La Verne City Council
October 5, 2026

Agenda Packet - October 5, 2026
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2026 Local Hazard Mitigation Plan | Planning Process
2-6
Date Event Description Attendance
May 21, 2025 CPT Meeting #1
• Steering Committee
• Geographic information system (GIS)
• File sharing site
10 June 10, 2025 CPT Meeting #2
• GIS
• Steering Committee
• Public Outreach Strategy
11 June 10, 2025
Steering
Committee
Meeting #1
• Introductions
• Planning overview
• Role of Steering Committee and ground
rules
• Hazards of concern
• Outreach strategy
16 June 18, 2025 CPT Meeting #3
• Steering Committee
• Public Outreach Strategy
• GIS
8 July 2, 2025 CPT Meeting #4
• Public Outreach Materials Update
• Steering Committee Meeting Agenda 8
July 10, 2025
Steering
Committee
Meeting #2
• Approve June Meeting Summary
• Committee Feedback from State HMP
and LHMP Draft Reviews
• Public Meeting Coordination
• Approve Hazard Scenarios
• Approve Public Survey for Distribution
• Approve Community Lifelines Definition
15 July 30, 2025 CPT Meeting #5
• Public outreach
• Public meeting
• Equity Priority Communities populations
• Goals and objectives
7 August 5, 2025 Public Outreach • Hazard awareness survey opened August 5, 2025 Public Outreach • National Night Out Approx. 600 August 27, 2025 CPT Meeting #6
• Public outreach results to date
• Mitigation catalog / strengths,
weaknesses, obstacles, and
opportunities (SWOO) exercise for each
natural hazard
7 September 18,
2025
Steering
Committee
Meeting #3
• Approve July meeting summary
• Public outreach update
• Draft LHMP table of contents preview
• Hazard mapping overview and input
• SWOO exercise
12

Agenda Packet - October 5, 2026
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2026 Local Hazard Mitigation Plan | Planning Process
2-7
Date Event Description Attendance
September 24,
2025
CPT Meeting #7
• Public meeting discussion
• Plan maintenance protocol
development
• Capability assessment preview
4 October 22, 2025 CPT Meeting #8
• Draft risk assessment results
• Draft hazard risk ranking
• Scheduling for mitigation action
workshop
5 November 5, 2025 CPT Meeting #9 • Mitigation action workshop 6 November 20,
2025
Steering
Committee
Meeting #4
• Approve September meeting summary
• Schedule and milestones
• Risk assessment results
• Risk ranking
10 December 3, 2025 CPT Meeting #10
• Mitigation action workshop follow-ups
• Schedule public comment and
milestone dates
5 December 31,
2025
Public Outreach • Hazard awareness survey results
tabulated
314
January 8, 2026
Steering
Committee
Meeting #5
• Approve November meeting summary
• Equity Priority Community confirmation
• Mitigation goal review
• Draft plan public comment period
15 January 15, 2026 Public Outreach Public meeting to preview the draft LHMP and kickoff public comment period 7
January 22, 2026 Public Outreach Opening of the 2-week public comment period N/A
February 5, 2026 Public Outreach Closure of the 2-week public comment period N/A
February 26, 2026
Plan Submittal to
Cal OES
Submittal of draft plan and plan review tool
to Cal OES for review and approval N/A
TBD Plan Submittal to
FEMA Region 9
Submittal of draft plan to FEMA Region 9 by
Cal OES
N/A
TBD Approval Pending
Adoption
Approval Pending Adoption provided by
FEMA Region 9 N/A
TBD Adoption La Verne City Council adoption of draft plan N/A TBD
Approval
Proof of adoption documentation
submitted to FEMA Region 9 and Cal OES N/A
TBD Approval Final approval of the plan by FEMA Region 9 N/A

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-1

3. CITY OF LA VERNE PROFILE
This chapter provides general information about the City of La Verne, including its historical information, physical setting, general building stock, land use, population, demographics, population trends, and community lifelines. Analyzing this information leads to an understanding of the study area, including economic, structural, and population assets at risk, and of concerns that could be related to hazards analyzed in this plan (e.g., low-lying areas prone to flooding, high percentage of vulnerable persons in an area).

3.1 OVERVIEW

3.1.1 Historical Overview
According to the La Verne Historical Society, due to its flourishing citrus industry, La Verne was a destination for migrant labor in the early 20th century. Nationalities that immigrated to La Verne included Mexican, Chinese, Indian, Japanese, and Filipino immigrants. Mexican immigrants who settled in La Verne after 1910 lived south of the Santa Fe railroad tracks in the and worked extensively in the orange groves and packing houses (City of La Verne 2022).

La Verne was incorporated in 1906 following a period of land speculation brought on by the extension of the Santa Fe Railroad. Originally named Lordsburg at the time of its founding in 1887, the City was selected as the site of the University of La Verne, which was established in 1892 and remains an important community institution. The City was known as the “Heart of the Orange Empire” due to its flourishing citrus industry, until rapid post-WWII development shaped the City’s residential neighborhoods (City of La Verne 2025).

The foothills of the San Gabriel Mountains north of Baseline Road were settled by ranchers in the late 1800s and early 1900s. Meanwhile, the Lordsburg (what will eventually become Old Town La Verne) sprung up along the extension of the Santa Fe Railroad in the southern half of modern day La Verne. These ranches in the north became productive agricultural groves during the citrus boom of the early 1900s. After World War II, the demand for residential development led citrus farmers to sell their agricultural land for housing developments. The large parcels were typically sold and developed with single-family subdivisions, fueling population growth during the 1970s and 1980s. Market conditions at the time, in addition to the steep hilly terrain (many areas of north La Verne have a slop of 20% or greater) and environmental and safety constraints (including fire hazard concerns), led to almost all prior citrus farms land being developed with lower-density, single-family housing which could

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-2
most feasibility fit within the unique hilly topography of this part of the City (City of La Verne 2022).

3.1.2 Government
The City of La Verne is governed by a council-manager form of government, where a fivemember City Council, elected by district, makes policy decisions, and a City Manager, appointed by the council, oversees daily operations. The City Council will assume the responsibility for the adoption of this LHMP while the City Manager will be responsible for overseeing its implementation.

The City of La Verne, California, provides a wide array of services, including community development, parks and recreation, public works, fire, and police.

3.2 PHYSICAL SETTING
This section describes the location, geography, topography, watersheds, and climate of the City of La Verne.

3.2.1 Location
The City of La Verne is nestled in the scenic foothills of the San Gabriel Mountains approximately 35 miles east of Los Angeles, with an area of approximately nine square miles.

The City is bounded by San Dimas to the west, Claremont to the east, Pomona to the south, and the San Gabriel Mountains to the north.

3.2.2 Geology, Geography, and Topography
The city is situated at the base of the San Gabriel Mountains, which are part of the Angeles National Forest. Elevations in the City range from a high of 1,700 feet to a low of 1,000 feet. The terrain of the city is a combination of relatively flat land in the mid and southern portions and hills primarily in the northern half of the City.

Geologically, La Verne is part of the larger San Gabriel Valley region, which is an alluvial plain created by the weathering of the San Gabriel Mountains. The plain slopes generally to the southeast at about 1.05 feet for every 100 feet. Soils in the San Gabriel Valley consist of alluvial debris deposited from the weathering of the San Gabriel Mountains and generally consist of sand, gravel, and clay deposited in successive layers by runoff from the nearby mountains and hills.

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-3

3.2.3 Watersheds and Surface Waters
A watershed is a geographical area that directs
precipitation and snowmelt toward creeks,
streams, rivers, and ultimately outflow locations
such as reservoirs, bays, and the ocean.

Watersheds vary in size and configuration,
encompassing anything from a small body of
water or county to vast regions covering
thousands of square miles with numerous
waterways (National Ocean Service 2024).

Figure 3-1 depicts the general makeup of a
watershed.

The San Gabriel Watershed takes in the City of La
Verne as depicted on Figure 3-2. The red marker
points to La Verne.

Source: (California Water Watch 2025)
Figure 3-2. Watershed for the City of La Verne
La Verne is situated in an alluvial fan that gently slopes in a westward direction towards San Dimas. The alluvial fan is bordered on the north by the San Gabriel Mountains and on the Figure 3-1. Watershed Diagram
Source: NOAA Fisheries, 2022

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-4
south by the San Jose Hills. The alluvial materials were deposited by the many intermittent streams that drain the southern slopes of the San Gabriel Mountains. Four major streams drain from the San Gabriel Mountains and flow into La Verne. These include the San Dimas Creek, Marshall Canyon Creeks, Live Oak Creek, and Thompson Creek.

The San Dimas Creek system, most of which is in the City of San Dimas to the west, is the largest in terms of drainage and watershed area. Smaller secondary drainage systems that flow into San Dimas Creek include Sycamore Canyon, Ham Canyon, Lodi Canyon, West Fork, East Fork, and Wolfskill Canyon, most of which are not located in the City of La Verne. At the base of the mountains, San Dimas Creek flows in a westerly direction in the City of San Dimas.

3.2.4 Climate
The climate of the City of La Verne is typical of Southern California with generally mild temperatures and little to no days below freezing. Average temperatures in the City of La Verne range from 55 degrees Fahrenheit in the winter months to 72 degrees Fahrenheit in the summer months. However, the temperatures can vary over a wide range, particularly when the Santa Ana winds blow, bringing higher temperatures and very low humidity.

Temperatures rarely exceed 110 degrees Fahrenheit in the summer months (June through September), and rarely drop below 30 degrees Fahrenheit in the winter months (November through March).

3.3 POPULATION AND DEMOGRAPHICS
Those that live in the City are one of the most important assets and this LHMP will assess risk to people and identify mitigation strategies to protect them, including equity priority populations.

3.3.1 General Population
Although La Verne is located in metropolitan Los Angeles County, it is a "close-knit" community that has been able to retain its "small town" traditions and virtues. With eight mobile home parks and three large retirement communities, La Verne has a significant senior citizen population. In addition, due to an influx of new upscale housing during the past two decades, La Verne also enjoys a large clientele of school-age youth. La Verne is a wellbalanced residential community that includes a good mix of commercial and industrial uses as well as the University of La Verne, an airport, and fine public and private schools (City of La Verne 2025).

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-5
Current and Historical Population
Table 3-1 shows past population estimates for La Verne from 2000 to 2025. Over that time, La Verne has experienced positive growth over several years over that period.

Table 3-1. Annual Population Data
Year Population Year Population Year Population
2000 31,638 2009 31,234 2018 32,317
2001 31,745 2010 31,120 2019 32,504
2002 31,875 2011 31,153 2020 32,383
2003 31,944 2012 31,526 2021 32,140
2004 31,916 2013 31,971 2022 32,391
2005 31,702 2014 31,968 2023 32,141
2006 31,333 2015 32,583 2024 32,111
2007 31,035 2016 32,484 2025 32,300
2008 31,449 2017 32,444
Source: California Department of Finance Historical Population Estimates The population of La Verne in 2020 increased approximately 7.2% since 2010. La Verne’s growth has outpaced Countywide growth, with Los Angeles County experiencing significantly lower population growth rates during the 2010 to 2020 period (3.2%) (City of La Verne 2022).

Future Population Projections
According to the 2025 City of La Verne General Plan, La Verne is projected to have 37,142 residents, 7,952 residential land use units, and 6,572 jobs by 2045. Compared to Los Angeles County as a whole, growth in La Verne is forecast to be slow, largely because the city is fully built out.

3.3.2 Vulnerable Populations
Underserved communities are populations sharing a particular characteristic, as well as geographic communities, which have been systematically denied a full opportunity to participate in aspects of economic, social, and civic life. Social vulnerability is the potential for loss within an individual or social group. The term recognizes that some traits influence an individual’s or group’s resilience. This is their ability to prepare, respond, cope or recover from an event (FEMA 2023).

Underserved communities and socially vulnerable populations located within the jurisdiction may be more at-risk during hazard events due to a variety of factors, such as their physical

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-6
and financial capacity to react or respond effectively, as well as the location and quality of their housing. Those with greater vulnerability may experience more severe impacts during emergencies or disasters. It is essential for public officials to consider the distinct needs of vulnerable populations in order to ensure their safety.

Social Vulnerability Index
The CDC SVI is a place-based index, database, and mapping application designed to identify and quantify communities experiencing social vulnerability. The current CDC SVI uses 16 US census variables from the 5-year American Community Survey to identify communities that may need support before, during, or after disasters. The factors include economic data as well as data regarding education, family characteristics, housing, language ability, ethnicity, and vehicle access. These variables are combined into a single measure of overall social vulnerability (CDC/ATSDR 2024). The Steering Committee chose this dataset as the basis for defining vulnerable populations or “Equity Priority Communities” in this plan. Factors from the CDC SVI are shown on Figure 3-3.

Figure 3-3. Equity Priority Community Factors

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... [ Below 150% Poverty ]
Socioeconomic [ Unemployed ]
[ Housing Cost Burden ]
> Status [ No High School Diploma ] ... [ No Health Insurance ] ·--·- [ Aged 65 & Older ] .c [ Aged 17 & Younger ] ra Household "- [ Civilian with a Disability ] a, Characteristics [ Single-Parent Households ] C [ English Language Proficiency ] -::s Hispanic or Latino (of any race) > Black or African American, Not Hispanic or Lat ino
Racial & Ethnic Asian, Not Hispanic or Latino
- American Indian or Alaska Native, Not Hispanic or Latino - Minority Status Native Hawaiian or Pacific Islander, Not Hispanic or Lat ino ra Two or More Races, Not Hispanic or Latino
"- Other Races, Not Hispanic or Latino
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> [ Multi-Unit Structures ]
0 [ Mobile Homes ] Housing Type & [ Crowding ] Transportation [ No Vehicle ] ~ [ Group Quarters ]
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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-7
The distribution of Equity Priority Community members among council districts is shown in Table 3-2.

Table 3-2. Estimated Number of Equity Priority Community Members Jurisdiction Total Population EPC Population % of Population 1st Council District 6,351 1,420 22.4%
2nd Council District 6,193 0 0.0%
3rd Council District 6,141 0 0.0%
4th Council District 6,085 0 0.0%
5th Council District 6,797 3,926 57.8%
Total 31,567 5,346 16.9%
Identified Equity Priority Communities
The identification of Equity Priority Communities within the planning area was emphasized throughout the planning process. This was completed through public outreach, review of available data and resources, and the input of local officials. Refer to Section Error! Reference s ource not found. for more information on how vulnerable communities were identified and included in the planning process.

The Steering Committee identified the following Equity Priority Communities within the City of La Verne and prioritized understanding risk and the development of mitigation strategies to support these groups.

Age
Children, especially in the youngest age groups, often cannot protect themselves during a disaster because they lack the necessary resources, knowledge, or life experiences to effectively cope with the situation. Hazard mitigation planning needs to be tailored such that the community is prepared to ensure that children are safe during disaster events and that families with children have access to necessary information and tools.

People 65 years old and older are likely to require financial support, transportation, medical care, or assistance with ordinary daily activities, especially during disasters. They are more likely to be vision, hearing, and/or mobility impaired, more likely to experience mental impairment or dementia, and more likely to live in assisted-living facilities where emergency preparedness is at the discretion of facility operators. Hazard mitigation needs to account for such needs.

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-8
Poverty
Economically disadvantaged families have limited ability to absorb losses due to hazard impacts. Wealth enables families to absorb and recover from losses more quickly, due to insurance, savings, and often the availability of low-cost credit. People with lower incomes tend not to have access to these resources. At the same time, poorer families are likely to inhabit poor quality housing and reside in locations that are most vulnerable to hazard events. Economically disadvantaged neighborhoods are also likely to have relatively poor infrastructure and facilities, which exacerbate the disaster consequences for community members who live there.

Linguistic Isolation
For populations who experience linguistic isolation due to limited English proficiency, disaster communication may be difficult, especially in communities for whom translators and accurate translations of advisories may be scarce. Such households are likely to rely on relatives and local social networks (i.e., friends and neighbors) for information for preparing for a disaster event.

People of Color
Social and economic marginalization of certain racial and ethnic groups, including real estate discrimination, has resulted in greater vulnerability of these groups to all types of hazards. Based on data from a number of studies, African Americans, Native Americans, and populations of Asian, Pacific Islander, or Hispanic origin are likely to be more vulnerable than the broader community. Research shows that minorities are less likely to be involved in predisaster planning and experience higher mortality rates during disaster events. Post-disaster recovery often exhibits cultural insensitivity. Since higher proportions of ethnic minorities live below the poverty line than the majority white population, poverty can compound vulnerability.

Renters
Renters are more vulnerable to natural disasters due to factors like less access to insurance, greater financial strain in moving, and potential displacement challenges in the aftermath.

They also may live in less resilient housing and face delays in property repairs, hindering recovery efforts.

People Who Rely on Public Transportation
Residents who do not own a vehicle may need additional assistance during evacuation from severe hazard events. Disruptions to transit systems can hinder evacuation efforts.

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-9
Access and Functional Needs
Persons with disabilities or other access and functional needs are more likely to have difficulty responding to a hazard event than the general population. Family, neighbors, and local government are the first level of response to assist these individuals, and coordination of efforts to meet their access and functional needs is paramount to life safety efforts.

Emergency managers need to distinguish between functional and medical needs to plan for incidents that require evacuation and sheltering. Knowing the percentage of population with access and functional needs allows emergency management personnel and first responders to anticipate the services needed by that population.

3.4 DEVELOPMENT PROFILE
Local Plan Requirement B2—
44 CFR Part 201.6(c)(2)(ii)(C)
Local Plan Requirement E1—
44 CFR Part 201.6(d)(3)
The plan should describe vulnerability in
terms of providing a general description of
land uses and development trends within
the community so that mitigation options
can be considered in future land use
decisions.

The plan must document how the plan was
reviewed and revised to document
changes in development.

3.4.1 Land Use
Land use describes the human use of land. It represents the economic and cultural activities (e.g., agricultural, residential, industrial, mining, and recreational uses) that are practiced at a given place. Public and private lands frequently represent very different uses (U.S. EPA 2024).

Land cover describes how much of an area is covered by forests, wetlands, impervious surfaces, agriculture, and other land and water types. Water types include wetlands or open water (National Ocean Service 2024).

La Verne is a built-out community with land area totaling 6,964 acres. Table 3-3 shows a potential buildout summary of land use designations for the city. Open space designations is anticipated make up approximately 22 percent of the City’s current land area. The open space category includes parks and recreation areas, utilities, easements, flood control channels, and some hillside areas that will remain undeveloped due to environmental/safety constraints.

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-10
Table 3-3. Land Use 2040 Potential Buildout Summary for the City of La Verne Land Use Category
General Plan Data
Acreage Percent of City
Hillside Residential 477 6.8
Low Density Residential 1,179 16.9
Medium Density Residential 286 4.1
High Density Residential 28 0.4
Very High Density Residential 0 0
Commercial/Business Park 3 0
Industrial 0 0
Community Facilities 600 8.6
Open Space 1,516 21.8
Right-of-Way (including Freeway
Corridor)
894 12.8
Specific Plan—Residential 1,121 16.1
Specific Plan—Mixed Use 860 12.3
Total 6,964 99.8
Source: 2025 City of La Verne General Plan
The northern half of La Verne (north of Baseline Road) generally exhibits different development patterns than the southern half of the City. The area north of Baseline Road is comprised of primarily single-family residential uses with open space or undevelopable land, whereas the area south of Baseline Road is a more diverse mix of single- and multifamily residential, commercial, industrial, and public/institutional uses. These differences in development patterns can be attributed to a combination of topographical and historical forces (City of La Verne 2022).

3.4.2 General Building Stock
Current Building Stock
Table 3-4 identifies the types of housing units in La Verne in 2020. The table summarizes total housing stock according to the type of structure, total occupied units, and the vacancy rate.

As shown in the table, the majority of housing in La Verne is single-family detached housing, which accounted for 63.7% of units in 2020. Mobile homes represent 15.3% of the housing stock. Multifamily units represent 13.3% of the housing stock, with duplex through fourplex units accounting for 5.4% and multifamily developments with five or more units accounting for 7.9%. Single family attached homes represent 7.6% of housing units (City of La Verne 2022).

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-11
Table 3-4. Housing Stock by Type and Vacancy
Total
Single Family Multifamily
Mobile Homes Occupied Vacant
Detached Attached 2-4 5+ Units
Units 12,211 7,783 932 660 967 1,869 11,737 474
Percent 100% 63.7% 7.6% 5.4% 7.9% 15.3% 96.1% 3.9%

3.4.3 Development Trends
Future Trends
La Verne is a largely built-out community with limited vacant land. Desirable new growth consistent with the Community Vision is directed along the City’s key corridors (Foothill Boulevard and Arrow Highway) and around its major activity and business centers (Old Town La Verne, the Metro A Line Station, La Verne Business Park, and Brackett Field) (City of La Verne 2025). As a mostly built-out city, La Verne has a relatively limited capacity for new development. Population growth is anticipated to follow current trends as noted in Section 3.3.1, with future development trends focusing redevelopment and infill development.

Because the City has finite options for expanding the local economic base, each future development project takes on a high level of importance in terms of meeting the City’s economic development goals.

Planning Framework
Future growth and redevelopment in the City of La Verne will be directed by its General Plan.

As a growth Management state, the State of California mandates that all cities and Counties develop and adopt General Plans. California Government Code 65041.1 established state planning priorities which are intended to promote equity, strengthen the economy, protect the environment, and promote public health and safety in the state, including in urban, suburban, and rural communities, shall be as follows:

1. To promote infill development and equity by rehabilitating, maintaining, and improving existing infrastructure that supports infill development and appropriate reuse and redevelopment of previously developed, underutilized land that is presently served by transit, streets, water, sewer, and other essential services, particularly in under-served areas, and to preserving cultural and historic resources.

2. To protect environmental and agricultural resources by protecting, preserving, and enhancing the state's most valuable natural resources; natural lands such as wetlands, watersheds, wildlife habitats, and other wildlands; recreation lands such as parks, trails, greenbelts, and other open space; and landscapes with locally unique features and areas identified by the state as deserving special protection.

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3. To encourage efficient development patterns by ensuring that any infrastructure associated with development, other than infill development, supports new development that does all of the following:
a. Uses land efficiently.
b. Is built adjacent to existing developed areas to the extent consistent with the priorities specified pursuant to subdivision.
c. Is located in an area appropriately planned for growth. d. Is served by adequate transportation and other essential utilities and services. e. Minimizes ongoing costs to taxpayers.

By providing goals and policies, the La Verne General Plan guides development of the City of La Verne into the type of community that its citizens desire. The General Plan is a "constitution" for local decision-making that addresses the range of immediate, mid-, and long-term issues with which the community is concerned. The Plan is intended to allow land use and policy determinations to be made within a comprehensive framework that incorporates public health, safety, and quality of life considerations in a manner that recognizes the resource limitations and the fragility of the community's natural environment.

3.5 COMMUNITY LIFELINES
FEMA released guidance on the community lifelines concept to describe the critical facilities or assets that enable the continuous operation of critical government and business functions and are essential to human health and safety or economic security. Lifelines are the most fundamental services in the community that, when stabilized, enable all other aspects of society to function. When disrupted, decisive intervention is required (FEMA 2023a).

The Steering Committee identified the community lifelines that support the City before, during, and after hazard events. A summary of the lifelines is listed in Table 3-5 and shown on Figure 3-4.

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2026 Local Hazard Mitigation Plan | City of La Verne Profile 3-13
Table 3-5. Community Lifelines in the City of La Verne
Planning Area
Safety and SecurityFood, Hydration, ShelterHealth and MedicalEnergyCommunicationsTransportationHazardous MaterialsWater Systems Total
1 st Council District 7 0 4 0 2 4 1 8 26
2 nd Council District 5 0 7 0 3 3 0 6 24
3 rd Council District 4 0 0 0 0 3 0 14 21
4 th Council District 1 0 0 0 1 1 0 9 12
5 th Council District 5 0 2 1 0 21 4 9 42
Outside of City* 0 0 0 0 0 0 0 16 16
Total 22 0 13 1 6 32 5 62 141
* Sixteen facilities - 2 potable water pump stations, 6 reservoirs, 2 wells and 1 wastewater treatment facility - outside of the City are part of the City's water and wastewater systems.

3.5.1 Safety and Security
Safety and security lifelines include law enforcement/security (e.g., police stations, correctional facilities, site security), fire service, search and rescue, government service (e.g., emergency operation centers, government offices, schools), and community safety (e.g., flood control, protective actions). Overall, 22 safety and security lifelines were identified in the City of this LHMP.

Table 3-6. Safety and Security Lifelines in the City of La Verne Planning Area
Law EnforcementFire ServiceLibraryPark/Recreation FacilitySchoolGovernment Service 1 st Council District 1 1 0 1 3 1
2 nd Council District 0 0 1 1 2 1
3 rd Council District 0 1 0 1 2 0
4 th Council District 0 1 0 0 0 0
5 th Council District 0 0 0 0 5 0
Total 1 3 1 3 12 2

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Figure 3-4. City of La Verne Community Lifelines

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3.5.2 Food, Hydration, Shelter
Food, hydration, and shelter lifelines include food (e.g., grocery stores, food banks), hydration (e.g., water supply chain, bottled water distribution), shelter, and agriculture. No food, hydration, and shelter lifelines were identified in the City for this LHMP. These lifelines exist within the City, but GIS data was not available for a spatial analysis of all facilities. Many of these facilities, including grocery stores, are part of the general building stock analysis. Shelters, food distribution centers, and cooling centers are included in the safety and security lifeline category (e.g., library, religious institution).

3.5.3 Health and Medical
Health and medical lifelines include medical care (e.g., hospitals, pharmacies, long-term care), public health (e.g., health surveillance, behavioral health, labs), patient movement (e.g., emergency medical service), fatality movement, and medical supply chain. Overall, 13 health and medical lifelines were identified in the City for this LHMP.

Table 3-7. Health and Medical Lifelines in the City of La Verne Planning Area
Assisted LivingDialysis CenterPharmacyMedical FacilitySenior Living 1 st Council District 3 0 1 0 0
2 nd Council District 0 0 4 2 1
3 rd Council District 0 0 0 0 0
4 th Council District 0 0 0 0 0
5 th Council District 0 0 0 1 1
Total 3 0 5 3 2

3.5.4 Energy
Energy lifelines include power grid (e.g., generation systems, transmission systems, distribution systems) and fuel (e.g., refineries, fuel storage, pipelines, gas stations). One energy systems lifeline was identified in the City’s 5 th Council
District for this LHMP. Additional energy lifelines exist within the City, but GIS data was not available for a spatial analysis. Many of these facilities, including gas stations, are part of the general building stock analysis.

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3.5.5 Communication
Communication lifelines include infrastructure (e.g., wireless, cable systems, television/radio, internet), alerts/warnings/messages, 911 and dispatch, responder communications, and finance (e.g., banks and electronic payment processing). Overall, six communication lifelines were identified in the City for this LHMP.

Table 3-8. Communication Lifelines in the City of La Verne Planning Area
Microwave TowerCommunication TowerFinance
1 st Council District 0 0 2
2 nd Council District 0 0 3
3 rd Council District 0 0 0
4 th Council District 0 0 1
5 th Council District 0 0 0
Total 0 0 6

3.5.6 Transportation
Transportation lifelines include highway/roadway/motor vehicle (e.g., roads, bridges), mass transit, railway (e.g., freight, passenger), aviation, and maritime.

Overall, 32 transportation lifelines were identified in the City for this LHMP.

Table 3-9. Transportation Lifelines in the City of La Verne Planning Area
Highway/Roadway BridgeRailway/Light Rail BridgeLight Rail Station/Metrolink StationAviation 1 st Council District 4 0 0 0
2 nd Council District 3 0 0 0
3 rd Council District 3 0 0 0
4 th Council District 1 0 1 0
5 th Council District 13 5 1 1
Total 24 5 2 1

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3.5.7 Hazardous Materials
Hazardous materials lifelines include facilities and HAZMAT, pollutants, or contaminants. No superfund sites or locations identified by the Environmental Protection Agency (EPA) dataset are located in La Verne.

3.5.8 Water Systems
Water systems lifelines include potable water infrastructure (e.g., intake, treatment, storage, distribution) and wastewater management (e.g., collection, storage, treatment, discharge). Overall, 62 water systems lifelines were identified for this LHMP.

Table 3-10. Water Systems Lifelines for the City of La Verne Planning Area
Potable Water InfrastructureWastewater Management
1 st Council District 8 0
2 nd Council District 5 1
3 rd Council District 11 3
4 th Council District 8 1
5 th Council District 4 5
Outside of City* 15 1
Total 51 11
* Sixteen facilities - 2 potable water pump stations, 6 reservoirs, 2 wells and 1 wastewater treatment facility - outside of the City are part of the City's water and wastewater systems.

3.6 ECONOMY

3.6.1 Industry, Businesses, and Institutions
According to the City of La Verne’s 2021 – 2029 Housing Element, the 2015-2019 ACS data identified 14,777 civilian employed persons in the La Verne labor force. Table 3-11 summarizes the breakdown of industry types in the City. Of La Verne’s employed residents, the “Educational, Health and Social Services” industry employed the most people at 26.0%. The second largest employment sector was the “Retail Trade” industry, which accounted for 11.6% of the total employed persons in La Verne.

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The City’s workforce holds a variety of types of jobs as shown in Table 3-12, with the largest sector (47.9%) working in management, business, science, and arts occupations, followed by

21.7% in the sales and office occupations (City of La Verne 2022).

Table 3-11. Employment in the City of La Verne by Industry Sector Industry Sector Number Percentage
Agriculture, forestry, fishing and hunting, and mining 139 0.9% Construction 772 5.2%
Manufacturing 1,168 7.9%
Wholesale trade 622 4.2%
Retail trade 1,717 11.6%
Transportation, warehousing, and utilities 752 5.1%
Information, finance, insurance, real estate, rental and leasing
1,436 9.7%
Professional, scientific, management, administration 1,648 11.2% Educational, health and social services 3,846 26.0%
Arts, entertainment, recreation, and services 1,235 8.4% Other services 853 5.8%
Public administration 589 4.0%
Source: (City of La Verne 2022)
Table 3-12. Jobs by Occupation in the City of La Verne
Occupation Sector Number Percentage
Management, business, science, and arts occupations 4,626 47.9% Services occupations 1,407 14.6%
Sales and office occupations 2,093 21.7%
Natural resources, construction, and maintenance
occupations 574 5.9%
Production, transportation, and material moving 954 9.9% Source: (City of La Verne 2022)
Based on the American Community Survey 5-year estimates data profiles from the U.S.

Census Bureau, the unemployment rate for California in 2023 was approximately 6.4%. In contrast, the City of La Verne reported a slightly higher unemployment rate of 6.9%. Figure 3-5 illustrates the unemployment rates for La Verne in relation to the State.

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Source: (U.S. Census 2025)
Figure 3-5. Recent Unemployment Rates for California and the City of La Verne 0%
2%
4%
6%
8%
10%
12%
2015 2016 2017 2018 2019 2020 2021 2022 2023
Unemployement Rate
State of California
City of La Verne

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Part 2 - Risk Assessment

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2026 Local Hazard Mitigation Plan | Hazards of Concern
4-1

4. HAZARDS OF CONCERN

4.1 WHAT IS A HAZARD OF CONCERN?
Defining the hazards that present the greatest risk to the Planning Area is the first step in assessing overall risk to the community. The CPT and Steering Committee reviewed available information to determine what types of hazards may affect the Planning Area, how often they can occur, and their potential severity.

4.2 FEDERAL DISASTER DECLARATIONS
Federal disaster declarations are typically issued for hazard events that cause more damage state and local governments can handle without assistance from the federal government, although no specific dollar loss threshold has been established for these declarations. A presidential disaster declaration puts federal recovery programs into motion to help disaster victims, businesses, and public entities. Some of the programs are matched by state programs. Review of presidential disaster declarations helps establish the probability of reoccurrence for each hazard and identify targets for risk reduction. Table 4-1 lists the federal disaster (DR), emergency (EM), and fire management assistance (FM) declarations that included Los Angeles County since 1954.

Table 4-1. Federal Disaster Declaration History in Los Angeles County Disaster Number Declaration Date
Incident
Type Title
DR-253-CA January 26, 1969 Flood Severe Storms & Flooding DR-295-CA September 29, 1970 Fire Forest & Brush Fires
DR-299-CA February 9, 1971 Earthquake San Fernando Earthquake DR-547-CA February 15, 1978 Flood Coastal Storms, Mudslides & Flooding EM-3067-CA October 29, 1978 Fire Brush Fires
DR-615-CA February 21, 1980 Flood Severe Storms, Mudslides & Flooding DR-635-CA November 27, 1980 Fire Brush & Timber Fires
DR-677-CA February 9, 1983 Storm Coastal Storms, Floods, Slides & Tornadoes DR-799-CA October 7, 1987 Earthquake Whittier Earthquake & Aftershocks DR-812-CA February 5, 1988 Flood Severe Storms, High Tides & Flooding DR-872-CA June 30, 1990 Fire Fires
DR-894-CA February 11, 1991 Freezing Severe Freeze
DR-935-CA February 25, 1992 Flood Rain/Snow/Windstorms, Flooding, Mudslides DR-942-CA May 2, 1992 Fire Fire During a Period of Civil Unrest

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Disaster Number Declaration Date
Incident
Type Title
DR-947 June 28, 1992 Earthquake Landers-Big Bear Earthquake DR-979-CA February 3, 1993 Flood Severe Winter Storm, Mud & Land Slides, & Flooding
DR-1005-CA October 28, 1993 Fire Fires, Mud/Landslides, Flooding, Soil Erosion DR-1008-CA January 17, 1994 Earthquake Northridge Earthquake DR-1044-CA January 10, 1995 Severe
Storm
Severe Winter Storms, Flooding, Landslides,
Mud Flows
DR-1046-CA March 12, 1995 Severe
Storm
Severe Winter Storms, Flooding Landslides,
Mud Flow
EM-3120-CA October 23, 1996 Fire Severe Firestorms
DR-1203-CA February 9, 1998 Severe
Storm
Severe Winter Storms and Flooding
FM-2417-CA June 6, 2002 Fire CA - Copper Fire - 06-06-2002 FM-2462-CA September 4, 2002 Fire Leona Fire
FM-2464-CA September 24, 2002 Fire Williams Fire
FM-2466-CA January 7, 2003 Fire CA - Wildfire (Pacific Fire) - 01-06-2003 FM-2502-CA October 25, 2003 Fire CA-Verdale Fire 10-25-2003 DR-1498-CA October 27, 2003 Fire Wildfires, Flooding, Mudflow and Debris Flow Directly Related T
FM-2528-CA July 14, 2004 Fire CA - Pine Fire - 7-13-2004 FM-2534-CA July 18, 2004 Fire CA-Foothill Wildfire-07-18-2004 FM-2535-CA July 21, 2004 Fire CA-Crown Wildfire-07-21-2004 DR-1577-CA February 4, 2005 Severe
Storm
Severe Storms, Flooding, Debris Flows, and
Mudslides
DR-1585-CA April 14, 2005 Severe
Storm
Severe Storms, Flooding, Landslides, and
Mud and Debris Flows
EM-3248-CA September 13, 2005 Hurricane Hurricane Katrina Evacuation FM-2583-CA September 28, 2005 Fire Topanga Fire
DR-1689-CA March 13, 2007 Freezing Severe Freeze
FM-2691-CA May 9, 2007 Fire Griffith Park Fire
FM-2694-CA May 10, 2007 Fire Island Fire
FM-2708-CA July 8, 2007 Fire Canyon Fire
FM-2733-CA October 21, 2007 Fire Buckweed Fire
FM-2732-CA October 21, 2007 Fire Canyon Fire
FM-2736-CA October 22, 2007 Fire Ranch Fire
EM-3279-CA October 23, 2007 Fire Wildfires

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Disaster Number Declaration Date
Incident
Type Title
DR-1731-CA October 24, 2007 Fire Wildfires, Flooding, Mud Flows, and Debris Flows
FM-2763-CA April 27, 2008 Fire Santa Anita Fire
FM-2788-CA October 12, 2008 Fire Marek Fire
FM-2789-CA October 13, 2008 Fire Sesnon Fire
FM-2792-CA November 15, 2008 Fire Freeway Fire Complex
FM-2791-CA November 15, 2008 Fire Sayre Fire
DR-1810-CA November 18, 2008 Fire Wildfires
FM-2830-CA August 28, 2009 Fire Station Fire
FM-2828-CA August 28, 2009 Fire PV Fire
DR-1884-CA March 8, 2010 Severe
Storm
Severe Winter Storms, Flooding, and Debris
and Mud Flows
FM-2851-CA July 30, 2010 Fire Crown Fire
FM-5025-CA June 2, 2013 Fire Powerhouse Fire
FM-5051-CA January 16, 2014 Fire Colby Fire
FM-5124-CA June 5, 2016 Fire Old Fire
FM-5129-CA June 21, 2016 Fire Fish Fire
FM-5132-CA July 9, 2016 Fire Sage Fire
FM-5135-CA July 23, 2016 Fire Sand Fire
DR-4305-CA March 16, 2017 Flood Severe Winter Storms, Flooding, and Mudslides
FM-5201-CA September 2, 2017 Fire La Tuna Fire
FM-5226-CA December 5, 2017 Fire Rye Fire
FM-5225-CA December 5, 2017 Fire Creek Fire
FM-5227-CA December 6, 2017 Fire Skirball Fire
EM-3396-CA December 8, 2017 Fire Wildfires
DR-4353-CA January 2, 2018 Fire Wildfires, Flooding, Mudflows, and Debris Flows
FM-5280-CA November 9, 2018 Fire Woolsey Fire
EM-3409-CA November 9, 2018 Fire Wildfires
DR-4407-CA November 12, 2018 Fire Wildfires
FM-5293-CA October 11, 2019 Fire Saddleridge Fire
FM-5296-CA October 24, 2019 Fire Tick Fire
FM-5297-CA October 28, 2019 Fire Getty Fire
EM-3428-CA March 13, 2020 Biological Covid-19
DR-4482-CA March 22, 2020 Biological Covid-19 Pandemic

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Disaster Number Declaration Date
Incident
Type Title
FM-5374-CA September 13, 2020 Fire Bobcat Fire
DR-4569-CA October 16, 2020 Fire Wildfires
EM-3591-CA January 9, 2023 Flood Severe Winter Storms, Flooding, and Mudslides
DR-4683-CA January 14, 2023 Flood Severe Winter Storms, Flooding, Landslides, and Mudslides
EM-3592-CA March 10, 2023 Flood Severe Winter Storms, Flooding, Landslides, and Mudslides
DR-4699-CA April 3, 2023 Severe
Storm
Severe Winter Storms, Straight-Line Winds,
Flooding, Landslides, and Mudslides
DR-4769-CA April 13, 2024 Severe
Storm
Severe Winter Storms, Tornadoes, Flooding,
Landslides, and Mudslides
FM-5537-CA September 11, 2024 Fire Bridge Fire
FM-5548-CA December 10, 2024 Fire Franklin Fire
FM-5549-CA January 7, 2025 Fire Palisades Fire
FM-5551-CA January 8, 2025 Fire Hurst Fire
FM-5550-CA January 8, 2025 Fire Eaton Fire
DR-4856-CA January 8, 2025 Fire Wildfires and Straight-Line Winds Source: FEMA, 2025

4.3 NATIONAL RISK INDEX
FEMA’s National Risk Index (NRI) is a dataset and online tool developed to help illustrate risk for 18 natural hazards. The NRI was used as a starting point for natural hazard selection for this LHMP. Hazard chapters align with the NRI hazard types, except for the flood chapter which focuses on the urban flooding concern for the City. Refer to Table 4-2 for the NRI ranking of natural hazards to the Planning Area. The Steering Committee chose to exclude hail, lightning, and tornado due to the “very low” ranking and the lack of historical impacts to the Planning Area.

Table 4-2. National Risk Index for the City of La Verne Hazard Risk Index Included in the Plan?
Avalanche Not Ranked No
Coastal Flooding Not Ranked No
Cold Wave Not Ranked Yes, Extreme Temperature
Drought Very Low Yes

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Hazard Risk Index Included in the Plan?
Earthquake Relatively Moderate, Relatively High &
Very High
Yes
Hail Very Low No
Heat Wave Relatively Low Yes, Extreme Temperature
Hurricane Not Ranked No
Ice Storm Not Ranked No
Landslide Very Low & Relatively Low Yes
Lightning Very Low No
Riverine Flooding Not Ranked Yes, Flood
Strong Wind Very Low Yes, Extreme Wind
Tornado Very Low No
Tsunami Not Ranked No
Volcanic Activity Not Ranked No
Wildfire Not Ranked Yes
Winter Weather Not Ranked No

4.4 HAZARDS OF CONCERN
The 2012 LHMP included Earthquake, Earth Movement, Flood (including dam failure), Wildfire, and Windstorm. Based on a review of the 2023 California State Hazard Mitigation Plan, the National Risk Index, the 2012 LHMP, and input from the Steering Committee, eight hazards, listed alphabetically, were identified as natural hazards of concern affecting La Verne and will be addressed in this plan.

Dam Failure Extreme Wind
Drought Flood
Earthquake Landslide

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Extreme Temperature Wildfire
See the table below for a complete comparison of hazards included in the 2023 California State Hazard Mitigation Plan, the expired 2012 LHMP, and the 2026 LHMP.

Table 4-3. Hazard Mitigation Plan Comparison
2023 California State Hazard
Mitigation Plan
2012 City of La
Verne Local Hazard
Mitigation Plan
2026 City of La
Verne Local Hazard
Mitigation Plan Comment
Air Pollution Not included Wildfire
Air pollution from wildfire
smoke is a concern for the
City and is discussed in the
Wildfire chapter
Civil Disorder Not included Not included Addressed in other plans Cyber Threats Not included Not included Addressed in other plans Dam Failure Flood Dam Failure This local hazard aligns
with the State
Drought Not included Drought
This local hazard aligns
with the State
Earthquake Earthquake Earthquake
This local hazard aligns
with the State
Electromagnetic Pulse Attack Not included Not included Not a concern for the City Energy Shortage Not included Not included Addressed in other plans Epidemic/Pandemic/VectorBorne Disease Not included Not included Addressed in other plans Extreme Cold or Freeze Not included Extreme
Temperature
This local hazard aligns
with the State
Extreme Heat Not included Extreme
Temperature
This local hazard aligns
with the State
Geomagnetic Storm Not included Not included Not a concern for the City Hazardous Materials Release Not included Not included Addressed in other plans Invasive and Nuisance
Species Not included Not included Addressed in other plans Landslide, Debris Flow, and
other Mass Movements
Earth Movement Landslide This local hazard aligns
with the State
Levee Failure Not included Not included No levees in the City Natural Gas Pipeline Hazards Not included Not included Addressed in other plans Oil Spills Not included Not included Addressed in other plans

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2023 California State Hazard
Mitigation Plan
2012 City of La
Verne Local Hazard
Mitigation Plan
2026 City of La
Verne Local Hazard
Mitigation Plan Comment
Other Potential Long-Term
Electrical Outrages Not included Not included Addressed in other plans Public Safety Power Shutoff Not included Wildfire Discussed in Wildfire and Extreme Wind chapters
Radiological Accidents Not included Not included Addressed in other plans Riverine, Stream and Alluvial
Flood
Flood Flood
This local hazard aligns
with the State
Sea-Level Rise, Coastal
Flooding and Erosion Not included Not included Inland area; not a concern for the City Severe Wind, Weather, and
Storms
Windstorm Extreme Wind
This local hazard aligns
with subsections in the
SHMP
Snow Avalanche Not included Not included Not a concern for the City Subsidence Not included Landslide Discussed in the Landslide chapter
Terrorism Not included Not included Addressed in other plans Transportation accidents
Resulting in Explosions or
Toxic Releases
Not included Not included Not a concern for the City
Tree Mortality Not included Not included Not a concern for the City Tsunami and Seiche Not included Not included
Inland area; no large
bodies of water that could
impact people or
development
Urban Structural Fire Not included Not included Addressed in other plans and programs
Volcano Not included Not included Not a concern for the City Well Stimulation and
Hydraulic Fracturing Not included Not included Does not occur in the City Wildfire Wildfire Wildfire This local hazard aligns
with the State

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2026 Local Hazard Mitigation Plan | Risk Assessment Methodology and Tools
5-1

5. RISK ASSESSMENT METHODOLOGY AND TOOLS

5.1 ASSESSING RISK
In hazard mitigation planning, risk is the potential for damage or loss when natural hazards interact with people or assets, such as buildings, infrastructure, and resources. A risk assessment is a process used to identify potential hazards and analyze what could happen if a disaster or hazard occurs. It involves a data-driven analysis to identify potential hazards, what could happen if hazards occur, and determine vulnerabilities to hazards (FEMA 2023).

The risk assessment process focuses on three main elements – hazard identification, exposure identification, and vulnerability identification and loss estimation.

5.2 RISK ASSESSMENT TOOLS
Local Plan Requirement A4 – 44 CFR Part 201.6(b)(3)
Review and incorporation, if appropriate, of existing plans, studies, reports, and technical information.

For this LHMP, GIS and FEMA’s Hazus software programs were used to conduct the risk assessment.

5.2.1 Mapping
GIS tools provide a mechanism to perform quantitative analysis. Hazards that have specified geographic boundaries permit analysis using GIS. These hazards include the following:
• Dam Failure
• Earthquake
• Flood
• Landslide
• Wildfire

5.2.2 Modeling
FEMA’s Hazus model version 6.1 was used to evaluate the following hazards:
• Dam Failure—A Level 2 user-defined analysis was performed for general building stock and critical facilities and infrastructure in inundation areas. Potential losses for the combined inundation areas of multiple dams, specific dams noted later in this section, were estimated using the Hazus flood module. To estimate damage that would result

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from a flood, Hazus uses pre-defined relationships between flood depth at a structure and resulting damage, with damage given as a percent of total replacement value.

Curves defining these relationships have been developed for damage to structures and for damage to typical contents within a structure. By inputting inundation depth data, estimated first floor elevations, and known property replacement cost values, dollar-value estimates of damage were generated.
• Earthquake—A Level 2 analysis was performed to assess earthquake exposure and vulnerability for three deterministic scenarios: Cucamonga M6.88, S. San Andreas M7.91, and Sierra Madre M7.16. The Hazus methodology uses ground motion and ground failure fragility curves to estimate damage state probabilities which are then used to estimate losses at the structure level.

Overview
FEMA developed the Hazards U.S., or Hazus, model in 1997 to estimate losses caused by earthquakes and identify areas that face the highest risk and potential for loss. Hazus was later expanded into a multi-hazard methodology with new models for estimating potential losses from hurricanes and floods. The use of Hazus for hazard mitigation planning offers numerous advantages:
• Provides a consistent methodology for assessing risk across geographic and political entities.
• Provides a way to save data so that it can readily be updated as population, inventory, and other factors change and as mitigation planning efforts evolve. • Facilitates the review of mitigation plans because it helps to ensure that FEMA methodologies are incorporated.
• Supports grant applications by calculating benefits using FEMA definitions and terminology.
• Produces hazard data and loss estimates that can be used in communication with local stakeholders.
• Is administered by the local government and can be used to manage and update an LHMP throughout its implementation.

Hazus is a GIS-based software program used to support risk assessments, mitigation planning, and emergency planning and response. It provides a wide range of inventory data, such as demographics, building stock, community lifelines, transportation and utility lifeline, and multiple models to estimate potential losses from natural disasters. The program can be used to map hazard data and the results of damage and economic loss estimates for buildings and infrastructure.

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Level of Detail for Evaluation
Hazus provides default data for inventory, vulnerability and hazards; this default data can be supplemented with local data to provide a more refined analysis. The model can carry out three levels of analysis, depending on the format and level of detail of information about the Planning Area:
• Level 1—All of the information needed to produce an estimate of losses is included in the software’s default data. This data is derived from national databases and describes in general terms the characteristic parameters of the Planning Area. • Level 2—More accurate estimates of losses require more detailed information about the Planning Area. To produce Level 2 estimates of losses, detailed information is required about local geology, hydrology, hydraulics and building inventory, as well as data about utilities and critical facilities. This information is needed in a GIS format. • Level 3—This level of analysis generates the most accurate estimate of losses. It requires detailed engineering and geotechnical information to customize it for the Planning Area.

5.3 RISK ASSESSMENT APPROACH
This plan evaluated risks associated with each identified hazard for La Verne. Each hazard was profiled using the following steps:
• Description of the Hazard: Defining the hazard and a discussion of potential impacts. • Location: Geographic areas most affected by the hazard. • Extent: Measuring the intensity of the hazard, warning time for preparations, and the reasonable worst-case scenario.
• Previous Occurrences: Summary of past events that have impacted the Planning Area. • Future Occurrences: Probability estimates, including potential frequency and intensity shifts caused by climate change and population and development trends.

For each hazard, one of the following assessment approaches was used, depending on the type of information available for the hazard:
• Quantitative assessment—Performed when numerical data are available to define risk. Available numerical hazard data may include financial impact and probability. • Qualitative assessment—Uses words to describe and categorize the likelihood and consequences of a risk when numerical data are unavailable.

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Vulnerability of exposed structures and infrastructure was evaluated by estimating the probability of occurrence of each event and assessing structures, facilities, and systems that are exposed to each hazard.
• Impact on Life, Health, and Safety
• Impact on General Building Stock
• Impact on Community Lifelines
• Impact on the Economy
• Impact on Historic and Cultural Resources
• Impact on Natural Resources

5.4 SOURCES OF DATA USED IN RISK ASSESSMENT
Hazard information and data were collected for all hazards from a variety of sources, described in the sections below.

5.4.1 Building and Cost Data
Parcel and building information from the Los Angeles County Assessor were used to compile a detailed, citywide structure inventory including replacement costs. Replacement cost is the cost to replace the entire structure with one of equal quality and utility. Replacement cost is based on industry-standard cost-estimation models published in RS Means Square Foot Costs (RS Means, 2024). It is calculated using the RS Means square foot cost for a structure, which is based on the Hazus occupancy class (i.e., multi-family residential or commercial retail trade), multiplied by the square footage of the structure from the tax assessor data.

The construction class and number of stories for single-family residential structures also factor in determining the square foot costs.

5.4.2 Community Lifelines
An inventory of critical facilities and infrastructure was compiled from City, county, state, and national datasets. The facilities were categorized by FEMA’s Community Lifelines: Safety and Security; Food, Hydration, Shelter; Health and Medical; Energy; Communications; Transportation; Hazardous Material; and Water Systems. To protect individual privacy and the security of assets, information is presented in aggregate, without details about specific individual properties or facilities.

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5.4.3 Population
The CDC’s SVI dataset was used for the population analysis. In alignment with the California State HMP, an overall index value of 0.7 or greater was used to define the Equity Priority Communities population. In preparation for spatial overlays with the hazard data, the spatial extent of the Census tract-level SVI data was refined to include populated areas only. The SVI data was combined with the dasymetric Census block data from Hazus to adjust the tract boundaries to populated areas.

5.4.4 Hazus Data Inputs
The following hazard datasets were used for the Hazus analyses conducted for the risk assessment:
• Dam Failure – Dam failure inundation area data, and associated inundation depth grids, provided by CA DWR and USACE were combined into one inundation depth grid.

The combined grid uses the maximum depth where inundation areas overlap. The inundation areas for the following dams are included: Live Oak, Live Oak Reservoir, Puddingstone, Puddingstone Diversion, San Dimas, Thompson Creek, Weymouth Memorial Reservoir, Thompson Creek, and San Antonio Dam. • Earthquake – ShakeMap data from the USGS Building Seismic Safety Council 2014 Event Set were used for the analysis of this hazard. This set of ShakeMap earthquake scenarios is the authoritative USGS collection for the continental United States. The scenario fault ruptures are derived from the latest National Seismic Hazard Model.

Landslide susceptibility data from the California Geological Survey (CGS) was also incorporated into the Hazus model to replace the default data.

5.4.5 Other Local Hazard Data
Local sources used in the risk and vulnerability assessment include the following:
• Flood – An exposure analysis was conducted using the effective DFIRM data from FEMA.

Only a small section of the San Dima Wash flood zone is within the City. One structure is located in the 0.2% annual chance flood zone.
• Landslide – An exposure analysis was conducted using deep-seated landslide susceptibility data from CGS. This data differentiates areas based on rock strength and steepness of slopes combined to create susceptibility classes. For the purposes of the exposure analysis, the classes were grouped as follows:
o Moderate – Susceptibility Classes III and V

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o High – Susceptibility Classes VII, VIII, and IX
o Very High – Susceptibility Class X
• Wildfire – An exposure analysis was conducted using fire hazard severity zones data from CAL FIRE. These zones were mapped based on fuel loading, slope, fire weather, and other relevant factors including winds. The zones are classified as Moderate, High, or Very High fire hazard.

5.4.6 Data Source Summary
Table 5-1 describes the data used for spatially-based exposure and vulnerability assessments.

Table 5-1. Data Source Summary
Data Source Date(s) Format(s)
Countywide Building Outlines Los Angeles Co. Downloaded 5/2025 Digital (GIS) format Los Angeles County Parcels Los Angeles Co. 2025 Digital (GIS) format Building replacement costs RS Means 2024
Digital (tabular)
format
SVI – California State data for
Census Tracts
CDC/ATSDR 2022
Digital (tabular)
format
San Antonio Dam - Maximum High
Breach Scenario inundation depth
grid
USACE NID Downloaded 3/2025 Digital (GIS) format
Thompson Creek Dam – Main
Dam & Saddle Dam 1 Sunny Day
Scenario inundation depth grids
USACE NID Downloaded 5/2025 Digital (GIS) format
California Dam Breach Inundation
Maps, Approved Inundation
Boundaries
CA DWR 2025 Digital (GIS) format
Cucamonga M6.88 ShakeMap
USGS Earthquake
Hazards Program
website
2017 Digital (GIS) format
S San Andreas
BB+NM+SM+NSB+SSB+BG M7.91
ShakeMap
USGS Earthquake
Hazards Program
website
2017 Digital (GIS) format
Sierra Madre M7.16 ShakeMap
USGS Earthquake
Hazards Program
website
2017 Digital (GIS) format
Digital Flood Insurance Rate Map
(effective 6/2/2021; last LOMR
12/27/2024)
FEMA 2024 Digital (GIS) format

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Data Source Date(s) Format(s)
CGS Map Sheet 58: Susceptibility
to Deep-Seated Landslides in
California
CGS 2018 Digital (GIS) format
Fire Hazard Severity Zones in Local
Responsibility Area CAL FIRE 2025 Digital (GIS) format
Police Stations Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Fire Stations Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Points of Interest - Municipal
Services Los Angeles Co. Downloaded 12/2025 Digital (GIS) format City facilities Google Maps Searched 1/2026 Web search
Community centers Google Maps Searched 1/2026 Web search Schools Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Museums Google Maps Searched 1/2026 Web search
Pharmacies Google Maps Searched 1/2026 Web search
Long-Term Care Facilities Google Maps Searched 1/2026 Web search Medical Clinics Google Maps Searched 1/2026 Web search
Electric Power Facilities Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Banks Google Maps Searched 1/2026 Web search
Airport Facilities Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Highway Bridges Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Points of Interest – Transportation Los Angeles Co. Downloaded 12/2025 Digital (GIS) format Light Rail Stations Google Maps Searched 1/2026 Web search Rail Bridges Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Facility Registry System (FRS) -
Toxic Release Inventory (TRI)
Facilities
HIFLD 2025 Digital (GIS) format
Potable Water Facilities Hazus v6.1 Downloaded 12/2025 Digital (GIS) format Potable water structures City of La Verne Provided 5/2025 Digital (GIS) format Potable water wells City of La Verne Provided 5/2025 Digital (GIS) format Potable water booster pump
stations City of La Verne Provided 5/2025 Digital (GIS) format Potable water pumps City of La Verne Provided 5/2025 Digital (GIS) format Potable water reservoirs City of La Verne Provided 5/2025 Digital (GIS) format Sewer structures City of La Verne Provided 5/2025 Digital (GIS) format Sewer lift stations City of La Verne Provided 5/2025 Digital (GIS) format

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5.5 DATA LIMITATIONS
Loss estimates, exposure assessments, and hazard-specific vulnerability evaluations rely on the best available data and methodologies. Uncertainties are inherent in any loss estimation methodology and arise in part from incomplete scientific knowledge concerning natural hazards and their effects on the built environment.

Uncertainties also result from the following:
• Approximations and simplifications necessary to conduct such a study. • Incomplete or dated inventory, demographic, or economic parameter data. • The unique nature, geographic extent, and severity of each hazard. • Mitigation measures already employed by the participating municipalities. • The amount of advance notice residents have to prepare for a specific hazard event. • Uncertainty of climate change projections.

Hazus currently represents the industry best management practice for assessing risk in support of hazard mitigation planning. However, the Hazus model is limited by the availability of data to support its working components. The model makes assumptions where firm data are not available. Assumptions are used, for example, to estimate ground deformation caused by liquefaction. These model limitations can lead to an understatement or overstatement of risk.

These factors can result in a range of uncertainty in loss estimates, possibly by a factor of two or more. Therefore, potential exposure and loss estimates are approximate. These results do not predict precise results and should be used to understand relative risk. Over the long term, the City of La Verne will collect additional data to update and refine existing inventories to assist in estimating potential losses.

Potential economic loss is based on the present value of the general building stock utilizing best available data. The City acknowledges significant impacts may occur to critical facilities and infrastructure as a result of these hazard events causing great economic loss. However, monetized damage estimates to critical facilities and infrastructure, and economic impacts were not quantified and require more detailed loss analyses. In addition, economic impacts to industry such as tourism and the real-estate market were not analyzed.

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DAM FAILURE
10,613
Displaced
Population
Overall Risk Ranking

COMMUNITY

LIFELINES

EXPOSED
4 1
11 27
26 4
8 $350 M
Building Structure &
Contents Damaged
10,390 Tons
Structure Debris

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6. DAM FAILURE

6.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

6.1.1 Description of the Hazard
Definition and Classification of Dams
A dam is an artificial barrier that can store water, wastewater, or liquid-borne materials for many reasons—flood control, human water supply, irrigation, livestock water supply, energy generation, containment of mine tailings, recreation, or pollution control. Many dams fulfill a combination of these functions. They are an important resource in the United States. In California, dams are regulated by the State of California Division of Safety of Dams. Additional regulatory oversight of dams is cited in Chapter 15 and described in Appendix C (Federal & State Agencies, Programs & Regulations).

The California Water Code (Division 3) defines a dam as any artificial barrier, together with appurtenant works that does or may impound or divert water, and that either:
• Has a height of more than 6 feet and it impounds 50 acre-feet or more of water, or • Has a height of 25 feet or higher and impounds more than 15 acre-feet of water.

Dams can be classified according to their purpose, the construction material or methods used, their slope or cross section, the way they resist the force of the water pressure, or the means used for controlling seepage. Materials used to construct dams include earth, rock, tailings from mining or milling, concrete, masonry, steel, timber, plastic, rubber, and combinations of these.

Cause of the Hazard
Partial or full failure of dams has the potential to cause massive destruction to the ecosystems and communities located downstream. Partial or full failure can occur because of one or a combination of the following reasons (FEMA 2016):
• Overtopping caused by floods that exceed the dam capacity (inadequate spillway capacity).

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• Prolonged periods of rainfall and flooding.
• Deliberate acts of sabotage (terrorism).
• Structural failure of materials used in dam construction. • Movement and/or failure of the foundation supporting the dam. • Settlement and cracking of concrete or embankment dams. • Piping and internal erosion of soil in embankment dams. • Inadequate or negligent operation, maintenance, and upkeep. • Failure of upstream dams on the same waterway.
• Earthquake (liquefaction/landslides).

Many dam failures in the United States have been secondary results of other disasters. The most common causes are earthquakes, landslides, extreme storms, equipment malfunction, structural damage, foundation failures, and sabotage. Poor construction, lack of maintenance and repair, and deficient operational procedures are preventable or correctable by a program of regular inspections. Terrorism and vandalism are serious concerns that all operators of public facilities must plan for; these threats are under continuous review by public safety agencies.

Planning Requirements
State of California
All dams whose inundation areas may impact the Planning Area have emergency action plans (EAPs) on file. The EAPs must include the following (Cal OES 2021):
• Emergency notification flow charts.
• Information on a four-step response process.
• Description of agencies’ roles and actions in response to an emergency incident. • Description of actions to be taken in advance of an emergency. • Inundation maps.
• Additional information such as revision records and distribution lists.

After the EAPs are approved by the state, the law requires dam owners to send the approved EAPs to relevant stakeholders. Local public agencies can then adopt emergency procedures that incorporate the information in the EAP in a manner that conforms to local needs and includes methods and procedures for alerting and warning the public and other response and preparedness related items (Cal OES 2021).

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Federal Energy Regulatory Commission
Dams that fall under the jurisdiction of the Federal Energy Regulatory Commission (FERC) also have specified planning requirements. FERC has the largest dam safety program in the United States. It cooperates with a large number of federal and state agencies to ensure and promote dam safety and, more recently, homeland security. FERC requires licensees to prepare EAPs and conducts training sessions on how to develop and test these plans. The plans are designed to serve as an early warning system if there is a potential for, or a sudden release of water from, a dam failure or accident to the dam. The plans include operational procedures that may be used, such as reducing reservoir levels and downstream flows and procedures for notifying affected residents and agencies responsible for emergency management. These plans are frequently updated and tested to ensure that in emergency situations everyone knows what to do, thus saving lives and minimizing property damage.

FEMA Guidance for Flood Mapping
FEMA’s Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures is part of the National Dam Safety Program, a partnership of states, federal agencies, and other stakeholders formed to encourage individual and community responsibility for dam safety. Under this program, states are responsible for regulating nonfederal dams. The guidelines provide information for federal and state agencies, local governments, dam owners, and emergency management officials to use for reducing flood hazards and the resulting potential for economic damage and loss of life. It is a resource for developing state-specific guidelines for dam safety and as a reference manual for mapping dam breach inundation zones (FEMA 2013).

Rehabilitation of High Hazard Potential Dams
FEMA’s Rehabilitation of High Hazard Potential Dams grant program provides assistance for eligible rehabilitation activities that reduce dam risk and increase community preparedness.

For the purposes of the HHPD program, the term “rehabilitation” means the repair, replacement, reconstruction, or removal of a dam that is carried out to meet applicable state dam safety and security standards (FEMA 2020).

Summary of Potential Impacts
Dam failure can be catastrophic to all life and property downstream. California’s Division of Safety of Dams has developed a hazard potential classification system for state-jurisdiction dams, as shown in Table 6-1. This system is modified from federal guidelines, which recommend three-tier classification. The California system adds a fourth hazard classification of “extremely high.” Dams classified as extremely high hazard may impact highly populated areas or critical infrastructure or have short evacuation warning times.

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Table 6-1. State of California Downstream Hazard Potential Classification Hazard
Classification Potential Downstream Impacts on Life and Property Low
No probable loss of human life and low economic and environmental losses.

Losses are expected to be principally limited to the Owner’s property.

Significant No probable loss of human life but can cause economic loss, environmental damage, impacts to critical facilities, or other significant impacts.

High Expected to cause loss of at least one human life.

Extremely High
Expected to cause loss of at least one human life and one of the following: result in an inundation area with a population of 1,000 or more; or result in the inundation of facilities or infrastructure, the inundation of which poses a significant threat to public safety as determined by the department on a case-by-case basis.

Source: (DWR Division of Safety of Dams 2021)
Cascading Hazard Impacts
Dam failure can cause cascading hazards such as landslides, bank erosion, and destruction of downstream habitat. Dam failure may worsen the severity of a drought by releasing water that might have been used as a potable water source.

6.1.2 Location
State- and federally-regulated dams within Los Angeles County have downstream impacts in the City as shown in Table 6-2. These were included in a combined dam inundation analysis. The combined dam failure inundation areas are shown in Figure 6-1.

Table 6-2. Dams in Los Angeles County with Potential to Impact La Verne Name
Hazard
Class Owner
Year
Built
Dam
Type
Crest
Length
(feet)
Height
(feet)
Storage
Capacity
(acrefeet)
Drainage
Area
(sq. mi.)
Live Oak High LA County
Public Works 1922 Gravity 303 76 239 2.3
Live Oak
Reservoir High Metropolitan Water District 1975 Earth 3,000 105 2,500 0.17 Puddingstone High LA County
Public Works 1928 Earth 2,698 147 16,342 33.6
Puddingstone
Diversion High LA County Public Works 1928 Earth 825 34 150 19.8 San Antonio
Dam
High USACE 1956 Earth 3,850 160 11,880 27
San Dimas High LA County
Public Works 1922 Gravity 340 131 1,534 15.9

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Name
Hazard
Class Owner
Year
Built
Dam
Type
Crest
Length
(feet)
Height
(feet)
Storage
Capacity
(acrefeet)
Drainage
Area
(sq. mi.)
Thompson
Creek
High LA County
Public Works 1928 Earth 1,500 66 543 3.46
Weymouth
Memorial
Reservoir
High Metropolitan
Water District 1966 Other 2,400 18 151 N/A
Source: National Inventory of Dams

6.1.3 Extent
Measuring Intensity
The increased risk or susceptibility to dam failure can be determined through inundation zones. The “inundation zone” is the area downstream of the dam that would be flooded in the event of a failure or uncontrolled release of water and is generally much larger than the area for the normal river or stream flood event. The “dam breach inundation zone” is larger than the 100-year floodplain used on FEMA’s flood insurance rate maps (FIRMs) (FEMA 2013).

Warning Time
Warning time for dam failure depends on the cause of the failure. In events of extreme precipitation or massive snowmelt, evacuations can be planned with sufficient time. In the event of a structural failure due to earthquake, it is possible that there would be no warning time. The USGS Earthquake Hazards Program has several dam-safety related earthquake programs, including dam-specific earthquake monitoring programs in California to help monitor safety concerns following seismic events.

A dam’s structural type affects warning time. Earthen dams do not tend to fail completely or instantaneously. Once a breach is initiated, discharging water erodes the breach until the reservoir is empty or the erosion stops. Concrete dams also tend to begin with a partial breach. The time of breach formation ranges from a few minutes to a few hours (U.S. Army Corps of Engineers 2025).

Worst-Case Scenario
A worst-case dam failure scenario for the City of La Verne would be the “probable maximum flood” for the combined dams. The probable maximum flood is defined as the flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions.

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Figure 6-1. Dam Failure Inundation Areas

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6.1.4 Previous Occurrences
There have been no dam failure events that have directly impacted the City of La Verne.

According to the Association of State Dam Safety Officials, “no one knows precisely how many dam failures have occurred in the United States, but they have been documented in every state. From January 2010 through June 2020, state dam safety programs reported 270 dam failures and 581 incidents—episodes that, without intervention, would likely have resulted in dam failure” (Association of State Dam Safety Officials n.d.). The historical record indicates that California has had about 45 failures of non-federal dams. The following sections provide a review of previous dam failure occurrences in Los Angeles County.

Declarations
Federal Declarations
Between 1954 and 2025, the federal government declared that Los Angeles County experienced one disaster (DR) related to dam failure.

Table 6-3. Federal Disaster Declarations for Dam Failure Event Name Disaster Number Declaration Date
Baldwin Hills Dam Failure DR-161 December 21, 1963
Source: (State of California 2023)
State Proclamations
Between 1954 and 2025, California included Los Angeles County in one state-proclaimed dam failure disaster.

Table 6-4. State Disaster Proclamation for Dam Failure
Event Name Disaster Number Proclamation Date
Baldwin Hills Dam Failure - December 16, 1963
Source: (State of California 2023)
United States Department of Agriculture Declarations
Between 2012 and 2025, United States Department of Agriculture (USDA) has not included Los Angeles County in declarations relating to dam failure.

Summary of Significant Events
1963 Baldwin Hills Reservoir Collapse
On December 14, 1963, the dam at the head of Cloverdale Road broke in the Baldwin Hills section of Los Angeles. A river of rushing water from the broken dam resulted in lost homes,

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ruined property, and even death. Automobiles, fragments of houses, and chunks of concrete were carried along the flood’s path and deposited on the ruins of Village Green. A helicopter team rescued 18 people.

6.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.

Probability
Large-scale dam failure events are infrequent and usually coincide with events that cause them, such as earthquakes and excessive rainfall. A Stanford University study found an average of about 10 dam failures per year nationwide over a period of record from 1848 through 2017 (Stanford University 2018).

Since no recorded failures have occurred on a dam that impacted the Planning Area, no estimate of frequency or probability of future occurrence can be developed based on the historical record. However, the risk of failure increases as dams age (Association of State Dam Safety Officials 2024).

Climate Change
Probability of dam failure could increase with changing climate conditions. Increases in the frequency and intensity of extreme rain events could increase the probability that dams will fail or overtop. Although dam failure is not considered a direct result of a changing climate, changes in climate can impact the functionality of dam’s infrastructure. And/or the operation of dams. All dam operations are based on hydrographs. As the hydrographs change, dam operations will change. The 2017 Oroville Dam Spillway incident is a perfect example of how increased precipitation associated with climate change impacts affected dam operations.

Potential Future Impacts
The future impacts from dam failure on the City of La Verne are not anticipated to increase since the current impacts are so negligible. If operational procedures for the Santa Fe dam are adjusted the probability of occurrence for these negligible impacts could change, but the extent and location of the hazard would not change. While the City is completely built out in the dam failure inundation area, redevelopment may increase the population and structural value exposed to the hazard.

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6.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

6.2.1 Summary of Vulnerability
To assess the City’s vulnerability to the dam failure hazard, dams rated as high hazard with mapped inundation areas were combined into a single inundation area. While there have been no historic impacts from dam failure in the City, and therefore no estimate of losses base on historical damages, there is significant vulnerability if a dam failure event were to occur in the future. Nearly 47% of the City’s population is exposed to the dam failure hazard.

The potential impacts to buildings in the City are primarily to residential structures, with more than 91% of the residential building stock in the dam failure hazard area. Community lifeline exposure is also significant with 27 transportation lifelines, 26 water systems, and 11 safety and security lifelines in the highest categories for exposure to the hazard. A Hazus vulnerability assessment was conducted, and detailed findings of potential impacts to the City of La Verne are outlined in the sections below.

6.2.2 Impact on Life, Health, and Safety
Table 6-5 summarizes the results of the estimated impact of the dam failure hazard on the population.

Table 6-5. Estimated Dam Failure Impacts on Population
Planning Area
Total Population
Exposed
Percent of
Population
Displaced
Population
People Requiring
Short-Term
Shelter
1st Council District 5,002 78.8% 4,218 143
2nd Council District 2,581 41.7% 1,306 141
3rd Council District 2,685 43.7% 1,672 45
4th Council District 112 1.8% 13 3
5th Council District 4,370 64.3% 3,403 187
Total 14,751 46.7% 10,613 519

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Equity Priority Communities
Equity Priority Communities include the very young and older residents, who may be unable to get themselves out of the inundation zone quickly. The table below summarizes the Equity Priority Community population exposed to the combined dam failure inundation areas.

Potential impacts to the Equity Priority Communities after a dam failure incident include loss of life and homes, access to drinking water and food, long-term power outages, inability to evacuate, and lack of resources to recover (National Academies Press 2012).

Table 6-6. Estimated Number of Equity Priority Community Members in the Combined Dam Failure Inundation Area
Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 5,002 1,118 22.4%
2nd Council District 2,581 0 0.0%
3rd Council District 2,685 0 0.0%
4th Council District 112 0 0.0%
5th Council District 4,370 1,929 44.1%
Total 14,751 3,047 20.7%

6.2.3 Impact on General Building Stock
The potential dam inundation impacts on the general building stock are shown in the following tables.

Table 6-7. Estimated Property Impacts for Combined Dam Failure Hazard Area Planning Area Total Buildings Buildings Exposed
Value Exposed
(Structure & Contents)
% of Total
Value
Exposed
1st Council District 1,994 1,548 $1,228,660,592 82.0%
2nd Council
District
1,062 453 $898,096,955 54.7%
3rd Council
District
2,078 907 $567,397,023 44.1%
4th Council
District
2,088 50 $243,787,211 16.0%

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Planning Area Total Buildings Buildings Exposed
Value Exposed
(Structure & Contents)
% of Total
Value
Exposed
5th Council
District
1,785 1,198 $2,750,560,624 81.3%
Total 9,007 4,156 $5,688,502,406 60.9%
Table 6-8. Structures by Occupancy Class in Dam Failure Hazard Area Planning Area
ResidentialCommercialIndustrialAgricultureReligionGovernmentEducationTotal 1 st Council District 1,476 32 20 0 4 9 7 1,548
2 nd Council District 411 40 0 0 0 0 2 453
3 rd Council District 905 0 0 0 0 1 1 907
4 th Council District 38 12 0 0 0 0 0 50
5 th Council District 956 127 84 4 6 2 19 1,198
Total 3,786 211 104 4 10 12 29 4,156

6.2.4 Impact on Community Lifelines
Community lifelines in the potential dam failure inundation zone are shown in Table 6-9.

Table 6-9. Community Lifelines in Dam Failure Hazard Area Planning Area
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal 1 st Council District 1 0 0 1 4 3 4 4 17
2 nd Council District 2 0 0 0 2 2 1 3 10
3 rd Council District 0 0 0 0 0 2 2 3 7
4 th Council District 1 0 0 0 0 0 1 2 4

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5 th Council District 0 1 0 3 2 4 19 7 36
Outside of City* 0 0 0 0 0 0 0 7 7
Total 4 1 0 4 8 11 27 26 81
* Sixteen facilities - 2 potable water pump stations, 6 reservoirs, 2 wells and 1 wastewater treatment facility - outside of the City are part of the City's water and wastewater systems.

6.2.5 Impact on the Economy
The potential economic impacts are estimated in the table below.

Planning Area
Estimated Loss Associated with
Combined Dam Failure
% of Total
Replacement
Value
Debris to Be
Removed
Structure Contents Total (Tons)
1 st Council
District
$29,998,608 $39,491,231 $69,489,839 4.6% 3,853
2 nd Council
District
$28,664,534 $46,528,198 $75,192,731 4.6% 828
3 rd Council
District
$53,609,465 $32,064,977 $85,674,443 6.7% 675
4 th Council
District
$5,920,970 $3,293,668 $9,214,638 0.6% 306
5 th Council
District
$40,028,479 $70,302,505 $110,330,984 3.3% 4,728
Total $158,222,057 $191,680,578 $349,902,635 3.7% 10,390

6.2.6 Impact on Historic and Cultural Resources
Depending on severity, dam failure events affecting the City of La Verne could bring devastating loss of life, property damage, and business disruption to the area in and around historical and cultural landmarks. All historic and cultural landmarks within the City combined dam failure inundation area are considered vulnerable to the effects of a dam failure event.

6.2.7 Impact on Ecosystems and Natural Resources
The environment would be vulnerable to risk in the event of dam failure. The inundation could introduce foreign elements into local waterways. This could result in destruction of the downstream habitat and could have detrimental effects on animals.

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6.2.8 Land Uses and Development Trends
New development or redevelopment anywhere in the combined dam failure inundation areas exposes that development to the dam failure hazard. The safety element of the General Plan establishes standards and plans for the protection of the community from dam failure hazards. Dam failure is not addressed as a separate hazard in the safety element, but flooding is. The City has established comprehensive policies and actions for land use in flood hazard areas. Flood-related policies and actions in the general plan will help to reduce the risk associated with dam failure for any future development or re-development in La Verne.

6.3 MITIGATION OPPORTUNITIES
Table 6-10 presents a range of potential opportunities for mitigating the dam failure hazard.

Table 6-10. Potential Opportunities to Mitigate the Dam Failure Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • Remove dams
• Harden dams
• Remove dams
• Harden dams
Reduce Exposure and Vulnerability
• Relocate out of dam
failure inundation
areas
• Elevate home to
appropriate levels
• Replace or
rehabilitate dams
with deficiencies
• Flood-proof facilities
within dam failure
inundation areas
• Replace earthen dams with hardened
structures
• Relocate critical facilities out of dam failure
inundation areas
• Consider open space land use in
designated dam failure inundation areas
• Adopt higher floodplain standards in
mapped dam failure inundation areas
• Retrofit critical facilities within dam failure
inundation areas
Build Local Capacity
• Learn about risk
reduction for the
dam failure hazard
• Learn the evacuation
routes for a dam
failure event
• Become educated
about early warning
systems and the
• Educate employees
on the probable
impacts of a dam
• failure
• Develop a continuity
of operations plan
• Map dam failure inundation areas
• Enhance emergency operations plan to
include a dam failure component
• Institute monthly communications checks
with dam operators
• Inform the public on risk reduction
techniques
• Adopt real-estate disclosure requirements
for the re-sale of property located within
dam failure inundation areas

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Community Scale Organizational Scale Government Scale
• dissemination of
warnings
• Consider the probable impacts of climate
change in assessing the risk associated
with the dam failure hazard
• Establish early warning capability
downstream of listed high-hazard dams
• Consider the residual risk associated with
protection provided by dams in future land
use decisions
Nature-Based Opportunities
• Restore and reconnect floodplains that intersect dam failure inundation areas that have been degraded by development and structural flood control
• Use soft approaches for stream bank restoration and hardening. Soft approaches can include but are not limited to the introduction of large woody debris into a system • Set back levees on systems that rely on levee protection to allow the river channel to meander, which reduces erosion and scour potential
• Acquire property within dam failure inundation areas, remove or relocate structures, and preserve these areas as open space in perpetuity
• Preserve floodplain storage capacity by limiting or prohibiting the use of fill within the floodplain

Agenda Packet - October 5, 2026
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DROUGHT

AT RISK

POPULATION
<5yrs 4.4%
65+ 24.2%

8.5%
Persons in
Poverty
31,567
Population Exposed
Overall Risk Ranking
62 Water
Community
Lifelines
Increased
Wildfire Risk

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2026 Local Hazard Mitigation Plan | Drought
7-1

7. DROUGHT

7.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

7.1.1 Description of the Hazard
Defining the Hazard
Drought is defined as the deficiency in precipitation over an extended period, resulting in a water shortage (NOAA 2024). The severity of a drought depends on the degree of moisture deficiency, the duration, and the size and location to the affected area.

The occurrence of drought is a normal phase in the climate cycle of most regions, originating from a deficiency of precipitation over an extended period of time, usually a season or more.

This leads to a water shortage for some activity, group, or environmental sector. Drought can be characterized based on the following:
• Meteorological measurements such as rainfall deficit compared to normal or expected rainfall
• Agricultural impacts due to reduced rainfall and water supply (e.g., crop loss, herd culling, etc.)
• Hydrological measurements of stream flows, groundwater, and reservoir levels relative to normal conditions
• Direct and indirect socio-economic impacts on society and the economy (e.g., increased unemployment due to failure of an industry because of drought) Cause of the Hazard
Droughts are climatic patterns that occur over long periods of time as the result of many causes. Global weather patterns that produce persistent, upper-level high-pressure systems along the West Coast result in warm, dry air and reduced precipitation. Anomalies of precipitation and temperature may last from several months to several decades. How long they last depend on interactions between the atmosphere and the oceans, soil moisture and land surface processes, topography, internal dynamics, and the accumulated influence of global weather systems.

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Droughts originate from a deficiency of precipitation resulting from an unusual weather pattern. If the weather pattern lasts a short time (a few weeks or a couple of months), the drought is considered short-term. If the weather pattern becomes entrenched and the precipitation deficits last for several months or years, the drought is considered long-term. It is possible for a region to experience a long-term pattern that produces drought, and to have short-term changes that result in wet spells within the long-term pattern. Likewise, it is possible for a long-term wet pattern to be interrupted by weather spells that result in shortterm drought.

Summary of Potential Impacts
Drought can have a widespread impact on the environment and the economy, although it typically does not result in loss of life or damage to structures, as do other natural disasters.

The National Drought Mitigation Center uses three categories to describe likely drought impacts:
• Economic Impacts—These impacts of drought cost people (or businesses) money.

Farmers’ crops are destroyed; low water supply necessitates spending on irrigation or drilling of new wells; water-related businesses (such as sales of boats and fishing equipment) may experience reduced revenue.
• Environmental Impacts—Plants and animals depend on water. When a drought occurs, their food supply can shrink, and their habitat can be damaged. • Social Impacts—Social impacts include public safety, health, conflicts between people when there is not enough water to go around, and changes in lifestyle.

The demand that society places on water systems and supplies—such as expanding populations, irrigation, and environmental needs—contributes to drought impacts. Drought can lead to difficult decisions regarding the allocation of water, as well as stringent water use restrictions, water quality problems, and inadequate water supplies for fire suppression.

There are also issues such as growing conflicts between agricultural uses of surface water and in-stream uses, surface water and groundwater interrelationships, and the effects of growing water demand on uses of water.

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Vulnerability of an activity to drought depends on its water demand and the water supplies available to meet the demand. The impacts of drought vary between sectors of the community in both timing and severity:
• Water supply—The water supply sector encompasses urban and rural drinking water systems that are affected when a drought depletes groundwater supplies due to reduced recharge from rainfall.
• Agriculture and commerce—Impacts on the agriculture and commerce sectors include the reduction of crop yield and livestock sizes due to insufficient water supply for crop irrigation and maintenance of ground cover for grazing. • Environment, public health, and safety—The environmental, public health, and safety sector focuses on wildfires that are both detrimental to the forest ecosystem and hazardous to the public. It also includes the impact of desiccating streams, such as the reduction of in-stream habitats for native species.

Cascading Hazard Impacts
The cascading impact most commonly associated with drought is wildfire. A prolonged lack of precipitation dries out vegetation, which becomes increasingly susceptible to ignition as the duration of the drought extends.

Drought is also often accompanied by extreme heat, exposing people to the risk of sunstroke, heat cramps, and heat exhaustion. Pets and livestock are also vulnerable to heat-related injuries.

7.1.2 Location
A drought is a regional event that is not confined to geographic boundaries; it can affect several areas at once and range in severity across those areas. Drought that affects the Planning Area would affect the entirety of the area simultaneously and has the potential to impact every person, directly or indirectly, in the City, as well as adversely affect the local economy.

7.1.3 Extent
The severity of any given drought depends on the degree of moisture deficiency, the duration, and the size and location of the affected area. The longer the duration of the drought and the larger the area impacted, the more severe the potential impacts.

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Measuring Intensity
Several quantitative methods for measuring drought in the United States. How these indices measure drought depends on the drought classification and the region being considered.

United States Drought Monitor
The U.S. Drought Monitor assesses multiple numeric measures of drought to depict the drought conditions and locations across the United States. The U.S. Drought Monitor uses five drought intensity categories, D0 through D4, to identify areas of drought. These categories are shown on Figure 7-1.

Source: (U.S. Drought Monitor 2024)
Figure 7-1. U.S. Drought Monitor Categories
National Oceanic and Atmospheric Administration Drought Indices National Oceanic and Atmospheric Administration (NOAA) has developed several indices to measure drought impacts and severity and to map their extent and locations (Figure 7-2):
• The Crop Moisture Index measures short-term drought weekly to assess impacts on agriculture.
• The Palmer Z Index measures short-term drought on a monthly scale. • The Palmer Drought Severity Index is based on long-term weather patterns. The intensity of drought in a given month is dependent on current weather plus the

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Category
DO
D1
D2
Description
Abnormally
Dry
Moderate
Drought
Severe
Drought
Extreme
Drought
Exceptional
Drought
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Possible Impacts
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
Some damage to crops, pastures
Streams, reservoirs, or wells low, some water
shortages developing or imminent
Voluntary water-use restrictions requested
Crop or pasture losses likely
Water shortages common
Water restrictions imposed
Major crop/pasture losses
Widespread water shortages or restrictions
Exceptional and widespread crop/pasture losses
Shortages of water in reservoirs, streams, and
wells creating water emergencies
2026 Local Hazard Mitigation Plan | Drought
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cumulative patterns of previous months. Weather patterns can change quickly, and the Palmer Drought Severity Index can respond fairly rapidly. • The Palmer Hydrological Drought Index quantifies hydrological effects (reservoir levels, groundwater levels, etc.), which take longer to develop and last longer. This index responds more slowly to changing conditions than the Palmer Drought Index. • The Standardized Precipitation Index considers only precipitation. A value of zero indicates the median precipitation amount; the index is negative for drought and positive for wet conditions. The Standardized Precipitation Index is computed for time scales ranging from 1 month to 24 months.

Sources: (U.S. Drought Monitor 2025) (NOAA 2025)
Figure 7-2. Example Local and National Drought Index Maps (March - April 2025) Maps of these indices show drought at a given point in time and are not necessarily indicators of the Planning Area’s long-term susceptibility to drought.

Warning Time
Droughts are climatic patterns that occur over long periods of time. Only generalized warning can take place due to the numerous variables that scientists have not pieced together well enough to make accurate and precise predictions.

Empirical studies conducted over the past century have shown that meteorological drought is never the result of a single cause. It is the result of many causes, often synergistic in nature; these include global weather patterns that produce persistent, upper-level high-pressure systems along the West Coast with warm, dry air resulting in less precipitation.

Agenda Packet - October 5, 2026
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USDM l ·WHk Ch~nge Short-Term MIDI l one-Term MIDI
I
m
llol:hliD
(!llml)g/@l!!l E:ilal!ltiiID
The U.S. Drought Mon[t()( depicts lM location and lnlensity of drought across the country. The map uses SclassilicaUOns..:

Abnormally Dry (DO). showing areas that may be going into Of arecomingout of drought, and four levels of drought (Ol 04).

The map is jointly l)(oduced by the National Oceanic and Atmospheric Administrat ion, U.S. Department of Agri<ull\Jre, and Nauonat Drought Mitigation Center. Authors from thes.e agencies rotate creating the map each week, using both
physkal indkators and input from local obserwrs.

This map is used by the U.S. Department of Agriculture to trigger some disaster dt>clarations and loan eligibility.

Individual states and water supply planning may use
additional lnfo rma1ion to inform their de-ctarations artd actions. Learn more 11 .
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OOlillimll)
Drought & Dryness catecories
i DO- Abnormally Ory
01 - Moderate Drought
02 - Severe Drought
03 - Extreme Drought
04 - Exceptional Drought
Total Area 1n Drought (Dl - 04)
% of CA

28.S'M,

16.3'Mi

17.1~

5.8~
O.l'Mi

39.3'Mo • oo ..

Palmer Drought Severity Index
March, 2025
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2026 Local Hazard Mitigation Plan | Drought
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At this time, scientists do not know how to predict drought more than a month in advance for most locations. Predicting drought depends on the ability to forecast precipitation and temperature. Anomalies of precipitation and temperature may last from several months to several decades.

Worst-Case Scenario
An extreme multi-year drought can impact the region with little warning. Combinations of low precipitation and unusually high temperatures could occur over several consecutive years. Intensified by such conditions, extreme wildfires could break out throughout Los Angeles County, as seen in 2025 with the Palisades and Eaton Fires, increasing the need for water. Surrounding communities, also in drought conditions, could increase their demand for water supplies relied upon in the City of La Verne, causing social and political conflicts. If such conditions persisted for several years, the economy of Los Angeles County and La Verne could experience setbacks, especially in water dependent industries.

7.1.4 Previous Occurrences
The following sections provide a review of previous drought occurrences in Los Angeles County.

Declarations
Federal Declarations
There have been no federal declarations for drought for Los Angeles County.

State Proclamations
Between 1954 and 2025, California included Los Angeles County in three state-proclaimed drought disasters.

Table 7-1. State Disaster Proclamations for Drought
Event Name Disaster Number Proclamation Date
1976 Drought -
February 9, 1976;
February 13, 1976; February 24, 1976;
March 26, 1976; and July 6, 1976
Drinking Water Shortage 2014-03 September 18, 2014
Tree Mortality 2015-05 October 30, 2015
Source: (State of California 2023)

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USDA Declarations
Between 2012 and 2025, USDA included Los Angeles County in 22 declarations relating to drought.

Table 7-2. USDA Disaster Declarations for Drought
Event Name Designation Number Declaration Date
Drought-Fast Track S3268 July 12, 2012
Drought S3452 December 19, 2012
Drought-Fast Track S3491 February 27, 2013
Drought-Fast Track S3542 June 19, 2013
Drought-Fast Track S3558 July 31, 2013
Drought-Fast Track S3626 January 15, 2014
Drought-Fast Track S3637 January 23, 2014
Drought-Fast Track S3626 January 15, 2014
Drought-Fast Track S3637 January 23, 2014
Drought S3743 September 17, 2014
Drought S3797 February 25, 2014
Drought-Fast Track S3784 February 4, 2015
Drought S3943 December 23, 2015
Drought-Fast Track S3952 February 17, 2016
Drought-Fast Track S4144 February 23, 2017
Drought-Fast Track S4460 March 20, 2019
Drought-Fast Track S4467 March 22, 2019
Drought-Fast Track S4467 March 22, 2019
Drought-Fast Track S4647 March 11, 2020
Drought-Fast Track S5146 April 8, 2022
Drought-Fast Track S5371 March 17, 2023
Drought-Fast Track S5943 March 25, 2025
Source: (USDA 2025)
Summary of Significant Events
Drought is an ongoing hazard that has shaped California’s history. In the mid-1800s, the Great Drought contributed to the demise of the cattle rancho system. Then in the 1920s and 1930s, dry conditions were prevalent in California and throughout the nation during the Great Depression and Dust Bowl. Later in the 20th century, significant droughts impacting water supplies occurred in the mid-1970s and mid- to early-1990s. Recent multi-year droughts occurred in 2007 to 2009, 2012 to 2016, and 2020 to early 2023. Drought conditions rose again in Los Angeles County in December 2024 and are ongoing at the time of writing (Figure 7-3).

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Source: (National Intigrated Drought Information System 2025) Figure 7-3. Percent of Los Angeles County Affected by Drought Conditions 2020 to 2025 Recent drought periods are described as follows:
• December 2024 to Present – The Los Angeles Watershed statistics indicate that precipitation is only 49 percent of the historical average (California Water Watch 2025).
• 2020 to 2023 Drought – A new record was set during this multi-year drought, with 2022 becoming the driest year in California since official drought records began in 1895. All 58 counties in California were impacted as USDA disaster-designated areas. This included residents in Los Angeles County.
• 2012 to 2016 Drought - The driest 3 consecutive years for statewide precipitation were between 2012 to 2014. Calendar year 2013 set minimum annual precipitation records for many communities.

Agenda Packet - October 5, 2026
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U.S. Drought Monitor (2000 - Present) 9-Month SPI (1895 - Present) Paleoclimate Data (0 - 2017) ~
.,
.., 100%
< 90% .,, 80% C
., 70% ...J
E 60% ..,
u 50%
oi 40% 0.. 30% ~ 20% ~ 10%
0%
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2026 Local Hazard Mitigation Plan | Drought
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• 2007 to 2009 Drought—This was California’s first statewide proclamation of drought emergency, and the first drought in more than 70 years where water shortage was directly linked to social services impacts (California Department of Water Resources 2010). Several California counties were also included in a state disaster proclamation, but Los Angeles County was only included in the emergency proclamation.

7.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.

Probability
Drought has a high probability of occurrence in the Planning Area. From January 2000 to December 2024, some part of Los Angeles County experienced a USDM rating of D0 or higher in 861 out of 1,318 weeks—nearly two-thirds of the weeks (refer to Figure 7-1 and Figure 7-3).

The Planning Area has also been included in USDA drought disaster declarations in 10 of the last 12 years. Historical drought data for the Planning Area indicate there have been four significant multi-year droughts in the last 35 years (1987 to 2024), amounting to a severe drought every 9 years on average.

Climate Change
Future impacts of climate change are expected to influence future drought occurrences for the Planning Area.

With a warmer climate, droughts could become more frequent, more severe, and longer lasting. The Fourth National Climate Assessment Report for the United States indicates that “rising air and water temperatures and changes in precipitation are intensifying droughts.

Changes in the relative amounts and timing of snow and rainfall are leading to mismatches between water availability and needs in some regions. Groundwater depletion is exacerbating drought risk.” (USGCRP 2018).

Because changes in precipitation patterns are still uncertain, the potential impacts and likelihood of drought are uncertain. Department of Water Resources (DWR) has noted impacts of climate change on statewide water resources by charting changes in snowpack, sea level, and river flow. As temperatures rise and more precipitation comes in the form of rain instead of snow, these changes will likely continue or grow even more significant. DWR estimates that parts of the state will experience a 48 to 65 percent loss in snowpack by the end of the century compared to historical averages (DWR 2021). Increasing temperatures may also increase net evaporation from reservoirs. The Planning Area’s water supply is

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derived from groundwater. Increased incidence of drought may cause a drawdown in groundwater resources without allowing for the opportunity for aquifer recharge.

Potential Future Impacts
The City of La Verne reviewed its General Plan under the capability assessment performed for this effort. The General Plan includes landscaping goals and policies that deal with water supply and the protection of water resources.

7.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

7.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the drought hazard, with the potential to affect the entire population of 31,567.

Drought can affect a wide range of economic, environmental, and social activities. Its impacts can span many sectors of the economy because water is integral to the ability to produce goods and provide services. The impacts can reach well beyond the area undergoing physical drought. Vulnerability of an activity to drought depends on its water demand and the water supplies available to meet the demand. The City does not maintain records of historical impacts to the economy, environment, and social activities. Future impacts will vary considerably based on the severity and duration of a drought event.

7.2.2 Impact on Life, Health, and Safety
Drought can affect people’s health and safety, including health problems related to low water flows, poor water quality, or dust and pollution (National Drought Mitigation Center 2025). Other possible impacts include recreational risks; effects on air quality; diminished living conditions related to energy, air quality, and hygiene; compromised food and nutrition; and increased incidence of illness and disease (U.S. Centers for Disease Control and Prevention 2024).

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Droughts can also lead to reduced local firefighting capabilities.

Equity Priority Communities
Equity Priority Communities vulnerable to drought include the very young, the elderly, and those experiencing poverty. An especially vulnerable population is found among those experiencing homelessness.

Those experiencing homelessness often set up shelter under bridges near or along waterways. Locations near bridges, especially if the bridges are built of cement, retain heat, and would adversely impact living conditions; similarly, drought conditions may dry up waterways which would otherwise produce a slight breeze and cool the surround areas due to the flow of the water. The table below summarizes the EPC population exposed to drought.

Table 7-3. Estimated Number of Total Population and Equity Priority Community Members Exposed to Drought
Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 6,351 1,420 22.4%
2nd Council District 6,193 0 0.0%
3rd Council District 6,141 0 0.0%
4th Council District 6,085 0 0.0%
5th Council District 6,797 3,926 57.8%
Totals 31,567 5,346 16.9%

7.2.3 Impact on General Building Stock
The general building stock will not be directly affected by drought conditions. Droughts can have significant impacts on landscapes, which could cause a financial burden to property owners. However, these impacts are not considered critical in planning for impacts from the drought hazard.

7.2.4 Impact on Community Lifelines
Community lifelines as defined for this plan will continue to be operational during a drought.

The cost of potable water may increase, but the community lifeline that includes hydration will still function. Landscaping at community lifeline facilities may not be maintained due to limited resources, but the risk to those areas will be largely aesthetic. For example, when

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water conservation measures are in place, landscaped areas may not be watered frequently and may die. These aesthetic impacts are not considered significant.

7.2.5 Impact on the Economy
A prolonged drought can have a serious economic impact on a community. For instance, drought affects water supply. When drought conditions persist with little to no relief, water restrictions may be put into place by local or state agencies. These restrictions may include placing limitations on when or how frequently lawns can be watered, car washing services, or any other recreational/commercial outdoor use of water supplies. In exceptional drought conditions, watering of lawns and crops may not be an option. If crops are not able to receive water, farmland will dry out and crops will die. This can lead to crop shortages, which, in turn, increases the price of food in all communities including those that do not directly grow crops like La Verne.

Increased demand can also result in shortages and higher water costs. Industries, such as landscaping companies, that rely on water for business could be impacted the most.

Although most businesses will still be operational, they may be impacted aesthetically if their landscaping cannot be maintained.

7.2.6 Impact on Historic and Cultural Resources
The increase in wildfire risk due to drought would be the primary impact on historic and cultural assets.

7.2.7 Impact on Ecosystems and Natural Resources
The impact to ecosystems, even in urban areas, can be profound during a drought. Surface water and waterways are reduced or dry up completely which impacts the habitat for surrounding flora and fauna reliant on those resources.

7.3 MITIGATION OPPORTUNITIES
Table 7-4 presents a range of potential opportunities for mitigating the drought hazard.

Table 7-4. Potential Opportunities to Mitigate the Drought Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • None • Stormwater management
• Identify alternative water sources
Reduce Exposure and Vulnerability

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Community Scale Organizational Scale Government Scale
• Drought-resistant
landscapes
• Reduce water system losses
• Modify plumbing systems
• (through water saving kits)
• Drought-resistant
landscapes
• Reduce private water
system losses
• Water use conflict regulations
• Reduce water system losses
• Distribute water saving kits
• Implement/expand water reuse
projects
Build Local Capacity
• Practice active water
conservation
• Practice active water
conservation
• Public education on drought
resistance
• Expand recycled water network
• Identify alternative water supplies
for times of drought; mutual aid
agreements with alternative
suppliers
• Develop drought contingency plan
• Develop criteria “triggers” for
drought-related actions
• Improve accuracy of water supply
forecasts
• Modify rate structure to influence
active water conservation
techniques
• Increase emergency storage
capacity
Nature-Based Opportunities
• Promote and use reclaimed water supplies
• Increase capacity for stored surface water to create habitats and ecosystems for aquatic species • Promote and use active groundwater recharge

Agenda Packet - October 5, 2026
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EARTHQUAKE
Sierra Madre M7.16 Scenario
31,567
Population Exposed
Social Impacts
$919 M
Building Structure &
Contents Damaged
137,950 Tons
Structure Debris
28 Displaced
Households
14 Require Shortterm Sheltering
45 Days Average
Downtime for
Lifelines

COMMUNITY

LIFELINES

EXPOSED
6 1
22 32
62 5
13

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2026 Local Hazard Mitigation Plan | Earthquake
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8. EARTHQUAKE

8.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

8.1.1 Description of the Hazard
Defining the Hazard
An earthquake is the vibration of the earth’s surface following a release of energy in the earth’s crust. This energy can be generated by a sudden dislocation of the crust or by a volcanic eruption. Most destructive quakes are caused by dislocations of the crust. The crust may first bend and then, when the stress exceeds the strength of the rocks, break and snap to a new position. In the process of breaking, vibrations called “seismic waves” are generated.

These waves travel outward from the source of the earthquake at varying speeds.

The location of an earthquake is commonly described by its focal depth and the geographic position of its epicenter. The focal depth of an earthquake is the depth from the Earth’s surface to the region where an earthquake’s energy originates (the focus or hypocenter). The epicenter of an earthquake is the point on the Earth’s surface directly above the hypocenter.

Cause of the Hazard
Tectonic Plates
The Earth’s crust, which is the rigid outermost shell of the planet, is broken into seven or eight major tectonic plates (depending on how they are defined) and many minor plates. Where the plates meet, they move in one of three ways along their mutual boundary: convergent (two plates moving together), divergent (two plates moving apart), or transform (two plates moving parallel to one another). Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. Subduction is a geological process that takes place at convergent boundaries of tectonic plate, in which one plate moves under another. Regions where this process occurs are known as subduction zones, and they have the potential to generate highly damaging earthquakes.

California is seismically active because of movement of the North American Plate, east of the San Andreas Fault, and the Pacific Plate to the west, which includes the state’s coastal

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communities. The transform (parallel) movement of these tectonic plates against one another creates stresses that 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, rupture occurs 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.

Seismic Fault Lines
Geologists have found that earthquakes reoccur along faults, which are zones of weakness in the earth’s crust. When a fault experiences an earthquake, there is no guarantee that all the stress has been relieved. Another earthquake can still occur. In fact, relieving stress along one part of a fault may increase it in another part.

Faults are more likely to have future earthquakes if they have more 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). “Potentially active” faults are those that displaced layers of rock from the Quaternary period (the last 1,600,000 years) (USGS 2022).

Determining if a fault is “active” or “potentially active” depends on geologic evidence, which may not be available for every fault. The majority of the seismic hazards are on well-known active faults. However, inactive faults, where no displacements have been recorded, also have the potential to reactivate or experience displacement along a branch sometime in the future. An example of a fault zone that has been reactivated is the Foothills Fault Zone. The zone was considered inactive until evidence of an earthquake (approximately 1.6 million years ago) was found near Spenceville, California. Then, in 1975, an earthquake occurred on another branch of the zone near Oroville, California (now known as the Cleveland Hills Fault).

The State Division of Mines and Geology indicates that increased earthquake activity throughout California may cause tectonic movement along currently inactive fault systems.

Summary of Potential Impacts
The greatest earthquake threat in the United States is along tectonic plate boundaries and seismic fault lines located in the central and western states; however, the Eastern United State does face moderate risk to less frequent, less intense earthquake events. Figure 8-1. shows relative seismic risk for the United States.

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Source: (USGS 2018)
Figure 8-1. USGS National Seismic Hazard Map
According to the USGS Earthquake Hazards Program, an earthquake hazard is anything associated with an earthquake that may affect people’s normal activities. This includes the following:
• Surface Faulting—Displacement that reaches the earth’s surface during slip along a fault. Commonly occurs with shallow earthquakes, those with an epicenter less than 20 kilometers.
• Ground Motion (shaking)—The movement of the earth’s surface from earthquakes or explosions. Ground motion or shaking is produced by waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the earth and along its surface.
• Landslide—A movement of surface material down a slope. • Liquefaction—A process by which water‐saturated sediment temporarily loses strength and acts as a fluid. Earthquake shaking can cause this effect. • Tectonic Deformation—A change in the original shape of a material due to strain.

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Cascading Hazard Impacts
Earthquakes can cause large and sometimes disastrous mudslides. Building and road foundations can lose load-bearing strength and may sink into what was previously solid ground. Earthen dams and levees are highly susceptible to seismic events, and the impacts of their failures can be considered secondary risks for earthquakes.

Unless properly secured, hazardous materials can be released, causing significant damage to the environment and people. Hazardous materials releases can occur during an earthquake from fixed facilities or transportation-related incidents. During an earthquake, structures storing these materials could rupture and leak into the surrounding rea or an adjacent waterway, having a disastrous effect on the environment. Transportation corridors can be disrupted during an earthquake, leading to the release of materials to the surrounding environment.

8.1.2 Location
Faults
A direct relationship exists between a fault’s length and location and its ability to generate damaging ground motion at a given site. Small, local faults produce lower magnitude quakes, but ground shaking can be strong, and damage can be significant in areas close to the fault. Large regional faults can generate earthquakes of great magnitudes but, because of their distance and depth, they may result in only moderate shaking in an area. The City of La Verne is in a region of High seismicity. According to the USGS, Southern California has the highest level of earthquake risk in the United States, with half of the expected financial losses from earthquakes in the Nation expected to occur in southern California. Sitting astride the Pacific - North American plate boundary at the Big Bend of the San Andreas Fault, Southern California has over 300 faults capable of producing magnitude 6 and larger earthquakes.

Affecting the more than 20 million inhabitants of the Los Angeles and San Diego metropolitan areas, this complex set of faults presents the greatest urban risk in the United States. Figure 8-2 shows the know faults within close proximity to the Planning Area.

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Source: (California Geological Survey 2015)
Note: City of La Verne indicated by the black dot.

Figure 8-2. Fault Activity Map
Major faults that have the potential to affect the City of La Verne include San Adreas, San Jacinto, Newport Inglewood, Palos Verdes, Whittier, Santa Monica, Sierra Madre, and Chino.

Other lesser faults in the Los Angeles Basin have potential to cause damaging earthquakes.

National Earthquake Hazards Reduction Program Soils
National Earthquake Hazards Reduction Program (NEHRP) soil types define locations that will be significantly impacted by an earthquake. NEHRP Soils B and C typically can sustain lowmagnitude ground shaking without much effect. Areas with NEHRP Soils D, E and F are most commonly affected by ground shaking. Figure 8-3 shows NEHRP soil classifications within the Planning Area.

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Figure 8-3. City of La Verne NEHRP Seismic Site Class

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8.1.3 Extent
Measuring Intensity
Earthquakes are typically classified in one of two ways: By the amount of energy released, measured as magnitude; or by the impact on people and structures, measured as intensity.

Magnitude
An earthquake’s magnitude is a measure of the energy released at the source of the earthquake. Magnitude is commonly expressed by ratings on the moment magnitude scale (Mw), the most common scale used today (USGS n.d.). This scale is based on the total moment release of the earthquake (the product of the distance a fault moved, and the force required to move it). The scale is as follows:
• Great—Mw > 8
• Major—Mw = 7.0 – 7.9
• Strong—Mw = 6.0 – 6.9
• Moderate—Mw = 5.0 – 5.9
• Light—Mw = 4.0 – 4.9
• Minor—Mw = 3.0 – 3.9
• Micro—w < 3
Intensity
The most commonly used intensity scale is the modified Mercalli intensity scale. Ratings of the scale as well as the perceived shaking and damage potential for structures are shown in Table 8-1. The modified Mercalli intensity scale is generally represented visually using a USGS product called a ShakeMap, which shows the expected ground shaking at any given location produced by an earthquake with a specified magnitude and epicenter. An earthquake has only one magnitude and one epicenter, but it produces a range of ground shaking at sites throughout the region, depending on the distance from the earthquake, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the earth’s crust.

Table 8-1. Mercalli Scale and Peak Ground Acceleration Comparison Modified
Mercalli Scale Perceived Shaking
Potential Structure Damage
Estimated PGA a
Resident Buildings (%)
Vulnerable
Buildings
I Not felt None None <0.17%

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Modified
Mercalli Scale Perceived Shaking
Potential Structure Damage
Estimated PGA a
Resident Buildings (%)
Vulnerable
Buildings
II Weak None None 0.17%-1.4%
IV Light None None 1.4%-3.9%
V Moderate Very Light Light 3.9%-9.2%
VI Strong Light Moderate 9.2%-18%
VII Very Strong Moderate Moderate/Heavy 18%-34%
VIII Severe Moderate/Heavy Heavy 34%-65%
IX Violent Heavy Very Heavy 65%-124%
X-XII Extreme Very Heavy Very Heavy >124%
a PGA measure in percent of g, where g is the acceleration of gravity Source: (USGS 2011) (USGS 2025)
Ground Motion
Earthquake hazard assessment is based on expected ground motion. During an earthquake when the ground is shaking, it also experiences acceleration. The peak acceleration is the largest increase in velocity recorded by a particular station during an earthquake. Estimates are developed of the annual probability that certain ground motion accelerations will be exceeded; the annual probabilities can then be summed over a time period of interest.

The most commonly mapped ground motion parameters are horizontal and vertical peak ground accelerations (PGA) for a given soil type. PGA is a measure of how hard the earth shakes, or accelerates, in a given geographic area. Instruments called accelerographs record levels of ground motion due to earthquakes at stations throughout a region. PGA is measured in g (the acceleration due to gravity) or expressed as a percent acceleration force of gravity (%g). These readings are recorded by state and federal agencies that monitor and predict seismic activity.

Maps of PGA values form the basis of seismic zone maps that are included in building codes such as the International Building Code. Building codes that include seismic provisions specify the horizontal force due to lateral acceleration that a building should be able to withstand during an earthquake. PGA values are directly related to these lateral forces that could damage “short period structures” (e.g., single-family dwellings). Longer period response components determine the lateral forces that damage larger structures with longer natural periods (apartment buildings, factories, high-rises, bridges). Table 8-1 also lists damage potential and perceived shaking by PGA factors, compared to the Mercalli scale.

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ShakeMaps
The USGS Earthquake Hazards Program produces maps called ShakeMaps that map ground motion and shaking intensity following significant earthquakes. ShakeMaps focus on the ground shaking caused by the earthquake, rather than on characteristics of the earthquake source, such as magnitude and epicenter. An earthquake has only one magnitude and one epicenter, but it produces a range of ground shaking at sites throughout the region, depending on the distance from the earthquake, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the earth’s crust.

A ShakeMap shows the extent and variation of ground shaking immediately across the surrounding region following significant earthquakes. Such mapping is derived from peak ground motion amplitudes recorded on seismic sensors, with interpolation where data are lacking based on estimated amplitudes. Color-coded instrumental intensity maps are derived from empirical relations between peak ground motions and Modified Mercalli intensity. In addition to the maps of recorded events, the USGS creates the following:
• Scenario ShakeMaps of hypothetical earthquakes of an assumed magnitude on known faults.
• Probabilistic ShakeMaps, based on predicted shaking from all possible earthquakes over a 10,000-year period. In a probabilistic map, information from millions of scenario maps is combined to make a forecast for the future. The maps indicate the ground motion at any given point that has a given probability of being exceeded in a given timeframe, such as a 100-year (1 percent annual chance) event.

The earthquake scenarios modeled for the risk assessment are shown in the following figures:
• Figure 8-4. Cucamonga M6.88 Earthquake Scenario ShakeMap • Figure 8-5. S San Andreas M7.91 Earthquake Scenario ShakeMap • Figure 8-6. Sierra Madre M7.16 Earthquake Scenario ShakeMap National Seismic Hazard Map
National maps of earthquake shaking hazards provide information for creating and updating seismic design requirements for building codes, insurance rate structures, earthquake loss studies, retrofit priorities and land use planning. After thorough review of the studies, professional organizations of engineers update the seismic-risk maps and seismic design requirements contained in building codes (Brown, et al. 2001). The USGS updated the National Seismic Hazard Maps in 2018. New seismic, geologic, and geodetic information on earthquake rates and associated ground shaking were incorporated into these revised maps (Figure 8-1.).

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Figure 8-4. Cucamonga M6.88 Earthquake Scenario ShakeMap

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Figure 8-5. S San Andreas M7.91 Earthquake Scenario ShakeMap

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Figure 8-6. Sierra Madre M7.16 Earthquake Scenario ShakeMap

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Figure 8-7. Liquefaction Zones in La Verne

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Liquefaction and Soil Types
Soil liquefaction occurs when water-saturated sands, silts or gravelly soils are shaken so violently that the individual grains lose contact with one another and float freely in the water, turning the ground into a pudding-like liquid. Building and road foundations lose loadbearing strength and may sink into the ground.

The NEHRP creates maps based on soil characteristics to help identify locations subject to liquefaction. NEHRP soil types define the locations that will be significantly impacted by an earthquake. Table 8-2 summarizes NEHRP soil classifications. NEHRP Soils B and C typically can sustain ground shaking without much effect, dependent on the earthquake magnitude.

The areas that are commonly most affected by ground shaking have NEHRP Soils D, E, and F.

In general, these areas are also most susceptible to liquefaction. Figure 8-7 shows liquefaction zones in the City of La Verne.

Table 8-2. NEHRP Soil Classification System
NEHRP Soil
Type
Description Mean Shear Velocity
to 30 m (m/s)
A Hard Rock 1,500
B Firm to Hard Rock 760-1,500
C Dense Soil/Soft Rock 360-760
D Stiff Soil 180-360
E Soft Clays <180
F Special Study Soils (liquefiable soils, sensitive clays, organic soils, soft clays > 36 m thick) -
Warning Time
There is no current reliable way to predict the day or month that an earthquake will occur at any given location. In 2019, Governor Gavin Newsom announced the launch of the country’s first statewide Earthquake Early Warning System. The California Earthquake Early Warning System uses ground motion sensors from across the state to detect earthquakes before humans can feel them. Notifications provide up to 19 seconds for Californians to take protective action and stay safe during the earthquake. As of April 2025, more than 4 million users have downloaded California’s MyShake App.

Worst-Case Scenario
With the abundance of fault exposure in southern California, the potential scenarios for earthquake activity are many. A worst-case scenario for the City of La Verne would be an earthquake similar to the Sierra Madre M7.16 scenario modeled for this LHMP. Based on regional impacts from historic events listed in Section 8.1.4, structural damages would be

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nearly $1 billion. With the added factor of the liquefaction potential throughout the city, structural failure of buildings, damage to utilities such as water pipes and wells, and sources of power would be inevitable. Since the City operates its own water systems, significant resources would be used to restore functionality to water infrastructure. It would take an estimated 3 months to restore water services to 90% functionality after this worst-case scenario event. Potential warning systems could give approximately 40 seconds notice that a major earthquake is about to occur but would not provide enough warning other than to duck, cover and hold on for personal safety. Again, based on regional impacts from historic events, minor injuries can be expected, but not a significant loss of life from this type of worstcase scenario.

8.1.4 Previous Occurrences
According to Appendix F of the 2023 CA State Hazare Mitigation Plan, La Verne was included in four Los Angeles countywide FEMA declarations for earthquakes: the Landers-Big Bear Earthquake (DR-947), the 1994 Northridge Earthquake (DR-1008), the 1987 Whittier Narrows Earthquake (DR-799), and the 1971 San Fernando Earthquake (DR-299). Additionally, 2 earthquake events occurred within the region that received state disaster proclamations, the Sierra Madre Earthquake (91-04) and the Upland Earthquake (89-07). Table 8-3 lists the 5.0 or greater magnitude earthquakes that have occurred within 100 miles of La Verne. The following sections provide summary descriptions of the most significant of these events.

Table 8-3. Earthquakes Magnitude 5.0 or Larger Within 100-mile Radius of the Planning Area Date and Name Magnitude Epicenter Location Fault Line
07/04/2019
Ridgecrest Earthquakes

7.1 11 miles WSW of Ridgecrest,
7 miles NW
Airport Lake fault
Zone
04/05/2018
Santa Cruz Island Earthquake

5.3 19 miles SW of Santa Cruz
Island
Santa Cruz Island
fault
03/29/2014
Brea Earthquake

5.1 Near Brea, CA Puente Hills fault
07/29/2008 5.44 Near Chino Hills, CA Whittier fault
01/17/1994
Northridge Earthquake

6.7 20 miles west-northwest of LA Northridge Thrust
06/28/1992
Landers-Big Bear Earthquake

7.3 Mojave Desert near Landers,
CA.

It was a complex
rupture involving
multiple faults, with
significant surface
breakage

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Date and Name Magnitude Epicenter Location Fault Line
06/28/1991
Sierra Madre Earthquake

5.8 12 miles northeast of
Pasadena, CA
Clamshell-Sawpit
Canyon fault
02/28/1990
Upland Earthquake

7.9 30 miles east of LA San Jose fault
01/18/1989
Malibu Earthquake

5.0 20 miles south of Malibu, CA N/A
12/03/1988
Pasadena Earthquake

5.0 Below City of Pasadena, CA Raymond fault
06/26/1988
Upland Earthquake

7.9 30 miles east of LA San Jose fault
06/10/1988
Tejon Ranch Earthquake

6.8 Northeast of Frazier Park, CA N/A
10/01/1987
Whittier Narrows Earthquake

5.9 Southeast of Pasadena Puente Hills fault
01/01/1979
Malibu Earthquake

5.2 South of Malibu, CA N/A
08/13/1978
Santa Barbara Earthquake

5.1 Southeast of Santa Barbara,
CA
Unknown
02/21/1973
Point Mugu Earthquake

5.3 Near Oxnard, 45 miles west of
LA
San Fernando fault
02/09/1971
San Fernando Earthquake

6.5 Near Sylmar, CA San Fernando fault
12/4/1948
Desert Hot Springs Earthquake

6.0 Near Desert Hot Springs, 100
miles east of LA
S. Branch San
Andreas fault
6/30/1941
Santa Barbara Earthquake

5.5 6 miles ESE of Santa Barbara,
CA
N/A
3/10/1933
Long Beach Earthquake

6.4 3 miles south of Huntington
Beach, CA
Newport-Inglewood
fault
Source: (Southern California Earthquake Data Center 2025) Summary of Significant Events
2024 Earthquake Near Highland Park
An unnamed 4.4 magnitude earthquake along the Puente Hills fault shook the greater Los Angeles area on August 12, 2024. Community members reportedly felt the quake as far north as Porterville and south to Chula Vista.
2010 Pico Rivera Earthquake

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Pico Rivera was the epicenter of a magnitude 4.4 earthquake on March 16, 2010. The earthquake struck about 1.5 miles northeast of Pico Rivera at a depth of 11.7 miles, which is considered shallow. The USGS stated that the quake was likely from the Puente Hills thrust fault. The epicenter was about 4.5 miles south of the epicenter of the 1987 Whittier Narrows earthquake. Both earthquakes exhibited thrust faulting. However, the 2010 earthquake strike rotated clockwise, suggesting that a different thrust system was activated. There were no injuries or major damage, but plenty of people felt the shaking. It was reported to have been felt from San Bernardino County to Santa Monica, and as far south as San Diego. 1994 Northridge Earthquake
The 1994 Northridge Earthquake was the costliest seismic event in California since the 1906 San Francisco Earthquake. The infrastructure of the metropolitan area was severely disrupted. Freeways collapsed, power systems for the city and linked communities as far away as Oregon were temporarily blacked out, and communications were disrupted. The California State HMP reports the Northridge Earthquake caused over $40 billion of disaster losses, 57 deaths, and 11,846 injuries (Cal OES 2023).

Officially lasting approximately 30 seconds, and with a magnitude of 6.7, this earthquake caused significant damage to buildings. Of 57 fatalities attributed to this quake, 16 were a result of the collapse of a single structure—the Northridge Meadows apartment building. The ground motion was measured throughout Southern California, including intensity readings of 1.82 g near the Ventura Freeway in the Tarzana area. Ground motions as strong as 1.21 g were measured as far away as Inglewood (approximately 25 miles from Northridge). One “g” of ground motion is enough to make unsecured buildings move off their foundations.

According to the USGS and the Southern California Earthquake Center, the Northridge Earthquake raised nearby mountains by as much as 70 centimeters. The fault, which was previously unknown, appears to be truncated by the fault that broke in the similarly sized 1971 San Fernando Earthquake, the two faults abutting at a depth of 5 miles. The Northridge Earthquake caused many times more damage than the 1971 event, primarily because its fault is directly under the densely populated valley, whereas the 1971 fault lies under the mountains.

The 1971 San Fernando earthquake
The 1971 San Fernando earthquake (also known as the 1971 Sylmar earthquake) occurred in the early morning of February 9 in the foothills of the San Gabriel Mountains in Southern California. The origin of faulting was located 5 miles north of the San Fernando Valley. The unanticipated thrust earthquake had a magnitude of 6.5 on the Ms scale and 6.6 on the Mw

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scale, and a maximum Mercalli intensity of XI. Damage was locally severe in the northern San Fernando Valley and surface faulting was extensive to the south of the epicenter in the mountains, as well as urban settings along city streets and neighborhoods. Uplift and other effects affected private homes and businesses. The shaking surpassed building code requirements and exceeded what engineers had prepared for, and although most dwellings in the valley had been built in the prior two decades, even modern earthquake-resistant structures sustained serious damage.

8.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.

Probability
California experiences hundreds of earthquakes each year, most with magnitudes below 3.0 and minimal damage. Earthquakes that cause moderate damage to structures occur several times a year. According to the USGS, a strong earthquake measuring greater than Magnitude 5.0 occurs statewide every 2 to 3 years, and major earthquakes of more than Magnitude 7.0 occur once a decade. The San Andreas Fault has the potential for experiencing major to great events.

Based on the most recent earthquake forecast model for California, scientists estimate that in the next 30 years the Los Angeles region has a 60 percent probability of an earthquake of Magnitude 6.7 or greater, a 46 percent probability of an earthquake of Magnitude 7 or greater, and a 31 percent probability of an earthquake of Magnitude 7.5 (USGS n.d.). • The Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3) predicts the probability of an earthquake of Magnitude 6.7 or greater over the next 30 years as shown on Figure 8-8. The UCERF3 also defined the following 30-year probability for the deterministic earthquake scenarios used for the risk assessment in this LHMP:
• Cucamonga M6.88 = 1.49%
• Sierra Madre M7.16 = 1.12%
• S. San Andreas = 16.90%

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Figure 8-8. UCERF3 Earthquake Probability
Climate Change
It is unknown whether climate change has a direct impact on earthquake probability or severity. However, cascading hazards related to earthquakes are exacerbated by climate change. Increasing air temperatures and extreme weather events can affect soil integrity and affect erosion, sedimentation, and landslide occurrence associated with earthquakes.

Potential Future Impacts
Since the entire Planning Area is located within earthquake hazard zones, all future development will, to some extent, be exposed to the earthquake hazard. The City of La Verne will strictly enforce all seismic building codes and design standards to prevent loss of life and property from earthquakes. Public education, cooperation with the community development, and individual preparedness are essential.

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1/1000 1/100 1/10 1 10
30•year M~.7 likelihood tPe1cenl)
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Uniform California Earthquake
Rupture Forecast, Version 3
(UCERF3)
2026 Local Hazard Mitigation Plan | Earthquake
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8.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

8.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the earthquake hazard, so an earthquake has the potential to affect the entire population, all 9,007 buildings in the Planning Area, with a total replacement value of $9.3 billion, all of the Planning Area’s identified critical facilities, and the entire environment of the Planning Area. Liquefaction zones and areas with NEHRP soils D and E are considered more vulnerable and are noted in the sections below.

8.2.2 Impact on Life, Health, and Safety
Depending on the severity of the earthquake some people may be directly injured or killed.

In addition, homes and businesses may be damaged, resources and supplies may be scarce, business interruptions may keep people from working, utilities may have outages, schools may be temporarily closed, and road closures may cause extra time and travel. All of these indirect effects could impact people who suffered no direct harm from the earthquake. Thus, the entire population must deal with the consequences of earthquakes to some degree.

Estimated Impacts on Persons and Households
Impacts on persons and households in the Planning Area were estimated for the scenario events assessed through the Level 2 Hazus analysis. Table 8-4 summarizes the results.

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Table 8-4. Estimated Earthquake Impact on Persons and Households Planning Area
Cucamonga M6.88 S. San Andreas M7.91 Sierra Madre M7.16 Displaced Households Short-Term Shelter Displaced Households Short-Term Shelter Displaced Households Short-Term Shelter 1st Council District 3 2 0 0 7 3
2nd Council District 5 3 0 0 9 5
3rd Council District 1 0 0 0 2 1
4th Council District 1 1 0 0 2 1
5th Council District 4 2 0 0 8 4
Tota 14 7 0 0 28 14
Equity Priority Communities
All people located in the liquefaction zone or NEHRP Class D and E Soils areas are considered exposed and potentially vulnerable. Equity Priority Community populations include the very young, the elderly, and those experiencing poverty. These populations are most susceptible based on many factors, including their physical and financial ability to react or respond during a hazard and the ability to be self-sustaining for prolonged periods of time after an incident because of limited ability to stockpile supplies.

Equity Priority Communities may live in structures that do not conform to seismic building codes; therefore, homes will sustain more damage during an event. Those experiencing homelessness are also especially vulnerable due to their lack of stable shelter and, depending on their location, may be threatened by bridge or other structural collapse. Those organizations with physical structures that provide care, services, and shelter may be impacted as a result of an earthquake. The tables below outline the number of Equity Priority Community members exposed to the earthquake liquefaction zone and NEHRP Class D and E soils.

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Table 8-5. Estimated Number of Total Population and Equity Priority Community Members Exposed to the Earthquake Liquefaction Zone
Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 0 0 0.0%
2nd Council District 0 0 0.0%
3rd Council District 0 0 0.0%
4th Council District 65 0 0.0%
5th Council District 5 5 100.0%
Total 70 5 6.6%
Table 8-6. Estimated Number of Total Population and Equity Priority Community Members Exposed to NEHRP Soil Classes D & E
Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 3,345 1,230 36.8%
2nd Council District 5,163 0 0.0%
3rd Council District 1,700 0 0.0%
4th Council District 1,364 0 0.0%
5th Council District 708 635 89.7%
Total 12,280 1,866 15.2%

8.2.3 Impact on General Building Stock
Building Age
Table 8-7 identifies significant milestones in building and seismic code requirements that directly affect the structural integrity of development. Using these time periods, the planning team identified the number of structures in the Planning Area by date of construction.

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Table 8-7. Age of Structures in La Verne
Time Period
Number of
Current Structures
Built in Period Significance of General Time Frame
Pre-1933 466 Before 1933, there were no explicit earthquake requirements in building codes. State law did not require local governments to have building officials or issue building permits.
1933 to 1940 146 In 1940, the first strong motion recording was made. 1941 to 1960 943 In 1960, the Structural Engineers Association of California published guidelines on recommended earthquake provisions. 1961 to 1975 2,208 In 1975, significant improvements were made to lateral force requirements.
1976 to 1993 4,161 In 1994, the Uniform Building Code was amended to include provisions for seismic safety.
1994 to Present 1,083 Seismic code is currently enforced.

Total 9,007
The number of structures does not reflect the number of total housing units, as many multifamily units and attached housing units are reported as one structure. Only about 12 percent of the Planning Area’s structures were constructed after the Uniform Building Code was amended in 1994 to include seismic safety provisions. Approximately 5 percent were built before 1933 when there were no building permits or seismic standards.

Loss Potential
Property losses were estimated through the Level 2 Hazus analysis for the assessed earthquake fault scenarios. Table 8-8 shows the estimates for damage to structures and building contents with the percent of total replacement value.

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Table 8-8. Loss Estimates for Fault Scenarios
Planning Area
Estimated Loss Associated with Earthquake % of Total
Replacement
Structure Contents Total Value
Cucamonga M6.88
1 st Council District $76,438,905 $34,306,059 $110,744,964 7.4% 2 nd Council
District
$122,970,064 $37,281,727 $160,251,792 9.8%
3 rd Council
District
$72,973,294 $28,610,977 $101,584,271 7.9%
4 th Council
District
$87,493,823 $35,462,777 $122,956,601 8.1%
5 th Council
District
$169,391,715 $74,061,755 $243,453,470 7.2%
Total $529,267,801 $209,723,296 $738,991,097 7.9%
S San Andreas M7.91
1 st Council District $15,312,345 $7,558,592 $22,870,936 1.5% 2 nd Council
District
$22,090,753 $7,333,044 $29,423,797 1.8%
3 rd Council
District
$11,288,665 $4,946,213 $16,234,878 1.3%
4 th Council
District
$14,663,512 $6,772,988 $21,436,499 1.4%
5 th Council
District
$38,612,594 $17,540,127 $56,152,721 1.7%
Total $101,967,869 $44,150,963 $146,118,831 1.6%
Sierra Madre M7.16
1 st Council District $97,326,895 $43,030,931 $140,357,826 9.4% 2 nd Council
District
$154,720,331 $46,840,918 $201,561,249 12.3%
3 rd Council
District
$81,311,861 $31,550,014 $112,861,875 8.8%
4 th Council
District
$102,921,471 $40,855,666 $143,777,137 9.4%
5 th Council
District
$225,615,079 $94,779,659 $320,394,738 9.5%
Total $661,895,637 $257,057,188 918,952,826 9.8%

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8.2.4 Impact on Community Lifelines
The entire Planning Area and all community lifelines are vulnerable to earthquakes, such as the Metro light rail track and station that may be damaged resulting in delayed transportation or evacuation. The Community lifelines in liquefaction zones or built on NEHRP D and E soils are more vulnerable to the earthquake hazard (Table 8-9 and Table 8-10).

Table 8-9. Community Lifelines in Earthquake Liquefaction Zone Planning Area
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal 1 st Council District 0 0 0 0 0 0 0 0 0
2 nd Council District 0 0 0 0 0 0 0 0 0
3 rd Council District 0 0 0 0 0 0 0 0 0
4 th Council District 0 0 0 0 0 0 0 1 1
5 th Council District 0 0 0 0 0 0 5 3 8
Outside of City* 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 5 4 9
* Sixteen facilities outside of the City are part of the City's water and wastewater systems.

Table 8-10. Community Lifelines in the NEHRP Soil Classes D & E Planning Area
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal 1 st Council District 1 0 0 1 1 3 1 5 12
2 nd Council District 2 0 0 0 4 4 3 1 14
3 rd Council District 0 0 0 0 0 1 1 0 2

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Planning Area
CommunicationsEnergyFood, Hydration, ShelterHazardous MaterialsHealth and MedicalSafety and SecurityTransportationWater SystemsTotal 4 th Council District 0 0 0 0 0 0 0 1 1
5 th Council District 0 0 0 2 0 0 14 5 21
Outside of City* 0 0 0 0 0 0 0 5 5
Total 3 0 0 3 5 8 19 17 55
* Sixteen facilities - 2 potable water pump stations, 6 reservoirs, 2 wells and 1 wastewater treatment facility - outside of the City are part of the City's water and wastewater systems.

Time to Restore Community Lifelines to Functionality
Hazus estimates the time to restore community lifelines to fully functional use. Results are presented as probability of being functional at specified time increments: 1, 3, 7, 14, 30 and 90 days after the event. For example, Hazus may estimate that a facility has 5 percent chance of being fully functional on Day 3, and a 95 percent chance of being fully functional on Day

90. The analysis of community lifelines in the planning area was performed for the assessed earthquake scenarios. The results are summarized in Figure 8-9 through Figure 8-11. These figures show the average functionality for all community lifelines in each category.

Figure 8-9. Average Community Lifeline Functionality by Number of Days Post-Event, Cucamonga Fault Scenario
0 20
40 60
80 100
Communications Energy Hazardous
Materials
Health & Medical Safety & Security Transportation Water Systems Percent Functionality
At Day 1 At Day 3 At Day 7 At Day 14 At Day 30 At Day 90

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Figure 8-10. Average Community Lifeline Functionality by # of Days Post-Event, San Andreas Fault Scenario
Figure 8-11. Average Community Lifeline Functionality by Number of Days Post-Event, Sierra Madre Fault Scenario

8.2.5 Impact on the Economy
Large-scale earthquakes can inflict significant economic damage, including direct losses from destroyed property and infrastructure, and indirect impacts like disruptions to businesses and supply chains, potentially leading to long-term economic hardship. The scenario earthquakes modeled for this risk assessment estimate as much as 10 percent of the total replacement cost value of the City could be damaged from earthquakes. That is 10 percent of the tax base, the economic engine for the City. Each of these earthquake 0 20
40 60
80 100
Communications Energy Hazardous
Materials
Health & Medical Safety & Security Transportation Water Systems Percent Functionality
At Day 1 At Day 3 At Day 7 At Day 14 At Day 30 At Day 90 0 20
40 60
80 100
Communications Energy Hazardous
Materials
Health & Medical Safety & Security Transportation Water Systems Percent Functionality
At Day 1 At Day 3 At Day 7 At Day 14 At Day 30 At Day 90

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scenarios would have regional impacts that would stress regional resources that would impact recovery times for the City.

The Hazus analysis estimated the number of earthquake-caused debris in the Planning Area for the assessed events, as summarized in Table 8-11.

Table 8-11. Estimated Earthquake-Caused Debris
Planning Area
Debris to Be Removed (tons)x 1000
Cucamonga M6.88 S San Andreas M7.91 Sierra Madre M7.16
1 st Council District 14.50 2.62 20.71
2 nd Council District 24.63 3.55 32.99
3 rd Council District 8.51 1.04 10.98
4 th Council District 10.15 1.30 13.38
5 th Council District 41.45 8.51 59.91
Total 99.24 17.01 137.95

8.2.6 Impact on Historic and Cultural Resources
Earthquakes can cause significant damage to historical and cultural resources, ranging from structural collapse of buildings and monuments to the destruction of artifacts and archaeological sites, impacting cultural heritage and potentially causing irreparable losses.

La Verne boasts a rich collection of historic and cultural resources that reflect its transformation from a citrus farming town to a suburban community. Various assets, such as the Weber House, a windmill, old barns, vehicles, and farm equipment from the “orange empire” (La Verne Historical Society 2024). Each of these resources would be susceptible to impacts from earthquakes.

8.2.7 Impact on Ecosystems and Natural Resources
Earthquakes cause significant environmental impacts, including ground shaking, landslides, tsunamis, soil liquefaction, and potentially, the release of hazardous materials, all of which can lead to habitat destruction, water contamination, and changes in land morphology.

8.2.8 Land Uses and Development Trends
New development or redevelopment anywhere in the City of La Verne exposes that development to the earthquake hazard. The safety element of the General Plan establishes standards and plans for the protection of the community from seismic hazards. The City has established comprehensive policies and actions for land use. Seismic policies and actions in

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the general plan will help to reduce the risk associated with earthquakes for any future development or re-development in La Verne.

8.3 MITIGATION OPPORTUNITIES
Table 8-12 presents a range of potential opportunities for mitigating the earthquake hazard.

Table 8-12. Potential Opportunities to Mitigate the Earthquake Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • None • None
Reduce Exposure and Vulnerability
• Locate outside of hazard
area (off soft soils)
• Retrofit structure (anchor
house structure to
foundation)
• Secure household items that
can cause injury or damage
(such as water heaters,
bookcases, and other
appliances)
• Build to higher design
• Locate or relocate critical
functions outside hazard
area where possible
• Build redundancy for critical
functions and facilities
• Retrofit critical buildings and
areas housing critical
functions
• Locate critical facilities or
functions outside hazard
area where possible
• Harden infrastructure
• Provide redundancy for
critical functions
• Adopt higher regulatory
standards
• Perform seismic retrofits for
vulnerable critical buildings
and areas
Build Local Capacity
• Practice “drop, cover, and
hold”
• Develop household
mitigation plan, such as
creating a retrofit savings
account, communication
capability with outside, 72-
hour self-sufficiency during
an event
• Keep cash reserves for
reconstruction
• Become informed of the
hazard and risk reduction
alternatives available
• Develop a post-disaster
action plan for your
household
• Adopt higher standard for
new construction; consider
“performance-based
design” when building new
structures
• Keep cash reserves for
reconstruction
• Inform your employees on
the possible impacts of
earthquake and how to deal
with them at your work
facility.
• Develop a continuity of
operations plan
• Provide better hazard maps
• Provide technical
information and guidance
• Enact tools to help manage
development in hazard
areas (e.g., tax incentives,
information)
• Include retrofitting and
replacement of critical
system elements in capital
improvement plan
• Develop strategy to take
advantage of post-disaster
opportunities
• Warehouse critical
infrastructure components
such as pipe fittings, valves,

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Community Scale Organizational Scale Government Scale
pumps, power line, and road
repair materials
• Solidify supplemental power
supply to tanks and pump
stations (generator
program)
• Develop and adopt a
continuity of operations plan
• Initiate triggers guiding
improvements (such as
<50% substantial damage or
improvements)
• Further enhance seismic risk
assessment to target high
hazard buildings for
mitigation opportunities
• Develop a post-disaster
action plan that includes
grant funding and debris
removal components

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EXTREME

TEMPERATURE
31,567
Population Exposed
Overall Risk Ranking
116 Days
Annually
Temperature Above
90° By Mid-Century

AT RISK

POPULATION
<5yrs 4.4%
65+ 24.2%

8.5%
Persons in
Poverty
Extreme Cold Impacts
Auto Accidents
Health & Safety
Power Outages

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-1

9. EXTREME TEMPERATURE

9.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

9.1.1 Description of the Hazard
Defining the Hazard
Extreme Cold
Extreme cold events refer to a prolonged period of time with extremely cold temperatures.

Further, what is considered an extreme cold event will vary by region. Extreme cold events are when temperatures drop well below the temperatures that are normal in an area.

Depending on what is normal, this may mean temperatures around the freezing point (32 ºF) or below 0 ºF. Freeze events are when temperatures remain below freezing for a sustained period. Temperatures below freezing in Southern California’s generally warm and mild weather regions are rare, but their occurrence can cause life loss and health risks to vulnerable populations.

Extreme Heat
In most of the United States, extreme heat is a long period (2 to 3 days) of high heat and humidity with temperatures above 90° Fahrenheit (F); in California, it is 3 days over 100° F (FEMA Preparedness Community 2024).

Extreme heat often results in the highest number of annual deaths among all weatherrelated hazards. Older adults, children, and sick or overweight individuals are at greater risk from extreme heat. According to the California Climate Adaptation Strategy, heat waves have claimed more lives in California than all other declared disaster events combined. It can take several days of oppressive heat for a heat wave to have a significant or quantifiable impact. Heat waves do not strike victims immediately, but their cumulative effects slowly cause harm to vulnerable populations.

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-2
Cause of the Hazard
Extreme Cold
Extreme cold events are often amplified or caused by a variety of factors, one being polar vortexes (CISA n.d.). Polar vortexes are a large area of low pressure and cold air surrounding both the earth’s poles. It’s a counterclockwise flow of air that keeps colder air near the poles.

Cold air damming may occur, in which low-level cold air mass is trapped topographically.

Often, this cold air is entrenched on the east side of mountainous terrain and often implies that the trapped cold air mass is influencing the dynamics of the overlying air mass.

Extreme Heat
Events of extreme heat, or heat waves, are usually a result of both high temperatures and high relative humidity. Temperature is the measure of how hot or cold something is and humidity is the amount of water vapor in the air. The higher the relative humidity or the more moisture in the air, the less likely that evaporation will take place. This becomes significant when high relative humidity is coupled with soaring temperatures, posing significant risk to human health.

Summary of Potential Impacts
Excessive heat is the primary weather-related cause of death in the United States, claiming over 100 lives each year. In a 30-year record of weather fatalities across the nation (1992 to 2021), excessive heat claimed more lives each year than floods, lightning, tornados, and hurricanes (Erdman 2023). Extreme heat events do not typically impact buildings; however, losses may be associated with the urban heat island effect and overheating of heating, ventilation, and air conditioning systems. These extreme heat events can lead to damage, impact water supplies, and lead to an increase in heat-related illnesses and deaths.

Cascading Hazard Impacts
A cascading impact of extreme heat is poor air quality, which can occur during summer, when stagnant atmospheric conditions trap humid air and pollutants near the ground and closer to residents. Ozone, a major component of smog, is created in the presence of sunlight via reactions between chemicals in gasoline vapors and industrial smokestacks. Hot weather can increase ozone levels. High ozone levels often cause or worsen respiratory problems.

Extreme heat contributes to more severe wildfires in a longer wildfire season and increases the health and safety risk experienced by wildland firefighters and populations near wildfires due to additional reductions in air quality. Wildfire can also further exacerbate worsening air

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-3
quality caused by extreme heat, placing all vulnerable populations at risk of new or worsened respiratory conditions.

Noted in the Drought chapter, extreme heat is also often associated with drought events. The prolonged exposure to extreme heat increases the risk of sunstroke, heat cramps and heat exhaustion to people and animals.

9.1.2 Location
Similar to the occurrence of drought, extreme temperature is a regional phenomenon.

Extreme temperature events would affect the entirety of the area simultaneously and has the potential to impact every person directly or indirectly in the city as well as adversely affect the local economy. Although the Planning Area typically experiences a mild to hot yearround climate, the region is not immune to temperature extremes.

Unseasonal cold snaps may occur due to atmospheric phenomena such as disruptions in the polar vortex or shifts in the jet stream, which can occasionally direct Arctic air masses into Southern California. These events can lead to sudden drops in temperature, particularly affecting communities in higher elevations or inland valleys.

Extreme heat events are often intensified in dense developments of the city. Extensive paved surfaces, limited tree canopy, and industrial activity contribute to urban heat island effect. In these areas, reduced air flow, reduced vegetation, and increased generation of waste heat can contribute to temperatures that are several degrees higher than in surrounding less urbanized areas.

The California Healthy Places Index (HPI): Extreme Heat Edition is a tool developed by the Public Health Alliance in partnership with the UCLA Luskin Center for Innovation. The tool provides datasets on projected heat exposure for California, place-based indicators measuring community conditions, and sensitive populations. It also provides a list of resources and funding opportunities that can be used to address extreme heat.

The tool can be used to:
• Understand the underlying heat vulnerability and resilience characteristics of a community.
• Identify resources to mitigate the adverse effects of extreme heat. • Prioritize public and private investments, resources, and programs.

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-4
The HPI combines 25 community characteristics, based on the social determinants of health, into a single score for each California census tract. Neighborhood-by-neighborhood, the HPI maps data on social conditions that drive health — like education, job opportunities, and clean air and water. The HPI tool evaluates the relationship between 23 identified key drivers of health and life expectancy at birth — which can vary dramatically by neighborhood. Based on that analysis, it produces a score ranking from 1 to 99 that shows the relative impact of conditions in a selected area compared to all other such places in the state. The HPI scores and compares geographies across the state, now with the ability to view data neighborhood-by-neighborhood, providing an even more granular view of community wellbeing. Figure 9-1 shows the HPI Extreme Heat Edition data generated for the City of La Verne.

Source: (Public Health Alliance of Southern California n.d.) Figure 9-1. HPI Extreme Heat Edition Data Outputs for the City of La Verne

9.1.3 Extent
Measuring Intensity
Extreme Cold
Wind chill can also make cold temperatures feel even colder. The Wind Chill Index (Figure 9- 2) is a measure of the rate of heat loss from exposed skin caused by the combined effects of

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-5
wind and cold (NOAA NWS n.d.). The NOAA and NWS chart shows the “Wind Chill Index” as it corresponds to various temperatures and wind speeds.

Source: (NOAA NWS n.d.)
Figure 9-2. NOAA and NWS Wind Chill Index Figure
The severity of extreme cold and freeze can be defined with record lows and in terms of economic losses incurred. Freezing temperatures and frost events can also severely affect the agriculture industry. Freezing temperatures occurring during winter and spring growing seasons can cause extensive crop damage. Secondary impacts of freeze events can include major economic impacts on farmers, farm workers, packers, and shippers of agricultural products. Freezes can also cause significant increases in food prices to the consumer because of shortages, disruption of global agricultural, and food supply chain issues (Masters 2024).

Extreme Heat
In an effort to raise the public’s awareness of the hazards of extreme heat, the NOAA and National Weather Service (NWS) has devised the “Heat Index.” The Heat Index chart, shown on Figure 9-3., uses air temperature and humidity to determine the heat index or apparent temperature. In addition, information regarding the likelihood of health dangers by heat index is presented.

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10 21 -4 -.3S -41 -47 -53 -59 -66 -72
15 25 19 13 6 0 -7 9 -39 -45 -51 -58 -64 -71 -77
20 t 24 17 11 4 -2 -9 22 ·42 ·48 -55 ·61 -68 -74 -81
.t:::. 25 23 16 9 3 --4 -11 24 .44 -51 -58 -64 -71 -78 -84 Q.

E 30 22 15 8 -5 -12 19 -26 -46 -53 -60 -67 -73 -80 -87
"'D 35 21 :'.34 -41 -48 -55 -62 -69 -76 -82 -89
C 21 14 7 0 -7 -14
3: 40 20 13 6 -1 -8 ~22 -36 -43 -50 -S7 -64 -71 -78 -84 -91 45 19 12 5 ·2 -9 -37 -44 -51 ·S8 -65 -72 -79 -86 -93
50 19 12 4 -3 -10 -38 -45 -52 -60 -67 -74 -81 -88 -95
5S 18 11 -3 -11 18 -39 -46 -54 -61 -68 -75 -82 -89 -97
60 • . 33 -40 -48 ·5S -62 -69 ·76 -84 -91 ·98
Fro stbite Times ~ 30minutes D 10minutes D Smin utes
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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-6
Source: (NOAA NWS 2024)
Figure 9-3. NOAA and NWS Heat Index
Legislation was introduced in California in 2021 to create and implement a statewide extreme heat ranking system. Heat-wave ranking would include the projected health impact and meteorological data, such as maximum and minimum temperatures, as well as how long a heat wave is anticipated to persist (California Department of Insurance 2022). The categorization would help communities take measures to reduce the number of heatrelated fatalities (Washington Post 2021).

Warning Time
Meteorologists can accurately forecast the timing and severity of extreme temperature events with several days’ lead time. These forecasts provide an opportunity for public health and other officials to notify vulnerable populations.

Currently, the only way to headline very cold temperatures is with the use of the NWSdesignated Wind Chill Advisory or Warning products. When actual temperatures reach Wind Chill Warning criteria with little to no wind, extreme cold warnings may be issued (NOAA NWS n.d.).

The NWS Heat Risk forecast (Figure 9-4.) provides a quick view of heat risk potential over the upcoming 7 days. The heat risk is portrayed in a numeric (0 – 4) and color (green, yellow,

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NWS Heat Index Temperature (°F)
80 82 84 86 88 90 94 96 98 10
40 80 81 83 85 88 91 97 101 1
45 80 82 84 87 89 93 100 1 -'?ft. 60 81 83 85 88 91 95 - >- 65 81 84 86 89 93 97
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orange, red, magenta) scale, which is similar in approach to the Air Quality Index or the UV Index. It provides one value each day that indicates the approximate level of heat risk concern for any location, along with identifying the groups who are most at risk.

Source: (NOAA NWS 2024)
Figure 9-4. NOAA and NWS Heat Risk
The NWS issues excessive heat watches, excessive heat warnings and heat advisories to warn of extreme heat events within the next 36 hours. If NWS forecasters predict an excessive heat event beyond 36 hours, then the NWS will issue messaging in the form of a special weather statement, emails, and social media in the 3 to 7 day timeframe. The NWS uses the Heat Risk Forecasting System to determine if an excessive heat watch/warning or heat advisory is warranted. The NWS issues the following types of heat-related advisories:
• Heat Advisory —Tied to events where Heat Risk output is on the orange/red (Level 2 – 3) thresholds (orange will not be an automatic heat advisory). • Excessive Heat Watch/Warning—Tied to events where Heat Risk output is on the red/magenta (Level 3 – 4) thresholds.

The NWS issues an excessive heat watch generally 2to 3 days in advance. An excessive heat watch is a way to give the public and emergency officials a warning that extreme temperatures are expected. If significantly hot temperatures remain in the forecast for 24 to

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Category Level
Green 0
Yellow ,
Orange 2
Red
Magenta 4
Meaning
No Elevated Risk
Low Risk for those ,extremely sensitive to
heat. especially those without effective
cooling and/or adequate hydration
Moderate Risk for those who are sensitive
to heat. especially those without effective
cooling and/or adequate hydration
High Risk for much of the population,
especially those who are heat sensitive and
those without effective cooling and/or
adequate hydration
Very High Risk for entire population due to
long duration heat, with little to no relief
overnight
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28 hours, the excessive heat watch will be upgraded to an excessive heat warning, indicating that extreme heat has either arrived or is expected soon.

Worst-Case Scenario
An extreme, multi-year drought associated with record-breaking rates of low precipitation and extreme heat is the worst-case scenario. Combinations of low precipitation and high temperatures could occur over several consecutive years, contributing to drought conditions. Intensified by such conditions, water use could exceed the reserve supply in the Planning Area. If such conditions persisted for several years, the economy of the City could experience setbacks, especially in water dependent industries.

An extreme cold worst-case scenario would involve an unprecedented temperature drop combined with winter storms, bringing sustained freezing temperatures. For a region unaccustomed to harsh extreme cold conditions, these conditions could overwhelm energy infrastructure, leading to widespread and sustained power outages due to frozen pipelines, grid failures, and surging heating demands.

9.1.4 Previous Occurrences
The following sections provide a review of previous extreme temperature occurrences in Los Angeles County.

Declarations
Federal Declarations
There have been 2 federal declarations for extreme temperature for Los Angeles County.

Table 9-1. Federal Disaster Declarations for Extreme Temperature Event Name Disaster Number Declaration Date
Severe Freeze DR-894-CA February 11, 1991
Severe Freeze DR-1689-CA March 13, 2007
Source: (FEMA 2025)
State Proclamations
There have been no state proclamations related to extreme temperature for Los Angeles County.

USDA Declarations
Between 2012 and 2025, USDA included Los Angeles County in 2 declarations relating to extreme temperature.

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Table 9-2. USDA Disaster Proclamations for Extreme Heat Event Description Designation Number Proclamation Date
Freezing temperatures, high winds,
excessive rain S3255 June 19, 2012
Excessive rain, high winds, cold
temperatures, and hail S4170 April 28, 2017
Source: (USDA 2025)
Summary of Recent Significant Events
The NOAA NCEI Storm Events Database did not report events in the Planning Area for extreme cold/wind chill, frost/freeze, or winter weather. Four winter storm events were reported for the eastern range of the San Gabriel Mountain and are presented in Table 9-3.

Table 9-3. Significant Extreme Cold and Freeze Events (2012 – 2025) Event Description Event ID Start Date
Winter storm conditions developed across the eastern range of the San Gabriel Mountains. Above 5000 feet, snowfall totals of 6 to 12 inches were reported. Additionally, southerly winds, gusting up to 67 MPH, were reported.
1091211 March 29, 2023
Winter storm conditions impacted the eastern range of the San Gabriel Mountains. Snowfall totals up to 3 inches were reported along with wind gusts up to 69 MPH.
1164871 February 1, 2024
Winter storm conditions impacted the eastern range of the San Gabriel Mountains in Los Angeles county. Snowfall totals of 1 to 3 feet were reported above 6000 feet along with wind gusts up to 83 MPH.
1164887 February 4, 2024
Significant, late-season, winter storm conditions developed across the eastern range of the San Gabriel Mountains. Mountain High reported 12-16 inches of snowfall while Mount Baldy reported 12-14 inches of snowfall. Along with the snow, southerly winds, gusting in excess of 40 MPH, were reported.
1207154 March 31, 2024
Source: (NOAA 2025)
The NOAA NCEI Storm Events Database did not report events in the Planning Area for extreme heat. The list below describes several recent significant extreme heat events within the Planning Area.
• September 2024 – An extreme heat wave impacted southern California the first week of the month, with daytime temperatures 10° to 20° above normal for that time of year (Figure 9-5). Persistent triple-digit temperatures caused a spike in emergency room visits for heat-related illnesses. Three fires burning in the eastern part of Los Angeles

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County exploded in intensity during this time period, impacting communities with smoke and short-notice evacuations (NOAA 2024).

Figure 9-5. September 2024 Extreme Heat Map
• August 2024 – The La Verne area experienced two multi-day heat events with temperatures over 90° F, with a maximum temperature of 101° F. • July 2024 – A weeklong extreme heat event occurred with temperatures between 90° F to 97° F.
• July/August 2023 – between July 11 and August 2, daytime temperatures only dipped below 90° F one day.
• August 2023 – Two multi-day heat events occurred with temperatures over 90° F, peaking at 102° F.

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Triple-digit daytime heat bakes southern California, Nevada, and Arizona ..

S ptember 6 2 24
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9.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.

Probability
With temperatures expected to increase in the service area because of changing climatic conditions, it is possible that the frequency of extreme cold/freeze events will decline in the future. Cold waves as defined in the NRI dataset do not occur in the City; however, winter weather is reported using these considerations, the annual probability assigned to the extreme cold/freeze hazard is likely low.

The City regularly experiences temperatures in the “danger” and “extreme danger” categories on the NWS the “danger” and “extreme danger” categories on the NWS Heat Index Chart (above 98° F). Climate models, completed by the County of Los Angeles, project that by mid-century, Los Angeles County will experience an average of 9 days of extreme heat per year, growing to 12 days per year by the final decades of the century (LAO 2021). Based on historic events and projected conditions, there is a high probability of occurrence of extreme heat for the Planning Area.

Climate Change
Data projections from Cal-Adapt, a tool provided by the California Energy Commission, were utilized to obtain localized climate change projections as it relates to the hazard of extreme temperature (Cal Adapt 2025). Data suggests that climatic changes may intensify the severity and frequency of extreme temperature events in the Planning Area. The increase in average surface temperatures can also lead to more intense heat waves that can be exacerbated in the City. When comparing average annual temperatures from 1901–1960 to those of 1986 – 2016, most of California has experienced increases exceeding 1°F, with some areas exceeding 2°F (OPR 2022). This general warming trend has the potential to reduce the occurrence and range of anticipated intensities of extreme cold or freeze events in the future.

According to the California HPI: Extreme Heat Edition, the City of La Verne is expected to experience 116.1 days over 90° F during years 2035 to 2064. This figure is expected to increase to 148 days during years 2077 to 2099, a 21.6 percent increase in the number of days experience extreme heat conditions.

Potential Future Impacts
Grid vulnerabilities to potential future heat waves described by climate change projections were assessed throughout Los Angeles County (LAC). Heat waves have posed serious

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challenges to power infrastructure in Southern California, including a major blackout in 2011 and emergency curtailment in 2014, and understanding how future temperature change might impact the power system is critically important for its continued reliable operation.

Potential increases in peak demand, resource adequacy requirements, and component over-loadings were forecast for ranges of scenarios from 2021 to 2060.

Extreme cold events, though less frequent, also present significant risks to grid reliability.

During cold snaps, the demand for heating surges, often relying heavily on natural gas, which is a primary fuel source for electricity generation. A shortage of natural gas during such events could severely limit power generation capacity, leading to blackouts.

9.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

9.2.1 Summary of Vulnerability
The entire Planning Area is exposed to the extreme temperature hazard, so an event has the potential to affect the entire population of 31,567. Extreme heat generally does not impact buildings, but all 9,007 buildings in the Planning Area will have an increased energy demand for cooling and have financial implications, especially to lower income residents and those on a fixed income, due to increased power bills. Extreme heat impacts to transportation lifelines such as bucked tracks on the Metro light rail system in La Verne could cause delays when residents are communing to larger population centers for work, to medical services, or other critical transportation needs. Extreme cold can place significant stress on energy usage and the resulting financial implications. The City of La Verne has not historically had severe prolonged cold events that would cause water pipes to burst. All of the Planning Area’s identified critical facilities, and the entire environment of the Planning Area are vulnerable to the extreme temperature hazard, primarily from potential financial impacts.

9.2.2 Impact on Life, Health, and Safety
Extreme temperatures, both heat and cold, have potential impacts including injury and death. The most vulnerable are those in the Equity Priority Communities discussed below.

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Equity Priority Communities
According to the EPA, those at greater risk to the adverse effects of excessive heat events are individuals with physical or mobility constraints, cognitive impairments, economic constraints, and social isolation. Such populations include the elderly, young children, lowincome people, people with life-threatening illnesses and those who are overweight. Equity Priority Community populations defined in this plan may experience greater impacts from extreme temperature events due to limited access or ability to afford adequate air conditioning or heating at home. Homes that lack proper insulation may be more prone to pipe damage from extreme cold events Power outages during either extreme heat or cold can be life threatening to those dependent on electricity for life support or temperature regulation.

Those experiencing homelessness are particularly vulnerable to extreme heat during the summer when increased humidity keeps nighttime temperatures above 80° F. The cumulative effects over several days of continuous exposure to heat, without relief, put the homeless at serious risk of heat stroke or worse. Similarly, exposure to extreme cold without adequate shelter or heating can lead to hypothermia or frostbite. The table below outlines the number of Equity Priority Community members exposed to extreme temperatures.

Table 9-4. Estimated Number of Total Population and Equity Priority Community Members Exposed to Extreme Temperature
Planning Area
Total Population
Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 6,351 1,420 22.4%
2nd Council District 6,193 0 0.0%
3rd Council District 6,141 0 0.0%
4th Council District 6,085 0 0.0%
5th Council District 6,797 3,926 57.8%
Totals 31,567 5,346 16.9%

9.2.3 Impact on General Building Stock
All of general building stock within the City of La Verne is considered to be exposed to the extreme temperature hazard with varying degrees of vulnerability based on the age and condition of the structures. Extreme heat events can significantly impact the built environment by causing infrastructure damage, increasing energy demand, exacerbating

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urban heat island effects, and posing health risks to residents and workers, necessitating adaptation strategies like green infrastructure and heat-resilient design.

9.2.4 Impact on Community Lifelines
Extreme temperature events can severely impact community lifelines by straining infrastructure, increasing energy demand, and disrupting essential services like healthcare, transportation, and food security, potentially leading to power outages, heat-related illnesses, and economic damage. For example, the Metro light rail track may expand in heat or shrink and break in extreme cold causing delayed transportation or evacuation.

In contrast, the most critical impact of extreme cold or freeze events is not on infrastructure itself, but on human safety and well-being. Prolonged exposure to freezing temperatures can lead to hypothermia, frostbite, and increased mortality. Cold weather can also hinder emergency response, isolate communities, and disrupt access to medical care and essential supplies.

9.2.5 Impact on the Economy
The economic and societal consequences of extreme temperature are pervasive. Impacts encompass reductions in gross domestic product, as workers and infrastructure systems become less productive, as well as wider detrimental effects on well-being, as healthcare outcomes worsen, and people are unable to access outdoor space. Impacts include transitory ones, from people enduring uncomfortable conditions and workers taking sick leave, and enduring losses, for example, due to interruptions to education or property damage from wildfires which can be more severe due to extreme heat’s effect on the environment. Tourism and other leisure activities are also affected as extreme temperature events occur, making walking, shopping, and sightseeing uncomfortable and potentially dangerous. The local economy could experience severe setbacks, particularly in sectors reliant on outdoor labor, transportation, and energy-intensive operations.

According to the Atlantic Council’s Adrienne Arsht Rockefeller Foundation Resilience Center, Extreme heat-related labor productivity losses already affect all regions and sectors of the US economy. Under baseline climate conditions, the United States could lose on average approximately $100 billion annually from heat-induced lost labor productivity.

9.2.6 Impact on Historic and Cultural Resources
Extreme temperature events pose significant threats to historic and cultural resources. High temperatures may accelerate deterioration of materials such as wood, paint, and textiles,

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-15
damaging structures and artifacts. Prolonged heat can also disrupt ecosystems around these sites. On the other hand, extreme cold can cause materials becoming brittle, increasing the risk of breakage and cracking. Cycles of freezing and thawing may introduce moisture into porous materials, causing internal fractures as water freezes and expands.

Buildings with outdated or insufficient insulation are especially vulnerable to burst pipes during cold snaps, which can lead to water damage, mold growth, and structural deterioration. In communities unaccustomed to extreme cold, sudden temperature drops may cause unexpected and severe damage, putting sensitive artifacts and historic structures at heightened risk.

9.2.7 Impact on Ecosystems and Natural Resources
As temperature extremes continue to fluctuate, pre-season freezes and shifts in warming could result in double blooms, premature budding, and early snowmelt which can increase scraggly brush growth and worsen wildfire threats each year (CISA n.d.). Freezing and warming weather patterns create changes in natural processes. An excess amount of snowfall followed by early warming periods may affect natural processes such as flow of water resources. Rising temperatures affect all types of ecosystems through shifts in species distribution and population structure and increase the risk of species extinction.

These changes can impact ecosystem services, such as carbon storage, and affect crop production. Higher temperatures also naturally increase the risk of arid conditions and droughts.

9.3 MITIGATION OPPORTUNITIES
Table 9-5 presents a range of potential opportunities for mitigating the extreme temperature hazard.

Table 9-5. Potential Opportunities to Mitigate the Extreme Temperature Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• Plan trees to create
shade in urban areas
• Remove concrete and
other hard surfaces
and replace them
with native vegetation
• Plant trees in urban
areas experience
urban heat island
effects or with below
average tree canopy
coverage
• Remove concrete and
other hard surfaces
• Plant trees in urban areas experience
urban heat island effects or with below
average tree canopy coverage
• Remove concrete and other hard surfaces
and replace them with native vegetation

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2026 Local Hazard Mitigation Plan | Extreme Temperature 9-16
Community Scale Organizational Scale Government Scale
and replace them
with native vegetation
Reduce Exposure and Vulnerability
• Insulate structures to
provide greater
thermal efficiency
• Provide redundant
power sources
• Install air conditioning
• Relocate critical
infrastructure
underground
• Provide cooling
centers for employees
• Install “cool roofs” and
“green roofs”
• Relocate critical infrastructure
underground
• Trim trees away from power lines
• Install “cool roofs” and “green roofs”
• Establish and promote accessible cooling
centers in the community
• Use the best available technology to
enhance the warning systems for extreme
heat or cold events
Build Local Capacity
• Promote 72-hour selfsufficiency
• Obtain a NOAA
weather radio
• Obtain an emergency
generator
• Provide safety training
and resources for
employees that work
primarily outside and
at field locations
• Create redundancy in
power supply
• Equip facilities with a
NOAA weather radio
• Equip vital facilities
with emergency
backup power
• Enhance public awareness and outreach
to address actions to take during extreme
heat or cold events
• Coordinate severe weather warning
capabilities and the dissemination of
warning among agencies with the highest
degree of capability
• Modify land use and environmental
regulations to support vegetation
management activities that improve
reliability in utility corridors
• Modify landscape and other ordinances to
encourage appropriate planting near
overhead power, cable, and phone lines
• Provide NOAA weather radios to the public
• Review and update heat response plan to
account for climate change projections
• Promote programs that support
community-scale microgrids
• Evaluate and revise building codes to
address and mitigate extreme heat or cold
impacts on residents
Nature-Based Opportunities
• Manage invasive species that thrive in warmer temperatures • Incorporate nature-based heat-reduction measures with plantings in green spaces, trail areas, and community parks

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EXTREME WIND
31,567
Population Exposed
Overall Risk Ranking
Power
Outages
May Trigger
Rapidly Spreads
Wildfires

AT RISK

POPULATION
<5yrs 4.4%
65+ 24.2%

8.5%
Persons in
Poverty

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2026 Local Hazard Mitigation Plan | Extreme Wind
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10. EXTREME WIND

10.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

10.1.1 Description of the Hazard
Defining the Hazard
Windstorms are generally short-duration events involving straight-line winds or gusts of over 50 miles per hour (mph), strong enough to cause property damage. Windstorms are especially dangerous in areas with significant tree stands and areas with exposed property, poorly constructed buildings, mobile homes (manufactured housing units), major infrastructure, and above-ground utility lines. A windstorm can topple trees and power lines, cause damage to residential, commercial and critical facilities, and leave tons of debris in its wake. There are seven types of damaging winds:
• Straight-line winds—Any thunderstorm wind that is not associated with rotation; this term is used mainly to differentiate from tornado winds. Most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft.
• Downdrafts—A small-scale column of air that rapidly sinks toward the ground. • Downbursts—A strong downdraft with horizontal dimensions larger than 2.5 miles resulting in an outward burst or damaging winds on or near the ground. Downburst winds may begin as a microburst and spread out over a wider area, sometimes producing damage similar to a strong tornado. Although usually associated with thunderstorms, downbursts can occur with showers too weak to produce thunder. • Microbursts—A small, concentrated downburst that produces an outward burst of damaging winds at the surface. Microbursts are generally less than 2.5 miles across and short-lived, lasting only 5 to 10 minutes, with maximum wind speeds up to 168 mph. There are two 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.

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• Gust front—A gust front is 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 derecho is a widespread thunderstorm wind caused when new thunderstorms form along the leading edge of an outflow boundary (the boundary formed by horizontal spreading of thunderstorm-cooled air). The word “derecho” is of Spanish origin and means “straight ahead.” Thunderstorms feed on the boundary and continue to reproduce. Derechos typically occur in summer when complexes of thunderstorms form over plains, producing heavy rain and severe wind. The damaging winds can last a long time and cover a large area.
• Bow echo—A bow echo is a linear wind front bent outward in a bow shape. Damaging straight-line winds often occur near the center of a bow echo. Bow echoes can be 200 miles long, last for several hours, and produce extensive damage at the ground.

Santa Ana Winds
In Southern California, strong, dry, gusty downslope winds known as Santa Ana winds form when air from a region of high pressure over the desert region of the southwestern United States flows westward toward low-pressure areas off the California coast (Figure 10-1). As the wind flows over the Sierra Nevada and Santa Ana mountains, it drops from high elevation to sea level. The air becomes compressed and heats up as it sinks, and its relative humidity drops. Gaps in mountains form wind tunnels that strengthen these winds as they pour warm air east to west through the canyons. These winds play a major role in increasing wildfire risk in the region because of the dryness of the winds and the speed with which they can cause a fire to spread, complicating containment efforts.

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Figure 10-1. Santa Ana Winds
Cause of the Hazard
Longer-period windstorms have two main causes: (1) large differences in atmospheric pressure across a region and (2) strong jet stream winds overhead. Horizontal pressure differences may accelerate the surface winds substantially as air travels from a region of higher atmospheric pressure to one of lower.

Santa Ana winds may occur year-round, but are most common during the cooler months, typically from September through March. A Santa Ana wind event can yield sustained winds of 40 miles per hour; isolated wind gusts of over 90 miles per hour have been recorded. Most Santa Ana wind events peak for a 12 to 24 hour period but can persist for a few days.

Summary of Potential Impacts
Windstorms can result in collapsed or damaged buildings, damaged or blocked roads and bridges, damaged traffic signals, streetlights and parks, and other damage. Wind speeds as low as 32 mph can cause structural damage, and winds of 100 mph can actually destroy wood-frame structures. High winds can also cause direct losses to buildings, people, and vital equipment. There are direct consequences to the local economy resulting from windstorms related to both physical damage and interrupted services.

Wind pressure can create a direct and frontal assault on a structure, pushing walls, doors, and windows inward. Conversely, passing winds can create lift and suction forces that act to

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SANTA ANA WINDS
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pull building components and surfaces outward. As positive and negative forces impact a building’s doors, windows, and walls, the result can be roof or building component failures and considerable structural damage. The effects of winds are magnified in the upper levels of multi-story structures.

Debris carried along by extreme winds can contribute directly to loss of life and indirectly to the failure of protective building envelopes. Falling trees and branches can damage buildings, power lines, and other property and infrastructure. Tree limbs breaking in winds of only 45 mph can be thrown over 75 feet, so overhead power lines can be damaged even in relatively minor windstorm events. During wet winters, saturated soils cause trees to become less stable and more vulnerable to uprooting from high winds. Utility lines brought down by summer thunderstorms have also been known to cause fires, which start in dry roadside vegetation. Electric power lines falling down to the pavement create the possibility of lethal electric shock.

Downed trees and power lines, and damaged property also can be major hindrances to emergency response and disaster recovery. Emergency response operations can be complicated when roads are blocked or when power supplies are interrupted. Industry and commerce can suffer losses from interruptions in electric service and from extended road closures.

Tornados, though rare, have occurred in Southern California and can cause localized damage. A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud extending to the ground. Tornadoes are most often generated by severe thunderstorm activity when cool, dry air intersects and overrides a layer of warm, moist air, forcing the warm air to rise rapidly. The damage caused by a tornado is a result of the high wind velocity and wind-blown debris, also accompanied by lightning or large hail. According to the NWS, tornado wind speeds normally range from 40 mph to more than 300 mph (NWS n.d.).

Cascading Hazard Impacts
City of La Verne experiences red flag conditions, where low humidity and high winds combine to create critical fire weather conditions. High winds can quickly cause or spread wildfires, inundating nearby areas with heavy smoke. The conditions not only elevate wildfire risk but also pose significant challenges for emergency response and public safety.

10.1.2 Location
Extreme winds can impact the entire City of La Verne. At the foothills of the San Gabriel Mountains, the city’s topography plays a role in amplifying wind intensity. La Verne’s

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geographic position makes it particularly vulnerable to strong wind patterns, especially during seasonal transitions.

10.1.3 Extent
Measuring Intensity
Damage from such winds accounts for half of all severe weather reports in the lower 48 states. Wind speeds can reach up to 100 mph and can produce a damage path extending for hundreds of miles. The Beaufort Wind Chart in Table 10-1 provides terminology and a description of potential wind impacts at different levels.

Table 10-1. Beaufort Wind Chart
Beaufort
Number
Range
(mph) Terminology Description
0 0 Calm Clam. Smoke rises vertically.
1 1-3 Light air Wind motion visible with smoke.
2 4-7 Light breeze Wind felt on exposed skin. Leave rustle. 3 8-12 Gently breeze Leaves and smaller twigs in constant motion. 4 13-18
Moderate
breeze
Dust and loose paper is raised. Small branches begin to move.
5 19-24 Fresh breeze Smaller trees sway.
6 25-31 Strong breeze
Large branches in motion. Whistling heard in overhead
wires. Umbrella use is difficult.
7 32-38 Near gale
Whole trees in motion. Some difficulty when walking into the wind.
8 39-46 Gale Twigs broken from trees. Car veer on road. 9 47-54 Sever gale Light structure damage.
10 55-63 Storm Trees uprooted. Considerable structural damage. 11 64-73 Violent storm Widespread structural damage.
12 74-95 Hurricane Considerable and widespread damage.

Source: (NWS n.d.)
Warning Time
NOAA issues watch, warning, and advisory information for high winds. Weather stations and media outlets warn residents of upcoming storms so they may prepare and plan accordingly.

Worst-Case Scenario
The worst-case scenario recently occurred in Los Angeles County in January 2025 when wildfires spread rapidly due to extreme winds.

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The Palisades Fire, driven by hurricane-force Santa Ana winds, burned 23,707, killed 12 people, and destroyed 6,837 structures.

The Eaton Fire began on the evening of January 7, 2025, in the Eaton Canyon in the San Gabriel Mountains, and was driven by powerful Santa Ana winds into foothill communities, particularly Altadena. The fire killed at least 17 people and destroyed more than 9,000 buildings.

These examples show how wildfires can spread by high velocity, warm winds. Wind-driven wildfire scenarios could occur within the City of La Verne.

10.1.4 Previous Occurrences
The following sections provide a review of previous extreme wind occurrences in Los Angeles County.

Declarations
Federal Declarations
Between 1954 and 2025, the federal government declared that Los Angeles County experienced four disasters (DR) related to extreme wind.

Table 10-2. Federal Disaster Declarations for Extreme Wind Event Name Disaster Number Declaration Date
Rain/Snow/Wind Storms, Flooding, Mudslides DR-935-CA February 25, 1992 Severe Winter Storms, Straight-Line Winds,
Flooding, Landslides, and Mudslides
DR-4699-CA April 3, 2023
Severe Winter Storms, Tornadoes, Flooding,
Landslides, and Mudslides
DR-4769-CA April 13, 2024
Wildfires and Straight-Line Winds DR-4856-CA January 8, 2025 Source: (FEMA 2025)
State Proclamations
Between 1954 and 2025, California included Los Angeles County in nine state-proclaimed extreme wind disasters.

Table 10-3. State Disaster Proclamations for Extreme Wind Event Name Disaster Number Proclamation Date
High Winds 83-01 March 1983
Windstorms 2000-02 April 1, 2000
Tropical Storm Kay - September 16, 2022

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Event Name Disaster Number Proclamation Date
December 2022 to January 2023
Storms
N-1-23, N-2-23, N-10-23 January 4, 2023
February to March 2023 Storms N-6-23, N-7-23, N-9-23,
N-10-23
March 1, 2023
Tropical Storm Hilary - August 19, 2023
January 2024 Winter Storms - June 21, 2024
Early February 2024 Storms - February 4, 2024
Los Angeles County Fires and
Windstorm Event
N-2-25 through N-24-25 January 7, 2025
Sources: (State of California 2023) (Cal OES 2025)
USDA Declarations
Between 2012 and 2025, the USDA did not include Los Angeles County in any declarations relating to extreme wind.

Summary of Significant Events
The January 2025 high wind events throughout Los Angeles County ranked among the most damaging and deadliest wind-driven wildfire events in California history. See Chapter 13.

Wildfire for additional details.

10.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, are discussed in the sections below.

Probability
The City regularly experiences extreme wind events, especially during the fall and winter months when the Santa Ana winds occur. Based on historic events and projected conditions, there is a high probability of occurrence of extreme wind events in the Planning Area.

Climate Change
It is uncertain whether extreme wind events are becoming more or less frequent under a changing climate. However, impacts from climate change are increasing the intensity and frequence of wildfires which spread quickly by extreme winds.

Potential Future Impacts
The City is surrounded by other incorporated cities so anticipated future growth will be managed through redevelopment, which creates an opportunity to build to a higher code.

The City will be well-equipped to manage development with its building code, and the Safety Element of its General Plan.

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10.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

10.2.1 Summary of Vulnerability
The entire Planning Area may be impacted by the extreme wind hazard, including the entire population of 31,567, all 9,007 buildings and all 141 community lifelines. Historic vulnerabilities and impacts in La Verne have primarily been related to power outages from downed utility lines or Public Safety Power Shutoff (PSPS) events, increased danger of wildfire in the foothills above the City, and downed branches and trees throughout the community.

10.2.2 Impact on Life, Health, and Safety
Damaging winds can cause injuries and fatalities. Downed trees may fall on homes or cars, killing or injuring those inside. Objects that are not secured can be picked up in wind events and become projectiles.

Equity Priority Communities
The entire Equity Priority Community population in La Verne is vulnerable to extreme wind events. The elderly, residents with disabilities, and those experiencing homelessness may be more vulnerable due to slower evacuation times. Residents experiencing poverty may live in older homes that are not built in compliance with modern codes and standards. Power outages from extreme wind events can be life threatening to those dependent on electricity for life support. The table below outlines the number of Equity Priority Community members exposed to extreme wind.

Table 10-4. Estimated Number of Total Population andEquity Priority Community Members Exposed to Extreme Wind
Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 6,351 1,420 22.4%
2nd Council District 6,193 0 0.0%

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Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
3rd Council District 6,141 0 0.0%
4th Council District 6,085 0 0.0%
5th Council District 6,797 3,926 57.8%
Totals 31,567 5,346 16.9%

10.2.3 Impact on General Building Stock
With extreme winds, damages are dependent on factors including wind speed, storm duration, and path of the storm track. Building construction also plays a major role in the extent of damage resulting from an extreme wind event. Due to differences in construction, residential structures are generally more susceptible to wind damage than commercial and industrial structures. Wood and masonry buildings, in general, regardless of their occupancy class, tend to experience more damage than concrete or steel buildings. High-rise buildings are also very vulnerable structures as wind speed normally increases with height above ground level

10.2.4 Impact on Community Lifelines
All community lifelines within the City of La Verne are vulnerable to direct and cascading impacts from extreme wind events. Community lifelines that lack backup power generation capabilities are especially vulnerable. Facilities located near trees or power lines that are likely to fall are vulnerable. Roads and other transportation infrastructure could be blocked by downed trees or other debris.

10.2.5 Impact on the Economy
Extreme winds can cause damage to structure and infrastructure resulting in significant repair or construction costs. Businesses may temporarily close if power is lost due to a wind event.

10.2.6 Impact on Historic and Cultural Resources
Historic structures and those of cultural importance may not be built to standards to withstand extreme winds. These historic and cultural resources may sustain damage, resulting in costly repairs or retrofits keeping in harmony with the original structure.

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10.2.7 Impact on Ecosystems and Natural Resources
Natural resources are highly vulnerable to extreme winds. Natural areas and parks may experience damage to trees and other plants.

10.2.8 Land Uses and Development Trends
New development or redevelopment anywhere in the City of La Verne exposes that development to extreme wind hazards. The safety element of the General Plan establishes standards and plans for the protection of the community from wind hazards. Extreme wind is addressed as part of the combined severe weather hazard in the safety element. The City has established comprehensive policies and actions for land use. Severe weather policies and actions in the general plan that address extreme wind will help to reduce the risk associated with extreme wind hazards for any future development or re-development in La Verne.

10.3 MITIGATION OPPORTUNITIES
Table 10-5 presents a range of potential opportunities for mitigating the extreme wind hazard.

Table 10-5. Potential Opportunities to Mitigate the Extreme Wind Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• None • None • None
Reduce Exposure and Vulnerability
• Provide redundant power
• Plant appropriate trees near
home and power lines
(“Right tree, right place”
National Arbor Day
Foundation Program)
• Relocate critical
infrastructure (such as
power lines) underground
• Reinforce or relocate critical
infrastructure such as power
lines to meet performance
expectations
• Install tree wire
• Harden infrastructure such
as locating utilities
underground
• Trim trees back from power
lines

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Community Scale Organizational Scale Government Scale
Build Local Capacity
• Trim or remove trees that
could affect power lines
• Promote 72 hour selfsufficiency
• Obtain a NOAA weather
radio
• Obtain an emergency
generator
• Trim or remove trees that
could affect power lines
• Create redundancy
• Equip facilities with a NOAA
weather radio
• Equip vital facilities with
emergency power sources
• Support programs such as
“Tree Watch” that proactively
manage problem areas
through use of selective
removal of hazardous trees,
tree replacement, etc.
• Increase communication
alternatives
• Modify land use and
environmental regulations to
support vegetation
management activities that
improve reliability in utility
corridors.
• Modify landscape and other
ordinances to encourage
appropriate planting near
overhead power, cable, and
phone lines
• Provide NOAA weather radios
to the public
Nature-Based Opportunities
• None identified

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FLOOD
31,567
Population Exposed
9,007
Structures Exposed
Overall Risk Ranking
Climate Change
Impacts May
Increase Heavy or
Extreme Rain Events

COMMUNITY

LIFELINES

EXPOSED
6 1
22 32
62 5
13

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11. FLOOD

11.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

11.1.1 Description of the Hazard
Defining the Hazard
Flooding is any overflowing of water onto land that is normally dry, due to rain, ocean waves, or the failure of a dam or levee. Floods are the most common of all weather-related natural disasters. Areas near rivers or streams are at risk from floods during heavy rain or periods of upstream snowmelt. In urban areas, where buildings, highways, driveways, and parking lots reduce the ground’s ability to absorb rainfall, the resulting increase in runoff can overwhelm constructed storm drain systems, resulting in flooding on nearby roads and buildings.

Cause of the Hazard
The severity of a flooding event is typically determined by a combination of several major factors, including stream and river basin topography and physiography; precipitation and weather patterns; recent soil moisture conditions; and the degree of vegetative clearing and impervious surface. Flood events can be brought on by heavy rainfall. The following are several types of flooding presented and defined by California DWR:
• Flash Flooding is a sudden, rapid flooding of low-lying areas typically caused by intense rainfall. Flash floods can also occur from the collapse of a manmade structure.

Rapidly rising water can reach heights of 30 feet or more. • Localized Flooding occurs in both urban and non-urban areas during or after a storm.

Any storm, particularly slow-moving, steady rainstorms, can overwhelm drainage systems. When the system backs up, pooling water can flood streets, yards, and even the lower floors of homes and businesses. Even less intense storms can cause this type of flooding when leaves, sediment, and debris plug storm drains. • Riverine Flooding occurs when rivers, streams, and lakes overflow their banks. This includes flooding caused by levee failure and channel erosion. Areas adjacent to local streams and creeks can also experience flooding as a result of excessive runoff from heavy rainfall and accumulation of water flowing over broad flat areas (DWR 2019).

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The land area susceptible to being inundated or flooded by water from any source (e.g., river, stream, lake, estuary) is referred to as a floodplain. The floodplain includes the floodway and the floodway fringe to convey the flood event and provide flood water storage. These areas form a complex physical and biological system that not only supports a variety of natural resources but also provides natural flood and erosion control. However, not all flooding occurs in such areas. Flash and localized flooding often occurs outside of designated floodplain areas.

Stormwater Runoff Floods
Stormwater flooding (also referred to as pluvial flooding) is a result of local drainage issues and high groundwater levels. If local conditions cannot accommodate intense precipitation through a combination of infiltration and surface runoff, water may accumulate and cause flooding problems. Flooding issues of this nature generally occur within areas with flat gradients, and generally increase with urbanization, which speeds accumulation of floodwaters because of impervious areas. Shallow street flooding can occur unless channels have been improved to account for increased flows.

Urban drainage flooding is caused by increased water runoff due to urban development and drainage systems. Drainage systems are designed to remove surface water from developed areas as quickly as possible to prevent localized flooding on streets and within other urban areas. These systems utilize a closed conveyance system that channels water away from an urban area to surrounding streams, and bypasses natural processes of water filtration through the ground, containment, and evaporation of excess water. Because drainage systems reduce the amount of time surface water takes to reach surrounding streams, flooding in those streams can occur more quickly and reach greater depths than prior to development within that area.

Summary of Potential Impacts
Because they border water bodies, floodplains have historically been popular sites to establish settlements. Human activities tend to concentrate in floodplains for a number of reasons: water is readily available; riverine floodplain land is fertile and suitable for farming; transportation by water is easily accessible; land is flatter and easier to develop; and there is value placed in ocean views. But human activity in floodplains frequently interferes with the natural function of floodplains. It can affect the distribution and timing of drainage, thereby increasing flood problems. Human development can create local flooding problems by altering or confining drainage channels or causing erosion of natural flood protection systems such as dunes. Flood potential can be increased in several ways: reducing a stream’s capacity to contain flows; increasing flow rates or velocities downstream; and

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allowing waves to extend further inland. Human activities can interface effectively with a floodplain as long as steps are taken to mitigate the activities’ adverse impacts on floodplain functions.

Cascading Hazard Impacts
The most problematic secondary hazard for flooding is bank erosion. In many cases, the threat and effects of erosion are worse than actual flooding. This is especially true on the upper courses of rivers where there are steep gradients. Floodwaters in these reaches may pass quickly and without much damage, but scour the banks, edging properties closer to the floodplain or causing them to fall in. Flooding is also responsible for hazards such as landslides when high flows over-saturate soils on steep slopes, causing them to fail.

Hazardous materials spills are also a secondary hazard of flooding if storage tanks rupture and spill into streams, rivers, or drainage sewers.

11.1.2 Location
FEMA defines flood hazard areas through statistical analyses of records of river flow, storm tides, and rainfall; information obtained through consultation with the community; floodplain topographic surveys; and hydrologic and hydraulic analyses. Flood hazard areas are delineated on FIRMs, which are official maps of a community on which the Federal Insurance and Mitigation Administration has delineated special flood hazard areas (SFHAs). The SFHA is the land area on a digital FIRM covered by floodwaters of the “base flood,” which is the flood with a 1 percent chance of occurrence in any given year (also called the 1 percent annual chance flood). Currently, FEMA has designated the City of La Verne as a “Non-SFHA” community, meaning that based on FEMA criteria the flood risk is not sufficient within the City to map as a Special Flood Hazard Area for regulatory purposes under the National Flood Insurance Program (NFIP).

11.1.3 Extent
Measuring Intensity
As noted above, there are no mapped floodplains within the City of La Verne. However, since the City participates in the National Flood Insurance Program, there is flood insurance in force within the City and there have been historic claims paid for flood losses since the City entered the NFIP in 1984.

Repetitive Loss Properties
A repetitive loss property is defined by FEMA as an NFIP-insured property that has experienced at least 2 paid flood losses of more than $1,000 each in any 10-year period since

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1978 (FEMA 2020). The government has instituted programs encouraging communities to identify and mitigate the causes of repetitive losses. Studies have found that many of these properties are outside any mapped 1 percent annual chance (100-year) floodplain. The key identifiers for repetitive loss properties are the existence of flood insurance policies and claims paid by the policies. Although flood loss claims have been paid as noted above, none of these are repetitive loss claims. There are no repetitive loss properties in the City of La Verne.

Warning Time
Due to the sequential pattern of meteorological conditions needed to cause serious flooding, it is unusual for a flood to occur without warning. Warning times for floods can be between 24 and 48 hours. Flash flooding can be less predictable, but potential hazard areas can be warned in advanced of potential flash flooding danger.

Each watershed has unique qualities that affect its response to rainfall. A hydrograph, which is a graph showing stream flow in relation to time, is a useful tool for examining a stream’s response to rainfall. Once rainfall starts falling over a watershed, runoff begins, and the stream begins to rise. Water depth in the stream channel (stage of flow) will continue to rise in response to runoff even after rainfall ends. Eventually, the runoff will reach a peak and the stage of flow will crest. It is at this point that the stream stage will remain the most stable, exhibiting little change over time until it begins to fall and eventually subside to a level below flooding stage.

The potential warning time a community has to respond to a flooding threat is a function of the time between the first rainfall and the first occurrence of flooding. The time it takes to recognize a flooding threat reduces the potential warning time to the time that a community has to take actions to protect lives and property. Another element that characterizes a community’s flood threat is the length of time floodwaters remain above flood stage.

Worst-Case Scenario
Since there are currently no mapped or regulated floodplains within the City of La Verne, a worst-case scenario for this hazard would be any pluvial flooding that occurs within the City that could not be managed with the City’s stormwater/flood control system. These would likely be pluvial flood scenarios where heavy rainfall overwhelms the capacity of urban drainage systems or the ground's ability to absorb water, leading to excess water flowing overland and pooling in low-lying areas. The City of La Verne has a well-established deciduous tree canopy. If an extreme precipitation event were to occur during the autumn when leaves are more prone to build up in street gutters, clogging stormwater infrastructure,

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roadway flooding may impede transportation in the low-lying areas of the City and even be severe enough to impact residential and commercial structures with minor flooding.

Certified flood control structures in the City have been recognized by FEMA and are managed by Los Angeles County. In Los Angeles County, the standard design for stormwater facilities is typically based on a 50-year frequency storm, meaning a rainfall event with a 1/50 probability of being equaled or exceeded in any given year. These could overtop if a worstcase scenario event results in runoff that exceeds standard design.

11.1.4 Previous Occurrences
The following sections provide a review of previous flood occurrences in Los Angeles County which may or may not have had impacts within the City of La Verne.

Declarations
Federal Declarations
Between 1954 and 2024, The federal government declared that Los Angeles County experienced 10 disasters (DR) or emergencies (EM).

Table 11-1. Federal Disaster Declarations for Flood
Event Name
Disaster
Number Event Date(s)
Severe Storms and Flooding DR-253-CA January 26, 1969
Coastal Storms, Mudslides, and Flooding DR-547-CA February 15, 1978 Severe Storms, Mudslides, and Flooding DR-615-CA January 8, 1980 Severe Storms, High Tides, and Flooding DR-812-CA January 17 to 22, 1988 Rain/Snow/Windstorms, Flooding, and Mudslides DR-935-CA February 10 to 18, 1992 Severe Winter Storm, Mud and Land Slides, and Flooding DR-979-CA January 5 to March 20, 1993
Severe Winter Storms, Flooding, Landslides, Mud Flows DR-1044-CA January 10, 1995 Severe Winter Storms, Flooding Landslides, Mud Flow DR-1046-CA March 12, 1995 Severe Winter Storms and Flooding DR-1203-CA February 9, 1998 Severe Storms, Flooding, Debris Flows, and Mudslides DR-1577-CA February 4, 2005 Severe Storms, Flooding, Landslides, and Mud and Debris Flows DR-1585-CA April 14, 2005
Severe Winter Storms, Flooding, and Debris and Mud
Flows DR-1884-CA March 8, 2010
Severe Winter Storms, Flooding, and Mudslides DR-4305-CA January 18 to 23, 2017 Severe Winter Storms, Flooding, Landslides, and
Mudslides
DR-4683-CA December 27, 2022, to
January 31, 2023

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Event Name
Disaster
Number Event Date(s)
Severe Winter Storms, Flooding, Landslides, and
Mudslides
EM-3592-CA March 9 to July 10, 2023
Severe Winter Storms, Flooding, and Mudslides EM-3591-CA January 8 to 31, 2023 Severe Winter Storms, Straight-Line Winds, Flooding,
Landslides, and Mudslides DR-4699-CA April 3, 2023
Severe Winter Storms, Tornadoes, Flooding, Landslides,
and Mudslides DR-4769-CA April 13, 2024
Source: (FEMA 2025)
State Proclamations
Between 1954 and 2024, California included Los Angeles County in 17 state-proclaimed flood disasters.

Table 11-2. State Disaster Proclamations for Flood
Event Name Disaster Number Proclamation Date
Potential Flood Damage and Landslides as a
Result of Fires 59-01 January 8, 1959
Flood and Rainstorm DR-122
February 16, 1962;
February 23, 1962
Flooding Causing Landslides - January 5, 1965
1969 Storms DR-253 January 23, 1969
1978 Winter Storms DR-547 February 27, 1978
1980 Winter Storms DR-615 February 7, 1980
1982 to 1983 Floods (DR-677), 82-18
December 8, 1882, to
March 21, 1883
1992 Winter Storms (DR-935), 92-01 February 12, 1992
1995 Winter Storms (DR-1044), 95-02 January 6 to 11, 1995 1995 Severe Winter Storms (DR-1044), 95-01, 95-02,
95-03, 95-04
January 6 to March 14, 1995
2001 March Storms 2001-01 March 1, 2001
2005 January Winter Storms (DR-1577), 2005-01, 2005-
02 January 12, 2005
2005 to 2006 Winter Storms (DR-16-28), 2006-01 January 12, 2006 December 2022 to January 2023 Storms N-1-23, N-2-23, N-10-23 January 4, 2023 Tropical Storm Hilary - August 19, 2023
January 2024 Winter Storms - June 21, 2024
Early February 2024 Storms - February 4, 2024
Sources: (State of California 2023) (Cal OES 2025)

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Summary of Significant Events
There are no known significant flood events within the City of La Verne. Creeks flow through the City in canyons, then into debris basins, which outlet into concrete channels and from there into a reservoir/lake with a controlled outlet structure. A secondary creek in the West Marshall Canyon, has experienced some flooding and debris flows.

Recent Events
There are no recent flood events of note within the City of La Verne.

11.1.5 Future Conditions
Future hazard conditions, including frequency and severity of future events, is discussed in the sections below.

Probability
The frequency and severity of fluvial flooding for river systems are based on “discharge probability.” The discharge probability is the probability that a certain river discharge (flow) level will be equaled or exceeded in a given year. Flood studies use historical records to determine the probability of occurrence for different discharge levels. These measurements reflect statistical averages only; it is possible for multiple floods with a low probability of occurrence (such as a 1 percent annual chance flood) to occur in a short time period. A single flood event can have flows at different points on a river or stream that correspond to different probabilities of occurrence.

For pluvial flooding, the probability can be associated with the design storms from which stormwater facilities are designed to convey. In the Los Angeles County Planning Area, the standard design storm for stormwater facilities is typically based on a 50-year frequency design storm, meaning a rainfall event with a 1/50 probability of being equaled or exceeded in any given year.

Climate Change
Climate change is playing a significant role in the increasing frequency and intensity of extreme weather events, particularly floods. According to scientific reports, as global temperatures rise, the hydrological cycle becomes more dynamic and unpredictable.

Warmer air holds more moisture, which often leads to heavier and more intense rainfall. This accelerates the risk of flooding, as seen in numerous impactful events around the world.

Additionally, the shift in weather patterns caused by climate change contributes to prolonged periods of drought in some regions, further exacerbating water-related challenges.

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Use of historical hydrologic data has long been the standard of practice for designing and operating water supply and flood protection projects. For example, historical data are used for flood forecasting models and to forecast snowmelt runoff for water supply. This method of forecasting assumes that the climate of the future will be similar to that of the period of historical record. However, the hydrologic record cannot be used to predict changes in frequency and severity of extreme climate events such as floods. Scientists project greater storm intensity with climate change, resulting in more direct runoff and flooding. High frequency flood events in particular will likely increase with a changing climate. What is currently considered a 1 percent annual chance also may strike more often, leaving many communities at greater risk. Going forward, model calibration must happen more frequently, new forecast-based tools must be developed, and a standard of practice that explicitly considers climate change must be adopted.

Climate change is already impacting water resources, and resource managers have observed the following:
• Historical hydrologic patterns can no longer be solely relied upon to forecast the water future.
• Precipitation and runoff patterns are changing, increasing the uncertainty for water supply and quality, flood management and ecosystem functions. • Extreme climatic events will become more frequent, necessitating improvement in flood protection, drought preparedness and emergency response.

The amount of snow is critical for water supply and environmental needs, but so is the timing of snowmelt runoff into rivers and streams. Rising snowlines caused by climate change will allow more mountain areas to contribute to peak storm runoff. Changes in watershed vegetation and soil moisture conditions will likewise change runoff and recharge patterns. As stream flows and velocities change, erosion patterns will also change, altering channel shapes and depths, possibly increasing sedimentation behind dams, and affecting habitat and water quality. With potential increases in the frequency and intensity of wildfires due to climate change, there is potential for more floods following fire, which increase sediment loads and water quality impacts.

Potential Future Impacts
According to the California Department of Finance, the population of the greater Los Angeles County region is expected to increase over the next 45 years. The City has limited potential for expansion through annexation, as it is surrounded by other incorporated cities. It is anticipated that future growth in the City will be managed through redevelopment, which

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creates an opportunity to correct past land use decisions, especially with regards to development within floodplains.

While regulated floodplains for the City have not been clearly identified, the City will be wellequipped to manage growth in floodplains with its flood damage prevention ordinance, its building code, and the Safety Element of its General Plan. Proper application of these tools requires accurate hazard mapping. Flood mapping should be taken into account as future land use decisions are made for areas impacted by flooding.

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11.2 VULNERABILITY ASSESSMENT
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(ii) The plan must include a description of the jurisdiction’s vulnerability to the hazards of concern and include an overall summary of the hazard’s impact on the community. The impacts need to include the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the hazard areas, and estimate of potential dollar losses to vulnerable structures, and a description of land uses and development trends.

11.2.1 Summary of Vulnerability
Since the City has been designated as a non-SFHA community, there is no flood extent and location data available to perform a quantitative risk assessment of the flood hazard. Since there are dam failure inundation areas within this City, residual flood risk may result from dam failure inundation. See the Dam Failure chapter for more information on that hazard.

Since there are no FEMA-mapped flood zones in the City of La Verne, a Hazus analysis could not be performed. Flood risk in the City is currently limited to urban drainage which is not mapped by FEMA. Therefore, the following sections provide a qualitative assessment of flood risk in the City of La Verne.

11.2.2 Impact on Life, Health, and Safety
Floods present threats to public health and safety. Floodwater is generally contaminated by pollutants such as sewage, human and animal feces, pesticides and insecticides, fertilizers, oil, asbestos, and rusting building materials. The following health and safety risks are commonly associated with flood events:
• Unsafe food — Floodwaters contain disease-causing bacteria, dirt, oil, human and animal wastes, and farm and industrial chemicals. They carry away whatever lies on the ground and upstream. Their contact with food items, including food crops in agricultural lands, can make that food unsafe to eat and hazardous to human health.

Power failures caused by floods damage stored food. Refrigerated and frozen foods are affected during the outage periods, and thus must be carefully monitored and examined prior to consumption. Foods kept inside cardboard, plastic bags, jars, bottles, and paper packaging are subject to disposal if contaminated by floodwaters.

Even though the packages do not appear to be wet, they may be unhygienic with mold contamination and deteriorate rapidly.

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• Contaminated drinking/washing water and poor sanitation—Flooding impairs clean water sources with pollutants and affects sanitary toilets. Direct and indirect contact with the contaminants—whether through direct food intake, vector insects such as flies, unclean hands, or dirty plates and utensils—can result in waterborne infectious disease. Wastewater treatment plants, if flooded and caused to malfunction, can be overloaded with polluted runoff waters and sewage beyond their disposal capacity, resulting in backflows of raw sewage to homes and low-lying grounds. Private wells can be contaminated or damaged severely by floodwaters, while private sewage disposal systems can become a cause of infection and illnesses if they are broken or overflow. Unclean drinking and washing water and sanitation, coupled with lack of adequate sewage treatment, can lead to disease outbreaks, including lifethreatening cholera, typhoid, dysentery, and some forms of hepatitis. • Mosquitoes and animals — Prolonged rainfall and floods provide new breeding grounds for mosquitoes—wet areas and stagnant pools—and can lead to an increase in the number of mosquito-borne diseases such as malaria and dengue and West Nile fevers. Rats and other rodents and wild animals also can carry viruses and diseases.

The public should avoid such animals and should dispose of dead animals in accordance with guidelines issued by local animal control authorities. • Molds and mildews — Excessive exposure to molds and mildews can cause flood victims—especially those with allergies and asthma—to contract upper respiratory diseases and to trigger cold-like symptoms such as sore throat, watery eyes, wheezing and dizziness. Molds grow in as short a period as 24 to 48 hours in wet and damp areas of buildings and homes that have not been cleaned after flooding, such as waterinfiltrated walls, floors, carpets, toilets, and bathrooms. Very small mold spores can be easily inhaled by human bodies and, in large enough quantities, cause allergic reactions, asthma episodes, and other respiratory problems. Infants, children, elderly people and pregnant women are considered most vulnerable to mold-induced health problems.
• Carbon monoxide poisoning—Carbon monoxide poisoning is a potential hazard after major floods. Carbon monoxide can be found in combustion fumes, such as those generated by small gasoline engines, stoves, generators, lanterns and gas ranges, or by burning charcoal or wood. In the event of power outages following floods, flood victims tend to use alternative sources of fuels for heating, cooling, or cooking inside enclosed or partly enclosed houses, garages or buildings without an adequate level of air ventilation. Carbon monoxide builds up from these sources and poisons the people and animals inside.

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• Hazards when reentering and cleaning flooded homes and buildings — Flooded buildings can pose health hazards after floodwaters recede. Electrical power systems can become hazardous. People should avoid turning on or off the main power while standing in floodwater. Gas leaks from pipelines or propane tanks can trigger explosion when entering and cleaning damaged buildings or working to restore utility service. Flood debris—such as broken bottles, wood, stones, and walls—may cause wounds and injuries when cleaning damaged buildings. Containers of hazardous chemicals, including pesticides, insecticides, fertilizers, car batteries, propane tanks and other industrial chemicals, may be hidden or buried under flood debris. A health hazard can also occur when hazardous dust and mold in ducts, fans and ventilators of air-conditioning and heating equipment are circulated through a building and inhaled by those engaged in cleanup.
• Mental stress and fatigue — Exposure to extreme disaster events can cause psychological distress. Having experienced a devastating flood, seen loved ones lost or injured, and homes damaged or destroyed, flood victims can experience long-term psychological impact. The expense and effort required to repair flood-damaged homes places severe financial and psychological burdens on the people affected, in particular the unprepared and uninsured. Post-flood recovery—especially when prolonged—can cause anxiety, anger, depression, lethargy, hyperactivity, sleeplessness, and, in an extreme case, suicide. Behavior changes may also occur in children. There is also a long-term concern among the affected that their homes can be flooded again in the future.

Equity Priority Communities
In the City of La Verne, low-income populations and individuals with limited English proficiency may be more vulnerable to flood hazards. Low-income residents have less resources to prepare for or recover from flooding and may face housing instability after a disaster.

Flooding is associated with contaminated water, the spread of diseases, and carbon monoxide poisoning related to power outages. People with limited English proficiency may face greater vulnerability to health disparities due to lack of information in their language.

The table below outlines the number of Equity Priority Community members who may be exposed to flood hazards.

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Table 11-3. Estimated Number of Equity Priority Community Members Exposed to Flood Hazards Planning Area Total Population Exposed
Total EPC Population
Exposed
EPC % of
Total Population Exposed
1st Council District 6,351 1,420 22.4%
2nd Council District 6,193 0 0.0%
3rd Council District 6,141 0 0.0%
4th Council District 6,085 0 0.0%
5th Council District 6,797 3,926 57.8%
Totals 31,567 5,346 16.9%

11.2.3 Impact on General Building Stock
“If it can rain where you live, it can flood where you live.” (Dr. Rick Knabb, the Weather Channel, 2019). This is especially true for pluvial flood conditions that rely on management systems to convey stormwater up to design capacities. When rainfall runoff exceeds design capacities, flooding may occur. Based on this premise, all 9,007 structures in the city could be susceptible to flooding under certain conditions. A recent analysis by the nonprofit First Street Foundation found the United States to be woefully underprepared for damaging floods. The report identified “around 1.7 times the number of properties as having substantial risk,” compared with FEMA’s designation (Insurance Information Institute, Resilience Blog, March 2025). According to the First Street Foundation, this equates to a total of 14.6 million properties across the country at substantial risk, of which 5.9 million property owners are currently unaware of or underestimating the risk they face.

11.2.4 Impact on Community Lifelines
Like general building stock, all community lifelines could be susceptible to pluvial flood conditions under certain conditions.

11.2.5 Impact on the Economy
Pluvial flooding, or flooding caused by heavy rainfall, can lead to significant economic impacts, including damage to infrastructure, businesses, and property, as well as disruptions to transportation and supply chains. The unpredictability of pluvial flooding makes it especially hazardous, often giving communities little time to prepare. They also pose risks to infrastructure, such as roadways and power grids, and can cause significant economic losses.

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11.2.6 Impact on Historic and Cultural Resources
Floods can significantly impact cultural and historic resources, causing damage or destruction to buildings, artifacts, and landscapes, potentially leading to the loss of irreplaceable cultural heritage and historical knowledge.

11.2.7 Impact on Ecosystems and Natural Resources
Floods can have both positive and negative impacts on ecosystems and natural resources, including habitat destruction, erosion, water contamination, and changes to soil fertility, while also potentially recharging groundwater and creating new habitats. Seasonal floods can renew ecosystems, providing life-giving waters in more ways than one. Floods transport vital nutrients, such as nitrogen, phosphorus, and organic material, to the surrounding land.

When the water recedes, it leaves sediment and nutrients behind on the floodplain. These types of benefits are not typically seen in urban areas experience pluvial flood conditions like the City of La Verne.

11.2.8 Land Uses and Development Trends
New development or redevelopment anywhere in areas prone to flooding exposes that development to the flood hazard. The safety element of the General Plan establishes standards and plans for the protection of the community from flood hazards. The City has established comprehensive policies and actions for land use in flood hazard areas. Floodrelated policies and actions in the general plan will help to reduce the flood risk for any future development or re-development in La Verne.

11.3 MITIGATION OPPORTUNITIES
Table 11-4 presents a range of potential opportunities for mitigating the flood hazard.

Table 11-4. Potential Opportunities to Mitigate the Flood Hazard Community Scale Organizational Scale Government Scale
Manipulate the Hazard
• Clear storm drains and
culverts
• Use low-impact
development
techniques
• Clear storm drains and
culverts
• Use low-impact
development techniques
• Maintain drainage systems
• Institute low-impact development
techniques on property
• Structural flood control, levees,
channelization, or revetments
• Stormwater management
regulations and master planning

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Community Scale Organizational Scale Government Scale
• Acquire vacant land or promote
open space uses in developing
watersheds to control increases in
runoff
Reduce Exposure and Vulnerability
• Locate outside of
hazard area
• Elevate utilities above
base flood elevation
• Use low-impact
development
techniques
• Raise structures above
base flood elevation
• Elevate items within
house above base
flood elevation
• Build new homes
above base flood
elevation
• Flood-proof structures
• Locate outside of hazard
area
• Use low-impact
development techniques
• Build critical function
redundancy or retrofit
critical buildings
• Provide floodproofing
when new critical
infrastructure must be
located in floodplains
• Locate or relocate critical facilities
outside of hazard area
• Acquire or relocate identified
repetitive loss properties
• Promote open space uses in
identified high hazard areas via
techniques such as: planned unit
developments, easements, setbacks,
greenways, sensitive area tracks
• Adopt land development criteria
such as planned unit developments,
density transfers, clustering Institute
low impact development techniques
on property
• Acquire vacant land or promote
open space uses in developing
watersheds to control increases in
runoff
• Harden infrastructure, bridge
replacement program
• Provide redundancy for critical
functions and infrastructure
• Adopt regulatory standards such as
freeboard standards, cumulative
substantial improvement or
damage, lower substantial damage
threshold, compensatory storage,
non-conversion deed restrictions
• Stormwater management
regulations and master planning
• Adopt “no-adverse impact”
floodplain management policies that
strive to not increase the flood risk on
downstream communities
• Improve unpaved roads to reduce
their likelihood to fail due to flooding
Build Local Capacity

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Community Scale Organizational Scale Government Scale
• Buy flood insurance
• Develop household
plan, such as retrofit
savings,
communication with
outside, 72 hour selfsufficiency during and
after an event
• Keep cash reserves for
reconstruction
• Support and implement
hazard disclosure for sale
of property in risk zones
• Solicit cost-sharing
through partnerships on
projects with multiple
benefits
• Produce better hazard maps
• Provide technical information and
guidance
• Enact tools to help manage
development in hazard areas
(stronger controls, tax incentives,
and information)
• Incorporate retrofitting or
replacement of critical system
elements in capital improvement
plan
• Develop strategy to take advantage
of post-disaster opportunities
• Warehouse critical infrastructure
components
• Develop and adopt a continuity of
operations plan
• Consider participation in the
Community Rating System
• Maintain and collect data to define
risks and vulnerability
• Train emergency responders
• Create an elevation inventory of
structures in the floodplain
• Develop and implement a public
information strategy
• Charge a hazard mitigation fee
• Integrate floodplain management
policies into other planning
mechanisms within the Planning
Area.
• Consider impacts of climate change
on the risk associated with the flood
hazard
• Consider the residual risk associated
with structural flood control in future
land use decisions
• Enforce National Flood Insurance
Program
• Adopt a Stormwater Management
Master Plan
Nature-Based Opportunities

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Community Scale Organizational Scale Government Scale
• Restore and reconnect floodplains that have been degraded by development and structural flood control
• Use soft approaches for stream bank restoration and hardening • Set back levees on systems that rely on levee protection to allow the channel to meander, which reduces erosion and scour potential
• Preserve floodplain storage capacity by limiting or prohibiting the use of fill in the floodplain • Incorporated green infrastructure into stormwater management facilities • Protect and/or restore riparian buffers

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LANDSLIDE
Very High, High & Moderate
Hazard Zones

COMMUNITY

LIFELINES

EXPOSED
1 1
3 11
6,180
Population Exposed
1,971
Number of
Structures Exposed
Overall Risk Ranking
$1.32 B
Value of Structures
& Contents Exposed

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12. LANDSLIDE

12.1 HAZARD PROFILE
Local Plan Requirement B1 – 44 CFR Part 201.6(c)(2)(i)
Include a description of the type, location, and extent for the identified hazards of concern and include information on previous occurrences of hazard events and the probability of future hazard events.

12.1.1 Description of the Hazard
Defining the Hazard
A landslide is the downward and outward movement of slope‐forming soil, rock, and vegetation driven by gravity. Both natural and human-induced changes in the environment can trigger landslides. The following are the several types of landslides:
• Rock falls are rapid movements of bedrock, which result in bouncing or rolling. • Topple is a section or block of rock that rotates or tilts before falling to the slope below. • Slides are movements of soil or rock along a distinct surface of rupture, which separates the slide material from the more stable underlying material. • Mudflows, sometimes referred to as mudslides, mudflows, lahars, or debris avalanches, are fast‐moving rivers of rock, earth, and other debris saturated with water. They develop when water rapidly accumulates in the ground, such as heavy rainfall or rapid snowmelt, changing the soil into a flowing river of mud or “slurry.” • Slurry can flow rapidly down slopes or through channels and can strike with little or no warning at avalanche speeds. Slurry can travel several miles from its source, growing larger as it picks up trees, cars, and other materials along the way. As the flows reach flatter ground, the mudflow spreads over a broad area where it can accumulate in thick deposits.
• Creep is the imperceptibly slow downward movement of slope forming rock or soil that can be accelerated during wet weather events or earthquakes.

Cause of the Hazard
Landslides are caused by a combination of geological and climate conditions and the influence of urbanization. They can be initiated by storms, earthquakes, fires, volcanic eruptions, or human modification of the land. Vulnerable natural conditions are affected by

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human development and the infrastructure that supports it. In some cases, irrigation increases the landslide potential. The following factors can contribute to slide formation:
• Change in slope of the terrain
• Increased load on the land
• Shocks and vibrations
• Change in water content
• Groundwater movement
• Frost action
• Weathering of rocks
• Removing or changing
• The type of vegetation covering slopes
Areas that are generally prone to landslide hazards include previous landslide areas, the bases of steep slopes, the bases of drainage channels, and developed hillsides where leach‐ field septic systems are used. Areas that are typically considered safe from landslides include areas that have not moved in the past, relatively flat‐lying areas away from sudden changes in slope, and areas at the top or along ridges set back from the tops of slopes.

While small landslides are frequently a result of human activity, the largest landslides are often naturally occurring phenomena with little or no human contribution. The sites of large landslides are typically areas of previous landslide movement that are periodically reactivated by significant precipitation or seismic events.

Summary of Potential Impacts
Landslides in hillside terrain can pose serious hazard to downslope property and structures.

They can disrupt roadways and other infrastructure lifelines, destroy private property, and cause flooding, bank erosion, and rapid channel migration. A slide can move rapidly down slopes or through channels and can strike with little or no warning. It can travel miles from its source, growing as it descends, picking up trees, boulders, cars, and anything else in its path.

Although slides behave as fluids, they convey many times the hydraulic force of water due to the mass of material they carry.

In spite of their destructive potential, landslides can serve beneficial functions to the natural environment. They supply sediment and large wood to the channel network and can contribute to complexity and dynamic channel behavior critical for aquatic and riparian ecological diversity.

Cascading Hazard Impacts
Landslides that block rivers or streams can contribute to flooding.

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12.1.2 Location
The City of La Verne also has areas with land movement (landslide and debris flow) potential.

These areas are primarily in the northern foothills of the city. In 2011, the California Geological Survey conducted a statewide analysis using a combination of regional rock strength and slope data to create classes of susceptibility to deep-seated landslides. The analysis assumed, in general, that susceptibility to deep-seated landslides is low on very low slopes in all rock materials and increases with slope and in weak rocks. The analysis also factored in locations of past landslides. Figure 12-1 shows deep-seated landslide susceptibility classes (none, low, moderate, high, and very high).

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Figure 12-1. Landslide Susceptibility

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12.1.3 Extent
Measuring Intensity
Landslides are typically a function of soil type and steepness of slope. Soil type is a key indicator for landslide potential and is used by geologist and geotechnical engineers to determine soil stability for construction standards. In general, landslide hazard areas are where the land has characteristics that contribute to the risk of the downhill movement of material, such as the following:
• A slope greater than 33 percent
• Post-wildfire areas
• A history of landslide activity or
movement during the last 10,000
years
• Stream or wave activity, which has
caused erosion, undercut a bank or
cut into a bank to cause the
surrounding land to be unstable
• The presence or potential for snow
avalanches
• The presence of an alluvial fan,
indicating vulnerability to the flow of
debris or sediments
• The presence of impermeable soils,
such as silt or clay, mixed with
granular soils, such as sand or
gravel
The best predictor of where slides might occur is the location of past movements. Past landslides can be recognized by their distinctive topographic shapes, which can remain in place for thousands of years. Most landslides recognizable in this fashion range from a few acres to several square miles. Most show no evidence of recent movement and are not currently active. A small proportion of them may become active in any given year, with movements concentrated within all or part of the landslide masses or around their edges.

The recognition of ancient dormant landslide sites is important in the identification of areas susceptible to flows and slides because they can be reactivated by earthquakes or by exceptionally wet weather. Also, because they consist of broken materials and frequently involve disruption of groundwater flow, these dormant sites are vulnerable to constructiontriggered sliding.

Warning Time
Landslides can occur suddenly or slowly. The velocity of slide may range from a slow creep of inches per year to many feet per second, depending on slope angle, material, and water content. Generally accepted warning signs for landslide activity include the following:
• Springs, seeps, or saturated ground in areas that have not typically been wet before

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• New cracks or unusual bulges in the ground, street pavements, or sidewalks • Soil moving away from foundations
• Ancillary structures such as decks and patios tilting or moving relative to the main house
• Tilting or cracking of concrete floors and foundations • Broken water lines and other underground utilities
• Leaning telephone poles, trees, retaining walls or fences • Offset fence lines
• Sunken or down-dropped road beds
• Rapid increase in creek water levels, possibly accompanied by increased turbidity (soil content)
• Sudden decrease in creek water levels though rain is still falling or just recently stopped
• Sticking doors and windows and visible open spaces indicating frames out of plumb • A faint rumbling sound that increases in volume as the landslide nears • Unusual sounds, such as trees cracking or boulders knocking together Some methods used to monitor landslides can provide an idea of the type of slide and the amount of time prior to failure. Assessing the geology, vegetation, and amount of predicted precipitation for an area can help in predictions of what areas are at risk during general time periods. Currently, there is no practical warning system for individual landslides, however. The standard operating procedure is to monitor situations on a case-by-case basis and respond after an event has occurred.

Worst-Case Scenario
The worst-case scenario for landslide hazards in the Planning Area would generally correspond to a severe storm with heavy rain that caused flooding in an area that had been burned by fire. Landslides are more likely during the late winter when the water table is high.

After heavy rains from November to December, soils become saturated with water. As water seeps downward through upper soils that may consist of permeable sands and gravels and as it accumulates on impermeable silt, it will weaken and destabilize the slope. A short intense storm could cause saturated soil to move, resulting in landslides. As rains continue, the groundwater table rises, adding to the weakening of the slope. Gravity, poor drainage, a rising groundwater table, and poor soil exacerbate hazardous conditions.