Item No.
TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL
FROM: OFFICE OF THE CITY MANAGER
BY: ANTHONY HILDEBRAND, FIRE CHIEF
DATE: FEBURARY 25, 2025
SUBJECT: ADOPTION OF THE 2024 CITY OF DOWNEY HAZARD MITIGATION PLAN
EXECUTIVE SUMMARY
The City Council will consider adopting Resolution No. 25-8292, approving the updated 2024 Hazard Mitigation Plan. The purpose of mitigation planning is to identify policies and actions that can be implemented over the long term, creating a framework for risk-based decision making to reduce damages to lives, property, and the economy from future disasters.
RECOMMENDATION
That the City Council:
Adopt Resolution No. 25-8292, adopting the 2024 City of Downey Hazard Mitigation Plan.
BACKGROUND
The Federal Disaster Management Act of 2000 requires every local, county, state government to have an approved Hazard Mitigation Plan (HMP) in order to be eligible for pre- and post-disaster grants and functions. The purpose of mitigation planning is to identify policies and actions that can be implemented over the long term to reduce risk and future losses. A proper mitigation plan forms the foundation for Downey’s long-term strategy to reduce disaster losses and rebuild in a way to prevent/mitigate future hazards.
It creates a framework for risk-based decision-making to reduce damages to lives, property, and the economy from future disasters. It is recommended that agencies update their plans about every five years.
The last Hazard Mitigation Plan was adopted in 2017. In May 2022, the City of Downey was awarded funds from the Hazard Mitigation Grant Program to conduct a plan update as it has been five years since the last plan was adopted. The Hazard Mitigation Grant Program is a federal grant, managed by the State. The award consists of $56,250 to cover the expense of revising the City’s Hazard Mitigation Plan, with a 25% match ($18,750), totaling at $75,000 for the entire project. Under the supervision of the Emergency
ADOPT RESOLUTION NO. 25-8292, A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF DOWNEY ADOPTING THE 2024 CITY OF DOWNEY HAZARD MITIGATION PLAN.
FEBURARY 25, 2025
PAGE 2
Preparedness Program Manager, the City hired Integrated Solutions Consulting through the City’s competitive bidding process to help update the plan.
ANALYSIS
The draft Hazard Mitigation Plan was approved by the State of California Office of Emergency Services (Cal OES) on November 5, 2024. The intent of the Hazard Mitigation Plan is to develop a baseline understanding of natural and man-made hazards, determining ways to reduce those risks, and prioritizing mitigation recommendations for implementation. Some identified hazards include earthquakes, wildfire smoke/air quality, utility loss, severe weather, civil unrest, etc. Each hazard is assessed based on historical and regional data. It describes the probability of the hazard and the jurisdiction’s vulnerability to those hazards, such as the financial risk. The development of the plan included public surveys, meetings with community stakeholders (i.e., City departments, schools, hospitals, non-profits), and public outreach during community events. Based on the identified risks, the Planning Team identified specific mitigation actions to reduce the impact or likelihood of the hazards.
The State submitted the Plan to FEMA and it was approved on November 22, 2024.
Following the approval of Cal OES and FEMA, the City must adopt the Plan and provide proof to FEMA.
Upon adoption, the Plan will be shared with partner agencies and authorities. Additionally, a digital copy of the plan will be posted on the City’s website, per the requirement of the Hazard Mitigation Grant Program.
CITY COUNCIL PRIORITIES
Quality of Life, Safety & Infrastructure
FISCAL IMPACT
There is no fiscal impact
ATTACHMENTS
Attachment A: No. 25-8292, adopting the 2024 City of Downey Hazard Mitigation Plan Attachment B: FEMA Approval Letter (November 22, 2024)
Attachment C: 2024 City of Downey Hazard Mitigation Plan
RESOLUTION NO. 25-8292
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF DOWNEY
ADOPTING THE 2024 CITY OF DOWNEY HAZARD MITIGATION PLAN
WHEREAS, the Federal Disaster Mitigation Act of 2000 requires that local governments develop and submit local hazard mitigation plans to the Federal Emergency Management Agency (FEMA) as a condition of receiving FEMA Hazard Mitigation Grant Program Funds; and
WHEREAS, the Disaster Mitigation Act requires local governments to develop and submit hazard mitigation plans to the California Governor’s Office of Emergency Services (Cal OES) and FEMA every five years; and
WHEREAS, the Emergency Preparedness Program Manager, City departments, and community leaders developed the Hazard Mitigation Plan for the City of Downey; and
WHEREAS, the public was provided with the opportunities to comment on the draft Hazard Mitigation Plan prior to the State’s and FEMA’s approval; and
WHEREAS, the draft Hazard Mitigation Plan submitted to the State of California Office of Emergency Services (Cal OES) was approved on November 5, 2024; and
WHEREAS, the draft Hazard Mitigation Plan submitted to FEMA was approved on November 22, 2024.
NOW, THEREFORE, THE CITY COUNCIL OF THE CITY OF DOWNEY DOES HEREBY RESOLVE AS FOLLOWS:
SECTION 1. The City Council hereby approves and adopts the City of Downey Hazard Mitigation Plan and directs staff to forward copies of the Plan to the appropriate local, state, and federal authories, and include copies of this resolution in the Hazard Mitigation Plan. A copy of the Plan is attached hereto as Exhibit A and incorporated by reference.
SECTION 2. The City Council further adopts the Downey Hazard Mitigation Plan by reference into the safety element of its general plan in accordance with the requirements of Assembly Bill 2140.
SECTION 3. The City Clerk shall certify to the adoption of this Resolution.
APPROVED AND ADOPTED this 25th day of Feburary, 2025.
_________________________________
HECTOR SOSA
Mayor
ATTEST:
______________________________
MARIA ALICIA DUARTE, CMC
CITY CLERK
APPROVED AS TO FORM:
ATTACHMENT A
RESOLUTION NO. 25-8292
PAGE 2
_______________________________
JOHN M. FUNK
City Attorney
I HEREBY CERTIFY that the foregoing Resolution was adopted by the City Council of the City of Downey at a Regular Meeting held on the 28th day of January, 2025, by the following vote, to wit:
AYES: Council Members:
NOES: Council Members:
ABSENT: Council Members:
ABSTAIN: Council Members:
MARIA ALICIA DUARTE, CMC
City Clerk
U.S. Department of Homeland Security
FEMA Region 9
1111 Broadway, Suite 1200
Oakland, CA 94607-4052
www.fema.gov
November 22, 2024
Rakdy Kholk
Emergency Manager
City of Downey, Fire Department, Office of Emergency Management 11111 Brookshire Avenue
Downey, CA 90241
Dear Rakdy Kholk:
The Federal Emergency Management Agency (FEMA) has completed its review of the City of Downey 2023 Hazard Mitigation Plan and has determined that this plan is eligible for final approval pending its adoption by the City of Downey.
Formal adoption documentation must be submitted to FEMA Region 9 within one calendar year of the date of this letter, or the entire plan must be updated and resubmitted for review. FEMA will approve the plan upon receipt of the documentation of formal adoption.
If you have any questions regarding the planning or review processes, please contact the FEMA Region 9 Hazard Mitigation Planning Team at [email protected].
Sincerely,
Alison Kearns
Planning and Implementation Branch Chief
Mitigation Division
FEMA Region 9
Enclosure (1)
City of Downey Plan Review Tool, dated November 22, 2024 cc: Robyn Fennig, State Hazard Mitigation Officer, California Governor’s Office of Emergency Services
Victoria LaMar-Haas, Hazard Mitigation Planning Chief, California Governor’s Office of Emergency Services
ATTACHMENT B
City of Downey
Hazard Mitigation Plan
2024
Fire Department, Office of Emergency Management
ATTACHMENT C
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City of Downey Hazard Mitigation Plan TOC-1
Table of Contents
PLAN ADOPTION
EXECUTIVE SUMMARY
ES.1 Plan Requirements and Objectives...............................................................ES-1 ES.2 Mitigation Definition.......................................................................................ES-3 ES.3 Planning Process Summary..........................................................................ES-4 ES.4 Hazard Analysis ........................................................................................... ES-5 ES.5 Mitigation Strategies and Implementation Plan ......................................... ES-6 ES.6 Monitoring, Evaluating, and Updating the Plan ......................................... ES-7
CHAPTER 1: PLANNING PROCESS
1.1 Planning Process ............................................................................................ 1-2
1.2 Steering Committee & Public Involvement ................................................... 1-7
1.3 Review and Incorporation of Existing Plans ............................................... 1-13
CHAPTER 2:PLANNING AREA PROFILE
2.1 City Description .............................................................................................. 2-1
2.2 Development Trends ...................................................................................... 2-4
2.3 Population ..................................................................................................... 2-11
2.4 National Flood Insurance Program .............................................................. 2-14
CHAPTER 3: RISK ASSESSMENT
3.1 Hazard Identification & Risk Assessment ..................................................... 3-1
3.2 FEMA National Risk Index .............................................................................. 3-9
City of Downey Hazard Mitigation Plan TOC-2
3.3 Total Risk Scores .......................................................................................... 3-15
3.4 Hazard Profiles & Description ..................................................................... 3-17
3.5 Acts/Threats of Mass Violence ................................................................... 3-18
3.6 Civil Unrest Hazard Profile .......................................................................... 3-24
3.7 Cyber Incident Hazard Profile ..................................................................... 3-29
3.8 Dam Failure Hazard Profile ......................................................................... 3-35
3.9 Drought Hazard Profile ................................................................................. 3-47
3.10 Earthquake Hazard Profile ........................................................................... 3-63
3.11 Hazardous Materials Release Hazard Profile .............................................. 3-96
3.12 Pandemic Hazard Profile ............................................................................ 3-114
3.13 Severe Weather/Storm Hazard Profile ....................................................... 3-121
3.14 Tornado Hazard Profile .............................................................................. 3-138
3.15 Mass Transportation Accident/Incident Hazard Profile ........................... 3-149
3.16 Urban Fires Hazard Profile ......................................................................... 3-156
3.17 Urban Flood Hazard Profile ........................................................................ 3-162
3.18 Utility Loss Hazard Profile ......................................................................... 3-183
3.19 Wildfire Smoke/Air Quality Hazard Profile ................................................ 3-187
3.20 Windstorm Hazard Profile ......................................................................... 3-203
3.21 Climate Change ........................................................................................... 3-216
CHAPTER 4: MITIGATION STRATEGIES
4.1 Mitigation Strategy ......................................................................................... 4-1
4.1.1 Mitigation Goals and Objectives .................................................................... 4-1
4.1.2 Mitigation Strategies and Actions ................................................................ 4-3
4.1.3 Mitigation Action Plan .................................................................................... 4-4
4.1.4 Mitigation Strategy/Action Timeline Parameters .......................................... 4-5
4.1.5 Mitigation Strategy/Action Estimated Cost ................................................... 4-5
4.1.6 Mitigation Strategy/Action Prioritization Process ....................................... 4-5
City of Downey Hazard Mitigation Plan TOC-3
4.1.7 Mitigation Priorities ........................................................................................ 4-8
CHAPTER 5: PLAN MAINTENANCE
5.1 Mitigation Progress Monitoring ..................................................................... 5-2
5.2 Planning Mechanisms .................................................................................... 5-2
5.3 Plan Update ................................................................................................... 5-11
APPENDICES
Appendix A: Additional Hazard Analysis Documentation
Appendix B: Stakeholder Engagement
Appendix C: FEMA Plan Review Tool
City of Downey Hazard Mitigation Plan ES-i
EXECUTIVE SUMMARY
Table of Contents
ES.1 Plan Requirements and Objectives .......................................................... ES-1 ES.2 Mitigation Definition .................................................................................. ES-3 ES.3 Planning Process Summary ..................................................................... ES-4 ES.4 Hazard Analysis ........................................................................................ ES-5 ES.5 Mitigation Strategies and Implementation Plan ...................................... ES-6 ES.6 Monitoring, Evaluating, and Updating the Plan ...................................... ES-7
List of Tables
Table ES.1: City of Downey Hazard Ranking Summary........................................ ES-5
City of Downey Hazard Mitigation Plan ES-1
ES.1 Plan Requirements and Objectives
The City of Downey (City) Hazard Mitigation Plan is a living document that reflects ongoing hazard mitigation activities. Hazard mitigation involves strategies to reduce short and long- term vulnerability to identified hazards. This document serves as the framework for the ongoing identification and implementation of hazard mitigation strategies developed in the City.
This Hazard Mitigation Plan serves as an update to the 2018 approved Plan.
Background Information
In 2000, the United States Congress determined that disasters and, more importantly, lack of preparedness for disasters, were significant causes of loss of life, human suffering, loss of income, and property loss and damage. Furthermore, because disasters often disrupt the normal functioning of governments and communities and adversely affect individuals and families with great severity, special measures designed to assist the efforts of the affected States in expediting the rendering of aid, assistance, and emergency services, and the reconstruction and rehabilitation of devastated areas, were necessary. As a result, Congress passed the Disaster Mitigation Act of 2000 (DMA 2000), or Public Law 106-390, to amend the Robert T. Stafford Disaster Relief and Emergency Assistance Act. This provides an opportunity for States, Tribal governments, and local jurisdictions to apply for assistance from the Federal government in carrying out their responsibilities to alleviate the suffering and damage which results from such disasters by:
a. revising and broadening the scope of existing disaster relief programs; b. encouraging the development of comprehensive disaster preparedness and assistance plans, programs, capabilities, and organizations by the States and by local governments;
c. achieving greater coordination and responsiveness of disaster preparedness and relief programs;
d. encouraging individuals, States, and local governments to protect themselves by obtaining insurance coverage to supplement or replace governmental assistance; e. encouraging hazard mitigation measures to reduce losses from disasters, including development of land use and construction regulations; and f. providing Federal assistance programs for both public and private losses sustained in disasters.
City of Downey Hazard Mitigation Plan ES-2
DMA 2000 allows State, Tribal, and local jurisdictions to obtain Federal assistance through pre-disaster hazard mitigation planning. As part of the requirements for receiving Federal grants for improving a locality’s resistance to disasters, each locality must determine their existing vulnerabilities and develop a plan to reduce or eliminate these vulnerabilities and must have this plan approved by the appropriate State and Federal officials. Upon approval of this plan, each locality is eligible to receive various types of disaster-related assistance through FEMA’s Hazard Mitigation Assistance (HMA) Program. This includes the Building Resilient Infrastructure and Communities (BRIC) program and Hazard Mitigation Grant Program (HMGP) which releases grant funds before and after a hazard event as well as the Flood Mitigation Assistance Grant (FMA) Program which appropriates funds for projects and planning that will reduce long-term risk of flood damage to structures insured under the National Flood Insurance Program (NFIP).
The BRIC program provides funds for hazard mitigation planning and the implementation of mitigation actions prior to a disaster event. These grants are funded and approved through the Federal Emergency Management Agency (FEMA) on a competitive basis. The HMGP provides grants to implement long-term hazard mitigation measures after a major disaster declaration. These grants are funded by FEMA but are distributed by the State.
In California, that agency is the Governor’s Office of Emergency Services (Cal OES).
FEMA has developed guidance to assist communities in developing both the vulnerability assessments and plans to reduce or eliminate their vulnerabilities to disasters. These tools, coupled with techniques from the safety and security industries were used to develop the City’s Hazard Mitigation Plan 1. In order to be eligible for certain Federal disaster assistance and mitigation funding, the City is required to have a Cal OES- and FEMA-approved Hazard Mitigation Plan in place. As a result, the City obtained grant funding to update this document to fulfill Cal OES and FEMA requirements and provide direction and guidance on implementing hazard mitigation actions on a hazard-level, probability, and cost-priority basis. The overall goal of the Hazard Mitigation Plan is to reduce the potential for damage to critical assets from natural and man-made hazards. In addition, the plan describes past and current hazard mitigation activities , and outlines future mitigation goals and strategies.
FEMA Requirements
FEMA requires that the Hazard Mitigation Plan meet certain requirements. First, the planning process must be open and public, and must allow the public to have an
1 FEMA Hazard Mitigation Assistance Grants (n.d.) Retrieved from ( http://www.fema.gov/hazard-mitigation- assistance
City of Downey Hazard Mitigation Plan ES-3
opportunity to comment during the drafting stage and prior to plan approval. Second, the process must allow other local jurisdictions to be involved in the planning process. Third, the Plan must incorporate, if appropriate, existing plans, studies, reports, and technical information.
FEMA expects that each Hazard Mitigation Plan have the following information:
1. Documentation of the planning process used to develop the plan
2. A risk assessment that provides a factual basis for upgrades and recommendations
3. A description of the natural hazards that can affect the jurisdiction
4. A description of the jurisdiction’s vulnerability to these hazards
5. A description of land usage, and an estimate of losses should a disaster occur
6. A mitigation strategy
7. A plan maintenance process
8. Documentation that the plan has been adopted by the jurisdiction’s governing body
9. Review by the State Hazard Mitigation Officer
ES.2 Mitigation Definition
Mitigation is the ongoing effort to prevent or lessen future emergency or disaster incidents, and the impacts they might have on people, property, and the environment. Examples of mitigation activities include the following:
• Legislation, laws, and regulations
• Variances
• Zoning and land use management
• Engineering and building codes
• Hazard mitigation plans & teams
• Technical guidance & assistance
• Financial assistance
• Hazard Identification
• Risk Analysis
• Evaluation
• Research
• Education
City of Downey Hazard Mitigation Plan ES-4
Mitigation decreases the demand for emergency response resources, reduces the principal causes of injuries and deaths, enables a quicker lifesaving response and economic recovery because the community infrastructure remains intact, and reduces the societal impacts of the emergency because it results in less disruption to the social environment. In essence, mitigation is the foundation of sustainable community development.
ES.3 Planning Process Summary
Hazard mitigation planning is a dynamic process built on realistic assessments of past and present information that enables the City to anticipate future hazards and provide mitigation strategies to address possible impacts and identified needs. The overall approach to the Hazard Mitigation Plan included developing a baseline understanding of natural and man-made hazards, determining ways to reduce those risks, and prioritizing mitigation recommendations for implementation.
To complete these objectives, the City compiled a qualified team with various expertise, including risk management, public safety and health, engineering and public works, water infrastructure, and emergency response agencies to participate on a Steering Committee to guide the development of the City’s comprehensive Hazard Mitigation Plan. In addition, the Steering Committee solicited public involvement throughout the planning process, including the release of a public survey through the City’s website and social media platforms, allowing the public to comment during the drafting stage, and making the draft Plan available to allow the public to comment on its content. Chapter 1: Planning Process contains descriptions of the Planning process, including information on the Steering Committee and public involvement.
City of Downey Hazard Mitigation Plan ES-5
ES.4 Hazard Analysis
The City is vulnerable to a wide range of natural and man-made hazards that threaten life and property. In order to identify the hazards that the City and neighboring communities perceive as the largest threat, each member of the Steering Committee participated in the Hazard Identification Workshop during the first Steering Committee Meeting. The Steering Committee brainstormed potential hazards based on past incidents that have impacted the City and information incorporated from other studies. (Incorporated Plans and studies are described in Chapter 1, Section1.3 - Review and Incorporation of Existing Plans. Each identified hazard was then qualitatively ranked based upon hazard probability/frequency, consequence/severity, and the City’s overall vulnerability. See Chapter 3, Section 3.1 Hazard Identification and Risk Assessment, contains detailed information regarding the hazard ranking. Figure 3.1 also outlines the risk formula. Table ES.1 provides a summary of the hazard ranking.
Table ES.1: City of Downey Hazard Ranking Summary
Hazard Rank
High
Earthquake
Wildfire Smoke/Air Quality
Medium
Hazardous Materials Release
Cyber Incident
Utility Loss
Acts of Mass Violence
Drought
Civil Unrest
Severe Weather/Storm
Mass Transportation Accident
Pandemic
Low
Dam Failure
Urban Flood
Tornado
Urban Fires
Windstorm
City of Downey Hazard Mitigation Plan ES-6
ES.5 Mitigation Strategies and Implementation Plan
Plan Goals and Objectives
As part of the development process, Plan goals and objectives were revalidated to provide a framework for mitigating hazards and proposing potential mitigation actions. The goals are consistent with the California State Hazard Mitigation Plan and the Los Angeles County Hazard Mitigation Plan and were developed by the Steering Committee. The City’s overall Plan goals are to:
• Protect Life, Property, and Commerce
• Promote Public Awareness of the Vulnerability to Hazardous Events and Ongoing Mitigation Strategies
• Preserve the Environment
• Promote Community-wide Involvement with Hazard Mitigation • Increase the Capacity of Emergency Operational Functionality Mitigation Strategies
Mitigation strategies are administrative and/or engineering project recommendations to reduce the vulnerability to the identified hazards. The Steering Committee identified specific mitigation actions to reduce the impact or likelihood of the hazards. The specific objectives served as a starting point for developing the mitigation actions.
Implementation Plan
Following the identification of mitigation actions, a simplified benefit/cost analysis was applied in order to prioritize the mitigation actions for implementation. The benefits of proposed actions were weighed against multiple factors as part of the project prioritization process.
Results from the benefit/cost analysis are collocated in Chapter 4, Table 4.2 New and Ongoing Strategies in the status column labeled STAPLEE+E prioritization score. Chapter 4, Section 4.1.6 Mitigation Strategy/Action Prioritization Process contains additional information regarding the prioritization approach.
City of Downey Hazard Mitigation Plan ES-7
ES.6 Monitoring, Evaluating, and Updating the Plan
The Hazard Mitigation Plan is a living document that reflects ongoing hazard mitigation activities and requires monitoring, evaluating, and updating to ensure the mitigation actions are implemented. To facilitate the Hazard Mitigation Planning process and adhere to regulatory requirements, the Plan will be reviewed annually, and any major revisions will be incorporated into the five-year update. In addition, public involvement will be requested when applicable. Chapter 5: Plan Maintenance outlines the update requirements and planning mechanisms the City has in place for ongoing hazard mitigation.
City of Downey Hazard Mitigation Plan 1-i
PLANNING PROCESS
Table of Contents
1.1 Planning Process................................................................................................ 2
1.2 Steering Committee & Public Involvement ....................................................... 7
1.3 Review and Incorporation of Existing Plans ................................................... 13
List of Tables
Table 1.1: State Disaster Declarations ............................................................................ 3 Table 1.2: Emergency Declarations ................................................................................. 4 Table 1.3: Steering Committee Participants .................................................................... 8 Table 1.4: Downey Resilience Council Meeting – September 12, 2024 ......................... 12 Table 1.5: Community Stakeholder Webinar – September 19, 2024 ............................. 13
City of Downey Hazard Mitigation Plan 1-2
1.1 Planning Process
Hazard mitigation planning is a dynamic process built on realistic assessments of past and present information that engages the City of Downey (City) to anticipate future hazards and provide meaningful strategies to address possible impacts and identified needs. The hazard mitigation planning process involves the following tasks. • Organizing resources
• Assessing risks
• Developing mitigation strategies, goals, and priorities • Adopting a plan
• Implementing the plan
• Monitoring progress
• Revising the plan as necessary
The overall approach to updating the Hazard Mitigation Plan includes building off the baseline understanding of the natural hazards as defined in the 2018 Hazard Mitigation Plan, determining ways to continue reducing those risks, and prioritizing those recommendations for implementation. The following task descriptions provide a detailed narrative of the overall project progression.
1.1.1 Organize Resources
Identify Stakeholders and Compile Steering Committee
Rakdy Khlok, Emergency Manager for the City, invited and coordinated participation for a Steering Committee from the appropriate law enforcement, emergency response, health organizations, City personnel, and local government representatives. The Steering Committee was responsible for providing essential insight into past hazard events, current hazard vulnerability (including specific locations), critical assets, and possible mitigation projects. The following groups were invited to participate in the plan development:
• Key City Personnel (Finance, Community Development, Emergency Management, Public Works, Engineering, Administration, Public Information Office, Code Enforcement and Parks & Recreation)
• City of Downey Police Department
• City of Downey Fire Department
• Private Utility Area Personnel
• Economic Development and Housing
City of Downey Hazard Mitigation Plan 1-3
In addition, the local Area E Disaster Management Area Coordinator, who is familiar with the cities hazards who make up Area E, was invited to take part in the planning process.
Norwalk and Paramount cities also participated in the planning process although not official members of the Steering Committee provided insight on regional hazard vulnerability and mitigation strategies.
Public Process
The Disaster Mitigation Act of 2000 requires an “Open and Public Process” for developing the Hazard Mitigation Plan. This process requires, at a minimum, that the public be allowed to comment on the Hazard Mitigation Plan during the drafting phase and prior to adoption.
To meet this requirement, the City published a public survey and solicited public comments during the drafting stage of the Hazard Mitigation Plan prior to submittal of the Plan for Federal Emergency Management Agency (FEMA) review. The public survey was announced through the City website and social media platforms on February 24, 2023.
The public comment period was held from October 3 through October 17, 2023 and again from July 15, 2024 to September 15, 2024. The second public comment and review period coincided with a major public event on July 24, 2024, to promote the hazard mitigation plan and invite residents to provide feedback. Documentation of public involvement/outreach is provided in Appendix B – Stakeholder Engagement, section B.1.
1.1.2 Risk Assessment
FEMA has declared 11 emergencies and disasters for the state of California between 2019 and February 2024. Emergency declarations allow states access to FEMA funds for Public Assistance (PA), and disaster declarations allow for additional PA funding, including Individual Assistance (IA) and the Hazard Mitigation Grant Program (HMGP). The tables below list emergencies and disasters in the state.
Table 1.1: State Disaster Declarations
Declaration Title Number Declaration Date
California Wildfires 4610-DR-CA Aug 24, 2021
California Wildfires DR-4569-CA
Oct 16, 2020
California Wildfires DR-4558-CA
Aug 22, 2020
California Covid-19 Pandemic DR-4482-CA
Mar 22, 2020
California Severe Winter Storms, Flooding,
Landslides, and Mudslides
DR-4434-CA
May 18, 2019
City of Downey Hazard Mitigation Plan 1-4
Declaration Title Number Declaration Date
California Severe Winter Storms, Flooding,
Landslides, and Mudslides
DR-4431-CA
May 1, 2019
Table 1.2: Emergency Declarations
Declaration Title Number Declaration Date
California Severe Winter Storms, Flooding,
Landslides, and Mudslides EM-3592-CA Mar 10, 2023
California Severe Winter Storms, Flooding,
and Mudslides EM-3591-CA Jan 9, 2023
California Caldor Fire 3571-EM-CA Sep 1, 2021
California Covid-19 EM-3428-CA Mar 13, 2020
California Earthquakes EM-3415-CA Jul 8, 2019
Identify Hazards
Although FEMA only requires and reviews natural hazards in hazard mitigation plans, the City decided to rank and mitigate against a comprehensive list of natural, technological, and human-caused hazards that could impact the planning area. In order to compile the list, the Steering Committee built upon the list of hazards identified in the 2018 Hazard Mitigation Plan and then continued to research historical records, and empirical evidence to determine any additional hazards. Due to the nature of non-natural hazards the following hazards of interest have been assessed for their inclusion within the hazard ranking and mitigation process. Hazards that have been identified as significant in this City and that will be considered in this plan are listed below. Acts of Mass Violence
1. Civil Unrest
2. Cyber Incident
3. Dam Failure
4. Drought
5. Earthquake
6. Hazardous Materials Release
7. Pandemic
8. Severe Weather/Storm
9. Tornado
10. Transportation Accident
11. Urban Flood
12. Urban Fires
13. Utility Loss
14. Windstorm
City of Downey Hazard Mitigation Plan 1-5
15. Wildfire Smoke/ Air Quality
Per FEMA’s requirement to consider all natural hazards, the following were not included because they do not directly impact the City’s geographic location:
• Avalanche
• Hurricanes
• Sea Level Rise
• Storm Surge
• Tsunami
Hazard definitions are included in the Risk Assessment.
Profile Hazard Events
The hazard event profiles consist of either a map indicating the area impacted by each hazard or an important piece of data regarding the characteristics of hazard events within the City and surrounding area. To update the detailed hazard profiles, the Project Team researched and reviewed relevant open-source natural hazard studies and mapping projects. In addition, the City supplied any hazard studies that have been developed specifically for the City. This task determined the hazard magnitude, frequency, and location characteristics (e.g., predicted ground acceleration values, fault locations, flood plains, etc.) that were used as the design-basis for the loss estimates and hazard ranking.
Loss Estimates
FEMA developed a standardized natural hazard loss estimation methodology containing models for estimating potential losses from earthquake, wind (hurricanes, thunderstorms, tornadoes, and extra-tropical cyclones), and flood (river basin and coastal) hazards. The City used HAZUS-MH, a PC-based software, which implements the FEMA-developed methodology and runs on a Geographic Information System (GIS) platform, to map and display earthquake hazard data, as well as the results of earthquake damage for buildings and infrastructure within the City.
HAZUS-MH contains baseline data such as:
• Demographic data (population, age, ethnicity, and income); • General building stock (square footage of occupancy classes for each census tract);
• Emergency response facilities (fire, police, emergency operations centers); • Dams;
• Hazardous materials facilities;
• Roads, airports, and other transportation facilities; and • Electric power, oil, and gas lines and other utility facilities.
City of Downey Hazard Mitigation Plan 1-6
In estimating losses, HAZUS-MH takes into account various physical impacts of a hazard event including:
• Damage to residential and commercial buildings;
• Schools ;
• Critical facilities;
• and infrastructure.
1.1.3 Mitigation Strategy Development
Development of Mitigation Goals and Objectives
The Project Team, based upon information provided by the Steering Committee, discussed the mitigation features and resources that the City currently has in place. These mitigation features provided a framework to determine where practical improvements could be made and where sufficient improvements would be prohibitive due to cost, schedule, or impracticality of implementation.
For each of the hazard events, mitigation goals and objectives were developed with the intention of reducing or eliminating the potential hazard impacts. The mitigation goals and objectives were developed at a Steering Committee Meeting to provide the basis for determining the associated mitigation projects.
Identify and Prioritize Mitigation Actions
Mitigation strategies are administrative and/or engineering project recommendations to reduce the vulnerability to the identified hazards. It was imperative to have City planners and community developers involved in this phase of the Plan in order to develop strategies and projects that will mitigate the hazards cost-effectively, as well as ensure consistency with the City’s long-term mitigation goals and capital improvements. At a Steering Committee Planning Workshop, a team-based approach was used to brainstorm mitigation projects based on the identified hazards. The evaluation and prioritization of the mitigation actions produced a list of recommended mitigation actions to incorporate into the Hazard Mitigation Plan.
City of Downey Hazard Mitigation Plan 1-7
1.1.4 Implementation & Monitoring
Preparation of Implementation Strategy
The Project Team developed an action plan to detail how the mitigation recommendations will be prioritized, implemented, and administered by the City. During the Hazard Mitigation Plan creation process, the Project Team coordinated with the Steering Committee to determine the mitigation project implementation strategy (including identifying responsible departments, funding resources, and estimated implementation timeframe).
1.2 Steering Committee & Public Involvement
While the City and Integrated Solutions Consulting (ISC) had lead responsibility for the update of the City’s Hazard Mitigation Plan, neighboring communities, agencies, businesses, and supporting organizations were invited to participate on the Steering Committee to review the Hazard Mitigation Plan during each phase of the document development. The City and ISC assessed community support through active community leaders, built a Steering Committee, and engaged the public participants through the use of a public community survey. Each member of the Steering Committee had the opportunity to participate in all aspects of the planning process. Table 1.3 provides a list of the Steering Committee participants. Individuals are listed in alphabetical order by last name.
1.2.1 Steering Committee & Participant Solicitation
The City solicited participation in the Hazard Mitigation Plan by contacting both internal and external City boundary stakeholders. Internal stakeholders included members of the various City departments. External stakeholders were comprised of representatives from local agencies and neighboring communities, including the Area E Disaster Management Area Coordinator who is familiar with the hazards of the 25 cities within Area E. Various stakeholders from supporting organizations were given the opportunity to provide feedback via email on the plan during the commend period to ensure equitable opportunity. See Appendix B – Stakeholder Engagement Table B.1 for a list of support organizations invited to participate.
City of Downey Hazard Mitigation Plan 1-8
1.2.2 Steering Committee Participants
The City brought together personnel from management, police, fire, administration, finance, community development, engineering, public works, and recreation departments to ensure the Steering Committee included a variety of departments and provided a mechanism for receiving input from each participant. Additionally, the City compiled historical hazard data, provided relevant planning documents for incorporation into the Hazard Mitigation Plan, and coordinated participation with the public. Each draft chapter was reviewed by the Steering Committee and specific comments and input were incorporated into the plan. The multidisciplinary Steering Committee enabled the City to work together and incorporate each individual’s expertise to provide a comprehensive Hazard Mitigation Plan.
The Hazard Mitigation Plan was developed with assistance and advice from participants from the City and neighboring agencies. Table 1.3 provides a list of the Steering Committee participants. Individuals are listed in alphabetical order by last name.
Table 1.3: Steering Committee Participants
Name Affiliation Title SCM
1 SCM
2 Brian Aleman Engineering, City of Downey Engineer
Cullen Armet Area E Disaster Management Disaster Management Area Coordinator
David Ashman Area E Disaster Management
Area
Disaster Management Area
Coordinator X
Matthew
Baugardner Public Works, City of Downey Director of Public Works Socorro Cottle Hospitals, Kaiser Downey Environmental Health & Safety Director X X
Vaniah De Rojas City Manager/Administrator's
Office, City of Downey ADA/Section 504 Coordinator
Paul Edwards Police, City of Downey Sergeant, Downey Police Department X
Julia Emerson Gas Company, SoCal Gas Public Affairs Manager X Elyzabeth
Estrada Integrated Solutions Consulting Senior Planner X X Jessica Flores Community Development, City of
Downey
Economic Development and
Housing Manager X X
Carlos Guerra Emergency Medical Services,
City of Downey
Ambulance Operator
Coordinator
Desi Gutierrez Capital Improvements, City of
Downey Principal Civil Engineer X
Anthony
Hildebrand Fire, City of Downey Assistant Chief X X
City of Downey Hazard Mitigation Plan 1-9
Name Affiliation Title SCM
1 SCM
2 Robert Jagielski School Board/Administrator,
Downey Unified
Senior Director of Student
Safety X X
Melissa
Johnston Hospitals Disaster Resource Center
Coordinator
Josef Kekula Road Department, City of
Downey
Superintendent Maintenance
and Facilities X X
Rakdy Khlok Emergency Management, City of
Downey Emergency Manager X X
Alvin Lam Information Technology, City of
Downey IT Manager X
Matthew
Lauwers
Code Enforcement, City of
Downey
Code Enforcement
Supervisor X
Isaac Magdaleno Integrated Solutions Consulting Planner X X James McQueen Equity and Inclusion, City of
Downey Program Manager
Daniel Mueller Water/Sewer/Watershed, City of
Downey
Deputy Director of Public
Works and Utilities Manager X
Dorian Munoz
City Manager/Administrator's
Office, Columbia Memorial
Space Center
Senior Activity Specialist
Francesca
Navarro
Grants Management, City of
Downey Principal Accountant X
Richard D.
Newton
Emergency Preparedness
Manager, City of Norwalk
Emergency Preparedness
Manager X
Edwin Norris Engineering, Columbia Memorial
Space Center
Deputy Director of Public
Works
Jayro Roman School Board/Administrator,
Downey Unified Program Administrator X X
Jasmine Salas Public Safety Officer, City of
Norwalk Public Safety Officer X
Matt Stanley Integrated Solutions Consulting Project Manager X X Carole Synder Hospitals, PIH Health Director, Emergency Preparedness X
Eric Wosick City of Paramount Assistant Public Safety
Director X
The Steering Committee met three times during the course of the project to discuss project progress and obtain valuable input and information for documenting the Hazard Mitigation Plan. The meetings are detailed over the subsequent pages. See Appendix B – Stakeholder Engagement for Steering Committee meeting sign in sheets and workshop photos and respective sign in sheets.
City of Downey Hazard Mitigation Plan 1-10
1.2.3 Steering Committee Meeting & Workshop Descriptions Steering Committee, Meeting #1 – Project Initiation, Hazard Identification, and Information Collection
Date: March 15, 2023
During the Project Initiation, Hazard Identification, and Information Collection Meeting, ISC gave an overview presentation that detailed the objectives and scope of the project. After a review of the project schedule and key tasks, the Steering Committee Meeting also served as a mechanism to determine the hazards to profile in detail. To effectively characterize the City’s risk and vulnerability, ISC facilitated a discussion of the historical hazards with the Steering Committee members during this meeting. This meeting also served as a forum to discuss information for background information and asset inventory.
Steering Committee, Meeting #2 –Mitigation Goals, Objectives, and Mitigation Action updates
Date: April 26, 2023
The Plan’s mitigation goals and objectives were updated with the intention of reducing or eliminating the potential hazard impacts, which also provided the basis for determining the associated mitigation projects. The Steering Committee reviewed the goals and objectives from the City’s 2018 Hazard Mitigation Plan, the California State Multi-Hazard Mitigation Plan, and the Los Angeles County Hazard Mitigation Plan as a baseline for determining the City’s current mitigation goals and objectives. Results from the Community Survey, Disaster Preparedness and Mitigation Questionnaire were also shared during the meeting to better inform the steering committee members of community priorities that resulted in 105 total responses.
Planning Workshop, Meeting #3 – Hazard Risk Rank Review, Mitigation Action Identification
Date: June 14, 2023
The Steering Committee determined the hazard profile ranking through a facilitated workshop where the information gathered was analyzed to assess risk and vulnerability of people, property, the environment, and its own operations from these hazards.
Chapter 3: Risk Assessment outlines the methodology used for hazard rankings.
Additionally, all Steering Committee participants were requested to provide existing plans
City of Downey Hazard Mitigation Plan 1-11
and technical studies, GIS data, and identify existing mitigation features as part of a detailed information request.
The meeting also identified potential mitigation actions and projects that will reduce the impact of identified hazards. First, the mitigation goals and objectives from Steering Committee Meeting #2 were reviewed and validated. Then, during the workshop, the Steering Committee participants brainstormed possible projects and actions to mitigate the effects of the identified hazards.
1.2.4 Public Meetings & Outreach
The public was invited to attend one of two (May 16, 2023, and May 22, 2023) public meetings to review the risk assessment results and discuss mitigation strategies. The public meetings were advertised locally in advance. See Appendix B – Stakeholder Engagement section B.1.1 Public Meetings for details.
On October 3, 2023, the City posted an advertisement on the City’s website inviting the public to participate in a comprehensive public survey that resulted in 105 total responses.
The survey assessed the community’s level of concern with various hazards and the steps each respondent had taken to prepare for a disaster. The results from the disaster preparedness and mitigation survey were integrated into the overall assessment to include the categories of social vulnerability and community resilience. See Appendix B – Stakeholder Engagement section B.5 Public Survey for complete survey responses to all thirty-two questions.
The City actively solicited public involvement through several advertisements and various social media platforms. See Appendix B – Stakeholder Engagement for social media screengrabs of Instagram and Facebook posts during the public survey period in section B.5.1 Social Media.
Members of the public were also able to provide direct input to the Hazard Mitigation Plan during the drafting stage and provide comments. The draft Hazard Mitigation Plan was initially provided on the City website for two weeks to allow the public to review the document and provide comments. The public comment period was held from October 3 through October 17, 2023. Another opportunity for the public to review the draft of the plan was made available again from July 15, 2024, to September 15, 2024. The second public comment and review period coincided with a major public event on July 24, 2024, to promote the hazard mitigation plan and invite residents to provide feedback. The July 24, 2024, public event was held in conjunction with the City of Downey’s Concert Under the
City of Downey Hazard Mitigation Plan 1-12
Stars. The City had a booth at the event and was available to discuss the plan, talk about emergency preparedness and mitigation, and was available to discuss how residents could be more resilient to the various hazards that could affect the City. The City announced to the 1,700 residents that attended the concert to learn about hazard mitigation and to visit the booth to review the plan. The July 24th concert (Las Catrinas- Mariachi) was selected to specifically reach out to the Hispanic population in the City, which is an important underserved demographic for the community. The concert also offered residents age 65 and over or with a disability to request a ride to the concert. City staff were on-hand to provide Spanish translation. Approximately 1,700 residents attended the event. Over 100 residents engaged with staff at the booth.
On September 12, 2024, the Downey Resilience Council participated in a draft review meeting for the hazard mitigation plan. A draft of the plan was presented, and members of the council were given an opportunity to provide feedback and recommended changes to the plan. The following organizations are part of the Downey Resilience Council and were invited to be part of the meeting. More information about the meeting can be found in Appendix B – Stakeholder Engagement.
Table 1.4: Downey Resilience Council Meeting – September 12, 2024 Organization Invited to Attend Attended Hazard Mitigation Meeting
American Red Cross Yes Yes
Area E Disaster Management Area
Coordinator Yes -
Chamber of Commerce Yes Yes
City of Norwalk Yes Yes
City of Paramount Yes -
Downey Adult School Yes -
Downey Amateur Radio Club Yes Yes
Downey City Management Yes Yes
Downey Emergency Management Yes Yes
Downey Police Yes -
Downey Unified School District Yes -
Kaiser- Downey Yes Yes
LA County Public Health Yes -
Los Angeles County Office of
Education Yes Yes
PIH Health- Downey Yes Yes
Rancho Los Amigos National
Rehabilitation Center Yes Yes
Southeast Area Animal Control
Authority (SEACCA) Yes Yes
SoCal Gas Yes Yes
The Arc Los Angeles and Orange
Co. Yes Yes
City of Downey Hazard Mitigation Plan 1-13
A City of Downey Hazard Mitigation Plan Community Stakeholder Webinar was conducted on September 19, 2024. The webinar was for key community stakeholders to provide input into the planning process, review key elements of the draft plan, and to invite them to be part of the annual maintenance process in subsequent years. The following organizations were represented in the webinar. More information about the webinar can be found in Appendix B – Stakeholder Engagement.
Table 1.5: Community Stakeholder Webinar – September 19, 2024 Community
Organization Target Audience
Arc of Los Angeles &
Orange Counties
Individuals with intellectual and developmental disabilities Downey Chamber of
Commerce
Business community
PTA HELPS Underserved families whose children attend Downy schools City of Downey Downey Residents
Downey A.C.E.R.T. City of Downey Advanced CERT (ACERT) Program. These volunteers are held to specific training and credentialing standards, must pass a City of Downey background check, and are authorized to assist the City in a variety of disaster preparedness, response, and recovery functions as affiliated disaster volunteers.
Downey Cemetery
District
Community Organization
Rotary Club of
Downey
Nonprofit Community Business Organization
BSA Scouting Troop
2 Community Youth Organization
General comments were received by the Community Development Department via email to Rakdy Khlok, Emergency Manager for the City. More information about public participation during the Hazard Mitigation Plan update can be found in Appendix B – Stakeholder Engagement.
1.3 Review and Incorporation of Existing Plans
While developing the City’s Hazard Mitigation Plan, the Project Team reviewed existing plans (detailed below) and incorporated relevant information into the planning efforts.
City of Downey 2018 Hazard Mitigation Plan
The City of Downey 2018 Hazard Mitigation Plan was crucial in comparing the previous mitigation ideas and attitudes to the City’s current needs and concerns. The project team referred to this plan constantly throughout the updating process. The Natural Hazards Mitigation Plan provides insight into hazard ranking, hazard history, and previously proposed mitigation projects.
City of Downey Hazard Mitigation Plan 1-14
Downey Vision 2025
The City’s “General Plan Vision 2025,” contains guidelines and policies that serve as the City’s vision for future planning and development. Mitigation projects defined in the Hazard Mitigation Plan will be required to align with the objectives outlined in the Safety Element of the General Plan. Proposed mitigation actions are found in Chapter 4 of this document.
City of Downey Urban Water Management Plan (UWMP) 2020
The City of Downey 2020 UWMP is updated every five years to monitor water supply issues and mitigate drought situations. As part of Urban Water Management Plan updates, the City will review the drought hazard profile in the Hazard Mitigation Plan and incorporate the drought mitigation actions identified in the plan.
City of Downey Emergency Operations Plan
The City of Downey periodically updates the Emergency Operations Plan (EOP). The multi-hazard EOP includes specific response procedures for many hazard scenarios that might affect the City. In order to ensure the plan includes an appropriate response, the City will incorporate the Risk Assessment element of the Hazard Mitigation Plan into the EOP update, as appropriate.
The California State Hazard Mitigation Plan (SHMP) 2018 The SHMP was reviewed to ensure consistency between the State and City Plan, with respect to identified hazards and vulnerability, goals and objectives, and mitigation actions. The State goals served as the basis for developing the goals at the City level. City goals and objectives are outlined in Chapter 4.
County of Los Angeles All-Hazards Mitigation Plan 2020
The County of Los Angeles All-Hazard Mitigation Plan was reviewed to ensure consistency between the County and City Plan. The County Plan, updated in 2020, outlines the County’s approach to hazard mitigation, focusing on natural hazards, human- caused events, and technological emergencies.
California Earthquake Loss Reduction Plan
California’s Seismic Safety Commission developed the Earthquake Loss Reduction Plan to identify actions to mitigate seismic hazards. This plan was reviewed for an overall seismic hazard evaluation for the Risk Assessment found in Chapter 3, as well as the identification of potential seismic mitigation actions.
City of Downey Hazard Mitigation Plan 1-15
California Water Plan 2018
The state updated the California Water Plan in 2018 in order to address drought hazard mitigation over the long term. This Plan outlines the state’s approach to integrated water management and sustainability. This information was used when developing the drought hazard profile.
California Adaptation Planning Guide 2020
FEMA, the California Governor’s Office of Emergency Services (Cal OES), and the California Natural Resources Agency developed the California Adaptation Planning Guide to assist municipalities in recognizing local climate change and to provide guidance addressing potential vulnerabilities. The information was used to develop potential hazards and to provide background information that allowed the Steering Committee to make educated decisions regarding mitigation actions designed to alleviate the effects of climate change.
City of Downey Hazard Mitigation Plan 2-i
PLANNING AREA PROFILE
Table of Contents
2.1 City Description ................................................................................................... 1
2.2 Development Trends ........................................................................................... 4
2.3 Population ......................................................................................................... 11
2.4 National Flood Insurance Program .................................................................... 14
List of Tables
Table 2. 1:Land Use Designations ................................................................................... 7 Table 2. 2: Projected Growth for the City of Downey ..................................................... 11 Table 2. 3: Evolution of Ethnic Composition .................................................................. 12 Table 2. 4- Percent of Households by Household Income for 2021 ............................... 13 Table 2. 5: NFIP Participation ........................................................................................ 14 Table 2. 6: Floodplain Manager in the City of Downey ................................................... 14
List of Figures
Figure 2. 1: City of Downey Profile Map .......................................................................... 3 Figure 2. 2: City of Downey General Plan Zoning Map .................................................... 9 Figure 2. 3: City of Downey Land Use Map ................................................................... 10
City of Downey Hazard Mitigation Plan 2-1
2.1 City Description
The City of Downey (City) is a municipality characterized by a combination of residential, industrial, and commercial developments. The City is located in the southeastern part of Los Angeles County, California, about 13 miles southeast of the City of Los Angeles. The City is bordered by the cities of South Gate and Paramount to the west; Bell Gardens, Commerce, and Pico Rivera to the north; Santa Fe Springs and Norwalk to the east, and Bellflower to the south. The City is located near three major Los Angeles County freeways, including Interstates 5, 605 and 105. Additionally, the City is in close proximity to Los Angeles International Airport, Hollywood Burbank Airport, the ports of Los Angeles and Long Beach, and is about 19 miles east of the Pacific Ocean.
According to the 2020 U.S. Census Bureau the City has a total area of 12.41 square miles.1 Elevations in the City range from a high of 145 feet in the northern region of the City to a low of 85 feet in the southern region, with an average elevation of 117 feet as stated in the City’s Emergency Operations Plan. The terrain of the City is primarily flat, without any major geographical features.
The climate is consistent with coastal Southern California and is generally characterized by warm summers and cool winters. Average temperatures range from the low-80’s in the summer to the high-40’s in the winter.2 Precipitation occurs mainly in the winter months with an average annual rainfall of approximately 17 inches.3 In 2020, NOAA’s Fullerton Municipal Airport Weather Station, the nearest weather station to the City, recorded February as the wettest month for the region with 3.02 inches of rainfall.4 According to the City’s website, the City began as a 96-acre parcel segmented from Rancho Santa Gertrudes in 1873. The new community was named “Downey City” after John Gatley Downey; a California governor who built the economic foundation of southern
1 United State Census Bureau. (2020). QuickFacts: Downey City, California. Retrieved from https://www.census.gov/quickfacts/downeycitycalifornia
2 Weather Spark. (2023). Climate and average weather year round in Downey. Retrieved from https://weatherspark.com/y/1624/Average-Weather-in-Downey-California-United-States-Year- Round#Figures-Temperature
3 Weather and Climate. (2023). Average monthly snow and rainfall in Downey (California) in inches.
Retrieved from Average monthly rainfall and snow in Downey (California), the United States of America (inches) (weather-and-climate.com)
4 National Oceanic and Atmospheric Administration. (2020). U.S. Climate Normals Quick Access. Retrieved from https://www.ncei.noaa.gov/access/us-climate-normals/#dataset=normals- monthly&timeframe=30&location=CA&station=USW00003166
City of Downey Hazard Mitigation Plan 2-2
California.5 With the expansion of the railroad system, the area continued to develop and by the beginning of the twentieth century had become a prominent agriculture and commercial leader in the area.
The City was incorporated on December 4, 1956, and experienced a period of rapid growth around that time. In 1940, the total population was 12,000, and by 1960 the population had surpassed 86,000.6 According to the 2023 estimates, the City has over 106,859 residents.7 The City has 12 parks, two public golf courses, a model city library, live theater, symphony orchestra, historical society and art museum.8 Figure 2.1, on the following page, provides an profile map of the City and demonstrate its location within Los Angeles County.
5 City of Downey. (2023). City History & Profile. Retrieved from https://www.downeyca.org/our-city/city-profile 6 City of Downey. (2023). City history & profile. Retrieved from https://www.downeyca.org/our-city/city-profile 7 World Population Review. (2023). Downey, California Population 2023 . Retrieved from https://worldpopulationreview.com/us-cities/downey-ca-population 8 CountyOffice.org. (2023). Golf courses in Downey, California. Retrieved from https://www.countyoffice.org/downey-ca-golf-course/
City of Downey Hazard Mitigation Plan 2-3
Figure 2. 1: City of Downey Profile Map
City of Downey Hazard Mitigation Plan 2-4
2.2 Development Trends
As mentioned in Section 2.1, the City has 12.41 square miles of land area. The Land Use Element of the City’s “General Plan Vision 2025” provides a guide for land use, future growth, and development within the City.
The following describes the City’s land use designations. These descriptions are excerpted from Downey’s General Plan Vision 2025 document that was adopted in January 2005 in an attempt to designate the proposed general distribution and intensity of uses of the land for housing, business, industry, open space, public facilities, and other categories of public and private uses.
The existing data is the most updated and readily available for use. Additional information has been provided by the Community Development Department in the City of Downey.
Residential Land Uses
Low Density Residential Development
This land use designation makes up 51% of the City’s overall land area.9 Typically, these areas contain detached, single-family residential units with a maximum approximate density of one housing unit per standard 5,000 square foot lot.10 The projected population for these areas is about 28 persons per acre. The City monitors population growth closely in these areas and has statutes in place to maintain a single-family image even as neighborhoods build out.
9 City of Downey. (2005). Vision 2025 general Plan Downey, California. Retrieved from https://www.downeyca.org/home/showpublisheddocument/134/636977201776000000 10 Ibid.
City of Downey Hazard Mitigation Plan 2-5
Low/ Medium Density Residential Development
This land use designation involves population densities of 9 to 17 housing units per acre or two housing units per a standard 5,000 square foot lot.11 Population projections for this type of land use ranges from 29 to 53 person per acre. Generally, lots in this category have two separate housing units sharing the same lot or two attached units (i.e. duplex, townhouses). This land use designation makes up 3% of the City’s overall land area.12.
Medium Density Residential Development
Making up 7% of the City land area, this residential designation involves densities of 18 to 24 housing units per acre or approximately 3 housing units per standard 6,000 square foot lot.13 Population projections, based on an average household size of 3.17 persons per unit, are estimated at a range of 57 to 76 person per acre.14 This land use is characterized by triplex properties, townhouses, condominiums, and apartment complexes.
Commercial Land Uses
Office - Commercial
Land use designated under this category is intended for professional and medical uses.
This land use category accounts for 3% of the overall land area of the City.15 Neighborhood Commercial
Neighborhood commercial land use applies to a range of commercial establishments whose customer base is drawn from the immediate surrounding neighborhood. Examples of businesses that belong under this category include grocery stores, barber shops, dry cleaners, and convenience markets. This classification accounts for 2% of the overall land area of the City.16
11 Ibid,
12 City of Downey. (2005). Vision 2025 general plan Downey, California. Retrieved from https://www.downeyca.org/home/showpublisheddocument/134/636977201776000000 13 City of Downey. (2005). Vision 2025 general plan Downey, California. Retrieved from https://www.downeyca.org/home/showpublisheddocument/134/636977201776000000 14 Ibid.
15 Ibid.
16 Ibid.
City of Downey Hazard Mitigation Plan 2-6
General Commercial
Making up 6% of the overall land use, the general commercial designation permits a full range of commercial uses.17 In contrast to the neighborhood commercial designations, uses in this category can be larger commercial establishments such as hotels, offices, and automotive repair businesses.
Manufacturing Land Uses
General Manufacturing
This classification includes manufacturing, wholesaling, and other industrial land uses.
Generally, the City attempts to separate this type of land use from others because businesses in this classification have the potential for creating traffic, noise, odor, vibration, and other undesirable impacts on the surrounding community. General Manufacturing makes up 4% of the overall City land area. 18 Commercial Manufacturing
The Commercial Manufacturing designation includes larger business establishments and is intended to provide areas for businesses that generate a great deal of employment opportunities. Some example uses of this land designation are shopping centers, large offices, and light industrial uses. This designation accounts for 5% of the City’s overall land area.19
Other Land Uses
Open Space
Approximately 106 acres of public parks make up the open space land designation.20 Areas under this category are intended to give the community places that provide relief from the built environment. In addition to park areas, the open space designation includes utility easements, riverbeds, parks, cemeteries, and golf courses. This designation accounts for 8% of the City’s total land area. 21
17 Ibid.
18 City of Downey. (2005). Vision 2025 general plan Downey, California. Retrieved from https://www.downeyca.org/home/showpublisheddocument/134/636977201776000000 19 Ibid.
20 Ibid.
21 Ibid.
City of Downey Hazard Mitigation Plan 2-7
Schools
Making up 6% of the overall City land area, this designation is intended for public and private schools offering K through 12 instruction.22 The City has 13 public elementary schools, 4 public middles schools, 3 public high schools, and at least 3 private schools located within the City boundaries.
Public
This land designation includes areas that are intended for facilities that support community services which are owned by public agencies. Examples of uses in this category are the Civic Center, the City Public Works Yard, Rancho Los Amigos Medical Center, and Los Padrinos Juvenile Hall. This land designation makes up 2% of the City’s overall land use.23 Mixed Use
This land designation blends a combination of the residential, commercial, and public spaces for establishments whose functions are interconnected. This type of land area provides flexibility to the City and accounts for 5% of the City’s overall land use.24 Table 2.1 provides a summary of the land use designations described in the sections above.
Table 2. 1:Land Use Designations
Land Use Designation Area (acres) Percentage
Low Density Residential 3,188 51
Low/ Medium Density Residential 187 3
Medium Density Residential 414 7
Office Commercial 163 3
Neighborhood Commercial 103 2
General Commercial 372 6
General Manufacturing 229 4
Commercial Manufacturing 304 5
Open Space 516 8
Schools 348 6
Public 104 2
22 Ibid.
23 Ibid.
24 City of Downey. (2005). Vision 2025 general plan Downey, California. Retrieved from https://www.downeyca.org/home/showpublisheddocument/134/636977201776000000
City of Downey Hazard Mitigation Plan 2-8
Land Use Designation Area (acres) Percentage
Mixed Use 301 5
Total 6,229 ≈100
Figures 2.2 and 2.3 illustrate the City’s zoning and land use designations, respectively, and were extracted from the 2023 revision of the General Plan Vision 2025 plan. As mentioned above, the City’s designations have not changed since the previous planning period. Figures 2.2 and 2.3 are current and are still in use.
City of Downey Hazard Mitigation Plan 2-9
Figure 2. 2: City of Downey General Plan Zoning Map
City of Downey Hazard Mitigation Plan 2-10
Figure 2. 3: City of Downey Land Use Map
City of Downey Hazard Mitigation Plan 2-11
2.3 Population
Since 1940, the City’s population has increased from about 12,000 residents to over 106,859 in 2023.25 Between 2020 and 2022, the population of Downey decreased approximately -3.9%.26 Conversely, future population growth is expected to grow slowly as development opportunities become increasingly limited and the City reaches its potential for building out.
Table 2.2 provides the City’s projected population growth through 2045. Population projections were estimated by calculating the average growth rate of 0.9% and 5.6%.27 Census data for those years was acquired through the Southern California Association of Governments (SCAG).28 Table 2.3 provides the census data used and population estimations.
Table 2. 2: Projected Growth for the City of Downey
Year 2010 2020 2045 % Change
2010 – 2020
% Change
2020 – 2045
Population 111,922 112,901 199,200 0.9% 5.6%
Demographics
The City’s population is a dynamic group representing people from many walks of life.
While many factors could influence the public’s opinion of the City’s emergency preparedness culture, the following subsections will focus on age, ethnicity, and income levels as well as the changes observed by the City for each of these categories.
25 World Population Review. (2023). Downey, California Population 2023. Retrieved from https://worldpopulationreview.com/us-cities/downey-ca-population 26 United Census Bureau. (2022). QuickFacts: Downey city, California. Retrieved from https://www.census.gov/quickfacts/fact/table/downeycitycalifornia/PST120222#PST120222 27 City of Downey. (2022) City of Downey 2021-2029 housing element. Retrieved from https://www.downeyca.org/home/showpublisheddocument/7275/638127636738570000 28 City of Downey. (2022) City of Downey 2021-2029 housing element. Retrieved from https://www.downeyca.org/home/showpublisheddocument/7275/638127636738570000
City of Downey Hazard Mitigation Plan 2-12
Population Age
According to the 2019 city profile developed by the Southern California Association of Governments (SCAG), the City experienced a significant increase in the 55-64 year age group.29 Growing from 7.2% of the population in the year 2000 to 11.2% in 2018; this group experienced the largest increase during the study period.30 Conversely, the 5-20 years age group decreased from 25.4% to 20.7% during the same timeframe. During this period, the largest group was the 35-54 years age group representing more than 25% of the City’s population.31 In 2020, the largest age group consisted of 20- to 44-year-old at approximately 37.1%, followed by the 0 to 19 age group at 26.7%32 Ethnicity
In the same study, it was reported that those identifying as Hispanic or Latino of any race increased from 57.9% to 74.0 % of the population during the 2000 to 2018 study period.33 This group represented the largest increase and the largest ethnicity group in the City. All other identified ethnicity groups experienced a decrease in percentage. The table below demonstrates the change in composition for each identified ethnic group from 2000 to 2018.
Table 2. 3: Evolution of Ethnic Composition
Ethnic Group
Year 2000 Population
Total Population 107,323
Year 2018
Total Population 114,146
Population Percentage Population Percentage
Hispanic/Latino 62,140 57.9 84,468 74.0
Non-Hispanic White 30,802 28.7 15,752 13.8
Non-Hispanic Asian 8,157 7.6 8,104 7.1
Non-Hispanic Black 3,756 3.5 3,881 3.4
Other 2,468 2.3 1,826 1.6
29 Southern California Association of Governments (SCAG). (2019). Profile of the City of Downey. Retrieved from https://scag.ca.gov/sites/main/files/file-attachments/downey_localprofile.pdf?1605664387 30 Ibid.
31 Ibid.
32 City of Downey. (2022) City of Downey 2021-2029 housing element. Retrieved from https://www.downeyca.org/home/showpublisheddocument/7275/638127636738570000 33 Ibid.
City of Downey Hazard Mitigation Plan 2-13
Household Income
The City’s median annual household income from 2017- 2021 was $77,972 according to the United States Census Bureau.34 As of 2021, 35% of households earned less than $13.5% annually while 17.8% of households earned $100,000 or more.35 According to City of Downey, 9.9 percent of residents live in poverty, as defined by federal guidelines.36 Table 2.4 demonstrates the percent of households by income for 2021.
Table 2. 4- Percent of Households by Household Income for 2021 Income Range Percentage
Less than $10,000 3.3
$10,000 to $14,999 2.0
$15,000 to $24,999 5.4
$25,000 to $34,999 6.2
$35,000 to $49,999 13.5
$50,000 to $74,999 17.4
$75,000 to $99,999 16.4
$100,000 to $149,999 17.8
$150,000 to $199,999 9.2
$200,000 or more 8.9
34 United Census Bureau. (2021). QuickFacts: Downey city, California. Retrieved from https://integratedsolutionscorp.sharepoint.com/sites/DowneyHMP/Shared%20Documents/Technical/HMP%2 0(Prior,%20Current)/HMP%202023%20Draft%20Files/AppendixA_RASupportDoc.FINAL.pdf 35 United Census Bureau. (2021).Income in the past 12 months (in 2021 inflation-adjusted). Retrieved from 36 City of Downey. (2022) City of Downey 2021-2029 housing element. Retrieved from https://data.census.gov/table?g=160XX00US0619766&tid=ACSST5Y2021.S1901https://www.downeyca.org /home/showpublisheddocument/7275/638127636738570000
City of Downey Hazard Mitigation Plan 2-14
2.4 National Flood Insurance Program
The National Flood Insurance Program (NFIP) is a federal program enabling property owners in participating communities to purchase insurance as a protection against flood losses in exchange for State and community floodplain management regulations that reduce future flood damages. Participation in the NFIP is based on an agreement between communities and the Federal Government. If a community adopts and enforces a floodplain management ordinance to reduce future flood risk to new construction in floodplains, the Federal Government will make flood insurance available within the community as a financial protection against flood losses. This insurance is designed to provide an alternative to disaster assistance and reduce the escalating costs of repairing damage to buildings and their contents caused by floods. The table below summarizes the City of Downey’s participation in the program.
Table 2. 5: NFIP Participation
CID Community
Name County Init. FHBM
Identified
Init. FIRM
Identified
Curr. Eff.
Map Date
Reg-Emer.
Date
060645 City of
Downey Los Angeles 07/19/74 09/26/08 (NSFHA) 09/07/84
Note: Non-Special Flood Hazard Area (NSFHA)
Each NFIP participating community has a designated Floodplain Manager/coordinator that is charged with enforcing floodplain regulations, routinely monitoring the floodplains, and providing community assistance such as encouraging owners to maintain flood insurance.
Table 2. 6: Floodplain Manager37 in the City of Downey
Name Title Phone Number
Roger Bradley City Manager 562.299-6603
As part of the City of Downey’s continued compliance with NFIP, the Downey Municipal Code includes Chapter 8 Floodplain Management, Grading and Paving. This is designed to promote public health, safety, and general welfare as well as minimize public and private losses due to flood conditions in flood-prone areas. The ordinance outlines several methods for reducing flood losses including controlling activities which increase
37 California Department of Water Resources (2023). Data provided by Division of Regional Assistance- Southern Region Office.
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vulnerability to erosion hazards, mitigation flood damage for new buildings during the construction stage, controlling any activity of diversions of flood paths, and controls for filling; grading; or and dredging.
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RISK ASSESSMENT
Table of Contents
3.1 Hazard Identification & Risk Assessment ........................................................ 1
3.2 FEMA National Risk Index ................................................................................. 9
3.3 Total Risk Scores ............................................................................................. 15
3.4 Hazard Profiles & Description ......................................................................... 17
3.5 Acts/Threats of Mass Violence ....................................................................... 18
3.6 Civil Unrest Hazard Profile .............................................................................. 24
3.7 Cyber Incident Hazard Profile ......................................................................... 29
3.8 Dam Failure Hazard Profile ............................................................................. 35
3.9 Drought Hazard Profile .................................................................................... 47
3.10 Earthquake Hazard Profile .............................................................................. 63
3.11 Hazardous Materials Release Hazard Profile ................................................. 96
3.12 Pandemic Hazard Profile ............................................................................... 114
3.13 Severe Weather/ Storm Hazard Profile ......................................................... 121
3.14 Tornado Hazard Profile ................................................................................. 138
3.15 Mass Transportation Accident/ Incident Hazard Profile ............................. 149
3.16 Urban Fires Hazard Profile ............................................................................ 156
3.17 Urban Flood Hazard Profile ........................................................................... 162
3.18 Utility Loss Hazard Profile ............................................................................ 183
3.19 Wildfire Smoke/Air Quality Hazard Profile ................................................... 187
3.20 Windstorm Hazard Profile ............................................................................. 203
3.21 Climate Change ............................................................................................. 216
List of Figures
Figure 3.1: Total Risk Score Formula ........................................................................................... 2 Figure 3.2: Domestic Terrorism Incidents by State 2010-2021 ................................................ 21 Figure 3.3: Black Lives Matter Protest in Los Angeles ............................................................ 26 Figure 3.4: Causes of Dam Failure ............................................................................................. 38
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Figure 3.5: Potential Impacting High Hazard Dams Outside the City of Downey .................. 42 Figure 3.6: Whittier Narrows Dam Inundation Area and Impact to the City of Downey ........ 43 Figure 3.7: Whittier Narrows Dam Scenarios ............................................................................ 44 Figure 3.8: Aerial View of the Whittier Narrows Dam................................................................ 45 Figure 3.9: Monthly Runoff in California by Years .................................................................... 49 Figure 3.10: Annual Runoff in California .................................................................................... 50 Figure 3.11: California Precipitation (09/07/2023) ..................................................................... 51 Figure 3.12: California Precipitation Statistics (1981-2023) ..................................................... 52 Figure 3.13: U.S. Palmer Drought Index Map (August 2023) .................................................... 54 Figure 3.14: U.S. Drought Monitor for California ....................................................................... 56 Figure 3.15: Southern California Historic Earthquakes Map ................................................... 76 Figure 3.16: Ground Acceleration Map (as of April 2023) ........................................................ 82 Figure 3.17: USGS National Seismic Hazard Map ..................................................................... 88 Figure 3.18: Map of Toxic Release Inventory Facilities in the City of Downey ...................... 99 Figure 3.19: Hazmat Road Review Critical Assets .................................................................. 104 Figure 3.20: Hazmat Rail Review Critical Assets .................................................................... 107 Figure 3.21: City of Downey Natural Gas Transmission Pipeline Map ................................. 111 Figure 3.22: City of Downey Natural Gas Transmission/ Supply Pipeline Map ................... 112 Figure 3.23: Nations with Confirmed Cases H1N1 (August 4, 2009) ..................................... 118 Figure 3.24: Active West Nile Virus Cases as of May 12, 2023 .............................................. 119 Figure 3.25: SPC Severe Thunderstorm Outlook Categories ................................................ 126 Figure 3.26: City of Downey Average Monthly Temperature ................................................. 128 Figure 3.27: City of Downey Average Monthly Precipitation with Daily Maximum .............. 129 Figure 3.28: EF1 Tornado rips off Roof of a building in Montebello, March 22, 2023 ......... 140 Figure 3.29: City of Downey Transportation Routes Map ...................................................... 154 Figure 3.30: City of Downey Truck Routes Map ...................................................................... 155 Figure 3.31: Fire Deaths per Million Population, US vs. California ....................................... 158
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Figure 3.32: Repetitive loss & Severe Repetitive loss Summary .......................................... 168 Figure 3.33: Insurance Occupancy ........................................................................................... 168 Figure 3.34: City of Downey FEMA Insurance Rate Map (FIRM) ............................................ 170 Figure 3.35: City of Downey 100-year Flood Study ................................................................. 171 Figure 3.36: City of Downey 500-year Flood Study ................................................................. 172 Figure 3.37: Air Quality in and around Downey ...................................................................... 195 Figure 3.38: Downey AQI (September 8 – September 11, 2023) ............................................ 196 Figure 3.39: Corsi-Rosenthal Box ............................................................................................. 197 Figure 3.40: City of Downey Historic Wind Event ................................................................... 207 Figure 3.41: City of Downey Average Wind Speeds ............................................................... 210 List of Tables
Table 3.1: Overall FEMA National Risk Index for the City of Downey Planning Area ........... 10 Table 3.2: Expected Annual Loss for the City of Downey Planning Area............................... 11 Table 3.3: Social Vulnerability for the City of Downey Planning Area .................................... 12 Table 3.4: Community Resilience for the City of Downey Planning Area .............................. 14 Table 3.5: 2023 Hazard Risk Scores for the City of Downey .................................................... 15 Table 3.6: Acts/Threats of Mass Violence Total Risk Score .................................................... 18 Table 3.7: Civil Unrest Total Risk Score ..................................................................................... 24 Table 3.8: Cyber Incident Total Risk Score ................................................................................ 29 Table 3.9: CISA National Cyber Incident Scoring System ........................................................ 32 Table 3.10: Dam Failure Total Risk Score .................................................................................. 35 Table 3.11: Historical California Dam Failures .......................................................................... 39 Table 3.12: Potential Impacting Dams Outside the City of Downey ........................................ 41 Table 3.13: Whittier Narrows Dam Consequence Estimate ..................................................... 45 Table 3.14: Drought Total Risk Score ......................................................................................... 47 Table 3.15: Types of Drought ...................................................................................................... 48
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Table 3.16: Palmer Drought Severity Index ............................................................................... 54 Table 3.17: U.S. Drought Monitor Classification ....................................................................... 55 Table 3.18: Drought Annualized Frequency (FEMA National Risk Index) .............................. 57 Table 3.19: Vulnerability and At-Risk Populations: Drought ................................................... 59 Table 3.20: Assets/Structures Vulnerability and Impact Summary: Drought ........................ 59 Table 3.21: Earthquake Total Risk Score ................................................................................... 63 Table 3.22: Southern California Historical Earthquakes .......................................................... 67 Table 3.23: San Andreas Fault Information ............................................................................... 77 Table 3.24: Newport-Inglewood Fault Information .................................................................... 78 Table 3.25: Whittier Fault Information ........................................................................................ 79 Table 3.26: Elsinore Fault Information ....................................................................................... 79 Table 3.27: Palos Verdes Fault Information ............................................................................... 80 Table 3.28: Mercalli Intensity vs. Richter Scale ......................................................................... 83 Table 3.29: Earthquake Warning California Alerting Thresholds ............................................ 84 Table 3.30: HAZUS Earthquake Expected Building Damage by Occupancy ......................... 85 Table 3.31: HAZUS Earthquake Expected Damage to Essential Facilities ............................. 86 Table 3.32: Earthquake Annualized Frequency (FEMA National Risk Index) ......................... 88 Table 3.33: Vulnerability and At-Risk Populations: Earthquake .............................................. 90 Table 3.34: Property Vulnerability to Earthquake ..................................................................... 92 Table 3.35: Assets/Structures Vulnerability and Impact Summary: Earthquake ................... 92 Table 3.36: Earthquake Expected Annual Loss ......................................................................... 94 Table 3.37: Hazardous Materials Release Total Risk Score ..................................................... 96 Table 3.38: US Department of Transportation Hazard Classification System ....................... 97 Table 3.39: Types of Hazardous Material Incidents ................................................................ 100 Table 3.40: Critical Assets within Road Impact Zone ............................................................. 101 Table 3.41: Critical Assets Within Rail Impact Zone ............................................................... 105 Table 3.42: Pandemic Total Risk Score .................................................................................... 114
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Table 3.43: Severe Weather/Storm Total Risk Score .............................................................. 121 Table 3.44: Hail Speed Estimates.............................................................................................. 122 Table 3.45: Historical Severe Weather Damage in Los Angeles County .............................. 123 Table 3.46: NWS Severe Weather Advisories .......................................................................... 126 Table 3.47: Converting Traditional Hail Size Descriptions ..................................................... 127 Table 3.48: Atmospheric River Scale........................................................................................ 128 Table 3.49: Hail Annualized Frequency (FEMA National Risk Index) .................................... 129 Table 3.50: Lightning Annualized Frequency (FEMA National Risk Index) .......................... 130 Table 3.51: Vulnerability and At-Risk Populations: Severe Weather/Storm ......................... 132 Table 3.52: Property Vulnerability: Severe Weather/Storm .................................................... 133 Table 3.53: Assets/Structures Vulnerability and Impact Summary: Severe Weather/Storm ………………………………………………………………………………………………133
Table 3.54: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates:
Severe Weather/Storm ....................................................................................................... 133 Table 3.55: Hail Expected Annual Loss .................................................................................... 135 Table 3.56: Lightning Expected Annual Loss .......................................................................... 136 Table 3.57: Tornado Total Risk Score ...................................................................................... 138 Table 3.58: Types of Tornadoes ................................................................................................ 139 Table 3.59: National Weather Service Tornado Advisories .................................................... 139 Table 3.60: NCEI Tornado Events in Los Angeles County (2018 - 2023) .............................. 141 Table 3.61: Enhance Fujita Scale .............................................................................................. 142 Table 3.62: NWS Severe Weather Advisories .......................................................................... 142 Table 3.63: Vulnerability and At-Risk Populations: Tornado ................................................. 144 Table 3.64: Property Vulnerability: Tornado ............................................................................ 145 Table 3.65: Assets/Structures Vulnerability and Impact Summary: Tornado ...................... 145 Table 3.66: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates:
Tornado ............................................................................................................................... 146
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Table 3.67: Tornado Expected Annual Loss for the City of Downey Planning Area ........... 147 Table 3.68: Mass Transportation Accident/Incident Total Risk Score .................................. 149 Table 3.69: Fatal Airborne Incidents within 50 Miles of the City of Downey (2017-2023) ... 151 Table 3.70: Urban Fires Total Risk Score ................................................................................. 156 Table 3.71: Urban Fires Losses and Financial Damages ....................................................... 159 Table 3.72: Urban Flood Total Risk Score ............................................................................... 162 Table 3.73: Flood Events in Los Angeles County (2017 - 2023) ............................................ 165 Table 3.74: HAZUS 100-Year Flood Expected Building Damage by Occupancy ................. 173 Table 3.75: HAZUS 100-Year Flood Expected Damage to Essential Facilities ..................... 174 Table 3.76: HAZUS 500-Year Flood Expected Building Damage by Occupancy ................. 175 Table 3.77: HAZUS 500-Year Flood Expected Damage to Essential Facilities ..................... 175 Table 3.78: Riverine Flooding Annualized Frequency (FEMA National Risk Index) ............ 176 Table 3.79: Vulnerability and At-Risk Populations in 500-year Flood Zone ......................... 177 Table 3.80: Assets/Structures Vulnerability and Impact Summary: 100-year and 500-year Flood per FEMA Flood Zone areas .................................................................................. 179 Table 3.81: Riverine Flood Expected Annual Loss ................................................................. 181 Table 3.82: Utility Loss Total Risk Score ................................................................................. 183 Table 3.83: PSPS Greater than 6 or More Days (2017-2023) .................................................. 185 Table 3.84: Wildfire Smoke/Air Quality Total Risk Score ....................................................... 187 Table 3.85: Wildfire Smoke Event Pollutants ........................................................................... 188 Table 3.86: Los Angeles County Annual Air Quality............................................................... 190 Table 3.87: Air Quality Index – Basics for Ozone & Particle Pollution.................................. 194 Table 3.88: National Weather Service Fire Advisories ........................................................... 195 Table 3.89: Wildfire Annualized Frequency (FEMA National Risk Index) ............................. 198 Table 3.90: Vulnerability and At-Risk Populations: Wildfire/Smoke ..................................... 200 Table 3.91: Assets/Structures Vulnerability and Impact Summary: Wildfire/Smoke .......... 200 Table 3.92: Wildfire Expected Annual Loss Estimates ........................................................... 201
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Table 3.93: Windstorm Total Risk Score .................................................................................. 203 Table 3.94: Types of Strong Winds ........................................................................................... 204 Table 3.95: Strong Wind Events for Los Angeles (2000-2023) ............................................... 205 Table 3.96: Major Windstorms in the Vicinity of the City of Downey .................................... 205 Table 3.97: Beaufort Wind Scale ............................................................................................... 208 Table 3.98: Strong Wind Annualized Frequency (FEMA National Risk Index) ..................... 210 Table 3.99: Vulnerability and At-Risk Populations: Strong Winds ........................................ 211 Table 3.100: Property Vulnerability: Strong Winds ................................................................. 212 Table 3.101: Assets/Structures Vulnerability and Impact Summary: Strong Winds ........... 213 Table 3.102: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates:
Strong Winds ...................................................................................................................... 213 Table 3.103: Strong Wind Expected Annual Loss ................................................................... 215
City of Downey Hazard Mitigation Plan 3-1
3.1 Hazard Identification & Risk Assessment
The Risk Assessment identifies the natural, technological, and human-caused hazards that have potential impacts on all or portions of the City. Hazard identification, historical occurrences, and risk modeling (where applicable and available for specific hazards) information was collected from multiple sources including but not limited to:
• Environmental Systems Research Institute (ESRI),
• Federal Emergency Management Agency (FEMA),
• National Centers for Environmental Information (NCEI), • National Fire Incident Reporting System (NFIRS),
• National Weather Service (NWS),
• United States Geological Survey (USGS),
• and local repositories.
This information was then analyzed to assess risk and vulnerability of people, property, the environment, and its own operations from these hazards. To that end, a risk ranking was performed for the hazards of concern described in this plan. The risk ranking is a key step in developing an action plan, as it allows the City to compare the risk factors of one hazard to another. That comparison provides critical information to use in selecting hazard mitigation actions and their priorities. This process is not only intended to help focus actions on the hazards with the highest rankings, but also to ensure the City does not forget about hazards that ranked low yet still pose significant risk.
In order to provide an informed and comprehensive ranking of the hazards addressed in this plan, several categories of factors were considered: extent, vulnerability impact and probability. The sum of all the weighted factors for the extent, vulnerability, and impact categories were combined into a final consequence score. Probability multiplied by consequence resulted in a total risk score for each hazard.
City of Downey Hazard Mitigation Plan 3-2
Figure 3. 1: Total Risk Score Formula
These results were determined by following a data-driven quantitative assessment, from reviewing and ranking local knowledge from local subject matter experts, to developing other risk elements by the Core Planning Team (the City and Integrated Solutions Consulting (ISC)) based on the data collected. These elements were then aggregated to inform the analysis.
At the fundamental level, consequence is an assessment of the potential impact(s) if the hazard incident actually occurs. In this assessment, the consequence of an event (or the impact) will be interdependent on the following factors: vulnerabilities (i.e. social, physical, and community conditions), capabilities and capacities, mitigation, and the characteristics (i.e. magnitude, scale, etc.) of the hazard event. Again, the frequency/probability of the hazard is not included in assessing the consequence because without the event, there is no consequence or impact.
3.1.1 Extent Factors
Extent was assessed in two sub-categories: hazard duration and intensity potential. Numerical impact factors were assigned as follows:
Duration—Duration is defined as the range of time that the hazard, its impact, and the following recovery could potentially be.
• High—The hazard, its impacts and the recovery could last for years (Extent Factor = 3) • Medium—The hazard, its impacts and the recovery could last for months (Extent Factor = 2)
• Low—The hazard, its impacts and the recovery could last for weeks (Extent Factor = 1) • Unlikely—The hazard, its impacts and the recovery could last for days at most (Extent Factor = 0)
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Intensity—The potential that an occurrence of this hazard could be catastrophic. Catastrophic incidents are those that cause extraordinary levels of mass casualties, damage, or disruption that could severely affect a jurisdiction’s operations, populations, economy, and/or morale.Historical studies, probabilistic models, and subject matter expertise all influence determinations of potential hazard intensity.
• High—High potential that this hazard could be catastrophic (Extent Factor = 3) • Medium—Medium potential that this hazard could be catastrophic (Extent Factor = 2) • Low—Low potential that this hazard could be catastrophic (Extent Factor = 1) • Unlikely—Virtually no potential that this hazard could be catastrophic (Extent Factor = 0) Each category was assigned a weighting factor to reflect its significance, consistent with those typically used for measuring the benefits of hazard mitigation actions: a weighting factor of 1 was assigned for Duration and a factor of 3 was assigned to Intensity.
3.1.2 Vulnerability Factors
Vulnerabilities were assessed in three sub-categories: population exposure, property exposure, and exposure based on changes in development. Numerical factors were assigned as follows:
People—Values were assigned based on the percentage of the total population exposed to the hazard event.
• High—25% or more of the population is exposed to, or could be impacted by, a single occurrence of the hazard (Vulnerability Factor = 3)
• Medium—6% to 24% of the population is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 2)
• Low—5% or less of the population is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 1)
• No Vulnerability—None of the population is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 0)
Property Exposed—Values were assigned based on the percentage of the total property value exposed to the hazard event.
• High—25% or more of the total assessed property value is exposed to, or could be impacted by, a single occurrence of the hazard (Vulnerability Factor = 3)
City of Downey Hazard Mitigation Plan 3-4
• Medium—6% to 24% of the total assessed property value is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 2) • Low—5% or less of the total assessed property value is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 1) • No Vulnerability—None of the total assessed property value is exposed to, or could be impacted by, a single occurrence of this hazard (Vulnerability Factor = 0) Changes in Development —Changes in development since the previous plan was approved have increased or decreased the community’s vulnerability/exposure to this hazard. • High—Changes in development have significantly increased the vulnerability/exposure of the community to this hazard (Vulnerability Factor = 3) • Medium—Changes in development have increased the vulnerability/exposure of the community to this hazard, but not significantly (Vulnerability Factor = 2) • Low—Changes in development have minimally increased the vulnerability/exposure of the community to this hazard (Vulnerability Factor = 1) • No Vulnerability—Changes in development have had no effect and/or have decreased the vulnerability/exposure of the community to this hazard (Vulnerability Factor = 0) Each category was assigned a weighting factor to reflect its significance, consistent with those typically used for measuring the benefits of hazard mitigation actions: a weighting factor of 3 was assigned for People, a factor of 2 Property Exposed, and 1 for Changes in Development.
3.1.3 Impact Factors
Hazard impacts were assessed in eight sub-categories: population and life/safety, underserved/equity, property damages, economy, own operations, future development, environment, and climate change. Numerical impact factors were assigned as follows:
Population and Life/Safety—Values were assigned based on 1.) subject matter expertise and/or best available data for populations vulnerable to the hazard event, and 2). whether affected populations are likely to experience adverse impacts from the hazard incident. • High—Populations exposed to this hazard are likely to experience significant adverse impacts (Impact Factor = 3)
City of Downey Hazard Mitigation Plan 3-5
• Medium—Populations exposed to this hazard are likely to experience some adverse impacts (Impact Factor = 2)
• Low—Populations exposed to this hazard are likely to experience minimal adverse impacts (Impact Factor = 1)
• No impact—Populations exposed to this hazard are not likely to experience significant adverse impacts (Impact Factor = 0) .....................................................................
Impact to Underserved/Equity—Values were 1). assigned based on subject matter expertise and/or best available data for underserved populations vulnerable to the hazard event, and 2). whether affected populations are likely to experience adverse/disproportionate impacts from the hazard incident resulting in greater disparity in equity. • High—Underserved populations exposed to this hazard are likely to experience significant adverse/disproportionate impacts (Impact Factor = 3)
• Medium—Underserved populations exposed to this hazard are likely to experience some adverse/disproportionate impacts (Impact Factor = 2)
• Low—Underserved populations exposed to this hazard are likely to experience minimal adverse/disproportionate impacts (Impact Factor = 1)
• No impact—Underserved populations exposed to this hazard are not likely to experience significant adverse/disproportionate impacts (Impact Factor = 0) Property Damage—Values were assigned based on the expected total property damages incurred from a hazard incident. It is important to note that values represent estimates of the loss from a major incident based on historical data or probabilistic models/studies. • High—More than $5,000,000 in property damages is expected from a single major hazard event, or damages are expected to occur to 15% or more of the property value within the jurisdiction (Impact Factor = 3)
• Medium—More than $500,000, but less than $5,000,000 in property damages is expected from a single major hazard event, or expected damages are expected to more than 5%, but less than 15% of the property value within the jurisdiction (Impact Factor = 2) • Low—Less than $500,000 in property damages is expected from a single major hazard event, or less than 5% of the property value within the jurisdiction (Impact Factor = 1) • No impact—Little to no property damage is expected from a single major hazard event (Impact Factor = 0)
City of Downey Hazard Mitigation Plan 3-6
Economy—An estimation of the impact, expressed in terms of dollars, on the local economy is based on a loss of business revenue, crops, worker wages and local tax revenues or on the impact on the local gross domestic product (GDP).
• High—Where the total economic impact is likely to be greater than $10 million (Impact Factor = 3)
• Medium—Total economic impact is likely to be greater than $100,000, but less than or equal to $10 million (Impact Factor = 2)
• Low—Total economic impact is not likely to be greater than $100,000 (Impact Factor = 1) • No Impact—Virtually no significant economic impact (Impact Factor = 0) Impact to Own Operations—An estimate of the impact on the ability of the affected jurisdiction to meet the essential day-to-day operational demands and needs of the community after a single major hazard event.
• High—Significant impact on the organization's own operations and/or the ability of the jurisdiction to meet the essential day-to-day operational demands and needs of the community from a single major hazard event (Impact Factor = 3) • Medium—Some impact on the organization's own operations and/or the ability of the jurisdiction to meet the essential day-to-day operational demands and needs of the community from a single major hazard event (Impact Factor = 2) • Low—Minimal impact on the organization's operations and/or the ability of the jurisdiction to meet the essential day-to-day operational demands and needs of the community from a single major hazard event (Impact Factor = 1)
• No Impact—No impact on the organization's operations and/or the ability of the jurisdiction to meet the essential day-to-day operational demands and needs of the community from a single major hazard event (Impact Factor = 0) Future Development—The potential that future development will have on increasing or decreasing the impact/consequence of this hazard.
• High—Future development trends will significantly increase the impact/consequence of this hazard (Impact Factor = 3)
• Medium—Future development trends will increase the impact/consequence of this hazard, but not significantly (Impact Factor = 2)
• Low—Future development trends will minimally increase impact/consequence of this hazard (Impact Factor = 1)
City of Downey Hazard Mitigation Plan 3-7
• No Impact—Future development trends will not increase the impact/consequence of this hazard, and/or may even decrease the impact/consequence of this hazard (Impact Factor= 0)
Environment—An estimate of the environmental impact from a single major hazard event requiring outside resources and support; and/or repair, clean-up, restoration, and/or preservation work.
• High—Environmental impact from a single major hazard event is likely to be significant, requiring extensive outside resources and support; and/or repair, clean-up, restoration, and/or preservation work that may take a year or longer to complete (Impact Factor = 3) • Medium— Environmental impact from a single major hazard event is likely to be localized, requiring some outside resources and support; and/or repair, clean-up, restoration, or preservation work that may take up to a month to complete (Impact Factor = 2) • Low—Environmental impact from a single major hazard event is likely to be minimal, requiring little to no outside resources and support; and/or minimal repair, clean-up, restoration, or preservation work that may take a week to complete (Impact Factor = 1) • No Impact—No environmental impacts from a single major hazard event are likely (Impact Factor = 0) .............................................................................................................
Climate Change—The potential that Climate Change will increase the risk of this hazard (i.e., type, location, and range of anticipated intensities of the identified hazard and impacts). • High—Climate Change trends will significantly increase the risk of this hazard and its impacts (Impact Factor = 3)
• Medium—Climate Change trends will increase the risk of this hazard and its impacts, but not significantly (Impact Factor = 2)
• Low—Climate Change trends will minimally increase the risk of this hazard and its impacts (Impact Factor = 1)
• No Impact—Climate Change trends will not increase the risk of this hazard and its impacts (Impact Factor = 0)
Each sub-category was assigned a weighting factor to reflect its significance, consistent with those typically used for measuring the benefits of hazard mitigation actions: a weighting of 3 was assigned for Population and Life/Safety and Underserved/Equity, and a weighting factor of 2 was assigned for Property Damages. A weighting factor of 1 was assigned for Economic, Own Operations, Future Development, Environment, and Climate Change.
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3.1.4 Probability of Occurrence Factors
The probability of occurrence of a hazard is indicated by a factor based on the likelihood of annual occurrence. The probability of occurrence factors used in the risk assessment calculations are:
• High—Significant hazard event is likely to occur annually (Probability Factor = 3) • Medium—Significant hazard event is likely to occur within 10 years (Probability Factor = 2)
• Low—Significant hazard event is likely to occur within 50 years (Probability Factor = 1) • Unlikely—There is little to no probability of significant occurrence, or the recurrence interval is greater than every 100 years (Probability Factor = 0) The assessment of hazard frequency is generally based on past hazard events in the area in conjunction with the professional judgement of local subject matter expects.
City of Downey Hazard Mitigation Plan 3-9
3.2 FEMA National Risk Index
The Federal Emergency Management Agency (FEMA) National Risk Index (NRI) is a dataset and online tool to help illustrate the United States communities most at risk communities for 18 natural hazards. These include:
• Avalanche
• Coastal Flooding
• Cold Wave
• Drought
• Earthquake
• Hail
• Heat Wave
• Hurricane
• Ice Storm
• Landslide
• Lightning
• Riverine Flooding
• Strong Wind
• Tornado
• Tsunami
• Volcanic Activity
• Wildfire
• Winter Weather
All the hazards on this list are not applicable to the City planning area; therefore, only those hazards with a defined risk to the City planning area will be included in this Plan. The NRI’s goal is to fill gaps in available data and analyses to better inform federal, state, local, tribal, and territorial decision makers as they develop risk reduction strategies.
The NRI leverages available source data for expected annual loss due to these 18 natural types of hazards, social vulnerability, and community resilience to develop a baseline relative risk measurement for each United States county and Census tract. These measurements are calculated using average past conditions, but they cannot be used to predict future outcomes for a community.
3.2.1 NRI Score
In the NRI, risk is defined as the potential for negative impacts as a result of a natural hazard.
The Risk Index is based on three (3) components – a natural hazards component (Expected Annual Loss), a consequence enhancing component (Social Vulnerability), and a consequence reduction component (Community Resilience). Using these components, the composite and hazard type Risk Index values are calculated for each community (county and
City of Downey Hazard Mitigation Plan 3-10
Census Tract). Risk Index values form an absolute basis for measuring Risk within the NRI and are used to generate Risk Index percentiles and ratings across communities.1 The table below illustrates the Risk Index rating and score for the City planning area (Census Tracts).
Table 3.1: Overall FEMA National Risk Index for the City of Downey Planning Area Census Tract Rating FEMA National Risk Index
Score
550501 Relatively Moderate 69.23
550502 Relatively Moderate 72.15
550601 Relatively Moderate 77.86
550602 Relatively Moderate 82.01
550700 Relatively High 89.37
550801 Relatively Moderate 84.16
550802 Relatively Moderate 69.37
550901 Very High 97.34
550902 Relatively High 86.23
551001 Relatively Moderate 82.72
551002 Relatively Moderate 70.66
551101 Very High 98.77
551102 Very High 98.57
551201 Relatively Moderate 83.37
551203 Relatively Moderate 67.48
551204 Relatively Moderate 73.89
551300 Very High 98.87
551401 Relatively Moderate 79.08
551402 Relatively High 85.35
551501 Relatively Moderate 83.96
551502 Relatively Moderate 77.06
551700 Relatively Moderate 77.53
551801 Relatively Moderate 82.52
551802 Relatively Moderate 81.18
553400 Relatively Moderate 68.27
980012 Relatively High 90.39
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience. (Expected Annual Loss X Social Vulnerability / Community Resilience = Risk Index).
1 Federal Emergency Management Agency. (2023). Determining Risk. Retrieved from https://hazards.fema.gov/nri/determining-risk .
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3.2.2 Expected Annual Loss
The Expected Annual Loss (EAL), the natural hazards component of the NRI, represents the average economic loss in dollars resulting from natural hazards each year. It is calculated for each hazard type and quantified loss for relevant consequence types such as, buildings, people, and agriculture. The EAL score and rating represents a community’s relative level of expected losses each year when compared to other communities at the same level. Since the score is associated to a community’s risk; the higher EAL score results in a higher Risk Index score.2The table below illustrates the EAL rating and score for the City planning area (Census Tracts).
Table 3.2: Expected Annual Loss for the City of Downey Planning Area Census Tract Rating FEMA National Risk Index Score
550501 Relatively Moderate 62.24
550502 Relatively Moderate 76.54
550601 Relatively Moderate 72.44
550602 Relatively Moderate 81.70
550700 Relatively High 86.06
550801 Relatively Moderate 83.57
550802 Relatively Moderate 64.90
550901 Relatively High 94.43
550902 Relatively Moderate 82.04
551001 Relatively Moderate 83.17
551002 Relatively Moderate 64.89
551101 Relatively High 96.96
551102 Relatively High 97.01
551201 Relatively Moderate 75.19
551203 Relatively Moderate 63.98
551204 Relatively Moderate 67.45
551300 Very High 97.66
551401 Relatively Moderate 68.60
551402 Relatively Moderate 77.95
551501 Relatively Moderate 79.26
551502 Relatively Moderate 73.78
2 Federal Emergency Management Agency. (2023). Expected Annual Loss. Retrieved from https://hazards.fema.gov/nri/expected-annual-loss .
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Census Tract Rating FEMA National Risk Index Score
551700 Relatively Moderate 72.26
551801 Relatively Moderate 83.14
551802 Relatively Moderate 75.49
553400 Relatively Low 58.95
980012 Relatively High 85.68
Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios.
(Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio).
An EAL score and rating is calculated independently for each consequence type (i.e., buildings, population, and agriculture) for each county and Census Tract. The population EAL is measured in fatalities and injuries while the building and agriculture values are measured in dollars. However, for consistency in the unit of measurement, the population EAL was monetized into population equivalence using a value of statistical life (VSL) approach where each fatality or 10 injuries is treated as $11.6 Million of economic loss.
3.2.3 Social Vulnerability
Social vulnerability, the consequence enhancing risk component of the NRI, measures the susceptibility of social groups to the adverse impacts of natural hazards, including disproportionate death, injury, loss, or disruption of livelihood. The Social Vulnerability score and rating represent the relative level of a community’s social vulnerability compared to all other communities at the same level. A higher Social Vulnerability score results in a higher Risk Index score.3 The table below illustrates the Social Vulnerability rating and score for the City planning area (Census Tracts).
Table 3.3: Social Vulnerability for the City of Downey Planning Area Census Tract Rating FEMA National Risk Index Score
550501 Relatively High 71.87
550502 Relatively Low 28.85
550601 Relatively High 72.22
550602 Relatively Moderate 52.15
3 Federal Emergency Management Agency. (2023). Social Vulnerability. Retrieved from https://hazards.fema.gov/nri/social-vulnerability .
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Census Tract Rating FEMA National Risk Index Score
550700 Relatively High 72.69
550801 Relatively Moderate 53.81
550802 Relatively High 63.88
550901 Very High 91.36
550902 Relatively High 74.18
551001 Relatively Moderate 47.93
551002 Relatively High 69.05
551101 Very High 94.68
551102 Very High 88.91
551201 Very High 86.37
551203 Relatively Moderate 59.22
551204 Relatively High 73.33
551300 Very High 87.36
551401 Very High 89.56
551402 Very High 85.91
551501 Relatively High 74.36
551502 Relatively High 63.49
551700 Relatively High 71.49
551801 Relatively Moderate 47.09
551802 Relatively High 76.08
553400 Relatively High 78.05
980012 Very High 81.25
Social Vulnerability is measured using the Social Vulnerability Index (SoVI) published by the University of South Carolina’s Hazards and Vulnerability Research Institute (HVRI).
3.2.4 Community Resilience
Community resilience, the consequence reduction risk component, measures the ability of a community to prepare for anticipated natural hazards, adapt to changing conditions, and withstand and recover rapidly from disruptions. The Community Resilience score and rating represent the relative level of a community’s resilience compared to all other communities at the same level. Since the score is inversely proportional to a community’s risk; the higher
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Community Resilience score results in a lower Risk Index score.4 The table below illustrates the Community Resilience rating and score for the City planning area (Census Tracts).
Table 3.4: Community Resilience for the City of Downey Planning Area Census Tract Rating FEMA National Risk Index Score
550501 Very Low 15.43
550502 Very Low 15.43
550601 Very Low 15.43
550602 Very Low 15.43
550700 Very Low 15.43
550801 Very Low 15.43
550802 Very Low 15.43
550901 Very Low 15.43
550902 Very Low 15.43
551001 Very Low 15.43
551002 Very Low 15.43
551101 Very Low 15.43
551102 Very Low 15.43
551201 Very Low 15.43
551203 Very Low 15.43
551204 Very Low 15.43
551300 Very Low 15.43
551401 Very Low 15.43
551402 Very Low 15.43
551501 Very Low 15.43
551502 Very Low 15.43
551700 Very Low 15.43
551801 Very Low 15.43
551802 Very Low 15.43
553400 Very Low 15.43
980012 Very Low 15.43
Community Resilience is measured using the Baseline Resilience Indicators for Communities (HVRI BRIC) published by the University of South Carolina's Hazards and Vulnerability Research Institute (HVRI).
4 Federal Emergency Management Agency. (2023). Community Resilience. Retrieved from https://hazards.fema.gov/nri/community-resilience .
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3.3 Total Risk Scores
The following table represents the new overall risk scores for the City based on the Risk Assessment Methodology defined at the beginning of this chapter. Following a data-driven quantitative assessment, from reviewing and ranking local knowledge from local subject matter experts, to developing other risk elements by the Core Planning Team based on the data collected. These elements were then aggregated to inform the analysis. The development of the Total Risk Score is organized based on the following: ranked by ranked by Total Risk Score. If same Risk score, ranked by Probability Factor. If same Probability Factor, ranked by Impact Factor and if same Impact Factor, ranked by Vulnerability Factor.
Table 3.5: 2023 Hazard Risk Scores for the City of Downey Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of Weighted
Extent Factors
Sum of Weighted
Vulnerability Factors
Sum of Weighted
Impact Factors Consequence Score
Total Risk Score
(Probability x
Consequence)
Earthquake 3 12 16 37 65 95
Wildfire Smoke/ Air Quality 3 7 15 23 45 69
HazMat Release 2 8 10 32 50 53
Cyber Incident 2 7 10 28 45 49
Utility Loss 2 7 12 26 45 49
Acts/Threats of Mass Violence 2 11 10 23 44 48
City of Downey Hazard Mitigation Plan 3-16
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of Weighted
Extent Factors
Sum of Weighted
Vulnerability Factors
Sum of Weighted
Impact Factors Consequence Score
Total Risk Score
(Probability x
Consequence)
Drought 2 6 12 23 41 45
Civil Unrest 2 4 12 24 40 44
Severe Weather /Storm 2 4 15 19 38 42
Transportation Accident 2 4 10 19 33 37
Pandemic 1 12 16 32 60 34
Dam Failure 1 5 12 33 50 29
Urban Flood 1 8 12 22 42 25
Tornado 1 8 7 23 38 23
Urban Fires 1 5 10 23 38 23
Windstorm 1 4 12 19 35 22
Classification Probability
Factor
Sum of Weighted
Extent Factors
Sum of Weighted
Vulnerability Factors
Sum of Weighted
Impact Factors Consequence Score Total Risk Score
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors. The Total Risk Score is a product of Probability and Consequence.
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Limitations
The assessment of data and identifying the risk to a community is not a hard science, as the analysis of hazards is complicated by several factors including laws, customs, ethics, values, attitudes, political preferences, complex infrastructures, and the built environment. It is not possible to fully predict hazards or their impacts. Furthermore, the perception of what constitutes a significant risk or impact can easily differ between individuals. Despite the inherent limitations, a well thought out risk assessment can act as a guide and provide a wealth of valuable information that is essential for identifying goals, prioritizing actions, planning and preparedness, and recovering and mitigating future hazards. The hazard analysis developed for this Plan should be best considered as an initial step in the process of continuously evaluating, preparing for, and mitigating the community’s hazards.
3.4 Hazard Profiles & Description
The hazard profiles identify the hazards that can affect the City. It analyzes each of the hazards with respect to where each hazard might affect the planning area, its potential magnitude, how often events have happened in the past, how likely they are to occur in the future; what parts of the City are most likely to be affected; and the potential consequences.
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3.5 Acts/Threats of Mass Violence
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.6: Acts/Threats of Mass Violence Total Risk Score Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Acts/Threats of
Mass Violence 2 11 10 23 44 48
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.5.1 Acts/Threats of Mass Violence Description
There is not a universal definition of mass violence crimes, mass murders, or mass killings; researchers, criminal justice experts and public policy bodies use many different definitions.
U.S. Congress has defined mass violence in legislation in three ways. • Mass Killings – three or more killings in a single incident that occur in a public place. • Mass Shooting – a multiple homicide incident in which four or more victims are. murdered with firearms, within one event, in one or more locations in close proximity. • Mass Public Shooting – a multiple homicide incident in which four or more victims are murdered with firearms, within one event, in one or more locations in at least one or more
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public locations; a workplace, school, restaurant, house of worship, neighborhood or other public setting.4F5
Terrorism as an act or threat of mass violence can take many forms. It is the unlawful use of force or violence against people or property to intimidate or coerce a government or civilian population in protest of political or social objectives. Terrorism and active assailant events are often violent mass casualty incidents. These events typically occur without warning, or without any warning signs. These events have recently taken the form of mass shootings, however, can also be caused by other means, such as bombs and vehicle-based attacks. These events can kill and injure multiple people in a single incident.
In recent years, terrorists have used mass transportation, explosive devices, guns, knives, biological weapons, kidnappings, and other methods to inflict terror on their target audience.
Although much focus has been placed on international terrorist groups targeting the United States and other western countries, terrorists can also be citizens of the targeted country. Active assailants are armed intruders engaged in killing or attempting to use deadly force on other people in a confined space or populated area. Most terrorist attacks stem from a political or religious disagreement with the target country or population.
The convergence of cyber incidents and terrorism is cyber terrorism. It is the use of technology and the internet to disrupt society and promote widespread fear. The worst possible cyberterrorism events include a breach in computers that control dams or air traffic control. The possible extent is endangering millions of lives and national security.
The Federal Bureau of Investigation (FBI) has categorized two types of terrorism in the U.S.:
• International Terrorism: Violent, criminal acts committed by individuals and/or groups who are inspired by, or associated with, designated foreign terrorist organizations or nations (state-sponsored).
• Domestic Terrorism: Violent, criminal acts committed by individuals and/or groups to further ideological goals stemming from domestic influences, such as those of a political, religious, social, racial, or environmental nature.
According to the Central Intelligence Agency, there are more than 65 terrorist groups designated by the U.S. State Department as Foreign Terrorist Organizations (FTOs).
5 National Mass Violence Victimisation Resource Center. (2023). About Mass Violence. Retrieved from https://www.nmvvrc.org/learn/about-mass-violence/ .
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Well-known international terrorist groups include Islamic Fundamentalist groups, such as Islamic State (IS) in Iraq and Syria, ISIS in numerous countries (10 affiliated groups as of May 2023), Al Qa’ida (5 affiliate groups as of May 2023), Segunda Marguetalia, and Revolutionary Armed Forces of Columbia – People’s Army. Currently, there are 58 Designated Foreign Terrorist Organizations (including affiliated groups) on the Department of State watch list.6 In 2022, the deadliest terrorist groups in the world were Islamic State (IS) and its’ affiliates, al- Shabaab, Baluchistan Libertarian Army (BLA), and Jamaat Nusrat Al Islam wal Muslimeen (JNIM).7
Domestic terrorism began to rise in recent years with the Department of Homeland Security declaring that the United States remains in a heightened threat environment. Lone offenders and small groups motivated by a range of ideological beliefs and/or personal grievances continue to pose a persistent and lethal threat to the United States.
According to the Department of Homeland Security, there have been 231 domestic terrorism incidents from 2010 to 2021 with 35% being racially or ethnically motivated. Over the last 10 years, investigations into domestic terrorism have risen more than 357% with the greatest number of incidents occurring in states with large metropolitan areas; California with Los Angeles, San Francisco and San Diego, New York with New York City and in Washington D.C. 8 Some notable domestic terrorism attacks include a 2018 attack on a Pittsburgh P.A. synagogue that left eleven people dead and a racially motivated attack in 2022 on a Buffalo, N.Y. grocery store where ten people were killed.
In the U.S., there are numerous extremist groups. Examples include The Boogaloo Movement, Neo-Fascist Skull mask Movement, The Proud Boys, and Oath keepers, with the first three listed having members in California.9 Additionally the Southern Poverty Law Center list 103 hate groups in California; 13 of which appear in the Los Angeles area, and six in nearby Orange County.10
6 U.S. Department of State. (2023). Foreign Terrorist Organizations. Retrieved from https://www.state.gov/foreign-terrorist-organizations/
7 Relief Web. (2023). Global Terrorism Index 2023. Retrieved from https://reliefweb.int/report/world/global- terrorism-index-2023
8 U.S, Government Accountability Office. (2023). The Rising Threat of Domestic Terrorism in the U.S. and Federal Efforts to Combat It. Retrieved from https://www.gao.gov/blog/rising-threat-domestic-terrorism-u.s.-and- federal-efforts-combat-it
9 George Washington University Program on Extremism. (2023). Domestic Extremism Tracker. Retrieved from https://extremism.gwu.edu/domestic-extremism-tracker
10 Southern Poverty Law Center. (2023) Hate Map. Retrieved from https://www.splcenter.org/hate-map
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In recent years, there have been several domestic terrorism incidents from those opposed to LGBTQ+ rights, animal rights activists, environmentalist groups and white supremacists.
The figure below shows the number of domestic terrorism incidents by state from 2010 to 2021.
Figure 3.2: Domestic Terrorism Incidents by State 2010-2021 11
There are several methods a terrorist may use to carry out their objective, including attacks of a chemical, biological, radiological, nuclear, explosive, and cyber nature. In addition, terrorists conduct hijackings, assassinations, armed assaults, kidnappings/hostage taking, arson fires, sabotage of critical infrastructures such as utilities and transportation, and the dissemination of confidential or otherwise sensitive information for the planning of terrorist attacks.
Preventing these incidents is in the purview of local, state, and federal law enforcement. The City of Downey assessed this hazard to determine where and how they can mitigate the effects of terrorism in the community.
11 GAO Highlights. (2023). Domestic Terrorism. Retrieved from https://www.gao.gov/assets/D23104720HIGH.pdf
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3.5.2 Acts/Threats of Mass Violence Hazard History
The U.S. has proven to be a high priority target for both domestic and international terrorists.
Acts or threats of mass violence have become increasingly alarming in their magnitude in recent years. Examples of this include the bombing of the Alfred P. Murray Federal Building in Oklahoma City in 1995 and the attacks of September 11, 2001, on the World Trade Center complex and the Pentagon. Not all attacks, however, are at this level of intensity. The U.S. has also been subject to small scale attacks in the past such as the bombing at the Boston Marathon in 2013. On the local level, in January 2023, a shooting at a Lunar New Year party in Monterey Park, approximately 13 miles from the City, left twelve people dead and nine injured. The shooter did take his own life.
There was a breach on the U.S. Capitol on January 6, 2021, that disrupted the joint session of Congress in the process of affirming the 2020 U.S. Presidential election results. More than 2,000 rioters from all fifty states traveled to Washington D.C. in support of Donald Trump who refused to accept the 2020 election results and falsely claimed that he won. Some were armed with Molotov cocktails and weapons and dressed in tactical gear. They broke windows and knocked down doors, violently pushing past and attacking Capitol Police as they searched for then Vice President Mike Pence and Speaker of the House Nancy Pelosi, vandalizing and looting offices and the House chamber. Damages are estimated at more than $2.734 million while 5 people died, including a Capitol police officer while several Capitol police officers committed suicide in the days and months following the riot. Approximately 140 police officers were assaulted on January 6th. More than 1,000 people have been arrested in connection to the violence at the Capitol on January 6, 2021. The City has not been directly impacted by terrorism events in the past.
3.5.3 Acts/Threats of Mass Violence Hazard Probability, Frequency, and Magnitude
While there has not been a large-scale event with the City, the City recognizes the potential for a terrorism event to impact residents. Given current escalating terrorism trends, the threat of a terrorist event within the U.S. is a credible possibility and the City ranked the probability of terrorism accordingly during the Hazard Identification Workshop. Although the City has few
City of Downey Hazard Mitigation Plan 3-23
hard targets within its boundaries, such as the Public Health Lab which houses protected classes of biological agents, the threat of terrorism exists due to its proximity to the City and County of Los Angeles, the Los Angeles Airport, and other identified targets.
The City previously completed a Security Vulnerability Assessment of City Hall to comply with the Bioterrorism Act of 2002. The Security Vulnerability Assessment evaluated the City’s vulnerability to malevolent attacks, including terrorism and contamination, and developed recommendations to protect against malevolent attacks. However, because of the security sensitive nature of the information, the terrorism risk assessment results are not repeated as part of the Hazard Mitigation Plan.
Vulnerability and Impacts
Mass violence impacts the life safety and health of the city by threatening the well-being off the Public through potential injury and death. Mass violence impacts property damage and critical infrastructure of the city by potentially damaging or destroying buildings and critical facilities in the area of the event. Mass violence impacts the economy of the city by disrupting business in the affected area, potentially for an extended period of time. Mass violence impacts the changes in development and impact of future development for the city by slowing down development in a specific area or causing businesses to relocate to a lower-risk area. Mass violence impacts underserved and at-risk populations of the city by limiting critical services within the area, disproportionately affecting individuals who rely on such services day-to-day. Research regarding the effects of climate change in severity of impact for Mass violence for the City indicates that countries and populations impacted by climate change are more vulnerable to terrorism recruitment, and violence, thus increasing the overall likelihood.12
12 United Nations. Meetings Coverage and Press Releases. (2021). People, Countries Impacted by Climate Change Also Vulnerable to Terrorist Recruitment, Violence, Speakers Tell Security Council in Open Debate.
Retrieved from https://press.un.org/en/2021/sc14728.doc.htm
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3.6 Civil Unrest Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.7: Civil Unrest Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Civil Unrest 2 4 12 24 40 44
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.6.1 Civil Unrest Hazard Description
Civil Unrest is generally the result of, and a form of protest, some form of socio-political problem. It typically consists of a disruption of normal, orderly conduct in urban areas, or an outbreak of rioting or violence that is of a large nature. Examples of civil disorders or civil strife, as it is sometimes referred to, might include illegal parades, sit-ins, riots, sabotage, and other forms of crime. It is typically spurred by specific events, such as criminal trials, sporting events, or political disfavor. Damage to local City buildings, critical facilities, and infrastructure resulting from these types of demonstrations could potentially leave citizens without critical resources. Incidents of Civil Unrest often occur sporadically and without warning.
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In addition to the physical losses a demonstration can bring to the City, they often require a response from local authorities which diminishes their ability to provide a service to other parts of the City. If a demonstration were to occur in conjunction with a hazardous event, it would be possible for the authorities to be overwhelmed, leaving the city vulnerable to extensive damage.
3.6.2 Civil Unrest Hazard History
The City of Downey is in close proximity to the City of Los Angeles which has been the host of several demonstrations of civil unrest historically. Below are a few examples of public demonstrations which have taken place in the region.
Watts Riot 1965
As stated by the Martin Luther King Jr Research and Education Institute, the Watts Riot was a six-day race riot that began on August 11th, 1965, and lasted until August 17th. By the time the National Guard was able to restore peace, 34 were dead, 1,032 were injured, 3,438 citizens had been arrested and the City of Los Angeles has sustained over $40 million in damages. The riot was started after police officers allegedly mistreated Marquette Fry, a 21- year-old African American man, after pulling him over for drunk driving. While the facts about the incident are unclear, rumors of police misconduct spread throughout the community inciting six days of chaos. It is estimated that between 31,000 and 35,000 adults actively participated in destroying and looting local neighborhoods.
Los Angeles Riot 1992
The Los Angeles Riot was a race riot that manifested after Rodney King, an African American man, was beaten by a group of police officers that stopped him for driving intoxicated on March 3, 1991, according to U.S News. The Los Angeles District Attorney charged the four officers with excessive force and for a year the case was covered heavily by the media. On April 29th, 1992, the jury acquitted all four officers of assault and three of the fours of using excessive force. Within the first half hour of the announcement of the verdict, at least 300 people gathered outside the Los Angeles County courthouse to protest. By the time the six-day demonstration was over the numbers of protesters had swelled, the City had sustained $1 billion in property damages, and widespread looting, assault, arson, and murder had been
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reported all over the city. Over 2,000 had been injured and 53 had been killed before Mayor Bradley declared the end of the riot on May 4th, 1992.
May Day Demonstration
On March 29th, 2006, according to the Los Angeles Times, over 500,000 gathered in the heart of Los Angeles, California to protest Congressional efforts to intensify illegal immigration legislation. While the protest was peaceful, several businesses had to shut down operations and traffic hazards resulted from the demonstration.
Black Lives Matter Demonstrations
The group Black Lives Matter (BLM) is an activist movement which campaigns against violence and racism directed towards black people. BLM regularly organizes demonstrations in response to shooting deaths of black people by law enforcement throughout the nation including protests in and near Los Angeles County. On July 10th, 2016, more than 1,000 protesters marched through the streets of Inglewood in a BLM protest against police violence.
The protest was peaceful, and no arrests were made though the 405 Freeway was temporarily blocked in both directions.
Figure 3.3: Black Lives Matter Protest in Los Angeles
Klu Klux Klan Rally
On February 28, 2016, violence broke out during a Klu Klux Klan rally in Anaheim, CA. Around noon, seven Klan members arrived at Pearson Park when counter-protesters swarmed Klan members setting off a series of brawls up and down West Cypress Street. When police arrived
City of Downey Hazard Mitigation Plan 3-27
on the scene, 5 were hurt and 13 were arrested. Orange County District Attorney, Tony Rackauckas, issued the following statement regarding the following legal proceedings. “This case is not about who was holding the protest rally, their racist message, or who was counter- protesting. This is about the mob mentality turning violent, which shut down neighboring streets, access to the park, and endangered the community.” Anti Trump Protests 2016
Dozens of people were arrested after demonstrators entered the 101 Freeway in Los Angeles in protest of the presidential election of Donald Trump. An estimated 3,000 people congregated at city hall before moving down the road and onto the freeway, which subsequently snarled traffic for miles. There were reports of protestors throwing rocks and bottles at police, vandalizing city buildings, and damaging at least one police car.
George Floyd Protests 2020
On May 27, 2020, crowds protested in the streets of downtown Los Angeles and blocked the 101 Freeway. There were additional neighborhood protests throughout the city. Most were peaceful, but some erupted in violence, looting, arson, and vandalism. Additionally, some groups were witnessed throwing objects at police. As police focused on crowd control and peaceful protests, some less than lethal force was used. Allegedly, the majority of injuries reported by people in crowds were due to the less than lethal rounds, with injuries ranging from minor to significant, some about the head, neck, back, and eyes. More than 4,000 individuals were arrested on various charges during the protests, which continued for weeks.13
3.6.3 Civil Unrest Hazard Probability, Frequency, and
Magnitude
The potential for Civil Unrest is difficult to predict and can happen anywhere in the City.
Demonstrations are often unplanned and arise as the result of an emotional response to current social and political issues. The threat of disturbances is always present as local governments attempt to respond to changes in the political climate. For example, declining financing for education, protocol for dealing with illegal immigrants, and many other issues
13 An Independent Examination of the Los Angeles Police Department 2020 Protest Response. (2021). Print.
Retrieved from https://clkrep.lacity.org/onlinedocs/2020/20-0729_rpt_CLA_03-11-21.pdf
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that could potentially recreate the events of previous riots. The City has dealt with small uprisings in its past but acknowledges the potential for larger demonstrations. As a result, Civil unrest was included in the Plan update.
Vulnerability and Impacts
Civil unrest impacts the life safety and health of the city by threatening the well-being of the public, potentially over a wide area. Civil unrest impacts property damage and critical infrastructure of the city by potentially damaging or destroying buildings within the affected area. Civil unrest impacts the economy for the city by disrupting or destroying businesses within the affected area, and potentially driving future businesses to relocate. Civil unrest impacts the changes in development and impact of future development for the city by reducing the likelihood of future development opportunities as the Public and businesses relocate to lower-risk areas. Civil unrest impacts underserved and at-risk populations of the city by limiting access to essential services within the event area. The effects of climate change in severity of impact for Civil unrest for the City is still being studied, but higher temperature may corelate with increased civil unrest through numerous, indirect factors.14
14 United Nations Climate Change. (2022). Conflict and Climate. Retrieved from https://unfccc.int/news/conflict- and-climate
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3.7 Cyber Incident Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.8: Cyber Incident Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Cyber Incident 2 7 10 28 45 49
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.7.1 Cyber Incident Hazard Description
A cyber incident is an anticipated or unanticipated disruption to information systems and networks. Events that cause cyber incidents are cyber-attacks, power outages, earthquakes, hurricanes, and other manmade and natural hazards. A cyber-attack is an effort by hackers to gain access to an electronic network or system. Cyber-attacks happen all day, every day, around the world. Major targets typically include governments, banks, and businesses, but any online network can be attacked. Common cyber-attacks are malware, phishing, and ransomware.
• Malware using any software used to gain unauthorized access to IT systems in order to steal data, disrupt system services or damage IT networks in any way.
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• Ransomware is a type of malware identified by specified data or systems being held captive by attackers until a form of payment or ransom is provided. • Phishing is an online scam enticing users to share confidential information using deceitful or misleading tactics.
Advancements in technology have increased the productivity of our nation and made daily operations and markets reliant on cyber systems. As a result, the United States has become, and will increasingly continue to be, vulnerable to non-traditional attacks including cyber- attacks on information and operations. Cyberspace is the nervous system for all critical infrastructures and is composed of hundreds of thousands of interconnected computers, servers, routers, switches, and fiber optic cables that allow our critical infrastructures to work. According to the Cybersecurity and Infrastructure Agency, 1 in 3 homes with computers are infected with malicious software, 47% of American adults have had their personal information stolen, and 600,000 Facebook accounts are hacked every day. Between 2015 and 2020, over 440,000 complaints were received on average every year and in 2020 victims of cyber-attacks lost $4.2 billion in total.
The attacks on computer systems can come in the form of viruses, Trojans, worms, spoofs, or hoaxes from virtually anywhere in the world. Computer viruses, ranging from devastating to simply annoying, are sent out daily by organizations and individual hackers, and intermittently by people who fail to protect their computer software.
3.7.2 Cyber Incident Hazard History
Cyber incidents occur regularly in California but are not typically reported in a local central database. Previous occurrences provided below are national and regional examples:
• On or around May 31, 2023, Progress Software, the provider of MOVEit Transfer software disclosed a vulnerability in their software that had been exploited by an unauthorized third party. Pension Benefit Information utilizes MOVEit in the regular course of our business operations to securely transfer files, including with Prudential and our other customers.
• On March 5, 2023, Sysco became aware of a cybersecurity event perpetrated by a threat actor believed to have begun on January 14, 2023, in which the threat actor gained access to Sysco systems without authorization and claimed to have acquired
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certain data. Personal information for some current and former colleagues has been impacted.
• On January 11, 2023, the FAA had a system outage, grounding all domestic and international flights nationally, because a contractor unintentionally deleted files on a database.
• On May 5, 2022, the City of Chula Vista identified evidence of unauthorized access to certain systems in the City’s computer network. As a result, City learned that an unauthorized party may have accessed or acquired certain data that was stored on their systems.
• To regain control of servers encrypted in an attack on September 17, 2021, Pottawatomie County, Kansas, officials agreed to pay a ransom of $71,606.25, which could be seen as a bargain considering the initial asking price attackers demanded—a cool $1 million to release control of the county’s data. The attack impacted the county’s driver’s license system and the tax department. It persisted for two weeks. • In May, 2021, An attack involving Babuk ransomware resulted in the theft of 250 gigabytes of police data, including police officer personnel files, arrest records, and intelligence memos. Screenshots shared by cybercriminals online included extensive personal data stolen from the department, as well as performance reviews and polygraph records. When attackers were denied a ransomware payment of $4 million, 22 personnel files were published online, each more than 100 pages. • An attack in May 2019, which began when an employee in the police department opened an infected email, took the City of Riviera’s main computer system offline, affecting every department. The city’s finance department was forced to manually issue payroll checks that would otherwise have been automatically deposited in employee accounts electronically. To secure the safe return of stolen data taken during the ransomware attack, city council members approved the payment of a $600,000 ransom, payable in bitcoins by the city’s insurance company.
3.7.3 Cyber Incident Hazard Probability, Frequency, and Magnitude
While the City of Downey has not experienced significant cyber incidents, the risk and vulnerabilities are realized through historical accounts in other places. The State of California
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Office of the Attorney General acknowledges 406 cyber incidents between June 1, 2022, and May 31, 2023. Most of these incidents originated outside of the state and impacted private companies collocated in the State. Cyber incidents occur virtually. They can originate from anywhere in the world and can target information technology anywhere in the world.
As society becomes increasingly dependent on technology, the threat and likelihood of cyber incidents will only increase.
Increased dependency on technology and the internet has resulted in a significant risk to cyber incidents.
Cyber incidents can disrupt the intended flow of information and cause business interruption, target private information, or physically manipulate items connected to the network. In major cyber-attacks, information can be stolen from millions of people. The extent and magnitude of a cyber incident is dependent on many variables and may range from a minor to major impact on both the general public and critical infrastructure. Table 3.9 outlines the Cybersecurity & Infrastructure Security Agency’s (CISA) practice of classifying cyber incidents. The table elaborates on the National Cyber Incident Scoring System (NCISS), a methodology utilized by CISA to classify the severity of a cyber incident after utilizing various factors to compute a score.
Table 3.9: CISA National Cyber Incident Scoring System 15 Priority Level Description
Emergency
An incident that poses an imminent threat to the provision of wide scale critical infrastructure services, national government stability, or the lives of the United States population.
Severe
An incident that is likely to result in a significant impact to public health or safety, national security, economic security, foreign relations, or civil liberties.
High
An incident that is likely to result in a demonstrable impact to public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.
Medium An incident that may affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.
Low
An incident that is unlikely to affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.
15 Cybersecurity & Infrastructure Security Agency. (2020). CISA National Cyber Incident Scoring System (NCISS). Retrieved from https://www.cisa.gov/news-events/news/cisa-national-cyber-incident-scoring-system- nciss.
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Priority Level Description
Baseline Classification
A baseline priority incident is highly unlikely to affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence. The bulk of incidents will likely fall into the baseline priority level with many of them being routine data losses or incidents that may be immediately resolved. However, some incidents may require closer scrutiny as they may have the potential to escalate after additional research is completed. In order to differentiate between these two (2) types of baseline incidents, and seamlessly integrate with the Cyber Incident Severity Schema (CISS), the NCISS separates baseline incidents into two (2) categories – minor and negligible.
Minor
An incident that is highly unlikely to affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence. The potential for impact; however, exists and warrants additional scrutiny.
Negligible
An incident that is highly unlikely to affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.
Vulnerability to Future Assets/Infrastructure
All existing and future assets/infrastructure are unlikely to receive direct damage. However, the systems and technologies that are integrated within these assets will undoubtedly be affected, especially as technology becomes more advanced and automatedVulnerability Analysis City of Downey government offices, as well as businesses, non-profits, and private residents can be impacted by cyber incidents. Vulnerability is dependent on what actions the individual or group in charge of the network have done to protect it.
Impact to City of Downey Residents
Any resident of the City that is connected to the internet is vulnerable to cyber incidents and identify theft. These incidents have long been a growing trend along with the increasing adoption of technology. Victims of this hazard are likely to experience substantial monetary loss or harassment. Any disruption to Internet service or critical infrastructure information systems could potentially threaten lives, property, the economy, and national security.
Impact to Essential Facilities and Other Property
Any essential facility connected to a network is at risk for a cyber incident. For example, individuals and businesses are reliant on information systems and the internet for daily tasks; without access to these systems, there could be major financial losses. Furthermore, delivery systems including water, electricity, even things such as groceries rely on information systems to coordinate and complete the delivery. Building Inventory: This hazard typically does not impact the actual building itself.
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Impact to Critical Infrastructure
While sabotage of computer systems normally would not lead to harm to health and safety, it is possible. As technology becomes more integrated into society, the more access hackers will have to sensitive systems. Integration of systems (such as electrical grids, air traffic control centers, traffic lights, etc.) can leave these systems vulnerable to attack. If these systems are compromised, it is possible that people may be injured or killed.
Impact to Environment
This hazard typically does not impact the environment.
Impact to Operations
Cyber incidents carried out on public infrastructure can directly impact the City’s ability to operate essential facilities and provide services. Forms of sabotage to computer systems include the introduction of viruses, malware or spyware that can cripple a computer network or steal private and public information. Emergency services, such as 911 dispatch would have difficulties because most phone lines work via the Internet. Medical response and care are reliant on electricity, water and information systems and the Internet to access medical records.
If the Internet was not available, many information systems would be inoperable and operations for many of the critical infrastructure sectors may stop altogether, causing critical disruptions for both the public and private sector.
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3.8 Dam Failure Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.10: Dam Failure Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Dam Failure 1 5 12 33 50 29
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.8.1 Dam Failure Hazard Description
Dams are artificial/manmade structures that retain or detain water behind a large barrier.
When full, or partially full, the difference in elevation between the water above the dam and below creates large amounts of energy, creating the potential for failure. Dams can fail due to 1) water heights or flows above the capacity for which the structure was designed; or 2) deficiencies in the structure such that it cannot hold back the potential energy of the water.
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If a dam fails, issues of primary concern include loss of human life/injury, downstream property damage, lifeline disruption (of concern would be transportation routes and utility lines required to maintain or protect life), and environmental damage.
Dams are an important part of the infrastructure in the U.S., providing avenues for water supply, flood control, irrigation, hydroelectric power, and recreation. According to FEMA’s National Inventory of Dams (NID), the United States now has more than 92,000 total dams with an average age of 61 years. Dams in the NID are owned, operated, and regulated by a variety of entities. A breakdown of these 90,000 plus dams is as follows: 80 percent are regulated by the state dam safety offices, nearly 70 percent of the entire inventory is privately- owned, and six percent are owned or regulated by the federal government, which encompasses approximately 35 percent of the tallest dams. 15,030 dams in the NID are classified as high hazard potential meaning there are more than 1,250 dams in California, zero in the City of Downey but two NID high hazard dams are in close proximity to the City and would cause consequences should they fail. According to the FEMA website, dam failures are generally caused by one or a combination of the following reasons.
Overtopping
The Association of State Dam Safety Officials (ASDSO) reports 34% of all U.S. dam failures are due to overtopping because of inadequate spillway design, debris blockage of spillways, or settlement of the dam crest. Overtopping occurs when primary and emergency spillways are not sufficient to pass floodwaters and the excess runs over the top of the dam. The overflow can erode the embankment, weakening the dam wall and potentially cause a full dam failure.
While the City has not experienced the repercussions of a failed dam, the Sweetwater Dam failure that occurred on January 27, 1916, is an example of a release in Southern California that was the result of overtopping. After experiencing a long period of drought, the area received more than thirty-nine inches of rain. As a result, more than 200 bridges were washed out, entire communities were swept away, levees collapsed, and valleys were inundated.
Should the Whittier-Narrows dam fail due to overtopping, this is likely the type of impact the City would encounter.
Acts of sabotage
Sabotage, or deliberate actions aimed at disrupting normal dam operations, can occur for many reasons. Like an act of terrorism or public demonstration, acts of sabotage can be motivated by several factors; political, socio-economic, and religious are just a few. Often, they occur
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suddenly, and without warning. However, according to the Stanford University National Performance of Dams Program (NPDP), sabotage and vandalism have been the cause of the fewest dam failures between the years 1975 and 2001. Therefore, while the City is vulnerable to acts of sabotage, it is unlikely to occur.
Structural failure of materials used in dam construction.
According to the NPDP, dam failure due to structural deficiencies are only marginally more common the acts of sabotage. Due to state regulations for dam construction and maintenance, failures due to inadequate structural integrity are rare.
According to FEMA, causes of dam failure in this category may include:
• Movement and/or failure of the foundation supporting the dam, • Settlement and cracking of concrete or embankment dams, • Piping and internal erosion of the soil in embankment dams, and • Inadequate maintenance and upkeep.
One of the most notable dam incidents in California history involved the Baldwin Hills Dam.
The dam was constructed in Baldwin Hills, Los Angeles between 1947 and 1951 to provide drinking water for West Los Angeles residents. The dam was constructed on an active fault line which many of the geologists involved in its planning considered unstable for a reservoir.
On December 14, 1963, a small crack developed in the embankment which widened to a 75- foot gash resulting in the release of 292 million gallons of water. Five people were killed, sixty- five homes were destroyed, and 210 home and apartments were damaged.
As mentioned previously, causes in this category are considered minor as they comprise a minute fraction of historic dam failures in the U.S. Figure 3.4 shows the causes of recorded dam failures between the years 1915 and 2016.
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Figure 3.4: Causes of Dam Failure
3.8.2 Dam Failure Hazard History
As stated previously, the most likely cause of flood within the City would be a dam failure or release. While the City has never been impacted by a dam failure or release, it should be noted, there have been a total of forty-five dam failures in California’s history. Failures and releases have occurred for a variety of reasons. According to the U.S. Bureau of Reclamation and as stated in Section 3.8.1, overtopping has accounted for more than 30 percent of all dam failures in the U.S. in the last seventy-five years. Other dams have failed due to specific shortcomings in the dam itself or an inadequate assessment of the surrounding geomorphologic characteristics.
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One notable dam failure occurred in 1883 in Sierra County, while a most recent failure occurred in 1965. The greatest catastrophe relating to California dam failure or release was William Mulholland’s St. Francis Dam, which failed in 1928, killing more than 450 people Because of this failure and the exposure of the potential risk to the general populace from a number of water storage dams in California, in 1929 legislation was enacted providing for supervision over non-federal dams in the State. Before the enactment of this legislation, either the State Engineer or the State Railroad Commission exercised State supervision over dams. This supervision was limited in scope and extended to less than half of the dams in the State. The statute enacted in 1929 provided for:
• Examination and approval or repair of dams completed prior to the effective date of the statute, August 14, 1929,
• Approval of plans and specifications, and supervision of construction of new dams, and of the enlargement, alteration, repair, or removal of existing dams, and • Supervision over maintenance and operation of all dams of jurisdictional size.
Overall, there have been at least 460 deaths as a result of dam failures in California. Some of these failures are outlined in the table below.
Table 3.11: Historical California Dam 16 Failures
Year
Failed Dam Location Cause of Failure/Deaths
1883 English Sierra County Dam crumbles to foundations, decay of timber used
1892 Long Valley
Creek San Jacinto Heavy rains, dam carried away
by flood
1895 The Angels Calaveras County Undetermined during flood, poor foundation/ 1 death reported
1896 Vernon Heights Oakland Shallow foundation
1898 Snake Ravine Stanislaus
County Poor compaction
1905 Piedmont No.1 Oakland Outlet pipe sheared off at core wall
1906 San Andreas San Mateo
County Crack along axis
16 Center for Watershed Sciences (n.d.) Research. Retrieved from https://watershed.ucdavis.edu/ .
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Year
Failed Dam Location Cause of Failure/Deaths
1912 Morena San Diego Overtopping
1916 Lower Otay San Diego Leakage and overtopping due to inadequate spillway
1918 Lake Hodges San Diego Cracks in pier
1925 Sheffield Santa Barbara Earthquake slide
1926 Puddingston Pomona Overtopping during construction 1927 Lake Hemet Palm Springs Overtopping
1928 Saint Francis San Francisquito
canyon
Sudden failure at full capacity
through foundation - 426 deaths
1934 Cogswell Monrovia Breaching of concrete cover
1963 Baldwin Hills Los Angeles Leak through embankment turned into washout/ 5 Deaths
1964 Hell Hole Rubicon River Failed during construction due to unprecedented rains
1965 Matilija Ventura Bad foundation and concrete
disintegrating
3.8.3 Dam Failure Hazard Probability, Frequency, and Magnitude Dams fail for a variety of reasons, including sub-standard construction materials/techniques, spillway design error, geological instability, poor maintenance, and earthquakes, and therefore recurrence probabilities are unknown. State jurisdiction dams are regulated by the California Department of Water Resource’s Division of Safety of Dams (DSOD) and each dam undergoes inspection on an annual basis to ensure it is safe, performing as intended, and is not developing issues. However, in 2017, the United States Army Corps of Engineers (USACE) discovered that the Whittier Narrows Dam was structurally unsafe and that an intense storm could prematurely open the dam’s massive spillway and flood the area below from Pico Rivera to Long Beach.
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The Whittier-Narrows Dam presents the greatest threat for dam failure or release to the City based on proximity. The USACE has reclassified the Whittier Narrows Dam as the agency’s highest dam priority nationally because of the risks “due to the combination of loss of life with a very high likelihood of failure only when filled by a rare flood event.” Such a storm event has only a 1 in 900 (i.e., 0.1%) chance of occurring in any given year.
The Garvey Reservoir Dam is also an identified high hazard dam, however due to data privacy and protected information, this information is not included in the HMP update. Inundation maps for the Garvey Reservoir do not show the City of Downey being directly impacted.
The San Gabriel Spillway which protects the dam, via nine emergency spillway gates, is commonly opened to permit small releases. If the pool exceeds 228.5 feet, the gates will open automatically to protect the dam but will result in downstream flooding. In addition, erosion from water piping through the foundation are rising concerns. Should the dam fail, according to recent estimates made by the USACE; waters from the Whittier-Narrows Dam would cause flooding in the City within 2-6 hours and reach an average depth of 5-10 feet resulting in loss of life and damage to structures, roads, and utilities. As a result of the potential severity of the consequence surrounding the failure or release of the Whittier-Narrows Dam, the City has identified Dam Failure as a vulnerability in this plan.
The table below identifies dams outside the City limits that could affect the City if they fail.
Table 3.12: Potential Impacting Dams Outside the City of Downey Dam Name Location NID Hazard Classification EAP
Garvey Reservoir 17 Los Angelos, CA High Approved
Whittier Narrows Dam Los Angelos, CA High Approved
17 National Inventory of Dams. (2022). Garvey Reservoir Inspection and Summary. Retrieved from https://nid.sec.usace.army.mil/#/dams/system/CA00217/inspections .
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Figure 3.5: Potential Impacting High Hazard Dams Outside the City of Downey
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While the City has not experienced a dam failure in the past, the entire City is located within the flood inundation area and is vulnerable to the impacts of a flood resulting from dam release or failure. The USACE assessment 18 is depicted below for the Whittier Narrows Dam.
Figure 3.6: Whittier Narrows Dam Inundation Area and Impact to the City of Downey
18 National Inventory of Dams. (2023). Whittier Narrows Dam Risk Characteristics. Retrieved from https://nid.sec.usace.army.mil/#/dams/system/CA10027/risk .
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Figure 3.7: Whittier Narrows Dam Scenarios
Scenarios are designated as either non-breach or breach. In non-breach scenarios the dam is operating as designed for the given pool level, releasing from outlets and controlled or uncontrolled spillways. In breach scenarios the continuity of the structure has been compromised, resulting in uncontrolled water releases that exceed the magnitude of releases in the equivalent non-breach scenario.
The Maximum High (MH) scenario (breach and non-breach) is based on the inflow design flood per FEMA guidelines and indicates the maximum reservoir pool level and likely maximum extent of inundation.
The Normal High (NH) scenario (breach and non-breach) represents normal full reservoir pool elevations with no flooding occurring downstream prior to dam releases. The NH scenarios represent the fair weather or sunny day scenarios per FEMA guidelines. The Intermediate High (IH), Top of Active Storage (TAS) and Security (SS) scenarios are intermediate pool levels between NH and MH. They are established based on the dam’s design characteristics and its operating history. The TAS represents the reservoir pool elevation the structure was designed for (such as the top of flood gates) and above which water must be released to ensure the integrity of the dam. The SS represents a high reservoir pool level observed or exceeded 1% of the time during the dam’s operating history. The IH represents a realistic operating condition that could be experienced during a major flood where the reservoir pool elevation exceeds Top of Active Storage.
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Table 3.13: Whittier Narrows Dam Consequence Estimate
Scenario Type Pool
Elevation
Daytime
People
at Risk
Nighttime
People
at Risk
Buildings
at Risk
Economic
Cost
Maximum High
Pool
Breach 241.3 0 0 0 0
Top of Active
Storage Pool
Breach 230.8 304,187 452,708 0 $6,043,625,027
Maximum High
Pool
Non-Breach 241.3 0 0 0 0
Top of Active
Storage Pool
Non-Breach 230.8 0 0 0 0
As a result of the threat of a dam release coupled with the potential for substantial impacts, the City has included dam failure as an identified hazard.
Figure 3.8: Aerial View of the Whittier Narrows Dam
While the State regulates dams to prevent failure, safeguard life, and protect property, some researchers doubt that the “overall safety of aging federal flood control systems that were not designed with climate change in mind.” They argue that as California experiences more intense storms, the aging dams in the area could fail and/or prematurely open and flood homes, schools, businesses, and roads. In 2016, Climate-Safe Infrastructure Bill (Assembly Bill [AB] 2800) became law and “established the Climate-Safe Infrastructure Working Group to develop recommendations to the California legislature on how to build
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and design our infrastructure to be safer for Californians in the face of growing climate extremes.” The Working Group’s 2018 report identified nearly 700 High hazard dams in California needing repairs and upgrades.
Vulnerability and Impacts
Dam failure impacts the life safety and health of the city by potentially causing injury or death due to rapid floodwaters and lack of essential services. Dam failure impacts property damage and critical infrastructure of the city by damaging or destroying buildings and infrastructure. Dam failure impacts the economy for the city by closing or destroying businesses in the affected flood area, driving away current and future businesses and parties. Dam failure impacts the changes in development and impact of future development for the city by potentially increasing relocation rates for businesses and homes to lower-risk areas. Dam failure impacts underserved and at-risk populations of the city by impacting critical services such as water, healthcare, and power infrastructure. The effects of climate change in severity of impact for dam failure for the City is largely increased precipitation. This in turn increases the chance for a dam failure due to overtopped reservoirs and structures under constant pressure from an increased reservoir.19
19 Jacques Leslie. Time Ideas. (2023). The Growing Danger of Dams. Retrieved from https://time.com/6317451/dams-environmental-impact-libya-danger/
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3.9 Drought Hazard Profile
Table 3.14: Drought Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Drought 2 6 12 23 41 45
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.9.1 Drought Hazard Description
A drought or extreme dry periodic climate is an extended period where water availability falls below the statistical requirements for a region. Drought is not a purely physical phenomenon, but rather an interplay between natural water availability and human demands for water supply. The National Integrated Drought Information System (NIDIS) defines drought as the deficiency of precipitation over an extended period of time (usually a season or more), resulting in a water shortage.20 The National Weather Service (NWS) defines drought as a deficiency of moisture that results in adverse impacts on people, animals, or vegetation over a sizeable area.21
Drought is part of the climate cycle, and it is an underestimated slow-moving hazard that can cause as much damage as other faster-moving hazards (e.g., hurricanes, flooding).
Drought can impact agriculture, public health, transportation, ecosystems, wildfire, and
20 National Integrated Drought Information System. (2023). What is a Drought? Drought Basics.
Retrieved from https://www.drought.gov/what-is-drought/drought-basics . 21 National Oceanic and Atmospheric Administration, National Weather Service. (2009). National Weather Service Glossary. Retrieved from https://w1.weather.gov/glossary/ .
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water quality. In order to assist with drought classification and monitoring, scientists have defined five (5) types of droughts, listed below. 22
Table 3.15: Types of Drought
Type Description
Meteorological Occurs when dry weather patterns dominate the area.
Hydrological Occurs when low water supply becomes evident in the water system Agricultural Occurs when crops become affected by drought.
Socioeconomic Occurs when the supply and demand of various commodities is affected by drought.
Ecological Occurs when natural ecosystems are affected by drought.
A drought’s severity depends on numerous factors, including duration, intensity, and geographic extent, as well as regional water supply demands by humans and vegetation.
Drought differs from other natural hazards in three (3) ways. • The onset and end of a drought are difficult to determine due to the slow accumulation and lingering effects of an event after its apparent end.
• The lack of an exact and universally accepted definition adds to the confusion about its existence and severity.
• In contrast with other natural hazards, the impact of drought is less obvious and may spread over a larger geographic area. These characteristics have hindered many governments' preparation of drought contingency or mitigation plans.
3.9.2 Drought Hazard History
Droughts reoccur every few years. Unlike other hazards (e.g., floods and earthquakes), droughts are not easily defined as “events”. A Presidentially Disaster Declaration for drought has never been declared in the State of California.
As stated in the City’s Urban Water Management Plan, the City supplies most of its water from groundwater pumped from the Central Basin. Additionally, the City is a member agency of the Central Basin Municipal Water District (CBMWD). The CBMWD imports
22 National Integrated Drought Information System. (2023). What is a Drought? Drought Basics.
Retrieved from https://www.drought.gov/what-is-drought/drought-basics .
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water from the Metropolitan Water District of Southern California and distributes it to its member agencies. Purchased water is expensive and reserved only for emergencies where the system demand exceeds production capacity. Additionally, the City utilizes recycled water to meet its non-potable demands.
Because water systems are interconnected, the regional impacts of drought may have adverse impacts for the City. It is important to consider current and past droughts throughout the state. Figure 3.9 provides the annual runoff in California provided by the U.S. Geological Survey from 2014-2023 with comparisons of prior years of generally dry and generally wet. (note, 2022 and 2023 are provisional and subject to change when final data is in.) Figure 3.10 provides runoff data for the last century. Runoff is the drainage of precipitation from, in this context, a land area. Commonly associated with the melting of the snowpack in Sierra Nevada mountains, runoff water flows down natural channels recharging reservoirs and groundwater systems in its path. It can be assumed then, that low runoff periods would be followed by periods of limited groundwater supply. The information can be taken as a case in point that periods of low runoff can contribute to and exacerbate drought conditions.
Figure 3.9: Monthly Runoff in California by Years
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Figure 3.10: Annual Runoff in California
Historic Droughts
Over the past century, many of the droughts experienced in the U.S. affected vegetation, food supply and livelihood for tens of thousands of families. This, in turn, created the need for water conservation and water management efforts across the country, including in California. For example, the California drought of 1976 to 1977 is an example of severe drought conditions. By the end of the “wet season” in 1976, California reservoirs were depleted and melting snow from the Sierra Nevada snowpack was minimal. The following year was marked as one of the driest years on record. Out of the 58 counties in California, 47 of them declared a local drought emergency. The drought hit farmers especially hard, with many experiencing economic losses in every stage of food production and supply.
This drought marked the beginning of an extensive water conservation movement across California that has continued even through times of abundance. As a result, farmers have switched to water efficient crops and reduced the aggressive pumping of groundwater.
In 2012, California experienced drought conditions it had not seen in 1,200 years according to a study completed by the University of Minnesota and Woods Hole Oceanographic Institution in Massachusetts. On January 17 of that year, California State Governor, Jerry Brown, declared a drought state of emergency.
California’s annual precipitation can vary greatly from year to year and region to region.
The map of California, figure 3.11 shows how [the 2023] water precipitation compares to
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what has been observed historically 23. The chart below, figure 3.11 provides a summary of California’s current statewide precipitation statistics 24.
Figure 3.11: California Precipitation (09/07/2023)
23 California Water Watch. (2023). Precipitation. Retrieved from https://cww.water.ca.gov/ . 24 Ibid.
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Figure 3.12: California Precipitation Statistics (1981-2023)
Climate change has made California’s dry and wet spells more extreme and unpredictable – after the three driest years on record, recent rain, and snowfall in early 2023 have dramatically changed conditions in many parts of the state. On March 24, 2023, Governor Gavin Newsom eased drought restrictions that are no longer needed while maintaining others to support impacted communities statewide via Executive Order N-5-23 25.
Harnessing water captured and stored from recent storms, (March 2023) the state also announced a major increase in expected State Water Project deliveries to local agencies – now an anticipated 75% allocation 26.The City will rely on the previously discussed infrastructure to maintain water services for its residents.
25Executive Department State of California. (2023). Drought Executive Order. Retrieved from https://www.gov.ca.gov/wp-content/uploads/2023/03/3.24.23-Drought-update-executive-order.pdf . 26California Department of Water Resources. (2023) Harnessing Series of Winter Storms, California Increases State Water Project Allocation. Retrieved from https://water.ca.gov/News/News- Releases/2023/March-23/Harnessing-Series-of-Winter-Storms-California-Increases-State-Water- Project-Allocation.
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3.9.3 Drought Hazard Probability, Frequency, and Magnitude A drought can occur anywhere in the City. Due to the dynamic nature of droughts, drought conditions are experienced differently based on where someone lives and their sources of water. For example, ranchers grazing livestock on non-irrigated rangeland and rural residents relying on private wells for groundwater can quickly be impacted by dry conditions. On the other hand, large urban water agencies with multiple water resources are able to manage for several dry years. However, if drought conditions in the area continue for an extended period of time, everyone will experience the effects.27 The City and the Metropolitan Water District of Southern California work closely together to evaluate new and innovative water management and supply development programs for the region, including water reuse and recycling, recharge facility construction, ocean and brackish water desalination, surface storage, and water use efficiency programs. These efforts are helping to enhance long-term water reliability and water quality as drought continues to impact the City as a whole.
Many drought indices have been developed; however, the Palmer Drought Severity Index (PDSI) is the most prominent index of meteorological drought utilized in the United States for drought monitoring. PDSI uses readily available temperature and precipitation data to estimate relative dryness to indicate the prolonged and abnormal moisture deficiency or excess. As an important climatological tool, the PDSI assists in evaluating the scope, severity, and frequency of prolonged periods of abnormally dry or wet weather.
Furthermore, it can be utilized to identify disaster areas and indicate the availability of irrigation water supplies, reservoir levels, range conditions, amount of stock water and potential intensity of wildfires. 28,29
The PDSI is a standardized measure that compares moisture deficiency and excess on a numerical scale that usually ranges from positive five (5) to a negative five (5). Positive
27 California Department of Water Resources. (n.d.). California Water Watch. Retrieved from https://cww.water.ca.gov/droughtindicator .
28 National Weather Service, Climate Prediction Center. (2005). Drought Indices: Explanation.
Retrieved from
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/cdus/palmer_drought/wpdanote.shtml . 29 National Center for Atmospheric Research. (n.d.). Climate Data Guide: Palmer Drought Severity Index (PDSI). Retrieved from https://climatedataguide.ucar.edu/climate-data/palmer-drought-severity- index-pdsi.
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values mean there is an excess in moisture supplies and conversely, negative values indicate moisture demands in excess of supplies. The table below displays the PDSI categories and Figure 3.13 illustrates the drought conditions in the contiguous United States as measured by the PDSI for the month of August 2023.
Table 3.16: Palmer Drought Severity Index
Palmer Drought
Severity Index Category
- 4.00 and below Extreme Drought
- 3.00 to - 3.99 Severe Drought
- 2.00 to - 2.99 Moderate Drought
- 1.99 to + 1.99 Mid-Range
+ 2.00 to + 2.99 Moderately Moist
+ 3.00 to + 3.99 Very Moist
+ 4.00 and above Extremely Moist
Figure 3.13: U.S. Palmer Drought Index Map (August 2023)
The U.S. Drought Monitor (USDM) is a collaboration between the National Drought Mitigation Center (NDMC), United Stated Department of Agriculture, and NOAA. They also rate drought nationwide by intensity utilizing a D0 (Abnormally Dry) to D4 (Exceptional
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Drought) scale, shown in the table below.30 The map updates weekly to show the location and intensity of drought across the country. 31 Figure 3.14 illustrates the USDM map for the State of California which shows where drought conditions are occurring and its severity. 32
Table 3.17: U.S. Drought Monitor Classification
Category Description Possible Impacts PDSI Range
D0 Abnormally
Dry
Used for areas showing dryness, but not yet in drought, or for areas recovering from drought.
Going into drought:
• Short-term dryness slowing planting, growth of
crops or pastures.
Coming out of drought:
• Some lingering water deficits.
• Pastures or crops not fully recovered.
-1.0 to -1.9
D1 Moderate
Drought
• Some damage to crops and pastures.
• Streams, reservoirs, or wells are low, and some
water shortages are developing or imminent.
• Voluntary water use restrictions requested.
-2.0 to -2.9
D2 Severe
Drought
• Crop or pasture losses are likely.
• Water shortages are common.
• Water restrictions imposed.
-3.0 to -3.9
D3 Extreme
Drought
• Major crop/pasture losses.
• Widespread water shortages or restrictions. -4.0 to -4.9 D4 Exceptional
Drought
• Exceptional and widespread crop/pasture losses.
• Shortages of water in reservoirs, streams, and
wells are creating water emergencies.
-5.0 or less
30 National Drought Mitigation Center. (n.d.). What is USDM. Retrieved from https://droughtmonitor.unl.edu/About/WhatistheUSDM.aspx . 31 National Integrated Drought Information System. (2023). U.S. Drought Monitor (USDM). Retrieved from https://www.drought.gov/data-maps-tools/us-drought-monitor . 32 U.S. Drought Monitor. (2023). California. Retrieved from https://droughtmonitor.unl.edu/Maps/MapArchive.aspx .
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Figure 3.14: U.S. Drought Monitor for California 33
Droughts develop gradually over long periods of time which can make it complicated to recognize when a drought will occur. However, understanding how large-scale climate patterns (e.g., El Niño–Southern Oscillation (ENSO) affect the potential of drought in an area can help forecast when drought conditions will occur. California’s Department of Water Resources (DWR)34 maintains the California Water Watch website which offers current local, at the regional and neighborhood level, and statewide water conditions.
The website includes information on precipitation, temperature, reservoirs, streamflow, groundwater, snowpack, soil moisture, and vegetation conditions, and California drought updates. In California, drought is based on impacts to water users and observing and monitoring water availability can help have a better understanding of when and where drought can occur.
33Ibid.
34 California Water Watch (n.d) Track California Water Conditions. Retrieved from https://cww.water.ca.gov/
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Estimating drought probability and frequency continues to be difficult, regardless of the improvements in science and technology. According to the 2023 California State Hazard Mitigation Plan, the normal occurrence droughts and documentation of past events and losses determine that the probability for drought events throughout the State will continue.35
The drought annualized frequency value represents the average number of recorded drought hazard occurrences, in event days, per year over the period of record (22 years).
The table below outlines the annualized frequency for drought, based on FEMA NRI data, for the City.
Table 3.18: Drought Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts
Events on Record
(2000 – 2021)
Annualized
Frequency
550501 1,624 73.8
550502 1,624 73.8
550601 1,624 73.8
550602 1,624 73.8
550700 1,624 73.8
550801 1,624 73.8
550802 1,624 73.8
550901 1,575 71.6
550902 1,589 72.2
551001 1,575 71.6
551002 1,575 71.6
551101 1,575 71.6
551102 1,575 71.6
551201 1,575 71.6
551203 1,575 71.6
35 California Governor’s Office of Emergency Services. (2023). California State Hazard Mitigation Plan.
Retrieved from https://www.caloes.ca.gov/wp-content/uploads/Hazard-Mitigation/Documents/2023- California-SHMP_Volume-1_11.10.2023.pdf.
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City of Downey
Census Tracts
Events on Record
(2000 – 2021)
Annualized
Frequency
551204 1,575 71.6
551300 1,575 71.6
551401 1,575 71.6
551402 1,575 71.6
551501 1,575 71.6
551502 1,575 71.6
551700 1,575 71.6
551801 1,575 71.6
551802 1,575 71.6
553400 1,575 71.6
980012 1,575 71.6
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
Vulnerability and Impacts
Population: The entire population of Downey is vulnerable to drought events. Drought impacts the life safety and health of the city by straining water supplies to severely impacted areas. The community may also exhibit a range of abilities to prepare for, respond to, and recover from drought hazards, as these conditions impact populations with health-related issues related to heat-related illness, respiratory problems, and people who work outdoors.
Drought impacts underserved and at-risk populations of the city by increasing the likelihood of health emergencies due to weather conditions usually accompanying droughts. These conditions can also impact lower-income populations, as food and water prices increase, or farmworkers who rely on agriculture for their livelihood.
In Downey, 12,419 residents (11.3 percent) are living with a disability. Disability and poverty are closely tied due to employment limitations. For residents with disabilities, more than 13 percent live in poverty. Many senior-headed households have special needs due to their relatively low incomes, disabilities or limitations, and dependency needs.
Specifically, many people aged 65 years and older live alone. In Downey, 12,552 residents
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are 65 years and older, representing 11.4 percent of the population. For residents 65 years and older, 9.5 percent live in poverty.
Extremely low-income (ELI) is defined as households with income less than 30 percent of area median income (AMI). 13.8 percent of the City's total households (4,525 households) are classified as extremely low income.
Table 3.19: Vulnerability and At-Risk Populations: Drought Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
Farmworkers 234 persons Less than 1% of labor
force
People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services Property: No structures will be directly affected by drought conditions. Drought impacts property damage and critical infrastructure of the city by increasing the strain on the electrical grid or water systems.
Table 3.20: Assets/Structures Vulnerability and Impact Summary: Drought Vulnerable Categories
Applicable to this Hazard
Number of Assets
of Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Hospitals 3 100%
Reliance on electrical
grid and sustained
power.
Parks 11 100% Reliance on water
systems for irrigation
Wells 20 100%
Reliance on electrical
grid and sustained
power; Prolonged
drought will impact
availability of water.
Lift Stations 2 100%
Reliance on electrical
grid and sustained
power.
Trees 15,600 100% Reliance on water
systems for irrigation
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Vulnerable Categories
Applicable to this Hazard
Number of Assets
of Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Source: Los Angeles County Assessors, City of Downey
Economic: Downey is located in Southern California, which is a semi arid desert environment with a limited amount of annual rainfall. As such there is a limited supply of surface and groundwater available to the region with most of the water supply imported from as far away as the Colorado River and Northern California. The Water Replenishment District of Southern California is charged with allocating water among the various jurisdictions and addressing potential water supply shortfalls by purchasing imported and reclaimed water for injection and spreading into the basin. Due to its high price, the direct use of imported water by the City is avoided except during periods of extreme drought.
Extreme drought would be very costly to the City.
Prices for food, energy, and other products increase as supplies are reduced. In some cases, local shortages of certain goods result in the need to import these goods from outside the stricken region. While droughts have a direct impact on agriculture, this sector is not a major economic driver for the City.
Changes in Development and Future Development: Drought impacts the changes in development and impact of future development for the city. Growth over the past decade has been modest. Between 2010 and 2020, as reported by the U.S. Census, the population of Downey grew approximately 0.9 percent, from 111,922 to 112,901 residents.
The Southern California Association of Governments (SCAG) growth forecasts predict a steady increase in population through 2045. From 2020 to 2045, SCAG projects that the City’s population will grow by 5.6 percent, while countywide population is expected to increase by 15.6 percent. The projected growth largely is tied to anticipated increases in housing production, which has not been a factor for the last decade. This projected population growth would add additional strain to water supplies and its 20 wells.
Droughts can directly impact the agricultural sector. In Downey, where there are no agricultural uses, only 234 residents, or 0.4 percent of the workforce are farmworkers. Los Angeles County has seen a significant decrease in agricultural workers. State EDD data (Employment Development Department) shows that between 2000 and 2020, the number of farmworkers countywide decreased by 43 percent, from 7,700 to 4,400 farmworkers in the region. In 2017, the Census of Agriculture from the US Department of Agriculture
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(USDA) documented that out of California’s approximate 377,500 agricultural workers, less than one percent (3,266) are located within Los Angeles County.
As new developments take place, the City has acknowledged that large or institutional consumers, such as the Downey Landing development project, should procure additional water rights during the conditional use permitting process.
The City of Downey Water Division extracts groundwater typically using around 20 of the 23 city-operated wells. The aquifers underneath the City are grouped into the central groundwater basin, which underlies large portions of central and eastern Los Angeles County. The basin is naturally recharged by regional rainfall, under flow from adjacent basins and runoff from surrounding uplands and mountains but the aquifers also receive supplemental imported water to meet demand and is recharged with highly treated wastewater. The Water Replenishment District of Southern California is charged with allocating water among the various jurisdictions and addressing potential water supply shortfalls by purchasing imported and reclaimed water for injection and spreading into the basin. Due to its high price, the direct use of imported water by the City is avoided except during periods of extreme drought. However, the increasing dependency on imported water to replenish the basin is an issue due to the increasing potential that the supplies of imported water may be curtailed by federal regulations or significant increases in the price.
As such, the city must look toward public and private conservation measures to maximize the use of existing water supplies as future development occurs. Water conservation is most successful when the consumer realizes the benefits of reducing demand. Providing apartments and business tenants with individual water meters provide incentives for these users to conserve water.
The use of reclaimed or recycled water for landscape irrigation and other non-potable needs can significantly reduce the demand on potable water supplies. Before reuse, reclaimed or recycled wastewater receives at least secondary treatment and basic disinfection at a domestic wastewater treatment facility. There are dual pipes in parts of the city for potable and reclaimed water enabling many public properties and private properties to use reclaimed or recycled water for landscaping and other non-potable needs. Expanding the dual pipe system would provide opportunities for other properties to use reclaimed or recycled water. During the development review process, features may be added to a project design that can conserve water over the long term. These features include:
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• Restrict the amount of areas devoted to turf and other plant materials that require significant amounts of water and use xeriscape landscaping methods. • Provide bubbler sprinklers for small boxes and basins • Use low flow fixtures
Climate Change: The effects of climate change in severity of impact for drought for the city is that droughts are likely to become more likely due to erratic and extreme temperatures and precipitation.36 As global climate change causes more variability in weather patterns, longer and more severe droughts are anticipated. The likelihood of experiencing an extreme drought has doubled over the past century. In 2023, California is in its third year of drought and needs to use less water.
The California Department of Water Resources states climate change is responsible for the decrease in the Sierra snowpack levels which provide as much as a third of California’s water supply. Warmer temperatures cause the snow to melt faster and earlier, making water more difficult to store and use. Higher temperatures and increasing variation in precipitation patterns are likely to increase the vulnerability of communities and impacts from extreme events (including drought), compounding already existing stressors.
FEMA NRI Expected Annual Loss Estimates
A Drought NRI Expected Annual Loss score and rating represent a community's relative level of expected building and population loss each year due to droughts when compared to the rest of the United States. Upon review, FEMAs NRI tool resulted in no available data for drought in the twenty-six census tracts for the City of Downey.
36 The World Bank. (2023). What You Need to Know About Climate Change and Drought. Retrieved from https://www.worldbank.org/en/news/feature/2023/09/11/what-you-need-to-know-about-climate- change-and-drought
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3.10 Earthquake Hazard Profile
Table 3.21: Earthquake Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Earthquake 3 12 16 37 65 95
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.10.1 Earthquake Hazard Description
Plate tectonics is a starting point for
understanding the forces within the Earth
that cause earthquakes. Plates are thick
slabs of rock that make up the outermost
100 kilometers of the Earth. The term
"tectonics" describes the deformation of the
Earth's crust, the forces producing such
deformation, and the geologic and
structural features that result. The constant motion of the plates causes stress in the brittle upper crust of the Earth. These tectonic stresses build as the rocks are gradually deformed. The rock deformation, or strain, is stored in the rocks as elastic strain energy.
When the strength of the rock is exceeded, ruptures occur along a fault. The rocks on opposite sides of the fault slide past each other as they spring back into a relaxed position.
The strain energy is released partly as heat and partly as elastic waves called seismic waves. The passage of these seismic waves produces the ground shaking in earthquakes.
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Faults are more likely to produce future earthquakes if they have rapid rates of movement, have had recent earthquakes along them, experience greater total displacements, and are aligned so that movement can relieve the accumulating tectonic stresses. Geologists classify faults by their relative hazards. “Active” faults, which represent the highest hazard, are those that have ruptured to the ground surface during the Holocene period (about the last 11,000 years). In contrast, “potentially active” faults are those that displaced layers of rock from the Quaternary period (the last 1,800,000 years). Determining if a fault is “active” or “potentially active” depends on geologic evidence which may not be available for every fault.
The Alquist-Priolo Earthquake Fault Zoning Act was signed into California Law on December 22, 1972, to mitigate the hazard of surface faulting to structures for human occupancy. The Act was a direct result of the significant damage to homes and businesses that occurred in the 1971 San Fernando Earthquake. It enforces the following to increase earthquake safety:37
• Directs the California Geological Survey (CGS) to create maps of known fault zones.
• Requires the sale of any home located within the fault zone designated on the maps to disclose that the property lies adjacent to a known fault. • Prohibits new construction of homes within these zones unless geologic studies are performed to prove that the fault will not pose a hazard to new structures proposed in these zones.
The State provides extensive regulations on earthquake-related issues. A key area for regulation is the California Building Standards Commission (CBSC). It is authorized by California Building Standards Law to administer the development, adoption, approval, publication, and implementation of California's building codes.
The California Building Standards Code, Title 24, serves as the basis for the design and construction of buildings in California. Improved safety, sustainability, maintaining consistency, new technology, construction methods, and reliability are paramount to the development of building codes. California’s building codes are published in their entirety every three (3) years. Intervening Code Adoption Cycles produce supplement pages halfway (18 months) into each triennial period. Amendments to California’s building
37 Structural Engineers Association of Northern California. (1972). Events/Alquist-Priolo Earthquake Fault Zoning Act. Retrieved from https://legacy.seaonc.org/event/alquistprioloact/ .
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standards are subject to a lengthy and transparent public participation process throughout each code adoption cycle. The California Seismic Safety Commission provides an array of regulatory and advisory information regarding seismic safety.38 Shaking
The amount of energy released during an earthquake is usually expressed as a magnitude and is measured directly from the earthquake as recorded on seismographs. An earthquake’s magnitude is expressed in whole numbers and decimals (e.g., 6.8).
Seismologists have developed several magnitude scales. One of the first was the Richter scale, developed in 1932 by Dr. Charles F. Richter of the California Institute of Technology.
The most used scale today is the Moment Magnitude (Mw) Scale. Moment magnitude is related to the total area of the fault that ruptured and the amount of offset (displacement) across the fault. It is a more uniform measure of the energy released during an earthquake.
The other commonly used measure of earthquake severity is intensity. Intensity is an expression of the amount of shaking at any given location on the ground surface. In general, it decreases with distance from the source of an earthquake, but it may be increased or decreased by several factors.
Amplification of Seismic Shaking
Although seismic waves radiate from their source like ripples on a pond, the radiation is not uniform due to the complex nature of an earthquake rupture, the different paths the waves follow through the Earth, and the different rock and soil layers near the Earth’s surface. Large earthquakes begin to rupture at their hypocenter deep in the Earth and the fault ruptures outward from that point. Because the speed of an earthquake rupture on a fault is similar to the speed of seismic waves, waves closer to the epicenter can be compounded by waves from farther along the rupture, creating a pulse of very strong seismic waves that moves along the fault in the direction of the fault rupture. Seismic waves may also be modified as they travel through the Earth’s crust.
As seismic waves approach the ground surface, they commonly enter areas of loose soil where the waves travel more slowly. As the waves slow down, their amplitude increases, resulting in larger waves with frequencies that are more likely to damage structures.
Waves can also be trapped within soft sediments between the ground surface and deep,
38 California Seismic Safety Commission. (n.d.) Retrieved from ssc.ca.gov
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hard basement rocks, their destructive energy multiplying as they bounce back and forth, producing much greater shaking at the ground surface.
Ground Failure
Fissuring, settlement, and permanent horizontal and vertical shifting of the ground often accompanies large earthquakes. Although not as pervasive or as costly as the shaking itself, these ground failures can significantly increase damage and, under certain circumstances, can be the dominant cause of damage. The following is a list of different ground failure scenarios.
Fault Rupture
The sudden sliding of one part of the earth’s crust past other releases the vast store of elastic energy in the rocks as an earthquake. The resulting fracture is known as a fault, while the sliding movement of earth on either side of a fault is called fault rupture. Fault rupture begins below the ground surface at the earthquake hypocenter, typically between three and ten miles below the ground surface in California. If an earthquake is large enough, the fault rupture will actually travel all the way to the ground surface, severely damaging structures built across its path.
Liquefaction
In addition to the primary fault rupture that occurs right along a fault during an earthquake, the ground many miles away can also fail during the intense shaking. One common type of failure occurs when soft, water-saturated soil settles, causing the water to eject sediment particles as it works its way to the ground surface. This phenomenon, known as liquefaction, turns the soil into a fluid, causing it to lose the ability to support buildings and other structures. Areas susceptible to liquefaction include places where sandy sediments have been deposited by rivers along their course or by wave action along beaches.
Landslides
Landslides are the result of the down-slope movement of unstable hillside materials under the influence of weathering and gravity over time. Strength of rock and soil, steepness of slope, and weight of the hillside material all play an important role in the stability of hillside areas. Weathering and absorption of water can weaken slopes, while the added weight of saturated materials or overlying construction can increase the chances of slope failure.
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Sudden failure can be triggered by heavy rainfall, excavation of weak slopes, and earthquake shaking, among other factors.
3.10.2 Earthquake Hazard History
To indicate the potential for an earthquake event, Table 3.22 lists significant recorded earthquakes in Southern California and the associated magnitudes (excerpted from the SCEDC (2013): Southern California Earthquake Data Center):
Table 3.22: Southern California Historical Earthquakes
Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 5.5 - 6.4 1796 LA Basin Earthquake
Magnitude 6.5 to 7.4 1800 San Diego Earthquake
Magnitude 6.5 to 7.4 1812 Wrightwood (or San Juan Capistrano) Earthquake
Magnitude 6.5 to 7.4 1812 Santa Barbara Earthquake
Magnitude 6.5 to 7.4 1852 Volcano Lake Earthquake
Magnitude 5.5 - 6.4 1855 Los Angeles Region Earthquake
Magnitude > 7.5 1857 Fort Tejon Earthquake
Magnitude 5.5 - 6.4 1858 San Bernardino Earthquake
Magnitude 5.5 - 6.4 1862 San Diego Earthquake
Magnitude > 7.5 1872 Owens Valley Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 5.5 - 6.4 1881 Parkfield Earthquake
Magnitude 5.5 - 6.4 1883 Santa Barbara Channel Earthquake Magnitude 6.5 to 7.4 1890 San Jacinto or Elsinore Fault Region Earthquake
Magnitude 6.5 to 7.4 1892 San Jacinto or Elsinore Fault Region Earthquake
Magnitude 6.5 to 7.4 1892 Laguna Salada Earthquake
Magnitude > 7.5 1892 Imperial Valley Earthquake
Magnitude 5.5 - 6.4 1899 Cajon Pass Earthquake
Magnitude 6.5 to 7.4 1899 San Jacinto Earthquake
Magnitude 5.5 - 6.4 1901 Parkfield Earthquake
Magnitude 5.5 - 6.4 1906 Imperial Valley Earthquake
Magnitude 5.5 - 6.4 1908 Death Valley Region Earthquake Magnitude 5.5 - 6.4 1910 Elsinore Earthquake
Magnitude 5.5 - 6.4 1915 Imperial Valley Earthquake
Magnitude 5.5 - 6.4 1916 South of Death Valley Earthquake Magnitude 6.5 to 7.4 1918 San Jacinto Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 5.5 - 6.4 1922 Parkfield Earthquake
Magnitude 5.5 - 6.4 1923 North San Jacinto Fault Earthquake Magnitude 5.5 - 6.4 1925 Santa Barbara Earthquake
Magnitude 6.5 to 7.4 1927 Lompoc Earthquake
Magnitude 5.5 - 6.4 1933 Long Beach Earthquake
Magnitude 5.5 - 6.4 1934 Parkfield Earthquake
Magnitude 5.5 - 6.4 1937 San Jacinto Fault ("Terwilliger Valley") Earthquake
Magnitude 6.5 to 7.4 1940 Imperial Valley Earthquake
Magnitude 5.5 - 6.4 1941 Santa Barbara Earthquake
Magnitude 4.5 - 5.4 1941 Torrance-Gardena Earthquakes
Magnitude 6.5 to 7.4 1942 Fish Creek Mountains Earthquake Magnitude 5.5 - 6.4 1946 Walker Pass Earthquake
Magnitude 6.5 to 7.4 1947 Manix Earthquake
Magnitude 5.5 - 6.4 1948 Desert Hot Springs Earthquake
Magnitude > 7.5 1952 Kern County Earthquake
Magnitude 5.5 - 6.4 1952 Bakersfield Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 5.5 - 6.4 1954 San Jacinto Fault Earthquake
Under magnitude 4.5 1966 Imperial Fault Earthquake
Magnitude 5.5 - 6.4 1966 Parkfield Earthquake
Magnitude 6.5 to 7.4 1968 Borrego Mountain Earthquake
Magnitude 4.5 - 5.4 1970 Lytle Creek Earthquake
Magnitude 6.5 to 7.4 1971 San Fernando (Sylmar) Earthquake Magnitude 4.5 - 5.4 1973 Point Mugu Earthquake
Magnitude 4.5 - 5.4 1975 Galway Lake Earthquake
Magnitude 4.5 - 5.4 1978 Santa Barbara Earthquake
Magnitude 4.5 - 5.4 1979 Malibu Earthquake
Magnitude 5.5 - 6.4 1979 Imperial Valley Earthquake
Magnitude 5.5 - 6.4 1980 White Wash Earthquake
Magnitude 4.5 - 5.4 1982 "Anza Gap" Earthquake
Magnitude 5.5 - 6.4 1986 North Palm Springs Earthquake
Magnitude 4.5 - 5.4 1986 Oceanside Earthquake
Magnitude 6.5 to 7.4 1987 Elmore Ranch/Superstition Hills Earthquakes Magnitude 5.5 - 6.4 1987 Whittier Narrows Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 4.5 - 5.4 1988 Tejon Ranch Earthquake
Magnitude 4.5 - 5.4 1988 Upland Earthquake
Magnitude 4.5 - 5.4 1988 Pasadena Earthquake
Magnitude 4.5 - 5.4 1989 Malibu Earthquake
Magnitude 4.5 - 5.4 1989 Newport Beach Earthquake
Magnitude 4.5 - 5.4 1989 Montebello Earthquake
Magnitude 4.5 - 5.4 1990 Upland Earthquake
Magnitude 5.5 - 6.4 1991 Sierra Madre Earthquake
Magnitude 5.5 - 6.4 1992 Joshua Tree Earthquake
Magnitude 6.5 to 7.4 1992 Landers Earthquake
Magnitude 5.5 - 6.4 1992 Big Bear Earthquake
Magnitude 5.5 - 6.4 1992 Mojave (Garlock) Earthquake
Magnitude 4.5 - 5.4 1993 Wheeler Ridge Earthquake
Magnitude 6.5 to 7.4 1994 Northridge Earthquake
Magnitude 5.5 - 6.4 1995 Ridgecrest Earthquakes
Magnitude 4.5 - 5.4 1996 Coso Earthquake
Magnitude 4.5 - 5.4 1997 Calico Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 4.5 - 5.4 1998 Coso Earthquake
Magnitude 4.5 - 5.4 1998 Crafton Hills (Redlands) Earthquake Magnitude 4.5 - 5.4 1998 San Bernardino Earthquake
Magnitude 4.5 - 5.4 1998 Whiskey Springs (Big Bear City) Earthquake Magnitude 6.5 to 7.4 1999 Hector Mine Earthquake
Under magnitude 4.5 2001 West Hollywood Earthquake
Magnitude 4.5 - 5.4 2001 Anza Earthquake
Magnitude 5.5 - 6.4 2002 Laguna Salada Earthquake
Magnitude 6.5 to 7.4 2003 San Simeon Earthquake
Magnitude 4.5 - 5.4 2005 Mettler Earthquake
Magnitude 4.5 - 5.4 2008 Chino Hills Earthquake
Magnitude 4.5 - 5.4 2009 Inglewood Earthquake
Magnitude 5.5 - 6.4 2009 Baja California Earthquake
Magnitude 6.5 to 7.4 2010 Sierra El Mayor Earthquake
Magnitude 4.5 - 5.4 2011 Calexico Earthquake
Magnitude 4.5 - 5.4 2012 Brawley Earthquake
Magnitude 4.5 - 5.4 2012 Westmoreland Earthquake
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Under Magnitude 4.5 Magnitude 4.5 - 5.4 Magnitude 5.5 - 6.4 Magnitude 6.5 to 7.4 Magnitude > 7.5
Magnitude Year Earthquake Name
Magnitude 4.5 - 5.4 2013 Isla Vista Earthquake
Magnitude 4.5 - 5.4 2014 Brea Earthquake
Magnitude 4.5 - 5.4 2015 Stovepipe Wells Earthquake
Magnitude 4.5 - 5.4 2016 San Jacinto Earthquake
Magnitude 4.5 - 5.4 2016 Borrego Springs Earthquake
Magnitude 4.5 - 5.4 2018 Santa Cruz Island Earthquake
Magnitude 5.5 - 6.4 2019 Ridgecrest Earthquake
Magnitude 6.5 - 7.4 2019 Ridgecrest Earthquake
Magnitude 5.5 - 6.4 2020 Lone Pine Earthquake 39
Southern California Historic Earthquakes
One of the best indicators of earthquake potential is learning the earthquake history of the area. The following is a discussion on large earthquakes that affected the City and Southern California in general, which were also included in Table 3.22. 1857 Fort Tejon Earthquake
On January 9, 1857, one of the greatest recorded earthquakes in the U.S. occurred in Southern California. The Fort Tejon earthquake measured 7.9 on the Richter scale and left a surface rupture scare of over 350 kilometers (225 miles) along the San Andreas
39 Southern California Earthquake Data Center. (2023). Earthquake Information – Chronological Earthquake Index. Retrieved from https://scedc.caltech.edu/earthquake/chronological.html
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Fault. Strong shaking was said to have lasted for over a minute, and water from the Los Angeles River was reportedly thrown out of its bed. The damage was not nearly as serious as it would be today since Southern California was sparsely populated at the time. Were the Fort Tejon earthquake to occur today, the damage could easily run into billions of dollars, and the loss of life could be substantial. The present-day communities of Wrightwood and Palmdale lie upon or near the 1857 rupture area. 1933 Long Beach Earthquake
In 1933, the Long Beach 6.4 magnitude earthquake struck the Los Angeles Basin on March 10. The earthquake occurred on the Newport-Inglewood Fault, causing serious damage in Long Beach and other communities. The earthquake resulted in 120 deaths and over $50 million in property damage. Most of the damaged buildings were of unreinforced masonry construction.
1971 Sylmar Earthquake (San Fernando)
On February 9, 1971, the Los Angeles Basin shook for over one minute. There were 65 deaths and a financial cost of over $500 million. The earthquake resulted in a crack in the Van Norman Dam where an 80-square mile area had to be evacuated due to fear the dam would break. Numerous people were trapped in buildings and fires were started from natural gas line breaks. Two hospitals collapsed killing nine people. The Veterans Administration Hospital had seven deaths and the Olive View Hospital had two deaths.
Following this earthquake, the Alquist Hospital Seismic Act was passed establishing structural and non-structure classifications for hospital building seismic –safety levels. 1987 Whittier Narrows Earthquake
In October 1987, the Whittier Narrows Earthquake struck the Los Angeles area with a 5.9 magnitude earthquake. This earthquake occurred on a fault system not previously known for seismic activity. There were 8 deaths and 200 injuries. The earthquake damage was estimated at $358 million.
1994 Northridge Earthquake
Thousands of homes and businesses were without electricity for days following the event; tens of thousands had no gas; and nearly 50,000 had little or no water. According to NASA Ames Research Center, building officials inspected over 66,500 structures and determined 4,000 were severely damaged and deemed uninhabitable. An additional
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11,000 buildings were moderately damaged and authorized only for limited occupancy.
Several collapsed bridges and overpasses created commuter havoc on the freeway system. In addition, ground shaking caused extensive damage and triggered liquefaction.
This ignited dozens of fires throughout the area resulting in further damage.
However, the earthquake occurred early in the morning on a holiday. This circumstance considerably reduced the impact. Many collapsed buildings were unoccupied, and most businesses were not yet open. Still, the direct and indirect economic losses ran into the tens of billions.
2019 Ridgecrest Earthquake Sequence
In July of 2019 there were two earthquakes in Searles Valley, Southern California, a magnitude 6.4 on July 4 and a magnitude 7.1 on July 6. The July 4th earthquake was felt by more than 47,000 people, even as far away as northern California and Phoenix, Arizona felt shaking. There were several aftershocks until about 34 hours later when there was a M7.1 on the fault orthogonal (rotated 90 degrees) from the M6.4, The July 6th earthquake was the largest earthquake in southern California since the Hector Mine Earthquake in 1999. Over the past 40 years, eight other earthquakes have occurred within 31 miles of the July 4th earthquake.40
Even when the epicenter of a major earthquake is not located directly within the City, the aftershocks associated with that earthquake can result in significant damage. The hazards associated with aftershock earthquakes are the same as mainshock earthquakes and may cause significant damage and disruption. The primary difference between the two types of earthquakes is that aftershock earthquakes are categorized by the following two guidelines. First, it must occur within one rupture length of the mainshock rupture surface, or alternatively, within an "aftershock zone" based upon early aftershock activity and defined by seismologists. Second, it must occur within that designated area before the seismicity rate in that area returns to its "background", pre-mainshock level. Figure 3.15 from the Southern California Earthquake Data Center details the locations and magnitudes for historic Southern California earthquakes.41
40 USGS. (2019). The 2019 Ridgecrest, California Earthquake Sequence. Retrieved from https://earthquake.usgs.gov/storymap/index-ridgecrest.html 41 Southern California Earthquake Data Center. (1994-Present). Historical Earthquakes and Significant Faults in Southern California. Retrieved from https://scedc.caltech.edu/earthquake/significant.html
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Figure 3.15: Southern California Historic Earthquakes Map42
3.10.3 Earthquake Hazard Probability, Frequency, and
Magnitude
The Steering Committee ranked earthquake as the greatest threat to the City as the County of Los Angeles is in a seismic fault zone near the Newport-Inglewood Fault according to a Preliminary Alquist-Priolo Earthquake Fault Zone map provided by the California Department of Conservation website and is located in a liquefaction zone. Due to the presence of nearby seismic fault zones and numerous past earthquakes in or near the City, the entirety of the City of Downey should be considered at risk for an earthquake.
Fault Zones
42 Ibid.
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There are many faults and fault zones throughout Southern California. After reviewing maps of the U.S., California and specifically the Southern California area, the research showed potential earthquake areas that could impact the City. Faults that were reviewed include: the San Andreas, Newport-Inglewood, Rose Canyon, Cristianos, San Joaquin Hills, Rose Canyon, Coronado Bank, Whittier-Elsinore, Palos Verdes, San Diego Trough, and San Clemente Faults. These faults, all considered, can produce earthquakes in the
4.5 – 8+ magnitude range. This report focused on the four faults that could most seriously impact the area:
1. San Andreas Fault
2. Newport-Inglewood Fault
3. Whittier-Fault
4. Palos Verdes Fault
A major earthquake along any of these four faults could result in substantial casualties and damage resulting from collapsed buildings, damaged roads and bridges, fires, flooding, and other threats to life and property. There may still be unmapped earthquake faults throughout Southern California that could also affect the City. The tables below provide the local earthquake faults in the City and Southern California areas.
The San Andreas Fault
Table 3.23: San Andreas Fault Information
Type of fault: Right-lateral strike-slip
Length: 1200 kilometers (km)
Nearby
Communities:
Parkfield, Frazier Park, Palmdale, Wrightwood, San Bernardino, Banning, Indio
Last Major Rupture: January 9, 1857 (Mojave segment); April 18, 1906 (Northern segment)
Slip rate: 20-35 millimeters/year (mm/yr.)
Interval Between
Major Ruptures:
Average of about 140 years on the Mojave segment; recurrence interval varies greatly from under 20 years (at Parkfield only) to over 300 years
Probable
Magnitudes: 6.8 to 8.0
This fault marks the boundary between the North American and Pacific tectonic plates and can produce earthquakes in the magnitude 8+ range. It has been scientifically determined
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through a carbon dating process that a major earthquake on this fault has occurred approximately every 145 years plus or minus 20 years. The last major earthquake on the Mojave segment of the fault occurred in 1857 (159 years ago as of 2016). The San Andreas Fault is considered one of the most active faults in the world today, and a major earthquake up to an 8.3 magnitude is expected to occur again within the next 20 years.
The ground shaking of an 8.3 magnitude earthquake on the Southern San Andreas Fault would result in serious damage in Southern California, including the City.
The Newport-Inglewood Fault
Table 3.24: Newport-Inglewood Fault Information
Type of fault: Right lateral; local reverse slip associated with fault steps Length: 75 km
Nearby
Communities:
Culver City, Inglewood, Gardena, Compton, Signal Hill, Long Beach, Seal Beach, Huntington Beach, Newport Beach, Costa Mesa
Last Major Rupture March 10, 1933, MW 6.4
Slip rate: 0.6 mm/yr.
Probable
Magnitudes: 6.0-7.4
The Newport-Inglewood Fault is considered the second most active fault in California. It runs from the City of Inglewood through the City of Huntington Beach and out into the Pacific Ocean in the Newport Beach area. This fault can produce earthquakes in the range of 6.3 to 7.5 magnitude. The 6.5 magnitude, 1933 Long Beach earthquake, occurred on the Newport-Inglewood fault causing 120 deaths and severe damage. Unreinforced masonry buildings collapsed leaving people trapped beneath the rubble.
Earthquakes are to be considered a major threat to the City. When scientists refer to the San Andreas Fault, they often call it “The Big One.” In 1990, the Los Angeles Times newspaper did a series of articles on the Newport-Inglewood Fault and described it as “The Bigger One.” Both faults would cause considerable damage; however, a 7.4 magnitude Newport-Inglewood earthquake could be more severe to the City than an 8.0 on the San Andreas due to the fault’s proximity to the City. The cost estimates of damage are much greater for the Newport-Inglewood worst-case scenario than the San Andreas worst-case scenario.
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Whittier-Elsinore Fault
Table 3.25: Whittier Fault Information
Type of fault: Right-lateral strike-slip with some reverse slip Length: 40 km
Nearby
Communities: Yorba Linda, Hacienda Heights, Whittier
Most Recent
Surface Rupture Holocene
Slip rate: Between 2.5 and 3.0 mm/yr.
Probable
Magnitudes: 6.0-7.2
The Whittier Fault runs along the Chino Hills range between Chino Hills and Whittier.
Earthquakes with surface rupture on the Whittier Fault are estimated to have return intervals for a M6.5 and M7.5 of 100 and 1,200 years, respectively. An unpublished paleo seismic investigation suggests that the Whittier segment has not moved for 2,000 years.
Since the average interval between major characteristic (extreme) events on the Whittier segment is estimated to be on the order of 1,200 years, the fault is considered long overdue. The Whittier fault joins the Chino Fault near Prado Dam where they merge into the Elsinore Fault.
Table 3.26: Elsinore Fault Information
Type of fault: Right-lateral strike-slip
Length: 180 km
Nearby
Communities: Temecula, Lake Elsinore, Julian
Last Major Rupture May 15, 1910; Magnitude 6.0
Slip rate: Roughly 4.0 mm/yr.
Probable
Magnitudes: 6.5-7.5
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The Elsinore Fault lies along the eastern base of the Santa Ana Mountains. It is one of the largest in Southern California and, historically, has been one of the quietest. The fault has only seen one historical event greater than magnitude 5.2, which was the M6.0 Elsinore Earthquake of 1910.
At the northern end, the fault splays into several faults, creating the Whittier-Elsinore Fault Zone. A “characteristic” Magnitude M6.9 on the northwest segment of the Whittier-Elsinore Fault Zone has been estimated to have a return period of 450 years. This “characteristic” earthquake would be expected to cause ground movement on the order of 3 to 6 feet, with peak horizontal ground accelerations up to one multiplier of gravity (1 g). Most structures built prior to 1997 were designed to withstand peak ground accelerations, described in further detail below, of up to 0.4 g, so a “characteristic” earthquake along this fault zone would have devastating consequences.
Palos Verdes Fault
Table 3.27: Palos Verdes Fault Information
Type of fault: Right reverse
Length: Roughly 80 km
Nearby
Communities: San Pedro, Palos Verdes Estates, Torrance, Redondo Beach Most recent surface
rupture: Holocene offshore; Late Quaternary onshore
Slip rate: Between 0.1 and 3.0 mm/yr.
Probable
magnitudes:
6.0 – 7.0 (or greater); fault geometries may allow only partial rupture at any one time.
The Palos Verdes Hills Fault is capable of a 6.0 to 7.0 magnitude earthquake. It has two main branches and continues southward as the Palos Verdes-Coronado Bank Fault Zone.
This fault is located off the coast of Redondo Beach and Torrance, and continues southward through the Palos Verdes peninsula and offshore, outside the San Pedro Bay.
The closest point lies southwest of the City raising the issue of the fault causing shaking and liquefaction.
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Peak Ground Acceleration
Peak Ground Acceleration (PGA) mapping represents peak horizontal acceleration of the ground on firm-rock conditions. The approach of representing peak horizontal ground acceleration on firm-rock is a common and widely used method of showing ground accelerations. The development of probabilistic acceleration maps is a result of three types of basic input parameters:
1) Attenuation of ground shaking with distance from the earthquake source. 2) Frequency of earthquakes within an area or region, termed recurrence; and 3) The character and extent of regions and faults that generate earthquakes.
According to the following Peak Ground Acceleration Map and the Department of Conservation Division of Mines and Geology 1998 Seismic Hazard Zone Report for Los Angeles County, the City is located in an area that will experience a PGA ranging from
0.37 g to 0.38 g with 10% exceedance in 50 years (0.0021 annual probability).
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Figure 3.16: Ground Acceleration Map (as of April 2023)
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Earthquakes are measured both in terms of their inherent magnitude and in terms of their local intensity. There are several standard measures of earthquakes, including the Richter Scale and the Modified Mercalli Intensity (MMI) scale. The Richter Scale measures the magnitude or amount of energy an earthquake releases. Magnitude is measured by seismographs. The MMI scale is an observed measurement of the earthquake’s intensity felt at the earth’s surface and it varies depending on the observer’s location at the earthquake’s epicenter. The MMI Scale is comprised of 12 increasing levels, designated by Roman numerals, which range from imperceptible shaking to catastrophic destruction. Furthermore, the MMI can be used to map earthquake impacts.43 The table below correlates the MMI Scale with the Richter Scale and effects of ground shaking.
Table 3.28: Mercalli Intensity vs. Richter Scale
Earthquakes can trigger other types of ground failures, which could contribute to the damage.
These include flow failures, landslides, and liquefaction. Liquefaction is not a type of ground failure; however, it is a physical process that occurs when shaking can mix groundwater and soil, liquefying and weakening the ground that supports buildings and severing utility lines. This is a
43 Pacific Northwest Seismic Network. (n.d.). Magnitude/Intensity. Retrieved from https://pnsn.org/outreach/about-earthquakes/magnitude-intensity .
Intensity Effects Richter
Scale
(approximate)
I. Instrumental Not felt. 1 – 2
II. Just Perceptible Felt by only a few people, especially on upper floors of tall buildings. 3 III. Slight Felt by people lying down, seated on a hard surface, or in the upper stories of tall buildings. 3.5
IV. Perceptible Felt indoors by many, by few outside; dishes and windows rattle. 4 V. Rather Strong Generally felt by everyone; sleeping people may be awakened. 4.5 VI. Strong Trees sway, chandeliers swing, bells ring, some damage from falling object. 5
VII. Very Strong General alarm; walls and plaster crack. 5.5 VIII. Destructive Felt in moving vehicles; chimneys collapse; poorly constructed buildings seriously damaged. 6
IX. Ruinous Some houses collapse; pipes break. 6.5
X. Disastrous Obvious ground cracks; railroad tracks bent; some landslides on steep hillsides. 7
XI. Very Disastrous Few buildings survive; bridges damaged or destroyed; all services interrupted (electrical, water, sewage, railroad; severe landslides. 7.5 XII. Catastrophic Total destruction; objects thrown into the air; river courses and topography altered. 8
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problem in floodplains where the water table is relatively high, and the soil is more susceptible to liquefaction.44
Earthquakes occur with little to no warning. Scientists cannot predict or forecast earthquakes. An earthquake early warning system uses earthquake science and technology of monitoring systems to alert devices and people when shaking waves generated by an earthquake are expected to arrive at a location. Although it may not sound like a lot of time (compared to other natural hazards), seconds to tens of seconds of advance warning can allow people and systems to take action and protect life and property from destructive shaking.45 In partnership with University of California Berkeley and USGS ShakeAlert, California OES developed the Earthquake Warning California system. The system uses ground-motion sensors to detect earthquakes that have already started and estimate their size, location, and impact.
Once it detects a significant magnitude, the MyShake App (registration is required), Wireless Emergency Alerts, or Android Alerts sends a warning to mobile phone users when shaking is about to occur in the user’s area. The speed of the alert varies depending on the individual’s distance from the origin of the earthquake. Therefore, if the individual is closer to the earthquake’s epicenter the warning will arrive faster than someone that is further away. The table below outlines the alerting thresholds for the Earthquake Warning California system.46 Table 3.29: Earthquake Warning California Alerting Thresholds Warning System Threshold
Wireless Emergency Alerts
The Wireless Emergency Alerts is used in response to magnitude 5.0 or greater earthquakes and will alert people who will experience a shaking level of MMI IV (light) or greater.
MyShake App
The MyShake App is used in response to magnitude 4.5 or greater earthquakes and will alert people who will experience a shaking level of MMI III (weak) or greater.
Android Alerts
The Android Alerts are used in response to magnitude 4.5 or greater earthquakes and will alert people who will experience a shaking level of MMI III (weak) or greater.
44 United States Geological Survey. (n.d.). What are the Effects of Earthquakes? Retrieved from:
https://www.usgs.gov/programs/earthquake-hazards/what-are-effects-earthquakes . 45 United States Geological Survey. (n.d.). What is the difference between earthquake early warning, earthquake forecasts, earthquake probabilities, and earthquake prediction? Retrieved from https://www.usgs.gov/faqs/what- difference-between-earthquake-early-warning-earthquake-forecasts-earthquake-probabilities. 46 California Governor’s Office of Emergency Services. (n.d.). Earthquake Warning California: Types of Alerts.
Retrieved from https://earthquake.ca.gov/get-alerts/ .
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HAZUS Probabilistic Magnitude 5.0
The total economic loss estimated for the earthquake is 1,927.99 Million, which includes building and lifeline related losses based on the region's available inventory. HAZUS estimates that about 5,108 buildings will be at least moderately damaged. This is over 11 percent of the buildings in the region. There are an estimated 97 buildings that will be damaged beyond repair. The table below summarizes the expected damage by general occupancy for the buildings in the City of Downey planning area.
Table 3.30: HAZUS Earthquake Expected Building Damage by Occupancy Damage
Level47 None Slight Moderate Extensive Complete
Occupancy Count % Count % Count % Count % Count %
Agriculture 10.09 0.04 5.31 0.04 3.43 0.08 0.98 0.17 0.19 0.19 Commercial 1504.24 5.78 763.22 5.45 603.54 13.65 175.99 29.78 26.00 26.71 Education 44.95 0.17 20.66 0.15 12.02 0.27 3.01 0.51 0.36 0.37 Government 30.63 0.12 14.26 0.10 11.11 0.25 3.47 0.59 0.53 0.54 Industrial 635.48 2.44 326.05 2.33 298.37 6.75 95.10 16.09 15.01 15.42 Other
Residential 4165.83 16.01 2252.60 16.08 850.71 19.25 176.89 29.93 24.97 25.65 Religion 84.03 0.32 40.93 0.29 27.60 0.62 8.16 1.38 1.27 1.31 Single
Family 19552.65 75.12 10589.70 75.57 2613.30 59.12 127.33 21.55 29.02 29.81 TOTAL 26,028 14,013 4,420 591 97
The table below summarizes the expected damage to essential facilities in the City of Downey planning area.
47 Hazus Earthquake Model Technical Manual, Hazus 4.2 SP3. (2020). 5.3.3.1 Strutucal Damage descriptions.
Retrieved from https://www.fema.gov/sites/default/files/2020-10/fema_hazus_earthquake_technical_manual_4-
2.pdf
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Table 3.31: HAZUS Earthquake Expected Damage to Essential Facilities Facility 48 Total At Least Moderate
(Greater than 50% damage) Complete
(Greater than 50% damage)
With
Functionality
(Greater than 50% on day 1)
Medical 4 1 0 3
Schools and related
assets 53 30 0 23
Emergency
Operations Center 2 1 0 1
Law Enforcement 2 0 0 2
Fire Assets 9 4 0 3
TOTAL 70 36 0 32
*Includes all assets within city boundaries and not just those from the city.
The total building-related losses were 1,875.34 Million, 17 percent of the estimated losses were related to the business interruption of the City of Downey. The residential occupancies made up 28 percent of the total loss. See Appendix A – Additional Hazard Analysis Information for building related economic loss estimates, Table 11.
HAZUS estimates the number of households that are expected to be displaced from their homes due to the earthquake and the number of displaced people that will require accommodation in temporary public shelters. Of these, 346 people (out of a total population of 187,417) will seek temporary shelter in public shelters.
For the transportation and utility lifeline systems, HAZUS computes the expected damage to transportation systems and the direct repair cost for each component only. There are no losses computed by HAZUS for business interruption due to lifeline outages. See Appendix A – Additional Hazard Analysis Information for transportation system economic losses, Table 12.
Earthquake probabilities are calculated by projecting earthquake rates based on earthquake history and fault slip rates and the result is expressed as the probability that an earthquake of a specified magnitude will occur on a fault or within an area.49 According to USGS, there is 75% probability of at least one (1) earthquake before 2043 with a magnitude of 7.0 that could cause widespread damage in Southern California (based on a 30-year period, beginning in 2014.50 The
48 Hazus Earthquake Model Technical Manual, Hazus 4.2 SP3. (2020). 6.1 Essential Facility Classification Retrieved from https://www.fema.gov/sites/default/files/2020-10/fema_hazus_earthquake_technical_manual_4-
2.pdf
49 California Department of Conservation. (n.d.). Earthquakes. Retrieved from https://www.conservation.ca.gov/cgs/earthquakes .
50 California Earthquake Authority. (2014). California Earthquake Risk Map and faults by County. Retrieved from https://www.earthquakeauthority.com/california-earthquake-risk/faults-by-county
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2014, Working Group on California Earthquake Probabilities (WGCEP) issued its third earthquake forecast, referred to as the Uniform California Earthquake Rupture Forecast (UCERF3), which determined the likelihood of magnitude 7.0 earthquakes by 2043. In the Los Angeles area, the probabilities are:51 52
• 60% that an earthquake measuring magnitude 6.7 or greater. • 46% that an earthquake measuring magnitude 7.0 or greater. • 31% that an earthquake measuring magnitude 7.5 or greater.
The USGS National Seismic Hazard Maps reflect the best and most current understanding of earthquake hazard in an area, the distribution of damaging earthquake shaking across the United States and compares earthquake shaking hazard areas with other areas across the United States.
The figure below illustrates the most recent USGS National Seismic Hazard Map which represents the expected number of occurrences of damaging earthquake shaking in 10,000 years. A “damaging earthquake shaking” in this map is that of MMI level VI or higher.53
51 United States Geological Survey. (2015). UCERF3: A New Earthquake Forecast for California's Complex Fault System. Retrieved from https://pubs.usgs.gov/fs/2015/3009/pdf/fs2015-3009.pdf . 52 United States Geological Survey. (2015). What is the probability that an earthquake will occur in the Los Angeles Area? Retrieved from https://www.usgs.gov/faqs/what-probability-earthquake-will-occur-los-angeles- area-san-francisco-bay-area
53 United States Geological Survey, Earthquake Hazards Program. (2022). Introduction to the National Seismic Hazard Maps. Retrieved from https://www.usgs.gov/programs/earthquake-hazards/science/introduction- national-seismic-hazard-maps.
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Figure 3.17: USGS National Seismic Hazard Map
The earthquake annualized frequency value represents the modeled frequency of an earthquake hazard occurrence per year. A higher annualized frequency value results in higher EAL and Risk Index scores. The table below outlines the annualized frequency for earthquakes, based on FEMA NRI data, for the City.
Table 3.32: Earthquake Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(2021 Dataset)
Annualized
Frequency
550501 n/a 0.964% chance per year
550502 n/a 0.964% chance per year
550601 n/a 0.964% chance per year
550602 n/a 0.964% chance per year
550700 n/a 0.964% chance per year
550801 n/a 0.964% chance per year
City of Downey Hazard Mitigation Plan 3-89
City of Downey
Census Tracts Events on Record
(2021 Dataset)
Annualized
Frequency
550802 n/a 0.964% chance per year
550901 n/a 0.964% chance per year
550902 n/a 0.964% chance per year
551001 n/a 0.964% chance per year
551002 n/a 0.964% chance per year
551101 n/a 0.961% chance per year
551102 n/a 0.963% chance per year
551201 n/a 0.963% chance per year
551203 n/a 0.960% chance per year
551204 n/a 0.964% chance per year
551300 n/a 0.964% chance per year
551401 n/a 0.964% chance per year
551402 n/a 0.964% chance per year
551501 n/a 0.964% chance per year
551502 n/a 0.962% chance per year
551700 n/a 0.960% chance per year
551801 n/a 0.960% chance per year
551802 n/a 0.961% chance per year
553400 n/a 0.960% chance per year
980012 n/a 0.962% chance per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
Vulnerability and Impacts
Population: An earthquake impacts the life safety and health of the city by potentially causing injury or death to the public due to debris, failed infrastructure, and other hazards. The entire population of Downey falls within areas with the potential for either violent or extreme level of ground shaking. Some populations in the Planning Area may be more vulnerable to an earthquake event than others. For example, those with mobility issues as well as the elderly may have challenges with evacuating or traveling to a shelter without assistance if they cannot stay in their homes.
City of Downey Hazard Mitigation Plan 3-90
In Downey, 12,419 residents (11.3 percent) are living with a disability. Among the disability types tallied (a resident can have more than one disability type) the most prevalent were ambulatory (serious difficulty walking or climbing stairs) and independent living difficulties (difficulty doing errands alone such as visiting a doctor’s office or shopping). One quarter of residents with a disability indicated an ambulatory difficulty and 21 percent indicated an independent living difficulty. The remaining disabilities tallied include cognitive difficulties (18 percent), self-care difficulties (14 percent), hearing difficulties (12 percent), and vision difficulties (11 percent).
As age increases, so does the percentage of each age group that has disability; for residents who are 75 years and over, more than half have a disability. The 65 to 74 years age group constitutes the second-highest number of disabilities. Disability and poverty are closely tied due to employment limitations. For residents with disabilities, more than 13 percent live in poverty.
Many senior-headed households have special needs due to their relatively low incomes, disabilities or limitations, and dependency needs. Specifically, many people aged 65 years and older live alone. In Downey, 12,552 residents are 65 years and older, representing 11.4 percent of the population. For residents 65 years and older, 9.5 percent live in poverty.
Along with an aging population, Downey is becoming more diverse racially and ethnically.
Hispanic residents make up most of the City’s population. Over 60% of residents speak a language other than English in the home, with 55.4% of residents speaking Spanish. 20.6% of residents speak English less than very well. Response and recovery efforts may be more challenging for those who do not speak English well even though the city has made continued efforts to provide resources to ensure all population needs are met.
Extremely low-income (ELI) is defined as households with income less than 30 percent of area median income (AMI). 13.8 percent of the City's total households (4,525 households) are classified as extremely low income and may have greater difficulty recovering from a major earthquake.
Table 3.33: Vulnerability and At-Risk Populations: Earthquake Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
City of Downey Hazard Mitigation Plan 3-91
Vulnerability and At-
Risk/Underserved Category Count Percent
Language other than English 70,341 64% of residents
Spanish Spoken at Home 60,889 55.4% of residents
Speak English less than very well 22,641 20.6% of residents People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services Property:
An earthquake impacts property damage and critical infrastructure of the city by potentially damaging or destroying buildings, infrastructure, power transmission lines, and more. All of Downey, including all critical facilities, and residential building units fall within areas with the potential for violent ground shaking. The northern tip of the city is prone to the highest potential for shaking.
The greatest potential danger is the collapse of older residential units constructed from unreinforced masonry and explosions of petroleum and fuel lines. The State Division of Mines and Geology has designated the entire city as a liquefaction zone; the city requires geotechnical reports for construction projects.
Based upon observations and experiences of the Code Enforcement Division, the City estimates that in 2020, fewer than 25 housing units were in severe need of replacement or substantial rehabilitation due to housing conditions. These units, for example, may be suffering from neglect and these buildings may be structurally unsound. These structures may be at greater risk of a seismic event. This does not include homes or structures that need more traditional rehabilitation such as repairs to maintain a safe and healthy living environment.
Earthquakes pose numerous risks to critical facilities and infrastructure. Risks, or the harm or losses, which are likely to result from exposure to earthquakes and liquefaction include:
• Damage to property, especially older buildings that predate improvements to building codes that occurred in the 1970s. The 2014 earthquake that impacted Napa demonstrated that structures built before 1950 sustained the most damages. • Fire from broken gas lines and power lines
• Flooding from damaged levees, of which the majority of the city is in a levee protected area
• Casualties (fatalities and injuries) from falling debris or secondary hazards
City of Downey Hazard Mitigation Plan 3-92
• Utility outages
• Economic losses for repair and replacement of critical facilities, roads, buildings, etc. • Indirect economic losses, such as income lost during the downtime that results from damage to private property or public infrastructure
• Roads that are blocked or damaged can prevent access throughout the area and can isolate residents and emergency service providers needing to reach vulnerable populations or to make repairs
Table 3.34: Property Vulnerability to Earthquake
Vulnerable Category Count Percent
Structures Built before 1960 17,847 More than 50% of occupied housing units
Source: US Census Bureau 2022 ACS
Table 3.35: Assets/Structures Vulnerability and Impact Summary: Earthquake Note: No major assets reside in the northern tip of the city susceptible to the highest risk of ground shaking.
Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Airport*
(No major airports in Downey) 0 0 There are no major
airports in Downey
Bridges 31 100%
Based on National
Bridge Inventory and a
Place Code
designating Downey as
the location
Government
(City Hall and Public Works) 2 100%
Columbia Memorial Space
Center 1 100%
Hospitals 3 100%
Major Shopping Centers 5 100%
National Register of Historic
Places 2 100%
Library 1 100%
City of Downey Hazard Mitigation Plan 3-93
Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Schools 28 100%
The Downey Unified
School District is
comprised of 13
elementary schools, 4
middle schools, 3 high
schools, and an adult
school. Other private
institutions and
academies also exist in
the city.
Fire Stations 4 100%
Police Stations 1 100%
Wells 20 100%
Lift Stations 2 100%
Source: Los Angeles County Assessors, National Bridge Inventory, City of Downey Economic: An earthquake impacts the economy of the city by either disrupting or destroying various businesses and/or services for the duration of, and after the event. Earthquakes can have a severe impact on local and regional economies. Another economic impact of an earthquake is the economic losses as a result of transportation and utility lifeline losses and the direct repair cost for each component. The debris removal required following an earthquake may also generate economic effects on the city.
Changes in Development and Future Development:
An earthquake impacts the changes in development and impact of future development for the city by potentially damaging current, in-progress developments, and reducing the prospect of future developments in terms of potential investors.
Downey is located within the Southern California region which is experiencing significant change.
Addressing these changes is a challenge for any community, but more so for Downey since most of this city was primarily developed during the time period of the 1950s and 1960s. Buildings and infrastructure have also matured. The mature status of the city creates opportunities for reinvestment and revitalization. It may also be an opportunity to save and renovate structures that are important to the history of the city. The current development standards contained in the Downey municipal code were adopted in 1977. Although some sections have been amended since then, most sections are in the need of updating to reflect changes in zoning and planning trends over the past 25 years.
City of Downey Hazard Mitigation Plan 3-94
Growth over the past decade has been modest. Between 2010 and 2020, as reported by the U.S.
Census, the population of Downey grew approximately 0.9 percent, from 111,922 to 112,901 residents. The Southern California Association of Governments (SCAG) growth forecasts predict a steady increase in population through 2045. From 2020 to 2045, SCAG projects that the City’s population will grow by 5.6 percent. The projected growth largely is tied to anticipated increases in housing production, which has not been a factor for the last decade. This projected population growth and increase in homes increases the City’s exposure to earthquakes.
Climate Change: Current research does not indicate a reliable connection between climate change and earthquakes.54
FEMA NRI Expected Annual Loss Estimates
An earthquake NRI Expected Annual Loss score and rating represent a community's relative level of expected building and population loss each year due to earthquakes when compared to the rest of the United States. The Expected Annual Loss score is positively associated to a community’s risk; therefore, a higher Expected Annual Loss score results in a higher Risk Index score. The table below outlines the earthquake Expected Annual Loss for the City of Downey planning area.
Table 3.36: Earthquake Expected Annual Loss
Tracts Population
Equivalence
Building
Value
Agriculture
Value
Total Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550501 $221.9K $454.6K N/A $676.4K 89.21 Relatively High 550502 $213.1K $851.3K N/A $1.1M 93.14 Relatively High
550601 $305.6K $618.5K N/A $924.1K 91.88 Relatively High 550602 $399.7K $909.9K N/A $1.3M 94.75 Relatively High
550700 $530.6K $1.1M N/A $1.6M 96.18 Relatively High
550801 $427.1K $997.2K N/A $1.4M 95.39 Relatively High
550802 $235.9K $494.4K N/A $730.3K 89.84 Relatively High 550901 $1.1K $1.8M N/A $2.8M 98.65 Very High
550902 $393.0K $935.0K N/A $1.3M 94.85 Relatively High
551001 $336.5K $1.1M N/A $1.4M 95.27 Relatively High
551002 $267.9K $460.7K N/A $728.5K 89.82 Relatively High
54 NASA. Global Climate Change. (2019). Can Climate Affect Earthquakes, Or Are the Connections Shaky? Retrieved from https://climate.nasa.gov/news/2926/can-climate-affect-earthquakes-or-are-the-connections- shaky/
City of Downey Hazard Mitigation Plan 3-95
Tracts Population
Equivalence
Building
Value
Agriculture
Value
Total Expected
Annual Loss
Expected
Annual
Loss Score
Rating
551101 $804.4K $3.0M N/A $3.8M 99.27 Very High
551102 $1.0M $2.8M N/A $3.8M 99.28 Very High
551201 $339.9K $679.1K N/A $1.0M 92.78 Relatively High
551203 $314.2k $396.8K N/A $711.1K 89.63 Relatively High 551204 $315.4K $470.2K N/A $785.6K 90.48 Relatively High 551300 $1.3M $3.0M N/A $4.3M 99.43 Very High
551401 $247.6K $566.0K N/A $813.6K 90.77 Relatively High 551402 $335.4K $788.9K N/A $1.1M 93.58 Relatively High
551501 $423.6K $759.2K N/A $1.2M 94.02 Relatively High
551502 $305.7K $662.9K N/A $968.6K 92.30 Relatively High 551700 $323.9K $594.1K N/A $918.0K 91.83 Relatively High 551801 $510.4K $887.9K N/A $1.4M 95.27 Relatively High
551802 $389.3K $638.5K N/A $1.0M 92.84 Relatively High
553400 $210.5K $407.1K N/A $617.6K 88.46 Relatively High 980012 $277.3K $1.3M N/A $1.6M 96.08 Relatively High
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
City of Downey Hazard Mitigation Plan 3-96
3.11 Hazardous Materials Release Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.37: Hazardous Materials Release Total Risk Score Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk Score
(Probability x
Consequence)
Hazardous
Materials
Release
2 8 10 32 50 53
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.11.1 Hazardous Material Release Hazard Description
Per 49 CFR, a hazardous materials release incident can be defined as one (1) of the following:
• An unintentional release of a hazardous material or the discharge of any quantity of hazardous waste.
• A specific cargo tank with a capacity of 1,000 gallons or greater containing any hazardous materials suffers structural damage to the landing retention system or damage that requires repair to a system intended to protect the landing retention system, even if there is not a hazardous materials release.
City of Downey Hazard Mitigation Plan 3-97
• An undeclared hazardous material is discovered.
• A fire, violent rupture, explosion, or dangerous evolution of heat occurs as a direct result of battery or battery-powered device.
Hazardous material is defined by the National Fire Protection Association (NFPA) 472 (Standard for Competence of Responders to Hazardous Materials/Weapons of Mass Destruction Incidents), as a matter (solid, liquid, or gas) or energy that when released is capable of creating harm to people, the environment, and property, including weapons of mass destruction, as defined in 18 United States Code (USC), Section 2332(a), as well as any other criminal use of hazardous materials, such as illicit labs, environmental crimes, or industrial sabotage. There are several ways in which hazardous materials are categorized. The Department of Transportation (DOT) organizes substances in nine (9) categories, outlined in the table below. The NFPA categorizes hazards by the severity of the hazards in three (3) principal categories – health, flammability, and instability.55
Table 3.38: US Department of Transportation Hazard Classification System Class Substance
1 Explosives
2 Gases
3 Flammable Liquids (and combustible liquids)
4 Flammable solids, substances liable to spontaneous
combustion, substances which, on contact with water, emit flammable gases
5 Oxidizing substances and organic peroxides
6 Toxic (poisonous) substances
7 Radioactive Materials
8 Corrosive Substances
9 Miscellaneous dangerous goods/hazardous materials and articles
The U.S. Environmental Protection Agency is responsible for regulating hazardous materials, but when transported in commerce, it is regulated by DOT. EPA regulations address hazardous substances and extremely hazardous substances. EPA chooses to specifically list hazardous
55 Federal Emergency Management Agency. (2019). Hazardous Materials Incidents: Guidance for State, Local, Tribal, Territorial, and Private Sector Partners. Retrieved from https://www.fema.gov/sites/default/files/2020- 07/hazardous-materials-incidents.pdf.
City of Downey Hazard Mitigation Plan 3-98
substances and extremely hazardous substances rather than providing objective definitions.
Hazardous substances, as listed, are generally materials that, if released into the environment, tend to persist for long periods and pose long-term health hazards for living organisms. They are primarily chronic, rather than acute health hazards.56 Regulations require that spills of these materials into the environment in amounts at or above their individual reportable quantities must be reported to the EPA. Extremely hazardous substances, on the other hand, while also generally toxic materials, are acute health hazards that, when released, are immediately dangerous to the life of humans and animals as well as causing serious damage to the environment. There are currently 355 specifically listed extremely hazardous substances listed along with their individual Threshold Planning Quantities (TPQ).57 When facilities have these materials in quantities at or above the TPQ, they must submit Tier II information to appropriate state and/or local agencies to facilitate emergency planning.58
According to reports obtained through the Toxic Release Inventory (TRI) Program, there are thousands of hazardous material release events annually that contaminate air, soil, and groundwater resources. These events can potentially trigger millions of dollars in clean-up costs, human and wildlife injuries, and in some cases human deaths.
56 City of Stillwater, Oklahoma. (n.d.). Hazardous Material Hazard. Retrieved from https://storymaps.arcgis.com/stories/c413b8e41bd34a6fb82ecad4efa45b73 57 Texas Commission on Environmental Quality. (n.d.). Chemical Reporting for Tier II. Retrieved from https://www.tceq.texas.gov/permitting/tier2/hazardous-chemical-information 58 National Archives. (n.d.). Code of Federal Regulations, Part 370 – Hazardous Chemical Reporting:
Community Right-To-Know. Retrieved from https://www.ecfr.gov/current/title-40/chapter-I/subchapter-J/part-370 .
City of Downey Hazard Mitigation Plan 3-99
Figure 3.18: Map of Toxic Release Inventory 59 Facilities in the City of Downey
59 US EPA (n.d.) 2021 TRI Factsheet City of Downey, CA. Retrieved from https://enviro.epa.gov/triexplorer/tri_factsheet.factsheet?pYear=2021&pstate=CA&pcity=downey&pParent=NAT .
City of Downey Hazard Mitigation Plan 3-100
Accidents which result in chemical clouds or release of hazardous materials into public water or sewer systems may affect outlying neighborhoods or the community at large. Depending upon the scale of the release, large segments of the residential and business populations may need to be evacuated quickly for extended periods of time. Effective emergency planning with regard to hazardous materials, therefore, requires the concerted efforts of the Fire and Police Departments as well as other public safety officials and Non-Government Organizations (NGOs) such as American Red Cross. Hazardous material releases may occur from any of the following:
Table 3.39: Types of Hazardous Material Incidents
Fixed-Site
Includes all releases involving the production, manufacturing, handling, and storage of hazardous products at a facility and releases that occur at designated hazardous waste disposal sites.
Transportation
Includes releases that occur while products are in transit from one facility to another or enroute to a designated hazardous waste disposal site. Main concerns for the City include the U.S. Interstates 5, 605, and 105 highways.
Intentional Spills
and Releases
Includes all criminal acts and acts of terrorism in which a hazardous material is used to intentionally cause injuries and/or fatalities, damage the environment and/or property, or advance a political or social agenda. Further detail on acts of terrorism can be found in the Adversarial/ Human-Caused Events section of this document.
In response to concerns over the environmental and safety hazards posed by the storage and handling of toxic chemicals, Congress passed the Emergency Planning and Community Right to Know Act (EPCRA) in 1986. To reduce the likelihood of hazardous material releases, EPCRA established specific requirements on federal, state, and local governments, Indian tribes, and industry to plan for hazardous materials emergencies. EPCRA’s Community Right-to-Know provisions help increase the public's knowledge and access to information on chemicals at individual facilities, their uses, and releases into the environment. States and communities working with facilities can use the information to improve chemical safety and protect public health and the environment. Under EPCRA, hazardous materials must be reported to the EPA, even if they do not result in human exposure.
Recognizing the inherent dangers associated with the utilization of hazardous substances, the California State Legislature has enacted several laws regulating the use and transport of identified hazardous materials. In particular, Chapter 6.95 of the Health and Safety Code requires all businesses using these materials to inform local government agencies of the types and quantities of materials stored on site. This disclosure enables emergency response agencies to respond quickly and appropriately to accidents involving dangerous substances. Chapter 6.95 of the
City of Downey Hazard Mitigation Plan 3-101
California Health and Safety Code and Title 19 of the California Code of Regulations describe the requirements for chemical disclosure, business emergency plans, and community right-to-know programs. According to these State requirements, a business that uses or handles hazardous materials in amounts equal to or greater than 55 gallons, 500 pounds or 200 cubic feet at any time must prepare a business emergency plan and chemical inventory. Inventories must be updated annually, and business plans must be updated every two years. The chapter also incorporated certain requirements from Federal Superfund Amendments and Reauthorization Act (SARA) Title III for chemicals designated as acutely hazardous. These regulations also apply to industrial accidents, refinery explosions and incidences of high-volume releases.
Critical Assets (Road)
Critical assets that would be impacted by a hazmat road incident are listed in the following table and corresponding map. A ½ mile zone extending outside of the roadways is outlined alongside primary road routes (impact area). This indicates what assets/locations are potentially at risk if a hazmat incident occurs along the roadway. Critical assets include but are not limited to fire stations, government facilities, hospitals, other medical facilities, police stations, retirement homes, and schools. These and additional assets are listed in the following table.
Table 3.40: Critical Assets within Road Impact Zone
Category Facility Address Districts
Apartment Regency Terrace 11410 Dolan District 61
Apartment Park Regency 10000 Imperial Hwy District 62
Bridge San Gabriel River
bridge at Firestone
San Gabriel River
bridge at Firestone District 64
Church Calvary Chapel 12808 Woodruff Ave District 62
Church Our Lady of
Perpetual Help 10727 Downey Ave. District 63
Church Legacy Church 8348 3rd St. District 63
Church Downey First
Christian Church 10909 New St. District 63
Church First Church of Christ
Downey 8454 5th St. District 63
Church Downey Memorial
Christian church 8841 Florence Ave. District 64
Fire Station Fire Station 2 9556 Imperial Hwy District 62 Government Facility City Hall 11111 Brookshire
Ave. District 63
Hospital Kaiser Hospital /
Medical Center 9333 Imperial Hwy. District 62
City of Downey Hazard Mitigation Plan 3-102
Category Facility Address Districts
Hospital PIH Downey 11500 Brookshire
Ave. District 61
Hotel Embassy Suites 8425 Firestone Blvd. District 63
Hotel Country Inn 11111 Myrtle District 63
Library Library 11121 Brookshire
Ave. District 63
Metro Green Line
Metro Green Line at
Lakewood (Check
down tracks in both
directions)
Metro Green Line at
Lakewood (Check
down tracks in both
directions)
District 62
Other Medical Facility Downey Community
Health Center 8425 Iowa District 61
Other Medical Facility Downey Regional
Medical Center 11500 Brookshire District 62
Other Medical Facility Lakewood Park
Health
12023 Lakewood
Blvd. District 62
Other Medical Facility Sunbridge Care
Center 9300 Telegraph District 64
Overpass 105 Fwy overpass at
Lakewood
105 Fwy overpass at
Lakewood District 62
Overpass 105 Fwy overpass at
Columbia
105 Fwy overpass at
Columbia District 62
Overpass 105 Fwy overpass at
Bellflower
105 Fwy overpass at
Bellflower District 62
Overpass 105 Fwy overpass at
Dunrobin
105 Fwy overpass at
Dunrobin District 62
Overpass 105 Fwy overpass at
Woodruff
105 Fwy overpass at
Woodruff District 62
Overpass 5 Fwy overpass at
Paramount
5 Fwy overpass at
Paramount District 63
Overpass 5 Fwy overpass at
Lakewood
5 Fwy overpass at
Lakewood District 64
Overpass Pedestrian overpass
at Buhman
Pedestrian overpass
at Buhman District 64
Overpass 605 Fwy overpass at
Florence
605 Fwy overpass at
Florence District 64
Parking Garage Parking structure 8201 2nd St. District 63 Police Station Police Station 10911 Brookshire
Ave. District 63
PRIORITY 1 All American 7201 Firestone Blvd. District 63 Retirement Downey Retirement 11500 Dolan District 61
Retirement Brookshire Manor 11410 Brookshire District 62 Retirement Lakewood Manor 12045 Lakewood
Blvd. District 62
Retirement Lakewood Gardens 12055 Lakewood
Blvd. District 62
City of Downey Hazard Mitigation Plan 3-103
Category Facility Address Districts
School Williams Elementary
School 7530 Arnette District 61
School Alameda School 8613 Alameda District 62
School Sussman Middle
School 12500 Birchdale District 62
School Downey Adult School 12330 Woodruff District 62
School Carpenter
Elementary School 9439 Foster District 62
School Lewis Elementary
School
13220 Bellflower
Blvd. District 62
School Ward Elementary
School 8851 Adoree District 62
School Gallatin Elementary
School 9513 Brookshire District 63
School Unsworth Elementary
School 9001 Lindsey District 64
School East Middle School 10301 Woodruff District 64
School Downey High School 11040 Brookshire
Ave. District 64
Store Downey Landing 12020 Lakewood
Blvd. District 62
Store Home Depot 7121 Firestone Blvd. District 63
Store Stonewood Mall 251 Stonewood District 64
Theater Downey Civic
Theater 8435 Firestone Blvd. District 63
Theater Old Downey Theater
(URM) 11028 Downey Ave. District 63
Theater Kirkorian Theater 8200 3rd St. District 63
Tunnel Pedestrian tunnel at
Bangle
Pedestrian tunnel at
Bangle District 63
City of Downey Hazard Mitigation Plan 3-104
Figure 3.19: Hazmat Road Review Critical Assets
City of Downey Hazard Mitigation Plan 3-105
Critical Assets (Rail)
Critical assets that would be impacted by a hazmat rail incident are listed in the following table and corresponding map. A ½ mile area extending outside of the railways is outlined alongside primary rail routes (impact area). This indicates what assets/locations are potentially at risk if a hazmat incident occurs along the railway. Critical assets include but are not limited to fire stations, government facilities, hospitals, other medical facilities, police stations, retirement homes, and schools. These and additional assets are listed in the following table.
Table 3.41: Critical Assets Within Rail Impact Zone
Category Facility Address Districts
Apartment Regency Terrace 11410 Dolan District 61
Church Our Lady of Perpetual Help 10727 Downey Ave. District 63 Church Legacy Church 8348 3rd St. District 63
Church Downey First Christian Church 10909 New St. District 63 Church First Church of Christ Downey 8454 5th St. District 63 Church Downey Memorial Christian
church 8841 Florence Ave. District 64
Government
Facility City Hall 11111 Brookshire
Ave. District 63
Hospital PIH Downey 11500 Brookshire
Ave. District 61
Hotel Embassy Suites 8425 Firestone Blvd. District 63
Hotel Country Inn 11111 Myrtle District 63
Library Library 11121 Brookshire
Ave. District 63
Other Medical
Facility
Downey Community Health
Center 8425 Iowa District 61
Other Medical
Facility
Downey Regional Medical
Center 11500 Brookshire District 62
Other Medical
Facility Downey Care Center 13007 Paramount District 61 Overpass 605 Fwy overpass at Florence 605 Fwy overpass at Florence District 64
Parking
Garage Parking structure 8201 2nd St. District 63
Police Station Police Station 10911 Brookshire
Ave. District 63
PRIORITY 1 All American 7201 Firestone Blvd. District 63 Retirement Downey Retirement 11500 Dolan District 61
Retirement Brookshire Manor 11410 Brookshire District 62 School Warren High School 8141 DePalma District 61
City of Downey Hazard Mitigation Plan 3-106
Category Facility Address Districts
School Williams Elementary School 7530 Arnette District 61 School St Matthias High School 7851 Gardendale. District 61 School Downey High School 11040 Brookshire
Ave. District 64
Store Downey Landing 12020 Lakewood
Blvd. District 62
Store Home Depot 7121 Firestone Blvd. District 63
Store Stonewood Mall 251 Stonewood District 64
Theater Downey Civic Theater 8435 Firestone Blvd. District 63 Theater Old Downey Theater (URM) 11028 Downey Ave. District 63 Theater Kirkorian Theater 8200 3rd St. District 63
Tunnel Pedestrian tunnel at Bangle Pedestrian tunnel at Bangle District 63
City of Downey Hazard Mitigation Plan 3-107
Figure 3.20: Hazmat Rail Review Critical Assets
City of Downey Hazard Mitigation Plan 3-108
3.11.2 Hazardous Material Release Hazard History
From January 2016 until May 7, 2023, in the City of Downey, there were 19 hazardous materials incident reports filed with the U.S. Department of Transportation (DOT). Both incidents involved a forklift puncturing drum. On October 12, 2018, the clean-up cost of 40 liquid gallons of tetrachloroethylene was $3,300 while on November 8, 2018, there was not a clean-up cost, but the response to the spill of 10 gallons of UN1263 Acetone 192 was $5,500. 2012 Richmond Refinery Fire
On August 6, 2012, a piping segment at the Number 4 Crude Unit at a Chevron refinery in Richmond, California, failed, resulting in the release of hydrocarbons. The hydrocarbon vapor cloud then ignited, resulting in a large, uncontrolled fire. The fire burned for several hours before being contained later that night. The picture below illustrates the smoke plume from the fire.
Although no fatalities resulted from the fire, according to the final investigation report completed by the U. S. Chemical Safety Board (CSB), more than 15,000 residents in the vicinity of the refinery sought medical treatment for respiratory irritation. The incident inundated local emergency response agencies and interrupted local operation of the Bay Area Rapid Transit (BART). Although the 2012 Richmond Refinery Fire did not impact the City, the incident illustrated the potential major impacts to residential area that a release of this magnitude could have on the City.
2016 Maywood Fire
On June 14, 2016, a fire erupted from a plastics facility in Maywood, California in the 3700 block of Fruitland Avenue, the location of Gemini Film & Bag. The fire spread to Panda International Trading Company (PITC), a nearby metal recycling yard, which resulted in an explosion. The explosion sent smoke and fine metal particles into the air causing the evacuation of hundreds of nearby homes and businesses. The fire, fueled by magnesium from PITC, burned for more than 30 hours. In the ensuing days after the fire, firefighters washed down homes, sidewalks, and cars to remove residue from the facility which posed potential health risks to residents. The EPA tested indoor samples from 43 homes and apartments nearest the fire. Preliminary test results indicated the presence of chromium, zine, copper, and magnesium, with some metals turning up at high levels.
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3.11.3 Hazardous Material Release Hazard Probability, Frequency, and Magnitude
While the City has never experienced a large-scale release, hazardous material emergencies are possible during transportation on all routes and from the release of toxic or flammable chemicals.
Highways
Although vehicles transporting hazardous materials in commerce are subject to the strict guidelines of the Department of Transportation’s Hazardous Material Regulation (HMR), U.S.
Interstates 5, 605, and 105 remain vulnerabilities within the City’s limits due to the volume of traffic and the nature of the materials transported. According to the City’s 2011 Commodity Flow Study, a chemical release is more likely to occur on one of the freeways mentioned above rather than the City streets. In the event of a release on the freeway, the California Highway Patrol (CHP) will have ultimate responsibility with the City Fire Department providing support as necessary.
Rail
In addition, the Union Pacific railroad traverses though the southwest portions of the City.
According to the City’s 2011 Commodity Flow Study, Union Pacific transports an extensive volume of goods though the Intermodal Container Transfer Facility, which is located approximately five miles from both Port of Los Angeles and the Port of Lon Beach. In utilizing a facility so close to the City of Downey, the rail traffic that traverses the City is frequent, increasing the potential for a release within the City borders. Should a chemical spill occur while the train is in transit, there is a chance it could bisect the City and impede several access routes. Given there are two fire stations on each side of the railroad, this condition is unlikely to adversely affect proper response to a release event.
Pipelines
Numerous petroleum product producers with large storage facilities maintain hundreds of miles of pipelines throughout the county. Figures 3.21 and 3.22 illustrate the major pipelines that run through the City.
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Air
There are no airports within the City limits; however, the Los Angeles County airspace is among the busiest in the nation. Hazardous materials may be transported by air over Downey to destinations at Long Beach or Los Angeles Airports. Since air transports fly over Downey the risk of an event occurring as the result of an air accident is possible at any time.
The ongoing use, production, and transportation of hazardous materials throughout the City poses a constant and real threat to the safety of the community. An accidental release of a hazardous substance into the environment has the potential to cause localized or widespread upset.
The City of Downey maintains some direct response capability, but as stated in the City’s 2011 Commodity Flow Study, through the City’s Memorandum of Understanding the City relies on neighboring communities to provide proper hazardous material release response capability. The City of Downey can provide scene management, incident command, and evacuation support in the event of a release.
While there is currently no mechanism to assign a true probability of a fixed-site or transportation hazardous material emergency, it is important to consider a relatively high likelihood of occurrence and conduct planning and training accordingly. Additional information regarding these facilities or other hazardous materials handlers in the City can be obtained by contacting the Downey Fire Department Hazardous Materials Specialist.
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Figure 3.21: City of Downey Natural Gas Transmission Pipeline Map
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Figure 3.22: City of Downey Natural Gas Transmission/ Supply Pipeline Map
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Hazardous materials releases can often have a devastating effect on the local air and land. Although low amounts of radiation are naturally found in nature, excess amounts can be devastating to the environment. Besides human injury caused by these releases, wildlife and their habitat can often be damaged long term. Certain releases can spark fires that damage the landscape. A hazardous substance released onto the land or water can severely contaminate and impact both land and marine-based ecosystems.
Vulnerability and Impacts
A hazardous materials release can impact the life safety and health of the city by directly threatening the public within the event area. Chemicals and substances released during a hazardous materials incident can cause significant injury or death. A hazardous materials release impacts property damage and critical infrastructure of the city by either restricting access to property and infrastructure, or potentially rendering the area unusable until cleanup takes place. A hazardous materials release impacts the economy for the city by shutting down businesses in the affected areas, potentially long-term. A hazardous materials release impacts the changes in development and impact of future development for the city by forcing the cessation of current development within the affected area or causing future developments to be relocated due to contamination. A hazardous materials release impacts underserved and at-risk populations of the city by restricting public transportation routes at or nearby the affected area and causing essential services to not be as readily accessible including water and healthcare. The effects of climate change in severity of impact for a hazardous materials release for the City is increasing the likelihood of a release due to climate-driven floods, storms, and wildfires.60
60 U.S Government Accountability Office. (2022). Chemical Accident Prevention. EPA Should Ensure Regulated Facilities consider Risks from Climate Change. Retrieved from https://www.gao.gov/products/gao-22-104494
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3.12 Pandemic Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.42: Pandemic Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Pandemic 1 12 16 32 60 34
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.12.1 Pandemic Hazard Description
An outbreak of an infectious disease that spreads across a large region is commonly referred to as a pandemic. For example, a flu pandemic occurs when a new influenza virus emerges for which people have little or no immunity, and for which there is no vaccine. The disease spreads easily from person-to-person, causing serious illness, and sweeps across regions quickly.
As stated in the Los Angeles County Pandemic Influenza Plan, “compared to other natural infectious health threats, pandemic flu has great potential to cause large-scale social disruption.” Also, according to the Department of Health and Human Services, an especially
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severe influenza pandemic could lead to “high levels of illness, death, social disruption, and economic loss.” Impacts can range from the closure of schools and businesses to interruptions of basic services such as public transportation and food delivery. Additionally, a substantial percentage of the population would require some form of medical treatment.
Health care facilities may be overwhelmed, resulting in shortages of hospital staff, beds, ventilators, and other medical supplies.
In order to define and prepare for an influenza pandemic, the World Health Organization (WHO) has developed a global influenza preparedness plan, which defines the stages of a pandemic, outlines the role of WHO, and makes recommendations for national measures before and during a pandemic. The pandemic phases are detailed below:
Interpandemic period:
• Phase 1: No new influenza virus subtypes have been detected in humans. • Phase 2: No new influenza virus subtypes have been detected in humans, but an animal variant threatens human disease.
Pandemic alert period:
• Phase 3: Human infection(s) with a new subtype but no human-to-human spread. • Phase 4: Small cluster(s) with limited localized human-to-human transmission. • Phase 5: Larger cluster(s) but human-to-human spread still localized.
Pandemic period:
• Phase 6: Pandemic: increased and sustained transmission in general population.
3.12.2 Pandemic Hazard History
There have been several major pandemics that have resulted in many fatalities in the past, including COVID-19. Although the likelihood of a catastrophic outbreak has diminished in 2023, several notable events have posed serious concerns to health care professionals.
COVID-19 Pandemic
COVID-19 is a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes respiratory illness in humans and can be spread from person to person through
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respiratory droplets. These droplets are released when someone infected with the disease sneezes, coughs, or talks. Infectious droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. COVID-19 was declared a public health emergency (PHE) nationwide on January 21, 2020. The pandemic began in Wuhan, China in December 2019 and quickly spread around China and the world.
Symptoms may appear 2–14 days after exposure, or there may be no symptoms at all (asymptomatic). Symptoms vary from mild to severe and can include headache, loss of smell and taste, nasal congestion, runny nose, cough, sore throat, muscle pain, fever, fatigue, diarrhea, and breathing difficulties. Complications from more severe symptoms can lead to further life-threatening illnesses, such as pneumonia or hypoxia.
The first instance of the coronavirus outbreak began in December 2019. There are now several variants of the virus throughout the world and the state of California. The most common variant in 2022 was the Omicron variant. Other variants include Alpha, Beta, Delta, Epsilon, Gamma, Iota, and Mu.61
The World Health Organization reports that there have been 765,222,932 confirmed cases of COVID-19 (as of May 3,2023) with 6,921,614 deaths worldwide. According to the Center for Disease Control and Prevention (CDC), as of April 2023, more than 104,335 cases of COVID-19 have been reported in the United States with more than 1,129,570 deaths.62 According to the California Department of Public Health, as of May 4, 2023, there have been 11,245,575 total cases of COVID-19 statewide with 101,785 deaths. Los Angeles County has 3,516,317 COVID-19 cases with 36,003 resulting in death. According to the County of Los Angeles Department of Public Health as of April 27,2023 there have been 46,687 COVID-19 cases with 432 deaths.63
There is no current cure or specific antiviral treatment for COVID-19. However, the first vaccine for COVID-19 was released on December 21, 2020. Since then, more than 13.37 billion doses of the vaccine have been administered in more 190 countries; that’s 69.9 percent of the world population who have received at least one does of a COVID-19 vaccine.
61 Centers for Disease Control and Prevention, CDC. (2023). Retrieved from https://www.cdc.gov/coronavirus/2019-nCoV/
62 World Health Organization. (2023). WHO Coronavirus (Covid-19) Dashboard. Retrieved from https://covid19.who.int/
63 California Department of Public Health, California All. (2023). Tracking Covid-19 in California.
Retrieved from https://covid19.ca.gov/state-dashboard/
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Most COVID-19 vaccines require at least two doses (series) to reach maximum efficacy.
Multiple booster shots in addition to the dose series completion are now recommended and even required in many countries as well. During March of 2023, unvaccinated people were
2.9 percent more likely to die from COVID-19 than people who were vaccinated with at least the primary series.64
When it comes to California, as of May 2023, more than 88,791,122 vaccines have been administered with 72.8 percent of the population completing the primary series (2 doses).
On May 11, 2023, the federal COVID-19 PHE declaration ended. The declaration ending means the CDC’s ability to collect and share certain data changed. The CDC is now updating their guidance to align with data changes. At the time of the declaration, most tools; vaccines, testing, and treatment will continue to remain available. Metrics that will continue to remain include required reporting of hospital admissions for COVID-19 (until April 2024), weekly COVID-19 death reports, emergency room patient admissions with diagnosed COVID-19 will continue to be posted on a weekly basis, wastewater surveillance and genomic surveillance, and the count of COVID-19 vaccines administered will remain for jurisdictions who continue to submit data; however, the frequency will change. Some sources of how and where the above data is collected will change.65 Recent Influenza Outbreaks
Influenza (flu) season occurs annually, but the severity varies depending on which strains emerge. Health professionals were concerned in 2006 that the continued spread of a highly pathogenic avian H5N1 virus across eastern Asia and other countries represented a significant threat to human health. The H5N1 virus has raised concerns about a potential human pandemic because:
• It is especially virulent.
• It is spread by migratory birds.
• It can be transmitted from birds to mammals and in some limited circumstances to humans, and
• Like other influenza viruses, it continues to evolve.
64 Centers for Disease Control and Prevention, CDC. (2023). Retrieved from https://www.cdc.gov/coronavirus/2019-nCoV/
65 ibid
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Also notable, was the outbreak of H1N1, known as the swine flu, in 2009. Figure
3.23 illustrates how widespread the strain became in 2009.
Figure 3.23: Nations with Confirmed Cases H1N1 (August 4, 2009)
West Nile Virus
West Nile Virus (WNV) is transmitted to people, birds, and other animals by the bite of an infected mosquito. According to the California Department of Public Health, people over the age of 60 are at the greatest risk of getting sick and are more likely to develop serious symptoms of WNV. People who have received organ transplants or those with certain medical conditions such as cancer, diabetes, hypertension, or kidney disease are at greater risk of developing severe symptoms from WNV.
West Nile Virus was first found in Africa. In 1999, VWN was first detected in the eastern United States. The virus has since spread across the United States. The mosquitoes who spread WNV are found throughout the state of California. In southern states with warmer climates and mosquitoes present year-round, the risk of infection may still be present in the winter months.
The West Nile Virus is the most common and serious vector-born virus in California. There have been more than 7,000 human cases and 300 deaths reported in California since 2003.
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80% or 4 out of 5 people who contract WNV don’t show any symptoms. Up to 20% (1 in 5 people) may have mild symptoms which include a fever, headache, body aches, and a rash.
The symptoms usually develop 3-14 days after being bitten by an infected mosquito. In most cases, the symptoms of West Nile Virus last for a few days, but fatigue and weakness may linger for weeks to a few months. Less than 1% of the population (1 out of 150 people) can get severe symptoms, which include high fever, headache, neck stiffness, vision loss, numbness, confusion, weak muscles, paralysis and coma. In these severe cases, the virus has affected the brain and/or nervous system and can cause encephalitis or meningitis.
WNV can be fatal.66 The figure below shows the counties in California with active WNV cases as of May 12, 2023.
Figure 3.24: Active West Nile Virus Cases as of May 12, 2023
66 California Department of Public Health. (2023). West Nile Virus. Retrieved from https://westnile.ca.gov/
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3.12.3 Pandemic Hazard Probability, Frequency, and Magnitude It is difficult to predict the probability, location, and severity of the next biological/human disease pandemic. In contrast to many other illnesses, highly contagious diseases spread rapidly and often unexpectedly. As many diseases spread from person to person and the City is a densely populated region, the steering committee determined the entire area to be equally vulnerable to a pandemic scenario. While the City has not experienced an outbreak of pandemic proportions, the City is equipped to respond to a moderately-sized scenario.
However, in the event of a large-scale outbreak that overwhelms the City’s emergency response capacity, the City will work with the Los Angeles County Department of Health and other outside organizations to obtain the necessary resources for care.
Vulnerability and Impacts
A pandemic impacts the life safety and health of the city by potentially causing injury or death among the population. The effects of infection are highly dependent on the type of pathogen. A pandemic impacts property damage and critical infrastructure of the city by reducing staffing to critical infrastructure facilities. This in turn may lead to an increased rate of accidents due to low staffing and oversight. A pandemic impacts the economy for the city by severely disrupting services in the form of fewer consumers, mandates requiring fewer individuals within businesses, and a general slowdown due to staffing shortages. A pandemic impacts the changes in development and impact of future development for the city by slowing down or halting current or future developments due to staffing and/or materials shortages. A pandemic impact underserved and at-risk populations of the city by lessening the access to healthcare facilities. The effects of climate change in severity of impact for a pandemic for the City is to directly increase the likelihood of occurrence. As global average temperatures continue to increase, the reproduction rate, resilience, and distribution of vector-borne diseases (e.g., malaria, West Nile, Zika, Chikungunya) are likely to increase.67
67 Pan American Health Organization. (n.d.). Climate Change and Health. Retrieved from https://www.paho.org/en/topics/climate-change-and-health .
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3.13 Severe Weather/ Storm Hazard Profile
Table 3.43: Severe Weather/Storm Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk Score
(Probability x
Consequence)
Severe
Weather/Storm 2 4 15 19 38 42
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.13.1 Severe Weather/ Storm Hazard Description
For the purposes of this Plan, severe weather/storm includes those hazards that are typically produced during severe thunderstorms (i.e., lightning and hail) and heavy rainfall.
Severe Thunderstorms/Lightning
A thunderstorm is a rain shower during which you hear thunder and since thunder includes lightning, then all thunderstorms include lightning. However, a thunderstorm is classified as severe when it contains one (1) or more of the following – hail one (1) inch or greater, winds gusting in excess of 58 mph, and/or a tornado.
Included below are the hazards that comprise a severe thunderstorm – lightning and hail.
Although strong winds and tornadoes also comprise of a severe thunderstorm, the City planning team chose to individually profile those hazard profiles. Each hazard is examined independently, but it is recognized that these could occur simultaneously.
Hail
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Hail is a form of precipitation that consists of solid ice that forms inside thunderstorm updrafts.
During a thunderstorm, hail forms when raindrops are carried upward by the thunderstorm’s updrafts into extremely cold air and freeze. As the hailstones continue to be carried upward, they continue to collide with liquid water drops that freeze into the surface of the hailstone.
Once the thunderstorm’s updraft can no longer hold the weight of the hailstone, which occurs when the updraft weakens or the hailstone is too heavy, then the hail falls. When a hailstone encounters different liquid water content conditions and temperatures within the thunderstorms, it causes hailstone to have layers of clear and cloudy ice. The speed at which hail falls primarily depends on four characteristics – hail size, friction between the hailstone and surrounding air, local wind conditions (horizontal and vertical), and degree of melting of the hailstone. There is much uncertainty in the average speed hail falls; however, NOAA developed the estimates shown in the table below. 68
Table 3.44: Hail Speed Estimates
Hail Size (inches) Fall Speed (mph)
Less than 1 9 – 25
1 – 1.75 20 – 40
2 – 4 44 – 72
4 or greater Over 100
Heavy Rainfall
There is no single definition for heavy (or extreme) rainfall. However, meteorologists consider instances where the amount of precipitation (rain or snow) experienced in a location substantially exceeds normal amounts. The amount of precipitation needed to qualify as heavy rain varies with location and season. Rainfall events share characteristics such as high moisture and an atmospheric disturbance (e.g., atmospheric river) and when these conditions persist over an area the more rainfall an area will receive.69 Heavy rainfall is most frequently measured by tracking the frequency of events, analyzing the mean return period, and measuring the amount of precipitation in a certain period (most typically inches of rain within
68 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Hail Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/hail/ .
69 National Oceanic and Atmospheric Administration. (2018). Ask the Scientist: Extreme Rainfall, Why it Happens and How We Predict It. Retrieved from https://www.noaa.gov/stories/ask-scientist-extreme-rainfall- why-it-happens-and-how-we-predict-it.
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a 24-hour period)70. An atmospheric river is a relatively common weather pattern that brings heavy rainfall and mountain snow to California and is often referred to as an atmospheric river.
About 30% to 50% of the annual precipitation in the west coast states occurs during a few atmospheric river events and approximately 80% of the levee breaches in the California’s Central Valley are associated with atmospheric rivers.71 Atmospheric rivers are long, concentrated regions in the atmosphere that transport moist air from the tropics to higher latitudes. The combination of moist air and high wind speeds produce heavy precipitation upon landfall, especially over mountainous terrain. As atmospheric rivers move over land, conditions can be similar to a tropical cyclone leading to flash flooding, mudslides, cyclone force winds, increased wave heights, and catastrophic damage to life and property.72
3.13.2 Severe Weather/ Storm Hazard History
To indicate the potential for a severe weather event, Table 3.45 lists severe weather events from the National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Environmental Information (NCEI). The table includes lightning, hail, and heavy rainfall with some of these storm event types resulting in extensive regional damage. This list is not comprehensive since severe weather is an annual event regularly causing minor damage and economic disruption (e.g., closed roads, fallen power lines, etc.).
Table 3.45: Historical Severe Weather Damage in Los Angeles County Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
E Central Sj
Valley
(Zone)
E Central Sj
Valley (Zone) 2/1/2000 0:01 Heavy
Rain 0 0 0.00k 0.00k
E Central Sj
Valley
(Zone)
E Central Sj
Valley (Zone) 2/13/2000 0:00 Heavy
Rain 0 0 0.00k 0.00k
Downey Los Angeles
Co. 4/18/2000 3:40 Hail 0 0 0.00k 0.00k
70 United States Environmental Protection Agency. (2023). Climate Change Indicators: Heavy Precipitation.
Retrieved from https://www.epa.gov/climate-indicators/climate-change-indicators-heavy-precipitation . 71 Monroe, R. (2019). New Scale To Characterize Strength And Impacts Of Atmospheric River Storms.
Retrieved from https://scripps.ucsd.edu/news/new-scale-characterize-strength-and-impacts-atmospheric- river-storms.
72 National Oceanic and Atmospheric Administration. (2023). Atmospheric Rivers: What are They and How Does NOAA Study Them? Retrieved from https://research.noaa.gov/2023/01/11/atmospheric-rivers-what- are-they-and-how-does-noaa-study-them/.
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Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
E Central Sj
Valley
(Zone)
E Central Sj
Valley (Zone) 9/1/2000 3:40 Heavy
Rain 0 0 0.00k 250.00k
Countywide Los Angeles
Co. 1/10/2001 11:00 Heavy
Rain 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 2/11/2001 6:00 Heavy
Rain 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 2/24/2001 10:00 Heavy
Rain 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 3/4/2001 14:00 Heavy
Rain 0 0 0.00k 0.00k
Mono (Zone) Mono (Zone) 7/2/2001 19:30 Heavy
Rain 0 0 0.00k 0.00k
Mono (Zone) Mono (Zone) 7/5/2001 14:30 Heavy
Rain 0 0 0.00k 0.00k
Sw Sj Valley
(Zone)
Sw Sj Valley
(Zone) 9/3/2001 7:42 Heavy
Rain 0 0 0.00k 0.00k
E Central Sj
Valley
(Zone)
E Central Sj
Valley (Zone) 9/3/2001 7:42 Heavy
Rain 0 0 0.00k 0.00k
Kern Cty
Mtns (Zone)
Kern Cty Mtns
(Zone) 9/3/2001 12:35 Heavy
Rain 0 0 0.00k 0.00k
Se Kern Cty
Desert
(Zone)
Se Kern Cty
Desert (Zone) 9/3/2001 12:35 Heavy
Rain 0 0 0.00k 0.00k
Indian Wells
Vly (Zone)
Indian Wells Vly
(Zone) 9/3/2001 12:35 Heavy
Rain 0 0 0.00k 0.00k
Duarte Los Angeles
Co. 7/28/2003 21:45 Lightning 0 1 0.00k 0.00k
Lancaster Los Angeles
Co. 7/29/2003 16:05 Hail 0 0 0.00k 0.00k
Compton Los Angeles
Co. 11/12/2003 17:00 Hail 0 0 3.500m 0.00k
South
Pasadena
Los Angeles
Co. 2/20/2004 13:15 Lightning 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 12/27/2004 17:00 Heavy
Rain 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 12/31/2004 7:30 Heavy
Rain 0 0 0.00k 0.00k
Countywide Los Angeles
Co. 1/7/2005 2:00 Heavy
Rain 0 0 5.000m 0.00k
Van Nuys Los Angeles
Co. 2/25/2005 14:35 Hail 0 0 0.00k 0.00k
Newhall Los Angeles
Co. 2/25/2005 14:55 Hail 0 0 0.00k 0.00k
La
Crescenta
Los Angeles
Co. 8/15/2005 1:40 Hail 0 0 0.00k 0.00k
Pasadena Los Angeles
Co. 10/17/2005 12:45 Hail 0 0 0.00k 0.00k
El Monte Los Angeles
Co. 10/17/2005 13:11 Hail 0 0 0.00k 0.00k
Sherman
Oaks
Los Angeles
Co. 12/27/2006 2:43 Hail 0 0 0.00k 0.00k
Duarte Los Angeles
Co. 5/22/2008 13:30 Hail 0 0 0.00k 0.00k
Fairmont Los Angeles
Co. 7/4/2011 15:15 Hail 0 0 0.00k 0.00k
Desert View
Highland
Los Angeles
Co. 9/10/2011 15:30 Hail 0 0 0.00k 0.00k
Walnut Los Angeles
Co. 3/1/2014 3:20 Hail 0 0 0.00k 0.00k
(Sxc)Santa
Catalina
Los Angeles
Co. 7/27/2014 11:30 Lightning 0 1 0.00k 0.00k
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Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
Marina Del
Ray
Los Angeles
Co. 7/27/2014 13:20 Lightning 1 8 0.00k 0.00k
Leona Vly Los Angeles
Co. 10/15/2015 14:35 Hail 0 0 0.00k 0.00k
Palmdale Los Angeles
Co. 10/15/2015 15:45 Hail 0 0 0.00k 0.00k
Desert View
Highland
Los Angeles
Co. 10/15/2015 15:52 Hail 0 0 0.00k 0.00k
Acton Los Angeles
Co. 8/3/2017 15:45 Hail 0 0 0.00k 0.00k
South
Whittier
Los Angeles
Co. 6/22/2022 7:45 Lightning 1 0 0.00k 0.00k
Total 2 10 8.500M 250.00K
In another example reported by NOAA, on January 31, 2016, a weather spotter in Monterey Park, about 9 miles north of the City, reported severe thunderstorms reaching approximately 60 MPH. Rainfall totals that day ranged from .5 to 1.5 inches in the area. Local damage reports included some roof damage and a knocked down power pole.
3.13.3 Severe Weather/ Storm Hazard Probability, Frequency, and Magnitude
Severe weather (i.e., severe thunderstorms, lightning, and hail) and heavy rainfall can occur anywhere in the City of Downey.
Severe weather can be life threatening and can cause substantial damage to infrastructure and property. The extent of damage caused by severe weather depends on the type of severe weather, strength, and location.
The figure below illustrates the severe thunderstorm outlook categories used by the NWS Storm Prediction Center (SPC) when issuing Severe Thunderstorm Outlooks.
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Figure 3.25: SPC Severe Thunderstorm Outlook Categories
The NWS SPC is responsible for issuing severe thunderstorms and tornado advisories, as conditions warrant. The table below outlines the severe thunderstorm 73 Refer to the Tornado section of this Plan for more advisory information during tornado activity.
Table 3.46: NWS Severe Weather Advisories
Type Description
Severe Thunderstorm
Watch
Issued by the NOAA SPC when conditions are favorable for the development of severe thunderstorms in and close to the watch area. The size of the watch can vary depending on the weather situation. Severe thunderstorm watches are usually issued for a duration of four (4) to eight (8) hours. They are normally issued well in advance of the actual occurrence of severe weather.
Severe Thunderstorm
Warning
Issued by the local NWS Forecast Office when either a severe thunderstorm is indicated by radar, or a spotter reports a thunderstorm producing hail one (1) inch or larger in diameter and/or winds equal or exceed 58 mph. Severe thunderstorm warnings are usually issued for a duration of one (1) hour. They can be issued without a Severe Thunderstorm Watch being already in effect. Severe thunderstorms can produce tornadoes with little or no advance warning.
73 National Weather Service. (n.d.). National Weather Service Glossary. Retrieved from https://w1.weather.gov/glossary/ .
City of Downey Hazard Mitigation Plan 3-127
Hail can vary in shape and size, and only the exceptionally large hailstones pose a serious risk to life safety. NWS reports hail size by comparing the hailstone with traditional object to size conversion for assessment and translation of severe hail reports. The table below lists the traditional conversion of hail size descriptions.74 Table 3.47: Converting Traditional Hail Size Descriptions Hail Size (inches) Object Analog Reported
0.25 Pea
0.50 Mothball
0.75 Penny
0.88 Nickel
1.00 Quarter
1.50 Walnut, ping pong
1.75 Golf ball
2.50 Tennis ball
2.75 Baseball
3.00 Teacup
Heavy rainfall can lead to flooding which can be unexpected and leave a small window of time for evacuation, if it is required. The NWS Los Angeles/Oxnard Forecast Office is responsible for issuing flood advisories and Flash Flood Warnings Impact-Based Warnings for events that occur within approximately six (6) hours of heavy rainfall in the City. Refer to the Urban Flood section of this Plan for more information during a heavy rainfall event that leads to flooding.
The Atmospheric River Scale was developed in collaboration with the Center for Western Water and Weather Extremes at Scripps Institution of Oceanography at University of California San Diego and National Weather Service. The scale uses the amount of water vapor within the atmospheric river as its basis and a period of 24 to 48 hours as its standard measurement of duration. For example, if an atmospheric river remains over an area for over 48 hours the category is increased one and if it is less than 24 hours it is decreased by a category. The Atmospheric River Scale has five (5) categories outlined below.75
74 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Hail Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/hail/ .
75 Monroe, R. (2019). New Scale To Characterize Strength And Impacts Of Atmospheric River Storms.
Retrieved from https://scripps.ucsd.edu/news/new-scale-characterize-strength-and-impacts-atmospheric- river-storms.
City of Downey Hazard Mitigation Plan 3-128
Table 3.48: Atmospheric River Scale
Category Description
1 Weak Primarily beneficial.
2 Moderate Mostly beneficial, but also hazardous.
3 Strong Balance of beneficial and hazardous.
4 Extreme Mostly hazardous, but also beneficial.
5 Exceptional Primarily hazardous.
Upcoming tables on the following pages provide information and trends for the aforementioned hazards, including average climate information for the City.
Figure 3.26: City of Downey Average Monthly Temperature 76
76 ibid
City of Downey Hazard Mitigation Plan 3-129
Figure 3.27: City of Downey Average Monthly Precipitation with Daily Maximum 77
The hail annualized frequency value represents the average number of recorded hail hazard occurrences, in event days, per year over the period of record (34 years). The table below outlines the annualized frequency for hail, based on FEMA NRI data, for the City.
Table 3.49: Hail Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(1986 – 2021) 34 years Annualized Frequency
550501 3 0.1 events per year
550502 3 0.1 events per year
550601 3 0.1 events per year
550602 3 0.1 events per year
550700 3 0.1 events per year
550801 3 0.1 events per year
550802 3 0.1 events per year
550901 3 0.1 events per year
550902 3 0.1 events per year
551001 3 0.1 events per year
551002 3 0.1 events per year
551101 3 0.1 events per year
551102 3 0.1 events per year
551201 3 0.1 events per year
551203 3 0.1 events per year
551204 3 0.1 events per year
77 ibid
City of Downey Hazard Mitigation Plan 3-130
City of Downey
Census Tracts Events on Record
(1986 – 2021) 34 years Annualized Frequency
551300 3 0.1 events per year
551401 3 0.1 events per year
551402 3 0.1 events per year
551501 3 0.1 events per year
551502 3 0.1 events per year
551700 3 0.1 events per year
551801 3 0.1 events per year
551802 3 0.1 events per year
553400 3 0.1 events per year
980012 3 0.1 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
The lightning annualized frequency value represents the average number of recorded strike occurrences, in event days, per year over the period of record (22 years). The table below outlines the annualized frequency for lightning, based on FEMA NRI data, for the City.
Table 3. 50: Lightning Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(1991-2012) 22 years Annualized Frequency
550501 22 1 event per year
550502 22 1 event per year
550601 22 1 event per year
550602 22 1 event per year
550700 24 1.1 events per year
550801 25 1.1 events per year
550802 31 1.4 events per year
550901 22 1 event per year
550902 22 1 event per year
551001 21 1 event per year
551002 21 1 event per year
551101 21 0.9 events per year
551102 21 0.9 events per year
551201 21 1 event per year
551203 21 1 event per year
551204 21 1 event per year
551300 22 1 event per year
551401 21 1 event per year
551402 21 1 event per year
City of Downey Hazard Mitigation Plan 3-131
City of Downey
Census Tracts Events on Record
(1991-2012) 22 years Annualized Frequency
551501 21 1 event per year
551502 21 1 event per year
551700 20 0.9 events per year
551801 14 0.6 events per year
551802 11 0.5 events per year
553400 14 0.6 events per year
980012 21 1 event per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
A heavy rainfall NRI annualized frequency is not available as FEMA does not include this hazard as one of the eighteen natural hazards in the National Risk Index.
Vulnerability and Impacts
Population: Severe weather impacts the life safety and health of the city by potentially causing injury or death to the public in extreme cases. Exposure is the greatest danger to people from thunderstorms. People can be hit by lightning, pelted by hail, and caught in rising waters. However, serious injury and loss of human life is rarely associated with hailstorms.
While national data shows that lightning causes more injuries and deaths than any other natural hazard except extreme heat, there does not seem to be any trend in the data to indicate that one segment of the population is at a disproportionately high risk of being directly affected. Anyone who is outside during a thunderstorm is at risk of being struck by lightning.
Aspects of the population who rely on constant, uninterrupted electrical supplies may have a greater, indirect vulnerability to lightning. As a group, the elderly or disabled, especially those with home health care services rely heavily on an uninterrupted source of electricity. Resident populations in nursing homes, residential facilities, or other special needs housing may also be vulnerable if electrical outages are prolonged. Thunderstorms have the potential energy and strong winds to topple dead trees and injure people. As a result, power outages that occur from severe weather can be life threatening and these populations could face more exposure and could experience greater secondary effects of the hazard.
In Downey, 12,419 residents (11.3 percent) are living with a disability. As age increases, so does the percentage of each age group that has disability; for residents who are 75 years and over, more than half have a disability. The 65 to 74 years age group constitutes the second- highest number of disabilities.
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Along with an aging population, Downey is becoming more diverse racially and ethnically.
Hispanic residents make up most of the City’s population. Over 60% of residents speak a language other than English in the home, with 55.4% of residents speaking Spanish. 20.6% of residents speak English less than very well. Although the city has made efforts to ensure emergency warnings and notifications are conducted to reach all population groups, generally this segment of the population may be more vulnerable during a severe weather event.
Table 3.51: Vulnerability and At-Risk Populations: Severe Weather/Storm Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
Language other than English 70,341 64% of residents
Spanish Spoken at Home 60,889 55.4% of residents
Speak English less than very well 22,641 20.6% of residents Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services Property: While the primary effects may not result in significant injury or property damage, all property is vulnerable during severe weather events. Mobile homes and properties in poor condition or closer to overhead power lines and large trees may be more vulnerable to damage. Due to the unpredictability of thunderstorm strength and path, most critical infrastructure that is above ground is equally exposed to the storm’s impacts. According to historical data, the city has experienced power outages in the past due to severe storms, but due to the random nature of these hazards, a more specific risk assessment was not conducted for this plan. Heavy rain and thunderstorms, particularly those that result in hail, could significantly impact motorists travelling along major roadways. Depending on the severity of the storm, these events could slow traffic, reduce visibility, and increase the likelihood of vehicle accidents, which may result in greater traffic delays.
City of Downey Hazard Mitigation Plan 3-133
Table 3.52: Property Vulnerability: Severe Weather/Storm Vulnerable Category Count Percent
Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
Source: US Census Bureau 2022 ACS
Table 3.53: Assets/Structures Vulnerability and Impact Summary: Severe Weather/Storm
Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Hospitals 3 100%
Reliance on electrical
grid and sustained
power.
Parks 11
100% Open areas
vulnerable to damage
and exposure of
residents
Wells 20
100% Reliance on electrical
grid and sustained
power.
Lift Stations 2
100% Reliance on electrical
grid and sustained
power.
Trees 15,600
100% Vulnerable to damage
and cause cascading
damages to property,
utilities, and roads
Streetlights 5,200 100% Vulnerable to damage
Source: Los Angeles County Assessors, National Bridge Inventory, City of Downey
Table 3.54: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates:
Severe Weather/Storm
Category/Type Number of
Structures
Tot a l Potential
Loss and
Replacement
Va lue *
Adjusted Potential Loss and
Replacement Value*
Due to the low extent of severe
weather/storms in the City of Downey,
this calculation estimates that 1% of
assets c ould be impacted during a
significant event .
Residential, Single
Residential, Multi-
Unit Residential
Structures
22,291 $4,815,267,965.00 $48,152,679.65
City of Downey Hazard Mitigation Plan 3-134
Commercial, Office
Buildings, Stores,
Service Stations
885 $847,087,183.00 $8,470,871.83
Industrial,
Manufacturing,
Warehouses
291 $175,933,384.00 $1,759,333.84
Recreational,
Cultural, Community
Centers, Athletic
Fields/Facilities
21 $58,482,613.00 $584,826.13
Institutional, Schools,
Hospitals/Healthcare,
Churches
107 $720,531,246.00 $7,205,312.46
Source: Los Angeles County Assessor
*Property Loss and Replacement Value does not include land valuations Economic: The economic impacts of storms are typically short term. Lightning can cause power outages and fires. Hail can destroy exposed property; an example is car lots, where entire inventories can be damaged. Generally, long-term economic impacts center around hazards that cascade from a thunderstorm, including flooding due to heavy rain.
Thunderstorms can have devastating effects on transportation corridors in the city.
Thunderstorms may increase the potential for transportation accidents along major roadways which could in turn cause longer traffic delays and timely movement of goods and services.
Other disruptions from thunderstorms include delayed emergency response vehicles and school closures.
Changes in Development and Future Development: Recent development has been constructed based on the latest building code and construction standards and is less likely to be severely impacted by severe weather and storms. However, based upon observations and experiences of the Code Enforcement Division, the city estimates that in 2020, fewer than 25 housing units were in severe need of replacement or substantial rehabilitation due to housing conditions. These units, for example, may be suffering from neglect and these buildings may be structurally unsound and more vulnerable to severe weather and storms.
Future development projects should consider severe weather hazards at the planning, engineering and architectural design stage with the goal of reducing vulnerability. Stormwater master planning and site plan review should account for building to withstand severe weather events and be considered for all new development. Future development in the city is not expected to be vulnerable to the hazard, but all development will be affected by severe weather and storm events.
City of Downey Hazard Mitigation Plan 3-135
Climate Change: The effects of climate change in severity of impact for severe weather for the city is fairly well connected. As the climate warms, it is anticipated for severe weather events to increase in both severity and frequency.78 It is anticipated that the atmospheric rivers that deliver storms to Southern California may intensify because of climate change. While the average number of storms in Southern California will remain the same, storms are expected to increase in intensity by 10 to 20 percent. This increase in storm intensity may also bring more intense winds.79 Climate change is expected to alter rainfall patterns in Southern California. As the climate warms, rain events are predicted to become more intense. Downey will likely experience more rain inundation events that lead to localized flooding.
FEMA NRI Expected Annual Loss Estimates
A hail NRI Expected Annual Loss (EAL) score and rating represent a community's relative level of expected building, population, and agriculture loss each year due to hail when compared to the rest of the United States. The EAL score is positively associated with a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. The table below outlines the hail EAL for the City of Downey planning area.
Table 3.55: Hail Expected Annual Loss
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550501 $15 $4 $0 $18 3.30 Very Low
550502 $17 $8 $0 $25 5.47 Very Low
550601 $23 $6 $0 $29 6.62 Very Low
550602 $18 $7 $0 $25 5.36 Very Low
550700 $29 $9 $0 $38 8.88 Very Low
550801 $19 $7 $0 $26 5.81 Very Low
550802 $11 $3 $0 $14 2.19 Very Low
550901 $18 $10 $0 $28 6.23 Very Low
550902 $23 $7 $0 $30 6.89 Very Low
551001 $16 $7 $0 $23 4.74 Very Low
551002 $15 $5 $0 $20 3.82 Very Low
78 NASA. Global Climate Change. (n.d.). Extreme Weather and Climate Change. Retrieved from https://climate.nasa.gov/extreme-weather/
79 Atmospheric Rivers' to Soak California as Climate Warms. Retrieved from https://www.livescience.com/49225- atmospheric-rivers-double-climate-change.html
City of Downey Hazard Mitigation Plan 3-136
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
551101 $16 $13 $0 $29 6.55 Very Low
551102 $22 $14 $0 $36 8.34 Very Low
551201 $15 $5 $0 $20 3.74 Very Low
551203 $15 $4 $0 $19 3.40 Very Low
551204 $17 $4 $0 $20 3.98 Very Low
551300 $22 $14 $0 $36 8.31 Very Low
551401 $18 $4 $0 $22 4.58 Very Low
551402 $19 $6 $0 $24 5.16 Very Low
551501 $20 $6 $0 $26 5.67 Very Low
551502 $17 $5 $0 $22 4.54 Very Low
551700 $26 $5 $0 $31 7.02 Very Low
551801 $13 $6 $0 $19 3.54 Very Low
551802 $18 $5 $0 $23 4.75 Very Low
553400 $16 $3 $0 $19 3.56 Very Low
980012 $0 $5 $0 $6 1.14 Very Low
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
A lightning NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to lightning when compared to the rest of the United States. The table below outlines the lightning EAL for the City of Downey planning area.
Table 3.56: Lightning Expected Annual Loss
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual Loss
Score
Rating
550501 $256 $3 N/A $259 6.57 Very
Low
550502 $299 $6 N/A $305 7.59 Very
Low
550601 $431 $4 N/A $435 10.03 Very
Low
550602 $322 $5 N/A $327 8.10 Very
Low
550700 $577 $8 N/A $584 12.19 Very
Low
550801 $383 $7 N/A $390 9.29 Very
Low
City of Downey Hazard Mitigation Plan 3-137
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual Loss
Score
Rating
550802 $264 $3 N/A $267 6.77 Very
Low
550901 $316 $7 N/A $323 8.01 Very
Low
550902 $398 $6 N/A $404 9.54 Very
Low
551001 $275 $5 N/A $281 7.08 Very
Low
551002 $264 $3 N/A $268 6.79 Very
Low
551101 $265 $10 N/A $274 6.95 Very
Low
551102 $375 $10 N/A $386 9.21 Very
Low
551201 $258 $4 N/A $261 6.63 Very
Low
551203 $262 $3 N/A $265 6.73 Very
Low
551204 $286 $3 N/A $289 7.27 Very
Low
551300 $382 $10 N/A $393 9.33 Very
Low
551401 $311 $3 N/A $314 7.79 Very
Low
551402 $321 $4 N/A $325 8.04 Very
Low
551501 $346 $5 N/A $350 8.54 Very
Low
551502 $298 $4 N/A $301 7.53 Very
Low
551700 $428 $4 N/A $432 9.98 Very
Low
551801 $150 $3 N/A $153 3.73 Very
Low
551802 $146 $2 N/A $148 3.62 Very
Low
553400 $171 $1 N/A $172 4.23 Very
Low
980012 $0 $4 N/A $4 0.22 Very
Low
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
A heavy rainfall NRI Expected Annual Loss calculation is not available as FEMA does not include this hazard as one of the eighteen natural hazards in the National Risk Index.
City of Downey Hazard Mitigation Plan 3-138
3.14 Tornado Hazard Profile
Table 3.57: Tornado Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Tornado 1 8 7 23 38 23
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.14.1 Tornado Hazard Description
A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground. A tornado is hard to see unless it forms a condensation funnel made up of water droplets, dust, and debris. Tornadoes are among the most violent phenomena of all atmospheric storms and atmospheric scientists continue to conduct research to better understand how tornadoes form. Tornadoes come from mainly two (2) types of thunderstorms – supercell and non-supercell. 80 The table below outlines the types of tornadoes.
80 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Tornado Basics. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/tornadoes/ .
City of Downey Hazard Mitigation Plan 3-139
Table 3.58: Types of Tornadoes 81
Type Description
Supercell
The most common and destructive tornadoes occur from supercells.
A supercell is a rotating thunderstorm with a well-defined radar circulation called a mesocyclone. Supercells can also produce damaging hail, severe non-tornadic winds, frequent lightning, and flash floods. The rotating updraft from a supercell is the key development for a tornado. One way a column of air can begin to rotate is from wind shear when winds at two (2) different levels above the ground blow at different speeds or in different directions. Once the updraft is rotating and fed with warm moist air flowing in the ground level, a tornado can form.
Non-Supercell
Nearly 20% of all tornadoes are associated with lines of strong thunderstorms called quasi-linear convective systems (QLCS). QLCS tornadoes frequently occur during the late night and early morning hours. These tornadoes, however, tend to be weaker and shorter- lived on average than those associated with supercell thunderstorms.
NOAA’s National Severe Storms Laboratory (NSSL) researchers are looking for ways to detect QLCS tornadoes more effectively.
Another type of non-supercell tornado is a landspout. A landspout is a tornado with a narrow, rope-like condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft - the spinning motion originates near the ground.
Tornadoes can be life threatening and can cause substantial damage to infrastructure and property. The extent of damage caused by a tornado depends on the type of severe weather, strength, and location. The table below outlines the tornado advisories issued by the NWS and the Storm Prediction Center (SPC) as conditions warrant.
Table 3.59: National Weather Service Tornado Advisories 82 Type Description
Tornado Watch
Issued by the SPC when conditions are favorable for the development of tornadoes in and close to the watch area. The size of the watch can vary depending on the weather situation. Tornado watches are usually issued for a duration of four (4) to eight (8) hours. They are normally issued well in advance of the actual occurrence of tornadoes.
Tornado Warning
Issued by the local NWS Forecast Office when either a tornado is indicated by radar or sighted by spotters. Tornado warnings are usually issued for a duration of around 30 minutes. They can be issued without a Tornado Watch being already in effect
81 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Types of Tornadoes. Retrieved from https://www.nssl.noaa.gov/education/svrwx101/tornadoes/types/ . 82 National Weather Service. (n.d.). National Weather Service Glossary. Retrieved from https://w1.weather.gov/glossary/ .
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3.14.2 Tornado Hazard History
Tornadoes are rare in California, with less than 10 per year occurring in the state each year. Most of those tornadoes are small and short lived. • An EF0 tornado developed near the community of Lake Los Angeles in September of 2021. No damage was reported.
• On March 22, 2023, the strongest tornado to hit Los Angeles County in 40 years hit Montebello. The EF-1 rated tornado had winds which peaked at 110 mph. At least seventeen buildings were damaged, with eleven of those being deemed unsafe by the fire department. Damage included caved in roofs, snapped power poles.83 Figure 3.28: EF1 Tornado rips off Roof of a building in Montebello, March 22, 2023
• In early June 2023, a pair of tornadoes touched down, lasting only minutes. Both were EF0’s with minimal damage.
83 CNN. (2023). Los Angeles Area Hit by Rare Tornado – The Strongest One to Hit the County Since 1983.
Retrieved from https://www.cnn.com/2023/03/22/weather/california-montebello-possible-tornado/index.html .
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NCEI Tornado Events
NCEI has reported five Tornado events from 2018 to 2023 in Los Angeles County. Most notably on March 22, 2023, in East Los Angeles County, an EF1 Tornado spawned off a strong winter storm which had recorded gusts in excess of 80 MPH. One-person sustained injuries, but no deaths were recorded. Additionally, an industrial warehouse and commercial business district was substantially damaged.84
Table 3.60: NCEI Tornado Events in Los Angeles County (2018 - 2023)85 Location County/ Zone Date Time Death Injury
Property
Damage
Crop
Damage
LLANO LOS ANGELES
CO. 09/09/2021 15:58 0 0 0.00K 0.00K
CERRITOS LOS ANGELES
CO. 02/23/2023 11:30 0 0 0.00K 0.00K
EAST LOS
ANGELES
LOS ANGELES
CO. 03/22/2023 10:14 0 1 0.00K 0.00K
COMPTON
MUNI ARPT
LOS ANGELES
CO. 05/04/2023 07:45 0 0 0.00K 0.00K
COMPTON LOS ANGELES
CO. 05/04/2023 07:56 0 0 0.00K 0.00K
Totals 0 1 0.00K 0.00K
3.14.3 Tornado Hazard Probability, Frequency and Magnitude The probability of tornados in the City planning area is low. However, the entire city of the City of Downey is at risk of a tornado if the right weather conditions are present.
Climate change impacts on tornadoes in the State of California requires further analysis. Future updates to this plan will consider new research on this topic.
Tornado “rating”, based on the Enhance Fujita Scale (EF Scale), is assigned after tornado- related damage is surveyed. The EF Scale is based on the estimated wind speeds and related
84 National Oceanic and Atmospheric Administration, National Centers for Environmental Information. (n.d.).
Storm Events Database. Retrieved from https://www.ncdc.noaa.gov/stormevents/ . 85 National Oceanic and Atmospheric Administration, National Centers for Environmental Information. (n.d.).
Storm Events Database. Retrieved from https://www.ncdc.noaa.gov/stormevents/ .
City of Downey Hazard Mitigation Plan 3-142
damage. The table below outlines the EF Scale. When tornado damages are surveyed, they are compared to a list of Damage Indicators and Degrees of Damage which help to better estimate the range of wind speeds the tornado likely produced. The EF Scale was revised from the original Fujita Scale and became operational in February 2007. 86 Table 3.61: Enhance Fujita Scale
EF Rating Class Wind Speed (mph) Wind Speed (km/h) Description F0 Weak 65-85 105-137 Gale
F1 Weak 86-110 138-177 Weak
F2 Strong 111-135 178-217 Strong
F3 Strong 136-165 218-266 Severe
F4 Violent 166-200 267-322 Devastating
F5 Violent >200 >322 Incredible
The NWS SPC is responsible for issuing severe thunderstorms and tornado advisories, as conditions warrant. The table below outlines the tornado advisories.87 Refer to the Severe Weather/Storm section of this Plan for more advisory information during severe thunderstorms.
Table 3.62:NWS Severe Weather Advisories
Type Description
Tornado
Watch
Issued by the SPC when conditions are favorable for the development of tornadoes in and close to the watch area. The size of the watch can vary depending on the weather situation. Tornado watches are usually issued for a duration of four (4) to eight (8) hours. They are normally issued well in advance of the actual occurrence of tornadoes.
Tornado
Warning
Issued by the local NWS Forecast Office when either a tornado is indicated by radar or sighted by spotters. Tornado warnings are usually issued for a duration of around 30 minutes. They can be issued without a Tornado Watch being already in effect
86 National Weather Service. (n.d.). The Enhance Fujita Scale (EF Scale). Retrieved from https://www.weather.gov/oun/efscale .
87 National Weather Service. (n.d.). National Weather Service Glossary. Retrieved from https://w1.weather.gov/glossary/ .
City of Downey Hazard Mitigation Plan 3-143
The tornado annualized frequency value represents the average number of recorded tornado hazard occurrences, in event days, per year over the period of record (72 years). Upon review, no data is available for the annualized frequency for tornadoes, based on FEMA NRI data, for the City, consisting of twenty-six census tracts.
Vulnerability and Impacts
Population:
Tornadoes can cause injuries and fatalities due to flying debris, collapsing buildings, and the sheer force of the winds. These injuries and casualties can occur to people caught in the tornado's path or those in poorly constructed or unprotected buildings. Tornadoes can disrupt power lines and electrical infrastructure, causing widespread power outages. This can impact medical facilities, emergency services, and the ability to communicate during and after the tornado. Tornadoes can block roads with debris, making it challenging for emergency responders to reach affected areas quickly. Tornadoes can render homes uninhabitable, leading to the displacement of residents. Finding temporary shelter for those affected becomes a critical concern for local authorities. Disadvantaged residents may have substandard housing or lack access to safe and sturdy buildings. This can lead to a higher risk of injury or death during tornadoes, as inadequate shelter may not provide adequate protection from the storm's path. Some residents may have limited mobility due to disabilities, lack of transportation, or other factors. This can make it more challenging for them to seek shelter or evacuate quickly when tornado warnings are issued. Individuals with pre-existing health conditions or those who rely on medical equipment that requires electricity may face greater risks during tornadoes, especially if power outages occur. Non-English-speaking population or cultural differences may face challenges in receiving and understanding emergency alerts and instructions, which can hinder their ability to respond effectively.
In Downey, 12,419 residents (11.3 percent) are living with a disability. Among the disability types tallied (a resident can have more than one disability type) the most prevalent were ambulatory (serious difficulty walking or climbing stairs) and independent living difficulties (difficulty doing errands alone such as visiting a doctor’s office or shopping). One quarter of residents with a disability indicated an ambulatory difficulty and 21 percent indicated an independent living difficulty. The remaining disabilities tallied include cognitive difficulties (18
City of Downey Hazard Mitigation Plan 3-144
percent), self-care difficulties (14 percent), hearing difficulties (12 percent), and vision difficulties (11 percent).
As age increases, so does the percentage of each age group that has disability; for residents who are 75 years and over, more than half have a disability. The 65 to 74 years age group constitutes the second-highest number of disabilities. Disability and poverty are closely tied due to employment limitations. For residents with disabilities, more than 13 percent live in poverty.
Many senior-headed households have special needs due to their relatively low incomes, disabilities or limitations, and dependency needs. Specifically, many people aged 65 years and older live alone. In Downey, 12,552 residents are 65 years and older, representing 11.4 percent of the population. For residents 65 years and older, 9.5 percent live in poverty.
Along with an aging population, Downey is becoming more diverse racially and ethnically.
Hispanic residents make up most of the City’s population. Over 60% of residents speak a language other than English in the home, with 55.4% of residents speaking Spanish. 20.6% of residents speak English less than very well.
Extremely low-income (ELI) is defined as households with income less than 30 percent of area median income (AMI). 13.8 percent of the City's total households (4,525 households) are classified as extremely low income.
Table 3.63: Vulnerability and At-Risk Populations: Tornado Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
Language other than English 70,341 64% of residents
Spanish Spoken at Home 60,889 55.4% of residents
Speak English less than very well 22,641 20.6% of residents Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services
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Property:
There are 23,194 buildings within the census tracts that define the planning area. Most of these buildings are residential. All of these buildings are considered to be exposed to the adverse impacts of a tornado. The frequency and degree of damage will depend on specific locations and the path of the tornado. Mobile homes, older buildings, and structures in poor condition are more prone to damages. The city estimates that in 2020, fewer than 25 housing units were in severe need of replacement or substantial rehabilitation due to housing conditions. These units, for example, may be suffering from neglect and these buildings may be structurally unsound.
Table 3.64: Property Vulnerability: Tornado
Vulnerable Category Count Percent
Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
Structures Built before 1960 17,847 More than 50% of
occupied housing units
Source: US Census Bureau 2022 ACS
Table 3.65: Assets/Structures Vulnerability and Impact Summary: Tornado Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Government
(City Hall and Public Works) 2 100% -
Columbia Memorial Space
Center 1 100% -
Hospitals 3 100% -
Major Shopping Centers 5 100% -
National Register of Historic
Places 2 100% -
Library 1 100% -
Parks 11 100% -
Schools 28 100% -
Fire Stations 4 100% -
Police Stations 1 100% -
Trees 15,600 100% -
Source: Los Angeles County Assessors, National Bridge Inventory, City of Downey
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Table 3.66: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates:
Tornado
Category/Type Number of
Structures
Total Potential
Loss and
Replacement
Value*
Adjusted Potential Loss and
Replacement Value*
Due to the low probability and low
geographic footprint of tornadoes in the
City of Downey, this calculation
estimates that 0.5% of assets could be
impacted.
Residential, Single
Residential, Multi-
Unit Residential
Structures
22,291 $4,815,267,965.00 $24,076,339.83
Commercial, Office
Buildings, Stores,
Service Stations
885 $847,087,183.00 $4,235,435.92
Industrial,
Manufacturing,
Warehouses
291 $175,933,384.00 $879,666.92
Recreational,
Cultural, Community
Centers, Athletic
Fields/Facilities
21 $58,482,613.00 $292,413.07
Institutional, Schools,
Hospitals/Healthcare,
Churches
107 $720,531,246.00 $3,602,656.23
Source: Los Angeles County Assessor
*Property Loss and Replacement Value does not include land valuations Economic: The economic impacts of a tornado are typically geographically isolated and short term. Impacted property may be damaged and affected businesses may be closed due to needed repairs. Tornadoes can devastate local economies, and disadvantaged individuals may have fewer resources to recover and rebuild. This can result in prolonged hardships and displacement for residents.
Changes in Development and Future Development: Due to the low probability and intensity of tornadoes, recent development that has been constructed based on the latest building code and construction standards should be more resilient to this hazard. Future development projects should consider tornadoes and severe weather hazards at the planning, engineering and architectural design stage with the goal of reducing vulnerability.
Growth over the past decade has been modest. Between 2010 and 2020, as reported by the U.S. Census, the population of Downey grew approximately 0.9 percent, from 111,922 to 112,901 residents. The Southern California Association of Governments (SCAG) growth
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forecasts predict a steady increase in population through 2045. From 2020 to 2045, SCAG projects that the City’s population will grow by 5.6 percent. This projected population growth and increase in homes increases the City’s exposure to tornadoes. New residents may also be less informed about this hazard.
Climate Change: To date, there is not enough evidence to show a direct correlation between tornadoes and climate change. Changes in smaller-scale, short-lived severe weather such as tornadoes and thunderstorms are more difficult to assess, and direct observations of those events and the conditions associated with them are incomplete. While the average annual number of tornadoes appears to have remained relatively constant, there is evidence nationally that tornado outbreaks have become more frequent, that tornado power has increased, that tornado activity is increasing in the fall. According to the 2023 Fifth National Climate Assessment, tornadoes are exhibiting changes that may be related to climate change, but scientific understanding is not confident enough to project the likelihood of future conditions.88 FEMA NRI Expected Annual Loss Estimates
A tornado NRI Expected Annual Loss score and rating represent a community's relative level of expected building and population loss each year due to tornadoes when compared to the rest of the United States The table below outlines the tornado EAL for the City of Downey planning area.
Table 3.67: Tornado Expected Annual Loss for the City of Downey Planning Area Tracts Population
Equivalence
Building
Value
Agriculture
Value
Total Expected
Annual Loss
Expected
Annual Loss
Score
Rating
550501 $1688 $2509 $0 $4197 12.50 Very Low
550502 $1989 $5597 $0 $7587 21.85 Very Low
550601 $2745 $3840 $0 $6585 19.65 Very Low
550602 $2081 $4783 $0 $6864 20.32 Very Low
550700 $3369 $6351 $0 $9720 25.42 Very Low
550801 $2194 $5121 $0 $7314 21.28 Very Low
550802 $1233 $2195 $0 $3427 9.97 Very Low
550901 $2106 $6618 $0 $8724 23.94 Very Low
550902 $2653 $5024 $0 $7677 22.02 Very Low
88 Fifth National Climate Assessment (2023). Climate Trends. Retrieved from https://nca2023.globalchange.gov/chapter/2/
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Tracts Population
Equivalence
Building
Value
Agriculture
Value
Total Expected
Annual Loss
Expected
Annual Loss
Score
Rating
551001 $1836 $4764 $0 $6600 19.69 Very Low
551002 $1763 $3151 $0 $4914 14.85 Very Low
551101 $1857 $8929 $0 $10.7K 26.80 Very Low
551102 $2548 $9572 $0 $12.1K 28.07 Very Low
551201 $1720 $3202 $0 $4923 14.88 Very Low
551203 $1750 $2349 $0 $4100 12.17 Very Low
551204 $1905 $2641 $0 $4546 13.60 Very Low
551300 $2549 $9521 $0 $12.1K 28.03 Very Low
551401 $2072 $2974 $0 $5046 15.28 Very Low
551402 $2139 $3919 $0 $6057 18.29 Very Low
551501 $2304 $4134 $0 $6438 19.28 Very Low
551502 $1986 $3398 $0 $5384 16.34 Very Low
551700 $2960 $3538 $0 $6498 19.42 Very Low
551801 $1510 $4030 $0 $5541 16.82 Very Low
551802 $2048 $3517 $0 $5565 16.89 Very Low
553400 $1839 $2141 $0 $3979 11.79 Very Low
980012 $0 $3779 $0 $3779 11.14 Very Low
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
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3.15 Mass Transportation Accident/ Incident Hazard
Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.68: Mass Transportation Accident/Incident Total Risk Score Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Mass
Transportation
Accident/Incident
1 12 16 32 60 34
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.15.1 Mass Transportation Accident/ Incident Hazard Description Roadway Incident
Freeway accidents occur very frequently in the Los Angeles County region. In recent years, California has averaged about 3,000 freeway accident-related deaths annually, according to the California Highway Patrol. The major local transportation routes that traverse the City include Interstates 5, and 605, and 105, creating local traffic congestion and increasing the potential for transportation accidents in the City.
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Railway Incident
Freight trains travel near the northeast border of the City hauling various types of hazardous materials. A major train derailment that occurs in a heavily populated industrial area could result in significant damage and potential loss of life. Both freeway and rail accidents can be a further hazard if the impacted vehicles are transporting hazardous materials. As noted in the hazardous material release hazard profile, accidents in these cases can result in hazardous materials releases.
Airborne Incident
Daily air traffic creates the potential for hazard events to occur in the skies over the City. The City is located on the flight path to the Los Angeles International Airport (LAX), the second busiest airport in the United States. With a high volume of flights over the City, there is the potential for airborne accidents.
3.15.2 Transportation Accident/ Incident Hazard History In August 1986, the City of Cerritos, less than 10 miles away from Downey, experienced a deadly plane crash where more than eighty people were killed when Aeromexico DC-9 Flight 498 collided with a single-engine Piper Archer 6,500 feet above a residential area. The pilot and two passengers aboard the Piper were killed while the sixty-four people aboard the DC-9 flight were killed. The Piper crashed onto the playground of Cerritos Elementary School. The pilots of the DC-9 had no way to control their plane and it crashed into a neighborhood. Fifteen people on the ground were killed and eight were left injured. Five homes were destroyed and another seven were damaged.89
September of 2008 marked the deadliest train accident in California history when a Metrolink train collided head-on with a Union Pacific freight train. The passenger train’s locomotive and lead passenger car derailed while the two locomotives and ten cars of the freight train derailed.
There were twenty-five fatalities, including the engineer of the passenger train. More than one
89 This Day in Aviation. (2018). Aeromexico Flight 498. Retrieved from https://www.thisdayinaviation.com/tag/aeromexico-flight-498/
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hundred people were injured. Physical damage was more than $12 million. The Chatsworth accident was just forty-five miles from the City of Downey.90 In February of 2015, there was a deadly accident with dozens of injuries when a Metrolink train hit a produce truck left on the tracks by the driver in Oxnard, seventy-five miles from the City of Downey. More than two dozen passengers were injured, and the train’s engineer later died.91
In the past five years, there have been 764 airborne incidents in the state of California. Of those, 167 have resulted in fatalities. The table below details the twenty-nine fatal National Transportation Safety Board (NTSB) investigations within 50 miles of the City of Downey.
Table 3.69: Fatal Airborne Incidents within 50 Miles of the City of Downey (2017-2023) Date City Distance from Downey # of Fatalities # of Injuries 1/4/17 San Pedro 22 2 0
1/17/17 Corona 39 1 1
7/14/17 El Monte 16 1 0
1/30/18 Newport Beach 35 3 1
8/5/18 Santa Ana 23 5 0
8/12/18 Sylmar 36 1 0
9/3/18 Pacoima 35 1 1
9/29/18 La Verne 29 1 1
10/1/18 La Verne 29 1 0
2/3/19 Yorba Linda 26 5 2
3/13/19 Compton 8 1 1
4/22/19 Norco 44 1 0
6/15/19 Porter Ranch 40 1 0
6/17/19 Two Harbors 40 1 0
9/19/19 Torrance 17 1 1
11/7/19 Upland 36 1 0
1/4/20 Santa Clarita 45 1 0
1/22/20 Corona 39 4 0
1/26/20 Calabasas 44 9 0
3/13/20 Sylmar 36 2 0
90 U.S. Department of Transportation, Federal Railroad Administration. (2019). Metrolink 111 Collision with UP. Chatsworth. Sept 2008. Retrieved from https://railroads.dot.gov/human-factors/elearning- attention/metrolink-111-collision-chatsworth-sept-2008
91 ABC News. (2015). Metrolink Crash: Truck Driver Arrested on Felony Hit and Run Charge. Retrieved from https://abcnews.go.com/US/metrolink-crash-truck-driver-arrested-felony-hit-run/story?id=29183024
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Date City Distance from Downey # of Fatalities # of Injuries 9/11/20 Van Nuys 32 2 0
10/4/20- Hawthorne 15 1 0
11/12/20 Los Angeles 13 1 0
2/19/20 Los Angeles 13 1 0
2/19/22 Newport Beach 32 1 0
4/20/22 Sylmar 36 1 0
8/20/22 Pacific Ocean 22 1 0
9/8/22 Santa Monica 27 2 0
11/30/22 Torrance 17 2 0
12/22/22 Santa Monica 27 1 0
4/29/23 Los Angeles 13 1 0
The most severe airborne incident within the last five years occurred in January of 2020 in Calabasas, forty-four miles from Downey. A well-known basketball player, his daughter, and others were all killed when the Sikorsky S-76B helicopter they were flying in crashed into the hillside. National Transportation Safety Board (NTSB) findings show that the pilot made a series of poor decisions causing him to fly blindly into the clouds, causing him to become disoriented to the point where he thought he was climbing into the clouds when he instead plunged into the Southern California hillside. The NTSB said the pilot ignored his training, violated flight rules by flying into conditions where he could not see, and failed to take alternative measures like slowing down, landing, or switching to auto-pilot. This came on a day when all LAPD helicopters were grounded because of the weather conditions.92
3.15.3 Transportation Accident/ Incident Hazard Probability, Frequency, and Magnitude
While the City has never experienced a large-scale transportation incident, due to the high volume of commuter traffic traveling through the streets, freight transportation on the railways, and air traffic in the skies above the City, there is a high potential for a transportation accident. In the event of a major incident, roadways could be populated by vehicles carrying hazardous chemicals and flammable materials, which could create the potential for fire,
92Associated Press. (2021). US Officials: Pilot error caused Kobe Bryant chopper crash. Retrieved from https://apnews.com/article/kobe-bryant-helicopter-crash-cause-2c87b04d28961fd277927eea8e8e5564
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hazardous material releases, and other harmful events. In 2011, the Downey Fire Department conducted a Hazardous Materials Commodity Flow Study which analyzed the flow of hazardous materials throughout the City. The study produced valuable information for emergency response planning.
Vulnerability and Impacts
A transportation accident impacts the life safety and health of the City by potentially causing injury or death to those involved in the accident or who are nearby. A transportation accident impacts property damage and critical infrastructure of the City by potentially damaging or destroying buildings or infrastructure at the accident site. A transportation accident impacts the economy for the City by hindering ongoing traffic flow, thereby reducing income in relation to public transportation and cargo. A transportation accident impacts the changes in development and impact of future development for the City by potentially slowing down current developments and causing existing developments to be relocated. A transportation accident impacts underserved and at-risk populations of the City by impacting essential services such as mass transportation. The effects of climate change in severity of impact for a transportation accident for the City is the overall increase in lethal car wrecks due to hotter weather.93 Figure 3.29 below depicts the transportation routes for the City and the potential areas for freeway-related accidents while Figure 3.30 depicts the truck routes throughout the City.
93 Syris Valentine. Scientific American. (2023). Hotter Days Are Increasing Car Crashes and Fatalities.
Retrieved from https://www.scientificamerican.com/article/hotter-days-are-increasing-car-crashes-and- fatalities/
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Figure 3.29: City of Downey Transportation Routes Map
City of Downey Hazard Mitigation Plan 3-155
Figure 3.30: City of Downey Truck Routes Map
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3.16 Urban Fires Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.70: Urban Fires Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Urban Fires 1 5 10 23 38 23
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.16.1 Urban Fires Hazard Description
The uncontrolled combustion or burning of an item, structure, or landscape is a fire. Fires constitute a much larger problem than is generally known. Deaths and injuries from all natural disasters combined—floods, hurricanes, tornados, earthquakes, etc.—are just a fraction of the annual casualties from fire. Deaths from natural disasters average just under 200 per year, versus approximately 4,000 deaths from fires. This section will describe the following fire categories: tire/scrap fires, structural fires, and arson. Wildfire Smoke / Air Quality will be covered in a separate section.
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Tire Fires
California is faced with the significant challenge of diverting or safely managing more than 51 million 94 reusable and waste tires generated each year. Many of those scrap tires end up in approved storage sites that are carefully regulated and controlled by the California Department of Resources Recycling and Recovery (CalRecycle). The Legislature recognized the need for waste tire management and passed the California Tire Recycling Act in 1989. To further strengthen waste tire management, the Legislature passed Senate Bill (SB) 876 in 2000 to augment the California Tire Recycling Act. However, some scrap tires are dumped intentionally in unapproved locations throughout the state.
Tire disposal sites can be fire hazards, in large part, because of the enormous number of scrap tires typically present at one site. This large amount of fuel renders standard firefighting practices nearly useless. Flowing and burning oil released by the scrap tires can spread the fire to adjacent areas. Tire fires differ from conventional fires in the following ways:
• Relatively small tire fires can require significant fire resources to control and extinguish.
• Those resources often cost much more than standard fire responses. • There may be significant environmental consequences of a major tire fire. Extreme heat can convert a standard vehicle tire into approximately 2 gallons of oily residue that may leak into the soil or migrate to streams and waterways.
Urban Fires
Lightning strikes, poor building construction, and building condition are the main causes for most urban fires in California. The City of Downey has structural fires each year citywide.
According to the National Fire Protection Association (NFPA), a fire occurs in a structure at the rate of one every 65 seconds, and a home fire occurs every 93 seconds. In 2021, the United States had 486,500 structural fires which resulted in, 3,010 civilian fatalities, 12,600 civilian injuries, and $12.8 in property damage. 95
Arson
94 CalRecycle (n.d.). Tire Management. Retrieved from https://calrecycle.ca.gov/Tires/ . 95 National Fire Protection Association. (2022). Fire Loss in the United States: Trend Tables. Retrieved from: Fire Loss in the United States: Trend Tables (nfpa.org).
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It is important to note that arson is a contributing factor to fire-related incidents within the City. According to the NFPA, between 2014 and 2018 an estimated average of 52 fires, 260 intentional fires are reported to fire departments in the United States each year, causing no civilian deaths, 950 injuries, and $815 million in direct property damage.96 Figure 3.31: Fire Deaths per Million Population, US vs. California
3.16.2 Urban Fires Hazard History
Urban fires create a devastating loss to property and even human life. Table 3.71 details the urban fires in the City of Downey for CY 2018-2023. City of Downey Fire Department officials say these are rough estimates, based off investigation narrative, narrative of event, and/or local knowledge of the building or incident. More detailed information does not appear to be immediately available. The below table and figures do not include structures considered vacant. Officials say if these figures were included, a significantly higher number
96 National Fire Protection Association. (2022). Fire death rates by State. Retrieved from https://www.nfpa.org/News-and-Research/Data-research-and-tools/US-Fire-Problem/Fire-deaths-by- state.
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would be obtained. This is due to the considerable number of fires on the Rancho Los Amigos grounds where multiple total loss fires occurred.
Table 3.71: Urban Fires Losses and Financial Damages
Date Cost Date Cost
1/8/2018 $90,000 3/15/2021 $900,000
2/14/2018 $65,000 4/1/2021 $60,000
5/29/2018 $125,000 6/21/2021 $75,000
6/17/2018 $50,000 6/25/2021 $60,000
8/19/2018 $2,000 6/27/2021 $15,000
9/25/2018 $2,100 6/30/2021 $25,000
12/28/2018 $25,000 9/15/2021 $50,000
2/11/2019 $75,000 10/16/2021 $75,000
3/25/2019 $10,000 11/9/2021 $250,000
5/8/2019 $20,000 11/15/2021 $75,000
6/13/2019 $20,000 12/13/2021 $20,000
8/11/2019 $15,000 1/14/2022 $25,000
10/13/2019 $37,500 2/25/2022 $150,000
10/21/2019 $25,000 3/14/2022 $50,000
10/25/2019 $120,000 3/17/2022 $125,000
10/25/2019 $20,000 4/6/2022 $80,000
11/23/2019 $25,000 4/27/2022 $7,500
12/1/2019 $20,000 5/16/2022 $30,000
12/14/2019 $5,000 6/3/2022 $150,000
12/16/2019 $30,000 6/15/2022 $10,000
12/24/2019 $20,000 6/29/2022 $40,000
2/8/2020 $100,000 7/22/2022 $25,000
4/16/2020 $50,000 7/24/2022 $85,000
4/18/2020 $75,000 8/15/2022 $60,000
4/26/2020 $7,500 10/7/2022 $75,000
5/31/2020 $10,500 10/12/2022 $80,000
6/12/2020 $1,250 10/17/2022 $125,000
7/4/2020 $1,500 10/27/2022 $30,000
7/10/2020 $60,000 11/1/2022 $7,500
10/21/2020 $75,000 12/1/2022 $10,000
12/10/2020 $655,000 12/19/2022 $50,000
12/25/2020 $75,000 12/20/2022 $175,000
12/28/2020 $50,000
1/7/2021 $15,000
2/5/2021 $75,000
2/20/2021 $10,000
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3.16.3 Urban Fires Hazard Probability, Frequency and Magnitude This hazard is considered to have a low risk because infrequent occurrences of this hazard have seldom occurred in the City but can likely occur in the future. Isolated incidents causing minimal impact may, of course, occur on a more frequent basis.
Urban Fire hazards occur citywide in the built environment. Communities with older wooden structures or structures near one another are more vulnerable to structural fires.
Fire-hazard events may occur anywhere within the county; because of this, future development will be impacted.
No significant or notable developmental (construction, climate variability, population changes, and other conditions) changes have occurred that would change the vulnerability of the City to this hazard. While new housing developments have been built since the last iteration of the plan, the trends have not been unique or reflective of an increased vulnerability to this hazard.
This hazard impacts the entire City equally; therefore, the entire population and all buildings within the City are vulnerable to fires and can expect the same impacts within the affected area. Because of the difficulty predicting which communities are at risk, the entire population and all buildings have been identified as risk facilities. All facilities are vulnerable to fire hazards. An essential or critical facility will encounter many of the same impacts as any other building within the City. These impacts include structural damage from fire and water damage from efforts extinguishing fire. A structural fire has the potential to cause enormous property damage and threaten the lives of City residents. Direct burns and smoke inhalation can both seriously injure residents and their pets, not to mention the significant financial loss that would likely accompany any such event.
Burning of certain property or urban structures has the potential to release hazardous fumes and smoke into the air, potentially threatening the health of the community and of the environment nearby. It is also possible for fires to spread amongst nearby trees and vegetation, potentially causing a great deal of damage to the surrounding flora and fauna.
City of Downey Hazard Mitigation Plan 3-161
Vulnerability and Impacts
Urban fire impacts the life safety and health of the City by posing a direct threat to the Public through smoke inhalation, and burns. Urban fire impacts property damage and critical infrastructure of the City by threatening existing structures beyond the initial point of ignition.
Urban fire impacts the economy for the City by damaging or destroying buildings such as businesses. Urban fire impacts the changes in development and impact of future development for the City by potentially halting current development due to damage or causing future development to account for high-risk fire zones. Urban fire impacts underserved and at-risk populations of the City by causing increased financial strain due to healthcare costs and property damage. The effects of climate change in severity of impact for urban fire for the City is an increased risk. Wildfires are burning more often, hotter, and are larger due to increasing temperatures. This increases the risk of an urban fire where the wildland-urban fire interface is more extensive.97
97 U.S Fire Administration. (n.d.). Wildland Urban Interface. Retrieved from https://www.usfa.fema.gov/stories/wildland-urban-interface/
City of Downey Hazard Mitigation Plan 3-162
3.17 Urban Flood Hazard Profile
Table 3.72: Urban Flood Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Urban Flood 1 8 12 22 42 25
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.17.1 Urban Flood Hazard Description
According to the National Flood Insurance Program (NFIP), flood is the most common type of disaster including both man-made and naturally occurring incidents in the U.S. Areas along rivers, streams, lakeshores, and coastlines are particularly susceptible to flooding.
The primary responsibility of the local governments during widespread flooding is to protect public safety. The second responsibility is protection of the environment followed by property including highways, streets, bridges, and other structures.
The types and causes of flooding that can occur within the City are the result of:
• Heavy rains,
• Dam release, (described in Section 3.5)
• Flood control channel overflow,
• Wastewater flooding within residences as a result of lift station failures, • Coastal, tropical, and/or hurricane storms, and
City of Downey Hazard Mitigation Plan 3-163
• Accidents such as reservoir leaks and water main breaks.
Due to light annual rain fall and the City’s location on the flood plain protecting it from channel overflow, dam release is the most probable cause of flooding with the City.
A flood occurs any time a body of water rises to cover what is usually dry land. Floods have many causes, including heavy rains, spring snowmelt, coastal storms, and dam or levee release. When flooding occurs, affected areas may sustain damage to structures and personal property, as well as severe damage to the environment in the form of soil erosion, deforestation and damage to utilities and transportation systems.
Floods can take several hours to days to develop. The following flood characterization designates the amount of time for response.
• Flood Watch – Issued when forecasters have between 50% and 80% confidence that a particular forecast point on a river will rise above flood stage. Flood Watches will typically be issued 6 to 48 hours before a river is forecast to rise above flood stage.
• Flood Warning – Flooding is expected to occur more than 6 hours after the causative event. Issued when flooding is imminent or occurring. • Flash Flood Watch – Issued when conditions are favorable for flash flooding. It does not mean that flash flooding will occur, but it is possible. • Flash Flood Warning – Issued when a flash flood is imminent or occurring. People in flood prone areas should move to high ground immediately. A flash flood is a sudden violent flood that can take from minutes to hours to develop. It is possible to experience a flash flood in areas not immediately receiving rain.
Alluvial Fan Flooding
Alluvial fan flooding occurs in the steep arid or semiarid mountains found throughout California. Alluvial fans are fan-shaped deposits of eroded rock and soil carried out of mountains and into valley floors by landslides, mudslides, mudflows, and surface runoff. At the beginning of the valley, alluvial fans are steep and narrow with boulders and other course material. The deposited material becomes increasingly fine as the gradient decreases and the material, mainly gravel, sand and mud, spreads.
City of Downey Hazard Mitigation Plan 3-164
When rain falls, runoff from the canyon walls flows as a high-velocity sheet that channels into rivulets, and then to natural drainage courses. The rapidly moving water often carries large boulders and other material from the watershed depositing them into runoff channels, blocking the flow of water. Floodwater then spills out onto the fan, with each event finding a new channel that soon fills up with deposits and overflows. Flooding in alluvial fans often can cause greater damage than clear-water flooding.
Flash Flooding
A flash flood is a rapid flooding of low-lying areas, rivers and streams that is caused by the intense rainfall associated with a thunderstorm or multiple thunderstorms. Flash floods also occur when a man-made structure, such as a dam, collapses. Flash flooding occurs when the ground under a storm becomes saturated with water so quickly that it cannot be absorbed. The runoff collects in low-lying areas and flows rapidly downhill. As a result, anything in its path is suddenly in rising water. Typically, flash floods begin with a slow- moving thunderstorm. A slow-moving thunderstorm usually takes longer to move out of the affected areas and causes the area to endure a greater amount of rainfall for a longer period of time. In addition, a thunderstorm may pass over an affected area repeatedly, dumping even more rainfall.
The heavy rainfall associated with these storm systems contributes to urban flooding in a number of ways. Primarily, heavy rainfall will often overwhelm the capacity of the conventional drainage system made up of storm drains, catch basins, sewers, and additional natural mechanisms for storm-water management. These systems typically cannot handle more than one or two inches of rainfall per hour before they begin to back up and overflow. This amount is further diminished if the storm drains, and other components of the storm-water management system, have not been adequately maintained, are clogged with debris such as trash or natural waste, or are old and in a state of disrepair. Heavy rainfall, combined with storm-water runoff, can cause local waterways to rise and overflow their banks.
City of Downey Hazard Mitigation Plan 3-165
3.17.2 Urban Flood Hazard History
A flood event in Los Angeles County can range from a few isolated areas where a number of streets are flooded preventing temporary access to homes and businesses, to numerous homes inundated with several feet of water causing millions of dollars of damage. Floods in the City area can cause extensive damage to residential and business properties, parks and recreational facilities, road and highway infrastructure, and critical utility facilities.
The City is adjacent to two major rivers: the San Gabriel River to the east and the Rio Hondo River to the west. These rivers both serve as flood control channels in times of heavy rains.
Specific low-lying regions of the City are more susceptible to urban flooding including Rancho Los Amigos Hospital Grounds, Firestone and Lakewood Boulevard, Firestone Boulevard and between Paramount Boulevard and Brookshire Avenue, areas south of Telegraph Road and north of the Santa Ana Freeway.
The National Center of Environmental Information (NCEI) has reported 24 flash flood events between 2017 until May 2023 in Los Angeles County. None of those incidents have resulted in loss of life or financial damages.58F 98 Between 2019 and February 2024, four emergencies and disasters have been declared for flooding (EM-3591, EM-3592, DR-4434, DR-4431). The table below lists the flood events that have occurred in Los Angeles County between 2017 and 2023 according to the NCEI.
Table 3.73: Flood Events in Los Angeles County (2017 - 2023) Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
LAS
LOMAS
LOS
ANGELES
CO.
01/12/2017 14:41 Flash
Flood 0 0 0.00K 0.00K
LANG
LOS
ANGELES
CO.
01/20/2017 12:59 Flash
Flood 0 0 0.00K 0.00K
98 National Centers for Environmental Information NCEI. (2023). Storm Events Database – Los Angeles County Flood & Flash Flood. Retrieved from
https://www.ncdc.noaa.gov/stormevents/listevents.jsp?eventType=%28C%29+Flash+Flood&eventType= %28Z%29+Flood&beginDate_mm=01&beginDate_dd=01&beginDate_yyyy=2017&endDate_mm=05&end Date_dd=26&endDate_yyyy=2023&county=LOS%2BANGELES%3A37&hailfilter=0.00&tornfilter=0&windf ilter=000&sort=DT&submitbutton=Search&statefips=6%2CCALIFORNIA
City of Downey Hazard Mitigation Plan 3-166
Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
LAS
LOMAS
LOS
ANGELES
CO.
01/20/2017 13:15 Flash
Flood 0 0 0.00K 0.00K
CARSON
LOS
ANGELES
CO.
01/22/2017 14:39 Flash
Flood 0 0 0.00K 0.00K
HUMPHR
EYS
LOS
ANGELES
CO.
02/11/2017 15:04 Flash
Flood 0 0 0.00K 0.00K
HUMPHR
EYS
LOS
ANGELES
CO.
02/17/2017 17:00 Flash
Flood 0 0 0.00K 0.00K
ACTON
LOS
ANGELES
CO.
08/03/2017 15:47 Flash
Flood 0 0 0.00K 0.00K
LLANO
CRYSTAL
ARPT
LOS
ANGELES
CO.
08/15/2020 14:50 Flash
Flood 0 0 0.00K 0.00K
GORMAN
LOS
ANGELES
CO.
08/18/2020 17:15 Flash
Flood 0 0 0.00K 0.00K
LAKE
HUGHES
LOS
ANGELES
CO.
09/11/2022 13:43 Flash
Flood 0 0 0.00K 0.00K
CLAREM
ONT
LOS
ANGELES
CO.
09/11/2022 18:20 Flash
Flood 0 0 0.00K 0.00K
DESERT
VIEW
HIGHLAN
D
LOS
ANGELES
CO.
09/11/2022 18:20 Flash
Flood 0 0 0.00K 0.00K
LAKE
HUGHES
LOS
ANGELES
CO.
09/11/2022 18:39 Flash
Flood 0 0 0.00K 0.00K
THREE
PT
LOS
ANGELES
CO.
09/11/2022 19:38 Flash
Flood 0 0 0.00K 0.00K
(SDB)SA
NDBERG
LOS
ANGELES
CO.
09/11/2022 20:01 Flash
Flood 0 0 0.00K 0.00K
ELIZABET
H LAKE
LOS
ANGELES
CO.
01/09/2023 15:49 Flash
Flood 0 0 0.00K 0.00K
SANTA
SUSANA
LOS
ANGELES
CO.
01/09/2023 19:17 Flash
Flood 0 0 0.00K 0.00K
VAL
VERDE
PARK
LOS
ANGELES
CO.
01/09/2023 19:56 Flash
Flood 0 0 0.00K 0.00K
City of Downey Hazard Mitigation Plan 3-167
Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
HEWITT
LOS
ANGELES
CO.
02/24/2023 14:44 Flash
Flood 0 0 0.00K 0.00K
HONBY
LOS
ANGELES
CO.
02/24/2023 22:39 Flash
Flood 0 0 0.00K 0.00K
NORTH
HOLLYW
OOD
LOS
ANGELES
CO.
02/25/2023 00:23 Flash
Flood 0 0 0.00K 0.00K
UNIVERS
AL CITY
LOS
ANGELES
CO.
02/25/2023 01:22 Flash
Flood 0 0 0.00K 0.00K
SAN
FERNAN
DO
LOS
ANGELES
CO.
02/25/2023 04:03 Flash
Flood 0 0 0.00K 0.00K
WAVE
LOS
ANGELES
CO.
02/25/2023 05:21 Flash
Flood 0 0 0.00K 0.00K
Total 0 0 0.00K 0.00K
The City has experienced large flooding events in the past. For example, in the winter of 1952 when Firestone Blvd. was overwhelmed with rainwater. On a smaller scale, the City has experienced local flooding which has inhibited traffic flow and resulted in minor property damage.
Repetitive Loss Properties
FEMA defines a repetitive loss structure as an NFIP-insured structure that has had at least two paid flood losses of more than $1,000 each in any 10-year period since 1978.
Severe Repetitive Loss Building
Defined by FEMA as any building that: (1) Is covered under a Standard Flood Insurance Policy made available under this title. (2) Has incurred flood damage for which: (a) Four or more separate claim payments have been made under a Standard Flood Insurance Policy issued pursuant to this title, with the amount of each such claim exceeding $5,000 and with the cumulative amount of such claims payments exceeding $20,000; or (b) At least two separate claims payments have been made under a Standard Flood Insurance Policy, with the cumulative amount of such claim payments exceeding the fair market value of the insured building on the day before each loss.
City of Downey Hazard Mitigation Plan 3-168
Severe Repetitive Loss Property
Either a severe repetitive loss building or the contents within a severe repetitive loss building, or both. The figure below summarizes FEMA repetitive loss and severe repetitive loss properties in the City.
Figure 3.32: Repetitive loss & Severe Repetitive loss Summary 99
The figure below summarizes the number of policies enforced and the total monetary amount of closed paid losses.
Figure 3.33: Insurance Occupancy 100
99 California Department of Water Resources (2023). Data provided by Division of Regional Assistance- Southern Region Office.
100 Ibid.
City of Downey Hazard Mitigation Plan 3-169
3.17.3 Urban Flood Hazard Probability, Frequency, and
Magnitude
Figures 3.34, 3.35, and 3.36 on the following pages provide FEMA Flood Insurance Rate Maps (FIRM) for the City, as well as Southern California. According to the maps, the City is in 500-year flood plains. The 500-year recurrence intervals indicate a 0.002 annual probability of a flooding event. Although unlikely, flooding remains a possibility due to the potential for release of nearby Prado Dam. Refer to section 3.8 for additional information on dam failure.
As of September 2022, more than 89,500 single-family homes had flood insurance policies.
There are only 40 policies in place in in the City of Downey.101
101 FEMA (2022). FEMA Risk Rating, Flood Insurance Policies. Retrieved from https://www.insurancejournal.com/app/uploads/2023/05/fema_risk-rating-2.0_exhibits-2-3-4.xlsx
City of Downey Hazard Mitigation Plan 3-170
Figure 3.34: City of Downey FEMA Insurance Rate Map (FIRM)
City of Downey Hazard Mitigation Plan 3-171
Figure 3.35: City of Downey 100-year Flood Study
City of Downey Hazard Mitigation Plan 3-172
Figure 3.36: City of Downey 500-year Flood Study
City of Downey Hazard Mitigation Plan 3-173
Due to Climate Change, more frequent and intense rains are leading to more severe flooding.
Heavy rain can trigger flash flooding and make rivers overflow. Saturated soil also creates ideal conditions for landslides and mudslides.
HAZUS
A HAZUS analysis was conducted for a 100-year and 500-year flood to examine the exposure and damages of buildings to flooding.
100-Year Flood Analysis
The total economic loss estimated for the flood is 1,209.09 Million, which represents 10.19 percent of total replacement value of the scenario buildings. HAZUS estimates that about 804 buildings will be at least moderately damaged. This is over 67 percent of the buildings in the City. There are an estimated 3 buildings that will be completely destroyed. The table below summarizes the expected damage by general occupancy for the buildings in the City of Downey planning area.
Table 3.74: HAZUS 100-Year Flood Expected Building Damage by Occupancy Damage
Level 1-10 11-20 21-30 31-40 41-50 >50
Occupancy Count % Count % Count % Count % Count % Count % Agriculture 0 0 0 0 0 0 0 0 0 0 0 0
Commercial 43 80 11 20 0 0 0 0 0 0 0 0
Education 0 0 0 0 0 0 0 0 0 0 0 0
Government 0 0 0 0 0 0 0 0 0 0 0 0
Industrial 40 60 24 36 3 4 0 0 0 0 0 0
Other
Residential 0 0 0 0 0 0 0 0 0 0 0 0
TOTAL 638 599 145 53 4 3
City of Downey Hazard Mitigation Plan 3-174
The table below summarizes the expected damage to essential facilities in the City of Downey planning area. As you will see, the damage is not significant (less than moderate).
Table 3.75: HAZUS 100-Year Flood Expected Damage to Essential Facilities Facility Total At Least Moderate
(Greater than 50% damage) At Least Substantial
(Greater than 50% damage) Loss of Use
(Greater than 50% on day 1)
Emergency
Operations Center 2 0 0 0
Fire Assets 9 0 0 0
Medical 4 0 0 0
Law Enforcement 2 0 0 0
Schools and
related assets 53 0 0 0
TOTAL 70 0 0 0
*Includes all assets within city boundaries and not just those from the city.
The total building-related losses were $568.77 Million. 53 percent of the estimated losses were related to the business interruption of the City of Downey. The residential occupancies made up 11.54 percent of the total loss. See Appendix A – Additional Hazard Analysis Information for building related economic loss estimates, Table 6.
HAZUS estimates the number of households that are expected to be displaced from their homes due to the flood incident and associated potential evacuation. HAZUS also estimates the number of displaced individuals that will require accommodation in temporary public shelters. The model estimates 3,126 households (or 9,378 people) will be displaced due to the flood. Displacement includes households evacuated from within or very near to the inundated area. Of these, 621 people (out of a total population of 187,241) will seek temporary shelter in public shelters. 500-Year Flood Analysis
The total economic loss estimated for the flood is $5,184.91 Million, which represents 43.72 percent of total replacement value of the scenario buildings. HAZUS estimates that about 4,130 buildings will be at least moderately damaged. This is over 70 percent of the buildings in the City.
There are an estimated 66 buildings that will be completely destroyed. The table below summarizes the expected damage by general occupancy for the buildings in the City of Downey planning area.
City of Downey Hazard Mitigation Plan 3-175
Table 3.76: HAZUS 500-Year Flood Expected Building Damage by Occupancy Damage
Level 1-10 11-20 21-30 31-40 41-50 >50
Occupancy Count % Count % Count % Count % Count % Count % Agriculture 0 0 0 0 0 0 0 0 0 0 0 0
Commercial 90 44 108 53 6 3 1 0 0 0 0 0
Education 1 100 0 0 0 0 0 0 0 0 0 0
Government 6 67 3 33 0 0 0 0 0 0 0 0
Industrial 87 36 120 49 30 12 5 2 2 1 0 0
Other
Residential 1 100 0 0 0 0 0 0 0 0 0 0
TOTAL 1,451 2,403 875 613 173 66
*Includes all assets within city boundaries and not just those from the city.
The table below summarizes the expected damage to essential facilities in the City of Downey planning area. As you will see, the damage is not significant (less than moderate).
Table 3.77: HAZUS 500-Year Flood Expected Damage to Essential Facilities Facility Total At Least Moderate
(Greater than 50% damage) At Least Substantial
(Greater than 50% damage) Loss of Use
(Greater than 50% on day 1)
Emergency
Operations Center 2 0 0 0
Fire Assets 9 0 0 0
Medical 4 0 0 0
Law Enforcement 2 0 0 0
Schools and
related assets 53 0 0 0
TOTAL 70 0 0 0
*Includes all assets within city boundaries and not just those from the city.
The total building-related losses were $2,922.01 Million , 44 percent of the estimated losses were related to the business interruption of the City of Downey. The residential occupancies made up 14.11 percent of the total loss. See Appendix A – Additional Hazard Analysis Information Section 500-Year flood for building related economic loss estimates, Table 6.
HAZUS estimates the number of households that are expected to be displaced from their homes due to the flood incident and associated potential evacuation. HAZUS also estimates the number of displaced individuals that will require accommodation in temporary public shelters. The model
City of Downey Hazard Mitigation Plan 3-176
estimates 11,941 households (or 35,854 people) will be displaced due to the flood. Displacement includes households evacuated from within or very near to the inundated area. Of these, 2,065 people (out of a total population of 187,241) will seek temporary shelter in public shelters.
An Urban Flood NRI annualized frequency is not available as FEMA does not include this hazard as one of the eighteen natural hazards in the National Risk Index. However, Riverine Flooding annualized frequency data for the City is available and represents the average number of recorded Riverine Flooding hazard occurrences (event-days) per year over the period of record (24 years). Per the County of Los Angeles Hazard Mitigation Plan “Floods can occur at any time but are most common with annual winter storms packed with subtropical moisture. Severe flooding is most likely to occur during strong El Niño events, generally ranging from 2 to 7 years and lasting from as little as 6 months to as long as 4 years.”102 The table below outlines the annualized frequency for riverine flooding, based on FEMA NRI data, for the City.
Table 3.78: Riverine Flooding Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(1996 – 2019) 24 years Annualized Frequency
550501 106 4.4 events per year
550502 106 4.4 events per year
550601 106 0 events per year
550602 106 0 events per year
550700 106 4.4 events per year
550801 106 0 events per year
550802 106 4.4 events per year
550901 106 0 events per year
550902 106 0 events per year
551001 106 4.4 events per year
551002 106 0 events per year
551101 106 0 events per year
551102 106 0 events per year
551201 106 0 events per year
551203 106 0 events per year
551204 106 0 events per year
551300 106 0 events per year
102 Chief Executive Office, OEM. (2020). County Los Angeles All Hazard Mitigation Plan. Retrieved from County- of-Los-Angeles-All-Hazards-Mitigation-Plan-APPROVED-05-2020.pdf (lacounty.gov)
City of Downey Hazard Mitigation Plan 3-177
City of Downey
Census Tracts Events on Record
(1996 – 2019) 24 years Annualized Frequency
551401 106 0 events per year
551402 106 0 events per year
551501 106 0 events per year
551502 106 0 events per year
551700 106 0 events per year
551801 106 0 events per year
551802 106 0 events per year
553400 106 0 events per year
980012 106 0 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
Vulnerability and Impacts
Population: Of greatest concern in the event of a flooding event is the potential for injury or loss of life. Seniors, persons with disabilities, and low-income persons are likely to be impacted during these events. Persons experiencing homelessness who are outside during flood conditions may experience property damage or be unable to access shelter. Possessions such as sleeping bags or electronic devices may be damaged or swept away by these floodwaters.
No properties within Downey are considered by FEMA to be within a 100-year flood zone. A small segment of the southeast portion of the city is located within the 500-year flood zone (0.2% Annual Chance of Flooding). Localized flooding in Downey is a concern and more study is needed to determine specific populations that may be vulnerable to urban/flash flooding.
Table 3.79: Vulnerability and At-Risk Populations in 500-year Flood Zone Vulnerability and At-
Risk/Underserved Category Count Percent of Total
Persons with Disabilities 1,140 9% (12,419)
Elderly (65+ years) 746 6% (12,552)
Elderly (75-84 years) 226 7% (3,373)
Elderly (85 years and over) 43 3% (1,701)
Language other than English 5,831 8% (70,341)
Speak English less than very well 1,703 8% (22,641)
People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count. Due to the transient
nature of this at-risk group,
location-specific analyses
were not possible.
City of Downey Hazard Mitigation Plan 3-178
Vulnerability and At-
Risk/Underserved Category Count Percent of Total
Note: This analysis was based on the census tracts that reside within the 500-year flood zone.
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services Property:
A small segment of the southeast portion of the city is located within the 500-year flood zone (0.2% Annual Chance of Flooding). Any physical assets within these mapped boundaries can potentially be inundated if enough precipitation falls, exceeding the storm drain infrastructure design capacity in these areas. Since the Army Corp of Engineers completed raising the channel levees in 2000, no properties within Downey are considered by FEMA to be within a 100-year flood zone (a flood of such intensity that it has a one percent chance of occurring in any given year). More study and analysis are needed to determine exposure and damage estimates to flash flooding due to localized flooding, which results from deficiencies in the existing storm drain system.
Localized flooding in Downey may result from deficiencies in the existing storm drain system.
Intensified development of properties over time has increased the amount of impermeable surfaces thereby reducing the watersheds ability to infiltrate storm water. This increase in impermeable surfaces has increased the quantity of water runoff, which is the amount of water directed toward drains from properties. This storm drain system consists of a network of reinforced concrete boxes along city streets that direct storm water toward flood control channels via reinforced concrete pipes. The system is typically designed to handle 10-year floods. However, there are parts of Downey where the amount of surface runoff now exceeds the design of this system and periodic flooding may occur. These areas include the arterial streets which may produce traffic delays and possible service interruptions during rainfall events. More study is needed to determine specific and repetitive loss areas.
The deficiencies in the storm drain system may be addressed by increasing the capacity of the storm drain system. However, upgrading the storm drain system involves capital outlays and coordination among government agencies. Downey has considered measures that reduce the volume of stormwater and the best method to reduce any further strain on the storm drain system.
These measures may include the following:
• Require hydrology studies that address the impact by developments on downstream stormwater capacity.
City of Downey Hazard Mitigation Plan 3-179
• Maximize the amount of landscape planting areas and other pervious surfaces on properties to decrease runoff volumes.
• Encourage the use of pervious materials that allow for stormwater infiltration and retention in areas used as driveways, walkways, courtyards, plazas, and other areas that are typically paved with impervious surfaces.
• Minimize the surface areas of rooftops, parking lots, driveways, walkways, and other impervious surfaces.
• Encourage building roof designs which direct rooftop runoff to pervious surfaces for stormwater infiltration and retention.
• Preserve existing natural vegetated areas and encourage vegetation and soil restoration where feasible.
• Incorporate stormwater runoff systems into site design to provide areas for infiltration and retention of stormwater runoff on site.
Table 3.80: Assets/Structures Vulnerability and Impact Summary: 100-year and 500-year Flood per FEMA Flood Zone areas
Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Airport*
(No major airports in Downey) 0 0% There are no major
airports in Downey
Government
(City Hall and Public Works) 0 0%
Columbia Memorial Space
Center 0 0%
Hospitals 0 0%
Major Shopping Centers 0 0%
National Register of Historic
Places 0 0%
Library 0 0%
Parks 1
(500-year flood only) 9%
Schools 1
(500-year flood only) 3%
Fire Stations 0 0%
Police Stations 0 0%
Source: Los Angeles County Assessors, National Bridge Inventory, City of Downey
Economic: Impacts to the local economy could include business interruptions, lost or reduced wages from potential relocation of populations, infrastructure and resource downtime costs. Other
City of Downey Hazard Mitigation Plan 3-180
secondary hazard impacts such as reduced water quality or resource availability, which could in turn raise costs of water processing and distribution, are also possible results from a severe flooding event. Data is limited for economic loss due to the isolated and urban nature of flooding in Downey.
Changes in Development and Future Development: The Federal Emergency Management Agency (FEMA) publishes maps that identify areas of Downey subject to flooding in the event of a major storm. These Flood Insurance Rate Maps (FIRMs) indicate areas that may be inundated in the event of a 100-year or a 500-year storm. Since the Army Corp of Engineers completed raising the channel levees in 2000, no properties within Downey are considered by FEMA to be within a 100-year flood zone (a flood of such intensity that it has a one percent chance of occurring in any given year). Areas that are designated for future residential development do not fall within the 100-year floodplain and are not subject to specialized flood construction requirements.
Climate Change: The effects of climate change in severity of impact for urban flood for the City is increasing the likelihood of it occurring. As global average temperatures increase, evaporation increases adding moisture into the atmosphere which results in more precipitation.103 Heavy precipitation events are expected to increase as much as three (3) times the historical average by the end of the century. Although heavy precipitation does not necessarily result in flooding, the potential increases and in some location moderate amounts of precipitation can lead to serious damage.
103 Environmental Protection Agency. (n.d.). Climate Change Indicators: U.S. and Global Precipitation. Retrieved from https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation .
City of Downey Hazard Mitigation Plan 3-181
FEMA NRI Expected Annual Loss Estimates
An Urban Flood NRI Expected Annual Loss calculation is not available as FEMA does not include this hazard as one of the eighteen natural hazards in the National Risk Index. However, a riverine flood NRI Expected Annual Loss score is available for the City. This rating represents the community's relative level of expected building, population, and agriculture loss each year due to riverine flood when compared to the rest of the United States. The table below outlines the riverine flood Expected Annual Loss for the City of Downey planning area.
Table 3.81: Riverine Flood Expected Annual Loss
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550501 $480 $10 $0 $490 30.8 Very Low
550502 $142 $4 $0 $146 28.1 Very Low
550601 $0 $0 $0 $0 0.0 No Expected Annual
Losses
550602 $0 $0 $0 $0 0.0 No Expected Annual
Losses
550700 $862 $55 $0 $917 33.2 Very low
550801 $0 $0 $0 $0 0.0 No Expected Annual
Losses
550802 $264 $3 n/a $267 29.3 Very Low
550901 $0 $0 $0 $0 0.0 No Expected Annual
Losses
550902 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551001 $1,047 $19 $0 $1,066 33.9 Very Low
551002 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551101 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551102 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551201 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551203 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551204 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551300 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551401 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551402 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551501 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551502 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551700 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551801 $0 $0 $0 $0 0.0 No Expected Annual
Losses
551802 $0 $0 $0 $0 0.0 No Expected Annual
Losses
City of Downey Hazard Mitigation Plan 3-182
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
553400 $0 $0 $0 $0 0.0 No Expected Annual
Losses
980012 $0 $0 $0 $0 0.0 No Expected Annual
Losses
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
City of Downey Hazard Mitigation Plan 3-183
3.18 Utility Loss Hazard Profile
Although FEMA does not require non-natural hazards for inclusion in a hazard mitigation plan, the City wishes to rank and mitigate against a comprehensive list of hazard events that could impact the city. Due to the nature of non-natural hazards and the discretionary status regarding their inclusion, this hazard has been qualitatively assessed for public education and informing its inclusion within the hazard ranking and mitigation process.
Table 3.82: Utility Loss Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Utility Loss 2 7 12 26 45 49
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.18.1 Utility Loss Hazard Description
Utility loss includes losses of power, water, sewer, and other critical services. A power outage is the loss of the electricity supply to an area. In addition to natural hazards, power failure can result from a defect in a power station, damage to a power line or other part of the distribution system, a short circuit, or overloading of electricity mains.
A power outage may be referred to as a blackout if power is lost completely, or as a brownout if some power supply is retained, but the voltage level is below the minimum level specified for the
City of Downey Hazard Mitigation Plan 3-184
system, and a short circuit indicates a loss of power for a short amount of time (usually seconds).
Some brownouts, called voltage reductions, are made intentionally to prevent a full power outage.
The absence of electrical power at City facilities for extended periods can, in some areas, preclude water deliveries where pumping is necessary. This will result in a loss of water and sewer services to the local area. In and of themselves, these short duration utility losses typically do not generate large hazards that can dramatically impact the City. However, utility losses in conjunction with other hazards can make response efforts much more difficult. For example, since water is typically pumped from a source, a loss of water during a fire will decrease the effectiveness of firefighting systems, or a sewer system failure in conjunction with a flood will result in increased localized flooding in residences and the streets. Since water and sewer systems usually require power sources for the pumps, adequate backup power should be available for critical systems in the event of a power failure.
3.18.2 Utility Loss Hazard History
California Energy Crisis 2000 and 2001 Blackouts
In 2000 and 2001, blackouts occurred in Southern California due to losses in transmission or generation and/or extremely severe temperatures that lead to heavy electric power consumption.
The crisis brought to light many critical issues surrounding the state’s power generation and distribution system, including its dependency on out-of-state resources. Although California has implemented effective energy conservation programs, the State continues to experience both population growth and weather cycles that contribute to a heavy demand for power. 2011 Southwest Blackout
In September of 2011, five separate power grids serving nearly 7 million people in southern California, western Arizona, and parts of Mexico went out in the span of 11 minutes. The power outage, termed the 2011 Southwest Blackout, was the largest power failure in California history and lasted over twelve hours.
Affected metropolitan areas were crippled from the loss of traffic signals; as a result, trains stopped running and freeways experienced extreme congestion. Public gas stations were also unable to pump fuel, leaving many vehicles stranded. The power outage also caused several
City of Downey Hazard Mitigation Plan 3-185
sewer pumping stations to fail, resulting in contaminated beaches and potentially unsafe water supplies. Restaurants and grocery stores also suffered large losses from spoiled food. 2020 Rolling Blackouts
Prolonged heat waves strain the state’s energy grid. August of 2020 marked the first time in 20 years when a blackout was ordered due to insufficient energy supplies. Hundreds of thousands lost power amid a heat wave. The power grid was already strained with the unprecedented heat wave with temperatures in much of the state reaching triple digits. California buys energy from neighboring states, but during heat waves like this one, those states have less energy to spare leading to rolling blackouts.104
The table below shows utility company PSPS, public safety power shutoffs of six days or more as documented by the California Public Utilities Commission Table 3.83: PSPS Greater than 6 or More Days (2017-2023) Utility Outage Start Full
Restoration Outage Duration Total Customers
Impacted Residential Commercial
SDG&E 12/5/17 12/11/17 6 days, 0 hrs., 52 min. 87 61 26 PG&E 10/26/19 11/2/19 6 days, 18 hrs., 46 min. - - -
SCE 1/15/21 1/21/21 6 days, 1 hr., 36 min. 555 470 73
SCE 1/14/21 1/20/21 6 days, 11 hrs., 26 min. 2,709 2,575 34 SCE 1/14/21 1/21/21 7 days, 1 hr., 26 min. 3,395 3,157 137 SCE 1/15/21 1/21/21 6 days, 7 hrs. 299 144 155
SCE 1/14/21 1/21/21 7 days, 7 hrs., 50 min. 714 638 52
PG&E 1/19/21 1/26/21 7 days, 16 hrs., 1 min. 1,363 1,281 79
3.18.3 Utility Loss Hazard Probability, Frequency, and Magnitude Currently, failure mechanism to calculate the probability of utility losses, without evaluating the failure as a cascade effect from natural hazards (e.g., earthquakes). However, California has implemented numerous conservation measures to ensure an adequate power supply, and the City has worked with its water suppliers to ensure an adequate water supply. As utilities lines and
104 ABC News. (2022). Why California Has Blackouts: A Look at the Power Grid. Retrieved from https://abcnews.go.com/US/california-blackouts-power-grid/story?id=89460998
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assets run through the entire City, the steering committee has assumed equal vulnerability for all portions of the City.
Vulnerability and Impacts
Utility loss impacts the life safety and health of the city by impairing essential services including water, power, and healthcare access. This may lead to injury, illness, or death to the Public. Utility loss impacts property damage and critical infrastructure of the city by significantly impairing the function of critical infrastructure. Depending on the cause of the utility loss (such as a storm,) damage to buildings or infrastructure may be damaged. Utility loss impacts the economy for the city by halting a significant portion of economic income for various businesses depending on the sector. Utility loss impacts the changes in development and impact of future development for the city by potentially pausing current developments and highlighting potential mitigation measures for future development. Utility loss impacts underserved and at-risk populations of the city by The effects of climate change in severity of impact for utility loss for the City is a general likelihood of increased utility interruptions. This is due to more frequent and intense severe weather due to climate change.105
105 NASA. Global Climate Change. (n.d.). Extreme Weather and Climate Change. Retrieved from https://climate.nasa.gov/extreme-weather/
City of Downey Hazard Mitigation Plan 3-187
3.19 Wildfire Smoke/Air Quality Hazard Profile
Table 3.84: Wildfire Smoke/Air Quality Total Risk Score Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk Score
(Probability x
Consequence)
Wildfire
Smoke/Air
Quality
3 7 15 23 45 69
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.19.1 Wildfire Smoke/Air Quality Description
Wildfire Smoke
The Southern California peak wildfire season (and therefore heightened risk of poor air quality) spans from late spring (May/June) to October. While the length of wildfire season depends on summer temperature, rainfall, wind, and historic data showing that most fires occur from May until October, rising temperatures and decreased rainfall that come with climate change have the season beginning earlier and ending later each year.106 When wind is paired with the hot, dry weather, it is a perfect combination for the spread of wildfire and the smoke that comes with them. Santa Ana winds in Southern California are strong, dry downslope that blow from the mountains toward the coast, causing wildfires to ignite and spread
106 Western Fire Chiefs Association. (2022). California Fire Season; In-Depth Guide. Retrieved from https://wfca.com/articles/california-fire-season-in-depth-guide/
City of Downey Hazard Mitigation Plan 3-188
rapidly. These winds reach up to forty miles per hour and sometimes top hurricane strength winds of 74 mph and above.
Due to the frequent massive sizes of wildfires, there’s a potential for air pollution to reach far outside the initial burn zone. Winds also move smoke away from the fire contributing to atmospheric mixing, which means that smoke impacts to the public around the fire may be lessened while winds move the smoke plume long distances into communities far from where the wildfire is burning.107 Due to this movement of wildfire smoke, the entirety of the City of Downey is at risk to poor air quality.
The composition of wildfire smoke is a complex mixture of particulate matter, carbon monoxide, hydrocarbons and other organic chemicals, nitrogen oxides and trace minerals. The Clean Air Act requires the Environmental Protection Agency (EPA), to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. The EPA has set NAAQS for six principal pollutants, three of which may be of concern during wildfire smoke events: particulate matter, ground level ozone and carbon monoxide. The following table elaborates on the specific details of each of the three pollutants.
Table 3.85: Wildfire Smoke Event Pollutants
Particulate Matter
(PM)
A mixture of solids and aerosols which vary greatly in size, shape, and chemical composition. Particles are classified by their diameter by the measure of microns. Particles with a diameter of 10 microns or less (PM10) can be inhaled by the lungs and may impact the individual’s health. Fine Particulate Matter refers to particles with a diameter of 2.5 microns or less (PM2.5).108
Ground-Level Ozone
(O3)
Ozone is a highly reactive and unstable gas which is part of smog. This pollutant forms due to complex reactions between chemicals present in the emissions from industrial plants, vehicles, consumer products, and other sources. At higher concentrations, its effects are comparable to household bleach in terms of killing living cells. It forms in greater amounts on hot, sunny, and calm days. In urban areas of California, ozone concentrations regularly surpass existing health standards in the summertime.109
107 Air Now. (2019). Wildfire Smoke, A Guide for Public Health Officials. Retrieved from https://www.airnow.gov/sites/default/files/2021-09/wildfire-smoke-guide_0.pdf 108 California Air Resources Board. (n.d.). Inhalable particulate Matter and Health (PM2.5 and PM10). Retrieved from https://ww2.arb.ca.gov/resources/inhalable-particulate-matter-and-health 109 California Air Resources Board. (n.d.). Ozone & Health. Retrieved from https://ww2.arb.ca.gov/resources/ozone-and-health
City of Downey Hazard Mitigation Plan 3-189
Carbon Monoxide
(CO)
A colorless, odorless gas forms from the incomplete combustion of carbon fuels. These fuels include natural gas, gasoline, or wood. The source of this reaction includes vehicles, power plants, and incinerators.110
Air Pollution
General air pollution can be caused by both manmade and natural sources. Natural sources include windblown or kicked-up dust, dirt and sand, volcanic smoke and burning materials, such as wildfires. When the sources are manmade, that means that the actions of humans created the pollution. Humans tend to be the leading causes of air pollution in cities. Manmade sources primarily include combustion, largely referring to the exhausts of planes, trains, automobiles, and industrial businesses. The latter may include power plants, factories and refineries, biomass burning; the burning of coal or plant matter for energy, heating or cooking, and agriculture.111 California leads the charts for the cities in the United States with the worst air pollution. The top five cities with the worst (PM2.5) include Los Angeles-Long Beach and Bakersfield. The top five U.S, cities with the worst ozone, also include Los Angeles-Long Beach and Bakersfield.
California’s unhealthy air quality, relative to other U.S. states, is due to several factors including a population of thirty-nine million people, major port industry and a growing economy that creates significant emissions from traffic, diesel trucks, construction, agriculture, and domestic emissions.
In any given year, California’s most polluted cities also tend to be most affected by wildfires.
Human-driven climate change is expected to further aggravate the intensity of wildfires in the future by creating warmer and drier conditions, which will worsen the air quality in the state.112 In addition to wildfires, increased levels of pollution from automobiles are usually more common during the wintertime in western states due to nitrite particles.113 Wildfire smoke and other pollutants can therefore overlap and further decrease the overall air quality.
110 California Air Resources Board. (n.d.). Carbon Monoxide & Health. Retrieved from https://ww2.arb.ca.gov/resources/carbon-monoxide-and-health 111 IQAir. (2023). What Causes Bad Air Quality? Retrieved from https://www.iqair.com/us/world-air-quality 112 ibid
113 American Lung Association. (n.d.). Particle Pollution. Retrieved from https://www.lung.org/clean- air/outdoors/what-makes-air-unhealthy/particle-pollution
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3.19.2 Wildfire Smoke/Air Quality Hazard History
Poor air quality within California has been a long-standing health hazard. The California Air Resources Board was created in 1967 as a merger of the Bureau of Air Sanitation and the California Motor Vehicle Pollution Control Board to address the severe air pollution. Since then, additional efforts have been made to regulate and control air pollution (smog,) such as addressing automobile emissions, factory discharge, and other emission sources. California was the first state to establish tailpipe emission standards in an effort to reduce air pollution.114 Over the past four decades, the average air quality in Los Angeles County has generally decreased in lower Air Quality Index (AQI) levels. (See Section 3.17.3 for details on AQI.) While the number of days with unhealthy or hazardous air has decreased, the number of days with moderate air quality has steadily increased. While moderate air quality is considered to be acceptable, individuals with pre-existing health conditions may be impacted by this level of pollution. The following table outlines the detailed historic air quality data of Los Angeles County, considering all criteria air pollutants.115
Table 3.86: Los Angeles County Annual Air Quality
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
2022 40 231 65 28 1 94
2021 41 228 70 26 - 96
2020† 60 169 77 44 16 137
2019 66 213 57 28 1 86
2018 35 222 89 18 1 108
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Very
Unhealthy or
Hazardous Air
Days
Very
Unhealthy Air
Days
Total
Unhealthy/
Hazardous Air
Days
2017 38 207 74 38 8 120
2016† 32 230 81 19 4 104
2015 26 207 95 36 1 132
2014 23 234 80 26 2 108
2013 22 243 75 25 0 100
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
2012† 33 203 93 35 2 130
2011 17 227 82 36 3 121
114 California Air Resource Board. (n.d.). History. Retrieved from https://ww2.arb.ca.gov/about/history 115 Los Angeles Almanac. (n.d.). Annual Air Quality Los Angeles County. Air Quality Days by Year, 1989-2022.
Retrieved from https://www.laalmanac.com/environment/ev01b.php
City of Downey Hazard Mitigation Plan 3-191
2010 32 219 99 15 0 114
2009 34 213 71 43 4 118
2008† 31 213 68 46 8 122
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
2007 45 193 91 30 6 127
2006 64 172 79 39 11 129
2005 57 170 77 49 12 138
2004† 29 179 87 67 4 158
2003 41 154 83 57 30 170
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
2002 34 152 104 53 22 179
2001 20 159 127 48 11 186
2000† 27 164 114 51 10 175
1999 17 180 140 27 1 168
1998 54 193 72 22 24 118
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
1997 33 171 116 32 13 161
1996† 42 154 91 47 32 170
1995 43 108 109 45 60 214
1994 22 124 96 41 82 219
1993 29 108 111 45 72 228
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
1992† 22 104 92 59 89 240
1991 16 117 96 51 85 232
1990 17 118 84 57 89 230
1989 10 69 110 63 113 286
1988† 9 65 84 63 145 292
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
1987 6 91 87 52 129 268
1986 7 72 92 54 140 286
1985 10 82 91 43 139 273
1984† 5 71 101 52 137 290
1983 11 102 80 37 135 252
Year
Good
Quality
Air Days
Moderate
Quality Air
Days
Unhealthy Air
for Sensitive
Groups
Unhealthy Air
Days
Very
Unhealthy or
Hazardous Air
Days
Total
Unhealthy/
Hazardous Air
Days
1982 8 83 91 54 129 274
1981 4 56 99 46 160 305
1980† 6 74 80 47 159 28
City of Downey Hazard Mitigation Plan 3-192
3.19.3 Wildfire Smoke/Air Quality Hazard Probability, Frequency, and Magnitude
Wildfire Smoke and poor Air Quality is a frequent and repeatable hazard within both California and the City of Downey planning area. Air monitoring indicates that 9/10 Californians breathe unhealthy levels of one or more pollutants at some point during the year.116 When the air quality reaches unhealthy levels, an alert is sent out to the affected areas recommending people stay indoors and avoid outdoor activities.
The magnitude of poor air quality is highly dependent on a few factors such as time of day, temperature, ongoing industrial pollutants, wildfires, and more. Air quality generally is the worst during the summer. However, as smoke from wildfires can travel hundreds of miles, a severe wildfire in a different state (or country) can impact the air quality in the City of Downey planning area both during wildfire season and at any other time during the year. The long travel distance of smoke was demonstrated in June of 2023 when Canadian wildfires caused New York City to experience record-setting air pollution, turning the skies orange with contaminants.117 The Air Quality Index is the EPA’s measure for reporting air quality. The AQI is divided into six categories with each category having increasing levels of risk, especially for immunocompromised individuals and those with pre-existing health conditions. This scale dictates when air quality alerts are sent out to the affected locations.
116 California Air Resources Board. (n.d.). Health & Air Pollution. Retrieved from https://ww2.arb.ca.gov/resources/health-air-pollution
117 Columbia climate School. Climate, Earth, and Society. (2023). State of the Planet, How Wildfire Smoke Can Travel Thousands of Miles, and How to Protect Yourself. Retrieved from https://news.climate.columbia.edu/2023/06/08/how-wildfire-smoke-can-travel-thousands-of-miles-and-how-to- protect-yourself/
City of Downey Hazard Mitigation Plan 3-194
The table below shows the six categories and the corresponding recommendations for each.
Table 3.87: Air Quality Index – Basics for Ozone & Particle Pollution 118 Daily AQI
Color
Levels of
Concern
Values of
Index Description of Air Quality
Green Good 0 to 50 Air quality is considered satisfactory, and air pollution poses little or no risk.
Yellow Moderate 51 to 100
Air quality is acceptable; however, for some
pollutants there may be a moderate health concern
for a very small number of people. For example,
people who are unusually sensitive to ozone may
experience respiratory symptoms.
Orange
Unhealthy for
Sensitive
Groups
101 to 150
Although general public is not likely to be affected at this AQI range, people with lung disease, older
adults and children are at a greater risk from
exposure to ozone, whereas persons with heart and
lung disease, older adults and children are at
greater risk from the presence of particles in the air.
Red Unhealthy 151 to 200
Everyone may begin to experience some adverse
health effects, and members of the sensitive groups
may experience more serious effects.
Purple Very
Unhealthy 201 to 300
This would trigger a health alert signifying that
everyone may experience more serious health
effects.
Maroon Hazardous 301 or higher
This would trigger health warnings of emergency
conditions. The entire population is more likely to be
affected.
EPA establishes an AQI for five (5) major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by EPA to protect public health - ground-level ozone, particle pollution (also known as particulate matter, including PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
When weather conditions are conducive to wildfire ignition, the NWS local Forecast Office issues a series of advisories. The table below outlines the fire advisories issued by NWS as conditions warrant.119
118 United States Environmental Protection Agency. (n.d.). Air Data Basic Information. Retrieved from https://www.epa.gov/outdoor-air-quality-data/air-data-basic-information 119 National Weather Service. (n.d.). Understanding Wildfire Warnings, Watches and Behavior. Retrieved from https://www.weather.gov/safety/wildfire-ww .
City of Downey Hazard Mitigation Plan 3-195
Table 3.88: National Weather Service Fire Advisories
Type Definition
Fire Weather
Watch
Issued to alert land managers and the public that upcoming weather conditions (e.g., combination of strong winds and low humidity, dry and unstable air mass, and/or lightning) could result in extensive wildland fire occurrence or extreme fire behavior.
It is issued when critical fire weather conditions are possible but not imminent or occurring.
Red Flag
Warning
Issued by NWS, in conjunction with land management agencies, to alert land managers to an ongoing or imminent critical fire weather pattern (e.g., combination of strong winds and low humidity, dry and unstable air mass, and/or lightning). It is issued when fire conditions are ongoing or expected to occur shortly.
Extreme Fire
Behavior
Issued when a wildfire is likely to run out of control. It is often hard to predict because fires tend to behave erratically and sometimes dangerously. To issue this alert, one (1) or more of the following criteria must be met – moving fast (i.e., high rate of spread), prolific crowning and/or spotting, presence of fire whirls, and/or strong convection column.
The Figure below shows the Air Quality in Downey on a map while Figure 3.38 shows the AQI over the course of a week in September of 2023.
Figure 3.37: Air Quality in and around Downey
City of Downey Hazard Mitigation Plan 3-196
Figure 3.38: Downey AQI (September 8 – September 11, 2023)120
Poor Air Quality Impacts and Precautions
When the AQI is at a heightened level, being outside is of particular concern for individuals with pre-existing health conditions. If exposed to poor air quality conditions (specifically ozone), physical symptoms may include difficulty breathing, coughing, inflammation, and reduced lung function.121 Exposure to wildfire smoke induces similar irritation to the eyes, nose, and throat.122 These symptoms may be more severe for those with pre-existing conditions.
As poor air quality due to either local pollution or wildfire smoke can linger over an area for an extended period, remaining at home for the entire duration isn’t a viable option for many individuals. Utilizing an N95 mask can help filter out the larger particles associated with wildfire smoke and other particulates when outside.123 Additionally, installing a High Efficiency particulate Air filter (HEPA) filter is extremely valuable tool to have running at home or workplace. While effective, HEPA filters may require monitoring and frequent replacement due to the intensity of wildfire smoke and other pollutants clogging up the filtration medium.
120 IQAir. (n.d.). Air quality in Downey. Retrieved from https://www.iqair.com/us/usa/california/downey 121 National Institutes of Health. (2011). Bad Air Day. Air Quality and Your Health. Retrieved from https://newsinhealth.nih.gov/2011/07/bad-air-day
122 New York State Department of Health. (n.d.). Exposure to Smoke from Fires. Retrieved from https://health.ny.gov/environmental/outdoors/air/smoke_from_fire.htm 123 Washington State Department of health. (2019) Wildfire Smoke and Face Masks. Retrieved from https://clark.wa.gov/sites/default/files/dept/files/public- health/wildfire%20smoke/DOH_Wildfire_Smoke_Face_Masks_Factsheet.pdf
City of Downey Hazard Mitigation Plan 3-197
A cost-effective option for individuals may be either buying or building a Corsi-Rosenthal box (originally utilized during COVID-19,) which uses Minimum Efficiency Reporting Values (MERV) filters and a common box fan to filter out particulates in large quantities of air in a short period of time.124 Higher MERV values are equivalent to a HEPA filter, and therefore can target similar pollutants such as both wildfire smoke and viral particles and effectively reduce particulates in a room.125,126 The following graphic demonstrates the basic construction of the Box, using a box fan, 4 MERV-13 filters, some cardboard, and tape. The overall cost is well under $100.127 Figure 3.39: Corsi-Rosenthal Box 128
The wildfire annualized frequency value represents the modeled frequency of wildfire hazard occurrences, in event days, per year. The table below outlines the annualized frequency for wildfire, based on FEMA NRI data, for the City.
124 UC Davis College of Engineering. R. Corsi. (2022). Science in Action: How to Build a Corsi-Rosenthal Box.
Retrieved from https://engineering.ucdavis.edu/news/science-action-how-build-corsi-rosenthal-box 125 Characterizing the performance of a DIY air filter. (2022). Rachael Dal Porto, Monet N. Kunz, Theresa Pistochini, Richard L. Corsi, Christopher D. Cappa. Aerosol Science and Technology. Retrieved from https://www.medrxiv.org/content/10.1101/2022.01.09.22268972v1.full 126 Yale Climate connections. Samantha Harrington. (2023). Wildfire smoke getting into your home? Build a DIY Corsi-Rosenthal air filter. Retrieved from https://yaleclimateconnections.org/2023/01/wildfire-smoke-getting-into- your-home-build-a-diy-corsi-rosenthal-air-filter/
127 Corsi_header image (n.d.). Edge Collective. Retrieved from https://cleanaircrew.org/corsi_header/ 128 Ibid.
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Table 3.89: Wildfire Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(2021 Dataset) Annualized Frequency
550501 n/a 0% chance per year
550502 n/a 0% chance per year
550601 n/a 0% chance per year
550602 n/a 0% chance per year
550700 n/a 0% chance per year
550801 n/a Less than 0.001% chance per year
550802 n/a 0% chance per year
550901 n/a 0% chance per year
550902 n/a 0% chance per year
551001 n/a 0% chance per year
551002 n/a 0% chance per year
551101 n/a 0% chance per year
551102 n/a 0% chance per year
551201 n/a 0% chance per year
551203 n/a 0% chance per year
551204 n/a 0% chance per year
551300 n/a 0% chance per year
551401 n/a 0% chance per year
551402 n/a 0% chance per year
551501 n/a 0% chance per year
551502 n/a 0% chance per year
551700 n/a 0% chance per year
551801 n/a 0% chance per year
551802 n/a 0% chance per year
553400 n/a 0% chance per year
980012 n/a 0% chance per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
Vulnerability and Impacts
Population: There are no recorded incidents of loss of life from wildfires in the city. Smoke and air pollution from wildfires can be a severe health hazard and pose a greater threat to residents, especially for sensitive populations, including the elderly and those with respiratory and cardiovascular diseases. Smoke generated by wildfire consists of visible and invisible emissions that contain particulate matter (e.g., soot, tar, water vapor, and minerals), gases (e.g., carbon monoxide, carbon dioxide, nitrogen oxides), and toxics (e.g., formaldehyde, benzene). Emissions from wildfires depend on the type of fuel, the moisture content of the fuel, the efficiency (or
City of Downey Hazard Mitigation Plan 3-199
temperature) of combustion, and the weather. Public health impacts associated with wildfire include difficulty in breathing, odor, and reduction in visibility.
The California Environmental Protection Agency created the online map CalEnviroScreen 3.0 that generates a score based on a community’s vulnerability to pollution and its population characteristics. The scale for vulnerability is shown in percentage ranges, from 1% to 10% (least vulnerable) to 91% to 100% (most vulnerable). 33% of residents live in a census tract with a score of 75% or higher. Smoke from wildfires may exacerbate these conditions and vulnerabilities.
City of Downey Hazard Mitigation Plan 3-200
Table 3.90: Vulnerability and At-Risk Populations: Wildfire/Smoke Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
Source: US Census Bureau 2022 ACS
Property: Wildfire severity is categorized into three zones: moderate, high, and very high.
Downey has no areas located in any of the zones.
Table 3.91: Assets/Structures Vulnerability and Impact Summary: Wildfire/Smoke Vulnerable Categories
Applicable to this Hazard
Number of Assets of
Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Airport*
(No major airports in Downey) 0 0% There are no major
airports in Downey
Government
(City Hall and Public Works) 0 0%
Columbia Memorial Space
Center
0 0%
Hospitals 0 0%
Major Shopping Centers 0 0%
National Register of Historic
Places
0 0%
Library 0 0%
Parks 0 0%
Schools 0 0%
Fire Stations 0 0%
Police Stations 0 0%
Trees 0 0%
Source: Los Angeles County Assessors, City of Downey
Economic: Air quality issues related to wildfires could adversely impact the economy and way of life for residents in Downey. People may be less reluctant to go outside thereby impacting commerce.
Changes in Development and Future Development: Growth over the past decade has been modest. Between 2010 and 2020, as reported by the U.S. Census, the population of Downey
City of Downey Hazard Mitigation Plan 3-201
grew approximately 0.9 percent, from 111,922 to 112,901 residents. The Southern California Association of Governments (SCAG) growth forecasts predict a steady increase in population through 2045. This projected population growth will increase the City’s exposure to air quality issues from wildfires.
Climate Change: Although Downey is not anticipated to be directly affected by wildfire, more frequent and intense wildfires are likely to occur in the region. The region’s risk of wildfire is likely to continue to rise due to increased dryness of vegetation, compounded by productivity of plants in the spring (which creates more fuel for dry season wildfires). Air quality issues in Downey are likely to increase due to wildfires burning hotter, longer, and more frequently, thus producing more smoke.129 Changes in climate are creating warmer and drier conditions which are leading to longer and more active wildfire seasons. Studies have shown that the number of large wildfires has more than doubled in the western United States. Furthermore, projections show that a one (1) degree Fahrenheit increase in the average annual temperature could increase the average burned area per year by as much as 600% (in some types of forests) in the western United States.130
FEMA NRI Expected Annual Loss Estimates
A wildfire NRI EAL score, and rating represent a community's relative level of expected building, population, and agriculture loss each year due to wildfires when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. The table below outlines the wildfire EAL for the City.
Table 3.92: Wildfire Expected Annual Loss Estimates
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550501 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550502 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550601 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550602 $0 $0 $0 $0 0.0 No Expected
Annual Losses
129 U.S Fire Administration. (n.d.). Wildland Urban Interface. Retrieved from https://www.usfa.fema.gov/stories/wildland-urban-interface/ 130 NOAA. (2023). Wildfire Climate Connection. Retrieved from https://www.noaa.gov/noaa-wildfire/wildfire- climate-connection.
City of Downey Hazard Mitigation Plan 3-202
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550700 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550801 $0 $64 $0 $64 33.4 Very Low
550802 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550901 $0 $0 $0 $0 0.0 No Expected
Annual Losses
550902 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551001 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551002 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551101 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551102 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551201 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551203 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551204 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551300 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551401 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551402 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551501 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551502 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551700 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551801 $0 $0 $0 $0 0.0 No Expected
Annual Losses
551802 $0 $0 $0 $0 0.0 No Expected
Annual Losses
553400 $0 $0 $0 $0 0.0 No Expected
Annual Losses
980012 $0 $0 $0 $0 0.0 No Expected
Annual Losses
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
City of Downey Hazard Mitigation Plan 3-203
3.20 Windstorm Hazard Profile
Table 3.93: Windstorm Total Risk Score
Hazard
Probability Consequence Total Risk
Probability
Factor
Sum of
Weighted
Extent
Factors
Sum of
Weighted
Vulnerability
Factors
Sum of
Weighted
Impact
Factors
Consequence
Score
Total Risk
Score
(Probability x
Consequence)
Windstorm 1 4 12 19 35 22
Classification
Low (L) 1 0–4 0–6 0–13 0–23 0–33
Medium (M) 2 5–8 7–12 14–26 24–46 34–66
High (H) 3 9–12 13–18 27–39 47–69 67–100
This legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard.
The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors.
The Total Risk Score is a product of Probability and Consequence.
3.20.1 Windstorm Hazard Description
Strong Winds
Strong winds, also known as damaging winds, are classified as exceeding 58 mph and often originate from thunderstorms.131 Most severe thunderstorm winds that cause damage at the ground are a result of outflow generated by the downdraft of a thunderstorm. The table below outlines the different types of strong winds.132 In coastal regions a strong wind is called a gale. Gale winds are sustained surface winds between 34 and 47 knots (39 to 54 mph).
131 Federal Emergency Management Agency. (n.d.). Strong Wind. Retrieved from https://hazards.fema.gov/nri/strong-wind .
132 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Types of Damaging Winds.
Retrieved from https://www.nssl.noaa.gov/education/svrwx101/wind/types/ .
City of Downey Hazard Mitigation Plan 3-204
Table 3.94: Types of Strong Winds
Type Description
Straight-
line Wind
Term used to define any thunderstorm wind that is not associated with a rotation and is used mainly to differentiate from tornadic winds.
Downdraft A small-scale column of air that rapidly winds towards the ground.
Macroburst
An outward burst of strong winds at or near the surface with horizontal dimensions larger than 2.5 miles and occurs when a strong downdraft reaches the surface.
Macroburst winds may begin over a smaller area and then spread out over a wider area, sometimes producing damage similar to a tornado. Although usually associated with thunderstorms, macrobursts can occur with showers too weak to produce thunder.
Microburst
A small, concentrated downburst that produces an outward burst of strong winds at or near the surface. Microbursts are small (less than 2.5 miles across) and short-lived (five (5) to 10 minutes) with maximum windspeeds sometimes exceeding 100 mph. There are two (2) kinds of microbursts – wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.
Gust Front
The leading edge of rain-cooled air that clashes with warmer thunderstorm inflow.
Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.
Derecho
A widespread, long-lived windstorm that is associated with a band of rapidly moving showers or thunderstorms. A typical derecho consists of numerous downbursts and downburst clusters. By definition, if the wind damage swath extends more than 240 miles and includes wind gusts of at least 58 mph or greater along most of its length, then the event may be classified as a derecho.
Haboob A wall of dust that is pushed out along the ground from a thunderstorm downdraft at high speeds.
Santa Ana
Winds
A seasonal phenomenon in Southern California occurs between October and March. These dry winds occur when cold air moves southward into the Great Basin between the Sierra Nevada Mountain Range and the Southern California Coastal Range. The cold air mass is characterized by unusually high pressure near the land surface. As the wind moves through canyons and passes, the wind accelerates to speeds of 40 mph (35 knots) with gusts up to about 70 mph (60 knots).
*A downburst is the general term used to broadly describe macro and microbursts.
3.20.2 Windstorm Hazard History
The National Centers for Environmental Information (NCEI) has reported two strong wind events between 2000 and 2023. There have been no declared emergencies or disasters for strong winds in the State. To indicate the potential for a destructive windstorm, table
3.95 lists the two NCEI strong wind events in the vicinity of the City.
City of Downey Hazard Mitigation Plan 3-205
Table 3.95: Strong Wind Events for Los Angeles (2000-2023) Location
County /
Zone Date Time Type Death Injury
Property
Damage
Crop
Damage
X N Los
Angeles
(Zone)
X N Los
Angeles
(Zone)
11/27/2004 12:20 Strong
Wind 1 1 0.00K 0.00K
Catalina
Island (Zone)
Catalina
Island (Zone) 12/30/2014 23:00 Strong
Wind 1 0 0.00K 0.00K
Total 2 1 0.00K 0.00K
Table 3.96: Major Windstorms in the Vicinity of the City of Downey Date Location and Damage
November 5-6, 1961 Santa Ana winds: Fire in Topanga Canyon February 10-11, 1973 Strong storm winds: 57 mph at Riverside, 46 Newport Beach. Some 200 trees uprooted in Pacific Beach alone
October 26-27, 1993 Santa Ana winds: Fire in Laguna Hills October 14, 1997 Santa Ana winds: 87mph gusts in central Orange County - secondary impact: large fire in Orange County
December 29, 1997 60+ mph gusts in Santa Ana
March 28-29, 1998
Strong storm winds in Orange County: sustained 30-40 mph. 70mph gusts in Newport Beach, gust up to 60mph in Huntington Beach.
Trees down, power out, and damage across Orange and San Diego Counties - 1 person dead in Jamul
September 2, 1998 Strong winds from thunderstorms in Orange County with gusts to 40mph. Large fires in Orange County
December 6, 1998 Thunderstorm in Los Alamitos and Garden Grove: gust of 50-60 mph called “almost a tornado”
December 21-22, 1999
Santa Ana winds: 68mph gusts in Campo, 53mph gusts in
Huntington Beach, and 44mph winds in Orange - home and tree damage in Hemet
March 5-6, 2000 Strong thunderstorm winds at the coast: gust 60 mph at Huntington Beach. Property damage and trees downed along the coast.
April 1, 2000 Santa Ana winds: gust 93 mph at Mission Viejo, 67 mph in Anaheim Hills.
December 25-26, 2000 Santa Ana winds: gust 87 mph at Fremont Canyon. Damage and injuries in Mira Loma, Orange and Riverside Counties.
February 13, 2001 Thunderstorm gust to 89 mph in east Orange.
City of Downey Hazard Mitigation Plan 3-206
Date Location and Damage
February 19, 2005 ¾” hail reported in Anaheim. In Laguna Hills thunderstorm winds had estimated gusts of 81 mph.
March 27, 2007
A microburst hit Fullerton Airport. The top recorded winds were only 30 mph, but spotters estimated winds of at least 45 mph. Another thunderstorm hit Encinitas.
March 22, 2023
The strongest tornado to hit the county since 1983 happened in Montebello. The EF-1 tornado had estimated peaked winds at 110 mph.
City of Downey Hazard Mitigation Plan 3-207
Figure 3.40: City of Downey Historic Wind Event
City of Downey Hazard Mitigation Plan 3-208
3.20.3 Windstorm Hazard Probability, Frequency, and
Magnitude
The Beaufort Wind Scale was developed to estimate and report wind speeds when a measuring apparatus is not available (e.g., open sea). It was invented in the 1805 by Sir Francis Beaufort of the British Navy as a way to interpret wind conditions at sea. Since then, the scale has been modified to include the effects on land. The table below outlines the 13- force classification that comprise the Beaufort Wind Scale.133 Table 3.97: Beaufort Wind Scale
Force Wind
(knots) Classification Appearance of Wind Effects
On the Water On Land
0 https://www.spc.noaa.gov/faq/tornado/beaufort.html .
City of Downey Hazard Mitigation Plan 3-209
Force Wind
(knots) Classification Appearance of Wind Effects
On the Water On Land
9 41 – 47 Strong Gale
High waves (23 to 32 feet),
sea begins to roll, dense
streaks of foam, and spray
may reduce visibility.
Slight structural damage
occurs, and slate blows off
roofs.
10 48 – 55 Storm
Very high waves (29 to 41
feet) with overhanging crests,
sea white with densely blown
foam, heavy rolling, and
lowered visibility.
Seldom experienced on
land, trees broken or
uprooted, and considerable
structural damage.
11 56 – 63 Violent Storm
Exceptionally high waves (37
to 52 feet), foam patches
cover sea, and visibility more
reduced.
--
12 > 63 Hurricane
Air filled with foam, waves
over 45 feet, sea completely
white with driving spray, and
visibility greatly reduced.
See Saffir-Simpson
Hurricane Wind Scale.
Winds of this speed and greater have been known to cause tornado-like conditions, damaging property and potentially inhibiting utilities, telecommunications, and transportation systems in and around the City.
Considering that Santa Ana Winds are a regular occurrence in Southern California, strong winds are likely to continue to occur, although infrequently, in the City. It should be noted that the Steering Committee did not identify any specific parts of the City which tend to be adversely affected by windstorms. It is, therefore, assumed the entire City is equally vulnerable to windstorm events. The extent and intensity of windstorms is highly variable and may change depending on a wide array of factors. In the past, high winds have toppled trees, damaged traffic signals, and in rare cases, caused minor injuries to residents. In response, the City determined windstorm was still a threat to the City and warranted inclusion in the Plan update. Figure 3.41 below provides information on the average wind speeds for the City of Downey in 2022. Please note, the Santa Ana winds typically occur in short bursts which can last a few days running into weeks, therefore, the winds patterns in the table below may not adequately portray the spikes in wind speeds which accompany the Santa Ana Winds.
City of Downey Hazard Mitigation Plan 3-210
Figure 3.41: City of Downey Average Wind Speeds
Climate change impacts on high wind events in the State requires further analysis. Future updates to this plan will consider new research on this topic.
The probability of occurrence for strong winds in the City is high because severe weather events occur annually. The strong wind annualized frequency value represents the average number of recorded strong wind hazard occurrences, in event days, per year over the period of record (34 years). The table below outlines the annualized frequency for strong winds, based on FEMA NRI data, for the City.
Table 3.98: Strong Wind Annualized Frequency (FEMA National Risk Index) City of Downey
Census Tracts Events on Record
(1986 – 2021) 34 years Annualized Frequency
550501 6 0.2 events per year
550502 6 0.2 events per year
550601 6 0.2 events per year
550602 6 0.2 events per year
550700 6 0.2 events per year
550801 6 0.2 events per year
550802 6 0.2 events per year
550901 6 0.2 events per year
550902 6 0.2 events per year
551001 6 0.2 events per year
551002 6 0.2 events per year
City of Downey Hazard Mitigation Plan 3-211
City of Downey
Census Tracts Events on Record
(1986 – 2021) 34 years Annualized Frequency
551101 6 0.2 events per year
551102 6 0.2 events per year
551201 6 0.2 events per year
551203 6 0.2 events per year
551204 6 0.2 events per year
551300 6 0.2 events per year
551401 6 0.2 events per year
551402 6 0.2 events per year
551501 6 0.2 events per year
551502 6 0.2 events per year
551700 6 0.2 events per year
551801 6 0.2 events per year
551802 6 0.2 events per year
553400 6 0.2 events per year
980012 6 0.2 events per year
Annualized frequency is defined as the expected frequency or probability of a hazard occurrence per year.
Vulnerability and Impacts
Population: Community members are the most vulnerable to high wind events. However, there are also segments of the population that are especially exposed to the indirect impacts of high winds, particularly the loss of electrical power. These populations include the elderly or disabled, especially those with medical needs and treatments dependent on electricity.
Severe wind events can harm all people throughout Downey but may have a greater effect on the safety of people experiencing homelessness and those working outdoors.
Populations that work outside or have respiratory illnesses may be impacted by severe wind events as they can generate dust and other contaminants that can affect the health of residents and workers.
Table 3.99: Vulnerability and At-Risk Populations: Strong Winds Vulnerability and At-
Risk/Underserved Category Count Percent
Persons with Disabilities 12,419 11.3% of residents
Elderly (65+ years) 12,552 11.4% of residents
Elderly (75-84 years) 3,373 3.1% of residents
Elderly (85 years and over) 1,701 1.5% of residents
Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
City of Downey Hazard Mitigation Plan 3-212
Vulnerability and At-
Risk/Underserved Category Count Percent
People Experiencing Homelessness 82 persons
Less than 1% of Los
Angeles County Homeless
Count
Source: US Census Bureau 2022 ACS, 2024 Los Angeles Homeless Services Authority Greater Los Angeles Homeless Count, CA Department of Developmental Services
Property: There are 23,194 buildings within the census tracts that define the planning area.
Most of these buildings are residential. All of these buildings are considered to be exposed to the adverse impacts of severe wind. The frequency and degree of damage will depend on specific locations and intensity of the wind event. Mobile homes, older buildings, and structures in poor condition are more prone to damage. The city estimates that in 2020, fewer than 25 housing units were in severe need of replacement or substantial rehabilitation due to housing conditions. These units, for example, may be suffering from neglect and these buildings may be structurally unsound.
General damage from high wind events can be both direct and indirect. Direct impacts refer to what the wind physically destroys, while indirect impacts include additional costs, damages and losses attributed to secondary hazards spawned by the event. Construction practices and building codes can help maximize the resistance of the structures to damage.
Secondary impacts of damage caused by wind events often result from damage to infrastructure. Downed power and communications transmission lines, coupled with disruptions to transportation, create difficulties in reporting and responding to emergencies.
These indirect impacts of a wind event put tremendous strain on a community. Public gathering places such as schools and parks may have increased impacts at certain times of the day. Due to the random nature of the hazard, a more specific risk assessment was not conducted for this plan.
Table 3.100: Property Vulnerability: Strong Winds
Vulnerable Category Count Percent
Occupied Housing Unit: Mobile
Home 96 0.3% of occupied housing
units
Source: US Census Bureau 2022 ACS
City of Downey Hazard Mitigation Plan 3-213
Table 3.101: Assets/Structures Vulnerability and Impact Summary: Strong Winds Vulnerable Categories
Applicable to this Hazard
Number of Assets
of Concern
% of Total
Number of
Assets
Additional
Considerations, if
applicable
Government
(City Hall and Public Works) 2 100% -
Columbia Memorial Space
Center 1 100% -
Hospitals 3 100% -
Major Shopping Centers 5 100% -
National Register of Historic
Places 2 100% -
Library 1 100% -
Parks 11 100%
Trees and vegetation
could be adversely
impacted.
Schools 28 100% -
Fire Stations 4 100% -
Police Stations 1 100% -
Trees 15,600 100%
Trees may be
vulnerable to strong
winds.
Source: Los Angeles County Assessors
Table 3.102: Exposed Assets and Potential Total and Adjusted Impact Loss Estimates: Strong Winds
Category/Type Number of
Structures
Total Potential
Loss and
Replacement
Va lue *
Adjusted Potential Loss and
Replacement Value*
Due to the low extent of strong winds
in the City of Downey, this calculation
estimates that 1% of assets c ould be
impacted during a significant event.
Residential, Single
Residential, Multi-
Unit Residential
Structures
22,291 $4,815,267,965.00 $48,152,679.65
Commercial, Office
Buildings, Stores,
Service Stations
885 $847,087,183.00 $8,470,871.83
Industrial,
Manufacturing,
Warehouses
291 $175,933,384.00 $1,759,333.84
Recreational,
Cultural, Community 21 $58,482,613.00 $584,826.13
City of Downey Hazard Mitigation Plan 3-214
Centers, Athletic
Fields/Facilities
Institutional, Schools,
Hospitals/Healthcare,
Churches
107 $720,531,246.00 $7,205,312.46
Source: Los Angeles County Assessor
*Property Loss and Replacement Value does not include land valuations Economic: Winds typically don’t have long-term impacts on the economy. The most common problems associated with high winds are loss of utilities. Downed power lines can cause power outages, leaving large parts of the city isolated, and without electricity, water, and communication. Damage may also limit timely emergency response and the number of evacuation routes.
Changes in Development and Future Development: Recent development that has been constructed based on the latest building code and construction standards should be more resilient to this hazard. Future development projects should consider wind and severe weather hazards at the planning, engineering and architectural design stage with the goal of reducing vulnerability.
Severe winds occur periodically and generally do not affect populations to the degree that they would need to migrate in and out of the city. It is unlikely that severe wind will affect land use and development because the development review process will take steps to mitigate or minimize the impacts of severe wind. Continued efforts to bury utilities will help to make the city more resilient to wind.
Climate Change: The effects of climate change in severity of impact for strong winds for the City is expected to increase in frequency and severity. Climate change has been linked to an increase in straight-line wind events.134
FEMA NRI Expected Annual Loss Estimates
A strong wind NRI Expected Annual Loss score and rating represent a community's relative level of expected building, population, and agriculture loss each year due to strong winds when compared to the rest of the United States. The table below outlines the strong wind Expected Annual Loss for the City of Downey planning area.
134 Rebecca Owen. Eos. (2023.) Climate Change May Be Causing Stronger Thunderstorm Wind Gusts.
Retrieved from https://eos.org/articles/climate-change-may-be-causing-stronger-thunderstorm-wind-gusts
City of Downey Hazard Mitigation Plan 3-215
Table 3.103: Strong Wind Expected Annual Loss
City of
Downey
Census
Tracts
Population
Equivalence
Building
Value
Agriculture
Value
Total
Expected
Annual Loss
Expected
Annual
Loss Score
Rating
550501 $189 $0 $0 $189 9.12 Very Low
550502 $222 $1 $0 $223 10.47 Very Low
550601 $307 $1 $0 $307 13.14 Very Low
550602 $233 $1 $0 $233 10.80 Very Low
550700 $376 $1 $0 $377 14.85 Very Low
550801 $245 $1 $0 $246 11.26 Very Low
550802 $138 $0 $0 $138 7.22 Very Low
550901 $235 $1 $0 $236 10.92 Very Low
550902 $296 $1 $0 $297 12.84 Very Low
551001 $205 $1 $0 $206 9.77 Very Low
551002 $197 $0 $0 $197 9.45 Very Low
551101 $207 $1 $0 $209 9.89 Very Low
551102 $285 $1 $0 $286 12.50 Very Low
551201 $192 $0 $0 $193 9.26 Very Low
551203 $196 $0 $0 $196 9.38 Very Low
551204 $213 $0 $0 $213 10.07 Very Low
551300 $285 $1 $0 $286 12.50 Very Low
551401 $232 $0 $0 $232 10.75 Very Low
551402 $239 $1 $0 $240 11.03 Very Low
551501 $257 $1 $0 $258 11.65 Very Low
551502 $222 $1 $0 $222 10.43 Very Low
551700 $331 $1 $0 $331 13.76 Very Low
551801 $169 $1 $0 $169 8.37 Very Low
551802 $229 $1 $0 $229 10.68 Very Low
553400 $205 $0 $0 $206 9.77 Very Low
980012 $0 $1 $0 $1 0.45 Very Low
Expected Annual Loss is calculated utilizing an equation that includes exposure, annualized frequency, and historic loss ratios. (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio)
City of Downey Hazard Mitigation Plan 3-216
3.21 Climate Change
With the release of the California Adaptation Planning Guide 135 (APG) in June 2020, the City aimed to include the effects of climate change into the Hazard Mitigation Plan update.
Climate change is already impacting California and will continue to affect it for the foreseeable future.136 For example, the average temperature in most areas of California is already 1°F higher than historical levels, and some areas have seen average increases in excess of 2°F. Similarly, sea levels along the coast of central and southern California increased over 15 centimeters (5.9 inches) during the 20th century.19 Over the long term, reducing GHG emissions can help make climate change less severe.
Differences in exposure, sensitivity, and adaptive capacity affect an individual’s or community’s vulnerability to climate change. Both sensitivity and exposure are directly affected by population growth, development patterns, and success in addressing underlying vulnerabilities, including equity and social vulnerability.
Primary climate change effects can exacerbate hazards seen at local and regional levels, such as wildfires and associated smoke, drought, landslides, flooding, and human health hazards.
As identified in the “Understanding Regional Characteristics” portion of the APG, the City is located in the South Coastal Region of California. As a result, the City considered the following climate change impacts as recommended by the APG:
• Increased Temperatures
• Reduced Precipitation
• Reduced Tourism
• Reduced Water Supply
• Wildfire Risk
• Public Health – Heat and Air Quality
135 California Adaptation Planning Guide (2020). Governor’s Office of Emergency Services. Retrieved from Californ https://www.caloes.ca.gov/wp-content/uploads/Hazard-Mitigation/Documents/CA- Adaptation-Planning-Guide-FINAL-June-2020-
Accessible.pdf#search=adaptation%20planning%20guideia Adaptation Planning Guide 136 Office of Environmental Health Hazard Assessment, “Indicators of Climate Change in California,” California Environmental Protection Agency, 2019, accessed August 2019, https://oehha.ca.gov/climate- change/document/indicators-climate-change-california.
City of Downey Hazard Mitigation Plan 3-217
Climate change has fundamentally altered the state’s hydrologic system – intensifying severe weather as it shifts from extreme dry to extreme wet situations.
According to the California Water Watch, many rural areas are still experiencing water supply challenges, especially communities that rely on groundwater supplies which have been depleted due to prolonged drought. While March 2023 has brought promising rain and snow, it will take more than a single wet year for California to fully recover from the last three years – the driest ever recorded in state history.137
137 California Water Watch (n.d.) Tracking Current Weather Conditions. Retrieved from https://cww.water.ca.gov/
City of Downey Hazard Mitigation Plan 4-i
MITIGATION STRATEGIES
Table of Contents
4.1 Mitigation Strategy ............................................................................................ 1
4.1.1 Mitigation Goals and Objectives ....................................................................... 1
4.1.2 Mitigation Strategies and Actions .................................................................... 3
4.1.3 Mitigation Action Plan ....................................................................................... 4
4.1.4 Mitigation Strategy/Action Timeline Parameters ............................................. 5
4.1.5 Mitigation Strategy/Action Estimated Cost ...................................................... 5
4.1.6 Mitigation Strategy/Action Prioritization Process ........................................... 5
4.1.7 Mitigation Priorities ........................................................................................... 8 List of Tables
Table 4. 1: Overall Plan Goals and Objectives ............................................................ 2 Table 4. 2: New and Ongoing Mitigation Strategies .................................................. 10 Table 4. 3: Completed, Deferred and Deleted Mitigation Strategies ........................ 17
City of Downey Hazard Mitigation Plan 4-1
4.1 Mitigation Strategy
The heart of the mitigation plan is the mitigation strategy, which serves as the long-term blueprint for reducing the potential losses identified in the risk assessment. The mitigation strategy describes how the community will accomplish the overall purpose, or mission, of the planning process. In this section, mitigation goals and objectives were reevaluated and updated; and mitigation actions/projects were updated/amended, identified, evaluated, and prioritized.
4.1.1 Mitigation Goals and Objectives
In this section of the Plan, the risk assessment identified the City of Downey as prone to 16 hazards. See Chapter 1 section 1.1.2 Identify Hazards. The Steering Committee and community stakeholders understand that although hazards cannot be eliminated altogether, stakeholders can work together toward building a disaster-resilient community.
The following is a table of goals and objectives. The five goals represent the City's long- term and strategic vision to accomplish and achieve successful mitigation efforts. The associated objectives are specific strategies and steps identified to assist City personnel and local government representatives in attaining the listed goals.
The mitigation goals provide guidelines for developing mitigation projects to provide prioritized hazard reduction. The goals are based on the goals from the 2018 Hazard Mitigation Plan, the findings of the Risk Assessment, and input from the Steering Committee and characterize long-term hazard reduction targets as well as the enhancement of current mitigation capabilities.
Table 4.1 includes the Plan goals and corresponding mitigation objectives. These strategies were developed and reviewed by the Steering Committee using knowledge of the local area (including high-hazard areas and sensitive populations), review of past efforts, findings of the Risk Assessment, and identification of mitigation projects.
City of Downey Hazard Mitigation Plan 4-2
Table 4. 1: Overall Plan Goals and Objectives
1. Protect Life and Property
• Strategy 1a: Implement activities that assist in protecting lives by making homes, businesses, infrastructure, critical facilities, and other properties more resistant to losses from natural and man-made hazards
• Strategy 1b: Improve hazard assessment information to make recommendations for encouraging preventative measures for existing and new developments in areas vulnerable to natural and man-made hazards • Strategy 1c: Protect lives by creating and implementing mitigation activities to reduce the potential impact hazard events may have on the general population • Strategy 1d: Promote business continuity planning for local businesses
2. Promote Public Awareness of the Vulnerability to Hazardous Events and Ongoing Mitigation Strategies
• Strategy 2a: Develop and implement educational and outreach programs to increase public awareness of the risks associated with natural and man-made hazards
• Strategy 2b: Provide information on tools; partnership opportunities, financial assistance, and other resources to assist in implementing hazard mitigation activities
3. Preserve The Environment
• Strategy 3a: Protect, rehabilitate, and enhance natural systems to serve natural and man-made hazard mitigation functions
• Strategy 3b: Improve hazard assessment information to make recommendations for encouraging preventative measures to reduce the effects of climate change within the City
City of Downey Hazard Mitigation Plan 4-3
4. Promote Community-wide Involvement with Hazard Mitigation. • Strategy 4a: Strengthen coordination and encourage participation among public agencies, citizens, non-profit organizations, businesses, and industry to gain a vested interest in hazard mitigation
• Strategy 4b: Encourage leadership within public and private organizations to prioritize and implement local hazard mitigation activities
5. Increase the Capacity of Emergency Operations Functionality • Strategy 5a: Develop and maintain policies to ensure the development and continuation of hazard mitigation initiatives
• Strategy 5b: Strengthen emergency operational functionality by increasing collaboration and coordination among public agencies, non-profit organizations, businesses, and industry
• Strategy 5c: Coordinate and integrate natural and man-made hazard mitigation activities, where appropriate, with Emergency Operations Plans and procedures It should be noted that the overall priorities for mitigation planning did not change much during the update. However, the current plan goals were revised to be clearer and more direct. Table 4.2 and Table 4.3 in Chapter 4.1.7 provides the mitigation actions.
4.1.2 Mitigation Strategies and Actions
Plan participants assessed 61 hazard mitigation strategies/actions, including strategies from FEMA guidance documents, strategies from the 2018 Hazard Mitigation Plan and suggestions from steering committee members and stakeholder engagement during the planning workshop and steering committee meetings. See Appendix B – Stakeholder Engagement for engagement supporting documentation.
These mitigation strategies/projects resulted in 18 new strategies/actions, 14 ongoing mitigation strategies/actions and 20 completed strategies/actions. A total of 3
City of Downey Hazard Mitigation Plan 4-4
strategies/actions were deferred and 6 strategies/actions were deleted. The new and ongoing mitigation strategies and actions are included in Chapter 4, Table 4.2 and Table
4.3 depict the complete, deferred, and deleted mitigation strategies. Each entities’ Mitigation Strategies & Actions are organized as follows:
• New Mitigation Actions- New actions identified during this 2023 update process. • Ongoing Mitigation Actions- These ongoing actions were included in the previous update and have yet to be completed. Some of these actions have no definitive end. During the 2023 update, these "ongoing" mitigation strategies/actions were modified and/or amended, as needed, to better define the strategy/action.
• Completed Mitigation Actions- Completed actions since 2018. Completed actions also included a brief description of the Status, resulting reduction or limitation of hazard impact(s) achieved, to show the resulting benefits of implementing the mitigation initiative.
• Deferred Mitigation Actions– Actions are deferred when risk can’t be validated, or additional time is needed to validate the potential impacts and benefits of the action.
• Deleted Mitigation Actions– These actions are no longer relevant or applicable because other mitigation actions addressed the mitigating need, or the hazard vulnerability changed resulting in reduced risk.
4.1.3 Mitigation Action Plan
The Action Plan for each mitigation project is presented in Table 4.1. The table is designed to capture important details intended to support the implementation of the strategy/action.
City of Downey Hazard Mitigation Plan 4-5
4.1.4 Mitigation Strategy/Action Timeline Parameters
While the preference is to provide definitive project completion dates, this is not possible for every mitigation strategy/action. Therefore, the parameters for the timeline (Timeframe Completion) are as follows:
• Short Term = to be completed in 1 to 2 years
• Medium Term = to be completed in 3-5 years
• Long Term = to be completed after the 5-year planning period
4.1.5 Mitigation Strategy/Action Estimated Cost
While the preference is to provide definitive costs (dollar figures) for each mitigation strategy/action, this is not possible for every mitigation strategy/action. Therefore, the estimated costs for the mitigation initiatives identified in this Plan were identified as high, medium, or low, using the following ranges:
• Low – less than $10,000
• Medium – from $10,000 to $100,000
• High – greater than $100,000
4.1.6 Mitigation Strategy/Action Prioritization Process The mitigation strategy/action must be prioritized according to a benefit/cost analysis of the proposed projects and their associated costs 1. The City is utilizing a different method of prioritizing actions compared to the previous plan. The mitigation strategies/actions were prioritized and evaluated using the STAPLEE+E method which uses eight criteria for evaluating a mitigation action: Social, Technical, Administrative, Political, Legal, Economic, Environmental, and Equity. Within each of those criteria are additional
1 Code of Federal Regulation. (2023). 44 CFR, Section 201.6(c)(3)(iii).
City of Downey Hazard Mitigation Plan 4-6
considerations. Because equity is essential to reducing risk to the whole community 2, an additional measure was added to the criteria totaling eight barometers. An explanation of how each of the STAPLEE+E criteria may be applied to evaluation of mitigation actions follows:
Social: Mitigation actions are acceptable to the community if they do not adversely affect a particular segment of the population, do not cause relocation of lower income people, and if they are compatible with the community’s social and cultural values. • Will the proposed action adversely affect one segment of the population? • Will the action disrupt established neighborhoods, break up voting districts, or cause the relocation of lower income people?
Technical: Mitigation actions are technically most effective if they provide a long-term reduction of losses and have minimal secondary adverse impacts. • How effective is the action in avoiding or reducing future losses? • Will it create more problems than it solves?
• Does it solve the problem or only a symptom?
• Does the mitigation strategy address continued compliance with the NFIP? Administrative: Mitigation actions are easier to implement if the jurisdiction has the necessary staffing and funding.
• Does the jurisdiction have the capability (staff, technical experts, and/or funding) to implement the action, or can it be readily obtained? • Can the community provide the necessary maintenance?
• Can it be accomplished in a timely manner?
Political: Mitigation actions can truly be successful if all stakeholders have been offered an opportunity to participate in the planning process and if there is public support for the action.
2 Executive Order 13985. (2021). Advancing Racial Equity and Support for Underserved Communities through the Federal Government. Retrieved from https://www.whitehouse.gov/briefing-room/presidential- actions/2021/05/20/executive-order-on-climate-related-financial-risk/.
City of Downey Hazard Mitigation Plan 4-7
• Is there political support to implement and maintain this action? • Is there a local champion willing to help see the action to completion? • Is there enough public support to ensure the success of the action? • How can the mitigation objectives be accomplished at the lowest cost to the public? Legal: It is critical that the jurisdiction or implementing agency have the legal authority to implement and enforce a mitigation action.
• Does the community have the authority to implement the proposed action? • Are the proper laws, ordinances, and resolutions in place to implement the action? • Are there any potential legal consequences?
• Is there any potential community liability?
• Is the action likely to be challenged by those who may be negatively affected? • Does the mitigation strategy address continued compliance with the NFIP? Economic: Budget constraints can significantly deter the implementation of mitigation actions. It is important to evaluate whether an action is cost-effective, as determined by a cost benefit review, and possible to fund.
• Are there currently sources of funds that can be used to implement the action? • What benefits will the action provide?
• Does the cost seem reasonable for the size of the problem and likely benefits? • What burden will be placed on the tax base or local economy to implement this action?
• Does the action contribute to other community economic goals such as capital improvements or economic development?
• What proposed actions should be considered but be “tabled” for implementation until outside sources of funding are available?
Environmental: Sustainable mitigation actions that do not have an adverse effect on the environment, comply with federal, state, and local environmental regulations, and are consistent with the community’s environmental goals, have mitigation benefits while being environmentally sound.
City of Downey Hazard Mitigation Plan 4-8
• How will this action affect the environment (land, water, endangered species)? • Will this action comply with local, state, and federal environmental laws and regulations?
• Is the action consistent with community environmental goals? Equity: Does not create an opportunity for unequal distribution of resources; racism; affect a particular segment of the population, including communities of color, communities that face discrimination based on sex, sexual orientation or gender identity, persons with disabilities, persons who identify with a certain religion, persons with Limited English Proficiency, or rural communities, etc.
• Is the action consistent and systematically fair?
4.1.7 Mitigation Priorities
Priority was assessed by requesting that each new and ongoing mitigation action submitted and or updated by City departments and local stakeholders be ranked by each of the eight criteria factors, this is a different method of prioritizing actions compared to the previous plan. Each STAPLEE+E criterion is evaluated on a scale from 1 to 5, with 1 defined as strongly disagree and 5 as strongly agree.
• In the 2023 plan update, the STAPLEE+E methodology scale included an eighth criteria: equity. Therefore, the highest favorable score would be 40, meaning that said action scored 5 out of all eight categories.
• In the 2018 plan update, a simplified Benefit-Cost Review was applied in order to prioritize the mitigation recommendations for implementation. The priority for implementing mitigation recommendations depended upon the overall cost effectiveness of the recommendation, while considering monetary and non- monetary costs and benefits associated with each action.
Mitigation strategies/actions with the highest scores represent those mitigation initiatives that represent the highest priority since the previous plan. In addition to the STAPLEE+E Method, the Steering Committee identified the strategies/actions that reflected shifts in local resources, City needs and capabilities. It should be noted that, although the STAPLEE+E Method provides a standardized process for assigning priority/importance
City of Downey Hazard Mitigation Plan 4-9
across all mitigations actions/projects there may be additional factors and considerations that elevate the status of a particular mitigation strategy/action. This is why the Steering Committee's input is also an important consideration in this process.
Table 4.2 depicts the City of Downey’s new and ongoing mitigation actions and other relevant information, in alphabetical order by hazard commencing with goals that are applicable to all hazards. The table identifies the hazards mitigated, corresponding goals & objectives, year initiated, responsible department, potential funding sources & monetary amount, and the status of each of the City’s mitigation actions. Table 4.3 showcases the City of Downey’s completed, deferred, and deleted mitigation actions.
City of Downey Hazard Mitigation Plan 4-10
Table 4. 2: New and Ongoing Mitigation Strategies
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
1 Identify and pursue funding
opportunities, in addition to the FEMA
grant programs, to develop and
implement local mitigation activities
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
1C
2016,
updated
in 2018
and 2023
Office of Emergency
Management,
Community
Development
Hazard Mitigation
Grant Program
(HMGP)
&
In Kind Matches
Long
Ongoing
The Office of Emergency Management will seek
funding for mitigation action every 5 years.
Priority:
Low
STAPLEE+E Prioritization Score:
37/40
2 Identify, implement, and promote new
collaborative programs and outreach
focusing on residents, city departments,
and industry stakeholders to promote
active emergency preparedness
activities that reduce hazards.
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
2A, 4A
2016,
updated
in 2018
and 2023
Office of Emergency
Management
In Kind Matches
&
$50,000
Long
Ongoing
Priority:
High
STAPLEE+E Prioritization Score:
35/40
3 Provide or facilitate/participate business
continuity workshops for business
owners to learn the importance of
disaster mitigation and how to create an
Emergency Operations Plan for their
business
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
1D
2016,
updated
in 2018
and 2023
Office of Emergency
Management
Local General Fund
&
$1,000
Long
Ongoing
Priority:
Medium
STAPLEE+E Prioritization Score:
37/40
4 Increase public awareness of severe
weather mitigation activities to include
shelter in place and air quality warnings
and appropriate actions taken.
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
2B
2016,
updated
in 2018
and 2023
Office of Emergency
Management
Local General Fund
&
35,000
Medium
Ongoing
The Office of Emergency Management modified the
action from being windstorm hazard specific to all
hazards.
Priority:
High
STAPLEE+E Prioritization score:
36/40
5 Coordinate with the Army Corp of
Engineers and nearby cities for
evacuation planning.
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
5C 2023 Office of Emergency
Management
Local General Fund
&
In Kind matches
Medium
New
Priority:
Medium
STAPLEE+E Prioritization score:
33/40
City of Downey Hazard Mitigation Plan 4-11
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
6 Develop and implement a public
outreach campaign to increase
awareness of the Downey Alerts System
and encourage resident opt-in for
notifications
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
5B
2016,
updated
in 2018
and 2023
Office of Emergency
Management
Hazard Mitigation
Grant Program
(HMGP)
&
$35,000
Long
Ongoing
Memorandum of Understandings (MOUs) were
developed with FEMA to harness existing platforms
to send IPAWs. This provided the capability to send
messages to all jurisdictions whether or not have
opted in.
Priority:
Low
STAPLEE+E Prioritization score:
36/40
7 Identify locations and install emergency
generators at the City of Downey
Emergency Shelter locations and
hardwire. Electrical work to modify
existing wiring & update lighting or
efficiency
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
1A, 5B 2024 Public Works, City of
Downey
Hazard Mitigation
Grant Program
(HMGP)
&
$500,000
Medium
New
Priority:
High
STAPLEE+E Prioritization Score:
40/40
8 Conduct a full-scale mass care and
shelter exercise
All Hazards
(Acts/Threats of Mass Violence, Civil Unrest, Cyber
Incident, Dam Failure, Drought, Earthquake,
Hazardous Materials Release, Pandemic, Severe
Weather/Storm, Tornado, Mass Transportation
Accident/Incident, Urban Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire Smoke/Air Quality)
1C, 2A, 2B,
4A,, 5B, 5C 2024
Office of Emergency
Management, Parks &
Recreation, Public
Works Department
Local General Funds
&
$500
Short
New
Priority:
Medium
STAPLEE+E Prioritization Score:
38/40
9 Conduct functional active shooter drill for
high-hazard areas/departments using a
vendor and invite local agencies to
participate.
Acts/Threats of Mass Violence 1A, 1B, 1C,
3A, 5A 2023 Kaiser Permanente
Safety Department
HPP Grant Funds
&
$11,500
Short
New
Conduct Stop the Bleed Training for staff and STB
kits next to AED kits
Benefits: Staff response/education
Anticipated Completion Date: 2024
Priority:
Medium
STAPLEE+E Prioritization Score:
35/40
10 Conduct active shooter training with the
Fire Department. Acts/Threats of Mass Violence 1A, 1B, 1C, 3A, 5A, 5B 2023 Police Department,
Fire Department
Homeland Security
Grant Program
(HSGP)
&
$15,000
Long
New
Priority:
High
STAPLEE+E Prioritization Score:
36/40
City of Downey Hazard Mitigation Plan 4-12
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
11 Encourage public transparency on
critical issues to minimize
misunderstanding and unrest within the
community
Civil Unrest 2B
2016,
updated
in 2018
and 2023
Police Department
Local General Fund:
Outreach budget
&
In Kind Matches
Long
Ongoing
This is an On-GOING activity. The Department
actively posts on social media, host townhall
meetings and Coffee with a Cop on Tuesday and
participate or host city-wide events (Touch- A-Truck,
National Night Out).
Priority:
High
STAPLEE+E Prioritization score:
39/40
12 Conduct a tabletop drill to focus on cyber
threat Cyber Incident 1C 2023
Kaiser Permanente
Safety Department,
Kaiser Regional
In Kind Matches
&
$25,000
Short
New
Priority:
High
STAPLEE+E Prioritization Score:
35/40
13 Conduct a cybersecurity PEN test which
involves a third party who tries to break
into the network and will provide a report
of the results after
Cyber Incident 1B, 1C 2024 Finance-IT Department
Local General Funds
&
$20,000
Short
New
Benefits: More than $500,000
Priority:
Medium
STAPLEE+E Prioritization Score:
40/40
14 Review partnerships and responsibilities
with the Army Corps of Engineers in
relation to the Whittier Narrows and
Garvey Reservoir dams to enhance
effective communications. Explore MOU
opportunities and validity.
Dam Failure 4B, 5C 2023 Office of Emergency
Management
Local General Fund
&
In Kind matches
Long
New
Priority:
High
STAPLEE+E Prioritization Score:
26/40
15 Extend recycled water main to Furman
Park to allow for retrofit of existing
landscape irrigation system to recycled
water thereby reducing demands on
potable water supplies.
Drought 1A, 1C, 3A, 5C
2022,
updated
in 2023
Public Works
Department, Utilities,
City of Downey, LA
County Flood Control
District
2022 Urban
Community Drought
Relief Grant and Water
Fund
&
$1,400,000
Short
New
Not only does this conserve water it also, helps
drought-proof the landscape irrigation system since
recycled water is exempt from water use reductions
during droughts
Benefits: Reduces reliance on potable water;
Drought-proof
Priority:
High
STAPLEE+E Prioritization Score:
39/40
City of Downey Hazard Mitigation Plan 4-13
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
16 Expand City initiative to upgrade public
property with drought tolerant
landscaping. Recreational areas,
building planters and street planters are
some examples of property locations
that might require updated landscaping
Drought 3A
2016,
updated
in 2018
and 2023
Public Works
Department, Utilities
Division
Water Fund
&
$50,000 - $10,000,000
Long
Ongoing
The City made a policy of replacing existing
landscaping with drought tolerant native
landscaping. Projects are performed along City
street right-of-way and at City facilities through
implementation of its Capital Improvement Program
as funding permits each fiscal year. The city
continues to upgrade facilities over the next decade
or so, it is possible that this upgrade could come to
an end at some point.
Priority:
Medium
STAPLEE+E Prioritization score:
33/40
17 Design and construction of Furman Park
stormwater capture and infiltration
project
Drought,
Urban Flood
1A, 1C, 2A,
3A,4A, 5A
2022,
updated
in 2023
Public Works
Department, Utilities,
LA County Flood
Control District
Regional & Municipal
City General Fund,
Safe Clean Water
(SCW) Program
Measure W
&
$20,000,000
Medium
New
Stormwater compliance; water
conservation/drought; retro to native landscaping.
Focuses on both wet weather and dry weather
flows; helps present runoff. CEQA and public
outreach required for project.
Benefits: Stormwater (MS4) Permit Compliance;
Flood/Run off control
Priority:
High
STAPLEE+E Prioritization Score:
37/40
18 Educating and promoting
implementation of stormwater measures
to developers and residents who are
constructing, improving, or residential,
commercial and/or industrial building
Drought, Severe Weather/Storm. Utility Loss 1A, 1B, 1C, 3A, 4A, 4B, 5A 2024 Public Works
Department
Stormwater Budget
&
$100,000
Long
New
Priority:
Medium
STAPLEE+E Prioritization Score:
30/40
19 Promote and continue to provide
education about earthquake
preparedness while in the hospital and
conduct annual drills for earthquake
Earthquake 1C, 2A, 4A, 5C 2023
Presbyterian
Intercommunity
Hospital (PIH)
In Kind Matches
&
$1,000
Medium
New
Anticipated Completion Date: 2026
Estimated Cost:
Priority:
Medium
STAPLEE+E Prioritization Score:
33/40
City of Downey Hazard Mitigation Plan 4-14
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
20 Perform ongoing assessments of
identified seismically vulnerable facilities
for inclusion among the list of prioritized
assessment locations by Fire
Department resources in the event of
significant seismic activity.
Earthquake 1B 2023 Fire Department
Local General Fund
&
In Kind Matches
Long
New
DFD Policy 2.14.1 and its appendices shall be
updated to reflect the prioritized list according to the relative potential for loss of life, disruption to critical infrastructure, and continuous capacity for effective
emergency response. Included in this list are
government buildings, transportation corridors,
utilities,
healthcare facilities, and high hazard occupancies.
Benefits: You cannot place a value on a life
Priority:
Medium
STAPLEE+E Prioritization Score:
40/40
21 Integrate new earthquake hazard
mapping data for the City of Downey and
improve technical analysis of earthquake
hazards
Earthquake 1B
2016,
updated
in 2023
Department of Public
Works – GIS Manager
National Earthquake
Hazards Reduction
Program (NEHRP)
State Assistance Grant
&
$30,000
Medium
Ongoing
Priority:
Medium
STAPLEE+E Prioritization score:
32/40
22 In collaboration with elected and
appointed officials within the City, to
increase capabilities within the
Hazardous Materials Division. Internal
and external resources will ensure that
regulatory compliance inspections are
conducted in accordance with state and
federal law, thus proactively addressing
conditions in the use, storage, and
transport of dangerous goods that could
be subject to accidental release.
Hazardous Material Release 5B
2016,
updated
in 2023
Fire Department, Los
Angeles County Health
Hazmat Division
Local General Fund
&
$85,000
Medium
Ongoing
An adoption of new fee schedule is expected at the
beginning of FY23-24.
Benefits Loss Avoidance: Reduction in or
elimination of accidental release of hazardous
materials from improper storage, transport, and/or
use of dangerous goods and wastes.
Priority:
Medium
STAPLEE+E Prioritization score:
34/40
23 Implement traffic control upgrades to
mitigate accidents in “trouble
intersections” (traffic signals, power, rail
controls)
Mass Transportation Accident/ Incident 1C
2016,
updated
in 2018
and 2023
Public Works
Department, Principal
Civil Engineer &
Maintenance and
Facilities
Hazard Mitigation
Grant Program
(HMGP)
&
$100,000 -
$10,000,000
Medium
Ongoing
Engineer has two locations they are reviewing
(Lakewood/Firestone and Lakewood/Imperial).
There are six intersections on Lakewood Boulevard
and are upgrading communication system with WIFI
antennas to improve timing
Benefits: Traffic congestion for 80,000 vehicles
City of Downey Hazard Mitigation Plan 4-15
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
Priority:
High
STAPLEE+E Prioritization score:
38/40
24 Implement buffering street improvement
projects to protect the public from the
impact of a traffic incident (sidewalks,
fences, drop off zones, and bridge rails)
Mass Transportation Accident/ Incident 1A
2016,
updated
in 2023
Public Works
Department, Principal
Civil Engineer,
Maintenance and
Facilities
Local General Fund
&
$100,000 -
$5,000,000
Long
Ongoing
Bike lanes were added, and schools have more
turnouts for drop-offs The City also has a Bike
Route Plan.
Anticipated Completion Date:
Priority:
High
STAPLEE+E Prioritization score:
38/40
25 Develop a Continuity of Government
Plan and encourage private industry to
develop continuity plans in order to
reduce the impact of service
interruptions and economic loss as the
result of a pandemic
Pandemic 1D
2016,
updated
in 2023
Office of Emergency
Management
Hazard Mitigation
Grant Program
(HMGP)
&
$50,000
Long
Ongoing
Priority:
Low
STAPLEE+E Prioritization score:
34/40
26 Propose a monetary set-up/ replacement
program for facility roofs and HVAC
systems
Severe Weather, Storm 1A, 3B 2024 Public Works,
Maintenance
Local General Fund
&
$300,000
Long
New
Benefit: Prevents storm related damage and
building climate control reliability
Anticipated completion date: 2038 (15-20 years)
Priority:
Medium
STAPLEE+E Prioritization Score:
30/40
27 Conduct PSA regarding tornados and
provide education and awareness media
materials via social media.
Tornado 2A 2024 Office of Emergency
Management
Local General Funds
&
$1,000
Short
New
Benefits: Life Safety
Priority:
Low
STAPLEE+E Prioritization Score:
34/40
28 Enhance and harden HVAC System at
Barbara J. Riley Community/Senior
Center
Severe Weather, Storm 1A, 5C 2023 Public Works, City of Downey
Local General Fund
&
$300,000
Short
New
The BJR Community/Senior Center is an identified
cooling center for the public.
Priority:
High
STAPLEE+E Prioritization Score:
40/40
City of Downey Hazard Mitigation Plan 4-16
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in
the risk assessment
Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status
29 Research best practices for tornado
sheltering that best match the school
campuses and district facilities. Review
structures in relation to current building
code standards to determine potential
hardening projects i.e. tornado sheltering
measures.
Tornado 1C, 2A, 5C 2024-25
Downey USD, DUSD
Emergency Operations
Team, City of Downey
Office Of Emergency
Management
&
$10,000,000
Short
New
Benefits: Reduce or eliminate injuries and the loss
of life
Priority
Medium
STAPLEE+E Prioritization Score:
30/40
30 Distribute information and education
materials that will help tie this to existing
drills already conducted regularly during
the school year
Tornado 1C, 2A, 5C 2024-25
Downey USD, DUSD
Emergency Operations
Team, City of Downey
Office Of Emergency
Management
&
$10,000,000
Short
New
Benefits: Reduce or eliminate injuries and the loss
of life
Priority
Medium
STAPLEE+E Prioritization Score:
30/40
31 Enhance mapping data to identify flood-
prone areas, due to standing water;
urban flooding; etc., throughout the city
and implement improvement projects to
enable efficient drainage within the
identified vulnerable locations.
Urban Flood 1B
2018,
updated
in 2023
Public Works
Department
Hazard Mitigation
Grant Program
(HMGP), Flood
Mitigation Assistance
(FMA), Building
Resilient Infrastructure
and Communities
(BRIC)
&
$2,000,000
Medium
Ongoing
A retention basin was created at the Dennis the
Menace Park to divert water back in 2017-18. A
similar project will be completed at Furman Park.
This is grant funded and is an on-going project.
Priority:
Medium
STAPLEE+E Prioritization score:
29/40
32 Enhance debris management strategies
for windstorm events Windstorm 5A
2016,
updated
in 2023
Public Works
Department
In Kind Matches
&
$30,000
Medium
Ongoing
The City of Downey has a dumpsite and equipment
for action. The Urban Forest Management Plan also
helps make the city more resilient to windstorms.
The task is ongoing.
Priority:
Medium
STAPLEE+E Prioritization score:
27/40
City of Downey Hazard Mitigation Plan 4-17
Table 4. 3: Completed, Deferred and Deleted Mitigation Strategies Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Establish a standing
emergency management
coalition that will keep hazard
mitigation a priority within the
City
All Hazards
(Acts/Threats of Mass Violence,
Civil Unrest, Cyber Incident, Dam
Failure, Drought, Earthquake,
Hazardous Materials Release,
Pandemic, Severe Weather/Storm,
Tornado, Mass Transportation
Accident/Incident, Urban Flood,
Utility Loss, Urban Fires, Windstorm
, Wildfire Smoke/Air Quality
5A 2016
Office of
Emergency
Management
Complete
The Downey Resiliency Group will meet
bi-monthly to prioritize hazard mitigation
for the city.
Develop public and private
partnerships to foster hazard
mitigation program coordination
and collaboration in the City
All Hazards
(Acts/Threats of Mass Violence,
Civil Unrest, Cyber Incident, Dam
Failure, Drought, Earthquake,
Hazardous Materials Release,
Pandemic, Severe Weather/Storm,
Tornado, Mass Transportation
Accident/Incident, Urban Flood,
Utility Loss, Urban Fires, Windstorm
, Wildfire Smoke/Air Quality
4B, 5B 2016
Office of
Emergency
Management
Complete
Increase City awareness of
how mitigation measures can
positively affect the City
environment and implement
mitigation projects accordingly
All Hazards
(Acts/Threats of Mass Violence,
Civil Unrest, Cyber Incident, Dam
Failure, Drought, Earthquake,
Hazardous Materials Release,
Pandemic, Severe Weather/Storm,
Tornado, Mass Transportation
Accident/Incident, Urban Flood,
Utility Loss, Urban Fires, Windstorm
, Wildfire Smoke/Air Quality
3B 2016
Office of
Emergency
Management,
Public Works
Department,
Community
Development
Deferred
City of Downey Hazard Mitigation Plan 4-18
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Work with City departments to
encourage the incorporation of
Hazard Mitigation Plan goals
into departmental operations
All Hazards
(Acts/Threats of Mass Violence,
Civil Unrest, Cyber Incident, Dam
Failure, Drought, Earthquake,
Hazardous Materials Release,
Pandemic, Severe Weather/Storm,
Tornado, Mass Transportation
Accident/Incident, Urban Flood,
Utility Loss, Urban Fires,
Windstorm, Wildfire Smoke/Air
Quality
1A 2016
Office of
Emergency
Management
Deleted
Develop and implement an
educational outreach campaign
to educate the public on
maintaining personal safety
during workplace incidents
Acts/Threats of Mass Violence 2B 2016
Office of
Emergency
Management,
Fire, Police
Department
Deferred
Action has been combined with another
action
Minimize earthquake damage
risk by initiating structural
integrity projects for critical
facilities
Earthquake 1A 2016 Public Works
Department
Complete
The 2019 and 2022 California Building
Code (CBC) supersedes the 2016
CBC.
Encourage seismic strength
evaluations of critical facilities
to identify vulnerabilities for
schools, public infrastructure,
and critical facilities
Earthquake 1B 2016
Department
of Public
Works – GIS
Manager
Deferred
Encourage the reduction of
nonstructural and structural
earthquake hazards in homes,
schools, businesses, and
government offices
Earthquake 1A 2016 Building
Safety
Deleted
The building codes have seismic
requirements and are adopted by the
city.
City of Downey Hazard Mitigation Plan 4-19
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Establish a framework to
compile and coordinate surface
water management plans and
data throughout the City
Urban Flood 1B 2016
Public Works
Department,
Utilities
Division
Complete
Downey along with other participating
cities and agencies located in these
watersheds have developed Watershed
Management Programs (WMPs) along
with Coordinated Integrated Monitoring
Programs (CIMPs) for each
watershed.
Develop programs to prevent
trees from threatening lives,
property, and public
infrastructure during windstorm
events
Windstorm 1A 2016 Public Works
Department
Complete
Downey will adopt the 2020 – 2021
Urban Forest Management Plan which
lays out the type of trees appropriate for
the location. It considers the
infrastructure of the area.
The city has updated the city’s Tree
Ordinance 2022, which outlines the
city’s policy on tree care. The trim
schedule will be every two years. The
task is completed.
Encourage overhead utilities to
use underground construction
methods where possible to
reduce power outages from
windstorms
Windstorm 5B 2016
Public Works
Department,
Engineering
Deleted
No funding available.
City of Downey Hazard Mitigation Plan 4-20
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Develop a Cal OES-approved
evacuation plan, coordinating
with the Army Corps of
Engineers, and make the plan
is publicly available
All Hazards
(Acts/Threats of Mass Violence,
Civil Unrest, Cyber Incident, Dam
Failure, Drought, Earthquake,
Hazardous Materials Release,
Pandemic, Severe Weather/Storm,
Tornado, Mass Transportation
Accident/Incident, Urban Flood,
Utility Loss, Urban Fires, Windstorm
, Wildfire Smoke/Air Quality)
5C 2016
Office of
Emergency
Management
Deleted
Grant monies originally awarded were
redirected to support another project.
Coordinate with County and
local public health
organizations to encourage
citywide education on the
benefits and availability of
vaccinations to improve public
health
Pandemic 2B 2016
Office of
Emergency
Management,
Fire
Department
Complete
Due to the Public Health Emergency,
COVID-19, a Medical Point of
Distribution (POD) plan was developed
to support mass vaccines
immunizations sites.
Hire additional staff to monitor
and coordinate fire prevention
ordinances with regard to
hazardous material
maintenance
Hazardous Material Release 1A 2016 Fire
Department
Complete
A part time fire inspector was hired in
2022 to address the action.
Organize and conduct
awareness training courses for
Police and Public Works
personnel
Hazardous Material Release 5 2016 Fire
Department
Deleted
The action never pursued, thus
removed. Not feasible with the number
of current staff.
Conduct assessments of City
buildings and implement facility
upgrades as appropriate to
reduce loss due to severe
storms
Severe Weather,
Storm 1A 2016 Public Works
Department Complete
City of Downey Hazard Mitigation Plan 4-21
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Expand City recycled water
infrastructure to enhance the
City’s capability to conserve
potable water supplies
Drought 3A 2016
Public Works
Department,
Utilities
Division
Complete
The City extended a recycled water
main north on Lakewood Boulevard
towards the north City limits. This
expansion allowed the landscaped
medians north of Gallatin Road and the
landscaping at Dennis the Menace Park
to be retrofitted to recycled water for
irrigation thereby reducing potable
water demands in the City. The City
also requires developments to provide
and use recycled water for landscape
irrigation and other non-potable water
needs. This resulted in the use of
recycled water at 8 additional
locations/developments for landscape
irrigation and dual plumbing purposes
further reducing demands on the City’s
potable water system
City of Downey Hazard Mitigation Plan 4-22
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Continue education campaigns
to encourage the public to
conserve water (Include State
and local rebates as well a rain
barrel availability)
Drought 2A 2016
Public Works
Department,
Utilities
Division
Complete
The City provided water conservation
information to its customers regarding
useful water conservation practices,
identifying leaks, and any updated
mandatory water use reductions and
restrictions. The City used various
means of distributing conservation
information depending on whether the
State was currently in a declared
drought and the time of year including
via social media, the Parks and
Recreation Guide “Discover Downey”
which included advertisements for
water conservation tips, and the City’s
website which includes rebate info, and
a link to the LA County Drought
Tolerant Landscaping Handbook.
Implement both current City
projects that capture storm-
water runoff in conjunction with
the open Municipal Storm
Water Permit issued by the
Department of Water
Resources for separate storm
sewer systems (MS4 permit)
Urban Flood, Drought 3A 2016
Public Works
Department,
Utilities
Division
Complete
The City is currently working on design
of several additional park stormwater
capture and infiltration projects and will
continue to pursue funds for
implementation of additional future
projects. The City constructed both a
stormwater capture and infiltration
facility at Dennis the Menace Park and
vegetated bioswale on the west side of
Lakewood Boulevard at the I-5
Freeway. Both of these facilities were
constructed to capture both wet and dry
weather runoff to help comply with the
city’s MS4 permit, to help conserve
local weather resources, as well as to
help alleviate flooding issues in the
area.
City of Downey Hazard Mitigation Plan 4-23
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Encourage cooperation with
third-party stakeholders to
promote effective emergency
response and to update
emergency plans as necessary
(Metro, TSA, Downey-link)
Mass Transportation
Accident/Incident 5B 2016
Fire
Department,
Police
Department
Deleted
The action was incorporated with
another action.
Update City commodity flow
studies to identify vulnerabilities
for HazMat release as a result
of commercial chemical
transport
Mass Transportation Accident/
Incident 1B 2016 Fire
Department
Complete
The Hazardous Materials Specialist
regularly monitors the presence,
tracking, and planning of hazardous
materials in our jurisdiction. Release
response planning is included in the
business plan for each monitored
location.
Conduct vulnerability
assessments for critical
infrastructure and key resource
(CIRK) facilities to identify
vulnerabilities in security
systems and implement
upgrades accordingly
Acts/Threats of Mass Violence 1A 2016 Fire
Department
Complete
For Fire Department-specific buildings,
assessments have been conducted by
Facilities Program manager. Funding
for security cameras has been
requested through the budget
process. Fire and life safety systems
have been implemented in all fire
stations as a part of recent facility
upgrades.
City of Downey Hazard Mitigation Plan 4-24
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Purchase Combat-Casualty kits
for each Fire and Police unit to
enhance emergency services
Acts/Threats of Mass Violence 5A 2016 Fire
Department
Complete
Combat casualty kits have been placed
on each police vehicle and fire
apparatus. Additionally, enhanced and
collaborative training has been
implemented between fire and police
departments to ensure appropriate and
efficient unified response to violent
incidents.
Revise City policies and
procedures that correspond
with escalating threat levels for
Fire and Police
Acts/Threats of Mass Violence 5C 2016
Office of
Emergency
Management,
Fire, Police
Department
Complete
Emergency Operations Plans (EOPs)
and Event Actions Plans (EAPs) are
updated routinely as emerging threats
arise and large-scale events occur.
Obtain alternative energy
sources for critical
infrastructure to maintain
continuity of government
Utility Loss 1C 2016 Public Works
Department
Complete
Solar panels have been purchased and
installed in the parking lot.
Coordinate with utility providers
to develop prioritization for
power restoration to City
facilities and assets in order to
maximize response efforts
Utility Loss 1C 2016 Public Works
Department Complete
Educate the public on personal
safety during an incident and
any available evacuation
avenues (Shelter in Place)
Civil Unrest 2B 2016
Police
Department,
Office of
Emergency
Management,
Public
Information
Officer
Complete
The Community Emergency Response
Team (CERT) training curriculum
includes State Implementation Plan
(SIP) guidance.
City of Downey Hazard Mitigation Plan 4-25
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department Status
Enhance emergency response
capabilities to promote public
safety and safety of first
responders during an incident
(training & resources,
communications)
Civil Unrest 5A 2016
Police
Department,
Fire
Department
Complete
Downey Alert training is ongoing to
notify staff in a timely manner.
Broaden coordination with Los
Angeles County Sherriff’s
Department and neighbor cities
to maximize effectiveness in
response and strengthen
coordination though joint
training
Civil Unrest 5B 2016 Police
Department
Complete
Conducted a training with Whittier
Police in 2018-2019 to enhance
coordination for civil unrest scenarios
with the Special Response Teams.
City of Downey Hazard Mitigation Plan 5-i
PLAN MAINTENANCE
Table of Contents
5.1 Mitigation Progress Monitoring ..................................................................... 2
5.2 Planning Mechanisms..................................................................................... 2
5.3 Plan Update ................................................................................................... 11
List of Tables
Table 5. 1: Regulatory Table ......................................................................................... 2 Table 5. 2: Administrative/Technical Tools Table ....................................................... 3 Table 5. 3: Fiscal Tools table ........................................................................................ 5 Table 5. 4: Grant Funding Tools ................................................................................... 5 Table 5. 5: Outreach and Partnership Tools ................................................................ 7 Table 5. 6: Action Item Implementation ..................................................................... 15
City of Downey Hazard Mitigation Plan 5-2
5.1 Mitigation Progress Monitoring
To ensure the Plan continues to provide an appropriate path for risk reduction throughout the City, it is necessary to regularly evaluate and update it. The Emergency Manager will be responsible for monitoring the status of the Plan and gathering appropriate parties to report on the status of mitigation actions. The Steering Committee will continue to be an active participant in the next plan update. As the Hazard Mitigation Plan matures, new stakeholders will be identified and encouraged to join the existing Steering Committee.
To thoroughly track hazard mitigation status, the City of Downey (City) must continuously monitor and document the progress of the implementation of mitigation actions. Though mitigation actions may be delegated to different departments within the City, the Emergency Manager will have the responsibility of monitoring overall progress.
To facilitate this monitoring process, Table 5.6: Action Item Implementation (located at the end of this Chapter) was developed to provide a mechanism for monitoring the overall implementation progress. The table is designed to monitor mitigation actions according to project managers, project status, and project milestones.
5.2 Planning Mechanisms
5.2.1 Process to Incorporate the Mitigation Strategy into Other Planning Mechanisms
Hazard mitigation practices must be incorporated within existing plans, projects, and programs. Therefore, the involvement of all departments, private non-profits, private industry, and appropriate jurisdictions is necessary to find mitigation opportunities within existing or planned projects and programs. The City’s 2018 HMP faced challenges in its integration with other planning frameworks due to the unexpected emergence of the global pandemic in 2020. This unforeseen crisis disrupted the normal course of planning activities, causing delays and setbacks in the implementation of the 2018 plan. As a result, the City's efforts to synchronize various planning mechanisms were hindered, leading to a disjointed approach in addressing pressing mitigation action issues. The pandemic's impact on resources, priorities, and decision-making processes further complicated attempts to harmonize planning efforts across different sectors. Despite these obstacles, the City continued to adapt and refine its strategies to navigate the complexities introduced by the pandemic and to foster more cohesive planning practices moving forward.
City of Downey Hazard Mitigation Plan 5-3
The City maintains the following processes to incorporate mitigation strategies of the HMP into its planning mechanisms. The following resources were identified by the Steering Committee as being most inherent to City operations and most likely to be avenues for the first steps in hazard mitigation implementation. A full list of identified resources can be found in Tables 5.1 through 5.5 later in this section.
Website
The City’s HMP will be posted on the city website to enable citizens to review and provide feedback regarding mitigation objectives and strategies. Feedback from residents can be incorporated during the annual review or five-year update of the HMP. In addition, the website can be used as a vehicle to maintain an ongoing conversation with the public regarding upcoming mitigation projects and provide an avenue for hazard education.
Additionally, social media is being leveraged to expand communication awareness and education for an all-hazards approach.
City of Downey City Council
The City Council is responsible for approving projects, plans, and programs on a citywide level. By providing mitigation planning concepts to the City Council, mitigation actions and projects will be incorporated into relevant planning efforts. The Emergency Management Department can work with Council Members to encourage the inclusion of mitigation goals and objectives for any project or planning efforts which are reviewed by the council.
Committees and Commissions
To assist the City Council in reviewing prominent issues, the City has established eleven committees and commissions listed below.
• Emergency Preparedness
• Green Task Force
• Handicap
• Library Advisory
• Personnel Advisory
• Planning
• Public Facilities Corporation
• Public Works Committee
• Recreation and Community
Services
• Water Facilities
• Youth Commission
City of Downey Hazard Mitigation Plan 5-1
As necessary, each specialized commission can review and implement hazard mitigation activities that affect its goals and objectives. Additionally, each commission can educate and assist the community with relevant safety issues and coordinate local gatherings.
Each of these groups can help raise awareness about hazardous events that can affect the City, educate the public about the actions the City is taking to reduce loss, and supply avenues for the community to provide feedback.
Community Development Department
The Planning Division of The City’s Community Development Department works closely with the Planning Commission to ensure that development within the City is consistent with the General Plan goals and policies, as well as in the best interests of the City. This includes development of land use, general planning, zoning requirements, and residential projects. Mitigation measures can be incorporated into potential projects.
The Building and Safety Division (the Division) of the City’s Community Development Department is responsible for reviewing construction plans and various building inspection activities. The objective of the Division is to protect the public in regard to building design and construction. Hazard mitigation activities that get incorporated into building codes will be enforced by the Division.
Resource Table
This section serves as a high-level capability assessment of the City’s resources through which hazard mitigation objectives may be achieved. The following subsections attempt to document the Regulatory, Administrative/Technical, Fiscal, Grant funding, and Outreach/Partnership resources available to the City. The city has the full capability and authority to expand upon its capabilities.
City of Downey Hazard Mitigation Plan 5-2
Planning and Regulatory Capabilities and Resources
Table 5. 1: Planning and Regulatory
Regulatory Resource Updated Comments
2030 Downey Forward Strategic
Plan
2024 The Downey Strategic Plan serves as a tool to ensure that City initiatives, strategies, and projects are developed to meet Council priorities, and that the overall City government is accountable in meeting community needs.
Downey’s “General Plan Vision
2025” (Building Codes, Land Use,
Planning regulations,
Development Ordinances)
2023 Plan outlines how the City is organized with regards to area such as land use, safety, different conservation efforts, and economic resilience and develop.
Downey Building Code 2022 California Building Code 1 is based upon the 2021 International Building Code and has been adopted by the City and established as the “Downey Building Code.
Downey Green Building
Standards Code 2
2022 Article 8, Building Standards Code.
International Building Code 3
(IBC).
2021 State adopts the 2021 IBC. State strengthens seismic resilience in IBC § 1613.2.5 by setting Seismic Design Category D as the mandatory minimum category for structures under the jurisdiction of the Office of Statewide Health Planning and Development (OSHPD) and by prohibiting the alternative Seismic Design Category determination of § 1613.2.5.1 and the simplified design procedure of § 1613.2.5.2 for structures under the jurisdiction of the Division of the State Architect—Structural Safety and those under the jurisdiction of OSHPD.
International Residential Code 4
(IRC)
2021 State adopts the 2021 IRC. Note that state does not adopt R322.1.9 (containing flood design specifications for manufactured homes) nor R327.1 (requiring, via application of the International Swimming Pool and Spa Code, swimming pools in coastal high-hazard areas to conform to ASCE 24).
1 California Code of Regulations. (2022) Title 24, Part 2. Retrieved from https://www.dgs.ca.gov/BSC/Codes 2 Ibid.
3 FEMA Fact Sheet. (2024) 2024 Building Code Adoption Tracking: FEMA Region 9. Retrieved from https://www.fema.gov/sites/default/files/documents/fema_fy24-bcat-region-9-report.pdf 4 Ibid.
City of Downey Hazard Mitigation Plan 5-3
Regulatory Resource Updated Comments
City Ordinance No. 925 Water
Conservation Regulations
1991 Ordinance outlines legality and framework for imposing water use restrictions and fines in times of water shortage
Urban Water Management Plan 2015 Plan outlines forecasts for drought probability and magnitude while expanding upon awareness of drought hazard vulnerability.
Security Vulnerability Assessment 2016 Plan outlines potential vulnerabilities for security breaches and makes recommendations for improvement in order to mitigate potential adversarial events.
Opportunity to Expand and Improve Planning and Regulatory Capabilities
• Adherence to building codes, including local codes, regulates growth and controls land use patterns. As codes are updated, consider emerging threats/hazards and future probability and impacts exacerbated by climate change to ensure lowered risk and fewer losses.
• The Hazard Mitigation Plan will be incorporated in the General Plan Safety Element, and specifically the Goals, Policies and Programs section related to each hazard to ensure greater alignment between the two plans.
Administrative and Technical Capabilities and Resources Table 5. 2: Administrative and Technical
Administrative/Technical
Resource Description and Role in Supporting Mitigation
Emergency Management Division Emergency Manager is responsible for emergency preparedness and hazard mitigation planning. This is the department ultimately responsible for promoting implementation of hazard mitigation objectives.
Fire Department The Fire Department is the seat of the emergency management division and will oversee its accomplishments. In addition, the Department has the authority to inspect facilities storing hazardous materials for proper storage, host public education campaigns, and inspect building structures.
Police Department The Police Department is able to support public outreach and may assist in identifying areas of improvement for resistance to civil unrest and adversarial events.
City of Downey Hazard Mitigation Plan 5-4
Administrative/Technical
Resource Description and Role in Supporting Mitigation
City Council City Council can review and approve mitigation propositions for implementation.
Emergency Preparedness
Commissions
The sole purpose of this commission is to keep hazard mitigation a priority. Through this group, all facets of the City will be encouraged to consider and mitigate potential vulnerability to hazards.
Green Task Force This commission seeks to foster environmental awareness and as such can promote environmentally sustaining mitigation activities.
Handicap Committee This committee seeks to ensure the disabled population is considered in public planning and projects.
Planning Commission This commission reviews planning documents for the City and will help promote considerations for hazard mitigation in future planning documents.
Community Development
Department
The Community Development Department is response for all developments within the City. This department will be able to include considerations for local hazards in new projects.
Public Works and GIS The Public Works Department is responsible for street improvements and overall City maintenance. This department can implement hazard mitigation activities as part of planned maintenance and City upgrades.
GIS provides spatial analysis and maps for the City.
Administration Administration is a multi-faceted resource. The City may utilize experts in its many departments to identify priority mitigation strategies, apply for funding, and implement mitigation projects.
Opportunity to Expand and Improve Administrative and Technical Capabilities
• Provide opportunities for continued education to Community Development staff to maintain state-of-the-art knowledge of new code and regulatory requirements that will mitigate hazard risk and ensure greater resilience. • The HMP and Green Task Force initiative should be closely aligned. The Green Task Force may consider mitigation measures that support sustainability and greater resilience to climate induced hazards. • Conduct training for GIS technicians on hazard-specific spatial analysis to better determine vulnerability and impacts to the City’s key assets. Continue to improve the public-facing GIS platform ( https://downeypw.org/xymaps/Map/Map) to articulate risk to residents, businesses and key stakeholders.
City of Downey Hazard Mitigation Plan 5-5
Fiscal Capabilities and Resources
Table 5. 3: Fiscal
Fiscal Resource Available for Use
General Fund Yes, with approval
Capital Improvement Plan Yes
Water Fund Yes,
Authority to impose taxes for specific purposes Yes, with voter approval Table 5. 4: Grants
Grant Funding Resource Agency Purpose
Pre-Disaster Mitigation Program
(PDM)
U.S. Department of Homeland
Security, Federal Emergency
Management Agency
To provide funding for States, and communities for cost-effective hazard mitigation activities which complement a comprehensive hazard mitigation program and reduce injuries, loss of life, and damage and deconstruction of property.
Hazard Mitigation Grant Program
(HMGP)
U.S. Department of Homeland
Security, Federal Emergency
Management Agency
To prevent future losses of lives property due to disasters; to implement State of local hazard mitigation plans; to enable mitigation measures to be implemented during immediate recovery from a disaster; and to provide funding for previously identified mitigation measures to benefit the disaster area.
Flood Mitigation Assistance
(FMA)
U.S. Department of Homeland
Security, Federal Emergency
Management Agency
To help States and communities plan and carry out activities designed to reduce the risk of flood damage to structures insurable under the NFIP.
Emergency Management
Performance Grants (EMPG)
U. S. Department of Homeland
Security; Federal Emergency
Management Agency
To encourage the development of comprehensive emergency management at the State and local level and to improve emergency management planning, preparedness, mitigation, response and recovery capabilities.
City of Downey Hazard Mitigation Plan 5-6
Grant Funding Resource Agency Purpose
Community Development Grant
Program (CDBG)
U.S. Department of Housing and
Urban Development
To develop viable urban communities by providing decent housing and a suitable living environment. Principally for low-to-moderate income individuals.
Public Assistance Program (PA) U.S. Department of Homeland Security, Federal Emergency
Management Agency
To provide supplemental assistance to States, local governments, and certain private nonprofit organizations to alleviate suffering and hardship resulting from major disasters or emergencies declared by the President. Under Section 406, Public Assistance funds may be used to mitigate the impact of future disasters.
Emergency Watershed Protection U.S. Department of Agriculture, Natural Resource Conservation
Service
To provide emergency technical and financial assistance to install or repair structures that reduce runoff and prevent soil erosion to safeguard life and property.
Disaster Mitigation and Technical
Assistance Grants
U.S. Department of Commerce,
Economic Development
Administration
To help States and localities to develop and /or implement a variety of disaster mitigation strategies.
Watershed Surveys and Planning U.S. Department of Agriculture, Natural Resource Conservation
Service
To provide planning assistance to Federal, State, and local agencies for the development of coordination water and related land resources programs in watersheds and river basins
National Earthquake Hazards
Reduction Program (NEHRP)
U.S. Department of Homeland
Security, Federal Emergency
Management Agency
To mitigate earthquake losses that can occur in many parts of the nation providing earth science data and assessments essential for warning of imminent damaging earthquakes, land-use planning, engineering design, and emergency preparedness decisions.
Engineering for Natural Hazards National Science Foundation Supports fundamental research that advances knowledge for understanding and mitigating the impact of natural hazards on constructed civil infrastructure
Opportunity to Expand and Improve Fiscal Capabilities
• Hazard mitigation projects may be considered during the annual budgeting process for funding from the general fund.
Consideration for priority mitigation projects and the cost match needed for BRIC, HMGP, and FMA may be considered.
City of Downey Hazard Mitigation Plan 5-7
• Where applicable, CDBG grants should be used to fund mitigation projects that enhance the resiliency of low-income and underserved areas of the City of Downey.
• Train staff on notice of intent (NOI) procedures and track opportunities on the Cal OES mitigation website to initiate applications for grant funding.
Education, Outreach and Partnership Capabilities and Resources Table 5. 5: Education, Outreach and Partnership Capabilities Outreach/Partnership
Resource Description and Role in Supporting Mitigation
City Website The City website is an open forum for providing hazard information and for accepting ongoing comments from the public. The City website will likely be the main avenue for maintaining an open dialogue with the public for hazard mitigation throughout the planning period.
Public Outreach The City holds several training opportunities throughout the year. Public safety training will be able to be expended to include hazard-specific information to improve hazard awareness. Community engagement opportunities include the annual ShakeOut drill to practice how to be safe during an earthquake while also reviewing and updating emergency preparedness plans and supplies, Touch-A-Truck and routine certified emergency response team (CERT) trainings.
Mutual Aid Agreements As part of expanding its resilience to the impacts of hazard events, the City intends to review its current mutual aid agreements, identify gaps, and secure new agreements to expand its available mutual resources.
Social Media The City leverages many social media platforms (Instagram, Facebook 5) to interact and communicate with the general public regarding any and all hazards information. It continues to be a great tool to engage people through more creative and interactive ways to generate actionable knowledge.
Community Emergency Response
Team
The CERT Program is a 20-hour, all-hazard training offered by the City. This valuable course is designed to help citizens protect themselves, their family, their neighbors, and their neighborhood in an emergency.
Opportunity to Expand and Improve Education, Outreach and Partnership Capabilities
5 City of Downey Government. (n.d.) Facebook. Retrieved from https://www.facebook.com/cityofdowney/
City of Downey Hazard Mitigation Plan 5-8
• Strengthen ties with residents, community organizations and businesses to ensure key content and information is timely and relevant. Create additional communications platforms to ensure information and content reaches community members, such as the Downey Discussion platform ( https://www.downeyca.org/our-city/downey-discussion) . • Ensure the outreach and education of the City’s most vulnerable populations are prioritized. Integrate the mitigation actions and strategies into overall programming for first responders, parks, road maintenance, and youth and senior programs. • Enhance the Emergency Preparedness webpage ( https://www.downeyca.org/our-city/departments/emergency-preparedness) to maintain the HMP for public viewing and feedback. Provide updates on the annual progress of the mitigation action plan. • Develop a comprehensive program to utilize social media to reach out to communities in the City to provide information on mitigation activities. Conduct an annual survey to solicit input as part of the continuing public participation initiative. Provide information and conduct the survey in English and Spanish.
City of Downey Hazard Mitigation Plan 5-9
Implement the Substantial Improvement/Substantial Damage Provisions Damage Estimates are a part of the National Flood Insurance Program (NFIP). If a community participates in the NFIP, part of the responsibility of the local participating community is to perform damage estimates. These estimates are performed using a FEMA Substantial Damage Estimate (SDE) software program. This program is used to assist local communities in determining damage estimates as it relates to the NFIP. The City is tasked with the training and deployment of the SDE program. Local building officials/Stormwater management and floodplain manager are responsible for ensuring that the substantial improvement/substantial damage provisions are implemented following a flood related event within their respective jurisdiction. The local officials will ensure that all NFIP criteria/requirements are implemented and met following a flood event, local officials will work with FEMA to ensure proper documentation/designations are made and properly recorded for structures deemed substantially damaged during an event. For specific information, see the City’s standard floodplain ordinance in Chapter 8 of the Downey California municipal code 6. For the City of Downey, “Substantial damage" is defined as damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50% of the reasonable replacement value of the structure at the time of its damage based on its assessed valuation. A building or grading permit shall be obtained before new construction or development or substantial improvement begins within any area of special flood hazards, established in Section 8700.05.
Progress for Mitigation Incorporation
The current update is the result of the City’s continued dedication to having a FEMA- approved plan. In obtaining FEMA approval and formally adopting the Plan update, the City will take its continued steps to forge a culture which includes considerations for hazard mitigation throughout the City’s many facets.
5.2.2 Available Planning Mechanisms to Incorporate Mitigation Requirements The City uses the following local planning mechanisms for incorporating the mitigation requirements of the HMP.
6 Downey California municipal code. (2022). Chapter 8 Floodplain ordinance. Retrieved from 8 https://library.qcode.us/lib/downey_ca/pub/municipal_code/item/article_viii-chapter_8
City of Downey Hazard Mitigation Plan 5-10
General Planning
The City is responsible for updating and incorporating mitigation actions and concepts in the General Plan Vision 2025 (Plan). The Plan is evaluated on a periodic basis, which includes a review of the policies and programs associated with land use and development, among other things. Mitigation actions from the HMP will be reviewed during the next scheduled update of the Plan and incorporated as applicable. As part of this review, ordinances and codes will be reviewed to ensure they are consistent with the mitigation strategies and referred to the appropriate regulatory authority as needed.
Urban Water Management Plan
The City is responsible for updating and incorporating mitigation actions and concepts into the City’s Urban Water Management Plan (UWMP). The UWMP is updated every five years, which includes a review of the policies and programs associated with providing adequate water supplies to meet demands under a range of water supply conditions.
Mitigation actions from the HMP will be reviewed during the next scheduled update of the plan and incorporated as applicable. As part of this review, ordinances and codes will be reviewed to ensure they are consistent with the mitigation strategies and referred to the appropriate regulatory authority as needed. The UWMP was updated in 2020, with its next revision scheduled in the near future.
Emergency Operations Plan
The City maintains an Emergency Operations Plan (EOP) that includes profiles and specific responses for earthquakes, hazardous materials incidents, flooding and several other hazards mentioned in the HMP. The City will incorporate the Risk Assessment into the EOP in addition to using emergency scenarios outlined in the report to address potential mitigation actions.
Capital Improvements Program
The City maintains a Capital Improvements Program (CIP) with projects that are budgeted for at least a five-year period. Engineering mitigation projects are included within the CIP.
Additionally, the projects already included within the CIP are reviewed for mitigation improvements (e.g., areas prone to flooding are configured with mitigation elements, current seismic design criteria is applied to construction, facility locations are reviewed for special hazards, etc.).
City of Downey Hazard Mitigation Plan 5-11
5.3 Plan Update
Mitigation planning is an ongoing process, and as such, the HMP should be treated as a living document that must grow and adapt in order to keep pace with changes within the City. The Steering Committee, led by the City’s Office of Emergency Management is responsible for ensuring the HMP is updated every five years. An annual assessment will be completed to document any changes in site hazards (e.g., updated FIRM maps, contemporary seismic studies, etc.) or the installation and purchase of new equipment (e.g., back-up generators, emergency response equipment, etc.) to ensure they do not have any major effects on City’s hazard vulnerabilities that would impact the conclusions or actions associated with the HMP.
Prior to the fifth year of the revision cycle, these annual observations will be reviewed to determine what changes should be implemented in the required HMP Update. The results of the annual evaluations will be folded back into each phase of the planning process and should yield decisions on how to update each section of the Plan. The Emergency Manager has the responsibility of implementing these annual and five-year requirements.
During the annual review, if any updates are deemed minor, then the Emergency Manager or designee will perform the updates. However, if more major updates are required, then the Steering Committee will be reconvened to discuss the effects on the Plan. For the fifth- year revision, the entire Steering Committee will reconvene in order to use their expertise to update the Plan in its entirety.
In addition to these periodic requirements, any significant modification to the City’s facilities should be considered with respect to a possible impact on the HMP. All Steering Committee members are responsible for providing updates for the Plan to the Emergency Manager as necessary. As noted in the following section, the completed HMP will be available on the City’s website to allow the public to continue to be involved during these periodic reviews.
The Plan will be reviewed on an annual basis by the City’s Office of Emergency Management. It will be reviewed and revised every five years by the Steering Committee to determine the effectiveness of programs and to reflect changes that may affect mitigation priorities. The Emergency Manager will be responsible for contacting the Steering Committee members and organizing the review. Committee members will be responsible for monitoring and evaluating the progress of the mitigation strategies in the Plan. The Steering Committee will review the goals and action items to determine their
City of Downey Hazard Mitigation Plan 5-12
relevance to changing situations in the City, as well as changes in federal policy, and to ensure they are addressing current and expected conditions. The Steering Committee will also review the risk assessment portion of the Plan to determine if this information should be updated or modified, given any new available data. The City departments and organizations responsible for the various action strategies will report on the status of the projects, the success of various implementation processes, difficulties encountered, success of coordination efforts, and which strategies should be revised or removed, on an annual basis. The table delineated below as Table 5.8 will serve as a tool to monitor the yearly progress of implementing action items.
The City’s Office of Emergency Management will be responsible for ensuring the Plan is updated. The Emergency Manager and the Steering Committee will also notify all affected stakeholders when changes have been made. The updated Plan will be submitted to the California Governor's Office of Emergency Services (Cal OES) and to the Federal Emergency Management Agency (FEMA) for review and approval.
5.3.1 Continued Public Involvement
To facilitate ongoing public input, the following activities will be conducted.
The Steering Committee, led by the Emergency Manager, will look for opportunities to raise community awareness about the 2024 HMP and the hazards that affect the City.
This effort will include attendance and provision of materials at City-sponsored events and social media posts (such as Facebook, X, and NextDoor). Any public comments received regarding the HMP will be collected by the Emergency Manager, addressed as needed, and considered during future HMP updates.
The City will circulate a Hazard Mitigation Questionnaire annually every fall to engage the public and gather data about the City's priorities resilience, hazards of concern, and what mitigation activities should be prioritized. The Hazard Mitigation Questionnaire will be circulated via City Council meetings, shared with key community organizations, and social media. A flyer and hard copies of the questionnaire will also be available to community organizations to ensure underserved and underrepresented population groups have an opportunity to participate. The Hazard Mitigation Questionnaire will be available in both English and Spanish.
The City will hold an annual townhall meeting or equivalent meeting to engage the public and provide them with an opportunity to inform the Emergency Manager and Steering
City of Downey Hazard Mitigation Plan 5-13
Committee about hazards of concern and mitigation priorities. The townhall meeting will be advertised via City Council meetings, invitations to community organizations, and social media. An invitation to the annual townhall meeting will be posted at city-owned facilities.
Table 5. 6: Key Community Organizations to Assist with Continued Public Outreach
Community
Organization Target Audience
Arc of Los Angeles &
Orange Counties
Individuals with intellectual and developmental disabilities Assistance League of
Downey
Underserved and socioeconomically disadvantaged residents Clergy Council Churches and their members
Downey Chamber of
Commerce
Business community
Downey Coordinating
Council
General public and civic organizations. The Downey Coordinating Council is a monthly gathering of representatives from various civic and service organizations who meet to share information about their events and activities of interest to the public. Its membership reflects a broad range of organizations and volunteers.
Downey Food Helps Underserved and underrepresented residents Gangs Out of
Downey (G.O.O.D.)
Underserved and underrepresented youth
PTA HELPS Underserved families whose children attend Downy schools The Whole Child Vulnerable and underserved children. The Whole Child strives to improve the lives of more than 8,000 individuals each year through mental health, family housing, parent enrichment and nutrition services.
TLC Family Resource
Center
Underserved and vulnerable students and their families in the Downey Unified School District.
Table 5. 7: HMP Continued Public Outreach Tools
Outreach Tool Purpose and Implementation
City Website The City website will be utilized to maintain a publicly available copy of the Hazard Mitigation Plan. The
website will also host the Annual Hazard Mitigation
Questionnaire, and be used to publicize the annual
townhall meeting.
Training and Education Events The City holds several training opportunities throughout the year. Education and training events will be leveraged to discuss hazards and educate residents on how they
implement mitigation strategies in their own households. will be able to be expanded to include hazard-specific
information to improve hazard awareness. Touch-A-
Truck and routine Community Emergency Response
Team (CERT) trainings will also be utilized to educate
and solicit feedback on the hazards and mitigation
opportunities identified in the plan.
City of Downey Hazard Mitigation Plan 5-14
Social Media The City leverages social media platforms (Facebook and Instagram) to interact and communicate with the
general public regarding any and all hazard information.
These social media platforms will be utilized to invite residents to participate in the Annual Hazard Mitigation Questionnaire and annual townhall meeting. Other
events, such as Touch-A-Truck, will also be advertised.
City of Downey Hazard Mitigation Plan 5-
15 Table 5. 8: Action Item Implementation
Action
Number
Mitigation Action
a measure, project, plan or activity proposed to reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
1 Identify and pursue funding
opportunities, in addition to the
FEMA grant programs, to
develop and implement local
mitigation activities
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
1C
2016,
updated
in 2023
Office of
Emergency
Management,
Community
Development
Hazard Mitigation
Grant Program
(HMGP)
&
In Kind Matches
Long
2 Identify, implement, and
promote new collaborative
programs and outreach focusing
on residents, city departments,
and industry stakeholders to
promote active emergency
preparedness activities that
reduce hazards.
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
2A, 4A
2016,
updated
in 2023
Office of
Emergency
Management
In Kind Matches
&
$50,000
Long
3 Provide or facilitate/participate
business continuity workshops
for business owners to learn the
importance of disaster mitigation
and how to create an
Emergency Operations Plan for
their business
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
1D
2016,
updated
in 2023
Office of
Emergency
Management
Local General Fund
&
$1,000
Long
City of Downey Hazard Mitigation Plan 5-
16 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
4 Increase public awareness of
severe weather mitigation
activities to include shelter in
place and air quality warnings
and appropriate actions taken.
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
2B
2016,
updated
in 2023
Office of
Emergency
Management
Local General Fund
&
35,000
Medium
5 Coordinate with the Army Corp
of Engineers and nearby cities
for evacuation planning.
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
5C 2023
Office of
Emergency
Management
Local General Fund
&
In Kind Matches
Medium
6 Develop and implement a public
outreach campaign to increase
awareness of the Downey Alerts
System and encourage resident
opt-in for notifications
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
5B
2016,
updated
in 2023
Office of
Emergency
Management
Hazard Mitigation
Grant Program
(HMGP)
&
$35,000
Long
City of Downey Hazard Mitigation Plan 5-
17 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
7 Identify locations and install
emergency generators at the
City of Downey Emergency
Shelter locations and hardwire.
Electrical work to modify existing
wiring & update lighting or
efficiency
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
1A, 5B 2024
Public Works,
City of
Downey
Hazard Mitigation
Grant Program
(HMGP)
&
$500,000
Medium
8 Conduct a full-scale mass care
and shelter exercise
All Hazards
(Acts/Threats of Mass
Violence, Civil Unrest,
Cyber Incident, Dam
Failure, Drought,
Earthquake, Hazardous
Materials Release,
Pandemic, Severe
Weather/Storm, Tornado,
Mass Transportation
Accident/Incident, Urban
Flood, Utility Loss, Urban
Fires, Windstorm, Wildfire
Smoke/Air Quality)
1C, 2A, 2B, 4A,,
5B, 5C 2024
Office of
Emergency
Management,
Parks &
Recreation,
Public Works
Department
Local General Funds
&
$500
Short
9 Conduct functional active
shooter drill for high-hazard
areas/departments using a
vendor and invite local agencies
to participate.
Acts/Threats of Mass
Violence
1A, 1B, 1C, 3A,
5A 2023
Kaiser
Permanente
Safety
Department
HPP Grant Funds
&
$11,500
Short
10 Conduct active shooter training
with the Fire Department.
Acts/Threats of Mass
Violence
1A, 1B, 1C, 3A,
5A, 5B 2023
Police
Department,
Fire
Department
Homeland Security
Grant Program
(HSGP)
&
$15,000
Long
11 Encourage public transparency
on critical issues to minimize
misunderstanding and unrest
within the community
Civil Unrest 2B
2016,
updated
in 2023
Police
Department
Local General Fund:
Outreach budget
&
In Kind Matches
Long
City of Downey Hazard Mitigation Plan 5-
18 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
12 Conduct a tabletop drill to focus
on cyber threat Cyber Incident 1C 2023
Kaiser
Permanente
Safety
Department,
Kaiser
Regional
In Kind Matches
&
$25,000
Short
13 Conduct a cybersecurity PEN
test which involves a third party
who tries to break into the
network and will provide a report
of the results after
Cyber Incident 1B, 1C 2024 Finance-IT
Department
Local General Fund
&
$20,000
Short
14 Review partnerships and
responsibilities with the Army
Corps of Engineers in relation to
the Whittier Narrows and Garvey
Reservoir dams to enhance
effective communications.
Explore MOU opportunities and
validity.
Dam Failure 4B, 5C 2023
Office of
Emergency
Management
Local General Fund
&
In Kind Matches
Long
15 Extend recycled water main to
Furman Park to allow for retrofit
of existing landscape irrigation
system to recycled water
thereby reducing demands on
potable water supplies.
Drought 1A, 1C, 3A, 5C 2022
Public Works
Department,
Utilities, City
of Downey,
LA County
Flood Control
District
2022 Urban
Community Drought
Relief Grant and Water
Fund
&
$1,400,000
Short
16 Expand City initiative to upgrade
public property with drought
tolerant landscaping.
Recreational areas, building
planters and street planters are
some examples of property
locations that might require
updated landscaping
Drought 3A
2016,
updated
in 2023
Public Works
Department,
Utilities
Division
Water Fund
&
$50,000 - $10,000,000
Long
City of Downey Hazard Mitigation Plan 5-
19 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
17 Design and construction of
Furman Park stormwater
capture and infiltration project
Drought,
Urban Flood
1A, 1C, 2A,
3A,4A, 5A 2022
Public Works
Department,
Utilities,
LA County
Flood Control
District
Regional & Municipal
City General Fund,
Safe Clean Water
(SCW) Program
Measure W
&
$20,000,000
Medium
18 Educating and promoting
implementation of stormwater
measures to developers and
residents who are constructing,
improving, or residential,
commercial and/or industrial
building
Drought, Severe
Weather/Storm. Utility Loss
1A, 1B, 1C, 3A,
4A, 4B, 5A 2024 Public Works
Department
Stormwater Budget
&
$100,000
Long
19 Promote and continue to provide
education about earthquake
preparedness while in the
hospital and conduct annual
drills for earthquake
Earthquake 1C, 2A, 4A, 5C 2023
Presbyterian
Intercommunit
y Hospital
(PIH)
In Kind Matches
&
$1,000
Medium
20 Perform ongoing assessments
of identified seismically
vulnerable facilities for inclusion
among
the list of prioritized assessment
locations by Fire Department
resources in the event of
significant seismic
activity.
Earthquake 1B 2023 Fire
Department
Local General Fund
&
In Kind Matches
Long
City of Downey Hazard Mitigation Plan 5-
20 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
21 Integrate new earthquake
hazard mapping data for the City
of Downey and improve
technical analysis of earthquake
hazards
Earthquake 1B
2016,
updated
in 2023
Department of
Public Works
– GIS
Manager
National Earthquake
Hazards Reduction
Program (NEHRP)
State Assistance Grant
&
$30,000
Medium
22 In collaboration with elected and
appointed officials within the
City, to increase capabilities
within the Hazardous Materials
Division. Internal and external
resources will ensure that
regulatory compliance
inspections are conducted in
accordance with state and
federal law, thus proactively
addressing conditions in the
use, storage, and transport of
dangerous goods that could be
subject to accidental release.
Hazardous Material
Release 5B
2016,
updated
in 2023
Fire
Department,
Los Angeles
County Health
Hazmat
Division
Local General Fund
&
$85,000
Medium
23 Implement traffic control
upgrades to mitigate accidents
in “trouble intersections” (traffic
signals, power, rail controls)
Mass Transportation
Accident/ Incident 1C
2016,
updated
in 2023
Public Works
Department,
Principal Civil
Engineer &
Maintenance
and Facilities
Hazard Mitigation
Grant Program
(HMGP)
&
$100,000 -
$10,000,000
Medium
City of Downey Hazard Mitigation Plan 5-
21 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
24 Implement buffering street
improvement projects to protect
the public from the impact of a
traffic incident (sidewalks,
fences, drop off zones, and
bridge rails)
Mass Transportation
Accident/ Incident 1A
2016,
updated
in 2023
Public Works
Department,
Principal Civil
Engineer,
Maintenance
and Facilities
Local General Fund
&
$100,000 -
$5,000,000
Long
25 Develop a Continuity of
Government Plan and
encourage private industry to
develop continuity plans in order
to reduce the impact of service
interruptions and economic loss
as the result of a pandemic
Pandemic 1D
2016,
updated
in 2023
Office of
Emergency
Management
Hazard Mitigation
Grant Program
(HMGP)
&
$50,000
Long
26 Propose a monetary set-up/
replacement program for facility
roofs and HVAC systems
Severe Weather, Storm 1A, 3B 2024 Public Works,
Maintenance
Local General Fund
&
$300,000
Long
27 Conduct PSA regarding
tornados and provide education
and awareness media materials
via social media.
Tornado 2A 2024
Office of
Emergency
Management
Local General Fund
&
$1,000
Short
28 Enhance and harden HVAC
System at Barbara J. Riley
Community/Senior Center
Severe Weather, Storm 1A, 5C 2023
Public Works,
City of
Downey
Local General Fund
&
$300,000
Short
City of Downey Hazard Mitigation Plan 5-
22 Action
Number
Mitigation Action
a measure, project, plan or activity proposed to
reduce current and future vulnerabilities described in the risk assessment Hazards Mitigated
Corresponding
Goals &
Objectives
Year
Initiated
Responsible
Department
Potential Funding
Source & Monetary
Amount
Timeframe
Completion1 Status Summary
29 Research best practices for
tornado sheltering that best
match our school campuses and
district facilities. Review
structures in relation to current
building code standards to
determine potential hardening
projects i.e. tornado sheltering
measures.
Tornado 1C, 2A, 5C 2024-25
Downey USD,
DUSD
Emergency
Operations
Team, City of
Downey
Office Of Emergency
Management
&
$10,000,000
Short
30 Distribute information and
education materials that will help
tie this to existing drills already
conducted regularly during the
school year
Tornado 1C, 2A, 5C 2024-25
Downey USD,
DUSD
Emergency
Operations
Team, City of
Downey
Office Of Emergency
Management
&
$10,000,000
Short
31 Enhance mapping data to
identify flood-prone areas, due
to standing water; urban
flooding; etc., throughout the city
and implement improvement
projects to enable efficient
drainage within the identified
vulnerable locations.
Urban Flood 1B
2016,
updated
2023
Public Works
Department
Hazard Mitigation
Grant Program
(HMGP), Flood
Mitigation Assistance
(FMA), Building
Resilient Infrastructure
and Communities
(BRIC)
&
$2,000,000
Medium
32 Enhance debris management
strategies for windstorm events Windstorm 5A
2016,
updated
in 2023
Public Works
Department
In Kind Matches
&
$30,000
Medium
City of Downey Hazard Mitigation Plan A-1
Table of Contents
Earthquake Analysis ........................................................................................................................... A-2 Flood Analysis .................................................................................................................................. A-23 100-Year Flood .................................................................................................................... A-23 500-Year Flood .................................................................................................................... A-38
Additional Hazard Analysis Documentation
City of Downey Hazard Mitigation Plan A-2
Earthquake Analysis
Hazus: Earthquake Global Risk Report
Region Name:
Earthquake Scenario:
Print Date:
Downey, CA
Prob_mag5
March 30, 2023
Disclaimer:
Totals only reflect data for those census tracts/blocks included in the user’s study region.
The estimates of social and economic impacts contained in this report were produced using Hazus loss estimation methodology software which is based on current scientific and engineering knowledge. There are uncertainties inherent in any loss estimation technique. Therefore, there may be significant differences between the modeled results contained in this report and the actual social and economic losses following a specific earthquake. These results can be improved by using enhanced inventory, geotechnical, and observed ground motion data.
City of Downey Hazard Mitigation Plan A-3
Section
General Description of the Region
Building and Lifeline Inventory
Building Inventory
Critical Facility Inventory
Transportation and Utility Lifeline Inventory
Earthquake Scenario Parameters
Direct Earthquake Damage
Buildings Damage
Essential Facilities Damage
Transportation and Utility Lifeline Damage
Induced Earthquake Damage
Fire Following Earthquake
Debris Generation
Social Impact
Shelter Requirements
Casualties
Economic Loss
Building Related Losses
Transportation and Utility Lifeline Losses
County Listing for the Region
Regional Population and Building Value Data
Table of Contents
City of Downey Hazard Mitigation Plan A-4
General Description of the Region
Hazus-MH is a regional earthquake loss estimation model that was developed by the Federal Emergency Management Agency (FEMA) and the National Institute of Building Sciences. The primary purpose of Hazus is to provide a methodology and software application to develop multi-hazard losses at a regional scale. These loss estimates would be used primarily by local, state and regional officials to plan and stimulate efforts to reduce risks from multi-hazards and to prepare for emergency response and recovery.
The earthquake loss estimates provided in this report was based on a region that includes 1 county(ies) from the following state(s):
California
Note:
Appendix A contains a complete listing of the counties contained in the region.
The geographical size of the region is 24.82 square miles and contains 44 census tracts. There are over 55 thousand households in the region which has a total population of 187,417 people. The distribution of population by Total Region and County is provided in Appendix B.
There are an estimated 45 thousand buildings in the region with a total building replacement value (excluding contents) of 29,513 (millions of dollars). Approximately 89.00 % of the buildings (and 48.00% of the building value) are associated with residential housing.
The replacement value of the transportation and utility lifeline systems is estimated to be 9,576 and 315 (millions of dollars) , respectively.
City of Downey Hazard Mitigation Plan A-5
Building Inventory
Hazus estimates that there are 45 thousand buildings in the region which have an aggregate total replacement value of 29,513 (millions of dollars) . Appendix B provides a general distribution of the building value by Total Region and County.