather Service (NWS), 2024
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August, being the hottest month of the year that the planning area experiences the Figure 6.4.2 below shows, the average high temperature for August 2024 in Los Angeles County. As shown, the temperature varies by location but remains higher than average monthly temperature.

Figure 6.4.2, Mean Max Temperature for August 2024, National Weather Service

6.4.4 History
Because of the changing climate conditions and the geographical location, Los Angeles County has been experiencing extreme heat waves in the past years. It has a history of extreme heat events, with temperatures frequently reaching 100 degrees or more, especially during the summer months. In some cases, these extreme heat events are record-breaking heat waves surpassing their all-time highs.

Extreme Heat events include:
• August 2020: A severe heatwave led to widespread power outages, affecting nearly 500,000 residents.

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• September 2020: The San Fernando Valley recorded a record high temperature of 121°F.
• August 2022: A record-breaking heatwave in late summer exceeded 100°F • September 2024: A severe September heatwave pushed temperatures 10- 20°F above normal, hitting 109°F in Long Beach
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 proclamations for extreme heat in the last five years. Even though there were no declared extreme heat emergencies, the county has issued several heat alerts and taken measures to protect residents from the impacts of heat waves during these periods.

6.4.5 Probability
Extreme heat events are an annual occurrence in Los Angeles County, though severity of such events vary per year based on other conditions, such as El Niño. Climate models project a substantial increase in the likelihood of extreme heat events in Los Angeles County. By mid-century, the county could experience more than five major heat waves annually, with some models suggesting up to tenfold increases in frequency. This heightened probability necessitates proactive mitigation and adaptation strategies.

Figure 6.4.3, Average Temperature 1900-2025, NOAA, NCEI, 2025.

6.4.6 Vulnerability
Extreme heat poses a significant and growing threat to Los Angeles County, where rising temperatures, urban heat islands, and widespread social vulnerability intersect.

Those most at risk include the elderly, low-income households lacking air conditioning, County of Los Angeles
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people experiencing homelessness (PEH), individuals with access and functional needs (AFN), and the County’s large population of outdoor and non-air-conditioned indoor workers. Infrastructure is also strained; electricity demand spikes during heatwaves, often overwhelming the power grid and triggering outages. Water systems experience increased demand and evaporation losses, while roadways and rail lines are subject to buckling or operational delays. In recent years, Los Angeles County has experienced severe consequences from prolonged heat events, reinforcing the urgent need for heat resilience strategies targeting both people and critical services.

Los Angeles County–Specific Impacts and Data
• 491,600 residents experienced power outages during the August 2020 heatwave.
• 96% of the County’s 1,000 miles of high-voltage transmission lines are exposed to moderate to high extreme heat risk.
• 1.7 million residents are considered highly vulnerable due to age, income, disability, or chronic health conditions.
• Over 300,000 outdoor workers are at elevated risk for heat-related illness and injury.
• Thousands of heat-related emergency visits occurred during multi-day heat events in 2020 and 2022; especially in neighborhoods with limited shade and high surface temperatures.
• 50+ cooling centers have been activated across the County during recent heatwaves to support at-risk populations.
• High heat contributes to worsened air quality, increased wildfire smoke exposure, and economic losses due to infrastructure damage, productivity decline, and rising healthcare costs.

6.4.7 Impacts
Los Angeles County has faced significant and growing impacts from extreme heatwaves over the past two decades. In August 2020, a prolonged heatwave caused rolling blackouts affecting nearly 500,000 customers, overwhelmed the state’s electrical grid, and forced the activation of emergency conservation protocols. That same summer, the San Fernando Valley hit 121°F, leading to widespread strain on County of Los Angeles
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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 the region led to localized transformer failures, asphalt buckling, and strain on water delivery systems due to elevated demand. During these events, outdoor workers, the elderly, and low-income residents without access to cooling systems were among the most affected. Economic activity was disrupted, with reports of business closures, service delays, and increased healthcare costs. In 2024, Long Beach reached a record 109°F, causing a spike in electricity demand and triggering emergency energy alerts across Southern California. Heat-related deaths and hospitalizations have also trended upward, particularly 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 forecasting and monitoring, education and awareness, and heat wave response.

To address extreme heat, Los Angeles County has implemented several measures:
• Cooling Centers: Establishment of air-conditioned public spaces where residents can seek relief during heatwaves. These centers are facilities such as libraries, community centers, and senior centers. Residents can locate the nearest cooling center using resources provided by the county. Additional resources can be found at https://ready.lacounty.gov/heat/ • Urban Greening Initiatives: Programs aimed at increasing green spaces, planting trees, and creating parks to provide shade and reduce ambient temperatures. These efforts help mitigate the urban heat island effect. • Public Awareness Campaigns: Educational initiatives to inform residents about heat risks, prevention strategies, and resources available during extreme heat events. These campaigns emphasize the importance of hydration, recognizing heat-related illness symptoms, and utilizing cooling centers. • Building Codes and Regulations: Incorporation of heat-mitigating designs and materials in new constructions and retrofits, such as cool roofs and reflective County of Los Angeles
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pavements, to reduce heat absorption. These measures aim to lower indoor temperatures and decrease reliance on air conditioning.

These strategies are designed to reduce heat exposure, protect vulnerable populations, and enhance community resilience against extreme heat events.

6.4.9 Summary
Extreme heat poses a growing threat to Los Angeles County, with increasing frequency and intensity of heat waves exacerbated by urban heat island (UHI) effects.

Understanding these impacts of extreme heat and taking appropriate precautions, residents of Los Angeles County can protect themselves and their communities from this growing climate hazard. The county has undertaken various mitigation efforts, including the establishment of cooling centers, urban greening projects, public education campaigns, and the implementation of heat-conscious building practices.

Ongoing adaptation and proactive planning are essential to safeguard public health, infrastructure, and the environment from the adverse effects of extreme heat.

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6.5 Drought

6.5.1 Nature
Drought is a prolonged period of belowaverage precipitation that leads to water shortages, impacting agriculture, ecosystems,
and urban water supplies. Unlike other natural
disasters, drought develops gradually, making
it difficult to predict and mitigate. In Los
Angeles County, droughts are a recurring issue
due to the region’s arid climate and
dependence on imported water supplies.

Drought severity is determined by its duration,
intensity, geographic extent, and water
demand. Climate change is exacerbating these
factors, leading to hotter temperatures,
reduced precipitation, and increased
evaporation rates. Wildfires are also projected
to increase in frequency and intensity during
drought season.

There are four common classifications of drought:
• Meteorological Drought: A prolonged period of below-normal precipitation.

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• Hydrological Drought: A reduction in surface and groundwater levels due to prolonged precipitation deficits.
• Agricultural Drought: A lack of soil moisture that affects crop growth and livestock sustainability.
• Socioeconomic Drought: When water shortages impact drinking water supplies, sanitation, public services, and economic activities.

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 snowpack and the Colorado River, reduced availability of these sources significantly increases vulnerability.

6.5.3 Extent
Drought is a recurring natural hazard that can severely impact agriculture, water supply, ecosystems, and communities. To monitor and communicate drought conditions across the United States, the National Drought Mitigation Center (NDMC), in partnership with the U.S. Department of Agriculture (USDA) and the National Oceanic and Atmospheric Administration (NOAA), produces weekly U.S. Drought Monitor maps. These maps categorize drought conditions into five levels based on intensity, duration, and impact on various sectors, including agriculture, water resources, and public health.

Each drought category reflects a different level of severity, from short-term dry conditions that may slow crop growth, to long-term, widespread water shortages that require emergency response. These classifications help decision-makers, farmers, and 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
• Exceptional and widespread crop/pasture losses
• Critical shortages of water in reservoirs, streams, and wells
• Water emergencies and possible mandatory rationing
• Severe impacts on ecosystems and wildlife habitats
D3 EXTREME

DROUGHT
• Major agricultural losses and pasture failure
• Widespread water shortages
• Water use restrictions likely enforced
• Increased risk of wildfires and heat-related stress
D2 SEVERE

DROUGHT
• Crop and pasture losses becoming likely
• Water shortages becoming common
• Local governments may implement water restrictions
• Hydropower generation and irrigation potentially
impacted
D1 MODERATE

DROUGHT
• Noticeable damage to crops and pastures
• Water levels in streams and reservoirs begin to decline • Voluntary water-use restrictions may be requested
• Some stress on fish and wildlife populations
D0 ABNORMALLY
DRY
• Early signs of drought, with short-term dryness slowing planting and crop growth
• If improving lingering water deficits as area recovers from drought
• Pastures or vegetation may show signs of delayed
recovery
Figure 6.5.1 Drought Categories and Associated Impacts
These classifications not only 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 local, state, and federal levels.

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6.5.4 History
Los Angeles County has experienced multiple significant droughts, with some lasting several years. There have been no federal declarations or state proclamations for drought in the last five years.

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 – The most severe drought in modern history, resulting in groundwater depletion and mandatory conservation measures.

6. 2020-2022 – California experienced a significant drought, with Los Angeles County experiencing "abnormally dry" conditions.

7. 2024-2025 – Los Angeles County is continuing to experience abnormally dry conditions, with lower average rainfalls and arid conditions.

The chart above, the Palmer Drought Severity Index, shows 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 December 20, 2011, until March 14, 2019. The State and the County passed several resolutions and regulations at different times to mitigate drought impacts like water Figure 6.5.3, NOAA Drought Severity Index, 2024
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conservation regulations. There were no federally declared drought disasters in the area in the past five years in the planning area.

6.5.5 Probability
Climate scientists predict that Los Angeles County and the rest of Southern California will get drier, while Northern California will get hotter. Rising temperatures contribute to higher evaporation rates and declining snowpack in the Sierra Nevada, a critical source of water for Southern California. The frequency of extreme droughts is expected to increase, reducing available water resources and heightening competition between urban, agricultural, and environmental needs. Long-term droughts have a 100% of occurring every ten-years, with potential for longer and more destructive drought events due to climate change.

6.5.6 Vulnerability
Los Angeles County’s 10 million residents face growing vulnerabilities during prolonged droughts, with over 75% of community water systems exhibiting at least one drought-related risk, such as reliance on a single source or aging infrastructure. The 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. All residents, and visitors of Los Angeles County are affected by water shortages during a prolonged drought conditions.

Vulnerabilities include:
• Low-income households, often lacking water-efficient appliances and cooling systems.
• Agricultural industry with over 140,000 acres of irrigated farmland in the County is at risk of reduced water allocation and drying pastures for livestock. • Wildland-urban interface (WUI) communities, where over 1 million residents face heightened wildfire risk due to dry vegetation and limited firefighting water supply.
• 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-reaching, cross-sector impacts of drought on the County’s economy, environment, and most at-risk communities.

6.5.7 Impacts
Over the past five years, Los Angeles County has experienced intensifying drought conditions marked by rising temperatures, reduced snowpack, and persistent water shortages. By 2022, 75% of the County’s community water systems showed at least one drought vulnerability, including reliance on a single water source or aging infrastructure. Public health impacts have also emerged, with 1,113 cases of Valley fever reported in 2020, linked to dry soil and dust exposure. Hydropower reductions during drought periods increased reliance on natural gas, contributing to elevated energy costs for residents. These compounding impacts have strained water supply, health systems, and infrastructure, reinforcing drought as a major and growing hazard for Los Angeles County.

6.5.8 Mitigation and Preparedness
To combat increasing drought risks, Los Angeles County has implemented water conservation policies, infrastructure investments, and emergency response measures.

Key strategies include:

Water Management and Conservation
• Expanding water recycling and desalination programs to reduce reliance on imported water.
• Implementing drought-tolerant landscaping initiatives to lower residential and commercial water use.
• Enforcing water efficiency regulations for new developments and upgrading older properties with water-saving strategies.

Infrastructure Improvements
• Enhancing groundwater recharge projects to increase local water storage. • Upgrading stormwater capture systems to maximize water retention during rainy seasons.
• Developing new water storage facilities to provide additional supply resilience.

Community Preparedness and Public Awareness
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• Launching county-wide conservation campaigns to encourage sustainable water use.
• Increasing financial incentives for water-efficient appliances and irrigation systems. • 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 and severe droughts, placing greater strain on water supply systems, public health, and agriculture. By implementing proactive water management strategies, investing in infrastructure resilience, and promoting community awareness, the County can mitigate the long-term impacts of drought and ensure sustainable water resources for future generations.

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6.6 Flooding

6.6.1 Nature
Flooding is a persistent and increasingly severe
hazard in Los Angeles County, driven by heavy
rainfall, storm surge, stormwater drainage, and rising
sea levels. The county’s complex hydrology, which
includes rivers, creeks, and an extensive urban flood
control system, is highly susceptible to overflow
events when precipitation exceeds drainage capacity.

The effects of climate change are exacerbating flood
risks by intensifying storms, altering precipitation
patterns, and increasing sea levels, leading to greater coastal inundation and inland flash floods.

Unlike other regions that experience seasonal
flooding due to snowmelt, flooding in Los Angeles
County primarily occurs during winter storms and
atmospheric river events, which bring intense rainfall
and lightning over short periods.
• The region’s high degree of urbanization contributes to flash flooding, as paved surfaces prevent natural absorption of water, leading to rapid runoff and street flooding.

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• Burn scars from recent wildfires further compound flood risks by reducing vegetation cover, destabilizing hillsides, and increasing the likelihood of land movement.

Flooding also creates secondary hazards, including erosion, infrastructure damage, water contamination, and transportation disruptions. Stormwater runoff can overwhelm wastewater treatment facilities, leading to hazardous spills. Landslides and mudflows in post-wildfire areas pose additional risks to homes, roads, and critical infrastructure.

These compounding threats highlight the urgent need for comprehensive flood mitigation efforts to protect communities, infrastructure, and the environment.

6.6.2 Location
Flood hazards are geographically widespread, with more than 240 square miles of land located within the 100- and 500-year floodplains. Historically significant events, such as the 1938 and 1969 floods, as well as more recent storms in 2023 and 2024, have caused substantial damage to infrastructure, triggered evacuations, and challenged long-term recovery efforts. Socially vulnerable populations, including older adults, individuals with access and functional needs, and low-income households, face disproportionate impacts due to limited financial resources, inadequate insurance coverage, and reduced access to services. The County’s flood control system includes concrete river channels, levees, storm drains, debris basins and reservoirs; has helped mitigate some flood risks but remains vulnerable to high-intensity storms that exceed design capacities.

Major Flood-Prone Areas:
• Los Angeles River, San Gabriel River, and Santa Clara River: These major waterways are prone to overflow during extreme storm events, particularly during El Niño years.
• Ballona Creek and Malibu Creek: These urban watersheds experience rapid runoff and flash flooding, especially in developed areas.
• Foothills, Valleys, and Recent Burn Scar Areas: Post-wildfire regions face heightened risk of flash floods and debris flows following storms. • Antelope Valley: In desert regions, stormwater pools into temporary lakes, causing flooded roadways and infrastructure damage.

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• Coastal Communities: Rising sea levels and storm surges threaten beachfront properties, harbors, and businesses.

Urban areas are particularly vulnerable due to impervious surfaces and outdated drainage systems. During intense storms, neighborhoods in Downtown Los Angeles, South LA, and the San Fernando Valley frequently experience street flooding and traffic disruptions, demonstrating the limitations of existing infrastructure in handling modern storm events.

For a better visual representation of this Flooding Hazard within the LA County planning area, please reference Appendix A for flood and inundation maps.

6.6.3 Extent
Los Angeles County faces a significant and evolving flood risk, with impacts ranging from localized urban inundation to widespread riverine flooding and destructive debris flows. Although the County has invested heavily in flood control infrastructure; including an extensive network of dams and debris basins; these systems are increasingly strained and cannot fully eliminate the threat. A growing number of residents are exposed to dangerous flooding each year, a situation made worse by the limitations of aging infrastructure and the complexities of urban hydrology. Intense rainfall events, especially those associated with atmospheric rivers, are occurring more frequently and with greater severity, often overwhelming drainage systems and resulting in severe flooding of streets and neighborhoods. Compounding this risk are burn scars from recent wildfires, which heighten the likelihood of mudslides and debris flows that threaten both life and property. As climate patterns shift and extreme weather events become more common, the flood vulnerability of Los Angeles County continues to deepen across its diverse geography.

Flood severity is typically measured using the 100-year and 500-year flood recurrence intervals, which indicate a 1% and 0.2% annual probability of flooding, respectively.

These designations guide floodplain management and mitigation efforts.

Key Flood Hazard Statistics in Los Angeles County:
• 243.32 square miles (5.11%) of land have a 0.2% annual flood probability. • 4.19 square miles (0.09%) have a 1% annual flood probability.

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Key Flood Hazard Statistics for Unincorporated Los Angeles County:
• 64.77 square miles (2.13%) have a 0.2% flood probability. • 1.23 square miles (0.04%) have a 1% flood probability.

As climate change accelerates sea-level rise and extreme rainfall events, these floodprone areas may expand, affecting more residents, infrastructure, and businesses.

FLOOD IMPACT ON LAND AREA
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
Los Angeles County has experienced numerous severe flood events, many of which have caused catastrophic damage to infrastructure, property, and human life. Over the decades, climate variability, rapid urbanization, and an aging flood control system have led to repeated flooding disasters. There have been no federal declarations or state proclamations for earthquakes in the last five years.

Below are some of the most significant historical and recent flood events affecting the region.

Notable Flood and Lightning Events in Los Angeles County:
• 1938 Los Angeles Floods: One of the deadliest floods in county history, caused by weeks of torrential rainfall, resulting in over 100 deaths, the destruction of thousands of homes, and widespread infrastructure damage, particularly to bridges and roadways.
• 1969 Winter Storms: Heavy rains led to massive debris flows in the San Gabriel Mountains, severe urban flooding across Los Angeles, and multiple dam breaches, prompting major evacuations.
• 1992-1993 El Niño Floods: A series of storms triggered landslides, flash flooding, and major coastal erosion, with significant damage to Pacific Coast Highway and residential areas.
• 2017 Winter Storms (DR-4305): Record-breaking rainfall led to significant urban flooding, road closures, and mudslides, with severe impacts across multiple communities.

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• October 2021: Los Angeles County experienced a rare and intense thunderstorm with a significant amount of lightning.
• September 2022 Hurricane Kay: A pacific hurricane that caused significant rainfall along with risk of mudflows, coastal flooding, and coastal erosion. • January 2023 Atmospheric River Event (DR-4683): Heavy rainfall overwhelmed storm drains, causing significant flooding in Hollywood, Baldwin Hills, and low-lying inland areas, leading to evacuations and infrastructure damage. • February 2023 Los Angeles Floods (DR-4699): A series of intense storms caused widespread flash flooding, freeway closures, and landslides, demonstrating the increasing vulnerability of the county's urban areas to extreme precipitation events. • August 2023 Tropical Storm Hilary (DR-4750): Several locations in the mountains of Southern California received over 10 inches of rainfall which set daily and/or monthly rainfall records, in many locations in Southern California, including within Los Angeles County. It also created significant threat of flash and riverine flooding prompted the evacuation of numerous vulnerable communities near burn scars in the region.
• December 2023 Pacific Storm: Storm surges and extreme coastal flooding led to significant erosion along the coastline, particularly impacting Marina del Rey, Long Beach, and Venice Beach.
• February - March 2024 Atmospheric River Storm (DR-4769): One of the most intense rainfall events in recent history, resulting in severe flash floods, mudslides, and power outages, with many homes and businesses sustaining flood damage.

6.6.5 Probability
Flood recurrence in Los Angeles County is influenced by both natural climate variability and the increasing effects of climate change. Historically, severe flooding is most likely during strong El Niño events, which occur approximately every 2 to 7 years and can persist for several months to multiple years. These events bring elevated precipitation levels and increase the likelihood of both inland and coastal flooding.

As climate change accelerates, the frequency and intensity of flood-generating events are expected to increase, altering traditional recurrence intervals and expanding the areas at risk. There is a 95% chance of a flooding event occurring each year withing Los Angeles County.

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Key climate-related drivers include:
• Sea-Level Rise: Projected to rise by 6 inches to over 2 feet by 2050, increasing the risk of tidal and storm surge flooding in coastal communities. • Atmospheric River Events: According to the 2024 THIRA, these events are becoming more frequent and intense, leading to elevated flash flood and debris flow risks.
• El Niño Cycles: Still expected every 2 to 7 years, but with increased variability and storm intensity that can overwhelm local drainage and flood control systems.

These evolving conditions challenge existing floodplain maps and design assumptions, highlighting the need for adaptive planning, updated risk models, and continued investment in resilient infrastructure and flood mitigation strategies.

6.6.6 Vulnerability
Los Angeles County faces widespread and layered vulnerabilities to flooding, shaped by a combination of environmental exposure and complex social factors. Physical vulnerability is pronounced in areas located within FEMA-designated Special Flood Hazard Areas (SFHAs), post-wildfire burn scars, and low-lying urban drainage basins that are prone to flooding. However, the degree of risk is significantly heightened for certain populations who may lack the resources or capacity to prepare for, respond to, and recover from flood events. Socially vulnerable groups, including older adults, individuals with disabilities or access and functional needs (AFN), mobile home residents, people experiencing homelessness, and low-income households; are more likely to reside in structurally vulnerable housing.

According to the 2021 Los Angeles County Comprehensive Floodplain Management Plan, more than a quarter of residents living within the 100-year floodplain earn less than $20,000 annually, underscoring the disproportionate economic burden faced by those least able to absorb the costs of recovery. Climate vulnerability data further demonstrates that marginalized communities in flood-exposed areas face elevated risks due to flooding events. The vulnerability landscape is further complicated by a shortage of affordable flood-resilient structures, and an increasing number of residents living in areas newly exposed due to climate-driven changes in precipitation and runoff patterns.

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6.6.7 Impacts
Flooding in Los Angeles County leads to a broad range of direct and cascading impacts on people, infrastructure, environment, and the economy. The County’s extensive network of critical facilities, including hospitals, fire stations, wastewater treatment plants, schools, and power substations. These areas face recurring exposure within both 100- and 500-year floodplains. Damage to these facilities not only compromises their physical integrity but also threatens their functionality during emergency response operations.

Flooding often disrupts lifeline services such as electricity, potable water, sanitation, and transportation, with rural and unincorporated areas facing the greatest challenges to rapid restoration. Mobile homes, frequently concentrated in low-lying or underdrained neighborhoods, are especially susceptible to flood damage due to construction limitations and inadequate protective measures. Previous flood events have resulted in significant debris flows, road closures, train stoppages, and damage to public and private structures.

Primary Vulnerabilities & Impacts:
• Over 1,470 structures are estimated to be damaged in a 100-year flood event, with total damages exceeding $769.7 million in property losses in unincorporated Los Angeles County.
• Additionally, more than 180 critical facilities are exposed in the 500-year floodplain, while 70 are within the 100-year floodplain, including transportation assets, utilities, emergency services, and hazardous materials facilities. • A 100-year flood event could displace over a thousand people with many requiring sheltering, support and recovery efforts.
• Approximately 19,563 tons of building-related debris could be generated by a 100- year flood event, with clean-up requiring more than 780 truckloads, posing logistical, environmental, and public health challenges. • 28.6% of households in the 100-year floodplain are economically disadvantaged, earning under $20,000 per year, limiting their ability to evacuate, recover, or pay for mitigation improvements.
• A large share of flood-prone properties are either uninsured or underinsured. The average flood insurance claim payout is $7,298, which is only about 1% of the 2019 County of Los Angeles
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Charts Source: LA County Public Works; 2021 County Comprehensive Flood Plan average replacement cost of structures in the floodplain—indicating significant gaps in financial resilience.
• Wildfire burn scars and post-fire hydrophobic soils significantly increase flood and debris flow risks, particularly in foothill and canyon communities. This hazard continues to grow in severity with climate-driven fire seasons.

6.6.8 Mitigation and Preparedness
Los Angeles County’s flood mitigation strategy reduces hazard exposure, enhances community resilience, and supports long-term climate adaptation. Grounded in FEMA’s National Mitigation Framework, CalOES planning guidance, and local policy, the County implements both structural and non-structural measures to address current and future flood risks. Core actions include regular maintenance and targeted upgrades to Estimated Damage to Critical Facilities in Unincorporated Areas from 100-Year Flood Sector Number of Facilities
Affected
Average % of Total Value
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 Value
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
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stormwater infrastructure, restoration of floodplains, and integration of flood hazard data into land use planning. The County also prioritizes the protection of critical facilities and vulnerable housing through site retrofits, property acquisition, and elevation programs. Public outreach is conducted through a bilingual, ADA-accessible Program for Public Information, which promotes flood safety awareness, emergency preparedness, and participation in the National Flood Insurance Program (NFIP).

To ensure that mitigation is both data-driven and community-centered, the County utilizes climate projections and FEMA’s HAZUS modeling to inform investments, while coordinating with regional partners to align local actions with broader watershed strategies. Key components of the approach include:
• Upgrading culverts, debris basins, and drainage systems to manage increased runoff
• Promoting low-impact development (LID) and incorporating green infrastructure in urban design
• Updating ordinances and the General Plan to discourage development in high-risk areas
• 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 state standards but advances flood risk reduction in a way that safeguards people, property, and natural systems for the future.

6.6.9 Summary
Flooding is one of the most persistent and complex natural hazards in Los Angeles County, intensified by climate change, urbanization, and aging infrastructure. The Los Angeles County region experiences a range of flood types, including stormwater runoff, flash flooding, coastal inundation, and post-wildfire debris flows. These events are most common during winter storms and atmospheric river systems. High-density development, extensive paved surfaces, and fire-damaged hillsides contribute to rapid runoff and increased overall flood vulnerability. Areas along (but not limited to) the Los Angeles, San Gabriel, and Santa Clara Rivers, as well as coastal communities and foothill regions, are particularly at risk.

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Los Angeles County’s mitigation strategy is proactive and multifaceted. It includes infrastructure upgrades, nature-based solutions, land use policy updates, and public education. Core priorities focus on protecting critical facilities, reducing exposure in high-risk housing, and promoting community resilience. Planning efforts are supported by FEMA’s HAZUS risk modeling and local climate projections. Despite progress, more than 750,000 residents remain at risk from major flood events, reinforcing the need for continued investment in comprehensive, flood risk reduction across the county.

6.6.10 National Flood Insurance Program (NFIP) Repetitive Loss (RL)
According to the Los Angeles County Public Works, there are 55 Repetitive Loss (RL) properties in 28 RL areas of Unincorporated Los Angeles County as of 2025, and 8 Severe Repetitive Loss Properties (SRLP). A Repetitive Loss (RL) property is any insurable building for which two or more claims of more than $1,000 were paid by the National 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 available during the drafting of this plan, but is being finalized and will be included in subsequent hazard mitigation efforts. Data from 2011 showed that 24 RL properties were located in the SFHA. At the time, the Los Angeles County Public Works stated, “the majority of the repetitive losses are associated with localized urban drainage flood problems, even for properties within a FEMA-designated flood zone.” The Los Angeles County Public Works oversees RL mitigation projects.

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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-related deterioration, inadequate
spillway capacity, structural damage from
seismic activity or flooding, and poor
maintenance. The catastrophic release of water
from a dam failure has the potential to cause
human casualties, significant economic loss, and
environmental destruction. This type of disaster
is particularly dangerous because it can occur
suddenly, leaving little time for evacuation or
emergency response efforts.

The magnitude of flooding from dam failure
often exceeds the capacity of downstream
channels, causing rapid inundation of
surrounding areas. This flooding can lead to
extensive property damage, erosion,
infrastructure destruction, and contamination of
water supplies. Additionally, secondary hazards
such as landslides and debris flows can be
triggered, compounding the disaster’s impact.

The structural stress on dams may rise as dams
age, and climate variability increases the frequency of extreme precipitation 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.

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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 (PW). In 2017, the California Legislature mandated that all state-jurisdictional dams (excluding those classified as Low Hazard) develop dam breach inundation maps and Emergency Action Plans (EAPs) approved by DSOD and Cal OES.

Many of these dams are located near highly populated areas, increasing the potential for human and economic impacts during a failure event. Seventy (70) dams are classified as High or Extremely High hazard potential dams, meaning their failure could result in significant loss of life and widespread property damage.

The Whittier Narrows Dam, reclassified as the U.S. Army Corps of Engineers’ (USACE) highest-priority dam safety concern, poses one of the greatest risks due to its potential to flood highly populated areas from Pico Rivera to Long Beach. USACE has 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 planning area, please 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-946, 2013) categorizes dam hazards into four classifications:
• Low Hazard: Minimal damage expected, no loss of life. • Significant Hazard: Potential for property damage and economic disruption. • High Hazard: Likely to result in loss of life and significant damage to critical infrastructure.
• Extremely High Hazard (DSOD Classification): Could cause large-scale fatalities and inundate areas with over 1,000 residents.

Given the population density of Los Angeles County, a dam failure classified as High or Extremely High Hazard would likely cause substantial human casualties, displace entire communities, and inflict severe economic and environmental damage. Table 6-3 and 6-4 below shows a list of dams and debris basins owned by PW along with their hazard classifications. Potential mitigation actions described in this AHMP are only applicable 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.

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Table 6-3: Los Angeles County PW Dam Hazard Status
Dam Name Hazard Status Location
Big Dalton Extremely High Glendora, CA
Big Santa Anita Extremely High Monrovia, CA
Big Tujunga No. 1 Extremely High Tujunga, CA
Cogswell Extremely High Azusa, CA
Devils Gate Extremely High LA Canada Flintridge, CA
Live Oak Extremely High La Verne, CA
Morris Extremely High Azusa, CA
Pacoima Extremely High Pacoima, CA
Puddingstone Extremely High San Dimas, CA
Puddingstone Diversion High La Verne, CA
San Dimas Extremely High La Verne, CA
San Gabriel No. 1 Extremely High Azusa, CA
Sawpit Extremely High Monrovia, CA
Sierra Madre High Sierra Madre, CA
Thompson Creek Extremely High Claremont, CA
Table 6-4: Los Angeles County PW Debris Basin Hazard Status Debris Basin Name Hazard Status Location
Bailey Debris Basin High Sierra Madre, CA
Big Dalton Debris Basin High Glendora, CA
Blanchard Debris Basin High Tujunga, CA
Brand Debris Basin High Glendale, CA
Eaton Wash Debris Basin Extremely High Pasadena, CA
La Tuna Debris Basin Extremely High Sun Valley, CA
Laguna Regulating Basin Significant Alhambra, CA
Little Dalton Debris Basin Extremely High Glendora, CA
Lower Sunset Debris Basin High Burbank, CA
Morgan Debris Basin High Glendora, CA
Rubio Debris Basin High Altadena, CA
Santa Anita Debris Basin Low Arcadia, CA
Sawpit Debris Basin Extremely High Monrovia, CA
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Debris Basin Name Hazard Status Location
Schoolhouse Debris Basin High Los Angeles, CA
Sierra Madre Villa Extremely High Sierra Madre, CA
Stevenson Ranch High Stevenson Ranch, CA
Stough Debris Basin Extremely High Burbank, CA
Wilson Debris Basin High Los Angeles, CA

6.7.4 History
Los Angeles County has experienced one of the deadliest dam failures in U.S. history:
• St. Francis Dam Failure (March 12-13, 1928):
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
While no major dam failures have occurred in recent decades, concerns over aging dam infrastructure, seismic risks, and increasing climate variability have raised alarms about future risks. Studies indicate that many California dams, including those in Los Angeles County, require structural updates to withstand modern hydrological conditions and potential seismic activity. There have been no federal declarations or state proclamations for dam failure in the last five years.

6.7.5 Dam Coordination
Los Angeles County Public Works coordinates with local, state, and federal agencies to mitigate flood risk hazards to downstream communities from its dams. At the local level, PW works with cities and public agencies during development of Emergency Action Plans (EAP). This provides local stakeholders with the opportunity to review the EAP, provide feedback, and confirm responsibilities and roles during an EAP activation. At request from local jurisdictions, PW may provide tours of its dam facilities, where information on dam safety and the potential hazards associated with dam failures are shared.

At the state level, PW works with the DSOD to meet compliance with state dam safety standards and flood management at all of PW’s dams. This includes annual dam County of Los Angeles
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inspections, review, approval, and oversight of dam construction projects, review of dam safety monitoring, and oversight of other dam safety regulatory activities. PW also coordinates with various state agencies, including DSOD, Cal OES, and Caltrans during development of EAPs.

At the federal level, PW works with the Federal Energy Regulatory Commission (FERC) to meet compliance with state dam federal standards and flood management at PW’s San Gabriel Dam, which is under FERC jurisdiction. This includes annual dam inspections, review, approval, and oversight of dam construction projects, review of dam safety monitoring, EAP coordination, and oversight of other dam safety regulatory 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 provides critical information to relevant local, state, and federal stakeholders to address hazard mitigation related to dam safety. This includes:
• Emergency Action Plans (EAPs): EAPs outline the roles, responsibilities, and procedures to follow in the event of a dam emergency. The EAPs include inundation maps, which show areas that would be affected by a dam failure, helping to identify populations at risk. These plans are shared with stakeholders to ensure a coordinated response. Due to the sensitive nature of information contained within the EAPs, they are confidential and not released to the general public.
• 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 impacts on critical infrastructure facilities such as hospitals, schools, and 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-jurisdictional dams, with approximately 70 classified as High or Extremely High Hazard by the California Division of Safety of Dams (DSOD), meaning their failure could result in loss of life and significant property damage.

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Although comprehensive failure probabilities are not published for each dam, FEMA and DSOD guidance suggest that the general annual probability of failure for High Hazard dams nationwide ranges from 0.01% to 0.1% (or 1 in 10,000 to 1 in 1,000) depending on maintenance, age, seismic vulnerability, and other site-specific factors.

Applying this range to Los Angeles County:
• The aggregate annual probability of a significant dam failure event in the county—across one or more of the 70 high-risk dams—is estimated at between

0.1% and 0.5% annually, factoring cumulative exposure and different hazard classifications. (Such as earthquake or flood related)
• Climate change, aging infrastructure, and seismic activity in Los Angeles County increase systemic risk across multiple structures simultaneously.

In summary, while the individual likelihood of failure for any one dam is very low, the overall countywide probability of at least one major dam failure event is low but still warrants continued vigilance, maintenance, and emergency planning.

6.7.7 Vulnerability
A catastrophic dam failure in Los Angeles County could have severe consequences for hundreds of thousands of residents. The densely populated nature of the county, combined with the location of several large dams near residential and commercial areas, increases the potential for widespread displacement, loss of life, and economic damage. The 2024 THIRA identifies multiple high-risk zones where dam failure could result in extensive flooding and mass evacuations.
• High-risk dams, among others, pose a significant threat to densely populated communities. A breach in any of these dams could inundate entire neighborhoods, affecting more than 500,000 residents in low-lying areas and floodplains.
• Socially vulnerable populations, including elderly individuals, the AFN community, people experiencing homelessness, low-income communities, and non-English-speaking residents face heightened risks during evacuations and recovery due to limited mobility, financial constraints, and access to resources. • Educational and healthcare institutions are at risk, with several schools, hospitals, and long-term care facilities located in flood-prone areas. A major dam failure could result in school closures, displacement of students, and disruption of healthcare services.

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• Evacuation and emergency sheltering demands would be substantial, requiring the rapid mobilization of resources to support displaced residents. Temporary shelters, emergency medical services, and logistical support would need to be activated to accommodate evacuees.

Los Angeles County relies heavily on dams and reservoirs for water storage, flood control, and supply regulation. Catastrophic dam failure poses an acute threat to life and property, especially in low-lying, highly populated downstream areas.

Extent of Exposure
• Total Area Exposed: 490.64 sq mi
• 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%)
• 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 failure, while rare, can have catastrophic consequences in densely populated downstream areas. With significant portions of critical infrastructure exposed— particularly in SD1 and SD5—planning for emergency evacuations, early warning systems, infrastructure hardening, and downstream development regulation is critical 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 would result in catastrophic consequences for downstream communities, with the greatest vulnerabilities concentrated in densely populated urban areas. Rapid and massive flooding would likely inundate residential neighborhoods, commercial districts, and industrial zones within minutes to hours, depending on proximity and topography. Critical infrastructure—including hospitals, fire and police stations, schools, and major transportation corridors—would be severely impacted, disrupting emergency services and evacuation routes. Thousands of people, including vulnerable populations such as those with Access and Functional Needs (AFN), elderly residents, and low-income households, would face immediate life-threatening conditions, displacement, and limited access to medical care or shelter. Economic losses would be compounded by damage to utilities, including power substations and water systems, potentially leaving large swaths of the region without essential services. The sheer scale of devastation from a dam failure, especially at facilities such as Whittier Narrows or Castaic Dam, underscores the critical importance of continued risk reduction, early warning systems, and dam rehabilitation 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:
• Incorporate more current information as it becomes available. • Assess any new or updated EAPs for dams owned by Los Angeles County. • Identify and review more current structural or condition assessment data to inform future risk assessments.
• 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 consequences for life, property, and critical infrastructure, particularly in the densely populated downstream areas. The sudden release of impounded water from a High or Extremely High Hazard dam could inundate neighborhoods within minutes, allowing little to no time for evacuation. More than 500,000 residents live within identified dam inundation zones, many of whom are in socially vulnerable populations—including County of Los Angeles
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individuals with limited mobility, low-income households, and people experiencing 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 significant risk. Hospitals, fire stations, law enforcement facilities, emergency operations centers, schools, and wastewater treatment plants located in downstream zones may be damaged or rendered inoperable, severely disrupting emergency response and life-sustaining services. Major transportation routes such as interstates, rail lines, and arterial roads could be submerged or washed out, impeding rescue and recovery efforts. Additionally, power substations, water distribution networks, and telecommunications infrastructure could suffer cascading failures, contributing to widespread outages and prolonged recovery periods.

The economic consequences of dam failure would be immense. Beyond property damage, business operations in inundated areas would halt, leading to loss of employment, tax revenue, and economic activity. Industrial zones (especially those near major flood control reservoirs or channels) could potentially release hazardous materials if overwhelmed, posing secondary environmental and public health hazards.

Debris accumulation, sedimentation, and contamination could severely impact ecosystems, water quality, and flood control infrastructure downstream, complicating both emergency cleanup and long-term environmental recovery.

Given the scale of potential impacts, dam failure is considered a stable low-probability but high-consequence hazard in Los Angeles County, requiring continued investment in structural mitigation, emergency preparedness, and public awareness to reduce the severity of its effects.

6.7.10 High Hazard Potential Dams Goals
Goal 1: Enhance resilience across dam/debris basin infrastructure, including highhazard potential dams, and other critical facilities within dam inundation zones.

Goal 2: Encourage structural reinforcement or retrofits for aging and vulnerable dams.

Goal 3: 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:
• Structural Reinforcements: Upgrading spillways, strengthening earthen dams, and implementing seismic retrofitting measures.
• Emergency Action Plans (EAPs): Mandated by DSOD for all High and Extremely High hazard dams to guide evacuation and response efforts. • Early Warning Systems: Improved flood monitoring and automated alert 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 implementing the associated mitigation actions, along with the priority, potential funding source, and expected time frame are listed in Section 7.8.

6.7.13 Summary
Los Angeles County has 90 state-jurisdictional dams, with 70 classified as High or Extremely High hazard, meaning their failure could result in widespread loss of life and economic devastation. While regulatory oversight has improved dam safety, aging infrastructure, seismic threats, and increased storm intensity remain challenges.

Continued investment in retrofits, early warning systems, and emergency planning is 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
movement of rock, soil, or debris along a
slope due to gravity. This process can occur
suddenly or gradually over time, depending
on contributing factors such as soil
composition, slope stability, and external
triggers. Land movement encompass a
variety of movement types including
mudflows, rockfalls, debris flows, land
slumps, land subsidence, and soil
movement. In Los Angeles County, the
diverse topography and geological
formations make certain areas more prone to
land movement, particularly during periods
of intense precipitation, seismic activity, or
human land-use modifications.

Climate change exacerbates land movement
by increasing the frequency and intensity of
extreme weather events, such as heavy rainfall and flooding, which can lead to accelerated erosion and heightened landslide risks.

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Land movement often occur in conjunction with other natural hazards, exacerbating their impact. Some of the primary contributing factors include:
• Seismic Activity: Earthquakes can destabilize slopes, leading to land movement and rockfalls. The force of seismic shaking can cause sudden failures, particularly in areas with pre-existing instability.
• Heavy Rainfall and Flooding: The likelihood of land movement increases after successive storms. Prolonged or intense rainfall saturates soil, reducing its cohesion and triggering slope failures.
• Coastal Erosion: Waves and storm surge erode coastal cliffs, leading to instability and eventual collapse, particularly in areas such as County beaches and coastal communities, many of which have previously experienced significant erosion. • Wildfires: Loss of vegetation due to fires reduces the soil’s ability to retain moisture, making slopes more susceptible to erosion and land movement during subsequent rain events.
• Burn Scars: Wildfire burn scars significantly elevate the risk of land movement by stripping the land of stabilizing vegetation. Areas affected by major fires such as the Woolsey Fire (2018), Bobcat Fire (2020), Bridge Fire (2024), Eaton Fire (2025), and 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 steep slopes, unstable geology, and weather patterns. The California Geological Survey (CGS) Landslide Susceptibility Map highlights high-risk areas. For a better visual representation of the Land Movement Hazard within the LA County planning area, 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):
• Santa Monica Mountains
• San Gabriel Mountains
• Sierra Pelona Mountains
• Baldwin Hills
• Puente Hills
• Palos Verdes Hills
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These areas are particularly vulnerable due to their steep terrains, weak rock formations, and history of slope movement. Additionally, human activities such as grading, excavation, and construction in these regions can further destabilize the ground, increasing the likelihood of land movement. Areas impacted by past wildfires, known as burn scars, are also highly susceptible to land movement, as the loss of vegetation reduces soil stability and increases erosion risks during heavy rains. This is particularly concerning in wildfire-prone areas such as the Santa Monica Mountains and the foothills of the San Gabriel Mountains, where post-fire land movement have historically caused significant damage.

6.8.3 Extent
The extent of land movement in Los Angeles is significant and varied, influenced by its unique geological setting. According to the 2011 CGS Landslide Susceptibility Map, 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-Risk Landslide Zones
(sq. miles)
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
Land movement have historically caused significant damage in Los Angeles County, often resulting in property destruction, infrastructure damage, and road closures. There have been no federal declarations or state proclamations for dam failure in the last five years. Some of the most notable events include:
• 1956 – Portuguese Bend Landslide: A massive landslide on the Palos Verdes Peninsula began in 1956 and remains active today. The movement of land has displaced homes and infrastructure, highlighting the region’s ongoing geologic instability.
• 1994 – Northridge Earthquake-Induced Land movement: The earthquake triggered more than 11,000 moving events, primarily in the Santa Susana Mountains and San Gabriel Mountains, causing extensive road and structural damage. • March 1995 – Pacific Palisades Landslide: Heavy rains weakened the coastal bluffs, leading to a 300-foot-wide collapse that buried part of the Pacific Coast Highway under 30 feet of debris.
• March 2005 – Sunset Mesa Landslide: A slope failure near Malibu caused over 20,000 cubic yards of debris to block roadways and damage property. • July 2023 – Peartree Lane Land Movement (Rolling Hills Estates): A sudden slope failure resulted in the displacement of 12 homes, which were red-tagged due to structural instability.
• September 2024 – Accelerated Land Movement in Rancho Palos Verdes: A significant increase in land movement, with certain areas shifting up to four inches per week toward the ocean, threatening roads and over 250 residential properties.

6.8.5 Types of Land Movement
Debris Flow/ Mudflow/ Soil Movement
Debris flow involves the rapid movement of a dense mixture of water, soil, rock, and organic material down a slope. This process can have significant impacts on landscapes, ecosystems, and human infrastructure.

Debris flows are characterized by their fluid-like behavior and ability to transport large objects, such as boulders and trees. They can travel at high speeds making them highly destructive. The composition of a debris flow can vary, but it typically includes:

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• Water: A crucial component that facilitates movement. • Soil and Rock: These provide the bulk of the material in a debris flow. • Organic Material: Includes vegetation and other natural debris that get caught in the flow.

Mudflows are rapid movements of water-saturated earth materials that can cause significant damage to both natural environments and human settlements. Mudflows are characterized by their fluid-like motion, which occurs when soil, rocks, and debris become saturated with water. This saturation reduces the friction between particles, allowing the mass to move downhill under the influence of gravity. Key characteristics include:
• Speed and Volume: Mud flows can travel at speeds up to 35 miles per hour and can carry large volumes of material, including rocks, trees, and even vehicles. • Consistency: The consistency of a mud flow can vary from a thick, viscous slurry to a watery flow. This depends on the proportion of water to solid materials. • Path: Mud flows typically follow existing drainage patterns, such as river channels and valleys, but can also carve new paths, leading to unpredictable and widespread damage.

Soil movement is a natural process that significantly impacts the environment and human activities. It involves the displacement of soil particles due to various natural and human caused factors. Key characteristics include:
• Landslides: Often occurring in hilly areas, landslides involve the downward movement of rock and soil. They can be sudden and fast-moving, making them particularly dangerous.
• Soil Creep: This is a slow and gradual movement of soil down a slope, often unnoticed until significant damage occurs.
• Soil Liquefaction: During an earthquake, saturated soil can temporarily lose its strength and behave like a liquid, causing structures to sink or tilt.

Causes
In Los Angeles County, several factors contribute to the occurrence of debris flows/mudflows/ soil movement:
• Heavy Rainfall and Storm Events: Intense and prolonged rainfall, often associated with storms, can saturate the soil, reducing its stability and triggering debris flows.

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The region's Mediterranean climate, with wet winters and dry summers, creates conditions conducive to such events.
• Wildfires: Los Angeles County frequently experiences wildfires, which can burn and destabilize vegetation that normally helps hold soil in place. The loss of vegetation increases the risk of soil erosion and, consequently, debris flows during subsequent rainfalls.
• Steep Terrain: The county's mountainous terrain, including areas like County mountainous areas, is particularly prone to debris flow. The steep slopes facilitate the rapid movement of debris downhill.
• Soil Composition: Certain soil types, such as clay-rich soils, can become highly unstable when saturated with water, making them more susceptible to debris flow. • Human Activity: Urban development, road construction, and deforestation can alter natural landscapes and exacerbate conditions that lead to debris flow. • Seismic Activity: Los Angeles County is situated in a highly active seismic zone, making it prone to earthquakes. Seismic activity can lead to soil liquefaction, landslides, and ground shaking, all contributing to soil displacement.

Land Subsidence
Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to various natural and human-induced factors. This hazard can have significant impacts on the environment, infrastructure, and communities.

A reduction in land elevation is one of the most noticeable features of land subsidence, leading to significant changes in the landscape. This phenomenon can occur due to natural processes, such as the dissolution of limestone, as well as human activities like the excessive extraction of groundwater, oil, or natural gas. Furthermore, land subsidence increases the risk of flooding because the lower elevation can lead to poor drainage and water accumulation. As the ground sinks, it often results in the formation of depressions, fissures, and sinkholes, which can dramatically alter the geography and infrastructure of the area.
• Depressions: Are sunken or low-lying areas on the Earth’s surface, often formed by natural or man-made processes.
• Fissures: Are a long, narrow crack or linear opening in the Earth’s crust. • Sinkholes: Are holes in the ground causes by the collapse or sinking of surface material into an underlying void.

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Causes
• Groundwater Extraction: One of the primary causes of land subsidence in Los Angeles County is the excessive extraction of groundwater. As water is pumped out of underground aquifers, the ground above can sink or settle, leading to subsidence.
• Oil and Gas Extraction: The removal of oil and natural gas from beneath the earth's surface also contributes to land subsidence. This extraction can create voids and reduce pressure in subterranean layers, causing the ground to sink. • Natural Soil Compaction: Over time, natural processes such as soil compaction can lead to gradual subsidence. In areas with loose or unconsolidated soils, the weight of overlying materials compacts the ground, resulting in a lowering of the 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 pebbles dislodging to massive boulders crashing down with significant force and impact.

Rock falls are characterized by:
• Speed and Suddenness: Rock falls occur quickly and without much warning, making them particularly dangerous.
• Varied Sizes: The size of the falling material can range from small pebbles to large boulders, impacting the severity of the event.
• Path Predictability: While the initial trigger point is often identifiable, the path of descent can be unpredictable due to varying terrain and obstacles.

Causes
The primary causes of rock falls include:
• Weathering and Erosion: Over time, weathering processes such as freeze-thaw cycles, chemical weathering, and the action of water can weaken rock structures.

Erosion can undermine the base of slopes, making rocks more susceptible to falling. • Seismic Activity: Los Angeles County is located in a seismically active region.

Earthquakes can dislodge rocks from cliffs and steep slopes, triggering rock falls.

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• Heavy Rainfall: Intense or prolonged rainfall can saturate the ground, increasing the weight and pressure on rock faces. This saturation can lead to the loosening and collapse of rocks.
• Human Activity: Construction, mining, and other human activities can destabilize rock formations. The vibrations from heavy machinery and blasting can initiate rock falls.

6.8.6 Probability
Landslides and other land movement events happen in Los Angeles County fairly often, especially after heavy rain or in areas that recently had wildfires or are prone to sliding. • Small landslides (like debris flows) are most likely during years with heavy rain, especially El Niño years. These happen every 2 to 7 years; there is 14% to 50% chance each year during those cycles.
• In high-risk zones (like steep mountain slopes with a history of movement), probability is 1–2% chance per year, especially following multi-year wet periods or major wildfires.
• Some areas of the County have been experiencing continuous sliding.

6.8.7 Vulnerability
Land movement pose risks to life, property, and essential infrastructure. The 2024 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:
• Residents of hillside and canyon communities such as Malibu, Topanga, and the Palos Verdes Peninsula.
• Homeowners in coastal bluff areas that are facing erosion-driven slope failures. • Communities in wildfire burn scar areas, where the loss of vegetation increases landslide probability during heavy rains.
• 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-seated landslides, especially after wildfire or heavy rain. These hazards can isolate communities, damage property, and disrupt lifelines.

Extent of Exposure
• Total Area Exposed: 284.57 sq mi
• 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%)
• 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
Landslides pose a serious risk to hillside communities and access routes, especially in areas recovering from wildfire. Current development and road infrastructure may not be resilient against slope failure. Mitigation actions should include slope stabilization, targeted buyouts or relocations, and early warning systems.

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6.8.8 Impacts
Los Angeles County's diverse landscape and dense population make it highly susceptible to the effects of land movement, affecting critical infrastructure and raising significant economic, social, and safety concerns.

Transportation Networks
Los Angeles County's extensive transportation network is vital for daily commutes, goods transport, and emergency services. Land movement can severely impact these systems:
• Road Damage: Causes closures, hazardous driving conditions and costly repairs, as seen annually on Pacific Coast Highway (PCH), and many other local roads. • Bridge Compromise: Affects structural integrity, necessitating closures and expensive reconstructions.
• Public Transit Disruptions: Impacts train tracks and bus routes, leading to delays and service interruptions.
• Rail Systems: Track misalignment can cause delays and potential derailments, affecting both passenger and freight lines.

Water Supply Systems
The county's water delivery system is complex and vulnerable to land movement:
• Compromised Pipelines: Leads to ruptures or leaks, disrupting supply and requiring major repairs.
• Reservoir Impact: Landslides can affect water quality and storage capacity.

Energy Infrastructure
Land movement poses risks to Los Angeles County's energy infrastructure, including:
• Electrical Grid Vulnerabilities: Land movement can damage power lines and substations, causing outages.
• Gas Pipeline Risks: Soil shifts can result in gas leaks or explosions, endangering safety.

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Communication Systems
Reliable communication is critical, and land movement can disrupt:
• Telecommunication Towers: Structural damage can impair cellular and internet services.
• Underground Cables: Earth shifts can damage cables, affecting connectivity.

Emergency Services Facilities
• Hospitals and Fire Stations: Essential for emergency response, but structural damage could impede operations, underscoring the need for resilient construction and strategic planning.

Economic Impacts
• Infrastructure Damage: Leads to costly repairs and maintenance of roads, bridges, and buildings.
• Property Loss: Homeowners face financial losses due to property damage or devaluation.

Environmental Impacts
• Ecosystem Disruption: Soil movement can lead to habitat loss and affect local flora and fauna.
• Increased Pollution: Erosion can result in sediment runoff, degrading water quality in rivers and oceans.

For a better visual representation of the Land Movement Hazard within the LA County planning area, please reference Appendix A for maps that show areas that are susceptible to land movement and recent burn scars.

6.8.9 Mitigation Strategies
To reduce the impact of land movement, Los Angeles County has implemented several mitigation and preparedness strategies, including:
• Land Use and Development Regulations: Restricting development in high-risk landslide zones to prevent new structures from being built on unstable terrain. • Infrastructure Resilience: Reinforcing existing infrastructure through slope stabilization projects, retaining walls, and improved drainage systems.

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• Stabilization Regulations: Implementing stricter grading and excavation regulations to minimize the destabilization of slopes.
• Public Awareness Campaigns: Enhancing landslide early notifications by monitoring potential movement areas and precipitation thresholds. • Evacuation Planning: Developing evacuation plans for at-risk communities, ensuring residents receive timely alerts and clear guidance. • Public Education: Conducting public education campaigns to inform residents about recognizing landslide warning signs and preparedness measures. • Operational Area Coordination: Increasing coordination across state, federal, and Office of Emergency Management officials with local jurisdictions to improve forecasting and response efforts.

6.8.10 Summary
Land movement remains a significant hazard in Los Angeles County, particularly in steep and coastal regions. The Palos Verdes Peninsula, Santa Monica Mountains, and San Gabriel Mountains are among the most vulnerable areas, with climate change and human activities exacerbating risks. By implementing land-use regulations, infrastructure reinforcements, and emergency response improvements, the County can 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-energy, long-wavelength ocean
waves generated primarily by
significant offshore seismic events
(such as subduction zone
earthquakes), submarine landslides,
or volcanic eruptions. In the context of
Los Angeles County, tsunamis
represent a relatively infrequent but
potentially high-impact hazard that
could produce rapid coastal
inundation and surge impacts.

Characteristics:
• Triggered mainly by distant, largemagnitude seismic events. • Features long wavelengths and prolonged arrival times. • Capable of producing rapid, deep inundation along low-lying coastal areas. • In summary, tsunamis are dynamic natural phenomena with the potential to cause sudden coastal flooding and damage if a triggering event occurs.

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6.9.2 Location
The updated tsunami hazard profile focuses on the coastal areas of Los Angeles County. The new zone map—developed using enhanced modeling techniques and updated coastal geomorphology data—highlights areas along the Pacific shoreline that are at risk. These include regions adjacent to the Los Angeles Basin, parts of Long Beach, Santa Monica Bay, and other low-elevation coastal zones.

For a better visual representation of Tsunami Inundation zones within the LA County planning area, please reference Appendix A for a “Tsunami Inundation Area” map.

Important Details:
• Coastal segments from the western margins of the Los Angeles Basin extending to the border with Orange County.

Overall, the coastal areas of Los Angeles County, containing our communities and infrastructure, face heightened exposure.

6.9.3 Extent
Using the latest hydrodynamic and inundation modeling, the updated tsunami inundation (zone) map provides a refined view of the extent of potential flooding. The map illustrates how tsunami waves could propagate inland, showing revised boundaries that account for current sea-level conditions and future sea-level rise projections.

Highlights:
• Inundation depths and reach have been recalculated, with some areas potentially experiencing water levels up to several feet in depth.
• The inland reach of flooding varies by local topography, with flat, low-lying areas showing the greatest potential for impacts. Impacted areas include, but are not limited to, Long Beach, The ports of Long Beach and Los Angeles, Marina del Rey, Venice and Santa Monica.
• Critical infrastructure within the updated zones has been identified to prioritize mitigation and evacuation routes for planning.

In essence, the extent of tsunami impacts is now mapped more precisely, offering local decision-makers a clearer view of potential flooding depths and distances inland.

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6.9.4 History
Historically, significant tsunami events in the Los Angeles region are rare, though distant seismic events (for example: the 1960 Chilean tsunami, or the most recent 2022 Tonga tsunami) have been known to produce measurable impacts. Historical records combined with geological studies indicate that while tsunamis have occurred in the past, their frequency is low compared to other hazards. However, the region’s proximity to major tectonic boundaries necessitates ongoing vigilance.

Historical Context:
• Past events have been sporadic but can serve as valuable lessons for preparedness. • Historical inundation records and sediment studies confirm that tsunamis have reached the Los Angeles coast in prehistory.
• Lessons learned from past minor events underscore the importance of maintaining updated hazard maps.

Thus, while historical tsunami events are infrequent, they provide a critical context for understanding future risks and guiding preparedness measures. There have been no federal declarations or state proclamations for tsunami in the last five years.

6.9.5 Probability
The probability of a tsunami affecting Los Angeles County is generally low when compared to more frequent hazards like earthquakes or floods. Nevertheless, the potential for a distance source tsunami generated by a distant, large seismic event remains a realistic risk. Updated probabilistic assessments—incorporating recent seismic data and tsunami modeling indicate that while the overall likelihood is low, the consequences in the event of a tsunami can be severe.

Probability Considerations:
• Low annual probability but high consequence if an event occurs; Los Angeles County has about a 2% annual chance.
• Distance source events from subduction zones across the ocean contribute most to the risk.
• Continuous monitoring and updated modeling are essential to reassess the risk over time.
• In summary, the probability of a tsunami remains low, but due to the potential for high-impact outcomes, it warrants continuous study and preparedness.

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6.9.6 Vulnerability
Coastal vulnerability in Los Angeles County is significantly influenced by factors such as urban density, low-elevation terrain, aging infrastructure, and socio-economic conditions. The updated tsunami zone map now better delineates areas where these vulnerabilities are most pronounced, highlighting communities that may have limited evacuation routes and fewer resources to recover from rapid inundation. About 75,000 people live in parts of Los Angeles County that could be flooded by a tsunami. Many people also work in these coastal areas, and around 660 unhoused individuals live there, making them especially at risk because they may not have easy access to shelter or transportation.

Tourism adds even more people to these areas, especially during busy weekends or holidays. Places like Santa Monica can see up to 300,000 visitors a day during peak times. This makes evacuating harder if a tsunami warning is issued. Roads near the coast can quickly become crowded, and visitors may not know the best way to leave.

Traffic could slow down emergency plans, so it’s important to have clear signs, early warnings, and good traffic control to help people get to safety quickly.

Factors:
• High population density in low-lying coastal areas.
• Critical infrastructure (e.g., hospitals, utilities, ports and shipping, transportation networks) located within the inundation zones.
• Socio-economic and language barriers that may hinder effective emergency response.
• Limited natural barriers in some coastal segments.
• Vulnerable communities include those with high population densities and critical infrastructure near the coast.

Ultimately, the vulnerability of the region is compounded by both physical exposures and social factors, underscoring the need for targeted mitigation efforts.

Contextual Overview
Coastal communities in Los Angeles County, including ports and tourist zones, are at risk from tsunamis. These rare but highly destructive events can inundate coastal infrastructure with little warning.

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Extent of Exposure
• Total Area Exposed: 32.89 sq mi
• 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%)
• 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
Tsunamis can cause rapid and catastrophic coastal flooding. With critical coastal infrastructure and residential areas exposed, especially in SD4 and SD3, there is a need for robust evacuation planning, vertical evacuation shelters, and community outreach to enhance preparedness and reduce vulnerability.

6.9.7 Impacts
Should a tsunami occur, the potential impacts on Los Angeles County could be extensive. Parts of Los Angeles County that could be impacted by a Tsunami are Marina Del Rey, Port of Los Angeles, Port of Long Beach, and other beach communities in low lying areas. The updated impact assessments reflect possible scenarios ranging from significant property damage to loss of life and long-term economic disruption. The new zone map aids in quantifying these impacts by providing detailed inundation depths and spatial extents, thereby allowing for better risk communication and planning.

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Potential Impacts:
• Severe flooding of coastal infrastructure and residential areas. • Disruption of transportation, utility services, and emergency response operations. • Economic losses in key sectors such as tourism, shipping, and local commerce. • Social impacts including displacement, loss of livelihoods, and challenges in emergency sheltering.

In short, the potential impacts of a tsunami are far-reaching, necessitating robust mitigation, evacuation, and recovery planning to minimize harm.

For a better visual representation of Tsunami Inundation zones within the LA County planning area, please reference Appendix A for a “Tsunami Inundation Area” map.

6.9.8 Summary
The updated tsunami section for the 2025 AHMP incorporates the latest scientific findings and mapping techniques to provide a more precise understanding of tsunami risks in Los Angeles County. By integrating an updated inundation zone map, the revision clarifies the spatial extent of potential flooding and highlights the vulnerabilities in coastal communities. This comprehensive update is designed to guide decision-makers in enhancing preparedness, targeting mitigation strategies, and strengthening community resilience.

Key Takeaways:
• Nature: Tsunamis are infrequent but high-energy events capable of rapid coastal inundation.
• Location & Extent: The updated zone map identifies vulnerable coastal areas with revised inland flood extents.
• History & Probability: Historical events are rare; however, distance events remain a realistic risk.
• Vulnerability & Impacts: High population density and critical infrastructure in coastal zones amplify risk, with potential for severe economic and social disruption.

This updated section is intended to serve as a critical tool for policymakers, emergency managers, and community stakeholders as they work together to reduce the long-term risks associated with tsunamis and enhance overall regional resilience.

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6.10 Severe Wind and Tornado

6.10.1 Nature
Severe wind and tornadoes pose
significant threats to life, property, and
infrastructure, though they differ in
frequency and intensity within Los Angeles
County. Severe wind events, particularly
Santa Ana winds, are a recurring natural
hazard that can cause widespread
damage, including downed power lines,
tree falls, and structural damage. These
winds originate from high-pressure
systems over the Great Basin, funneling dry
and warm air through mountain passes into
the coastal and valley regions at high
speeds. Additionally, storm-driven winds,
microbursts, straight-line winds and gust
fronts associated with severe weather can
create hazardous conditions, often leading
to transportation disruptions, fire hazards,
and prolonged power outages.

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Tornadoes, while relatively rare in the region, have been recorded and can cause localized but intense damage. These violent windstorms form when unstable atmospheric conditions produce rotating updrafts, resulting in a funnel cloud that contacts the ground.

6.10.2 Location
Severe wind events affect the entire Los Angeles County planning area, with the strongest occurrences in canyon passes, valleys, and coastal regions. The Santa Ana winds are most intense in the fall and winter months, particularly impacting areas in the Valley, and foothill communities of the County. Storm-driven winds, on the other hand, can impact any part of the county and vary in intensity based on weather patterns.

These winds can reach speeds of 60 to 80 mph, sometimes exceeding those thresholds, leading to significant damage.

Tornadoes are more sporadic in occurrence and can develop in various parts of the county, particularly in lowland areas where severe thunderstorms have the potential to 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 they descend from the inland desert regions, creating not only critical wind events but also extremely dangerous fire conditions and contributing to the spread of wildfires.

The winds are classified in the Beaufort Wind Scale, see Figure 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 example, o is described as ‘calm’ a sea like a mirror while 12 described as hurricane force with devastating conditions.

Tornadoes are classified using the Enhanced Fujita (EF) Scale Figure 6.10.2. The Enhanced Fujita (EF) Scale is specifically used to rate the intensity of tornados based on the damage they cause (damage indicators) such as building types, and trees. It ranges from EF-0 to EF-5, with increasing numbers indicate stronger tornados and more severe damage. While tornadoes in the region typically do not exceed EF-1 County of Los Angeles
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intensity, they can still produce damaging winds above 100 mph, capable of tearing roofs off buildings, uprooting trees, and overturning vehicles.

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
Calm, smoke rises
vertically
1 1-3 Light Air Scaly ripples, no foam crests
Smoke drift indicates
wind direction, still wind
vanes
2 4-6 Light Breeze Small wavelets, crests glassy,
no breaking
Wind felt on face, leaves
rustle, vanes begin to
move
3 7-10 Gentle
Breeze
Large wavelets, crests begin
to break, scattered whitecaps
Leaves and small twigs
constantly moving, light
flags extended
4 11-16 Moderate
Breeze
Small waves 1-4 ft. becoming
longer, numerous whitecaps
Dust, leaves, and loose
paper lifted, small tree
branches move
5 17-21 Fresh Breeze
Moderate waves 4-8 ft taking
longer form, many whitecaps,
some spray
Small trees in leaf begin
to sway
6 22-27 Strong
Breeze
Larger waves 8-13 ft,
whitecaps common, more
spray
Larger tree branches
moving, whistling in
wires
7 28-33 Near Gale
Sea heaps up, waves 13-19 ft,
white foam streaks off
breakers
Whole trees moving,
resistance felt walking
against wind
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8 34-40 Gale
Moderately high (18-25 ft)
waves of greater length,
edges of crests begin to
break into spindrift, foam
blown in streaks
Twigs breaking off trees,
generally impedes
progress
9 41-47 Strong Gale
High waves (23-32 ft), sea
begins to roll, dense streaks
of foam, spray may reduce
visibility
Slight structural damage
occurs, slate blows off
roofs
10 48-55 Storm
Very high waves (29-41 ft)
with overhanging crests, sea
white with densely blown
foam, heavy rolling, lowered
visibility
Seldom experienced on
land, trees broken or
uprooted, "considerable
structural damage"
11 56-63 Violent Storm
Exceptionally high (37-52 ft)
waves, foam patches cover
sea, visibility more reduced
12 64+ Hurricane
Air filled with foam, waves
over 45 ft, sea completely
white with driving spray,
visibility greatly reduced
Figure 6.10.1 Beaufort Wind Scale
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Enhanced Fujita Scale:

THE ENHANCED FUJITA SCALE (EF SCALE)
EF RATING 3 Second Gust (MPH) DAMAGE
EF 0 65-85 MPH Light: Branches broken,
minor roof damage
EF 1 86-110 MPH
Moderate: Roofs
damaged; trees uprooted
EF 2 111-135 MPH
Considerable: Roofs torn
off, large trees down
EF 3 136-165 MPH Severe: Homes destroyed;
cars lifted
EF 4 166-200 MPH Devastating: Houses
leveled; debris airborne
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 which caused destructions, and wildfires. There have been no federal declarations or state proclamations for Severe Wind & Tornadoes in the last five years. Some notable incidents include:
• November-December 2011: A wind event caused more than $35 million in damages and severely impacted several foothill communities and unincorporated areas.
• December 2019: An EF-0 tornado touched down in South Los Angeles, causing minor roof damage and downing power lines.
• January 2021: A severe windstorm impacted the region, leading to damage across multiple communities and emergency response efforts to clear roadways. • September 2021: An EF-0 tornado developed near the community Lake of Los Angeles; %no damage was reported.

Figure 6.10.2 Enhanced Fujita Scale
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• April 2023: An EF-0 tornado recorded in Cerritos causing tree damage. • March 2023 (DR# 4699): An EF-1 tornado struck Montebello, one of the strongest tornadoes recorded in the area, causing significant damage to commercial structures and vehicles.
• May 2023: An EF-0 tornado occurred near the communities of Carson and Compton damaging buildings and vehicles.
• August 2023 (DR# 4750): Tropical Storm Hillary impacting Los Angeles County.
• February 2024: Strong winds impacting across Eastern Santa Monica Mountain and Santa Clarita Valley.
• March 2024: Strong winds impacting areas around San Gabriel Valley. • January 2025 (DR# 4856): A severe windstorm impacted the region, leading to a Potentially Dangerous Situation (PDS), red flag conditions. Several fires broke out in the area, which exhibited extreme fire behavior, causing widespread destruction.
• March 2025 (DR# 4856): As part of a storm event, an EF-0 tornado struck Pico Rivera, California, at 3:15am, with wind speeds reaching up to 85 mph.

6.10.5 Probability
Severe wind events are a regular occurrence in Los Angeles County, with a high probability, 99% chance recurring annually. Santa Ana winds are particularly common during the cooler months, and climate patterns suggest that extreme wind events may become more frequent due to changing weather dynamics. Because wind events and tornados are localized in nature, probability vary from one area to another and is difficult to determine percentage of happening in one area. Tornadoes remain a lowprobability hazard, 10% chance, in the planning area; however, given past occurrences, they cannot be ruled out entirely. Atmospheric conditions capable of producing tornadoes may arise during severe thunderstorms, particularly in winter storm systems that generate strong wind shear. While the likelihood of an EF-2 or stronger tornado is minimal, the potential for localized damage remains. The Santa Ana winds occur ten to twenty-five times annually and can last for several days, posing a recurring threat of damage and disruption in Los Angeles County.

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6.10.6 Vulnerability
Severe wind and tornadoes can be extensive, affecting both infrastructure and public safety. High-wind events pose a risk to critical infrastructure, particularly power lines, communication systems, and transportation networks. Buildings, especially older structures and mobile homes, are vulnerable to wind-related damage, including roof failures, window breakage, and structural collapse.

In addition to physical damage, severe wind events can cause significant economic disruptions. Prolonged power outages impact businesses, healthcare facilities, and emergency response services. Road closures and debris blockages hinder mobility and commerce, while wind-driven wildfires, a secondary hazard of Santa Ana winds, can lead to devastating losses.

Public safety is also a major concern, with risks of flying debris, vehicle accidents, overturned vehicles, 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 socioeconomic vulnerabilities. These hazards can disrupt critical services, exacerbate existing inequalities, and significantly damage structures not built to withstand extreme wind conditions.

Vulnerable Populations
Out of the county’s estimated 10.2 million residents, the following populations are considered especially vulnerable:
• 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.
• Access and Functional Needs (AFN) Populations: Estimated 1.7 million individuals (17%) including those with disabilities, limited mobility, or communication barriers.
• 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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• People Experiencing Homelessness (PEH): Over 75,000 individuals (2024 LAHSA count), at direct risk from falling debris and lack of shelter during windstorms.
• Mobile Home Residents: Approximately 98,000 units countywide, concentrated in inland valleys and foothill communities that are highly exposed to Santa Ana winds.
• Children Under Age 5: Around 600,000 countywide, vulnerable to respiratory complications from airborne particulates and debris stirred by strong winds. • Economic Impact: Business disruptions, increased insurance claims, and the costs of emergency response and recovery add financial burdens to local communities.

Critical Infrastructure at Risk
Severe wind and tornado events can cause widespread cascading failures in vital systems, including:
• Power Infrastructure: Los Angeles County contains over 20,000 miles of overhead power lines vulnerable to high-wind damage and fire ignition. • Medical Facilities: Over 350 licensed hospitals and health clinics, many reliant on uninterrupted power and access for vulnerable patient populations. • Transportation Corridors: Major highways (I-5, I-10, US-101) and over 3,100 bridges, particularly in canyon and foothill areas, are susceptible to obstruction by fallen trees and debris.
• Communication Towers: Over 800 critical telecom sites serve the county’s emergency communications and can be disrupted by high wind gusts. • Schools: Approximately 2,300 public K–12 schools and 100+ college campuses face operational disruptions from power outages or infrastructure damage during events.

6.10.7 Impacts
Severe wind and tornado events pose significant threats to critical infrastructure, public safety, and community operations in Los Angeles County. High winds, such as those during Santa Ana events, regularly damage power lines, uproot trees, and disable County of Los Angeles
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transportation corridors. A notable example occurred in January 2025, when widespread windstorms caused power outages for more than 200,000 customers, including approximately 127,000 Los Angeles Department of Water and Power (LADWP) customers and over 52,000 Southern California Edison (SCE) customers.

During this same period, wildfires exacerbated by the strong winds impacted several medical facilities, disrupting critical health services and requiring the emergency relocation of patients.

Tornadoes, while rare, have also demonstrated destructive capacity in localized areas.

In March 2025, an EF-0 tornado touched down in Pico Rivera, downing power lines and trees and obstructing roadways, highlighting the potential for tornadic activity to impact urban communities. These hazards not only endanger life and property but also threaten economic continuity and the functioning of emergency services, particularly 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 structural resilience, enhancing early warnings and alerts, and increasing public awareness of such events.

Severe Wind and Tornado Mitigation
• Strengthening building codes to require wind-resistant design features.

Promoting the use of wind-resistant materials and construction techniques in new developments.
• Conducting regular tree-trimming and vegetation management to reduce infrastructure damage risks.
• Retrofitting and reinforcing critical infrastructure, such as power lines and utility systems, to withstand high-wind conditions.
• Implementing public education campaigns on windstorm preparedness and safety measures.
• Leveraging early warning alerting and preparedness messaging, as well as integrating emergency messaging with local broadcast and mobile networks.

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6.10.9 Summary
Severe wind and tornadoes, though differing in frequency, remain potential hazards for Los Angeles County. Santa Ana winds and storm-driven gusts regularly impact the region, causing damage to infrastructure and increasing wildfire risks. While tornadoes are rare, their occasional occurrence necessitates preparedness and mitigation efforts.

By implementing stronger building codes, reinforcing critical infrastructure, and enhancing preparedness and public awareness, the county can reduce its vulnerability 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
This section outlines the defining
characteristics of mass violence,
which includes intentional, highimpact incidents such as terrorism, active shooter events, vehiclerammings, and other coordinated attacks. Understanding the nature of
these events is critical for
developing effective mitigation
strategies.
• Mass violence includes both
targeted attacks (e.g.,
ideologically motivated
terrorism) and opportunistic
acts (e.g., active shooters or
violent assaults in public
spaces).
• These incidents are characterized by their low warning time, high lethality, and potential to incite widespread fear and panic.

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• Acts of mass violence
may be perpetrated by
individuals, small groups,
or well-organized
networks, and can
involve firearms,
explosives, vehicles, or
biological agents.
• These attacks often aim
to disrupt societal
functions, damage
infrastructure, or exploit
vulnerabilities in soft
targets such as schools,
places of worship, or
entertainment venues.

In summary, the nature of mass
violence lies in its deliberate
intent to inflict harm on groups
and disrupt public order,
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
disruption and significant loss of
life and property.

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• Events can result in many casualties and severe physical and psychological impacts.
• Mass violence can disrupt essential services, strain emergency response systems, and create cascading socioeconomic effects.
• The overall disruption may extend far beyond the immediate scene, affecting broader community resilience.

In essence, while these events may be rare, their extensive impacts necessitate comprehensive planning and resilient infrastructure.

6.11.3 History
Historical data illustrates that mass violence has evolved over time, with earlier events 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. • Recent events in the last five years include high-profile active shooter incidents at schools, public transportation hubs, and commercial centers, as well as vehicle-ramming attacks in urban areas.

Overall, the historical trend shows that while frequency remains low, the severity of mass violence incidents has escalated, necessitating continual updates to mitigation strategies.

6.11.4 Location
Mass violence incidents tend to occur in areas where people naturally congregate, including urban centers, transportation hubs, educational and religious institutions, shopping centers, and public events and venues.
• Public spaces such as transit stations, stadiums, malls and other locations where large number of people assemble, are considered higher-risk areas. • Critical infrastructure location, like government buildings and commercial center, are often targeted.
• Certain events may also occur in areas lacking adequate physical security or surveillance.

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Thus, identifying and securing high-density locations is a key focus for mitigating the effects of mass violence.

6.11.5 Probability
The probability of mass violence incidents is difficult to predict precisely; however, the potential for occurrence is recognized as a persistent low-frequency, high-impact risk that requires constant vigilance.
• Such incidents are statistically rare yet present a disproportionate risk due to their catastrophic consequences.
• Threat assessments and intelligence reports indicate that evolving tactics may increase probability over time.
• Continuous monitoring and updated threat analyses (e.g., via THIRA processes) are essential in quantifying risk levels.

In summary, while mass violence events are not common, their inherent unpredictability and high severity demand that communities prepare as if an incident could occur at any time.

6.11.6 Vulnerability
Mass violence depends on a variety of factors, including physical infrastructure design, public awareness, security preparedness, and interagency coordination. • Critical vulnerabilities include open public spaces with minimal physical barriers or limited or ineffective safety / security protocols in place. • Gaps in training and preparedness among first responders can exacerbate the situation during an active incident.
• Social vulnerabilities—such as communication gaps or lack of multilingual emergency information—may hinder rapid response and community resilience.

Thus, reducing vulnerability involves investing in infrastructure hardening, robust security measures, regular training exercises, and effective public communication strategies.

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6.11.7 Impacts
The impacts of mass violence events are multifaceted, life safety, community stability, and the local economy.
• Immediate impacts include fatalities, injuries, and trauma among affected populations.
• Secondary impacts may encompass prolonged disruption of local services, economic downturns, and lasting psychological effects on communities. • Long-term consequences can involve extensive resource allocation for recovery and mitigation, further straining public systems.

Mass violence inflicts immediate harm and often triggers a chain of secondary impacts that complicate community recovery and strain long-term resilience efforts.

6.11.8 Summary
In conclusion, mitigating the hazards of mass violence requires an integrated, multilayered approach that spans prevention, preparedness, response and recovery.

Communities must implement measures to secure high-risk locations, upgrade physical and digital security, enhance interagency coordination, and continuously update training and threat assessments.
• Mitigation strategies include physical security enhancements (e.g., barriers and surveillance), regular active shooter drills, improved emergency communication systems, and coordinated law enforcement and public health responses. • Investment in resilience-building measures and community outreach helps to ensure that, in the event of an incident, communities can recover quickly and effectively.

This section underscores that while mass violence events are rare, their potential for 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
the integrity, confidentiality, or
availability of information. Cyber
incidents can range from minor
targeted data breaches to largescale ransomware attacks and distributed denial-of-service (DDoS)
events that compromise critical
infrastructure. Common types of
cybersecurity incidents include, but
are not limited to:
• Data Breaches: The compromise, unauthorized disclosure, or unauthorized acquisition of information.

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• Malware: Malicious hardware, firmware, or software that is intentionally included or inserted in a system for a harmful purpose. • Ransomware: 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. • Denial of Service (DoS): An attack meant to shut down a machine or network, rendering it inaccessible to its intended users.
• Distributed Denial of Service (DDos): A DoS attack that uses numerous hosts to perform the attack.
• Insider Threats: When an insider (e.g., an employee or vendor) uses their authorized access, wittingly or unwittingly, to do harm to an organization. • Phishing Attacks: 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:

Rapid Onset: Impacts to operations can occur suddenly and evolve quickly. • Sophistication: Can be highly sophisticated with state or non-state actors involved.
• Hybrid Attacks: May involve both cyber and physical components due to interdependencies.
• 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
Unlike traditional hazards that have a physical geographic footprint, cybersecurity incidents are inherently transboundary. However, their effects manifest locally through the disruption of critical services and systems and necessitate regionally coordinated preparedness and response efforts.

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Jurisdictional Relevance:
• Impact local government networks and county infrastructure. • Affect public and private sector systems within Los Angeles County. • Disrupt critical infrastructure such as utilities and cause cascading impacts. • Involve cyber nodes that, while globally distributed, converge on regional networks.

Critical Sectors Impacted:
• Hospitals and healthcare facilities.
• Financial, banking, or payroll systems.
• Transportation providers and systems.
• Utilities such as electricity, gas, and water.
• Emergency response and public safety agencies.

6.12.3 Extent
The extent of cybersecurity incidents is measured not only by the volume of compromised data or financial loss but also by the potential disruption to essential services and critical infrastructure.

Scope of Impacts:
• Rapid spread across interconnected digital systems.
• Potential for cascading failures that disrupt multiple sectors. • Economic losses that may run into millions of dollars.

Measurable Factors:
• Number of systems compromised.
• Downtime of critical infrastructure and services.
• 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, continuity of operations planning, backup systems and redundancies, disaster recovery strategies, and regional cyber response coordination.

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6.12.4 History
Historically, cybersecurity incidents have evolved from isolated breaches to 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 large corporations, public entities including local governments, and critical infrastructure sectors. Previous major cybersecurity incidents have included:
• 2024 Los Angeles County Superior Court Ransomware Attack: Resulted in the shutdown of nearly every court system, a multi-day closure of the court, and cascading impacts to operations.
• 2024 Hospital Group Attack: A major hospital company experienced an attack that caused IT and phone system outages and disrupted patient care at several Los Angeles County hospitals.
• 2024 Telecommunication Industry Attacks: A series of attacks against telecommunications providers in the United States resulted in compromised customer data.
• 2023 City Attack: A cybersecurity incident at a city within Los Angeles County caused city IT systems to be taken offline.
• 2022 Aviation Industry Attacks: 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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Risk Trends:
• Rapid expansion of the Internet of Things (IoT), the network of internetconnected devices ranging from smart refrigerators to autonomous vehicles, has added new attack vectors to the threat landscape.
• Increasing sophistication of cybercriminal methods including zero-day exploits, a previously unknown cybersecurity vulnerability.
• Growing frequency of reported incidents nationally and globally.

Contributing Factors:
• Inadequate cybersecurity measures in legacy systems still being used by organizations.
• Underinvestment in cyber defense infrastructure or cybersecurity expertise. • Greater digital reliance in everyday operations without proper continuity of operations planning.

Given current trends and technological developments, the likelihood of cybersecurity incidents remains high, necessitating ongoing vigilance and enhanced preparedness measures. As cybersecurity incidents continue to increase in frequency, the potential 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 to attack. This is influenced by both technological and organizational factors including, but not limited to: outdated software or use of legacy systems, insufficient patch management, inadequate segmentation and defense-in-depth strategies, and lack of cybersecurity training among personnel. Organizational challenges also contribute to cybersecurity vulnerability including, but not limited to: budget constraints, gaps in coordination, and rapid technology adoption without corresponding security protocols.

According to the 2024 Threat and Hazard Identification and Risk Assessment (THIRA), over 616,000 people may be affected by a large-scale cybersecurity incident with cascading impacts to utilities. Over 123,000 of those impacted in the THIRA scenario are estimated to have access and functional needs and over 77,000 people are County of Los Angeles
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estimated to have limited English proficiency. Depending on the utilities affected by the incident, a widespread amount of the population could be without utility service for an extended period. Addressing these vulnerabilities is essential to reduce the risk and potential disruption of cybersecurity incidents, calling for both technical upgrades and improved interagency coordination.

6.12.7 Impacts
The impacts of cybersecurity incidents are multifaceted, affecting economic stability, public safety, and critical infrastructure operations.

Direct Impacts:
• Disruption of critical services (e.g., healthcare, emergency response, transportation, etc.).
• Extended duration Continuity of Government or Continuity of Operations event. • Financial losses due to ransom payments, remediation costs, and potential legal fees.
• Loss, compromise, or unauthorized release of sensitive data.

Indirect impacts:
• Erosion of public trust in digital services and affected institutions. • Cascading effects on physical infrastructure (e.g., power grid, water systems, wastewater, etc.).
• Long-term economic repercussions from reduced competitiveness. • The significant impacts—both direct and cascading—of cybersecurity incidents necessitate comprehensive mitigation and recovery strategies that address both technical and socioeconomic dimensions.

6.12.8 Summary
In summary, cybersecurity incidents represent an evolving and critical threat that intersects with multiple aspects of community resilience and safety.

Key Takeaways:
• Cyber incidents are dynamic, sophisticated, and far-reaching in impact • They affect local systems despite their global nature County of Los Angeles
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• Historical trends and increasing digital dependency heighten both probability and vulnerability
• Impacts extend beyond financial loss to include service disruption and cascading infrastructure failures
Cybersecurity incidents demand a proactive, coordinated response that integrates robust technical defenses with cross-sector planning and recovery efforts. By understanding the nature, scope, and potential consequences of these incidents, 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 disrupt the continuous flow of people, goods, and emergency services across Los Angeles County. Transportation incidents can be triggered by a variety of factors including natural events, human error, and deliberate acts. Other characteristics include:
• Affected Modes of Transportation: Incidents can involve any mode of transportation such as multi-vehicle collisions, hazardous material spills, rail derailments, aviation incidents, and maritime disruptions. • Cascading Impacts: Disruptions to the transportation system often have the potential to trigger cascading failures due to the interconnected design of highways, rail networks, airports, and seaports.
• Contributing Factors: Incidents may be influenced by both predictable factors (e.g., rush-hour congestion) and unpredictable occurrences (e.g., extreme weather or infrastructure failure).

6.13.2 Location
The county’s network encompasses highways, rail, airports, ports, and local roads that are critical to regional mobility and commerce.

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• Freeways: Los Angeles County boasts an extensive freeway system with over 1,200 miles of high-capacity roads including corridors such as I-5, I-405, I-10, I-710, and I-210.
• 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 aviation airports. The County owns and operates Brackett Field Airport, Compton/Woodley Airport, San Gabriel Valley Airport, General William J. Fox Airfield, and Whiteman Airport. The Ports of Los Angeles and Long Beach, which are two of the busiest ports in the United States and vital for national and international trade, are also in Los Angeles County. Additionally, Los Angeles Union Station serves as the largest passenger rail station on the west coast. • Other Transportation Networks: The county includes robust passenger rail, bus, and paratransit systems, along with freight rail systems, emerging mobility options such as taxis and rideshare services, and enhanced bicycle networks.

This comprehensive network is the backbone for daily commuting, freight movement, and emergency response across the region.

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-vehicle collisions, hazardous material spills, and roadway fires impacting multiple vehicles with potential delays in emergency responses. • Rail disruptions can impede commuter and freight services, impacting both local transit and regional connectivity.
• Air and maritime incidents—such as delays at major airports or disruptions at port facilities—can significantly affect commerce, supply chains, and public safety. • Cascading effects across interconnected transportation modes may exacerbate congestion and strain additional infrastructure systems such as power, water, and emergency communications.

The extensive and interdependent nature of these networks means that an incident in one area can quickly influence multiple transportation systems.

County of Los Angeles
All-Hazards Mitigation Plan

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Glendora City CouncilJune 9, 2026

Glendora City Council
June 9, 2026