26-604 - Resolution — Fresno City Council, May 21, 2026 (part 1 of 3)

Fresno County, California
Hazard
Mitigation Plan
2024
Exhibit A

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024 1

1. Introduction

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024

2 PURPOSE
Fresno County, along with 17 participating jurisdictions, prepared this local multi-jurisdictional hazard mitigation plan to better protect the people and property of the County from the effects of hazard events. This plan underwent a comprehensive update in 2023-2024 building upon the plan that was originally developed in 2009. This plan demonstrates the community’s commitment to reducing risks from hazards and serves as a tool to help decision makers direct mitigation activities and resources.

This plan was also developed to make Fresno County and participating jurisdictions eligible for certain federal disaster assistance, specifically, the Federal Emergency Management Agency’s (FEMA) Hazard Mitigation Grant Program (HMGP), Pre-Disaster Mitigation (PDM) program, and Flood Mitigation Assistance (FMA), and Building Resilient Infrastructure and Communities (BRIC). This plan also meets the planning requirements of the National Flood Insurance Program’s Community Rating System (CRS).

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024

3 BACKGROUND AND SCOPE
Each year in the United States, natural disasters take the lives of hundreds of people and injure thousands more. Nationwide, taxpayers pay billions of dollars annually to help communities, organizations, businesses, and individuals recover from disasters. These monies only partially reflect the true cost of disasters because additional expenses to insurance companies and nongovernmental organizations are not reimbursed by tax dollars. Many natural disasters are predictable, and much of the damage caused by these events can be alleviated or even eliminated through planned mitigation.

Hazard mitigation is defined by FEMA as “any sustained action taken to reduce or eliminate long- term risk to human life and property from a hazard event.” The results of a three-year, congressionally mandated independent study to assess future savings from mitigation activities provide evidence that mitigation activities are highly cost-effective. Natural hazard mitigation saves $6 on average for every $1 spent on federal mitigation grants, according to an analysis by the National Institute of Building Sciences. An earlier (2005) study by NIBS found a benefit-cost ratio (BCR) of 4:1. \ Hazard mitigation planning is the process through which hazards that threaten communities are identified, likely impacts of those hazards are determined, mitigation goals are set, and appropriate strategies to lessen impacts are determined, prioritized, and implemented. This plan documents Fresno County’s hazard mitigation planning process identifies relevant hazards and vulnerabilities and provides strategies the County and participating jurisdictions will use to decrease vulnerability and increase resiliency and sustainability in Fresno County.

The Fresno County Multi-Jurisdictional Hazard Mitigation Plan is a multi-jurisdictional plan that geographically covers everything within Fresno County’s jurisdictional boundaries (hereinafter referred to as the planning area). Unincorporated Fresno County and the following communities and special districts participated in the planning process:
▪ City of Clovis
▪ City of Coalinga
▪ City of Firebaugh
▪ City of Fowler
▪ City of Fresno
▪ City of Kerman
▪ City of Kingsburg
▪ City of Mendota
▪ City of Reedley
▪ City of San Joaquin
▪ City of Sanger
▪ City of Selma
▪ Fresno Metropolitan Flood Control District
▪ Kings River Conservation District
▪ Lower San Joaquin Levee District
▪ Sierra Resource Conservation District/Highway 168 Fire Safe Council ▪ Westlands Water District

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024

4 This plan was prepared pursuant to the requirements of the Disaster Mitigation Act of 2000 (Public Law 106-390) and the implementing regulations set forth by the Interim Final Rule published in the Federal Register on February 26, 2002, (44 CFR §201.6) and finalized on October 31, 2007. (Hereafter, these requirements, and regulations will be referred to collectively as the Disaster Mitigation Act.) While the act emphasized the need for mitigation plans and more coordinated mitigation planning and implementation efforts, the regulations established the requirements that local hazard mitigation plans must meet for a local jurisdiction to be eligible for certain federal disaster assistance and hazard mitigation funding under the Robert T. Stafford Disaster Relief and Emergency Act (Public Law 93-288).

Because the Fresno County planning area is subject to many kinds of hazards, access to these programs is vital.

Information in this plan will be used to help guide and coordinate mitigation activities and decisions for local land use policy in the future. Proactive mitigation planning will help reduce the cost of disaster response and recovery to communities and their residents by protecting critical community facilities, reducing liability exposure, and minimizing overall community impacts and disruptions. The Fresno County planning area has been affected by hazards in the past and is thus committed to reducing future impacts from hazard events and becoming eligible for mitigation- related federal funding.

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024

5 PLAN ORGANIZATION
The Fresno County Multi-Jurisdictional Hazard Mitigation Plan is organized as follows:
▪ Chapter 1: Introduction
▪ Chapter 2: Community Profile
▪ Chapter 3: Planning Process
▪ Chapter 4: Risk Assessment
▪ Chapter 5: Mitigation Strategy
▪ Chapter 6: Plan Implementation and Maintenance
▪ Jurisdictional Annexes
▪ Appendices

1. Introduction
2024 Fresno County Hazard Mitigation Plan
May 2024

6 JURISDICTONAL ANNEXES
Each jurisdiction participating in this plan developed its own annex, which provides a more detailed assessment of the jurisdiction’s unique risks as well as their mitigation strategy to reduce long-term losses. Each jurisdictional annex contains the following:

▪ Community profile summarizing geography and climate, history, economy, and population. ▪ Hazard risk information for geographically specific hazards or unique vulnerabilities. ▪ Hazard map(s) at an appropriate scale for the jurisdiction, if available. ▪ Number and value of buildings, critical facilities, and other community assets located in hazard areas, if available.
▪ Vulnerability information in terms of future growth and development in hazard areas. ▪ A capability assessment describing existing regulatory, administrative, technical, and fiscal resources and tools as well as outreach efforts and partnerships and past mitigation projects; and ▪ Mitigation actions specific to the jurisdiction.

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
1 2. Community Profile
Section Name

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
2 HISTORY
When the first European settlers came to the Fresno area in the early 1800s, the Yokuts tribe was living on the valley floor and in the foothills along the San Joaquin and the Kings Rivers. The Monache tribe lived further up the rivers. Map 1. Historic Tribal Map of Fresno County provides a map of the historic location of these tribes in Fresno County.

Source: Native Land Digital Indigenous Territories

After the initial Spanish explorers came, others began to arrive, including trappers, hunters, and miners.

Kit Carson, the famous mountain man, explored the area during the 1840s. Named for the Spanish word for ash or ash tree, Fresno County was created in 1856, yet its present-day boundaries were not established until 1909. The County was a part of the mining boom of California from its early years until the mid-1860s. Once gold fever subsided, the County turned to livestock and general farming, which received its impetus from the arrival of the Central Pacific Railroad in 1872. As more water became available, the County shifted from general farming to orchards and vineyards.

Map 1. Historic Tribal Map of Fresno County

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
3 GEOGRAPHY AND CLIMATE
One of California’s largest counties, Fresno County covers an area of over 6,000 square miles in central California. A map of the county is shown in Map 2. Fresno County Base Map. It is approximately 200 miles north-northwest of Los Angeles and approximately 160 miles southeast of San Francisco. The county is home to 15 cities and approximately 35 unincorporated communities.

Source: CA Geoportal: CA-DFW: Cal Trans; County of Fresno – GIS Fresno County is large and geographically diverse. The County is located near the center of California’s San Joaquin Valley and is part of the Great Central Valley, one of the state’s distinct physical regions.

The County’s topography is characterized by broad, flat valley floors that generally slope from southeast to northwest; foothills and moderately high mountains (Coast Ranges) in the west; and foothills and high mountains (Sierra Nevada) in the east. Approximately 55 percent of the County is Map 2. Fresno County Base Map

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
4 mountainous, and 45 percent is valley land. Elevations range from 100 to 400 feet on the valley floor to 4,000 feet in the Coast Ranges and more than 14,000 feet in the Sierra Nevada. There are two major rivers in Fresno County, both which originate in the Sierra Nevada: the San Joaquin and Kings rivers.

Additionally, Fresno County is home to a variety of conifer and hardwood forests and woodlands. These tree-dominated habitats can support diverse wildlife populations as well as timber production.

The climate varies among the County’s three regions. Summers are long, hot, and dry in the valley; moderate to hot in the Coast Ranges; and relatively cool in the high elevations of the Sierra Nevada.

There is little precipitation in the County during the summer. Winters in the valley and Coast Ranges are short and mild with light rain in the valley and moderate rainfall in the Coast Ranges. In the Sierra Nevada, winters vary from short and mild with frequent rain and some snow to moderately severe with frequent snow. Most of the seasonal precipitation occurs between October and April. More specific information about Fresno County’s climate can be found in Chapter 4 Risk Assessment.

The mountainous eastern region of the county receives on average up to 70 inches of precipitation annually, mostly in snowfall. Many small mountain lakes and streams in this region are tributaries to the San Joaquin and Kings Rivers which flow into the Central Valley. The valley and western portions of the county, by contrast, are extremely arid, receiving, on average, less than 10 inches of annual rainfall.

The Southern Central Valley Region is projected to increase in temperatures, decline in precipitation along with snowpack in the mountainous area, annual heat waves are projected to increase, and wildfire risk along the eastern edge is projected to experience an increase of 4 to 6 times current conditions according to the Cal-Adapt Climate projections. Detailed information on future climate projections is described in Table 1. Climate Change Projections for Climate-Related Hazards.

Table 1. Climate Change Projections for Climate-Related Hazards Ranges
Temperature Change (1990-2100)
January increases in average temperatures of 3 to 4 degrees Fahrenheit by 2050 and 7 to 10 degrees Fahrenheit by 2100. July increases in average temperatures of 5 degrees to 6 degrees in 2050 and 9 to 11 degrees Fahrenheit by 2100, with larger temperature increases in the mountainous regions to the east. (modeled high temperatures – average of all models; high carbon emissions scenario)
Precipitation
Low areas are projected to experience declines in annual precipitation of 1 or 2 inches by 2050 and up to 2.5 inches by 2100, while more elevated areas are projected to decline up to 10 inches (CCSM3 climate model; high carbon emissions scenario)
Heat Wave
The threshold temperature that defines a heat wave is over 100 degrees Fahrenheit in most of the region. In the mountains, a heat wave is defined by lower temperatures, 70 degrees to 90 degrees Fahrenheit. By 2050, the number of annual heat waves is projected to increase by three to five. An increase of seven to 10 heat waves is expected by 2100 in most of the region, with an increase of up to 14 expected in the mountain areas.

Snowpack
Snowpack in the eastern elevated regions is projected to decrease by approximately 9 inches, resulting in snowpack that is less than 4 inches by March 2090 (CCSM3 climate model; high emissions scenario)
Wildfire Risk The eastern edge of the region is projected to experience an increase in wildfire risk of 4 to 6 times current conditions (GFDL model, high carbon emissions scenario) Source: Public Interest Energy Research, 2011. Cal-Adapt

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
5 ECONOMY
Since the early 1950s, Fresno County has been one of the leading agriculture counties in the United States. Therefore, the agricultural industry is critical to protect and grow as it is an economic powerhouse and major source of employment for the county. Agriculture is Fresno County’s primary industry and is a driving force in the County’s economy. The County’s farmland accounts for nearly half of the land base at 1.88 million acres. More than 300 different crops are grown in the jurisdiction supporting 20 percent of all jobs in the Fresno area. In 2021, Fresno County was the second ranking agricultural county in the state, with a total gross production value of over $8 billion. The leading county for gross production was Tulare County at $8.6 billion. However, over the years, Fresno, Kern, and Tulare, all in the San Joaquin Valley, tend to be the leading counties for produce production. The leading commodities in Fresno County include grapes, pistachios, milk, oranges, peaches, cattle, garlic, tomatoes, tangerines, and mandarins, as well as nectarines. 1 The 2022 Fresno County Crop and Livestock Report ranks the top 10 crops as: 2

1. Grapes

2. Almonds

3. Pistachios

4. Milk

5. Poultry

6. Cattle and calves

7. Tomatoes

8. Peaches

9. Garlic

10. Mandarins
Agriculture accounts for the largest portion of jobs in Fresno County; However, since 1990, the percentage of agriculture-related jobs has continuously fallen. In 1990 agriculture-related jobs accounted for over 50 percent of the total jobs within the top ten raking industries. By 2000, there was a decrease, with agriculture-related jobs falling to approximately 47 percent of those total jobs. By 2013, the percentage had decreased to approximately 36 percent and has continuously decreased to date.

While the agricultural economy is improving, the industry struggles with labor shortages during peak harvest periods, increased production expenses, and climate hazard-related losses such as extreme heat and warm nights, drought, and wildfires. Additionally, climate and weather-related hazards pose a 1 California Agriculture Statistics Review 2021-2022 https://www.cdfa.ca.gov/Statistics/PDFs/2022_Ag_Stats_Review.pdf 2 AG Crop Report_1ST HALF OF BOOK (fresnocountyca.gov)
https://www.fresnocountyca.gov/files/sharedassets/county/v/1/agricultural-commissioner/ag-crop-reports/2022-ag-crop-report- optimized.pdf

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
6 risk to the health and safety outdoor and farm workers within the industry 3 Beyond agriculture and farming, construction is additional sector of employment for the county as well as the healthcare field, showing robust growth in Fresno County.

Despite the success of the booming agriculture and construction industries, the unemployment rate in the county has remained high and the average minimum wage, while above the state’s, remains low.

As of November 2023, the unemployment rate in Fresno County was 7.6 percent up from 6.9 percent in October 2023 and above the 2022 rate of 6.3 percent. Compared to other San Joaquin Valley Counties, Fresno County’s unemployment rate is average. San Joaquin and Stanislaus has an unemployment rate of 6.4 percent, Merced 8.5 percent, Kings 8 percent, Tulare 10.2 percent, Kern 7.8 percent.

Between October and November 2023, total industry employment decreased by 1,600 jobs and farm employment down 9.7 percent. In fact, farm employment recorded the largest month-over decline with a drop of 3,900 jobs. Areas with seasonal economies, such as the County’s agriculture industry, tend to have higher unemployment. Annual Employment by Industry compares the distribution of employment in Fresno County to the State of California. Table 2. Employment in Fresno County and California, 2023 describes the employment statistics for Fresno County.

Table 2. Employment in Fresno County and California, 2023 Fresno County California
Nov 23
Prelim
Percent
Change Year
Nov 23
Prelim
Percent
Change Year
Civilian Labor Force (1) 461,000 0.7% 19,360,500 0.2%
Civilian Employment 426,200 -.6% 18,436,6000 -0.2%
Civilian Unemployment 34,800 20.0% 946,300 21.4%
Civilian Unemployment Rate 7.6% Unavailable 4.9% Unavailable Civilian Unemployment 4.9% Unavailable Unavailable Unavailable (CA Unemployment Rate) 4.9% Unavailable 4.9% Unavailable (U.S. Unemployment Rate) 3.5% Unavailable 3.5% Unavailable Total, All Industries (2) 435,100 1.5% 18,769,300 1.5%
Total Farm 36,300 -2.4% 438,200 3.2%
Total Nonfarm 398,800 1.9% 18,331,100 1.4%
Total Private 317,900 1.4% 15,705,400 1.5%
Goods Producing 50,300 1.4% 2,306,900 1.1%
Mining, Logging, and Construction 23,000 2.7% 968,400 3.9% Mining and Logging 200 0.0% 20,100 1.0%
Construction 22,800 2.7% 948,300 4.0%
Specialty Trade Contractors 15,500 4.0% 630,400 4.7%
Manufacturing 27,300 0.4% 1,338,500 -0.8%
Durable Goods 9,500 -1.0% 869,000 -1.1%
Non-Durable Goods 17,800 1.1% 469,500 -0.3%
Food Manufacturing 13,400 3.1% 171,600 2.9%

3 fcgpr_general-plan_prd-county_redline_2024-01-12_1.pdf (fresnocountyca.gov) https://www.fresnocountyca.gov/files/sharedassets/county/v/1/public-works-and-planning/development-services/planning-and- land-use/general-plan-review-comments/fcgpr_general-plan_prd-county_redline_2024-01-12_1.pdf

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
7 Fresno County California
Nov 23
Prelim
Percent
Change Year
Nov 23
Prelim
Percent
Change Year
Service-Providing 348,500 2.0% 16,024,200 1.5%
Private Service Providing 267,600 1.4% 13,398,500 1.5%
Construction – Residual 7,300 0.0% Unavailable Unavailable Trade, Transportation, and Utilities 79,100 0.5% 3,221,300 0.5% Wholesale Trade 15,900 -1.2% 654,300 -2.5%
Retail Trade 41,600 0.5% 1,675,600 1.2%
Food and Beverage Retailers 8,500 2.4% 382,800 1.8%
General Merchandise Retailers 10,400 5.1% 331,300 2.2%
Transportation, Warehousing, and
Utilities 21,600 1.9% 891,400 1.4%
Transportation and Warehousing 18,500 0.5% 827,400 1.4% Information 3,400 3.0% 580,200 -5.4%
Financial and Insurance 8,300 2.5% 532,300 -1.2%
Insurance Carriers and Related
Activities 4,200 0.0% 202,600 -0.4%
Real Estate and Rental and
Leasing 5,300 2.5% 313,800 -0.1%
Professional and Business
Services 36,000 1.1% 2,902,200 -1.1%
Professional, Scientific, and
Technical Service 11,600 -4.1% 1,473,000 1.3%
Management of Companies and
Enterprises 2,900 3.6% 251,900 0.3%
Administrative and Support and
Waste Management 21,500 3.9% 1,177,300 -4.2%
Administrative and Support
Services 19,900 3.6% 1,121,000 -4.4%
Waste Management and
Remediation Services 1,600 6.7% 56,300 -1.1%
Private Education and Health
Services 4,200 -0.1% 3,169,800 4.6%
Private Educational Services 4,200 -10.6% 419,200 2.6%
Health Care and Social Assistance 78,200 0.5% 2,750,600 4.9% Ambulatory Health Care Services 22,600 -2.2% 988,400 3.3% Hospitals 15,500 -0.6% 414,300 2.1%
Nursing and Residential Care
Facilities 8,300 1.2% 320,800 7.2%
Social Assistance 31,800 2.9% 1,027,100 7.0%
Leisure and Hospitality 39,500 5.9% 2,081,600 4.9%
Accommodation and Food
Services 35,000 6.4% 1,732,200 4.5%
Food Services and Drinking Places 33,000 7.1% 1,515,200 4.5%

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
8 Fresno County California
Nov 23
Prelim
Percent
Change Year
Nov 23
Prelim
Percent
Change Year
Other Services 13,600 3.0% 597,300 4.0%
Government 80,900 3.9% 2,625,700 1.2%
Federal Government 9,600 -2.0% 250,500 1.0%
Total State and Local Government 71,300 4.7% 2,375,200 1.2% State Government 13,200 2.3% 550,200 -0.4%
State Government Educational
Services 4,200 2.4% 251,900 -1.4%
Local Government 58,100 5.3% 1,825,000 1.7%
Source: California Employment Development Department, Employment by Industry Data, 2023 1) Civilian labor force data are by place of residence; include self-employed individuals, unpaid family workers, household domestic workers, & workers on strike.

Data may not add due to rounding. The unemployment rate is calculated using unrounded data. (2) Industry employment is by place of work; excludes self-employed individuals, unpaid family workers, household domes

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
9 In 2022, Fresno County’s employment rose and was the largest over-the-year percent change in covered employment among selected large counties in California at 2.9 percent shown in Figure 1.

Percent Change in Employment Among Large Counties in California, 2022. Nationally, employment increased 2.6 percent over the year. 4

Figure 1. Percent Change in Employment Among Large Counties in California, 2022

Source: U.S. Bureau of Labor Statistics

Comprehensive economic data available for Fresno County comes from the U.S. Census Bureau by way of the American Community Survey. Select estimates of economic characteristics for Fresno County are shown in Table 3. Fresno County Economic Characteristics and Table 4. Fresno County Employment by Industry.

4 County Employment and Wages in California — Fourth Quarter 2022 : Western Information Office : U.S. Bureau of Labor Statistics (bls.gov) https://www.bls.gov/regions/west/news-release/countyemploymentandwages_california.htm

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
10 Table 3. Fresno County Economic Characteristics
Characteristic Fresno County
In civilian labor force, total, percent of population age 16 years+

62.7 In civilian labor force, female, percent of population age 16 years+
383,402
Total accommodation and food services sales, 2017
($1,000)
$1,783,383
Total health care and social assistance receipts/revenue, 2017 ($1,000)
$6,660,486
Total retail sales, 2017 ($1,000) (c) 11,346,970
Median household income (in 2022 dollars), 2018-2022 $67,756 Per capita income in past 12 months (in 2015 dollars), 2018- 2022
$30,130
Persons in poverty, percent 18.6%
Total employer establishments, 2021 18,199
Total employment 2021 276,218
Total annual payroll ($1,000), 2021 14,367,074
Total employment, percent change 2020-2021 -2.8%
Source: U.S. Census Bureau, 2018-2022 American Community Survey 5-Year Estimates Table 4. Fresno County Employment by Industry
Industry # Employed % Employed
Educational Services, and Health
Care, and Social Assistance 105,214 23.5%
Retail Trade 44,105 9.9%
Agriculture, Forestry, Fishing and
Hunting, and Mining 33,444 7.5%
Arts, Entertainment, and Recreation,
and Accommodation, and Food
Services
41,873 9.4%
Professional, Scientific, and
Management, and Administrative
and Waste Management Services
41,376 9.2%
Manufacturing 29,670 6.6%
Public Administration 22,473 5%
Construction 29,222 6.5%
Other Services, Except Public
Administration 22,473 5.0%
Transportation and Warehousing,
and Utilities 33,307 7.4%
Finance and Insurance, and Real
Estate and Rental and Leasing 20,222 4.5%
Wholesale Trade 12,255 2.7%
Information 4,844 1.1%

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
11 Industry # Employed % Employed
Total 440,478 100.0
Source: U.S. Census Bureau American Community Survey, 2023 Estimates, www.census.gov/ The median household income for Fresno County has increased over the past nine years, from about $41,900 in 2005 to $45,233 in 2015 and $69,571 in 2023. In comparison with other San Joaquin Valley counties, the median household income is somewhat low. The County falls significantly short of the state median household income $91,905, as well as other counties in the San Joaquin Valley $82,837 in San Joaquin County and $74,872 in Stanislaus County.

To address unemployment rates and loss of jobs, the county is working to expand, diversify, and strengthen the job base. New industrial sectors for the county include service and technology as well as light manufacturing. Business opportunities in areas such as information processing, water, energy, and health care have gained traction in the county and are projected to be pillars in the future regional economy.

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
12 POPULATION
Fresno County is one of the largest, fastest growing, and most diverse counties in California. It is the state’s 10th most populous county according to the California Department of Finance. Based on the 2020 census, Fresno County has a population of 39,538,223. Figure 2. Fresno County Population:

Annual Percent Change (1970-2022) displays the short-run pattern of Fresno County's population growth by tracking the year-to-year percent change over 1970-2022. The average annual percent change for the entire 53-year period is also traced on this chart to provide a benchmark for gauging periods of relatively high--and relatively low--growth against the backdrop of the long-term average.5 Table 5. Fresno County Population by Jurisdiction displays the population among Fresno County and its municipalities. The City of Fresno encompasses most of the population while the City of San Joaquin is home is the least number of residents in the County.

Source: California REA Project
5 Fresno County vs. California | Population Trends Report over 1969-2022 (reaproject.org) https://california.reaproject.org/analysis/comparative-trends-analysis/population/reports/60019/60000/ Figure 2. Fresno County Population: Annual Percent Change (1970-2022)

2. Community Profile
2024 Fresno County Hazard Mitigation Plan
May 2024
13 Table 5. Fresno County Population by Jurisdiction
Jurisdiction Population 2020
Fresno County 1,008,654
Fresno 542,107
Clovis 120,124
Coalinga 17,590
Firebaugh 8,096
Fowler 6,700
Huron 6,206
Kerman 16,016
Kingsburg 12,380
Mendota 12,595
Reedley 25,227
San Joaquin 3,700
Sanger 26,617
Selma 24,674
Source: U.S. Census Bureau, 2020

Fresno County residents have completed less formal education than residents of California as a whole, with 78.3 percent of the population in Fresno County attaining education levels beyond a high school diploma, compared with 84.4 percent of the population in California. Select demographic and social characteristics for Fresno County from the 2023 estimates American Community Survey are shown in Table 6. Fresno County Demographics.

Table 6. Fresno County Demographics
Fresno County
Population
Population, 2022 estimate 1,015,190
Population, percent change-2020 (estimates base) to 2022 0.6% Population, Census, 2020 1,008,654
Age and Sex
Persons under 5 years, percent 6.9%
Persons under 18 years, percent 27.6%
Persons 65 years and over, percent 12.9%
Female persons, percent 49.7%
Race and Hispanic Origin
White alone, percent 34.7%
Black or African American alone, percent 5.4%
American Indian and Alaska Native alone, percent 0.4%
Asian alone, percent 15.1%
Native Hawaiian and Other Pacific Islander alone, percent 0.3%

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2024 Fresno County Hazard Mitigation Plan
May 2024
14 Two or More Races, percent 4.1%
Hispanic or Latino, percent 39.4%
White alone, not Hispanic, or Latino percent 34.7%
Education
High school graduate or higher, percent of persons aged 25 years+ (2018-2022)

78.3%
Bachelor’s degree or higher, percent of persons aged 25 years+ (2018-2022)

23.4%
Source: U.S. Census Bureau, 2022 5-Year American Community Survey (ACS)

VISITING POPULATION
Every year, millions of people visit Fresno County, more of half of which visit for leisure activities.

Fresno County is the gateway to many recreational activities including national and state parks. The Yosemite, Kings Canyon, and Sequoia National Parks and other High Sierra sights attract visitors from all over the world. The Fresno/Clovis Convention and Visitors Bureau found that in 2022 travelers to Fresno County spent a combined $1.3 billion up 31.4 percent from 2021 which is very similar to the state’s average at 31.7 percent. The boom in tourism added more than 15,000 jobs to the region. 6

FARMWORKERS
Fresno County is one of the leading counties in agricultural production and provides produce and goods to nearly 100 countries across the world. As such, the level of production would not be possible without the labor of farmworkers. Disasters, such as the recent atmospheric rivers and subsequent flooding, have devastated communities in Fresno County, especially farmworkers. Flooded roads and farms for example, significantly impact farm workers due to lack of paychecks which can lead to or exacerbate financial hardships. Lost wages brought on by inequitable extreme weather events can increase the disparity within the farmworker community. It is important that mitigation goals and actions are working towards reducing risk to protect the agricultural industry, specifically the farm workers as the county’s economy and success depends on the labor or these workers.

SOCIAL VULNERABILITY
Emergencies and disasters often highlight and intensify existing societal inequities, affecting groups based on socioeconomic status, race, age, disability, and other social factors. These events disproportionately impact certain populations, creating additional challenges in the preparedness, response, recovery, and mitigation stages. For instance, the COVID-19 pandemic shed light on pre- existing disparities such as limited healthcare access, leading to higher rates of emergency department visits, hospitalizations, and mortality among vulnerable groups. It is essential to recognize and understand these community-specific limitations and barriers to ensure equitable preparedness and response strategies for future incidents.

SOCIAL VULNERABILITY INDEX
To aid in this, the Centers for Disease Control and Prevention (CDC) developed the Social Vulnerability Index (SVI), a comprehensive tool designed for emergency management planners and practitioners at

6 Visitors to Fresno County spent big bucks last year; see how much tourism brings - The Business Journal https://thebusinessjournal.com/visitors-to-fresno-county-spent-big-bucks-last-year-see-how-much-tourism-brings/

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2024 Fresno County Hazard Mitigation Plan
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15 state, local, and tribal levels. The SVI helps identify communities with high social vulnerability, potentially facing greater impacts during emergencies and disasters. This tool is instrumental in guiding targeted efforts in preparedness, response, and recovery, and in understanding the unique challenges certain communities may face, such as evacuation difficulties due to lack of transportation.

The SVI utilizes 16 variables, including factors like education level, presence of disabilities, and access to transportation, to calculate a community’s vulnerability score. This score ranges from 0 to 1, where higher scores indicate increased vulnerability. The evaluation is percentile-based, with communities in the top 10 percent (above the 90th percentile) for a variable scoring a 1, denoting high vulnerability, and those in the bottom 10 percent scoring a 0. Additionally, the SVI categorizes these 16 variables into four distinct themes, providing deeper insights into specific vulnerability aspects. These themes and their constituent variables offer a nuanced understanding of a community's resilience and ability to handle disasters, both in terms of human impact and financial consequences. In Fresno County, the SVI index is .9649 which indicates a high level of social vulnerability, shown in Map 3. Fresno County Social Vulnerability Index.

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16 Source: CDC
Map 3. Fresno County Social Vulnerability Index

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17 DISADVANTAGED COMMUNITIES
The California Environmental Protection Agency developed a tool called CalEnviroScreen to identify communities most impacted by poverty and pollution. The Senate Bill 535 Disadvantaged Communities map identifies census tracts that have an overall CalEnviroScreen score of 75 or above, meaning they are among the top 25 percent most vulnerable and burdened by pollution in the state. In Fresno County, nearly all the census tracts in the eastern part of the county are identified as disadvantaged communities, shown in Map 4. Fresno County Disadvantaged Communities.

Source: California OEHHA, CalEnviroScreen 4.0 Tool

Map 4. Fresno County Disadvantaged Communities

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18 DEVELOPMENT AND INFRASTRUCTURE

POPULATION
California has long been known for its significant population growth and has sustained its growth for a long period of time. Additionally, the state of California is home to many diverse populations and communities including immigrants from more than 60 nations. While growth rates have recently slowed, the state is still growing faster than the country. The state’s growth and changing population will put pressure on infrastructure, service needs, future planning efforts should incorporate population changes to account for increased population growth. Fresno County has a projected population growth of about 88,000 people in the next 40 years. Population projections for the San Joaquin Valley counties are described in Table 7. San Joaquin Valley Future Population Estimates.

Table 7. San Joaquin Valley Future Population Estimates Geography Estimates
2020
Estimates
2030
Estimates
2040
Estimates
2050
Estimates
2060
Fresno County 1,007,344 1,047,382 1,083,901 1,098,206 1,095,205 Stanislaus
County 553,706 558,565 577,523 593,396 609,615
Merced County 280,909 311,578 329,168 336,170 338,247
Madera County 156,141 161,980 163,345 161,937 159,048
Kings County 152,200 157,531 161,190 160,446 156,194
Tulare County 472,597 487,378 487,888 472,966 446,588
Kern County 905,241 940,257 966,310 969,968 954,655
Source: State of California Department of Finance
Since 1960, Fresno County’s population has shifted from the county’s unincorporated area to the county’s cities. Fresno County’s population and anticipated growth is mostly concentrated in and around the county’s cities. The Fresno metropolitan area has absorbed much of the county’s population growth, either through annexations or new development. On average, Fresno County's population grew at an annual rate of 1.74 percent over 1970-2022. The county posted its highest growth in 1989 (3.68 percent) and recorded its lowest growth in 2022 (0.22 percent). In 2022, Fresno County's population grew by 0.22 percent.

HOUSING
As the population increases, additional demand on infrastructure and services will follow including education, transportation corrections, water, health, welfare, and especially housing. The state of California struggles to house its growing population and as a result has a large, unhoused population.

Fresno County faces similar struggles as the state and is working to address the ongoing housing crisis, which has recently been exacerbated by the COVID-19 pandemic. As of 2022, there are an estimated 4,200 individuals that are without housing in the Fresno-Madera region. Since the COVID-19

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19 pandemic, there has been a 43 percent increase in the homeless population from the pre-pandemic estimated of 3,641 in the Fresno-Madera region. 7

7 Fresno leaders share plans to address homelessness - CalMatters https://calmatters.org/california-divide/2022/01/fresno- homelessness/

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20 EMPLOYMENT
Employment projections according to the California Employment Development Department, are estimated to increase across all industries including Trade, Transportation, and Utilities, as well as Educational Services (private), Health Care, and Social Assistance, shown in Figure 3. 2020-2030 Industry Sector Employment Projections.

Source: U.S. Bureau of Labor Statistics’ Current Employment Statistics (CES) March 2021 benchmark and Quarterly Census of Employment and Wages (QCEW) industry employment.

Figure 3. 2020-2030 Industry Sector Employment Projections

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21 TRANSPORTATION
Fresno County is situated mostly west of Interstate 5, which is the major highway stretching across the West Coast from Southern California to Northern Washington State. Interstate 5 experiences heavy traffic due to local, regional, and national travel of people and goods. The map below shows the Fresno County transportation system.

Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS Map 5. Fresno County Transportation System

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22 The map below shows the rail network within Fresno County that includes passenger and freight rail across the region and state. New additions to the rail network are set to change by the next hazard mitigation plan update. In about five years, Fresno’s core will be transformed into the first major hub on America’s most ambitious active infrastructure project: a 500-mile bullet train shuttling people 200-plus mph from San Francisco to Los Angeles in under three hours. The high-speed rail will span 119 miles across Madera, Fresno, Kings, Tulare and Kern counties. The Authority plans to extend this 119-mile segment into Merced and Bakersfield. Unlike Interstate 5, the state’s north-south connector, it’ll run through the heart of the Central Valley. The infrastructure project could support the increase in population over the next several decades as the Central Valley population is growing. 8A map of the project in shown below. 9

8 From ‘train to nowhere’ to Fresno’s dream: What high-speed rail means for the Central Valley - The Business Journal https://thebusinessjournal.com/from-train-to-nowhere-to-fresnos-dream-what-high-speed-rail-means-for-the-central- valley/
9 High-Speed Rail: Central Valley at a Glance (ca.gov) https://www.hsr.ca.gov/wp- content/uploads/docs/communication/info_center/factsheets/Central-Valley-Factsheet.pdf Map 6. Fresno County Rail Network

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23 Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS Source: California High Speed Rail Authority
Map 7. High Speed Rail: Central Valley

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3.Planning Process
Section Name

3. Planning Process
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Requirements §201.6(b) and §201.6(c)(1): An open public involvement process is essential to the development of an effective plan. In order to develop a more comprehensive approach to reducing the effects of natural disasters, the planning process shall include:

An opportunity for the public to comment on the plan during the drafting stage and prior to plan approval;
An opportunity for neighboring communities, local and regional agencies involved in hazard mitigation activities, and agencies that have the authority to regulate development, as well as businesses, academia, and other private and nonprofit interests to be involved in the planning process; and Review and incorporation, if appropriate, of existing plans, studies, reports, and technical information. [The plan shall document] the planning process used to develop the plan, including how it was prepared, who was involved in the process, and how the public was involved.

BACKGROUND
Mitigation planning is critical to lessen impacts from hazards to the whole community. In order to achieve this, mitigation planning must encourage whole community involvement, assessing risk and using a range of resources to reduce risk to people, economies, and natural environments.

The primary purpose of the Fresno County Multi-Jurisdictional Hazard Mitigation Plan (LHMP) update is to reduce or eliminate long-term risk to people and property from natural hazards and their effects on the Fresno County, California planning area. Fresno County recognized the need for and importance of a Local Hazard Mitigation Plan (LHMP) and initiated its development in 2007 after receiving a grant from the Federal Emergency Management Agency (FEMA), which served as the primary funding source for this plan. The original LHMP was developed in 2007-2008 and received FEMA approval in 2009. Additional details on the original planning effort can be referenced in the 2009 Plan. The plan underwent a comprehensive update in 2017-2018 and was approved in 2018.

The most recent hazard mitigation plan update occurred in 2023-2024 and was approved in 2024. The planning process followed a similar update to that used in the last plan update, utilizing input from the Hazard Mitigation Planning Committee (HMPC). Witt O’Brien’s was procured to support the update in 2023.

CHANGES SINCE PREVIOUS PLAN

Requirements §201.6(d)(3): A local jurisdiction must review and revise its plan to reflect changes in development, progress in local mitigation efforts, and changes in priorities, and resubmit it for approval within 5 years in order to continue to be eligible for mitigation project grant funding.

The updated LHMP complies with Federal Emergency Management Agency (FEMA) guidance and California Office of Emergency Services guidelines for Local Hazard Mitigation Plans. The update followed the requirements noted in the Disaster Mitigation Act (DMA) of 2000 and the 2023 Local Hazard Mitigation Planning Handbook.

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This HMP update involved a comprehensive review and update of each section of the 2018 plan and includes an assessment of the progress of the participating communities in evaluating, monitoring and implementing the mitigation strategy outlined in the initial plan. Only the information and data still valid from the 2018 plan was carried forward as applicable into this HMP update.

EQUITY
Additionally, the latest Local Mitigation Planning Handbook includes guidance on ensuring equity is embedded throughout the planning process and within the hazard mitigation plan itself. While disasters themselves do not discriminate, impacts from disasters can be disproportionately experienced across different communities and populations based on existing inequities. It is critical to involve all communities or organizations that represent such unserved and socially vulnerable communities to ensure that the plan is aware and works to reduce risk to the whole community. For example, the public survey was translated into Spanish to ensure that Spanish speaking residents were able to participate in the public survey and provide input as there is a large Spanish speaking population within the county.

The steps to ensure equity into the planning process described in the FEMA Local Mitigation Planning Handbook is outlined below.

Procedural Equity: is committing to equity within the planning process.

• Making clear, fair and inclusive processes. Work with partners who represent underserved groups and socially vulnerable populations to design and implement outreach and engagement methods that will reach the most marginalized and/or vulnerable members of the community.
• Giving chances for meaningful input. Underserved groups should have a true voice in planning and prioritizing mitigation. Invite nonprofit and community-based organizations that support these groups to join the local mitigation planning team. Invite other representatives as well. Welcome them to share their input throughout the planning process.

Structural Equity: builds on the need for accountability. It supports learning the history that led to privilege. It also supports working to correct past harms. Plans can address this by:

• Talking about equity early and often with the planning team. Use the principles of equity in all decision-making processes, from initial outreach to publication of the plan. • Recognizing and dealing with the societal systems that cause inequity. • Forming organizational infrastructure to address inequities. This should happen both at the staff and leadership levels. If inequities are raised during the planning process, make sure there are tools and paths to fix them. Think about working with consultants who have expertise in diversity, equity, and inclusion.

Distributional Equity: ensures that communities that are disproportionately at risk of hazards and their impacts are benefitted by mitigation actions that work to reduce their risk. Communities disproportionately at risk the hazard impacts include:
• High poverty

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• Limited access to a vehicle
• Age (very old or very young)
• Limited English proficiency
• Disability status
• Race
• Ethnicity

The HMPC is committed to working to address and remove physical, social, temporal, language, accessibility, and historically institutional barriers through the planning process to ensure that the plan works for the whole community.

FUTURE PLANNING UPDATES
Chapter 6 (Plan Implementation) identifies key requirements for updating future plans including:
• Ensure that the plan’s mitigation strategy complies with all applicable legal requirements related to civil rights.
• Consider changes in vulnerability due to action implementation; • Document success stories where mitigation efforts have proven effective; • Document areas where mitigation actions were not effective; • Document any new hazards that may arise or were previously overlooked; • Document hazard events and impacts that occurred within the five-year period; • Incorporate new data or studies on hazards and risks; • Incorporate new capabilities or changes in capabilities; • Incorporate documentation of continued public involvement; • Incorporate documentation to update the planning process that may include new or additional stakeholder involvement;
• Incorporate growth and development-related changes to building inventories; • Incorporate new project recommendations or changes in project prioritization; • Include a public involvement process to receive public comment on the updated plan prior to submitting the updated plan to Cal OES/FEMA; and
• Include re-adoption by all participating entities following FEMA approval.

These requirements and others as detailed throughout this plan were addressed during the plan update process.

PLAN SECTION REVIEW AND ANALYSIS – 2024 UPDATE
During the 2024 plan update, the Hazard Mitigation Planning Committee (HMPC) updated each of the sections of the previously approved plan to include new information. Witt O’Brien’s developed a power point presentation during the kick-off meeting to describe each step of the planning process and

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relevant updates based on the FEMA’s local plan update guidance (2023) to ensure that the plan met the latest requirements. A summary of the changes in this plan update is highlighted in the table below.

Table 8. Fresno County Hazard Mitigation Plan Update Highlights Plan Section Summary of Plan Review, Analysis, and Updates Introduction Updated relevant dates and data
Community Profile Updated with recent census data and current economy description Planning Process Updated relevant dates, data, and planning process pertaining the 2024 plan update Risk Assessments
Revisited former hazards list for possible modifications. Reviewed the County and City of Fresno’s CRS participation Updated list of disaster declarations to include recent data.

Updated tables to include recent National Center for Environmental Information data. Updated past occurrences for each hazard to include recent data.

Updated critical facilities list.

Updated growth and development trends to include recent Census and local data sources.

Updated historic and cultural resources using local/state/national sources.

Updated property values for vulnerability and exposure analysis, using updated building information based on assessor’s data.

Updated estimate flood losses using the latest Fresno County Digital Flood Insurance Rate Map (DFIRM) and assessor’s data.

Updated National Flood Insurance Program (NFIP) data and Repetitive Loss structure data from the previous plan.

Incorporated new hazard loss estimates since 2018, as applicable. Used updated GIS inventory data to assess wildfire threat to the County Updated HAZUS-MH Level I earthquake vulnerability analysis data
Updated information regarding specific vulnerabilities to hazards, including maps and tables of specific assets at risk, specific critical facilities at risk, and specific populations at risk.

Updated maps in plan where appropriate.

Reviewed mitigation capabilities and update to reflect current capabilities Mitigation Strategy
Indicated what projects have been implemented that may reduce previously identified vulnerabilities.

Updated Chapter 5 based on the results of the updated risk assessment, completed mitigation actions, and implementation obstacles and opportunities since the completion of the 2018 plan.

Reviewed and updated goals and objectives based on HMPC input.

Revised to include more information on the Community Rating System (CRS) categories of mitigation measures (structural projects, natural resource protection, emergency services, etc.) and how they are reviewed when considering the options for mitigation.

Included updated information on how actions are prioritized.

Reviewed mitigation actions from the 2018 plan and develop a status report for each; identified if actions have been completed, deleted, or deferred/carried forward. Updated priorities on actions.

Identified and detailed new mitigation actions proposed by the HMPC.

Plan Section Summary of Plan Review, Analysis, and Updates Plan Adoption Plan will be re-adopted as part of the update process Plan Maintenance
Reviewed and updated procedures for monitoring, evaluating, and updating the plan. Revised to reflect current methods.

Updated the system for monitoring progress of mitigation activities by identifying additional criteria for plan monitoring and maintenance.

Jurisdictional
Annexes
Updated previous participants’ annexes with recent Census data.

Updated past event history and hazard loss estimates. Added new maps and updated old maps as needed.

Updated mitigation actions from 2018 and added new mitigation actions.

Appendices Updated references.

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Plan Section Summary of Plan Review, Analysis, and Updates Updated planning process documentation.

Updated mitigation alternatives analyzed in the process. Public participation plan updated Plan Adoption.

INCORPORATION OF EXISTING PLANS, STUDIES, AND
DATA
The HMPC used technical data, reports, and studies from the following agencies and groups in the development and update of this plan:
• Bureau of Land Management
• California Department of Forestry and Fire Protection • California Department of Parks and Recreation Office of Historic Preservation • California Department of Transportation
• California Geological Survey
• Fresno County Agricultural Department
• Fresno County Health Department
• Fresno County Information Technology/Geographic Information Systems Department • Fresno County Internal Services Department
• Fresno County Land Use Department
• Fresno County Public Works and Planning Department
• National Oceanic and Atmospheric Administration National Climatic Data Center • National Register of Historic Places
• Natural Resource Conservation Service
• National Weather Service
• U.S. Fish and Wildlife Service
• U.S. Geological Survey
• US Sierra National Forest
• Western Regional Climate Center

PLAN PARTICIPATION
In the 2024 plan update, the following jurisdictions participated in the planning process and will be adopting the updated plan following FEMA approval.
• Fresno County
• City of Clovis
• City of Coalinga
• City of Firebaugh

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• City of Fowler
• City of Fresno
• City of Kerman
• City of Kingsburg
• City of Mendota
• City of Reedley
• City of San Joaquin
• City of Sanger
• City of Selma
• Fresno Metropolitan Flood Control District
• Lower San Joaquin Levee District
• Sierra Resource Conservation District/Highway 168 Fire Safe Council • Kings River Conservation District
• Westlands Water District

The DMA planning regulations and guidance stress that each local government seeking FEMA approval of their mitigation plan must participate in the planning effort in the following ways:
• Participate in the process as part of the HMPC
• Detail areas within the planning area where the risk differs from that facing the entire area
• Identify potential mitigation actions
Formally adopt the plan

For the Fresno County planning area’s HMPC, “participation” meant the following:
• Attending and participating in the HMPC meetings
• Completing and returning worksheets or reviewing jurisdictional annexes • Collecting and providing other requested data (as available) • Identifying mitigation actions for the plan
• Reviewing and providing comments on plan drafts
• Informing the public, local officials, and other interested parties about the planning process and providing opportunity for them to comment on the plan • Coordinating, and participating in, the public input process • Coordinating the formal adoption of the plan by the governing boards

The County and all jurisdictions with annexes to this plan and seeking FEMA approval met all of these participation requirements. In most cases one or more representatives for each jurisdiction attended the

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multi-jurisdictional meetings Schedule of Planning Meetings, and also brought together a local planning team to help collect data, identify mitigation actions and implementation strategies, and review and provide data on annex drafts. In some cases, the jurisdictions had limited capacity to attend or had conflicts with HMPC meetings; in these cases, side-bar phone calls and emails were used to provide input into the process. Appendix B provides additional information and documentation of the planning process.

In addition to the jurisdictions adopting the plan, the HMPC included a wide variety of other stakeholders, including:
• American Red Cross of the Central Valley
• California State University, Fresno
• Cargill
• Central Valley Flood Protection Board
• City of Huron
• City of Orange Cove
• City of Parlier
• Clovis Community College
• Fresno Chamber of Commerce
• Fresno City College
• Fresno Madera Continuum Of Care
(FMCoC)
• Inyo County Office of Emergency Services
• Kern County Fire
• Kings County Emergency Management
• Madera County Emergency Management
• Mariposa County Emergency Management
• Merced County Emergency Management
• Mono County
• Monterey County Emergency Management
• PG&E

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• Pilot Power Group
• Reedley College
• San Benito County Emergency
Management
• San Joaquin College of Law
• San Joaquin River Exchange Contractors
Water Authority
• Southern California Edison
• Sun-Maid
• Tulare County OES
• United Way of Tular County
• West Hill College Coalinga
A complete list of the participants in the HMPC is included in Appendix B: Participation Documentation.

PLAN TIMELINE
The planning team met formally three times to discuss the planning process, share information, review draft plan components, and identify strategies and actions to include in the new plan. A timeline of the planning process is as follows:
• August 2023:
o Fresno County contracted with Witt O’Brien’s to complete this plan update • October 2023:
o Fresno County and Witt O’Brien’s conducted a project kickoff meeting to discuss timeline, participation, and goals for the update.
o Fresno County worked with participating jurisdictions to solicit participation and identify planning team members
o Witt O’Brien’s began conducting hazard analysis and mapping for inclusion in the HIRA
• November 2023:

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o November 17, 2023: Fresno County Multi-Jurisdictional Hazard Mitigation Plan Kickoff Meeting – Virtual meeting, via Microsoft Teams. Discussion topics included:
▪ Planning team introductions
▪ Hazard mitigation overview
▪ The mitigation planning process
▪ Hazard identification data gathering exercises
▪ Questions and next steps
o Critical facilities list was finalized
• December 2023:
o Capability Assessment and Hazard Identification Exercise worksheets shared with planning team members
o Participating jurisdictions provided feedback on the hazards causing the greatest challenges for their communities by completing Hazard Identification Exercise worksheets
o Fresno County works with the planning team to identify critical facilities and assets to use in the plan update.
• January 2023:
o Participating jurisdictions began cataloguing their capabilities and resources, as outlined in the Capability Assessment Worksheet
o The public was given the opportunity to provide input on the plan via the “Fresno County Hazard Mitigation Plan – Public Opinion Survey”, which was open from January 10, 2024, to January 30, 2024.
o January 16, 2024: Fresno County Multi-Jurisdictional Hazard Mitigation Plan – Public Meeting – First of two virtual and in-person hybrid meetings open to the public. Discussion topics included:
▪ Hazard mitigation and mitigation planning overview
▪ Availability of public survey
▪ Opportunity for input and open discussion

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o January 17, 2024: Fresno County Multi-Jurisdictional Hazard Mitigation Plan – Public Meeting – Second of two virtual and in-person hybrid meetings open to the public. Discussion topics included:
▪ Hazard mitigation and mitigation planning overview
▪ Availability of public survey
▪ Opportunity for input and open discussion
• February 2023:
o Mapping and modeling for the HIRA was substantively completed • March 2023:
o A wide variety of stakeholders (including non-government organizations, businesses, and neighboring communities) were invited to join the planning team, participate in future meetings, and comment on the draft plan. o March 6, 2024: Fresno County Multi-Jurisdictional Hazard Mitigation Plan - HIRA Meeting – Virtual meeting, via Microsoft Teams. Discussion topics included:
▪ Plan process review
▪ HIRA progress
▪ Hazard maps developed to date
▪ Results of the public survey
▪ Brainstorming hazard mitigation actions
o Strategy worksheets were shared with plan participants o Plan participants provided feedback on the goals and objectives for the plan, reviewed their actions from the previous plan, determined which to keep in the new plan, and identified new actions (via the Strategy Worksheet). o March 28, 2024: Fresno County Multi-Jurisdictional Hazard Mitigation Plan – Strategy Meeting – Virtual meeting, via Microsoft Teams. Discussion topics included:
▪ Plan status

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▪ Review and discussion of the proposed goals for the plan ▪ Mitigation action development updates, discussion, brainstorming, and problem-solving
▪ Discussion of aligning mitigation actions with grant opportunities ▪ Timeline, Next Steps, and Questions
• April 2023:
o The Planning Team provided all remaining input, worksheets, and data, and the plan draft was finalized.
• May 2023:
o The Planning Team provided all remaining input, worksheets, and data, and the plan draft was finalized.
o The draft plan was made available for public review online on May 3, 2024, and remained available for public comment through May 17, 2024. An online form allowed plan participants to provide feedback on the draft, and on risk reduction in Fresno County in general.

Documentation of the planning process (including presentations, meeting participation, surveys and results, and relevant communications) is available in Appendix B: Process and Participation Documentation.

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4. Risk Assessment
Section Name

4. Risk Assessment
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Requirement §201.6(c)(2): [The plan shall include] A risk assessment that provides the factual basis for activities proposed in the strategy to reduce losses from identified hazards. Local risk assessments must provide sufficient information to enable the jurisdiction to identify and prioritize appropriate mitigation actions to reduce losses from identified hazards.

As defined by FEMA, risk is a combination of hazard, vulnerability, and exposure. Risk is the estimated impact that a hazard would have on people, services, facilities, and structures in a community. It refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.

The risk assessment process identifies and profiles relevant hazards and assesses the exposure of lives, property, and infrastructure to these hazards. The process allows for a better understanding of a jurisdiction’s potential risk to hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

This risk assessment followed the methodology described in the 2023 FEMA publication Local Mitigation Planning Handbook:

1. Describe hazards

2. Identify community assets

3. Analysis risks

4. Summarize vulnerability

Data collected through this process has been incorporated into the following sections of this chapter:

• Hazard Identification Natural Hazards Section: identifies the natural hazards that threaten the planning area and describes why some hazards have been omitted from further consideration. • Hazard Profiles Section: discusses the threat to the planning area and describes previous occurrences of hazard events and the likelihood of future occurrences. • Vulnerability Assessment Section: assesses the County’s total exposure to natural hazards, considering assets at risk, critical facilities, and future development trends. • Human-Caused Hazards Section: identifies the areas most susceptible to potential human- caused hazard events by evaluating the locations of hazardous materials facilities and transportation routes.
• Capability Assessment Section: inventories existing mitigation activities and policies, regulations, and plans that pertain to mitigation and can affect net vulnerability.

This risk assessment covers the entire geographical extent of Fresno County. Since this plan is a multi- jurisdictional plan, the HMPC was required to evaluate how the hazards and risks vary from jurisdiction to jurisdiction. While these differences are noted in this chapter, they are expanded upon in the annexes of the participating jurisdictions. If no additional data is provided in an annex, it should be assumed that the risk and potential impacts to the affected jurisdiction are similar to those described here for the entire Fresno County planning area.

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HAZARD IDENTIFICATION

Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the type of all natural hazards that can affect the jurisdiction.

The Fresno County HMPC conducted a hazard identification study to determine the hazards that threaten the planning area.

METHODOLOGY AND RESULTS
Using existing hazards data and input gained through planning meetings during the 2024 plan update, the HMPC agreed to continue to profile the same 19 identified hazards in the 2018 plan, into the 2024 plan update. In order to update the profiled hazards, data from the California Governor’s Office of Emergency Services (CA-OES), FEMA, the National Oceanic and Atmospheric Administration, and many other sources were examined to assess the significance of these hazards to the planning area.

Significance was measured in general terms and focused on key criteria such as frequency and resulting damage, which includes deaths and injuries and property, economic, and crop damage as the county is one of the largest agricultural producers in the state. The hazards evaluated as part of this plan include those that occurred in the past or have the potential to cause significant human and/or monetary losses in the future. The potential for loss and impacts from the hazards are analyzed further in the Vulnerability Assessment section.

In alphabetical order, the natural hazards identified and investigated for the Fresno County Multi- Jurisdictional Hazard Mitigation Plan include:
• Agricultural Hazards
• Avalanche
• Dam Failures
• Drought
o Tree Mortality
• Earthquake
• Flood
• Wildfire
• Volcano
Human Health Hazards
• Epidemic/Pandemic
• West Nile Virus
• Landslide
Severe Weather

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• Extreme Temperatures
o Extreme Cold/Freeze
o Extreme Heat
• Fog
• Heavy Rain/Thunderstorm/Hail/Lightning/Wind
• Winter Storm
• Tornado
Soil Hazards
• Erosion
• Expansion Soils
• Land Subsidence
• Landslide

OVERALL HAZARD SIGNIFICANT SUMMARY
Overall hazard significance was based on a combination of Geographic Extent, Probability and Potential Magnitude/Severity as defined in Table 9. Fresno County Hazard Significance. The individual ratings are based on or interpolated from the analysis of the hazards in the sections that follow. During the 2024 Fresno County LHMP update, the individual ratings and significance of the hazards were revisited and updated. Subsidence, as a subset of soil hazards, has become more of an issue due to heavy groundwater withdrawal during the severe multi-year drought 2012-2017 and 2020- 2023. It may also be exacerbating flood hazards by lowering levee heights in some areas. This hazard’s significance was changed from low to medium during the 2017 update.

Table 9. Fresno County Hazard Significance
Hazard 0.3 0.3 0.2 0.1 0.1 Overall
Risk
Probability Impact Spatial Extent Warning Time Duration Agricultural
Hazards Highly Likely Negligible Limited More than 24
hours
Less than
24 hours

3.5 Avalanche Likely Limited Limited Less than 6 hours Less than 6 hours

2.4 Dam Failure Occasional Critical Extensive More than 24 hours
Less than
24 hours

2.6 Drought Likely Limited Significant More than 24
hours
More than
1 week

2.5 Earthquake Occasional Catastrophic Significant Less than 6 hours Less than 6 hours

2.5 Flood/Levee Failure Likely Critical Extensive More than 24 hours
Less than 1
week

2.6 Human Health Hazards

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Hazard 0.3 0.3 0.2 0.1 0.1 Overall
Risk
Probability Impact Spatial Extent Warning Time Duration Epidemic/Pandemic Occasional Negligible Extensive More than 24 hours
More than
1 week

3.1 Hazardous Materials Highly Likely Limited Significant Unavailable Unavailable Unavailable West Nile Virus Occasional Negligible Limited More than 24 hours
Less than 1
week

2.7 Severe Weather
Extreme
temperatures Highly Likely Negligible Significant More than 24 hours
Less than 1
week

3.3 Fog Highly Likely Limited Extensive More than 24
hours
Less than
24 hours

2.4 Heavy
Rain/Thunderstorm/
Hail/Lightning
Highly Likely Limited Extensive More than 24
hours
Less than
24 hours

2.4 Winter Storm Highly Likely Negligible Limited More than 24 hours
Less than
24 hours

2.2 Tornado Occasional Negligible Extensive More than 24 hours
Less than 6
hours

2.2 Soil Hazards
Erosion Likely No Data No Data No Data No Data 1.9
Expansive Soils Occasional No Data No Data No Data No Data 1.3 Landslide Occasional Limited Limited 12 to 24 hours Less than 6 hours

2.0 Land Subsidence Highly Likely No data Extensive No Data No Data 2.0 Volcano Unlikely Negligible Extensive Less than 6 hours Less than 1 week

2.0 Wildfire Highly Likely Critical Extensive 12 to 24 hours Less than 1 week

3.65 Geographic Extent
Limited: Less than 10% of planning
area
Significant: 10-50% of planning area
Extensive: 50-100% of planning area
Probability of Future Occurrences
Highly Likely: Near 100% chance of occurrence in next year, or happens every year
Likely: Between 10 and 100% chance of occurrence in next year, or has a recurrence interval of 11 to 100 years
Unlikely: Less than 1% chance of occurrence in the next 100 years, or has a recurrence interval of greater than every 100 years
Magnitude/Severity
Catastrophic-More than 50 percent of property severely damage; shutdown of facilities for more than 30 days; and/or multiple deaths
Critical-25-50 percent of property severely damaged; shutdown of facilities for at least two weeks; and/or injuries/or illnesses result in permanent disability
Limited-10-25 percent of property severely damaged; shutdown of facilities for more than a week; and/or injuries/illnesses treatable do not result in permanent disability
Negligible-Less than 10 percent of property severely damaged, shutdown of facilities and services for less than 24 hours; and/or injuries/illnesses treatable with first aid

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Hazard 0.3 0.3 0.2 0.1 0.1 Overall
Risk
Probability Impact Spatial Extent Warning Time Duration Significance
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact

DISASTER DECLARATION HISTORY
Federal and/or state disaster declarations may be granted when the severity and magnitude of an event surpasses the ability of the local government to respond and recover. Disaster assistance is supplemental and sequential. When the local government’s capacity has been surpassed, a state disaster declaration may be issued, allowing for the provision of state assistance. Should the disaster be so severe that both the local and state governments’ capacities are exceeded, a federal emergency or disaster declaration may be issued allowing for the provision of federal assistance.

The federal government may issue a disaster declaration through FEMA, the U.S. Department of Agriculture (USDA), and/or the Small Business Administration (SBA). FEMA also issues emergency declarations, which are more limited in scope and without the long-term federal recovery programs of major disaster declarations. The quantity and types of damage are the determining factors.

A USDA declaration will result in the implementation of the Emergency Loan Program through the Farm Services Agency. This program enables eligible farmers and ranchers in the affected county as well as contiguous counties to apply for low interest loans. A USDA declaration will automatically follow a major disaster declaration for counties designated major disaster areas and those that are contiguous to declared counties, including those that are across state lines. As part of an agreement with the USDA, the SBA offers low interest loans for eligible businesses that suffer economic losses in declared and contiguous counties that have been declared by the USDA. These loans are referred to as Economic Injury Disaster Loans.

Fresno is among the many counties in California that are susceptible to disaster. Details on federal and state disaster declarations were obtained by the FEMA, and CA-OES and compiled in chronological order in Table 10. Fresno County Disaster Declaration: State and Federal Declarations, 1950- 2024. A review of state and federal declared disasters indicates that Fresno County received 51 state declarations between 1950 and January 2024, 33 of which also received federal disaster declarations.

USDA declarations for the planning area are discussed in the Agricultural Hazards Section.

This disaster history (combined federal and state) suggests that Fresno County experiences a major event worthy of a disaster declaration every 1.5 years. The County has a 68 percent chance of receiving a disaster declaration in any given year, which is up nearly double from 39 percent in the previous plan update in 2018. Except for the declarations for earthquake, wildfire, and epidemic/pandemic due to the COVID-19 pandemic in 2019/2020, every declaration resulted directly or indirectly from severe weather. Most disaster-related injuries to people and damage to property and crops resulted from severe weather. However, the recent COVID-19 pandemic resulted in significant economic damage, hospitalizations, and loss of life compared to any other disaster related event. More information on the COVID-19 pandemic is summarized in the Pandemic/Epidemic hazard profile section.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024 7
Table 10. Fresno County Disaster Declaration: State and Federal Declarations, 1950-2024 Hazard Type Disaster
#
Year State
Declaration
Federal
Declaration
Location Damage*
Floods CDO 50-
01 1950 11/21/1950 N/A Fresno
County
9 deaths;
$32,183,000
Floods DR-47 1955 12/22/1955 12/23/55
Fresno
County
(statewide)

74. $200,000,000
Unseasonal and
Heavy Rainfall N/A 1957 5/20/1957 N/A
Fresno
County
(other
cherry
producing
areas)
2 injuries.
$6,000,000
Storm & Flood
Damage N/A 1958 4/2/1958 4/4/1958
Fresno
County
(statewide)

13. $24,000,000
Unseasonal and
Heavy Rainfall N/A 1959 9/17/1959 N/A
Fresno
County
(other
Tokay
grape
producing
areas)
2 deaths
$100,000
Abnormally Heavy
and Continuous
Rainfall
N/A 1963 2/14/1964 N/A
Fresno
County
(and 50
other
counties)
Unknown
1969 Storms OEP 253-
DR-CA 1969 1/25/1969 1/26/1969
Fresno
County
(and 39
other
counties)
47 deaths
161 injuries
$300,000,000
Freeze and Severe
Weather Conditions N/A 1972 4/17/1972 N/A
Fresno
County
(and 16
other
counties)
$111,517,260
Drought N/A 1976 2/9/1979 N/A
Fresno
County
(and 30
other
counties)
$2,664,000,000
Rains Causing
Agricultural Losses N/A 1982 10/26/1982 N/A
Fresno
County
(and 10
other
counties)
$345,195,974
Winter Storms DR-682 1982/1983 3/15/1983 2/9/1983
Fresno
County
(and 43
other
counties)
$523,617,032

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2024 Fresno County Hazard Mitigation Plan
May 2024 8
Hazard Type Disaster
#
Year State
Declaration
Federal
Declaration
Location Damage*
Coalinga
Earthquake DR-682 1983 5/02/1983 5/3/1983 Fresno
County
No deaths
47 injuries
$31,076,300
Storms DR-758 1986 2/26/1986 2/18/1986
Fresno
County
(and 38
counties)
13 deaths
67 injuries
$407,538,904
Wildland Fires N/A 1987 9/03/1987 N/A
Fresno
County
(and 23
other
counties)
3 deaths
76 injuries
$18,000,00
Freeze DR-894 1990 1/11/1991 2/11/1991
Fresno
County
(and 32
counties)
$856,329,675
Late Winter Storms DR-979 1992 1/21/1993 1/15/1993
Fresno
County
(and 23
other
counties)
20 deaths
10 injuries
$600,000,000
Severe Winter
Storms DR-1044 1995 1/17/1995 1/13/1995
Fresno
County
(and 44
other
counties)
11 deaths
$741,400,000
Late Winter Storms DR-1046 1995 N/A 1/10/1995
Fresno
County
(and all
other
counties
except Del
Norte)
17 deaths
$1,100,000,000
January 1997
Floods DR-1155 1997 1/5/1997 1/4/1997
Fresno
County
(and 46
other
counties)
8 deaths
$1,800,000,000
Severe Winter
Storms and
Flooding
DR-1203 1998 N/A 2/9/1998
Fresno
County
(and 39
other
counties)
17 deaths
$550,000,000
Freeze DR-1267 1998-1999 N/A 2/7/1999
Fresno
County
(and 7
other
counties)
Unknown
Severe Freeze DR-1689 2007 N/A 3/14/07
Fresno
County
(and 11
other
counties)
$1,400,000,000

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2024 Fresno County Hazard Mitigation Plan
May 2024 9
Hazard Type Disaster
#
Year State
Declaration
Federal
Declaration
Location Damage*
Goose Fire FM-5140 2016 7/30/2016 8/8/2016 Fresno
County Unknown
Floods CDO 50-
01 1950 11/21/1950 N/A
Fresno
County
(statewide)
9 deaths
$32,183,000
Floods DR-47 1955 12/22/1955 12/23/1955
Fresno
County
(statewide)
74 deaths
$200,000,000
Unseasonal and
Heavy Rain N/A 1957 5/20/1957 N/A
Fresno
County
(other
cherry
producing
areas)
2 injuries
$6,000,000
Storm & Flood
Damage N/A 1958 4/2/1958 4/4/1958
Fresno
County
(statewide)
13 deaths
$24,000,000
Unseasonal and
Heavy Rainfall N/A 1959 4/2/1958 4/4/1958
Fresno
County
(statewide)
13 deaths
$24,000,000
Unseasonal and
Heavy Rainfall N/A 1959 9/17/1959 N/A
Fresno
County
(other
tokay
grape
producing
areas)
2 deaths
$100,000
Abnormally Heavy
and Continuous
Rainfall
N/A 1963 2/14/1964 N/A
Fresno
County
(and 50
other
counties)
Unknown
969 Storms OEP 253-
DR-CA 1969 1/25/1969 1/26/1969
Fresno
County
(and 39
other
counties)
47 deaths
161 injuries
$300,000,000
Freeze and Severe
Weather Conditions N/A 1972 4/17/1972 N/A
Fresno
County
(and 16
counties)
$111,517,260
Drought N/A 1976 2/9/1976 N/A
Fresno
County
(and 30
other
counties)
$2,664,000,000
Rains Causing
Agricultura Losses N/A 1982 10/26/1982 N/A
Fresno
County
(and 10
other
counties)
$345,195,974
Winter Storms DR-682 1982-1983 3/15/1983 2/9/1983
Fresno
County
(and 43
$523,617,032

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2024 Fresno County Hazard Mitigation Plan
May 2024 10
Hazard Type Disaster
#
Year State
Declaration
Federal
Declaration
Location Damage*
other
counties)
Coalinga
Earthquake DR-682 1983 5/02/1983 5/3/1983 Fresno
County
No deaths
47 injuries
$31,076,300
Storms DR-758 1986 2/26/1986 2/18/1986
Fresno
County
(and 38
other
counties)
13 deaths
67 injuries
$407,538,904
Wildland Fires N/A 1987 9/03/1987 N/A
Fresno
County
(and 23
other
counties)
3 deaths
76 injuries
$18,000,000
Freeze DR-894 1990 1/11/1991 2/11/1991
Fresno
County
(and 32
other
counties)
$856,329,675
Late Winter Storms DR-979 1992 1/21/1993 1/15/1993
Fresno
County
(and 23
other
counties)
20 deaths
10 injuries
$600,000,000
Severe Winter
Storms DR-1044 1995 1/17/1995 1/13/1995
Fresno
County
(and 44
other
counties)
11 deaths
$741,400,000
Late Winter Storms DR-1046 1995 N/A 1/10/1995
Fresno
County
(and all
other
counties
except Del
Norte)
17 deaths
$1,800,000,000
January 1997
Floods DR-1155 1997 1/5/1997 1/4/1997
Fresno
County
(and 46
other
counties)
8 deaths
$1,800,000,000
Severe Winter
Storms and
Flooding
DR-1203 1998 N/A 2/9/1998
Fresno
County
(and 39
counties)
17 deaths
$550,000,000
Freeze DR-1689 2007 N/A 3/14/2007
Fresno
County
(and 7
other
counties)
Unknown
Severe Freeze DR-1689 2007 N/A 3/14/2007
Fresno
County
(and 11
$1,400,000,000

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May 2024 11
Hazard Type Disaster
#
Year State
Declaration
Federal
Declaration
Location Damage*
other
counties)
Epidemic/Pandemic DR-4482-
CA 2020 N/A 3/22/20
Fresno
County
(statewide)
Unknown
Wildfires DR-4569-
CA 2020 N/A 10/16/20
Fresno
County
(and 7
other
counties)
Unknown
Severe Winter
Storms, Flooding,
Landslides,
Mudslides
DR-4683-
CA 2023 N/A N/A Fresno
County Unknown
Severe Winter
Storms, Straight-
Line Winds,
Flooding,
Landslides
DR-4699-
CA 2023 N/A 4/3/2023 Fresno
County Unknown
Source: California Governor’s Office of Emergency Services, www.oes.ca.gov/ *Damage amount and deaths and injuries reflect totals for all impacted counties

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
12 HAZARD PROFILES

Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the location and extent of all natural hazards that can affect the jurisdiction. The plan shall include information on previous occurrences of hazard events and on the probability of future hazard events.

The hazards identified in the Hazard Identification section are profiled individually in this section. In general, information provided by planning team members is integrated into this section with information from other data sources. These profiles set the stage for the Vulnerability Assessment section, where the vulnerability is quantified, where possible, for each of the priority hazards.

Each hazard is profiled in the following format:

▪ Hazard/Problem Description—This section gives a description of the hazard and associated issues followed by details on the hazard specific to the Fresno County planning area. Where known, this includes information on the hazard extent, seasonal patterns, speed of onset/duration, and magnitude and/or secondary effects.
▪ Extent – This section gives a description of the potential strength or magnitude of the hazard as it pertains to Fresno County. The geographic extent or location of the hazard is also discussed. ▪ Past Occurrences—This section contains information on historical incidents, including impacts where known. The extent or location of the hazard within or near the Fresno County planning area is also included here. Historical incident worksheets were used to capture information from participating jurisdictions on past occurrences.
▪ Likelihood of Future Occurrence—The frequency of past events is used in this section to gauge the likelihood of future occurrences. Where possible, frequency was calculated based on existing data. It was determined by dividing the number of events observed by the number of years on record and multiplying by 100. This gives the percent chance of an event happening in any given year (e.g., three droughts over a 30-year period equates to a 10 percent chance of a drought in any given year). The likelihood of future occurrences is categorized into one of the following classifications:
o Highly Likely—Greater than 90 percent annual probability of occurrence o Likely—Between 50 and 90 percent annual probability of occurrence o Occasional—Between 1 and 49.9 percent annual probability of occurrence o Unlikely—Less than 1 percent annual probability of occurrence ▪ Climate Change Considerations - This describes the potential for climate change to affect the frequency and intensity of the hazard in the future.

The Vulnerability Assessment section has more detail on the County’s total exposure to natural hazards, considering assets at risk, critical facilities, and future development trends. Where feasible the

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May 2024
13 vulnerability of people, property, critical facilities, the natural environment, and future development are considered for each hazard.

The following sections provide profiles of the natural hazards that the HMPC identified in Identifying Hazards section. The hazards follow alphabetically.

SUMMARY OF CLIMATE CHANGE IMPACTS IN CALIFORNIA
Overall, the planet is warming faster than ever. Heat trapping gases—such as carbon dioxide and methane—are building up in our atmosphere, creating a blanket around the globe that traps heat, like a greenhouse. This is also known as global warming, even though many of its effects go far beyond temperature changes. Global warming pollution comes from the use of fossil fuels such as oil, coal, and natural gas, and from agricultural and industrial activities. We burn fossil fuels to generate energy, to power vehicles and other transportation such as planes, and to manufacture countless products. The extra trapped heat has been changing important aspects of our climate and the water cycle, which is the movement of water on our planet.

Summary of climate change trends and projections are listed below:

▪ Higher temperatures
▪ Increasing evapotranspiration (water that evaporates or is used by plants) ▪ Longer and more severe droughts
▪ Declining snowpack
▪ More intense rainstorms
▪ More frequent and extensive wildfires
▪ Sea level rise1

1 https://www.ucsusa.org/sites/default/files/2020-10/climate-change-in-SJValley.pdf

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
14 AGRICULTURAL HAZARDS

HAZARD/PROBLEM DESCRIPTION
Located in the Central San Joaquin Valley, Fresno County’s farming and agricultural industry is ranked as one of the top agriculture-producing counties in California and the country. Farming and agriculture- related businesses are a significant component of the local economy and are responsible for 20 percent of all jobs in the Fresno area. The following figure shows the type of farms across the San Joaquin Valley.

4. Risk Assessment
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May 2024
15 Source: Public Policy Institute of California
Figure 4. Farm Size in the San Joaquin Valley

4. Risk Assessment
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May 2024
16 4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
17 In Fresno County, according to the USDA 2022 agricultural census, there were a total of 4,427 farms encompassing 1,659,451 acres of land, which brings the average size of a farm to approximately 375 acres. The market value of agricultural products sold reached a staggering $6,995,967,000, averaging $1,580,295 per farm. Out of the total farms, 3,823 were dedicated to cropland, covering 1,182,023 acres. According to the Fresno County Agricultural Commissioner the County has approximately 678,103 acres of prime agricultural land, 404,083 acres of farmland of statewide importance, and 825,276 acres of grazing land (see Table 11. Fresno County's Farmland Inventory below). An updated source for the information below was not available during the latest plan update.

Table 11. Fresno County's Farmland Inventory
Soil Category Acres
Prime Farmland 678,103
Farmland of Statewide
Importance
404,083
Unique Farmland 33,653
Farmland of Local
Importance
131,341
Grazing Land 825,276
Urban and Built-Up Land 124,025
Water 4,915
Other Land 116,094
Source: Fresno County Agricultural Commissioner 2017

According to the 2022-2023 Fresno County Agricultural Crop and Livestock Report, the total gross value of agricultural commodities in Fresno County in 2021 was over $8 billion. The County’s leading agricultural products included grapes, almonds, pistachios, milk, poultry, cattle and calves, tomatoes, peaches, garlic, and mandarins.

Fresno’s top ten crops have seen a shift between 1995 and 2022. However, the crops have mostly remained constant, their ranks in the county have changed in the intervening 20 years. A list of Fresno County’s top leading crops is described in Table 12. Fresno County's Ten Leading Crops.

Table 12. Fresno County's Ten Leading Crops
Crop 2022
Rank 2022 Dollar Value 2015
Rank
2014
Rank
2005
Rank
1995
Rank
Almonds 2 $1,141,308,000 1 1 2 7
Grapes 1 $1,241,178,000 2 2 1 2
Poultry 5 $538,305,000 3 3 7 3
Cattle and
Calves 6 $488,665,000 4 5 5 8
Tomatoes 7 $429,263,000 5 6 4 4
Milk 4 $655,138,000 6 4 3 5
Peaches 8 $368,392,000 7 9 8 12

4. Risk Assessment
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May 2024
18 Crop 2022
Rank 2022 Dollar Value 2015
Rank
2014
Rank
2005
Rank
1995
Rank
Garlic 9 $351,875,000 8 8 14 11
Mandarins 10 $240,684,000 9 N/A N/A N/A
Oranges N/A N/A 10 11 10 10
Pistachios 3 $705,941,000 N/A N/A N/A N/A
Source: State of California Department of Conservation Farmland Mapping and Monitoring Program, www.conservation.ca.gov/

According to the HMPC, agricultural losses occur on an annual basis and are usually associated with severe weather events, including heavy rains, floods, hail, freeze, drought or disease outbreaks. The State of California Hazard Mitigation Plan attributes most of the agricultural disasters statewide to drought, freeze, and insect infestations. Other agricultural hazards include fires, crops and livestock disease, noxious weeds, and contamination of animal food and water supplies.

Fresno County is threatened by several insects that, under the right circumstances, can cause severe economic and environmental harm to the agricultural industry. Insects of concern to plants and crops include the medfly, peach fruit fly, Mexican fruit fly, guava fruit fly, oriental fruit fly, melon fly, gypsy moth, Japanese beetle, glassy-winged sharpshooter, paper wasp, and Turkestan roach. Livestock disease can also cause large-scale economic losses in any area that raises large amounts of livestock.

Noxious weeds, which are any plant that is or is liable to be troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or important native species and that is difficult to control or eradicate, are also of concern. Noxious weeds within the planning area include yellow starthistle, purple loosestrife, and Japanese dodder.

Noxious weeds have been introduced in the planning area by a variety of means, including through commercial nurseries. An absence of natural controls combined with the aggressive growth characteristics and unpalatability of many of these weeds allows these weeds to dominate and replace more desirable native vegetation. Negative effects of weeds include the following:

▪ Loss of wildlife habitat and reduced wildlife numbers ▪ Loss of native plant species
▪ Reduced livestock grazing capacity
▪ Increased soil erosion and topsoil loss
▪ Diminished water quality and fish habitat
▪ Reduced cropland and farmland production
▪ Reduced land value and sale potential

Another threat to the agricultural industry is the wild hogs that run free in the eastern and western foothills of the County. These wild hogs can cause extensive agricultural crops and property damage to farms and private land. Wild hogs are known to carry and transmit 30 different virulent and bacterial diseases, as well as at least 37 parasites both to humans and livestock. E. coli contamination of leafy vegetables has been linked to wild hogs foraging in vegetable fields.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
19 In addition to issues associated with wild hogs, the proper management of other wildlife within the planning area is of significant concern to the County Department of Agriculture. Wildlife such as coyotes, ground squirrels, and others can cause extensive livestock, crop, and property damage. Such wildlife is also known to carry and transmit diseases (e.g., bubonic plague and rabies) to livestock and domestic animals as well as to humans.

According to the Fresno County Operational Area Master Emergency Services Plan, the consequences of agricultural disasters to the planning area include ruined plant crops, dead livestock, ruined feed and agricultural equipment, monetary loss, job loss, and possible multi-year effects (i.e., trees might not produce if damaged, loss of markets, food shortages, increased prices, possible spread of disease to people, and loss or contamination of animal products). When these hazards cause a mass die-off of livestock, other issues arise that include the disposal of animals, depopulation of affected herds, decontamination, and resource problems. Those disasters related to severe weather may also require the evacuation and sheltering of animal populations. Overall, any type of severe agricultural disaster can have significant economic impacts on the agricultural community as well as the entire Fresno County planning area.

EXTENT
Historically, Fresno County has received disaster declarations from the USDA for a variety of incident types, including drought, hail, rain, cold and wind. Fresno County’s agriculture industry is a multi-billion- dollar enterprise; a long-term, widespread agricultural hazard could have impacts in the hundreds of millions of dollars, if not billions of dollars.

PAST OCCURRENCES
Based on information from the USDA, Fresno County received 11 USDA disaster declarations between 1991 and 2024 (see Table 13. Fresno County's USDA Disaster Declarations). Between January of 2018 and 2024, Fresno County received seven additional USDA Declaration for drought, frost and freeze, excessive rain, moisture, humidity, and hail. All the declarations were associated with drought or severe weather events; none were related to agricultural disease.

Table 13. Fresno County's USDA Disaster Declarations
Incident Type Incident Date Damage ($)
Short-term Drought 2009 $164,893,718
Severe Spring Storm: Rain, Hail,
High Winds 6/4 & 5/2009 $4,533,107
Lack of Chill Hours 2014 $53,534,295
Severe Long-Term Drought 2012-2016 Not Quantified
Excessive Rain, Moisture,
Humidity 2019 Not Quantified
Excessive Rain, Moisture,
Humidity, Hail 2019 Not Quantified
Drought 2020 Not Quantified
Drought 2021 Not Quantified

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20 Incident Type Incident Date Damage ($)
Frost, Freeze 2021 Not Quantified
Drought 2021 Not Quantified
Drought 2022 Not Quantified
Source: USDA, Farm Service Agency, Disaster Designation Information

Historical occurrences identified by the HMPC include the following:

Fresno County
▪ 1970s: A local outbreak of scabies occurred.
▪ 1991: There was an outbreak of bovine tuberculosis in Fresno County. ▪ 1997/1998: One bird in downtown Fresno was discovered with exotic Newcastle disease, a contagious and fatal viral disease affecting all species of birds that does not affect humans. The bird and all chickens within a one-kilometer radius were destroyed. ▪ 1998: Freeze resulted in almost $70 million in losses, including crop loss, broken water pipes and water damage, damaged water treatment plants, and damaged fire sprinkler systems. Other impacts included almost 18,000 applications for services and assistance and over 1,700 unemployment insurance claims filed.
▪ 1999: Severe weather caused a crop loss of over $89 million. ▪ 2006: Fresno County growers were impacted by adverse spring weather with $21 million in losses. ▪ 2006: Twenty-one days of over 100 degrees, including three days over 113 degrees, caused crop, livestock, poultry, and milk production losses of $93 million. ▪ 2008: A Fresno County dairy was quarantined after state and federal agriculture officials found bovine tuberculosis in five cows.
▪ 2009: Short term drought with no or little allocation to the west side. Springtime hail brought damage to trees along the Kings River corridor.
▪ 2012 - 2016: Long-term western states drought. Billions in losses. ▪ 2014: Warm winter and spring brought a lack of chill hours affecting fruit set in cherry crop. ▪ 2019: no description available
▪ 2020: no description available
▪ 2021: no description available
▪ 2022: Highly Pathogenic Avian Influenza (HPAI) cases were confirmed in California commercial flock across the state including Fresno County. HPAI is a highly contagious and often datal disease in birds.
▪ 2023: Highly Pathogenic Avian Influenza (HPAI) cases were detected in a commercial flock in Fresno County. Infected flocks were euthanized to prevent further spread and the location was under quarantine.

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May 2024
21 Neighboring Counties
▪ 2002: Merced County had an outbreak of avian influenza H5 (which is different from the severe variety found in Asia).
▪ 2002/2003: After more than 10 years without a case of bovine tuberculosis in California, two dairy herds in Tulare County and one in Kings County were infected with bovine tuberculosis. All three herds were quarantined, 152,000 cattle were tested, 8,000 cattle destroyed, and the affected premises were cleaned and disinfected.
▪ 2002/2003: There was an outbreak of exotic Newcastle disease in Southern California. ▪ 2022: Highly Pathogenic Avian Influenza (HPAI) cases were confirmed in California commercial flock.
▪ 2023: Highly Pathogenic Avian Influenza (HPAI) cases were confirmed in California commercial flock.

According to data provided by the Farm Subsidy Database, total indemnities, and premium subsidies of the crop insurance program in the U.S., 1995-2022 include $172,457,906,536 total indemnities and $123,784,169,781 in total premium subsidies. The major cause behind crop yield or revenue that prompts an indemnity payment are largely due to natural hazard events such as drought, hail, or excessive rain. The top 10 national causes of loss with the largest indemnity payments from 1995 to 2022 are described in Table 14. Fresno County Indemnities by Hazard (1995-2022).

Table 14. Fresno County Indemnities by Hazard (1995-2022) Cause of Loss Indemnities Paid 1995-
2022
Percent of Total
Indemnities
Drought $60,391,798,966 35.0%
Excess Moisture/Precipitation $42,820,224,318 24.8%
GRP/GRIP/ARPI/SCO/STAX/MP/HIPWI Crops
Only* $13,350,536,562 7.7%
Hail $10,773,528,422 6.2%
Heat $8,509,718,490 4.9%
Decline in Price $7,797,184,357 4.6%
Freeze $5,143,337,715 3.0%
Wind/Excess Wind $3,546,363,004 2.1%
Cold Wet Weather $3,284,833,480 1.9%
Hot Wind $2,867,328,212 1.7%
Source: EWG, from USDA Risk Management Agency, Cause of Loss Historical Data Files. * Types of insurance policies; details on the RMA website. Indemnities for GRP/GRIP crops between 1995-2013; indemnities for ARPI, SCO, STAX, MP, HIP, WI crops 2014-2022, indemnities for ECO crops 2021 and 2022.

In Fresno County, the total amount of indemnities paid from 1995-2022 is 1,244,730,687. The breakdown of indemnities by crop and by cause are described in Table 15. Fresno County

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
22 Indemnities by Crops (1995-2022) and Table 16. Fresno County Indemnities by Cause of Loss (1995-2022).

Table 15. Fresno County Indemnities by Crops (1995-2022) Crops Indemnities Percent from 1995-2022
Other Crops 37.42%
Cotton Ex Long Staple 27.02%
Almonds 17.83%
Grapes 6.59%
Pistachios 6.51%
Tomatoes 4.64%
Source: EWG Farm Subsidy Database || Fresno County, California Crop Insurance Subsidies Table 16. Fresno County Indemnities by Cause of Loss (1995-2022) Cause of Loss Indemnities Percent from 1995-2022
Failure of Irrigation Supply 29.68%
Other Causes 20.37%
Heat 18.67%
Excess Moisture/Precipitation 16.49%
Freeze 8.81%
Cold Wet Weather 5.97%
Source: EWG Farm Subsidy Database || Fresno County, California Crop Insurance Subsidies

LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—As long as the hazards discussed in this section continue to be an ongoing concern to the Fresno County planning area, the potential for agricultural losses remains.

CLIMATE CHANGE CONSIDERATIONS
As climate change has progressed, noticeable changes have occurred with the climate and weather patterns across the globe. Weather events have become more numerous and more severe. Changes in weather patterns can have dramatic impacts on the ecosystem, including agriculture systems; more severe impacts can be expected into the future.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
23 AVALANCHE

HAZARD/PROBLEM DESCRIPTION
Avalanches occur when loading of new snow on a slope increases stress at a rate faster than strength develops, and the slope fails. Critical stresses develop more quickly on steeper slopes and where deposition of wind-transported snow is common. Most avalanches occur during and shortly after storms. This hazard generally affects a small number of people, such as snowboarders, skiers, and hikers, who venture into backcountry areas during or after winter storms. Roads and highway closures, damaged structures, and destruction of forests are also a direct result of avalanches. Avalanches typically occur above 8,000 feet and on slopes ranging between 25- and 50-degrees incline. The eastern portion of Fresno County is in the Sierra National Forest in a high alpine environment and has potential for areas above 8,000 on slopes ranging between 25- and 50-degrees incline. When avalanches occur, they can travel as fast as 200 miles per hour and can spontaneously. 2The combination of steep slopes, abundant snow, weather, snowpack, and an impetus to cause movement creates avalanches. Areas prone to avalanche hazards include hard to access areas deep in the backcountry. Avalanche hazards exist in eastern Fresno County in the Sierras, where combinations of the above criteria occur.

EXTENT
Small - Based on this information, the geographic extent rating for avalanches in Fresno County is limited and only impacts the mountainous area within the eastern part of the county. Occasional death and injury might occur to persons in the backcountry.

PAST OCCURRENCES
Historically, avalanches occur within the County between the months of December and April, following snowstorms. According to the HMPC, there has been some historical avalanche activity involving people, but specific details are unknown.

LIKELIHOOD OF FUTURE OCCURRENCES
Likely—Injuries and loss of life from an avalanche are usually due to people recreating in remote areas during the time of the avalanche. Given the topography and amount of snow falling on an annual basis in eastern Fresno County, avalanches will continue to occur, but damage from avalanches should continue to be limited.

CLIMATE CHANGE CONSIDERATIONS
In the future, the likelihood and nature of avalanches may be affected by climate change. As winter is taking longer to descend, weaker snow accumulates at the very bottom of the snowpack. As more snow piles on top of the weak layer, and temperatures remain warm, the upper, moisture- laden layers

2 Avalanches, facts and information (nationalgeographic.com) https://www.nationalgeographic.com/environment/article/avalanches

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
24 become vulnerable to sliding and create a delicate situation. More extreme precipitation events that deposit large amounts of snow in a short period of time could also periodically increase the potential for large avalanches.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
25 DAM FAILURE
Dams are manmade structures built for a variety of uses, including flood protection, power generation, agriculture, water supply, and recreation. When dams are constructed for flood protection, they usually are engineered to withstand a flood with a computed risk of occurrence. For example, a dam may be designed to contain a flood at a location on a stream that has a certain probability of occurring in any one year. If prolonged periods of rainfall and flooding occur that exceed the design requirements, that structure may be overtopped and fail. Overtopping is the primary cause of earthen dam failure in the United States.

Dam failures can also result from any one or a combination of the following causes:
▪ Earthquake
▪ Inadequate spillway capacity resulting in excess overtopping flows ▪ Internal erosion caused by embankment or foundation leakage or piping or rodent activity ▪ Improper design
▪ Improper maintenance
▪ Negligent operation
▪ Failure of upstream dams on the same waterway

According to the Association of State Dam Safety Officials, the causes of dam failures are most likely due to one of five reasons:

1. Overtopping: caused by water spilling over the top of a dam. Overtopping of a dam is often a precursor of a dam failure. These account for approximately 34 percent of all U.S. dam failures.

2. Foundation Defects: including settlement and slope instability, cause about 30 percent of all dam failures.

3. Cracking: caused by movements like the natural settling of a dam.

4. Inadequate maintenance and upkeep.

5. Piping: when seepage through a dam is not properly filtered and soil particles continue to progress, and form sink holes in the dam. About 20 percent of U.S. dam failures have been caused by piping.

The percentage of dam failure causes is shown in Figure 2. Dam Failure Primary Incident Mechanism, ASDSO Incident Database (2010-2019), with overtopping accounting for the majority of the incidents and cracking accounting for the least percentage of incidents.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
26 Source: ASDSO Incident Database

Water released by a failed dam generates tremendous energy and can cause a flood that is catastrophic to life and property. A catastrophic dam failure could challenge local response capabilities and require evacuations to save lives. Impacts to life safety will depend on the warning time and the resources available to notify and evacuate the public. Major loss of life could result as well as potentially catastrophic effects to roads, bridges, and homes. Associated water quality and health concerns could also be issues. Factors that influence the potential severity of a full or partial dam failure are the amount of water impounded; the density, type, and value of development and infrastructure located downstream; and the speed of failure. In general, there are three types of dams with different failure characteristics, described below:

▪ Concrete arch or hydraulic fill: A concrete arch or hydraulic fill dam can fail almost instantaneously: the flood wave builds up rapidly to a peak then gradually declines. ▪ Earth-rockfill: earth-rockfill dam fails gradually due to erosion of the breach: a flood wave will build gradually to a peak and then decline until the reservoir is empty. ▪ Concrete gravity: concrete gravity dam can fail instantaneously or gradually with a corresponding buildup and decline of the flood wave.

Figure 5. Dam Failure Primary Incident Mechanism, ASDSO Incident Database (2010-2019)

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
27 EXTENT
Extensive - According to the Fresno County Operational Area Master Emergency Services Plan, there are several hundred dams in Fresno County constructed for flood control, irrigation storage, electrical generation, recreation, and stock watering purposes. The National Inventory of Dams identifies 52 dams (see Table 17. Fresno County and Surrounding Areas Dams) that are located in or are of significance to Fresno County. Of these dams, 32 are considered high hazard, 4 are significant hazard, and 14 are low hazard. Several are located within Madera County and Kern County; however, they pose a threat to Fresno County based on the topography and hydrological flow characteristics of the area. According to the Fresno County Flood Control District, in a worst-case scenario of a hypothetical failure of a dam or its critical structures, such as spillways or outlet gates, the areas that would be impacted by flooding would including areas eat of the Highway 168, Areas to the west of Highway 99, and any neighborhood or business touching Highway 41. 3 Table 18. Fresno County Dams details the dams affecting Fresno County. The majority of these dams are in the San Joaquin River or Kings River watersheds in the eastern part of the county. Both incorporated and unincorporated areas are at risk of damage from flooding in the event of a dam failure, however, the City of Fresno, Clovis, Sanger and the eastern unincorporated county are at greater risk. Generally, the areas at risk are large urban and rural areas downstream and below the dams on the valley floor. There have not been any failures of major dams in Fresno County; future failures are more likely to occur with smaller dams, with minimal or no damage potential. Based on this information, the geographic extent rating for dam failure in Fresno County is extensive.

Table 17. Fresno County and Surrounding Areas Dams
Hazard Dam Name City Owner
Name Dam Type NID Storage
(Acre-Feet)
High Alluvial Drain
Detention Clovis
Fresno
Metropolitan
Flood
Control
District
Earth 832.7
High
Balsam
Meadow
Forebay Main
Big Creek
Southern
California
Edison
Company
Rockfill 1,960
High Big Creek Dam
No.1 Big Creek
Southern
California
Edison
Company
Concrete/Arch, Gravity 89,800
High Big Creek Dam
No.3 Big Creek
Southern
California
Edison
Company
Concrete/Gravity/Rockfill 89,800
High Big Creek Dam
No.6 Big Creek
Southern
California
Edison
Company
Concrete/Arch 1,726

3 The areas of Fresno at risk of flooding if a dam breaks | YourCentralValley.com | KSEE24 and CBS47 Fresno CA https://www.yourcentralvalley.com/digital-exclusive/the-areas-of-fresno-at-risk-of-flooding-if-a-dam-breaks/

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
28 Hazard Dam Name City Owner
Name Dam Type NID Storage
(Acre-Feet)
High Big Creek Dam
No.7 Auberry
Southern
California
Edison
Company
Concrete/Gravity 35,000
High Big Dry Creek Clovis
Fresno
Metropolitan
Flood
Control
District
Earth 30,200
High Courtright Balch Camp
Pacific Gas
and Electric
Company
Rockfill 134,342
High Crane Valley North Fork
Pacific Gas
and Electric
Company
45,410
High Fancher Creek Clovis
Fresno
Metropolitan
Flood
Control
District
Earth 9,600
High Fancher Creek
Detention Fresno
Fresno
Metropolitan
Flood
Control
District
Earth 1,891
High Florence Lake Mono Hot
Springs
Southern
California
Edison
Company
Concrete/Multi Arch 68,000
High Fresh Water
Pond** Old River CalMat Earth 46
High Friant Fresno
U.S. Bureau
of
Reclamation
Concrete, Gravity 520,500
High Friant Dike 3 Fresno
U.S. Bureau
of
Reclamation
Earth 555,500
High
Friant Millerton
Road
Embarkment A
Fresno
U.S. Bureau
of
Reclamation
Earth 555,500
High Giffen Reservoir Fresno Harris
Farms Inc Earth 900
High Hume Lake Barton’s Resort
USDA
Forest
Service
Concrete 0
High Little Panoche
Detention Oro Loma
U.S. Bureau
of
Reclamation
Earth 13,240
High Mammoth Pool* Big Creek Southern
California Earth 122,175

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
29 Hazard Dam Name City Owner
Name Dam Type NID Storage
(Acre-Feet)
Edison
Company
High Manzanita
Diversion North Fork
Pacific Gas
and Electric
Company
Concrete/Arch 168
High Pine Flat Dam Sanger
USACE-
Sacramento
District
Gravity 1,091,700
High Red Bank Clovis
Fresno
Metropolitan
Flood
Control
District
Earth 1,100
High Redbank Creek
Detention Basin Fresno
Fresno
Metropolitan
Flood
Control
District
Earth 940
High Sand Creek Orosi
Tulare Co
Resources
Managemen
t Agency
Earth 1,050
High Sequoia Lake YMCA Inc Earth 1,370
High Shaver Dike Shaver Lake
Southern
California
Edison
Company
Concrete/Arch/Gravity 135,568
High Shaver Lake Shaver Lake
Southern
California
Edison
Company
Concrete/Earth 135,568
High Silt Pond Coalinga Granite
Construction Earth 25
High Vermillion
Valley
Mono Hot
Springs
Southern
California
Edison
Company
Earth 140,000
High Wishon Main Wishon Village
Pacific Gas
and Electric
Company
Rockfill 133,600
High Mendota
Diversion* Firebaugh
Central Calif
Irrigation
District
Buttress 3,000
Significant Balch Afterbay Balch Camp
Pacific Gas
and Electric
Company
Concrete/Arch 325
Significant Blach Diversion Balch Camp
Pacific Gas
and Electric
Company
Concrete/Arch 1,295
Significant Big Creek Dam
No.5 Big Creek Southern
California Concrete/Arch 74

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
30 Hazard Dam Name City Owner
Name Dam Type NID Storage
(Acre-Feet)
Edison
Company
Significant Wishon
Auxiliary No.1 Wishon Village
Pacific Gas
and Electric
Company
Concrete/Gravity 133,600
Low
Balsam
Meadow
Forebay Dike
Big Creek
Southern
California
Edison
Company
Earth 1,960
Low Bear Creek
Diversion
Mono Hot
Springs
Southern
California
Edison
Company
Concrete/Arch 103
Low Big Creek Dam
No.3a Big Creek
Southern
California
Edison
Company
Concrete/Gravity/Rockfill 89,800
Low Big Creek Dam
No.4 Big Creek
Southern
California
Edison
Company
Concrete/Arch 100
Low Chilkoot* Bass Lake
Pacific Gas
and Electric
Company
Rockfill 308
Low Kerckhoff Friant
Pacific Gas
and Electric
Company
Concrete/Arch 4,252
Low Lemoore Div
Weir
Lemoore
Canal and
Irrigation
Company
Buttress 50
Low Mono Creek
Diversion
Mono Hot
Springs
Southern
California
Edison
Company
Concrete/Arch 45
Low Mud San Joaquin
James
Irrigation
District
Earth 304
Low Portal Forebay
Dike
Mono Hot
Springs
Southern
California
Edison
Company
Earth 390
Low Portal Forebay
Main
Mono Hot
Springs
Southern
California
Edison
Company
Earth/Rockfill 390
Low Reynolds Weir None
Laguna
Irrigation
District
Buttress 260

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
31 Hazard Dam Name City Owner
Name Dam Type NID Storage
(Acre-Feet)
Low San Joaquin
No.3 Forebay* North Fork
Pacific Gas
and Electric
Company
Earth 20
Low Stinson Weir
Stinson
Canal and
Irrigation
Company
Buttress 50
Low Wishon
Forebay* Friant
Pacific Gas
and Electric
Company
Earth 69
Source: 2024; National Inventory of Dams Note: 1 acre-foot=326,000 gallons Hazard: H=High, S=Significant, L=Low
*Madera County
**Kern County

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
32 Table 18. Fresno County Dams
Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
1017-5
Alluvial
Drain
Detention
Fresno
Metropoli
tan Flood
Control
District
12 833 Certified Satisfactory Fresno
CA01358 36.86 -119.67
Park,
sanitation
, utility, or
water
district
134 ERTH High No 1994
95-2 Balch
Afterbay
Pacific
Gas and
Electric
Company
139 1,295 Certified Satisfactory Fresno
CA00336 36.91 -119.09
Private
company
,
corporati
on, LLC,
partnersh
ip
235 CORA High No 1928
104-42 Balsam
Meadow
Southern
California
Edison
127 2,040 Certified Satisfactory Fresno
CA01283 37.16 -119.25
Private
company
,
corporati
on, LLC,
partnersh
ip
1,325 ROCK High No 1986
104-0 Bear Creek
Diversion
Southern
California
Edison
55 103 Certified Satisfactory Fresno
CA00428 37.34 -118.98
Private
company
,
corporati
on, LLC,
partnersh
ip
241 CORA Low No 1927
4 DAMS WITHIN JURISDICTION OF THE STATE OF CALIFORNIA DAMS LISTED ALPHABETICALLY BY COUNTY SEPTEMBER 2022 https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/All-Programs/Division-of-Safety-of- Dams/Files/Publications/Dams-Within-Jurisdiction-of-the-State-of-California-Listed-Alphabetically-by-County-September- 2022.pdf

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
33 Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
104-4 Big Creek
No.4
Southern
California
Edison
75 100 Certified Satisfactory Fresno
CA00430 37.2 -119.24
Private
company
,
corporati
on, LLC,
partnersh
ip
220 CORA Low No 1913
104-5 Big Creek
No.5
Southern
California
Edison
58 42 Certified Satisfactory Fresno
CA00431 37.2 -119.31
Private
company
,
corporati
on, LLC,
partnersh
ip
153 CORA Significant No 1921
104-6 Big Creek
No.6
Southern
California
Edison
140 993 Certified Satisfactory Fresno
CA00432 37.21 -119.33
Private
company
,
corporati
on, LLC,
partnersh
ip
485 CORA Low No 1923
104-22 Big Creek
No.7
Southern
California
Edison
223 35,000 Certified Satisfactory Fresno
CA00440 37.15 -119.45
Private
company
,
corporati
on, LLC,
partnersh
ip
893 GRAV Extremely High No 1951
1017-2 Big Dry
Creek
Fresno
Metropoli
tan Flood
Control
District
50 30,200 Certified Satisfactory Fresno
CA0175 36.89 -119.66
Park,
sanitation
, utility, or
water
district
25,300 ERTH Extremely High No 1948

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
34 Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
97-119 Courtright
Pacific
Gas and
Electric
Company
315 123,300 Certified Satisfactory Fresno
CA00412 37.08 -118.97
Private
company
,
corporati
on, LLC,
partnersh
ip
862 ROCK High No 1958
1017-4 Fancher
Creek
Fresno
Metropoli
tan Flood
Control
District
46 9,600 Certified Satisfactory Fresno
CA01327 36.85 -119.54
Park,
sanitation
, utility, or
water
district
15,312 ERTH Extremely High No 1991
1017-6
Fancher
Creek
Detention

Fresno
Metropoli
tan Flood
Control
District
16 1,891 Certified Satisfactory Fresno
CA01497 36.76 -119.61
Park,
sanitation
, utility, or
water
district
2,860 ERTH Extremely High No 2006
104-9 Florence
Lake
Southern
California
Edison
149 64,406 Certified Satisfactory Fresno
CA00433 37.27 -118.97
Private
company
,
corporati
on, LLC,
partnersh
ip
3,106 MULA Extremely High No 1926
699-0 Giffen
Reservoir
Harris
Farms,
Inc
29 900 Certified Satisfactory Fresno
CA00711 36.8 -119.44
Private
company
,
corporati
on, LLC,
partnersh
ip
1,250 ERTH High No 1971

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
35 Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
104-10 Huntington
Lake 1
Southern
California
Edison
170 88,834 Certified Satisfactory Fresno
CA00434 37.23 -119.24
Private
company
,
corporati
on, LLC,
partnersh
ip
1,310 GRAV Extremely High No 1917
104-25 Mammoth
Pond
Southern
California
Edison
406 123,000 Certified Satisfactory Fresno
CA00443 37.32 -119.32
Private
company
,
corporati
on, LLC,
partnersh
ip
820 ERTH Extremely High No 1960
1053-0 Mendota
Diversion
Central
California
Irrigation
District
23 3,000 Certified Satisfactory Fresno
CA00886 36.79 -120.37
Park,
sanitation
, utility, or
water
district
485 FLBT Significant No 1917
104-12 Mono Creek
Diversion
Southern
California
Edison
50 45 Certified Satisfactory Fresno
CA00436 37.36 -119
Private
company
,
corporati
on, LLC,
partnersh
ip
112 CORA Low No 1927
1085-0 Mud
James
Irrigation
District
14 304 Certified Satisfactory Fresno
CA00913 36.56 -120.17
Park,
sanitation
, utility, or
water
district
127 ERTH Low No 1919
104-24
Portal
Powerhous
e Forebay

Southern
California
Edison
65 325 Certified Satisfactory Fresno

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
36 Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
CA00442 37.32 -119.07
Private
company
,
corporati
on, LLC,
partnersh
ip
792 ERTH Low No 1955
1017-0 Redbank
Fresno
Metropoli
tan Flood
Control
District
33 1,100 Certified Satisfactory Fresno
CA00837 36.81 -119.58
Park,
sanitation
, utility, or
water
district
1,450 ERTH Extremely High No 1962
1017-3
Redbank
Creek
Detention
Basin

Fresno
Metropoli
tan Flood
Control
District
17 940 Certified Satisfactory Fresno
CA-1331 36.77 -119.66
Park,
sanitation
, utility, or
water
district
6,619 ERTH Extremely High No 1990
80-0 Reynolds
Weir
Laguna
Irrigation
District
13 260 Certified Satisfactory Fresno
CA00302 36.43 -119.67
Park,
sanitation
, utility, or
water
district
130 FLBT Low No 1928
693-0 Sequoia
Lake Y.M.C.A.,
Inc. 51 1,370 Certified Satisfactory Fresno
CA00709 36.73 -119
Private
company
,
corporati
on, LLC,
partnersh
ip
225 ERRK High No 1888
104-18 Shaver Lake
Southern
California
Edison
180 135,283 Certified Satisfactory Fresno
CA00437 37.15 -119.3
Private
company
,
corporati
2,169 GRAV Extremely High No 1927

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
37 Dam
No.4 Dam Number Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment County
National
ID No. Lat. Long. Owner
Type
Crest
Type
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
on, LLC,
partnersh
ip
696-0 Stinson
Weir
Stinson
Canal
and
Irrigation
Company
14 50 Certified Satisfactory Fresno
CA00710 36.46 -119.99
Private
company
,
corporati
on, LLC,
partnersh
ip
256 FLBT Low No 1910
104-23 Vermillion
Valley
Southern
California
Edison
167 125,000 Certified Satisfactory Fresno
CA00441 37.37 -119
Private
company
,
corporati
on, LLC<
partnersh
ip
4,234 ERTH Extremely High No 1954
97-118 Wishon
Pacific
Gas and
Electric
Company
265 118,000 Certified Satisfactory Fresno
CA00411 37.01 -118.97
Private
company
,
corporati
on, LLC,
partnersh
ip
3,328 ROCK High No 1958
Source: California Department of Water Sources, Division of Safety of Dams, Dams within Jurisdiction of the State of California, September 2022

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
38 Both unincorporated and incorporated areas of the County are identified on dam failure inundation maps included in the County’s dam failure evacuation plan. The inundation areas for each of the dams are generally downstream and include large rural and urban areas on the valley floor below the dams.

Adjacent jurisdictions could also be affected by a dam failure in Fresno County. These include, depending on the dam involved, the Counties of Tulare, Kings, Madera, and Merced. Figure 3. Fresno County Dams by Hazard Classification illustrates the locations of identified dams of concern within Fresno County. Figure 4. Fresno County Dams by Capacity shows a map of dams in Fresno County and their hazard class, while Figure 5. Water Routes and Dams that Impact Fresno County shows the water routes and the dams that impact Fresno County.

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39 Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS; US Army Corps of Engineers Note: California identifies 4 dam hazard classifications, while the NID identifies 3 dam hazard classifications.

Figure 6. Fresno County Dams by Hazard Classification

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40 Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS; US Army Corps of Engineers

Figure 7. Fresno County Dams by Capacity

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41 Source: Fresno County Operational Area Dam Failure Evacuation Plan, 2003

Figure 8. Water Routes and Dams that Impact Fresno County

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42 PAST OCCURRENCES
According to the National Performance of Dams Program at Stanford University, there have been 32 dam incidents based on the list of dams that impact Fresno County in Table 19. Fresno County Previous Dam Incidents. Two of the incidents were Uncontrolled Release of Reservoir (URR) which is an incident that involves damage to a dam and is an uncontrolled release. A few of the previous dam incidents were due to penstock leaks and ruptures, sinkholes, embarkment instability, earthquakes, inflow flooding, piping, unknown causes, or the cause was not documented. The incidents impacting Fresno County dates to January 1, 1916, to October 27, 2021. Based on past occurrences, there has been a dam incident about every 3 years. The majority of the incidents were dam types such as concrete, rockfill, and gravity. The dams with multiple incidents include Big Creek Dam 3a, 4, 5, and 6, Crane Valley, Florence Lake, Mammoth Pool, and Mud Lake. More information on dam incidents is described in the table below.

Table 19. Fresno County Previous Dam Incidents
Dam Name Incident Date Incident Type Dam Type
Uncontrolled
Release of
Reservoir (URR)
Balch Diversion 6/8/1998 Earthquake Arch No
Bear Creek
Diversion 8/6/2003 Penstock Rupture Unknown No
Big Creek Dam 5 10/27/2021 Unknown Concrete Unknown
Big Creek Dam No.
3a 6/8/1998 Earthquake Gravity No
Big Creek Dam No.
3a 6/14/1996 Penstock Rupture Gravity No
Big Creek Dam No. 4 6/14/1996 Unknown Concrete No
Big Creek Dam No. 4 1/5/2010 Unknown Concrete; Arch No
Big Creek Dam No. 4 6/8/1998 Earthquake Concrete; Arch No Big Creek Dam No. 5 6/8/1998 Earthquake Concrete; Arch No Big Creek Dam No. 5 3/10/1995 Unknown Concrete; Arch No Big Creek Dam No. 6 1/3/1997 Unknown Concrete No
Big Creek Dam No. 6 1/2/1997 Unknown Concrete No
Big Creek Dam No. 6 6/8/1998 Earthquake Concrete; Gravity No Big Creek Dam No. 7 6/8/1998 Earthquake Gravity No
Courtright 6/8/1998 Earthquake Rockfill No
Crane Valley 3/13/2012 Sinkhole Rockfill No
Crane Valley 12/17/2009 Unknown Rockfill No
Crane Valley 6/8/1998 Earthquake Rockfill No
Crane Valley 3/22/2011 Embankment
Instability Unknown No
Florence Lake 5/12/2011 Unknown Concrete No
Florence Lake 5/15/1999 Not Known Concrete No
Florence Lake 6/8/1998 Earthquake Concrete No
Mammoth Pool 2/16/2016 Sinkhole Rockfill No

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43 Dam Name Incident Date Incident Type Dam Type
Uncontrolled
Release of
Reservoir (URR)
Mammoth Pool 6/8/1998 Earthquake Rockfill No
Mendota Diversion 1/1/1916 Piping Unknown Unknown
Mono Creek
Diversion 6/8/1998 Earthquake Concrete; Arch No
Mud Lake 1/1/1982 Not Known Rockfill Yes
Mud Lake 1/1/1932 Inflow Flood -
Hydrologic Event Rockfill Yes
Portal Forebay Dike 5/15/1999 Earthquake Rockfill No
San Joaquin No. 3
Forebay 12/17/2016 Penstock Leak Unknown No
Shaver Lake 6/8/1998 Earthquake Gravity No
Wishon Auxiliary
No. 1 6/8/1998 Earthquake Rockfill No
Source: Stanford, NPDP Dam Incident Database

According to the Fresno County Operational Area Master Emergency Services Plan, there were 14 dam failures in Fresno County between 1976 and 1983, but all were earthen dams on private property.

None of the County’s 23 major dams were involved. The failures were due to inadequate rodent and vegetation control, unauthorized and inadequate construction, and failure to consult an engineer. The main impacts from these failures were silting of downstream waters, properties, and dams; flooded or undermined roadways; and eroded embankments. Main losses were flooding of a residence and construction lumber washed downstream. In 1986, Friant Dam experienced a small, uncontrolled release. The lock on the drum gate opened, releasing 3,000 cubic feet per second. No major flooding resulted. One incident that was not captured in the NPDP Dam Incident Database was the Friant Dam incident that occurred on January 3, 1997. Stormwater breached the Friant Dam sending a historic 59,000 cubic feet of water a second cascading down the San Joaquin River, laying waste to the bridge a few hundred feet downstream from the dam. 5

▪ 4/02/2018: At the Auberry Lumber Mill, the dam's spillway pipes became obstructed by overgrown vegetation, leading to water overtopping the structure. This overtopping resulted in erosion of the dam's downstream slope, a situation that had the potential to escalate to a dam failure. Fortunately, this event did not necessitate any evacuations, nor did it result in any reported damages.

Dam failures can occur very quickly depending on the severity of the event and what caused the failure to occur. Additionally, planned releases of dam can occur in order to mitigate flood risk from heavy rain events. For example, The Oroville Dam released billions of gallons of water in February 2024 to reduce flood risk from several recent atmospheric river events that produced heavy rain in California. This was

5 In 1997, California was devastated by historic floods (sfgate.com) https://www.sfgate.com/bayarea/article/1997-historic-floods- devastated-california-17697232.php

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44 an effort to protect downstream communities from flood risk. 6 Planned releases can occur over several hours or days depending on how much water is being released.

LIKELIHOOD OF FUTURE OCCURRENCES
Possible—The County remains at risk of dam failures from numerous dams under a variety of ownership and control and of varying ages and conditions. Given the high number of dams in the County and the history of past dam failures, the potential exists for future dam failures in the Fresno County planning area. Nonetheless, it should be noted that there have not been any failures of major dams in the County. Uncontrolled or controlled release flooding below dams due to excessive rain or runoff are more likely to occur than failures.

CLIMATE CHANGE CONSIDERATIONS
The potential for climate change to affect the likelihood of dam failure is not fully understood at this point in time. With a potential for more extreme precipitation events as a result of climate change, this could result in large inflows to reservoirs. However, this could be offset by generally lower reservoir levels if storage water resources become more limited or stretched in the future due to climate change, drought and/or population growth.

6 California Reservoir 'Spectacular' Release of Billions of Gallons of Water (newsweek.com) https://www.newsweek.com/california- reservoir-spectacular-release-billions-gallons-water-1866518

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45 DROUGHT

HAZARD/PROBLEM DESCRIPTION
Drought is a gradual phenomenon. Although droughts are sometimes characterized as emergencies, they differ from typical emergency events. Most natural disasters, such as floods or forest fires, occur relatively rapidly and afford little time for preparing for disaster response. Droughts occur slowly, over a multi-year period, and it is often not obvious or easy to quantify when a drought begins and ends.

Drought is a complex issue involving many factors—it occurs when a normal amount of moisture is not available to satisfy an area’s usual water-consuming activities. Drought can often be defined regionally based on its effects:

▪ Meteorological drought is defined by a period of substantially diminished precipitation duration and/or intensity. The commonly used definition of meteorological drought is an interval of time, generally in the order of months or years, during which the actual moisture supply at a given place consistently falls below the climatically appropriate moisture supply. ▪ Agricultural drought occurs when there is inadequate soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought usually occurs after or during meteorological drought, but before hydrological drought and can affect livestock and other dry-land agricultural operations.
▪ Hydrological drought refers to deficiencies in surface and subsurface water supplies. It is measured as stream flow, snowpack, and as lake, reservoir, and groundwater levels. There is usually a delay between lack of rain or snow and less measurable water in streams, lakes, and reservoirs. Therefore, hydrological measurements tend to lag behind other drought indicators. ▪ Socio-economic drought occurs when physical water shortages start to affect the health, well- being, and quality of life of the people, or when the drought starts to affect the supply and demand of an economic product.

One dry year does not normally constitute a drought in California. California’s extensive system of water supply infrastructure—its reservoirs, groundwater basins, and inter- regional conveyance facilities—mitigates the effect of short-term dry periods for most water users. Defining when a drought begins is a function of drought impacts to water users. Hydrologic conditions constituting a drought for water users in one location may not constitute a drought for water users elsewhere, or for water users having a different water supply. Individual water suppliers may use criteria such as rainfall/runoff, amount of water in storage, or expected supply from a water wholesaler to define their water supply conditions.

The drought issue in California is further compounded by water-rights. Water is a commodity possessed under a variety of legal doctrines. The prioritization of water rights between farming and federally protected fish habitats in California is part of this issue.

Drought impacts are wide-reaching and may be economic, environmental, and/or societal. The most significant impacts associated with drought in the planning area are those related to water intensive activities such as agriculture, wildfire protection, municipal usage, commerce, tourism, recreation, and wildlife preservation. Also, during a drought, allocations go down, which results in reduced water availability. Voluntary water conservation measures are typically implemented during extended droughts. A reduction of electric power generation and water quality deterioration are also potential

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46 problems. Drought conditions can also cause soil to compact which reduces its ability to absorb water, potentially making an area more susceptible to flooding.

TREE MORTALITY
The HMPC identified tree mortality as an additional drought impact of significance to Fresno County during the 2018 update. In recent years, due to the multi-year drought throughout the planning area and state-wide, a vast number of trees have been (and continue to be) impacted within Fresno County foothill and mountain communities and beyond. Standing dead trees could fall and pose a risk to people, buildings, power lines, roads, and other infrastructure. In addition, drought-impacted trees become susceptible to diseases and insect infestations (bark beetle) further adding to the risk of tree mortality and related potential impacts.

The location, extent, and probability of occurrence for tree mortality can be viewed as sub-set to the drought hazard. Those areas of the natural environment susceptible to drought comprise a larger area, since tree mortality is related to other sub-factors specific to the species impacted such as tree age and soil composition. Figure 6. Fresno County Drought Related Tree Mortality High Hazard Zones shows the extent of the impact of drought and tree mortality in Fresno County. The Tier 1 High Hazard Zones (as indicated in red) depict areas where tree mortality directly coincides with critical infrastructure.

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47 Source: CA Geoportal; CalFire – Fire Resources & Assessment Program (FRAP), 10/2022; County of Fresno - GIS

Figure 9. Fresno County Drought Related Tree Mortality High Hazard Zones

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48 EXTENT
Given the historical occurrence of severe drought impacts throughout Fresno County and across the state, the HMPC understands that drought will continue to pose a high degree of risk to the entire planning area, potentially impacting crops, livestock, water resources, the natural environment at large, buildings and infrastructure (from land subsidence), and local economies. While drought affects the entire planning area equally, the potential impacts may be variable and specific to each jurisdiction, depending on contextual factors such as the degree of assets and activities historically impacted by drought within each jurisdiction, such as the agricultural and parks and tourism industries.

Figure 7. U.S. Drought Monitor: California (January 23, 2024) and Figure 8. U.S. Drought Monitor:

California (January 23, 2018) below provide a “snapshot in time” of the drought conditions in California in January 2024 and January 2018 when the plan was last updated. The snapshots selected are instrumental in depicting both the historic and potential change in drought’s geographic range and severity in Fresno County. Compared to 2018, drought conditions across California state have significantly improved due to the increased precipitation in early 2023. The majority of the state experienced no drought conditions while some small areas in northern and southern California experienced abnormally dry conditions. These two figures alone show the duality of drought conditions over the span of a couple of years.

The magnitude or intensity of drought is measured by the U.S. Drought Monitor (USDM) through maps that are updated weekly to show the location and intensity of drought across the country. The USDM identifies areas in drought and labels them by intensity using four categories of drought, D1 (the least intense) to D4 (the most intense). It also describes areas with no drought and uses the D0 category to indicate abnormally dry areas that could be entering or recovering from drought, Table 20. U.S.

Drought Monitor Drought Categories.

Table 20. U.S. Drought Monitor Drought Categories
Category Description
None
(Gray) Normal or wet conditions
D0
(Light Yellow) Abnormally Dry
D1
(Light Orange) Moderate Drought
D2
(Orange) Severe Drought
D3
(Red) Extreme Drought
D4
(Maroon) Exceptional Drought
Source: U.S. Drought Monitor
Other drought indices have been developed by the National Oceanic and Atmospheric Administration (NOAA) to measure impacts and severity of meteorological and hydrological drought and to map their extent and locations.

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49 ▪ The Crop Moisture Index: measures the short-term drought weekly to assess impacts on agriculture.
▪ The Palmer Z Index: measures the short-term drought on a monthly scale. ▪ The Palmer Drought Severity Index: is based on long-term weather patterns. The intensity of drought in each month is dependent on current weather plus the cumulative patterns of previous months.
▪ 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: only considers precipitation.

To ensure that the State of California can maintain safe, clean, and reliable water service, Cal Water follows a set of drought severity stages to determine the level of water conservation and assess potential water-use restrictions described in Table 21. California Drought Severity Stages.

Table 21. California Drought Severity Stages
Stage Description
1 • We implement policies and guidelines for reducing water usage by 10 percent. • Residential and business customers are subject to water-use restrictions • Outdoor irrigation is subject to limited times
• Leak repairs must be made in a timely manner
• Shut-off nozzles are required when using a hose to wash a car • Outdoor watering is prohibited within 48 hours of rain 2 • We implement policies and guidelines for reducing water usage by 20 percent • Residential and business customers are subject to additional water-use restrictions • Outdoor irrigation by residential and business customers is limited further to 1-3 days per week, depending on local ordinance
• Use of non-recirculating systems in all new conveyer car wash and commercial laundry systems are prohibited
• Use of single pass cooling systems in new connections is prohibited 3 • We implement policies and guidelines for reducing water usage by 30 percent • Residential and business customers are subject to additional water-use restrictions • Water usage for construction and dust control is prohibited • Irrigation of ornamental turf on public street medians is prohibited • Filling ornamental lakes or ponds is prohibited
4 • We implement policies and guidelines for reducing water usage by 40 percent • Residential and business customers are subject to additional water-use restrictions • Vehicle washing is prohibited, except with recirculated water or low-volume systems • Use of water for recreational purposes, such as water parks, is prohibited • Filling swimming pools is prohibited
5 • We implement policies and guidelines for reducing water usage by 50 percent • Residential and business customers are subject to additional water-use restrictions • Net zero demand increase is required on new water service connections • Single pass cooling systems are prohibited

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50 Stage Description
• Swimming pool covers are required
6 • We implement policies and guidelines for reducing water usage by more than 50 percent • Residential and business customers are subject to additional water-use restrictions • All landscape irrigation is prohibited
• New water service connections are prohibited
Source: California Water Service: https://www.calwater.com/help/drought-faqs/what-are-the-stages-of-drought/

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51 Source: U.S. Drought Monitor

Figure 10. U.S. Drought Monitor: California (January 23, 2024)

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52 Source: U.S. Drought Monitor

TREE MORTALITY EXTENT
Extensive - The US Forest Service (USFS), Pacific Southwest Region, State and Private Forestry staff conduct annual aerial surveys throughout forested areas of California to detect tree mortality and tree damage (i.e., defoliation or branch flagging). The survey found approximately 39.6 million acres were surveyed during the 2022 flight season and 36.3 million dead trees. The majority of the trees killed were fir, followed by ponderosa pine, and Douglas fir. The elevated levels of tree mortality can be attributed to the ongoing drought period (2020-2023) and bark and engrave beetle attacks.7 The California/Shasta red fir, white fir, and grand fir mortality was attributed to fir engraver beetle increased in 2022. Approximately 28.1 million dead fir trees were recorded across 1.9 million acres, compared to approximately 6.1 million dead fir trees across 780,000 acres recorded in 2021. The central Sierra Nevada Region experienced the tree mortality that was most severe and widespread.

Within Fresno County, there are several national parks and forests. In fact, the Sequoia and Sierra forests have increased tree mortality in 2022 compared to 2021. Table 22. Tree Mortality by National Forest shows the National Forests and acres with mortality and estimated number of dead trees by Forest (2022).

7 2022 Aerial Survey Results: California (usda.gov) https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fseprd1099786.pdf Figure 11. U.S. Drought Monitor: California (January 23, 2018)

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53 ▪ Sequoia: Mortality increased from an estimated 380,000 dead trees across 64,000 acres in 2021 to approximately 410,000 dead trees across 75,000 acres in 2022. Most of the mortality was light in severity except for moderate levels of mortality along southern Hume Lake District o California red fir mortality decreased from approximately 230,000 dead trees across 34,000 acres in 2021 to ~200,000 dead trees across 35,000 acres in 2022. o White fir mortality increased from approximately 100,000 dead trees across 17,000 acres in 2021 to ~110,000 dead trees across 19,000 acres in 2022. ▪ Sierra: Mortality increased from an estimated 860,000 dead across 91,000 acres in 2021 to approximately 1.7 million dead trees across 180,000 acres in 2022 o California red fir mortality increased from approximately 790,000 dead trees across 75,000 acres in 2021 to ~1.5 million dead trees across 150,000 acres in 2022. o White fir mortality increased from approximately 13,000 dead trees across 5,500 acres in 2021 to ~130,000 dead trees across 26,000 acres in 2022.

Table 22. Tree Mortality by National Forest
National Forest Acres Dead Trees
Angeles National Forest 1,100 10,000
Cleveland National Forest 1,500 8,000
Eldorado National Forest 91,000 1,300,000
Humboldt-Toiyabe National Forest* 50,000 750,000
Inyo National Forest* 78,000 880,000
Klamath National Forest* 140,000 1,800,000
Lake Tahoe Basin Management Unit 58,000 1,400,000
Lassen National Forest 170,000 1,900,000
Los Padres National Forest 12,000 59,000
Mendocino National Forest 40,000 550,000
Modoc National Forest 180,000 2,200,000
Plumas National Forest 110,000 1,600,000
San Bernardino National Forest 3,900 13,000
Sequoia National Forest 75,000 410,000
Shasta-Trinity National Forest 290,000 4,400,000
Sierra National Forest 180,000 1,700,000
Six Rivers National Forest 24,000 150,000
Stanislaus National Forest 140,000 2,600,000
Tahoe National Forest 260,000 5,000,000
The numbers of acres and trees throughout this report have been rounded as appropriate. *include acreage outside of California but within the National Forest Boundary.

The Tree Mortality Task Force mapping effort (see previous map) identifies Tier 1 and Tier 2 risk zones to fully capture the extent of tree mortality risk to populations, buildings, infrastructure, and natural

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54 resources. Tier 1 are those areas that directly coincide with critical infrastructure, and which pose a direct threat to people and assets operating in these areas. Tier 2 are areas defined by watersheds and which have a significant degree of tree mortality coinciding with significant community and natural resource assets. 8
Based on the mapping as well as input from the LHMPC, the extent of the Tree Mortality Tier I and II Hazard Areas in Fresno County comprises over 25 percent of the planning area and therefore covers an extensive area in Fresno County.

PAST OCCURRENCES
Historically, California has experienced multiple severe droughts. According to the DWR, droughts exceeding three years are relatively rare in Northern California, and the region is the geographic source of much of the state’s developed water supply. According to the “Water Year 2023: Weather Whiplash, From Drought to Deluge” from the California Department of Water Resources, California Natural Resources Agency, stated in their report that 2023 demonstrated dramatic extremes of California’s climate. At the beginning of the year, California had the three driest years on record that prompted the Governor to issue a proclamation of a state of emergency for Fresno County described in the table below. The storms from 2023 have provided relief from the water shortages of the prior drought years due to atmospheric rivers, tropical storms, and hurricane events.

The 1929-1934 drought established the criteria commonly used in designing storage capacity and yield of large Northern California reservoirs. Table 23. Severity of Extreme Droughts in the Sacramento and San Joaquin Valleys below compares the 1929-34 drought in the Sacramento and San Joaquin Valleys to drought periods in 1976-77, and 1987-92, 2012-17, and 2020-2023. The driest single year of California’s measured hydrologic record was 2022.9

Table 23. Severity of Extreme Droughts in the Sacramento and San Joaquin Valleys Drought
Period
Sacramento Valley Runoff San Joaquin Valley Runoff
(maf*/yr) (% Average 1901-
96) (maf*/yr) (% Average 1906-96)
1929-34 9.8 55 3.3 57
1976-77 6.6 37 1.5 26
1987-92 10.0 56 2.8 47
2012-17 N/A 43 N/A N/A
2020-23 N/A N/A N/A N/A
Source: California Department of Water Resources, www.water.ca.gov/ *Million acre-feet

The HMPC identified the following droughts as having significant impacts on the planning area:

8 CAL FIRE
9 2022 Is California's Record Driest Year, So Far, NOAA Says | Weather.com https://weather.com/news/climate/news/2022- 07-11-june-record-driest-noaa-climate-report

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55 ▪ 1928-1934: This seven-year drought predated the construction of many of the water projects in California including the Federal Central Valley Project and State Water Project. Because the 1928- 34 drought constituted the first major drought on record in California, it served as the basis for early reservoir operations planning and the development of shortage criteria for water supply contracts. ▪ 1976: A federal disaster declaration was declared because of a drought affecting Fresno County and much of California.
▪ 1987-1992: Fresno County also suffered adverse effects resulting from this statewide drought. ▪ 2002: Abnormally dry to moderate drought conditions lingering from 2001 into 2002 reduced rangeland grasses and feed for cattle. Losses to rangeland and loss of feed were estimated at $2.5 million. An estimated 850,000 acres were affected in both the east and west side of the valley. A USDA disaster declaration on November 22 made low interest loans available to family-size operations.
▪ 2008: Drought impacted Fresno County of most of the Central valley, resulting in significant crop damage. In addition, the drought not only impacted agriculture, but the economy of the planning area in general, where small towns were especially hard hit, including job loss and the need for food-supply assistance provided by the state.
▪ 2012-2017: Drought produced severe impacts to water wells throughout the planning area, with a high number of wells running dry. Land subsidence due to increased groundwater pumping also occurred in areas of the San Joaquin Valley including Fresno County. Crop damage was widespread as well. Water allotments were drastically reduced in many towns and water agencies, with extremely high costs for procuring water. In addition, job loss occurred with many families requiring food supply assistance, and water supply assistance provided to homeowners with dry wells. According to a report released by UC Davis Center for Watershed Sciences, the 2014 California drought cost the state's agriculture industry about $1 billion in lost revenue, with a total statewide economic cost of the drought calculated to be $2.2 billion. The 2014 drought, the report says, is responsible for the greatest water loss ever seen in California agriculture - about one third less than normal. The report calls the groundwater situation in California "a slow-moving train wreck." Spring snowpack at Donner Summit reached record low levels in 2014, exceeded in 2015 by a remarkable April 1 snow- water-equivalent value of only 5 percent of average. Decreased precipitation since contributed to near-record low levels in the Shasta Reservoir. The ongoing drought has contributed to declines in Fresno County crop values, based on information from an article in the Fresno Bee. Fresno County's overall gross value fell 2.2 percent to $6.4 billion in 2013, and with the reduction lost its status as the number one agricultural county in California. The Fresno County Agricultural Commissioner noted the drought -- one of the worst in state history -- has pinched the production of several west side field crops including cotton, corn silage and barley. The field crop category fell by 42 percent 10
▪ 2020-2023: The three-year drought is the most recent drought period. The state ranked driest on record for much of 2022, including driest ever January-March, January-May, and January-October.

Drought conditions started on February 11, 2020, and ended October 10, 2023. Overall, the state experienced 76 percent of its average precipitation in 2022. The beginning of 2022 was the direst January through April based on records dating back to 1895 and received only 25 percent of the average statewide precipitation. In addition to a lack of precipitation, a persistent heat dome settled over California in early September that was long-lasting and intense, setting numerous daily and

10 California - State Climate Summaries 2022 (ncics.org) https://statesummaries.ncics.org/ca /

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56 nightly high temperatures records. The majority of California did not receive any precipitation for a record-breaking 212 days. This drought period was the hottest and driest since at least 1895. 11

LIKELIHOOD OF DROUGHT OCCURRENCES
Possible —Historical drought data for the Fresno County planning area and the Central Valley region indicate there have been six significant droughts and 26 years of were classified as a drought year in the last 96 years. This equates to a 27 percent chance of a drought in any given year. Based on this data, droughts will likely affect the planning area.

Using the data from the U.S. Drought Monitor from 2000-2024, Fresno County has experienced moderate (D1) to exceptional drought (D4) about 77 percent of the time, up from 60 percent from the last plan update. The U.S. Drought Monitor produces weekly reports and of the 1251 weekly reports that had been produced, when the data was pulled in on January 30th, 2024, 958 weekly reports indicated that Fresno County experienced some level of drought. Figure 9. Fresno County Percent Area in U.S. Drought Monitor Categories (2000-2023) depicts a drought time series from January 2000 to January 2024 for Fresno County.

Source: U.S. Drought Monitor

LIKELIHOOD OF TREE MORTALITY OCCURRENCE
Highly Likely - Based on historical data in lack of precipitation and increased temperatures, it is a certainty that tree mortality resulting from drought and insect infestation will continue in the future, though the degree to which it occurs depends on future rainfall levels and other factors. Some of the current challenges include how to eradicate the bark beetle, dead tree removal strategies, how to utilize the wood once it is removed, and how to restore the forests to a sustainable ecosystem. 12

11 Statewide Rankings | Climate at a Glance | National Centers for Environmental Information (NCEI) (noaa.gov) https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/statewide/rankings/4/pcp/202209 12 http://frap.fire.ca.gov/projects/projects_drought
Figure 12. Fresno County Percent Area in U.S. Drought Monitor Categories (2000-2023)

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57 CLIMATE CHANGE CONSIDERATIONS
In California, rising temperatures are projected to increase the average lowest elevation at which snow falls, reducing water storage in the snowpack, particularly at those lower mountain elevations which are now on the margins of reliable snowpack accumulation. This is especially concerning as mountain snowpack provides as much as a third of California’s water supply by accumulating snow during wet winters. Higher spring temperatures will also result in earlier melting of the snowpack. The shift in snow melt to earlier in the season is critical for California’s water supply because flood control rules require that water be allowed to flow downstream, and that water cannot be stored in reservoirs for use in the dry season. It is projected that by the end of the century, California’s Sierra Nevada snowpack is projected to experience a 48 to 65 percent loss from the historical April 1 average and will have a significant decrease in snowpack impacting water supply and crop production.

WATERSHED AND ECOSYSTEMS
Climate change will likely adversely impact the ability of watersheds and ecosystems to deliver important ecosystem services such as clean water, fertile soil for crop production, and flood control.

There is a broad range of climate change impacts that affect water resources in California which can be seen in Table 24. Summary of Climate Change Impacts on Water Resources. These changes may limit the natural capacity of healthy forests to capture water and regulate stream flows.

Table 24. Summary of Climate Change Impacts on Water Resources Resource Type of Impact Description
Sea Level Direct Sea level is rising and will likely impact coastal areas
Soil Moisture Direct
Prolonged dry seasons can lead to
decreases in soil moisture; drier
vegetation
Vegetation Indirect Longer and more intense fire season with increased extent of area burned
Stream Conditions Direct Increases in water temperature; potential effects on fish
Snowpack Indirect Increases in temperature will lead to decreases in snowpack
Runoff Direct
Warmer temperatures are likely to lead
to a shift in peak runoff from spring to
winter and a likely decrease in summer
baseflow
Hydropower Indirect
Decreased summer flows resulting
from earlier snowmelt and a shift in
peak runoff could affect hydropower
generation during summer months
Precipitation Direct
Warmer winter temperatures will result
in a greater percentage of precipitation
falling as rain rather than as snow
Groundwater Indirect Reduction in snowpack and extended periods of drought are likely to
increase dependency on groundwater

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58 Source : http://frap.fire.ca.gov/data/assessment2010/pdfs/3.1water.pdf p. 140

SNOWFALL AND SNOWPACK
In the southern portion of the Sierra Nevada, temperatures are generally cooler, and more precipitation falls as snow than the central and northern portions of the range due to higher elevations. However, average annual precipitation decreases gradually moving southward because of the position of the jetstream in northern California and the Pacific Northwest during winter. In general, precipitation varies greatly in the Sierra Nevada region with historical annual precipitation ranging from 50 to 200 percent of average. Weather phenomena such as the El Nino Southern Oscillation, contribute to these variabilities.

Increased winter temperatures have resulted in more precipitation falling as rain rather than snow and reduced snowpack in my parts of the Sierra Nevada. Reduce snowpack and earlier snowmelt have led to earlier timing of streamflow in the region. According to the Fourth California Climate Assessment report, by 2050 the average water supply from snowpack is projected to decline to two-thirds from historical levels. If emission reductions do not occur, water from snowpack could fall to less than one- third of historical levels by 2100 which will have significant impacts on California’s water management system. However, during the 2022 water year the State of California experienced record-breaking precipitation with one of the largest snowpack years on record. The 2022 water year alleviated drought conditions however brought flooding concerns across the state, including in Fresno County. 13 As such, Fresno County potentially has less capacity to address future drought (and wildfire) risk related to climate change due to projected temperature increases and shortages in water. About 85 percent of Californians depend on groundwater for some portion of their water supply. In fact, in some basins, groundwater withdrawal exceeds the amount is replenished long-term. 14 Groundwater overdraft in some agricultural regions averages about 2 million acre-feet annually, where the impacts of drought include decreased availability of water for agriculture and environmental uses. In forested and other vegetated areas, prolonged drought decreases the moisture content of forest fuels and increases the risk of high severity wildfires.

California is the single most productive agricultural state with Fresno County and the San Joaquin Valley being a key factor to such productivity. The agricultural industry relies heavily on reservoir water supplied by snowmelt and rainfall runoff. Yearly variations in snowpack depths have implications for water availability as snowmelt from the winter snowpack feeds a network of reservoirs. California snowpack over the past several years is described in the figure below. The 2022-2023 season was one of the highest snowpack levels since the 1982-1983 season.

13 https://water.ca.gov/News/News-Releases/2023/April-23/Snow-Survey-April-2023 14 https://www.ppic.org/publication/groundwater-in-california/

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59 Source: California Department of Water Resources, Historical Snowpack Comparison

As such, the HMPC understands that high degree of risk posed by drought will be exacerbated by greater climate variation in the future, which, in this case, means greater variation and uncertainty regarding the availability of water supplies which are already under tremendous stress. The HMPC will continue to explore solutions for mitigating the drought hazard by accessing the best available data and resources on climate change and its relationship to drought.

Figure 13. California Snow Water Content Percent of April 1 Average (January 31, 2024)

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60 EARTHQUAKE

HAZARD/PROBLEM DESCRIPTION
An earthquake occurs when two blocks of the earth suddenly slip past one another creating a vibration through the release of energy in the earth’s crust. The vibrations that are generated are called “seismic waves”. The surface where they slip is called the fault or fault plane. Earthquakes can result in ground shaking, soil liquefaction, landslides, fissures, avalanches, fires, and tsunamis. Additionally, earthquakes can cause buildings to collapse and cause heavy items to fall, resulting in injuries and property damage. They happen anywhere and at any time.

A fault is a fracture or zone of fractures between two blocks of rock. Faults allow blocks to move relative to each other. The movement may occur rapidly, in the form of an earthquake – may occur slowly, in the form of creep. There are major faults which include Normal, Reverse, Strike-Slip, and Oblique Slip Faults. Fresno County has major active or potentially active faults, including the Ortigalita Fault in the Panoche Valley and the Nunez Fault northwest of Coalinga. The Clovis Fault is a concealed fault near Clovis but is not considered to be active currently. Active faults zones outside of the county include the San Andreas Fault to the west and the Sierra Nevada Fault Zone to the east. Both of these faults present seismic ground shaking hazard throughout the county. 15

SEISMIC HAZARDS
Earthquakes can cause structural damage, injury, and loss of life, as well as damage to infrastructure networks, such as water, power, gas, communication, and transportation. The degree of damage depends on many interrelated factors. Among these are the magnitude, focal depth, distance from the causative fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction. The following analysis of seismic hazards from the Fresno County General Plan Background Report (2023) discusses some of these factors in more detail.

Ground Shaking
When movement occurs along a fault, the energy generated is released as waves, which cause ground shaking. Ground shaking intensity varies with the magnitude of the earthquake, the distance from the epicenter, and the type of rock or sediment through which the seismic waves move. The geological characteristics of an area thus can be a greater hazard than its distance to the earthquake epicenter.

Although most of Fresno County is situated within an area of relatively low seismic activity, the faults and fault systems that lie along the eastern and western boundaries of Fresno County, as well as other regional faults, have the potential to produce high-magnitude earthquakes throughout the County. A high-magnitude earthquake on one of these faults could cause moderate intensity ground shaking in Fresno County. The valley portion of Fresno County is located on alluvial deposits, which tend to experience greater ground shaking intensities than areas located on hard rock. Therefore, structures in the valley areas would tend to suffer greater damage from ground shaking than those located in the foothill and mountain areas.

Seismic Structural Safety

15 Fresno County General Plan Background Report (2023)

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61 Older buildings constructed before building codes were established, and even newer buildings constructed before earthquake-resistance provisions were included in the codes, are the most likely to be damaged during an earthquake. Buildings one or two stories high of wood-frame construction are considered to be the most structurally resistant to earthquake damage. Older masonry buildings without seismic reinforcement (unreinforced masonry) are the most susceptible to the type of structural failure that causes injury or death.

The susceptibility of a structure to damage from ground shaking is also related to the underlying foundation material. A foundation of rock or very firm material can intensify short-period motions, which affects low-rise buildings more than tall, flexible ones. A deep layer of water-logged soft alluvium can cushion low-rise buildings, but it can also accentuate the motion in tall buildings. The amplified motion resulting from softer alluvial soils can also severely damage older masonry buildings.

Other potentially dangerous conditions include, but are not limited to, building architectural features that are not firmly anchored, such as parapets and cornices; roadways, including column and pile bents and abutments for bridges and overcrossings; and above-ground storage tanks and their mounting devices.

Such features could be damaged or destroyed during strong or sustained ground shaking.

LIQUEFACTION POTENTIAL
Liquefaction is a process whereby soil is temporarily transformed to a fluid form during intense and prolonged ground shaking. Areas most prone to liquefaction are those that are water saturated (e.g., where the water table is less than 30 feet below the surface) and consist of relatively uniform sands that are loose to medium density. In addition to necessary soil conditions, the ground acceleration and duration of the earthquake must be of sufficient energy to induce liquefaction. Scientific studies have shown that the ground acceleration must approach 0.3g before liquefaction occurs in a sandy soil with relative densities typical of the San Joaquin alluvial deposits.

Liquefaction during major earthquakes has caused severe damage to structures on level ground because of settling, titling, or floating. Such damage occurred in San Francisco on bay-filled areas during the 1989 Loma Prieta earthquake, even though the epicenter was several miles away. If liquefaction occurs in or under a sloping soil mass, the entire mass may flow toward a lower elevation.

Also, of particular concern in terms of developed and newly developing areas are fill areas that have been poorly compacted.

No specific countywide assessments to identify liquefaction hazards have been performed. Areas where groundwater is less than 30 feet below the surface are primarily in the valley. However, soil types in the area are not conducive to liquefaction, because they are either too coarse or too high in clay content. Areas subject to 0.3g acceleration or greater are in a small section of the Sierra Nevada along the Fresno-Inyo border and along the Coast Range foothills in western Fresno County. However, the depth to groundwater in such areas is greater than in the valley, which would minimize liquefaction potential as well. Detailed geotechnical engineering investigations would be necessary to evaluate liquefaction potential more accurately in specific areas and to identify and map the areal extent of locations subject to liquefaction.

SETTLEMENT
Settlement can occur in poorly consolidated soils during ground shaking. During settlement, the soil materials are physically rearranged by the shaking to result in a less stable alignment of the individual minerals. Settlement of sufficient magnitude to cause significant structural damage is normally

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62 associated with rapidly deposited alluvial soils or improperly founded or poorly compacted fill. These areas are known to undergo extensive settling with the addition of irrigation water, but evidence is not available. The only urban area directly affected by settlement is the City of Coalinga. Fluctuating groundwater levels may have changed the local soil characteristics. Sufficient subsurface data is lacking to conclude that settlement would occur during a large earthquake; however, the data is sufficient to indicate that the potential exists.

Other Hazards
Earthquakes can also cause seiches, tsunamis, landslides, and dam failures. A seiche is a periodic oscillation of a body of water resulting from seismic shaking or other causes that can cause flooding.

Earthquake-induced seiches and tsunamis are not considered a risk in Fresno County. Earthquakes may cause landslides, particularly during the wet season, in areas of high water or saturated soils. The most likely areas for earthquake-induced landslides are the same areas of high landslide potential discussed in Section 4.2.9 Landslide. Finally, earthquakes can cause dams to fail (see Section 4.2.3 Dam Failure).

Hazardous material incidents following an earthquake represent a significant and complex challenge.

Earthquakes, by their very nature, can cause extensive structural damage, leading to the disruption of systems and containers that store or transport hazardous materials. This disruption can result in leaks, spills, or even explosions of hazardous substances, such as chemicals, gases, and radioactive materials. The immediate aftermath of an earthquake often sees a chaotic environment, where the release of these materials can go undetected or unaddressed for a critical period. Earthquakes can also result in fires from ruptured gas or power lines.

FAULTS
An active fault is defined by the California Geological Survey as one that has had surface displacement within the last 11,000 years (Holocene). This does not mean, however, that faults having no evidence of surface displacement within the last 11,000 years are necessarily inactive. For example, the 1975 Oroville earthquake, the 1983 Coalinga earthquake, and the 1987 Whittier Narrows earthquake occurred on faults not previously recognized as active. Potentially active faults are those that have shown displacement within the last 1.6 million years (Quaternary). An inactive fault shows no evidence of movement in historic (last 200 years) or geologic time, suggesting that these faults are dormant.

There are several active and potentially active faults within and adjacent to Fresno County.

Faults within Fresno County and major active and potentially active faults in the region are illustrated in Figure 11. Alquist-Priolo Earthquake Fault (Hazards) Zones.

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63 Source: California Department of Conservation

Figure 14. Alquist-Priolo Earthquake Fault (Hazards) Zones

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64 ▪ Clovis Fault—The northwest-trending Clovis fault is believed to be approximately five to six miles east of the City of Clovis, extending from an area just south of the San Joaquin River to a few miles south of Fancher Creek. The Clovis fault is considered a pre-Quaternary fault or fault without recognized Quaternary displacement. This fault is not necessarily inactive. ▪ Hartley Springs Fault, Silver Lake Fault (Parker Lake Fault), Unnamed Faults— Holocene and Quaternary faults are present in the vicinity of Duck Lake in the northeastern part of Fresno County, a few miles south of Mammoth Lakes.
▪ Unnamed Inferred Faults—Relative or apparent upward and downward displacement, which are interpreted as inferred faults, occur in an area located a few miles south of Helm, extending southeast to approximately Lanare (between Fresno Slough and Crescent Ditch). As with the Clovis fault, there is no apparent Quaternary displacement; however, the possibility for fault movement in this area cannot be eliminated.
▪ Nuñez Fault—The Nuñez fault is located approximately six to seven miles northwest of Coalinga.

The Nuñez fault experienced surface rupture during the 1983 Coalinga earthquake and is designated an earthquake fault zone under the Alquist-Priolo Earthquake Fault Zoning Act of 1994.

No structure for human occupancy may be built within an earthquake fault zone until geologic investigations demonstrate that the site is free of fault traces that are likely to rupture with surface displacement. Special development standards associated with Alquist- Priolo requirements would be necessary for development in this area.
▪ Ortigalita Fault—The Ortigalita fault zone is approximately 50 miles long, originating near Crow Creek in western Stanislaus County and extending southeast to a few miles north of Panoche in western Fresno County. Most of the faults are considered active due to displacement during Holocene time and are designated an earthquake fault zone under the Alquist-Priolo Earthquake Fault Zoning Act of 1994. The southernmost extension of the fault lies in Fresno County. ▪ The San Andreas Fault—The San Andreas fault lies to the west and southwest of Fresno County.

In the southwestern part of the County, the fault is roughly parallel to and a few miles west of the County line. This fault is considered active and is of primary concern in evaluating seismic hazards throughout western Fresno County, although effects of earthquakes along the San Andreas fault could occur farther east as well.
▪ Sierra Nevada Fault Zone (Owens Valley Fault Zone)—Approximately 12 miles east of the eastern Fresno County boundary lies the Owens Valley fault zone. This northwest-trending fault zone is a lengthy and complex system containing active and potentially active faults. Historically, this fault has been the source of seismic activity in Madera County to the north. ▪ Foothills Fault System—The southern part of the Foothills Fault System, located approximately 70-80 miles north of the City of Fresno, includes the Bear Mountains fault and the Melones fault zone, as well as numerous smaller, but related faults. According to the California Geological Survey data, these faults have not shown any activity during the last 1.6 million years; however, geologic investigations of the seismic safety of the Auburn Dam site suggest these faults are potentially active. Therefore, the possibility exists that earthquakes could occur on these faults. ▪ White Wolf Fault—The White Wolf fault is located approximately 100 miles south of western Fresno County. The fault was not considered active until 1952, when movement along it generated a series of damaging earthquakes in the Bakersfield (Kern County) area. ▪ Coast Range-Sierran Block Boundary—Recent evidence suggests that faults along the western boundary of the Central Valley may be more active than once believed. According to the California Geological Survey, asymmetrical folds have recently been identified on the eastern slopes of the

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65 Coast Range, which includes western Fresno County. Such folds can hide faults that show no surface rupture. These faults and folds, which are part of a large system called the Coast Range- Sierran Block Boundary, are like the faults/folds identified as the cause of the 1983 Coalinga earthquake. Therefore, faults beneath the Central Valley once believed to be inactive are now believed to be active and capable of generating large magnitude earthquakes.

Figure 12. USGS National Seismic Hazard Peak Ground Acceleration (PGA), 2% Probability of Exceedance in 50 Years is an earthquake shaking map of Fresno County that is based on the 2 percent probability of occurrence in 50 years, based on analyses of these faults, soils, topography, groundwater, and the potential for earthquake shaking sufficiently strong to trigger landslide and liquefaction. It represents worst-case ground shaking and supports the conclusion that the Fresno County planning area is at risk of future damaging earthquake hazards, especially in the western and northeastern portions of the County.

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66 Source: Central United States Earthquake Consortium (CUSEC), USGS National Seismic Hazard Map 2018

Figure 15. USGS National Seismic Hazard Peak Ground Acceleration (PGA), 2% Probability of Exceedance in 50 Years

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67 Seismic risk is not limited to identified faults. A significant fraction of small to moderately large earthquakes occur on faults not previously recognized. Such earthquakes are characterized as “background seismicity” or “floating earthquakes,” which means that the expected sources and locations of such earthquakes are unknown.

EXTENT
Large - Figure 16. California's Fault Lines shows the location of faults and past earthquake epicenters in Southern California. Since earthquakes affect large areas the earthquake hazard extent within city limits is considered significant, potentially impacting 50-100 percent of the planned area.

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68 Figure 16. California's Fault Lines

Source: California Institute of Technology, Southern California Earthquake Data Center, 2017

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69 The amount of energy released during an earthquake is usually expressed as a magnitude and is measured directly from the earthquake as recorded on seismographs. Seismologists have developed several magnitude scales; one of the first was the Richter Scale, developed in 1932 by the late Dr.

Charles F. Richter of the California Institute of Technology.

The Moment Magnitude Scale is used to quantify the magnitude or strength of the seismic energy released by an earthquake. Another measure of earthquake severity is Intensity. Intensity is an expression of the amount of shaking at any given location on the ground surface based on felt or observed effects. Seismic shaking is typically the greatest cause of losses to structures during earthquakes. Intensity is measured with the Modified Mercalli Intensity (MMI) scale. Table 25. Richter Scale Measurements and Associated Characteristics below compares Magnitude and the felt effects associated with the MMI scale. Damage typically occurs in MMI VII or above, and some areas of the County are susceptible to this level of shaking.

Table 25. Richter Scale Measurements and Associated Characteristics Magnitude Mercalli
Intensity Effects Frequency
Less than 2.0 I Microearthquakes, not felt or rarely felt; recorded by seismographs. Continual

2.0-2.9 I to II Felt slightly by some people; damages to buildings. Over 1M per year

3.0-3.9 II to IV Often felt by people; rarely causes damage; shaking of indoor objects noticeable. Over 100,000 per year

4.0-4.9 IV to VI
Noticeable shaking of indoor objects and rattling
noises; felt by most people in the affected area;
slightly felt outside; generally, no to minimal
damage.
10K to 15K per year

5.0-5.9 VI to VIII
Can cause damage of varying severity to poorly
constructed buildings; at most, none to slight
damage to all other buildings. Felt by everyone.
1K to 1,500 per year

6.0-6.9 VII to X
Damage to a moderate number of well-built
structures in populated areas; earthquake-resistant
structures survive with slight to moderate damage;
poorly designed structures receive moderate to
severe damage; felt in wider areas; up to hundreds
of miles/kilometers from the epicenter; strong to
violent shaking in epicentral area.
100 to 150 per year

7.0-7.9 VIII <
Causes damage to most buildings, some to
partially or completely collapse or receive severe
damage; well- designed structures are likely to
receive damage; felt across great distances with
major damage mostly limited to 250 km from
epicenter.
10 to 20 per year

8.0-8.9 VIII <
Major damage to buildings, structures likely to be
destroyed; will cause moderate to heavy damage
to sturdy or earthquake-resistant buildings;
damaging in large areas; felt in extremely large
regions.

One per year

9.0 and Greater VIII <
At or near total destruction - severe damage or
collapse to all buildings; heavy damage and
shaking extends to distant locations; permanent
changes in ground topography.

One per 10-50 years

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70 Source: USGS

PAST OCCURRENCES
Earthquakes have occurred in Fresno County in the past. Earthquakes can be felt in Fresno County by earthquakes that occur within jurisdictional boundaries and outside of jurisdictional boundaries. In the last 10 years, Fresno County has experienced on average 30 earthquakes per year that are within 186 miles and at least magnitude 4.0 or greater. According to the Fresno County Operational Area Master Emergency Services Plan, the California Geological Survey has identified a minimum of four magnitude

5.0 or greater earthquakes that caused damaging shaking in Fresno County between 1800 and 1999.

Details on some of these events follow.

▪ 1983: In Coalinga, a surface rupture occurred along the Nuñez fault. The main shock was 6.7 on the Richter scale. The surface rupture was determined not to be the cause of the main shock; instead, a blind thrust fault concealed deep within a complex fold-and-thrust belt at the western end of the San Joaquin Valley was identified as the cause. Approximately 800 buildings were destroyed, and 1,000 people were left homeless. No deaths resulted, but 47 people were injured. Private homeowner losses exceeded $25 million. Public agency losses were roughly $6 million. The commercial section of Coalinga was heavily damaged; however, most schools and the hospital received only slight damage. Local, state, and federal declarations resulted. ▪ August 4, 1985: A magnitude 6.0 earthquake occurred, centered about 10.5 kilometers east of Coalinga. It is unknown to what extent earthquakes occurring outside of the planning area were felt by Fresno County residents.

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71 4. Risk Assessment
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72 LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely - Based on the past occurrences, Fresno County is likely to experience about 2 earthquakes a month. Not every earthquake is significant, and the majority of the earthquakes do not cause damage, but earthquakes do occur and can be felt in Fresno County on an annual basis.

According to the Fresno County Operational Master Emergency Services Plan, the faults and fault systems that lie along the eastern and western boundaries of Fresno County, as well as other regional faults, have the potential to produce high magnitude earthquakes throughout the County. Based on the Alquist-Priolo Earthquake Fault Zone chart, Fresno County would be affected by earthquake activity in the Alcalde Hills and Ortigalita Peak faults. There are also several faults in the vicinity of Coalinga that could cause problems in the future. These include the Nuñez fault, about ten kilometers northwest of Coalinga, the Coalinga fault, 5 kilometers northeast of Coalinga; and the New Idria fault, approximately 21 kilometers northwest of Coalinga. In addition, there are many faults in neighboring counties that could potentially affect Fresno County. Specifically, the U.S. Geological Survey is predicting an earthquake at the community of Parkfield in Monterey County, approximately 15 miles southwest of Coalinga.

In addition, according to the California Earthquake Authority (CEA) the Central Valley South region (which includes Fresno, Kern, Kings, Madera, Mariposa, Merced, and Tulare counties), has a 75 percent likelihood or one or more M7.0 or greater quakes striking Southern California based on a 30- yar period, beginning in 2014. The nearby San Andreas Fault system is the major geologic boundary between the North American and Pacific tectonic plates and passes through much of the state with the potential to create the biggest earthquakes. A study by the U.S. Geological Survey indicates that a portion of the San Andreas Fault near Tejon Pass could be overdue for a major earthquake. 16

CLIMATE CHANGE CONSIDERATIONS
There is some evidence to suggest that weather and climate change impacts can affect seismic activity under the Earth’s surface. Geologists have identified a relationship between rainfall rates and seismic activity in certain regions across the globe. In the Himalayas for example, the frequency of earthquakes is influenced by the annual rainfall cycle of the summer monsoon season. Research reveals that 48 percent of earthquakes in the Himalayas strike during the drier pre-monsoon months of March, April, and May while just 16 percent occur in the monsoon season. 17 According to the U.S. Geological Survey, the only correlation that’s been noted between earthquakes and weather is that large changes in the atmosphere pressure caused by major storms like hurricane have been shown to occasionally trigger “slow earthquakes” which release energy over a comparatively long periods of time. However, these numbers are small and are not significantly significant. 18 While climate change may have a connection to seismic activity, it is not expected to directly affect earthquake frequency or intensity as most earthquakes occur far beneath the Earth’s surface and far from the influence of weather conditions. However, climate change impacts could exacerbate indirect impacts of earthquakes (e.g., climate change will increase the frequency and intensity of extreme precipitation events, increasing the probability of landslides and liquefaction events during an earthquake).
16 California Earthquake Authority https://www.earthquakeauthority.com/california-earthquake-risk/faults-by-county 17 https://theconversation.com/how-climate-change-might-trigger-more-earthquakes-and-volcanic-eruptions-210841 18 https://climate.nasa.gov/news/2926/can-climate-affect-earthquakes-or-are-the-connections-shaky/

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73 FLOOD

HAZARD/PROBLEM DESCRIPTION
Floods are among the most frequent and costly natural disasters in terms of human hardship and economic loss and are usually caused by weather events. Floods can cause substantial damage to structures, landscapes, and utilities as well as life safety issues. Certain health hazards are also common to flood events. Standing water and wet materials in structures can become breeding grounds for microorganisms such as bacteria, mold, and viruses. This can cause disease, trigger allergic reactions, and damage materials long after the flood. When floodwaters contain sewage or decaying animal carcasses, infectious disease becomes a concern. Direct impacts, such as drowning, can be limited with adequate warning and public education about what to do during floods. Where flooding occurs in populated areas, warning and evacuation will be of critical importance to reduce life and safety impacts.

A floodplain is an area adjacent to a channel of water. Floodplains are illustrated on inundation maps, which show areas of potential flooding and water depths. In its common usage, the floodplain most often refers to the area that is inundated by the 100-year flood, the flood that has a one percent chance in any given year of being equaled or exceeded. The 100-year flood is the national minimum standard to which communities regulate their floodplains through the National Flood Insurance Program. The 500-year flood is a flood that has a 0.2 percent chance of being equaled or exceeded in any given year.

In addition to the standard 100-year and 500-year flood maps, the California Department of Water Resources (CA DWR) has initiated a program that covers areas at risk of a 200-year flood. After propositions IE and 84 were passed in 2006, funding became available to support the Central Valley Floodplain Evaluation and Delineation (CVFED) program. To assist DWR with fulfilling new California code requirements, the CVFED Program provides new maps delineating the 100-year, 200-year and 500-year floodplains for areas receiving protection from the State federal flood protection system in the Central Valley. The potential for flooding can change and increase through various land use changes and changes to land surface, which can result in a change to the floodplain. A change in environment can create localized flooding problems inside and outside of natural floodplains by altering or confining natural drainage channels. These changes are most often created by human activity.

The Fresno County planning area is susceptible primarily to three types of flooding: localized, riverine, and dam failure flooding.

▪ Localized flooding: Localized flooding problems are often caused by flash flooding, severe weather, or an unusual amount of rainfall. Flooding from these intense weather events usually occurs in areas experiencing an increase in runoff from impervious surfaces associated with development and urbanization as well as inadequate storm drainage systems. The term “flash flood” describes localized floods of great volume and short duration. This type of flood usually results from heavy rainfall on a relatively small drainage area. Precipitation of this sort usually occurs in the winter and spring. Flash floods often require immediate evacuation within the hour. ▪ Riverine flooding: Riverine flooding, defined as when a watercourse exceeds its “bank-full” capacity, generally occurs because of prolonged rainfall, or rainfall that is combined with already saturated soils from previous rain events. This type of flood occurs in river systems whose tributaries may drain large geographic areas and include one or more independent river basins. The onset and duration of riverine floods may vary from a few hours to many days. Factors that directly

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74 affect the amount of flood runoff include precipitation amount, intensity and distribution, the amount of soil moisture, seasonal variation in vegetation, snow depth, and water-resistance of the surface due to urbanization. In the Fresno County planning area, riverine flooding is largely caused by heavy and continued rains, sometimes combined with snowmelt, increased outflows from upstream dams, and heavy flow from tributary streams. These intense storms can overwhelm the local waterways as well as the integrity of flood control structures. The warning time associated with slow rise floods assists in life and property protection.
▪ Dam failure flooding: Flooding from failure of one or more upstream dams is also a concern to the Fresno County planning area. A catastrophic dam failure could easily overwhelm local response capabilities and require mass evacuations to save lives. Impacts to life safety will depend on the warning time and the resources available to notify and evacuate the public. Major loss of life could result, and there could be associated health concerns as well as problems with the identification and burial of the deceased. Dam failure is further addressed in the Dam Failure section.

ATMOSPHERIC RIVER
California, including the location of the planning area, is subject to the effects of a phenomenon referred to as atmospheric rivers. These weather events consist of long, narrow regions in the atmosphere transporting tremendous amounts of water vapor from the tropics, shown in Figure 14. The Science Behind Atmospheric Rivers. These weather regions behave like rivers in the sky. They can carry heavy volumes of water vapor compared to the amount of water flowing at the mouth of the Mississippi River. As these atmospheric rivers arrive in California, they tend to generate significant rain and snow.

Atmospheric rivers can arrive in many different shapes and sizes. The larger events can generate extreme rainfall amounts resulting in flooding. They can stall over watersheds vulnerable to flooding, often saturated with heavy snow amounts. The atmospheric rivers known as a “Pineapple Express” coming from the tropics and arriving with warmer air may produce heavy rains that will melt ground snow, adding to the water volume that will be in the flood runoff.

These events can produce heavy amounts of precipitation creating extensive damage. However, these events may present as weaker systems that produce precipitation that is enough to be beneficial for the local water supply. At the higher elevations in the California mountains, these events have the potential to generate a tremendous snowpack providing a source of water during the dry summer months.

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75 Source: NOAA

LOCATION
Flooding is a hazard which can impact virtually all of the planning area. Many communities in Fresno County have development in or near floodplains which are vulnerable to fluvial flooding. Additionally, there are several leveed areas in the County, and failures of these levees could result in extensive flooding. Flash flooding occur as result of intense rainfall, and this can occur practically anywhere in the County. Figure 18. Fresno County Flood Hazard Areas and Leveed Areas shows the extent of the 100-year and 500-year floodplains in the County as well as the leveed areas. Analysis of the flood hazard risk for individual communities in Fresno County is available in the community annexes.

Figure 17. The Science Behind Atmospheric Rivers

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76 Figure 18. Fresno County Flood Hazard Areas and Leveed Areas

Eastern and Central Fresno County
Eastern Fresno County extends from the Sierra Nevada foothills to the Great Western Divide. It is located primarily in the Sierra Nevada, where precipitation falls mainly as snow. The region is characterized by small local watersheds and draining to the reservoirs upstream of Millerton and Pine Flat reservoirs. Flows originating in the mountains and foothills contribute to the drainage and flooding problems on the valley floor.

Central Fresno County includes the area between the valley floor around Fresno Slough and eastward to the Sierra Nevada foothills, including Millerton Reservoir to Pine Flat Reservoir. The geographic area of central Fresno County runs along the Sierra Nevada foothills at elevations around 500 feet, slopes down to the Fresno Slough on the valley floor and drains gently to the north. This area is the population center of the County; thus, most storm drainage and flood control systems are largely designed to protect urban development. In central Fresno County, annual precipitation typically amounts to 6 inches in areas like Mendota, while in Fresno itself, the average is about 11.50 inches.

The western slope of the Sierra Nevada drains into central Fresno County via the San Joaquin and Kings rivers and small creeks and stream systems. The Fresno Slough, also known as the North Fork

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
77 of the Kings River, is connected to the San Joaquin River by the James Bypass, a manmade canal. It directs floodwater from the Kings River to the San Joaquin River. Three dams have been constructed to control flows on the rivers. These dams are Friant and Mendota dams on the San Joaquin River and Pine Flat Dam on the Kings River. Pine Flat Dam is operated primarily for flood control purposes. Friant Dam was constructed and is managed by the U.S. Bureau of Reclamation as part of the Central Valley Project. Although Friant Dam does serve to reduce release volumes in the main San Joaquin River channel, it was not sited, designed, or engineered for the purpose of flood control. Mendota Dam is operated primarily for irrigation.

In addition to the flood control facilities on the San Joaquin and Kings rivers, several reservoirs and detention basins have been constructed on streams east of the Fresno-Clovis area to prevent urban flooding. These facilities include Redbank Dam and the Redbank-Fancher Creeks Flood Control Project. The Redbank-Fancher Creeks Flood Control Project consists of two dams (Big Dry Creek Dam and Fancher Creek Dam), three detention basins (Redbank Creek, Pup Creek, and Alluvial Drain detention basins), and various canals to convey discharges around developed areas. The Friant-Kern Canal draws water from Millerton Reservoir at Friant Dam and flows south along the foothills toward Bakersfield.

The rivers, streams, and flood control systems of eastern and central Fresno County are described in further detail below. Table 26. Major Flood Control Facilities and Stream Systems in Eastern and Central Fresno County summarizes the location, capacity, and managing agency for each steam system and flood control facility in eastern and central Fresno County.

Table 26. Major Flood Control Facilities and Stream Systems in Eastern and Central Fresno County
Facility/Water Body Location Capacity Managing Agency
Millerton Reservoir*
17 miles northeast of SR 99
on the San Joaquin River in
the north central part of the
county
520,500 acre-ft1 U.S. Bureau of
Reclamation
Pine Flat Reservoir
16 miles northeast of
Sanger on the Kings River in
the east central part of the
county
1,000,000 acre-ft1 U.S. Army Corps of
Engineers
Mendota Pool
On the San Joaquin River at
Mendota where the river
turns north, and Fresno
Slough joins the river in the
northwestern part of the
country
5,000 acre-ft2 U.S. Bureau of
Reclamation
Big Dry Creek Reservoir
West of Friant-Kern Canal
and north of Tollhouse Road
on Big Dry Creek
30,200 acre-ft1 Fresno Metropolitan Flood
Control District
Redbank Reservoir
7 miles east of Clovis, 3
miles southwest of the
Friant-Kern Canal between
Dog Creek and Fancher
Creek in the central part of
the
county
1,030 acre-ft Fresno Metropolitan Flood
Control District

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2024 Fresno County Hazard Mitigation Plan
May 2024
78 Facility/Water Body Location Capacity Managing Agency Fancher Creek Reservoir
East of the Friant-Kern
Canal at the confluence of
Fancher and Hog creeks
9,712 acre-ft1 Fresno Metropolitan Flood
Control District
Redbank Creek Detention
Basin
On Redbank Creek north of
McKinley Avenue and west
of DeWolf Avenue
940 acre-ft1 Fresno Metropolitan Flood
Control District
Pup Creek Detention Basin
On Pup Creek south of
Herndon Avenue and east of
Temperance Avenue
559 acre-ft1 Fresno Metropolitan Flood
Control District
Alluvial Drain Detention
Basin
On Alluvial Drain west of
Temperance Avenue and
north of Nees Avenue
305 acre-ft1 Fresno Metropolitan Flood
Control District
Eastern and Central
Fresno County 1997
Flows from the Sierra
Nevada southwest along the
northern border of the
county to Mendota where it
turns to flow to the
northwest. Forms the border
between Fresno and Madera
counties
8,000 cfs1** (Friant Dam to
Chowchilla) 2,500 cfs1,4 (to
Mendota) 4,500 cfs1,4
(Mendota Dam
to Sand Slough)
U.S. Bureau of Reclamation,
U.S. Army Corps of
Engineers, and Local
Irrigation
Districts
Kings River
Flows from the Sierra
Nevada to Sanger and
Reedley and into Kings
County boundary to Army
Weir above Hwy 41 where
the normal flow is diverted to
the North Fork. Excess flows
are diverted to Tulare
Lakebed
13,000 cfs3** Kings River Conservation
District
Fresno Slough & James
Bypass
A seasonal waterway
system which connects the
Kings River near Laton and
Lemoore
NAS to the San Joaquin
River at Mendota Pool during
flood events
4,750 cfs1 U.S. Army Corps of
Engineers
Friant-Kern Canal
Flows southeasterly from
Millerton Lake through
Orange Cove continuing on
to Bakersfield. Crosses five
feet below Kings River via a

24.5 ft diameter 3,000 ft
siphon
5,000 cfs1
Friant-Kern Water Users’
Authority,
U.S. Bureau of Reclamation,
U.S. Army Corps of
Engineers
Millerton Reservoir*
17 miles northeast of SR 99
on the San Joaquin River in
the north central part of the
county
520,000 acre-ft1 U.S. Bureau of
Reclamation
Holland Creek Diversion
Channel
South of the Friant-Kern
Canal where it crosses
Trimmer Springs Road
Peak channel capacity is
1,044 cfs
Fresno Metropolitan Flood
Control District
Fancher Creek Detention
Basin
Southwest corner of
McKinley Avenue and McCall
Avenue
Ultimate capacity is 1,802
ac/ft.

Fresno Metropolitan Flood
Control District

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
79 Facility/Water Body Location Capacity Managing Agency Pup-Enterprise Detention
Basin
East side of DeWolf Avenue,
just south of Herndon
Avenue
Ultimate capacity is 200 ac/ft. Fresno Metropolitan Flood Control District
Big Dry Creek Detention
Basin
North of Freeway 168 and
Dakota Avenue Ultimate capacity is 251 ac/ft. Fresno Metropolitan Flood Control District
Dry Creek Extension
Basin
Northwest corner of
Annadale Avenue and
Brawley Avenue
Ultimate capacity is 854 ac/ft. Fresno Metropolitan Flood Control District
Facility/Water Body Location Capacity Managing Agency
Millerton Reservoir*
17 miles northeast of SR 99
on the San Joaquin River in
the north central part of the
county
520,500 acre-ft1 U.S. Bureau of
Reclamation
Source: Fresno County General Plan, 2017; Fresno Metropolitan Flood Control District Note: The numbers provided in this table are design capacity and actual river capacity may vary significantly *Friant Dam/Millerton Reservoir is not sited, designed, or operated to function as a flood control facility, and any such capability is incidental to its function as a diversion facility 1U.S. Army Corps of Engineers
2Central California Irrigation District
3Kings River Conservation District
4River channel capacity is difficult to define due to significant changes in the river conditions over time, variance in channel conditions and geometry along a given river reach, and assumptions made in developing hydraulic models

San Joaquin River
The San Joaquin River forms the boundary between Fresno and Madera counties, shown in Figure 19.

San Joaquin River. It flows from the Great Western Divide in the Sierra Nevada southwest along the northern border of Fresno County where it is joined by flows from the North Fork of the Kings River.

From there, the river flows northwest up the San Joaquin Valley toward the Delta. Friant Dam, which serves to regulate river flows, is the most significant of the dams on the San Joaquin River. Several dams are located upstream of Friant Dam.

The storage capacity of Millerton Reservoir (formed by Friant Dam) is 520,500 acre-feet. The Central Valley Project Friant Unit consists of Friant Dam and Millerton Reservoir; the Friant-Kern Canal, which runs south to Kern County; and the Madera Canal, which runs northwesterly to Madera County.

Releases from Friant Dam to the San Joaquin River and the Friant-Kern Canal provide service to water users within Fresno County.

This storage capacity of Millerton Reservoir is inadequate for full flood protection during wet years, and emergency releases may result in flooding problems downstream. The U.S. Army Corps of Engineers (the Corps) has evaluated the operational plans for all the dams in the San Joaquin River system to determine the possibility of coordinated releases to reduce the likelihood of coincident peak flows downstream with some success. However, in 1997, emergency releases from Friant Dam combined with large storm events and several levee breaks contributed to flooding along the San Joaquin River. Not designed for purposes of flood control, any flood control capability of the Friant Unit

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
80 is incidental to its function as a diversion facility. The Madera Canal, also part of this unit, also serves to release runoff volumes from the San Joaquin River.

The Friant-Kern Canal carries irrigation water from Millerton Reservoir southeast to Kern County. The average annual delivery from the canal is about one million acre-feet with a design capacity of 5,000 cubic feet per second (cfs). There is a spillway into the Kings River just upstream of a double barrel 24 ½-foot diameter siphon under the river. Although the canal was constructed by the Bureau of Reclamation and is normally managed by the Friant-Kern Water Users Authority, floodwater in the canal is managed by the U.S. Army Corps of Engineers. During times of flooding, water from the Friant- Kern Canal may not be releasable to the Kings River since the Corps may not want additional flows on the river.

Mendota Pool is a 5,000-acre-foot reservoir created by Mendota Dam located just outside City of Mendota on the San Joaquin River. The primary function of the dam is storage of irrigation water for agriculture; however, the water level in the pool also functions to maintain water levels in the Mendota Wildlife Management Area. Mendota Pool provides little or no flood protection. Mendota Dam contains flow from the San Joaquin River as well as discharge and releases from the Kings River via the Fresno Slough and James Bypass. The Delta-Mendota Canal conveys Delta water to Mendota Pool from the north, and several irrigation channels divert flows from it. The Bureau of Reclamation, in coordination with the Central California Irrigation District, manages this system, which is part of the Central Valley Project.

Southern California Edison and Pacific Gas and Electric own and operate several dams and reservoirs on the San Joaquin River and its tributaries upstream of Friant Dam. The most notable of these are Edison Lake and Florence Lake. These upstream storage facilities are operated to produce electric energy and have a combined capacity of about 609,530 acre-feet. Their operation does affect the flow of water into Millerton Reservoir and subsequently the timing and availability of releases to Friant Unit contractors. None of these storage facilities are designed or operated for flood control, and the Corps currently has no jurisdiction over releases from these structures. Cumulative flood releases from the upper San Joaquin River dams could overwhelm Friant Dam.

From Friant to Gravelly Ford, the San Joaquin River is part of the Designated Floodway Program administered by the State Reclamation Board. Land use restrictions and river management practices allow the river to meander, flood the overbanks, and remain in a relatively natural state. Downstream of Gravelly Ford, the river is confined by levees. The design capacity of the San Joaquin River from Friant Dam to Chowchilla Bypass is in excess of 8,000 cfs, while the channel capacity downstream is reduced. The major San Joaquin River “choke point” in Fresno County is the reach near Mendota and Firebaugh, which has a channel capacity of 8,000 cfs. Beyond that point, San Joaquin River channel capacity continues to decrease for some distance due to lack of annual flooding and natural channel clearing since Friant Dam was constructed. Further downstream, the river channel has been deepened and widened by historical flows of the Merced and Tuolumne rivers and other tributaries.

In addition to releases from Friant Dam, two uncontrolled streams, Cottonwood Creek, and Little Dry Creek, add significantly to the river flows below Friant during heavy precipitation. Historically, large areas within the Central Valley were within the river’s floodplain. Development has encroached on the floodplain and the flow is now confined to a relatively narrow channel constrained by levees, which reduce the carrying capacity of the river. Most of the flow from Friant Dam is diverted to the Chowchilla Bypass, which branches off the San Joaquin River about 11 river miles upstream from Mendota Dam.

Over time, encroachment of vegetation, substantial sedimentation, and land subsidence has considerably reduced channel capacity. Erosion, seepage, and prolonged high water compromise levee integrity. Downstream of the Chowchilla Bypass, the river is not confined by levees (within Fresno County) and generally carries no more than 2,500 cfs.

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2024 Fresno County Hazard Mitigation Plan
May 2024
81 Flood control measures constructed along the main stem of the river have impacted riparian and wetland wildlife habitat areas. Levee construction and sediment and vegetation removal can damage streamside vegetation, divert floodwater from wetlands and riparian areas, and reclaim natural wetlands for other uses.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
82 Figure 19. San Joaquin River

Source: American Rivers

Kings River
The Kings River originates high in the Sierra Nevada Mountains near the Inyo County line and flows southwest through the central part of Fresno County and into Tulare County at Reedley. It has a large drainage basin, which includes most of Kings Canyon National Park and most of the area between Shaver and Florence lakes in the north to the Fresno/Tulare County border in the south. North of Hanford, the river branches, and the south fork flows southward to the Tulare Lakebed. The north fork joins Fresno Slough, which conveys flows north to the San Joaquin River at Mendota Pool. Several sloughs and canals branch off the river and are used for water storage and to convey irrigation water.

The Kings River flows are regulated by Pine Flat Dam, completed in 1954 for flood control purposes.

Pine Flat Reservoir has a storage capacity of approximately one million acre-feet. The flood control functions of the facility are managed by the Corps while the releases for irrigation diversion are

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
83 managed by the Kings River Water Association. There are additional reservoirs upstream of Pine Flat that are owned and operated by Pacific Gas and Electric for the purpose of hydroelectric power generation. These facilities have a combined storage capacity of about 252,000 acre-feet. Two uncontrolled creeks, Hughes Creek and Mill Creek, flow into the Kings River below Pine Flat Dam. Pine Flat Reservoir has adequate storage capacity to avoid emergency releases in most storm events, but these downstream creeks can add significant flow to the river.

Downstream of Pine Flat Dam, the Kings River is managed for flood control by the Kings River Conservation District in cooperation with the Corps, the California Department of Water Resources (DWR), and local irrigation districts. Releases from Pine Flat Dam and flows from Hughes Creek and Mill Creek provide most of the river’s flow. Numerous sloughs and irrigation canals branch off the Kings River. The capacity of the river is more than 13,000 cfs. The Kings River flood control facilities include many miles of levees in central Fresno County.

There are three weirs on the river: Army Weir, Crescent Weir, and Stinson Weir. Army Weir is located where the north and south forks branch off the natural river just upstream from State Route 41.

Crescent Weir is located at the Crescent Bypass southwest of 22nd and Excelsior Avenues. The Crescent Bypass flows to Fresno Slough. Stinson Weir is located near the confluence of Murphy Slough and Fresno Slough at Elkhorn Avenue. Normal flows are held by these weirs in the main channel. During storm events, as much as 4,750 cfs is diverted to the North Fork and the San Joaquin River. As much as 3,200 cfs can then be diverted to the Crescent Bypass. Any flow above approximately 10,000 cfs is divided equally between the north and south forks.

In practice, the flow of the Kings River is carefully managed using analysis of anticipated weather, upstream flows, and ability of downstream users to receive the water. Significant adjustment may be necessary, and a variety of operations options are considered, including storing or routing water through alternate sloughs or requesting users to accept additional water. Fresno Slough and the James Bypass are normally dry except for groundwater seepage and irrigation returns. Flow is diverted to the South Fork only in very wet years.

Sand and gravel extraction has occurred along both the San Joaquin River and the Kings River in Fresno County, although most of this aggregate mining has occurred outside of the main river channels. The hydrologic effect of the mining and subsequent reclamation activity has generally been to increase the overall hydraulic capacity of the rivers to accommodate major flood events.

Eastern County Streams
There are many creeks and lakes in the high Sierra Nevada within Fresno County, all of which eventually feed into either the Kings River or the San Joaquin River. In addition, several creeks drain the foothill areas and flow into developed areas in central Fresno County. Most of these streams (i.e., Redbank, Fancher, Dry, and Dog creeks) have been controlled by efforts of the Corps and the Fresno Metropolitan Flood Control District to protect the City of Fresno from damage from flooding from a 200- year storm. Other creeks, such as Wahtoke Creek, are uncontrolled. Some streams in foothill areas of southeastern Fresno County are tributaries to the Orange Cove Stream Group and to Sand Creek, which is a tributary to the Kaweah River.

Flood control efforts along some of these eastern Fresno County streams include the following:

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
84 ▪ Redbank Reservoir—Redbank Reservoir, formed by Redbank Dam, is located on Redbank Creek north of Shaw Avenue. The reservoir has a gross pool capacity of 1,030 acre-feet and receives water from the Redbank Creek watershed. The reservoir is operated for flood control by the Fresno Metropolitan Flood Control District.
▪ Redbank-Fancher Creeks Flood Control Project—This project consists of a system of two dams, three detention basins, and canals to protect developed areas in and around the City of Fresno from a 200-year storm. The project was built by the Corps and is managed and operated by the Fresno Metropolitan Flood Control District. Fancher Creek Reservoir has a capacity of 9,712 acre- feet and retains water from Fancher and Hog creeks and some flows from Redbank Creek. Fancher Dam diverts flows via canals around Fresno. Redbank Creek Detention Basin (940 acre-feet) contains local flows from Redbank Creek downstream from Redbank Dam. The Alluvial Drain and Pup Creek detention basins have capacities of 305 and 559 acre-feet, respectively, and can each regulate discharges into Dry Creek at 25 cfs.
▪ Big Dry Creek Reservoir—Big Dry Creek Reservoir, with a capacity of 30,200 acre-feet, retains flows from Big Dry Creek and Dog Creek and diverts flows via Little Dry Creek to the San Joaquin River at a rate of up to 700 cfs. During a flood event, water is not typically released from Big Dry Creek Dam; however, during a severe flood event, it may be necessary to do so.

Western County Streams
Western Fresno County consists of the Coast Range within which lies the County’s western boundary with San Benito and Monterey counties and the San Joaquin Valley area between the Range and the Fresno Slough. Interstate 5 and the California Aqueduct pass in a north-south direction through western Fresno County. A complex system of streams drains the eastern slope of the Coast Range into the valley and the Fresno Slough. Western Fresno County is significantly different from the rest of the County in climate and character.

Western Fresno County is largely unpopulated. The major land uses are agriculture and grazing. The region is quite dry, with an average annual rainfall of only six to eight inches, yet the stream systems are prone to high flows and flooding because they drain very large watersheds. The soil in the Coast Range is subject to erosion. As a result, stormwater runoff typically carries large volumes of sediment and naturally occurring minerals, such as selenium, arsenic, boron, and asbestos, which is undesirable to downstream users.

Western Fresno County contains five major stream systems that flow from the Coast Range as described further below.

▪ Little Panoche Creek—Little Panoche Creek, located in the northwestern corner of Fresno County, is managed for flood control purposes by the DWR. The DWR operates and maintains a detention dam and reservoir (Little Panoche Reservoir) on the creek. The facility was constructed by the Bureau of Reclamation to provide flood protection for the California Aqueduct. It was designed for a 100-year storm and has a storage capacity of 820 acre-feet. When storage levels in the reservoir exceed 820 acre-feet, the dam’s uncontrolled spillway releases water. The creek flows under Interstate 5 and the California Aqueduct. Little Panoche Creek ends at a retention basin on the east side of the aqueduct. When the retention basin fills with stormwater during high flows, stormwater is pumped into the aqueduct. The reservoir also serves as a wildlife preserve.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
85 ▪ Panoche Creek—Panoche Creek is located just south of Little Panoche Creek in northwestern Fresno County. It flows under Interstate 5and across the California Aqueduct. The estimated 100- year peak flow for Panoche Creek is 22,000 cfs. On the east side of the aqueduct, the water is not channelized and flows overland. During high creek flows, stormwater floods vast tracks of agricultural land and portions of the City of Mendota.
▪ Tumey Gulch and Arroyo Ciervo—Tumey Gulch and Arroyo Ciervo are in central western Fresno County and flow easterly from Ciervo Mountain. The estimated 100-year peak flow is 3,600 cfs for Tumey Gulch and is 900 cfs Arroyo Ciervo. No flood control facilities exist on the streams; however, the California Aqueduct obstructs their eastward flow. During periods of high stream flow, sediment laden floodwater may form ponds on the west side of the aqueduct. These ponds may spill stormwater and sediment into the aqueduct during storm events. ▪ Cantua Creek System—This creek system includes Arroyo Hondo, Cantua Creek, Salt Creek, Martinez Creek, and Domegine Creek in central western Fresno County. These creeks drain the east side of Joaquin Ridge, crossing Interstate 5 between Kamm Road and Fresno-Coalinga Road.

The estimated 100-year peak flow from the Cantua Creek system is 8,300 cfs. As with Tumey Gulch and Arroyo Ciervo, stormwater from the Cantua Creek system ponds on the east side of the California Aqueduct during periods of high flow, dumping large quantities of sediment and storm runoff into the aqueduct. Cantua Creek has inundated Interstate 5 during large storm events. ▪ Arroyo Pasajero Stream System—The Arroyo Pasajero stream system encompasses the largest drainage area in the western San Joaquin Valley. The major creeks in the system are Los Gatos, Warthan, Jacalitos, and Zapato-Chino creeks. They flow through the City of Coalinga and under Interstate 5 to a small ponding basin on the west side of the California Aqueduct. Arroyo Pasajero carries large quantities of sediment containing naturally occurring asbestos. During flood events, the system may damage the aqueduct and Interstate 5. Floodwater may also wash asbestos fibers into the aqueduct.

Major Sources of Flooding/Problem Areas
Flooding is a natural occurrence in the Central Valley because it is a natural drainage basin for thousands of watershed acres of Sierra Nevada and Coast Range foothills and mountains. FEMA’s Flood Insurance Study for the County, effective January 20, 2016, describes several types of primary flood problems.

▪ General rainfall floods can occur in Fresno County during winter and spring months. This type of flood results from prolonged heavy rainfall over tributary areas and is characterized by high peak flows of moderate duration. Flooding is more severe when antecedent rain has resulted in saturated ground conditions; when the ground is frozen, and infiltration is minimal; or when rain on snow in the high elevations on the east side adds snowmelt to rain flood runoff. ▪ Snowmelt floods on the San Joaquin and Kings rivers and their higher elevation tributaries can be expected to occur any time from April through June. Although snowmelt flooding is of much larger volume and longer duration than rain flooding, it does not have the high peak flows characteristic of rain floods. Snowmelt flood runoff is sometimes augmented by late spring rains on the snowfields or lower elevation tributary watersheds.
▪ Cloudburst storms sometimes lasting as long as three hours can occur any time from late spring to early fall and may occur as an extremely severe sequence within a general rainstorm.

Cloudbursts are high-intensity storms that can produce floods characterized by high peak flows,

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
86 short duration of flood flows, and small volume of runoff. In some areas, especially where drainage basins are small, cloudbursts can produce peak flows substantially larger than those of general rainstorms. Cloudburst storms usually cover small areas and would not generally affect flood flows or flood stages on the San Joaquin or Kings rivers. Generally, only the upper reaches of the smaller streams are affected by cloudbursts.

In urban areas, flood problems intensify because open land available to absorb rainfall and runoff is being used for new development, which increases the number of paved areas (i.e., impervious surfaces). The decrease in the amount of open land increases the volume of water that must be carried away by waterways. Urban development in some areas of Fresno County has been substantial in recent years and is expected to continue.

Eastern and Central Fresno County Flood Problem Areas
Most flood issues in eastern and central Fresno County are associated with the San Joaquin River, Kings River, and several other stream systems. In Fresno County, there are 23 dams that could cause substantial flooding in the event of a failure. The majority of these dams are in the San Joaquin and Kings River watersheds in the eastern part of the county. Generally, the areas at risk are large urban and rural areas downstream and below the dams on the valley floor.

San Joaquin River System
The San Joaquin River from Gravelly Ford to the Chowchilla Bypass outside Fresno County is confined by a levee system. The design capacity of the river is 5,000 cfs, which is considered a safe carrying capacity with three feet of allowable freeboard. Over time, encroachment of vegetation, substantial sedimentation, and land subsidence has considerably reduced channel capacity. Erosion, seepage, and prolonged high water compromise levee integrity. Levee maintenance is generally under the jurisdiction of local reclamation districts. Uncontrolled flooding from the San Joaquin River between the Chowchilla Bypass and Dos Palos tends to flow into Madera County north of Mendota.

The Mendota Pool area has shown evidence of significant subsidence, possibly affecting levee height, river invert (i.e., bottom of low-flow channel), as well as the pool depth. The flooding hazards in the region are from Panoche Creek to the west into Madera County downstream from Mendota Pool. It was reported in 1997 (Fresno County General Plan Background Report) that the Mendota Dam is of limited usefulness for flood control purposes. Construction of a new dam at Mendota has been contemplated to improve flood control capabilities of the lower reaches of the San Joaquin.

The flooding potential from creeks and streams between the San Joaquin and Kings Rivers in the east has been substantially eliminated within the last few years by the completion of the Redbank- Fancher Creeks Flood Control Project. This has resulted in a decrease in the areas designated for the 100-year floodplain. However, as noted in the Fresno County General Plan Background Report, the 100-year storm event flows have increased from 18,000 cfs to 24,500 cfs in the San Joaquin River over last few decades (due to increasing intensity of storms and statistical analysis of the meteorologic/hydrologic database for the San Joaquin River).

Kings River System

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
87 Uncontrolled creeks within the Kings River system, notably Mill Creek, continue to challenge management of Pine Flat Dam and Kings River flood control during consecutive large storm events. In 1997, water was not released from Pine Flat due to large flows in Mill Creek, which pushed the limits of the system. If another large event had occurred before Pine Flat Reservoir releases could provide adequate storage space and the Mill creek watershed was still saturated, rapid runoff in Mill Creek and an emergency spill at Pine Flat would have overwhelmed the system. In the event of a major release from Pine Flat Dam, downstream flooding would occur over agricultural lands near the riverbanks and possibly within the Cities of Reedley and Kingsburg.

Western Fresno County Flood Problem Areas
Flood issues in western Fresno County are varied in scope and unique in nature. Many creeks prone to high flows and significant erosion are found in the area, but most of the region is unpopulated, so flooding in many areas poses little threat to life or personal property. Major facilities that are subject to flooding include Interstate 5 and the California Aqueduct. Urban areas subject to flooding include the communities of Coalinga, Huron, and Mendota. Important wetland habitat in the Mendota Wildlife Management Area is also subject to flooding and may be impacted by sediments carried by flood flows from these creeks.

During large storm events, the California Aqueduct is flooded by high flows from Arroyo Pasajero.

Consequently, the Bureau of Reclamation, the Corps, and the DWR are coordinating efforts to relieve the threat of flooding from this stream system. Other stream systems obstructed by the aqueduct may pose a flooding hazard during periods of high flow when ponds form on the west side of the aqueduct.

The streams carry large amounts of sediment. When ponds fill with sediment, water spills into the aqueduct.

Various stream systems also flood developed areas in western Fresno County during storm events.

Creeks that feed into Arroyo Pasajero flow through the City of Coalinga, creating flood hazards and preventing development in impacted areas. Downstream, Arroyo Pasajero is prone to flooding the road into the City of Huron. After crossing the California Aqueduct, Panoche Creek flows overland and floods both agricultural land and portions of the City of Mendota.

The Mendota Wildlife Management Area receives water from Panoche Creek, which drains into Mendota Pool. During storm events, the sediments carried in Panoche Creek contain high levels of selenium and arsenic, which may degrade the water quality in the Mendota Wildlife Management Area.

Localized Flooding Problem Areas
Localized flooding also occurs throughout the County with several areas of primary concern. According to the Fresno County Department of Public Works, numerous roads throughout the County are subject to flooding in heavy rains. In addition to flooding, damage to these areas during heavy storms includes pavement deterioration, washouts, landslides/mudslides, debris areas, and downed trees. The amount and type of damage or flooding that occurs varies from year to year, depending on the quantity of runoff. Flooding problems are tracked by road maintenance area (see Figure 17. Fresno County Road Maintenance Areas) and noted below.

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
88 Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno - GIS

Figure 20. Fresno County Road Maintenance Areas

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024
89 A1. Firebaugh Area
The following roads in Area #1 are subject to flooding in heavy rains and flooding signs are required. • Washoe at Delta Mendota Canal southeast of Bridge
• Herndon at Russell
• Belmont from San Diego to Fairfax
• Shaw between Milux and Russell
• Washoe .01 miles north of California
• Shields at Fairfax southwest corner
• Russell 1.9 miles south of Shields
• Little Panoche, numerous areas 1.3 miles west of Interstate 5 to C/L • Milux at Bullard, west side
• Bullard east of Milux numerous areas to Fairfax
• Althea 1 mile west of Russell
• Hudson at Merrill northeast corner
• Fairfax at Valeria southwest corner
• Fairfax .02 miles south of Valeria
• Oxalis .04 miles west of Ormsby

A.2 Tranquility
Areas that flood east of James Road:
• Butte, American to North
• American, Denver to El Dorado
• El Dorado, American to Colorado
• Marin, Adams South .2 miles
• Sumner, Colorado to Placer
• Yuba, Manning to Colorado
• Parilier, Placer to Yuba
• Springfield, Colorado to Plumas
• Springfield, Colusa to Sutter
• Huntsman, Colorado to El Dorado
• Floral, Colorado to Graham
• Rose, Colorado to Trinity
• Napa, at drain ditch crossing (Nebraska)?

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90 • Kamm, Placer to Yuba
A.3 Coalinga
• Mt. Whitney
Areas that flood west of James Road:
• San Mateo north of State Route 180
• Sante Fe at San Benteo
• Jefferson Amador to Tuolumne
• Lincoln James Rd. to Calaveras
• Mt. View San Mateo to Monterey
• Clarkson San Mateo to Amador
• Amador Clarkson to Elkhorn
• Elkhorn Amador to Sonoma
• Sonoma Elkhorn to Mt. Whitney
• Kamm State Route 33 to Interstate 5
• Manning Aqua Duct to Interstate 5
• Douglas south of Manning .1 mile
• Douglas north of Manning 1 mile
• San Diego Adams to American
• Jensen San Diego to Washoe
• Coalinga-Mendota Road
• Parkfield
• Collwell east and west
• Boone
• Alcalde Road
A.3 Biola
• Dickenson Avenue, Herndon to Barstow
• Dickenson Avenue, south of North Avenue, east side
• Belmont Avenue, Grantland to Howard Avenue, various locations • Shields Avenue, Westlawn to Bishop Avenue, various locations • Shields Avenue west of State Route 145, various locations

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91 • Shaw Avenue west of State Route 145, various locations • Dower Avenue, Shields Avenue to Shaw Avenue, various locations • Henderson north of South Avenue, east side
• Brawley south of Lincoln
• Elm Avenue between Morton and Clayton Avenue.
• Adams-Clovis Avenue to State Route 99
• Central at Blyth to Cornelia
• Grantland south of Shaw, east side
• Grantland south of Belmont to RXR tracks, east side

A.5 Caruthers
• Floral west of Temperance
• Fowler at Davis
• McCall south of Clarkson
• Fowler north of Elkhorn
• Temperance south of Conejo
• Dewolf north of Mt. View
• Clovis north of Nebraska
• Harlan between Maple and Chestnut

A.7 Fresno-Clovis
• Copper between Minnewawa and Fowler
• Copper near Armstrong
• Armstrong between Copper and International
• International between Flower and Armstrong
• Fowler between International and Shepherd
• Behymer between Willow and Minnewawa
• Behymer between Minnewawa and Fowler
• Sunnyside between Teague and Nees
• Teague between Fowler and Armstrong
• Marion between Teague and Nees
• Shaw between McCall and Leonard
• Academy between Herndon and Shaw

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92 • Sierra between Academy and Del Rey
• Herndon between Academy and Madsen
• Madsen between Herndon and Shepherd
• Shepherd between SH 168 and Academy
• Shepherd between Fowler and Armstrong
• Gettysburg between Van Ness and Wishon
• Sierra between Forkner and Van Ness Extension
• College between Swift and Santa Ana

A.8 Fresno-Sanger
This is not a complete list as there are many locations that pool at the shoulder or just onto the road.

Large or back-to-back storms can change all.
• Jensen at Sierra Vista
• Shields/Locan
• National east of Minnewawa
• Monticeto/Rogers
• Fowler at Princeton
• Butler east of Locan
• Gettysburg/Greenwood
• McKinley west of Bethel
• McKinley at Leonard
• Indianola south of Highway 180
• Dewolf/Church
• Bond/Mayfair Drive North
• Griffith east of Clovis
• Dakota east of Highland
• Fowler at Olive
• Walling north of Kings Canyon
• Olive east of Hornet
• Temperance north of Church
• Temperance north of Jensen
• Locan north of Church
• Highland north of Jensen

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93 • Zediker south of Belmont
• Tulare west of Zediker
• Newmark north of Belmont
• Macdonough north of Belmont
• Newmark north of Highway 180
• California east of Dockery
• McCall/Tulare
• Tulare east of McCall
• Indianola at Jensen
• Olive/Zediker
• Thompson north of Dakota
• Rancho at Butler
• Illinois west of Villa
• Madison west of Clovis
• Grant west of Clovis
• Washington west of Clovis
• Easterby Drive Southwest of Minnewawa
• Easterby Drive Northwest of Minnewawa
• Brown at Jackson

A.9 Sanger-Del Rey
• American between Academy and Armstrong
• Central between McCall and Willow
• Bethel south of Adams 100-500 feet
• Bethel between Manning and Rose
• Willow between North and Jensen
• Nebraska from Academy to city limits and at intersection of Bethel

A.10 Reedley-Dunlap
• Alta at Manning
• Zediker south of Caruthers
• South at Zediker
• Reed at Floral

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94 • Reed at South
• Adams between Zediker and Smith
• Smith at Dinuba
• Hill between Sumner and Adams
• Monson south of Parlier (this might be the City of Orange Cove)

LEVEE FAILURE
A levee is a raised area that runs along the banks of a river or canal. Levees reinforce the banks and help prevent flooding. By confining the flow, levees can also increase the speed of the water. Levees can be natural or man-made. A natural levee is formed when sediment settles on the riverbank, raising the level of the land around the river. To construct a man-made levee, workers pile dirt or concrete along the riverbanks, creating an embankment. This embankment is flat at the top, and slopes at an angle down to the water. For added strength, sandbags are sometimes placed over dirt embankments.

Levees provide strong flood protection, but they are not failsafe. Levees are designed to protect against a specific flood level and could be overtopped during severe weather events. Levees reduce, not eliminate, the risk to individuals and the structure behind them. A levee system failure or overtopping can create severe flooding and high-water velocities. It’s important to remember that no levee provides protection from events for which it was not designed, and proper operation and maintenance are necessary to reduce the probability of failure.

There are three primary risks to levee integrity in Fresno County:
▪ Earthquake failure
▪ High water failure
▪ Dry weather failure.

EARTHQUAKE FAILURE
Seismic risk in the Fresno area is characterized as moderate-to-high because of many active faults in the area. Figure 16. California's Fault Lines illustrates the locations of faults in and surrounding Fresno County. Seismic risk to levees stems from the risk of liquefaction, ground settlement, and cracking.

HIGH WATER FAILURE
High water in the County can overtop levees. High water also increases the hydrostatic pressure on levees and their foundations, causing instability, shown in Figure 18. Levee Failure Process. The risk of through-levee and under-levee seepage failures increases as well.

Under-seepage refers to water flowing under the levee through the foundation materials, often emanating from the bottom of the landside slope and ground surface and extending landward from the landside toe of the levee. Through-seepage refers to water flowing through the levee prism directly,

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95 often emanating from the landside slope of the levee. Both conditions can lead to failure by several mechanisms, including excessive water pressures causing foundation heave and slope instabilities, slow progressing internal erosion, and piping leading to levee slumping.

Overtopping failure occurs when the flood water level rises above the crest of a levee. The representation of the failure modes and the evaluation of the probability of levee failures for each mode are discussed in the remaining sections.

Source: Reclamation District 1000

Figure 21. Levee Failure Process

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96 DRY WEATHER FAILURES
Dry weather, or sunny days, failures are levee breaches that are not flood or seismic related. These failures typically occur between the end of the late snowmelt from the Sierras, in late May, and the beginning of the rainy season, in early October. Sunny-day failures are addressed separately from flood-induced failures to differentiate between winter and summer events. Aside from seismic events, factors that can cause levee failures in the County in the summer period are different than the factors that can cause winter failures.

Burrowing animal activities and pre-existing weaknesses in the levees and foundation are the key weak links leading to levee failures. This is the case whether or not the failures occur during a high-tide condition. Burrowing animals can cause undue weaknesses by creating a maze of internal and interconnected galleries of tunnels. Tree growth on levees may cause weakness as well.

Under-seepage and through-levee seepage are slow processes that tend to work through time by removing fines from levee and foundation material during episodes of high river levels. Cumulative deterioration through the years can lead to foundations ultimately failing in dry weather by means of uncontrollable internal erosion that leads to slumping and cracking of levees.

FLOODPLAIN MAPPING
FEMA established standards for floodplain mapping studies as part of the National Flood Insurance Program (NFIP). The NFIP makes flood insurance available to property owners in participating communities adopting FEMA-approved local floodplain studies, maps, and regulations. Floodplain studies that may be approved by FEMA include federally funded studies; studies developed by state, city, and regional public agencies; and technical studies generated by private interests as part of property annexation and land development efforts. Such studies may include entire stream reaches or limited stream sections depending on the nature and scope of a study. A general overview of floodplain mapping is provided in the following paragraphs. Details on the NFIP and mapping specific to participating jurisdictions are in the jurisdictional annexes.

▪ Flood Insurance Study (FIS): The FIS develops flood-risk data for various areas of a community that is used to establish flood insurance rates and to assist the community in its efforts to promote sound floodplain management. The current Fresno County FIS is dated January 20, 2016. This study covers both the unincorporated and incorporated areas of the County. ▪ Flood Insurance Rate Map (FIRM): The FIRM is designed for flood insurance and floodplain management applications. For flood insurance, the FIRM designates flood insurance rate zones to assign premium rates for flood insurance policies. For floodplain management, the FIRM delineates 100- and 500-year floodplains, floodways, and the locations of selected cross sections used in the hydraulic analysis and local floodplain regulation.
▪ Letter of Map Revision (LOMR) and Map Amendment (LOMA): LOMRs and LOMAs represent separate floodplain studies dealing with individual properties or limited stream segments that update the FIS and FIRM data between periodic FEMA publications of the FIS and FIRM. ▪ Digital Flood Insurance Rate Maps (DFIRM): As part of their Map Modernization program, FEMA is converting paper FIRMS to digital FIRMs (DFIRMS). These digital maps: incorporate the latest updates (LOMRs and LOMAs), utilize community supplied data, verify the currency of the floodplains and refit them to community supplied base maps, Upgrade the FIRMs to a GIS

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97 database format to set the stage for future updates and to enable support for GIS analyses and other digital applications, and solicit community participation.

To describe the flood hazard areas for a specific area, FEMA uses flood zone designations which include Zone V, Zone VE and C 1-30, Zone A, Zone AE, Zone AH, Zone AO, Zone X (shaded), and Zone X (unshaded). The flood determinations and their descriptions used in floodplain mapping are described in the table below.

Table 27. Floodplain Zone Designations
Zone
Designation
Percent Annual
Chance of Flood Description
Zone V 1%
Areas along coasts subject to inundation by th
e 1% annual chance of flooding with additional
hazards associated with storm-induced
waves. Because hydraulic analyses have not
been performed, no base flood elevations
(BFEs) or flood depths are shown.

Zones VE and V1-30 1%
Areas along coasts subject to inundation by th
e 1% annual chance of flooding with additional
hazards associated with storm-induced
waves.

BFEs derived from detailed hydraulic analyses
are shown within these zones. (Zone VE is us
ed on new
and revised maps in place of Zones V1-30.)
Zone A 1%
Areas with a 1% annual chance of flooding an
d a 26% chance of flooding over the life of a
30-year mortgage.

Because detailed analyses are not performed
for such areas, no depths or BFEs are
shown within these areas.

Zone AE 1%
Areas with a 1% annual chance of flooding
and a 26% chance of flooding over the life of
a 30-year mortgage. In most instances, BFEs
derived from detailed analyses are shown at
selected intervals within these zones.

Zone AH 1%
Areas with a 1% annual chance of flooding
Where shallow flooding
(usually areas of ponding) can
occur with average depths between 1 – 3
feet.

Zone AO 1%
Areas with a 1% annual chance of flooding, w
here shallow flooding average depths are bet
ween 1 – 3 feet.

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98 Zone
Designation
Percent Annual
Chance of Flood Description
Zone X
(shaded) 0.2%
Represents areas between the limits of the 1
% annual chance of flooding and 0.2% chance
of flooding.

Zone X (unshaded) Undetermined
Areas outside of the 1% annual chance
floodplain and 0.2% annual chance floodplain;
areas of 1% annual chance sheet flow
flooding where average depths are less than
one (1) foot; areas of 1% annual chance
stream flooding where the contributing
drainage area is less than one (1) square mile,
or areas protected from the 1% annual chance
flood by levees. No BFE or depths are shown
within this zone.

Source: FEMA

COMMUNITY RATING SYSTEM
As part of the NFIP, the Community Rating System (CRS) is a voluntary incentive program that recognizes and encourages community floodplain management practices that exceed the minimum requirements.

CRS communities have flood insurance premium rates discounted to reflect reduced flood risk resulting from the community’s efforts that address the three goals of the program. With an updated hazard mitigation plan, lower flood insurance premiums will be provided for the jurisdictions that participate in the National Flood Insurance Program’s Community Rating System.

According to the FEMA Community Status Book, accessed on March 27, 2024, Fresno County joined the CRS on May 1, 2016, and has a CRS class of 7 which provides a 15 percent SFHA discount and

0.05 percent non-SFHA discount. Additionally, the County joined the NFIP on October 1, 1991.

Table 28. Community Rating System (CRS) Credits and Discounts CRS Class CRS Discount Credit Points Required
1 45% 4,500+
2 40% 4,000-4,499
3 35% 3,500-3,999
4 30% 3,000-3,499
5 25% 2,500-2,999

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99 CRS Class CRS Discount Credit Points Required
6 20% 2,000-2,499
7 15% 1,500-1,999
8 10% 1,000-1,499
9 5% 500-999
10 0% 0-499
Source: FEMA
The flood mitigation activities and their points are listed below. The total number of points will equal to a CRS class and then determine the CRS discount for flood insurance for the community.

Table 29. Community Rating System (CRS) Mitigation Actions and Points Series
300 Mitigation Actions Maximum
Points
Average
Points

This series of credits programs advise people about flood hazards, flood insurance, and ways to reduce flood damage. The activities also provide data insurance agents need for accurate flood insurance rating.

310
Elevation Certificates
• Have written procedures for managing floodplain-related certificates for new constructions in the floodplain. (at a minimum, a community must maintain certificates for buildings built after the date of its CRS application)
• Maintain a rate of 90% accuracy
116 36
320
Map Information Service
• Provide Flood Insurance Rate Map information to those who inquire, and publicize this service
90 78
330
Outreach Projects
• Distribute outreach projects with messages about flood hazards, flood insurance, flood protection measures, and/or the natural and beneficial functions of floodplains
350 87
340
Hazard Disclosure
• Real estate agents advise potential purchasers of flood-prone property about the flood hazard
• Regulations require notice of the hazard
80 15
350
Flood Protection Information
• The public library and/or community's website maintains references on flood insurance and flood protection
125 48

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100
Series
300 Mitigation Actions Maximum
Points
Average
Points
360
Flood Protection Assistance
• Give inquiring property owners technical advice on protecting their buildings from flooding and publicize this service 110 59
370
Flood Insurance Promotion
• Assess flood insurance coverage in the community; promote flood insurance through meetings, technical assistance, brochures, or other means
• This series credits programs that limit floodplain development or provide increased protection to new and existing development 220 40
410
Floodplain Mapping
• Develop new flood elevations, floodway delineations, wave heights, or other regulatory flood hazard data for an area not mapped in detail by the flood insurance study
• Have a more restrictive mapping standard
850 78
420
Open Space Preservation
• Guarantee that currently open public or private floodplain parcels will be kept free from development
• Incentivize keeping the floodplain open with zoning restrictions, lot size requirements, or other regulations
2,870 471
430
Higher Regulatory Standards
• Limit new buildings and/or fill in the floodplain
• Require freeboard
• Require soil tests or engineered foundations
• Require compensatory storage
• Require coastal construction standards in AE Zones
• Have regulations tailored to protect critical facilities or areas subject to special flood hazards such as alluvial fans, ice jams, subsidence, coastal erosion
2,462 272
440
Flood Data Maintenance
• Keep flood and property data on computer records
• Use better base maps
• Maintain elevation reference marks
222 127
450
Stormwater Management
• Regulate new development throughout the watershed to ensure that post-development runoff is no greater than pre-development runoff.
• Regulate new construction to minimize soil erosion and protect or improve water quality
755 110
510
Floodplain Management Planning
• Using a standard process, prepare, adopt, implement, and update
• A comprehensive flood hazard mitigation plan and/or
762 197

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101
Series
300 Mitigation Actions Maximum
Points
Average
Points
• Plan to protect natural functions within the community's floodplain and/or
• A plan for managing substantial flood damage to properties in the community and/or
• A plan to serve and/or recover threatened and endangered species in the floodplain
• Prepare an analysis of the repetitive flood loss areas within the community

*** relates to hazard mitigation planning
520
Acquisition and Relocation
• Acquire and/or relocate flood prone buildings so that they are out of the floodplain, and the floodplain remains open
2,250 176
530
Flood Protection
• Protect existing floodplain development by floodproofing, elevation, or minor flood control projects.
1,600 64
540
Drainage System Maintenance
• Have a program for and conduct annual inspections of all channels and detention basins; remove debris as needed
470 203
610
Flood Warning and Response
• Provide early flood warning to the public, and have a detailed flood response plan keyed to flood crest predictions
• Incorporate substantial damage assessment into flood
operations
365 266
620
Levees
• Annually inspect and maintain existing levees; have a system for recognizing the threat of levee failure and/or overtopping, disseminating warnings, and providing emergency response; and coordinate with operators of critical facilities
235 111
630
Dams
• Have a high-hazard potential dam that could affect the community; have a system for recognizing the threat of dam failure, disseminating warnings, planning, and practicing emergency responses; and coordinating with operators of critical facilities.
160 38
Source: FEMA

LEVEE MAPPING
As part of FEMA’s Map Modernization program, FEMA is mapping levees within communities, with a primary focus on maps determined to provide a 100-year level of flood protection. Most of the levees are privately owned, maintained, and operated. Because of the ownership and lack of enforcement for

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maintenance, most of the levee systems do not meet the current standards for flood protection and are mapped as such.

As part of the flood mapping process, the Federal Emergency Management Agency (FEMA), and its State and local mapping partners, review and evaluate levee system data and documentation. Any community and/or other party seeking recognition or continued recognition of a levee system on a Flood Insurance Rate Map (FIRM) must provide FEMA with data and documentation, certified by a registered professional engineer, showing that the levee system is expected to provide 1-percent- annual-chance (base) flood risk reduction. To be mapped on a FIRM as providing base flood risk reduction, levee systems must meet and continue to meet the NFIP minimum design, operation, and maintenance requirements described in Title 44, Chapter 1, Section 65.10 of the Code of Federal Regulations (44 CFR 65.10).19
Provisionally Accredited Levee System (PAL)
In Fresno County, similar to other locations in California, levees and flood control facilities have been built and are maintained variously by public and private entities, including water, irrigation and flood control districts, other state and local agencies, and private interests.

To best address the issue of levees in the DFIRM process, FEMA provided guidance for the issuance of PAL (provisionally accredited levee) agreements that would allow for identified levees to be provisionally accredited for purposes of mapping while communities/levee owners compile and submit data and documentation necessary for full accreditation. Communities have two years from the date of FEMA’s initial coordination to submit to FEMA final accreditation data for all PALs. Levees for which such agreements were signed are shown on the final effective FIRM as providing protection from the flood that has a 1-percent-chance of being equaled or exceeded in any given year and labeled as a PAL. Following receipt of final accreditation data, FEMA will revise the FIS and FIRM as warranted.

Levee Flood Protection Zone (LFPZ)
FEMA-designated 100-year and 500-year floodplains in Fresno County that were updated under the Map Modernization Program and became effective on January 20, 2016. The State of California (DWR) completed levee flood protection zone (LFPZ) maps in December 2008 of areas that may be inundated if a project levee fails (from water surface elevations at the top of the levee, which may be from a storm event even larger than the levee’s design storm). The LFPZ map of the San Joaquin River shows a considerable area within Fresno County that may be inundated if the project levees fail.

A relatively broad levee flood protection zone (LFPZ) is identified along the San Joaquin River, with depths less than three feet indicated west of the river, but greater than three feet all along the east side of the river. Several areas protected by project levees in the east county would also have inundation areas that are primarily less than three feet but include some deeper areas. Fresno County’s levee system can be seen in Figure 19. Fresno County Levee System.

19 https://www.fema.gov/sites/default/files/documents/fema_meeting-criteria-accrediting.pdf

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Source: CA Geoportal: CA-DFW; CalTrans; USACE-National Levee Database: County of Fresno - GIS

Figure 22. Fresno County Levee System

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EXTENT
Small - Fresno County is large and geographically diverse. Water resources in the Fresno County planning area include several rivers and streams, artificial waterways, and groundwater sources located throughout the County. The mountainous eastern portion of Fresno County, located primarily in the Sierra Nevada, contains many small mountain lakes and streams that are tributaries to the San Joaquin and Kings rivers, which flow into the Central Valley. The arid western portion of Fresno County is characterized by larger watersheds in the Coast Range that drain stormwater eastward into the valley and the Fresno Slough. Flash floods with depths of several feet can occur in the valleys of the Sierras, while large areas of relatively shallow inundation can occur in the Central Valley.

During winter and spring months, river systems in Fresno County swell with heavy rainfall and snowmelt runoff. To prevent flooding, a wide variety of storm drainage and flood control measures are used throughout the County. These include flood control reservoirs, levee systems, and watershed treatments. In rural areas, the management of reservoir releases, canals, and levee systems reduces the likelihood of flooding and reroutes stormwater around urban areas. In developed areas, storm drainage systems composed of street gutters, inlets, underground storm drains, ponds, pumping stations, and open channels are used to collect and control stormwater runoff. The storm drainage and flood control systems are discussed further in the sections that follow.

Figure 20. Fresno County Waterways illustrates natural and manmade waterways in the County.

Information on the County’s more notable waterways and associated flood control facilities extracted from the Fresno County General Plan Background Report is included below by region.

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Source: CA Geoportal: CA-DFW; CalTrans: County of Fresno-GIS; U.S. National Map Viewer, ½ Arc Sec. FEMA

Figure 23. Fresno County Waterways

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The map below illustrates the city’s mapped flood hazard areas. Flood hazard areas periodically change to reflect improved and updated mapping techniques as well as areas that may have been altered by flood mitigation projects, typically reflected in the development of the Conditional Letters of Map Revision (CLOMR) or Letters of Map Revision (LOMR). More detailed flood hazard maps are included in this Chapter.

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Source: CA Geoportal; CA-DFW; CalTrans; USACE-National Levee Database; FEMA-Map Service Center; DFIRM, 1/2016; County of Fresno - GIS

Figure 24. Fresno County Flood Hazard Areas

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LEVEE FAILURE EXTENT
The geographic extent of the levee hazard is shown in Figure 21. Fresno County Flood Hazard Areas and explained further in the Vulnerability portion of this plan.

PAST OCCURRENCES
Fresno County has a long history of flooding, Historical records indicate that nine significant flood events occurred in Fresno County between the 1840s and 1900. A series of river floods during the 1980s and 1990s prompted FEMA to drastically revise its estimate of the 100-year flood flows in the San Joaquin River channel and to develop a new FIRM for the area. Construction of major detention structures in the eastern part of the County along the Fresno County Stream Group enabled FIRMs to be revised in the early 1990s to show a reduced 100-year flood risk from the San Joaquin River to the metropolitan area. Within the past 70 years, there have been 53 recorded flood incidents within Fresno County. Detailed information on each of the flood events is described below.

▪ December 1955: A rain on snow event caused local and downstream flooding in eastern Fresno County, ultimately affecting the entire valley region. Homes were lost and roads and bridges were damaged or destroyed. Damage to some dam facilities also resulted. ▪ 1995: From January to March 1995, strong storms in the County led to severe flooding, road closures, a destroyed bridge on Interstate 5, hundreds displaced, and seven fatalities, particularly affecting the western region. Damages included twenty homes, $5 million to public facilities, over $8.6 million to agriculture, and $9 million in business impacts, with multiple infrastructure disruptions like road closures and compromised water systems. A local, state, and federal disaster was declared due to the extensive impact of the storms.
▪ 1997: A regionwide rain on snow event in high elevations caused local flooding and flooding downstream in the valley. Homes, bridges, roads, and other infrastructure near waterways were damaged. A bridge on Interstate 5 over the Kings River was washed out. Losses to infrastructure were estimated in the hundreds of millions. Other impacts included damage to fisheries and wildlife. ▪ 1998 (El Niño rain event): In 1998, Fresno County was hit by extensive rainfall over 33 days within a six-month period, causing widespread flooding and prompting local, state, and federal emergency declarations. Property and public facility damage totaled nearly half a million dollars, while the farming industry suffered a $17 million loss, primarily impacting tree fruit and row crops. The community faced substantial economic impacts between $38-48 million, and the agricultural workforce experienced significant unemployment and reduced work hours. ▪ April 28, 2005 (Parlier Flood): A cell of severe weather passed over the City of Parlier dropping up to three inches of rain in 20 minutes. The drainage system could not handle the flow, and approximately 25 homes and businesses were flooded. The City of Parlier declared a local disaster, as did Fresno County. Damage was estimated at $700,000. Homeowners had little or no insurance coverage. In addition, J Street was closed for one day. ▪ 2005-2006: Above average rainfall occurred between December 19, 2005, and January 1, 2006.

This resulted in flooding of low-lying areas throughout the County. Flood control basins were overflowing in several areas, including the Cities of Fresno and Clovis. Property damage included damage to approximately 180 businesses and homes estimated at $1.4 million within the unincorporated County. Damage to other jurisdictions was estimated at $611,307. Damage to crops

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was minimal due to the time of year. Flooding further resulted in several road closures, which were one to two weeks in duration.
▪ April 5, 2006: Heavy rainfall and snowmelt caused high runoff into the San Joaquin and Kings River drainages, putting levees and river channels at risk, although they ultimately held. A flood fighting team from the Department of Water Resources (DWR) and construction crews worked to reinforce the system, resulting in minimal property and crop damage, except for 200 acres in the Tranquility Irrigation District affected by a levee break. Despite the damage to the levee, canal systems, and river channels, disaster declarations were made due to the potential for more severe consequences had there been system failures.
▪ July 2006: Flash floods from thunderstorms in drainages above the north end of Huntington Lake resulted in a variety of damage. This included an estimated $250,000 in damage to private boats and an estimated $200,000 in damage to local infrastructure (roads, boat docks, etc.). Other impacts included loss of power for three weeks in some areas, closure of a primary summer road for one week, and closure of Huntington Lake to recreational use for one week. Cleanup costs exceeded $150,000, and search and rescue costs were estimated at $25,000. ▪ October 29, 2007: Newspapers and broadcast meteorologists reported several roadways flooded in Northwest Fresno. Numerous vehicles were stranded, and water rescues occurred. Heavy rain caused a roof to collapse at an industrial plant on the northwest side of the city. Damage was estimated at 250,000 to the roof structure alone. Total property damage associated with the event amounted to over $500,000.
▪ December 2007: Heavy rain and snowstorms ravaged central California, including the San Juaquin Valley and Fresno metropolitan area. The combination of locally heavy rains and poor drainage areas within the urban and suburban land lead to over $175,000 in property damage between December 18th and 19th.
▪ December 29, 2010: On the morning of the 29th, heavy rain across the San Joaquin Valley caused widespread urban and poor drainage flooding. Especially hard hit were the metro areas of Fresno, Visalia, and Bakersfield, and the adjacent foothills. Fresno had a record rainfall of 0.92 inch on the 28th, breaking the old record of 0.72 inch, set in 2004. The two-day total at Fresno-Yosemite International Airport was 1.54 inch, which pushed the December rainfall to 5.92 inches for the second wettest December on record for Fresno; the wettest December was in 1955, with 6.73 inches. It was also the coldest low of the year for Fresno, with temperatures dropping below 32 degrees. Property damage amounted to $125,000.
▪ November 30, 2011: Fresno set record high minimum temperatures on the last day of the month, establishing the total record for the sixth warmest November. This was also the fourth consecutive month that Fresno ranked in the top 10 warmest months. Fresno had a record rainfall on November 30th of 0.62 inch; the old record was 0.50 inch. As a result of the heavy rainfall, some rock and mud slides occurred as the moisture weakened the soil. Law enforcement reported a rock and mud slide on Highway 168 about 15 miles northeast of Clovis, which closed the road for several hours while authorities cleaned up the debris.
▪ 1/07/2017: A series of systems fed by a continued influx of very moist air was pushed into the central California interior through an atmospheric river set-up for several days. This created high snow levels between 9,000-10,000 feet and heavy rainfall for much of the San Joaquin Valley County Warning Area which in turn created flooding and flash flooding of area rivers, streams, and water supply canals. Also, debris flows, rockslides, and road ponding/flooding were reported. ▪ 1/20/2017: A nearly stationary cold low-pressure system from the Pacific Northwest moved into central California and tropical moisture being fed from the Pacific with a continued atmospheric river

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set-up, brought thunderstorms and heavy rainfall to the Sierra Nevada Mountains and Foothills and parts of the San Joaquin Valley over several days. Small pea-sized hail was also reported with some thunderstorms.
▪ 2/03/2017: Tropical influx jet pushed into central California ahead of a cold front created heavy rains which were enhanced by orographically lifting with the Sierra Mountains. ▪ 2/07/2017: Atmospheric River system brought heavy rainfall, flooding, debris flows, and high elevation snowfall to the central California region. Damages were over $100,000 and the California Highway Patrol reported road closure due to a bridge collapse from heavy rainfall near Sugarloaf Road and Auberry Road just northeast of Meadow Lakes.
▪ 2/20/2017: A series of strong low-pressure systems accompanied with tropical moisture influxes brought strong winds, heavy rainfall, flooding, debris flows, funnel cloud reports, and high elevation snows to the central California region. Precipitation was enhanced at times by orographically lifting. ▪ 6/19/2017: Between June 18 and June 29, significant water releases from Pine Flat Dam caused flooding along the Kings River, prompting evacuations and levee breaches near Kingsburg, affecting homes, and prompting a large-scale sandbagging operation. The second levee breach on June 24 threatened 90 homes in Tulare County, leading to the evacuation of 300 people and damaging 7 structures. Water levels receded by June 29 after releases from the dam were reduced on June 26, ending the immediate flood threat.
▪ 3/21/2018: From March 20 to 22, a surge of tropical moisture led to heavy rainfall, causing widespread flooding, road closures from rockslides and debris flows, particularly in Mariposa and Springville near recent burn scars. Thunderstorms on March 22 exacerbated conditions, prompting flash flood emergencies, evacuations, and a tornado touchdown near Dinuba. While the Southern Sierra Nevada received 4 to 8 inches of rain, the San Joaquin Valley saw 1 to 3 inches, with several feet of snow accumulating above 9000 feet.
▪ 10/03/2018: On October 2, an upper-level low pressure system brought light rainfall across the San Joaquin Valley and more significant rain in the Southern Sierra Nevada, followed by scattered thunderstorms on October 3 that led to moderate to heavy rainfall and numerous flooding reports.

The Ferguson Fire burn scar experienced flash flooding with debris flows and washed-out roads, while the San Joaquin Valley and Southern Sierra received one to two inches of rain. The system moved east by October 4, ending the precipitation event with snow levels remaining high at above 11000 feet, limiting snowfall to the higher peaks.
▪ 11/21/2018: Following a 45-day dry spell in central California, a low-pressure system on November 21 brought light to moderate precipitation, marking the first significant winter storm with 8 to 16 inches of snow above 7000 feet in the Southern Sierra Nevada. The San Joaquin Valley received a quarter to three-quarters of an inch of rain, ending its dry streak. This weather event resulted in minor nuisance flooding reports across the region.
▪ 12/16/2018: A cold front that was associated with a moist upper trough pushed across central California on December 17. This system brought moderate to locally heavy rainfall from Fresno County northward the late evening of December through the morning of December 17 where several stations reported a half inch to an inch and a quarter of rainfall, and there were several reports of mainly nuisance flooding during this time. The precipitation mainly fell as snow above 6500 feet where several stations in the Southern Sierra Nevada north of Fresno County picked up between 3 and 6 inches of new snow. Further south the rainfall was less plentiful with most locations receiving between a few hundredths of an inch to a quarter of an inch of rain by the time the precipitation ended by early afternoon on December 17.

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▪ 2/02/2019: On February 2, a strong low-pressure system brought high winds to the Grapevine area, extending to Bakersfield, causing tree and wind damage, followed by moderate to heavy precipitation that led to roadway flooding. The San Joaquin Valley received over an inch of rain, while mountain areas got 2 to 5 inches, mainly as snow above 5000 feet, with SNOTEL stations reporting several feet of new snow. Additional thunderstorms later in the day produced hail, more rainfall, and a small tornado south of Maricopa.
▪ 2/14/2019: Between February 13 and 17, a potent low-pressure system brought heavy rainfall, strong winds, and a drop in snow levels from nearly 9000 feet to 1500 feet, causing widespread flooding and road closures in central California. Thunderstorms with hail and a small tornado followed a cold front on February 15, while the Southern Sierra Nevada received up to 20 inches of new snowfall. Overall, the San Joaquin Valley accumulated up to an inch and a half of rain, and the Tehachapi Mountains saw 1 to 2 inches of liquid precipitation. ▪ 3/02/2019: A strong storm system on March 2 brought light to heavy precipitation to central California, with thunderstorms causing flooding and a tornado near Mendota. The Southern Sierra Nevada received 1 to 3 inches of liquid precipitation, while the San Joaquin Valley and Kern County Mountains accumulated up to an inch of rain. The storm, which initially held snow levels above 8000 feet, exited the region by March 3 after dropping snow levels to around 5000 feet and leaving the Kern County Deserts with up to half an inch of rainfall. ▪ 5/26/2019: On May 25, a strong upper low-pressure system moved southward, bringing instability and scattered thunderstorms to the San Joaquin Valley, with one storm producing nickel-sized hail and roadway flooding near Mettler and Maricopa. The system continued through California on May 26, causing widespread rainfall, mountain snow, and gusty winds, with the Sierra Nevada receiving 2 to 5 inches of snow and some areas experiencing heavy rainfall and wind gusts over 35 mph.

Record-breaking daily precipitation was recorded on May 26 across the region, reflecting the system's significant impact.
▪ 5/29/2019: Following cool temperatures, the area warmed up on May 28, leading to seasonable conditions and daily afternoon showers and thunderstorms due to abundant moisture. On May 31, storms in the mountains contributed to heavy rainfall, snowmelt, and significant runoff, causing river levels in the San Joaquin Valley to rise rapidly, notably along the Kings River due to Pine Flat Dam releases. This led to flooding at Lindy's Landing campground near Reedley and the Kings River Golf and Country Club near Kingsburg from May 29, continuing beyond month's end. ▪ 6/01/2019: Because of continued increased releases at Pine Flat Dam. Runoff continued to produce flooding at Lindy's Landing campground near Reedley, and the Kings River Golf and Country Club near Kingsburg well into June. The releases were cut back during the middle of the month and the flood waters receded by the evening of June 19.
▪ 12/08/2019: During December 7-8, a trough brought widespread rain to California, with 1-2 inches in the Sierra and up to an inch in the San Joaquin Valley, while areas further south received less.

The snow levels stayed between 7000 and 8000 feet, leading to 8-12 inches of new snow in the higher elevations. Scattered thunderstorms also caused localized heavy rainfall, roadway flooding, and small hail before the system moved eastward, ending the precipitation by late evening. ▪ 12/22/2019: On December 22 and 23, a frontal system brought strong winds and substantial precipitation across central California, with gusts over 50 mph in the foothills and mountains, and some areas near Lebec experiencing winds over 75 mph. The Sierra Nevada and adjacent foothills received 1 to 1.5 inches of rain, while the San Joaquin Valley had reduced totals due to rain shadowing, and central Tulare County saw moderate to heavy rainfall as the low-pressure center

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moved north. Above 5000 feet, the precipitation turned into heavy snow, with 10 to 15 inches reported in the higher Sierra regions.
▪ 3/25/2020: Between March 20 and March 29, central California experienced a series of weather systems, one of which brought heavy precipitation on March 22 and 23 with up to an inch of liquid precipitation and 8 to 12 inches of snow above 7000 feet in the Sierra Nevada. Another system on March 25 and 26 triggered strong winds, thunderstorms, hail, and localized flooding, with snowfall reaching down to 4000 feet. The final system on March 29 delivered lighter precipitation, capping off a period of significant weather activity across the region. ▪ 4/17/2020: On April 16-17, a low-pressure system near California's coast moved inland, bringing widespread showers and thunderstorms, causing localized heavy rainfall and some flooding through April 18. While rainfall amounts varied, some areas received nearly an inch, and most saw up to half an inch. Above 7000 feet, snowfall ranged from 2 to 5 inches in the higher Sierra Nevada. ▪ 5/18/2020: A low pressure system moving across central California on May 18 brought widespread precipitation, with the Sierra Nevada receiving up to 3.25 inches of rain and snow levels dropping to around 6000 feet, leading to new snowfall at higher elevations. Thunderstorms in the afternoon triggered nuisance flooding on roadways in several communities, while areas in the Kern County Deserts and surrounding mountains experienced strong wind gusts up to 70 mph. The storm and associated effects, including the strong winds, subsided by the late morning of May 19 as the system exited the region.
▪ 1/28/2021: A powerful storm system swept through central California from January 27 to January 29, bringing heavy rainfall and strong winds that resulted in significant flooding, power outages, and downed trees. The system, energized by a deep moisture surge, unloaded 4 to 7 inches of rain in the Sierra foothills and 2.5 to 4 inches in the northern San Joaquin Valley, with the southern valley and Kern County receiving up to an inch, causing roadway flooding and triggering mudslides in burn scar areas. As the storm progressed, it also dumped 4 to 6 feet of snow in higher elevations of the Sierra Nevada, leading to travel restrictions and road closures before moving out of the area by the afternoon of January 29.
▪ 10/25/2021: A significant low-pressure system, fueled by tropical moisture from Typhoon Namtheun, brought intense rainfall to central California, leading to moderate to heavy precipitation and resulting in widespread flooding across the region, particularly in the San Joaquin Valley and adjacent foothills. As the storm progressed inland on October 25, it unleashed heavy rains and caused flash flooding, with snow levels above 9000 feet initially, then dropping to 6000 to 7000 feet, leading to substantial snowfall in the higher elevations. The system's impact was compounded by strong winds and thunderstorms but concluded with the precipitation and wind diminishing by the morning of October 26 as it moved eastward.
▪ 12/14/2021: In mid-December, a potent low-pressure system from the Gulf of Alaska brought significant moisture to central California, leading to 2 to 4 inches of rain in the Sierra Nevada and causing widespread minor flooding and rockslides in the San Joaquin Valley and adjacent foothills.

The storm's intensity resulted in heavy snowfall above 5500 feet, with snow levels dropping to 1500 feet, and strong winds that led to road closures and travel restrictions. High winds with gusts over 50 mph, and up to 70 mph near Grapevine, exacerbated the hazardous conditions, adding to the storm's impact on infrastructure and travel.
▪ 12/23/2021: In late December, a deep upper trough delivered rain and snow to central California, with the Sierra Nevada receiving 1 to 3 inches of liquid precipitation and snow levels hovering between 8000 to 9000 feet. Rain shadow effects resulted in varying rainfall in the San Joaquin Valley, while cooler air later introduced showery conditions and lowered snow levels to 5500 feet.

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High elevation areas estimated 18 to 24 inches of new snow before the weather system gradually receded.
▪ 12/10/2022: In December, central California experienced a strong low-pressure system that brought substantial snowfall, accumulating 18 to 30 inches above 5000 feet and significant rain in the Sierra Nevada and foothills. Snow levels dropped to 3000 feet, leading to 3 to 6 inches of fresh snow in higher elevations and up to 5 inches of rain in lower areas, with the San Joaquin Valley and Tehachapi Mountains receiving up to an inch of rain. The system abated by midday on December 12 after diminishing the previous evening.
▪ 12/27/2022: A potent low-pressure system traversing California on December 27 drew in substantial tropical moisture, causing widespread heavy rainfall and triggering a fatal rockslide in Yosemite National Park. The storm blanketed the higher Sierra Nevada with 18 to 30 inches of snow above 7500 feet, while the foothills and valleys received 1 to 1.5 inches of rain, leading to reports of nuisance flooding. Accompanying the precipitation, strong winds gusted over 40 mph in mountainous areas, amplifying the storm's impact before it subsided early on December 28. ▪ 12/31/2022: At the close of December, a strong upper trough carrying tropical moisture swept through California, culminating in significant rainfall and flooding on the 31st, with many areas experiencing road closures. High winds battered the region, particularly the West Side Hills and Tehachapi Mountains, where gusts surpassed 60 mph, while lower Sierra Nevada elevations and adjacent foothills received 2 to 7 inches of rain. The intense precipitation added substantially to the existing snowpack, with high-elevation areas recording up to 30 inches of new snow, exacerbating the already heightened winter conditions.
▪ 1/05/2023: In early January, an atmospheric river brought significant rainfall and snow, with 18 to 30 inches of snow above 8000 feet in the Sierra Nevada and extensive flooding in the San Joaquin Valley. The Tehachapi Mountains saw powerful wind gusts over 60 mph, causing damage and leading to numerous weather advisories. These events disrupted infrastructure due to the combined impact of heavy precipitation and strong winds.
▪ 1/09/2023: A strong low-pressure system traversed central California on January 9 and 10, delivering 3 to 6 inches of rain in the Sierra Nevada and causing widespread flooding, with over 150 incidents reported. High snow levels resulted in significant runoff, while strong downslope winds caused power outages and damage; evacuations and road closures were necessary, including the inundation of Planada. The storm subsided by January 11, but the aftermath of flooding and wind damage persisted, prompting extensive emergency responses. ▪ 1/14/2023: The system that swept through central California on January 14 delivered heavy rain and snow, with the Sierra Nevada receiving 2 to 4 inches of liquid precipitation and the foothills getting 1.5 to 3 inches. Snowfall accumulated 1.5 to 3 feet above 6000 feet elevation, with snow levels dropping to 4500 feet by evening. Flooding became the primary concern as the heavy rains fell on already saturated soils, exacerbating runoff from previous storms. ▪ 1/16/2023: A subsequent storm on January 15-16 brought less precipitation but more wind damage to Central California, with gusts over 60 mph in the Tehachapi Mountains and West Side Hills causing power outages and tree falls. The San Joaquin Valley and Sierra foothills experienced wind gusts exceeding 40 mph, toppling power infrastructure, and blocking roads. The storm's effects persisted until January 17, with gradual wind reduction but persistent rainfall due to the already saturated ground from prior storms.
▪ 2/24/2023: A potent low-pressure system moved down the California coast on February 24-25, bringing heavy precipitation and causing snow levels to drop dramatically, leading to significant snowfall and road closures in the mountains. The Sierra Nevada and adjacent areas received 1.5 to

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3 inches of rain, while the snowfall at higher elevations ranged between 2 to 4 feet, resulting in extensive road closures. As the system passed, it caused flooding in the San Joaquin Valley and lower foothills, with the weather clearing as the low moved out of the area by the morning of February 26.
▪ 2/27/2023: Another cold upper trough moved across central California on February 27 and 28 which resulted in another period of widespread precipitation across the area. The snow level was between 3000 and 4000 feet or much of this event which resulted in heavy snowfall for the Sierra Nevada where several SNOTELs picked up an estimated 2 to 3 feet of new snowfall. Below the snow line, much of the San Joaquin Valley picked up between a quarter to a half inch of additional rainfall over already saturated soil while the Sierra foothills picked up between a half inch and an inch of combined liquid precipitation. Several roads in the mountains remained closed because of the continued snowfall across the area. The precipitation ended by the morning of March 1 as a colder and drier airmass pushed into central California.
▪ 3/10/2023: A deep moisture surge from the Pacific led to 4-8 inches of rain in the Sierra Nevada and significant flooding across the San Joaquin Valley and nearby foothills on March 9 and 10, exacerbated by high snow levels and saturated ground. Flash flood emergencies were declared in Tulare and Kern counties as runoff from the mountains threatened communities. Evacuations were enacted, and roads were shut down due to the extensive flooding and damage necessitating substantial repairs.
▪ 3/11/2023: Following the departure of the warm and moist storm which produced widespread flooding across the area on March 9 and 10, another moist system moved through central California on March 11 and 12. While precipitation amounts were generally much lower with this system with most of the Sierra Nevada picking up between 1 and 2 inches of liquid precipitation and adjacent foothills picking up between a half inch and an inch of rainfall, the cooler unstable airmass on the back side of this system produced afternoon and evening thunderstorms across the lower elevations resulting in widespread flooding and wind damage across the San Joaquin Valley. ▪ 4/17/2023: Increased releases at Pine Flat dam due to heavy snow melt runoff resulted in flooding near the Kings River downstream of Pine Flat Dam. The increased runoff produced flooding at Lindy's Landing campground near Reedley, and the Kings River Golf and Country Club near Kingsburg.
▪ 5/09/2023: An upper trough moved across Central California on May 9. This system provided for enough instability for scattered thunderstorms to break out along the West Side Hills and the Sierra Nevada during the afternoon. One thunderstorm produced heavy rainfall near Coalinga which resulted in a brief closure of SR 198 just to the southwest of Coalinga as rocks and mud impacted the highway.
▪ 6/10/2023: A strong closed upper low-pressure system approached the southern California coast on June 10. This system pushed a surge of moisture northward into central California and provided for enough instability for showers thunderstorms to develop across the area during the afternoon.

While precipitation was generally light with most locations receiving less than a tenth of an inch, a few thunderstorms produced locally heavy rainfall. One thunderstorm produced localized roadway flooding in western Fresno County.

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Table 30. Fresno County Flood Previous Occurrences
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Eastern Fresno
County
December
1955 0 0 0 0 0
Interstate 5
West Fresno
County
January 1995 0 ~14 M ~8.6 M 7 0
Interstate 5
Kings River 1997 0 0 0 0 0
Fresno County 2/01/1998 –
June 1998 0 458,000 17 M 0 0
City of Parlier 4/28/2005 0 700,000 0 0 0
Fresno / Clovis 12/19/2005 –
1/01/2006 0 1.4 M 0 0 0
Fresno County 4/05/2006 0 0 0 0 0
Huntington
Lake July 2006 0 0 0 0 0
Northwest
Fresno 10/29/2007 0 500,000 0 0 0
Fresno
Metropolitan
Area
12/18/2007 0 175,000 0 0 0
Fresno / Visalia
/ Bakersfield 12/29/2010 0 125,000 0 0 0
Fresno County 11/30/2011 0 0 0 0 0
Raisin City 1/07/2017 0 0 0 0 0
Panoche
Junction 1/20/2017 0 0 0 0 0
Herndon 2/03/2017 0 0 0 0 0
Meadow Lakes 2/07/2017 0 100,000 0 0 0
Squaw Valley 2/20/2017 0 0 0 0 0
Belmont Ave. 6/19/2017 0 0 0 0 0
Lakeshore 3/21/2018 0 0 0 0 0
Ora 10/03/2018 0 0 0 0 0
Chandler 11/21/2018 0 0 0 0 0
Oxalis 11/16/2018 0 0 0 0 0
Parlier 2/02/2019 0 0 0 0 0
Huron 2/14/2019 0 0 0 0 0
Friant 3/02/2019 0 0 0 0 0
Selma 5/26/2019 0 0 0 0 0
Sanger 5/29/2019 0 0 0 0 0
Piedra 6/01/2019 0 0 0 0 0
Melvin 12/08/2019 0 0 0 0 0
Malaga 12/22/2019 0 0 0 0 0
Lacjac 3/25/2020 0 0 0 0 0

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Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Oro Loma 4/17/2020 0 0 0 0 0
Riverdale 5/18/2020 0 0 0 0 0
Oro Loma 1/28/2021 0 0 0 0 0
Old Fig Garden 10/25/2021 0 0 0 0 0
Clarks Corner 12/14/2021 0 0 0 0 0
Glorietta 12/23/2021 0 0 0 0 0
Clovis 12/10/2022 0 0 0 0 0
Big Creek 12/27/2022 0 0 0 0 0
Ockenden 12/31/2022 0 0 0 0 0
Coalinga 1/05/2023 0 0 0 0 0
Pine Ridge 1/09/2023 0 500,000 0 0 0
Herndon 1/14/2023 0 0 0 0 0
Alder Springs 1/16/2023 0 0 0 0 0
Three Forks 2/24/2023 0 1,000 0 0 0
Squaw Valley 2/27/2023 0 0 0 0 0
Hammond 3/01/2023 0 9,000 0 0 0
Squaw Valley 3/10/2023 0 0 0 0 0
Reedley 3/11/2023 0 0 0 0 0
Sanger 4/17/2023 0 0 0 0 0
Sanger 5/01/2023 0 0 0 2 0
Coalinga 5/09/2023 0 0 0 0 0
Coalinga 6/10/2023 0 0 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

LOCALIZED FLOODING
In addition to the major historical flood events described above, as previously described, the Fresno County planning area remains at risk of annual localized flooding.

LEVEE FAILURE PAST OCCURRENCE
• February 18, 2017: Dry weather debilitated a levee located in the Fresno Slough, where the San Joaquin River and Kings River meet. The levee experienced several small breaks for a few days, posing a danger to nearly 80 homes in the vicinity, forcing hundreds of people to evacuate. Repairs and monitoring led by Fresno County Public Works and Emergency Management stopped the levee breach.
• June 22, 2017: A 15-foot-wide breach opened along the Kings River, leading to mandatory evacuations. The Kings River began to flood 25 miles north of Fresno. The levee failure occurred after a prolonged period of warmer-than-average temperatures led to a surge in snowmelt from the nearby Sierra Nevada Mountains.

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• March 27, 2023: A levee broke near Floral Avenue and Highway 145 south of Kerman Monday morning. According to a news report, no structures were threatened by the water and the land is all for agricultural use. 20

LIKELIHOOD OF FUTURE OCCURRENCES
Likely - Based on historical data, it is likely that flood events will occur in the future.

CLIMATE CHANGE CONSIDERATIONS
Overall, Increasing, and warmer rainfall and less snow from major storms will result in decreasing and shifting snowmelt to earlier in the season and most snow melting by early spring are expected.

Freezing elevations in the San Joaquin River will increase and snow accumulation decreasing.

Heavy precipitation events that lead to flooding occur at the short-term time scales of weather, rather than the multi-year time scales of climate that most climate models examine. However, extreme events are, by their very nature, uncommon. New research suggests that by the end of the century, due to climate change impacts, storms will generate 200 to 400 percent more water flow in the Sierra Nevada mountains due to increased precipitation in the form of rain and not snow. The study suggests that some locations could get over 100 inches of water in a month period plus the snow accumulation in higher elevations. This would have major impacts in Central Valley 21According to the Central Valley Flood Protection Plan 2022, by 2072 climate change is predicated to increase peak flood flows up to five times in the Central Valley compared to past recorded events. The Central Valley already has one of the highest flood risks in the United States and is anticipated to increase, devastating properties, communities, and the agricultural industry. While the climate is warming, extreme weather events such as atmospheric rivers, the primary source of major flooding, will become more intense as they become wetter, longer, and wider, increasing their potential to cause catastrophic events.

Within the State of California, including the San Joaquin Valley, projections show that rainstorms during the wet winter months will likely become more extreme, with more water falling in shorter periods of time and potentially creating flood. Increased rainfall causes floods when rain falls on top of snow in the mountains. The resulting rapid snowmelt has historically been a reason for major floods. 22 Globally, precipitation extremes and their hydrological impacts (e.g., the magnitude of 100-year floods) are expected to get larger because in most places, higher temperatures will result in increased atmospheric water vapor available to form precipitation. The 100-year flood of today might become a more frequent event in the future (i.e., a 50-year event), meaning that current design levels and regulatory practices might be less adequate in the future.

20 https://kmph.com/news/local/levee-breaks-monday-morning-along-hwy-145-in-eastern-fresno-county-san-joaquin- helm-kerman
21 https://www.yourcentralvalley.com/digital-exclusive/fresno-would-be-underwater-warns-ucla-catastrophic-flood-study/ 22 https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Flood-Management/Flood-Planning-and- Studies/Central-Valley-Flood-Protection-Plan/Files/CVFPP-Updates/2022/a0000- CVFPP_U22_layout_Highlights_vFINAL_online.pdf

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HUMAN HEALTH HAZARDS: EPIDEMIC/PANDEMIC

HAZARD/PROBLEM DESCRIPTION
Epidemics occur when an infectious disease spreads beyond a local population, lasting longer and reaching people in a wider geographical area. When that disease reaches global proportions, it is considered a pandemic. Pandemics are large-scale outbreaks of infectious disease that can greatly increase morbidity and mortality over a wide geographic area and cause significant economic, social, and political disruption. The most recently pandemic, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) as known as COVID-19, resulted in an unprecedented global health crisis which significantly impacted all sectors and communities. Several factors determine whether an outbreak will explode into an epidemic or pandemic: the ease with which a microbe moves from person-to-person and the behavior of individuals and societies.

A pandemic flu occurs when a new influenza virus emerges for which people have little or no immunity, and for which there is no vaccine. This disease spreads easily person-to-person, causes serious illness, and can sweep across the country and around the world in a very short time. In continuation to the efforts made during the COVID-19 pandemic, the U.S. Centers for Disease Control and Prevention (CDC) has been working closely with other countries and the World Health Organization to strengthen systems to detect outbreaks of influenza that might cause a pandemic and to assist with future pandemic planning and preparation.

Pandemics can last for a long period of time, encompassing a several years, compared to other natural hazards. The recent COVID-19 pandemic lasted for 3 years, from January 2020-May 2023, with the ending of the emergency proclamation. While pandemics may end, the virus still circulates. For example, the Spanish Flu that caused a pandemic in early 1900s is now the seasonal flu. The COVID- 19 and its variants are still persistent globally and new variations continue to evolve. The Pandemic Intervals Framework (PIF) describes the progression of an influenza pandemic using six intervals described in the table below.

AVIAN INFLUENZA
Due to the possibility that bird flu viruses could mutate and gain the ability to spread easily between people, avian influenza poses a significant pandemic threat to birds and humans. The U.S. Centers for Disease Control and Prevention (CDC) has been monitoring for illness among humans exposed to infected birds. Historical HPAI outbreaks have occurred all around the world since 1878 when it was first discovered in Northern Italy. HPAI continued to spread throughout the 20th century and in 1996 a new strain of HPAI subtype H5N1 was introduced to poultry in the Guangdong providence of China resulting a mortality of greater than 40 percent in aquatic birds. In 2003, two humans were diagnosed with HPAI H5N1 after returning from China and human cases continued to be reported resulting in hundreds of deaths. However, bird flu transmission from human-to-human is very rare and when it has occurred it has only spread to a few people. While the transmission from human to human is rare, the pandemic risk associated with HPAI is high due to the rapid mutations and increased risk of HPAI spillover from poultry to humans is a cause for significant concern. Recently, HPAI outbreaks have occurred in the United States in 2022 and 2023. While no human-to-human transmission has occurred with avian influenza that is currently circulating in the U.S., the CDC is closely monitoring to indicate increased risk of infection for the general public. 23

23 https://asm.org/articles/2022/july/avian-influenza-past,-present,-future

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Table 31. CDC Pandemic Intervals Framework (PIF)
Interval
Number
Interval Name Description
1 Investigation Investigation of cases of a novel influenza A virus infection in humans.

Public health actions focus on targeted monitoring and investigation. 2 Recognition
Recognition of increased potential for ongoing transmission of a novel influenza A virus. public health actions focus on control of the outbreak, including treatment of sick persons.
3 Initiation
Initiation of a pandemic wave. A pandemic occurs when people are easily infected with a novel influenza A virus that has the ability to spread in a sustained manner from person-to-person
4 Acceleration
The acceleration (or “speeding up”) is the upward epidemiological curve as the new virus infects susceptible people. Public health actions at this time may focus on the use of appropriate non-pharmaceutical interventions in the community (e.g. school and child-care facility closures, social distancing), as well the use of medications (e.g. antivirals) and vaccines, if available. These actions combined can reduce the spread of the disease and prevent illness or death.
5 Deceleration
The deceleration (or “slowing down”) happens when pandemic influenza cases consistently decrease in the United States. Public health actions include continued vaccination, monitoring of pandemic influenza A virus circulation and illness, and reducing the use of non-pharmaceutical interventions in the community (e.g. school closures).
6 Preparation
When pandemic influenza has subsided, public health actions include continued monitoring of pandemic influenza A virus activity and preparing for potential additional waves of infection. It is possible that a 2nd pandemic wave could have higher severity than the initial wave.

Source: CDC

It has long been recognized that human influenza viruses and the like occur in temperate climate during the winter season and have low activity during the summer months. The onset of pandemics is likely to occur during the winter months as the weather becomes colder and more and more people congregate inside with poor indoor air quality. Additionally, ongoing pandemics are likely to increase in activity around the winter months for similar reasons as experienced with the COVID-19 pandemic.

Pandemics can occur relatively quickly, usually over several months, but comparatively to natural hazards, it can be a long time. However, the first deaths from a pandemic will not be known until perhaps weeks after infection, delaying response from public health and government leaders. The spread of disease can occur rather quickly due to international transportation such as air travel. The World Health Organization is responsible for closely monitoring infectious disease on a global scale, its activity, and spread. There are different thresholds that define the spread of disease by scale described in Table 32. Infectious Disease Severity and Scale.

Table 32. Infectious Disease Severity and Scale
Term Definition
Outbreak An outbreak is an occurrence of cases of disease that is more than expected, or cases clustered by time, space, or common behaviors.

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Term Definition
Epidemic Epidemic is described as an unexpected increase in the number of disease cases in a specific geographical area.

Endemic A disease outbreak is endemic when it is consistently present but limited to a particular region. This makes the disease spread and rates predictable.

Pandemic An epidemic that has spread over several countries or continents and affects many people.

Source: WHO

Pandemics in nature are destructive, causing major disruptions to the economy, the public health and health care system, and population health. Pandemic impacts are not felt equally across populations, certain populations including people of color, children, the elderly, individuals with disabilities, and individuals with chronic health conditions. Previously, the magnitude of a pandemic was measured by the Pandemic Severity Index (PSI) which has been phased out by the Pandemic Severity Assessment Framework (PFAS). There are two main factors that can be used to determine the impact of a pandemic and guide decisions.

1. Clinical Severity: how serious is the illness associated with the infection.

2. Transmissibility: how easily the pandemic virus spreads from person-to-person.

Guidance from the CDC states that health officials should perform at least two assessments when using the PSAF. The first assessment is appropriately called an “initial assessment,” and health officials should complete this assessment early on during a pandemic. At this point, activity may be detected in pockets or certain communities across the country so information and understanding about the pandemic virus may be limited. The initial assessment is intended to help health officials develop a preliminary understanding of the potential impact of the pandemic. Once quality data becomes available, health officials can perform a “refined assessment” which provides a more detailed and accurate picture of pandemic impact, including assessments of the impact by age group. Table 33.

CDC Pandemic Severity Assessment Framework (PFAS) describes scaled measures of transmissibility and clinical severity for refined assessments of pandemic influenza effects.

Table 33. CDC Pandemic Severity Assessment Framework (PFAS) Parameter
No. and
Description24
Scale
1 2 3 4 5 6 7
Transmissibility
Symptomatic
attack rate,
community, %
<10 11-15 16-20 21-24 >25 - -

24 24 Reed, Carrie, Matthew Biggerstaff, Lyn Finelli, Lisa M. Koonin, Denise Beauvais, Amra Uzicanin, Andrew Plummer, Joe Bresee, Stephen C. Redd, and Daniel B. Jernigan. “Novel Framework for Assessing Epidemiologic Effects of Influenza Epidemics and Pandemics - Volume 19, Number 1—January 2013 - Emerging Infectious Diseases Journal - CDC.” Accessed August 28, 2023. https://doi.org/10.3201/eid1901.120124.

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Parameter
No. and
Description24
Scale
1 2 3 4 5 6 7
Symptomatic
attack rate,
school, %
<20 21-25 26-30 31-35 >36 - -
Symptomatic
attack rate,
workplace, %
<10 11-15 16-20 21-24 >25 - -
Household
secondary attack
rate,
symptomatic, %
<5 6-10 11-15 16-20 >21 - -
R0: basic
reproductive
number
<1.1 1.2-1.3 1.4-1.5 1.6-1.7 >1.8 - -
Peak %
outpatient visits
for influenza-like
illness
1-3 1-3 1-3 1-3 1-3 - -
Clinical Severity
Case-fatality
ratio, % <0.02 0.02-0.05 0.05-0.1 0.1-0.25 0.25-0.5 0.5-1 >1 Case-
hospitalization
ratio, %
<0.5 0.5-0.8 0.8-1.5 1.5-3 3-5 5-7 >7
Ratio, deaths:
hospitalization,
%
<3 4-6 7-9 10-12 13-15 16-18 >18
Source: CDC

Federal, state, and local public health agencies provide instructions to all organizations and individuals based on the severity of a pandemic and the infectious diseases’ transmission methods. The worst- case scenario for the City of Carson would be a disease with high clinical severity (7) and high transmissibility (5) in the CDC’s PSAF.

EXTENT
Large - An especially severe influenza pandemic could lead to high levels of illness, death, social disruption, and economic loss. Impacts could range from school and business closings to the interruption of basic services such as public transportation, health care, and the delivery of food and essential medicines. Since the hazard can affect 50-100 percent of the planning area it was given an extensive geographic extent rating.

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PAST OCCURRENCES
Since 1918, there have been six epidemics or pandemics over the span of 105 years. Using the PSAF developed by the CDC, each prior epidemic or pandemic has been measured by their transmissibility and clinical severity score shown in Figure 22. Previous Pandemics and Epidemics using PSAF and text below.

Source: CDC

▪ 1918-19 Spanish flu (H1N1): This flu is estimated to have sickened 20-40 percent of the world’s population. Over 20 million people lost their lives. Between September 1918 and April 1919, 500,000 Americans died. The flu spread rapidly; many died within a few days of infection, others from secondary complications. The attack rate and mortality were highest among adults 20-50 years old; the reasons for this are uncertain. By late September 1918, over 35,000 people throughout California had contracted influenza. According to state officials, influenza was most prevalent in the southern part of California, but the death toll was high across the state. ▪ 1957-58 Asian flu (H2N2): This virus was quickly identified due to advances in technology, and a vaccine was produced. Infection rates were highest among school children, young adults, and pregnant women. The elderly had the highest rates of death. A second wave developed in 1958. In

Figure 25. Previous Pandemics and Epidemics using PSAF

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total, there were about 70,000 deaths in the United States. Worldwide deaths were estimated between 1 and 2 million.
▪ 1968-69 Hong Kong flu (H3N2): This strain caused approximately 34,000 deaths in the United States and more than 700,000 deaths worldwide. It was first detected in Hong Kong in early 1968 and spread to the United States later that year. Those over age 65 were most likely to die. This virus returned in 1970 and 1972 and still circulates today. ▪ 2009 H1N1 flu: This new H1N1 virus was first detected in the United States and has genes not previously identified in people or animals. From April 2009 – April 2010, the CDC estimates about

60.8 million cases, 274,304 hospitalizations and 12,469 deaths in the United States. About 151,700 to 575,400 people worldwide are estimated to have died from the flu, and most deaths occurred in people under age 65. This is because younger people were less likely to have had prior exposure to a similar H1N1 virus, unlike older generations.
▪ 2019 COVID-19 Pandemic: The coronavirus disease 2019 (COVID-19) pandemic is a global outbreak of coronavirus – an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The pandemic caused millions of deaths, hospitalizations, and infections across the United States and even more globally. Cases of novel coronavirus (nCoV) were first detected in China in December 2019, with the virus spreading rapidly to other countries across the world. This led WHO to declare a Public Health Emergency of International Concern (PHEIC) on January 30, 2020, and to characterize the outbreak as a pandemic on 11 March 2020.

On March 13, 2020, the President declared the ongoing Coronavirus Disease 2019 (COVID-19) pandemic of sufficient severity and magnitude to warrant an emergency declaration for all states, tribes, territories, and the District of Columbia pursuant to section 501 (b) of the Robert T. Stafford Disaster Relief and Emergency Assistance Act, 42 U.S.C. 5121-5207 (the “Stafford Act”). The emergency declaration lasted until May 2023.

THE COVID-19 PANDEMIC
The most recent and notable pandemic that has occurred is the COVID-19 pandemic which has been the deadliest pandemic in history. On March 11, 2020, The World Health Organization (WHO) officially declaration the Coronavirus disease 2019 (COVID-19) outbreak a pandemic due to the global spread and the severity of the disease. COVID-19 is a respiratory illness that can spread from person to person and is highly contagious. Soon after, stay-at-home orders were issued across the country to keep people safe against contracting the virus, then COVID-19 testing sites opened and were a critical tool in informing individuals if they had COVID-19 or not in order to minimize and reduce the spread of the virus.

December 2020 marked a historical moment in the pandemic as COVID-19 vaccines were developed to be distributed under emergency use to protect people against adverse health effects from COVID-19, especially for older adults, who were passing at a higher rate than other age groups. The pandemic response efforts expanded into vaccine distribution and administration. In the beginning of the vaccine response, due to high demand and low supply, vaccine was prioritized for older adults, healthcare workers and other groups that were identified as high risk by state and local health departments.

Since 2020, the virus has mutated, and different variants have emerged throughout the three years since the beginning of the pandemic. Some symptoms of COVID-19 include cough, difficulty breathing, fever, fatigue, muscle pain, and loss of taste or smell. Severe cases resulted in hospitalizations, death, or chronic conditions from long-COVID. Individuals at high risk of adverse health outcomes included the elderly, people with underlying medical conditions and those who are immunocompromised.

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The pandemic highlighted existing health disparities among communities resulting in disproportionate impacts in COVID-19 case rates, hospitalizations, and deaths. Those without health insurance and access to healthcare, people of color, people with disabilities, and low socioeconomic status bared the burden of COVID-19 from physical impacts in contracting the virus to financial burdens such as unemployment. 25
Specifically in the state of California, people of color and low-income communities were disproportionately impacted by COVID-19 as case, hospitalizations, and deaths rates were significantly higher. According to the California’s COVID-19 disparity data, death rate for Latino people is 8 percent higher than the rate for all Californians, case rate for Pacific Islander people is 82 percent higher, death rate for black people is 19 percent higher, and case rate for communities’ median income less than $40,000 is 14 percent higher. 26Due to the COVID-19 emergency declaration ending in May of 2023, there has been a sharp decrease in COVID-19 reporting and surveillance, especially at the local level.

As of May 2023, there have been 12,251,820 COVID-19 cases and 111,554 deaths since the start of the pandemic in California State. Within Fresno County, as of May 2023, there have been 333,200 COVID-19 cases and 2,909 deaths.

LIKELIHOOD OF FUTURE OCCURRENCES
Possible— Due to the recent COVID-19 pandemic, there have been studies trying to understand and predict how likely a similar pandemic is to occur in the future and we can better prepare for the next one. According to one study, the probability of a pandemic similar to COVID-19 is about a two-percent chance of occurring in any year. Based on the increasing rate at which novel pathogens such as SARS- CoV-2 have broken loose in human populations in the past 50 years, the study estimates that the probability of novel disease outbreaks will likely grow three-fold in the next few decades.

Historical modeling suggests that the frequency and severity of epidemics caused by zoonotic disease are increasing, driven by human activities and their impact on the environment. They estimate that the probability of a future zoonotic event resulting in a pandemic of COVID-19 magnitude or larger is between 2.5-3.3 percent annually. In other words, there is a 22-28 percent chance that another outbreak on the magnitude of COVID-19 will occur within the next 10 years, and a 47-57 percent chance that it will occur within the next 25 years. It is likely for a future epidemic or pandemic occurring and impacting the planning area in a similar manner as the COVID-19 pandemic.

CLIMATE CHANGE CONSIDERATIONS
This is overwhelming evidence that climate change is fueling disease outbreaks and epidemics and that it is not a matter of if, but when. Climate change can influence the risk of disease outbreak through several ways both directly and indirectly. These include the slow rise in temperatures, changes in environmental conditions that increase the dispersal of disease vectors such as mosquitos, rodents, and ticks; and the sudden appearance of extreme events such as floods, which can contaminate drinking water sources and trigger the displacement of humans and animals, which can carry and transmit pathogens.

25 Inequity and the Disproportionate Impact of COVID-19 on Communities of Color in the United States: The Need for a Trauma-Informed Social Justice Response - PMC (nih.gov) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8243721/ 26 https://covid19.ca.gov/equity/

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Climate conditions can influence the spread of infectious diseases, and changes to these conditions can lead to new patterns. Temperature differences can affect where insect populations live and the diseases they may carry. Insects such as fleas, ticks, and mosquitoes can carry diseases like Lyme, West Nile, malaria, and Zika. Additionally, changes in climate can increase the likelihood of new viruses occurring or mutating in different animal species and infecting humans. Many countries across the world have experienced new outbreaks in infections varying from mosquito-borne dengue virus and chikungunya virus infection. In addition to the impacts from climate change, extreme climate events and disasters can increase the rise in epidemics. For example, a major flood event can cause the spread of infectious diseases such as cholera. 27

27 https://www.science.org/doi/10.1126/science.adk4500#:~:text=However%2C%20there%20is%20overwhelming%20evidenc e,diseases%2C%20both%20directly%20and%20indirectly.

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HUMAN HEALTH HAZARDS: WEST NILE VIRUS

HAZARD/PROBLEM DESCRIPTION
The impact to human health that wildlife, and more notably, insects, can have on an area can be substantial. Mosquitoes transmit the potentially deadly West Nile virus to livestock and humans alike.

West Nile virus first struck the western hemisphere in Queens, New York, in 1999 and killed four people. Since then, the disease has spread across the United States. The highest number of reported cases were in 2003 and 2012 from 1999-2022. Since 1999, there have been 56,575 cases, 25,777 hospitalizations, and 2,776 deaths. West Nile Virus cases from 1999 to 2022 are described in Figure

23. U.S. West Nile Reported Cases by Year.

Source: CDC

In assessing this hazard, the HMPC also discussed Zika virus, which is recently invasive, with the first reported cases in the U.S. occurring in Florida during the summer of 2016, and 5102 Zika cases reported across all 50 states by the end of 2016.

Most humans infected by the West Nile virus have no symptoms. A small proportion develop mild symptoms that include fever, headache, body aches, skin rash, and swollen lymph glands. Less than 1 percent of those infected develop more severe illnesses such as meningitis or encephalitis, symptoms of which include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. Of the few people who develop encephalitis, fewer than 1 out of 1,000 infected dies as a result. People over 50 and those with compromised immune systems are the most vulnerable to the virus. Those with Zika virus are highly unlikely to develop serious illness requiring a hospital visit, however Zika virus can cause severe brain defects in infants such as microcephaly along with other morbidity including miscarriage, stillbirth, and other types of birth defects.

Figure 26. U.S. West Nile Reported Cases by Year

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There is no specific treatment for Zika or West Nile virus infection, nor a vaccine to prevent the viruses.

Treatment of severe illness includes hospitalization, use of intravenous fluids and nutrition, respiratory support, prevention of secondary infections, and good nursing care. Medical care should be sought as soon as possible for people who have symptoms suggesting severe illness. People over 50 years of age appear to be at high risk for the severe aspects of the disease.

The West Nile virus is a concern in the Fresno County planning area in part because of the agricultural nature of the County and the large areas of standing water created through farming operations. Excess standing water provides a breeding area for mosquitoes. Also contributing to the mosquito population in the County are the beaver dams and ponds, which are large pools of standing water. The Zika virus is of minimal concern to the County given that there is no record of Zika virus being transmitted in or near Fresno County.

Within the Fresno County planning area, several mosquito abatement and control districts operate to prevent the spread of the virus through focused efforts on reducing the mosquito population and educating the public. Several types of preventive methods lower mosquito populations to levels that reduce chances for the spread of disease. The County also has an active surveillance program and maintains records for all identified cases of the virus.28

EXTENT
Large - An especially severe mosquito-borne illness outbreak could lead to high levels of illness, death, social disruption, and economic loss. Impacts could range from school and business closings to the interruption of basic services such as public transportation, health care, and the delivery of food and essential medicines. Since the hazard can affect 50-100 percent of the planning area it was given an extensive geographic extent rating.

PAST OCCURRENCES
The virus first appeared in California in 2002 with the identification of one human case. In 2003, three human cases occurred in California, and the virus was detected in six southern California counties. By 2004, the virus was in all 58 counties in California; 830 human infections were identified. Since 2003, there have been more than 7,500 human cases and over 300 deaths reported in California. Recently, the Fresno County Department of Public Health has confirmed its first human death this year caused by West Nile Virus in November 2023. 29 Table 34. California West Nile Cases by Year shows West Nile cases in humans, birds, mosquitos, horses, and sentinel flock.

Table 34. California West Nile Cases by Year
Year Humans Birds Mosquitos Horse Sentinel Flock

CA FC CA FC CA FC CA FC CA FC
2004 830 15 3,232 116 1,136 14 540 21 805 25
2005 935 68 3,046 97 1,242 71 456 33 1,053 85

28 https://www.fresnocountyca.gov/Departments/Public-Health/Community-Health/Communicable-Disease-Investigation- Program/Mosquito-Borne-Illness
29 https://abc30.com/west-nile-virus-death-fresno-county-mosquito-sickness/14003501/

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Year Humans Birds Mosquitos Horse Sentinel Flock

CA FC CA FC CA FC CA FC CA FC
2006 278 11 1,446 2 832 40 58 5 640 37
2007 380 17 1,395 114 1,007 61 28 1 510 46
2008 445 3 2569 44 2,003 53 32 1 585 24
2010 111 23 416 22 1,305 130 19 4 281 7
2011 158 9 688 15 2,087 123 15 5 391 0
2012 479 24 1,644 25 2,849 147 22 3 540 0
2013 379 7 1,251 12 2,528 66 23 N/A 458 0
2014 801 43 2,442 9 3,304 138 15 2 443 0
2015 782 8 1,349 3 3,329 108 19 N/A 449 0
2016 442 14 1,352 6 3,528 185 21 2 343 0
2017 87 1 264 3 2,545 136 21 1 155 0
2018 217 14 501 0 1,963 N/A 11 N/A 163 N/A
2019 225 51 226 10 3,288 N/A 15 N/A 139 N/A
2020 235 10 343 5 2,628 322 20 N/A 144 N/A
2021 129 14 210 0 2,263 219 13 2 90 N/A
2022 207 30 189 2 3,165 296 16 N/A 145 N/A
2023 397 22 855 1 4,512 232 31 2 186 N/A
Source: California West Nile Virus Web Site, www.westnile.ca.gov/ *As of January 25, 2024

West Nile virus activity in California (and Fresno County) for 2023 year to date is illustrated in Figure

24. California West Nile Cases by County.

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Source: WestNile.ca.gov

Figure 27. California West Nile Cases by County

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The Zika Virus is another well-known virus that, along with the West Nile Virus, is a mosquito-borne disease. These viruses are transmitted to humans through mosquito bites. Unlike the West Nile Virus, the Zika virus is primarily transmitted by Aedes mosquitoes while the West Nile Virus is transmitted by Culex mosquitoes. From 2015 to March 2024, there have been 761 total Zika Virus infections in the State of California. Table 35. Fresno County Zika Cases (2015-2024) shows the number of cases for Fresno County from 2015 to 2024.

Table 35. Fresno County Zika Cases (2015-2024)
County 2015-
2016 2017 2018 2019 2020 2021 2022 2023 2024
Fresno
County 7 1 0 0 0 0 0 0 0

LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Based on historical data, the Fresno County planning area has experienced 384 human cases of West Nile virus since 2004. This is an average of 19 cases per year. The agricultural nature of much of the planning area combined with the great potential for standing water to be present throughout the County puts the planning area at future risk of West Nile virus.

Likelihood of Zika virus transmission is very low due to several factors, including mosquito abundance, number of travels associated cases, population, and distance from the U.S.-Mexico border. Taking these factors into consideration, CDPH concludes that current conditions in Fresno County present a very low risk for local transmission. As a result, vulnerability to Zika virus is not considered further.

CLIMATE CHANGE CONSIDERATIONS
In the aftermath of the 2015 pandemic of Zika virus (ZIKV), concerns over links between climate change and emerging arboviruses have become more pressing. Milder weather in the current “cold” seasons and warmer weather in the summer could make the county a more suitable habitat for new mosquito species, increasing the potential for additional cases of some mosquito-borne diseases that are already established in the county. At the same time, increases in the precipitation associated with extreme events could increase the habitat suitable for supporting mosquitoes. Drawing definitive conclusions about public health risk changes associated with vector-borne illnesses as a result of climate change are complicated by the need to also account for any associated changes in human behavior that would accompany the associated impacts to seasonal and daily weather conditions. For example, increased temperatures could result in more time spent indoors during extreme heat days, which could potentially reduce exposure to disease carrying vectors. In 2023, the World Health Organization (WHO) warned that climate change is causing a surge in Mosquito-Borne diseases. WHO cited a study which finds the incidence of infection caused by mosquito-borne illnesses which thrive in tropical and subtropical climates, have grown dramatically in recent decades. While globally, Zika cases are declining from its peak in 2015, 2016, and 2017, down to about 30-40,000 reported cases every year which occur mostly in the United States, Zika is still circulating and a threat as our climate changes. 30

30 https://www.voanews.com/a/who-warns-climate-change-causing-surge-in-mosquito-borne-diseases/7043700.html

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LANDSLIDE

HAZARD/PROBLEM DESCRIPTION
Landslides refer to a wide variety of processes that result in the perceptible downward and outward movement of soil, rock, and vegetation under gravitational influence. Common names for landslide types include slump, rockslide, debris slide, lateral spreading, debris avalanche, earth flow, and soil creep. Landslides may be triggered by both natural and human-induced changes in the environment that result in slope instability.

The susceptibility of an area to landslides depends on many variables, including steepness of slope, type of slope material, structure and physical properties of materials, water content, amount of vegetation, and proximity to areas undergoing rapid erosion or changes caused by human activities.

These activities include mining, construction, and changes to surface drainage areas.

Landslides often accompany other natural hazard events, such as floods, wildfires, or earthquakes.

Landslides can occur slowly or very suddenly and can damage and destroy structures, roads, utilities, and forested areas and cause injuries and death.

Landslides are often triggered by precipitation and as a result are sensitive to local climate conditions.

Due to climate change, precipitation patterns worldwide and therefore will likely have a strong influence on landslide activity in the next couple of decades. A study found that during 2015 to 2020 that landslides in both the wet regions in northwestern California and dry regions in southern California moved faster than average during wet years and slower than average during dry years. 31The warning time for hazards such as landslides and debris flow are often very short and may occur very quickly.

Identifying the area in which these events are likely to occur can assist with hazard preparedness when triggering types of events like heavy rainfall occurs. However, in some cases, landslides can occur very slowly, even extremely slowly and building on these landscapes may remain in use for hundreds of years with only minimal damage and repair costs. 32
The severity of a landslide or mudflow depends on many factors including local bedrock, soil conditions, moisture content, slope, and vegetation. Landslide velocities vary over ten orders of magnitude from extremely slow (a few millimeters a year) to extremely rapid (more than 5 millimeters a second), shown in Table 36. Landslide Velocity Class. Many human activities can make the earth’s materials less stable, therefore increasing the chance of ground failure. Human activities contribute to soil instability through grading of steep sloped or overloading them with artificial fill, by extensive irrigation, construction of impermeable surface, excessive groundwater, withdrawal, and removal of stabilizing vegetation. Some of the natural non-seismic causes of ground instability include heavy rainfall and poor-quality natural materials.

31 Handwerger, Alexander L., et al. “Landslide sensitivity and response to precipitation changes in wet and dry climates.” Geophysical Research Letters, vol. 49, no. 13, 2022, https://doi.org/10.1029/2022gl099499. 32 Social and environmental impacts of landslides | Innovative Infrastructure Solutions (springer.com) https://link.springer.com/article/10.1007/s41062-018-0175-y

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Table 36. Landslide Velocity Class
Velocity Class Description Velocity (mm/s) Typical
Velocity
Response
7 Extremely Rapid 5X10^3 5 m/s N/A
6 Very Rapid 5X10^1 3 m/min N/A
5 Rapid 5X10^-1 1.8 m/h Evacuation
4 Moderate 5X10^-3 13 m/month Evacuation
3 Slow 5X10^-5 1.6 m/year Maintenance
2 Very 5X10^-7 16 mm/year Maintenance
1 Extremely Slow N/A
Source: WP/WLI 1995 and Cruden and Varnes 1996
EXTENT
The Fresno County General Plan Background Report describes areas in Fresno County that are particularly prone to landslides. Landslide hazard areas include foothill and mountain areas where fractured and steep slopes are present (i.e., the Sierra Nevada), areas where less consolidated or weathered soils overlie bedrock (e.g., the Coast Range), and areas where inadequate ground cover accelerates erosion (e.g., along the San Joaquin River). According to the background report, areas where steep slopes are present are not generally heavily populated and most are in federal or state lands. The report further identified State Route 168 in eastern Fresno County and State Route 198 in western Fresno County as areas that could be affected by landslides caused by earthquakes or heavy rains. It also concludes that there is no risk of large landslides in the valley area of the County due to its relatively flat topography. However, there is the potential for small slides and slumping along the steep banks of rivers and creeks.

Figure 25. Fresno County Landslide Susceptibility is a landslide hazard map from the background report. It indicates that the central and eastern portions of Fresno County are at low risk for landslides and the far west side of the County along the Coast Range is at moderate risk for landslides.

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Source: California Department of Conservation, Landslide Inventory (Beta) Map Viewer

Figure 28. Fresno County Landslide Susceptibility

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PAST OCCURRENCES
Landslides occur in every state and can occur in any area composed of very weak or fractured materials resting on a steep slope can and will likely experience landslides. Areas vulnerable to landslides include the following: 33

Areas more prone to landslides
▪ On existing old landslides
▪ On or at the base of slopes
▪ In or at the base of minor drainage hollows
▪ At the bae or top of an old fill slope
▪ At the base or top of a steep cut slope
▪ Burn area and canyon, hillside, mountain, and other steep areas are vulnerable ▪ Develop hillsides where leach field septic systems are used

Areas less prone to landslides
▪ On hard, non-jointed bedrock that has not moved in the past ▪ On relatively flat-lying areas away from sudden changes in slope angle ▪ At the top or along the nose of ridges, set back from the tops of slopes

There have been no disaster declarations associated with landslides in Fresno County. Notable landslides of record are included in Table 37. Notable Past Landslides Events and described below:

▪ 1995: Following a large storm event, a large landslide occurred on Los Gatos Road, a significant local access road west of Coalinga. State geologists determined that catastrophic failure was unlikely, but long-term road maintenance could be compromised due to undercutting of the slope by the creek below the road.
▪ 5/13/2019: An area of Huntington Lake Road in Fresno County was subject to an extended closure because of a landslide, a recurring issue in that region known as the "beaver slide." This incident is part of a history of similar geological disturbances affecting the area. ▪ 12/30/2022 - 1/10/2023: Fresno County experienced multiple landslide incidents due to rockslides and mudslides that impacted various roadways, including State Routes 168 and 180. The California Highway Patrol (CHP) reported significant obstructions from rockslides on SR-168, near lower vista and east of Prather, and mudslides at the junctions of SR180 with Silver Lane and Millwood Road.

These incidents caused extensive road blockages with mud, dirt, rocks, and even large boulders, necessitating road closures and emergency responses.
▪ March 2023: California Highway Patrol dealt with landslides that led to road obstructions on Auberry Road and SR-63, while a significant rockfall on Trimmer Road caused extensive

33 Landslide Basics | U.S. Geological Survey (usgs.gov) https://www.usgs.gov/programs/landslide-hazards/landslide-basics

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blockages. By mid-March, Caltrans had to close an 8-mile section of State Route 180 due to multiple slides impeding the road, demonstrating the ongoing geological instability in the region.

Table 37. Notable Past Landslides Events
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Los Gatos
Road 1995 N/A N/A N/A N/A N/A
Huntington
Lake Road 5/13/2019 N/A N/A N/A N/A N/A
SR-168 and
SR-180
12/30/2022 –
1/10/2023 N/A N/A N/A N/A N/A
Dunlap March 2023 N/A N/A N/A N/A N/A
Source: CA Department of Conservation

LIKELIHOOD OF FUTURE OCCURRENCES
Possible--Based on data provided by the HMPC, minor landslides have occurred in the past, probably over the last several hundred years, as evidenced both by past deposits exposed in erosion gullies and recent landslide events. With significant rainfall, additional failures are likely within the identified landslide hazard areas. Given the nature of localized problems identified within the County, minor landslides will likely continue to impact the area when heavy precipitation occurs, as they have in the past.

CLIMATE CHANGE CONSIDERATIONS
Climate change projections for more intense precipitation events have the potential to increase landslide incidence. In fact, during extended drought periods, soil loses its ability to absorb water and when rain occurs landslide risk increases. During period of prolonged water crisis, soils dry out and lose their drainage capacity. California experiences long prolonged drought periods which can increase the risk and incidence of landslides when major rain events do occur. Additionally, California’s drought has also helped fuel major wildfires in recent years, and post-wildfire slopes are especially susceptible to mudslides. Plants destroyed by wildfires weaken the roots and therefore reduce soil stability.

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SOIL HAZARD: EROSION

HAZARD/PROBLEM DESCRIPTION
Erosion is the general process whereby rocks and soils are broken down, removed by weathering, or fragmented and then deposited in other places by water or air. The rate of erosion depends on many variables, including the soil or rock texture and composition, soil permeability, slope, extent of vegetative cover, and precipitation amounts and patterns. Erosion increases with increasing slope and precipitation and with decreasing vegetative cover, which includes areas where protective vegetation has been removed by fire, construction, or cultivation. Significant erosion can cause degradation and loss of agricultural land, degradation of streams and other water habitats, and rapid silting of reservoirs.

EXTENT
The Fresno County General Plan Background Report identifies those areas with moderately high to high erosion potential. These include areas of certain soil types in the Sierra Nevada and the foothills that generally coincide with slopes that exceed 30 percent (see Figure 26. Fresno County Steep Slope Areas and Figure 27. Fresno County Erosion Soils). However, many of these identified areas are located within the boundaries of the Sierra National Forest, Sequoia National Forest, or Kings Canyon National Park, which limits their availability for intensive development.

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Source: USGS, National Map Viewer, ½ Arc Second DEM: CA Geoportal; CA-DFW; CalTrans; County of Fresno - GIS

Figure 29. Fresno County Steep Slope Areas

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Source: USDA National Resources Conservation Service, Soils Survey

Figure 30. Fresno County Erosion Soils

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Erosion within the valley area is generally not a large concern, with the exception of areas containing Rossi soil east of the Fresno Slough from approximately Mendota to Fish Slough near Helm. Severe erosion potential has also been identified along the San Joaquin River Bluff. Also, along the main bypass floodway of the Fresno Slough, widely spaced gullies in a trellis pattern have eroded the soils where subsiding floodwaters drain back into the deeper main flood channel.

In western Fresno County, most soil associated with the Kettleman series appears to be subject to moderate to severe sheet and gully erosion potential. These include areas located primarily west of Interstate 5 in the Coast Range foothills. Also, in the western portion of the County, Panoche and Panhill soils, which under natural conditions do not exhibit erosion potential, are susceptible to erosion as a result of human activity. These soils are located extensively throughout the western part of the County and are prevalent in areas on recent alluvial fans in the central part of the region.

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One of the main concerns associated with erosion is related to wildfire as a fire burns it destroys plant material. Plants such as shrubs, grasses, and trees provide roots that stabilize the soil. Fires destroy soil protection, leading to increased vulnerability to erosion, in addition to increased risk of flood hazard.

The amount of erosion after a burn is determined by the severity of the burn, the slope, soil type and condition of the watershed before the burn. Using information provided by Cal Fire, Figure 28. Fresno County Wildfire Priority Landscape - Post Wildfire Erosion Threat outlines the post fire erosion threat for Fresno County.

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Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS, CalFIRE – FRAP, California’s Forests and Rangelands: 2010 Assessment

Figure 31. Fresno County Wildfire Priority Landscape - Post Wildfire Erosion Threat

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PAST OCCURRENCES
Historically, there have been no significant erosion events within the County. However, recently during the 2022-2023 season, the United States Forest Service warned visitors to the Sierra National Forest to avoid the Jose Basin Area. The Sierra National Forest officials reported roads in that area experiencing “significant erosion issues” caused primarily by local topography, erosive soils, and lingering effects of the Creek fire. 34 due to the increasing precipitation and flood events in the 2022 water year. Other areas in Fresno County experienced erosion as well during the same period of time.

LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Based on input from the HMPC, erosion does occur in the planning area. Given the nature of erosion problems identified within the County, erosion will continue to be an issue.

CLIMATE CHANGE CONSIDERATIONS
The primary climate related drivers affecting erosion, on both inland and coastal areas, are changes in temperature, water levels, precipitation, vegetation loss or changes, and weather. Climate is a major driver of erosion, however changes in land use and land cover, due to development and land management, can dramatically affect exposure of sediments to erosion. Erosion involves the breakdown, detachment, transport, and redistribution of soil particles by forces of water, wind, or gravity.

34 https://www.yourcentralvalley.com/news/local-news/stay-out-of-the-jose-basin-area-warns-sierra-national-forest/

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SOIL HAZARDS: EXPANSIVE SOILS

HAZARD/PROBLEM DESCRIPTION
Expansive (swelling) soils or soft bedrock are those that increase in volume as they get wet and shrink as they dry. They are known as shrink-swell, bentonite, expansive, or montmorillinitic soils. Swelling soils contain high percentages of certain kinds of clay particles that are capable of absorbing large quantities of water, expanding up to 10 percent or more as the clay becomes wet. The force of expansion is capable of exerting pressures of 20,000 pounds per square foot or greater on foundations, slabs, and other confining structures. Soils composed only of sand and gravel have no potential for volume changes. Soils are generally classified into three expansive soils classes with low, moderate, and high potential for volume changes:

▪ Low: This soils class includes sands and silts with relatively low amounts of clay minerals. Sandy clays may also have low expansion potential if the clay is kaolinite. Kaolinite is a common clay mineral.
▪ Moderate: This class includes silty clay and clay textured soils, if the clay is kaolinite, and includes heavy silts, light sandy clays, and silty clays with mixed clay minerals. ▪ High: This class includes clays and clay with mixed montmorillonite, a clay mineral which expands and contracts more than kaolinite.

Soils with relatively high clay content are considered expansive due to the capacity of clay minerals to take in water and expand to greater volumes. Highly expansive soils can cause structural damage to foundations and roads without proper structural engineering and require detailed geologic investigations and costlier grading applications. This makes highly expansive soil less suitable for development. Expansive soils can be found predominantly in the eastern part of the county in a northwest trending belt approximately parallel to the Friant-Kern Canal foothills in Kings Canyon National Park. Another expansive soil formation is located along the Fresno Slough from Madera County to Kings County 35
Damage can include severe structural damage, cracked driveways and sidewalks, heaving of roads and highway structures, and disruption of pipelines and other utilities. Destructive forces may be upward, horizontal, or both. Building in and on swelling soils can be done successfully, although more expensively, as long as appropriate construction design and mitigation measures are followed.

EXTENT
Small - According to the Fresno County General Plan Background Report, expansive soils within Fresno County generally occur in a northwest-trending belt approximately parallel to the Friant-Kern Canal foothills in Kings Canyon National Park in the Sierra Nevada, along the Fresno Slough from Madera County to Kings County, and roughly parallel to the San Luis Drain west of Tranquility and San Joaquin. Figure 29. Fresno County Expansive Soils from the Fresno County General Plan Background Report illustrates the area’s most susceptible to expansive soils.

35 Fresno County General Plan Background Report 2042

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Source: USDA – Natural Resources Conservation Service, Soils Survey, Fresno County – CA654, CA653 – August 2023 and CA740, CA792, CA760 & CA750 – September, 2023; Geoportal; CA-DFW; CalTrans; County of Fresno - GIS

Figure 32. Fresno County Expansive Soils

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PAST OCCURRENCES
Expansive soils are present in the County. However, due to the ability to successfully mitigate the hazard by adhering to sound design and construction practices, the HMPC was unable to find examples of historical expansive soil problems in the planning area.

LIKELIHOOD OF FUTURE OCCURRENCES
Possible—Based on the soil types found in Fresno County, the potential exists for expansive soil to be a future issue in the Fresno County planning area.

CLIMATE CHANGE CONSIDERATIONS
There is potential for more severe wet and dry cycles in future climate, which may have an effect on the frequency and intensity of expansive soils in Fresno County.

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SOIL HAZARDS: LAND SUBSIDENCE

HAZARD/PROBLEM DESCRIPTION
Land subsidence is defined as the vertical sinking of the land over manmade or natural underground voids. Subsidence, usually as a direct result of groundwater withdrawal or oil and gas withdrawal is common in several areas of California, including parts of the Central Valley. Weight, including surface developments such as roads, reservoirs, and buildings, and manmade vibrations from such activities as blasting and heavy truck or train traffic can accelerate the natural processes of subsidence. According to the California State Hazard Mitigation Plan 2023, by 1970, significant land subsidence had affected about half of the San Joaquin Valley, covering around 5,200 square miles, with more than 1 foot of subsidence observed. In specific localized regions, the ground had subsided by as much as 28 feet.

Subsidence can result in serious structural damage to buildings, roads, irrigation ditches, canals, streams, underground utilities, and pipelines. It can disrupt and alter the flow of surface or underground water. Improper use of land subject to subsidence can result in excessive economic losses: direct economic losses as well as indirect losses (e.g., increased taxes and decreased property values).

In California, the floor of the arid Central Valley is sinking due to groundwater pumping for agricultural and drinking water. According to a Stanford University study, land subsidence will likely continue for decades to centuries. Reducing or slowing the rate of land subsidence may be difficult at points due to periods of drought straining the water supply and system. 36 Other research suggests that groundwater depletion has been mainly propelled by the rapidly expanding estates of perennial, water-intensive crops such as almonds, citrus, and wine grapes. Additionally, non-drought years and years where California experiences extensive rainfall, may not even cause significant changes in land subsidence as this issue has been going on for one hundred years. Much of the groundwater depletion has occurred in the San Joaquin Valley and over the past two decades, the central valley has consumed nearly 36 million acre-feet of groundwater, translating to 11.7 trillion gallons of our most precious resource. 37 EXTENT
In the San Joaquin Valley, farmers rely heavily on surface-water diversions to meet irrigation water demand, but the recent droughts have induced substantial increases in groundwater pumping.

Unfortunately, this excessive water extraction from the unconsolidated deposits of the San Joaquin Valley causes land subsidence.

According to the Fresno County Background Report 2000, in some areas along the valley trough and in parts of western Fresno County, groundwater pumping has caused subsidence of the land surface.

Historically, this has occurred in areas where the groundwater basin has been subject to overdraft and long-term recharge is inadequate to maintain the water table elevation, leaving underground voids.

One study suggests that land subsidence is located in areas where the water demand for agriculture and the density of groundwater wells is the highest, whereas the rate of subsidence is strongly affected the amount of local and imported surface water and by groundwater resources. 38 There are two main subsidence bowls covering hundreds of square miles that grew wider and deeper between spring 2015 and fall 2016. The geographic extent and magnitude of subsidence in the San 36 https://news.stanford.edu/2022/06/02/will-californias-san-joaquin-valley-stop-sinking/ 37 https://fresnoalliance.com/central-valley-groundwater-sinking-faster-than-ever/ 38 https://www.sciencedirect.com/science/article/abs/pii/S0022169418309661

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Joaquin Valley is displayed below in Figure 30. Subsidence in the San Joaquin Valley, May 7, 2015 – September 10, 2016.

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Figure 33. Subsidence in the San Joaquin Valley, May 7, 2015 – September 10, 2016

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Geospatial analysis indicates that subsidence risk is concentrated in the western portion of the County.

While subsidence rates fall in the -4 to -1-inch range in the east, NASA’s survey technology shows subsidence reaching up to -16 inches in some pockets along the San Joaquin Valley corridor. Effected jurisdictions include Firebaugh, Mendota, Coalinga, and Huron.

Additionally, a significant area of concern is the Eastside Bypass, a system designed to carry flood flow off the San Joaquin River. Subsidence also intensified at a third area, near Tranquility, where the land surface has settled up to 20 inches in an area that extends seven miles. Specific areas where subsidence has been a problem include the Westlands Water District and the Pleasant Valley Water District. The increased subsidence rates have the potential to damage levees, bridges, and roads. Over time, subsidence can permanently reduce the underground aquifer’s water storage capacity.

PAST OCCURRENCES
Subsidence caused by groundwater pumping in the Central Valley has been a problem for decades.

Long-term subsidence already has destroyed thousands of public and private groundwater well casings in the San Joaquin Valley. NASA has been using radar satellite maps to document rates of subsidence in the San Joaquin Valley since 2014. The NASA analysis evaluated the Eastside Bypass system and found that the land surface had fallen between 16 inches and 20 inches since May 2015 – on top of several feet of subsidence measured between 2008 and 2012. Though recent technology and resources has brought this problem to light, the San Joaquin Valley subsidence due to groundwater extraction was observed as early as the 1920s. Extensive monitoring and research related to subsidence in the Valley was carried out in the 1950s through the 1970s because of concerns about subsidence-related damage to the state and federal water projects. Figure 31. Estimated Subsidence Between 1949 and 2005 below documents 50-years of estimated subsidence rates in the San Joaquin Valley. Similar to the estimates, the eastern portion of the County has historically seen the most subsidence, potentially reaching up to 30-feet in the north-east.

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Figure 34. Estimated Subsidence Between 1949 and 2005

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In 1963, DWR initiated construction of the State Water Project’s 444-mile-long California Aqueduct.

Subsidence mitigation was integrated into the project design; however, subsidence has required repairs such as the raising of canal linings, bridges, and water control structures on the Aqueduct and on the Central Valley Project’s Delta-Mendota and Friant-Kern canals. In recent years, a five-mile reach of the Eastside Bypass was raised in 2000 because of subsidence, and DWR estimates that it may cost in the range of $250 million to acquire flowage easements and levee improvements to restore the design capacity of the subsided area.

LIKELIHOOD OF FUTURE OCCURRENCES
Occasional—Land subsidence has been a constant issue affecting Fresno County for decades. This hazard is ongoing and is certain to continue in the future. However, legislation passed in 2014 requires local governments to regulate pumping and recharge to better manage groundwater supplies.

Groundwater-dependent regions are required to halt overdraft and bring basins into sustainable levels of pumping and recharge by the early 2040s. Though occurrence may be inevitable, the magnitude of subsidence rates is dependent on the mitigation actions and pumping regulations initiated by Fresno County. Excess groundwater pumping is more likely to occur during times of drought.

CLIMATE CHANGE CONSIDERATIONS
The most likely impact that climate change will have on land subsidence risk is the potential for extended and severe drought, which could likely result in more groundwater pumping and human- induced subsidence. During periods of drought, water levels may be drawn too low, which results in an irreversible compaction of aquitards. The water cannot recharge the layers, causing permanent subsidence and diminishment of groundwater storage capacity.

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SEVERE WEATHER: GENERAL
Severe weather is generally any destructive weather event, but usually occurs in the Fresno County planning area as localized thunderstorms that bring heavy rain, hail, lightning, and strong winds.

The National Oceanic and Atmospheric Administration’s National Center for Environmental Information (NCEI) has been tracking severe weather since 1950. The Storm Events Database contains data on the following: all weather events from 1993 to 2023. This database contains over 3,000 severe weather events that occurred in Fresno County between 1950 to 2023. Table 38. NCEI Hazard Event Reports for Fresno County (1950-2023) summarizes these events.

Table 38. NCEI Hazard Event Reports for Fresno County (1950-2023) Type # of Events Property Loss
($)
Crop Loss
($) Deaths Injuries
Dense Fog* 1,509 24,136,000 0 24 72
Flash Floods 48 87,000 0 0 0
Floods 420 583,281,000 124,190,000 12 8
Funnel Clouds 47 0 0 0 0
Hail 73 1,020,000 2,100,500 0 4
Heavy Rain 151 2,179,000 95,690,000 0 0
High Winds** 111 402,518,000 30,000 1 0
Lightning 38 1,770,000 300,000 2 3
Severe
Thunderstorms/Wind 73 4,224,500 43,085,000 2 15
Tornado** 35 6,480,050 26,000 0 3
Wildfires* 662 1,847,706,500 119,918,000 5 112
Source: National Center for Environmental Information Storm Events Database, www.ncdc.noaa.gov/stormevents/
*Hazards with wide extents have losses which reflect larger zones that extend beyond Fresno County **Source is NOAA Storm Events Database GIS data

The NCEI table above summarizes severe weather events that occurred in Fresno County. A few of the events resulted in state and federal disaster declarations. It is further interesting to note that different data sources capture different events during the same time period, and often different information specific to the same events. While the HMPC recognizes these inconsistencies, they see the value this data provides in depicting the County’s “big picture” hazard environment.

In the previous plan, all of Fresno County’s state and federal disaster declarations have been a result of natural hazards, mostly caused by severe weather. Since the 2018 update, state and federal declarations resulted from the COVID-19 pandemic, which has been the exception for the county regarding causes of state and federal declarations. For this plan, severe weather is broken down as follows:

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▪ Extreme Temperatures (Extreme Cold/Freeze and Extreme Heat) ▪ Fog
▪ Heavy Rain/Thunderstorm/Hail/Lightning/Wind
▪ Winter Storm
▪ Tornado

Due to the size of the County and changes in elevation and climate, weather conditions can vary greatly across the County. The profiles that follow provide information, where possible, from three weather stations in different parts of the County: Huntington Lake (elevation: 7,000 feet) in east Fresno County, Fresno WSO AP (elevation: 33 feet) in central Fresno County, and Coalinga (elevation: 66 feet), in west Fresno County.

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SEVERE WEATHER: EXTREME TEMPERATURES

HAZARD/PROBLEM DESCRIPTION
Extreme temperature events, both cold and hot, can have severe impacts on human health and mortality, natural ecosystems, and agriculture and other economic sectors.

EXTREME COLD/FREEZE
Extreme cold or freeze is largely accompanied by a winter storm or weather system that produces cold temperatures. What is considered an excessively cold temperature varies according to the normal climate for that region. However, when temperatures are far below normal, with higher wind speeds, heat leaves the human body more rapidly, which increases the possibility of negative effects from these extreme temperatures. 39
The greatest danger from extreme cold is to people, as prolonged exposure can cause frostbite or hypothermia, and can become life threatening. When someone is suffering from hypothermia, body temperatures can become so low that they affect the brain, making it difficult for the victim to think clearly or move well. In the case of frostbite, the frozen tissue becomes numb, and the victim may be unaware that anything is wrong until someone else notices. This makes hazards from extreme cold particularly dangerous, as people may not understand what is happening to them or what to do about it. 40 The primary hazards from extreme cold are frostbite and hypothermia. Frostbite is caused by freezing of the skin and underly tissue. It causes a loss of feeling and color in the affected areas of the body, and most often affects the nose, chin, fingers, or toes. It can be permanently damaging if not treated promptly and can lead to infection, nerve damage, or amputation in severe cases. The risk of frostbite is increased in people with preexisting conditions, the elderly, people with reduced blood circulation, and people who are not dressed warmly enough for the conditions.

Hypothermia occurs when the body loses heat faster than it can produce heat, causing a dangerously low body temperature. A normal body temperature is around 98.6° F. Hypothermia occurs when your body temperature falls below 95° F.45 As this happens, the heart and other essential organs cannot work properly. If hypothermia is not treated, it can lead to heart failure, respiratory failure, and eventually to death. 41
Excessive or extreme cold can accompany severe winter weather, or it can occur without severe weather. For this reason, extreme cold is considered a separate hazard from severe winter storms. The effects of freezing temperatures on agriculture in Fresno County are discussed further in the Agricultural Hazards section.

In Fresno County, the average low temperatures in the winter months range from 53 to 38 degrees.

Therefore, it is likely that since the average low in the month of January specifically, is 38 degrees that there are days in which temperatures are below freezing.

39 National Weather Service. Stay Safe in the Extreme Cold. Retrieved 12.07.23from: https://www.weather.gov/dlh/extremecold 40 Centers for Disease Control and Prevention. Extreme Cold: A Prevention Guide to Promote Your Personal Health and Safety. Retrieved

12.07.23 from: https://www.cdc.gov/nceh/toolkits/winterweather/default.html 41 Mayo Clinic. Hypothermia: Overview. Retrieved 12.07.23 from https://www.mayoclinic.org/diseases- conditions/hypothermia/symptoms-causes/syc-20352682

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Source NWS

WIND CHILL
The National Weather Service Issues Extreme Cold Warnings when the temperature feels like it is -30° F or colder across a wide area for a period of at least several hours. When possible, these advisories are issued a day or two in advance of the conditions.

The most common extent/severity marker for extreme cold is the Wind Chill scale. Figure 36. NWS National Weather Service Wind Chill Chart depicts the National Weather Service’s methodology for determining the wind chill, using wind speed and actual temperature. Although wind chill is not necessarily related to extreme cold as a single cause, the advisory system that the NWS currently uses relies on wind chill to relay warning and advisory information to the public. Extreme cold severity is a function of wind chill and other factors, such as precipitation amount (rain, sleet, ice, and/or snow).  42

42 Climate Fresno - California and Weather averages Fresno (usclimatedata.com) https://www.usclimatedata.com/climate/fresno/california/united-states/usca2234 Figure 35. Fresno County Average Temperatures and Precipitation

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Figure 36. NWS National Weather Service Wind Chill Chart

Source: NWS

EXTREME HEAT
Extreme heat, as per the guidance provided by the Fresno County Public Health, is considered a period of high heat and humidity with temperatures above 90 degrees for at least two to three days. In extreme heat your body works extra hard to maintain a normal temperature, which can lead to death. These episodes, often referred to as "heat waves," lack a universal definition but are typically delineated by the potential for dangerously hot weather conditions capable of causing heat-related illnesses and even fatalities. 30
Remarkably, heat-related issues pose a significant threat and constitute one of the foremost weather- related causes of mortality in the United States. Annually, they claim the lives of over a thousand individuals. Those most susceptible to the adverse effects of extreme heat span a diverse spectrum and include, but are not limited to, vulnerable populations such as infants and young children, older adults, individuals with chronic medical conditions, pregnant women, and those with disabilities. 31 Furthermore, the United States, with particular emphasis on the Los Angeles region, is confronting an ominous trajectory regarding extreme heat events. This trajectory is inexorably linked to the ongoing and anticipated shifts in our climate. As climate change continues to unfold, it is expected that both the frequency and severity of extreme heat events will escalate, heightening the urgency for proactive measures to protect communities and mitigate the associated risks. Therefore, it is imperative for regions like Los Angeles to prepare for these impending challenges and enact robust strategies to safeguard the health and well-being of their residents in the face of rising temperatures.

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Heat Index
The Heat Index is a metric that considers both the actual air temperature and the relative humidity, providing a more accurate reflection of how hot it feels. Relative humidity represents the amount of moisture in the air compared to what it would contain if fully saturated, which depends on both moisture content and temperature. There exists a clear correlation between air temperature, relative humidity, and the heat index, such that as air temperature and relative humidity rise, the heat index follows suit, and conversely, it drops when they decrease. The National Weather Service has created a Heat Index Chart, denoted in Figure 37. NWS Heat Index, which illustrates how the Heat Index classifications change and intensify from "Caution" to "Extreme Danger" as both temperature and relative humidity increase.34

Figure 37. NWS Heat Index

Source: NWS

The classifications of the Heat Index describe the risk of heat disorders with prolonged exposure or strenuous activity. As the heat index increases the heat index classification increases as well and darkens from light yellow to red. This also increases the likelihood for individuals to experience adverse effects on the body. The description of the heat index can affect the body is described in Table 39.

Extreme Heat Health Impacts Using the Heat Index.

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Table 39. Extreme Heat Health Impacts Using the Heat Index Classification Heat Index Effect on the Body
Caution
(Light Yellow) 80F-90F Fatigue possible with prolonged exposure and/or physical activity
Extreme Caution
(Yellow) 90F-103F Heat stroke, heat cramps, or heat exhaustion possible with prolonged exposure and/or physical activity
Danger
(Orange) 103F-124F Heat cramps or heat exhaustion likely, and heat stroke possible with prolonged and/or physical activity
Extreme Danger
(Dark Red) 125F or higher Heat stroke highly likely
Source: NWS

Wet Bulb Globe Temperature
The Wet Bulb Globe Temperature (WBGT) is a comprehensive meteorological metric that encompasses several vital weather parameters, including temperature, humidity, wind, solar radiation, and more. This multi-faceted index plays a pivotal role in assessing the risk of heat stress, particularly for populations engaging in outdoor activities, such as outdoor workers and athletes.

WBGT serves as a crucial tool for making informed decisions when its com/.’]es to safeguard individuals or entire communities during hot and potentially hazardous weather conditions. Its application extends to various scenarios, where mitigating the effects of extreme heat is paramount.

For instance, in the context of outdoor work, WBGT can guide recommendations for necessary modifications. These may involve advising outdoor laborers to curtail strenuous activities during periods of elevated WBGT, suggesting shifts that begin earlier or later in the day when conditions are less oppressive, and ensuring the availability of shaded areas to allow for periodic relief from the heat.

By factoring in a comprehensive range of meteorological elements, the WBGT not only provides a more nuanced understanding of heat stress but also empowers decision-makers to proactively protect the well-being of those exposed to the elements, ultimately enhancing safety, and minimizing the risks associated with extreme heat.

Heat Risk
The National Weather Service (NWS) HeatRisk prototype is a color-numeric-based index that provides a forecast of the potential level of risk for heat-related impacts to occur over a 24-hour period. That level of risk is illustrated by a color/number along with identifying the groups potentially most at risk at that level. Each HeatRisk level is also accompanied by recommendations for heat protection and can serve as a useful tool for planning for upcoming heat and its associated potential risk. Based on the NWS high resolution national gridded forecast database, a daily HeatRisk value is calculated for each location from the current date through seven days in the future.

The HeatRisk prototype takes into consideration:
▪ How unusually above normal the temperatures are at your location (is it warmer than the top 5 percent of hottest days in the period of record for this date?)

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▪ The time of the year (for example, is this early season heat that you likely haven't become used to, typical mid-summer heat, or late season heat that you may have become more used to?) ▪ The duration of unusual heat (for example, are temperatures overnight at levels that would lower heat stress, maintain it, or will unusually warm overnight low temperatures add to heat stress into the next day)
▪ If those temperatures are at levels that pose an elevated risk for heat complications, such as heat stress, based on peer-reviewed science and heat-health thresholds supported by the Centers for Disease Control and Prevention (CDC) national data sets.

The Heat Risk tool can be used to protect communities and individuals from potential risks of extreme heat. Adverse impacts from weather events generally affect historically underserved communities and the Heat Risk tool seeks to provide support for those communities and be better prepared. Groups that are heat-sensitive or heat vulnerable face a higher risk of heat-related illnesses and adverse impacts than others. This groups include:

▪ The elderly and very young
▪ People experiencing homelessness
▪ Individuals on certain medications and/or those with pre-existing conditions that increase heat sensitivity
▪ Outdoor workers, especially new workers, temporary workers, workers that are not yet accustomed to working outdoors, and those working in non-cooled spaces ▪ Individuals exercising or engaging in strenuous activities outdoors during the heat of day, especially those that are not accustomed to the level of heat, not drinking enough fluids, and those new to that type of activity.
▪ Individuals without adequate cooling mechanisms or proper hydration ▪ Individuals not acclimated to the level of heat expected, especially those that are new to a warmer climate
▪ Individuals sensitive to poor air quality, which can be exacerbated by heat waves ▪ Individuals living in low-income communities

Heat Tools and the National Weather Service Heat Products The National Weather Service (NWS) uses the various tools described including the Wet Bulb Globe Temperature tool, Heat Risk tool, and the Heat Index to inform the issuance of NWS official heat watches, warnings, and advisories. Each tool provides a different perspective beyond what the actual air temperature is and can provide a deeper level of understanding.

EXTENT
Large - Both extreme heat and extreme cold cover greater than 25 percent of the planning area.

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EXTREME HEAT
The NWS has in place a system to initiate alert procedures (advisories, watches, and warnings) when high temperatures are expected to have a significant impact on public safety. The expected severity of the heat determines which type of alert is issued, described in Table 40. NWS Heat Related Product.

Table 40. NWS Heat Related Product
Heat-Related Product Description
Excessive Heat Warning
(Dark Purple)
An Excessive Heat Warning is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Warning is when the maximum heat index temperature is expected to be 105° or higher for at least 2 days and night-time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas not used to extreme heat conditions. If you don't take precautions immediately when conditions are extreme, you may become seriously ill or even die.

Excessive Heat Watches
(Dark Red)
Heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased but its occurrence and timing is still uncertain.

Heat Advisory
(Orange)
A Heat Advisory is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Advisory is when the maximum heat index temperature is expected to be 100° or higher for at least 2 days, and night- time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas that are not used to dangerous heat conditions.

Take precautions to avoid heat illness. If you don't take precautions, you may become seriously ill or even die.

Excessive Heat Outlooks
(Light Yellow)
The outlooks are issued when the potential exists for an excessive heat event in the next 3-7 days. An Outlook provides information to those who need considerable lead-time to prepare for the event.

Source: NWS

A common guideline for the issuance of excessive heat alerts in Fresno County is when the maximum daytime high is expected to equal or exceed 110°F and a nighttime minimum high of 80°F or above is expected for two or more consecutive days.

Fresno County begins to experience hot weather in May or June of each year, and the heat continues throughout the summer months. The Fresno County Heat Emergency Contingency Plan provides a two-phase approach to mitigate and reduce the effects of extreme heat. Phase I calls for a heat awareness campaign to be initiated at the beginning of the heat season. Phase II calls for an operational area response to a heat emergency. The County Health Officer may determine that a Heat Emergency exists based on the threat to public health and safety. This may include:

• Excessive Heat Warning or Heat Wave issued by the NWS. • Heat-related illnesses and deaths are above average.
• Abnormal amounts of heat related deaths occur in local animal populations.

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• Successive days when daytime temperature exceeds normal ranges, and the nighttime heat index does not drop below 80 degrees.
• The California Independent System Operator (CALISO) issues a Stage 3 Electrical Emergency. • High heat is accompanied by electrical blackouts or rotating power outages. • Two or more jurisdictions within the County “declare” heat emergencies. • The state “declares” a heat emergency.

EXTREME COLD
Similar to Extreme Heat, the National Weather Service (NWS) has in place a system to initiate alert procedures (advisories, watches, and warnings) when low temperatures are expected to have a significant impact on public safety. The expected severity of the cold determines which type of alert is issued, described in Table 41. NWS Winter Storm Weather Products.

Table 41. NWS Winter Storm Weather Products
Winter Storm Product Description
Winter Weather Advisory
(Light Purple)
Wintry weather expected. Light amounts of wintry precipitation or patchy amounts of wintry precipitation or patchy blowing snow will cause slick conditions and could affect travel if precautions are not taken.

Winter Storm Watch
(Light Blue)
Snow, sleet, or ice possible. Confidence is medium that a winter storm could produce heavy snow, sleet, or freezing rain and cause significant impacts.

Winter Storm Warning
(Pink)
Snow, sleet, or ice expected. Confidence is high that a winter storm will produce heavy snow, slight, or freezing rain and cause significant impacts.

Source: NWS

The National Weather Service (NWS) developed the Wind Chill Temperature (WTC) index to provide a formula to calculate the dangers from winter winds and freezing temperatures shown in Table 42. NWS Extreme Cold Weather Products. Additionally, the NWS produces frost and freeze advisory, watch, and warning to communicate when temperatures can pose a risk.

Table 42. NWS Extreme Cold Weather Products
NWS Product Description
Frost Advisory
(Light Blue)
A frost advisory means areas of frost are expected or occurring, posing a threat to sensitive vegetation.

Freeze Watch
(Blue)
NWS issues a freeze watch when there is a potential for significant, widespread freezing temperatures within the next 24-36 hours. A freeze watch is issued in the autumn until the end of the growing season and in the spring at the start of the growing season.

Freeze Warning
(Dark Blue)
When temperatures are forecasted to go below 32°F for a long period of time, NWS issues a freeze warning. This temperature threshold kills some types of commercial crops and residential plants.

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NWS Product Description
Hard Freeze Warning
(Light Purple)
NWS issues a hard freeze warning when temperatures are expected to drop below 28°F for an extended period of time, killing most types of commercial crops and residential plants.

Source: NWS

Overall, extreme temperature impacts would likely be limited in the planning area, at least 25 percent of the planning area affected, which is extensive. Extreme cold can occasionally cause problems with communications facilities and utility transmission lines. Danger to people is highest when they are unable to heat their homes and when water pipes freeze. Extreme cold and extreme heat can also impact livestock and even crops if the event occurs during certain times of the year.

PAST OCCURRENCES
Information from the three representative weather stations introduced in the Severe Weather: General section, is summarized below.

FRESNO COUNTY—EAST (MAMMOTH LAKE, INYO COUNTY, PERIOD OF RECORD 12/01/1993 - 08/31/2020)
The previous plan included weather data from the Huntington Lake weather station, however data from that weather station has not been updated since 2016. Therefore, the Mammoth Lake weather station was used in Inyo County, which is just outside of the northeastern portion of Fresno County, to provide an understanding of averages for the eastern portion of the jurisdiction. While the period of record only captures up until August of 2020, it is the closest weather station to the eastern portion of Eastern Fresno County that has a similar environment.

Monthly average maximum temperatures in the warmest months (May through October) range from the mid-50s to low 80s. Monthly average minimum temperatures from November through April range from the high 20s to low 10s. July 11 had the highest extreme maximum temperature of 91 degrees. January 13 had the lowest extreme minimum temperature of -16 degrees.

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Source: Western Regional Climate Center, www.wrcc.dri.edu/

FRESNO COUNTY—CENTRAL (FRESNO YOSEMITE INTERNATIONAL, PERIOD OF RECORD 01/01/1948 - 02/04/2024
Monthly average maximum temperatures in the warmest months (May through October) range from the high 70s to low 100s. Monthly average minimum temperatures from November through April range from the mid-30s to mid-40s. September 6 had the highest extreme maximum temperature of 114 degrees.

December 23 and January 10 had the lowest extreme minimum temperature of 18 degrees.

Figure 38. Mammoth Lakes Daily Averages and Extremes: Temperatures

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Source: Western Regional Climate Center, www.wrcc.dri.edu/

FRESNO COUNTY—WEST (COALINGA WEATHER STATION, PERIOD OF RECORD 1942 TO 2023)
Monthly average maximum temperatures in the warmest months (May through October) range from the high 70s to low 100s. Monthly average minimum temperatures from November through April range from the high 40s to 100s. July 12 had the highest extreme maximum temperature of 118 degrees.

December 22 had the lowest extreme minimum temperature of 11 degrees.

Figure 39. Fresno Yosemite International Daily Averages and Extremes: Temperatures

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Source: Western Regional Climate Center, www.wrcc.dri.edu/ Figure 40. Coalinga Daily Averages and Extremes: Temperature

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The HMPC identified the following events related to extreme temperatures in the Fresno County planning area:

EXTREME COLD/FREEZE
▪ 1990: This freeze event is on record as the most economically devastating freeze event to date due to the loss of production citrus trees, not just the loss of the fruit crop. ▪ December 20-28, 1998: Extreme low temperatures adversely affected agricultural crops in the County. Citrus crops were impacted the most, but winter vegetables were also damaged. Total crop damage was estimated at $74 million. The loss to crops also resulted in unemployment and loss of income to small towns and industry throughout the planning area. An estimated 14,000 or more agricultural workers were out of work. Estimated economic impacts to the community were $220 million. This freeze resulted in local, state, and federal declarations (2/9/99). The County also incurred $223,700 in damage to government facilities and roads. Statewide, $2.5 million was paid out in claims.
▪ January 2007: Freezing temperatures destroyed citrus crops and put many people out of work.

Within the agricultural citrus belts, temperatures ranged from 19-24°F during the morning. Damage to County facilities was estimated at $15,000. Crop damage was estimated at roughly $128 million.

Residual effects from loss of sales and resulting unemployment were three times the cost of the crop damage ($383 million). Local, state, and federal disasters were declared. The state provided monies for mortgage and rental assistance. Federal and state donations to local food banks were increased. Unemployment insurance benefits were also increased. Central and South Valley estimated combined property damage was $250,000, and agricultural damage was $710 million.

Table 43. Fresno County Previous Occurrences: Extreme Cold Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Fresno County 1990 0 0 0 0
Fresno County 12/20/1998 –
12/28/1998 0 223,700 74 M 0 0
Fresno County January 2007 0 250,000 128 M 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

EXTREME HEAT
▪ July 2006: The planning area experienced six days of triple digit temperatures. The state declared a heat emergency for Fresno County. Cooling centers were opened by the state and some local jurisdictions. 24 people died between July 14 and August 1. 16,500-25,000 dairy cattle died in the Central Valley, and up to 700,000 poultry died. Milk production was down 30 percent, with dairy losses estimated to exceed $80 million. Residual effects from loss of sales and resulting unemployment were three times the cost to the livestock industry. A local declaration was also declared to dispose of dead livestock at the County landfill. Federal/state disaster relief included $16 million for lost milk production. Federal loans were made available to farmers.

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▪ July 2007: Extreme, prolonged heat caused a mass die-off of farm animals such as dairy cattle and poultry. An estimated 50,000 turkeys, weighing up to 40 pounds each, died, which created a disposal issue. Zacky Farms was hit hardest, but other losses were incurred at various locations throughout the County. A local emergency was declared to legally dispose of these animals at the local landfill.
▪ July 2008: An intense heatwave gripped Interior Central California starting July 8 due to a high- pressure system, with temperatures soaring to 105-112 degrees and minimum heat index values staying above 80 degrees at night. Record-breaking minimum temperatures were observed in Bakersfield and Fresno, exacerbating conditions already critical due to concurrent wildfires which led to significant air quality issues and advisories. This extreme weather claimed the lives of two farm workers in Kern County, highlighted the vulnerability of sensitive groups, and resulted in substantial poultry losses in Kings County, prompting a local state of emergency. ▪ August 2011: In late August, a robust high-pressure system caused a severe heatwave in southeast California, with temperatures in Joshua Tree National Park surpassing 110 degrees from Tuesday through Saturday. The extreme conditions resulted in the tragic deaths of two European tourists, whose bodies were discovered near Black Eagle Mine Road, indicating they suffered from exposure after leaving their vehicle in a challenging area of the park. Authorities concluded that the victims, found a mile apart, had entered the park before noon and their vehicle was left in a location unsuitable for passenger vehicles.
▪ July 2013: A record-setting ridge of high pressure (600 dm over northern New Mexico) built in over the Great Basin and desert Southwest, beginning around June 29th, lasting through approximately July 7, when it hit another peak in temperatures. This resulted in extreme high temperatures, well above normal, across the region during this period. The hottest days in July were the 1st through the 3rd, during which several record high minimums were set, as well as highs well over 100 degrees. Prolonged heat in the higher terrain was a significant impact, like in San Diego County. ▪ June 2016: Strong high pressure over the four corners region retrograded westward over southern and central California bringing a period of high temperatures over the 110-degree mark to locations in the Kern County Desert.
▪ June 2017: A prolonged heatwave caused by a high-pressure ridge resulted in extreme temperatures, particularly in desert regions where Palm Springs hit 122 degrees on the 20th, 24th, and 25th of the month. The intense heat triggered Flex Alerts for energy conservation and led to a local emergency in Fresno County due to delays at a rendering facility that impacted livestock carcass processing. Measures were taken to implement alternative disposal methods as per Fresno County health and agricultural authorities.
▪ August 2017: Upper-level high pressure brought record heat to the area. A plume of subtropical moisture promoted the growth of isolated afternoon thunderstorms with large hail. A 13-year-old was hospitalized Tuesday after suffering heat stroke during tryouts for the freshman football team at Lincoln High School on August 1. Temperatures at Lincoln Airport reached 100 degrees between 4 and 7 pm PDT.
▪ September 2017: A persistent large upper ridge centered over the Great Basin provided the area with an extended period of much warmer than normal temperatures between August 26 and September 3. High temperatures ranged mainly from 106 to 112 degrees at many locations each day between August 26 and September 3 across the San Joaquin Valley, the southern Sierra foothills, and the Kern County Deserts while morning lows ranged from the mid 70's to the lower 80's.

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▪ June 2019: A large area of high pressure prevailed over California between June 10 and June 12 which resulted in much warmer than normal temperatures across the area during the period. High temperatures generally ranged between 102 and 107 degrees each day across much of the San Joaquin Valley prompting the first Excessive Heat Warning of the season. As a result of the heat, emergency cooling centers were opened each afternoon in several municipalities in the San Joaquin Valley during this period.
▪ May 2020: A large area of high pressure built into California on May 25 and May 26. This resulted in much above normal daytime temperatures on both days with some locations setting new daily records on May 26. The high then strengthened on May 27 and May 28 resulting in widespread record heat over the region on both days with highs in the San Joaquin Valley mainly between 103 and 107 on both days. Triple digit heat was also observed across portions of the Sierra foothills and Kern County Deserts. Temperatures cooled by several degrees on May 29 and lowered to below seasonal averages by May 30 as the large area high pressure broke down, and a cold front pushed through the area.
▪ August 2020: On August 14, a dominant high-pressure system over the Desert Southwest extended its reach over central California, leading to extreme heat and triggering Excessive Heat Warnings for multiple regions, including the San Joaquin Valley and Kern County Deserts. Record- breaking temperatures were observed on August 16 and 17, exceeding 110 degrees F, prompting several local emergencies due to livestock fatalities and the opening of cooling centers. This prolonged heat event subsided on August 21 as a northwesterly flow ushered in cooler air, offering a respite from the searing temperatures.
▪ June / July 2021: In June 2021, a large upper ridge over the four corners area expanded westward, bringing extreme heat to central California from June 15 to 18, with Kern County Deserts feeling the surge by June 15 and temperatures climbing over 110°F in several areas by June 19.

Relief came between June 20 and 22 as the ridge moved east, reducing the scorching temperatures. The following month, from July 7 to 13, another intense high-pressure system settled over the region, causing several days of near-record temperatures, and marking the most severe heat spell since July 2006, albeit with lower humidity levels that mitigated the overall impact. The heat moderated across the area by July 14 as the ridge shifted eastward. ▪ September 2021: A large upper high-pressure center strengthened over the Great Basin during the Labor Day weekend (September 4 to September 6) resulting in temperatures rising to much above normal levels over the San Joaquin Valley, West Side Hills, and Kern County Deserts on September 6. The dangerous heat remained prevalent over the area through September 9 prompting the issuance of heat highlights as the large upper high produced a pronounced southeast flow over the area. A trough moved into northern California during the morning of September 10 bringing an end to the dangerous heat as afternoon highs remained below the century mark at most stations.
▪ September 2022: A large area of high pressure that was centered over the Great Basin area built westward into California on August 31st and brought a period of hot and dry weather to the area which prevailed across the area through much of early September. An Excessive Heat Warning was issued for a large portion of the area including all the San Joaquin Valley, the West Side Hills, the Sierra Foothills, Yosemite Valley, The Kern River Valley, and the Kern County desert areas and remained in effect until the evening hours of September 9. The large high-pressure area finally broke down on September 9 and temperatures remained below dangerous levels on September 10. ▪ July 2023: California experienced multiple waves of high pressure, starting with record-high temperatures on the 1st and 2nd, which cooled slightly on the 3rd as the pressure system shifted eastward. Mid-month, from the 13th to the 17th, another high-pressure build-up over the Desert

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Southwest pushed temperatures near record highs, prompting an Excessive Heat Warning across the region, sparing only the Sierra Nevada above 7000 feet where a Heat Advisory was declared.

The pattern repeated with even stronger high pressure from the 21st to the 23rd, inducing a dangerous heat period until a diminishing ridge brought a mild cooling trend by the 25th, with temperatures staying above normal but below hazardous levels in the days following.

Table 44. Fresno County Previous Occurrences: Extreme Heat Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Fresno County 7/16/2006 –
7/22/2006 0 0 0 0 0
Fresno County July 2007 0 0 0 0 0
Fresno County July 2008 0 0 0 2 0
Joshua Tree
National Park August 2011 0 0 0 2 0
Fresno County July 2013 0 0 0 0 0
Fresno County June 2016 0 0 0 0 0
Fresno County June 2017 0 0 0 0 0
Fresno County August 2017 0 0 0 0 1
Clovis 9/01/2017 0 0 0 0 0
Coalinga,
Mendota,
Firebaugh
6/10/2019 0 0 0 0 0
Coalinga,
Mendota,
Firebaugh
5/26/2020 0 0 0 0 0
Coalinga,
Mendota,
Firebaugh
8/14/2020 0 4M 0 0 0
Tollhouse,
Pine Ridge 6/17/2021 0 0 0 0 0
Coalinga,
Mendota,
Firebaugh
7/09/2021 0 0 0 0 0
Coalinga,
Avenal 9/09/2021 0 0 0 0 0
Hanford,
Corcoran,
Lemoore
9/01/2022 0 0 0 0 0
Coalinga,
Lemoore,
Hanford
July 2023 0 0 0 0 0
Coalinga,
Lemoore,
Hanford
7/15/2023 0 0 0 0 0
Hanford,
Corcoran,
Lemoore
7/21/2023 0 0 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

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LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Temperature extremes are likely to continue to occur annually in the Fresno County planning area.

EXTREME HEAT
The California Heat Assessment Tool (CHAT) was funded and developed to better understand heat vulnerability driven by climate changes to support mitigating public health impacts of extreme heat events in the future. According to CHAT, the projected Average Maximum Temperature during future Heat Health Event (HHEs) for Fresno County, areas within the jurisdiction are projected to reach 90-94 to 106-110 degrees Fahrenheit are shown in Figure 38. Fresno County California Heat Assessment Tool (CHAT) Heat Health Event Projections.

Source: California Heat Assessment Tool (CHAT)

CLIMATE CHANGE CONSIDERATIONS
Although heat waves will likely become more frequent, there is also the potential for continued cold outbreaks in winter, even in an overall warmer climate. This could have direct impacts on human health in terms of heat related illness. With the general trend of increased warming of average temperatures, extreme high temperatures will likely increase as well. Cascading impacts include increased stress on water quantity and quality, degraded air quality, and increased potential for more severe or catastrophic Figure 41. Fresno County California Heat Assessment Tool (CHAT) Heat Health Event Projections

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natural events such as heavy rain, droughts, and wildfire. Another cascading impact includes increased duration and intensity of wildfires with warmer temperatures.

Temperatures in the State of California are projected to increase overall. As a part of the California’s Changing Climate 2018 report, by 2100 the average annual maximum daily temperature is projected to increase by 5.6-8.8 degrees Fahrenheit. As a result, heat waves are expected to increase in frequency, duration, and magnitude. Los Angeles County will experience an average of nine days of extreme heat per year, growing to 12 days per year, by the final decades of the century.

SEVERE WEATHER: FOG

HAZARD/PROBLEM DESCRIPTION
Fog results from air being cooled to the point where it can no longer hold all the water vapor it contains.

For example, rain can cool and moisten the air near the surface until fog forms. A cloud- free, humid air mass at night can lead to fog formation, where land and water surfaces that have warmed up during the summer are still evaporating water into the atmosphere. This is called radiation fog. A warm moist air mass blowing over a cold surface also can cause fog to form, which is called advection fog.

TULE FOG
The interior California valleys have a unique fog problem called tule fogs. The tule fog is a radiation fog, which condenses when there is a high relative humidity, typically after a heavy rain, calm winds, and rapid cooling during the night. The longer nights during the winter months create this rapid ground cooling and results in a pronounced temperature inversion at a low altitude, creating a thick ground fog.

Above the cold, foggy layer, the air is typically warm and dry. Once the fog has formed, turbulent air is necessary to break through the inversion. Daytime heating can also work to evaporate the fog in some areas. The tule fogs get their name from the tule reeds, which grew around the swamps and deltas of the great Tulare Lake that once covered the southern end of the San Joaquin Valley.

The tule fog season in Fresno County is typically in the late fall and winter (November through March) but can occur as late as May. Fog typically forms rapidly in the early morning hours. Tule fog can last for days, sometimes weeks. Fog can have devastating effects on transportation corridors in the County.

Nighttime driving in the fog is dangerous and multi-car pileups have resulted from drivers using excessive speed for the conditions and visibility.

The San Joaquin Valley is hemmed in on three sides by mountain ranges, with resulting inversion layers trapping cooler air on the valley floor. This predisposes the Fresno area to severe episodes of fog in winter months, when barometric pressures are high, humidity is increased, and ambient temperatures are low. Table 45. Average Number of Dense Fog Days (October-April) shows the monthly and total average number of days with dense fog from 1910-2024. The number of dense fog days per year has decreased in the past several decades, Figure 39. Average Number of Dense Fog Days Per Year (1910-2024) shows the average number of dense fog days per year. 43

43 Number of Days With Dense Fog by Cool Season FAT.pdf (weather.gov) https://www.weather.gov/media/hnx/

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Table 45. Average Number of Dense Fog Days (October-April) Source: NOAA

October November December January February March April Total Average
Number
of Days
with
Dense
Fog
2 days 5 days 10 days 10 days 5 days 2 days 1 day 31 days

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Source: NOAA

Fog contributes to transportation accidents and is a significant life safety hazard. These accidents can cause multiple injuries and deaths and could have serious implications for human health and the environment if a hazardous or nuclear waste shipment were involved. Other disruptions from fog include delayed emergency response vehicles and school closures.

EXTENT
Tule fog forms on clear nights when the ground is moist, and the wind is near calm. On nights like this, the ground cools rapidly. In turn, the moist air above it cools and causes water vapor to condense.

Once it has formed, the air must be heated enough to either evaporate the fog or lift it above the surface so that visibilities improve. Common areas for tule fog to form include foothills and valleys.

Visibility in tule fog is usually less than an eighth of a mile (about 600 ft or 200 m) but can be much lower. Visibility can vary rapidly; in only a few feet, visibility can go from 10 feet (3.0 m) to near zero.

Figure 40. November 2007 Fog Incident shows an example of an incident caused by tule fog in Fresno County.

Figure 42. Average Number of Dense Fog Days Per Year (1910-2024) 0 1
2 3
4 5
6 7
8 9
10 2022-2023
2019-2020
2016-2017
2013-2014
2010-2011
2007-2008
2004-2005
2001-2002
1998-1999
1995-1996
1992-1993
1989-1990
1986-1987
1983-1984
1980-1981
1977-1978
1974-1975
1971-1972
1968-1969
1965-1966
1962-1963
1959-1960
1956-1957
1953-1954
1950-1951
1947-1948
1944-1945
1941-1942
1938-1939
1935-1936
1932-1933
1929-1930
1926-1927
1923-1924
1920-1921
1917-1918
1914-1915
1911-1912
Average Number of Dense Fog Days Per Year (1910-2024)

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Source: Donavan, California Highway Patrol

Most of these notable fog-related accidents occurred on Highway 99, like the one pictured above.

Traffic Accident Caused by Fog, November 2007. In addition to these events, other, less notable collisions occurred on other roads during foggy conditions. Of their most notable fog events, there have been over 20 deaths and hundreds of injuries.

PAST OCCURRENCES
According to the HMPC, severe fog is a recurring problem within the planning area, and most damage results from automobile accidents. Most of these incidents occurred between November and March; one was in October. There have been hundreds of reported fog incidents since 1950, the most notable fog incidents reported by the HMPC include in the following below and in Table 46. Fresno County Past Occurrences: Fog.

▪ February 1991: A series of accidents involving 74 vehicles occurred along a three-mile, fog- shrouded stretch of Highway 99 south of Fresno. Three people were killed and 30 were injured.

Figure 43. November 2007 Fog Incident

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▪ January 16, 1994: Dense fog caused a 56-vehicle pileup on Highway 99 near Selma, killing two people and injuring 42 others.
▪ November 1998: Dense fog caused a chain-reaction accident involving 74 vehicles along a one- mile stretch of Highway 99 near Kingsburg. Two people were killed, 51 others injured. ▪ February 2002: Fog was a factor in a string of crashes on Highway 99 near Selma that killed two people. More than 30 others were injured in the accident, which involved 87 cars, trucks, and big rigs over a four-mile stretch.
▪ November 20, 2002: Fog was a major factor in a 50-vehicle collision on Highway 99 near Merced that resulted in 32 injuries.
▪ February 7, 2006: Fog was a factor in a 20-vehicle collision on Highway 99 near Tulare that resulted in one death and multiple injuries.
▪ November 3, 2007: Dense fog contributed to the worst traffic accident in Fresno County on Highway 99 just south of Fresno. At least two people were killed in the 108-car chain-reaction crash, which involved 18 big rigs, and 39 individuals were sent to local hospitals. Drunk driving was also cited as a contributing factor. Traffic Accident Caused by Fog, November 2007. ▪ February 2008: Two nights of dense fog resulted in a 10-15 car pileup on the morning of the 11th near Kerman west of Fresno, where there were no injuries, and newspaper accounts of only minor property damages. However, the fog was a major factor in a series of chain-reaction accidents on Highway 99 near Kingsburg during the morning of February 12th. At least four separate accidents occurred, involving at least 40 vehicles, and resulting in at an estimated 10 people being injured. ▪ November 2012: Patchy dense fog developed in the San Joaquin Valley following a storm on November 20th-21st, starting in the Los Banos area before spreading to the Reedley-Visalia area.

This fog caused variable visibilities across the Valley, affecting most airports with fluctuations from near zero to a couple of miles. Persistent dense fog was implicated in a fatal chain reaction crash on Highway 152 near Chowchilla in Madera County on the morning of November 27th. ▪ January 2013: January began with the central and southern San Joaquin Valley under a cold, dry airmass that moved into the region. Dense fog continued its reputation as the main winter weather hazard for the central and southern San Joaquin Valley, as a fatal collision occurred 3 miles southeast of Chowchilla in dense fog during the morning of January 4th. These conditions continued through the morning of the 5th, and then a strong upper-level low brought the first precipitation of the year that evening.
▪ January 2017: High pressure with clearing skies over the region coupled with recent heavy precipitation created ideal conditions for dense nighttime and morning radiational fog to develop.

Fresno police and California Highway Patrol reported a 2-vehicle accident during dense fog causing one fatality at Jensen Avenue and Chateau Fresno Avenue in the city of Fresno in Fresno County.

It also appeared alcohol was a factor.
▪ 1/31/2017: High pressure with clearing skies over the region coupled with recent heavy precipitation created ideal conditions for dense nighttime and morning radiational fog to develop. Damages totaled thousands of dollars and resulted in 1 death.
▪ 1/10/2019: An upper ridge pushed inland into California on the evening of January 9th and morning of January 10. As a result, skies cleared out and winds diminished across the San Joaquin Valley during the early morning hours which led to the development of widespread dense fog across much of the valley on the morning of the 10th and several locations reported visibility of an eighth of a mile or less. The dense fog was responsible for a fatal auto accident near Atwater. Several school

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districts in the valley opened late that morning. The fog lifted into a low cloud deck by late morning and dissipated by early afternoon.
▪ 1/27/2019: The fog reformed in much of the valley not long after midnight and persisted until late morning. Fog reduced visibility to below an eighth of a mile for 5 to 10 hours at several locations.

There were several fog related accidents during the morning of January 27 and California Highway Patrol paced traffic on several highways until the fog lifted by late morning. ▪ 12/11/2019: Fog settled back into the San Joaquin Valley north of Kern County during the evening of December 10 and reduced visibility to below a quarter mile at several locations during the morning of December 11. Once again, several school districts in the valley either opened late or delayed bus service. The fog lifted into a status deck by late morning which eroded by afternoon as an upper-level trough moved to the north of the area and mixed out the near surface airmass. ▪ 1/24/2020: High pressure continued to strengthen over the area on January 24, although some high clouds pushed through the area, light winds and inversion conditions allowed for an area of dense fog to form in the center of the San Joaquin Valley north of Kern County where low-level moisture has persisted. The fog reduced visibility to less than an eighth of a mile at several locations and resulted in several school districts either opening late or delaying or cancelling bus service as it persisted until late morning when it lifted into a low cloud deck. The low stratus deck slowly dissipated during the afternoon. The fog also contributed to two multi-vehicle accidents near Caruthers.
▪ 1/06/2021: High pressure built over central California on January 5. With mainly clear skies and light winds, areas of dense fog formed in the San Joaquin Valley during the early morning hours of January 6. The fog did cause a few automobile accidents as it formed over a widespread area. The fog lifted into a stratus deck by late morning as a weak system moved through northern California then dissipated by midday.
▪ 11/21/2021 - Another night of clear skies, light winds and inversion conditions resulted in widespread dense fog forming in the San Joaquin Valley during the evening of November 21 into the early morning of November 22. The fog persisted over a widespread area until late morning when it lifted into a low clouds deck which eroded during the afternoon. The fog resulted in at least three major vehicular accidents in the San Joaquin Valley during the morning of November 22. ▪ 12/03/2021 - Little change in the upper air pattern occurred from the previous day. Clear skies, light winds and inversion conditions in the San Joaquin Valley allowed for areas of dense fog to form in Merced, Madera, and Fresno Counties in the central San Joaquin Valley during the early morning hours and the fog resulted in several multi-vehicle accidents including two which had fatalities.

Traffic was packed during the morning commute on SR 99 north of Madera and several school districts had delayed openings. The fog lifted into a low cloud deck by late morning and dissipated during the afternoon.
▪ January 2022: Persistent dense fog affected parts of the central San Joaquin Valley, particularly between Merced and Madera, from the evening of January 14 until midday on January 16.

Intermittent fog was present in other areas of the San Joaquin Valley during this time. The fog, influenced by a low-pressure system off the Southern California coast, lifted by January 16 and was a contributing factor in a fatal multi-car accident near Biola in Fresno County.

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Table 46. Fresno County Past Occurrences: Fog
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Highway 99
Fresno
February
1991 0 0 0 3 30
Highway 99
Selma 1/16/1994 0 0 0 2 42
Highway 99
Kingsburg
November
1998 0 0 0 2 51
Highway 99
Selma
February
2002 0 0 0 2 30
Highway 99
Merced 11/20/2002 0 0 0 0 32
Highway 99
Tulare 2/07/2006 0 0 0 1 0
Highway 99
Fresno 11/03/2007 0 0 0 2 39
Highway 99
Kingsburg
February
2008 0 0 0 0 10
Los Banos
Area
November
2012 0 0 0 3 0
Southern San
Joaquin Valley January 2013 0 0 0 0 0
Fresno County January 2017 0 33,000 0 1 0
Between
Merced and
Madera
1/14/22 0 630,000 0 0 0
Fresno,
Madera,
Merced, and
Atwater
1/10/2019 0 10,000 0 1 3
San Joaquin
Valley 1/27/2019 0 20,000 0 0 0
Fresno and
Reedley 12/03/2019 0 10,000 0 0 0
Hanford 12/11/2019 0 10,000 0 0 0
Hanford 1/24/2020 0 50,000 0 0 0
Hanford and
Visalia 1/06/2021 0 150,000 0 1 0
Hanford,
Visalia, and
Porterville
11/21/2021 0 65,000 0 0 0
San Joaquin
Valley 11/22/2021 0 15000 0 0 0
San Joaquin
Valley 12/03/2021 0 400,000 0 2 3
Between Selma
and Fresno
Highway 99
1/14/2022 0 630,000 0 1 1

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Source: NOAA, National Centers for Environmental Information, Storm Events Database

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LIKELIHOOD OF FUTURE OCCURRENCES
Likely—Based on the NCEI, since 1991 there have been 28 major fog incidents over a 32-year period equates to a major fog event about once a year and an 87.5 percent chance of a major fog event in any given year. Based on input from the HMPC, it is likely that minor fog events will continue to occur annually in the Fresno County planning area.

CLIMATE CHANGE CONSIDERATIONS
California’s winter tule fog has declined dramatically over the past three decades, raising a red flag for the state’s multibillion dollar agricultural industry, according to researchers at UC Berkeley. Crops such as almonds, pistachios, cherries, apricots, and peaches go through a necessary winter dormant period brought on and maintained by colder temperatures. Tule fog, a thick ground fog that descends upon the state’s Central Valley between late fall and early spring, helps contribute to this winter chill. “The trees need this dormant time to rest so that they can later develop buds, flowers and fruit during the growing season,” said biometeorologist and study lead author Dennis Baldocchi. “An insufficient rest period impairs the ability of farmers to achieve high quality fruit yields.” The findings have implications for the entire country since many of these California crops account for 95 percent of U.S. production, the authors noted. The researchers paired NASA and National Oceanic and Atmospheric Administration satellite records with data from a network of University of California weather stations, covering 32 consecutive winters. There was a great deal of variability from year to year, but on average, the researchers found a 46 percent drop in the number of fog days between the first of November and the end of February. Climate forecasts suggest that the accumulation of winter chill will continue to decrease in the Central Valley. Tule fog was also less prevalent in recent years in part due to the multi- year drought.

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SEVERE WEATHER: HEAVY RAIN/THUNDERSTORM/HAIL/LIGHTNING/WIND

HAZARD/PROBLEM DESCRIPTION
Storms in the Fresno County planning area are generally characterized by heavy rain often accompanied by strong winds and sometimes lightning and hail. Thunderstorms are one of the most common natural hazards in the U.S., with approximately 100,000 thunderstorms recorded per year nationwide. Approximately 10 percent of the thunderstorms that occur each year in the United States are classified as severe. A thunderstorm is classified as severe when it can produce wind gusts greater than 58 mph, or hail that is one inch or larger in diameter, which is about the size of a quarter. Hail that size and larger can destroy crops, roofs, and vehicles, and even cause human casualties. Descriptions of hail, lightning, and high winds, commonly accompanied by severe thunderstorms, are listed below.

▪ Hail: is formed when water droplets freeze and thaw as they are thrown high into the upper atmosphere by the violent internal forces of thunderstorms. Hail is usually associated with severe storms within the Fresno County planning area. Hailstones are usually less than two inches in diameter and can fall at speeds of 120 miles per hour (mph). Hail events are usually brief, lasting on average 10 to 20 minutes but may last longer with some thunderstorms depending on conditions.

Severe hailstorms can be quite destructive, causing damage to roofs, buildings, automobiles, vegetation, and crops.
▪ Lightning: is defined as all the various forms of visible electrical discharge caused by thunderstorms. Thunderstorms and lightning are usually (but not always) accompanied by rain.

Cloud-to-ground lightning can kill or injure people by direct or indirect means. Objects can be struck directly, which may result in an explosion, burn, or destruction. Or, damage may be indirect, when the current passes through or near an object, which generally results in less damage. ▪ High winds: often accompanying severe thunderstorms, can cause significant property and crop damage, threaten public safety, and have adverse economic impacts from business closures and power loss. Windstorms in Fresno County are typically straight-line winds. Straight-line winds are generally any thunderstorm wind that is not associated with rotation (i.e., is not a tornado). It is these winds, which can exceed 100 mph, that represent the most common type of severe weather and are responsible for most wind damage related to thunderstorms. These winds can overturn mobile homes, tear roofs off houses, topple trees, snap power lines, shatter windows, and sandblast paint from cars. Other associated hazards include utility outages, arcing power lines, debris blocking streets, dust storms, and an occasional structure fire. Tornadoes (see Section

4.2.18 Tornado) and funnel clouds can also occur during these types of storms. ▪ Downslope Winds: occur when warm/dry air descends rapidly down a mountain side. These types of winds may commonly occur just west of the Sierras. These winds can blow over 40 mph and can occur in sudden gusts that are even stronger, which can make driving hazardous. In addition, their dry conditions increase the risk of wildfires in the area. ▪ Santa Ana Winds: occur when air from a region of high pressure over the dry, desert region of the southwestern U.S. flows westward towards low pressure located off the California coast. This creates dry winds that flow east to west through the mountain passages in Southern California closer to Los Angeles and San Diego but may occasionally influence Fresno County. These winds are most common during the cooler months of the year, occurring from September through May.

Santa Ana winds typically feel warm (or even hot) because as the cool desert air moves down the side of the mountain, it is compressed, which causes the temperature of the air to rise. These

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strong winds can cause major property damage. They also increase wildfire risk because of the dryness of the winds and the speed at which they can spread a flame across the landscape.

EXTENT
The National Weather Service classifies hail by diameter size, and corresponding everyday objects to help relay scope and severity to the population. Table 47. Hail Measurements indicates the hailstone measurements utilized by the National Weather Service.

Table 47. Hail Measurements
Average Diameter Corresponding
Household Object
Pea 0.25
Marble or Mothball 0.50
Penny or Dime 0.75
Nickle 0.88
Quarter 1.00
Half-Dollar 1.25
Walnut or Ping Pont Ball 1.50
Golf Ball 1.75
Hen’s Egg 2.00
Tennis Ball 2.50
Baseball 2.75
Teacup 3.00
Grapefruit 4.00
Softball 4.50
Source: National Weather Service

The largest hailstones recorded in Fresno County had a diameter of 1.75 inches in 1957. Lightning is measured by the Lightning Activity Level (LAL) scale, created by the National Weather Service to define lightning activity into a specific categorical scale. The LAL is a common parameter that is part of fire weather forecasts nationwide. The LAL is reproduced in Table 48. Lightning Activity Level Scale.

Table 48. Lightning Activity Level Scale
Lightning Activity Level
LAL1 No thunderstorms
LAL2 Isolated thunderstorms. Light rain will occasionally reach the ground. Lightning is very infrequent, 1 to 5 cloud to ground strikes in a five-minute period
LAL3 Widely scattered thunderstorms. Light to moderate rain will reach the ground. Lightning is infrequent, 6 to 10 cloud to ground strikes in a five-minute period.

LAL4 Scattered thunderstorms. Moderate rain is commonly produced. Lightning is frequent, 11 to 15 cloud to ground strikes in a five-minute period.

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Lightning Activity Level
LAL5 Numerous thunderstorms. Rainfall is moderate to heavy. Lightning is frequent and intense, greater than 15 cloud to ground strikes in a five-minute period.

LAL6
Dry lightning (same as LAL 3 but without rain). This type of lightning has the potential for extreme fire activity and is normally highlighted in fire weather forecasts with a Red Flag warning
Source: National Weather Service

High winds or a windstorm are especially dangerous in areas with significant tree stands and areas with exposed property, poorly constructed buildings, manufactured housing units, major infrastructure, and above-ground utility lines. High winds can cause downed trees and power lines, flying debris and building collapses, which may lead to power outages, transportation disruptions, damage to buildings and vehicles, and injury or death. There are several types of high winds events described in Table 49.

Types of High Winds.

Table 49. Types of High Winds
Type Description
Straight-line
winds
Used to describe any thunderstorm wind that is not associated with rotation and is used mainly to differentiate from tornadic winds.

Downdraft Is a small-scale column of air that rapidly sinks toward the ground.

Macroburst An outward burst of strong winds at or near the surface with horizontal dimensions larger than 4 km and occurs when a strong downdraft reaches the surface.

Microburst
A small, concentrated downburst that produces an outward burst of strong winds at or near the surface.

There are small and short-lived, lasting only 5-10 minutes, with maximum speeds sometimes exceeding 100 miles per hour.

Downburst
Used to broadly describe macro and microbursts. It is a general term for all localized strong wind events that are caused by a strong downdraft within a thunderstorm while microburst simply refers to a small downburst that is less than 4 km across.

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.

Derecho
A widespread, long-lived storm that is associated with a band of rapidly moving showers or thunderstorms.

A typical derecho event consists of numerous microbursts, downbursts, and downburst clusters. A derecho event is classified when damage extends more than 240 miles and includes wind gusts of at least 58 miles per hour.

Source: NOAA

The Beaufort Wind Scale was one of the first scales to estimate wind speed and effects. It was originally developed to help sailors estimate the winds via visual observations. The scale starts with 0 and goes to a force of 12. The Beaufort scale is still used today to estimate wind strengths shown in the table below. Table 50. Beaufort Wind Scale outlines the Beaufort scale, describing the damaging effects of wind speed.

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Table 50. Beaufort Wind Scale
Wind Speed (mph) Description-Visible Condition
0 Calm: smoke rises vertically
1-4 Light air; direction of wind shown by smoke but not by wind vanes 4-7 Light breeze: wind felt on face; leaves rustle; ordinary wind vane moved by wind 8-12 Gentle breeze; leaves and small twigs in constant motion; wind extends light flag 13-18 Moderate breeze; raises dust and loose paper; small branches are moved 19-24 Fresh breeze: small trees in leaf begin to sway; crested wavelets form on inland water 25-31 Strong breeze; large branches in motion; telephone wires whistle; umbrellas used with difficulty
32-38 Moderate gale whole trees in motion; inconvenience in walking against wind 39-46 Fresh gale breaks twigs off trees; generally, impedes progress 47-54 Strong gale slight structural damage occurs; chimney pots and slates removed 55-63 Whole gale trees uprooted; considerable structural damage occurs 64-72 Storm very rarely experienced; accompanied by widespread damage 73+ Hurricane devastation occurs
Source: NOAA

Fresno County is at risk of experiencing events in any of these categories.

PAST OCCURRENCES
Heavy rains and severe storms occur in the Fresno County planning area primarily during the late fall, winter, and spring, but have been documented in every month of the year. According to the Fresno County General Plan Background Report, the majority of precipitation is produced by storms during the winter months. Precipitation during the summer months is in the form of convective rain showers and is rare. Fresno County receives about 10 inches of rain per year. Snowstorms, hailstorms, and ice storms occur infrequently in the San Joaquin Valley and severe occurrences of any of these are very rare.

Damaging winds often accompany winter storm systems moving through the area. Although summer winds are a frequent occurrence, with afternoon winds of 10 to 20 mph being common, it is the winds experienced during the winter storms that result in the most wind-related damage.

According to the HMPC, short-term, heavy storms can cause both widespread flooding as well as extensive localized drainage issues. With the increased growth of the area, the lack of adequate drainage systems has become more of an issue. In addition to the flooding that often occurs during these storms, strong winds, when combined with saturated ground conditions, can down very mature trees.

Information from the three representative weather stations introduced in Section 4.2.13 Severe Weather: General is summarized below and in Figure 41. Mammoth Lakes Daily Averages:

Precipitation, Figure 42. Central (Fresno WSO AP Weather Station, Period of Record 1948 to 2024), and Figure 43. West (Coalinga Weather Station, Period of Record 1942 to 2023).

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Source: Western Regional Climate Center, www.wrcc.dri.edu/ Figure 44. Mammoth Lakes Daily Averages: Precipitation

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Source: Western Regional Climate Center, www.wrcc.dri.edu/

Figure 45. Central (Fresno WSO AP Weather Station, Period of Record 1948 to 2024)

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Source: Western Regional Climate Center, www.wrcc.dri.edu/

Figure 46. West (Coalinga Weather Station, Period of Record 1942 to 2023)

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SEVERE WEATHER EVENTS
Also related to severe weather is the issue of dust storms caused by blowing dust during high wind events. Like foggy conditions, blowing dust can cause extreme visibility problems resulting in traffic accidents. Given the agricultural nature of much of the planning area, recently plowed fields can create the potential for blowing dust and debris. A list of severe weather events is provided in Table 51.

Fresno County Past Occurrences: Severe Weather. A list of high wind event is mapped in Figure

44. Fresno County Historic Wind Events and detailed in Table 52. Fresno County Previous Occurrences: High Wind. The following tables describe other severe weather specific events in Table

53. Fresno County Past Occurrences: Thunderstorm Wind, Table 54. Fresno County Past Occurrences: Hailstorm, Table 55. Fresno County Past Occurrences: Lightning Storm, and Table

56. Fresno County Past Occurrences: Heavy Rain. The HMPC provided the following information:

▪ 11/29/1991: The day after Thanksgiving, furious winds stoked a huge dust storm on Interstate 5 in western Fresno County, reducing visibility to zero and causing multiple traffic collisions. At least 164 vehicles were involved in 33 collisions clustered along a two- mile segment of the highway. A total of 349 people were involved in the collisions; 17 were killed and 151 were injured. ▪ 4/14/2009: California experienced a sequence of weather events starting with an upper-level ridge on April 11th -12th, followed by a mostly dry system on the 13th. This transition led to a cold front on April 14th, causing strong winds and dust storms in the San Joaquin Valley, particularly affecting Coalinga, and Avenal with near-zero visibility. Wind gusts reached 41 mph in Bakersfield and 35 mph in Fresno, closely approaching April wind records. The dust storms led to a traffic collision on Interstate 5 due to poor visibility, resulting in several injuries but no fatalities. Winds persisted into April 15th, spreading to Merced and Atwater, with a notable gust of 40 mph in Fresno on April 16th.

The event concluded with minimal rainfall, highlighting the dry conditions of the period. ▪ 4/14/2015: An upper-level trough of low pressure moved onshore on April 14th resulting in wind gusts of 45-60 MPH. An area of dust and dirt was lifted into the atmosphere, reducing visibility to near zero across Highway 180 near Fresno. The reduced visibility led to a seven- car crash causing minor injuries and the closure of the roadway for a few hours. Blowing dust reduced visibility to nearly zero along Highway 180, near Fresno, causing two multi-car accidents. ▪ 2/17/2017: A series of strong low-pressure systems accompanied with tropical moisture influxes brought strong winds, heavy rainfall, flooding, debris flows, funnel cloud reports, and high elevation snows to the central California region. Precipitation was enhanced at times by orographically lifting. ▪ 4/06/2017: A low pressure center moved into northern California on the 6th and spread precipitation into central California by late afternoon. This system brought a period of cool, windy, and unsettled conditions to the area which continued through the 8th. There were several reports of 10-20 inches of new snow over the Southern Sierra Nevada above 8000 feet while thunderstorms during the afternoon of April 8 produced heavy rainfall in some areas. There were numerous reports of heavy rainfall over the Southern Sierra Nevada and adjacent foothills where 2 to 4 inches of rain fell.

There were also strong winds across much of the area during this event with several locations reporting wind gusts above 50 mph.
▪ 11/26/2017: A swift-moving upper trough brought rain to central California and snow to higher elevations starting late on November 26, with a cold front intensifying the precipitation the following morning. The Southern Sierra Nevada received up to an inch of rain, while the San Joaquin Valley saw lighter rainfall; snow levels, initially high, dropped to 4000 feet post-frontal, resulting in modest snow accumulation. The system’s most pronounced effect was the robust winds it generated across

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the southern Sierra Nevada, Tehachapi Mountains, and Kern County deserts from the evening of November 26 through the next day’s early afternoon.
▪ 12/16/2017: An upper trough that had very little moisture with it dropped southeast out of the Gulf of Alaska and pushed into northern California on December 15. This system pushed through central California on the morning of December 16 pushing a cold front through the region. Strong post- frontal winds developed in the San Joaquin Valley behind the front by late morning and continued well into the afternoon hours before the winds diminished by evening. Several stations in the San Joaquin Valley measured peak wind gusts between 35 mph and 55 mph. ▪ 11/29/2018: A strong upper trough reached California's coast on November 28, bringing significant rainfall that triggered mudslides, particularly in the burn scar areas, and forced the closure of Highway 140. On November 29, as the system advanced inland, it delivered intense precipitation, with 2 to 5 inches in the Southern Sierra Nevada and foothills, and snowfall accumulating up to 3 feet above 5500 feet. Accompanying the system were strong winds, with gusts surpassing 55 mph, and post-frontal thunderstorms that produced localized heavy showers and gusty winds until the weather system exited the region early on November 30.
▪ 12/28/2018: A dry shortwave dropped southward just to the east of the Sierra crest as an upper trough deepened over the Desert Southwest during the morning of December 28. Meanwhile, an upper ridge pushed inland into northern California setting up a period of strong offshore Mono type winds along the crest of the Southern Sierra Nevada. This resulted in a closure of the China Peak ski resort as winds gusted around 55 mph at the top of the lifts. Meanwhile the center of the San Joaquin Valley was sheltered form the winds and clear skies overnight some locally dense fog formed and impacted traffic along State Route 99.
▪ 12/31/2018: A strong shortwave trough dropped down through the Great Basin during the morning of December 31. With high pressure pushing inland into northern California behind the trough, offshore Mono type winds developed over the higher elevations of the southern Sierra Nevada which down sloped into the foothills. This resulted in several drought weakened trees being knocked down in the foothills near North Fork and Oakhurst where locally strong wind gusts exceeding 60 mph were reported.
▪ 1/06/2019: The second of a series of winter storms moved through central California from the afternoon of January 6 through the early morning of January 7. While this storm produced another round of rain and higher elevation snow across the area with many locations in the southern Sierra Nevada picking up between 1 to 2 inches of liquid precipitation, the main impact from this storm was strong winds were most noticed across the San Joaquin Valley where several trees and power lines were blown down or knocked over.
▪ 1/17/2019: As a potent low-pressure system surged into central California on January 16, it delivered not only moderate to heavy precipitation but also spawned strong winds, with several reports of gusts over 50 mph in the Kern County Mountains and Deserts. The storm prompted flash flooding, notably in the Ferguson Fire burn area of Mariposa County and produced a tornado east of Clovis rated as EF-1. While the San Joaquin Valley and Kern County Deserts received up to an inch of rain, the Southern Sierra Nevada saw 2 to 4 inches of liquid precipitation, predominantly as snow above 7000 feet, with some locations accumulating 10 to 20 inches. ▪ 2/02/2019: As a potent upper low-pressure system neared the central California coast on the morning of February 2, it generated strong southerly winds that disrupted the Grapevine area and extended into Bakersfield, causing downed trees and damage. The ensuing inland movement of the low ushered in moderate to heavy precipitation, triggering numerous flooding events and thunderstorms that produced hail and a brief tornado south of Mariposa. The San Joaquin Valley

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received over an inch of rain, while mountain areas accumulated 2 to 5 inches of liquid precipitation, with the higher elevations above 5000 feet experiencing significant snowfall. ▪ 2/13/2019: A low-pressure system brought a surge of moisture to central California on February 13 and 14, unleashing heavy rain and strong winds, with gusts over 60 mph and snow levels rising to nearly 9000 feet, causing widespread flooding and multiple road closures due to flooding and debris flows. A subsequent cold front on February 15 drastically lowered snow levels to 5000 feet, sparking thunderstorms with small hail in the San Joaquin Valley and an EF0 tornado near Yosemite Lakes. The ensuing days saw snow levels drop to 1500 feet, resulting in significant snowfall accumulation and travel disruptions across the Southern Sierra Nevada, with total rainfall reaching up to 7 inches in higher elevations.
▪ 3/06/2019: A potent upper low-pressure system brought intense winds and heavy rains to central California on March 5, causing extensive damage. Gusts escalated as a strong southwest upper jet streamed overhead, leading to widespread flooding and the evacuation of several communities due to a potential levee breach near Lake Isabella. The storm's forceful winds, alongside substantial rainfall, prompted road closures and thunderstorms, further exacerbating the severe weather conditions and infrastructure disruptions.
▪ 3/19/2019: Strong southerly winds developed over the area during the evening of March 19 as a low-pressure system deepened off the California coast and interacted with an amplifying inland ridge. Several locations along the west side of the San Joaquin Valley and in the Kern County Mountains reported wind gusts exceeding 40 mph during the evening. The winds diminished overnight as cooler air settled in over the area.
▪ 11/26/2019: A cold low-pressure system from the Gulf of Alaska reached the Pacific Northwest on November 26, bringing widespread precipitation to central California through November 28, affecting Thanksgiving travel with road closures due to snow. Snow levels dropped to 2000-2500 feet, leading to 5-10 inches of snow in the southern Sierra foothills and 3-8 inches in the Kern County Deserts, while the higher Sierra regions accumulated 18-36 inches. The San Joaquin Valley received a quarter to half an inch of rain, with localized heavier falls from thunderstorms, and significant closures occurred on Interstate 5 and State Route 58 due to snow and accidents. ▪ 12/22/2019: A frontal system crossing central California on December 22 and 23 generated strong winds, especially in the Fort Tejon area and Bakersfield, where gusts surpassed 50 mph and some locations near Lebec experienced gusts over 75 mph, causing minor damage. After the winds eased on December 22, the region received widespread rain, with the Sierra Nevada and foothills accumulating 1 to 1.5 inches of precipitation, and higher elevations above 5000 feet gaining 10 to 15 inches of snow. The San Joaquin Valley recorded lower rainfall amounts due to rain shadowing, with most places receiving a quarter to half an inch.
▪ 1/16/2020: A cold front connected to an upper trough swept through California on January 16, bringing 6 to 8 hours of precipitation, and depositing a quarter to a full inch of rain across the San Joaquin Valley and adjacent areas, with higher elevations above 4000 feet receiving 5 to 14 inches of snow. Strong winds followed, especially in the southern San Joaquin Valley and Kern County Mountains and Deserts, where gusts surpassed 40 mph and some areas experienced brief gusts over 70 mph, causing minor wind damage. The intense conditions eased by the morning of January 17 as the system moved on.
▪ 2/09/2020: A upper-level low pressure system dropped southward along the crest of the Sierra Nevada on the evening of February 8 and morning of February 9 then strengthened over southern California during the afternoon of February 9 through the morning of February 10. This system produced a very strong offshore gradient which resulted in damaging northeast winds over the

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Sierra Nevada, mainly over Yosemite Park and Sierra National Forest as well as over the adjacent foothills. The winds knocked down many droughts killed trees over the Sierra and produced widespread property damage over the Sierra foothills in Madera County. There were also several reports of wind gusts between 60 and 70 mph over the Kern County Mountains and Deserts between the evening of February 8 and morning of February 10. ▪ 3/01/2020: A cold upper low-pressure system moved south off the California coast on March 1, causing mountain showers and dropping snow levels to 3000 feet, with up to four inches of snow accumulating in areas like Pine Mountain Club. Northeast winds gusted between 35 and 45 mph in the Sierra Nevada, with a peak gust of 83 mph reported near North Fork, while the Kern County Deserts experienced northerly gusts over 60 mph. The gusty conditions persisted until the evening of March 2 before diminishing.
▪ 12/28/2020: A low pressure system moving along the central California coast brought significant precipitation and snowfall to the region on December 27-28, with the Sierra Nevada receiving up to three-quarters of an inch of rain and high-elevation areas accumulating several inches of snow. The Tehachapi Mountains also experienced snowfall and precipitation, leading to paced travel and chain restrictions on major routes like Interstate 5 and State Route 168. Gusty winds accompanied the storm, with some areas recording wind gusts exceeding 50 mph. ▪ 1/18/2021: A low-pressure system off Southern California's coast and a secondary low moving through Nevada produced destructive northeast winds, with gusts over 60 mph, damaging structures and causing extended power outages in the Sierra foothills. The winds, which also caused the loss of ancient sequoias and necessitated major power line repairs in Mariposa County, prompted disaster declarations. By January 20, the winds subsided as the low pressure moved southward away from the coast.
▪ 1/27/2021: A very potent storm system swept through central California, causing heavy rainfall, flooding, and strong winds, with gusts over 45 mph and peak winds reaching 60 mph in the Fort Tejon and West Side Hills areas. This led to power outages and additional trees downed, especially in the Sierra Nevada which had recently experienced a severe wind event. The storm generated heavy precipitation throughout the region, with up to 7 inches of rain in the Sierra foothills and 4 inches in the San Joaquin Valley, while the mountains received 4 to 6 feet of snow, disrupting travel, and closing roads until the system exited on January 29. ▪ 10/11/2021: A deep upper low-pressure system dropped from the Pacific Northwest into the Great Basin during the morning of October 11. This resulted in a period of strong winds from the late morning hours until the evening as a very strong pressure gradient developed. Several stations reported wind gusts exceeding 58 mph with the strongest winds most noticeable on the Mojave Desert Slopes of the Tehachapi Mountains. A few low impact indicator sites reported gusts exceeding 80 mph. The winds diminished by the morning of October 12 as the low moved east of the Great Basin and pressure gradients relaxed.
▪ 10/17/2021: A strong cold front pushed through central California from the evening of October 17 through the early morning of October 18 as a low-pressure system dropped southward through the Great Basin. While this system did bring some light precipitation to the Sierra Nevada with several stations measuring 1 to 3 tenths of an inch of liquid precipitation and 1 to 3 inches of new snowfall above 6000 feet, the main impact from this system was a period of gusty winds across the West Side Hills as well as across the Kern County Mountains. Several stations reported wind gusts exceeding 45 mph with a few low impact indicator sites measuring gusts exceeding 60 mph. ▪ 10/25/2021: A significant upper-level low from the Gulf of Alaska, fueled by Typhoon Namtheun's remnants, brought intense moisture and heavy precipitation to Central California, with areas north

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of Kern County receiving up to 5 inches of rain and snow levels dropping to 6000 feet by October 25 evening. The storm also generated high winds, with gusts hitting 58 to 70 mph, and fostered scattered thunderstorms, one of which formed a funnel cloud in southwestern Kings County. This system concluded with snow accumulations of 9 to 30 inches in the higher elevations and rainfall tapering off late on October 25, with diminished winds by the next morning. ▪ 12/13/2021: A strong low-pressure system from the Gulf of Alaska brought heavy moisture to central California, resulting in 2 to 4 inches of rain in the Sierra Nevada and significant snowfall above 5500 feet. The system also caused substantial snowfall, with high-elevation SNOTELs recording 2 to 4 feet of new snow, and snow levels dropping to 1500 feet in some areas.

Accompanying the precipitation were strong winds, particularly over the West Side Hills and through the Grapevine and Tehachapi areas of Kern County, with gusts surpassing 50 mph and some exceeding 70 mph.
▪ 3/27/2022: An upper low-pressure system off the southern California coast brought strong winds, with gusts over 45 mph in the West Side Hills and Tehachapi Mountains. Precipitation followed, yielding a quarter to half an inch of rain in the San Joaquin Valley and foothills, and 0.40 to 0.80 inches in the Sierra Nevada, where elevations above 5500 feet saw 3 to 8 inches of new snow.

Thunderstorms developed in the afternoon but moved quickly, preventing significant flooding. ▪ 11/08/2022: A deep upper low-pressure system from the Gulf of Alaska introduced widespread precipitation to central California, with the Sierra Nevada receiving 2-4 inches of rain and 20-30 inches of snow above 6000 feet. Strong southerly winds were prominent in Kern County's higher elevations on November 8, with gusts surpassing 50 mph, and some areas experiencing over 75 mph. These conditions led to power outages across the San Joaquin Valley and Sierra foothills, attributed to wind damage, accidents on wet roads, and thunderstorms. ▪ 12/31/2022: A large trough brought tropical moisture to California, causing moderate to heavy precipitation and flooding, with the Sierra Nevada receiving up to 7 inches of rain. Strong winds also affected the region, particularly the West Side Hills and Tehachapi Mountains, where gusts surpassed 60 mph. Additionally, higher elevations saw substantial snow accumulation, with SNOTEL stations recording 18 to 30 inches, adding to the already heavy snowpack from earlier in December.
▪ 1/04/2023: A significant low-pressure system with an atmospheric river caused moderate to heavy precipitation and strong winds, leading to widespread flooding and snow levels between 7000 to 8000 feet. High elevation areas received up to 30 inches of snow, while the Sierra Nevada and foothills saw up to 3 inches of rain, exacerbating the effects of previously saturated soils.

Additionally, the system generated intense winds, with gusts over 60 mph in the Kern County Mountains and West Side Hills, resulting in numerous reports of wind damage. ▪ 1/07/2023: A low-pressure system traversed northern California, delivering light to moderate precipitation and strong wind gusts, with some areas experiencing gusts over 60 mph. Precipitation varied, with the Sierra Nevada near Yosemite Park receiving up to an inch of rain and the San Joaquin Valley getting up to half an inch, while Kern County saw less than a tenth of an inch. The snow level dropped to around 5000 feet, leading to significant snow accumulation of 5 to 10 inches at higher elevations.
▪ 1/09/2023: A strong low-pressure system brought intense precipitation and high winds to central California, with the Sierra Nevada receiving 3 to 6 inches of rain, exacerbating runoff from existing snowpack and causing extensive flooding, including the inundation of Planada and a record flood at Bear Creek. Strong downslope winds, exceeding 60 mph in areas like the Tehachapi Mountains and Sierra foothills, led to power outages and fallen power lines. The storm system moved east by

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January 11, with winds abating, but the significant rainfall resulted in continued flooding from the accumulated runoff.
▪ 1/16/2023: Following the January 14 storm, another system on January 15-16 unleashed less rainfall but more destructive winds, with gusts over 40 mph in the San Joaquin Valley and Sierra foothills, and over 60 mph in the Tehachapi Mountains and West Side Hills. These strong winds caused widespread power outages and toppled trees, leading to road closures. The storm's impact lingered with slow subsiding precipitation, not fully clearing until January 17. ▪ 2/21/2023: A cold upper trough pushed into central California between the afternoon of February 21 and the early morning of February 22. A cold front associated with this trough produced strong winds throughout much of the area. Several stations in the wind prone areas of the West Side Hills and in the Mountains and Deserts of Kern County measured gusts exceeding 60 mph with a few low impact indicator stations reporting gusts above 80 mph. There were also several reports of downed trees in the San Joaquin Valley.
▪ 2/24/2023: On February 24 and 25, a cold upper low-pressure system near California's coast generated powerful winds, as snow levels plunged to 1500 feet, resulting in 2 to 4 feet of snow at higher elevations and subsequent road closures. The San Joaquin Valley and lower Sierra foothills faced both flooding and wind-related disruptions. As the system advanced across southern California on the evening of February 25, it continued to produce strong winds before moving eastward by the morning of February 26.
▪ 3/14/2023: Following the recent events which produced widespread flooding across the central California Interior, another atmospheric river plunged through the region on March 14 and 15 producing heavy precipitation, flooding and strong winds with several stations measuring gusts exceeding 60 mph. Much of the Sierra Nevada picked up another 3 to 6 inches of liquid precipitation with snow levels above 8500 feet while the adjacent foothills picked up 2 to 4 inches of rainfall while the San Joaquin Valley and West Side Hills generally picked up between 0.5 to 1.5 inches of rainfall.
▪ 3/21/2023: A strong upper trough passed through, bringing intense winds that exceeded 60 mph across the West Side Hills, Sierra Nevada, and Kern County Mountains and Deserts. The Sierra Nevada experienced heavy snowfall, with high elevation SNOTEL stations recording 18 to 30 inches, while the San Joaquin Valley received additional rain on saturated ground. Thunderstorm outflow winds also caused tree damage in and around Fresno on March 21.

Table 51. Fresno County Past Occurrences: Severe Weather Date Location Magnitude
(mph) Fatality Injury Property
Loss Crop Loss
3/04/1954 Fresno 0 0 0 $0 $0
7/28/1958 Fresno 0 0 0 $0 $0
7/28/1958 Unincorporated 0 0 0 $0 $0
5/29/1984 Fresno 0 0 0 $0 $0
5/30/1994 Fresno 0 1 0 $0 $0
5/01/1995 Unincorporated 0 0 0 $500,000 $0
5/01/1995 Unincorporated 0 0 0 $500,000 $0
5/13/1995 Unincorporated 0 0 0 $0 $0
6/15/1995 Unincorporated 0 0 0 $500,000 $0

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Date Location Magnitude
(mph) Fatality Injury Property
Loss Crop Loss
10/30/1996 Unincorporated 0 0 0 $10,000 $0
2/14/1998 Fresno 57.5 0 0 $0 $0
2/23/1998 Fresno 0 0 0 $100,000 $0
4/20/2001 Fresno 57.5 0 0 $0 $0
5/31/2002 Unincorporated 0 0 0 $50,000 $0
5/31/2002 Unincorporated 0 0 0 $50,000 $0
7/21/2006 Unincorporated 69 0 0 $0 $0
10/29/2007 Fresno 57.5 0 0 $30,000 $0
10/29/2007 Fresno 57.5 0 0 $50,000 $0
10/29/2007 Fresno 57.5 0 0 $10,000 $0
1/27/2008 Unincorporated 64.4 0 0 $50,000 $0
3/15/2008 Mendota 57.5 0 0 $10,000 $0
5/28/2009 Fresno 57.5 0 0 $0 $0
5/28/2009 Reedley 57.5 0 0 $0 $0
5/28/2009 Sanger 57.5 0 0 $0 $0
5/28/2009 Unincorporated 57.5 0 0 $60,000 $0
5/28/2009 Unincorporated 57.5 0 0 $0 $0
6/05/2009 Unincorporated 59.8 0 0 $0 $0
6/05/2009 Unincorporated 59.8 0 0 $0 $0
2/28/2014 Unincorporated 64.4 0 0 $500,000 $0
2/17/2017 Fresno, Clovis,
Visalia 57 0 0 0 0
4/06/2017 Fresno, Clovis,
Visalia 73 0 0 0 0
11/26/2017
Auberry,
Prather,
Shaver Lake
52 0 0 0 0
12/16/2017 Fresno, Clovis,
Visalia 51 0 0 0 0
11/29/2018 Fresno, Clovis,
Visalia 55 0 0 0 0
12/28/2018
South Sierra
Mountains
Zone
58 0 0 0 0
12/31/2018
Auberry,
Prather,
Shaver Lake
59 0 0 0 0
1/06/2019
Fresno,
Sanger,
Reedley
53 0 0 0 0
1/17/2019
South Sierra
Mountains
Zone
57 0 0 0 0

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Date Location Magnitude
(mph) Fatality Injury Property
Loss Crop Loss
2/02/2019
South Sierra
Mountains
Zone
52 0 0 0 0
2/13/2019
South Sierra
Mountains
Zone
51 0 0 0 0
3/06/2019 Fresno, Clovis,
Visalia 56 0 0 0 0
3/19/2019 Fresno, Clovis,
Visalia 56 0 0 0 0
11/26/2019
Firebaugh,
Coalinga,
Mendota
56 0 0 0 0
12/22/2019
Firebaugh,
Coalinga,
Mendota
53 0 0 0 0
1/16/2020
Shaver Lake,
Huntington
Lake,
Lakeshore
51 0 0 0 0
2/09/2020 Auberry,
Shaver Lakes 81 0 0 22,000 0
3/01/2020 Auberry,
Shaver Lakes 72 0 0 0 0
12/28/2020
Coalinga,
Mendota,
Firebaugh
55 0 0 0 0
1/18/2021
Shaver Lake,
Huntington
Lake,
Lakeshore
87 0 0 200,002,000 0
1/27/2021 Auberry,
Shaver Lakes 56 0 0 0 0
10/11/2021 Coalinga,
Avenal 53 0 0 0 0
10/17/2021
West Side
Mountains
North of
Highway 198
(Zone)
55 0 0 0 0
10/25/2021
Friant,
Auberry,
Shaver Lake
58 0 0 0 0
12/13/2021
West Side
Mountains
South of
Highway 198
(Zone)
54 0 0 0 0
3/27/2022
West Side
Mountains
North of
52 0 0 0 0

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Date Location Magnitude
(mph) Fatality Injury Property
Loss Crop Loss
Highway 198
(Zone)
11/08/2022
West Side
Mountains
South of
Highway 198
(Zone)
52 0 0 0 0
12/31/2022
West Side
Mountains
South of
Highway 198
(Zone)
54 0 0 0 0
1/04/2023
West Side
Mountains
North of
Highway 198
(Zone)
51 0 0 0 0
1/07/2023
West Side
Mountains
North of
Highway 198
(Zone)
57 0 0 0 0
1/09/2023
West Side
Mountains
North of
Highway 198
(Zone)
50 0 0 0 0
1/16/2023
West Side
Mountains
South of
Highway 198
(Zone)
63 0 0 0 0
2/21/2023 Coalinga,
Avenal 54 0 0 0 0
2/24/2023
West Side
Mountains
North of
Highway 198
(Zone)
52 0 0 0 0
3/14/2023
West Side
Mountains
North of
Highway 198
(Zone)
56 0 0 0 0
3/21/2023
West Side
Mountains
South of
Highway 198
(Zone)
52 0 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

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Source: CA Geoportal: CA-DFW; CalTrans; County of Fresno – GIS; NOAA – National Weather Service, Storm Prediction Center, SVRGIS; NOAA – National Centers for Environmental Info.

Figure 47. Fresno County Historic Wind Events

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STRONG WIND EVENTS
▪ 2/01/2017: A weak cold frontal passage brought breezy to gusty winds for parts of the San Joaquin Valley and caused minor damage.
▪ 3/05/2017: A cold upper trough delivered widespread rain, with 0.75 to 1.5 inches in the Southern Sierra Nevada and adjacent foothills, and 6 to 12 inches of snow above 6000 feet. The San Joaquin Valley received less than a quarter of an inch of rain due to rain shadowing. Post-frontal gusty winds affected the Kern County Mountains and Deserts, with gusts exceeding 45 mph reported on the afternoon and evening of March 5.
▪ 3/30/2017: A upper-level trough moved southeast along the Sierra Nevada range on the day of the 30th. Upper-level northwest flow helped increase the surface wind as the pressure gradient at the surface tightened. This resulted in strong and gusty winds across most of the area. Several reports of wind gusts above 40 mph were reported in the San Joaquin Valley while several reports of winds gusts above 50 mph were reported in the Kern County Mountains and Deserts while some indicator ridge tops had gusts exceeding 90 mph. The strong winds produced blowing dust across portions of the southern San Joaquin Valley and Kern County Deserts. In addition, there were several reports of downed trees and power lines which resulted power outages across parts of the San Joaquin Valley.
▪ 12/04/2017: A large upper ridge built into the Pacific Northwest on December 4 behind a trough which pushed through California the previous day. This resulted in a strong gradient over the southern Sierra Nevada producing Mono type winds over the Southern Sierra Nevada on the evening of December 4 through the late morning of December 5. ▪ 1/09/2018: Central California experienced a series of low-pressure systems, with the most significant arriving between January 8 and 9, bringing heavy rain and strong winds, including a peak gust of 94 mph at Grapevine Peak. This system resulted in street flooding in Bakersfield, mudslides in Kern County, and snowfall above 5500 feet. By the morning of January 10, the precipitation had ceased, but dense fog affected visibility and traffic across the San Joaquin Valley and nearby highways.
▪ 5/11/2018: High pressure built over Central California on May 3 and kept warm temperatures, dry conditions, and generally light winds over the area. However, an upper-level low pressure system moved into the Pacific Northwest on May 10 then dropped into the Great Basin on May 11. This resulted in increased surface pressure gradients which produced strong winds over portions of the area during the afternoon of May 11. There were a few reports of minor wind damage in the San Joaquin Valley and some low impact indicator stations in the Kern County Mountains and Deserts reported winds gusts exceeding 70 mph.
▪ 10/14/2018: A low pressure system moved into southern California on October 13 and moved slowly inland on October 14. While the precipitation with this system mainly stayed to the south of our area, it interacted with an upper ridge that was building into the Pacific Northwest to produce a strong offshore gradient over central California which resulted in a brief period of strong mono-type northeast winds over the Southern Sierra Nevada during the late evening of October 14 and the early morning of October 15. Several dead trees were blown down near North Fork and Bass Lake in Madera County resulting in some brief road closures and some damage to a few structures. ▪ 12/31/2018: A strong shortwave trough dropped down through the Great Basin during the morning of December 31. With high pressure pushing inland into northern California behind the trough, offshore Mono type winds developed over the higher elevations of the southern Sierra Nevada which down sloped into the foothills. This resulted in several drought weakened trees being

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knocked down in the foothills near North Fork and Oakhurst where locally strong wind gusts exceeding 60 mph were reported.
▪ 1/06/2019: The second of a series of winter storms moved through central California from the afternoon of January 6 through the early morning of January 7. While this storm produced another round of rain and higher elevation snow across the area with many locations in the southern Sierra Nevada picking up between 1 to 2 inches of liquid precipitation, the main impact from this storm was strong winds were most noticed across the San Joaquin Valley where several trees and power lines were blown down or knocked over.
▪ 1/17/2019: A strong low-pressure system delivered moderate to heavy rain and strong winds to central California, leading to flash flooding and roadway closures, especially in the Ferguson Fire burn area. The storm system caused a tornado rated EF-1 east of Clovis on January 17, and the Southern Sierra Nevada received 2 to 4 inches of rain, translating to 10 to 20 inches of snow above 7000 feet. Additionally, post-frontal wind gusts in the Kern County Mountains and Deserts exceeded 50 mph, with some areas experiencing gusts over 65 mph. ▪ 1/20/2019: A strong cold front swept through central California on January 20-21, causing moderate to heavy precipitation and strong wind gusts. The San Joaquin Valley experienced widespread wind damage, with gusts over 35 mph, while gusts in the Kern County Mountains and Deserts reached up to 90 mph. The Southern Sierra Nevada received up to 1.5 inches of rain and 5 to 10 inches of snow above 7000 feet before the system exited the region by the evening of January 21. ▪ 2/02/2019: A strong southerly winds ahead of an upper low-pressure system caused damage in the Grapevine and Bakersfield areas, with reports of downed trees and wind damage. The system brought moderate to heavy rain and thunderstorms to the San Joaquin Valley and southern Sierra foothills, with over an inch of rain in the valley and 2 to 5 inches in the mountains, and a brief tornado near Mariposa. Above 5000 feet, heavy snowfall accumulated, adding to the snow from another storm on February 4 and 5.
▪ 4/09/2019: a strong low-pressure system entered the Pacific Northwest and moved southeast, bringing a cold front that caused strong wind gusts across the San Joaquin Valley, Lake Isabella, and Tehachapi areas. These gusts, exceeding 40 mph in the valley and 60 mph in the mountain areas, led to several power outages due to downed lines. Some locations even reported gusts surpassing 70 mph, underscoring the system's strength despite limited moisture affecting central California.
▪ 11/29/2019: The cold low-pressure system which brought widespread rain and lower elevations snow during the previous two days moved east of the area on November 29, but brisk northwest winds behind the departing system produced several gusts exceeding 40 mph in the Kern County Mountains and Deserts. A few low impact indicator sites measured gusts exceeding 60 mph. ▪ 2/02/2020: The cold front which moved into the area during the morning of February 2 brought strong winds to the area by late afternoon as pressure gradients increased. Winds gusts exceeding 40 mph were reported in the San Joaquin Valley and several gusts exceeding 60 mph were reported across the Kern County Mountains and Deserts with a few low impact indicator sites measuring gusts above 80 mph. The winds downed several trees and power poles and flipped over two big rigs near Mojave during the evening. The winds decreased during the morning of February 3 as pressure gradients diminished.
▪ 2/08/2020: An upper-level low pressure system moved along the Sierra Nevada on February 8-9 and strengthened over southern California, causing damaging northeast winds. These winds downed drought-stricken trees in Yosemite Park and the Sierra National Forest, causing

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widespread property damage, especially in Madera County's foothills. Gusts between 60 and 70 mph were also reported in the Kern County Mountains and Deserts during this period. ▪ 1/18/2021: An upper low off the southern California coast and a secondary system from Nevada generated destructive northeast winds across the Sierra Nevada, with gusts over 60 mph causing extensive damage and power outages. The severe winds led to disaster declarations in Mariposa and Madera Counties, with over 30 miles of power lines replaced in Mariposa County and fifteen ancient giant sequoias felled. The winds, which also affected the Tehachapi Mountains and the San Joaquin Valley with gusts over 50 mph, subsided by the morning of January 20 as the low moved towards the Baja coast.
▪ 5/20/2021: A cold low-pressure system brought strong winds, with gusts over 60 mph in Kern County and up to 90 mph in certain areas, prompting road closures. As the system moved on the following day, it left behind a cool airmass and instability that resulted in rain and snow showers over the Sierra Nevada. The precipitation was mostly light, but areas above 6000 feet received up to 2 inches of new snow.
▪ 6/22/2022: Tropical Storm Celia's moisture, coupled with a hot, unstable airmass over central California, triggered scattered thunderstorms on June 22, ending a two-month dry spell. These storms varied in intensity but generally brought one to two tenths of an inch of rain to the San Joaquin Valley and more to the Tehachapi Mountains and southern Sierra. Strong outflow winds and dry microbursts from the storms caused damage, downing several trees and power lines. ▪ 12/31/2022: A trough with tropical moisture caused moderate to heavy precipitation and significant flooding in California, with reports of road closures due to debris flows. Strong winds with gusts over 60 mph affected the West Side Hills and Tehachapi Mountains, while the Sierra Nevada and foothills received substantial rainfall, contributing to an already heavy snowpack from earlier storms.

The San Joaquin Valley and Tehachapi Mountains received less rain due to rain shadow effects. ▪ 1/04/2023: An intense low-pressure system with an atmospheric river brought heavy precipitation and strong winds to the area, leading to flooding and heavy snowfall above 8000 feet. The San Joaquin Valley experienced significant rainfall, exacerbating the flooding from previously saturated soils. The system's powerful winds, surpassing 60 mph in places, caused widespread wind damage.
▪ 1/07/2023: A low pressure system passed through northern California from January 7 to 8, bringing light to moderate precipitation and wind gusts exceeding 60 mph in some areas. The Sierra Nevada near Yosemite received up to an inch of rain and 5 to 10 inches of snow at higher elevations, while the San Joaquin Valley saw up to a half inch of rain. Despite being less intense than the previous storm, the system still affected the region with notable wind and precipitation. ▪ 1/09/2023: A powerful low-pressure system unleashed strong winds exceeding 60 mph in the Tehachapi Mountains, West Side Hills, and Sierra foothills of central California, leading to extensive power outages as lines were downed. The tropical moisture within the system also produced significant rain, contributing to widespread flooding, but the most disruptive force was the wind, which caused the evacuation of towns like Planada and a record flood along Bear Creek. Though the precipitation ceased, and the winds subsided by January 11, the impact of the winds, alongside the heavy rains, left a lasting imprint with ongoing flooding and damage control. ▪ 1/16/2023: Following the storm on January 14, a subsequent system on January 15-16 brought less rain but caused damaging wind gusts in the San Joaquin Valley and the Sierra foothills, with gusts over 60 mph in the Tehachapi Mountains. These winds led to power outages and road closures from fallen trees and power lines, compounding the flooding from already saturated grounds. The storm's effects lingered until January 17, although winds diminished by the afternoon of January 16.

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▪ 2/21/2023: A cold upper trough pushed into central California between the afternoon of February 21 and the early morning of February 22. A cold front associated with this trough produced strong winds throughout much of the area. Several stations in the wind prone areas of the West Side Hills and in the Mountains and Deserts of Kern County measured gusts exceeding 60 mph with a few low impact indicator stations reporting gusts above 80 mph. There were also several reports of downed trees in the San Joaquin Valley.
▪ 8/20/2023: Moisture from Hurricane Hillary prompted thunderstorms and significant outflow winds in the San Joaquin Valley on August 19, and as the storm weakened, it brought 3 to over 5.5 inches of rain to Kern County's mountains and deserts on August 20. The southern Sierra Nevada received 1 to 3 inches of rain, setting new daily rainfall records. Flash flooding and road closures followed, with conditions stabilizing as the moisture dissipated and an offshore trough moved northeast by August

22. Table 52. Fresno County Previous Occurrences: High Wind Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Fresno,
Coalinga,
Mendota
02/01/2017 30 1000 0 0 0
Shaver Lake,
Squaw Valley,
Auberry
03/05/2017 26 0 0 1 0
Fresno,
Sanger,
Reedley
03/30/2017 43 200000 0 0 0
Auberry,
Shaver Lake,
Prather
12/04/2017 43 100000 0 0 0
Shaver Lake,
Squaw Valley,
Auberry
01/09/2018 43 1000 0 0 0
Fresno,
Coalinga,
Mendota
05/11/2018 30 1000 0 0 0
Auberry,
Shaver Lake,
Prather
10/14/2018 39 10000 0 0 0
Auberry,
Shaver Lake,
Prather
12/31/2018 43 1000 0 0 0
Fresno,
Sanger,
Reedley
1/06/2019 39 1000 0 0 0
Auberry,
Shaver Lake,
Prather
1/17/2019 35 1000 0 0 0
Fresno,
Sanger,
Reedley
1/20/2019 39 5000 0 0 0

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Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Auberry,
Shaver Lake,
Prather
2/02/2019 43 5000 0 0 0
Fresno 4/09/2019 35 1000 0 0 0
Sequoia Kings
Zone 11/29/2019 43 100000 0 0 0
Fresno,
Kerman,
Mendota
2/02/2020 39 5000 0 0 0
Shaver Lake,
Auberry,
Tollhouse
2/08/2020 43 5000 0 0 0
Shaver Lake,
Auberry,
Tollhouse
1/18/2021 43 1000 0 0 0
Foggy Bottom
Zone 5/20/2021 26 1500 0 0 0
Fresno,
Clovis 6/22/2022 48 10000 0 0 0
Los Banos,
Dos Palos 12/31/2022 35 1000 0 0 0
Merced,
Madera,
Mendota
1/04/2023 35 1000 0 0 0
Fresno,
Clovis 1/07/2023 30 1000 0 0 0
Visalia,
Porterville,
Reedley
1/09/2023 30 1000 0 0 0
Fresno,
Clovis 1/16/2023 43 50000 0 0 0
Fresno,
Clovis 2/21/2023 35 1000 0 0 0
Merced,
Madera,
Mendota
8/20/2023 30 1000 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

THUNDERSTORM WIND EVENTS
▪ 9/11/2017: A stationary upper low off the California coast drew tropical moisture into central California, triggering a severe thunderstorm outbreak on September 11 with downburst winds over 60 mph, causing damage to structures and knocking down power lines. Rainfall was light, with most areas receiving less than a quarter inch, but parts of the Southern Sierra Nevada and Tehachapi Mountains saw up to half an inch.

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▪ 5/19/2019: A strong low-pressure system delivered heavy rainfall to central California, breaking several daily records, and depositing 8 to 14 inches of snow above 6000 feet in the Sierra Nevada.

The unstable weather also sparked thunderstorms in the San Joaquin Valley, leading to reports of small hail, heavy rain, and a small EF0 tornado with accompanying wind damage near Huron. ▪ 6/29/2021: A strong high-pressure center over the Pacific Northwest pulled in moisture from the east which produced thunderstorms over the Sierra Nevada during the afternoon of June 29.

Although the thunderstorms on the previous day were mainly dry with very little rainfall, the moisture surge the following day was deeper and as a result some of the thunderstorms produced locally heavy rainfall, damaging outflow winds and small hail during the afternoon and early evening hours of June 29.
▪ 6/22/2022: Moisture from Tropical Storm Celia combined with a hot, unstable airmass over central California, triggering scattered showers and thunderstorms on June 22, marking the region's first significant rain in two months. Rainfall varied due to the storms' convective nature, with the San Joaquin Valley receiving up to two-tenths of an inch, while the Tehachapi Mountains and southern Sierra saw up to three-quarters of an inch. Some storms generated strong winds and dry microbursts, toppling trees and power lines.
▪ 2/05/2023: A strong low-pressure system swept through northern to central California, dropping

0.75 to 1.5 inches of rain and reducing snow levels to 4000 feet, leaving 9 to 15 inches of snow above 6500 feet in the Sierra Nevada. Strong wind gusts hit the Mohave Desert, and the system’s unstable conditions led to scattered thunderstorms in the San Joaquin Valley, causing wind damage and hail. The weather affected travel, pacing traffic on Interstate 5, and accumulating light snow across the Tejon Pass.
▪ 3/12/2023: Following the departure of the warm and moist storm which produced widespread flooding across the area on March 9 and 10, another moist system moved through central California on March 11 and 12. While precipitation amounts were generally much lower with this system with most of the Sierra Nevada picking up between 1 and 2 inches of liquid precipitation and adjacent foothills picking up between a half inch and an inch of rainfall, the cooler unstable airmass on the back side of this system produced afternoon and evening thunderstorms across the lower elevations resulting in widespread flooding and wind damage across the San Joaquin Valley. ▪ 3/21/2023: A strong upper trough moved across the region on March 21 and 22. This system produced strong winds across the West Side Hills, the Sierra Nevada and across the Kern County Mountains and Deserts where several stations measured gusts exceeding 60 mph. In addition, heavy snow fell in the Sierra Nevada where several high elevation SNOTEL stations picked up between 18 and 30 inches of new snow while liquid precipitation totals were generally between 1 and 2 inches. Much of the San Joaquin Valley picked up between a quarter and three quarters of an inch of additional rainfall over an already saturated ground while thunderstorm outflow winds knocked down several trees in and around Fresno during the afternoon of March 21. ▪ 8/19/2023: Hurricane Hillary's moisture caused showers and thunderstorms with notable outflow winds in the San Joaquin Valley on August 19, and as it weakened, it brought 3 to over 5.5 inches of rain to Kern County on August 20. The Sierra Nevada south of Kings Canyon and the southern San Joaquin Valley received 1 to 3 inches and a half inch to an inch of rain, respectively, with new daily records set in the northern areas. Flash flooding and road closures followed in Kern County, but by August 22, an offshore trough moved the moisture out, leading to drier conditions for the rest of the week.

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Table 53. Fresno County Past Occurrences: Thunderstorm Wind Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Caruthers 9/11/2017 61 120,000 0 0 0
Huron 5/19/2019 52 75,000 25000 0 0
Pine Logging
Camp 6/29/2021 52 0 0
0 0
Friant 6/22/2022 60 0 0 0 0
Wahtoke 2/05/2023 35 1000 0 0 0
Monmouth 3/12/2023 35 1000 0 0 0
Highway City 3/21/2023 40 25000 0 0 0
Sunnyside 8/19/2023 48 50000 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

HAILSTORM EVENTS
▪ 5/19/2019: An upper-level low brought heavy rain to central California, breaking daily records, and delivering 0.75 to 2 inches of precipitation, with snowfall of 8 to 14 inches above 6000 feet in the Sierra Nevada. The following day, thunderstorms caused small hail, heavy rain, and an EF0 tornado with some wind damage near Huron.
▪ 3/11/2023: After a storm caused extensive flooding on March 9 and 10, another system passed through central California on March 11 and 12, bringing less precipitation, with the Sierra Nevada receiving 1 to 2 inches and foothills about half an inch to an inch. However, afternoon and evening thunderstorms in the cool, unstable air mass led to widespread flooding and wind damage across the San Joaquin Valley.

Table 54. Fresno County Past Occurrences: Hailstorm
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Westhaven 5/19/2019 0.5 0 1 M 0 0
Ingle 3/11/2023 1 0 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

LIGHTNING STORM EVENTS
▪ 7/30/2021: Subtropical moisture continued to stream into central California on July 30. Once again, afternoon thunderstorms developed over the Sierra Nevada. One thunderstorm produced a fatal lightning strike over the Sierra Nevada during the early afternoon. ▪ 8/12/2023: An upper-level low pressure system which contained the remnant moisture from former Tropical Storm Eugene was situated off the California coast on August 12. This moisture helped fuel scattered thunderstorms during the afternoon and evening hours over the Sierra Nevada. A

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lightning strike from one of the thunderstorms downed a large tree and started a small fire near Shaver Lake during the evening.

Table 55. Fresno County Past Occurrences: Lightning Storm Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Mono Hot
Springs 7/30/2021 0 0 0 1 0
Shaver Lake
Heights 8/12/2023 0 1,000 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

HEAVY RAINSTORM EVENTS
▪ 1/12/2017: A series of systems fed by a continued influx of very moist air was pushed into the central California interior through an atmospheric river set-up for several days prior and a colder low-pressure system moved into central California. This created thunderstorms that produced heavy rainfall for parts of the San Joaquin Valley. Reports of road ponding/flooding were reported along with a few reports of funnel clouds.
▪ 1/21/2017: A nearly stationary cold low-pressure system from the Pacific Northwest moved into central California and tropical moisture being fed from the Pacific with a continued atmospheric river set-up, brought thunderstorms and heavy rainfall to the Sierra Nevada Mountains and Foothills and parts of the San Joaquin Valley over several days. Small pea-sized hail was also reported with some thunderstorms.
▪ 2/03/2017: Tropical influx jet pushed into central California ahead of a cold front created heavy rains which were enhanced by orographically lifting with the Sierra Mountains. ▪ 4/13/2017: a large low-pressure system moved through central California, generating strong wind gusts and moderate rainfall, with the San Joaquin Valley experiencing winds over 35 mph and the Kern County Mountains and Deserts over 45 mph. Merced and Mariposa Counties and Yosemite National Park received up to half an inch of rain. Fresno was hit by a nearly stationary thunderstorm that set a record for April rainfall since the 1880s with 2.04 inches at the airport. Thunderstorm outflow also caused blowing dust and reduced visibility, leading to vehicular accidents near Lemoore.
▪ 11/17/2017: A strong upper trough pushed through the Pacific Northwest on November 16 and 17.

A fetch of deep moisture of tropical origin was pulled up ahead of this trough and brought moderate to heavy precipitation to Merced and Mariposa Counties as well as to Yosemite National Park.

Several locations in Yosemite National Park measured between 2 and 4 inches of rainfall while several mountain and foothill stations in Madera, Fresno and Tulare Counties picked up over an inch of rain. Snow was basically confined to elevations above 8000 feet as a warm airmass prevailed over the region. Several SNOTELs above 9000 feet did pick up between 1 and 2 feet of fresh snowfall as this was the first significant storm of the season at the higher elevations. ▪ 3/21/2018: A tropical air mass brought heavy rain to central California, causing widespread flooding, road closures due to rockslides and debris flows, particularly in burn scar areas around Mariposa and Springville. Thunderstorms on March 22 led to flash flooding and funnel clouds, prompting a

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Flash Flood Emergency in western Mariposa County, including building floods and evacuations. A tornado was also reported near Dinuba in Tulare County. The Southern Sierra Nevada received 4 to 8 inches of rain, while the San Joaquin Valley recorded 1 to 3 inches, with several feet of snow above 9000 feet.
▪ 9/04/2018: A low pressure system centered over southern Nevada provided for a shallow surge of mid-level moisture into central California on September 3 and 4. During the afternoon of the 4th, several thunderstorms developed over the higher elevations of the Southern Sierra Nevada from Yosemite National Park southward to the Lake Isabella area where the atmosphere was unstable.

Heavy rainfall was produced by thunderstorms near Kings Canyon and near Lake Isabella which over an inch of rainfall between 100 pm PDT and 5 pm PDT. In addition, isolated thunderstorms brought some light rainfall to the southern Sierra foothills and to the Kern County Deserts. ▪ 5/18/2019: An upper-level low pressure system entered central California, delivering between 0.75 and 2 inches of rain, and setting new daily records. Above 6000 feet, the Sierra Nevada received 8 to 14 inches of fresh snow. On May 19, thunderstorms in the San Joaquin Valley caused small hail and heavy rainfall, and an EF0 tornado along with wind damage was reported near Huron. ▪ 12/01/2019: A large upper low-pressure system brought moderate to heavy rain to central California, mainly north of Fresno County, with 1 to 3 inches of rainfall. The Sierra Nevada and the central San Joaquin Valley were significantly impacted, while snow levels over the Southern Sierra Nevada dropped to 7000 feet, resulting in 6 to 12 inches of new snow. Less rain fell further south, with up to half an inch. This weather caused nuisance flooding and a multi-vehicle accident on State Route 99 north of Fresno.
▪ 12/08/2019: An upper trough brought widespread precipitation to California, with the heaviest in the northern regions where the Sierra recorded 1 to 2 inches and the valley got up to an inch of rain.

Southern areas saw less, with Kings and Tulare Counties receiving up to half an inch, and Kern County less than a quarter inch. Snow levels stayed between 7000 and 8000 feet, with the higher Sierra getting 8 to 12 inches of new snow. The event also included scattered thunderstorms that led to local heavy rain, roadway flooding, and small hail before the precipitation ceased by the evening of December 8 as the trough moved east.
▪ 10/08/2021: A Pacific cold frontal system pushed through the area during the morning of October 8 spreading widespread precipitation across the area. Several stations in the eastern portion of the San Joaquin Valley and the Sierra Nevada range measured between a tenth and four tenths of an inch of rainfall with portions of Fresno and Madera Counties picking up locally heavy showers which produced higher precipitation amounts. Several high elevation SNOTELs picked up an estimated one to three inches of new snowfall. The precipitation ended by late afternoon as the storm moved east of the area.
▪ 2/24/2023: A cold low-pressure system off California's coast brought 1.5 to 3 inches of rain and significant snowfall, with snow levels dropping to near 1000 feet. Higher elevations in the Sierra Nevada and adjacent areas received 2 to 4 feet of snow, leading to extended closures of mountain roads. Flooding in the San Joaquin Valley and lower Sierra foothills caused additional road closures. The system moved out of the area by the morning of February 26.

Table 56. Fresno County Past Occurrences: Heavy Rain
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Glorietta 1/12/2017 0 0 0 0 0

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Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Melvin 1/21/2017 0 0 0 0 0
Glorietta 2/03/2017 0 0 0 0 0
(FAT) Air
Terminal 4/13/2017 0 0 0 0 0
Clovis 11/17/2017 0 0 0 0 0
Melvin 3/21/2018 0 0 0 0 0
Cedar Grove 9/04/2018 0 0 0 0 0
Fresno 5/18/2019 0 0 15M 0 0
Herndon 12/01/2019 0 50,000 0 0 0
Clovis 12/08/2019 0 0 0 0 0
Melvin 10/08/2021 0 0 0 0 0
Melvin 2/24/2023 0 0 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

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LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Heavy rain, thunderstorms, hail, lightning, and wind are well-documented seasonal occurrences that will continue to occur annually in the Fresno County planning area.

CLIMATE CHANGE CONSIDERATIONS
Atmospheric Rivers - Atmospheric rivers account for up to 50 percent of California’s total annual precipitation. Climate change can drive conditions to be conducive to an increase and greater intensity of atmospheric rivers due to warmer temperatures. Additional moisture from atmospheric rivers could increase the frequency of thunderstorms and severe storms to occur.

Heavy Rain - California’s variable precipitation is also characterized by multi-year wet or dry periods.

Future average precipitation is difficult to predict and unlikely to change substantially when focusing on annual precipitation. Even if heavy rain were to increase in future decades, it is likely that warmer air temperatures will increase moisture loss from soils and lead to drier seasonal conditions. 44 Hail - According to some scientists, it is predicted that severe convective storms are becoming more likely in our warming climate. Storms with the right mixture of atmospheric ingredients for hail are more likely to form. Because the planet is getting warmer, the odds are generally higher that a hailstone will melt before making its way to the ground. However, the hailstones that do make it down may be larger and cause more damage. 45Overall, the future probability of hail events occurring in the future is unlikely unless significant changes in the atmosphere increase the chance of hail events impacting the planning area.

Lightning - On a large scale, lightning strikes nationwide are projected to increase by 12 percent per every degree Celsius of global warning and about 50 percent over the 21st century if greenhouse gases increase at their current pace. However, so far scientists have not yet seen an increase in lightning events. When looking at the past 25 years, there hasn’t been a noticeable increase in global lightening or U.S. lightning. 46In future decades, it is uncertain if lightning events will increase or decrease in frequency within the planning area.

44 Summary of Projected Climate Change Impacts on California - California Climate Adaptation Strategy https://climateresilience.ca.gov/overview/impacts.html
45 Severe Hailstorms Are Costly and Hard to Predict - Eos https://eos.org/articles/severe-hailstorms-are-costly-and-hard-to- predict
Severe Hailstorms Are Costly and Hard to Predict - Eos https://eos.org/articles/severe-hailstorms-are-costly-and-hard-to- predict
46 Lightning could spark more California fires as world warms - CalMatters https://calmatters.org/environment/2021/09/california-fires-lightning/

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SEVERE WEATHER: WINTER STORM

HAZARD/PROBLEM DESCRIPTION
Winter snowstorms can include heavy snow, ice, and blizzard conditions. Heavy snow can immobilize a region, stranding commuters, stopping the flow of supplies, and disrupting emergency and medical services. Accumulations of snow can collapse roofs and knock down trees and power lines. In rural areas, homes and farms may be isolated for days, and unprotected livestock may be lost. The cost of snow removal, damage repair, and business losses can have a tremendous impact on cities and towns.

Winter weather can vary by types including blizzards, ice storms, snow squalls, heavy snow, and sleet or freezing rain, described in more detail below:

Winter Weather Types
▪ Blizzards: defined by the National Weather Service, blizzards are a combination of sustained winds or frequent gusts of 35 mph or greater and visibilities of less than a quarter mile from falling or blowing snow for 3 hours or more. A blizzard, by definition, does not indicate heavy amounts of snow, although they can happen together. The falling or blowing snow usually creates large drifts from the strong winds. The reduced visibilities make travel, even on foot, particularly treacherous.

The strong winds may also support dangerous wind chills. Ground blizzards can develop when strong winds lift snow off the ground and severely reduce visibilities. ▪ Ice Storm: occurs when a layer of warm (above freezing), moist air aloft coincides with a shallow cold (below freezing) pool of air at the surface. As snow falls into the warm layer of air, it melts to rain, and then freezes on contact when hitting the frozen ground or cold objects at the surface, creating a smooth layer of ice. This phenomenon is called freezing rain. Similarly, sleet occurs when the rain in the warm layer subsequently freezes into pellets while falling through a cold layer of air at or near the Earth’s surface. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least .25 inch of ice on exposed surfaces. Extended periods of freezing rain can lead to accumulations of ice on roadways, walkways, power lines, trees, and buildings. Almost any accumulation can make driving and walking hazardous. Ice accumulations can lead to downed trees, utility poles and communication towers. Ice can disrupt communications and power while utility companies repair significant damage. Even small accumulations of ice can be extremely dangerous to motorists and pedestrians. Bridges and overpasses are particularly dangerous because they freeze before other surfaces. ▪ Snow Squalls: often associated with strong cold fronts, are a key wintertime weather hazard. They move in and out quickly, and typically last less than an hour. The sudden white-out conditions combined with falling temperatures produce icy roads in just a few minutes. Squalls can occur where there is no large-scale winter storm in progress and might only produce minor accumulations. Snow squalls can cause localized extreme impacts to the traveling public and to commerce for brief periods of time. Unfortunately, there is a long history of deadly traffic accidents associated with snow squalls. Although snow accumulations are typically an inch or less, the added combination of gusty winds, falling temperatures and quick reductions in visibility can cause extremely dangerous conditions for motorists.
▪ Heavy Snow: in large quantities, may fall during winter storms. Six inches or more in 12 hours or eight inches or more in 24 hours constitute conditions that may significantly hamper travel or create hazardous conditions. The National Weather Service issues warnings for such events. Smaller amounts can also make travel hazardous, but in most cases, only results in minor inconveniences.

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Heavy wet snow before the leaves falls from the trees in the fall or after the trees have leafed out in the spring may cause problems with broken tree branches and power outages. ▪ Sleet or Freezing Rain: sleet is defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. Heavy sleet is a relatively rare event, defined as ice pellets covering the ground to a depth of a one- half inch or more. Freezing rain falls as a liquid but freezes into glaze upon contact with the ground.

Heavy accumulations of ice can bring down trees, electrical wires, telephone poles and lines, and communication towers. Communications and power can be disrupted for days until the damage can be repaired. Even small accumulations of ice may cause extreme hazards to motorists and pedestrians.

Some winter storms are accompanied by strong winds, creating blizzard conditions with blinding wind- driven snow, severe drifting, and dangerous wind chills. Strong winds with these intense storms and cold fronts can knock down trees, utility poles, and power lines. Blowing snow can reduce visibilities to only a few feet in areas where there are no trees or buildings. Serious vehicle accidents can result in and cause injuries and deaths.

The central and western portions of the Fresno County planning area generally do not experience snowfall on a seasonal basis; however, the higher elevations in the eastern portion of the County receive an abundance of snow, mostly between the months of November through April. Winter snowstorms in this part of the County, including strong winds and blizzard conditions, can result in localized power and phone outages and closures of streets, highways, schools, business, and nonessential government operations. People can also become isolated from essential services in their homes and vehicles. Snow removal costs can impact budgets significantly. Heavy snowfall during winter can also lead to flooding or landslides during the spring if the area snowpack melts too quickly.

EXTENT
The extent of winter storms and cold that cause issues in Fresno County includes storms forecasted to be Winter Storm Warnings, Wind Chill Warnings or Blizzard Warnings. These storms would be confined to the Sierra Mountains within Fresno County. Heavy snows, or a combination of snow, freezing rain or extreme wind chill due to strong wind, may bring widespread or lengthy road closures and hazardous travel conditions, plus threaten temporary loss of community services such as power and water. Deep snow and additional strong wind chill or frostbite may be a threat to even the appropriately dressed individual or to even the strongest person exposed to the frigid weather for only a short period.

Depending on the magnitude of the winter storm, the National Weather Service will issue either a Winter Weather Advisory, Winter Storm Watch, or a Winter Storm Warning, shown in the table below.

Table 57. NWS Winter Storm Weather Product
Winter Storm Product Description
Winter Weather Advisory
(Light Purple)
Wintry weather expected. Light amounts of wintry precipitation or patchy amounts of wintry precipitation or patchy blowing snow will cause slick conditions and could affect travel if precautions are not taken.

Winter Storm Watch
(Light Blue)
Snow, sleet, or ice possible. Confidence is medium that a winter storm could produce heavy snow, sleet, or freezing rain and cause significant impacts.

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Winter Storm Product Description
Winter Storm Warning
(Pink)
Snow, sleet, or ice expected. Confidence is high that a winter storm will produce heavy snow, slight, or freezing rain and cause significant impacts.

Source: NWS

PAST OCCURRENCES
Information from the three representative weather stations introduced in the Severe Weather: General section is summarized below. There was no mean monthly snow fall for the central and eastern weather stations across the county. Figure 45. Mammoth Lake Mean Monthly Snow (1993-2022) shows the monthly mean snow fall in inches for the Mammoth Lake Weather Station.

Source: Western Regional Climate Center, www.wrcc.dri.edu/

The Fresno County Office of Emergency Services is not aware of any incidents where snow caused enough damage to declare a countywide emergency. The following winter snow event impacted the eastern portion of the Fresno County planning area shown in Table 58. Fresno County Past Occurrences: Snow and listed below.

▪ January 2005: Heavy wet snow fell in eastern Fresno County above 4,000 feet resulting in a regionwide closure of roads and loss of power for up to three weeks in three communities. Eight injuries were reported due to vehicle accidents from poor road conditions. Property damage was estimated at $3.5 million from trees falling on homes, cabins, and outbuildings. Infrastructure damage was estimated at $2.5 million to the power distribution grid and $250,000 to the road system. An estimated 10-15,000 merchantable trees were damaged or destroyed. Most roads in the area were closed for three weeks; schools were closed for two weeks.

33.8 37.5

27.8 14.4

4.1 0.3 0 0 0

5.1 12.4

38.8 0
5 10
15 20
25 30
35 40
45 MAMMOTH LAKE - MEAN MONTHLY
SNOW FALL IN INCHES (1993 -2022)
Figure 48. Mammoth Lake Mean Monthly Snow (1993-2022)

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▪ 3/24/2011: The last major storm of the month arrived on March 24th. This storm brought gusts to 45 mph to the west side of the San Joaquin Valley, and gusts to 65 mph in the Kern County mountains and deserts. Convective activity was limited to near Merced, with several reports of road flooding due to the already saturated ground. Thunderstorms and showers moved east into the foothills of Madera and Mariposa Counties, where the heavy rains triggered rock and mud slides. Mainly light showers occurred southward. The trough moved east of the region on the 25th, with residual light showers in its wake. Additionally, light snow fell in the Southern Sierra Nevada measuring around 5 inches or less. Local media reported that the roof of a vacant store at Shaver Lake collapsed on March 26th due to 6 feet of snow accumulation on the roof. ▪ 4/12/2012: An upper-level short-wave moved into California on April 10th, flattening the ridge. This set the stage for back-to-back strong storms to move through the central California interior on the 11th, 12th, and 13th. Each storm triggered severe thunderstorms over the central and southern San Joaquin Valley with hail up to 1.75 inches in diameter. Tallies of agricultural and crop loss approached 100 million dollars due to the extensive hail damage across Kings, Tulare, Fresno, and Merced counties. Funnel clouds were observed, although none touched down. The first storm brought up to a foot of snow to the Southern Sierra Nevada, and the second colder storm dropped up to 30 inches of snow at Lodgepole in Sequoia National Park. ▪ 2/18/2019: Showers and winds diminished across the area during the evening of February 17 as skies cleared out. This resulted in the freezing of leftover rain and melted snow on several roads which resulted in several roads in the Kern County Mountains being closed for several hours overnight and into the morning hours of February 18. Black ice also resulted in a fatal two vehicle accident near Oakhurst on State Route 49 during the morning of February 18. ▪ 1/09/2023: Central California was struck by a low-pressure system that swept in with a tropical moisture surge, causing widespread heavy precipitation and record-breaking flooding. The snow levels at about 7500 feet led to significant runoff, exacerbating the flooding that shut down numerous roads and necessitated evacuations, including the entire inundated town of Planada.

Additionally, the storm caused power outages due to high winds, with a record 26.2-foot crest at Bear Creek, before diminishing on January 11.

Table 58. Fresno County Past Occurrences: Snow
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Eastern Fresno
County January 2005 0 3.5 M 0 0 8
Fresno County 3/24/2011 0 0 0 0 0
Fresno County 4/10/2012 0 0 100 M 0 0
Oakhurst 2/18/2019 0 80,000 0 0 0
Planada 1/09/2023 0 8,900,000 0 0 0
Source: NOAA, National Centers for Environmental Information, Storm Events Database

LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Snow in the eastern region of the County is a well-documented seasonal occurrence that will continue to occur annually.

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CLIMATE CHANGE CONSIDERATIONS
Historically, California has relied heavily on the Sierra Nevada snowpack. Runoff from melting mountain snow is captured and distributed throughout the state via an extensive network of aqueducts.

Observations over recent warmer decades reveal a decline in California’s lower elevation snowpack, and climate models indicate considerably greater loss of mountain snowpack as temperatures continue to warm. Overall, precipitation will fall as rain instead of snow. However, snow that does manage to accumulate will melt earlier in the spring. As spring snowpack decreases in the future decades, the state’s water storage capacity will be reduced as well. Researchers found that winters are becoming increasing shorter in the mountainous western United States, as snow is disappearing earlier in the year. By 2050, the average water supply from snowpack is projected to decline to two-thirds of historical levels, some studies project. If greenhouse gas emissions do not reduce, water from snowpack could fall less than one-third of historical levels by the year 2100.47 47 https://scripps.ucsd.edu/research/climate-change-resources/faq-climate-change-california

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SEVERE WEATHER: TORNADO

HAZARD/PROBLEM DESCRIPTION
Tornadoes are another severe weather hazard that can affect the Fresno County planning area, primarily during the rainy season. Tornadoes form when cool, dry air sits on top of warm, moist air.

Tornadoes are rotating columns of air marked by a funnel-shaped downward extension of a cumulonimbus cloud whirling at destructive speeds of up to 300 mph, usually accompanying a thunderstorm. Tornadoes are the most powerful storms that exist. They can have the same pressure differential that fuels 300-mile-wide hurricanes across a path only 300-yards wide or less. With additional heat in the atmosphere storms are projected to become more severe in the future, and thus lightning may become more prevalent. Tornadoes typically occur during the “tornado season” from April through June. Tornadoes usually occur in the spring and summer months, however the tornadoes that have occurred in the planning area and in neighboring communities have occurred in the spring but also in the winter months (December and January). Tornadoes can last from several seconds to more than an hour as they are rolling through communities. However, most tornadoes usually last less than 10 minutes. Typically, tornadoes will gradually lose intensity as the condensation funnel decreases in size, the tornado becomes tilted with height before it completely dissipates.

The size of the tornado does not necessarily equate to the severity of the tornado. Occasionally, small tornadoes can do major damage and some very large tornadoes, over a quarter-mile wide, have produced only light damage. The measure of the magnitude and intensity of a Tornado, the Enhanced Fujita Scale or EF Scale, which became operational in 2007, is used to categorize tornadoes based on estimated wind speeds and related damage, shown in Table 59. Fujita Scale and Table 60. Enhanced Fujita Scale. The EF scale is based off wind estimates (not measurements) from the relevant damage.

The scale uses three-second gusts estimated at the point of damage. Additionally, the National Weather Service is the only federal agency with authority to provide an “official” tornado EF Scale rating.

Table 59. Fujita Scale
Fujita (F) Scale Fujita Scale Wind
Estimate (mph) Typical Damage
F0 < 73
Light damage. Some damage to chimneys; branches
broken off trees; shallow- rooted trees pushed over; sign boards damaged.

F1 73-112
Moderate damage. Peels surface off roofs; mobile
homes pushed off foundations or overturned; moving
autos blown off roads.

F2 113-157
Considerable damage. Roofs torn off frame houses;
mobile homes demolished; boxcars overturned; large
trees snapped or uprooted; light-object missiles
generated; cars lifted off ground.

F3 158-206
Severe damage. Roofs and some walls torn off well-
constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and
thrown.

F4 207-260
Devastating damage. Well-constructed houses leveled;
structures with weak foundations blown away some
distance; cars thrown and large missiles generated.

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Fujita (F) Scale Fujita Scale Wind
Estimate (mph) Typical Damage
F5 261-318
Incredible damage. Strong frame houses leveled off
foundations and swept away; automobile-sized missiles
fly through the air in excess of 100 meters (109 yards); trees debarked; incredible phenomena will occur.

Source: National Oceanic and Atmospheric Administration Storm Prediction Center, www.spc.noaa.gov/faq/tornado/f-scale.html

Table 60. Enhanced Fujita Scale
Enhanced Fujita (EF) Scale Enhanced Fujita Scale Wind Estimate (mph) EF0 65-85
EF1 86-110
EF2 111-135
EF3 136-165
EF4 166-200
EF5 Over 200
Source: National Oceanic and Atmospheric Administration Storm Prediction Center, www.spc.noaa.gov/faq/tornado/ef-scale.html

Tornadoes can cause damage to property and loss of life. While most tornado damage is caused by violent winds, most injuries and deaths result from flying debris. Property damage can include damage to buildings, fallen trees and power lines, broken gas lines, broken sewer and water mains, and the outbreak of fires. Agricultural crops and industries may also be damaged or destroyed. Access roads and streets may be blocked by debris, delaying necessary emergency response.

EXTENT
The majority of tornadoes in the past in Fresno County have been F0 and F1. Large tornadoes are possible, however. Should the County be hit by an EF-4 or EF-5 tornado, it can be extrapolated that because of its relative size and the potential size and length of a tornado’s path a significant portion of the County could be impacted, resulting in property and crop damage and loss of life.

PAST OCCURRENCES
Based on data from 1950 to1995, California ranks 32nd among the 50 states for frequency of tornadoes, 36th for injuries, and 31st for cost of damage. When compared to other states by frequency per square mile, California ranks 44th for frequency and injuries per area and 40th for cost of damage

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per area. Figure 46. Fresno County Historic Tornado Events shows tornadoes that have affected the County using NOAA data from 1950 to 2022.

Source: CA Geoportal; CA-DFW; CalTrans; County of Fresno – GIS; NOAA – National Weather Service, Storm Prediction Center, SVRGIS; NOAA – National Centers for Environmental Info.

Figure 49. Fresno County Historic Tornado Events

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According to the HMPC, during the rainy season, the Fresno County planning area is prone to relatively strong thunderstorms, sometimes accompanied by funnel clouds and tornadoes. While tornadoes do occur occasionally, most often they are of F0 or F1 intensity. Documented incidents of tornadoes in the Fresno County planning area from the NCEI Storm Events Database are listed in Table 61. Fresno County Past Occurrences: Tornadoes and Table 62. Recent Fresno County Past Occurrences by City: Tornado.

Table 61. Fresno County Past Occurrences: Tornadoes
Type # of Events Property Loss
($) Deaths Injuries
Tornado: F0 20 250,000 0 0
Tornado: F1 9 5,705,050 0 3
Tornado: F2 1 5,000 0 0
Totals 30 5,960,050 0 3
Source: NOAA, National Centers for Environmental Information, Storm Events Database

A summary of the most recent tornadoes is described below.

▪ 2/12/2018 - Warm temperatures were followed by a low-pressure system that led to strong winds in the Kern County area. This weather system also resulted in a weak tornado touching down near Sanger on the morning of February 12th.
▪ 1/16/2019 - Intense storms brought heavy rain and strong winds to central California, leading to an EF-1 tornado east of Clovis, alongside significant snowfall above 7000 feet in the Southern Sierra Nevada. The storm affecting the region on January 16 and 17, also caused extensive roadway flooding and forced the closure of State Route 140 due to flash flooding and debris flows. ▪ 3/02/2019 - A Pacific storm system brought moderate to heavy precipitation to central California, culminating in thunderstorms that led to a tornado near Mendota causing minor roof damage. The Southern Sierra Nevada received 1 to 3 inches of rain, while snow levels, initially above 8000 feet, dropped to around 5000 feet after the cold front. The storm passed by March 3rd. ▪ 5/18/2019 - An intense low-pressure system led to record-breaking rainfall in central California with significant snowfall in the Sierra Nevada. The system also sparked thunderstorms across the San Joaquin Valley, producing small hail, heavy rain, and an EF0 tornado near Huron.

Table 62. Recent Fresno County Past Occurrences by City: Tornado Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Parlier 2/12/2018 EF0 0 0 0 0
Academy 1/17/2019 EF1 500,000 0 0 0
Mendota 3/02/2019 EF0 20,000 0 0 0
Huron 5/18/2019 EF0 0 0 0 0

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Source: NOAA, National Centers for Environmental Information, Storm Events Database

LIKELIHOOD OF FUTURE OCCURRENCES
Possible—Thirty tornadoes have occurred in Fresno County over 73 years of record keeping, which equates to one tornado every 2.4 years, on average, and a 40 percent chance of a tornado occurring in any given year. Historical tornadic activity within the planning area indicates that the area will likely continue to experience the formation of funnel clouds and low intensity tornadoes during adverse weather conditions. The actual risk to the County is dependent on the nature and location of any given tornado.

CLIMATE CHANGE CONSIDERATIONS
The total number of U.S. tornadoes observed each year roughly doubled from the 1950s to the 1990s with the advent of more storm spotters and chasers. Most of these “extra” tornadoes were on the weak side that were not originally detected prior. Climate change typically plays out through broad regional shifts, such as depleted sea ice, warmer oceans, and drier landscapes. Sometimes these shifts are distinct enough from natural variation to signal clearly that human-caused climate change is likely involved. In contrast, tornadoes are brief and episodic, and they normally vary a great deal over time and space, so it’s difficult to distill long-term trends in their behavior and distinguish those from normal ups and downs. 48Therefore, scientists must attempt to predict how climate change might affect the individual weather “ingredients” that support the development of supercell thunderstorms. The weather ingredients include warm, moist air, an unstable atmosphere, and wind at different levels moving in different directions at different speeds, a phenomenon known as wind shear. As global temperatures increase, the hotter atmosphere is able to hold more moisture. This increases atmospheric instability, an important supercell ingredient. On the other hand, as the earth warms, wind shear is likely to decrease.

Some studies predict that climate change could provide the opportunity for more severe thunderstorms to form. However, this does not necessarily mean that more tornadoes will occur, especially in light of the fact that only about 20 percent of supercell thunderstorms produce tornadoes. While there have been no long-term trends in the frequency of tornadoes, there have been changes in tornado patterns in recent years. Research has shown that there are fewer days with at least one tornado but more days with over thirty, even as the total number of tornadoes per year has remained relatively stable. In other words, tornado events are becoming more clustered. There is speculation that some of these changes are linked to climate change and its effect on the jet stream. Tornado outbreaks have also coincided with rising ocean temperatures. But no one can say for certain that climate change is a contributing factor in these events. 49

48 https://yaleclimateconnections.org/2021/07/climate-change-and-tornadoes-any-connection/ 49 https://education.nationalgeographic.org/resource/tornadoes-and-climate-change/

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VOLCANO

HAZARD/PROBLEM DESCRIPTION
Of the almost 70 active and potentially active volcanoes in the United States, more than 50 have erupted one or more times in the past 200 years. Volcanic eruptions occur in the state about as frequently as the largest San Andreas Fault Zone earthquakes; at least ten eruptions have occurred in California in the last 1,000 years and the likelihood of renewed volcanism in the state is on the order of 1 in a few 100 to 1 in a few thousand annually. Volcano hazards are the greatest in five western states:

Alaska, Hawaii, California, Oregon, and Washington. Volcanoes create a wide variety of hazards that can kill people and destroy property. 50
Populations living near volcanoes are most vulnerable to volcanic eruptions and lava flows; although, large explosive eruptions can endanger people and property hundreds of miles away and even affect global climate. Volcanic ash can also travel and affect populations many miles away. The ash from the 1980 eruption of Mount St. Helens in Washington fell over a large area of the western United States.

Heavy ash fall can collapse buildings, and even minor ash fall can damage crops, electronics, and machinery. Some volcanic hazards, such as landslides, can occur even when a volcano is not erupting.

Figure 47. Components of a Volcanic Eruption depicts a volcano typical of those found in the western United States.

50 California State Hazard Mitigation Plan

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Source: National Park Service

The State of California Multi-Hazard Mitigation Plan identifies volcanoes as one of the hazards that can adversely impact the state. However, there have been few losses in California from volcanic eruptions.

Of the approximately 20 volcanoes in the state, only a few are active and pose a threat. According to the USGS California Volcano Observatory, there are six volcanos that pose a high risk and 4 volcanos that pose a moderate risk to the state of California. The six volcanoes include Mount Shasta, Medicine Lake Volcano, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, and Salton Buttes. The volcanoes that pose a moderate risk include Soda Lakes, Long Valley Volcanic Region, Ubehebe Craters, Coso Volcanic Field.

EXTENT
The Fresno County General Plan Background Report identifies the Mono Lake-Long Valley area located adjacent to the north and east of the northernmost areas of Fresno County as the only known volcanic hazard to Fresno County. The Long Valley area is an active volcanic region of California and includes features such as the Mono-Inyo Craters, Long Valley Caldera, and numerous active and Figure 50. Components of a Volcanic Eruption

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potential faults. Figure 48. Volcanoes In or Near California shows volcanoes in or near California and the location of the Long Valley area relative to the Fresno County planning area.

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Source: USGS

Populations living near volcanoes are most vulnerable to volcanic eruptions and lava flows, although volcanic ash can travel and affect populations many miles away and cause problems for aviation.

Based on information in the background report, the Fresno County planning area is susceptible to various hazards associated with its proximity to the Long Valley area as further described below.

VOLCANIC FLOWS
Two mildly explosive volcanic vents are located three to four miles from northernmost Fresno County, northwest of Duck Lake. In the event of an eruption, flows or debris from the vents would likely flow predominantly southwest approximately parallel to the North Fork of the San Joaquin River in Madera County. Lava flows, steam blasts, or base surges could occur in the northernmost tip of Fresno County.

The northern portions of the Silver Divide (including Duck Lake and Fish Creek) could be subject to lava flows. However, this area of the County is mostly unpopulated and not easily developable as it is situated on the high peaks of the Sierra Nevada. Thus, potential safety hazards would be limited to backcountry visitors.

Figure 51. Volcanoes In or Near
California

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PYROCLASTIC FLOW
Pyroclastic flows are sudden eruption of hot (400- 1300°F), gas-pressurized flows of ash and lava fragments that rush outward from the volcano with great force at ground speeds greater than 50 miles per hour (mph). Pyroclastic flows typically follow valleys but can overtop ridges and travel 30 miles or more from the volcano. Due to the fast nature of these flows, they are the main cause of eruption- related fatalities. Flows can knock down, shatter, bury, or carry away nearly all objects and structures in its path and extreme temperatures can burn forests, crops, buildings, furnishings, and vehicles.

ASH
With most volcanic eruptions, a significant amount of ash is released into the atmosphere. The location and thickness of ash in any given area is generally a function of the volume erupted and wind speed and direction. Based on historical wind directions and wind speeds, most volcanic ash from a volcanic eruption of Long Valley would be deposited east of the volcano. Looking at historical data from past ash falls, most ash beds from volcanic eruptions in California lie east of their source vents. Other studies of Mount Rainier and Mount St. Helens show that more than 90 percent of the ash beds deposited from volcanic eruptions during the last 10,000 years lie to the east of those volcanoes. This data suggests that most ashfall from future eruptions, including those from Long Valley, would also be deposited to the east of the source.

According to a worst-case scenario provided in the background report, geologists estimate that the South Fork of the San Joaquin River, Mono Creek, Margaret Lakes, Duck Lake, Fish Creek, Lake Thomas A. Edison, Bear Creek, Lake Italy, and the town of Mono Hot Springs could be subject to eight inches or more of compacted ash from an eruption at Long Valley. It only takes up to five inches of ash to stop an automobile engine. These areas, in addition to Kaiser Creek and Three Island Lake, could also be affected by hot pyroclastic flows. It is further estimated that up to two inches of ash could fall within a 50-mile radius of the eruption, potentially affecting the areas of Auberry, Prather, Meadow Lakes, Pine Ridge, Tollhouse, Dinkey Creek, Humphreys Station, Courtright Reservoir, Pine Flat Reservoir, and numerous small lakes, creeks, and streams.

LAHARS
Lahars are slurry-like floods of volcanic ash, rock, and water that look like wet concrete. Debris flows gain momentum during travel by eroding and entraining soil and loose rock debris from channels. Large debris flows may carry boulders 30 feet across and travel through valleys and stream channels at speeds of 20 to 40 mph. Debris flows can be hot, with temperatures close to boiling. They occur during an eruption due to melting snow or ice, or after an eruption due to remobilization of loose volcanic deposits during intense rainfall. Debris flows have the ability to destroy buildings and bridges and bury vast areas with deposits of mud and rock to 160 feet thick as far as 65 miles from the volcano.

RESULTING FLOODS AND MUDFLOWS
An eruption on the western slope of Mammoth Mountain (on the rim of the Long Valley Caldera) in the winter could also cause hot mudflows to mix with melting snow and rock debris, creating the possibility of severe flood conditions in the San Joaquin River drainage system, endangering people, dams, and other property as it moves downstream.

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Figure 49. California Volcano Hazard Zones illustrates areas subject to potential volcanic hazards from future eruptions in California and supports the conclusion that the planning area is potentially at risk to volcanic activity from the Long Valley area. The hazard zone for the Long Valley Volcanic Region is right outside of the Fresno County’s jurisdictional boundaries but would still pose a threat to the planning area. The ash dispersion map that follows (Figure 50. Volcanic Hazards Ash Dispersion Map for the Long Valley Caldera) also illustrates the extent to which the planning area may be affected by ash fallout in the event of renewed volcanic activity in the area.

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Source: USGS

Figure 52. California Volcano Hazard Zones

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Source: National Parks Service
Note: Ma = Million Years Ago

PAST OCCURRENCES
During the past 1,000 years there have been at least 12 volcanic eruptions in the Long Valley area.

Volcanoes in the Mono-Inyo Craters volcanic chain, which extends from just south of Mammoth Mountain to the north shore of Mono Lake, have erupted often over the past 40,000 years. Over the past 5,000 years, small to moderate eruptions have occurred at various sites along the Mono- Inyo Craters volcanic chain at intervals ranging from 250 to 700 years (see Figure 51. Volcanic Activity in the Mono-Inyo Craters Volcanic Chain of the Past 5,000 Years). According to the California State Hazard Mitigation Plan, the most recent eruption in California occurred at Lassen Park within the Lassen Volcanic National Park about 100 years ago, from 1914- to 1917, about 55 miles east of the town of Redding.

Figure 53. Volcanic Hazards Ash Dispersion Map for the Long Valley Caldera

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Source: U.S. Geological Survey

In 1980, four large earthquakes (greater than magnitude 6 on the Richter Scale) and numerous relatively shallow earthquakes occurred in the area. Since then, earthquakes and associated uplift and deformation in the Mammoth Lakes Caldera have continued. Because such activities are common precursors of volcanic eruptions, the U.S. Geological Survey closely monitors the unrest in the region.

LIKELIHOOD OF FUTURE OCCURRENCES
Unlikely—According to the U.S. Geological Survey, the pattern of volcanic activity over the past 5,000 years suggests that the next eruption in the Long Valley area will most likely happen somewhere along the Mono-Inyo volcanic chain. However, the probability of such an eruption occurring in any given year is less than 1 percent. Most likely, the next eruption will be small and like previous eruptions along the Figure 54. Volcanic Activity in the Mono-Inyo Craters Volcanic Chain of the Past 5,000 Years

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Mono-Inyo volcanic chain during the past 5,000 years. Based on available data and the location of the County relative to the Long Valley area, there is a remote potential for volcanic activity of sufficient magnitude to adversely impact the Fresno County planning area. Researchers have long thought the risk of a super volcanic eruption in the Long Valley Caldera in our lifetime is extremely low, given that overall, the magma underneath the area is clearly cooling—essentially continuing to calm down, but the cooling process may release enough gas and liquid to cause earthquakes and small eruptions. Other scientists suggest that scientists suspect the Long Valley Caldera as a volcano is moribund— essentially dead— and the increased seismic activity, when it happens, is being generated by fluids that are not magma, but are still hot and moving to the surface as the magma cools and solidifies. 51

CLIMATE CHANGE CONSIDERATIONS
There presently is not enough data or research to quantify the magnitude of potential change that climate change may have on volcanic activity.

51 https://phys.org/news/2023-10-california-riskiest-volcanoes-eruption.html

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WILDFIRE

HAZARD/PROBLEM DESCRIPTION
Three classes of fires exist in the planning area: understory fires, crown fires, and ground fires.

Naturally induced wildfires burn at relatively low intensities, consuming grasses, woody shrubs, and dead trees. These understory fires often play an important role in plant reproduction and wildlife habitat renewal and self-extinguish by low fuel loads or precipitation. Crown fires, which consist of fires consuming whole living tress, are low probability but high consequence type events. Crown fires typically match perceptions of wildfires. In areas with high concentrations of organic materials in the soil, ground fires may burn, sometimes persisting undetected for long periods until the surface is ignited.

Potential losses from wildfire include human life, structures, critical infrastructure, natural and cultural resources, quality and quantity of water supplies, cropland, timber, and recreational opportunities.

Economic losses could also result due to damages to natural resources, grazing lands, tourism, and local businesses do not mention the loss of revenue to businesses during a wildfire event. Smoke and air pollution from wildfires can be a severe health hazard to local communities and the greater San Joaquin Valley air basin. In addition, catastrophic wildfire can create favorable conditions for other hazards such as flooding, landslides, and erosion during the rainy season impacting communities and downstream reservoirs.

To better address wildfire threats, California has updated its approach to land and fire management.

This includes advanced techniques for managing vegetation to lower fuel levels, employing controlled burns to restore natural fire cycles and mitigate risks, and enforcing tighter building regulations alongside thoughtful land use strategies to enhance the resilience of communities to wildfires. This comprehensive approach integrates the latest scientific insights, technological innovations, and traditional practices, aiming for a more effective mitigation of wildfire impacts throughout the state.

Generally, there are three major factors that sustain wildfires and predict a given area’s potential to burn. These factors are fuel, topography, and weather.

▪ Fuel—Fuel is the material that feeds a fire and is a key factor in wildfire behavior. Fuel is generally classified by type and by volume. Fuel sources are diverse and include everything from dead tree leaves, twigs, and branches to dead standing trees, live trees, brush, and cured grasses. Also, to be considered as a fuel source are manmade structures, such as homes and other associated combustibles. The type of prevalent fuel directly influences the behavior of wildfire. Fuel is the only factor that is under human control. Fuel types within the Fresno County planning area include annual grasses, deciduous oaks, and heavy brush in the Coast Range of western Fresno County, seasonal grasses, deciduous and evergreen oaks, brush, and grass in the lower and mid-elevations of central and eastern Fresno County, and conifers in the higher elevations of eastern Fresno County.
▪ Topography—An area’s terrain and slopes affect its susceptibility to wildfire spread. Both fire intensity and rate of spread increase as slope increases due to the tendency of heat from a fire to rise via convection. The arrangement and types of vegetation throughout a hillside can also contribute to increased fire activity on slopes.
▪ Weather—Weather components such as temperature, relative humidity, wind, and lightning also affect the potential for wildfire. High temperatures and low relative humidity dry out fuels that feed wildfires, creating a situation where fuel will more readily ignite and burn more intensely. Thus,

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during periods of drought, the threat of wildfire increases. Wind is the most influential weather factor of the three and its influence can increase rates of spread regardless of temperature and relative humidity. The Fresno County planning area has a diverse normal wind pattern. The western side of the planning area is influenced more by the coastal range and weather patterns along the coast.

The east side of the valley is more influenced by the normal heating and cooling of the valley floor and the influence along the river drainages, this area is also susceptible to foehn winds from the high Sierra. Lightning during the summer monsoonal moisture season also ignites wildfires, often in difficult terrain with limited access for firefighters. o Wildfire is an ongoing concern for the Fresno County planning area. Historically, the fire season extends from June through October of each year during the hot, dry months. Since 2010 the fire season throughout California and Fresno County has been getting longer, typically starting in May, and extending into November, but wildfires can occur any time of year. Fire conditions arise from a combination of high temperatures, intense sunlight, low rainfall and humidity, dry vegetation, and high winds. Down slope winds, such as the Santa Ana winds of southern California which can gust to 80 mph, are often associated with the most destructive wildfires.

Since they usually occur in the fall and winter after the summer dry season when there is ample dry vegetation for fuel, they can cause small fires to quickly burn out of control. Between 1948 and 2017, a recent study found, 22 percent of Southern California’s fires started under Santa Ana-like wind conditions, but those fires were more destructive and extensive than fires that started in calmer conditions, responsible for nearly half of the total area burned in the region and 80 percent of the fire-related economic damage incurred between 1990 and 2009.

WILDLAND URBAN INTERFACE (WUI)
Throughout California, communities are increasingly concerned about wildfire safety as increased development in the foothills and mountain areas and subsequent fire control practices have affected the natural cycle of the ecosystem. While wildfire risk is predominantly associated with wildland- urban interface (WUI) areas, significant wildfires can also occur in heavily populated areas and across non WUI landscapes in the forest. The wildland-urban interface is a general term that applies to development adjacent to or within large watershed landscapes that support wildfire. Wildfires affect grass, forest, and brush lands, as well as any structures located within them. Where there is human access to wildland areas, such as the Sierra Nevada and Coast Range foothills, the risk of fire increases due to a greater chance for human carelessness as 90 percent of wildland fires are human caused.

EXTENT
In terms of geographic extent, the wildfire hazard potentially impacts the entire planning area, but the most intense fires will be in the forested areas of the county. While Figure 52. Fresno County's Wildfire Severity Zones depicts potential severity across the planning area, the history of occurrence table (Table 64. Fresno County Past Occurrences: Wildfire) and Figure 53. Fresno County Historic Wildfires indicates that even moderate and low risk areas have experienced wildfires, and potentially will continue to do so. However, with regard to the severity or potential impact of the wildfire hazard two facts should be considered: first, both maps demonstrate that the areas of greatest risk correspond to the locations with the greatest number of historical events; second, the Medium, High, and Very High hazard areas correspond to heavily forested areas and urban wildland interface areas, where fuel loads for wildfire are highest, are periodically exacerbated by drought conditions, and further complicated by a widespread incidence of tree mortality adding additional fuel load risk (see drought and tree mortality sections for more information). Finally, to understand the extent of wildfire severity,

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the variable risk (Low, Medium, High, Very High) across the planning area identified on the wildfire risk map must be viewed in relation to the location of each jurisdiction participating in the plan. Most of the risk is in the unincorporated areas and on the fringes of municipalities that include Coalinga, Fresno, and Firebaugh. The Sierra Resource Conservation District has considerable area at risk of wildfires.

For additional information on each jurisdiction’s wildfire risk, please consult the jurisdictional Annexes and the Vulnerability Section.

The Fire Rating System is defined in Table 63. The Fire Danger Rating System describes the characteristics and potential intensity of fires, including the effect on the ability to manage and suppress fires. Such characteristics should be understood considering the wildfire risks and history of occurrence in Fresno County, as identified and in the narrative descriptions of wildfire history previously discussed.

Fire conditions up through Class 5 are possible in Fresno County, primarily in the unincorporated areas.

Table 63. The Fire Danger Rating System
Rating Basic Description Detailed Description
CLASS 1: Low
Danger (L) COLOR
CODE: Green
fires not easily started
Fuels do not ignite readily from small firebrands. Fires in open or cured grassland may burn freely a few hours after rain, but wood fires spread slowly by creeping or smoldering and burn in irregular
fingers. There is little danger of spotting.

CLASS 2:

Moderate Danger
(M) COLOR CODE:

Blue
fires start easily and
spread at a moderate
rate
Fires can start from most accidental causes. Fires in open cured grassland will burn briskly and spread rapidly on windy days.

Woods fires spread slowly to moderately fast. The average fire is of moderate intensity, although heavy concentrations of fuel – especially draped fuel -- may burn hot. Short-distance spotting may occur but is not persistent. Fires are not likely to occur.
serious and control is relatively easy.

CLASS 3: High
Danger (H) COLOR
CODE: Yellow
fires start easily and
spread at a rapid rate
All fine dead fuels ignite readily, and fires start easily from most causes.

Unattended bushes and campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. High intensity burning may develop on slopes or in concentrations of fine fuel. Fires may become serious and their control difficult,
unless they are hit hard and fast while small.

CLASS 4: Very
High Danger (VH)
COLOR CODE:

Orange
fires start very easily and
spread at a very fast rate
Fires start easily from all causes and immediately after ignition, spread rapidly and increase quickly in intensity. Spot fires are a constant danger. Fires burning in light fuels may quickly develop high-intensity characteristics - such as long-distance spotting - and fire whirlwinds when they burn into heavier fuels. Direct attack at the head of such fires is rarely possible after they have.
been burning more than a few minutes.

CLASS 5: Extreme
(E) COLOR CODE:

Red
fire situation is explosive
and can result in
extensive property
damage
Fires under extreme conditions start quickly, spread furiously, and burn intensely. All fires are potentially serious. Development into high intensity burning will usually be faster and occur from smaller fires than in the Very High Danger class (4). Direct attack is rarely possible and may be dangerous, except immediately after ignition. Fires that develop headway in heavy slash or in conifer stands may be unmanageable while the extreme burning condition lasts. Under these conditions, the only effective and safe control action is on the flanks, until the weather changes or
the fuel supply lessens.

Source : http://www.wfas.net

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Within the County there are three principal areas that have large damaging fire history: West of Interstate 5, the San Joaquin River Watershed, and the Kings River Watershed. Each of these areas have unique vegetation and topography types, fire weather and communities. West of Interstate 5 is best described as an area with low rainfall (average of less than 10 inches) and a vegetation type consisting of annual grass, oak woodlands, and brush. This area is predominantly used as rangeland for livestock grazing, mining, oil and gas production and underground transportation.

The San Joaquin River and the Kings River Watersheds have a diverse vegetation type ranging from annual grasslands, oak woodlands, brush, and timber. These vegetation types of transition from the valley floor to the Sierra Nevada’s. The topography ranges from rolling foothills, steep river canyons to high Sierra mountains. This area has numerus communities and homes on small parcels intermixed within the larger landscape. The San Joaquin River and Kings River have numerous hydroelectric facilities and critical power infrastructure located from the foothills to the high Sierra. Recreation in the Sierra and Sequoia National Forests areas along with group camps increases the population and ignition potential during fire season. The drought that started in 2012 has left an abundance of dead brush, oaks, and timber in the upper elevations of these watersheds. The impacts to the vegetation will carry on for many years into the future making fire suppression more difficult and increasing the chance for large catastrophic fires across the landscape.

Figure 55. Fresno County's Wildfire Severity Zones

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Source: CA Geoportal; CA-DFW; CA Department of Forestry & Fire Protection, CalFIRE ArcGIS Online Portal; CalTrans; County of Fresno - GIS

PAST OCCURRENCES
Wildfires are of significant concern throughout California. According to the California Department of Forestry and Fire Protection (CAL FIRE), vegetation fires occur within their jurisdiction on a regular basis; most are controlled and contained early with limited damage. For those ignitions that are not readily contained and become major incidents, damage can be extensive. There are many causes of wildfire, from naturally caused lightning fires to human-caused fires linked to activities such as smoking, campfires, debris burning, equipment use, and arson. Recent studies conclude that the greater the population density in an area, the greater the chance of an ignition. The recent major wildland fires are the Powerhouse Fire in 1989 and the Valerie Meadows Fire in 1979. Most of the lands at the upper elevations have experienced fire within the past fifty years. Fires at the lower elevations generally do not offer fuel reduction benefits in following year(s) due to re-growth of annual grasses. With population continuing to grow throughout California and the Fresno County planning area, the risk posed by wildfire also continues to grow.

According to the 2005 Prefire Management Plan for CAL FIRE’s Fresno-Kings Unit, an ignition analysis for 2004 was determined to be very similar to that of years past. The four primary ignition sources continue to be other and undetermined (535 fires), arson (311 fires), equipment use (315 fires), and debris burning (158 fires). The remaining causes, which are almost insignificant in number, are lightning, campfires, smoking, vehicles, electrical power, and playing with fire. The unit, which encompasses all of Fresno and Kings counties, experiences 120 to 200 fires a year in the state responsibility area and 1,400 to 1,600 fires in the local responsibility area is a fire history map for the Fresno-Kings Unit. During the drafting of the 2009 Fresno County HMP, the Unit, which encompasses all of Fresno and Kings counties, experienced 120 to 200 fires a year in the state responsibility area and 1,400 to 1,600 fires in the LRA.

In 2017, the Fresno County Fire Protection District reports a dramatic increase in fire incidents, with 1,283 reported as of July 31, 2017. That said, of the total number, 470 were categorized as Vegetation fires (wildfires), while the remaining fires related to vehicles (221), structures (197), refuse (331), industrial (33), improvement/controlled burns (21), and agricultural products (10). However, as has been noted previously, wildfires occur from both natural and human-made causes. Therefore, given the recent frequency increase in vegetation fires, and the fact that other types of fires have the potential to spread into a wildfire scenario, the wildfire hazard risk seems to be growing, and the LHMPC will remain vigilant in its efforts to mitigate the risks, although an increase in frequency does not necessarily translate to an increase in the extent (range) of wildfires or their severity.

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Previous wildfire events are detailed in the table and map below for Fresno County. The HMPC identified the following as notable wildfires in the Fresno County planning area:

▪ 1933: The Tollhouse Fire started when a local resident was burning brush in late August. The fire got out of hand and burned across fields and grazing lands and encircled the Town of Tollhouse, a large hub for the timber industry in eastern Fresno County. It burned portions of the flume that carried logs and boards from Shaver Lake to the valley floor. The fire raced up the hill and burned into Jose Basin and over Burrough Mountain into Blue Canyon. The fire burned very hot, destroying conifers in the area, which never grew back. Tollhouse was evacuated for safety, but no losses were incurred.
▪ 1987: The state declared a disaster for Fresno County and 32 other counties during the 1987 wildfires. Collectively, the fires resulted in 3 deaths, 76 injuries, and $18 million in damage. The eastern side of Fresno County was primarily affected. Property damage was estimated at $1 million.

Damage to roads, bridges, and power distribution also occurred. Timber production in the area was also impacted.
▪ August 2-21, 1989: The Powerhouse Fire, suspected to be caused by arson, ignited near the Fresno and Madera County line, and burned through 21,000 acres, affecting the areas from Auberry to Meadow Lakes. Although no fatalities occurred and no homes were destroyed, the fire caused minor injuries to firefighters and the loss of several outbuildings, as well as damage to infrastructure. The fire's impact was particularly severe on the local watershed and wildlife, signaling a significant ecological and community disturbance.
▪ August 24, 1994: The Big Creek Wildland Fire in eastern Fresno County burned 9,000 acres of national forest land, threatened hundreds of homes, and led to the evacuation of the Big Creek community. Costs included $2 million in damage to national forest infrastructure, $500,000 to power distribution, and recovery expenses for the land were estimated at $2 million. The firefighting effort exceeded $50 million, and a subsequent mudslide incurred an additional $50,000 in damages. ▪ September 21, 2000: The Millwood Fire burned 283 acres; 363 personnel responded. Highway 180 was closed until 8:00 p.m. that evening. A shelter was prepared in the City of Orange Cove but was not used.
▪ August 17, 2001: The Highway fire located near the community of Dunlap, burned 4,152 acres, and destroyed five outbuildings, a cabin, two travel trailers, and a miscellaneous number of cars. ▪ August 17, 2001: The Musick Fire, located between Shaver Lake and Big Creek, burned 193 acres. No structures were damaged in this fire caused by downed power lines. The cost was estimated at $800,000.
▪ July 2013: The Aspen Fire took place in the Kaiser Wilderness area of the Sierra National Forest, North of Huntington Lake. The fire burned over 150,000 acres with a suppression cost of $22.8 million dollars. The fire posed imminent danger to people within the National Forest, resulting in the evacuation of multiple campsites.
▪ July 30, 2015: The Rough Fire, sparked by lightning in the Sierra National Forest, spread to encompass 151,000 acres, affecting nearby national parks, and causing the evacuation of multiple communities. The blaze led to poor air quality, the closure of schools and summer camps, and the destruction of buildings, while also severely reducing local tourism revenue. Suppression efforts for this massive wildfire cost $119 million.

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▪ July 1, 2016: The Curry Fire was a major wildland fire that burned 2,944 acres in Coalinga, CA.

Though no crop, property or infrastructure damage or personal injury occurred, it did result in several road closures.
▪ July 2016: The Goose Fire began at or around the intersection of Gooseberry Lane and Morgan Canyon Road, South of the town of Prather. The fire consumed 2,241 acres and destroyed 4 residences and 5 outbuildings. The fire posed an imminent threat to 400 homes, and residents were issued evacuation orders.
▪ August 8, 2016: The Mineral Fire was a major wildland fire which burned 7,05 acres in Coalinga, CA. Though no crop, property or infrastructure damage or personal injury occurred, it did result in several road closures.
▪ October 11, 2016: The Sacata Fire started near Sacata Ridge above Pine Flat in the Sierra National Forest. The fire was contained after burning over 1,500 acres. Active for 9 days, it was fully contained by October 20, 2016.
▪ July 9, 2017: The Garza Fire was a major wildland fire igniting in Monterey County (Coalinga, CA), and spreading to Kings and Fresno Counties. Although the fire burned 48,888 acres, no personal injuries or damage to crops, buildings or infrastructure were reported. However, it did result in several road closures.
▪ June 25, 2017: The Creek fire began off Los Gatos Creek Rd, west of Derrick, or 13 miles northwest of Coalinga, CA in Fresno County. The cause is under investigation. It burned 357 acres before being contained on June 28, 2017. There was one residence and 3 sheds destroyed. The cost of containment was $1.5 million.
▪ July 16, 2017: The Detwiler Fire began 15 miles northwest of Mariposa, CA. It was human caused.

It burned 81,826 acres, resulting in 63 residences, 67 minor structures and 1 commercial structure being destroyed with another 13 residences and 8 minor structures damaged. The fire forced the evacuation of several small rural communities for as long as 10 days and the entire town of Mariposa (population 18,000) for 3 days. Parts of Highways 41, 49, and 140 were closed at times during the fire. The fire was 90 percent contained on July 31, 2017, but no additional growth occurred before it was completely contained on August 24, 2017. The cost of containment was $87 Million.
▪ August 13, 2017: The South Fork Fire started near Wawona in Yosemite National Park, prompting the closure of trails and the evacuation of Wawona due to the spread of the fire caused by thunderstorm downdrafts. Although containment reached 44 percent by the end of August, the fire was allowed to burn to the east into more rugged terrain. The fire, managed as it moved into the wilderness, was expected to continue burning into October. ▪ August 29, 2017: The Railroad Fire started near Sugar Pine, just south of Yosemite National Park, and led to the closure of Highway 41 and evacuations, including the Tenaya Lodge. It burned 12,407 acres, including part of the Nelder Grove of Giant Sequoias, and was contained by September 15, 2017, with costs reaching $20.8 million. Seventeen structures were destroyed, notably historical railroad items from the Yosemite Mountain Sugar Pine Railroad. ▪ September 3, 2017: Two fires started within a short time of each other both in the foothills of the Sierra Nevada. The Mission fire began 2 miles east of North Fork in Madera County and burned 1035 acres and destroyed three residences and damaged 4 other structures before being contained on September 13, 2017. The Peak fire began 9 miles southeast of Mariposa in Mariposa County and burned 680 acres and destroyed 2 structures before being contained on September 9, 2017.

The cause of both fires is unknown.

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▪ July 13, 2018: The Ferguson Fire began on July 13 near Mariposa, CA, and grew under difficult conditions including steep terrain and heavy beetle-killed trees, leading to road closures and evacuations. Smoke from the fire caused significant air quality issues, prompting the closure of parts of Yosemite National Park, and impacting the broader Sierra Nevada region. By the end of July, the fire had consumed 57,041 acres and incurred costs of $64.3 million, with the firefighting effort marred by the deaths of two firefighters.
▪ July 13, 2020: The Mineral fire was first spotted around 5 PM, with nearly 1000 acres burned by days end. The next several days resulted in significant fire growth and numerous evacuation notices within the region. Highway 198 between Coalinga and Monterey County was closed which impacted commerce, though the greatest impact was the loss of seven structures. Full containment of the fire was seen on 26th, though growth ended days prior. ▪ July 24, 2020: The Blue Jay fire began due to a lightning strike near the White Wolf Campground.

The fire burned in general wilderness, though did close several trails within the park. ▪ August 15, 2020: The Hills Fire started in the foothills about 9 miles south of Coalinga, CA. It grew to 2,121 acres before being contained on 8/25/2020. The cause was under investigation. The cost of containment was $3.9 million. No structures were destroyed or damaged. Tragically, a helicopter pilot was killed on August 18 when his helicopter crashed while making water drops over the fire. ▪ August 19, 2020: The Castle Fire, ignited by lightning on August 19, 2020, near the Giant Sequoia National Monument, grew from 2,000 to 35,674 acres by the end of August, prompting evacuations and road closures. Merging with the Shot Gun Fire to form the SQF Complex on August 29, the fire had zero containment and costs reached $5.6 million by August 31st. The fire persisted into September, challenging firefighting efforts in the Sequoia National Forest. ▪ September 4, 2020: The Creek Fire, which started near Big Creek, California on September 4th, rapidly expanded to 73,278 acres by September 6th due to extreme heat and low humidity. Despite the slowing effects of extensive smoke, by September 9th the fire had reached nearly 153,000 acres, necessitating the evacuation of about 45,000 people and the destruction of 853 structures by the end of the month. Persistent hot and dry conditions under strong high pressure allowed the fire to continue burning into November, with containment costs reaching $106 million. ▪ 2021: The Blue Fire, Fish Fire, Slope Fire, and Vulcan Fire, all occurring in 2021, collectively burned 442 acres of land in Fresno County, California. The Blue Fire was the largest, scorching 277 acres near Shaver Lake, while the Fish and Slope Fires were quickly contained, affecting 75 and 25 acres, respectively. The Vulcan Fire consumed 140 acres near Friant Road and was managed by both CAL FIRE and Fresno City Fire Department. Despite the varied sizes and locations, effective firefighting efforts led to the successful containment of each incident without significant damage to communities or infrastructure.
▪ 2022: In 2022, Fresno County in California experienced several wildfires that tested the mettle of firefighting teams. Near Shaver Lake, the House Fire in May necessitated significant resource deployment and evacuation measures but was quickly brought under control, covering an area of 171 acres. The Pebble Fire, which emerged east of Fresno in late July, consumed 55 acres and was swiftly contained, showcasing the effectiveness of local firefighting efforts. The Power Fire in September posed a threat to 130 acres near Aubery Rd but was contained within a week by the diligent efforts of the Fresno-Kings Unit. Finally, the Table Fire, which occurred in early July on Table Mountain, was the most quickly addressed, with 52 acres contained in a mere two days. ▪ 2023: Throughout 2023, Fresno County in California faced a series of wildfires across various locations, each notable for their swift containment. The Crane Fire and Rodeo Fire, both near Squaw Valley, and the Juniper Fire to the west of Coalinga were among the smaller incidents,

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affecting areas of 24 and 15 acres each. Larger fires like the Orange Fire near Orange Cove and the Panoche Fire north of Little Panoche Rd, burned through 108 and 65 acres, respectively. The Pistol Fire near Auberry Road, and the extensive Slough Fire near San Joaquin, which spanned a vast 640 acres, were also brought under control promptly. Meanwhile, the Wildcat Fire occurred around Forest Service Road 10S069 and Trimmer Springs Road, near Pine Flat, and was managed by the US Forest Service-Sierra National Forest. The investigation into the causes of these wildfires was ongoing as the fire season progressed.

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Table 64. Fresno County Past Occurrences: Wildfire
Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Town of
Tollhouse 1933 0 0 0 0 0
Eastern Fresno
County 1987 0 1 M 0 3 76
Auberry Road
and Meadow
Lane
8/2/1989 –
8/21/1989 0 0 0 0 0
Big Creek 8/24/1994 0 0 0 0 12
Big Creek 9/21/2000 0 0 0 0 0
Dunlap 8/17/2001 0 0 0 0 0
Shaver Lake
and Big Creek 8/17/2001 0 0 0 0 0
Kaiser
Wilderness July 2013 0 0 0 0 0
Sierra National
Forest 7/30/2015 0 0 0 0 0
Coalinga 7/01/2016 0 0 0 0 0
Gooseberry
Lane and
Morgan
Canyon Road
July 2016 0 0 0 0 0
Coalinga 8/08/2016 0 0 0 0 0
Coalinga 7/09/2017 0 0 0 0 0
Los Gatos
Creek Road 6/23/2017 0 0 0 0 0
Mariposa 7/16/2017 0 0 0 2 19
Wawona 8/13/2017 0 0 0 0 0
Sugar Pine 8/29/2017 0 0 0 0 6
Sierra Nevada
Foothills 9/03/2017 0 0 0 0 0
Mariposa 7/13/2018 0 0 0 2 19
Highway 198
Coalinga 7/13/2020 0 0 0 0 0
White Wolf
Campground 7/24/2020 0 0 0 0 0
Coalinga 8/15/2020 0 0 0 1 0
Giant Sequoia
National
Monument
8/19/2020 0 0 0 0 15
Big Creek 9/04/2020 0 0 0 0 29
Shaver Lake,
Friant Road 2021
Shaver Lake,
Table Mountain 2022

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Location Date Magnitude Property
Loss ($)
Crop Loss
($) Deaths Injuries
Squaw Valley,
Orange Cove 2023
Source: NOAA, National Centers for Environmental Information, Storm Events Database, California Department of Forestry and Fire Protection CAL FIRE

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Source: CA Geoportal; CA-DFW; Ca Department of Forestry & Fire Protection, CalFIRE ArcGIS Online Portal; CalTrans; County of Fresno - GIS

Figure 56. Fresno County Historic Wildfires

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LIKELIHOOD OF FUTURE OCCURRENCES
Highly Likely—Within the Fresno-Kings Unit, fire occurrences range from 120 to 200 fires a year in the SRA and 1,400 to 1,600 fires in the LRAs. Fires will continue to occur on an annual basis in the Fresno County planning area.

Other statistical measures to be considered in assessing the extent of the wildfire hazard include data on frequency (and severity): According to the Fire and Resource Assessment Program (FRAP), having compiled and analyzed a variety of measures for fire activity, such as the influence of time and fuel types, although fire activity across the state varies from year to year, the annual average since 2000 is 598,000 acres, or almost twice that of the preceding 50-year period from 1950-2000 (264,000 acres).

It should be noted that many ecosystems in the state that previously adapted to frequent low to moderate severity fires have seen shifts in reduced fire frequency (missed fire cycles), associated fuel build-up, and subsequent increases in fire severity when wildfires eventually occur. That said, other ecosystems appear to be burning too frequently – a situation facilitated by exotic invasive species that cause fundamental changes to post-fire fuel dynamics. These changes facilitate early seral phases to re-burn within a matter of only a couple years and may reduce or eliminate native species that require time to develop to maturity and assure regeneration. And, in areas such as Fresno County, where ecosystems are commingled across various regimes, there is more uniformity of mixed-and high- severity effects that are not as clearly linked to basic ecosystem function. Therefore, in many mixed conifer systems, while the modern trend indicates an increase in fire rates, the type of fire and its typical interval are still significantly departed from the frequent low and mixed-severity fires that dominated low and mid-elevation confer forests throughout California52

CLIMATE CHANGE
Over the past four decades, annual area burned has increased significantly in California and across the western United States. This trend reflects a confluence of intersecting factors that affect wildfire regimes. It is correlated with increasing temperatures and atmospheric vapor pressure deficit.

Anthropogenic climate change is the driver behind much of this change, in addition to influencing other climate-related factors, such as compression of the winter wet season. These climatic trends and associated increases in fire activity are projected to continue into the future. Additionally, factors related to the suppression of the Indigenous use of fire, aggressive fire suppression and, in some cases, changes in logging practices or fuel management intensity, collectively have produced large build-ups of vegetative fuels in some ecosystems. 53
According to the Environmental Protection Agency (EPA) the change in burned area has increased from 1984-2001 and 2002-2020 by 3.62 acres per square mile. Most of the western states have also seen an increase in burned acreage from similar time intervals, shown in Figure 57. Change in Annual Burned Acreage by State Between 1984-2001 and 2002-2020.

52 2010 Assessment Chapter 2.1: Wildfire Threat to Ecosystem Health and Community Safety 53 Drivers of California’s changing wildfires a state-of-the-knowledge synthesis (nwfirescience.org) nwfirescience.org/sites/default/files/publications/Drivers of California’s changing wildfires- a state-of-the-knowledge synthesis.pdf

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Figure 57. Change in Annual Burned Acreage by State Between 1984-2001 and 2002-2020

Source: MTBS (Monitoring Trends in Burn Severity) 2022

Even under a pathway of lower greenhouse gas emissions, average annual temperatures are projected to exceed historical record levels most likely by the middle of the 21st century. Overall, warming will lead to increased heat wave intensity but decreased cold wave intensity. Future heat waves signify a potential increase in the wildfire hazard intensity and severity in Fresno County, as well as a year-long fire season. According to the California’s Fourth Climate Change Assessment, by 2100 if greenhouse gas emissions continue to rise, one study found that the frequency of extreme wildfires would increase, and the average area burned statewide would increase by 77 percent. 54

54 State Key Findings - California Climate Change Assessment

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Finally, it should be noted that Fresno County potentially has less capacity to address future wildfire risk related to climate change due to shortages in water, vital to combating wildfires. In California, rising temperatures are projected to increase the average lowest elevation at which snow falls, reducing water storage in the snowpack.

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FRESNO COUNTY’S MITIGATION CAPABILITIES
Thus far, the planning process has identified the hazards posing a threat to Fresno County and described, in general, the vulnerability of the County to these risks. The next step is to assess what risk reduction mechanisms are already in place. These mechanisms include e laws, policies, programs, staff, funding and other resources on hand to carry out the plan and increase resilience. This part of the planning process is the mitigation capability assessment. Combining the risk assessment with the mitigation capability assessment results in the County’s “net vulnerability” to disasters and more accurately focuses the goals, objectives, and proposed actions of this plan. The capability assessment also informs the mitigation strategy. The chosen actions should either match the community’s resources or support strengthening or building capacity where resources might not exist.

As such, this section presents Fresno County’s mitigation capabilities: programs and policies currently in use to reduce hazard impacts or that could be used to implement hazard mitigation activities. It also identifies capabilities specific to the other participating jurisdictions can be found in the jurisdictional annexes.

The HMPC used a two-step approach to originally conduct this assessment for the County. First, an inventory of common mitigation activities was made through the use of a matrix. The purpose of this effort was to identify policies and programs that were either in place, needed improvement, or could be undertaken, if deemed appropriate. Second, the HMPC reviewed existing policies, regulations, plans, and programs to determine if they contributed to reducing hazard-related losses or if they inadvertently contributed to increasing such losses. During the 2024 update this section was reviewed by County and Witt O’ Brien’s consultant team staff to update information where applicable. This included revising sections to align with changes that will be reflected in the updated General Plan.

This update process afforded the County and its participating jurisdictions the opportunity to review their previous capabilities and note the ways in which these capabilities have improved or expanded since the adoption of the previous plan. Additionally, in summarizing their current capabilities and identifying gaps, plan participants also considered their ability to expand or improve upon existing policies and programs as potential new mitigation strategies. Chapter 5 Mitigation Strategy includes mitigation actions aimed at improving community capability to reduce hazard risk and vulnerability. An overview of Fresno County’s capabilities is described in Table 65. Fresno County Capability Summary.

Table 65. Fresno County Capability Summary
Area Degree of Capability
Limited Moderate High
Planning and Regulatory
Capability X
Administrative and
Technical Capability X
Fiscal Capability UNKNOWN
Available Staff UNKNOWN
Political Support/Interest UNKNOWN
Community Support UNKNOWN

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FRESNO COUNTY’S REGULATORY MITIGATION CAPABILITIES
Table 66. Fresno County's Regulatory Mitigation Capabilities regulatory mitigation capabilities, including planning and land management tools, typically used by local jurisdictions to implement hazard mitigation activities and indicates those that are in place in Fresno County. Excerpts from applicable policies, regulations, and plans and program descriptions follow to provide more detail on existing mitigation capabilities.

Table 66. Fresno County's Regulatory Mitigation Capabilities Plans In Place Adopted/Updated
Under
Development Expected
Completion Yes No Yes No
Building Codes (please
indicate UCC or IBC + year) UNKNOWN
Community Emergency
Response Team (CERT) UNKNOWN
Community Rating System
(CRS Program of the NFIP) UNKNOWN
Emergency Management
Accreditation Program (EMAP) UNKNOWN
Fire Code UNKNOWN
Firewise Community UNKNOWN
Floodplain Management/Flood
Damage Prevention Ordinance UNKNOWN
Land Use/Development
Planning UNKNOWN
National Flood Insurance
Program (NFIP) UNKNOWN
Post Disaster
Redevelopment/Reconstruction
Plan/Ordinance

UNKNOWN
Storm Ready UNKNOWN
Stormwater Management
Plan/Ordinance UNKNOWN
Subdivision
Regulations/Ordinance UNKNOWN
Two Weeks Ready UNKNOWN
Unified Development
Ordinance UNKNOWN
Zoning Ordinance UNKNOWN

As indicated in the table above, Fresno County has several plans and programs that guide the County’s development in hazard-prone areas. Starting with the Fresno County General Plan, which is the most comprehensive of the County’s plans when it comes to mitigation, some of these are described in more detail below.

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FRESNO COUNTY GENERAL PLAN
The Fresno County General Plan consists of multiple documents: the countywide General Plan Background Report, the countywide General Plan Policy Document, and over 40 regional, community, and specific plans. This discussion is derived primarily from the Fresno County General Plan Policy Document, from which the text that follows is largely extracted.

The Fresno County General Plan is a comprehensive, long-term framework for the protection of the county’s agricultural, natural, and cultural resources and for development in the county. Designed to meet State general plan requirements, it outlines goals, policies, and programs and sets out plan proposals to guide day-to-day decisions concerning Fresno County’s future. The County sees its primary role to be the protector of prime agricultural lands, open space, recreational opportunities, and environmental quality, and the coordinator of countywide efforts to promote economic development.

▪ Economic Development
▪ Agricultural Land Use
▪ Transportation and Circulation
▪ Public Facilities and Services
▪ Open Space and Conservation
▪ Health and Safety
▪ Environmental Justice
▪ Housing

Each of these elements includes goal statements relating to different aspects of the issues addressed in the element. Under each goal statement, the plan sets out policies that amplify the goal statement.

Implementation programs are listed in a separate Administration and Implementation Section and describe briefly the action proposed by the program, the County agencies or departments with primary responsibility for carrying out the program, and the time frame for accomplishing the program.

The County is conducting a comprehensive review of its current General Plan. Based on the review, County staff has proposed revisions to the Plan’s goals, policies, and programs.

Following is an element-by-element summary of the General Plan goals and policies that are most relevant to the Hazard Mitigation Plan Update. The summary tracks the organization of each element, with topically focused goals followed by related policies. Note that the summaries reflect policies as proposed by the County as a result of its ongoing review, including deletions and revisions.

STATE OF CALIFORNIA SAFETY ELEMENT
The state of California requires General Plans to address nine elements which include land use, circulation, housing, conservation, open space, noise, safety, environmental justice, and air quality. The safety elements aim to reduce the potential short and long-term risk of death, injuries, property damage, and economic and social dislocation resulting from fires, floods, droughts, earthquakes, landslides, climate change, and other hazards. The safety elements should contain general hazard and risk reduction strategies complementary to the local hazard mitigation plan. In order to support the Fresno County General Plan’s Safety Element, the local hazard mitigation plan must address parts of

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the state’s safety element requirements. Table 67. California State Safety Element Requirements includes the state’s Safety Element requirements.

Table 67. California State Safety Element Requirements
Statutory Citation Brief Description of Requirements
Gov. Code 65302(g)(1) Identification of unreasonable risks and policies for the protection of the community from such risks.

Gov Code 65302(g)(1) Slope Instability
Slope instability leading to mudslides and landslides.

Gov. Code 65302(g)(1)
Seismic risks, including:

Seismically induced surface rupture, ground shaking, ground failure, tsunami, seiche, and dam failures; subsidence, liquefaction, and other seismic hazards identified to Chapter 7.8 (commencing with Section 2690) of Division 2 of the Public Resources Code, and other geologic hazards known to the legislative body

• Mapping known seismic and other geologic hazards
• Address
o Evacuation routes
o Military installations
o Peak load water supply requirements and
o Minimum road widths and clearances around structures
Gov. Code 65302(g)(2)
Flooding

Identify
• Flood Hazard Zones
• FEMA Flood Insurance Maps
• Army Corps of Engineer Flood Information
• Flood maps from the Central Valley Flood Protection Board • Dam Failure Maps (Office of Emergency Services)
• DWR Floodplain Maps
• Maps of Levee Protection Zones
• Areas subject to inundation in the event of the failure of levees and floodwalls • Historic flood information
• Existing and planned development in flood hazard areas • Agencies with responsibility for flood protection

Mandatory Goals, Policies, and Objectives
• Avoid and minimize flood risks for new development
• Should new development be located in flood hazard zones? If so, what are appropriate mitigation measures?
• Maintain the integrity of essential public facilities • Locate, when feasible, new essential public facilities outside of flood hazard zones, including hospitals and health care facilities, emergency shelters, fire stations, emergency command centers, and emergency communications facilities, or identifying mitigation measures.
• Establishing cooperative working relationships among public agencies with responsibility for flood protection

Feasible Mitigation Measures, to implement the policies above.

Gov. Code 65302(g)(3) Wildland and Urban Fires

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Statutory Citation Brief Description of Requirements
Identification of, and policies for, the protection of the community from, unreasonable risks associated with wildland and urban fires.

State Responsibility Areas and Very High Fire Hazard Severity Zones Consider advice in OPR’s Fire Hazard Technical Advisory Identify
• CalFIRE Fire Hazard Severity Zone Maps
• Historical data on wildfires
• USGS wildfire hazard areas
• Existing and planned development within these areas
• Agencies with responsibility for fire protection in these areas

Mandatory Goals, Policies and Objectives
• Protect the community from unreasonable risks
• See mitigation measures below

Feasible Mitigation
• Avoid and minimize fire risks for new development
• Should new development be located in fire hazard zones? If so, what are appropriate mitigation measures?
• Maintain the integrity of essential public facilities • Locate, when feasible, new essential public facilities outside of fire hazard zones, including hospitals and health care facilities, emergency shelters, fire stations, emergency command centers, and emergency communications facilities.
• If essential facilities are located in high fire zones, identify mitigation measures, such as safe access for emergency response vehicles, visible street signs, and water supplies for structural fire suppression
• Establishing cooperative working relationships among public agencies with responsibility for fire protection
Gov. Code 65302(g)(4)
Climate Change Adaptation and Resilience

Address climate change adaptation and resiliency strategies by using the process in the Adaptation Planning Guide and reflected in referenced tools such as Cal-Adapt

Vulnerability Assessment (Gov Code 65302(g)(4)(A)

Create a vulnerability assessment that identifies the risks that climate change poses to the local jurisdiction and the geographic areas at risk from climate change impacts, the following:
• Information that may be available from federal, state, regional, and local agencies that will assist in developing the vulnerability assessment and the adaptation policies and strategies, including, but not to, all of the following
(I) Information from the Internet based Cal-Adapt tool
(II) Information from the most recent version of the California Adaptation Planning Guide
(III) Information from local agencies on the types of assets, resources, and populations that will be sensitive to various climate change exposures (IV) Information from local agencies on their current ability to deal with the impacts of climate change
(V) Historical data on natural events and hazards, including locally prepared maps of areas subject to previous risk, areas that are vulnerable, and sites that have been repeatedly damaged
(VI) Existing and planned development in identified at-risk areas, including structures, roads, utilities, and essential public facilities

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Statutory Citation Brief Description of Requirements
(VII) Federal, state, regional, and local agencies with responsibility for the protection of public health and safety and the environmental, including special districts and local offices of emergency services

Mandatory Goals, Policies, and Objectives (Gov. Code 65302(g)(4)(B)) • Crete a set of adaptation and resilience goals, policies, and objectives based on the information above for the protection of the community
Gov. Code 65302(g)(4)

CONTINUED
Feasible Mitigation (Gov. Code 65302(g)(4)(C))
• Create a set of feasible implementation measures designed to carry out the goals, policies, and objectives identified above, including but not limited to, all of the following:
(i) Feasible methods to avoid or minimize climate change impacts associated with new uses of land
(ii) The location, when feasible, of new essential public facilities outside of at-risk areas, including, but not limited to, hospitals and health care facilities, emergency shelters, emergency command centers, and emergency communications facilities, or identifying construction methods or other methods to minimize damage if these facilities are located in at-risk areas.
(iii) The designation of adequate and feasible infrastructure located in an at-risk area (iv) Guidelines for working cooperatively with relevant local, regional, state, and federal agencies
(v) The identification of natural infrastructure that may be used in adaptation projects, where feasible. Where feasible, the plan shall use existing natural features and ecosystem processes, or the restoration of natural features and ecosystem processes, when developing alternatives for consideration. For the purposes of the clause, “natural infrastructure” means preservation or restoration of ecological systems, or utilization of engineered systems that use ecological processes, to increase resiliency to climate change, manage other environmental hazards, or both. This may include but is not limited to floodplain and wetlands restoration or preservation, combining levees with restored natural systems to reduce flood risk, and urban tree planting to mitigate high heat days.

Other documents (Gov. Code 65302(g)(4)(D)(i), 65302(g)(4)(D)(ii) • If a city or county has adopted the local hazard mitigation plan, or other climate adaptation plan or document that fulfills commensurate goals and objectives and contains the information required pursuant to this paragraph, separate from the general plan, an attachment of, or reference to, the local hazard mitigation plan or other climate adaptation plan or document
• Cities or counties that have an adopted hazard mitigation plan, or other climate adaptation plan or document that substantially complies with this section or have substantially equivalent provisions to this subdivision in their general plans, may use with this section, or have substantially equivalent provisions, climate adaptation plan or document, specifically showing how each requirement of this subdivision has been met.

Gov Code 65302(g)(5)-
(g)(8)
Other Considerations

• Cities and counties that have floodplain management ordinances that have been approved by FEMA that substantially comply with this section, or have substantially equivalent provisions to this subdivision in their general plans, may use that information in the safety element to comply with this subdivision, and shall summarize and incorporate by reference into the safety element the other general plan provisions or the flood plain ordinance, specifically showing how each requirement of this subdivision has been met. • Prior to the periodic review of its general plan and prior to preparing or revising its safety element, each city and county shall consult the California Geological Survey of the Department of Conservation, the Central Valley Flood Protection Board, if the city or county is located within the boundaries of the Sacramento and San Joaquin Drainage District, as set forth in Section 8501 of the Water Code, and the Office of Emergency Services for the

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Statutory Citation Brief Description of Requirements
purpose of including information known by and available to the department, the agency, and the board required by this subdivision.
• To the extent that a county’s safety element is sufficiently detailed and contains appropriate policies and programs for adoption by a city, a city may adopt that portion of the county’s safety element that pertains to the city’s planning area in satisfaction of the requirement imposed by this subdivision.
• Review the safety element for fire and flood impacts upon each Housing Element update. • Review the safety element for climate change at each update to the Local Hazard Mitigation Plan, Jurisdiction may also choose to do a comprehensive review of the safety element upon each housing element update to streamline review.

HEALTH AND SAFETY ELEMENT
Planning for growth and development requires the consideration of a wide range of public safety issues.

Many of the health and safety risks associated with development, including risks to buildings and infrastructure, can be avoided through siting decisions made at the planning stages of development, while others may be lessened through the use of mitigation measures in the planning and land use review process. This element outlines Fresno County’s strategy for ensuring the maintenance of a healthy and safe physical environment. Applicable goals and policies are presented below.

Emergency Management and Response
Policies listed in the table below seek to create an effective emergency response and management system by ensuring that vital public infrastructure is designed to remain operational during and after a major disaster event, by siting critical emergency response facilities as far from potential disaster impact areas as is practical, and through continuing public education and outreach on emergency preparedness and disaster response programs.

Table 4. Fresno County Emergency Management and Response Goals Goal or
Policy Description
Goal HS-A To protect public health and safety by preparing for, responding to, and recovering from the effects of natural or technological disasters.

Policy A.1
The County shall, through the Fresno County Operational Area Master Emergency Services Plan and the Fresno County Multi-Hazard Mitigation Plan, maintain the capability to effectively respond to emergency incidents, including maintenance of an emergency operations center.

Policy HS-A.2
In coordination with cities, special districts, and other State and Federal agencies, the County shall maintain the Fresno County Multi- Jurisdictional Hazard Mitigation Plan to identify and mitigate, to the extent feasible, natural, and human-made hazards within the county.

Policy HS-A.3:

The County shall, within its authority and to the best of its ability, ensure that emergency dispatch centers, emergency operations centers, communications systems, vital utilities, and other essential public facilities necessary for the continuity of government are designed in a manner that will allow them to remain operational during and following an earthquake or other disaster.

Policy HS-A.4:

The County shall ensure that the siting of critical emergency response facilities such as hospitals, fire stations, sheriff’s offices and substations, dispatch centers, emergency operations centers, and other emergency service facilities and utilities are sited and designed to minimize their exposure and susceptibility to flooding, seismic and geological effects, fire, landslides, avalanche, and explosions as required by State regulations. This includes locating new essential public facilities outside of Very High Fire Hazard Severity Zones, if feasible. Exception to this policy shall be allowed on the condition that

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Goal or
Policy Description
the only alternative location would be so distant as to jeopardize the safety of the community, given that precautions are taken to protect the facility.

Policy HS-A.5 The County shall maintain coordination with other local, State, and Federal agencies to provide coordinated disaster response, especially to the most impacted populations in the County.

Policy HS-A.6:

The County shall support local fire agencies through distribution of information during the permit process, through links on County websites, and by providing assistance at public meetings, in promoting the education of County residents concerning emergency preparedness, defensible space, and safety, as described in the Fresno-King Unit Fire-Plan information and public education outreach programs, focusing on the most vulnerable at-risk communities such as those in the Very High Fire Hazard Severity Zone.

Policy HS-A.7
The County shall review the design of all buildings and structures in the Very High Fire Hazard Severity Zones and State Responsibility Areas to ensure they are designed and constructed to State and local regulations and standards as part of the building permit plan check process.

Policy HS-A.8
The County shall continue to improve community transportation corridors to allow for effective evacuation routes for the public and effective access for emergency responders, including in areas that lack more than two emergency access routes.

Policy HS-A.9 The County shall prevent and control the spread of vector-borne diseases through best practice vector control techniques on County properties and will encourage use of these practices on other properties.

Policy HS-A.10
The County, as part of its five-year Capital Improvement Plan, shall conduct an evaluation of all County facilities including those operated by County first responders to determine retrofits that may be needed for long-term resilience to climate change hazards including wildfire and drought.

Policy HS-A.11
The County shall invest in sustainable backup power sources as funding becomes available to provide redundancy and continued services for critical facilities in the event of a power outage triggered by a climate event.

Policy HS-A.12
Establish minimum standards for evacuation, including in the Very High Fire Hazard Severity areas, in the Emergency Operations Plan and continuously reassess access and evacuation route capacity and put mitigation measures and improvement plans in place if needed.

Policy HS-A.13 The County shall periodically evaluate the ability of County facilities to function after a major disaster as well as project and assess future emergency needs.

FIRE HAZARDS
Policies in this section and in Table 68. Fresno County Fire Hazard Goals and Policies are designed to ensure that new developments are constructed to minimize potential fire hazards, minimize the risk of fire in already developed areas, and to provide public education concerning fire prevention.

Table 68. Fresno County Fire Hazard Goals and Policies
Goal or
Policy Description
Goal HS-B: To minimize the risk of loss of life, injury, and damage to property and natural resources resulting from fire hazards.

Policy HS-B.1: The County shall review project proposals to identify potential fire hazards and to evaluate the effectiveness of preventive measures to reduce the risk to life and property.

Policy HS-B.2:

The County shall ensure that development in high fire hazard areas is designed and constructed in a manner that minimizes the risk from fire hazards by increasing resistance of structures to heat, flames, and embers. The County shall review current building code standards and other applicable statutes, regulations, requirements, and guidelines regarding construction, and specifically the use and maintenance of non-flammable materials (both residential and commercial) and consider adopting

4. Risk Assessment
2024 Fresno County Hazard Mitigation Plan
May 2024 252
Goal or
Policy Description
amendments to Title 15 of the County Ordinance Code (Building and Construction) to implement appropriate standards. Special consideration shall be given to the use of fire- resistant construction in the underside of eaves, balconies, unenclosed roofs and floors, and other similar horizontal surfaces in areas of steep slopes.

Policy HS-B.3: The County shall coordinate with telecommunication service entities to fire-harden communications.

Policy HS-B.4:

The County shall require that new discretionary development including residential subdivisions and large commercial proposals in high-fire- hazard areas have fire-resistant vegetation, cleared fire breaks separating communities or clusters of structures from native vegetation, or a long-term comprehensive vegetation and fuel management program. Fire hazard reduction measures shall be incorporated into the design development projects in fire hazard areas.

Policy HS-B.5:

In consultation with the local fire agency and CalFire, the County shall require structures to be sited to maximize low-flammability landscape features to buffer against wildfire spread. Consultation with the local fire agency will be necessary to make this determination.

Policy HS-B.6:

The County shall require that new foothill and mountain subdivisions and residential areas in Very High Fire Hazard Severity Zones provide for safe and ready access for fire and other emergency equipment, for routes of escape that will safely handle evacuations, and for roads and streets designed to be compatible with topography while meeting fire safety needs.

Fresno City CouncilMay 21, 2026

Fresno City Council
May 21, 2026