Atwater City Council
June 22, 2026

Merced County Multi-Jurisdictional Hazard Mitigation Plan Community Profile and Capability Assessment
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2 COMMUNITY PROFILE AND CAPABILITY ASSESSMENT

2.1 History
An expedition led by Gabriel Moraga in 1806 came upon a river he named El Rio de Nuestra Señora de la Merced (River of Our Lady of Mercy), or Merced River in which derived the name of the County. During a period between 1841 and 1844, while California was a province of independent Mexico, four Mexican land grants were made which eventually became Merced County. The County was created by the Act of April 19, 1855 and included parts of Mariposa County. Parts of the territory were also given to Fresno County in 1856. Merced County’s current boundaries and its location within the State of California is shown in Figure 2-1 below.

The early economy of the County centered on ranching and farming. Settlement in Merced County remained modest throughout much of the county's first century. Merced County is considered to be located in the world’s most productive agricultural area, which, today, is a major source of employment, along with food processing, retailing, and light manufacturing.

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Figure 2-1 County of Merced Planning Area

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2.2 Geography and Climate
Merced County encompasses approximately 2,000 square miles, ranking it the 25th largest out of a total of 58 counties in California. It is located in the heart of the San Joaquin Valley, north of Fresno and southeast of San Jose, and spans from the coastal ranges to the foothills of Yosemite National Park. The City of Merced is the County seat and offers a small community atmosphere, residential neighborhoods characterized by wide, tree-lined streets, and homes in a wide economic range.

The County of Merced is neighbored by the counties of Tuolumne County and Mariposa County to the northeast, Madera County to the south and east, Fresno County to the southeast, San Benito County to the southwest, Santa Clara County to the west, and Stanislaus County to the northwest.

Merced County is home to two national protected areas – Merced National Wildlife Refuge and San Luis National Wildlife Refuge. The former Castle Air Force Base and the United States Penitentiary-Atwater are located in an unincorporated area near Atwater. The Board of Supervisors is the governing body for Merced County.

Elevation in Merced County, according to data gathered by the Shuttle Radar Topography Mission ranges from 6 feet above mean sea level (msl) ranking it 20 in terms of lowest elevations when compared to a total of 58 counties in California, to 1,781 feet above msl ranking it 54 in terms of highest elevation when compared to a total of 58 counties in California. The rivers in this region include the Merced and Chowchilla, which are both tributaries of the San Joaquin River. On average, there are 263 sunny days per year in Merced County. The number of days with any measurable precipitation is 49 with an average of approximately 12 inches of rain per year. The month of July is the warmest month with an average high around 96 degrees. The month of January is the coolest month with an average low of 37 degrees.

2.3 Economy
Merced County is located in the heart of California’s rapidly growing San Joaquin Valley, the richest agricultural area in the world. With that distinction also come the challenges of an economy which has historically been dependent on seasonal agriculture and low wages. Select 2019 economic characteristics estimated for Merced County by the U.S. Census Bureau American Community Survey (ACS) are shown in Table 2-1.

Table 2-1 Merced County Economic Characteristics
Merced County
Families Below Poverty Level 17.2%
Individuals Below Poverty Level 21.2%
Median Home Value $252,700
Median Household Income $53,672
Per Capita Income $23,011
Population >16 Years Old in Labor Force 59.6%
Population Employed 52.6%
Source: U.S. Census Bureau ACS 2015-2019 5-Year Data Profile Merced County provides a broad range of services to its residents, businesses, and visitors, and manages and operates its facilities to meet community needs. Agriculture is the foundation of Merced County’s economy, and the County consistently ranks as one of California’s top five producers of milk and cream,

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chickens, almonds, alfalfa, cattle and calves, silage, and tomatoes. Merced County is home to four agricultural processing facilities that are among the largest of their kind in the world: Ernest and Julio Gallo winery, Hilmar Cheese production facility, Ingomar Packing Company tomato processing plant, and Foster Farms poultry processing facility. The ACS 5-Year data profiles also provide estimates for total employment by industry sector. These employment trends are shown below in Table 2-2.

Table 2-2 Merced County Employment by Industry Sector
Industry Sector Percent of Workforce
Educational services, and health care and social assistance 21.60% Agriculture, forestry, fishing and hunting, and mining 12.90% Manufacturing 11.30%
Retail trade 11.20%
Arts, entertainment, and recreation, and accommodation and food services 7.80% Construction 7.10%
Professional, scientific, and management, and administrative and waste management services

6.20%
Transportation and warehousing, and utilities 5.90%
Other services, except public administration 4.50%
Public administration 4.50%
Wholesale trade 3.20%
Finance and insurance, and real estate and rental and leasing 2.90% Information 0.90%
Source: U.S. Census Bureau ACS 2015-2019 5-Year Data Profile

2.4 Population
The total estimated population of Merced County in 2019 was 271,382 up from 255,793 people in 2010.

This constitutes an approximately 6% increase in population since the last census. Table 2-3 and Table 2-4 show several key demographic and social characteristics of Merced County, how those characteristics have changed over the last five years, and how those characteristics compare to the rest of the state and nation. Increases in population growth also increase exposure to severe weather-related hazards, pandemic/epidemics as well as earthquakes. This increase in growth also puts more demand on water resources and can increase vulnerability to drought.

Table 2-3 Merced County Demographic and Social Characteristics, 2015-2019 Merced County 2015 2019 % Change
Population 263,885 271,382 2.84%
Median Age 30.4 31.1 2.30%
Total Housing Units 84,063 85,251 1.41%
Housing Occupancy Rate 92.40% 93.80% 1.52%
% of Housing Units with no Vehicles
Available 7.50% 6.90% -8.00%
Median Home Value $161,200 $252,700 56.76%
Unemployment 9.70% 7.10% -26.80%
Mean Travel Time to Work (minutes) 26.1 28.6 9.58%
Median Household Income $42,462 $53,672 26.40%
Per Capita Income $18,204 $23,011 26.41%

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Merced County 2015 2019 % Change
% of Individuals Below Poverty Level 26.10% 21.20% -18.77% # of Households 77,692 80,008 2.98%
Average Household Size 3.32 3.32 0.00%
% of Population Over 25 with High School
Diploma 67.90% 69.10% 1.77%
% of Population Over 25 with Bachelor’s
Degree or Higher 13.10% 13.80% 5.34%
% with Disability 15.70% 13.00% -17.20%
% Speak English less than "Very Well" 22.80% 22.70% -0.44% Source: U.S. Census Bureau ACS 5-Year Data Profiles, 2015-2019 Table 2-4 Demographic and Social Characteristics Compared to the State and Nation Demographic & Social Characteristics (as of 2019) County California U.S.

Median Age 31.1 36.5 38.1
Housing Occupancy Rate 93.80% 92.00% 87.90%
% of Housing Units with no Vehicles Available 6.90% 7.10% 8.60% Median Home Value $252,700 $505,000 $217,500
Unemployment 7.10% 3.80% 3.40%
Mean Travel Time to Work (minutes) 28.6 29.8 26.9
Median Household Income $53,672 $106,916 $62,843
Per Capita Income $23,011 $36,955 $34,103
% of Individuals Below Poverty Level 21.20% 13.40% 13.40% Average Household Size 3.32 2.95 2.62
% of Population Over 25 with High School Diploma 69.10% 83.30% 88.00% % of Population Over 25 with bachelor’s degree or Higher 13.80% 33.90% 32.10% % with Disability 13.00% 10.60% 12.60%
% Speak English less than "Very Well" 22.70% 17.80% 8.40% Source: U.S. Census Bureau ACS 5-Year Data Profiles, 2015-2019 Table 2-5 breaks down the demographics of the county by sex and race.

Table 2-5 Merced County Demographics by Race and Sex
Merced County Population %
Total Population 271,382 ---
Male 136,987 50.50%
Female 134,395 49.50%
Hispanic or Latino 161,814 59.6%
White alone 75,037 27.6%
Black alone 7,812 2.9%
Asian alone 19,650 7.2%
American Indian and Alaska Native alone 931 0.3%
Native Hawaiian and Other Pacific Islander alone 607 0.2% Some other race alone 226 0.1%
Two or more races alone 5,305 2.0%
Source: U.S. Census Bureau ACS 5-Year Data Profiles, 2015-2019

2.5 County’s Mitigation Capabilities
The following section assesses the County’s and each participating jurisdictions’ existing capabilities to pursue hazard mitigation. The capability assessment analyzes Merced County’s capabilities that can be leveraged to mitigate hazards. Combining the risk assessment with the mitigation capability assessment

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results in the County’s “net vulnerability” to disasters, and more accurately focuses the goals, objectives, and proposed actions of this plan.

The Hazard Mitigation Planning Team (HMPT) used a two-step approach to conduct this assessment for the County and jurisdictions. 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 HMPT conducted an inventory and review of 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.

This assessment is divided into four sections: regulatory mitigation capabilities; administrative and technical mitigation capabilities; fiscal mitigation capabilities; and mitigation outreach and partnerships.

Additional information on jurisdiction capabilities can also be found in the participating jurisdiction’s annexes.

2.5.1 Regulatory Mitigation Capabilities
The regulatory and planning capabilities table lists planning and land management tools typically used by local jurisdictions to implement hazard mitigation activities and indicate those that are in place in Merced County. Table 2-6 identifies the planning and land management tools typically used by local jurisdictions to implement hazard mitigation activities and indicates those that are in place in Merced County.

Table 2-6 Regulatory Mitigation Capabilities
Regulatory Tool
(ordinances, codes,
plans)
Merced
County Atwater Dos Palos Gustine Livingston
Los Banos Merced
General Plan Yes Yes Yes Yes Yes Yes Yes
Zoning ordinance Yes Yes Yes Yes Yes Yes Yes
Subdivision ordinance Yes Yes Yes Yes Yes Yes Yes
Growth management
ordinance Yes No Yes No
Floodplain ordinance Yes Yes No No Yes Yes Yes
Other special purpose
ordinance (storm water,
steep slope, wildfire) Yes N/A N/A No
Yes, Fire
Protection
Ordinance
Yes, Storm
Water
Pollution
Plan
N/A
Building code Yes Yes Yes Yes Yes Yes Yes
Fire department ISO
rating Yes Yes, Rating 3
Yes Yes Yes, Rating
5 Yes, Rating
3 Yes, Rating
2 Erosion or sediment
control Yes N/A No No No Yes Yes
Storm water
management program
Yes Yes Yes Yes Yes Yes Yes
Site plan review
requirements Yes Yes Yes Yes Yes Yes
Capital improvements
plan Yes Yes Yes Yes Yes Yes Yes
Economic development
plan Yes Yes Yes Yes Yes Yes Yes
Local Emergency
Operations Plan Yes Yes Yes Yes Yes Yes Yes
Other special plans N/A N/A n/a No No Yes N/A

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Regulatory Tool
(ordinances, codes,
plans)
Merced
County Atwater Dos Palos Gustine Livingston
Los Banos Merced
Flood insurance study or
other engineering study
for streams
Yes Yes No -
NSFHA Yes Yes N/A Yes
Elevation certificates (for
floodplain development) Yes No No No No N/A Yes
Source: HMPT
Related Plans and Regulations
Merced County General Plan, 2013 - A comprehensive 2030 Merced County General Plan was adopted December 2010. This General Plan defines the County’s goals, objectives and policies that guide the physical growth, use and development of land under the jurisdictional authority of the County through the year 2030. The General Plan may address other topics that the community deems relevant to its development, such as economic development, historic preservation, and urban design. There are five principles highlighted as the core issues facing the Merced County community in the adoption of the General Plan: Agriculture, Economic Development, Environmental Quality, Public Facilities and Services, and Transportation. The County also promotes their public safety goals through the Health and Safety Element, among their ten other General Plan elements.

The purpose of the Public Health and Safety Element is to reduce or eliminate long-term risk to people and property from natural or human caused hazards. Traditionally viewed as an element that focuses on planning for catastrophes, this element is now expanded to include community health and community safety related issues that are more commonly associated with the built environment as affecting the health and safety of residents living within the County. The Element also covers goals and policies focused on geologic and seismic hazards, flood hazards, fire hazards, airport safety, hazardous materials, climate adaptation, noise, and environmental justice.

Merced County Emergency Operations Plan, 2013 - The Emergency Operations Plan addresses the planned response to emergency situations associated with natural disasters, technological incidents, human caused events and national security emergencies in or affecting Merced County. The plan establishes the emergency management organization required to mitigate any significant emergency or disaster affecting Merced County; identifies the policies, responsibilities, and procedures required to protect the health and safety of communities, public and private property, and the environmental effects of natural, human caused and technological emergencies and disasters; and establishes the operational concepts and policies for disaster response and recovery.

County of Merced Fire Management Plan –The County of Merced reorganized their Fire Department and entered into a Cooperative Fire Protection Agreement with the California Department of Forestry and Fire Protection (CAL FIRE) for the provision of fire protection services. The contract began in 1988. The CAL FIRE agreement provides daily staffing at fire stations, dispatch, management, incident command, training, investigation and fire prevention activities. Through the Cooperative Agreement CAL FIRE also manages the Office of Emergency Services for the County. The County’s Fire Management Plan is a product of the implementation of the State Fire Plan. The State Fire Plan provides an analysis procedure utilizing, in part, computer based geographical information data that is validated by experienced fire managers to assess fire fuel hazards and risks in order to design and implement mitigating activities. The Fire Management Plan provides background information, fuels and fire data, proposed projects, and individual Battalion reports outlining mitigating activities commonly carried out each year.

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Madera-Mariposa-Merced Unit (MMU) 2020 Strategic Fire Plan – The MMU Strategic Fire Plan is an annual fire plan establishing goals and priorities that align with CAL FIRE’s Strategic Plan and the California Fire Plan, while also identifying goals and priorities specific to the Unit. The California Fire Plan is the road map for reducing the risk of wildfire in California, where as the MMU Strategic Fire Plan identifies strategic goals and objectives that target the anticipation and reduction of wildfire within the boundaries of the Unit. For the challenges facing the Unit, such as extreme heat, tree mortality, and drought conditions across the three counties, the plan addresses problem areas and risk. This plan also seeks to improve operational effectiveness, budgetary and fiscal circumstances, foster a healthy ecosystem, and improve firefighter safety by identifying working projects specific to each Battalion within the MMU.

Emergency Services Ordinance, Chapter 2.72 - The purposes of this ordinance are to provide for the preparation and implementation of plans for the protection of people and property within the County in the event of an emergency; the direction of the emergency organization; and the coordination of the emergency functions of the County with the cities in the County and with all other public agencies, corporations, organizations, and affected private persons. The ordinance establishes the Merced Operational Area Council and designates the membership of the council. The council’s powers include the development of emergency and mutual aid plans and agreements and the ordinances and resolutions to implement them.

Fire Mitigation Ordinance Chapter 9.24 – The purpose of this ordinance is to impose a fee on new buildings and improvement projects because they contribute to the increase for potential fire danger in Merced County, it is in the best interest of the citizens of the County and promotes and protects the health and welfare of the residents of Merced County. It is necessary that persons who carry out such projects within the County pay a reasonable fee to mitigate such fire danger.

Floodplain Management Ordinance Chapter 18.30 - It is the purpose of the ordinance to promote the public health, safety, and general welfare, and to minimize public and private losses due to flood conditions in specific areas by legally enforceable regulations applied uniformly throughout the community to all publicly and privately owned land within flood prone, mudslide [i.e. mudflow] or flood related erosion areas. These regulations are designed to:
● Protect human life and health;
● Minimize expenditure of public money for costly flood control projects; ● Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
● Minimize prolonged business interruptions;
● Minimize damage to public facilities and utilities such as water and gas mains; electric, telephone and sewer lines; and streets and bridges located in areas of special flood hazard; ● Help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize future blighted areas caused by flood damage; ● Ensure that potential buyers are notified that property is in an area of special flood hazard; and ● Ensure that those who occupy the areas of special flood hazard assume responsibility for their actions.

Merced Groundwater Subbasin Groundwater Sustainability Plan – The Sustainable Groundwater Management Act (SGMA) requires the formation of local Groundwater Sustainability Agencies (GSAs) to oversee the development and implementation of Groundwater Sustainability Plans (GSPs). The goal of the GSPs is to achieve sustainable management of the State’s groundwater basins. The purpose of the Merced Groundwater Subbasin GSP is to bring the Merced Groundwater Basin (Merced Subbasin), a critically over drafted basin located within the San Joaquin Valley, into sustainable groundwater management by 2040.

This subbasin is heavily reliant on groundwater and the County water users recognize the basin has been in overdraft. This plan is the outcome of collaboration among the County of Merced and numerous water

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districts and cities within the Merced Subbasin. The 2019 GSP outlines how the GSAs will achieve sustainable groundwater management on a long-term basis by increasing recharge and reducing groundwater pumping through various implementation programs and projects.

Merced Integrated Regional Water Management Plan. The Merced Integrated Regional Water Management Plan (IRWMP) is the first IRWMP for the Merced Region. The plan was developed as a multistakeholder process that builds on the Region’s history of collaboration on water resource management issues. The IRWMP is a water resources planning document for the Region and serves as a blueprint for water resources management. It was developed based on Proposition 84 IRWM program guidelines and from input from a Regional Advisory Committee. Similar to the GSP, the IRWMP establishes several objectives and performance measures selected to provide long-term direction towards meeting project goals related to managing flood flows for public safety, water supply, recharge, and natural resource management; meeting water demands (agriculture, urban, and environmental needs); correcting groundwater overdraft conditions; and improving coordination of land use and water resource planning.

The IRWMP also includes objectives that address water use efficiency, water quality, natural resource management, water-related needs of disadvantaged communities, recreation opportunities, climate change adaptation and mitigation; and public outreach and enhancing communication among stakeholders in the Region.

2.5.2 Administrative and Technical Mitigation Capabilities Table 2-7 below identifies the county personnel responsible for activities related to mitigation and loss prevention in Merced County and the unincorporated areas. Many positions are full time and/or filled by the same person. A summary of technical resources follows.

Table 2-7 Merced County Administrative and Technical Mitigation Capabilities Personnel Resources Yes/No Department/Position
Planner/engineer with knowledge of land
development/land management practices
Yes Public works/ Deputy Director Roads
Engineer/professional trained in construction
practices related to buildings and/or infrastructure
Yes Public works/ Deputy Director Roads
Planner/engineer/scientist with an understanding
of natural hazards
Yes Public works/ Deputy Director Roads
Personnel skilled in Geographic information
systems (GIS)
No
Full time building official Yes Community and Economic development Building Division
Floodplain manager Yes Community and Economic development Building Division
Emergency manager No Office of Emergency Services (OES) Grant writer Yes
Other personnel N/A
GIS Data Resources
(Hazard areas, critical facilities, land use, building
footprints, etc.)
No
Warning Systems/Services
(Reverse 9-11, cable override, outdoor warning
signals)
Yes OES
Other N/A
Source: HMPT

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Office of Emergency Services
The Merced Office OES provides preparedness before, and coordination direction during, large-scale emergencies and disasters. Merced OES coordinates with partner agencies including the six incorporated cities within the county, special districts, and key private agencies in providing planning, response, recovery, and mitigation activities as a result of disaster related incidents.

Merced County, in conjunction with the cities of Merced, Los Banos, Livingston, Gustine, Dos Palos, emergency fire, law enforcement, health, and Emergency Medical Service agencies, launched the Emergency Notification System (ENS) – a technical capability service allowing residents throughout the entire county to be alerted of an emergency or an important community alert in their area. The improved Merced County ENS will allow residents throughout the County alternate ways of being contacted during an emergency, such as cell phones, business phones, home phones, emails, text messages or hearingimpaired receiving devices. More importantly, individuals can choose how they will be notified and in what preference order. When an emergency message is issued about a potential safety hazard or concern, messages will be sent to all standard voice and text communication devices registered in the system, including home phones, cell phones, email, and more. Residents and businesses with listed telephone numbers are already included in the system. Those residents having only a cell phone or wanting to be contacted through different methods can provide the information using the registration link at www.co.merced.ca.us/alert.

Merced County Fire Department
The primary mission of the Merced County Fire Department is to provide a range of programs aimed at protecting the lives and property of the people of Merced County from the adverse effects of fires, sudden medical emergencies, exposure to hazardous materials, or other dangerous conditions. The programs maintained by the department include:
● Comprehensive fire protection planning
● Fire prevention education
● Fire law and code enforcement
● Suppression and recovery
The Merced County Fire Department provides first responder-level Emergency Medical Services (EMS), including rescue and extrication, as well as control and mitigation of hazardous materials emergency incidents. The Merced County Fire Department personnel and equipment are also available to provide mutual aid fire/rescue/EMS services to cooperating agencies and participate in the statewide fire and rescue mutual aid system.

In addition, assistance and support are also provided for other non-fire emergencies such as floods, earthquakes, and other disasters.

Extreme Heat Preparedness
The County of Merced manages extreme heat events by providing cooling zones and centers for County residents. When the heat index is expected to exceed 105 degrees, various cooling centers in the County were opened to help residents cope with the extreme temperatures. Cooling centers were open during the summer months of 2021 in six of the participating jurisdictions, and at 12 Merced County libraries. In events of extreme heat, the County OES provides public notification alerts to residents with information on the location and hours of operations of cooling centers throughout the County. Transportation to these centers is also often provided free of charge. Additional information on health and safety measures for residents is also provided. Public notifications flyers distributed during the summer of 2021 are shown below.

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Figure 2-2 Public Notification for Extreme Heat and Safety Preparedness Source: Merced County Public Information Officer 2021

2.5.3 Fiscal Mitigation Capabilities
The following table identifies financial tools or resources that the county could potentially use to help fund mitigation activities. There are currently no specific funding sources for hazard mitigation.

Table 2-8 Merced County Financial Capabilities
Financial Resources Accessible/
Eligible to Use
Comments/Has this been used for
mitigation in the past?
Community Development Block Grants Yes No
Capital improvements project funding Yes No
Authority to levy taxes for specific
purposes
Yes Has not been used. Must be approved by
voters.

Fees for water, sewer, gas, or electric
services, new development
Yes Has not been used. Services provided through
cities or districts and levied through property
assessments
Incur debt through general obligation
bonds
Yes No
Incur debt through special tax bonds Yes Has not been used. Must be approved by twothirds voters.

Incur debt through private activities Yes Has not been used. Do not have any in place.

Federal Grant Programs (HMGP) Yes Has not been used. Various departments in Merced County are eligible.

Source: Planning Team

2.5.4 Other Mitigation Programs and Partnerships
Table 2-9 below summarizes some of the mitigation partnerships and education or outreach capabilities available to Merced County.

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Table 2-9 Merced County Education and Outreach Capabilities Education & Outreach Yes/No Comments
Local Citizen Groups That
Communicate Hazard Risks Yes See below
Firewise USA No 6 communities within the county are Firewise communities StormReady Yes UC Merced is a participant
Other
American Red Cross: The American Red Cross identified several capability enhancements through collaboration with the county, cities, and fire departments of Merced County. Programs such as outreach campaigns for preparedness education, continuing shelter inspections, and updating existing points of contact for shelter sites. These efforts will improve the American Red Cross’ ability to conduct mitigation, preparedness, and response efforts in Merced County.

2.5.5 Opportunities for Enhancement
The 2021 MJHMP update provided the County and the participating jurisdictions an opportunity to review and update the capabilities currently in place to mitigate hazards. This also provided an opportunity to identify where capabilities could be improved or enhanced. Specific opportunities could include:

Plan Updates: Merced County has identified several plans which could be updated, such as the County Emergency Operations Plan, Disabled, Access, and Functional Needs plans, and the Flood Annex to the EOP. During the update process of each of these plans there is an opportunity to reference the MJHMP and enhance the capabilities for implementation of goals and objectives of each plan. The City of Livingston has also identified potential updates to their Emergency Response and Disaster Plan. The City of Merced identified an update to the Water System Response Plan, which would meet the requirements of the America’s Water Infrastructure Act. As mentioned above, updates to related plans such as these provide an opportunity to both build resilience and enhance the cross-plan integration of the MJHMP.

Training: Provide training opportunities to help inform County staff on how best to integrate hazard information and mitigation projects into their departments. Merced County has identified a multi-year training and exercise plan which would cover all county departments. The City of Los Banos has identified an inter-departmental training effort to be undertaken. The City of Dos Palos has also identified providing opportunities for Incident Command System training for city staff.

Firewise: Firewise USA® is a voluntary program that provides a framework to help neighbors get organized, find direction, and take action to increase the ignition resistance of their homes and community. The program is co-sponsored by the USDA Forest Service, the U.S. Department of the Interior, and the National Association of State Foresters. As of June 2021, neither Merced County nor any of the incorporated jurisdictions in the county were participants in the program. In order to become a Firewise USA site, a neighborhood, community, city, or county must form a board or committee comprised of residents and stakeholders, obtain a written wildfire risk assessment, develop and maintain an action plan, and contact the applicable state liaison to the program.

Storm Ready: As of June 2021, neither Merced County nor any of the incorporated jurisdictions in the county are certified as Storm Ready communities. The UC Merced is certified Storm Ready. The National Weather Service’s Storm Ready program helps local governments handle extreme weather and improve the timeliness and effectiveness of hazardous weather-related warnings for the public. To be officially Storm Ready, a community must:
● Establish a 24-hour warning point and emergency operations center ● Have more than one way to receive severe weather warnings and forecasts and to alert the public

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● Create a system that monitors weather conditions locally ● Promote the importance of public readiness through community seminars, and ● Develop a formal hazardous weather plan, which includes training severe weather spotters and holding emergency exercises
Community Rating System (CRS): An additional indicator of floodplain management capability is the active participation of local jurisdictions in the CRS. The CRS is an incentive-based program that encourages counties and municipalities to undertake defined flood mitigation activities that go beyond the minimum requirements of the NFIP, adding extra local measures to provide protection from flooding.

All of the 18 creditable CRS mitigation activities are assigned a range of point values. As points are accumulated and reach identified thresholds, communities can apply for an improved CRS class. Class ratings, which run from 10 to 1, are tied to flood insurance premium reductions. As class ratings improve (decrease), the percent reduction in flood insurance premiums for NFIP policy holders in that community increases. These potential discounts in flood insurance premiums through CRS are summarized in Table 2-10 below. As of 2021 neither Merced County nor any of the incorporated jurisdictions in the county participate in the CRS. Should the City of Merced and Merced County decide to join the CRS, it would be an opportunity for enhancement of existing mitigation capabilities and help make flood insurance more affordable in the future.

Table 2-10 CRS Premium Discounts
Class Discount Class Discount SFHA (Zones A, AE, A1-A30, V, V1-V30, AO, and AH): Discount varies depending on class. SHFA (Zones A99, AR/A, AR/AE.

AR/A1-A30, AR/AH, and AR/AO): 10% discount for Classes 1-6; 5% discount for Classes 7-9. Non-SFHA (Zones B, C, X, D): 10% discount for Classes 1-6; 5% discount for Classes 7-9. In determining CRS premium discount, all AR and A99 Zones are treated as non-SFHAs.
1 45% 6 20%
2 40% 7 15%
3 35% 8 10%
4 30% 9 5%
5 25% 10 --
Source: FEMA CRS Coordinators Manual
Financial Capability Improvements: There are several financial resources listed in Table 2-8 that the County could leverage in the future for funding mitigation efforts. In particular, the LHMP provides eligibility for the FEMA HMA grants. County OES staff can attend workshops and trainings regarding the grant application process and how to develop successful grant applications under the HMGP. The California Office of Emergency Services (Cal OES) periodically hosts related trainings and webinars.

Understanding the types of projects that can be funded, and the components of a successful application will enhance chances of a successful grant award.

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3 PLANNING PROCESS
Requirement §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:
(1) An opportunity for the public to comment on the plan during the drafting stage and prior to plan approval;
(2) 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
(3) 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.

3.1 Background on Mitigation Planning in Merced County
The primary purpose of the Merced County MJHMP update is to reduce or eliminate long-term risk to people and property from natural hazards and their effects on the Merced County planning area. Merced County recognized the need and importance of a LHMP and initiated its development in 2013 after receiving a grant from FEMA, which also served as the primary funding source for this plan.

The plan underwent a comprehensive update in 2021. The planning process followed during the update was similar to what was used in the original plan development. This planning process utilized the input from a multi-jurisdictional HMPT. A significant change from the 2014 Plan is the inclusion of all of the incorporated communities within the planning area (six), versus three in the previous update. Wood Environment & Infrastructure Solutions, Inc. (Wood) was procured to assist with the update in 2021. The process is described further in this section and documented in Appendix B.

3.2 What’s New in the Plan Update
DMA Requirement §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 MJHMP complies with FEMA guidance and California Office of Emergency Services guidelines for LHMPs. The update followed the requirements noted in the DMA of 2000 and FEMA’s 2013 Local Hazard Mitigation Planning Handbook.

This MJHMP update involved a comprehensive review and update of each section of the 2014 plan and includes an assessment of the progress in evaluating, monitoring and implementing the mitigation strategy outlined in the initial plan. The planning process provided an opportunity to review jurisdictional priorities related to hazard significance and mitigation actions, and revisions were made where applicable

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to the plan and the municipal annexes. Another major change in priority was the desire to include all incorporated jurisdictions in the County, including new annexes for the municipalities of Dos Palos, Gustine and Merced. Only the information and data still valid from the 2014 plan was carried forward as applicable into this MJHMP update.

3.2.1 Plan Section Review and Analysis – 2021 Update
During the 2021 plan update, the HMPT updated each of the sections of the previously approved plan to include new information. Wood developed a summary of each section in the plan and guided the HMPT through the elements that needed updating during the kickoff webinar in December 2020. This included analyzing each section using FEMA’s local plan update guidance (2013) to ensure that the plan met the latest requirements. In addition, the FEMA Local Mitigation Plan Review Tool that was provided with the approval of the 2014 version of this plan was referenced, in particular the 2014 FEMA comments on opportunities for improvement were considered and addressed in the 2021 update. The HMPT and Wood determined that nearly every section of the plan would need revision to align the plan with the latest FEMA planning guidance and requirements and recent California legislation. A summary of the changes in this plan update is highlighted in the table below.

Table 3-1 Merced County Hazard Mitigation Plan Update Highlights Plan Section Summary of Plan Review, Analysis, and Updates

1. Introduction Revised to reflect updated plan and 2021 planning process

2. County Profile and
Capability Assessment
Updated with recent census data and current economy description Updated land use and development trends

3. Planning Process
Describes and documents the planning process for the 2019 update, including coordination among agencies
Describes how 2014 plan was integrated with/into other planning efforts.

Removed 2014 planning process info.

Describes changes to jurisdictional participation
Describes 2021 public participation process
Describes the Hazard Mitigation Planning Committee
Describes the 10-step process followed for the update

4. Hazard Identification
and Risk Assessment
Drought is now profiled as separate hazards and are no longer part of Severe Weather Discussion on levee failure has been added to Flood
Climate change information has been added to each hazard profile 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. 2014 Plan on Vulnerability Assessment is now included with the Risk Assessment section as subsections by hazard.

Updated critical facilities identified from the 2014 plan.

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 Digital Flood Insurance Rate Map (DFIRM) and assessor’s data.

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Plan Section Summary of Plan Review, Analysis, and Updates Updated National Flood Insurance Program (NFIP) data and Repetitive Loss structure data from the previous plan.

Incorporated new hazard loss estimates since 2014, 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.

Revisited and updated hazard significance/priority levels.

Updated maps in plan where appropriate.

5. Mitigation Strategy
Indicated what actions have been implemented that may reduce previously identified vulnerabilities.

Updated mitigation strategy based on the results of the updated risk assessment, completed mitigation actions, and implementation obstacles and opportunities since the completion of the 2014 plan.

Reviewed and updated goals and objectives based on HMPT input.

Included updated information on how actions are prioritized, or how priorities changed.

Reviewed mitigation actions from the 2014 plan and developed a status report for each; identified if actions have been completed, deleted, or deferred/carried forward.

Updated priorities on actions.

Identify examples of successful implementation to highlight positive movement on actions identified in 2014 plan.

Identified new mitigation actions proposed by the HMPT with more detail on implementation than the previous plan.

Developed a summary table of mitigation actions for all participating jurisdictions.

6. Plan Review,
Evaluation and
Implementation
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.

Added a process for incorporation of the HMP into existing mechanisms

7. Plan Adoption Updated to reflect 2021 process.

Jurisdictional Annexes
*Developed annexes for new participating jurisdictions in 2021.

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 2016 and added new mitigation actions.

Updated and integrated the following existing and new annexes:

A City of Atwater
B City of Dos Palos*
C City of Gustine*
D City of Livingston
E City of Los Banos
F City of Merced*
Appendices Appendix A: Planning Team

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Plan Section Summary of Plan Review, Analysis, and Updates Appendix B: Planning Process Documentation
Appendix C: Approval and Adoption
Appendix D: Mitigation Categories and Alternatives
Appendix E: Annual Progress Meeting Agenda and Report Template Appendix F: Outreach Strategy

3.3 Multi-Jurisdictional Participation
In the 2021 MJHMP update, the following jurisdictions participated in the planning process and will be adopting the updated plan following FEMA approval. All incorporated cities in the County participated in this planning process. As noted previously, the cities of Dos Palos, Gustine, and Merced are new to the multi-jurisdictional planning process.

Lead Jurisdiction:
● Merced County
Municipalities:
● City of Atwater
● City of Dos Palos
● City of Gustine
● City of Livingston
● City of Los Banos
● City of Merced
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 HMPT
● 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 Merced County planning area’s HMPT, “participation” meant the following:
● Providing facilities for meetings
● Attending and participating in the HMPT meetings
● Completing and returning Wood Plan Update Guide worksheets ● Collecting and providing other requested data (as available) ● Identifying mitigation actions for the plan
● Reviewing and providing comments on plan drafts and jurisdictional annexes ● 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 multi-jurisdictional webinars/meetings described in Table 3-3 Schedule of Planning Meetings and brought together a local planning team to help collect data, identify mitigation actions and implementation

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strategies, and review and provide data on annex drafts. In some cases, the jurisdictions had limited capacity to attend or had conflicts with HMPT meetings; in these cases, alternative forms of communication were used to provide input into the process, and some instances a representative from a different jurisdiction’s department attended the HMPT meeting on behalf of the main representative.

Appendix B provides additional information and documentation of the planning process.

3.4 Planning Process
Wood established the planning process for the Merced County MJHMP using the DMA planning requirements and FEMA’s associated guidance. The original FEMA planning guidance is structured around a four-phase process:
● Organize Resources
● Assess Risks
● Develop the Mitigation Plan
● Implement the Plan and Monitor Progress
Into this process, Wood integrated a more detailed 10-step planning process used for FEMA’s CRS and FMA programs. Thus, the modified 10-step process used for this plan meets the requirements of major grant programs including: FEMA’s HMGP, PDM program, FMA Program, and flood control projects authorized by the U.S. Army Corps of Engineers.

In 2013, FEMA released the Local Mitigation Planning Handbook that has become the official guide for local governments to develop, update and implement local mitigation plans. While the requirements under §201.6 have not changed, the Handbook provides guidance to local governments on developing or updating hazard mitigation plans to meet the requirements under the Code of Federal Regulations (CFR) Title 44 – Emergency Management and Assistance §201.6, Local Mitigation Plans for FEMA approval and eligibility to apply for FEMA HMA grant programs. It also offers practical approaches, tools, worksheets and local mitigation planning examples for how communities can engage in effective planning to reduce long-term risk from natural hazards and disasters. The Handbook complements and liberally references the Local Mitigation Plan Review Guide (October 1, 2011), which is the official guidance for federal and state officials responsible for reviewing local mitigation plans in a fair and consistent manner.

Table 3-2 shows how the modified 10-step process fits into FEMA’s four-phase process, and how these elements correspond to the tasks in the FEMA Mitigation Planning Handbook.

Table 3-2 Merced County Hazard Mitigation Planning Process FEMA’s 4-Phase DMA Process Modified 10-Step CRS Process FEMA Local Mitigation Planning
Handbook Tasks
1) Organize Resources
201.6(c)(1) 1) Organize the Planning Effort 1: Determine the planning area and resources
201.6(b)(1) 2) Involve the Public 2: Build the planning team - 44 CFR 201.6 (C)(1)
201.6(b)(2) and (3) 3) Coordinate with Other
Departments and Agencies
3: Create an outreach strategy - 44 CFR
201.6(b)(1)
4: Review community capabilities - 44
CFR 201.6 (b)(2)&(3)
2) Assess Risks
201.6(c)(2)(i) 4) Identify the Hazards

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FEMA’s 4-Phase DMA Process Modified 10-Step CRS Process FEMA Local Mitigation Planning
Handbook Tasks
201.6(c)(2)(ii) 5) Assess the Risks
5: Conduct a risk assessment - 44 CFR
201.6 (C)(2)(i) 44 CFR
201.6(C)(2)(ii)&(iii)
3) Develop the Mitigation Plan
201.6(c)(3)(i) 6) Set Goals 6: Develop a mitigation strategy - 44 CFR 201.6(c)(3)(i); 44 CFR 201(c)(3)(ii)
and 44 CFR 201.6(c)(3)(iii)
201.6(c)(3)(ii) 7) Review Possible Activities
201.6(c)(3)(iii) 8) Draft an Action Plan
4) Implement the Plan and Monitor Progress
201.6(c)(5) 9) Adopt the Plan 7: Review and adopt the plan 201.6(c)(4)
10) Implement, Evaluate, and
Revise the Plan
8: Keep the plan current
9: Create a safe and resilient
community - 44 CFR 201.6(c)(4)

3.4.1 Phase 1: Organize Resources
Planning Step 1: Organize the Planning Effort
The 2021 planning process and update of the LHMP had its roots in the development of a grant application. The County Office OES wrote the grant and in the process solicited commitments from local government jurisdictions that were interested in participating. With an understanding of the number of jurisdictions and their commitment to participate, the grant application was approved and awarded to the County in 2019.

Wood worked with the County to get organized for the plan update. Organizational efforts were initiated with the County and participating jurisdictions in December 2020 to inform and educate the plan participants of the purpose and need for updating the countywide hazard mitigation plan. An initial meeting between Wood and County OEM was held to discuss the organizational aspects of this plan update process. Invitations to the kickoff meeting for this plan update were extended to key County departments, the six incorporated communities, and representatives from special districts for the County and municipalities, as well as to other federal, state, and local stakeholders that might have an interest in participating in the planning process. Representatives from participating jurisdictions and HMPT members to the 2014 plan were used as a starting point for the invite list, with additional invitations extended as appropriate throughout the planning process. The list of initial invitees is included in Appendix A.

Representatives from the following County and municipal departments participated on the HMPT and the development of the plan update. A list of specific HMPT representatives is included in Appendix A. Other local, state, federal, and private stakeholders invited to participate in the HMPT are discussed under Planning Step 3.

Merced County
● Office of Emergency Management
● GIS
● Office of Education
● Division of Environmental Health
● County Counsel
● Community and Economic Development
● Fire Department
● Executive Office

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● IT Department
● Public Works Department
● Agriculture Commissioner
● Food Bank
City of Atwater
● City Manager
● Police Department
● Fire Department
City of Dos Palos
● Police Department
City of Gustine
● Police Department
City of Livingston
● Public Works
City of Los Banos
● Community and Economic Development
● Fire Department
City of Merced
● Fire Department
Planning Meetings
The planning process officially began with a kickoff meeting on December 16, 2020. The meeting covered the scope of work and an introduction to the DMA requirements. Participants were provided with a Local Hazard Mitigation Plan Update Workbook, which included worksheets to facilitate the collection of information necessary to support update of the plan. Using FEMA guidance, Wood designed these worksheets to capture information on past hazard events, identify hazards of concern to each of the participating jurisdictions, quantify values at risk to identified hazards, inventory existing capabilities, and record possible mitigation actions. A copy of Wood’s Local Hazard Mitigation Plan Update Guide for this project is included in Appendix B. The County and each jurisdiction seeking FEMA approval of their plan completed and returned the worksheets in either the Local Hazard Mitigation Plan Update Workbook or shared their most recent Local Hazard Mitigation Plan for incorporation into the plan document.

During the planning process, the HMPT communicated through face-to-face meetings, email, and telephone conversations. A majority of the meetings (3 out of the 4) were held virtually due to social distancing requirements associated with the ongoing COVID-19 pandemic. Draft documents were posted on a Google Drive and in some cases emailed so that the HMPT members could easily access and review them. The HMPT formally met four times during the planning period (December 16, 2020 – June 29, 2021). The purposes of these meetings are described in Table 3-3. The planning consultant sent meeting handouts ahead of time to the participating jurisdictions to review and provide feedback before or at the meeting. In addition to these meetings some jurisdictions held meetings with subcommittees to discuss the needed input for the plan update. In a couple cases some municipalities were not able to attend the planning workshops due to scheduling conflicts or limited staff capacity. Fire Captain and Assistant Director of County OES and the planning consultant worked with the jurisdictions individually in those cases to obtain necessary information and input into the planning process. This was done through direct

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emails from the planning consultant and follow-up phone conversations with the consultant and County OES where necessary.

Table 3-3 Summary of Planning Meetings
Meeting
Number
Meeting Topic Date Location
1 Kickoff/Planning Team Roles and Expectations December 16, 2020 Virtual/Webinar
– Microsoft
Teams
2 Hazard identification and Risk Assessment March 24, 2021 Virtual/Webinar
– Microsoft
Teams
3 Mitigation Strategy and Goals Update May 13, 2021
Virtual/Webinar
– Microsoft
Teams
4 Mitigation Strategy Refinement June 29, 2021 County EOC – Atwater
Meeting #1 – Kickoff Meeting
On December 16, 2020, the Planning Team convened virtually to discuss the process for completing the update of this plan. The kickoff meeting was well attended with 23 individuals present. The audience was a mix of county departments, local governments, special districts and stakeholders. A complete list of those in attendance at the kickoff meeting can be found in the sign-in sheets in Appendix B.

Following introductions, Wood reviewed the DMA requirements and the suggested planning process to follow to meet the requirements as well as the expected schedule of the process. The roles of the HMPT and stakeholder was discussed including the participation requirements for the different roles.

During the kickoff meeting the Planning Team validated the identified hazards within the 2014 plan with minor revisions and collaboratively prioritized the hazards for the purpose of identifying which are “of most concern” to the County. More details are included in Section 4: Risk Assessment.

The group also discussed other agencies that should be part of this planning process, as well as related planning efforts to be coordinated with and recent studies to be incorporated. Part of this discussion was also related to creating a public outreach strategy to involve the public throughout the planning process.

This outreach strategy is included in Appendix F.

The kickoff meeting ended with Wood sharing handouts to assist in the planning process. These handouts included the Local Hazard Mitigation Plan Update Workbook which outlined data collection needs for each participating jurisdiction.

Meeting #2 – Risk and Goals
On March 24, 2021, the HMPT convened virtually to discuss the results of the risk and vulnerability assessment. Forty-one (41) members of the HMPT were present for the discussion. Wood began the meeting with a presentation on the results the risk assessment for natural hazards, results for hazardous material incidents were presented at the next meeting. The group went through each hazard together and discussed the results as well as shared any local insight to inform the HIRA update. Refer to the meeting summary in Appendix B for notes related to each hazard discussed. Part of this discussion was also related to development trends.

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Following the discussion on the results of the risk assessment, Wood explained this update process provides an opportunity to review the previous plan’s goals to determine if they are still valid, comprehensive, and reflect current priorities and updated risk assessment. The group was also encouraged to share their jurisdiction’s goal statements with their local planning teams prior to the next meeting to discuss if changes are necessary.

Wood shared with group that the online public survey had been opened and already received 30 responses at that time. A link was shared with the HMPT to easily distribute by email and for posting on each of the participating jurisdiction’s websites and MJHMP webpages. The meeting ended with a review of the next steps and planning process schedule.

Meeting #3 – Mitigation Strategy and Goals Update
The HMPT convened virtually on May 13, 2021 with 28 people participating to update the plan’s mitigation strategy. The group finalized the plan’s goals and objectives (Step 6) and discussed the criteria for mitigation action selection and prioritization using a worksheet provided by Wood. The group reviewed each possible new mitigation action and additional details were provided by the Planning Team (Step 7). The meeting ended with a review of the next steps and planning process schedule. Wood provided the Planning Team with a link to an online form to submit new mitigation actions. During the Planning Team review of the full plan, each member was provided a handout on prioritizing new mitigation actions and asked to focus on prioritizing each new mitigation action for their jurisdiction.

Meeting #4 – Mitigation Strategy Refinement
On June 29, 2021, the HMPT convened in person to identify new mitigation actions to include in the updated plan. This encompassed a review of possible mitigation activities, alternatives, and related climate adaptation strategies. The group also discussed criteria for mitigation action selection and prioritization.

This was followed by a brainstorming session to elicit the development of new mitigation actions. Entities responsible for new mitigation action implementation were identified. The HMPT completed a sticky dot exercise to prioritize the new mitigation actions. Mitigation action worksheets were also re-distributed to allow additional details to be added following the workshop.

Planning Step 2: Involve the Public
Involving the public assures support from the community at large and is a required part of the planning process per the DMA 2000. Early discussions with Merced County and input received in the first HMPT meeting established the initial plan for public involvement in the plan update. Public outreach began with the creation of an online public survey that was shared with each participating jurisdiction to post on their websites and disseminate via email to local stakeholders. The public outreach activities described here were conducted with participation from and on behalf of all jurisdictions participating in this plan.

Throughout the planning process public workshops were held to inform the public of the purpose of the DMA and the hazard mitigation planning process for the Merced County planning area. At each workshop the public in attendance were provided comment cards to leave any comments related to the County’s MJHMP as well as provide their contact information if they would like to receive ongoing updates and information related to the planning process.

At the kickoff meeting, the HMPT discussed additional options for public involvement and agreed to an approach using established public information mechanisms and resources within the community.

Additional public involvement activities included press releases, website postings, flyer development and distribution, two public workshops, and the collection of public comments on the draft plan. Details on the outreach methods and approach are also summarized in the Community Outreach Strategy included in Appendix F.

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Online Public Survey
During the plan update’s initial drafting stage, an online public survey was used to gather public input to the Planning Team. The survey provided an opportunity for public input during the planning process, prior to finalization of the plan update. The survey gathered public feedback on concerns about hazards and input on mitigation strategies to reduce their impacts. The survey was released on May 3, 2021 and closed on June 2, 2021. The Planning Team provided links to the public survey by distributing it using social media, email, and posting the link on websites. A link to the survey was also posted on some of the participating jurisdictions’ websites as well as through social media posts; screenshots from both can be found in Appendix B. A total of 290 people filled out the survey online. Results showed that the public perceives the most significant hazards to be drought, extreme temperatures, pandemic/epidemic, and climate change. Figure 3-1 shows the results of question 4 of the survey which asked the public’s opinion on what mitigation actions that should have the highest priority in the updated hazard mitigation plan.

Wildfire fuels treatment projects, forest health/watershed protection, water conservation, evacuation route development and public health incident preparedness were cited as the most popular mitigation actions.

This information was shared with the HMPT during the update of the mitigation strategy to consider when evaluating hazard rankings and as a source of potential mitigation ideas. A summary of all the survey data and documentation of the public feedback can be found in Appendix B.

Figure 3-1 Results from Question 4: The following types of mitigation actions may be considered in Merced County. Please indicate the types of mitigation actions that you think should have the highest priority in the Merced County MultiJurisdictional Hazard Mitigation Plan.

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Online Public Workshops
Two online public workshop was held during the planning process to inform the public, receive input to integrate into the plan update, and keep the public updated on the progress being made in the planning process. Both workshops were held virtually as webinars due to social distancing requirements associated with the ongoing COVID-19 pandemic.

The first workshop took place on May 12, 2021 through Facebook Live. The workshop introduced the public to the hazard mitigation planning process for the County’s Plan Update and answered any questions and gather public input to be integrated into the plan update. In addition, it was an opportunity to help staff identify risks, hazards and vulnerabilities from the public’s perspective. At the end of the first workshop over 300 individuals participated in the virtual workshop by either logging on and briefly viewing the live workshop. Members of the public were able to submit comments verbally or via the chat function. The HMPT received four comments from the meeting that helped to inform the group on the public initial thoughts on hazard mitigation and hazards in their community. The recording of the meeting was subsequently posted on the County’s Facebook Webpage, where it has had an additional 1,985 views as of June 2, 2021, of which 1,020 views were 3-second video views of the workshop recording.

The second public workshop took place on September 22, 2021 while the draft plan was out for public review. The workshop was noticed with a press release and social media postings. The workshop was online using MS Teams and was simultaneously broadcasted as a Facebook Live event by the County. The second virtual public workshop was an opportunity to learn more about the updated draft MJHMP including the planning process, the hazards assessed, and the mitigation actions proposed in the MJHMP.

Following the public workshop was an opportunity for the public to comment on the draft MJHMP. Nine persons attended the Teams session. There were no comments received during the workshop. The recording of the meeting was subsequently posted on the County’s Facebook Webpage. The County encourages participation and feedback by attending the public workshop, visiting the County’s Project Webpage, and/or commenting on the Public Review Draft MJHMP Critical Facilities Database Website and Coordination
A unique aspect of the 2021 plan update process was the development of a web-based mapping application by the County in collaboration with Wood. This project webpage served multiple purposes: a planning process backgrounder for the HMPT and public with public survey links; a GIS/map based – interactive storyboard (i.e., Experience Builder Application) to communicate the highlights of the risk assessment, including interactive hazard maps; a web-based method for collecting, validating, updating and maintaining critical facilities for the plan; and finally a platform to make the Plan a “living document” moving forward, providing a basis for the plan maintenance and continuous updating of critical facility data. A screenshot of the project webpage is shown in Figure 3-2 below. The website and critical facilities database was completed with assistance from a professor and students at California State University, Stanislaus.

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Figure 3-2 Merced County’s MJHMP Webpage and Information Resource Portal Source: Merced County 2021
Each participating jurisdiction’s assistance was requested to validate the critical facility GIS data that has been collected. There were two primary aspects of this: data completeness/correctness and alignment/classification with FEMA Lifelines framework. Through a password protected interface built with the ArcGIS Online Experience Builder application jurisdictions were able to browse map based critical facility data, edit descriptive attributes, and add new point data. This process further engaged participating jurisdictions who saw the value of the MJHMP and long-term use and maintenance of the critical facility data moving forward.

Public Review Period
On September 15-October 6, 2021, a public review draft of this plan was released for comment and made available for download via the County OES website. The draft plan was advertised through social media, mass emailing, and an advertisement through the media mechanisms noted previously. An electronic comment form through Microsoft Forms was provided with the draft plan. Two comments were received, one from a member of the public expressing that the plan was well done, and the other from a representative of the Lower San Joaquin Levee District, who did not have any specific things to note.

Comments received were shared with the HMPT but did not result in changes to the plan. Both comments are documented in Appendix B.

3.4.2 Planning Step 3: Coordinate with Other Departments and Agencies Early in the planning process, state and local agencies and organizations were invited to participate as stakeholders in the process through email. Stakeholders include local and regional agencies involved in hazard mitigation activities or those beyond the County and local government that have the authority to regulate development. The Merced County Cooperator’s List provided the basis for a contact list, which was maintained on a Google Drive by County OES and the planning consultant. Stakeholders could participate in various ways, either by contributing input at HMPT meetings, being aware of planning activities through an email group, providing information to support the effort, or reviewing and commenting on the draft plan. Based on their involvement in other hazard mitigation planning efforts, and status in the County, representatives from the following agencies and organizations were invited to participate as stakeholders in the process by email; an asterisk indicates they participated in HMPT

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meetings. Involvement of local academic institutions include students with California State University, Stanislaus who were tasked to assist with the web-based GIS application for critical facility mapping noted previously. The University of California, Merced was also represented at HMPT meetings. More specific on stakeholder agency representatives can be found in Appendix A and documentation in Appendix B.

Neighboring Counties
● County of Fresno
● County of Kings
● County of Madera*
● County of Mariposa*
State and Federal Agencies
● California Office of Emergency Services Region V*
● California Department of Water Resources*
● California Department of Parks and Recreation*
● National Weather Service*
Businesses, Academia, and Private and Non-Profits
● American Red Cross*
● University of California, Merced*
● California State University, Stanislaus*
● Pacific Gas & Electric (PG&E) *
● Mercy Medical Center*
● Merced Irrigation District*
● Turlock Irrigation District*
● Merced County Food Bank*
Incorporation or Existing Plans and Other Information
The coordination and synchronization with other community planning mechanisms and efforts are vital to the success of this plan. To have a thorough evaluation of hazard mitigation practices already in place, appropriate planning procedures should also involve identifying and reviewing existing plans, policies, regulations, codes, tools, and other actions are designed to reduce a community’s risk and vulnerability from natural hazards. Merced County uses a variety of mechanisms to guide growth and development.

Integrating existing planning efforts, mitigation policies, and action strategies into this plan establishes a credible, comprehensive document that weaves the common threads of a community’s values together.

The development and update of this plan involved a comprehensive review of existing plans, studies, reports, and initiatives from Merced County and each participating municipality that relate to hazards or hazard mitigation. A high level summary of the key plans, studies and reports is summarized in the table below. Information on how they informed the update are noted and incorporated where applicable.

Table 3-4 Summary of Review of Key Plans, Studies and Reports Plan, Study, Report Name How Plan informed LHMP
Merced County General Plan Provided background information on the county including some information related to jurisdictions. The elements were used to provide information on risk and
vulnerabilities to hazards and the existing policies the County has in place related to hazards and mitigation.

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Plan, Study, Report Name How Plan informed LHMP
Municipal General Plans (including Safety Elements,
Land Use Elements, and Housing Elements)
Informed the municipal annexes and in some cases the
community service district annexes on past hazard
events, mitigation policies, combining designations and existing and projected development
City of Merced 2015 Local Hazard Mitigation Plan Informed the HIRA sections, mitigation action plans and capability assessments for the City of Merced
Merced County Flood Insurance Study Reviewed for information on past floods and flood problems to inform risk assessment (Section 4)
Utilized Digital Flood Insurance Rate Maps effective
2018 State of California Multi-Hazard Mitigation Plan Reviewed information on climate change and hazard assessment data to ensure consistency with this plan
update
Reviewed list of hazards to inform risk assessment
(Section 4)
Reviewed goals for consistency
Turlock Irrigation District Local Hazard Mitigation Plan 2020
Reviewed risk assessment chapter in TLD plan to help
inform the Merced County LHMP update
NOAA National Centers for Environmental InformationState Climate SummariesReviewed information on climate change to inform risk assessment (Section 4)
California Department of Finance/U.S. Census Bureau,
American Community Survey, 2015-2019
Informed the background on the community including
demographic trends
USDA Risk Management Agency Crop Indemnity
Reports, 2007-2020
Informed the adverse weather section vulnerability
assessment on how crops have been impacted by
weather events in the past. Also informed the Drought
and Agricultural Pests and Disease sections of the HIRA California Climate Adaptation Strategy, 2018 and
California OES Contingency Plan for Excessive Heat
Emergencies (2014)
Informed the Extreme Heat profile and climate change
considerations
Other technical data, reports and studies were reviewed and considered, as appropriate, during the collection of data to support Planning Steps 4 and 5, which include the hazard identification, vulnerability assessment, and capability assessment. Information from the following agencies and groups in were reviewed in the development and update of this plan. Specific references relied on in the development of this plan are also sourced throughout the document as appropriate. ● California Department of Forestry and Fire Protection ● California Department of Parks and Recreation Office of Historic Preservation ● California Department of Transportation
● California Department of Public Health
● California Natural Resources Agency
● California Department of Water Resources
● California Geological Survey
● Merced County Agricultural Department
● Merced Office of Emergency Services
● California Water Foundation
● National Oceanic and Atmospheric Administration National Climatic Data Center ● National Register of Historic Places
● Natural Resource Conservation Service

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● National Weather Service
● U.S. Fish and Wildlife Service
● U.S. Geological Survey
● Western Regional Climate Center
● Center for Western Weather and Water Extremes
Integration of 2014 Plan into Other Plans and Planning Mechanisms While the 2014 MJHMP including jurisdictional annexes for Atwater, Livingston, or Los Banos, or the City of Merced 2015 LHMP, were not specifically incorporated or referenced in county or municipal plans and planning mechanisms, a process to do so with the 2021-2026 plan is outlined in subsection 6.3.3.

Specifically, there is a process noted in both subsection 6.3.3 and corresponding mitigation actions in subsection 5.3 that outline how the County and municipalities can achieve Assembly Bill (AB) 2140 compliance, which recommends adoption by reference or incorporation of the LHMP into the Safety Element of the General Plan. The County was actively coordinating an amendment of the General Plan Safety Element to accommodate this during the finalization of this LHMP in late 2021.

3.4.3 Phase 2: Assess Risks
Planning Step 4: Identify the Hazards
Wood led the HMPT in an effort to review the list of hazards identified in the 2014 plan and document all the hazards that have, or could, impact the planning area, including documenting recent drought, flood, wildfire and winter storm events. Data collection worksheets were used in this effort to aid in determining hazards and vulnerabilities and where risk varies across the planning area. The profile of each of these hazards was then updated in 2019 with information from the HMPT and additional sources. Web resources, existing reports and plans, and existing GIS layers were used to compile information about past hazard events and determine the location, previous occurrences, probability of future occurrences, and magnitude/severity of each hazard. GIS were used to display, analyze, and quantify hazards and vulnerabilities where data permitted. The potential for climate change to affect the frequency and intensity of the hazards was summarized based on latest available science, where applicable. A more detailed description of the HIRA process and the results are included in Section 4: Hazard Identification and Risk Assessment.

Planning Step 5: Assess the Risks
After updating the profiles of the hazards that could affect the County, the HMPT collected information to describe the likely impacts of future hazard events on the participating jurisdictions. This step included two parts: a vulnerability assessment and a capability assessment.

Vulnerability Assessment – Participating jurisdictions updated their assets at risk to natural hazards— overall and in identified hazard areas. These assets included total number and value of structures; critical facilities and infrastructure; natural, historic, and cultural assets; and economic assets. The HMPT also analyzed development trends in hazard areas. The latest DFIRM was used to refine the estimate flood losses during the update, where available for the NFIP participating communities.

Capability Assessment – The HMPT also conducted a capability assessment update to review and document the planning area’s current capabilities to mitigate risk and vulnerability from natural hazards.

By collecting information about existing government programs, policies, regulations, ordinances, and emergency plans, the HMPT can assess those activities and measures already in place that contribute to mitigating some of the risks and vulnerabilities identified. This information for the County is included in Section 6 and in the respective jurisdictional annexes. This addressed FEMA planning task 4: Review community capabilities - 44 CFR 201.6 (b)(2) & (3).

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Results of the risk assessment was presented, and comments discussed at the second HMPT meeting in March 2021. A more detailed description of the risk assessment process and the results are included in Section 4: Hazard Identification and Risk Assessment.

3.4.4 Phase 3: Develop the Mitigation Plan
Planning Step 6: Set Goals
Wood facilitated a discussion session with the HMPT to review the 2014 plan’s goals and objectives. The HMPT discussed definitions and examples of goals, objectives, and actions and considered the goals of the state hazard mitigation plan and other relevant local plans when reviewing and revising the goals and objectives. The resulting updated goals and objectives are presented in Section 5: Mitigation Strategy.

Planning Step 7: Review Possible Activities
Wood facilitated a discussion at an HMPT meeting to review the alternatives for mitigating hazards. This included a brainstorming session with the HMPT to identify a comprehensive range of mitigation actions for each identified hazard, and a method of selecting and defending recommended mitigation actions using a series of selection criteria. More specifics on the process and the results of this collaborative process are captured in Section 5: Mitigation Strategy.

As part of the review of mitigation options long-term climate change adaptation strategies were also discussed. HMPT members were encouraged to incorporate climate change adaptation measures into the mitigation strategy of their respective jurisdictions utilizing resources and guidance available on the CalAdapt website.

Planning Step 8: Draft an Action Plan
Based on input from the HMPT regarding the draft risk assessment and the goals and activities identified in Planning Steps 6 and 7, Wood produced a complete first draft of the plan. This complete was shared electronically with the HMPT for review and comment. Other agencies were invited to comment on this draft as well. HMPT and agency comments were integrated into the second draft, which was advertised and distributed to collect public input and comments. Neighboring county emergency managers and interested stakeholders identified under Step 3 were also solicited to provide comments on the draft plan; no comments were received. Wood integrated comments and issues from the public, as appropriate, along with additional internal review comments and produced a final draft for the California Office of Emergency Services and FEMA Region IX to review and approve, contingent upon final adoption by the governing boards of each participating jurisdiction.

3.4.5 Phase 4: Implement the Plan and Monitor Progress
Planning Step 9: Adopt the Plan
In order to secure buy-in and officially implement the plan, the plan was adopted by the governing boards of each participating jurisdiction on the dates included in the adoption resolutions in Appendix C:

Approval and Adoption. The final plan will be included in the Safety Element of the County General Plan and result in the County’s eligibility for Assembly Bill (AB) 2140. This adoption makes the jurisdiction eligible for consideration for part or all of its local costs on eligible public assistance to be provided by State share funding through the CDAA.

Planning Step 10: Implement, Evaluate, and Revise the Plan The true worth of any mitigation plan is in the effectiveness of its implementation. Up to this point in the plan update process, all of the HMPT’s efforts have been directed at researching data, coordinating input

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from participating entities, and updating and developing appropriate mitigation actions. Each recommended action includes key descriptors, such as hazard(s) addressed, lead manager and priority, to help initiate implementation. An overall implementation strategy is described in Section 6: Plan Adoption, Implementation, and Maintenance.

Finally, there are numerous organizations within the Merced County planning area whose goals and interests’ interface with hazard mitigation. Coordination with these other planning efforts, as addressed in Planning Step 3, is paramount to the ongoing success of this plan and of mitigation in Merced County and is addressed further in Section 6. A plan update and maintenance schedule and a strategy for continued public involvement are also included in Section 6.

Implementation and Maintenance Process: 2014 Plan
The 2014 LHMP included a process for implementation and maintenance which was generally followed, with some variation. Implementation of the plan including the status of mitigation actions is captured in Section 5 and the jurisdictional annexes. In general, the County and participating jurisdictions have made progress in the implementation of the plan. Successes of note are detailed in the mitigation strategy in Section 5. An updated implementation and maintenance section can be referenced in Section 6..

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4 HAZARD IDENTIFICATION AND RISK ASSESSMENT
Requirement §201.6(c)(2)(i):
[The risk assessment shall include a] description of the type, 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.
§201.6(c)(2)(ii):
[The risk assessment shall include a] description of the jurisdiction’s vulnerability to the hazards described in paragraph (c)(2)(i) of this section. This description shall include an overall summary of each hazard and its impact on the community. All plans approved after October 1, 2008 must also address NFIP insured structures that have been repetitively damaged by floods. The plan should describe vulnerability in terms of:
§201.6(c)(2)(ii)(A):

The types and numbers of existing and future buildings, infrastructure, and critical facilities located in the identified hazard areas;
§201.6(c)(2)(ii)(B):

An estimate of the potential dollar losses to vulnerable structures identified in ... this section and a description of the methodology used to prepare the estimate.
§201.6(c)(2)(ii)(C):

Providing a general description of land uses and development trends within the community so that mitigation options can be considered in future land use decisions.

Risk to natural hazards is a combination of hazard, vulnerability and capability. This section of the MHMP will look at both hazards and vulnerability. The risk assessment process identifies and profiles relevant hazards and assesses the exposure to lives, property and infrastructure to these hazards. The goal of the risk assessment is to estimate the potential losses in Merced County from a hazard event. This process also allows communities in Merced County to better understand their potential risk to natural hazards and provides a framework for developing and prioritizing mitigation actions to reduce the risks from future hazard events in Merced County.

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 builds upon the methodology described in the 2013 FEMA Local Mitigation Planning Handbook, which recommends a four-step process for conducting a risk assessment:

1. Describe Hazards

2. Identify Community Assets

3. Analyze Risks

4. Summarize Vulnerability

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In essence, the risk assessment evaluates potential loss from hazards by assessing the vulnerability of the county’s population, build environment, critical facilities, and other assets. Data collected through this process has been incorporated into the following sections of this section:

Subsection 4.1: Hazard Identification - identifies the hazards that threaten the Planning Area and describes why some hazards have been omitted from further consideration.

Subsection 4.2: Asset Summary - describes the methodology for inventorying assets as the basis for determining vulnerability of the planning area to the identified hazards.

Subsection 4.3: Hazard Analysis and Risk Assessment - discusses the threat to the Planning Area and describes previous occurrences of hazard events and the likelihood of future occurrences (2013 FEMA Local Mitigation Planning Handbook Risk Assessment Step 1). It also includes a vulnerability assessment considering assets at risk, critical facilities, and development trends (2013 FEMA Local Mitigation Planning Handbook Risk Assessment Steps 2, 3 and 4).

This risk assessment covers the entire geographical area of Merced County. Since this plan is a multijurisdictional plan, the HMPC was required to evaluate how the hazards and risks vary from jurisdiction to jurisdiction. While these differences are noted in this section, 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 Merced County planning area.

4.1 Hazard Identification
The San Joaquin Valley region and Merced County is susceptible to a number of hazards. This MHMP profiles the most significant of these hazards. In the early meetings with Merced County and the Planning Team, data was reviewed from the following sources on hazards affecting the county, those sources were:

Federal and State Disaster Declaration History, the State of California Hazard Mitigation Plan (2018), the Health Safety Element of the Merced County 2035 General Plan (2012), and interviews of staff that live and work in Merced County.

Using existing natural hazards data and input gained through planning meetings during both the 2014 HMP and 2021 update, the HMPC agreed upon a list of hazards that could affect Merced County. The following table explains the changes in the hazards profiled in 2014 and the 2021 update.

Table 4-1 Updates to Hazards Profiled, 2014 Plan and 2021 Update 2014 Hazards 2021 Hazards Comments
Earthquake Earthquake No Changes.

Floods (including dam failures) Flooding and Levee Failure Broke out dam failures as its own sections:
“dam incidents”. Added levee failure to
section due to the large number of levees
in the County.

Severe Weather (including Drought,
Extreme Heat, Freeze)
Severe Weather: Dense Fog,
Extreme Heat, Freeze, Heavy
Rain and Wind
Broke out drought into its own section.

Added dense fog, wind and heavy rain to
severe weather.

Wildfire Wildfire No Changes.

Agriculture Pest and Disease New in 2021. Added due to significant agricultural industry in the County and the
impacts to the local economy.

Cyber Attacks New in 2021. Added due to worldwide
uptick in number and extent of attacks.

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2014 Hazards 2021 Hazards Comments
Dam Incidents Identified in General Plan Safety Element.

Includes flooding from excess releases.

Drought Previously part of severe weather section.

Profiled separately due to the unique
nature of the hazard and different
consequences.

Hazardous Materials New in 2021. Added due to potential for fixed facility and transportation incidents.

Landslide New in 2021. Added due to presence of
landslide susceptible terrain in the
western county.

Pandemic/Epidemic New in 2021. Included due to extent of impacts associated with 2020 COVID 19
Pandemic.

Subsidence New in 2021. Included due to history of
subsidence related to groundwater
withdrawals and impacts to canal and
levee infrastructure.

The 2021 HMP update included a significant re-evaluation of the hazards with the latest, best available data. Hazards data from Merced County, California Governor’s 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. The update process included a comprehensive, parcel-level risk analysis with GIS where available data permitted. Many new maps and tables were added that capture the potential losses.

4.1.1 Overall Hazard Significance Summary
Overall hazard significance was based on a combination of Geographic Area, Probability of Future Occurrence and Potential Magnitude/Severity as defined below. The individual ratings are based on or interpolated from the analysis of the hazards in the sections that follow. During the 2021 Merced County HMP update the individual ratings and significance of the hazards was revisited and updated. Public concern was also considered via input at public webinars and an online survey.

Table 4-2 Merced County Hazard Significance
Hazard Geographic Area
Probability of
Future
Occurrence
Magnitude/Severity
(Extent)
Overall
Significance
Agriculture Pest and
Disease Extensive Likely Critical Medium
Cyber Attack Significant Likely Critical Medium
Dam Incidents Significant Occasional Catastrophic Medium Drought Extensive Likely Critical High
Earthquake Significant Unlikely Critical Medium
Flood and Levee
Failure Extensive Likely Catastrophic High
Hazardous Materials Limited Highly Likely Negligible Low Landslide Limited Occasional Limited Low
Pandemic/Epidemic Extensive Occasional Catastrophic High

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Hazard Geographic Area
Probability of
Future
Occurrence
Magnitude/Severity
(Extent)
Overall
Significance
Severe Weather:

Dense Fog Extensive Highly Likely Critical High
Severe Weather:

Freeze Extensive Highly Likely Critical High
Severe Weather: Heat Extensive Highly Likely Critical High Severe Weather:

Heavy Rain Extensive Highly Likely Critical High
Severe Weather: High
Wind/Tornado Extensive Highly Likely Critical High
Subsidence Extensive Likely Negligible Low
Wildfire Significant Likely Limited Medium
Geographic Area
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 10 years or less.

Occasional: Between 1 and 10% chance of
occurrence in the next year or has a recurrence
interval of 11 to 100 years.

Unlikely: Less than 1% chance of occurrence in
next 100 years or has a recurrence interval of
greater than every 100 years.

Magnitude/Severity (Extent)
Catastrophic—More than 50 percent of property severely
damaged; 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 and/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
Significance
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact

4.1.2 Non-Profiled Hazards
The Planning Team reviewed data and discussed several other hazards, which were eliminated from further discussion because they occur rarely and/or their impacts are not significant. The list below details these hazards and provides a brief explanation for their omission from further profiling. ● Avalanche - Snowfall is extremely rare to nonexistent across the planning area. ● Coastal Erosion/Storm - Hazard does not occur due to distance from coasts and ocean. ● Hailstorm - Severe thunderstorms during which hail normally occurs are rare. ● Hurricane - Hazard does not occur due to distance from ocean. ● Tsunami - Hazard does not occur due to distance from ocean. ● Volcano - The U.S. Geological Survey does not include Merced County in their map of areas identified as subject to hazards from potential eruptions in California.

The Planning Team acknowledges there are other human caused hazards that can affect the County. They are recognized here, with notes below how they are considered as consequences of other hazards or addressed in other planning mechanisms:
● Civil Unrest and Terrorism – More commonly addressed in the local emergency operations plans; an uptick in social equity-related incidents and far-right extremism has been noted in recent years. ● Power outages/Utility Failure – This is addressed as a consequence of other hazards such as severe weather, earthquakes, and wildfires.

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● Transportation Hazards – Transportation safety is typically addressed in other planning mechanisms.

Noted as a consequence of other hazards where applicable, e.g. Severe Weather: Fog, earthquakes, floods.

4.1.3 Disaster Declaration History
One method to identify hazards is to look at the events that have triggered federal and/or state disaster declaration that included Merced County. Federal and 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.

In other words, a presidential disaster declaration puts federal recovery programs in place to help disaster victims, business, and public agencies.

The federal government may issue a disaster declaration through FEMA, the U.S. Department of Agriculture (USDA), or the Small Business Administration. FEMA also issues emergency declarations, which are more limited in scope and without the long-term federal recovery programs of major disaster declarations (Farm Service Agency 2018). The quantity and types of damage are the determining factors.

This section focuses on state and federal disaster and emergency declarations.

The communities throughout Merced are among the many in California that are susceptible to disaster.

Details on federal and state disaster declarations were obtained by the HMPC, FEMA, and the California OES and compiled in chronological order in Table 4-3. A review of state and federal declared disasters indicates that Merced County received 18 proclamations between 1950 and March 2020. Of the 18 state declarations, seven were associated with flooding; two were for drought (not including declaration issued by the USDA); three were for freeze; and two were for the COVID-19 pandemic.

This disaster history (combined federal and state) suggests that Merced County experiences a major event worthy of a disaster declaration about every 4 years. The County has a 26 percent chance of receiving a disaster declaration in any given year. With the exception of the declarations for drought and the COVID19 pandemic, every declaration resulted directly or indirectly from severe weather. Further, a review of these events helps Merced County, and its jurisdictions identify risk reduction targets and ways to improve capabilities to avoid large-scale hazard events in the future.

The following table lists the declarations where Merced County was included in federal and/or state disaster declarations from 1950 to the present.

Table 4-3 Merced County Disaster Declaration History 1950-present Hazard Type Disaster Name Disaster Number
Flood 1950 Floods (Statewide) OCD50-01
Flood 1955 Floods (Statewide) DR-47
Flood 1969 Storms, Flooding DR-253
Freeze 1972 Freeze
Drought California Drought January 1976-77 3023
Severe Storms 1983 Coastal Storms, Floods, Slides, &
Tornadoes DR-677
Freeze 1990 Freeze DR-894
Flood 1995 Late Winter Storms DR-1046
Flood 1997 January Floods DR-1155
Flood 1998 El Niño Floods DR-1203

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Hazard Type Disaster Name Disaster Number
Freeze 1998 Freeze DR-1267
Hurricane Katrina Evacuation California Hurricane Katrina Evacuees September 2005 EM-3248
Flood 2006 June Storms DR-1646
Freeze 2007 Severe Freeze DR-1689
Drought Central Valley Drought 2008 GP 2008-03
Drought Drought State of Emergency Statewide 2014 B-17-2014 Flooding and Mudslides January 2017 Storms DR-4301
Pandemic California COVID-19 EM-3428
Pandemic California COVID-19 Pandemic DR-4482
Source: Merced OES, Cal OES and FEMA
Since 2012, there have been 18 disaster designations issued by the Secretary of Agriculture in Merced County, 15 of which were for drought and three were for hail, excess rain, cold temperatures, and high winds. Of the drought designations, 11 are classified as “Drought-Fast Track” Secretarial disaster designations. According to the Secretary of Agriculture, a Fast Track designation is for a severe drought and provides an automatic designation when during the growing season any portion of the county meets the severe drought intensity value for eight consecutive weeks. Refer to the drought hazard profile for more information of disaster declarations from the Secretary of Agriculture related to drought events.

Table 4-4 USDA Agricultural Declarations in Merced County, 2012-2020 Year Hazard Designation
Number Approval Date
2012
Drought-Fast Track S3268 7/12/2012
Hail, rain, cold temperatures S3320 8/3/2012
Drought S3379 9/5/2012
Drought S3452 12/19/2012
2013
Drought-Fast Track S3491 2/27/2013
Drought-Fast Track S3511 4/24/2013
Drought-Fast Track S3547 7/3/2013
Drought-Fast Track S3558 7/31/2013
2014 Drought-Fast Track S3626 1/15/2014
Drought S3743 9/17/2014
2015 Drought-Fast Track S3784 2/4/2015
Drought S3943 12/23/2015
2016
Drought-Fast Track S3952 2/17/2016
Severe weather including excessive
rainfall and high winds S4164 3/31/2017
2017 Drought-Fast Track S4144 2/23/2017
2019 Excessive rain and hail S4657 3/11/2020
2020 Drought-Fast Track S4697 6/16/2020
Source: USDA Secretary of Agriculture

4.1.4 Climate Change Considerations Summary
Merced County is part of the San Joaquin Valley part of California’s Central Valley. The region is known as one of the world’s most productive agricultural regions and is also vulnerable to the impacts on climate change. The following are highlights from California’s Fourth Climate Change Assessment, San Joaquin Valley Region Report (Preview), of projected impacts to the State of California and the Central Valley due to climate change:
● Acceleration of higher temperatures across California.

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● More intense and frequent heat waves.
● Increasing evapotranspiration.
● More intense and frequent droughts.
● More intense rainstorms.
● Higher frequency of catastrophic floods.
● More severe and frequent wildfires.
● Declining and change in timing of snowmelt.
● Increased susceptibility to rain-on-snow events from atmospheric rivers. ● Increased stream temperatures resulting in decreased water quality.

The important consideration for hazard mitigation is that climate change is exacerbating the hazards which are already identified and profiled. Additional specifics associated with the hazards are discussed in the Climate Change Considerations portion of each hazard profile.

4.1.5 Overview of Hazard Identification and Risk Assessment Subsection 4.3 contains detailed hazard profiles for the identified hazards. Each hazard profile includes the following subsections:
● Hazard/Problem Definition—This section gives a description of the hazard and associated issues followed by details on the hazard specific to the Merced County planning area. ● Geographic Area – This section gives a spatial description of the potential location or areas of Merced County where the hazard expected to impact.
● Extent (Magnitude/Severity)– This section gives a description of the potential strength or magnitude of the hazard as it pertains to Merced County.
● Previous Occurrences—This section contains information on historical incidents, including impacts where known. Historical incident worksheets were used to capture information from participating jurisdictions on past occurrences.
● Probability 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:
- Highly Likely — Near 100 percent chance of occurrence in next year or happens every year. - Likely — Between 10 and 100 percent chance of occurrence in next year or has a recurrence interval of 10 years or less.
- Occasional — Between 1 and 10 percent chance of occurrence in the next year or has a recurrence interval of 11 to 100 years.
- Unlikely — Less than 1 percent chance of occurrence in next 100 years or has a recurrence interval of greater than every 100 years.
● Climate Change Considerations - This describes the potential for climate change to affect the frequency and intensity of the hazard in the future.
● Vulnerability - Following the hazard profiles is a vulnerability assessment for each identified hazard.

The assessment was conducted through the study of potential impacts to the following specific sectors:
- General Property
- People
- Critical Facilities and Infrastructure

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- Economy
- Historic, Cultural, and Natural Resources
- Future Development
- Risk Summary - Each vulnerability assessment includes a risk summary of the key issues/problems based on threat, vulnerability and consequence to the planning area and jurisdictions from the specific hazard.

Data used to support this assessment included the following:
● County GIS data (hazards, base layers, and assessor’s data); ● Statewide GIS datasets to support mitigation planning; ● State of California Hazard Mitigation Plan 2018;
● Merced County Hazard Mitigation 2014;
● Jurisdictional Hazard Mitigation Plans;
● CAL FIRE datasets;
● California’s Fourth Climate Change Assessment
● Written descriptions of inventory and risks provided by the jurisdictions; ● Online data sources (cited where applicable);
● Data and information from existing plans and studies; and ● Input from planning team members and staff from the County and local, state, and federal agencies.

Asset Summary

4.1.6 Assets Exposure
As a starting point for analyzing the Planning Area’s vulnerability to identified hazards, the HMPC used a variety of data to define a baseline against which all disaster impacts could be compared. If a catastrophic disaster was to occur in the Planning Area, this section describes significant assets exposed or at risk in the Planning Area. Data used in this baseline assessment included:
● Total assets at risk;
● Critical facility inventory;
● Cultural, historical, and natural resources; and
● Population growth and land use/development trends.

Total Assets at Risk
Building value assessments in this plan are based on data from the Merced County’s Assessor’s Office.

This data provided the baseline for an inventory of the total exposure of developed properties within the county and helps to ensure that the updated HMP reflects changes in development. It is important to note that depending on the nature and type of hazard event or disaster, it is generally the value of the infrastructure or improvements to the parcels that are of concern or at risk. Generally, the land itself is not a total loss, but may see a reduction in value. Thus, the parcel analysis excludes land value.

Parcel Exposure and Preparations for Analysis
Merced County Assessor data was used to inventory the total number and types of parcels with improvements, defined as parcels with an improvement value greater than zero, in the County. Building content values were estimated based on the following formulas based on FEMA/Hazus methods: a) Residential properties received content values worth 50% of the improved values; b) Agricultural, Commercial, Exempt, and Mixed Use related properties received content values worth 100% of the improved values; and c) Industrial properties received content values worth 150% of the improved values.

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Adding up these content and original improved values yields the Total Value of Improved Parcels, which is an estimation of the total property exposure within the County. Building counts were based on an address point database to further refine the number of structures, as one parcel may have multiple buildings.

Table 4-6 summarizes the property inventory for the County and each participating jurisdiction with detail by property type. Table 4-5 shows the total property inventory from the Assessor’s Office.

Table 4-5 Total Exposure Summary by Jurisdiction
Jurisdiction Improved
Parcel Count
Building
Count Improved Value Estimated Content Value Total Value Atwater 7,634 9,654 $1,391,376,798 $826,122,017 $2,217,498,815 Dos Palos 1,774 2,001 $202,169,557 $111,638,513 $313,808,070 Gustine 1,874 2,109 $290,346,103 $174,766,468 $465,112,571 Livingston 3,344 4,007 $708,187,135 $500,444,666 $1,208,631,801 Los Banos 12,253 13,111 $2,492,207,313 $1,427,441,289 $3,919,648,602 Merced 22,362 31,744 $4,753,631,582 $3,092,973,003 $7,846,604,585 Unincorporated 28,343 35,327 $5,628,897,061 $4,421,594,611 $10,050,491,672 Total 77,584 97,953 $15,466,815,549 $10,554,980,566 $26,021,796,115 Source: Merced County Assessor’s Office, Wood Analysis
Table 4-6 Total Exposure by Jurisdiction and Property Type Jurisdiction
Property
Type
Improved
Parcel
Count
Building
Count Improved Value Estimated Content Value Total Value Atwater
Agricultural 4 4 $294,019 $294,019 $588,038
Commercial 254 941 $187,232,236 $187,232,236 $374,464,472 Exempt 77 150 $14,001,651 $14,001,651 $28,003,302
Industrial 48 48 $28,819,757 $43,229,636 $72,049,393
Mixed Use 6 6 $236,330 $236,330 $472,660
Residential 7,229 8,489 $1,159,329,319 $579,664,660 $1,738,993,979 Vacant
Land 16 16 $1,463,486 $1,463,486 $2,926,972
Total 7,634 9,654 $1,391,376,798 $826,122,017 $2,217,498,815 Dos Palos
Commercial 104 154 $16,913,918 $16,913,918 $33,827,836
Exempt 39 94 $1,962,673 $1,962,673 $3,925,346
Industrial 9 9 $1,043,139 $1,564,709 $2,607,848
Mixed Use 5 5 $104,170 $104,170 $208,340
Residential 1,611 1,733 $182,105,228 $91,052,614 $273,157,842 Vacant
Land 6 6 $40,429 $40,429 $80,858
Total 1,774 2,001 $202,169,557 $111,638,513 $313,808,070 Gustine
Agricultural 3 3 $249,806 $249,806 $499,612
Commercial 86 212 $13,841,697 $13,841,697 $27,683,394
Exempt 21 22 $1,947,230 $1,947,230 $3,894,460
Industrial 8 8 $21,456,333 $32,184,500 $53,640,833
Mixed Use 3 3 $55,055 $55,055 $110,110
Residential 1,749 1,857 $252,615,603 $126,307,802 $378,923,405 Vacant
Land 4 4 $180,379 $180,379 $360,758
Total 1,874 2,109 $290,346,103 $174,766,468 $465,112,571

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Jurisdiction
Property
Type
Improved
Parcel
Count
Building
Count Improved Value Estimated Content Value Total Value Livingston
Agricultural 8 9 $713,550 $713,550 $1,427,100
Commercial 82 235 $75,954,862 $75,954,862 $151,909,724
Exempt 48 114 $8,331,817 $8,331,817 $16,663,634
Industrial 19 33 $103,753,191 $155,629,787 $259,382,978 Mixed Use 3 4 $53,004 $53,004 $106,008
Residential 3,177 3,605 $519,238,129 $259,619,065 $778,857,194 Vacant
Land 7 7 $142,582 $142,582 $285,164
Total 3,344 4,007 $708,187,135 $500,444,666 $1,208,631,801 Los Banos
Agricultural 6 8 $519,029 $519,029 $1,038,058
Commercial 441 889 $287,223,390 $287,223,390 $574,446,780 Exempt 189 270 $15,571,378 $15,571,378 $31,142,756
Industrial 23 43 $29,327,893 $43,991,840 $73,319,733
Mixed Use 9 9 $175,156 $175,156 $350,312
Residential 11,554 11,861 $2,158,859,942 $1,079,429,971 $3,238,289,913 Vacant
Land 31 31 $530,525 $530,525 $1,061,050
Total 12,253 13,111 $2,492,207,313 $1,427,441,289 $3,919,648,602 Merced
Agricultural 23 26 $1,112,724 $1,112,724 $2,225,448
Commercial 911 2,819 $1,045,871,699 $1,045,871,699 $2,091,743,398 Exempt 632 1,313 $48,779,381 $48,779,381 $97,558,762
Industrial 120 220 $167,440,322 $251,160,483 $418,600,805 Mixed Use 16 17 $259,279 $259,279 $518,558
Residential 20,611 27,288 $3,488,757,480 $1,744,378,740 $5,233,136,220 Vacant
Land 49 61 $1,410,697 $1,410,697 $2,821,394
Total 22,362 31,744 $4,753,631,582 $3,092,973,003 $7,846,604,585 Unincorporated
Agricultural 9,875 13,314 $2,230,504,412 $2,230,504,412 $4,461,008,824 Commercial 689 1,703 $277,981,955 $277,981,955 $555,963,910 Exempt 427 769 $56,580,563 $56,580,563 $113,161,126
Industrial 158 250 $322,872,531 $484,308,797 $807,181,328 Mixed Use 70 81 $2,168,754 $2,168,754 $4,337,508
Residential 17,020 19,083 $2,737,477,431 $1,368,738,716 $4,106,216,147 Vacant
Land 104 127 $1,311,415 $1,311,415 $2,622,830
Total 28,343 35,327 $5,628,897,061 $4,421,594,611 $10,050,491,672 Grand Total 77,584 97,953 $15,466,815,549 $10,554,980,566 $26,021,796,115 Source: Merced County Assessor’s Office, Wood Analysis
Critical Facility/Lifeline Inventory
A significant aspect of the 2021 HIRA update was the update of critical facilities and an alignment/classification with the FEMA Lifelines framework. The critical facilities/lifelines GIS database was based on a combination of county-provided data, Homeland Infrastructure Foundation Level Data (HIFLD), and local input. Jurisdictions were able to browse map based critical facility data, edit descriptive attributes, and add new point data through a password protected interface built with the ArcGIS Online Experience Builder application setup by the County GIS coordinator. The results are summarized here and provided the basis for GIS based vulnerability analyses, where data permitted.

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For the purposes of this plan, a critical facility is defined as one that is essential in providing utility or direction either during the response to an emergency or during the recovery operation. FEMA sorts critical facilities into seven lifeline categories as shown in Figure 4-1.

Figure 4-1 Lifeline Categories
These lifeline categories standardize the classification of critical facilities and infrastructure that provide indispensable service, operation, or function to a community. A lifeline is defined as providing indispensable service that enables the continuous operation of critical business and government functions, and is critical to human health and safety, or economic security. These categorizations are particularly useful as they:
● Enable effort consolidations between government and other organizations (e.g., infrastructure owners and operators).
● Enable integration of preparedness efforts among plans, easier identification of unmet critical facility needs.
● Refine sources and products to enhance awareness, capability gaps, and progress towards stabilization.
● Enhance communication amongst critical entities, while enabling complex interdependencies between government assets.
● Highlight lifeline related priority areas regarding general operations as well as response efforts.

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Table 4-7 shows a summary of the critical facilities analysis. Figure 4-2 illustrates the location of critical facilities in Merced County.

Table 4-7 Summary of Critical Facilities by Jurisdiction and Lifeline Jurisdiction
CommunicationsEnergyFood, Water, ShelterHazardous MaterialHealth and MedicalSafety and SecurityTransportationTotal Atwater 7 5 3 1 1 34 11 62
Dos Palos 1 - - - - 7 - 8
Gustine 6 - 2 1 - 8 3 20
Livingston 6 1 3 3 - 14 5 32
Los Banos 15 2 20 6 3 53 6 105
Merced 36 3 52 17 22 87 53 270
Unincorporated 113 216 31 24 1 164 467 1,016
Total 184 227 111 52 27 367 545 1,513
Source: HIFLD, Merced County, City of Atwater, City of Dos Palos, City of Gustine, City of Livingston, City of Los Banos, City of Merced

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Figure 4-2 Merced County Critical Facilities

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Other critical facilities unique to the county are the California Aqueduct, the Castle Air Museum, and the Federal Bureau of Prisons located in Atwater. These facilities are better addressed in the emergency operations plans for the county, the two municipalities, and federal emergency plans.

The California Aqueduct, part of the California State Water Project, runs through the western part of Merced County. The State Water Project is a water storage and delivery system of reservoirs, aqueducts, power plants, and pumping plants. Its main purpose is to store water and distribute it to 29 urban and agricultural water suppliers in Northern California, the San Francisco Bay Area, the San Joaquin Valley, the Central Coast, and Southern California. Seventy percent of the contracted water supply goes to urban users and 30 percent goes to agricultural users. The State Water Project makes deliveries to two-thirds of California's population. Earthquakes, landslides, flooding, or other hazard events that disrupt the aqueduct’s ability to deliver water could have serious impacts to agriculture in the county and water users in many areas of California.

The Castle Air Museum is one of Merced County’s treasures drawing visitors from across the country.

Located on the site of the former Castle Air Force Base (known as Merced Army Airfield during WWII), the museum has a collection of 53 World War II, Korean War, and Vietnam Era aircraft. The indoor museum contains many additional Air Force and Army Air Corps artifacts and a B-52 simulator.

The Federal Bureau of Prisons in Atwater is one of the larger employers in the city with over 100 employees and approximately 1,600 prisoners. Although this plan recognizes the critical assets of this facility and its role in the county’s economy, as federally owned property, the prison develops its separate emergency management plans.

Cultural, Historical and Natural Resources
Assessing Merced County’s vulnerability to disaster also involves inventorying the natural, historical, and cultural assets of the area. This step is important for the following reasons:
● The community may decide that these types of resources warrant a greater degree of protection due to their unique and irreplaceable nature and contribution to the overall economy. ● In the event of a disaster, an accurate inventory of natural, historical and cultural resources allows for more prudent care in the disaster’s immediate aftermath when the potential for additional impacts is higher.
● The rules for reconstruction, restoration, rehabilitation, and/or replacement are often different for these types of designated resources.
● Natural resources can have beneficial functions that reduce the impacts of natural hazards, for example, wetlands and riparian habitat which help absorb and attenuate floodwaters and thus support overall mitigation objectives.

Historic and Cultural Resources
Historical resources are buildings, structures, objects, places, and areas that are eligible for listing in the National Register of Historic Places (NRHP), the California Register of Historic Resources, or the County’s List of Historic Resources, have an association with important persons, events in history, or cultural heritage, or have distinctive design or construction method.

For purpose of federal actions, a qualified historic resource is defined as a property listed in or formally determined eligible for listing in the NRHP before a disaster occurs. The NRHP is part of a national program to coordinate and support public and private efforts to identify, evaluate, and protect historic and archeological resources. Properties listed include districts, sites, buildings, structures, and objects that are significant in American history, architecture, archeology, engineering, and culture. The National Register is administered by the U.S. Department of the Interior National Park Service. Local and state

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agencies may consider a broader definition of qualified historic properties in the review, evaluation, and treatment of properties damaged during a disaster.

The State of California Office of Historic Preservation can provide technical rehabilitation and preservation services for historic properties affected by a natural disaster. Depending on the hazard, protection could range from emergency preparedness, developing a fire safe zone around sites susceptible to wildfires, or seismically strengthening or structurally reinforcing structures.

State and local registers of historic resources provide designated Historical Landmarks, Points of Historical Interest, and Historic Buildings. These resources include, but are not limited to:
● The California Register of Historical Resources
● The California Historical Landmarks
● The California Inventory of Historical Resources
● The California Points of Historical Interest
Historical Resources designated on a federal, state or local level are listed in Table 4-8.

Table 4-8 Merced County Historical Resources
Property Name Register Jurisdiction Date Listed
Bank of Italy National Merced 10/12/2004
Bank of Los Banos
Building National Los Banos 8/24/1979
Bloss Mansion National Atwater 9/3/1981
Buhach Grammar School National Merced 4/7/1983
Canal Farm Inn State Landmark Los Banos 1/27/1956
Church of St. Joseph National Los Banos 7/8/2004
Cook, Maj. George
Beecher, House National Merced 9/15/1983
G.B. Neighbors Home Point of Interest Snelling 6/2/1967 George S. Bloss Mansion Point of Interest Atwater 3/15/1974 Gwin Post Office, Paddy
Bennett Place Point of Interest Le Grand 1/19/1972
Kaehler-Rector House National Merced 1/4/192
Lake Yosemite Water
Tower Point of Interest Merced 1/19/1972
Leggett House National Merced 10/25/1979
Leggett, Thomas H. House National Merced 7/8/1982
Los Banos State Landmark Los Banos 3/1/1956
Los Banos Creek Point of Interest Los Banos 6/2/1967
Merced County
Courthouse Point of Interest/National Merced 6/2/1967/10/29/1975 Merced County High
School National Merced 5/31/1984
Merced County Justice
Courthouse Building Point of Interest Gustine 8/25/1995 Merced Masonic
Temple/Welch & Griffith State Merced 11/3/2000
Merced Theatre National Merced 5/1/2009
Pacheco Pass State Landmark Los Banos 5/29/1969
San Luis Gonzaga
Archeological District National Los Banos 5/7/1973

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Property Name Register Jurisdiction Date Listed
Snelling Community
Recreational Hall Point of Interest Snelling 6/2/1967
Snelling Courthouse State Landmark Snelling 11/15/1948
Temporary Detention
Camps for Japanese
Americans-Merced
Assembly Center
State Landmark Merced 5/13/1980
Tioga Hotel National Merced 10/3/1980
U.S. Post Office National Merced 2/10/1983
Source: California Office of Historic Preservation
Other historic sites of local importance also exist. These include several cemeteries and churches located in the larger cities and other rural areas in the county. The five additional sites designated as California Historical Landmarks include the Canal Farm Inn, Los Banos Park, Merced Assembly Center at Merced County Fairgrounds, Pacheco Pass at Romero Outlook, and Snelling Courthouse. Other notable sites include Applegate Park; one of Merced’s central parks located along the Bear Creek Bikeway. The park is an excellent destination on bike or foot. It offers 32 acres of recreation with a zoo, outdoor theater, picnic tables, barbeque grills, volleyball nets, tennis/basketball courts, a skate park, rental facilities, a large playground, a rose garden and fountain, and the Kiwanas-sponsored Kiddieland amusement park.

Applegate Park is located along Bear Creek and the Bear Creek bikeway, between M and R Streets. The southern edge of the park follows 25th Street, P Street, and 26th Street.

Lists of designated historical resources change periodically, and they may not include those currently in the nomination process and not yet listed. Additionally, as defined by the National Environmental Policy Act (NEPA), any property over 50 years of age is considered a historic resource and is potentially eligible for the National Register. Thus, in the event that the property is to be altered, or has been altered, as the result of a major federal action, the property must be evaluated under the guidelines set forth by NEPA.

Structural mitigation projects are considered alterations for the purpose of this regulation.

Cultural resources defined in California Environmental Quality Act Section 15064.5 as include prehistoric and historic archeological resources; historic-period resources (buildings, structures, area, place, or objects). Archeological resources reflect past human activity extending from Native American prehistoric cultures throughout the early 20th century. The artifacts left by previous occupants may be encountered in small to large residential sites, or special use areas.

Many cultural and historical resources in the County are vulnerable to several hazards due to location and the nature of their construction. Some of these risks include earthquakes, wildfires, coastal storms, or adverse weather.

Natural Resources
Natural resources are important to include in benefit/cost analyses for future projects and may be used to leverage additional funding for mitigation projects that also contribute to community goals for protecting sensitive natural resources. Inventory and awareness of natural resource assets is vital to meeting conservation objectives. For example, protecting wetland areas provides sensitive habitat protection as well as floodwater conveyance and storage, which further enhances public safety.

The Merced National Wildlife Refuge which encompasses 10,258 acres of wetlands, native grasslands, vernal pools, and riparian areas. It was established in 1951 under the Lea Act to attract wintering waterfowl away from adjacent farmland where foraging ducks and geese were causing extensive damage

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to crops. Much of the Refuge is located in flood hazard areas and benefits the surrounding area by absorbing floodwaters and recharging aquifers.

To further understand natural resources that may be particularly vulnerable to a hazard event, as well as those that need consideration when implementing mitigation activities, it is important to identify at risk species (endangered and threatened species) in the Planning Area. The US Fish and Wildlife Service (USFW) maintains a list of federally listed threatened and endangered species for the country, which can be queried at the state or even county levels. The California Department of Fish and Wildlife also maintains species lists and accounts for threatened and endangered species. State and federal laws protect the habitat of these species through the environmental review process. Species of special concern may additionally include species that meets the State definition of threatened or endangered but has not been formally listed, experiences seriously population declines, or habitat decline, or has naturally small populations exhibiting high susceptibility to population decline (USFW 2019).

Table 4-9 summarizes Merced County’s special status animal species as indicated in the Fish and Wildlife Service database, within the Environmental Conservation Online System.

Table 4-9 Threatened and Endangered Species in Merced County Group Common Name Scientific Name Status
Amphibians California tiger Salamander Ambystoma californiense Threatened California red-legged frog Rana draytonii Threatened
Birds California condor Gymnogyps californianus Endangered Crustaceans
Conservancy fairy shrimp Branchinecta conservatio Endangered Vernal pool fairy shrimp Branchinecta lynchi Threatened Vernal pool tadpole shrimp Lepidurus packardi Endangered Fishes Delta smelt Hypomesus transpacificus Threatened
Flowering Plants
Greene's tuctoria Tuctoria greenei Endangered
Keck's Checker-mallow Sidalcea keckii Endangered
Colusa grass Neostapfia colusana Threatened
Hartweg's golden sunburst Pseudobahia bahiifolia Endangered Fleshy owl's-clover Castilleja campestris ssp.
succulenta Threatened
Hoover's spurge Chamaesyce hooveri Threatened
Hairy Orcutt grass Orcuttia pilosa Endangered
San Joaquin Orcutt grass Orcuttia inaequalis Threatened Insects
Monarch Butterfly Danaus plexippus Candidate
Valley elderberry longhorn
beetle Desmocerus californicus dimorphus Threatened
Mammals
Giant kangaroo rat Dipodomys ingens Endangered
San Joaquin kit fox Vulpes macrotis mutica Endangered
Fresno kangaroo rat Dipodomys nitratoides exilis Endangered Reptiles Blunt-nosed leopard lizard Gambelia silus Endangered Giant garter snake Thamnophis gigas Threatened
Source: USFW – Environmental Conservation Online System Growth and Development Trends
Population and Projected Growth
Merced County is the fastest growing county in the state, and the region as a whole is projected to grow significantly through 2060 (CA 4th CC Assessment). According to the Department of Finance (DOF) the 2020 population of Merced County as a whole was 283,521. DOF projects the total population will

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increase by 86% to 329,635 by 2030. While total households in the County is also projected to increase from 89,454 in 2020 to 97,063, people per households is project to slightly decrease from 3.43 to 3.31 person per household.

All of the incorporated communities expect Dos Palos (slight decrease -0.1) experienced an increase or no change in population between 2019 and 2020. The City of Merced is listed by the California DOF as one of the top ten cities under 300,000 with the largest numeric change (+2,209) in population between 2019 and 2020 (88,120).

Increases in population growth also increase exposure to severe weather-related hazards, pandemic/epidemics as well as earthquakes. This increase in growth also puts more demand on water resources and can increase vulnerability to drought.

Social Vulnerability
Social vulnerability considerations were included in the update of this plan in 2021 to identify areas across the County that might be more vulnerable to hazard impacts based on a number of factors. A social vulnerability index (SoVI) was developed by the Center for Disease Control’s (CDC) Agency for Toxic Substances and Disease Registry and their Geospatial Research, Analysis & Services Program teams, as a way to portray communities’ capacities to prepare for and respond to natural and manmade disasters. The SoVI does so by providing insight into particularly vulnerable populations to in turn assist emergency response planners and even public health officials identify communities more likely to require additional support before, during, and after a hazardous event. The CDC’s SoVI create county- and state level maps to show relative vulnerability and hence provide key socially and spatially relevant information on communities’ populations, and these maps compare the SoVI based on Census Tracts. The overall social vulnerability based on the SoVI data is shown for Merced County by Census Tracts in Figure 4-5 below, based on statewide ranking. This overall index combines four main themes of vulnerability, namely:
socioeconomic status; household composition and disability; minority status and language; and housing and transportation, which in turn are comprised of subcategories for a total of 15 variables accounting for various vulnerability factors. For additional information on the CDC’s SoVI, refer to their documentation and materials online at https://svi.cdc.gov/.

Based on this data, the areas with the highest level of social vulnerability in the County are in the western and southeastern portion of the County, as well as some of the incorporated jurisdictions including Merced and Los Banos.

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Figure 4-3 Overall Social Vulnerability in Merced County based on the SoVI, by Census Tracts

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Development Trends
As noted, the County has experienced population growth in the last decade and since the last plan update. There has been an increase in housing unit development, primarily in the cities of Merced, Gustine, Livingston and the unincorporated county. This new development built to modern codes should be less vulnerable to severe weather and earthquakes. Development in flood hazard areas should be mitigated to withstand the 1% annual chance flood; however, development in the 0.2% flood hazard zone is not regulated at this time. Although most development in the City of Merced and around the UC Merced campus has occurred in downtown Merced and in areas outside the floodplain.

Refer to Table 4-10 for comparison of housing units from the 2010 census to the ACS 5-Year estimates for 2015-2019 in the incorporated and unincorporated areas of Merced County. This comparison provides additional information on changes in development trends since the 2015 MJHMP was approved, for both the municipalities and the Census Designated Places (CDP) in the unincorporated areas.

Table 4-10 Housing Unit Development, 2010-2019
Jurisdiction 2010 2019 % Change
Merced County 83,698 85,251 2%
City of Atwater 9,771 9,577 -2%
Ballico CDP 132 182 38%
Bear Creek CDP 90 61 -32%
Cressey CDP 123 113 -8%
Delhi CDP 2,854 3,030 6%
City of Dos Palos 1,700 1,545 -9%
Dos Palos Y CDP 123 94 -24%
El Nido CDP 105 97 -8%
Franklin CDP 1,907 1,976 4%
City of Gustine 2,087 2,249 8%
Hilmar-Irwin CDP 1,841 2,001 9%
Le Grand CDP 503 554 10%
City of Livingston 3,320 3,699 11%
City of Los Banos 11,375 11,293 -1%
McSwain CDP 1,409 1,590 13%
City of Merced 27,446 26,873 -2%
Planada CDP 1,207 1,338 11%
Santa Nella CDP 493 614 25%
Snelling CDP 112 69 -38%
South Dos Palos CDP 488 629 29%
Stevinson CDP 101 154 52%
Tuttle CDP 39 48 23%
University of California Merced CDP 0 0 0%
Volta CDP 106 69 -35%
Winton CDP 3,056 3,305 8%
Source: California Dept. of Finance
The areas located in the Sphere of Influence (SOI) for each incorporated jurisdiction are areas each City plans to grow into and potentially slated for future development. Understanding the potential hazard exposure in each area can help to mitigate the impacts of events before development occurs in those areas. During this plan update process parcel analysis was conducted using the SOI areas for each incorporated jurisdiction and overlaid with available hazard risk layers to determine where future development may be at risk of natural hazard events. The results of the analysis have been integrated into

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the applicable hazard sections: dam, flood, wildfire and landslide. Table 4-10 is the summary of the SOI total exposure by jurisdiction.

Table 4-11 Total Exposure Summary by Jurisdiction Sphere of Influence Areas Jurisdiction Improved
Parcel Count
Building
Count Improved Value Estimated Content Value Total Value Atwater 675 837 $150,375,296 $124,680,732 $275,056,028
Dos Palos 545 688 $53,185,264 $32,248,327 $85,433,591
Gustine 97 126 $17,005,380 $15,800,283 $32,805,663
Livingston 60 85 $13,899,670 $12,073,468 $25,973,138
Los Banos 194 253 $28,473,256 $23,323,506 $51,796,762
Merced 2,528 2,896 $554,502,737 $328,069,420 $882,572,157 Total 4,099 4,885 $817,441,603 $536,195,735 $1,353,637,338 ● City of Dos Palos - Received approval for a grant that will fund the construction of a new Water Treatment facility. Once the new facility is completed and operational, development can begin on new residential and commercial projects.
● City of Merced - City Council voted in February of 2021 to move forward the annexation of UC Merced. This would allow for additional annexations to potentially occur and would include up to 7,800 acres of land. Currently, much of this land is rolling grass land or grazing land. Much of this property will likely be developed into commercial, retail and high-density housing to support the demands of UC Merced.
● Merced County – The HMPT noted the growth and development trends associated with UC Merced, high-speed rail and related transit-oriented growth and growth at Castle Air Force Base associated with autonomous vehicle testing.

4.2 Hazard Analysis and Risk Summary
Requirement §201.6(c)(2)(i):
[The risk assessment shall include a] description of the type, 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.

4.2.1 Dam Incidents
Hazard/Problem Description
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

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● Negligent operation
● Failure of upstream dams on the same waterway
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.

Controlled release or spillway flooding: Spillways are designed to relieve pressure on dams and prevent dam failures. Flooding downstream often results when spillways flow, though the potential for flooding as a result of discharge from dam outlet structures can also result from excessive rain events. However, controlled releases of water from dams is a measure that can prevent or minimize spillway flooding or structure failure, by regulating capacity in a managed way. Even controlled releases can lead to unwanted or unpredicted flooding, depending on environmental and weather conditions, or even human error.

In general, there are three types of dams: concrete arch or hydraulic fill, earth-rockfill, and concrete gravity. Each type of dam has different failure characteristics. A concrete arch or hydraulic fill dam can fail almost instantaneously: the flood wave builds up rapidly to a peak then gradually declines. An earthrockfill dam fails gradually due to erosion of the breach: the downstream flood wave will build gradually to a peak and then decline until the reservoir is empty. And a concrete gravity dam can fail instantaneously or gradually with a corresponding buildup and decline of the flood wave.

Geographic Area
According to the California Department of Water Resources’ Jurisdictional Dams and the National Inventory of Dams (NID) databases there are 44 dams of concern to Merced County; ten of which are in the County and 34 upstream of the County. Table 4-11 lists the high and significant hazard dams within and upstream of Merced County.

Figure 4-4 shows where the high and significant hazard dams are located, and the potential inundation areas based on the best available data at the time of this plan update. It is important to note that the inundation areas shown do not represent all dams that pose a risk; some of this information is not available in GIS or allowed for release in a public document. Virtually no urban area in the County is free from flooding in the event of dam failure. Potential impacts are greatest for Merced, Livingston and the central areas of the unincorporated Merced County.

Table 4-12 Dams of Concern Within and Upstream of Merced County County Dam Name River Downstrea
m City
Normal
Storage
Capacity
(Acre Feet)
Emergency
Action
Plan
(EAP)?
NID
Hazard
Rating

CA DSOD
Hazard
Rating*
Merced
Lake Yosemite Merced 10,323 No High Extremely High
Castle Canal Creek 7,510 No High Extremely High
Merced Falls Merced Snelling 603 Yes High Low
Burns Burns Creek Planada 6,800 Yes High -
Los Banos Creek
Detention
Los Banos
Creek
Los Banos 34,500 Yes High -

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County Dam Name River Downstrea
m City
Normal
Storage
Capacity
(Acre Feet)
Emergency
Action
Plan
(EAP)?
NID
Hazard
Rating

CA DSOD
Hazard
Rating*
O’Neill Forebay San Luis
Creek
Volta 56,430 Yes High -
B.F. Sisk Dike San Luis
Creek
- Yes High -
B.F. Sisk San Luis
Creek
2,094,900 Yes High -
Mustang Creek Mustang
Creek
700 No Significant Significant
Kelsey S. Fork Dry 1,000 No Significant Significant
Fresno
Alluvial Drain
Detention Big Dry Creek 833 No High
Big Dry Creek Big Dry Creek
& Dog Creek 30,200 No High
Fancher Creek
Fancher
Creek and
Hog Creek
9,600 No High
Fancher Creek
Detention
Fancher
Creek 1,891 No High
Friant Dike 3 520,500 Yes High
Friant Millerton
Road
Embankment A
San Joaquin
River Fresno 520,500 Yes High
Griffen Reservoir Holland
Creek
900 Yes High
Little Panoche
Detention
Little
Panoche
Creek
Oro Loma
5,580
Yes High
Pine Flat Dam Kings Sanger 1,000,000 Yes High
Redbank Redbank
Creek
1,100 No High
Redbank Creek
Detention Basin
Redbank
Creek
940
No High
Madera
Buchanan Dam Chowchilla
River Chowchilla 105,000 Yes High
Friant San Joaquin
River Fresno 520,500 Yes High
Hidden Dam Fresno River Madera 90,000 Yes High
Madera Lake Fresno River 2,300 No High
Berenda Slough Berenda
Slough 2,450 No Significant
Black Hawk Coarse Gold
Cr 740 No Significant
Mendota
Diversion
San Joaquin
River 3,000 No Significant
Oakhurst
Wastewater
Treatment
Tr Fresno
River 110 No Significant

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County Dam Name River Downstrea
m City
Normal
Storage
Capacity
(Acre Feet)
Emergency
Action
Plan
(EAP)?
NID
Hazard
Rating

CA DSOD
Hazard
Rating*
Spring Longhollow
Creek 152 Yes Significant
Upper Wilcox
Unnamed
Tributary to
Picayunne
Creek
200 No Significant
Mariposa
Bear Dam Bear Creek Planada 7,700 Yes High
Exchequer Dike Merced River Snelling 1,024,600 Yes High Exchequer Main Merced River Snelling 1,024,600 Yes High Mariposa Dam Mariposa
Creek Le Grand 15,000 Yes High
Mcswain Merced River Snelling 8,255 Yes High
Owens Dam Owens Creek Planada 3,600 Yes High
Stockton Creek Stockton
Creek 368 No High
Stanislaus Turlock Lake Tuolumne
River 63,406 Yes High
Tuolumne
Don Pedro Dike
B
Tuolumne
River La Grange 2,030,000 Yes High
Don Pedro Main Tuolumne
River La Grange 2,030,000 Yes High
Gasburg Creek
Dike
Tuolumne
River La Grange 1 Yes High
Don Pedro Dike
A
Tuolumne
River La Grange 2,030,000 Yes Significant
Don Pedro Dike
C
Tuolumne
River La Grange 2,030,000 Yes Significant
Source: California Department of Water Resources Division of Safety of Dams (DSOD) and the NID * DSOD added a fourth category (“Extremely High”) to the NID categories for downstream hazard potential. Extremely High is defined as expected to cause considerable loss of human life or would result in an inundation area with a population of 1,000 or more.

Analysis using inundation data and mapping associated with the O’Neil Forebay, Los Banos, and San Luis dams was not possible for the plan due to information being considered sensitive and restricted, per communication with OES and the dam owners. The following is a summary of the downstream communities that would be affected by each dam in a dam failure or incident based on information in dam emergency action plans, including depth of inundation and time to inundation. ● O’Neil Forebay Dam
- Santa Nella: 4-10 feet within 5 hours of failure
- Ingoma: 0-2 feet within 10 hours
- Volta: 2-4 feet within 5 hours
● Los Banos Dam
- Los Banos: 5-6 feet within 2.5 hours
- Volta: 5-6 feet within 2.5 hours
- Trent: 5-6 feet within 2.5 hours

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● San Luis Dam
- Santa Nella: 10-20 ft within 2 hours
- Volta: 10-20 ft in less than 10 hours
- Ingomar: 10-20 ft in less than 10 hours
- Trent: 2-4 ft in 5 hours
- Gustine: 2-10 ft in less than 10 hours
- Stevenson: 2-10 in 15 hours

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Figure 4-4 Dams of Concern to Merced County and Best Available Inundation Mapping

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Extent (Magnitude/Severity)
Standard practice among federal and state dam safety offices is to classify a dam according to the potential impact a dam failure (breach) or mis-operation (unscheduled release) would have on downstream areas. The hazard potential classification system categorizes dams based on the probable loss of human life and the impacts on economic, environmental and lifeline facilities. The US Army Corp of Engineers uses three categories to classify dams’ potential hazard to life and property:
● High hazard indicates that a failure would most probably result in the loss of life; ● Significant hazard indicates that a failure could result in appreciable property damage; ● Low hazard indicates that failure would result in only minimal property damage and loss of life is unlikely.
● Undetermined hazard dams have not been rated or their hazard rating is not known In addition to these, high, significant, and low hazard classifications the California Division of Dam Safety (DSOD) adds the fourth category of “Extremely High”. The DSOD defines this fourth category as “expected to cause considerable loss of human life or would result in an inundation area with a population of 1,000 or more” (DSOD 2020). As shown in Table 4-11 two dams in Merced County, Lake Yosemite and Castle dams are classified as “Extremely High”.

In 2017 the State of California established the Spillway Re-evaluation Program after the Orville Dam incident, to assess spillways to confirm they meet minimum safety standards. The Don Pedro dam located in Tuolumne County was listed as being part of this program and poses a risk to central portions of Merced County.

Since the County has several high and significant hazard dams, there is potential for loss of life and property damage. 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 Merced County. The extent of impacts depends on the nature of failure and location of the dam. The largest populations potentially at risk would be in Merced, Livingston, and Atwater. The central portions of the unincorporated areas county would also be impacted were a dam to fail and flood downstream.

Past Occurrences
There is no history of dam failure affecting the county, but according to the HMPT there have been recurring issues with flooding due to high flows released below dams in the area.

Probability of Future Occurrences
Occasional—The County remains at risk to dam failures from numerous dams under a variety of ownership and control and of varying ages and conditions. However, based on historical experience dam failure is unlikely in the area. Nevertheless, given the number of dams of concern in the County the potential exists for future dam failures in Merced County, but the likelihood of this is low. Uncontrolled or controlled release flooding as well as spillway 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 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

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water resources become more limited or stretched in the future due to climate change, drought and/or population growth.

Vulnerability Assessment
A dam incident can range from a small, uncontrolled release to a catastrophic failure. Vulnerability to dam failures is confined to the areas and populations subject to inundation downstream of the facility.

Secondary losses would include loss of the multi-use functions of the dam itself and associated revenues that accompany those functions.

General Property
In general, communities located below a high or significant hazard dam and along a waterway are potentially exposed to the impacts of a dam failure. Inundation maps that identify anticipated flooded areas (which may not coincide with known floodplains) are typically produced for all high hazard dams and included in the Emergency Action Plan (EAP) required for each dam. A GIS layer that contained inundation maps for four of the 34 high hazard dams that affect the County was analyzed to quantify risk across the planning area. Table 4-13 through Table 4-16 summarize the estimated building exposure (more details on the parcel analysis methodology under the Asset Summary section). Table 4-12 summarizes the results of the GIS analysis, and includes a population estimate based on the number of residential parcels exposed, multiplied by an average household size estimate from the census. Exposure estimates from failure of other high hazard dams were not possible due to data restrictions and/or limitations.

Table 4-13 Summary of Dam Inundation by Dam and Jurisdiction Dam Jurisdiction Improved
Parcel Count
Building
Count Population
Don Pedro Dam
Livingston 1 1 -
Unincorporated 3,888 4,909 8,353
Total 3,889 4,910 8,353
McSwain Dam
Livingston 1 1 -
Unincorporated 160 180 309
Total 161 181 309
New Exchequer Dam
Atwater 37 37 -
Livingston 3,340 4,001 14,216
Unincorporated 8,869 11,138 19,505
Total 12,246 15,176 33,721
Yosemite Dam
Atwater 21 23 67
Merced 4,768 6,080 18,784
Unincorporated 1,024 1,359 3,214
Total 5,813 7,462 22,065
Grand Total 22,109 27,729 64,447
Source: California DSOS, NID, Merced County Assessor’s Office Table 4-14 Don Pedro Dam Inundation
Jurisdiction Property Type Improved
Parcel Count Building Count
Livingston Agricultural 1 1
Total 1 1
Unincorporated Agricultural 1,352 1,968
Commercial 97 333

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Jurisdiction Property Type Improved
Parcel Count Building Count
Exempt 40 56
Industrial 15 19
Mixed Use 2 2
Residential 2,365 2,514
Vacant Land 17 17
Total 3,888 4,909
Grand Total 3,889 4,910
Source: California DSOS, NID, Merced County Assessor’s Office Table 4-15 McSwain Dam Inundation
Jurisdiction Property Type Improved
Parcel Count Building Count
Livingston Agricultural 1 1
Total 1 1
Unincorporated
Agricultural 48 59
Commercial 13 18
Exempt 7 8
Industrial 1 1
Residential 90 93
Vacant Land 1 1
Total 160 180
Grand Total 161 181
Source: California DSOS, NID, Merced County Assessor’s Office Table 4-16 New Exchequer Dam Inundation
Jurisdiction Property Type Improved
Parcel Count
Building Count
Atwater Residential 37 37
Total 37 37
Livingston
Agricultural 8 9
Commercial 79 231
Exempt 48 113
Industrial 19 33
Mixed Use 3 4
Residential 3,176 3,604
Vacant Land 7 7
Total 3,340 4,001
Unincorporated
Agricultural 3,183 4,415
Commercial 223 603
Exempt 101 144
Industrial 41 64
Mixed Use 12 15
Residential 5,273 5,860
Vacant Land 36 37
Total 8,869 11,138
Grand Total 12,246 15,176
Source: California DSOS, NID, Merced County Assessor’s Office

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Table 4-17 Lake Yosemite Dam Inundation
Jurisdiction Property Type Improved
Parcel Count
Building Count
Atwater
Commercial 1 2
Residential 20 21
Total 21 23
Merced
Agricultural 5 5
Commercial 24 30
Exempt 110 134
Industrial 22 38
Mixed Use 1 1
Residential 4,603 5,869
Vacant Land 3 3
Total 4,768 6,080
Unincorporated
Agricultural 36 46
Commercial 34 305
Exempt 10 12
Industrial 18 22
Mixed Use 3 3
Residential 917 965
Vacant Land 6 6
Total 1,024 1,359
Grand Total 5,813 7,462
Source: California DSOS, NID, Merced County Assessor’s Office People
Persons located underneath or downstream of a dam are at risk of a dam failure, though the level of risk can be tempered by topography (specifically where populations are located within the inundation path of a dam), amount of water in the reservoir and time of day of the breach. Injuries and fatalities can occur from debris, bodily injury and drowning. Once a dam has breached, standing water presents all the same hazards to people as floodwater from other sources. People in the inundation area may need to be evacuated, cared for, and possibly permanently relocated. Impacts could include thousands of evacuations and likely hundreds of casualties, depending on the dam involved. Specific population impacts are noted in Table 4-12 , and total people at risk were calculated by multiplying the average number of persons per household in Merced County (3.32) and each applicable incorporated jurisdiction (Atwater 3.18, Livingston

3.94, and Merced 3.20) times the number of residential parcels where dam inundation occurs. Based on the best available data accessible to the planning team at this time of this analysis, an incident at the New Exchequer Dam would potentially put the most people at risk (33,721), followed by Lake Yosemite dam (22,064) and Don Pedro dam (8,353). The unincorporated areas of Merced County have the most people (31,381) potentially exposed to a dam inundation event followed by City of Merced with potentially 18,784 exposed to the Lake Yosemite dam inundation. Population impacts from other high hazard dams were not possible due to data restrictions and/or limitations.

Critical Facilities
A total dam failure can cause catastrophic impacts to areas downstream of the water body, including critical infrastructure. Any critical asset located under the dam in an inundation area would be susceptible to the impacts of a dam failure. Of particular risk would be roads and bridges that could be vulnerable to washouts, further complicating response and recovery by cutting off impacted areas. Based on the critical facility inventory considered in the updating of this plan and intersected with the dam inundation extents

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available, 272 critical facilities were found to be at risk. Unincorporated County has the greatest number of facilities at risk followed by City of Merced and City of Livingston. These at risk facilities are listed in the tables below by jurisdiction and critical facility classification as based on the FEMA Lifeline categories.

Table 4-18 Dam Inundation Effects on Critical Facilities – Estimates by Jurisdiction and FEMA Lifeline
Jurisdiction
CommunicationsEnergyFood, Water, ShelterHazardous MaterialHealth and MedicalSafety and SecurityTransportationTotal Atwater - - - - - - 1 1
Dos Palos - - - - - - - 0
Gustine - - - - - - - 0
Livingston 6 1 3 3 - 13 5 31
Los Banos - - - - - - - 0
Merced 4 2 6 3 3 4 13 35
Unincorporated 21 8 16 8 - 64 88 205
Total 31 11 25 14 3 81 107 272
Source: HFILD, Merced County, Cities of Atwater, Dos Palos, Gustine, Livingston, Los Banos, Merced As noted under the Geographic Area section, inundation data is not available for the O’Neil Forebay, Los Banos or San Luis Dams due to being restricted and sensitive information. The following is a summary of the potential impacts on critical facilities from a dam failure or inundation event. ● O’Neil Forebay Dam
- Potential Impacts to Transportation infrastructure:
o Interstate 5
o Highway 33
o Highway 140
- Potential Impacts to Water Systems infrastructure:
o Delta Mendota
o The California Aqueduct
● Los Banos Dam
- Potential impacts to Transportation infrastructure:
o Interstate 5
o Highway 152
o Highway 165
- Potential impacts to Water Systems infrastructure:
o Delta Mendota
o The California Aqueduct
● San Luis Dam
- Potential impacts to Transportation infrastructure:
o Interstate 5
o Highway 152

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o Interstate 165
o Highway 33
o Highway 140
- Potential impacts to Water Systems infrastructure:
o Delta Mendota
o The California Aqueduct
- Potential impacts to Power/Energy infrastructure:
o PG&E substations
o Solar fields
Economy
Extensive and long-lasting economic impacts could result from a major dam failure including the longterm loss of water in a reservoir after a failure event. Based on the analysis there is 6,504 buildings, at a minimum, that are designated as agricultural properties potentially exposed to dam inundation event. A major dam incident and loss of water from the associated reservoir could include direct business and specifically impacts to the agricultural industry, resulting in damages and indirect disruption of the local economy.

Historic, Cultural and Natural Resources
Dam failure effects on the environment would be similar to those caused by flooding from other causes.

Water could erode stream channels and topsoil and cover the environment with debris. For the most part the environment is resilient and would be able to rebound from whatever damages occurred, though this process could take years. However, historic and cultural resources could be affected just as housing or critical infrastructures would, were a dam to fail and cause downstream inundation that could further erode surfaces or cause scouring of structural foundations.

Future Development
GIS was used to analyze parcels exposed to dam inundation areas that are located within each city’s SOI.

The results shown in Table 4-18 show that there is a total of 6,917 buildings and 18,247 currently exposed to dam inundation within the SOI areas.

Table 4-19 Total Dam Inundation Summary by Dam within Sphere of Influence Areas Dam Inundation Sphere of
Influence
Improved
Parcel Count
Building
Count Population
Don Pedro Dam
Delhi 55 55 183
Hilmar 1,450 1,778 4,731
Livingston 1 3 0
Total 1,506 1,836 4,914
McSwain Dam
Cressey 1 1 3
Livingston 1 1 0
Snelling 104 111 286
Total 106 113 289
New Exchequer Dam
Atwater 10 12 7
Ballico 59 65 166
Cressey 78 92 262
Delhi 1,021 1,319 3,788
Hilmar 1,450 1,778 4,731
Livingston 59 83 149
Snelling 145 170 412

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Dam Inundation Sphere of
Influence
Improved
Parcel Count
Building
Count Population
Stevinson 53 65 149
Winton 98 113 375
Total 2,973 3,697 10,040
Yosemite Dam
Atwater 42 44 120
Franklin 774 1,080 2,520
Merced 128 147 365
Total 944 1,271 3,005
Grand Total 5,529 6,917 18,247
Source: California DSOS, NID, Merced County Assessor’s Office The areas located in the SOI for each incorporated jurisdiction are areas each City plans to grow into and potentially slated for future development. In addition to the SOI areas there are also 71 vacant parcels countywide that are within dam inundation areas. These areas should take into consideration potential impacts from dam failure risk upstream and should attempt to overlay the existing dam inundation maps with proposed future development. In the case of a dam failure, inundation would likely follow some existing FEMA mapped floodplains, which contains development restrictions for areas in the 1% annual chance floodplain, but it could exceed those floodplains and affect areas that are not regulated for flood hazards. Also, of note is that development below a low or undetermined hazard dam could increase its hazard rating, though there is only one low hazard and one undetermined hazard dam in the County (while the majority are high or significant hazard dams). Finally, added development could compromise dams and reservoir resources if populations depend on them for critical needs such as potable water during or after a dam failure event.

Risk Summary
● There are 44 dams of concern for Merced County. 10 are within the county (8 High Hazard Potential and two Significant) and 34 dams are upstream of the county (26 High Hazard and eight Significant). ● Of the eight high hazard potential rated dams in the County, 2 (Castle and Yosemite dams) are rated as “Extremely High” by the State of California DSOD.
● Countywide there are a minimum of 27,729 parcels at risk based on limited available inundation mapping, with greatest number of buildings exposed in unincorporated areas (17,586) followed by the City of Merced (6,080), City of Livingston (4,003) and City of Atwater (60). ● Residential property types make up the most buildings (18,963) at risk of flooding from dam failures, agricultural (6,504), and commercial (1,522).
● Based on limited available mapping, the New Exchequer Dam puts the most parcels at risk of dam inundation (33,721) countywide (most in Unincorporated and Livingston), followed by the Yosemite dam (22,065).
● An estimated 64,447 people countywide might be displaced from their homes based the location of their residences along the inundation areas; actual amounts would vary. ● A total of 272 critical facilities are within dam inundation areas. The greatest number in unincorporated Merced County (205) and Transportation lifeline is most at risk countywide. ● Related Hazards: drought, flooding, earthquake/liquefaction, landslide, and severe weather.

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Table 4-20 Hazard Risk Summary by Jurisdiction - Dam Incidents Jurisdiction Geographic Area
Probability of
Future
Occurrence
Magnitude/
Severity
Overall
Significance
Merced County Significant Occasional Catastrophic Medium City of Atwater Extensive Occasional Limited Medium
City of Dos Palos Limited Occasional Limited Medium
City of Gustine Extensive Occasional Limited Low
City of Livingston Limited Occasional Limited Medium
City of Los Banos Extensive Occasional Catastrophic Medium City of Merced Extensive Occasional Catastrophic High

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4.2.2 Drought
Hazard/Problem Description
Drought is a gradual phenomenon. Normally, one dry year does not constitute a drought in California, but rather serves as a reminder of the need to plan for droughts. California's extensive system of water supply infrastructure (reservoirs, groundwater basins, and interregional conveyance facilities) generally mitigates the effects of short‐term dry periods for most water users.

Drought can have secondary impacts. For example, drought is a major determinant of wildfire hazard, in that it creates greater propensity for fire starts and larger, more prolonged conflagrations fueled by excessively dry vegetation, along with reduced water supply for firefighting purposes. Drought is also an economic hazard. Significant economic impacts on California’s agriculture industry can occur as a result of short‐ and long‐term drought conditions; these include hardships to farmers, farm workers, packers, and shippers of agricultural products. In some cases, droughts can also cause significant increases in food prices to the consumer due to shortages.

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 on 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 other drought indicators. ● Socioeconomic 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.

The California Department of Water Resources (DWR) says the following about drought:
“One dry year does not normally constitute a drought in California. California’s extensive system of water supply infrastructure—its reservoirs, groundwater basins, and interregional 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

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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 problems that can occur as a result of drought conditions. The reduced demand for electrical power generation is commonly linked to higher electricity costs due to the loss of hydropower supplies. Water quality deterioration is due to lower levels of precipitation and limited water storage supply. Drought conditions can also cause soil to compact and not absorb water well, potentially making an area more susceptible to flooding.

Geographic Area
Drought is a regional hazard, and at its worst can affect the entire state of California with varying levels of dryness and drought activity (as will be covered in more detail under the sections to follow). It is safe to assume that unless the drought event is at its very beginning or very end, if any area of the Merced County is affected by any level of drought, the other areas of the county are experiencing varying effects as well.

Sustainable Groundwater Management Act (SGMA) of 2014
In January 2014, Governor Brown declared an emergency proclamation due to multiple years of drought.

The proclamation called on citizens to reduce water use by 20 percent; with a subsequent executive order in April 2015 that directed urban water agencies to reduce water use by 25 percent (Ken Topping, 2016).

In September 2014, the Governor signed a three-bill package (California Senate Bills 1168 and 1319, and Assembly Bill 1739), known as the SGMA. The SGMA provides for the establishment of local GSAs to manage groundwater sustainability within the groundwater subbasins defined by the California DWR.

Within Merced County there are portions of four groundwater subbasins, Merced, Turlock, Delta Mendota, and Chowchilla, that are required under SGMA to conduct sustainable groundwater planning and management. Each of the four subbasins are required to develop and implement a GSP by 2020 or 2022.

As of April 2021, all four subbasins have formed 14 GSAs as shown in Table 4-20.

Table 4-21 Groundwater Sustainability Agencies in Merced County Subbasin Groundwater Sustainability Agency (GSA)
Merced
Merced-Irrigation-Urban GSA
Merced Subbasin GSA
Turner Island Water District GSA #1
Turlock West Turlock GSA
East Turlock GSA
Delta Mendota
City of Dos Palos GSA
City of Gustine GSA
City of Los Banos GSA
Central Delta Mendota GSA
Turner Island Delta Mendota GSA
Northwestern Delta Mendota GSA
Grassland Water District GSA
San Joaquin River Exchange Contractors GSA
Chowchilla Chowchilla Water District GSA
County of Merced Chowchilla GSA
Source: Merced County Water Resources https://www.co.merced.ca.us/3140/Sustainable-Groundwater---SGMA

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Extent (Magnitude/Severity)
The magnitude of a drought’s impact is directly related to the severity and length. The severity of a drought depends on water availability and moisture deficiency, the time period, and the size and location of the affected area. The longer the drought persists and the larger the area impacted, the more severe the potential impacts. Droughts can be a short-term event over several months or a long-term event that lasts for years or even decades. In Merced County, the onset of drought is often signaled by a lack of significant winter precipitation and snowfall (moisture deficiency) in the Sierra Nevada Mountains.

Droughts typically do not result in direct impacts on people or property, but they can have significant impacts on agriculture, which can indirectly impact people and property. Hot and dry conditions that persist into spring, summer, and fall can aggravate drought conditions, making the effects of drought more pronounced as water demands increase during the growing season and summer months. Impacts increase with the length of a drought, as carry over supplies in reservoirs are depleted and water levels in groundwater basins decline (California DWR 2012).

The U.S. Drought Monitor is an accepted and widely used site for obtaining and summarizing drought information, as it integrates data from several other sources including the Palmer Drought Index, Soil Moisture Models, U.S. Geological Survey Weekly Stream Flows, Standardized Precipitation Index, and the Satellite Vegetation Health Index. It includes drought intensity categories for measuring dry conditions across counties, states, and regions of the U.S., so that drought can be quantified. These categories range from “abnormally dry” to “exceptional drought.” The following figures provide “snapshots in time” of the drought conditions in California as of August 2015 (during the period of the last multi-year drought in Merced County and the state, from 2012- 2017) and March 30, 2021. The snapshots selected are instrumental in depicting both the historic and potential change in drought’s geographic range and severity in the County (circled in blue).

Note: The Drought Monitor maps integrate data from several sources including the Palmer Drought Index, Soil Moisture Models, U.S. Geological Survey Weekly Stream flows, Standardized Precipitation Index, and Satellite Vegetation Health Index. The drought status in California is noted on the following graphic from the National Drought Mitigation Center.

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Figure 4-5 U.S. Drought Monitor for California: August 4, 2015

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Figure 4-6 U.S. Drought Monitor for California: March 30, 2021 Past Occurrences
Historically, California has experienced severe drought conditions. The state’s available record for determining hydrologic risks is short, only going back about 100 years. Recent droughts affecting Merced County are summarized below using data from Cal OES and from the County Agricultural Commissioner’s Office.
● 1928-1937—This drought affected the entire state and is the longest, most severe drought on record with a recurrence interval of greater than 100 years.
● 1947-1950—Drought affected the entire state but was most extreme in Southern California. The drought in winter of 1950 affected the area from the Kern River basin north to the American River basin. The drought caused two deaths and $33 million in damages. ● 1976-1977—The drought of 1976-1977 was most severe in the northern three-quarters of California, but the impact was experienced statewide because of the dependence of Southern California on water transfers from the north. The water year 1977 was the driest year of record at almost all gauging stations in the affected area in California, and the water year 1976 was among the five driest in the central and northern Sierra Nevada. The two-year deficiency in runoff accumulated during the drought is unequalled at gauging stations in the affected area; and this deficiency has a recurrence interval that exceeds 80 years. Crop damages statewide were $2.67 billion. ● 1987-1992—California experienced a serious drought due to low precipitation and runoff levels.

During this multi-year, multi-county drought, the runoff from the San Joaquin Valley was 47 percent of average. In 1991, the U.S. Department of Agriculture Economic Research Report Agricultural Outlook reported that the Merced River flow would be inadequate to provide sufficient water for

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agricultural uses for the fifth consecutive year. A U.S. Department of Agriculture (USDA) drought disaster declaration was declared.
● 2004-2005—On January 15, 2005, the USDA designated 53 of California’s 58 counties as natural disaster areas due to damages and losses caused by extreme drought. ● 2008-2009—On June 12, 2008, the Governor proclaimed Merced County as a state disaster area due to the Central Valley Drought.
● 2012 – 2017—In September 2012, the USDA designated Merced County a contiguous disaster area due to drought that occurred since January 1, 2012. In January 2014, the Governor proclaimed a State of Emergency and directed state officials to take all necessary actions to prepare for these drought conditions: to assist farmers and communities that are economically impacted by dry conditions and to ensure the state can respond if Californians face drinking water shortages. The Governor also directed state agencies to use less water and hire more firefighters and initiated an expansive water conservation public awareness campaign. 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. 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." (NCICS 2019). According to the 2018 State of California Hazard Mitigation Plan, by the time the drought was declared officially in 2017, the state been declared a federal disaster area and had expended $6.6 billion in drought response and mitigation programs.

As shown in Table 4-4, of the 18 total Secretary of Agricultural Disaster Designations for Merced County in the past 8 years, 15 were specific to drought. In addition to the USDA designations there have also been two federal disaster declarations due to drought in the county (Refer to Table 4-3).

The National Drought Mitigation Center developed the Drought Impact Reporter in response to the need for a national drought impact database for the United States. Information comes from a variety of sources:
online, drought-related news stories and scientific publications, members of the public who visit the website and submit a drought-related impact for their region, members of the media, and members of relevant government agencies. The database is being populated beginning with the most recent impacts and working backward in time. The Drought Impact Reporter contains information on 195 impacts from droughts that affected Merced County between 2000 and 2020. Most of the impacts (113) were classified as “water supply and quality” and “relief, response and restrictions” (101). Other impacts included “agriculture” (79), “society and public health” (72), “plants and wildlife” (23), “fire” (16), “business and industry” (13), “tourism and recreation” (7) and “energy” (6). These categories are described as follows:
● Water Supply and Quality (113) —Drought effects associated with water supply and water quality include dry wells, voluntary and mandatory water restrictions, changes in water rates, increasing of water restrictions, increases in requests for new well permits, changes in water use due to water restrictions, greater water demand, decreases in water allocation or allotments, installation or alteration of water pumps or water intakes, changes to allowable water contaminants, water line damage or repairs due to drought stress, drinking water turbidity, change in water color or odor, declaration of drought watches or warnings, and mitigation activities.

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● Relief, Response, and Restrictions (101) —This category refers to drought effects associated with disaster declarations, aid programs, requests for disaster declaration or aid, water restrictions, or fire restrictions. Examples include disaster declarations, aid programs, USDA Secretarial disaster declarations, Small Business Association disaster declarations, government relief and response programs, state level water shortage or water emergency declarations, county-level declarations, a declared “State of Emergency,” requests for declarations or aid, nonprofit organization based relief, water restrictions, fire restrictions, National Weather Service (NWS) Red Flag Warnings, and declaration of drought watches or warnings.
● Agriculture (79) —Drought effects associated with agriculture, farming, aquaculture, horticulture, forestry, or ranching. Examples of drought-induced agricultural impacts include damage to crop quality; income loss for farmers due to reduced crop yields; reduced productivity of cropland; insect infestation; plant disease; increased irrigation costs; cost of new or supplemental water resource development (wells, dams, pipelines) for agriculture; reduced productivity of rangeland; forced reduction of foundation stock; closure/limitation of public lands to grazing; high cost or unavailability of water for livestock, Christmas tree farms, forestry, raising domesticated horses, bees, fish, shellfish, or horticulture.
● Society and Public Health (72) —Drought effects associated with human, public and social health include: health-related problems related to reduced water quantity or quality, such as increased concentration of contaminants; loss of human life (e.g., from heat stress, suicide); increased respiratory ailments; increased disease caused by wildlife concentrations; increased human disease caused by changes in insect carrier populations; population migration (rural to urban areas, migrants into the United States); loss of aesthetic values; change in daily activities (non-recreational, like putting a bucket in the shower to catch water); elevated stress levels; meetings to discuss drought; communities creating drought plans; lawmakers altering penalties for violation of water restrictions; demand for higher water rates; cultural/historical discoveries from low water levels; cancellation of fundraising events; cancellation/alteration of festivals or holiday traditions; stockpiling water; public service announcements and drought information websites; protests; and conflicts within the community due to competition for water.
● Plants and Wildlife (23)—Drought effects associated with unmanaged plants and wildlife, both aquatic and terrestrial, include: loss of biodiversity of plants or wildlife; loss of trees from rural or urban landscapes, shelterbelts, or wooded conservation areas; reduction and degradation of fish and wildlife habitat; lack of feed and drinking water; greater mortality due to increased contact with agricultural producers (as predators seek food from farms and producers are less tolerant of the intrusion); disease; increased vulnerability to predation (from species concentrated near water); migration and concentration (loss of wildlife in some areas and too much wildlife in others); increased stress on endangered species; salinity levels affecting wildlife; wildlife encroaching into urban areas; and loss of wetlands.
● Fire (16)—Drought often contributes to forest, range, rural, or urban fires, fire danger, and burning restrictions. Specific impacts include enacting or increasing burning restrictions, fireworks bans, increased fire risk, occurrence of fire (number of acres burned, number of wildfires compared to average, people displaced, etc.), state of emergency during periods of high fire danger, closure of roads or land due to fire occurrence or risk, and expenses to state and county governments of paying firefighters overtime and paying equipment (helicopter) costs. ● Business and Industry (13) —This category tracks drought’s effects on non-agriculture and nontourism businesses, such as lawn care, recreational vehicles, or gear dealers, and plant nurseries.

Typical impacts include reduction or loss of demand for goods or services, reduction in employment, variation in number of calls for service, late opening or early closure for the season, bankruptcy, permanent store closure, and other economic impacts.

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● Tourism and Recreation (7) —Drought effects associated with recreational activities and tourism include closure of state hiking trails and hunting areas due to fire danger; water access or navigation problems for recreation; bans on recreational activities; reduced license, permit, or ticket sales (e.g., hunting, fishing, ski lifts, etc.); losses related to curtailed activities (e.g., bird watching, hunting and fishing, boating, etc.); reduced park visitation; and cancellation or postponement of sporting events. ● Energy (6)—This category concerns drought's effects on power production, rates and revenue.

Examples include production changes for both hydropower and non-hydropower providers, changes in electricity rates, revenue shortfalls and/or windfall profits, and purchase of electricity when hydropower generation is down.

Probability of Future Occurrences
Likely – Historical drought data for the County planning area and the San Joaquin Valley region indicate there have been five significant multi-year droughts in the last 91 years. This equates to a multi-year drought every 18 years on average, or a 5 percent chance of a drought in any given year. Based on this data, droughts will likely affect the planning area. Given the historical occurrence of severe drought impacts throughout Merced 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 cascading or compound hazards), and local economies.

In addition, although drought affects the entire planning 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.

Climate Change Considerations
Water resources in California area already experiencing stresses related to population growth, increased water demand, poor water quality, groundwater overdraft, and aging infrastructure. Scientific studies prepared for various California climate assessments and adaptations strategies also already show that drought conditions in California are likely to become more frequent and persistent over the next century due to climate change. Temperatures are warming, heat waves are more frequent, and precipitation has become increasingly variable (California Natural Resources Agency 2018a). According to California’s Climate Adaptation Strategy, also referred to as “Safeguarding California Plan: 2018 Update”, climate change is likely to significantly diminish California’s future water supply. As a result, the state must change its water management, as climate change will create greater competition for limited water supplies (California Natural Resources Agency 2018b). The recent drought conditions over the past decade underscore the need to examine water supply and distribution management, conservation, and use policies. California and the San Joaquin Valley region have experienced a succession of dry spells and with warmer temperatures and periodic droughts that frequently contribute to water shortages in the region.

Climate change projections of extreme prolonged droughts will exacerbate the San Joaquin Valley’s existing water supply challenges. In an average year, approximately 40 percent of the state’s total water supply comes from groundwater, and during a dry year this increases to more than half of the state’s water supply, with groundwater acting as a critical buffer against the impacts of drought and climate change (California Natural Resources Agency 2018).

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Table 4-22 Summary of Climate Change Impacts on Water Resources Resource Type of
Impact Description
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
Source: http://frap.fire.ca.gov/data/assessment2010/pdfs/3.1water.pdf p. 140 Vulnerability Assessment
All of Merced County is vulnerable to drought. Drought is one of the few hazards with the potential to impact all the citizens of the county through water restrictions, economic losses, and increased energy costs. The urbanized areas of the county and the agriculture industry are most likely to experience hardships associated with reduced water supply.

Impacts include water restrictions associated with domestic supplies, agricultural and livestock losses and economic impacts, hydroelectric power reductions, and increased costs for water. Secondary effects include susceptibility to wildfires and increased groundwater pumping that can contribute to land subsidence problems and degraded water quality.

General Property
Based on the USDA’s Risk Management Agency (RMA) Crop Indemnity Reports, which were collected for the years 2007-2020, crop losses due to drought were only reported between 2007 and 2014 across the county. Table 4-22 summarizes the agricultural losses experienced across the county communities. A total of $885,477 was indemnified for 14,660 acres of insured crops.

Table 4-23 Crops Loss Due to Drought, Risk Management Agency Crop Indemnity Reports, 2007-2020
Year Crop
Net
Determined
Acres
Indemnity
Amount
2007
Wheat 301.9 $16,130
Oats 228.3 $1,241
Barley 1,345.9 $32,857

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Year Crop
Net
Determined
Acres
Indemnity
Amount
Total 1,876 $50,228
2008
Wheat 683.2 $75,727
Oats 1,376.3 $34,192
Barley 960.9 $45,245
Total 3,020 $155,164
2009
Wheat 2,179.4 $280,639
Oats 882.7 $32,334
Barley 1,534.2 $74,455
Total 4,596 $387,428
2010 Wheat 860.2 $5,599
Total 860.2 $5,559
2011 Wheat 170 $22,806
Total 170 $22,806
2012
Wheat 1,910.3 $167,880
Oats 1,482 $56,827
Total 3,392 $224,707
2013
Wheat 243.9 $8,907
Oats 35 $633
Total 279 $9,540
2014
Wheat 313.9 $26,623
Oats 151.4 $3,382
Total 465 $30,005
Grand Total 14,660 $885,477
Source: USDA RMA Crop Indemnity Reports, 2007-2020
People
According to this California DOF the 2020 County population was 283,521 people. The County’s population is projected to continue to increase by 1 percent to 1.48 percent annually until 2060 (CBPR 2016). This projected population growth would add additional strain to the surface water supplies and already depleted groundwater supplies but through the County Groundwater ordinance which prohibits the unstainable extraction or conveyance may help with reducing the impacts on drought on the regional groundwater supply.

The historical and potential impacts of drought on populations include agricultural sector job loss, secondary economic losses to local businesses and public recreational resources, increased cost to local and state government for large-scale water acquisition and delivery, and water rationing and water wells running dry for individuals and families. As drought is often accompanied by prolonged periods of extreme heat, negative health impacts such as dehydration can also occur, where children and elderly are most susceptible. Air quality often declines in times of drought which can affect those with respiratory ailments.

Critical Facilities
Drought impacts to critical facilities include water shortfalls for facility operations and critical functions, and potential structural destabilization and damage resulting from land subsidence. Refer to the section on Subsidence for more information.

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Economy
Drought impacts to the local or regional economy can be difficult to quantify but can be extensive and long-lasting depending on the circumstances during, and after a severe drought event. If water resources are limited, effects would be more severe for industries that rely on large amounts of water and any prolonged drought would intensify these impacts. Sectors critical to the economy such as commerce, distribution, agriculture, tourism, related environmental resources, municipal and industrial water supply, key city assets, energy generation, and even socioeconomic aspects can be affected due to lack of, or even reduced quality of water resources.

Agriculture in the San Joaquin Valley relies on artificial irrigation using mostly imported water and/or groundwater. Local droughts are expected and accommodated for; however, a prolonged statewide drought could exceed local capabilities to handle reductions of imported surface water supplies and potentially lead to reductions in distribution from local water storage districts.

The costs of drought are difficult to quantify because the impacts affect so many different sectors including wildlife and natural resources, business and industry, tourism and recreation, agriculture, and individual households. Agriculture often suffers the most financial losses from drought and is the major component of the Merced County economy. For example, according to the California Integrated Climate Adaptation and Resiliency Program’s 2020 Report and 2020 Recommendations, the 2014-2017 multi-year drought was estimated to cost over $6.6 billion once it was over and the loss of 5,000 jobs in 2016 (OPR 2020).

Historic, Cultural and Natural Resources
The Merced National Wildlife Refuge encompasses over 10,000 acres of wetlands, native grasslands, vernal pools and riparian areas and is home to various bird species and other wildlife including the largest wintering population of lesser Sandhill cranes and Ross’ geese, and both species are vulnerable to drought. The impacts of drought on vegetation and wildlife can include death from dehydration and spread of invasive species or disease because of stressed conditions, loss of biodiversity, loss of trees in rural and urban landscapes, loss of wetlands, and degradation of habitat.

In general, environmental impacts from drought are more likely at the interface of the human and natural world. The loss of crops or livestock due to drought can have far reaching economic effects on communities, wind and water erosion can alter the visual landscape, and dust can damage property.

Water-based recreational resources are also heavily affected by drought conditions. Indirect impacts from drought arise from increased wildfire risk and greater occurrence of fire.

Future Development
With the County’s population projected to continue to grow while climate change projections are showing an increased duration an intensity of drought events for the San Joaquin Valley, it will be important for each new development application to be reviewed with existing and future water supplies in mind.

Because future development encompasses all forms of property, buildings, infrastructure, critical facilities and all related populations and their functions, drought impacts to future development align with the historical and potential impacts to populations, property, natural environment, and critical facilities discussed (above).

Risk Summary
● Due to the widespread impacts in San Joaquin Valley, it can have, drought is considered a High significance hazard.
● There have been five multi-year droughts in the past 91 years. Most recent drought lasted from 2012 to 2017 and resulted in a declared State of Emergency.

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● 15 USDA Disaster Designations due to drought have been made in the last 8 years. ● 195 reports of impacts related to drought were made within Merced County between, 2000 and 2020. ● Between 2007-2014 a total of $885,477 crop indemnity claims was paid due to crop losses for a total of 14,660 acres due to drought impacts.
● Climate change projections show that extreme prolonged drought is likely to continue and will exacerbate existing water supply challenges.
● Related Hazards: Extreme Heat, Wildfire, Subsidence, Agricultural Pest Infestation and Disease Table 4-24 Hazard Risk Summary – Drought
Jurisdiction Geographic Area
Probability of
Future
Occurrence
Magnitude/
Severity
Overall
Significance
Merced County Extensive Likely Critical High
City of Atwater Extensive Likely Limited Medium
City of Dos Palos Extensive Likely Limited Medium
City of Gustine Extensive Likely Limited Medium
City of Livingston Extensive Likely Limited Medium
City of Los Banos Extensive Likely Limited Medium
City of Merced Extensive Likely Negligible Low

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4.2.3 Earthquake
Hazard/Problem Definition
An earthquake is caused by a sudden slip on a fault. Stresses in the earth’s outer layer push the sides of the fault together. Stress builds up and the rocks slip suddenly, releasing energy in waves that travel through the earth’s crust and cause the shaking that is felt during an earthquake. 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. The magnitude of earthquakes is usually measured using the Richter scale; a logarithmic scale calculated from the amplitude of the largest seismic wave recorded for the 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. Seismic shaking is typically the greatest cause of damage to structures during earthquakes. Seismologists have developed the Mercalli scale to quantify the shaking intensity of an earthquake’s effects, which is measured by how an earthquake is felt by humans and the damage to buildings.

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 lines. Other damage-causing effects of earthquakes are surface rupture, fissuring, settlement, and permanent horizontal and vertical shifting of the ground. Secondary impacts can include landslides, seiches, liquefaction, and dam failure.

Liquefaction occurs when ground shaking causes the mechanical properties of some fine grained, saturated soils to liquefy and act as a fluid (liquefaction). It is the result of a sudden loss of soil strength due to a rapid increase in soil pore water pressures caused by ground shaking, in areas of shallow groundwater (within 10’ of surface or less). Liquefaction that produces surface effects generally occurs in the upper 40 to 50 feet of the soil column, although the phenomenon can occur deeper than 100 feet.

The duration of ground shaking is also an important factor in causing liquefaction to occur. The larger the earthquake magnitude, and the longer the duration of strong ground shaking, the greater the potential there is for liquefaction to occur.

In populated areas, the greatest potential for loss of life and property damage can come as a result of ground shaking from a nearby earthquake. The degree of damage depends on many interrelated factors.

Among these are the moment magnitude, focal depth, distance from the causative fault, duration of shaking, type of surface deposits or bedrock, presence of high ground water, topography, and finally, the design, type, and quality of building construction.

Geographic Area
The nearest faults of major significance are the San Andreas to the west of Merced County, a distance of approximately 15 miles from the county line; the Hayward and Calaveras faults to the northwest; the White Wolf, Garlock, and Sierra Nevada faults to the south; and the Bear Mountain Fault Zone about 5 miles east of and parallel to the eastern border of Merced County. These faults have been and will continue to be the principal source of seismic activity affecting the County of Merced.

The only fault known inside the County is the "Ortigalita", also known as the "Telsa-Ortigalita Fault", located in the western quarter of the County, dissecting the Coast Range in a northwesterly direction. This fault has not been active in historic times, however, there is no guarantee that it will never become active again.

There have been no records of major seismic activity originating in the county, with most epicenters in the county being below a magnitude 4.0. However, the county has been shaken by earthquakes originating elsewhere. There is documented evidence of six earthquakes that shook the area, those of 1872, 1906,

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1952, 1966, 1984, and 1989. Major damage occurred in Los Banos in 1906, with minor damage recorded throughout the county from other occurrences.

The San Andreas Fault occurs where the North American and Pacific plates come together and grind in a side-by-side motion relative to each other. Another large known fault, the White Wolf fault, is located to the south near Arvin and Bakersfield in Kern County and produced a severe M 7.7 earthquake in 1952.

Figure 4-7 below shows the known faults and potential for ground shaking resulting from earthquakes in and near Merced County, based on USGS probabilistic ground shaking with a 2% in 50-year occurrence (AKA 2500-year probabilistic ground shaking).

Figure 4-7 Merced County Earthquake Ground Shaking Potential and Nearby Faults Earthquakes can occur at any time of the day or night and any time of the year. Earthquakes are particularly dangerous due to their rapid onset, generally without warning. Aftershocks can occur for days, weeks, and even months following a major earthquake. This additional damage to structures already weakened by the main earthquake increases the danger to rescue and recovery personnel.

Extent (Magnitude/Severity)
For extent, the severity of an earthquake, or the amount of energy released during an earthquake is usually expressed in terms of intensity or magnitude as described further below.

Intensity: Intensity represents the observed effects of ground shaking at any specified location and earthquake shaking decreases with distance from the earthquake epicenter. Intensity is an expression of the amount of shaking at any given location on the ground surface based on felt or observed effects.

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Seismic shaking is typically the greatest cause of losses to structures during earthquakes. Intensity is measured with the Modified Mercalli Intensity (MMI) scale. The intensity of ground shaking at a particular site or structure is a function of many factors including: 1) earthquake magnitude, 2) distance from the epicenter, 3) duration of strong ground motion, 4) local geologic conditions (soil type and topography), and 5) the fundamental period of the structure. A brief description of those factors is presented below.

The Modified Mercalli Intensity scale is summarized in Table 4-24, along with the effects associated with the MMI scale. Damage typically occurs in MMI of scale VII or above.

Earthquake Magnitude: Magnitude represents the amount of seismic energy released at the hypocenter of an earthquake. It is based on the amplitude of the earthquake waves recorded. 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 Richter scale is numeric and has a logarithmic relationship between scale factors, so that a difference of one scale number represents a tenfold increase in measured amplitude, which in turn corresponds to an approximate 31x energy release difference when compared to the next whole number value. The Moment Magnitude scale (Mw, or M), which is a measurement of energy released by the movement of a fault and is the modern method used by seismologists to measure earthquakes. Overall, as the amount of energy released by an earthquake increases, the potential for ground shaking impacts also increases.

Distance from Epicenter: Earthquake energy generally dissipates (or attenuates) with distance from a fault. Over long distances, this loss of energy can be significant, resulting in a significant decrease in ground shaking with increased distance from the epicenter.

Duration of Strong Shaking: The duration of the strong ground shaking constitutes a major role in determining the amount of structural damage and the potential for ground failure that can result from an earthquake. Larger magnitude earthquakes have longer durations than smaller earthquakes.

Local Geologic Conditions: The geologic and soil conditions at a particular site have the potential to substantially increase the effects of ground shaking. The thickness, density, and consistency of the soil, as well as shallow ground water levels, have the potential to amplify the effects of ground shaking depending on the characteristics of the earthquake. In general, the presence of unconsolidated soils above the bedrock surface can amplify the ground shaking caused by an earthquake.

Fundamental Periods: Every structure has its own fundamental period or natural vibration. If the vibration of ground shaking coincides with the natural vibration period of a structure, damage to the structure can be greatly increased. The extent of damage suffered during an earthquake can also depend on non-geologic factors. The type of building and its structural integrity will influence the severity of the damage suffered. Generally, small, well-constructed, one- and two-story wood and steel frame buildings have performed well in earthquakes because of their light weight and flexibility. Reinforced concrete structures will also usually perform well. Buildings constructed from non-flexible materials, such as unreinforced brick and concrete, hollow concrete block, clay tile, or adobe, are more vulnerable to earthquake damage.

Effects of Ground Shaking: The primary effect of ground shaking is the damage or destruction of buildings, infrastructure, and possible injury or loss of life. Building damage can range from minor cracking of plaster to total collapse. Disruption of infrastructure facilities can include damage to utilities, pipelines, roads, and bridges. Ruptured gas and water lines can result in fire and produce scour/inundation damage, respectively, to structures, as can fire from other causes, such as electrical damages. Secondary effects can include geologic impacts such as co-seismic fault movement along nearby faults, seismically induced slope instability, liquefaction, lateral spreading, and other forms of ground failure and seismic response. These secondary effects were demonstrated in Oceano by the San Simeon 2003 earthquake.

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Table 4-25 Earthquake Magnitude and Intensity Measurements and Intensity 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
Source: USGS
Past Occurrences
There have not been any damaging earthquakes greater than M 6.0 recorded in Merced County in over 200 years and the County has not been included in any federal disaster declarations involving earthquakes, though several have been very close. The most recent large earthquake near Merced County was 16 miles east north-east of King City at a magnitude of 5.3 on October 20, 2012. Several aftershocks followed the main earthquake, including a 3.1 aftershock. This quake was preceded by two earthquakes located approximately 100 miles from Merced County, the 1982 New Idria earthquake (M 5.4) and the 1983 Coalinga (M 6.5). There was a low level of ground shaking reported.

Major earthquakes have occurred near Merced County and resulted in ground shaking felt in the county.

The Fort Tejon earthquake in 1857 of M 7.9 was one of the greatest earthquakes ever recorded in the United States and the largest in California. It left an extensive surface rupture scar over 215 miles in length along the San Andreas Fault. The epicenter is now thought to have been located near Cholame, approximately 134 miles southwest of the City of Merced. During the Fort Tejon earthquake, strong shaking lasted from one to three minutes. As a result of the shaking, the flow of the Kern River was turned upstream, and water ran four feet deep over its banks. The waters of Tulare Lake were thrown upon its shores, stranding fish miles from the original lakebed. Property loss was heavy at Fort Tejon, one of the only settlements at the time, an Army post in south-central Kern County about four miles from the San

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Andreas Fault. In 1857, two buildings were declared unsafe, three others were damaged extensively but were habitable, and still others sustained moderate damage. One person was killed in the collapse of an adobe house at Gorman.

Figure 4-8 below displays the common areas damaged by earthquakes based on historic evidence dating back to the year 1800. The occurrences are color-coded by damaging shaking intensity across the state of California, and Merced County is enclosed within a black circle. The figure shows that, per the MMI scale noting occurrences equal to or greater than an Intensity of VII, the county has experienced 1 to 3 earthquake events of this kind, mostly affecting the far western and southwestern portions of the County.

Figure 4-8 Areas Damaged by Earthquakes from 1800 to 2017 Source: California State Hazard Mitigation Plan, 2018; California Geologic Survey

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Probability of Future Occurrences
It is estimated that major earthquakes (ranging from a magnitude of 7 to 7.9) occur in California one out of every 10 years. However, strong earthquakes (from magnitudes 6 to 6.9) strike the state about once every two to three years. A strong earthquake can cause major damage depending on the epicenter’s location with regards to populated areas, and can lead to billions of dollars in disasters, deaths, injuries, and disruptions in services and communities’ way of life. Moderate earthquakes (around magnitudes of

5.5) can occur three to four times a year in the state.

Along the San Andreas Fault, segments exist where no large earthquakes have occurred for long intervals of time. These areas accumulate potential energy and provide clues as to where the next earthquake may occur and when. Scientists term these segments “seismic gaps” and, in general, have been successful in forecasting the time when some of the seismic gaps will produce large earthquakes. Geologic studies show that over the past 1,400 to 1,500 years, large earthquakes have occurred at about 150-year intervals on the southern San Andreas Fault. As the last large earthquake on the southern San Andreas was the Fort Tejon earthquake in 1857, that section of the fault is considered a likely location for an earthquake within the next few decades (USGS 1997).

Based on the earthquake shaking potential mapped for Merced County, the proximity to the San Andreas Fault with a history of shaking, but no surface rupture, the probability of damaging seismic ground shaking in Merced County is occasional. The shaking levels expected with a 2% in 50 years probability are depicted in Figure 4-7.

Climate Change Considerations
Climate change is not expected to directly affect earthquake frequency or intensity.

Vulnerability Assessment
Earthquake loss estimation for the 2021 HMP update utilized FEMA’s Hazus-MH 4.2 natural hazard loss estimation software. Hazus is a GIS based, standardized, nationally applicable multi-hazard loss estimation methodology and software. Local, state and federal government officials use Hazus for preparedness, emergency response, and mitigation planning. A level 1 Hazus analysis was performed which estimates damage based on an inventory database compiled at a national level aggregated to Census Tracts. As with any model there are uncertainties, and the results should be considered approximate for planning purposes.

To evaluate potential losses associated with earthquake activity in the planning area, a Hazus 2,500-year probabilistic scenario was run for Merced County. The 2,500-year scenario represents the level of shaking considers multiple faults in the region instead of a single scenario. The methodology utilizes probabilistic seismic hazard contour maps developed by the U.S. Geological Survey (USGS) for the 2018 update of the National Seismic Hazard Maps that are included with HAZUS-MH. The USGS maps provide estimates of potential ground acceleration and spectral acceleration at periods of 0.3 second and 1.0 second, respectively. The 2,500-year return period analyzes ground shaking estimates from the various seismic sources in the area with a 2 percent probability of being exceeded in 50 years. The International Building Code uses this level of ground shaking for building design in seismic areas.

Hazus estimates the number of people displaced, the number of buildings and facilities/infrastructure damaged, the number of casualties, and the damage to transportation systems and utilities. Results produced by Hazus are reported at the census tract level. Figure 4-9 below displays the Census Tracts within the county which were analyzed in this scenario, color-coded by the amount of total losses each tract experienced. The map is followed by the Hazus results broken up in respective sections.

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Figure 4-9 Hazus Earthquake Analysis for Merced County – Total Losses by Census Tract (in Thousands of Dollars)
General Property
Unreinforced Masonry Building (URM)s: Unreinforced masonry building type structures consist of buildings made of unreinforced concrete and brick, hollow concrete blocks, clay tiles, and adobe. Buildings constructed of these materials are heavy and brittle, and typically provide little earthquake resistance. In small earthquakes, unreinforced buildings can crack, and in strong earthquakes, they have a tendency to collapse. These types of structures pose the greatest structural risk to life and safety of all general building types.

Per Hazus, there are an estimated 77,000 buildings in Merced County with a total building replacement value (excluding contents) of $24 Billion. Approximately 94% of these buildings (and 82% of the building value) are associated with residential housing. In terms of building construction types found in the region, wood frame construction makes up 87% of the building inventory. The remaining percentage is distributed between the other general building types.

The categories of damages defined by Hazus are:

Slight damage includes diagonal hairline fractures on most shear wall surfaces and hairline cracks on most infill walls.

Moderate damage includes cracks on most walls and failure of some shear walls.

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Extensive damage means that most shear wall surfaces in the structure have reached or exceeded their capacity exhibited by large, through-the-wall diagonal cracks.

Complete damage means that the structure has collapsed or is in danger of collapse.

The building losses are broken into two categories: direct building losses and business interruption losses.

The direct building losses are the estimated costs to repair or replace the damage caused to the building and its contents. The business interruption losses are the losses associated with inability to operate a business because of the damage sustained during the earthquake. Business interruption losses also include the temporary living expenses for those people displaced from their homes because of the earthquake.

The total building-related losses were $2.4 billion. By far, the largest loss was sustained by the residential occupancies which made up over 61% of the total loss. Figure 4-10 and Figure 4-11 below provide a summary of the losses associated with the building damage.

Figure 4-10 Earthquake Losses by Loss Type and Occupancy Type (in Millions of Dollars) Source: Hazus-MH 4.2

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Figure 4-11 Hazus 2,500 Year Probabilistic Earthquake Scenario Structure Damage by Occupancy Type
Source: Hazus-MH 4.2
Hazus estimates that about 17,106 buildings will be at least moderately damaged. This is over 22% of the total building stock in the county. There are an estimated 1,386 buildings that will be damaged beyond repair. Table 4-25 summarizes the expected damage by property occupancy type in more detail, whereas Table 4-26 contains the results of the expected building damage by building material type.

Table 4-26 Expected Building Damage by Occupancy Class
Source: Hazus-MH 4.2

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Table 4-27 Expected Building Damage by Building Material (All Design Levels) Source: Hazus-MH 4.2
Hazus also estimates the amount of debris that will be generated by the earthquake event analyzed. The model subdivides the debris into two general categories: a) Brick/Wood, and b) Reinforced Concrete/Steel. This distinction is made because of the different types of material handling equipment required to handle the debris.

The model estimates that a total of 442,000 tons of debris will be generated. Of that total amount, Brick/Wood comprises 38% of the debris, while the remainder would be Reinforced Concrete/Steel. If the debris tonnage was converted to estimates of truckloads required to remove it, debris generated would convert to about 17,680 truckloads, with each truckload carrying 25 tons. Figure 4-12 summarizes the debris generation estimate and material type for this earthquake event.

Figure 4-12 Debris Generation in Millions of Tons and by Material Type Source: Hazus-MH 4.2

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People
Shelter Requirement: Hazus estimates the number of households that are expected to be displaced from their homes due to the earthquake and the number of displaced people that will require accommodations in temporary public shelters. The model estimates 918 households to be displaced due to the earthquake.

Of these, approximately 882 people (out of a total population of 255,793) will seek temporary shelter in public shelters.

Casualties: Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake-related injuries result from collapsing walls, flying glass, and falling objects as a result of the ground shaking, or people trying to move more than a few feet during the shaking. Hazus estimates the number of people that will be injured and killed by the earthquake. The casualties are broken down into four severity levels that describe the extent of the injuries. The levels are described as follows:

Severity Level 1: Injuries will require medical attention, but hospitalization is not needed.

Severity Level 2: Injuries will require hospitalization but are not considered life-threatening.

Severity Level 3: Injuries will require hospitalization and can become life-threatening if not promptly treated.

Severity Level 4: Victims are killed by the earthquake.

The casualty estimates are provided for three times of day: 2:00 AM, 2:00 PM and 5:00 PM. These times represent the periods of the day that different sectors of the community are at their peak occupancy loads. The 2:00 AM estimate considers that the residential occupancy load is at its maximum. The 2:00 PM estimate considers that the educational, commercial and industrial sector loads are at their maximum, and has the highest numbers of casualties estimated. The 5:00 PM represents peak commute time. These estimates of casualties are broken down in Table 4-27.

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Table 4-28 Hazus Earthquake Casualty Estimates from Merced County Source: Hazus-MH 4.2
Social Vulnerability
Populations most vulnerable to earthquake and liquefaction activity would be those that rely on specific services or electrical power, which may not be available during or after a quake, or those which are homeless, would have a difficult time evacuating due to age or disability, cannot communicate easily due to speaking English less than well, for example.

Critical Facilities and Infrastructure
Critical Facility Inventory: Hazus breaks critical facilities into two groups: essential facilities and high potential loss facilities. Essential facilities include hospitals, medical clinics, schools, fire stations, police

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stations and emergency operations facilities. High potential loss facilities include dams, levees, military installations, nuclear power plants and hazardous material sites.

Essential Facility Damage: There are four (4) hospitals in the region with a total bed capacity of 246 beds. There are 145 schools, 31 fire stations, 14 police stations and one (1) emergency operation facility.

The inventory also includes 23 hazardous material sites.

On the day of the earthquake, the model estimates that only 125 hospital beds (51%) are available for use by patients already in the hospital and those injured by the earthquake. After one week, 75% of the beds will be back in service. By 30 days, 94% will be operational. The essential facility inventory and expected damages from the earthquake event are provided in Table 4-28.

Transportation Systems Inventory: Within Hazus, the lifeline inventory is divided between transportation and utility lifeline systems. There are seven (7) transportation systems that include highways, railways, light rail, bus, ports, ferry and airports. There are six (6) utility systems that include potable water, wastewater, natural gas, crude & refined oil, electric power and communications. The transportation systems inventory and expected damages from the earthquake, in terms of number of structures and locations affected, are provided in Table 4-29, while losses in millions of dollars are summarized in Table 4-30. The total value of the lifeline inventory is over $9.4 billion. This inventory includes over 274 miles of highways, 532 bridges, and 11,935 miles of pipes.

Utility Lifeline Systems Inventory: The replacement value of the transportation and utility lifeline systems is estimated to be $4.48 billion and $4.97 billion, respectively. The expected utility system facility damages in terms of total structures or systems affected, along with the inventory of this dataset, are summarized in Table 4-31. Economic losses in millions of dollars are found in Table 4-32. Site specific expected utility system pipeline damages (including their inventory) are included in Table 4-33, while the potable water and electric power system performance limitations, damages, and inventory will be in Table 4-34.

Table 4-29 Essential Facility Inventory and Expected Damage Source: Hazus-MH 4.2

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Table 4-30 Transportation Systems Inventory and Expected Damage by Number of Locations Source: Hazus-MH 4.2

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Table 4-31 Transportation System Economic Losses in Millions of Dollars Source: Hazus-MH 4.2

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Table 4-32 Expected Utility System Facility Inventory and Damages Source: Hazus-MH 4.2

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Table 4-33 Utility System Economic Losses in Millions of Dollars Source: Hazus-MH 4.2
Table 4-34 Expected Utility System Pipeline Damage (Site Specific) Source: Hazus-MH 4.2

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Table 4-35 Expected Potable Water and Electric Power System Performance Source: Hazus-MH 4.2
Beyond the modeling estimates of Hazus-MH, there are several other critical facilities which are unique to Merced County and are crucial to the function of the wider region and the state of California. The California Aqueduct, part of the California State Water Project, runs through the western part of Merced County. The State Water Project is a water storage and delivery system of reservoirs, aqueducts, power plants, and pumping plants. Its main purpose is to store water and distribute it to 29 urban and agricultural water suppliers in Northern California, the San Francisco Bay Area, the San Joaquin Valley, the Central Coast, and Southern California. The State Water Project makes deliveries to two-thirds of California's population. An earthquake event, or landslides triggered by one, which damage the aqueduct could disrupt the aqueduct’s ability to deliver water, which would have serious impacts to agriculture in the county and water users in many areas of California. Similarly, Interstate 5 runs through the western portion of the county and serves as a major shipping and transportation corridor for all of California and the west coast of the United States. Any damage or impacts to Interstate 5 in Merced County from an earthquake would result in disruptions to the entire state.

Economy
Hazus estimates the long-term economic impacts to the region. The model quantifies this information in terms of income and employment changes within the region. The total economic loss estimated for the earthquake is $4.6 Billion, which includes building and lifeline related losses based on the region's available inventory. An estimated 14% of losses computed by Hazus were related to the business interruption of the region.

Since the building losses are broken into two categories (of direct building losses compared to business interruption losses), building-related losses, which summarize estimated costs to fix or replace structures and damages to properties and their contents, are discussed in more detail in Table 4-26 of this section.

However, business interruption losses are summarized herein. They included the temporary living expenses for people displaced from their homes because of the earthquake event. These business-related economic losses are included in Table 4-35 below.

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Table 4-36 Building-Related Economic Loss Estimates in Millions of Dollars Source: Hazus-MH 4.2
Historic, Cultural, and Natural Resources
Earthquake effects on the environment, natural resources, and historic and cultural assets could be very destructive depending on the type of seismic activity experienced and secondary/cascading effects from an event (e.g. wildfire). The biggest impact would likely be on older properties such as wooden or masonry buildings, though reinforced masonry structures would be much more resilient during earthquakes.

Future Development
Future development in the county is not anticipated to significantly affect vulnerability to earthquakes when designed according to modern building codes. However future development will result in a slight increase in exposure of the population, building stock, and related infrastructure to earthquakes.

Risk Summary
● Merced County is located in a geologically complex and seismically active region, albeit less so than other areas of California. There are numerous active and potentially active faults in close proximity to the County. The County does not have a history of significant damaging earthquakes. ● The overall significance of earthquakes is Medium but ranked High for communities on the western side of the county including Dos Palos and Gustine and in the more densely populated cities such as Merced.
● A moderate earthquake occurring in or near Merced County could result in deaths, casualties, property damage, agricultural and environmental damage, and disruption of normal government and community services and activities.
● The location of the epicenter as well as the time of day and season of the year would have a profound effect on the number of deaths and casualties, as well as property damage. ● The hazard of earthquakes varies from place to place, dependent upon the regional and local geology.
● Effects on people: Hazus probabilistic scenario modeling of worst case ground shaking results in estimates of 488-1,132 people needing hospitalization and between 10-65 deaths depending on the time of day the earthquake hits.

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● Effects on property: Hazus probabilistic scenario modeling indicates about 17,106 buildings will be at least moderately damaged, with approximately $2.4 billion in losses. ● Effects on economy: The total economic loss estimated for a large earthquake is $4.6 billion, which includes building and lifeline related losses based on the region's available inventory. An estimated 14% of losses computed by Hazus were related to the business interruption of the region. ● Effects on critical facilities and infrastructure: Essential facility damage (police, fire, school, medical) is predicted to be low; only 246 hospital beds (51%) would be available during the earthquake. Utility lifeline systems impacts would be significant particularly to bridges; moderate damage can be expected to water, wastewater, power and communications facilities; loss of water and power would be significant in the days and weeks following the earthquake. ● Cascading and Secondary Effects: Earthquakes can cause many cascading effects such as fires, flooding, hazardous materials spills, utility disruptions, landslides, and transportation emergencies.

Ground shaking may cause tsunamis or seiche, the rhythmic sloshing of water in lakes or bays.

Table 4-37 Hazard Risk Summary - Earthquake
Jurisdiction Geographic Area
Probability of
Future
Occurrence
Magnitude/
Severity
Overall
Significance
Merced County Significant Unlikely Critical Medium
City of Atwater Extensive Occasional Critical Medium
City of Dos Palos Extensive Occasional Critical Medium
City of Gustine Significant Likely Critical Medium
City of Livingston Limited Occasional Limited Medium
City of Los Banos Limited Likely Limited Medium
City of Merced Extensive Occasional Critical Medium

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4.2.4 Flood & Levee Failure
Hazard Description
Floods are among the most frequent and costly natural disasters in terms of human hardship and economic loss. Floods can cause substantial damage to structures, bridges and roadways, 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.

Floodplains are defined as the areas immediately adjacent to a channel from a river, stream, or other waterway. Floodplains are illustrated on inundation maps, which show areas of potential flooding and water depths. In its common usage and based on FEMA guidelines, the floodplain most often refers to the area that is inundated by the 100-year flood, or the flood that has a one percent chance occurrence 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 FEMA NFIP. The 500-year flood is the flood that has a

0.2 percent chance of being equaled or exceeded in any given year. A 500-year flood event would be slightly deeper and cover a greater area than a 100-year flood event. The potential for flooding can change and increase through various land use changes and changes to land surface, which then may 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.

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 manmade. A natural levee is formed when sediment settles on the riverbank, raising the level of the land around the river. To construct a manmade 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 flood events. Levees reduce, not eliminate, the risk to individuals and 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.

Riverine flooding - Riverine flooding, defined as the condition when a watercourse (e.g. river or channel) exceeds its “bank-full” capacity, generally occurs as a result 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 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. Intense storms can overwhelm the local waterways as well as the integrity of any flood control structures. The warning time associated with slow rise floods assists in life and property protection

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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.

Levee Failure – Flooding from the failure of levees throughout the county or upstream is also of concern.

A catastrophic flood control structural failure could easily overwhelm local response capabilities to save lives and require mass evacuations. Impacts to life safety will depend on the warning time and the resources available to notify and evacuate the public. Loss of life could result, and there could be associated health concerns as well as negative effects to local buildings and infrastructure.

The potential for flooding can change and increase through various land use changes and changes to land surface, which result in changes to the floodplain. Environmental changes can create localized flooding problems in and outside of natural floodplains by altering or confining natural drainage channels. These changes are most often created by human activity.

Encroachment into areas subject to inundation by floodwaters having rapid flows aggravates the risk of flood damage and heightens potential flood hazards by further increasing velocities. To reduce the risk of property damage in areas where the stream flows are high, the community may wish to restrict development in areas outside the floodway. FEMA defines a regulatory floodway as the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. The floodway is illustrated in Figure 4-13 below. The area between the floodway and 1-percent-annual-chance floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the water surface elevation of the base flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in schematic in the following.

Figure 4-13 Floodway Schematic
Source: Guidance for Flood Risk Analysis and Mapping – FEMA, 2019

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Geographic Area
The Merced River, in the central part of California, is a 145-mile (233 km)-long tributary of the San Joaquin River flowing from the Sierra Nevada into the Central Valley. It is most well-known for its swift and steep course through the southern part of Yosemite National Park, and the world-famous Yosemite Valley. The river's character changes dramatically once it reaches the foothills and the lowlands, becoming a slowmoving waterway meandering through irrigated fields. Large-scale irrigated agriculture was introduced to the Central Valley in the late 19th century, and led to the construction of numerous state, federal and privately owned dams.

The San Joaquin River swings northwest, passing through many different channels, some natural and some manmade. Northeast of Dos Palos, it is joined by the Fresno and Chowchilla Rivers. Fifty miles downstream, the Merced River (highlighted below in Figure 4-14) empties into the San Joaquin. Canal and flood control development in the late 1800’s and early 1900’s redirected water flow and managed waterways through a series of canals, water storage and agricultural levies. This led to the conversion on thousands of acres of lake basin land into farmable ground.

Figure 4-14 Merced River
Source: Merced County website
The Tenaya, Yosemite, Bridalveil, and Pigeon Creeks join the Merced River before it breaches the glacial moraine at the valley's end. From there the river picks up Cascade Creek and turns south near El Portal, flowing through Merced River Canyon. State Route 140 follows the river out of the west entrance to the national park, a few miles before the South Fork Merced River, the largest tributary, joins from the left. The river arcs northwest to receive the North Fork, and a few miles after it enters Lake McClure, formed by New Exchequer Dam. Below New Exchequer, the river flows west through a heavily irrigated region of the Central Valley, passing through McSwain and Crocker-Huffman Dams and the cities of Hopeton, Delhi and Livingston. It joins the San Joaquin River at Hills Ferry, a few miles south of Turlock. There are also many lakes in the watershed of the Merced River, including Merced Lake, Tenaya Lake, the Chain Lakes, May Lake, Lake McClure, and Lake McSwain. The Merced River is the third largest tributary of the San Joaquin River.

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The primary cause of local flooding is due to the drainage patterns that flow towards the San Joaquin River Basin and Merced County. The numerous tributaries of the San Joaquin – the Fresno, Chowchilla, Merced, Tuolumne, Mariposa Creek, Calaveras, Mokelumne, and others flowed freely across alluvial flood plains to join the river. All of the major tributaries of the river originate in the Sierra Nevada. Most of the streams that start in the Coast Range are intermittent and contribute little to the flow of the San Joaquin.

During the winter, spring, and early summer, storms and snowmelt swell the river. In 1914 – before the development of major dams and irrigation diversions – the California Department of Engineering estimated the river's flow in full flood at 325,000 cubic feet per second (cfs). In late summer and autumn, there is little water left over to replenish stream flow.

The floodplain of the Merced River is well defined from the eastern county boundary to approximately 10 miles above the mouth of the river. Downstream of this point, the floodplain is undifferentiated from the valley floor and major floods can spread out over large areas. Floodplain storage reduces peak flows in the downstream direction. With the diminishing channel capacity of the Merced River, flood hazards increase. During the 1950 flood event, approximately 19,600 acres of land along the Merced River were inundated, including the towns of Snelling and Merced Falls.

The Merced River's primary human use is irrigation. The Merced Irrigation District (MID) operates most of the irrigation infrastructure, which supplies water to 154,394 acres (624.81 km2) of farmland. The Irrigation District and watershed are shown in Figure 4-15. As a whole, the system includes about 4,000 sets of control gates and 793 miles (1,276 km) of canals. Irrigation has taken most of the water out of the lower river, which now rarely reaches the sea. Water that does return to the river does so in for form of irrigation return flows, which carry pesticides, fertilizer and other pollutants. The MID is federally required to allow at least 15,000-acre feet (19,000,000 m3) of water annually to flow continually down the river, not including flooding. The water has allowed the San Joaquin River below the Merced River confluence to contain water, while above the confluence all its water is usually diverted for irrigation.

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Figure 4-15 Merced Irrigation District Watershed System Source: MID
The physical risks associated with potential flooding and the regulatory requirements for floodplain management are important considerations when decisions are being made regarding future land use throughout the County. Those same risks guide the local and community-level emergency response needs. Economic growth and prosperity in Merced County are dependent upon federal, state, and local agency involvement on regional and local flood management systems. Flood protection regulations within California have been increased over the past few years through legislation. This legislation included the requirement for the California DWR and Central Valley Flood Protection Board to prepare and adopt a Central Valley Flood Protection Plan (CVFPP) by 2012. The legislation also established certain flood protection requirements for local land use decision making based on the CVFPP. The law sets a higher standard for flood protection for the entire San Joaquin Valley. The standard was set for an urban level flood protection necessary to withstand a 1 in 200 chance of a flood event occurring in any given year (200-year flood) for areas developed or planned to have a population of at least 10,000. It also requires impacted counties to collaborate with cities to develop flood emergency response plans. Figure 4-16 shows the extent of this 200-year flood event based on the Best Available Maps (BAM) developed by California DWR.

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Figure 4-16 Merced County 200-year Floodplain
Source: USACE, Wood Planning Team

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In 2009, FEMA completed their DFIRM conversion and updated a number of flood zone areas using 2005 levee certification criteria. In 2007, the California DWR completed their Awareness Floodplain Mapping of Merced County to identify all pertinent flood hazard areas that are not mapped under FEMA’s program, which provides an additional resource for identifying special flood hazard areas within the County.

Extent (Magnitude/Severity)
The FEMA and the Federal Insurance Administration have assessed flood hazards for major streams in Merced County. A large portion of Merced County continues to be subject to inundation during flood events, as approximately 380,010 acres have been determined to be in the FEMA floodplain. The extent of the floodplain is shown in Figure 4-17. Both a 100-year and 500-year flood event scenario are critical events in Merced County as the flooding would cover at least 35 to 50 percent of the County. More detailed maps are in the jurisdictional annexes.

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Figure 4-17 Merced County 100-year and 500-year Floodplain

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The largest flood of record on the Merced River was 46,200 cubic feet per second (cfs) and occurred on December 4, 1950, downstream of Old Exchequer Dam (built in Mariposa County in 1926). The New Exchequer Dam, which has more flood storage capacity, was built in 1967. Based on USGS stream data, the largest discharges along the Merced River since the construction of New Exchequer Dam occurred in 1983 followed by 1997.

During the major flood events in 1969, 1997, 1998, and 2006, Bear Creek overflowed at the southwest end of the City of Merced in the vicinity of Thornton Avenue and State Highway 140. Stream gauge data is not available to quantify the magnitude of these events. Historical records also indicate that Bear Creek overflowed its banks upstream from the G Street Bridge. This overflow was worsened by debris restricting flow under the bridge. The largest flood on the San Joaquin River since the completion of Friant Dam in 1943 occurred in 1997. Along the San Joaquin River during the past century, the five largest flood events include, in order of magnitude, those from 1997, 1938, 1983, 1969, and 2006 based on USGS data. The historical San Joaquin River floodplain widens from approximately 3 to 4 miles in the reach south of Merced County to approximately 19 miles in central Merced County. This large expansion of the floodplain is accompanied by a decrease in channel slope. The floodplain then narrows to approximately 2 miles downstream of the Merced River in the northern part of the county.

Previous Occurrences
Between 1992 and 2002, every county in California was declared a federal disaster area at least once for a flooding event. California has a chronic and destructive flood history. Of the 336 federally declared disasters in California between 1950 and 2020, 37 were flood related. This makes flooding second only to fire in the number of federal disaster declarations in the state. Historically, floods have been the most frequent cause of disaster in Merced County.

Significant flooding occurs in Merced County approximately every five years. Merced County has had two flood events that were federally declared disasters, once in 1969 and again in 2017. FEMA’s Flood Insurance Study also listed flooding events in 1937-38, 1950, 1955, 1969, 1983, 1997, 1998, and 2006.

Additionally, NOAA’s National Centers for Environmental Information (NCEI) database lists 54 flood or flash flood events which have occurred in the county between 1950 and 2020.

Table 4-37 below highlights several notable flood events in the county that resulted in significant damages or involved federal disaster declarations.

Table 4-38 Major Floods in Merced County
Date of Event Incident Description
January-February
1969
A series of storms delivered 12-50 inches of rainfall over an 8-day period throughout Central and Southern California. This affected the San Joaquin Valley and resulted in the first federal disaster for flood in Merced County.

March 25, 1998 A series of thunderstorms brought locally heavy rain to the City of Merced area, resulting in rainfall totals for 24 hours ending by the morning of the 25th from 3.5" to 5.9" in the Merced City area. One gauge in the north part of town showed 6.8" in the 48-hour period from the evening of the 23rd to the evening of the 25th. Over 1000 people were evacuated from Merced City and nearby County areas. Over 65 homes and 19 apartments were flooded in and around Merced City as the result of torrential/record-setting rainfall in the previous 18 hours. According to the NCEI database, $9.6 million in property damage and $1.5 million in crop damages occurred during this event.

October 24, 1998 The cool season's first significant rain pushed through Central California. Merced received

0.75” of rain in embedded frontal thundershowers and locally heavy rain in about 2 hours.

Some local street flooding was reported just south of Hilmar and within Delhi. In Merced a

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Date of Event Incident Description
tree was toppled by the storm. Several traffic accidents occurred on rain-slickened roads.

According to NCEI, this event also resulted in $120,000 in property damage and six injuries.

January 10, 2005 Heavy rain resulted in water overflowing from Bear Creek in the Merced area from heavy rainfall damaged a handful of homes on the 11th, and $200,000 in property damages.

March 22, 2005 Over 4 inches of rain fell in a 24-hour period in the Mariposa County area of Central California, upstream of Merced County. Numerous small creeks flooded in Mariposa, Merced, and Madera Counties. Flooding caused damage to structures within the town of Mariposa and several bridges and roads in and around Hornitos, Merced Falls, and Catheys Valley in Merced and Mariposa Counties. $250,000 in property damage was recorded.

April 4, 2006 Due to continued heavy rain and subsequent high stream flows, a break in Black Rascal Creek flooded homes in north Merced. And Bear Creek raised over its banks in West Merced flooding a residential section in that vicinity. Overall, there were approximately 300 homes flooded around Merced with over 500 people evacuated during the event. $9.72 million in property damage.

March 27, 2011 During the frequently stormy period that began on the 18th and ended on the 28th, as much as 7 inches of rain fell in the San Joaquin Valley and up to 10 inches of rain drenched the adjacent foothills while the higher elevations of the Sierra (above 7000 feet) received snow accumulations of up to 15 feet. Excessive runoff combined with an increase in reservoir releases at the major dams caused higher than normal flows along rivers and streams through the end of the month. The Merced River at Stevinson peaked a half of a foot below flood stage at 4:30 pm on the 21st but otherwise remained well above monitor stage during the last two weeks of the month. Water levels along the San Joaquin River approached levels that had not been observed since January 1997. In Merced County, several water swollen creeks briefly flowed out of their banks on the morning of the 20th and caused minor flooding. The event caused $500,000 in property damage.

November 30, 2012 California highway patrol reported a multi-vehicle accident in heavy rain on Highway 99 at west side boulevard. Involved three cars and a big rig. Number of injuries unknown at this time. $120,000 in damages were also recorded.

February 1-23,
2017
On March 19, 2017, Governor Edmund G. Brown Jr. requested a major disaster declaration due to severe winter storms, flooding, and mudslides during the period of February 1-23, 2017. The Governor requested a declaration for public assistance for 42 counties and Hazard Mitigation statewide. Merced County was included in the declaration.

Source: NCEI Storm Events Database, FEMA

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Figure 4-18 Image of Past Flooding in Merced County
Source: Fox 26 News, Images of February 2017 flooding
Probability of Future Occurrences
Due to the history of past flooding events and the natural drainage pattern of the planning area, flooding in Merced County is likely to continue to occur. The potential for failure of one of the many levees throughout the county could create more risk for flooding. The 100-year flood is the flood that has a one percent chance in any given year of being equaled or exceeded. Based on past events, flooding events less severe than a 100-year flood and those outside of the 100-year floodplain occur frequently during periods of heavy rains. According to the NCEI Storm Events Database, there have been 54 flood events recorded for Merced County between 1990 and 2020. Utilizing the methodology explained in subsection

4.1.1, this means there is a 180% chance of a flood event occurring in a given year. Significant flooding occurs in Merced County approximately every five years.

Climate Change Considerations
California’s Fourth Climate Assessment found that costs associated with direct climate change impacts by 2050 will be dominated by human mortality, coastal damage, and the potential for droughts and megafloods (California Natural Resources Agency 2018). Scientific studies outlined in the same assessment also indicated shifts in California’s precipitation regime, which show more dry days, more dry years, a longer dry season, and increases in occasional heavy precipitation events and floods. Studies also project greater storm intensity with climate change, resulting in more direct runoff and flooding (California Natural Resources Agency 2018). As a result, high frequency flood events in conjunction with heavy precipitation events and extreme storm events will increase with climate change. Certain climate studies noted in the Fourth Climate Assessment also forecast that during periods with heavy rain and frequent storm events there is an increase in flood events, as well as landslide and debris flow (California Natural Resources Agency 2018). For example, during the 2016-2017 winter, the storms resulted in many secondary hazards, including numerous landslides and in some watersheds an increased sediment load. Also, with wildfires already being a problem in California, increasing periods of drought and lack of precipitation are expected

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to exacerbate conditions for fires to occur, and in turn worsen the potential for runoff and flooding associated with burned areas.

The Fourth Climate Assessment also includes nine reports for the nine regions in California. According to the preview for the San Joaquin Valley Region Summary Report, which has not yet been published at the time of this plan update, the frequency of catastrophic floods will increase in the coming years. This in turn will lead to increased stresses to agriculture, natural ecosystems, water resources, land use and community development, transportation, energy, public health, and climate justice.

Vulnerability Assessment
While there are some benefits associated with flooding, such as the replenishment of sediments and nutrients to agricultural lands, it is considered a hazard to development in floodplains. Floods can cause many cascading effects. Fire can break out as a result of dysfunctional electrical equipment. Hazardous materials can also get into floodways, causing health concerns and polluted water supplies. In many instances during a flood, the drinking water supply will be contaminated. During the 2021 update the following vulnerability analysis using GIS was performed to quantify flood risk.

General Property
Historically, Merced County has been at risk to flooding primarily during the winter and spring months when river systems in the county swell with heavier rainfall and runoff from winter snowmelt. Normally, storm floodwaters are kept within defined limits by a variety of storm drainage and flood control measures. But occasionally, extended heavy rains result in floodwaters that exceed normal high-water boundaries and cause damage. Flooding has occurred in the past within the 100-year floodplain and in other localized areas.

A flood vulnerability assessment was performed for Merced County using the following GIS methodology.

The County’s parcel layer and associated assessor’s building improvement valuation data were provided by the County and were used as the basis for the inventory. Merced County’s effective DFIRM was used as the hazard layer. A DFIRM is FEMA’s flood risk data that depicts the 1% annual chance (100-year) and the

0.2% annual chance (500-year) flood events; this data is incorporated into the National Flood Hazard Layer (NFHL). Merced County’s effective FEMA DFIRM, dated December 2, 2009, was determined to be the best available floodplain data. Figure 4-17 summarizes the flood zones included on these maps.

GIS was used to intersect the parcel boundaries with a master address point layer to obtain the number of buildings per parcel. Only parcels with improvement values greater than zero were used in the analysis, this method assumes that improved parcels have a structure of some type. The DFIRM flood zones were overlaid in GIS on the address points to identify structures that would likely be inundated during a 1% annual chance and 0.2% annual chance flood event. This overlay can be seen graphically in the regional maps in Figure 4-17, and in more detail in the jurisdictional annexes.

Building improvement values and counts for those points were then extracted from the parcel/assessor’s data and summed for the unincorporated county and jurisdictions. Results of the overlay analysis area shown in Table 4-38 for the 1% annual chance flood and Table 4-39 for 0.2% annual chance flood. The jurisdictional annexes provide more detailed information based on property type. Property type refers to the land use of the parcel and includes agricultural, commercial, exempt, industrial, mixed use, residential, and vacant. A loss estimate analysis was also performed based on depth damage functions developed by the Army Corp of Engineers and FEMA. The loss curves depict the expected flood losses associated with the depth of flooding at a structure. Contents values were estimated as a percentage of building value based on their occupancy type, using FEMA/HAZUS estimated content replacement values. This includes 100% of the structure value for agricultural, commercial, exempt, and open space structures, 50% for

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multi-residential and residential structures and 150% for industrial structures. Building and contents values were totaled to obtain total exposure.

There are different depth damage curves for structure and content losses. For the purposes of this planning level analysis, an average flood depth of 2 feet is assumed. A depth damage ratio of 25% was used for structural loss, based on the FEMA damage curves, assuming a 2-foot-deep flood. A loss ratio was also calculated to express the estimated losses in relation to the total value of all property in the jurisdiction, including property values not exposed to the floodplain boundaries. The results are shown in the loss estimate columns in Table 4-38 for the 1% annual chance flood.

The result is an inventory of the number and types of improved parcels subject to flooding. Results are presented by unincorporated county and incorporated jurisdictions. Detailed tables show counts of parcels by jurisdictions and land use type (agricultural, commercial, exempt, industrial, multi-residential, open space and residential) within each flood zone. It is important to note that there could be more than one structure or building on an improved parcel (i.e., a condo complex occupies one parcel but might have several structures). This flood loss analysis does not account for business disruption, emergency services, environmental damages, or displacement costs, thus actual losses could exceed the estimate shown. Conversely, this analysis does not differentiate parcels that may have been developed since when the county and cities adopted floodplain regulations, which would be mitigated to the 1% annual chance flood if developed in accordance with local floodplain regulations.

Table 4-39 1% Annual Chance Floodplain Exposure and Loss by Jurisdiction Jurisdiction Property
Type
Improved
Parcel
Count
Building
Count
Improved
Value
Estimated
Content Value
Total Value Estimated Loss
Atwater Commercial 4 8 $446,109 $446,109 $892,218 $223,055 Exempt 7 7 $0 $0 $0 $0
Industrial 1 1 $16,651 $24,977 $41,628 $10,407
Residential 342 344 $87,919,330 $43,959,665 $131,878,995 $32,969,749 Total 354 360 $88,382,090 $44,430,751 $132,812,841 $33,203,210 Livingston Agricultural 1 1 $7,441 $7,441 $14,882 $3,721 Total 1 1 $7,441 $7,441 $14,882 $3,721
Merced Agricultural 17 19 $704,235 $704,235 $1,408,470 $352,118 Commercial 527 1,873 $339,551,353 $339,551,353 $679,102,706 $169,775,677 Exempt 433 960 $9,185,588 $9,185,588 $18,371,176 $4,592,794 Industrial 118 218 $167,406,079 $251,109,119 $418,515,198 $104,628,799 Mixed Use 9 9 $185,869 $185,869 $371,738 $92,935
Residential 9,161 12,140 $1,218,507,813 $609,253,907 $1,827,761,720 $456,940,430 Vacant
Land
30 38 $1,030,699 $1,030,699 $2,061,398 $515,350
Total 10,295 15,257 $1,736,571,636 $1,211,020,769 $2,947,592,405 $736,898,101 Unincorporated Agricultural 2,240 2,920 $571,674,871 $571,674,871 $1,143,349,742 $285,837,436 Commercial 182 516 $45,633,503 $45,633,503 $91,267,006 $22,816,752 Exempt 84 115 $9,565,302 $9,565,302 $19,130,604 $4,782,651 Industrial 57 82 $63,423,427 $95,135,141 $158,558,568 $39,639,642 Mixed Use 15 17 $233,502 $233,502 $467,004 $116,751
Residential 2,697 2,967 $319,577,554 $159,788,777 $479,366,331 $119,841,583

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Jurisdiction Property
Type
Improved
Parcel
Count
Building
Count
Improved
Value
Estimated
Content Value
Total Value Estimated Loss
Vacant
Land
25 26 $131,577 $131,577 $263,154 $65,789
Total 5,300 6,643 $1,010,239,736 $882,162,673 $1,892,402,409 $473,100,602 Grand
Total
15,950 22,261 $2,835,200,903 $2,137,621,633 $4,972,822,536 $1,243,205,634 Source: Merced County Assessor’s Office; NFHL Effective date 12/02/2008, FEMA; GIS analysis Large areas of Merced County are at risk of being inundated by a 100-year flood event. The City of Merced, City of Atwater, and unincorporated areas of the County are predominantly inundated by the 100-year floodplain and have the greatest percentages of total loss from a 100-year flood event. While other jurisdictions are far less at risk during in a 100-year flood event, several jurisdictions including Dos Palos and Gustine are at a greater risk of inundation in the event of a 200-year flood.

Based on this analysis, the Merced County planning area has 15,950 parcels and 22,261 buildings valued over $2.8 billion in the 100-year floodplain. An additional 2,904 parcels and 3,866 buildings valued at roughly $596 million fall within the 500-year floodplain. As a result, total structural exposure is approximately $4.4 billion. When factoring the content values within these areas in addition to the structures the total combined value of exposure is $6.1 billion. Development in the 500-year floodplain is typically not regulated, thus a large flood event could be extremely damaging in the County and Merced.

This information is summarized in Table 4-39 below.

Table 4-40 0.2% Annual Chance Floodplain Exposure and Loss by Jurisdiction Jurisdiction Property
Type
Improved
Parcel
Count
Building
Count
Improved
Value
Estimated
Content
Value
Total Value Estimated
Loss
Merced Commercial 30 31 $62,378,180 $62,378,180 $124,756,360 $31,189,090 Exempt 33 69 $0 $0 $0 $0
Mixed Use 2 3 $41,361 $41,361 $82,722 $20,681
Residential 1,594 2,412 $337,480,454 $337,480,454 $674,960,908 $168,740,227 Total 1,659 2,515 $399,899,995 $399,899,995 $799,799,990 $199,949,998 Unincorporated Agricultural 204 262 $39,295,471 $39,295,471 $78,590,942 $19,647,736 Commercial 6 14 $9,074,287 $9,074,287 $18,148,574 $4,537,144 Exempt 6 6 $3,145,199 $3,145,199 $6,290,398 $1,572,600
Mixed Use 4 4 $148,839 $148,839 $297,678 $74,420
Residential 1,022 1,062 $144,732,798 $144,732,798 $289,465,596 $72,366,399 Vacant
Land
3 3 $6,699 $6,699 $13,398 $3,350
Total 1,245 1,351 $196,403,293 $196,403,293 $392,806,586 $98,201,647 Grand
Total
2,904 3,866 $596,303,288 $596,303,288 $1,192,606,576 $298,151,644 Source: Merced County Assessor’s Office; NFHL Effective date 12/02/2008, FEMA; GIS analysis Another method of assessing flood vulnerability is through the utilization of the California DWR BAM which display a 200-year floodplain. The BAM does not replace existing FEMA regulatory floodplains, but rather identifies potential flood risks that may warrant further studies or analysis. Analyzing this floodplain data in the same way as described above revealed an estimated additional 2,159 buildings exposed to flood hazard throughout the unincorporated portions of Merced County.

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Insurance Coverage, Claims Paid, and Repetitive Losses
Unincorporated Merced County joined the NFIP in 1979. All of the jurisdictions in the county, with the exception of Gustine, are NFIP participants. The County currently does not participate in the optional CRS, nor do any of the jurisdictions.

In the unincorporated county, there are 1,558 policies in force, of which there are 1,285 single family units, 4 2-4 family, three all other residential, and 266 nonresidential. The number of policies in force by jurisdiction and flood zone are shown in Table 4-40 below. The City of Gustine is not included as it is not a NFIP participant.

Table 4-41 Merced County Community Information System Policies in Force by Flood Zone and Jurisdiction
Flood Zone Merced
County
City of
Merced
City of
Los
Banos
City of
Livingston
City of Dos
Palos
City of
Atwater
A01-30 & AE
Zones
33 275 0 0 0 0
A Zones 411 51 0 0 0 0
AO Zones 240 573 0 0 0 0
AH Zones 80 114 0 0 0 0
AR Zones 0 0 0 0 0 0
A99 Zones 0 0 0 0 0 0
V01-30 & VE
Zones
0 0 0 0 0 0
V Zones 0 0 0 0 0 0
D Zones 0 0 0 0 0 0
B, C & X Zone
Standard 51 59 0 3 0 1
Preferred 62 119 16 1 3 13
Total 877 1,191 16 4 3 14
Source: FEMA NFIP Community Information System
NFIP data indicates that there are 4,987 insurance policies in Merced County representing $1,084,286,000 of insurance coverage in force. Since 1979 there have been 281 paid losses, totaling $4,484,055. Most of the losses have been in the City of Merced and the unincorporated county. Table 4-41 provides more details on flood insurance policies for each individual jurisdiction.

FEMA insures properties against flooding losses through the NFIP. As part of the process to reduce or eliminate repetitive flooding to structures across the United States, FEMA has developed an official Repetitive Loss Strategy. The purpose behind the national strategy is to identify, catalog, and propose mitigation measure to reduce flood losses to the relatively few numbers of structures that absorb the majority of the premium dollars from the national flood insurance fund.

A repetitive loss property is defined by FEMA as “a property for which two or more NFIP losses of at least $1,000 each have been paid within any 10-year period since 1978”. A repetitive loss property may or may not be currently insured by the NFIP. There are 13 repetitive loss buildings in the unincorporated county, 3 of which are insured and a total of $367,067 was paid out. There are no Severe Repetitive Loss properties, as defined by FEMA, anywhere in the County.

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Table 4-42 Merced County Flood Insurance Policy Information Jurisdiction Policies Insurance in Force No. of Paid Losses Total Losses Paid Atwater 14 $4,018,000 1 $1,740
Dos Palos 3 $553,000 0 $0
Gustine N/A N/A N/A N/A
Livingston 4 $665,000 0 $0
Los Banos 16 $5,180,000 0 $0
Merced 3,401 $772,521,900 151 $2,230,265
Unincorporated 1,558 $301,348,300 129 $2,252,050
Total 4,996 $1,084,286,000 281 $4,484,055
Source: FEMA NFIP Community Information System
People
The total number of residential properties in each floodplain was multiplied by the average household size of 3.32 persons for the County (ACS 2019 estimates) to estimate resident population within mapped flood hazard areas. Based on this analysis, which accounts for residents only and not workers, there are 49,878 residents living in the 100-year flood zone throughout the County. Of all study areas, the City of Merced has the most residents living in the 1% annual chance flood area, followed by the unincorporated county. Table 4-42 below details population estimates by jurisdiction, followed by similar tables for the 500-year floodplain.

Table 4-43 Population Living in the 1% Annual Chance Flood Hazard Zone Jurisdiction Population
Atwater 1,094
Merced 38,877
Unincorporated County 9,907
Total 49,878
Source: Wood GIS analysis on Merced County Assessor’s Office data and FEMA NFHL, ACS Census Estimates The same analysis was conducted for the 500-year floodplain, indicating that there are 11,267 residents living in the 500-year flood zone throughout Merced County. The majority of people living in this floodplain are residents of the City of Merced, with almost 8,000 people in the 500-year floodplain. This population distribution is shown in the table below.

Table 4-44 Population Living in the 0.2% Annual Chance Flood Hazard Zone Jurisdiction Population
Merced 7,728
Unincorporated County 3,539
Total 11,267
Source: Wood GIS analysis on Merced County Assessor’s Office data and FEMA NFHL, ACS Census Estimates Critical Facilities and Infrastructure
Key support facilities and structures most necessary to withstand the impacts of, and respond to, natural disasters are referred to as critical facilities. Examples of these critical facility types include utilities, transportation infrastructure, and emergency response and services facilities, given failures of components along major lifelines or even closures or inaccessibility to key emergency facilities could limit if not

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completely cut off transmission of commodities, essential services, and other potentially catastrophic repercussions. Floods and levee failure have the ability to disrupt, damage, or destroy these critical facilities, which in turn can impede the ability of Merced County to respond to and recover from a major flood event.

A GIS analysis of exposed critical facilities was conducted, similar to the parcel analysis, using HIFLD. The results of critical facilities throughout the county which are exposed to the various flood hazards are shown in Table 4-444 and Table 4-45 below, and organized by the jurisdiction they are located in and the FEMA Lifeline category into which they are classified.

Table 4-45 Critical Facilities Within the 1% Annual Chance Flood Hazard by FEMA Lifeline and Jurisdiction
Jurisdiction
CommunicationsEnergyFood, Water, ShelterHazardous MaterialHealth and MedicalSafety and SecurityTransportationTotal Atwater 2 2 1 - - 1 4 10
Dos Palos - - - - - - - 0
Gustine - - - - - - - 0
Livingston - - - - - - - 0
Los Banos - - - - - - - 0
Merced 26 3 30 15 6 51 25 156
Unincorporated 13 5 13 11 - 34 180 256
Total 41 10 44 26 6 86 209 422
Source: HIFLD, FEMA NFHL
Table 4-46 Critical Facilities Within the 0.2% Annual Chance Flood Hazard by FEMA Lifeline and Jurisdiction
Jurisdiction
CommunicationsEnergyFood, Water, ShelterHazardous MaterialHealth and MedicalSafety and SecurityTransportationTotal Atwater - - - - - - - 0
Dos Palos - - - - - - - 0
Gustine - - - - - - - 0
Livingston - - - - - - - 0
Los Banos - - - - - - - 0
Merced - - 2 - 2 5 - 9
Unincorporated 1 - - - - 5 1 7
Total 1 0 2 0 2 10 1 16
Source: HIFLD, FEMA NFHL

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Economy
Flooding can have a major economic impact on the economy. Based on the flood loss analysis, there are 2,397 commercial structures worth an estimated $771 million in total value directly at risk to flooding in the 1% annual chance zone. Based on the loss analysis this could result in approximately $193 million in direct losses. This does not account for other indirect losses such as business interruption, lost wages and other downtime costs.

Effects on the agriculture economy can be devastating, and a large amount of area at risk to flooding in the County is agricultural. Flooding can damage crops and livestock. In addition to the obvious impacts on crops and animals, flooding can have deleterious effects on soil and the ability to reinvigorate the agricultural activities impacted once the flood waters recede. Damage to water resources such as underground irrigation systems, water storage reservoirs, springs and other natural water bodies could have a serious effect upon agriculture operations.

Historic, Cultural, and Natural Resources
There are 15 properties throughout the County on the NRHP. Most of these places are located in the City of Merced, which has the highest risk and exposure to flood hazards.

Natural areas within the floodplain often benefit from periodic flooding as a naturally recurring phenomenon. These natural areas often reduce flood impacts by allowing absorption and infiltration of floodwaters. Natural resources are generally resistant to flooding except where natural landscapes and soil compositions have been altered for human development or after periods of previous disasters such as drought and fire. Wetlands, for example, exist because of natural flooding incidents. A large percentage of flood prone area in the County are wetlands that are part of the San Luis and Merced National Wildlife Refuges. These areas provide natural and beneficial functions to hold and absorb floodwaters. Areas recently suffering from wildfire damage may erode because of flooding, which can temporarily alter an ecological system.

Future Development
Flooding and floodplain management are significant issues for Merced County. The potential or likelihood of a flood event in the county increases with the annual onset of heavy rains in winter and spring months.

Much of the historical growth in the problem areas connected with flooding and stormwater runoff include erosion, sedimentation, degradation of water quality, losses of environmental resources, and certain health hazards. For NFIP participating communities, floodplain management practices implemented through local floodplain management ordinances should mitigate the flood risk to new development in the 100-year floodplains. As noted previously, a large amount of development has occurred in the 500-year floodplain and these areas are not regulated or require flood mitigation.

The development trend in the Merced County planning area is steady growth. Much of this growth is occurring in the urban areas, which can increase stormwater runoff. The 2020 Caltrans Economic Forecast at the county-level for all 58 counties in California for 2018-2050, projects that Merced County’s population will continue to increase by 1.3 percent through 2025. Such growth may consume previously undeveloped acres, and the increase in impervious surfaces could affect existing drainage and flood control facilities.

Changes in municipal boundaries such as annexations into the SOI may change the flood risk profile for certain communities. A GIS analysis of 1% annual chance flood exposure within SOI boundaries is summarized in the tables below.

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Table 4-47 Sphere of Influence Risk to FEMA 1% Annual Chance Flood Hazard Sphere of
Influence
Improved
Parcel
Count
Building
Count
Improved
Value
Estimated
Content
Value
Total Value Estimated
Loss
Population Loss
Ratio
Atwater 72 80 $9,559,223 $6,160,259 $15,719,482 $3,929,871 169 1.4% Livingston 1 1 $103,862 $103,862 $207,724 $51,931 0 0.2% Merced 908 1,121 $154,013,086 $111,545,194 $265,558,280 $66,389,570 2,673 7.5% Total 981 1,202 $163,676,171 $117,809,315 $281,485,486 $70,371,372 2,842 Table 4-48 Sphere of Influence Risk to FEMA 0.2% Annual Chance Flood Hazard Sphere
of
Influence
Improved
Parcel
Count
Building
Count
Improved
Value
Estimated
Content
Value
Total Value Estimated
Loss
Population Loss
Ratio
Atwater 1 1 $81,844 $40,922 $122,766 $30,692 3 0.01%
Merced 80 86 $29,663,971 $17,321,531 $46,985,502 $11,746,375 249 1.3% Total 81 87 $29,745,815 $17,362,453 $47,108,268 $11,777,067 252 Risk Summary
The overall significance of the flood hazard is High. The 100-year floodplain in Merced County is vast, and many thousands of residents and millions in property value are within the floodplain. ● Countywide there are 22,261 structures at risk worth $4.9 billion, with a loss estimate of $1.2 billion. ● The City of Merced accounts for 59% of the total losses in the 100-year floodplain. 48% of the City of Merced’s buildings are in the floodplain.
● Commercial structures account for 15.5% of total losses in the 100-year floodplain, with a loss estimate of $193M
● Countywide approximately 49,878 persons live in the 100-year floodplain, of which the vast majority (38,877) are in the City of Merced.
● There are 11,267 persons within the 500-year floodplain and a flood of this magnitude would have severe consequences.
● Levees and flood control dam infrastructure provide some protection, but also pose potential levee and dam failure risks.
● A total of 438 critical facilities are found in 1% annual chance (422 facilities) and 0.2% annual chance (16 facilities) flood zones in the county. Most of them are in the City of Merced or in the unincorporated areas of the county.
● Related hazards: Severe weather: Heavy Rain, Wildfire, Landslide and Debris Flow.

Table 4-49 Hazard Risk Summary – Flood & Levee Failure
Jurisdiction Geographic
Extent
Probability of
Future
Occurrence
Magnitude/
Severity
Overall
Significance
Merced County Extensive Likely Catastrophic High
City of Atwater Extensive Likely Critical Medium
City of Dos Palos Limited Occasional Limited Low
City of Gustine Significant Occasional Critical Medium
City of Livingston Limited Occasional Negligible Medium