Agenda packet — West Sacramento City Council, April 9, 2025 (part 2 of 4)

Coordination and Review
The updated Yolo County Multi-Jurisdictional Local Hazard Mitigation Plan has been coordinated and reviewed by the City’s Office of Emergency Services, the Yolo County Office of Emergency Services, the California Office of Emergency Services, and the Federal Emergency Management Agency.

Budget/Cost Impact
Adoption of the Yolo County Multi-Jurisdictional Local Hazard Mitigation Plan does not have an immediate fiscal impact but positions the City to receive federal and state funding for hazard mitigation projects. Implementation of specific mitigation actions may require future budget allocations, grant applications, or cost-sharing agreements.

ATTACHMENT(S)

1. Resolution 25-20

2. Yolo County Multi-Jurisdictional Local Hazard Mitigation Plan

3. Annex D: City of West Sacramento
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RESOLUTION 25-20

A RESOLUTION OF THE CITY COUNCIL

OF THE CITY OF WEST SACRAMENTO

ADOPTING THE YOLO COUNTY

MULTI-JURISDICTION LOCAL HAZARD MITIGATION PLAN UPDATE
WHEREAS, the Federal Disaster Mitigation Act of 2000 (DMA 2000) requires all jurisdictions to be covered by a Pre-Disaster All Hazards Mitigation Plan in order to be eligible for Federal Emergency Management Agency pre- and post-disaster mitigation grants and funding; and
WHEREAS, the City of West Sacramento acknowledges that every jurisdiction is vulnerable to natural, hazards, and recognizes the importance of enhancing its ability to withstand hazards as well as the importance of reducing human suffering, property damage, interruption of public services and economic losses caused by those hazards; and WHEREAS, City of West Sacramento staff participated in a collaborative effort, led by the County of Yolo, involving various local and tribal government jurisdictions, public authorities, special districts and selected community-based organizations; and WHEREAS, the Yolo County Multi-Jurisdiction Local Hazard Mitigation Plan update focuses on the potential impacts from natural disasters; and includes an assessment of these hazards and risks, a plan to mitigate those identified potential hazards and risks, and methods of monitoring, evaluating, and updating the plan at least once every five years; and WHEREAS, adoption by the City of West Sacramento demonstrates its commitment to hazard mitigation and achieving the goals outlined in the Yolo County Multi-Jurisdiction Local Hazard Mitigation Plan update; and
WHEREAS, the City of West Sacramento seeking FEMA approval of the hazard mitigation plan desires to comply with the requirements of the Disaster Mitigation Act and to augment its emergency planning efforts by formally adopting the Yolo County Multi-Jurisdiction Local Hazard Mitigation Plan update by reference into the Safety Element of the General Plan in accordance with the requirements of AB 2140; and
NOW, THEREFORE, BE IT RESOLVED the City Council of the City of West Sacramento hereby adopts the Yolo County Multi-Jurisdiction Local Hazard Mitigation Plan update, incorporated herein by reference.

PASSED AND ADOPTED this 9th day of April, 2025 by the following vote:

AYES:

NOES:

ABSENT:

Martha Guerrero, Mayor
ATTEST:

Jennifer Cusmir, City Clerk
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2018 Yolo County Hazard Mitigation Plan
(HMP) April 2017
Yolo County Operational Area
9 This document is a support annex to the
Yolo County Multijurisdictional Hazard
Mitigation Plan
Annex D: City of
West Sacramento
Version 2.5 July 2024
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ACKNOWLEDGEMENTS
The City of West Sacramento would like to thank those Yolo County Operational Area collaborators and partners who participated in the planning and development of this document.

The official Yolo County Local Hazard Mitigation Steering Committee provided the oversight and dedication to this project that was required and without their commitment; this project would not be possible. Additionally, the City of West Sacramento convened their own internal working group to concurrently review and update this annex.

As with any working plan, this document represents planning strategies and guidance as understood as of the date of this plan’s release. This plan identifies natural hazards and risks and identifies the hazard mitigation strategy to reduce vulnerability and make the City of West Sacramento more disaster resistant and sustainable.

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1.1 Planning Process .......................................................................................................................................................... 6

1.1.1 Planning Process Coordination ................................................................................................................... 10

1.2 Community Profile ................................................................................................................................................... 10

1.3 Geography and Climate ........................................................................................................................................... 11

1.4 History ........................................................................................................................................................................... 12

1.5 Economy ........................................................................................................................................................................ 13

1.6 Development Trends................................................................................................................................................ 14

1.7 Population .................................................................................................................................................................... 15 Section 2.0: Risk Assessment, Hazard Profiles and Vulnerability Assessment ............................................ 16

2.1 Hazard Identification ............................................................................................................................................... 16

2.2 Hazard Profiles ........................................................................................................................................................... 18 Climate Change ............................................................................................................................................................. 18

2.2.2 Flood ...................................................................................................................................................................... 20

2.2.3 Levee Failure ...................................................................................................................................................... 26

2.2.4 Severe Weather: Extreme Heat ................................................................................................................... 30

2.2.5 Severe Weather : Extreme Cold and Freeze........................................................................................... 34

2.2.6 Severe Weather: High Winds ....................................................................................................................... 36

2.3 Low Significance Hazards ...................................................................................................................................... 40

2.4 Vulnerability Assessment ...................................................................................................................................... 40

2.4.1 Asset Inventory .................................................................................................................................................. 40 Section 3.0 Mitigation Strategy ........................................................................................................................................ 47

3.1 Capability Assessment .......................................................................................................................................... 47

3.1.1 Regulatory Capability ................................................................................................................................... 47

3.1.2 West Sacramento Administrative/Technical Mitigation Capabilities ........................................ 51

3.1.3 West Sacramento Fiscal Mitigation Capabilities .................................................................................. 53

3.1.4 West Sacramento Mitigation Education, Outreach, and Partnerships ....................................... 54

3.1.5 Other Mitigation Efforts ................................................................................................................................. 55

3.2 Future Development Trends .............................................................................................................................. 55

3.3 Mitigation Goals and Objectives .......................................................................................................................... 59

3.3.1 Planning Process Objectives ........................................................................................................................ 60

3.4 Mitigation Actions ................................................................................................................................................... 61

3.4.1 Progress on Local Mitigation Efforts ........................................................................................................ 68 Section 4.0: Plan Review, Evaluation and Implementation .................................................................................. 69

4.1 Plan Adoption ........................................................................................................................................................... 69

4.2 Plan Monitoring ....................................................................................................................................................... 69

4.3 Plan Evaluation ........................................................................................................................................................ 69

4.4 Plan Update ................................................................................................................................................................ 70 112
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4.5 Continued Public Involvement ............................................................................................................................ 70 Appendix A: City Adoption Documentation ................................................................................................................ 72 Appendix B: Public Participation Documentation ................................................................................................... 73 113
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SECTION 1.0: INTRODUCTION
This Annex details the hazard mitigation planning elements specific to the City of West Sacramento (hereinafter referred to as “the City”), a previously participating jurisdiction to the 2018 Yolo County Multi-Jurisdictional Hazard Mitigation Plan. This Annex is not intended to be a standalone document but appends to and supplements the information contained in the Base Plan document.

As such, all sections of the Base Plan, including the planning process and other procedural requirements apply to and were met by the City of West Sacramento. This Annex provides additional information specific to the City of West Sacramento, with a focus on providing additional details on the risk assessment and mitigation strategy for this community.

1.1 PLANNING PROCESS
As described above, the City of West Sacramento followed the planning process detailed in Section

2.0 of the Yolo County LHMP Base plan. The City of West Sacramento formulated their own internal planning team to support the broader planning process as shown in Table 1. Additional details on plan participation and city/county/allied agency representatives are also included in the Base Plan.

Name Position/Title How Participated
Brenna Howell Emergency Services
Coordinator
Plan Development/Review
Bryan Jonson Fire Marshal Plan Development/Review
Blake Johnson RD 900 General Manager Plan Development/Review David Tilley Principal Planner Plan Development/Review
Greg Fabun Flood General Manager Plan Development/Review Paul Dirksen Flood Protection Planner Plan Development/Review Steve Binns Fire Chief Plan Development/Review
Roxanna RecinosSerna Chief Building Official Plan Development/Review Greg Fabun NFIP/CRS Coordinator Plan Development/Review Erin Rivas Flood Plain Manger Plan Development/Review
Robert Santos Utilities Maintenance
Superintendent
Plan Development/Review
Mark Collier Principal Engineer Plan Development/Review Jason Winger Lieutenant Plan Development/Review
Nicole Winger Secretary Social Media/Website/Survey/Public Involvement
Seamus Laffey Senior Planner Plan Development/Review
Jaipal Chahal Planner Plan Development/Review
Jason Puopolo Planner Plan Development/Review
Al Casciato Certified Disaster Council
Member
Citizen At Large
Plan Development/Review
Table 1: City of West Sacramento – Planning Team
The purpose of having the City’s Certified Disaster Council Member and Citizen at Large on the City Planning Team is for that specific representative to provide information regarding the development of the LHMP to the City Council members, citizens, business, stakeholders, community-based organizations that represent underserved populations and vulnerable populations. This 114
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representative is our in the community on a day-to-day basis and can speak to the process and development of the LHMP.

The City internal planning team meetings are documented below:

City of West Sacramento Planning Team Meetings/Discussions on LHMP Annex Meeting Purpose Date
Winter storms AAR Discuss lessons learned from
AAR and LHMP Mitigation
Plan and Projects
02/28/2023
Recovery Scoping for Winter
storms
Recovery Process and LHMP
Process/Review/Participation
05/03/2023
Emergency
Management/Flood Division
Committee Planning Meeting
LHMP Overview, Plan
components, mitigation
strategy
06/13/2023
Final LHMP Draft Review
Emergency
Management/Flood Division
Committee Planning Meeting
LHMP Base Plan from County
and COWS Annex
06/13/2023
Table 2: City of West Sacramento – Planning Team Meetings The City of West Sacramento Annex has been prepared in conjunction with the Yolo County Operational Area Multi-Jurisdictional Hazard Mitigation Plan (HMP) 2023 Update. Coordination with other community partners and establishing an inter-jurisdictional process for the development and implementation of effective hazard mitigation strategies is paramount to successfully mitigating the identified hazards that pose real or potential threats to the City of West Sacramento.

Since the inception of this planning process a major forum for sharing this planning with adjacent jurisdictions is the Mutual Aid Regional Advisory Committee for California Mutual Aid Region IV.

Region IV’s members are contiguous counties to Yolo County and the City of West Sacramento. The value to this collaboration is that these counties share many of the same characteristics as Yolo County such as similar threats, politics, geography and culture. This coordinated process has been made possible by the support of many federal grant programs. Since many of the counties in Region IV have already gone through the hazard mitigation planning process, their experience and advice has proven invaluable to the City of West Sacramento. Each of these meetings includes a local roundtable discussion where the City of West Sacramento is the representative City for all small cities within Mutual Aid Region IV and we are actively engaged and well represented at the quarterly meetings where we have been able to freely and collaboratively share the local hazard mitigation planning process with neighboring communities and jurisdictions. Additionally, the MARAC Region IV is a public meeting and is noticed by Cal OES to many community partners such as local and regional agencies involved in hazard mitigation activities, agencies that have the authority to regulate development, representatives of businesses, academia, and other private organizations and lastly representatives of nonprofit organizations, including community-based organizations, that work directly with and/or provide support to underserved communities and socially vulnerable populations. The City of West Sacramento used these meetings to outreach to business, academia, private organizations, and non-profits. The comments resulting from this effort were incorporated into the plan, as appropriate. The MARAC Region IV Meetings where the Yolo County LHMP were discussed are as follows:
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 Wednesday, April 12, 2023, 0900-1200 Virtual Meeting
 Wednesday, July 12, 2023, 0900-1200 at Cal OES Inland Region HQ, Sacramento, CA  Wednesday, October 11, 2023, 0900-1200 at Memorial Medical Plaza, Modesto, CA Additionally, the regional neighboring jurisdictions specifically invited to comment on the plan were the following:

Sutter County
Zachery Hamill, Emergency Operations Manager
Sacramento County
Mary Jo Flynn, Emergency Operations Coordinator
City of Sacramento
Daniel Bowers, City of Sacramento
Solano County
Tina De Leon, Assistant Emergency Services Manager
Jenny Novelli, Emergency Services Coordinator
Napa County
Brieanna Jones, Emergency Services Officer
Colusa County
Kristopher Cooper, Lieutenant Support Services
Lake County
Leah Sautelet, Emergency Services Manager
Glenn County
Amy Travis, Deputy Director OES
Sonoma County
Jeff DuVall, Director of Emergency Management
Placer County
David Atkinson, Assistant Director of Emergency Services Regional Disaster Medical Health Specialist, Region IV
Brian Cross, RDMHS II
Jared Gunter, RDMHS I
It should be noted that the RDMHS above is an organization that serves underserved communities.

These specialists work together to coordinate disaster medical response and health services across their respective regions.

At the beginning of the planning project, it was decided by Steering Committee that early public outreach in all stages of the plan development would be a high priority. The City of West Sacramento sat on the Steering Committee and provided representation for all the Fire Agencies in 116
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Yolo County and also represented itself and their internal City of West Sacramento Planning Team.

In addition to the solicitation for Planning Team support, there was a Public Survey that was developed and distributed through various means such as posted on the City website, the link to the website is as follows
https://www.cityofwestsacramento.org/government/departments/fire/emergencymanagement/plans-and-publications/2023-hazard-mitigation-plan and posted on City social media, local message boards and handed out to various members of the public at events in within the City. The survey provided an opportunity for the public to share their opinions and participate in the mitigation planning process. The information provided aided in helping the Planning Team better understand the hazard concerns and identified area policies and projects that could potentially help lessen the impact of future hazard events. Proof of the meeting invites via social media for the City of West Sacramento specific populations are noted in the Appendices to this document.

For more information on the role of the Steering Committee see Section 2.2 of the Base Plan.

Public meetings were conducted at various locations and times to allow for underserved communities as well as vulnerable populations to attend and provide feedback and comments. In particular for the 2023 MJHMP Update, there were significant efforts to incorporate input from the aging population, those with access and functional needs, and those who reside in unincorporated areas. We included various locations and times for the public meetings such as in an unincorporated area, senior centers during the daytime, as well as a zoom option for those who may not be able to attend an in-person meeting due to varying factors and circumstances. The City of West Sacramento conducted specific outreach to our own populations not just the County populations via social media for participation in these meetings. Please refer the Appendices of this document to show the social media posts and Yolo County Appendix A for more information.

Public workshops were held by the County in coordination with the cities and other participating jurisdictions. These workshops were held in the evenings, during the week at selected, accessible locations within the County, one of those meetings was held in the City of West Sacramento so that our populations could easily attend making this meeting accessible by underserved communities and vulnerable populations that may not have access to the internet or be able to use an online platform. The overall purpose of these meetings was to inform the public on the purpose and planning process for the local hazard mitigation plan development, present the types of hazards in or possibly affecting the City of West Sacramento, and seek input from the public on priorities for risk reduction. The public meetings held were sparsely attended and the comments received on the plan had nothing to do with the local hazard mitigation plan itself, rather the focus was on response protocols from the public.

There were also two opportunities for participation (virtual) and draft copies of the plan available for the public to review and provide comment. Additionally, the City of West Sacramento has a dedicated web presence to inform the public about the plan revision. The link to the website is as follows https://www.cityofwestsacramento.org/government/departments/fire/emergencymanagement/plans-and-publications/2023-hazard-mitigation-plan and there is a survey located at the bottom of the webpage along with the 2018 LHMP. The opportunities for public participation into the planning process are as follows:
 Monday, June 5th at 5:30 pm 2040 Lake Washington Blvd, West Sacramento  Thursday, June 8th at 6:00 pm Virtual via ZOOM
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 Friday, November 17, 2023, at 9:00 am Virtual via Teams The public meetings were held at various locations and times to allow for underserved communities as well as vulnerable populations to attend and provide feedback and comments. Sign in sheets are posted in the Appendices of this plan and the Yolo County Appendix A. There were significant efforts to incorporate input from the aging population and those with access and functional needs. We included various locations and times for the public meetings such as at senior centers during the daytime, as well as a zoom option for those who may not be able to attend an inperson meeting due to varying factors and circumstances.

The overall process included the discussion of the hazard mitigation planning process into various public meetings such as emergency management meetings, local and regional public health meetings, fire agency meetings, school board meetings and participating jurisdictional meetings and forums.

For more detailed information on the meetings and forums held to inform the public, neighboring jurisdictions and underserved and vulnerable populations please refer to Section 2 Planning Process of the Yolo County Base Plan and their Appendix A.

1.1.1 PLANNING PROCESS COORDINATION
Specifically, the City of West Sacramento incorporated into or implemented the 2018 Yolo County Multi-Jurisdictional HMP through other plans and programs shown in Table 3. More information on the general planning process led by the Yolo County Office of Emergency Services can be found in Section 2.0 Planning Process of the Base Plan and Chapter 6.8 Incorporation Into Other Planning Mechanisms.

City of West Sacramento Plan Implementation/Incorporation Planning Mechanism 2018 HMP was
Incorporated/Implemented In. Details: How was it incorporated? 2035 General Plan Update Safety Element
2022 Community Rating System (CRS) Used for documentation to support CRS reporting
2023 LHMP Annex Update Used original existing data from the 2018 LHMP Annex for the new version of the West
Sacramento Annex
Table 3: 2018 LHMP Incorporation into other Planning Mechanisms At a minimum, the information will need to be incorporated into the City’s Emergency Operations Plan, General Plan, City Land Use and Development Plans, Annual Budgets, and Capital Improvement Plans in addition to what is documented in Table 3. The City Planning Team will continue to provide oversight and accountability to ensure the information is being incorporated into jurisdictional planning mechanisms through the annual progress report surveys and meetings.

1.2 COMMUNITY PROFILE
The community profile for the City of West Sacramento is detailed in the following sections. Figure 1 displays a City of West Sacramento map.
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/
Figure 1: Map of the City of West Sacramento
West Sacramento is a vibrant, innovative and business friendly community located just across the beautiful Sacramento River from California's capital city. The city's redevelopment, growth and increasingly diverse economy are inspired by a community personality and energy all its own. The City maintains a business climate that encourages new business formation and growth. Businesses investing in West Sacramento recognize its many advantages:
 Strategic location within easy reach of West Coast markets and the Pacific Rim  Comprehensive transportation network including the Port of West Sacramento, highway and rail
 Favorable California tax credits in the West Sacramento Enterprise Zone  Vacant land and housing communities
 Proximity to University of California, Davis, the San Francisco Bay area, the Sierra Nevada Mountains, and both Northern and Southern California  Highly skilled, regional labor force
 Higher education and K-12 education system
 Riverfront recreation and regional entertainment destinations

1.3 GEOGRAPHY AND CLIMATE
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The City of West Sacramento is located in eastern Yolo County between the Sacramento River to the east and the Yolo Bypass to the west. The City lies immediately across the Sacramento river from the City of Sacramento and is approximately 85 miles east of San Francisco. Interstate 80 runs through the north western portion of the city; Highway 50 bisects the city, running east-west through the center of town; and Interstate 5 runs north-south through the city of Sacramento just across the river. The official elevation of West Sacramento is 20 feet and the total land area within the city limits is 22.8 feet. See Figure 1 for a map of the City of West Sacramento.

The Central Valley climate can be described as Mediterranean. During the hot, dry, sunny summers, temperatures can exceed 100 degrees Fahrenheit on some days, however more often summer temperatures are in the low 90s. The Sacramento River Delta breeze usually cools overnight temperatures into the 60s. Spring and fall has some of the most pleasant weather in the state.

Table 4 shows the City of West Sacramento weather averages.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
High Temp 55 62 67 74 82 89 94 93 89 79 64 55
Low Temp 41 45 47 50 54 58 61 61 59 54 46 40
Precipitation 4.18 3.77 3.15 1.17 .6 .18 .05 .05 .37 1 2.59 2.76 Table 4: City of West Sacramento Weather Averages

1.4 HISTORY
Over four thousand years ago, the Patwin Indians were the first inhabitants of the area now known as the City of West Sacramento. These Native Americans established villages on the west bank of the Sacramento River and their members often numbered in the hundreds. The Patwin Indians took advantage of the abundant natural resources offered by the land and water that surrounded them. They hunted and fished; they also crafted baskets, fishing nets, boats, and rafts from willows, tough grasses, and vines. All of their needs were provided by their environment.

The tranquil lifestyle of the Patwin Indians changed dramatically with the introduction of European settlers during the 19th century. Many hunters and trappers were attracted to the Sacramento Valley by the abundance of fur-bearing animals. Tragically, with the arrival of these European explorers came diseases which decimated the Patwin Indian population. Malaria and smallpox epidemics swept throughout the Patwin and other surrounding Native American villages in 1833 and 1837. By the time the epidemics had been contained, the Native American population in the Sacramento Valley had dropped from 60,000 to 20,000 people. Over time, more and more settlers came to the valley. The few remaining Patwin Indians either became employed or enslaved by the Euro American settlers, thus bringing to a close the Patwin cultural lifestyle.

In 1844, Jan Lows de Swart, a Flemish traveler, was the first Euro-American to permanently settle in the area of West Sacramento. Jan, who came to be known as John Schwartz, built a shack along the west bank of the Sacramento River six miles south of the confluence with the American River.

In 1845, Schwartz acquired a land grant from the Mexican Governor Manuel for an area of land one mile wide and twenty miles long. He named his newly acquired property "Rancho Nueva Flandria" after his native homeland. Shortly after settling here, John, with the help of his brother George, established a salmon fishery along the river. Besides drying and pickling the salmon, they also engaged in raising livestock and cultivating potatoes and melons. Little did John and his brother realize that within a few years, the great gold rush of 1848 would begin in California. The announcement of the discovery of gold at Sutter's Mill brought thousands of miners to the area. 120
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In 1846, an adventuresome jack-of-all-trades named James McDowell bought 600 acres of "Rancho Nueva Flandria" from John Schwartz. With his wife, Margaret, and their three daughters, McDowell settled in the area we know today as Broderick. The McDowell family was not untouched by the violence that often marked the tumultuous times of the Gold Rush. In May of 1849, James McDowell was shot and killed in a barroom brawl that he had supposedly instigated. With the loss of the sole supporter of the McDowell family, Margaret had to find the means to support herself and her children. At first, Margaret McDowell took boarders into her home as a means of gaining some income, but she soon realized that this was not enough. It became apparent that the land she owned was her most valuable asset. In October of 1849, Margaret hired a land surveyor to map out 160 acres, which was subsequently divided into forty-one blocks. She sold individual lots within this platted area which she named the Town of Washington. The first lot was sold to August W.

Kaye for $500. During the ten years following its creation, the rural Town of Washington experienced a significant increase in business development and shipping activity. One of the earliest companies to be established in the town was the California Steam Navigation Company, which was attracted to the area in 1859 by the close proximity of the Sacramento River. Other economic enterprises that marked early Washington included hotels, saloons, and restaurants catering to the needs of weary travelers. Many travelers making the harsh journey through the marshlands on their way to Sacramento welcomed the rest stop at the Town of Washington.

Other enterprises that found success in the early days of West Sacramento were the fishing and farming industries. Fishermen saw the profitable potential in salmon, sturgeon, catfish, eel, crayfish, and clams. The river community was thriving, supplying fish markets not only in Sacramento, but in San Francisco as well. In addition, the rich soil of the valley produced abundant crops of com, melons, cucumbers, and sweet potatoes. The dairy industry also established roots in West Sacramento around this time. One of the area's most well-known dairy farmers was Mike Bryte. Bryte came to California in 1849 to try his hand at gold mining. Although he did not make a fortune in gold, he bought a dairy farm in 1853 which was very successful. When the California Steam Navigation Company came to Washington, Bryte used the steamships to carry his dairy products to regional markets. Profits from this allowed Bryte to expand his holdings. By 1879, he owned 1,500 acres of land, raised 150 cows and 100 young stock, and farmed 2,500 acres in Sacramento County. Mike Bryte's status in the community was marked by his election to the Yolo County Board of Supervisors and later as sheriff. During the 20th century, Mike Bryte's property was subdivided and became known as the community of Bryte.

With time, the area continued to grow, prosper, and develop. The Town of Washington was renamed Broderick in honor of U. S. Senator David D. Broderick. After 1900, the three communities known as Bryte, Broderick, and West Sacramento were cumulatively known as "East Yolo.” From 1900 to 1920, the population of East Yolo doubled from 1,398 to 2,638. These communities are the foundation on which the current City of West Sacramento is built. In June 1963, the Port of Sacramento was opened to deep sea traffic with the completion of the Deep Water Ship Channel.

The project had been authorized by Congress in 1946 and construction commenced in 1949. The City of West Sacramento was officially incorporated as a city in 1987. Although the City continues to change and grow even today, its roots are deeply embedded in the community spirit of the past.

1.5 ECONOMY
West Sacramento is a vibrant, innovative and business friendly community located just across the beautiful Sacramento River from California's capital city. The city's redevelopment, growth and increasingly diverse economy are inspired by a community personality and energy all its own. The City maintains a business climate that encourages new business formation and growth. 121
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It is envisioned for the future that West Sacramento will continue to build on its successes since incorporation, as a vibrant city where people can live, work and play. As the City grows and develops, it will work to expand on its most recognized characteristics.

Top West Sacramento Employers
 Raley’s
 IKEA
 Walmart
 Amazon
 CalSTRS
 Nor-Cal Beverage
 UNFI (Formerly Tony’s Fine Foods)
 City of West Sacramento
The City will remain a powerful job center for the region and continue to have a strong and diverse economy, maintaining its current strengths as a global food hub and in distribution, adding significant new employment in manufacturing and office occupations. The City will continue to retain a job surplus. As the city’s downtown, West Capitol Avenue will find new life as an active and attractive mixed-use commercial and residential core.

The City will continue to approach planning and investments that provide community-wide benefit such as the Civic Center, Community Center, River Walk, Barge Canal Access, and bridges that join the north and south areas as well as streetcar and bridges east across the river to downtown Sacramento.

1.6 DEVELOPMENT TRENDS
Based on this information below in the following paragraphs, this plan has been revised to reflect changes in development within the City of West Sacramento. The City is a high growth city. There are several development projects planned and there is an expansion of housing projects throughout the city.

According to the General Plan Background report in 2015 on Demographics and Economic Conditions, the growth between 2000 and 2007 for the West Sacramento retail, office, and industrial submarket grew by 22.1 percent, with the office market experiencing the largest increase. However, at a 19.2 percent vacancy rate (compared to 11.8 percent for the Sacramento regional market), the office market is over-supplied while the retail and industrial markets appear under-supplied with very-low- to low-vacancy rates (1.4 percent retail and 5.8 percent industrial vacancy rates compared to 6.1 percent retail and 8.4 percent industrial vacancy rates for the Sacramento regional market).

Assuming a 5 percent vacancy rate, the 28,314 households projected by 2030 for West Sacramento will create demand for approximately 29,804 housing units. New housing demand totals 12,238 units, which amounts to nearly a 70 percent increase over the city’s current housing stock. Current (2012) housing units are split approximately 68 percent single-family and 24 percent multi-family.

Detached and attached single-family units constitute the single-family category, and all other units (apartments, condominiums, and mobile homes) comprise the multi-family category.

There has been development since the previous plan and there will continue during the next planning cycle, the City will do a better job on getting development numbers. Details were not available in this planning cycle for specific development numbers. All of the development done in 122
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the hazard prone areas were done to the floodplain ordinance and modern building codes. As such, though there may be more residents and structures in the hazard area, the risk and vulnerability is not expected to be greater than it was before the development occurred.

1.7 POPULATION
The California Department of Finance estimated the January 1, 2022 total population for the City of West Sacramento was 52,837.

According to SACOG, West Sacramento’s population is projected to increase by 74 percent from 2014 to 2035, to more than 88,600 residents by 2035.
 West Sacramento is projected to account for more than half (53 percent) of projected growth in Yolo County from 2014 to 2035.
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VULNERABILITY ASSESSMENT
The City of West Sacramento identified the hazards that affect the city and developed natural hazard profiles based upon the countywide risk assessment, past events and their impacts.

This risk assessment covers the entire geographical extent of the City of West Sacramento. In accordance with FEMA requirements, this risk assessment describes how the hazards and risks vary across the City.

This LHMP Update involved a comprehensive review and update of each section of the 2018 risk assessment. Information from the 2018 LHMP was used in this Plan Update where valid and applicable. As part of the risk assessment update, new data was used, where available, and new analyses were conducted. Where data from existing studies and reports was used, the source is referenced throughout this risk assessment.

2.1 HAZARD IDENTIFICATION
The City of West Sacramento planning team conducted a hazard identification assessment to determine the natural hazards that threaten the City. This section details the methodology and results of this effort.

Data Sources
The following data sources were used for this Hazard Identification portion of this Plan:
 California Office of Emergency Services (CAL OES)
 HMPC input
 National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC) Storm Events Database
 2018 Yolo County LHMP
 2018 State of California Hazard Mitigation Plan
 City General Plan Documents
 City 2018 LHMP Annex
 City EOP
Results and Methodology
Using existing hazards data and input gained through planning meetings, the planning team agreed upon a list of natural hazards, those are identified in Table 4, that could affect the City. Hazards data from Cal OES, FEMA, the NOAA NCDC database, and many other sources were examined to assess the significance of these hazards to the area. Those hazards identified as a high or medium significance are considered priority hazards for mitigation planning. Those hazards that occur infrequently or have little or no impact on the City were determined to be of low significance and not considered a priority hazard. Significance was determined based on the hazard profile, focusing on key criteria such as frequency, extent, and resulting damage, including deaths/injuries and property, and economic damage. The ability of a community to reduce losses through implementation of existing and new mitigation measures was also considered as to the significance of a hazard. The hazard and risk assessment is shown in Table 5.

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Geographic
Extent
Likelihood of
Future
Occurrences
Magnitude/
Severity Significance
Climate
Change
Influence
Dam Failure Extensive Unlikely Catastrophic Low
Drought Significant Likely Limited Low
Earthquake Significant Occasional Limited Low
Flooding Extensive Occasional Catastrophic High
Land Subsidence Limited Likely Negligible Low
Levee Failure Extensive Occasional Catastrophic High
Severe Weather:

Extreme Heat Extensive Highly Likely Critical Medium
Severe Weather:

Extreme Cold and
Freeze
Extensive Highly Likely Limited Medium
Severe Weather: Fog Significant Highly Likely Negligible Low Severe Weather: High
Winds
Extensive Highly Likely Critical Medium
Severe Weather:

Tornado
Limited Unlikely Limited Low
Volcano Negligible Unlikely Negligible Low
Wildfire Significant Occasional Critical Low
Geographic Extent
Limited: Less than 10% of
planning area
Significant: 10-50% of
planning area
Extensive: 50-100% of
planning area
Likelihood of Future
Occurrences
Highly Likely: Near 100%
change of occurrence in next
year, or happens every year.

Likely: Between 10 and
100% change 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 or
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
Catastrophic – More than 50% of property severely damaged; shutdown of facilities for more than 30 days; and/or multiple deaths.

Critical – 25-50% of property severely damaged; shutdown of facilities for at least two weeks; and/or injuries and/or illness result in permanent disability.

Limited – 10-25% of property severely damaged; shut down of facilities for more than a week; and/or injuries/illnesses treatable to do not result in permanent disability.

Negligible – Less than 10% of property severely damaged, shutdown of facilities and services for less than 24 hours; and/or injuries/illness treatable with first aid.

Significance
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact
Climate Change Influence
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact
Table 5: City of West Sacramento - Hazard Identification Assessment 125
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6. Hazard Excluded Why Excluded
Air Pollution The City did consider this a hazard for this Plan, it is dealt with in other planning mechanisms in the City. Smoke is discussed in the wildfire hazard.

Energy Shortage and
Energy Resilience
The City did consider this a hazard, it is dealt with in other planning mechanisms in the City.

Natural Gas Pipeline
Hazards
The City did not consider this a hazard as we only looked at the natural hazards and we work directly with the utility provider on other planning/preparedness and response planning resources.

Oil Spills The City did not consider this a hazard, as there are other regulatory planning mechanisms to address this hazard.

Radiological Accidents There is minimal exposure in the City at risk to this hazard.

Cyber Threats The City did consider this a hazard, but it is dealt with in other planning mechanisms in the City.

Airline Crashes There have been no past occurrences in the City of airplane crashes.

This is not a hazard to be included in the LHMP.

Civil Disturbance The City did consider this a hazard, but it is dealt with in other planning mechanisms in the City.

Table 6: City of West Sacramento – Excluded Hazards

2.2 HAZARD PROFILES
Each hazard vulnerability assessment in this section includes a hazard profile/problem description as to how each medium or high significant hazard affects City of West Sacramento and includes information on past hazard occurrences and the likelihood of future hazard occurrence. The intent of this section is to provide jurisdictional specific information on hazards and further describes how the hazards and risks differ across the Yolo County Operational Area.

Yolo County identified natural hazards that affect the unincorporated county and developed natural hazard profiles based upon the countywide risk assessment, past events and their impacts. All of the natural hazards profiled in the Yolo County Hazard Mitigation Plan can affect the different jurisdictions and are detailed below. No additional hazards are profiled. Definitions for the rankings and a detailed explanation of the hazards can be found in Section 3.0 Hazard Identification and Risk Assessment in the Base Plan.

CLIMATE CHANGE
Climate change will affect the people, property, economy and ecosystems of the City in a variety of ways. Climate change impacts are most frequently associated with negative consequences, such as increased flood vulnerability or increased heat-related illnesses and other public health concerns; however, other changes may present opportunities. The most important effect for the development of this Plan is that climate change will have a measurable impact on the occurrence and severity of natural hazards.
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This LHMP Update is concerned with human-induced climate change that has been rapidly warming the Earth at rates unprecedented in the last 1,000 years. Since industrialization began in the 19th century, the burning of fossil fuels (coal, oil, and natural gas) at escalating quantities has released vast amounts of carbon dioxide and other greenhouse gases responsible for trapping heat in the atmosphere, increasing the average temperature of the Earth. Secondary impacts include changes in precipitation patterns, the global water cycle, melting glaciers and ice caps, and rising sea levels. According to the Intergovernmental Panel on Climate Change (IPCC), climate change will “increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems” if unchecked.

Climate change is not a discrete event but a long-term hazard, the effects of which communities are already experiencing.

Climate change adaptation is a key priority of the State of California. The 2023 State of California Multi-Hazard Mitigation Plan stated that climate change is already affecting California. Sea levels have risen by as much as seven inches along the California coast over the last century, increasing erosion and pressure on the state’s infrastructure, water supplies, and natural resources. The State has also seen increased average temperatures, more extreme hot days, fewer cold nights, a lengthening of the growing season, shifts in the water cycle with less winter precipitation falling as snow, and earlier runoff of both snowmelt and rainwater in the year. In addition to changes in average temperatures, sea level, and precipitation patterns, the intensity of extreme weather events is also changing.

Climate change is a global phenomenon. It is expected to affect the whole of the City. Climate change exacerbates other hazards, such as drought, extreme heat, flooding, wildfire, and others.

The speed of onset of climate change is very slow. The duration of climate change is not yet known but is feared to be tens to hundreds of years.

Climate change is virtually certain to continue without immediate and effective global action.

According to NASA, 2017 and 2019 were two of the hottest years on record. Without significant global action to reduce greenhouse gas (GHG) emissions, the IPCC concludes in its Fifth Assessment Synthesis Report (2014) that average global temperatures are likely to exceed 1.5°C by the end of the 21st century, with consequences for people, assets, economies and ecosystems, including risks from heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scarcity, sea level rise and storm surges.

Additionally, according to the City’s current Climate Action Plan, climate change is an on-going longterm change in average global or regional weather patterns. Since the mid-20th century, our climate has been warming at an increasing rate. Scientists attribute this global warming trend to human expansion of the "greenhouse effect" — warming that occurs when the atmosphere traps 127
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Climate change is the distinct change in measures of weather patterns over a long period of time, ranging from decades to millions of years. More specifically, it may be a change in average weather conditions such as temperature, rainfall, snow, ocean and atmospheric circulation, or in the distribution of weather around the average.

Climate change is expected to affect West Sacramento, Yolo County, the State of California, and the world. Climate change is expected to exacerbate the effects and impacts of other hazards. Climate change is already affecting and will continue to alter the physical environment throughout the City and greater Sacramento Valley; however, specific implications of climate change effects vary with differing physical, social, and economic characteristics within the City.

The City of West Sacramento in general could see population fluctuations as a result of climate impacts relative to those experienced in other regions, and these fluctuations could be expected to impact demand for housing and other development. For example, sea level rise may disrupt economic activity and housing in coastal communities, resulting in migration to inland urban areas.

Other interior western states may experience an exodus of population due to challenges in adapting to heat even more extreme than that which is projected to occur here.

The California Climate Adaptation Strategy outlines the following climate change impact concerns for the Northern Sierra Nevada Region communities (California Natural Resources Agency 2021):
 Increased temperature
 Decreased precipitation
 Reduced snowpack
 Reduced tourism
 Ecosystem change
 Sensitive species stress
 Increased wildfire frequency and area burned.

Climate change vulnerability will also be noted for each hazard in the following sections.

2.2.2 FLOOD
Hazard/Problem Description
Flooding is the rising and overflowing of a body of water onto normally dry land. History clearly highlights floods as one of the primary natural hazards impacting the City. Floods are among the costliest natural disasters in terms of human hardship and economic loss nationwide. The City of West Sacramento is susceptible to various types of flood events as described below.  Riverine flooding – Riverine flooding, defined as when a watercourse exceeds its “bankfull” capacity, generally occurs as a result of prolonged rainfall, or rainfall that is combined 128
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onset and duration of riverine floods
may vary from a few hours to many
days and is often characterized by high
peak flows combined with a large
volume of runoff. 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 waterresistance of the surface due to urbanization. In the City of West
Sacramento, riverine flooding can occur
anytime from November through April and is largely caused by heavy and continued rains, sometimes combined with snowmelt, increased outflows from upstream dams, and heavy flow from tributary streams. These intense storms can overwhelm the local waterways as well as the integrity of flood control structures. Flooding is more severe when antecedent rainfall has resulted in saturated ground conditions. The warning time associated with slow rise riverine floods assists in life and property protection  Flash flooding – Flash flooding describes localized floods of great volume and short duration. This type of flood usually results from a heavy rainfall on a relatively small drainage area. Precipitation of this sort usually occurs in the winter and spring. Flash floods often require immediate evacuation within the hour and thus early threat identification and warning is critical for saving lives.
 Localized/Stormwater 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.

Flooding, and the threat of a flood emergency have been associated with the Sacramento region and Central Valley throughout history. West Sacramento is particularly susceptible to flooding due to its location at the confluence of the Sacramento and American Rivers. Historically, West Sacramento suffered from almost annual flooding until the massive reclamation efforts of the early twentieth century.

Over the past few decades, the City of West Sacramento has experienced significant flooding.

General rain floods can occur in the City anytime during the period from November through April.

This type of flood results from prolonged heavy rainfall and is characterized by high peak flows of moderate duration and by a large volume of runoff. Flooding is more severe when antecedent rainfall has resulted in saturated ground conditions.

According to the National Flood Insurance Study in Yolo County most recent 2012 report, during high flood-flows, the City of West Sacramento is not protected from flooding by the levees along the Sacramento River and the Yolo Bypass. Yolo Bypass drains water from Cache Creek, Putah Creek and also receives flows from the Sacramento River over Fremont Weir near Knights Landing, and 129
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Floodwaters flow south to the SPRR embankment then through the street undercrossings at Jefferson Boulevard and Fifth Street. The flooding continues south to the old Sacramento Northern Railway embankment where the flow is restricted by the two smaller undercrossings located at West Capitol Avenue and the old Highway 40. The Sacramento Northern embankment is ultimately overtopped and the floodwaters flow south into the SRDWSC. The Sacramento River right levee south of the SRDWSC lock fails due to structural instability. Floodwater flows into the city area south of the SRDWSC, 13 fills the entire area, and then overtops and fails the south SRDWSC levee.

The SRDWSC then carries the water out of the study area. The Yolo Bypass east levee just south of the SPRR fails due to encroachment of freeboard. Floodwater flows into the city area north of the SRDWSC, fills the area, and flows into the SRDWSC. Flows in the SRDWSC are large enough that some water flows into and floods the city area south of the SRDWSC. The 1-percent annual chance flows for the Sacramento River and Yolo Bypass are concurrent events. It is possible for levee failures to occur on both the Yolo Bypass and Sacramento River for the same storm. A scenario assuming a failure on both systems was found to cause the greatest amount of flooding for most of the City of West Sacramento.

Past Occurrences
Disaster Declaration History
A list of state and federal disaster declarations since the last planning cycle for the City of West Sacramento from flooding, (including heavy rains and storms) is shown on Table 7.

Disaster Type State Declarations Federal Declarations
Count Years Count Years
Flood (including
heavy rains and
storms) since the last
plan update in 2018
and included in OA
Declaration
5 05/01/2019
05/17/2019
01/04/2023
01/04/2023
04/20/2023
5 05/01/2019 DR4431-CA
05/17/2019 DR4434-CA
01/14/2023 DR4683-CA
01/19/2023 EM3591-CA
04/03/2023 DR4699-CA
Source: Cal OES, FEMA
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Occasional: Between 1 and 10% chance of occurrence in the next year or has a recurrence interval of 11 or 100 years.

VULNERABILITY ASSESSMENT
Vulnerability—Extremely High
Historically, West Sacramento has always been vulnerable to flooding because of its relatively flat terrain and the number of water courses that traverse the City. High water levels are a common occurrence in winter and spring months due to increased flow from stormwater runoff and snowmelt. Most areas of the City are subject to flooding by the failure of urban drainage systems that cannot accommodate large volumes of water during severe rainstorms.

River flooding is the most significant natural hazard that West Sacramento faces. Sacramento is not just at high risk of flooding but is at high risk of catastrophic flooding. When the 100-year event is exceeded, the consequences could be great as flood depths behind levees can range up to many feet deep in some urban areas.

The vulnerable populations within the City are all vulnerable to the flood hazard, those populations include the homeless, elderly, people in care facilities and other populations that have access and functional needs. Those can include: non-English speakers, people on life saving devices requiring power, those that are on medications, and many more.

Impacts
Floods and their impacts vary by location and severity of any given flood event and will likely only affect certain areas of the City during specific times. Natural areas, such as wetlands and riparian 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. Preserving and protecting these areas and associated functions are a vital component of sound floodplain management practices for West Sacramento. Based on the risk assessment, it is evident that floods will continue to have potentially devastating human and economic impacts to certain areas of the City, especially to those areas near rivers, creeks, and streams. Surrounded by levees on all sides, the City of West Sacramento is inherently more vulnerable to flooding than most other urbanized areas in the country. Levee failure flooding is discussed in more detail in Section 2.4 below. The City noted that many of the floods in the City are minor, localized flood events that are more of a nuisance than a disaster. Specific impacts to the City from riverine flooding that are not fully quantified, but can be anticipated in large future events, include:
 Injury and loss of life
 Commercial and residential structural and property damage  Disruption of and damage to public infrastructure and services  Health hazards associated with mold and mildew, contamination of drinking water, etc.  Damage to roads/bridges resulting in loss of mobility  Significant economic impact (jobs, sales, tax revenue) to the community  Negative impact on commercial and residential property values  Significant disruption to students and teachers as temporary facilities and relocations would likely be needed
 At risk populations and underserved communities
 Impact on the overall mental health of the community
 City facilities are all at risk from the flood hazard across the planning area, those facilities are all documented in Table 9.
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Predominantly, the effects of flooding are generally confined to areas near the waterways of the City. As waterways grow in size from local drainages, so grows the threat of flood and dimensions of the threat. This threatens structures in the floodplain. Structures can also be damaged from trees falling as a result of water-saturated soils. Electrical power outages happen, and the interruption of power causes major problems. Loss of power is usually a precursor to closure of governmental offices and community businesses. Schools may also be required to close or be placed on a delayed start schedule. Roads can be damaged and closed, causing safety and evacuation issues. People may be swept away in floodwaters, causing injuries or deaths.

Floods can cause substantial damage to structures, landscapes, and utilities as well as life safety issues. Floods can be extremely dangerous, and even six inches of moving water can knock over a person given a strong current. A car will float in less than two feet of moving water and can be swept downstream into deeper waters. This is one reason floods kill more people trapped in vehicles than anywhere else. During a flood, people can also suffer heart attacks or electrocution due to electrical equipment short outs. Floodwaters can transport large objects downstream which can damage or remove stationary structures, such as dam spillways. Ground saturation can result in instability, collapse, or other damage. Objects can also be buried or destroyed through sediment deposition. Floodwaters can also break utility lines and interrupt services. Standing water can cause damage to crops, roads, foundations, and electrical circuits. 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 from any type of flooding.

Impacts from streambank erosion include greater levee maintenance and increased risk of levee failure. Should the levees fail, the area protected by the levees would be flooded.

Flooding also brings contamination and disease. Floodwaters can carry raw sewage, leaked toxic chemicals, and runoff from hazardous waste sites and factory farms. They can pollute drinking water supplies and cause eye, ear, skin, and gastrointestinal infections. When floodwaters recede, bacteria and mold may remain, and residents may suffer from mental health problems and lost business or wages.

As with many natural hazards, it is most often lower-income people, people experiencing homelessness, the elderly, and communities of color who suffer the greatest harm. These populations are least likely to have flood insurance, access to transportation during an evacuation, cash on hand, or the ability to relocate—and the structural inequities of the past and present mean they are more likely to be in harm’s way.

Participation in the National Flood Insurance Program
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25 Section 2.0: Hazard Identification and Risk Assessment County of Yolo The City participates in the NFIP and continues to enforce the compliance with the NFIP through their Flood Plain Management Ordinance. The floodplain management ordinance meets the NFIP’s floodplain management criteria.

Currently, there is one (1) Repetitive Loss property and zero (0) Severe Repetitive Loss Properties in West Sacramento.

For more information on the NFIP Program refer to Section 3.1.1 Regulatory Capability in this Annex and the Yolo County Base Plan.

Climate Change and Flooding
Use of historical hydrologic data has long been the standard of practice for designing and operating water supply and flood protection projects. For example, historical data are used for flood forecasting models and to forecast snowmelt runoff for water supply. This method of forecasting assumes that the climate of the future will be similar to that of the period of historical record.

However, scientists project greater storm intensity with climate change, resulting in more direct runoff and flooding. High frequency flood events (e.g., 10-year floods) in particular will likely increase with a changing climate. What is currently considered a 1-percent-annual-chance (100- year) flood also may strike more often, leaving many communities at greater risk. Going forward, model calibration must happen more frequently, new forecast-based tools must be developed, and a standard of practice that explicitly considers climate change must be adopted.

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

The amount of snow is critical for water supply and environmental needs, but so is the timing of snowmelt runoff into rivers and streams. Rising snowlines caused by climate change will allow more mountain areas, such as the Sierra Nevada watersheds, to contribute to peak storm runoff.

Changes in watershed vegetation and soil moisture conditions will likewise change runoff and recharge patterns. As stream flows and velocities change, erosion patterns will also change, altering channel shapes and depths, possibly increasing sedimentation behind dams, and affecting habitat and water quality.

Changes in Population
Impacts to identified assets at risk to this hazard and the overall vulnerability of the City may be affected in the future by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development.

Population projections for the City show slower growth to 2035 as detailed in our most current general plan. Populations are anticipated to grow by only 2.4% between now and 2035, thus future population growth should not increase the potential impacts from this hazard on City assets. With respect to population patterns such as those associated with migration, density, or makeup of 133
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Future Development
Communities that participate in the NFIP adopt regulations and codes that govern development in special flood hazard areas and enforce those requirements through their local floodplain management ordinances through the issuance of permits. West Sacramento floodplain management ordinance provides standards for development, subdivision of land, construction of buildings, and improvements and repairs to buildings that meet the minimum requirements of the NFIP.

The International Residential Code (IRC) and International Building Code (IBC), by reference to ASCE 24, include requirements that govern the design and construction of buildings and structures in flood hazard areas. FEMA has determined that the flood provisions of the I-Codes are consistent with the requirements of the NFIP (the I-Code requirements shown either meet or exceed NFIP requirements). ASCE 24, a design standard developed by the American Society of Civil Engineers, expands on the minimum NFIP requirements with more specificity, additional requirements, and some limitations.

One of the most effective ways to reduce vulnerability to potential flood damage is through careful land use planning that fully considers applicable flood management information and practices.

Preservation and maintenance of natural and riparian areas should also be an ongoing priority to realize the flood control benefits of the natural and beneficial functions of these areas. Also to be considered in reducing flooding in areas of existing and future development is to promote implementation of stormwater program elements and erosion and sediment controls, including the clearing of vegetation from natural and human-made drains that are critical to flood protection.

Both native and invasive species can clog drains, and reduce flows of floodwaters, which slow that natural drainage process and can exacerbate flooding.

California’s 2007 flood legislation (Senate Bill 5) directly linked system-wide flood management planning to local land use planning, requiring local jurisdictions to demonstrate an urban level of flood protection before approving new development in urban and urbanizing areas. “Urban level of flood protection” means the level of protection necessary to withstand flooding that has a 1-in-200 chance of occurring in any given year (California Government Code Section 65007). DWR has been developing criteria to guide local jurisdiction compliance with the new requirements. In addition to developing criteria to help local jurisdictions in their land use planning, DWR is preparing criteria for use in the design of levees protecting urban and urbanizing areas. DWR is also working with local partners to develop guidance related to nonurban flood protection levels.

Once these standards become effective, cities and counties within the Sacramento-San Joaquin Valley cannot enter into development agreements or issue a permit to construct a new structure in areas located within a flood hazard zone unless the following is established:
 Find that existing facilities protect urban and urbanizing areas to a 1-in 200 chance of flooding in any given year or the FEMA standard of flood protection in non-urbanized areas  Find that the local flood management agency has made adequate progress on the construction of the flood protection system to provide the required level of protection  Impose conditions on the development agreement that will provide the required level of protection

2.2.3 LEVEE FAILURE
Hazard/Problem Description
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27 Section 2.0: Hazard Identification and Risk Assessment County of Yolo A levee is a raised area that runs along the banks of a stream or canal. Levees reinforce the banks and help prevent flooding by containing higher flow events to the main stream channel. By confining the flow to a narrower steam channel, levees can also increase the speed of the water.

Levees can be natural or man-made. A natural levee is formed when sediment settles on the streambank, raising the level of the land around the stream.

Levees provide strong flood protection, but they are not failsafe. Levees are designed to protect against a specific flood level and could be overtopped during severe weather events or dam failure.

Levees reduce, not eliminate, the risk to individuals and structures located behind them. A levee system failure or overtopping can create severe flooding and high-water velocities. It is 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.

In addition to overtopping, levee systems can fail or be compromised in a variety of ways. Underseepage refers to water flowing under the levee through the levee foundation materials, often emanating from the bottom of the landside slope and ground surface and extending landward from the landside toe of the levee. Through-seepage refers to water flowing through the levee prism directly, often emanating from the landside slope of the levee. Both conditions can lead to failure by several mechanisms, including excessive water pressures causing foundation heave and slope instabilities, slow progressing internal erosion, and piping leading to levee slumping. Rodents can burrow into and compromise the levee system. Erosion can also lead to levee failure. Figure 2 depicts many causes of levee failure.

Figure 2 Potential Causes of Levee Failure
Source: USACE
The potential for flooding in the West Sacramento area depends on the levee system and magnitude of flood hazards. Inundation of West Sacramento could occur if the levees failed or were overtopped by flood waters. The area of greatest concern is along the west bank of the Sacramento 135
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28 Section 2.0: Hazard Identification and Risk Assessment County of Yolo River south of the barge canal. A report prepared
for the Corps found low stability of levee materials
in this area. During the 1986 floods, some
slumping of a section of levee occurred near the
intersection of Davis Road and South River Road.

Other areas that have experienced levee slumping
and spreading are located on the east side of the
Yolo Bypass. Levee slumping has occurred in
areas just south of Highway 80, between Highway
80 and the Southern Pacific railroad tracks, and
the levee from the Sacramento Bypass to the
railroad tracks. The levee section between the
railroad tracks and Highway 80 is now stable after
repairs in 1983 and showed no problems during
the 1986 floods. The area from the railroad tracks
to the Sacramento Bypass has experienced not
only slumping and spreading, but also damage
from wave action during the 1986 floods.

Although much remedial work has been
completed, more work is proposed by WSAFCA in
conjunction with the Corps to meet the City’s 200-
year level of protection goal.

RD 900
RD 900 is an independent special district that maintains the majority of the levees that surround West Sacramento, including 13.6 miles of levee on the east and west boundaries of the City. The district overlies approximately two-thirds of the City. RD 900 is bound by the Southern Pacific Railroad embankment on the north, the Sacramento River on the east, Shangri-La Slough on the south, and the Sacramento Deep Water Ship Channel (DWSC) on the west. The DWSC also bisects RD 900 into two district areas.

RD 900 participates in levee design, engineering, construction, and maintenance; flood system planning and policy development; and is responsible for flood fight operations, including levee patrol and repair, within its boundaries. RD 900 does not have a role in performing evacuation operations but will make information and recommendations for voluntary and mandatory evacuations to the City EOC. RD 900 coordinates regularly with RD 537 and MA 4.

The district consists of a seven-person staff and a five-member board of trustees. The RD 900 District Manager is the point of contact for West Sacramento.

Location and Extent
Approximately 150 years ago, the levees of the Sacramento-San Joaquin Delta were raised to prevent flooding on what remains some of the most fertile farmland in the nation. While the peat soils were excellent for agriculture, they do not create strong foundations for levee barriers meant to contain a constant flow of river water. Nevertheless, it was these native soils that were primarily used to create the levee system.

Past Occurrences
Disaster Declaration History
There have been no federal or state disasters declarations related to levee failure in West Sacramento.
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There have been about 5-10 levee issues since the last planning period. However, most of these issues were small scale and did not result in any threats to life, property or the environment.

These numbers are not representative of future occurrences within the City Likelihood of Future Occurrence
Occasional – Due to the low number of past events, future levee failures are occasional. It is important to note that numerous levee improvement projects have been completed and are ongoing throughout the City, which will make the future occurrence of levee failure less likely to occur.

VULNERABILITY ASSESSMENT
Vulnerability—Extremely High
Levee failure flooding can occur as the result of partial or complete collapse of an impoundment, and often results from prolonged rainfall and resulting higher water elevations in the river. The primary danger associated with dam or levee failure is the high velocity flooding of those properties downstream of the breach. Impacts from this include property damage, critical facility damage, and life safety issues. Vulnerability to levee failures is generally confined to the areas subject to inundation downstream of a flood protection facility. Secondary losses would include loss of the multi-use functions of the facility and associated revenues that accompany those functions.

The vulnerable populations within the City are all vulnerable to the levee failure hazard, those populations include the homeless, elderly, people in care facilities and other populations that have access and functional needs. Those can include: non-english speakers, people on life saving devices requiring power, those that are on medications, and many more.

Impacts
Levee failures and their impacts would vary by location and severity of any given levee failure or breach event and will likely only affect certain areas of the City during specific times. Based on the number of levees located throughout the City and population in leveed areas, future levee failure events would have potentially devastating economic impacts to the City. Impacts that are not quantified, but can be anticipated in large future events, include:
 Commercial and residential structural and property damage  City facilities are all at risk from the flood hazard across the planning area, those facilities are all documented in Table 9
 Costs incurred due to post-flood clean up and repair of buildings and infrastructure  Damage to roads/bridges resulting in loss of mobility  Decreased revenue due to loss of income, sales, tourism, and property taxes  Deterioration of homes and neighborhoods as floods recur  Disruption of and damage to public infrastructure and services  Health hazards associated with mold and mildew, contamination of drinking water, etc.  Impact on the overall mental health of the community
 Injury and loss of life, including first responders rescuing those who did not evacuate or are stranded
 Loss of historical or unique artifacts
 Loss of jobs due to businesses closing or cutting back on operating hours  Loss of programs or services that are cut to pay for flood recovery  Mental health and family impacts, including increased occurrence of suicides and divorce  Negative impact on commercial and residential property values 137
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 Significant economic impact (jobs, sales, tax revenue) to the community The aftermath of levee failure events presents numerous threats to public health and safety, including unsafe food, contaminated drinking and washing water and poor sanitation, mosquitoes and animals, mold and mildew, carbon monoxide poisoning, and mental stress and fatigue. The best preparation for these effects includes awareness that they can occur, education of the public on prevention, and planning to deal with them during responses to flooding events. Levee failure can be a deadly hazard. Roads running through low-lying areas prone to sudden and frequent flooding are a serious threat. The potential for injuries from levee failure flooding results from people walking or playing in or near flooded areas. Generally, floods kill people in one of two situations:
when people ignore basic safety precautions (such as evacuations and warnings), and when a flash flood hits an area with no warning. Although it is possible to analyze life and safety impacts resulting from the flood hazard, injuries and casualties were not estimated for this hazard.

Climate Change and Levee Failure
On average, changes in California’s annual precipitation levels are not expected to be dramatic; however, small changes may have significant impacts for water resource systems, including levees.

Levees are designed partly based on assumptions about a river’s flow behavior, expressed as hydrographs. Changes in weather patterns can have significant effects on the hydrograph used for the design of a levee. If the hygrograph changes, it is conceivable that the levee can lose some or all of its designed margin of safety, also known as freeboard.

Population projections for the City show slower growth to 2035 as detailed in our most current general plan. Populations are anticipated to grow by only 2.4% between now and 2035, thus future population growth should not increase the potential impacts from this hazard on City assets. With respect to population patterns such as those associated with migration, density, or makeup of socially vulnerable populations the data shows that most socially vulnerable populations and disadvantaged communities are concentrated in the central and northern portion of the City.

Future Development
SB 5 and levee improvement projects are underway in the City that will provide 200-year level of protection for urbanizing areas, as well as levee improvement projects to provide 100-year level in non-urban areas. These improvements will allow development in leveed areas to continue.

2.2.4 SEVERE WEATHER: EXTREME HEAT
Hazard/Problem Description
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31 Section 2.0: Hazard Identification and Risk Assessment County of Yolo According to information provided by FEMA, extreme heat is defined as temperatures that hover 10 degrees or more above the average high temperature for the region and last for several weeks.

Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of summer heat. In the 40-year period from 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the heat wave of 1980, more than 1,250 people died.

Heat disorders generally have to do with a reduction or collapse of the body’s ability to shed heat by circulatory changes and sweating or a chemical (salt) imbalance caused by too much sweating.

When heat gain exceeds a level at which the body can remove it, or when the body cannot compensate for fluids and salt lost through perspiration, the temperature of the body’s inner core begins to rise, and heat-related illness may develop. Elderly persons, small children, chronic invalids, those on certain medications or drugs, and persons with weight and alcohol problems are particularly susceptible to heat reactions.

Extreme heat can also affect agriculture in the City. Power outages are also a concern during extended heat events that occasionally overwhelm the utility companies, leading to temporary outages. Extreme heat conditions can also compound the effects of other hazards, such as drought and wildfire and can contribute to increases in tree mortality.

Location and Extent
Extreme heat events occur on a regional basis. Extreme heat can occur in any location of the City.

All portions of the City are at some risk to extreme heat. Extreme heat occurs throughout the City primarily during the summer months. The Western Regional Climate Center (WRCC) maintains data on weather normal and extremes in the western United States.

Heat emergencies are often slower to develop, taking several days of continuous, oppressive heat before a significant or quantifiable impact is seen. Heat waves do not strike victims immediately, but rather their cumulative effects slowly take the lives of vulnerable populations. Heat waves do not generally cause damage or elicit the immediate response of floods, fires, earthquakes, or other more “typical” disaster scenarios. While heat waves are obviously less dramatic, they are potentially deadlier. According to the 2018 California State Hazard Mitigation Plan, the worst single heat wave event in California occurred in Southern California in 1955, when an eight-day heat wave resulted in 946 deaths.

The NWS has in place a system or scale to initiate alert procedures (advisories or warnings) when extreme heat is expected to have a significant impact on public safety. The expected severity of the heat determines whether advisories or warnings are issued. The NWS HeatRisk forecast provides a quick view of heat risk potential over the upcoming seven days. The heat risk is portrayed in a numeric (0-4) and color (green/yellow/orange/red/magenta) scale which is similar in approach to the Air Quality Index (AQI) or the UV Index. This can be seen in Table 8.

Table 8: National Weather Service HeatRisk Categories
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Green 0 No Elevated Risk
Yellow 1 Low Risk for those extremely sensitive to heat, especially those without effective cooling and/or adequate hydration
Orange 2 Moderate Risk for those who are sensitive to heat, especially those without effective cooling and/or adequate hydration
Red 3 High Risk for much of the population, especially those who are heat sensitive and those without effective cooling and/or adequate hydration Magenta 4 Very High Risk for entire population due to long duration heat, with little to no relief overnight
Source: National Weather Service
The NWS office in Sacramento can issue the following heat-related advisory as conditions warrant.  Heat Advisories are issued during events where the HeatRisk is on the Orange/Red threshold (Orange will not always trigger an advisory)
 Excessive Heat Watches/Warnings are issued during events where the HeatRisk is in the Red/Magenta output
Past Occurrences
Disaster Declaration History
There have been no State or Federal disasters related to extreme heat.

Planning Team Events
Members of the Planning Team recalled the following events:
 August 2020
 September 2020
 May 2021
 June 2021
 July 2021
 August 2021
 September 2021
 June 2022
 September 2022
Likelihood of Future Occurrence
Highly Likely—Temperature extremes are likely to continue to occur annually in the City.

Temperatures at or above 90°F are common most summer days in the City.

VULNERABILITY ASSESSMENT
Vulnerability—Medium
Extreme heat happens in the City of West Sacramento each year. Extreme heat rarely affects buildings in the City but affects the population.

Impacts from Extreme Heat
Vulnerable populations are at the greatest risk to the effects of extreme heat.

Vulnerable populations to extreme heat include:
 Homeless
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 Elderly (65 and older)
 Individuals with disabilities
 Individuals dependent on medical equipment
 Individuals with impaired mobility
 Non-English Speakers
Extreme Heat can contribute to higher daytime temperatures, reduced nighttime cooling, and higher air-pollution levels. These, in turn, contribute to heat-related deaths and heat-related illnesses such as general discomfort, respiratory difficulties, heat cramps, heat exhaustion, and nonfatal heat stroke.

Extreme Heat can also exacerbate the impact of naturally occurring heat waves, which are periods of abnormally hot, and often humid, weather. Sensitive populations are particularly at risk during these events.
 Older adults are among the most vulnerable to extreme heat events. Many physiological, psychological, and socioeconomic factors contribute to this danger. Older adults are more likely to be in poor health, to be less mobile and more isolated, to be more sensitive to high heat, and to live on reduced incomes.
 Young children tend to be more susceptible to extreme heat due to their small size and other characteristics. Children’s more rapid breathing rates relative to body size, time spent outdoors, and their developing respiratory systems raise their chances of aggravated asthma and other lung diseases caused by ozone air pollution and smog, which usually increases during heat waves.
 Populations with low‐income are at greater risk of heat-related illnesses due to poor housing conditions, including lack of air conditioning and small living spaces, and inadequate resources to find alternative shelter during a heat wave.  People who spend their working hours outdoors are more prone to conditions such as heat exhaustion and heat stroke. They have higher exposures to ozone air pollution and heat stress, especially if work tasks involve heavy exertion.  People in poor health, including people with chronic conditions, disabilities, mobility constraints, and those taking certain medications, are vulnerable to extreme temperatures.

People with diabetes, physical impairments, and cognitive deficits are especially at-risk during heat waves.

Excessive heat events, or abrupt and dramatic temperature increases, are particularly dangerous and can result in above-average rates of mortality. From 2004 to 2018 the Centers for Disease Control and Prevention recorded 10,527 heat-related deaths in the United States, an average of 702 per year. These numbers include deaths where heat was the underlying cause and deaths where heat was a contributing cause.

In addition to vulnerable populations, pets and livestock are at risk to extreme heat. Extreme heat dries out vegetation in the City, creating greater risks from grass fires. Further, extreme heat, combined with low humidity and high winds, can cause power disruptions.

All of the City facilities in Table 9 can be impacted by extreme heat due to loss of power.

Climate Change and Heat
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34 Section 2.0: Hazard Identification and Risk Assessment County of Yolo According to the US EPA Climate change and heat interact in important ways. In many areas of the U.S., steadily increasing warming trends are intensifying already higher temperatures in heat island areas. This continued warming is expected to worsen heat islands in the future.As urban population densities increase and natural land areas decrease, heat islands will strengthen.The City is currently analyzing and looking to address and respond to these trends by taking actions to reduce their local heat islands. For example, strategies such as installing cool roofs and increasing tree canopy can lower heat island temperatures and lessen the exposure and sensitivity of City residents to climate change impacts, while also lowering the greenhouse gas emissions that cause climate change.

Population projections for the City show slower growth to 2035 as detailed in our most current general plan. Populations are anticipated to grow by only 2.4% between now and 2035, thus future population growth should not increase the potential impacts from this hazard on City assets. With respect to population patterns such as those associated with migration, density, or makeup of socially vulnerable populations the data shows that most socially vulnerable populations and disadvantaged communities are concentrated in the central and northern portion of the City.

Future Development
As the City shifts in demographics, more residents will become senior citizens. The residents of nursing homes and elder care facilities are especially vulnerable to extreme temperature events. It is encouraged that such facilities have emergency plans or backup power to address power failure during times of extreme heat. Low-income residents and homeless populations are also vulnerable.

Cooling centers for these populations should be utilized when necessary.

2.2.5 SEVERE WEATHER : EXTREME COLD AND FREEZE
Hazard/Problem Description
According to the National Weather Service (NWS) and the Western Regional Climate Center (WRCC), extreme cold often accompanies a winter storm or is left in its wake. Prolonged exposure to cold can cause frostbite or hypothermia and can be life-threatening. Infants and the elderly are most susceptible. Pipes may freeze and burst in homes or buildings that are poorly insulated or without heat. Freezing temperatures can cause significant damage to the agricultural industry.

Location and Extent
Extreme cold and freeze events occur on a regional basis. Extreme cold can occur in any location of the City. All portions of the City are at risk to extreme cold. While there is no scale (i.e. Richter, Enhanced Fujita) to measure the effects of freeze, temperature data for the County from the WRCC indicates that there are 8.3 days that fall below 32F. Freeze has a slow onset and can generally be predicted in advance for the City. Freeze events can last for hours (in a cold overnight), or for days to weeks at a time.

Past Occurrences
Disaster Declaration History
The City has had no past federal or state disaster declarations for extreme cold and freeze.

Planning Team Events
Members of the Planning Team recalled the following events:
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Likelihood of Future Occurrence
Highly Likely—Extreme cold and freeze are likely to continue to occur annually in the City. In a typical year, minimum temperatures fall below 32°F on 18.3 days in the City. This equates to a likelihood of future occurrences being considered highly likely.

VULNERABILITY ASSESSMENT
Vulnerability—Medium
Extreme cold and freeze events happen in the City each year. It can impact both populations and structures in the City of West Sacramento.

Impacts
Extreme cold and freeze events happen in the City each year. Extreme cold often accompanies a winter storm or is left in its wake. Prolonged exposure to cold can cause frostbite or hypothermia and can be life-threatening. Vulnerable populations to cold and freeze include:
 Homeless
 Infants and children under age five
 Elderly (65 and older)
 Individuals with disabilities
 Individuals dependent on medical equipment
 Individuals with impaired mobility
Of significant concern is the impact to populations with special needs such as the elderly, unhoused, and those requiring the use of medical equipment. The residents of nursing homes and elder care facilities are especially vulnerable to extreme temperature events. It is encouraged that such facilities have emergency plans or backup power to address power failure during times of extreme cold and freeze. In addition to vulnerable populations, pets and livestock are at risk to freeze and cold.

Impacts to the City as a result of extreme cold and freeze include damage to infrastructure, utility and power outages, road closures, traffic accidents, and interruption in business and school activities. Pipes may freeze and burst in homes or buildings that are poorly insulated or without heat. Freezing temperatures and ice can cause accidents and road closures and can cause significant damage to the agricultural industry. Extreme cold can affect agricultural products in the City. Freeze damages reduce the values of agricultural crops. Delays in emergency response services can also occur.

All of the City facilities in Table 9 can be impacted by extreme cold and freeze due to loss of power.

Climate Change and Extreme Cold and Freeze
Overall, climate change is expected to increase average temperatures, so the total number of days with cooler temperatures is expected to drop. However, climate change may increase the number of severe storms affecting the City. These intense storm systems could create severe winter weather conditions and more severe winter weather events in the area.

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36 Section 2.0: Hazard Identification and Risk Assessment County of Yolo Population projections for the City show slower growth to 2035 as detailed in our most current general plan. Populations are anticipated to grow by only 2.4% between now and 2035, thus future population growth should not increase the potential impacts from this hazard on City assets. With respect to population patterns such as those associated with migration, density, or makeup of socially vulnerable populations the data shows that most socially vulnerable populations and disadvantaged communities are concentrated in the central and northern portion of the City.

Future Development
Future development built to code should be able to withstand extreme cold and freeze. Pipes at risk of freezing should be mitigated be either burying or insulating them from freeze as new facilities are improved or added. Current City codes provide such provisions for new construction.

2.2.6 SEVERE WEATHER: HIGH WINDS
Hazard/Problem Description
This section includes a description and location and extent discussion for high winds.

High winds, as defined by the NWS glossary, are sustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or winds of 58 mph or greater for any duration. These winds may occur as part of a seasonal climate pattern or in relation to other severe weather events such as thunderstorms.

Location and Extent
The entire City of West Sacramento is subject to significant, non-tornadic (straight-line), winds.

Each area of the City is at risk to high winds. Magnitude of winds is measured often in speed and damages. These events are often part of a heavy rain and storm event, but can occur outside of storms. The speed of onset of winds can be short, but accurate weather prediction mechanisms often let the public know of upcoming events. Duration of winds in California is often short, ranging from minutes to hours. The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. Figure 2 shows the Beaufort wind scale.
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37 Section 2.0: Hazard Identification and Risk Assessment County of Yolo Source: National Weather Service
Figure 2: Beaufort Wind Scale
Figure 3 depicts wind zones for the United States. The map denotes that City of West Sacramento falls into Zone I, which is characterized by high winds of up to 130 mph. 145
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Figure 3: Wind Zones in the United States
Past Occurrences
Disaster Declaration History
There have been no past federal or state disaster declarations due to high winds.

Planning Team Events
The Planning Team for the City noted the following events since 2013:
 2019 – Damaging winds occurred in the City, multiple trees fell citywide  2023 – Damaging winds occurred in the City, causing extreme damage citywide Likelihood of Future Occurrence
Highly Likely –High winds are a well-documented seasonal occurrence that will continue to occur annually in the City.

VULNERABILITY ASSESSMENT
Vulnerability—Medium
The City is subject to potentially destructive straight-line winds. High winds are common throughout the area and can happen during most times of the entire year and outside of a severe 146
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39 Section 2.0: Hazard Identification and Risk Assessment County of Yolo storm event. Straight line winds are primarily a public safety and economic concern. Structures, and the citizens of the City are at risk to high winds.

Impacts
High winds, often accompanying severe storms and thunderstorms, can cause significant property damage, threaten public safety, and have adverse economic impacts from business closures and power loss.

Straight-line winds may also exacerbate existing weather conditions by increasing the effect on temperature and decreasing visibility due to the movement of particulate matters through the air, as in dust and snowstorms. The winds may also exacerbate fire conditions by drying out the ground cover, propelling embers around the region, and increasing fire severity. These winds may push automobiles off roads, damage roofs and structures, and cause secondary damage due to flying debris.

Impacts from straight line winds:
 Increased wildfire risk
 Increased chance of PSPS event
 Windblown weeds
 Downed trees
 Power line impacts and economic losses from power outages  Occasional building damage, primarily to roofs
City facilities in Table 9 that can be impacted by high winds and damages from trees due to loss of power are noted in the first column.

Particularly vulnerable populations in West Sacramento are the homeless, elderly, low income or non-English speaking populations. Power outages can be life threatening to those dependent on electricity for life support. These populations face isolation and exposure during severe weather high wind events and could suffer more secondary effects of the hazard. Those experiencing homelessness who lack adequate shelter may be directly exposed to high winds, leading to the destruction of temporary shelter, hypothermia or illness from this exposure.

Campers, mobile homes, barns, and sheds and their occupants are particularly vulnerable as windstorm events in the region can be sufficient in magnitude to overturn these lighter structures.

Livestock that may be contained in these structures may be injured or killed, causing economic harm to the rancher who owns both the structure and the livestock. Overhead power lines are vulnerable and account for the majority of historical damages. State highways can be vulnerable to high winds and dust storms, where high profile vehicles may be overturned by winds and lowered visibility can lead to multi-car accidents.

Climate Change and High Winds
Climate change is expected to cause an increase in intense rainfall, which is usually associated with strong storm systems. This means that City could see more intense storms in the coming years and decades. Such an increase may not affect all forms of severe weather and may not always be apparent. While average annual rainfall may increase or decrease slightly, the intensity of individual thunderstorm events is likely to increase during the 21st century. This may bring stronger thunderstorm winds.

Climate change impacts on winds are not well understood. Until recently, scientists had predicted rapid inland warming would weaken one of the primary drivers for Santa Ana winds and reduce 147
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Population projections for the City show slower growth to 2035 as detailed in our most current general plan. Populations are anticipated to grow by only 2.4% between now and 2035, thus future population growth should not increase the potential impacts from this hazard on City assets. With respect to population patterns such as those associated with migration, density, or makeup of socially vulnerable populations the data shows that most socially vulnerable populations and disadvantaged communities are concentrated in the central and northern portion of the City.

Future Development
Future development projects should consider windstorm hazards at the planning, engineering and architectural design stage with the goal of reducing vulnerability. Utilities at risk to high winds should be undergrounded as new facilities are improved or added. Development trends in the City are not expected to increase vulnerability to this hazard.

2.3 LOW SIGNIFICANCE HAZARDS
The following hazards were rated by the City planning team as low significance; however, it should be noted that the City takes these hazards seriously by planning, training and exercise activities.  Dam Failure
 Drought
 Earthquake
 Volcano
 Wildfire
Though considered hazards of concern in the County and in the State of California, earthquake and wildfire are not considered hazards of concern for the City and are not profiled in this Annex. The City is in an area with low to moderate seismicity. As such, earthquake is not considered a priority hazard. The City is located outside of any moderate or higher CAL FIRE Fire Hazard Severity Zones.

As such, wildfire is not considered a priority hazard.

2.4 VULNERABILITY ASSESSMENT
The vulnerability assessment analyzes the population, property, and other assets to risk to natural hazards. This section lists the City’s assets to risk to natural hazards, including critical facilities and infrastructure; historic, cultural, and natural resources; and economic assets. All facilities listed in this section are vulnerable to the hazards identified and all equally at risk to all of the hazards profiled for the City of West Sacramento. The populations within the City still remain vulnerable to all of the profiled hazards, the vulnerability has not changed.

2.4.1 ASSET INVENTORY
Table 9 lists the critical facilities and other community assets identified by representatives from the City of West Sacramento as important to protect in the event of a disaster. 148
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Fire Station #42 3585 Jefferson
Boulevard
Fire Station 1 Engine, 1 Brush truck
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Fire Station #43 1561 Harbor
Boulevard
Fire Station 1 Engine, 1 Brush truck
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Fire Station #44 905 Fremont
Street
Fire Station 1 Engine, 1 Brush truck
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
COWS Police
Department
550 Jefferson
Boulevard
Police Station
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
PW and Parks
Maintenance
Office
1951 S. River
Road
Office/Warehouse Sludge Dewatering
Building
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Parks
Maintenance
Building
1991 S. River
Road
Office Digester & Pump Room,
Caustic Feed Facility,
Electric Building,
Polymer Building,
Blower Building,
Sulfur/Chlorine
Building, Return Sludge
& Pump, Machine Shop
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Club West Teen
Center
1125 Riverbank
Road
Community Center
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
PSIP Water
Treatment
Plant
1380 Enterprise
Boulevard
Well Pump Building, Wells,
Chlorine Building
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Fire Station #41 132 Fifteenth St. Fire Station 2 Engines, 1 Squad, 1 Water Tender, 1 Boat
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
George Kristoff
Water
Treatment
Plant
400 N. Harbor
Boulevard
Lab/Mechanical
Building
Actiflo Basins, Chemical
Storage, Low-lift
Station, Filter Control
Building, Operations
and Chemical Feed
Building
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Bryte Pump
Station Building
1600 Citrus Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
South Pump
Station
1966 Park
Boulevard
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Coke Lift
Station
Coke
Street/Evergreen
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Water Well #22
& Storage
964 Oak Street Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Deerwood
Pump Station
Deerwood
St./Lakewood
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Storm Drain Lift
Station
Fifth Street and C
Street
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Iron Triangle
Pump Station
1021 Triangle
Court
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Sewer Pump
Station
3930 Industrial
Boulevard
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Jefferson Pump
Station -
Control Room
601 Jefferson
Boulevard
Pump Station Structure - No phone
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Weather
Hazards
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Southport
Water
Reservoir &
Pump
Linden Road at
Touchstone
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Lighthouse
Pump Station
310 B Street
Between 3rd and
4th Street
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Washington
Underpass
Storm Wat
Riske Lane/I-275 Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Linden Park 2601
Summerfield
Drive
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Touchstone
Park
2598
Independence
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Elkhorn Park 820 Cummins
Way
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Sam Combs
Park
205 Stone
Boulevard
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Memorial Park 18th St. and
Delaware
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Summerfield
Park
2950 Linden Rd. Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Meadowdale
Park
3625 W. Capitol
Avenue
Park Park Space - No phone
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Weather
Hazards
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Bryte Park 425 Todhunter
Avenue
Park Park Space - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
City Property 422 "C" Street Development
Property
Vacant Lot
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Central Water
Tank
Industrial &
Stone Water Tank Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Northeast
Water Tank Fourth & B Street Water Tank Structure - No phone Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Raley's Storm
Drain Pump
Station
2nd Street/F
Street
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Harbor
Boulevard
Storm Drain
Pump Station
Harbor
Boulevard/Rice
Avenue
Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
West
Sacramento
Civic Center
1110 West
Capitol Avenue
Government
Building
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Golden Gate
Sewer Lift
Station
3400 Golden
Gate Drive/Half
Moon Bay Circle Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Southport
Sewer Lift
Station
2500 Jefferson
Boulevard Sewer Lift Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Carlin Pump
Station
2930 Oates
Street Pump Station Structure - No phone
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Weather
Hazards
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Washington
Fire Station 317 3rd Street
Fire Station
(Vacant) Vacant Structure
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Bridgeway
Lakes
Boathouse and
Concession
Stand
3650 Southport
Parkway Community Center
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Bridgeway
Island Sewer
Pump Station
4099 Otis
Avenue
Sewer pump
station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards Fire Station 45
Lake Washington
Boulevard Fire Station
2 Ladder Trucks, 2
Engines, 1 Boat
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards City Property
520/540 Harbor
Boulevard Warehouse
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Allen Sewer
Pump Station
Allen/Linden
Road Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards Rec Center
2801 Jefferson
Boulevard Sports Center
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
In-Line Booster
Pump Station
2320
Washington
Boulevard Pump Station Structure - No phone
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Bryte Bend
Flouride
Facilities
400 N. Harbor
Boulevard Flouride Facility Structure - No phone
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Vulnerability
to Profiled
Hazards Name Address Function
Special
Equipment/Amenities
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Community
Center/Transit
Center
1075 West
Capitol Avenue Community Center
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Largo Sewer
Pump Station
4099 Southport
Park Pump station
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards Old Town Inn
826 West Capitol
Avenue
Development
Property Vacant Lot
Vulnerable to
Flooding, Levee
Failure, Severe
Weather
Hazards
Port of West
Sacramento -
Fire Training
Tower
2901 Industrial
Boulevard
Government
Training Facility Port Front Gate
Table 9: West Sacramento - Critical Facilities and other Community Assets

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SECTION 3.0 MITIGATION STRATEGY

3.1 CAPABILITY ASSESSMENT
Capabilities are the programs and polices currently in use to reduce hazard impacts or that could be used to implement hazard mitigation activities. The capability assessment is divided into five sections: regulatory, administrative and technical, fiscal, outreach and partnerships, and other mitigation efforts.

3.1.1 REGULATORY CAPABILITY
The legal and regulatory capabilities are shown in Table 10 which presents the existing ordinances and codes that affect the physical or built environment of the City. Examples of legal and/or regulatory capabilities can include: a jurisdiction’s building codes, zoning ordinances, subdivision ordnances, special purpose ordinances, growth management ordinances, site plan review, general plans, capital improvement plans, economic development plans, emergency response plans, and real estate disclosure plans.

Plans
Y/N
Year
Does the plan/program address hazards?
Does the plan identify projects to include in the
mitigation strategy?
Can the plan be used to implement mitigation actions?
General Plan Y Plan addresses hazards and identifies projects and mitigation actions for them. See the discussion below this table.

Capital Improvements Plan Y
Economic Development Plan Y The Planning and Environmental Review Division maintains the General Plan which has an Economic
Development Element, but many of the items identified
within the Element are the responsibility of the Office of Economic Development & Marketing. The Element does
not address hazards.

Local Emergency Operations Plan Y
2018
City Emergency Operations. This plan contains numerous
annexes for hazards, support and function.

Continuity of Operations Plan Y Continuity of Government Operations is noted in the City EOP.

Transportation Plan Y
Stormwater Management
Plan/Program
Y
Engineering Studies Y
Community Wildfire Protection Plan N There is no WUI threat to the City.

Other special plans (e.g., brownfields
redevelopment, disaster recovery,
coastal zone management, climate
change adaptation)
Y Climate Action Plan
This LHMP will be the 3rd LHMP annex to the Yolo County plan since 2013.
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Plans
Y/N
Year
Does the plan/program address hazards?
Does the plan identify projects to include in the
mitigation strategy?
Can the plan be used to implement mitigation actions?
Building Code, Permitting, and
Inspections Y/N Are codes adequately enforced?
Building Code Y Yes
Building Code Effectiveness Grading
Schedule (BCEGS) Score
Y
Fire department ISO rating: Y Rating: 1/9

Site plan review requirements Y The City operates a public counter for review of all development applications.

Land Use Planning and Ordinances
Zoning ordinance Y
Subdivision ordinance Y
Floodplain ordinance Y
Natural hazard specific ordinance
(stormwater)
Y
Flood insurance rate maps Y
Elevation Certificates Y Comprehensive record of elevation certificates Acquisition of land for open space
and public recreation uses
Y Land acquisition is on-gong for purposes of flood control, species conservation, open space preservation and
recreation.

Erosion or sediment control program Y
Other Y
How can these capabilities be expanded and improved to reduce risk? Begin new General Plan Update. Other areas identified for improvement include: Keeping the City GIS layers updated; keeping the Ordinances and Codes updated; Conduct cross-training between City Departments related to hazard mitigation; Encourage others to become certified floodplain managers – a certificate from the Association of State Floodplain Managers.

Table 10: West Sacramento Regulatory Mitigation Capabilities As indicated in the tables above, the City has several plans and programs that guide the City’s mitigation of development of hazard-prone areas. Starting with the West Sacramento General Plan, which is the most comprehensive of the County’s plans when it comes to mitigation, some of these are described in more detail below.

West Sacramento General Plan (2011 – many sections amended in 2022) A general plan is a legal document, required by state law, that serves as a community's "constitution" for land use and development. The plan must be a comprehensive, long-term document, detailing proposals for the "physical development of the county or city, and of any land outside its boundaries which in the planning agency's judgment bears relation to its planning" (Government Code §65300 et seq.). Time horizons vary, but the typical general plan looks 10 to 20 years into the future. The law specifically requires that the general plan address seven topics or 156
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"elements." These are land use, circulation (transportation), housing, conservation, open space, noise, and safety. The plan must analyze issues of importance to the community, set forth policies in text and diagrams for conservation and development, and outline specific programs for implementing these policies.

Safety Element
The purpose of the Safety Element is to identify and assess the potential for hazards to occur in West Sacramento and to formulate measures that provide adequate public protection. The City’s physical setting and the projected rate of urban expansion create a potential for the residents of the City to be greatly affected by several hazards. Hazards can result from the action of nature, as in the case of severe weather and floods; they can be human caused, as in the case of fires caused by arson or through carelessness.
2022 California Building Standards Code
The City of West Sacramento has fully adopted the California Building Standards. Title 15 of the West Sacramento Municipal Code includes amendments to the Building Standards to provide more specific requirements within the city. This includes an amendment stating that where the standards of the Code for required water supply for fire protection cannot be implemented, such as in rural areas where access to the public water supply is not available, a fire sprinkler system deemed acceptable by the fire chief may be installed. This does require connection to the public water supply.

Title 17 of the City of West Sacramento Municipal Code is the local code that refers to local mitigation and associated land use practices and policies.

Chapter 18.04 of the City’s Municipal Code establishes provisions to restrict, prohibit, or control development of uses that could increase or cause flood damage. This chapter of the Municipal Code also establishes the community development director as the floodplain administrator. The duty of the floodplain administrator is to review development permits for consistency with criteria in the City Municipal Code, and other State and Federal requirements.

Weed Abatement Standard
Every spring, the Fire Marshal identifies properties where overgrown weeds present a potential fire hazard, notifies property owners, and oversees the removal of such hazards by either the property owners or a public contractor. Property owners will be charged for any work done by the contractor. This requirement is solidified in City municipal code.

Other West Sacramento Plans/Studies/Programs
West Sacramento Emergency Operations Plan (April 2017)
The purpose of the City EOP and its Functional Annexes is to provide the basis for a coordinated response before, during and after a disaster incident affecting the City of West Sacramento.

This plan is the principal guide for the City’s response to, and management of real or potential emergencies and disasters occurring within its designated geographic boundaries. Specifically, this plan is intended to:
 Facilitate multi-jurisdictional and interagency coordination in emergency operations, particularly between local government, private sector, operational area (geographic county boundary), and state response levels, and appropriate federal agencies.  Serve as a city plan, a reference document, and when possible, may be used for pre-emergency planning in addition to emergency operations.
 To be utilized in coordination with applicable local, state and federal contingency plans.  Identify the components of an Emergency Management Organization (EMO), and establish associated protocols required to effectively respond to, manage and recover from major emergencies and/or disasters.
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 Establish the operational concepts and procedures associated with field response to emergencies, and EOC activities.
 Establish the organizational framework of the California Standardized Emergency Management System (SEMS), and the National Incident Management System (NIMS).

Flood Protection ‐ West Sacramento Area Flood Control Agency (WSAFCA/Agency) The West Sacramento Area Flood Control Agency (WSAFCA/Agency) was formed in 1994 through a Joint Exercise of Powers Agreement among the City of West Sacramento (City), Reclamation District 900, and Reclamation District 537. WSAFCA is composed of a 3-member Board and supported by City staff. WSAFCA is working toward achieving 200-year level flood protection for the West Sacramento community by 2025.

Due to catastrophic Hurricane Katrina, the United States Corps of Engineers (USACE) upped the standards for levees and WSAFCA responded by implementing the West Sacramento Levee Improvement Program (WSLIP). Under this program, the California Department Water of Resources (DWR) and WSAFCA completed three Early Implementation Projects (EIP): I Street Bridge (2008), CHP Academy (2011) and Rivers Project (2011). During the Southport EIP, the West Sacramento Project was authorized by Congress in the Water Infrastructure Improvements for the Nation Act (2016). The Southport Setback Levee Project became the first component of the federally authorized Project.

For the next increment, WSAFCA and DWR led design efforts for the Yolo Bypass East Levee due to insufficient Preconstruction Engineering and Design federal funding. The Agency is currently awaiting construction funding and new start designation.

WSAFCA is working quickly and efficiently to face the challenges of stricter flood control standards imposed by the State. These standards must be met by 2025 and WSAFCA is working together with their project partners to make the required improvements a reality.

The City and West Sacramento Area Flood Control Agency have created partnerships to leverage local funds with State and federal flood risk reduction funding. The majority of the cost for the levee improvement projects are funded by cost sharing agreements with our partnering agencies. 1‐foot freeboard requirement Ordinance
On March 3, 2021, the City of West Sacramento adopted Ordinance 21-3, which amended Chapter

18.20.010 of the Municipal Code: Title 18 to include a 1-foot freeboard requirement for mechanical items.

Participation in the National Flood Insurance Program (NFIP) Due to new, stricter standards imposed by the state and federal government, the Federal Emergency Management Agency (FEMA) is in the process of re-evaluating current Flood Insurance Rate Maps (FIRMs), which show the level of protection provided by all existing risk-reduction systems, in the country. Concurrently, the City of West Sacramento and the West Sacramento Area Flood Control Agency are working to build and strengthen in place levees to achieve 200-year flood protection for the West Sacramento community by 2025.

The City’s last adopted FIRM (1995) shows the vast majority of West Sacramento mapped in areas designated as Flood Zone X. In Flood Zone X there is not a statutory requirement for flood 158
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insurance. New construction and expansion of existing structures are allowed without being subject to onerous elevation and flood-proofing requirements.

If the planned levee improvements are not completed before West Sacramento is remapped, portions or all of West Sacramento's FIRM could be changed from Flood Zone X to something called a Special Flood Hazard Area (SFHA). Properties in a SFHA are required to have and maintain flood insurance. Additionally, new construction and major renovations of properties in a SFHA are required to be elevated and flood-proofed, which would likely severely limit property enhancement and greatly diminishing West Sacramento's economic development.

The City of West Sacramento participates in FEMA's National Flood Insurance Program (NFIP). This allows residents and property owners in the city to purchase federally subsidized flood insurance.

Chapter 18.04.010 of the City municipal code adopted the minimum floodplain management criteriathe and the methods of reducing flood losses are noted specifically in Chapter 18.04.040..

Currently, Flood insurance is not mandatory, but West Sacramento strongly recommends that all property owners purchase and maintain flood insurance at all times. Typically, flooding is NOT covered under your home or business owner's insurance policy.

The City implements and enforces our local floodplain management ordinance to regulate development through our building department, it should be noted that 99.9% of the city is NOT in a SFHA. The City Manager is designated to address the commitments of the NFIP and administer the program.

Any substantially damaged structures that must be rebuilt or expanded will require the improved structures to be built to current codes and standards in accordance with the City Floodplain ordinance and will go through City permitting and review process. The plans submitted will be reviewed for compliance as appropriate and shall be marked on the plans prior to building permit approval.

Emergency Management Program
The Office of Emergency Services (OES), a program within the Fire Department, is responsible for coordinating the planning for, response to, and recovery from all-hazards that may impact the City.

These duties include:
 Identification and assessment of potential hazards and threats  Development, implementation, and maintenance of appropriate contingency plans  Development and presentation of community and interagency preparedness programs  Coordination of interagency emergency management
 Maintenance and management of the county Emergency Operations Center (EOC) in support of emergency response operations

3.1.2 WEST SACRAMENTO ADMINISTRATIVE/TECHNICAL MITIGATION CAPABILITIES Table 11 identifies the City personnel responsible for activities related to mitigation and loss prevention in the City.

Administration Y/N
Describe capability
Is coordination effective?
Planning Commission Y
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Administration Y/N
Describe capability
Is coordination effective?
Mitigation Planning Committee Y Every five years hazards are reviewed by committee of officials from Countywide/Citywide departments including Planning, Stormwater, Transportation and more.

Mitigation is planned and recorded.

Maintenance programs to reduce
risk (e.g., tree trimming, clearing
drainage systems)
Y Drainages throughout the City are cleared during routine maintenance and inspected and cleared immediately
before storms.

Mutual aid agreements Y Multiple mutual aid agreements between city, county and state and local entities.

Other Evacuation Plan, Flood Response Annex, Flood Inundation Tool (ESRI)
Staff
Y/N
FT/PT
Is staffing adequate to enforce regulations?
Is staff trained on hazards and mitigation?
Is coordination between agencies and staff effective?
Chief Building Official Y
FT
Community Development; Building Official; Public Works
Floodplain Administrator Y
FT
Chief of Emergency Services Y
FT
The Office of Emergency Services shall be headed by the Fire Chief by the which position is designated as the Deputy Director of Emergency Services. There are two staff assigned to the office.

Community Planner Y
FT
Civil Engineer Y
FT
.

GIS Coordinator Y
FT
Other Y The City is well equipped with professional staff from numerous departments all playing a role, to different
degrees, in natural hazard mitigation.

Technical Y/N
Describe capability
Has capability been used to assess/mitigate risk in the past?
Emergency Alert System: Yolo-Alert Y Yolo County has a subscription based alerting system.

Wireless Emergency Alert (WEA) messages may be
disseminated with this system. This system is used
regularly for alerting, evacuation and other needs. The Office of Emergency Services is the primary Alert
Originator for Yolo County. The County currently uses the Everbridge system in which the City is a participant. The City has the ability to launch their own messages on the Countywide system.

Hazard data and information Y Documented through this LHMP, and the City’s EOP and annexes. Also as on file with County OES.
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Administration Y/N
Describe capability
Is coordination effective?
Grant writing Y
FT
Hazus analysis N Hazus runs are not an inhouse capability.

Other N
How can these capabilities be expanded and improved to reduce risk? Both the Climate Action plan and Environmental Justice Element of the General Plan call for enhanced communication plans to target the County’s diverse and sometimes disenfranchised communities.

Emergency communication and coordination could be enhanced by culturally competent and preestablished interpreters and translators who are already trained and imbedded with our communities and who will be received as trusted spokespeople.

Other areas identified for improvement include: Conducting emergency management exercises, Providing incident management training, Educate staff on the value and mindset of pre-disaster mitigation; Conduct evacuation planning, Continue planning for better public outreach and disaster warning systems; train and educate newer staff.

Table 11: West Sacramento County Administrative/Technical Mitigation Capabilities

3.1.3 WEST SACRAMENTO FISCAL MITIGATION CAPABILITIES
Table 12 identifies financial tools or resources that the City could potentially use to help fund mitigation activities.

Funding Resource
Access/
Eligibility
(Y/N)
Has the funding resource been used in
past and for what type of activities?
Could the resource be used to fund
future mitigation actions?
Capital improvements project funding Y
Authority to levy taxes for specific purposes Y
Fees for water, sewer, gas, or electric services Y
Impact fees for new development Y
Storm water utility fee Y
Incur debt through general obligation bonds
and/or special tax bonds
Y
Incur debt through private activities Y
Community Development Block Grant Y
Other federal funding programs Y FEMA mitigation grants have been used to mitigate flood risk through home
elevations and acquisitions. These
programs have been successful and will be
applied in the future when available.

State funding programs Y Cal DWR, Cal OES, Federal Funds Other
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Funding Resource
Access/
Eligibility
(Y/N)
Has the funding resource been used in
past and for what type of activities?
Could the resource be used to fund
future mitigation actions?
How can these capabilities be expanded and improved to reduce risk? The City can continue to update and maintain fee plans. Along with this, grants from the state such as Cal DWR, Cal OES, and federal sources like BRIC, HMGP, FMA, and PDM can be sought out as additional funding sources. The City can pursue funding districts that engage in mitigation to reduce risk for the community.

Cooperating in the multi-agency Silver Jackets program would also expand capabilities as partnerships are created and maintained.

Table 12: West Sacramento County Fiscal Mitigation Capabilities

3.1.4 WEST SACRAMENTO MITIGATION EDUCATION, OUTREACH, AND PARTNERSHIPS Table 13 identifies education and outreach programs and methods already in place that could be/or are used to implement mitigation activities and communicate hazard-related information.

Program/Organization Yes/No
Describe program/organization and
how relates to disaster resilience and
mitigation.

Could the program/organization help
implement future mitigation activities?
Local citizen groups or non-profit organizations
focused on environmental protection,
emergency preparedness, access and functional
needs populations, etc.

Yes
Ongoing public education or information
program (e.g., responsible water use, fire safety,
household preparedness, environmental
education)
Yes. Non-profit organizations and government
agencies Citywide do ongoing public
education for preparedness on all hazards
preparedness, flood and water use.

Natural disaster or safety related school
programs
Y West Sacramento works closely with the
Washington Unified School District on all
aspects of safety/emergency planning.

StormReady certification N
Firewise Communities certification N
Public-private partnership initiatives addressing
disaster-related issues
Y City Chamber of Commerce works closely
with City in promotion of information and
preparedness.

Other N
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Program/Organization Yes/No
Describe program/organization and
how relates to disaster resilience and
mitigation.

Could the program/organization help
implement future mitigation activities?
How can these capabilities be expanded and improved to reduce risk? Social media to connect with most vulnerable populations in various languages (some rural areas do not have broadband, many do not watch tv/cable to get messages).

Coordinate with public and mental health departments, service providers and organizations in providing information and utilizing their communication tools to connect with clients. 2-1-1 is an effective resource in some areas but not all. Need to make it more robust so people know to use it and that it has reliable and timely information.

Utilize neighborhood associations, schools, community watch groups to distribute information.

Utilize “NextDoor” site to convey information.

Other areas for improvement include: Conducting more emergency management exercises; Continue local hazard mapping efforts; Conduct more creative outreach efforts such as hazard warning signs – “if the levee breaks – water will be this high”.

Table 13: West Sacramento County Mitigation Education, Outreach, and Partnerships In times of emergency or disaster, agencies like the West Sacramento Fire and Police Departments will turn to citizen volunteers for assistance, especially in the first hours of an event. Both public safety agencies have been training citizens through their respective volunteer organizations such as the Community Emergency Response Team (CERT) or the Volunteers in Policing Services (VIPS).

Both programs train residents in basic disaster response skills. These programs can make a positive difference when citizens may need to be on their own temporarily.

The City works with the Bryte and Broderick Community Action Network (BBCAN) which implements and supports programs and projects to meet the aspirations of the diverse community by working with the City, non-profit and faith-based organizations, schools, and businesses toward sustaining a healthy, informed, and engaged community, in which planning and mitigating against future disasters is an area of focus.

3.1.5 OTHER MITIGATION EFFORTS
The City is pursuing multiple other mitigation efforts not captured in this plan. These include:

Climate Action Plan
The City of West Sacramento is currently preparing a Climate Action Plan (CAP) as an update to its original CAP. Climate action plans typically serve as a comprehensive road map that outlines the actions a city will take to reduce local greenhouse gas (GHG) emissions. West Sacramento’s CAP will also include a high-level analysis of climate change, its local impacts as well as opportunities to reduce local vulnerability.

3.2 FUTURE DEVELOPMENT TRENDS
Four 40 West
BlackPine received approval of a major map modification to the previously approved Alura tentative subdivision map (TSM) along with a new TSM to the west of the original one. The project as reconfigured will contain 106 single family homes and a 0.6acre park site. The project is currently under construction.
50 Waterfront Place
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Fairfield River Landing LLC is proposing to develop a 165-unit 8 story residential building at 50 Waterfront Place with underbuilding parking. The units are comprised of studio one and two bedroom units and include a business services area, fitness area, dog wash bike storage and balconies. Design review for this project was approved on April 11, 2023.

Bridge District Phase VI
On January 12, 2023, the Community Development Director approved the design of a 7-story market rate apartment building and mixed-use amenity building located at the northeast corner of Riverfront Street and Mill Street. The project would include 21 ground-floor townhome units which would front on Riverfront Street and Mill Street and 239 apartment units located above podium parking. The townhome units are envisioned to be live-work units. The mixed-use amenity building is located north of the residential building and includes retail space on the ground level, a fitness area and pool on the second level and office space on the remaining levels. The exterior building materials include stucco, fiber cement siding, metal panels, wood-look tile or siding, and board-formed concrete, which will allow for a diverse look to the project.

Block 17
The Planning Division received a design review application from Smart Growth Investors for an approximately 86 foot tall, 191,443 square foot commercial office, research, and development building at 1041 5th Street (southeast corner of Fifth and Mill Street). The project received design review approval on March 9, 2023.

Grand Street Apartments
The project applicant sought design review approval of an approximately 195 unit, five story market rate multifamily residential project at 840-850 Delta Lane. The project will include on site amenities consisting of a pool, rooftop deck and an at grade parking garage in the rear of the property. The main entrance and leasing office is proposed at the northwest corner of the project and all the residential units on the ground floor along Casey Street and Grand Street will have individual entrances and stoops fronting the public right of way. The exterior building materials include a dark grey brick veneer on the ground level. The project received design review approval on November 10, 2022.
851 Sacramento Avenue
On December 2, 2021 the Planning Commission found the grading permit for a permitted by right project at 851 Sacramento Avenue is consistent with the City's General Plan. The grading and rough site work is for a project that as currently planned includes approximately 445 residential units on five stories with ground floor live/work units along much of the frontage as well as a one-story retail building at the western side of the property. The live/work units are 45 feet deep on the ground floor with direct access to the sidewalk on Sacramento Avenue.

Kind
The project includes 148 multifamily units in two 3-story buildings and ground level parking with 39 spaces. The project is located at 429 F Street / 600 4th Street in the Washington neighborhood.

On November 19, 2020, the Planning Commission approved Washington Specific Plan minor deviations and design review for the project. Also on November 19th, the Zoning Administrator approved a parking reduction for the project, reducing the number of required parking spaces from 68 to 39. On January 20, 2021, the City Council approved a Development Agreement for the project.

On March 18, 2021, the Planning Commission approved enhancements for the parking area, which is one of the provisions required in the Development Agreement. The project was completed August of 2022.
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219‐221 5th Street Multifamily
The Planning Division received a design review application for an 18 unit, three story multifamily project at 219-221 5th Street. The project also requires minor deviation from the Washington Specific Plan for a reduced building setback along 5th Street. The project received Planning Commission approval on November 5, 2020.

River One
River One LLC has submitted an application for a tentative subdivision map, design review, and an extension of an existing Development Agreement. The project is located at the northeast corner of 3rd Street and Tower Bridge Gateway. The applications have been submitted to facilitate construction of a 7-story , 193 room hotel and a 7-story, 57 room condominium building. The project also includes an underground parking garage. The project received Planning Commission approval of the tentative subdivision map on November 21, 2019. The City Council approved the design of the project on December 11, 2019.
218 4th Street Townhomes
Kuchman Architects, on behalf of the owner Next Generation Capital, LLC, submitted an application for a 25 unit condominium row-house style project at 218 4th Street and 407 B Street. The project requires approval from the Planning Commission for a Vesting Tentative Subdivision Map, design review and minor deviations from the Washington Specific Plan. The project was approved by the Planning Commission on May 21, 2020.

Kierland Subdivision
Next Generation Capital submitted an application requesting approval of entitlements for a 16 unit small lot residential infill project called Kierland. The project is located in the Washington District at 317 and 331 F Street. The project was approved by the Planning Commission on August 20, 2020.

Washington Commons Cohousing
The Planning Division received an application for a 35-unit condominium cohousing community at 316-330 G Street. The project requires Planning Commission approval of a tentative condo map, Washington Specific Plan Minor Deviations for reduced setbacks and design review. The building is 4 stories with 35 parking spaces and community facilities on the ground floor and condo units on floors 2-4. The project was approved by the Planning Commission on May 21, 2020. Project is currently under construction.

West Gateway Place Phase II
Jamboree Housing submitted an application for a 60 unit affordable housing project at 801-810 Delta Lane. The project requires Design Review Administrator approval. The project would be comprised of two buildings combined by a central courtyard and walkway. The building is proposed to be ±45 feet tall and includes a mix of 27 one-bedroom units, 18 two-bedroom units, and 15 three-bedroom units. The exterior materials are white stucco and both light and dark colored batten siding. Parking will be provided on-site and in the public parking lot at 808 Tower Bridge Gateway. The design review was approved by the Interim Community Development Director on February 28, 2020. Project is currently under construction.

Kinect at Southport / Jefferson Village Apartments
The City received a design review application from American Capital Group in December of 2018 for a 292 unit multifamily project at 2301-2425 Jefferson Blvd. (APN 046-010-004-000, 046-010- 038-000, 046-010-051-000). The site is located along the east side of Jefferson Boulevard, south of 165
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Gateway Drive and north of Lake Washington Boulevard. The Clarksburg Branch Line Trail is on the eastern side of the site and a Reclamation District 900 canal on the south side. The application was reviewed for conformance with the zoning requirements in effect at that time which permitted multifamily by right on this property. After public noticing was completed, the project received design review approval determining it was in conformance with the Southport Framework Plan and Design Guidelines as well as the General Plan on October 2, 2019.

The applicant subsequently requested and received a Zoning Administrator minor modification to the project on May 6, 2020 for modifications to the site plan and unit count after public noticing was complete. The modification increased the number of units to 322 and condensed the number of buildings on the site from sixteen down to six such that the units are in fewer but larger buildings. Project is currently under construction.

CalSTRS Phase 2 Design Review
Ridge Capital, on behalf of CalSTRS, submitted a design review application for the second phase of their Headquarters at 200 Waterfront Place. The project includes five stories of office over a fivelevel parking garage and a stepped down frontage along 3rd Street that includes a lobby, café and childcare center. The property is subject to the River’s Landing: River Three Development Agreement which was approved in 2006. Per the development agreement, the design review is limited to the 3rd Street frontage and requires both Planning Commission and City Council approval. The project was approved by the City Council on May 15, 2019.

River Oaks Vesting Tentative Subdivision Map
Seecon Homes, Inc. submitted an application for a tentative subdivision map for 115 single family homes on 19.3 acres. The proposed project consists of two villages bisected by Village Parkway. The project is located on both sides of Village Parkway between Linden Road and Lake Washington Blvd. The project was approved by the Planning Commission on February 7, 2019.

West
CA Ventures submitted a design review application for a 285-unit, five story mixed use residential/retail building at 805 Riverfront Street (southeast corner of Ballpark Drive and Riverfront Street). The design includes retail along the entire length of the building’s Riverfront Street frontage and residential stoops along Ballpark Drive, State Street and a newly constructed access street. The exterior materials are primarily vinyl windows, smooth light-colored cement plaster, fiber board cement lap siding, brick and aluminum storefront windows along the ground floor Riverfront Street frontage, and steel balconies throughout the project for all residential units.

The applicant submitted two color board options, both with light colored cement plaster as the main color with different accent colors of blue, green and grey.

The project is adjacent to the Riverwalk trail and will provide additional landscaping and amenities along the trail. The landscape plans provided are meant to serve as initial concepts and specific details of the trail amenities and landscaping along the Riverwalk and street frontages are under development.

The project also requires Zoning Administrator minor deviations from the Bridge District Specific Plan. The project received Zoning Administrator and Design Review approval on October 16, 2018. Project is currently under construction.

Savoy
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Kuchman Architects submitted an application requesting approval of entitlements for a 25 unit small lot residential infill project called The Savoy. The project is located within the Washington District at 641 5th Street and consists of a mix of single family and duplex homes. The application was approved by Planning Commission on December 7, 2017.

Westgate Assisted Living
The Westgate assisted living project (formerly Summerplace) was approved in 2014 at 2305 Jefferson Blvd in Southport. The project required approval of a Conditional Use Permit, tentative map, environmental review and design review. The Planning Commission approved a time extension request for the Conditional Use Permit and Tentative Map on June 15, 2017, extending the CUP and TPM 5039 to have been extended to February 20, 2020.

Myer Ranch Subdivision
Update: Building permits issued for some lots and currently under construction.

Evergreen Communities submitted an application for a tentative subdivision map on a 15.7 acre site located easy of Jefferson Boulevard and south of Perkins Road in the Southport area of West Sacramento. The project site includes sixteen individual lots that were created as part of an old subdivision map that was recorded in 1913. The project will reconfigure the lots to create sixteen new lots, each 0.98 acre in size, for the development of ranchette single family homes. All of the lots will be served by public water and sewer. The Planning Commission approved the project on June 19, 2014.

3.3 MITIGATION GOALS AND OBJECTIVES
The information developed for the risk assessment was used as the primary basis for developing mitigation goals and objectives. Mitigation goals are defined as general guidelines explaining what each jurisdiction wants to achieve in terms of hazard and loss prevention.

Hazard Risk Prioritization

Mitigation Goals & Objectives

Mitigation Project Identification

Mitigation Project Implementation
Goal statements are typically long-range, policy-oriented statements representing jurisdiction-wide visions. Objectives are statements that detail how each jurisdiction’s goals will be achieved, and typically define strategies or implementation steps to attain identified goals. Other important inputs to the development of jurisdiction-level goals and objectives include performing reviews of existing local plans, policy documents, and regulations for consistency and complementary goals, as well as soliciting input from the public.

The following represents overarching strategic goals associated with the identification and eventual implementation of appropriate and meaningful hazard mitigation efforts in relation to prioritized hazards and threats confronting the City. The establishment of hazard mitigation goals represents both individual and collective strategies that have been mutually agreed upon by the City. These goals will be adopted by City as the guiding policy behind local hazard mitigation efforts, in 167
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conjunction with other associated principles. These priorities, goals and objectives have not changed from the last plan update in 2018.

The City of West Sacramento has adopted the hazard mitigation goals and objectives and also those listed in Section 4.0 Mitigation Strategy the Base Plan of the Yolo County Hazard Mitigation Plan:

Goal 1: Protection of life during and after the occurrence of disasters from identified hazards
Goal 2: Preventing loss of life and reducing the impact of damage where problems cannot be eliminated
Goal 3: Protection of emergency response capability
Goal 4:

Protection of developed property, homes and businesses, industry, educational opportunities and the cultural fabric by combining hazard loss reduction with the community’s environmental, social and economic needs Goal 5: Promoting public awareness of community hazards and mitigation measures and encouraging public participation in the planning objectives Goal 6: Preserving or restoring natural mitigation values such as flood plains Goal 7: Protection of natural resources and the environment

3.3.1 PLANNING PROCESS OBJECTIVES
The following objectives are meant to serve as a metric upon which the West Sacramento can be evaluated. Meeting these objectives assures the Multi Hazard Mitigation Plan as a functional document that identifies short-and long-term strategies, and describes each measure including:

Objective 1: Identification of individuals, agencies or organizations responsible for project implementation
Objective 2: Projecting a realistic and doable time frame for project implementation Objective 3: Explanation of how the project will be financed including the conditions for financing and implementation as information is available Objective 4: Identification of alternative measures, should financing not be available Objective 5: Maintain consistent support for the implementation of existing hazard mitigation planning goals and objectives for the operational area 168
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Objective 6: Base mitigation strategies on hazards as identified within the Yolo OA Risk Assessment
Objective 7:

Provide significant potential for the effective reduction of damage to public and/or private property, or to costs associated with local, state, and federal recovery from future potential impacts
Objective 8:

Establish and maintain a benchmark for identifying the most practical, cost effective, socially acceptable, and environmentally sound mitigation solution after consideration of available alternatives
Objective 9:

Address a repetitive problem, or one that has the potential to have a major impact on an area, reducing the potential for loss of life, loss of essential services and personal property, damage to critical facilities, economic loss, hardship or human suffering
Objective 10: Meet applicable permit requirements
Objective 11: Develop mitigation standards for development in hazardous areas Objective 12: Contribute to both the short-and long-term solution to the hazard vulnerability risk problem
Objective 13: Assuring the benefits of a mitigation measure is equal to or exceeds the cost of implementation
Objective 14: Have manageable maintenance and modification costs Objective 15:

When feasible, be designed to accomplish multiple objectives including improvement of life safety, damage reduction, restoration of essential services, protection of critical infrastructure, security of economic development, recovery, and environmental sustainability
Objective 16: Whenever feasible, use existing resources, agencies and programs to implement the project
Objective 17: Include regional hazard mitigation concerns and strategies

3.4 MITIGATION ACTIONS
The planning team for the City identified and prioritized the following mitigation actions based on the risk assessment. Background information as well as information on how the action will be implemented and administered, such as ideas for implementation, responsible office, partners, potential funding, estimated cost, and timeline are also described. 169
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The following mitigation actions in Table 14 were identified based on the hazard vulnerability and risk analysis for the City, some of these actions were carried over from the previous plan and some of the actions are new actions in the 2023 plan. Completed actions from the previous plan are noted in Table 15.
2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
MULTI‐HAZARD ACTIONS
Create an All
Hazards Public
Awareness and
Disaster
Preparedness
Education
Program
City of West
Sacramento
Public
Information
Officer/Emerge
ncy Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
”Annual
Implementat
ion, 5 Years”
Important
element of
CRS as part of
the NFIP
program
Integrate Local
Hazard
Mitigation Plan
into Safety
Element of
General Plan
City of West
Sacramento
Community
Development
Department
Director and
Planning
Department
Staff
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
”Annual
Implementat
ion, 5 years”
This is part of
element D3.c
plan
integration to
existing
planning
mechanisms

FLOODING HAZARD ACTIONS
Promote Flood
Insurance
(Cont’d
participation in
the NFIP)
City of West
Sacramento,
Floodplain
Manager
Existing
from last
plan
City General
Fund
”Annual
Implementat
ion, 5 years”
Continue to
send out
public
education
materials to
people living
within city
boundaries to
buy flood
insurance
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
Backup
Generators
City of West
Sacramento
Public Works
/RD 900, Flood
Division
Department
Heads and RD
900 General
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award.

Purchase
large
generators
for backup
power supply
to pump
stations and
other critical
facilities
Hardening of
Blacker Canal
Bank
City of West
Sacramento
Public
Works/RD 900,
Flood Division
Department
Heads and RD
900 General
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award
Construction
of blacker
canal banks
to prevent
flooding
SCADA
Implementation
City of West
Sacramento
Public
Works/RD 900,
Flood Division
Department
Heads and RD
900 General
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award.

Purchase
SCADA
remote
monitoring
equipment to
better
monitor
pump
stations
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
Hardening of
Bridgeway
Lakes Drainage
Canal
City of West
Sacramento
Public Works
/RD 900, Flood
Division
Department
Heads and RD
900 General
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award.

Construction
of Bridgeway
Lakes
Drainage
canal to
prevent
flooding
Storm Drain
Master Plan
City of West
Sacramento
Floodplain
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award.

Update the
City’s storm
drain master
plan
Stone Locke
Solution Project
City of West
Sacramento
Floodplain
Manager and
Public Works
Department
Head, RD 900,
Flood Division
Department
Heads and RD
900 General
Manager
New

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5–15-year
Project
Timeframe
dependent
upon grant
award.

Demolish the
existing Stone
Lockes which
separate the
deep-water
channel and
the
Sacramento
River and
rebuild a new
structure
RD 537 Pump
Station
Upgrades
City of West
Sacramento
and RD 900,
Flood Division
Department
Head and RD
900 General
Manager
Existing
from last
plan
$500,000, need

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award,
upgrade and
modernize
pump
stations in the
District
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
West Sac Goat
Program
City of West
Sacramento
Parks
Department
Head/RD900
General
Manager
New City General
Fund
”Annual
Implementat
ion, 5 years”
Grazing
program for
city open
space to
eliminate
new growth
after wet
winters

LEVEE FAILURE HAZARD ACTIONS
Yolo Bypass
East Levee
(YBEL) South
City of West
Sacramento
Public Works,
RD 900, Flood
Division
Department
Heads and RD
900 General
Manager
New

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Timeframe
dependent
upon grant
award, major
design and
construction
levee
improvement
project
Yolo Bypass
East Levee
(YBEL) North
City of West
Sacramento
Public Works,

WSAFCA, RD
900, Flood
Division
Department
Heads and RD
900 General
Manager
New

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
project
Timeframe
dependent
upon grant
award, major
design and
construction
levee
improvement
project
Sac River North
(1 and 2
segments/weir
to Rivas)
City of West
Sacramento
Public Works,

WSAFCA, RD
900, Flood
Division
Department
Heads and RD
900 General
Manager
New

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
project
Timeframe
dependent
upon grant
award, major
design and
construction
levee
improvement
project
SEVERE WEATHER (Heat) HAZARD ACTIONS
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
Emergency
Power
(Generators/tra
nsfer switch for
PW Corp yard
critical facilities
City of West
Sacramento,
Public Works
Facilities
Manager
Existing
from last
plan

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Need back up
power and
transfer
switch to PW
corporation
yard for
power
outages
during severe
weather
flooding
Heat
Preparedness
Campaign
City of West
Sacramento
Public
Information
Officer/
Emergency
Manager
Existing
from last
plan
City General
Fund
” Annual
Implementat
ion, 5 Years”
Specific
education to
public
including
socially
vulnerable
populations
and
disadvantage
d
communities
in heat
related injury
and illnesses
SEVERE WEATHER (Extreme Cold & Freeze) HAZARD ACTIONS
Emergency
Power
(Generators/tra
nsfer switch for
PW Corp yard
critical facilities
City of West
Sacramento
Public Works
Facilities
Manager
Existing
from last
plan
$200,000, need

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
Need back up
power and
transfer
switch to PW
corporation
yard for
power
outages
during severe
weather
flooding
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
Extreme Cold
and Freeze
Preparedness
Campaign
City of West
Sacramento
Public
Information
Officer/Emerge
ncy Manager
Existing
from last
plan
$50,000 City
General Fund
”Annual
Implementat
ion, 5 Years”
Specific
education to
public
including
socially
vulnerable
populations
and
disadvantage
d
communities
in extreme
cold and
freeze related
injury and
illnesses
SEVERE WEATHER (High Winds) HAZARD ACTIONS
City Tree
Trimming/Lim
bing for those
that are
identified as
hazardous to
people or
facilities due to
high winds
City of West
Sacramento
Parks and
Public Works
Department
Heads, Tree
Division staff,
PG&E staff
New

HMGP, PDM,
BRIC, Grant
funded sources
to fund project
5-year
Project
trees limbing
or removal for
dangerous
trees near City
Facilities that
could cause
injury or
death or
damages
those facilities
near City
infrastructure
such as water
and sewer
lines
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2023 MITIGATION ACTIONS (Previous Plan and New Plan Mitigation Actions) Mitigation
Project
Jurisdiction/
Responsible
Agency
New/
Existing or
Completed/
Deleted
Potential
Funding
Source
Timeframe
of
Completion
Comments/
Progress
High Winds
Preparedness
Campaign
City of West
Sacramento
Public
Information
Officer/Emerge
ncy Manager
Existing
from last
plan
City General
Fund
”Annual
Implementa
tion, 5
Years”
Specific
education to
public
including
socially
vulnerable
populations
and
disadvantaged
communities
in high wind
related injury
and illnesses
Table 14: West Sacramento Mitigation Actions

3.4.1 PROGRESS ON LOCAL MITIGATION EFFORTS
This plan has been created as a “living” document with input from the City Planning Team and with input from the public. Based on the planning meetings and the progress monitored, several mitigation actions were completed since the last planning cycle (2018 previous plan). Table 15 provides a snapshot of the progress made in local mitigation efforts for the City of West Sacramento.

Progress in Local Mitigation Efforts (Completed Actions Previous Plan) Project Description Comments
Community Warning System
Project
Procure an alert and warning
system to inform the public on
disasters and emergencies
Completed
Flood Response Plan Develop a Flood Response
Plan
Completed
Levee Improvement Projects
(various)
Several projects have been
completed such as the
Southport levee improvement
project along the Sacramento
River
Completed
Community Emergency
Response Training
Train community volunteers
in Disaster Management and
Community Response to
utilize in a
Disaster/Emergency
Completed
Sutter Avenue Reconstruction Completely reconstruct
existing roadway to mitigate
the flooding on Sutter Ave.

Completed
Table 15: West Sacramento Progress Towards Mitigation
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SECTION 4.0: PLAN REVIEW, EVALUATION AND

IMPLEMENTATION

4.1 PLAN ADOPTION
Upon submission to the California Office of Emergency Services (CalOES) for review, and subsequent approval by the Federal Emergency Management Agency (FEMA), the Yolo County Multi-jurisdictional Hazard Mitigation Plan will be presented to local government for formal adoption. As appropriate, the adopted plan and accompanying City of West Sacramento Annex will then be incorporated into the local plans such as the 2035 general plan update, the Hazards Section in the City Emergency Operations Plan and lastly this plan will be used to inform the Floods and Levee Failure, Severe Weather (heat, cold, high winds) Annexes and the Reclamation District 900 Emergency Response Plan and annexes.

4.2 PLAN MONITORING
The process of hazard mitigation does not end with the completion, approval, and adoption of the Yolo County Multijurisdictional Hazard Mitigation Plan and the City of West Sacramento Annex.

Within the lifespan of these documents (five years), local government along with community-based organizations, non-profit organizations, businesses, academia, neighboring jurisdictions and agencies who work with underserved populations and those that are socially vulnerable will ensure that the mitigation goals and strategies identified are monitored, that plan administration will continue under a collaborative and cooperative umbrella, and that the document itself will be properly maintained.

The City of West Sacramento is the lead coordination agency for hazard mitigation planning within the City, and will assist and support the ongoing collaborative efforts of Yolo County, through the established Hazard Mitigation Steering Committee. Specific plan maintenance activities by the City may include:
• Distribution of the HMP and Jurisdictional Annexes to all interested parties, including both written and digital formats.
• Monitoring of the City of West Sacramento mitigation project activities and dissemination of status reports.
• Generation of reports relative to plan status, project management, and revision updates to executive leadership.
• Preparations for eventual plan revision and updating.

4.3 PLAN EVALUATION
Upon approval and adoption by the City of West Sacramento, the prioritized mitigation strategies will be further developed for funding and implementation by the lead agencies. The plan describes the potential sources of Hazard Mitigation Strategy funding, and general procedures to obtain that funding.

The mitigation strategies represented and adopted within this plan are recommendations only and must be approved and funded in order to be implemented as official mitigation solutions.

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Sacramento to undertake project implementation based upon identified mitigation strategies, funding availability, and local need when it arises. The City of West Sacramento will meet with the Yolo County Office of Emergency Services Hazard Mitigation Steering Committee to evaluate the plan after each update meeting.

4.4 PLAN UPDATE
During the five-year update cycle, the City will participate with the Yolo County Office of Emergency Services at their tri-annual update meetings with the Hazard Mitigation Steering Committee and local stakeholders to discuss revisions to their 2023 plan. Additionally, in the next planning cycle the City will develop their own single jurisdictional plan. We will continue to work with and coordinate with the County on their LHMP all while developing our own moving forward. The City will focus on public participation particularly in the area of neighboring communities, representatives of business and academia, private organizations, non-profit organizations, and community based organizations that work directly to support the underserved and socially vulnerable. We have worked in this area for years but in the next planning cycle we will work to establish relationships with those agencies and organizations cited previously and work with them directly on the single jurisdictional planning effort.

4.5 CONTINUED PUBLIC INVOLVEMENT
The public will continue to be apprised of the plan’s progress through the City of West Sacramento website, including providing copies of annual progress reports on the website. Upon initiation of future update processes, a new public involvement strategy will be initiated based on guidance from a new planning team. This strategy will be based on the needs and capabilities of the planning partnership at the time of the update. At a minimum, this strategy will include the use of local media outlets within the planning area, including publishing an annual report that will be made available to the public. At the end of each year after the annual report is completed, the planning team will hold a public meeting to discuss the progress of the hazard mitigation action strategy, highlighting any new hazards or vulnerabilities, mitigation projects underway, or grant funding opportunities that are being pursued. We will also allow public feedback and comments through a survey to see what additional information the public would like to hear about, and how this process can be improved.

Socially Vulnerable and Underserved Populations
Disasters affect everyone and highlight the longstanding disparities and inequities experienced by people from racial and ethnic minority groups, people with low incomes, communities with less power and access to resources, and individuals who may have a disability and/or access and functional needs. To address this gap, we will convene a workgroup specific to these issues and emergency planning within the City.

These work groups will guide us to help provide the highest level of service to those with a disability and/or access and functional needs, as well as move beyond the traditional definitions of accessibility planning, and engage the whole-community. These work groups review and approve plans such as the Hazard Mitigation Plan (including updates) and Emergency Operations Plan, address gaps, and develop solutions to improve the life and safety of all residents within the City.

These work groups help set priorities and drive meaningful change to ensure our whole community is equitable in all phases of emergency management.
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Additional organizations and partnerships are continually added to these work groups, especially as the existing organizations invite other community organizations that they have partnered and worked with. We anticipate continued and increased engagement from these work groups on hazard mitigation.
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APPENDIX A: CITY ADOPTION DOCUMENTATION

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APPENDIX B: PUBLIC PARTICIPATION DOCUMENTATION
This screen shot is from the City Facebook account and was posted on May 10, 2023, on the social media site and the city website. This documents the invite to the City’s populations specifically.

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The next screen shot is of a Facebook post specific to the populations of our City reminding them to attend the public meeting on the LHMP Project. This post was on June 5, 2023.

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The next picture is of the sign-in sheet from the public meeting on June 5, 2023, in the City to our populations. This is also documented in the Yolo County Appendices. 183
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This document is a support annex to local
Emergency Operations Plans
2023

YOLO COUNTY

OPERATIONAL
AREA
HAZARD

MITIGATION PLAN
[VOLUME 1]
December 2023
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ACKNOWLEDGEMENTS
The Yolo County Multi-Jurisdictional Hazard Mitigation Plan update was made possible through the dedicated efforts of each participating jurisdiction, stakeholders, members of the public, and the Yolo County Office of Emergency Services. The development of this plan was only possible with the dedication and commitment of the Hazard Mitigation Plan Steering Committee, Planning Partners, and the Community. Participants included the following:

Jurisdictions:

County of Yolo
City of Davis
City of West Sacramento
City of Winters
City of Woodland
Tribal: Yocha DeHe Winton Nations
Special Districts, Partners & County Departments:

Dignity Woodland Memorial Hospital
Dunnigan Water District
Knights Landing Ridge Drainage District
In-home Support Services Advisory Committee
Pacific Gas and Electric (PG&E)
Madison and Knights Landing Community Service District
Reclamation District 108
Reclamation District 787 (River Garden Farms)
Sacramento River West Side Levee District
Sutter Davis Hospital
University of California, Davis
Yolo County Administrators Office
Yolo County Commission on Aging and Adult Services
Yolo County Community Works/Public Works
Yolo County Flood Control and Water Conservation District Yolo County Housing Authority
Yolo County Health and Human Service Agency
Yolo County Sheriff's Office
The citizens of Yolo County are commended for their participation in the outreach strategy. This outreach success will set the course for the successful implementation of this plan during the next performance period.
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EXECUTIVE SUMMARY
Yolo County’s 2023 Hazard Mitigation Plan update defines measures to reduce risks from natural disasters in the Yolo County planning area, including unincorporated areas, incorporated cities, and special purpose districts. The plan updates the County’s previous plan, the 2018 Yolo County Multi-Hazard Mitigation Plan. It complies with federal and state hazard mitigation planning requirements to establish eligibility for funding under Federal Emergency Management Agency (FEMA) grant programs for all jurisdictions that participated as planning partners.

Yolo County is vulnerable to a wide range of natural and manmade hazards. These hazards can threaten the life and safety of residents and visitors, potentially damage or destroy public and private property and disrupt the local economy and overall quality of life. While the threats from hazard events may never be fully eliminated, there is much we can do to lessen their potential impact on our communities. By minimizing the damaging effects of hazards upon our built environment, we can prevent such events from resulting in disasters. Hazard mitigation is the concept and practice of reducing risks to people and property from known hazards. Hazard mitigation uses long-term and short-term policies, programs, projects, and other activities to alleviate the death, injury, and property damage that can result from a disaster. Yolo County and a partnership of local governments within the County have developed a hazard mitigation plan to reduce risks from natural disasters in the Yolo County Operational Area—defined as the unincorporated county and incorporated jurisdictions within the geographical boundaries of the County. The plan complies with federal and state hazard mitigation planning requirements to establish eligibility for funding under FEMA grant programs.

GUIDING PRINCIPAL
The following guiding principle was created and agreed upon by the participants to represent the overall intended outcome of the Plan:

Reduce the risk to life and property in Yolo County efficiently and effectively by decreasing the long-term vulnerability from hazards through coordinated planning, partnerships, capacity building, and effective risk reduction measures.

PLAN DOCUMENT DEVELOPMENT

ORGANIZATION
A core Yolo County staff planning team was assembled to facilitate this plan update. A planning partnership was formed by engaging eligible local governments and ensuring they understood 186
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their compliance expectations under the updated plan. A steering committee was assembled to oversee the plan update, consisting of both governmental and nongovernmental stakeholders within the planning area. Coordination with other local, state, and federal agencies involved in hazard mitigation occurred throughout the plan update process. Organization efforts included reviewing the County’s 2023 hazard mitigation plan, the California statewide hazard mitigation plan, and existing programs that may support hazard mitigation actions. This plan was prepared in coordination with FEMA and the California Office of Emergency Services (Cal OES) to ensure it meets all applicable federal and state requirements.

This plan has been set up in two volumes so that jurisdiction-specific elements can easily be distinguished from those that apply to the whole County. Volume 1 includes the federally required details of a hazard mitigation plan for all participating jurisdictions. This describes the planning process, public involvement strategy, hazard risk assessments, countywide mitigation actions, and a plan maintenance strategy. Since this is a multi-jurisdictional plan, Volume 1 addresses the entirety of Yolo County, which includes all participating jurisdictions and the entire geographic boundary. Volume 2 contains the Jurisdictional Annexes, which detail the hazard mitigation planning elements specific to each participating jurisdiction in the Yolo County Joint Hazard Mitigation Plan Update and includes all federally required jurisdictionspecific features for each participating jurisdiction.

Each annex is not intended to be a standalone document but annexes to, supplements, and incorporates by reference the information contained in Volume 1 of the Plan. All information in Volume 1, including the planning process and other procedural requirements and planning elements, apply to and were met by each participating jurisdiction. The Annexes provide additional information specific to each participating jurisdiction, focusing on providing further details on the risk assessment and mitigation strategy.

All participating jurisdictions will adopt Volume 1 and their jurisdiction-specific annex in Volume 2.

PUBLIC OUTREACH
The planning team implemented a multi-media public involvement strategy utilizing the outreach capabilities of the planning partnership that the Steering Committee approved. The process included in-person public meetings, virtual public meetings, a community hazard mitigation awareness survey, a project website, and multiple print, web-based, and social media releases.

Additionally, the Steering Committee comprised community-based organizations, non-profit organizations, and other agencies that helped amplify public outreach efforts to their networks.

ADOPTION
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Once pre-adoption approval has been granted by the California Governor’s Office of Emergency Services and FEMA, each planning partner will individually adopt the updated plan. Each partner has up to one year from FEMA approval to adopt the plan.

RISK ASSESSMENT
Risk assessment measures the potential loss of life resulting from natural hazards, personal injury, economic injury, and property damage to determine the vulnerability of people, buildings, infrastructure, and the environment to natural hazards. The Steering Committee used the risk assessment to rank risks and gauge the potential impacts of each threat of concern in the Operational Area. The risk assessment included the following:
• Hazard identification and profiling
• Assessment of the impacts on physical, social, environmental, and economic assets • Identification of areas of vulnerability
• Estimates of the cost of potential damage
The degree of Risk is based on the likelihood of occurrence and severity of the damage using a basic scale of High, Moderate, Possible, Negligible. Based on the risk assessment, hazards were ranked for the risk they pose to the overall Operational Area.

Table ES-1: Hazard Risk Assessment Ranking
Ranking Hazard Risk Score Degree of Risk
1 Levee Failure 12.0 High
2 Wildfire 9.75 High
3 Drought 8.81 Moderate
4 Severe Weather: Extreme Heat 7.75 Moderate
5 Flooding 7.13 Moderate
6 Severe Weather: High Wind 6.5 Possible
7 Dam Failure 6.25 Possible
8 Earthquake 5.5 Possible
9 Severe Weather: Freeze 4.56 Possible
10 Land Subsidence 4.25 Possible
11 Severe Weather: Fog 0.26 Negligible
12 Severe Weather: Tornado 0.13 Negligible
13 Landslide 0 Negligible
14 Volcano 0 Negligible

MITIGATION STRATEGY
The 2018 mitigation actions were reviewed, changed, updated, and revised to reflect new MultiJurisdictional Hazard Mitigation Plan (MJHMP) priorities. During this update process, each of the 2018 mitigation actions was examined for relevancy and the potential for future implementation and then evaluated for potential follow-up. Some mitigation actions developed 188
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during the 2018 Plan effort are an inherent part of the update process or needed to be more detailed for implementation at a local jurisdiction level and, thus were not included in this update. The County has made significant changes to other 2018 Mitigation Actions because of the updated risk assessment and implementation strategy to include more detail or to update based on current mitigation practices. During this MJHMP update process, the Steering Committee also decided to add countywide mitigation actions. These countywide actions were based on the highest-rated hazards of concern in the identified problem statements across the operational area. They were included to provide a high-level countywide mitigation strategy. 189
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TABLE OF CONTENTS
Acknowledgements....................................................................................................................................... 2 Executive Summary ...................................................................................................................................... 3 Guiding Principal ...................................................................................................................................... 3 Plan Document Development ................................................................................................................... 3 Organization.......................................................................................................................................... 3 Public Outreach......................................................................................................................................... 4 Adoption ................................................................................................................................................... 4 Risk Assessment ....................................................................................................................................... 5 Mitigation Strategy ................................................................................................................................... 5 Table of Contents.......................................................................................................................................... 7 Acronyms and Abbreviations ..................................................................................................................... 10 Jurisdictional Annexes................................................................................................................................ 13 Section 1.0: Introduction............................................................................................................................. 14

1.1 Purpose............................................................................................................................................ 14

1.2 Scope............................................................................................................................................... 14

1.3 Regulatory Framework ................................................................................................................... 15

1.4 History and Overview ..................................................................................................................... 15

1.4.1 Demographics.......................................................................................................................... 22

1.4.2 Community Lifelines and Infrastructure.................................................................................. 24

1.4.3 Natural, Historical, and Cultural Resources............................................................................. 27

1.4.4 Economics................................................................................................................................ 35

1.5 Existing Authorities, Policies, Programs, and Resources ............................................................... 38

1.6 New Items for the 2023 Update ...................................................................................................... 40

1.6.1 What’s New in the Plan Update................................................................................................. 42

1.6.2 Climate Change........................................................................................................................ 43

1.6.3 Continued Participation in the Community Rating System Program ...................................... 44

1.7 Hazard Mitigation Principles.......................................................................................................... 44

1.8 Plan Organization and Structure ..................................................................................................... 44 Section 2.0: Planning Process..................................................................................................................... 46

2.1 Participating Jurisdictions and Organizations................................................................................. 49

2.2 Steering Committee......................................................................................................................... 51

2.2.1 Steering Committee Tasks....................................................................................................... 54

2.2.2 Steering Committee Future Tasks............................................................................................ 55

2.3 Stakeholder Engagement................................................................................................................. 55

2.4 Public Involvement ......................................................................................................................... 56

2.4.1 Integration of Public Input....................................................................................................... 57

2.4.2 Continued Public Involvement ................................................................................................ 58

2.5 Incorporation of 2018 HMP into Existing Plans............................................................................. 58 Section 3.0: Hazard Identification and Risk Assessment............................................................................ 60 190
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3.1 Hazard Identification....................................................................................................................... 60

3.1.1 Hazard Prioritization and Risk Ranking .................................................................................... 61

3.1.2 Results........................................................................................................................................ 63

3.1.3 Disaster Declaration History.................................................................................................... 67

3.2 Hazard Profiles and Vulnerability Assessment............................................................................... 69

3.2.1 Hazard Profiles .......................................................................................................................... 69

3.2.2 Vulnerability Assessment .......................................................................................................... 70

3.2.3 Power Shortage/Failure.............................................................................................................. 71

3.2.4 Climate Change.......................................................................................................................... 76

3.2.5 Agricultural Hazards.................................................................................................................. 82

3.3 Hazard Risk Assessment – Natural Hazards................................................................................... 91

3.3.1 Severe Weather - General ........................................................................................................ 91

3.4 Dam Failure .............................................................................................................................. 128

3.5 Drought..................................................................................................................................... 138

3.7 Earthquake ................................................................................................................................ 152

3.8 Flooding.................................................................................................................................... 171

3.8.1 Loss Estimates ......................................................................................................................... 212

3.8.2 Participation in the National Flood Insurance Program (NFIP)............................................... 212

3.8.3 Repetitive Loss and Severe Repetitive Loss Properties........................................................... 217

3.9 Land Subsidence ....................................................................................................................... 220

3.10 Levee Failure .......................................................................................................................... 227

3.11 Wildfire..................................................................................................................................... 255

3.12 Yolo County Operational-Area Problem Statements.................................................................... 273 Section 4.0 Capability Assessment ........................................................................................................... 277

4.1 Incorporation of Existing Plans, Studies, Reports, and Technical information .............................. 277

4.1.1 Federal ..................................................................................................................................... 278

4.1.2 State ......................................................................................................................................... 285

4.1.3 Local Capability Assessment................................................................................................... 292 Planning and Regulatory Capability ................................................................................................. 292

4.2 Expanding Capabilities................................................................................................................... 294 Expanding Planning and Regulatory Capabilities ............................................................................ 294 Expanding Code, Ordinance, or Requirements Capabilities............................................................. 295 Expanding Administrative and Technical Capabilities..................................................................... 295 Expanding Fiscal Capabilities........................................................................................................... 295 Expanding Education and Outreach Capabilities.............................................................................. 295 Section 5.0 Mitigation Strategy ................................................................................................................ 297

5.1 Mission Statement......................................................................................................................... 298

5.2 Guiding Principles......................................................................................................................... 298

5.3 Mitigation Goals ........................................................................................................................... 298

5.4 Mitigation Objectives...................................................................................................................... 300

5.5 Mitigation Alternatives................................................................................................................... 301

5.6 Yolo County Operational-Area Mitigation Action Plan ................................................................. 305

5.6.1 Previous Mitigation Actions.................................................................................................... 306 191
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5.6.2 Mitigation Action Success Stories........................................................................................... 306

5.7 Mitigation Action Prioritization...................................................................................................... 324 Section 6.0: Plan Adoption, Maintenance, And Evaluation...................................................................... 328

6.1 Future Development Trends............................................................................................................ 328

6.2 Plan Adoption ............................................................................................................................... 331

6.3 Plan Implementation and Monitoring ............................................................................................. 331 Annual Progress Report - Monitoring............................................................................................... 331 Grant Monitoring and Evaluation ..................................................................................................... 333

6.4 Plan Evaluation ............................................................................................................................... 333

6.5 Plan Maintenance.......................................................................................................................... 333

6.6 Plan Update ..................................................................................................................................... 335

6.7 Continuing Public Involvement ...................................................................................................... 336

6.8 Incorporation into Other Planning Mechanisms............................................................................. 337 Appendix A: Planning Documentation..................................................................................................... 341 Letter of Interest (LOI) Template ......................................................................................................... 342 Planning Partner Expectations.............................................................................................................. 343 2018 Initial HMP Meetings................................................................................................................... 348 2018 First Public Meeting..................................................................................................................... 352 2018 Steering Committee Meeting ....................................................................................................... 358 2019 Planning Meetings........................................................................................................................ 358 2019 Steering Committee Meetings...................................................................................................... 361 2023 Kickoff Planning Meetings.......................................................................................................... 361 ............................................................................................................................................................... 372 2023 Planning Meeting ......................................................................................................................... 381 Appendix B: Old Mitigation Project List.................................................................................................. 400 Appendix C: Adoption Letters.................................................................................................................. 405 192
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ACRONYMS AND ABBREVIATIONS
ADA Americans with Disability Act
AEL Annualized Earthquake Losses
AELR Annualized Earthquake Loss Ratio
APEL Annualized Earthquake Percent Losses
APG Adaptation Planning Guide
BAM Best Available Maps
BNSF Burlington Northern and Santa Fe Railroad
BRBNACP Blue Ridge Berryessa Natural Area Conservation Partnership BRIC Building Resilient Infrastructure and Communities Grant Program CAISO California Independent System Operator
Cal OES California Office of Emergency Services
CAAP Climate Action and Adaptation Plan
CCAP Cache Creek Area Plan
CCR California Code of Regulations
CCRMP Cache Creek Resources Management Plan
CDAA California Disaster Assistance Act
CDBG-DR Community Development Block Grant – Disaster Resilience CEQA California Environmental Quality Act
CFR Code of Federal Regulations
CGS California Geological Survey
CLD California Levee Database
CNRA California Natural Resource Agency
COOP Continuity of Operations Plan
CPUC California Public Utilities Commission
CRS Community Rating System
CSA County Service Area
CVFPB Central Valley Flood Protection Board
CWA Clean Water Act
DFG California Department of Fish and Game
DMA Disaster Mitigation Act
DPA Direct Protection Area
DPC Delta Protection Commission
DSOD Division of Safety of Dams
DVBRTF Delta Vision Blue Ribbon Task Force
DWR California Division of Water Resources
DWS Division of Water Safety
ESA Endangered Species Act
EWP Emergency Watershed Protection
FEMA Federal Emergency Management Agency
FIRM Flood Insurance Rate Map
FIS Flood Insurance Study
FMA Flood Mitigation Assistance Program
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11 Acronyms and Abbreviations Yolo County Operational Area FMMP Farmland Mapping and Monitoring Program
GHG Greenhouse Gases
GIS Geographic Information Systems
HMGP FEMA Hazard Mitigation Grant Program
IPCC International Panel on Climate Change
IT Information and Technology
KLRC Knights Landing Ridge Cut
KLRDD Knights Landing Ridge Drainage District
LNU Lake Napa Unit
LOMA Letter of Map Amendment
LOMR Letter of Map Revision
LURMP Land Use and Resource Management Plan
MJHMP Multi-Jurisdictional Hazard Mitigation Plan
MMI Modified Mercalli Intensity
MT Metric Ton
MW Megawatts
NCDC National Climatic Data Center
NDIS National Integrated Drought Information System
NEPA National Environmental Policy Act
NFIP National Flood Insurance Program
NID National Inventory of Dams
NIMS National Incident Management System
NOAA National Oceanic and Atmospheric Administration
NRCS National Resources Conservation Service
NWS National Weather Service
NWL TAC Natural and Working Lands Technical Advisory Committee OES Office of Emergency Services
OPR Office of Planning and Research
PG&E Pacific General and Electric Company
PL Public Law
PSPS Public Safety Power Shutoff
PST Pacific Standard Time
RAWS Remote Automated Weather Station
RD Reclamation District
SAC-SJ Sacramento San-Joaquin
SBC Small Business Administration
SCU Santa Clara Unit
SEMS Standardized Emergency Management System
SFHA Special Flood Hazard Area
SGMA Sustainable Groundwater Management Act
SHMP State Hazard Mitigation Plan
SMY Sacramento Maintenance Yard
SRA State Responsibility Area
SRWSLD Sacramento River West Side Levee District
UBC State of California Uniformed Building Code
UCERF Uniform California Earthquake Rupture Forecast
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USACE United States Army Corps of Engineers
USDA United States Department of Agriculture
VHFSZ Very High Fire Severity Zone
WFPI Wind-enhanced Fire Potential Index
WUI Wildland Urban Interface
YCCAC Yolo County Climate Action Commission
YCH Yolo County Housing Authority
YOA Yolo Operational Area
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JURISDICTIONAL ANNEXES
While this Volume, Volume 1, addresses the entire geographic area of Yolo County and all participating Jurisdictions holistically, Volume 2 of the Yolo County Multi-Jurisdictional Hazard Mitigation Plan Update contains the Jurisdictional Annexes for each participating Jurisdiction.

These participating Jurisdictions remain as planning partners and have completed their intent to submit a Jurisdictional annex as they complete them.
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The 2023 Yolo County Operational Area Multi-Jurisdictional Hazard Mitigation Plan (MJHMP) has been prepared with the intent of establishing an inter-jurisdictional process for the development and implementation of effective hazard mitigation strategies in association with identified hazards that pose real or potential threats to the Yolo Operational Area (YOA).

1.1 PURPOSE
Yolo County, four incorporated communities, Unincorporated Yolo County including all Special Districts, and The Yocha Dehe Wintun Nation prepared this Multi-jurisdictional HMP Update to the Federal Emergency Management Agency (FEMA) approved 2018 Yolo County MJHMP.

The purpose of this plan is to guide and integrate hazard mitigation planning into the activities and programs of local jurisdictions, special districts, and all sectors, to the extent possible, in order to better protect the people and property of Yolo County from the effects of natural hazards. This MJHMP Update demonstrates Yolo County’s commitment to reducing risks from hazards and serves as a tool to help decision makers direct mitigation activities and resources.

This MJHMP Update was also developed to ensure Yolo County and participating jurisdictions’ continued eligibility for certain federal disaster assistance: specifically, the FEMA Hazard Mitigation Grant Program (HMGP), Building Resilient Infrastructure and Communities (BRIC), and the Flood Mitigation Assistance Program (FMA).

1.2 SCOPE
This Yolo County 2023 MJHMP Update is a multi-jurisdictional plan that geographically covers the entire area within Yolo County’s jurisdictional boundaries (referred to as the Operational Area). The following jurisdictions participated in the planning process and are seeking FEMA approval of the HMP Update:
 The County of Yolo
 The City of Davis
o University of California, Davis
 The City of West Sacramento
 The City of Winters
 The City of Woodland
 The Yocha Dehe Wintun Nation
 Reclamation District 108 (including Sacramento West Side Levee District, Knights Landing Ridge Drainage District, Dunnigan Water District)  Reclamation District 787
 Yolo County Flood Control & Water Conservation District The plan identifies and evaluates specific local hazard mitigation strategies to be considered by the YOA and associated planning support for those strategies developed by its political subdivisions, agencies, special districts, and organizations. The plan describes strategies that 197
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1.3 REGULATORY FRAMEWORK
Mitigation Act of 2000 (Public Law 106-390), is to reduce the loss of life and property, human suffering, economic disruption, and disaster assistance costs resulting from natural disasters. The Disaster Mitigation Act (DMA 2000) shifted the federal emphasis toward planning for disasters before they occur and requires proactive pre-disaster planning as a condition of receiving certain federal financial assistance under the Stafford Act. Regulations developed to fulfill the Disaster Mitigation Act’s requirements are included in Title 44 of the Code of Federal Regulations (44 CFR). The Disaster Mitigation Act encourages state and local authorities to work together on pre-disaster planning and to assist local governments in accurately assessing mitigation needs, resulting in faster allocation of funding and more cost-effective risk reduction projects under FEMA’s Hazard Mitigation Assistance program. The Disaster Mitigation Act requires the plan be updated every five years to remain in compliance with federal mitigation grant conditions.

Grant compliance is contingent on meeting the plan update requirements that are contained in 44 CFR. Jurisdictions that allow a plan to expire are not able to pursue funding under the Stafford Act for which a current hazard mitigation plan is a prerequisite. Federal regulations require a plan for monitoring, evaluating, and updating hazard mitigation plans. The plan update process provides an opportunity to reevaluate recommendations, monitor the impacts of actions that have been accomplished, and determine if there is a need to change the focus of mitigation strategies over time.

1.4 HISTORY AND OVERVIEW
Yolo County was one of the original 27 counties created when California became a State in 1850. "Yolo" is derived from the native Poewin Indian word "yo-loy" meaning "abounding in the rushes". Other historians believe it to be the name of the Indian chief, Yodo, or the Indian village of Yodoi.

The first recorded contact with Westerners occurred in the late 1820s. These included Spanish missionaries as well as trappers and hunters who could be found along the banks of "Cache Creek" - named by French-Canadian trappers. The first white settler was William Gordon who received a land grant from the Mexican government in 1842 and began planting wheat and other crops.

The towns of Yolo County were out growths of native villages along waterways. The county’s first town, Fremont, was founded in 1849 along the confluence of the Sacramento and Feather Rivers and became the first county seat. Knights Landing, Washington, Cacheville (later called Yolo), Clarksburg, Winters, Esparto, Capay, Guinda, and Davisville (Davis) were all built near waterways. Davisville had the added advantage of being on the path of the newly constructed 198
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In 1906, to further emphasize agriculture's role in Yolo County, the University of California chose a 780-acre farm belonging to Jerome Davis for establishment of a university farm to serve as part of the College of Agriculture. The Davis farm has since become a separate campus of the University and has received world-wide fame for its research and educational work.

In 1987, West Sacramento became Yolo County's fourth incorporated city. It is home to the Port of West Sacramento and Sacramento Deep Water Channel, providing worldwide access to Yolo County's agricultural and manufacturing production.

Yolo County is in the rich agricultural regions of California’s Central Valley and the Sacramento River Delta. It is directly west of Sacramento, the State Capital of California, and northeast of the Bay Area counties of Solano and Napa (see Figure 1-1). The eastern two-thirds of the county consists of flat plains and basins. The western third is largely composed of rolling terraces and steep uplands used for dry-farmed grain and range. The elevation ranges from slightly below sea level near the Sacramento River around Clarksburg to 3,000 feet along the ridge of the western mountains. Putah Creek descends from Lake Berryessa offering fishing and camping opportunities and drifts through the arboretum of the University of California at Davis. Cache Creek, flowing from Clear Lake, offers class II-III rapids for white water rafting and kayaking.

Bordering counties are as follows:
• Northeast: Sutter County
• Southeast: Sacramento County
• South: Solano County
• Southwest: Napa County
• North: Colusa County
• Northwest: Lake County
The Central Valley climate can be described as Mediterranean. During the hot, dry, sunny summers, temperatures can exceed 100 degrees F on some days, however more often summer temperatures are in the low 90s. The Sacramento River Delta breeze usually cools overnight temperatures into the 60s. Spring and fall has some of the most pleasant weather in the state.

The rainy season typically runs from late fall through early spring and fog season last from November through March. Average annual rainfall is about 17 inches. 199
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17 Section 1: Introduction Yolo County Operational Area Figure 1-1: Location of Yolo County in California
Yolo County is a general law county, which means that the Board of Supervisors is elected by district and that principal officers of the County are regulated by statutes that assign their duties.

The county’s total size is 653,549 acres (or 1,021 square miles). This includes both the incorporated area (the cities of Davis, West Sacramento, Winters and Woodland) which totals 32,325 acres and the unincorporated area, which totals 621,224 acres. Yolo County’s proximity to Sacramento International Airport as well as two major interstate highways places it within a significant transportation hub of the state. See Figure 1-2 for a map of Yolo County. 200
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18 Section 1: Introduction Yolo County Operational Area Figure 1-2: Map of Yolo County
The four cities have independent land use authority from the County. The unincorporated county contains several communities, including Capay, Clarksburg, Dunnigan, Esparto, Guinda, Knights Landing, Madison, Monument Hills, Rumsey, Yolo and Zamora. These unincorporated communities are under the jurisdiction of Yolo County.

There are other entities within Yolo County that have their own land use and related authority.

These include University of California Davis (UC Davis), the Yocha Dehe Wintun Nation, and in some circumstances the various school districts.

Established as the University Farm in 1906 and as a formal University in 1959, UC Davis is the largest campus in the UC system, spanning over 5,500 acres in Davis. The university is known for its agriculture, arts, humanities, life sciences, health sciences, veterinarian and engineering programs. Although the University is not subject to this General Plan, it is located within the unincorporated area and its resident student population and on-campus housing are factored into County policy.
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19 Section 1: Introduction Yolo County Operational Area Yocha Dehe Wintun Nation is the only federally recognized tribe with landholdings in Yolo County. The Yocha Dehe Wintun Nation operates the Cache Creek Casino Resort in western Yolo County and has become the County’s largest private employer. Tribal trust lands are administered by the U.S. Department of the Interior, Bureau of Indian Affairs and are not subject to County jurisdiction.

The Housing Authority of Yolo County (YCH) is an independent organization whose board of directors is appointed by the Yolo County Board of Supervisors. It receives funding from a variety of public and private sources to provide affordable housing and social programs for the County. Currently, the YCH owns and manages 431 conventional housing apartments and 301 migrant farm worker units. 1
Yolo County departments are responsible for providing a wide array of services to the unincorporated areas of Yolo County, as well as within municipalities. Departments are managed by elected officials or appointed directors who are responsible for administering local programs and services, in accordance with both applicable state law and county regulations.

Many county departments are further sub-divided into divisions, offices, and programs, which provide specific services to the public. The following is a list of Yolo County departments:
• Agriculture
• Assessor/Clerk-Recorder/Elections
• Board of Supervisors
• Community Services
o Environmental Health
o Fleet Services
o Integrated Waste Management
o Planning
o Public Works
• County Administrator
• County Counsel
• Child Support Services
• Department of Financial Services
• District Attorney
• General Services
o Facilities
o Information Technology
o Parks
• Health & Human Services Agency
1 Yolo County Housing (2023). FY Annual Agency Plan. Retrieved from Transparency & Accountability page <ych.ca.gov/about-us/#transparency>
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20 Section 1: Introduction Yolo County Operational Area o Community Health
o Child, Youth & Family
o Adult & Aging
o Service Centers
• Human Resources
• Library
• Probation
• Public Defender
• Sheriff-Coroner
Special Districts
The following is a list of special districts in Yolo County. • Knights Landing Ridge Drainage District
• Dunnigan Water District
• Esparto Community Service District
• Madison Community Service District
• Knights Landing Community Services District
• Cacheville Community Services District
• North Davis Meadows CSA
• Dunnigan County Service Area
• El Macero County Service Area
• Garcia Bend County Service Area
• North Davis Meadows County Service Area
• Wild Wings County Service Area
• Snowball County Service Area
• Willowbank County Service Area
• Colusa Basin Drainage District (also in Colusa County) • Yolo County Flood Control & Water Conservation District • Yolo County Resource Conservation District
• Yolo County Transportation District
• Reclamation Districts 108 (also in Colusa County), 150, 1600, 2035, 2068 (also in Solano County), 2093 (also in Solano County), 307, 537, 730, 765, 785, 787, 827, 999 (also in Sacramento County)
• Sacramento River Westside Levee District (also in Colusa County) • Yolo County Fire Districts (see below)
• Yolo County School Districts (see Section 1.4.5)
• Yolo County Cemetery Districts
o Capay Cemetery
o Cottonwood Cemetery
o Davis Cemetery
o Knights Landing Cemetery
o Mary’s Cemetery
o Winters Cemetery
• Solano Air Quality Management District (not in Yolo County) 203
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21 Section 1: Introduction Yolo County Operational Area • Napa-Solano-Yolo-Marin County Public Health Laboratory (not in Yolo County) • Woodland-Davis Clean Water Agency
• Sacramento Regional County Sanitation District (also in Sacramento and Placer Counties)
Fire Districts
Figure 2 provides a map of the Yolo County Fire Protection Districts.

Figure 1-3: Yolo County Fire Protection Districts
Parks & Recreation
In addition to parks operated and maintained by the four cities, the County of Yolo also provides regional recreational sites at various locations:
• Cache Creek Canyon
• Camp Haswell
• Vernon A. Nichols Park
• Knights Landing Boat Launch
• Esparto Community Park
• Elkhorn Regional Park
• Putah Creek Fishing Access
• Grasslands Regional Park
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22 Section 1: Introduction Yolo County Operational Area • Clarksburg Boat Launch
• Gibson Historical Museum

1.4.1 DEMOGRAPHICS
Lying directly between the rapidly growing regions of Sacramento and the Bay Area, Yolo County has experienced and will continue to experience, tremendous pressures to provide additional residential, commercial and industrial development. The ease of access provided by the Sacramento International Airport, the Capitol Corridor train, the Port of Sacramento and Interstates 5, 80 and 505, have all exacerbated existing growth pressures in the county.

The County’s economy is primarily based on agriculture. Yolo County has led the State in agricultural preservation practices for the last several decades, primarily by directing growth into the incorporated cities where services are available and where development can occur more efficiently. The Yolo County General Plan seeks to continue to preserve agriculture while also allowing for measured, appropriate residential and economic development focused within existing communities that will meet regional and local needs.

According to the California Department of Finance, 2022 Population and Housing estimates, the county’s 1,014.8 square miles of land area were home to 221,165 people and contained 81,945 housing units. The California Department of Finance population estimates for the County and incorporated jurisdictions are shown on Table 1-1. Approximately 88 percent of that population and 90 percent of the housing units lay within the four incorporated cities of Davis, Woodland, West Sacramento, and Winters. The population of Unincorporated Yolo County is approximately 35,900 residents as of 2022.

Table 1-1 Yolo County Population Estimates – Jan 1, 2022 Jurisdiction 2022 Housing Units
Davis 64,869 27,596
West Sacramento 52,837 12,788
Winters 7,422 2,754
Woodland* 60,137 22,236
*Woodland is the County seat, and is the center of the agricultural economy.

Source: California Department of Finance, 2022 E-5 Population and Housing Estimates – Organized by Geography Davis, has a unique university and residential community internationally known for its commitment to environmental awareness and implementing progressive and socially innovative programs. West Sacramento, sits across the Sacramento River from the State capital, Sacramento. It is home to the Port of West Sacramento, which ships out 1.3 million tons of Yolo County’s many agricultural products, such as rice, wheat and safflower seed, to world-wide markets. West Sacramento is also home to a Triple-A baseball team, the Rivercats, as well as several State agencies. The City of Winters, is a small farming town nestled at the base of the Vaca Mountains and offers unique shops, renowned restaurants, galleries and regionally 205
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Approximately half of the county’s unincorporated population and housing units are located within existing communities and residential neighborhoods. According to Census data2, the largest unincorporated population is Esparto, with a population of 3,733 and 1,267 housing units in 2021, which also serves as the gateway to the Capay Valley. Monument Hills is defined by its large lot, rural residential character, with a population of 1,508 and 559 housing units in 2021.

El Macero is a golf course community, adjoining the City of Davis to the east, with a population of 1,073 and 391 housing units in 2021. Knights Landing has a population of 944 and 296 housing units in 2021 and is a popular area for hunting and fishing. Dunnigan is the highway commercial center for the northern county, located at the interchange of Interstates 5 and 505 and has 1,081 residents and 501 housing units in 2021. Clarksburg is the focus of the county’s premier wine-growing region, with a population of 379 and 154 housing units in 2021. Yolo was once the County seat and currently has a population of 243 and 120 housing units in 2021.

Madison has a long farming history and includes one of two Migrant Labor Camps in the county, with 478 residents and 186 housing units in 2021. Other communities include West Plainfield, Rumsey, Guinda, Capay, North Davis Meadows, Binning Farms, Willow Bank, Patwin Road, Royal Oaks, Willow Oak, West Kentucky, El Rio Villa, Zamora and the Rumsey Rancheria. UC Davis accounts for much of the remaining unincorporated population, with 8,532 students and faculty living on campus, according to the 2021 Census data. The agricultural areas are the final component, with approximately 7,000 residents and an estimated 2,350 housing units.

Select social and economic information for the County and participating jurisdictions are shown in Table 1-2.

Table 1-2 Yolo County – Select Social and Economic Statistics Statistic Number
Populations
Population under 5 5.0%
Population under 18 20.4%
Population over 65 13.2%
Median Age (years) 32.7
Racial Makeup
White alone 73.1%
Black or African American 3.2%
American Indian or Alaska Native 1.8%
Asian 15.2%
2 U.S. Census Bureau (2021). American Community Survey 1-year estimates. Retrieved from Census Reporter Profile page for Yolo County, CA <http://censusreporter.org/profiles/05000US06113-yolo-county-ca/> 206
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24 Section 1: Introduction Yolo County Operational Area Native Hawaiian or Pacific Islander 0.6%
Hispanic or Latino 32.6%
Two or more races 6.1%
Income
Median household income (in dollars) $78,146
Mean income $109,287
Poverty Rate
All families 5.8%
All people 14.8%
Source: 2021 US Census
Approximately 66 percent of Yolo County residents’ live-in single-family houses and 34 percent live in multiple-family units.

1.4.2 COMMUNITY LIFELINES AND INFRASTRUCTURE
A lifeline enables the continuous operation of critical government and business functions and is essential to human health and safety or economic security. Lifelines are the most fundamental services in the community that, when stabilized, enable all aspects of society to function.

Lifelines are the integrated network of assets, services, and capabilities that are used day-to-day to support recurring needs of the community. There are multiple components and subcomponents that establish the parameters of the lifeline. The table below lists the components and subcomponents of Community lifelines.

Table 1-3 Community Lifeline Components

1. Safety and Security
Law Enforcement/Security Government Service
Police Stations
Law Enforcement
Site Security
Correctional Facilities
Emergency Operation Centers
Essential Government Functions
Government Offices
Schools
Public Records
Historic Resources
Cultural Resources
Fire Services
Fire Stations
Firefighting resources
Search and Rescue Community Safety
Local Search and Rescue Flood Control
Other Hazards
Protective Actions

2. Food, Water, Shelter
Food Water
Commercial Food Distribution
Commercial Food Supply Chain
Food Distribution Programs (e.g, Food banks)
Drinking Water Utilities (intake, treatment,
storage, and distribution)
Wastewater systems
Commercial Water Supply Chain
Shelter Agriculture
Housing (e.g., homes, shelters)
Commercial Facilities (e.g., hotels)
Animals and Agriculture
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3. Health and Medical
Medical Care Medical Supply Chain
Hospitals
Dialysis
Pharmacies
Long-Term Care Facilities
VA Health System
Veterinary Services
Home Care
Blood/Blood Products
Manufacturing
- Pharmaceutical
- Device
- Medical Gases
Distribution
Critical Clinical Research
Sterilization
Raw Materials
Public Health
Epidemiological Surveillance
Laboratory
Clinical Guidance
Assessment/Interventions/Treatments
Human Services
Behavioral Health
Patient Movement Fatality Management
Emergency Medical Services Mortuary and Post-Mortuary Services

4. Energy
Power Grid Fuel
Generation Systems
Transmission Systems
Distribution Systems
Refineries/Fuel Processing
Fuel Storage
Pipelines
Fuel Distribution (e.g. Gas stations, fuel points)
Off-shore Oil Platforms

5. Communications
Infrastructure Alerts, Warnings, and Messages
Wireless
Cable systems and wireline
Broadcast (TV and Radio)
Satellite
Data Centers/Internet
Local Alert/Warning Ability
Access to IPAWS (WEA, EAS, NWR)
NAWAS Terminals
911 & Dispatch Finance
Public Safety Answering Points
Dispatch
Banking Services
Electronic Payment Processing
Responder Communications
LMR Networks

6. Transportation
Highway/Roadway/Motor Vehicle Railway
Roads
Bridges
Freight
Passenger
Mass Transit Aviation
Bus
Rail
Ferry
Commercial (e.g., cargo/Passenger)
General
Military
Maritime
Waterways
Ports and Port Facilities

7. Hazardous Materials
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26 Section 1: Introduction Yolo County Operational Area Facilities HAZMAT, Pollutants, Contaminants
Oil/HAZMAT Facilities (e.g., chemical, nuclear)
Oil/HAZMAT/Toxic Incidents from Facilities
Oil/HAZMAT/Toxic Incidents from Non-Fixed
Facilities
Radiological or Nuclear Incidents
A critical facility may be defined as one that is essential in providing utility or direction either during the response to an emergency or during the recovery operation. FEMA’s HAZUS loss estimation software uses the following three categories of critical assets (Essential Facilities, High Potential Loss Facilities and Transportation and Lifelines). Essential facilities are those that if damaged would have devastating impacts on disaster response and/or recovery. High potential loss facilities are those that would have a high loss or impact on the community.

Transportation and lifeline facilities are a third category of critical assets.

The Yolo County Office of Emergency Services maintains a listing of Critical Facilities in Yolo County (including the participating jurisdictions) and the list is categorized according to FEMA’s critical facility definition. Additionally, the Annexes list the critical facilities specific to each jurisdiction. The following table (Table 1-4) lists the general categories of critical facilities in Yolo County.

Table 1-4: General Categories of Critical facilities in Yolo County Essential Facilities High Potential Loss Facilities Transportation and Lifelines • Hospitals and other Medical
Facilities
• Police Stations
• Fire Stations
• Emergency Operation Centers
• Power Plants
• Dams/levees
• Military installations
• Hazardous Material Sites
• Schools
• Shelters
• Day Care Centers
• Nursing Homes
• Main Government Buildings
• Highways, Bridges and
Tunnels
• Railroads and Facilities
• Bus Facilities
• Airports
• Water Treatment Facilities
• Natural Gas Facilities and
Pipelines
• Oil Facilities and Pipelines
For critical facilities, there are two hospitals in the County with a total bed capacity of 151 beds.

There are 83 schools, 20 fire stations, five police stations, and seven Emergency Operations Centers. There are seven dams identified within the region. Of these, two of the dams are classified as ‘high hazard’. There are also 1,227 hazardous material sites, zero military installations and zero nuclear power plants in Yolo County. There are several transportation systems in the County; these include highways, railways, bus routes, shipping lanes, and airport flight routes. There are over 458 kilometers of highways, 253 bridges, and 5,946 kilometers of pipeline in Yolo County. There are three bus terminals and four primary airports in the County, in addition to the Port of West Sacramento. There are six utility systems that include potable water, wastewater, natural gas, crude & refined oil, electric power and communications. 209
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27 Section 1: Introduction Yolo County Operational Area Other facilities in the county, such as locations that hold musical concerts, sporting events, and other events that attract large numbers of people, may also be at higher risk due to concentrations of population. These include, but are not limited to, the Yolo County Fairgrounds, the Cache Creek Casino and Resort, Raley Field, University of California, Davis, high school campuses and county or city parks. Other critical facilities unique to the county, tribe and cities are located in their respective Annexes (Jurisdictional Annexes are found in Volume 2), Yolo County Unincorporated Area Critical Facilities and other Community Assets are listed below.

Table 1-5: Yolo County Unincorporated Area - Critical Facilities and Community Assets Facility Address City
Communications Shed 3rd & B Streets West Sacramento
Probation/Storage 218 West Beamer Woodland
Emergency Operations Center 120 W. Main Street, Suite E Woodland Probation Annex 218 West Beamer Woodland
Public Works/Planning 292 West Beamer Woodland
Communication Center 35 N. Cottonwood Woodland
Yolo County Courthouse 725 Court Street Woodland
Erwin Meier Administration Building 625 Court Street Woodland Cache Creek Water Treatment Plant 1475 Hwy 16 Rumsey
County Landfill CR 104 & 28H Woodland
Health and Human Services Agency 25 & 137 N. Cottonwood Woodland Monroe Detention Center 140 Tony Diaz Drive Woodland
Sheriff Administration Office 140 Tony Diaz Drive Woodland Morgue 140 Tony Diaz Drive Woodland
Airport – Hanger Building CR95/CR29 Woodland
Airport Electrical Control & Storage Building CR95/CR29 Woodland More detailed information on damage and impact to the community as well as the overall summary of the community’s vulnerability is located Section 3.0 of the MJHMP Base Plan.

1.4.3 NATURAL, HISTORICAL, AND CULTURAL RESOURCES
Assessing Yolo 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.
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28 Section 1: Introduction Yolo County Operational Area • 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.

Natural Resources
The Yolo Bypass Wildlife Area (Wildlife Area) is 16,770 acres of managed wildlife habitat and agricultural land located within the southern floodway of the Yolo Bypass. A portion of the Wildlife Area spans Interstate 80 adjacent to the Yolo Causeway, between the cities of Davis and West Sacramento. The Wildlife Area is a public and private restoration project managed by the California Department of Fish and Game (DFG) in consultation with the Yolo Basin Foundation.

In 1997, the U.S. Army Corps of Engineers restored wetlands and associated habitats within the Wildlife Area. This project, originally named the Yolo Basin Wetlands, was renamed the Vic Fazio Yolo Wildlife Area. The entire wildlife area, however, is officially named the Yolo Bypass Wildlife Area.

The Blue Ridge Berryessa area consists of 785,000 acres along the spine of the western Blue Ridge Mountains in the northwestern part of Yolo County, and includes portions of Colusa, Solano, Napa and Lake Counties. The area remains primarily in private ownership and is not subject to State or federal management. The Blue Ridge Berryessa Natural Area Conservation Partnership (BRBNACP) is a collaboration involving various private landowners; businesses; local, state, and federal agencies; non-profit organizations; and supporters working to protect and enhance the 600,000 acre. To date, 50,000 acres have been conserved through easements and purchases.

In 2015, Berryessa Snow Mountain National Monument was created. The 330,780-acre monument extends from nearly sea level on Bureau of Land Management lands around Lake Berryessa in the south, up to 7,000 feet through the northern Snow Mountain Wilderness and the eastern boundary of the Yuki Wilderness in the Mendocino National Forest. The Monument offers a wealth of natural, historical and cultural resources, as well as exciting recreation opportunities for visitors. See Figure 1-2 for a map of Berryessa Snow Mountain National Monument.
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29 Section 1: Introduction Yolo County Operational Area Figure 1-4: Berryessa Snow Mountain National Monument
Source: San Francisco Chronicle
The lower Cache Creek planning area includes over 28,000 acres of land with state designated mineral resources, which includes about 18,250 acres of known “significant” deposits. Within the Cache Creek planning area, the County has designated an Open Space area of about 5,000 primarily privately owned acres which fall under the management guidance and regulation of the Cache Creek Resources Management Plan (CCRMP). As a by-product of permitted aggregate mining within the Cache Creek planning area there is an increasing acreage of dedicated land transferring into public ownership. Public access to these areas is anticipated to increase over time pursuant to the CCRMP. The CCRMP is a component of the Cache Creek Area Plan (CCAP), which is an adopted part of the county’s General Plan. The focus of the CCAP is groundwater protection, agricultural preservation, restoration of Cache Creek, and limitation and regulation of mining.

The Cache Creek Wild and Scenic River Area includes 31 miles of upper Cache Creek in Lake and Yolo counties that were added to the State Wild and Scenic Rivers System in 2005.

Designation of the upper reaches of the Creek as “wild and scenic” supports the creek’s scenic, recreational, wildlife, and fishery values and precludes new dams and water diversions. 212
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30 Section 1: Introduction Yolo County Operational Area The federal government owns 30,225 acres and the State of California owns 17,257 acres of land in unincorporated Yolo County managed for open space purposes. Each of the four Yolo County cities also own public open space, mostly in the form of parkland within their boundaries.

Notably, the City of Davis has acquired open space lands in a number of locations around its edge, and a number of open space areas are owned and managed by the University of California.

While nearly entirely altered from its native condition, agricultural lands in Yolo County continue to represent an important landscape for numerous wildlife species. Raptors, waterfowl and other water birds, a variety of songbirds, and small mammals use agricultural fields for nesting and foraging; but to large extent, the enhanced value of agricultural habitats in Yolo County is due to the integration of natural communities within the agricultural landscape.

Adjacent riparian corridors, roadside trees, windbreaks, woodlots, isolated trees, and field borders provide important nesting, roosting, and cover habitat for many local and migratory species that also use the agricultural fields as foraging habitat. The retention of these adjacent habitats has greatly enhanced the wildlife value of agricultural habitats in Yolo County and their continued retention and restoration is essential in maintaining this value over time.

Approximately 21 percent of the county can be defined as natural lands. These include native oak woodlands, prairie grasslands, and chaparral communities in the western mountains and foothills, riparian woodlands, native and restored wetland communities, and remnant valley oak groves and valley oak trees on the valley floor.

Wetlands
Wetlands include permanent marsh communities that are inundated all or most of the year, and seasonal wetlands that are inundated only a part of the year, typically during winter and spring.

Native seasonal wetlands are uncommon in Yolo County and include several remaining patches of alkali sink between Davis and Woodland, and vernal pools associated with the prairie grasslands near Winters. Most seasonal wetlands in Yolo County are restored and managed to provide habitat for wintering waterfowl. Significant areas of seasonal wetland and marsh communities are found primarily in the Yolo Basin, including the Yolo Bypass Wildlife Area, private lands in the southern panhandle, the Conaway Ranch north of Interstate 80, and the City of Davis Wetlands. Additional wetland habitats are found at the recently restored Roosevelt Ranch Preserve east of Zamora and in several other isolated locations throughout the central and eastern portions of the county.

Wetlands are among the most productive wildlife habitats, supporting many species of birds, mammals, reptiles, and amphibians. The presence of wetlands also enhances the biological value of the surrounding landscape because many species that find nesting and cover habitat in wetlands may forage more widely in agricultural or grassland habitats. Marsh communities, including non-tidal freshwater emergent wetland, tidal freshwater emergent wetland, and tidal 213
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31 Section 1: Introduction Yolo County Operational Area perennial aquatic wetland provide nesting and cover habitat for many wetland- and aquaticassociated species. Seasonal wetlands provide important habitat for wintering waterfowl and other water birds; and during the dry summer and fall, seasonal wetlands are used by numerous raptor and songbird species.

Riparian
Riparian refers to streamside vegetation that occurs along rivers, creeks, and sloughs. In Yolo County, riparian woodland and shrub communities occur along several natural rivers, creeks, and sloughs and constructed water delivery canals in the county, including Sacramento River, Putah Creek, Cache Creek, Oat Creek, Bird Creek, Buckeye Creek, Willow Slough, Dry Slough, Elk Slough, Sutter Slough, Tule Canal, Deep Water Ship Channel, and the Knights Landing Ridge Cut. Most of the creeks in the county drain the Interior Coast Ranges and flow west to east toward the Sacramento River basin. The sloughs are backwater drainages of the Sacramento River; and the canals were constructed for water delivery or transport purposes. The most significant riparian communities occur along Putah Creek and Cache Creek. Both supports relatively dense valley oak/cottonwood riparian forest and are significant wildlife movement corridors between the Interior Coast Ranges on the west and the Sacramento River basin on the east. Smaller creeks and sloughs also support significant remaining riparian corridors that interconnect the mountainous landscape on the west with the valley floor or extend north-south through the lower elevation agricultural landscape.

Riparian vegetation is also essential in maintaining the quality of in-stream habitat by providing shade, food, and nutrients. Downed trees, willow mats, and other vegetation scour pools, form logjams and dams, and provide important habitats for fish, aquatic reptiles and amphibians, and aquatic insects, those are listed below.
• Oak Woodlands/Chaparral
• Grassland Prairies/Valley Oak Savannah
• Remnant Oak Trees, Groves, and Tree Rows
Special-Status Species
Many special-status species (including state and federal threatened and endangered species, state species of special concern and fully protected species, and plants listed by the California Native Plant Society) occur or have potential to occur in Yolo County. Special-status species occur throughout the county in all of the vegetation communities and habitats described above.

However, while several species such as bald eagle, golden eagle, and Cooper’s hawk are known to occur primarily in the mountainous regions on the western edge of the county, most are known to occur in the more disturbed agricultural landscape of the Central Valley.

As noted above, in many cases the retention of natural features within this landscape greatly enhances habitat conditions for species, such as the Swainson’s hawk, that have successfully 214
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32 Section 1: Introduction Yolo County Operational Area adapted to an agricultural landscape. Others continue to persist in smaller patches of suitable habitat, such as the state-threatened black rail, which has been detected in the wetlands on the Yolo Bypass Wildlife Area; and the western burrowing owl, which uses remaining grasslands, roadside edges, artificial berms, and some agricultural habitats. Some species have not been detected in the county for many years, such as the western yellow-billed cuckoo, due to limited habitat availability and quality. Preservation and restoration of suitable habitats for these species is key to their continued occurrence or reestablishment in Yolo County.

The Delta Region
In the past several years, the Delta has become an area of intense interest, with numerous planning and legislative efforts looking to redefine the policy and regulatory landscape. The 1959 Delta Protection Act created the legal delta boundary in the Sacramento-San Joaquin Delta (see Figure 1-3). A portion of Yolo County falls within the boundary. The Regional Flood Planning Boundary includes areas of Yolo County outside of the legal delta boundary.

Figure 1-5: The Legal Delta Boundary
Source: Public Policy Institute of California
Those areas of the Yolo Bypass, the City of West Sacramento, and the unincorporated area that lie south of Interstate 80 are located within the Primary and Secondary Zones of the Sacramento215 2023 Yolo Multi-Jurisdictional
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33 Section 1: Introduction Yolo County Operational Area San Joaquin Delta. Land use in these areas must be consistent with the Yolo County General Plan with the Land Use and Resource Management Plan (LURMP), as adopted by the Delta Protection Commission (DPC). In 2018, the DPC was in the process of updating the LURMP, to address a wide range of issues, including court decisions related to water export, studies that indicate serious problems with the health of the Delta ecosystem, concerns about the ability of levees to withstand significant flood and/or seismic events, and the effects of future global climate change. However, this process ended up pausing and the update was never completed.

Figure 1-6: Delta Protection Zones in Yolo County
Source: Yolo County GIS Department
In 2006, the Governor issued an Executive Order creating the Delta Vision process. The Delta Vision Blue Ribbon Task Force (DVBRTF) is a group of public officials, experts, and stakeholders, charged with developing recommendations on the overall management and governance of the Delta, including goals related to improving safety, ensuring water supply and 216
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34 Section 1: Introduction Yolo County Operational Area water quality, expanding recreation, coordinating emergency response, and protecting infrastructure and public safety.

Historical Resources
Individuals, various community groups and local organizations throughout Yolo County preserve historical resources. These groups include the County Planning Commission/Historic Preservation Commission and various volunteer historical societies. The Planning Commission serves as the Historic Preservation Commission which is tasked with establishing criteria, guidelines and standards to pursue the goals outlined in the County’s Historic Preservation Ordinance. The Commission is responsible for maintaining an inventory of all historical landmarks and districts within Yolo County and recommending future historic designations to the Board of Supervisors.

The Planning Commission decides permits for demolition and for alterations to historic structures. There are a number of repositories of historical artifacts and information in Yolo County, including the Yolo County Historical Museum, the Yolo County Archives and Record Center and the Hattie Weber Museum. The Yolo County Historical Museum is in Woodland.

The museum provides tours of the architecturally historic building and displays furnishings and artifacts from Yolo County’s past, specifically between 1850 and 1930, and includes outbuildings that feature artifacts associated with the agricultural industry and farming lifestyle.

The Yolo County Archives and Record Center maintains a comprehensive archive of historical materials dating back from the County’s beginnings in 1850. A broad range of materials are stored at the Archive and Record Center, including County documents, original tax records, old newspapers, probates, wills, civil and criminal cases, original maps of Mexican land grants, personal scrapbooks, video reels and a complete set of meeting notes from every meeting of the Yolo County Board of Supervisors.

Yolo County maintains its own list of local historical landmarks. There are also county listings on the National Register of Historic Places, the list of California State Historical Landmarks, and the list of California Points of Historical Interest.

Cultural Resources
There is one tribe with registered traditional land in Yolo County, the Yocha Dehe Wintun Nation, which is a federally recognized Tribe. They are a significant landowner and employer as the operators of the Cache Creek Casino Resort in Brooks. The Yocha Dehe Wintun Nation is a recognized sovereign nation. As such, the Department of the Interior, Bureau of Indian Affairs, holds approximately 267 acres in trust for the Rumsey Tribe (the Tribe). One site contains houses for the tribal members, a community center, and the Yocha-De-He Preparatory School.

The other site is home to the Cache Creek Casino Resort. As sovereign lands, these areas are not 217
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35 Section 1: Introduction Yolo County Operational Area a part of the County’s General Plan. The Tribe also owns several thousand acres in and around the trust lands. More information on the Yocha Dehe Wintun Nation can be found in their Annex (Volume 2).

1.4.4 ECONOMICS
Yolo County has many existing characteristics that make it a competitive business environment within the Sacramento region. The County’s several significant assets include the following:
• Access to regional job centers
• Visibility and easy access to Interstates 80, 5 and 505 • Airport and transit connections
• Affordable housing
• Affordable land
• Food and fiber business synergy
Economic assets at risk may include major employers or primary economic sectors, such as, agriculture, whose losses or inoperability would have severe impacts on the community and its ability to recover from disaster. After a disaster, economic vitality is the engine that drives recovery. Every community has a specific set of economic drivers, which are important to understand when planning to reduce disaster impacts to the economy. When major employers are unable to return to normal operations, impacts ripple throughout the community. Major employers in the County are shown in Table 1-6.

Table 1-6: Major employers in Yolo County in 2022
Employer Name Location Industry
Beckman Coulter Inc West Sacramento Physicians & Surgeons Equip & Supls-Mfrs Cache Creek Casino Resort Brooks Casinos
Capital Express Lines West Sacramento Trucking-Motor Freight City of Davis – City Manager
Ofc
Davis City Government-Executive Offices
Clark Pacific West Sacramento Concrete Products – Except Block & brick (mfrs)
Dennis Blazona Constr Inc West Sacramento Construction Companies Fedex Freight West Sacramento Trucking-Motor Freight
IKEA West Sacramento Furniture-Dealers-Retail
Mariani Nut Co Winters Nuts-Edible
Mcguire & Hester West Sacramento General Contractors
Nor-Cal Beverage Co West Sacramento Vending Machines – Manufacturers Pacific Coast Producers Woodland Canning (mfrs)
Procurement Office West Sacramento State Government- General Offices Promega Corp Madison Biotechnology Products & Services
Rite Aid Distribution Ctr Woodland Distribution Centers (whls) Sutter Davis Hospital Davis Hospitals
Target Distribution Ctr Woodland Distribution Centers (whls) Tony’s Fine Foods West Sacramento Grocers-Wholesale
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36 Section 1: Introduction Yolo County Operational Area University of California Davis Davis Schools-Universities & Colleges Academic UPS Customer Ctr West Sacramento Mailing & Shipping Services Walmart Supercenter West Sacramento Department Stores
Woodland Healthcare Woodland Health Care Management
Woodland Healthcare
Foundation
Woodland Health Services
Yolo County District Attorney Woodland Government Offices – County Yolo County Sheriff-Civil Div Woodland Government Offices – County Source: State of California, Employment Development Department Agriculture has been at the heart of Yolo County’s identity, character, economy and way of life since the County’s founding in 1850. Today, over 85 percent of county land is used for agriculture. Traditional growers on large-scale farms share the land with a growing number of diversified small farms (e.g. truck farms), as well as thriving livestock operations. Additionally, many farmers are implementing innovative new models for farm operation, crop choice and mix and marketing. Important contributors to the strength and success of agriculture in Yolo County include the County’s longstanding commitment to agricultural preservation, its focus on directing growth into the existing cities and towns and the presence of UC Davis, which is an international leader in agricultural research and education.

The gross value of Yolo County’s agricultural production for 2021 was $811,123,000. This represents an increase of $99,297,000 or 13.9% above 2020’s value of $711,826,000. Almonds were the top commodity for 2021 with a gross value of $137,114,000, followed by tomatoes with a gross value of $136,618,000. Although there was an increase in gross crop value, 2021 was a challenging year due to water shortage. This is reflected primarily in a 45% decrease in Rice acreage. Seed crop was also down. The overall value of our primary crop increases was due to strong pricing and an increase in almond production due to maturing trees. Hay for feed reflected an increase demand again driven by drought. Table 1-6 contains a list of the top ten agricultural commodities in Yolo County for 2021 and their gross values across three years.

Table 1-7 Top 10 Commodities in Yolo County, 2019-2021
Commodity 2021 2020 2019

1. Almonds (Meats) $137,114,000 $98,250,000 $157,776,000

2. Tomatoes, Processing $136,618,000 $127,435,000 $107,540,000

3. Grapes, Wine (All)1 $116,528,000 $104,760,000 $108,143,000

4. Organic Production (All) $56,877,000 $46,080,000 $56,902,000

5. Rice2 $38,791,000 $67,667,000 $57,086,000

6. Walnuts (All) $37,526,000 $27,550,000 $35,800,000

7. Hay, Alfalfa $34,336,000 $27,270,000 $30,492,000

8. Sunflower seed $30,095,000 $33,422,000 $26,260,000

9. Pistachios3 $29,138,000 $8,569,000 $2,566,200

10. Apiary4 $22,085,000 $16,231,000 $14,301,000
1 2020 value corrected
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37 Section 1: Introduction Yolo County Operational Area 2 Includes USDA Support prices, does not include seed
3 2020 and 2019 total values corrected
4 Includes colonies, honey, package bees, pollination, queens, and wax. 2020 value corrected Source: Yolo County Agriculture Department, Yolo County Agricultural Crop Report Important farmlands in Yolo County are presented on the Important Farmlands in Figure 1-5.

The majority of the County’s farmland is Prime Farmland, particularly in flat areas. Most of the County’s cities and unincorporated communities are surrounded by Prime Farmland. The western foothills are predominantly classified as Grazing Land.

Figure 1-7: Important Farmland in Yolo County, 2018
Source: California Department of Conservation
The California Land Conservation Act, better known as the Williamson Act, has been a cornerstone of the County’s agricultural preservation program. As shown in Figure 1-6, 410,659 acres or 67 percent of Yolo County’s total land area is in Williamson Act contracts. In 2005, the State honored Yolo County with an agricultural stewardship award in recognition of the County’s work to preserve agricultural land through the Williamson Act. Subventions 220
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38 Section 1: Introduction Yolo County Operational Area (reimbursements for lost property tax revenue resulting from Williamson Act contracts) have repeatedly been proposed for reduction or elimination by the State in recent years to balance the State budget. This would have a significant and adverse effect on both farmers and the County.

Figure 1-8: Williamson Act Contracts
Source: Yolo County GIS Department

1.5 EXISTING AUTHORITIES, POLICIES, PROGRAMS, AND RESOURCES Yolo County and its jurisdictions each has an Emergency Operations Plan, a General Plan, which includes a Safety Element, an Emergency Services Ordinance that clearly defines roles and responsibilities in accordance with state and federal guidelines. The County CAO and jurisdictional City Managers noted in this document serve as the Directors of Emergency Services for their respective areas by law, ordinance and Municipal Code. The Board of Supervisors, City Councils, Tribal Council or Special District Board of Directors serve as the 221
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39 Section 1: Introduction Yolo County Operational Area administering agency and the promulgation authority for all plans, policies and procedures within Yolo County and its member jurisdictions. The county and participating jurisdictions recognizes the enhanced Hazard Mitigation Plan of the State of California, the California Emergency Services Act, and the appropriate Federal Regulations including 44 CFR 201. Yolo County is subject to the State of California Uniformed Building Code (UBC), which dictates standards on all current and future construction within Yolo County. 2030 General Plan
The Yolo County 2030 General Plan adopted in 2009 provides comprehensive and long-term policies for the physical development of the county and is often referred to as “the constitution” for local government. This is only the third time in the county’s history that the General Plan has been comprehensively updated, and the first time since 1983. While the fundamental goals of promoting agriculture, enhancing open space, and creating sustainable communities are the same as they have been over the past 50 years, the circumstances facing the county have changed.

Issues such as the global economy, climate change, and the role of local government create new challenges to maintaining the county’s historic vision. The 2030 General Plan charts a course for the county over the next twenty years that will achieve its goals and address these concerns. The General Plan separates action items that will implement the variety of programs needed to realize the county’s vision; this plan works in coordination with the 2023 revision of the HMP.

Climate Action and Adaptation Plan
Yolo County has a well-earned reputation for environmental protection and climate action. A leading advocate of ecosystem conservation, responsible growth, and agricultural lands preservation for more than 40 years, the County has also taken numerous steps to reduce emissions associated with County government operations.

In 1982, Yolo County adopted an Energy Plan, which was one of the first of its kind. In 2007, Yolo County became one of 12 charter members from throughout the country to sponsor the Cool Counties Initiative, which pledges each county collectively to reduce greenhouse gas emissions by 80% by 2050. That same year, the county organized local cities, special districts and UC Davis to form the Yolo County Climate Change Compact, providing an ongoing forum for exchanging information on how best to analyze and address greenhouse gas emissions. The 2030 General Plan, adopted in November 2009, has over 350 policies that deal with climate change.

In September 2020, the Yolo County Board of Supervisors doubled down on its commitment to climate leadership by approving a Climate Emergency Declaration (Resolution No. 20-114), which set a goal for the County to achieve a carbon negative footprint by 2030, while ensuring a just transition to an inclusive, equitable, sustainable, and resilient local economy. This goal was, and continues to be, one of the most ambitious emission reduction goals of any municipality in 222
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40 Section 1: Introduction Yolo County Operational Area the Country. The Board subsequently created the Yolo County Climate Action Commission (YCCAC), an eleven-member advisory body is charged with developing and implementing a Climate Action and Adaptation Plan (CAAP) to meet the 2030 goal and ensuring vulnerable, marginalized, and historically underserved communities are centered in the process.

The CAAP and MJHMP overlap in that both documents address climate-related natural hazards such as wildfires and floods and propose responses in the form of policies, programs, and projects. The Climate Action and Adaptation Plan, in contrast also considers incremental or slow-onset climate change such as seasonal shifts, and the ways community members and industries need to adjust to these changing climatic conditions. Still, both documents have a goal of long-term risk reduction, and initiatives from the County’s climate planning work have historically been incorporated into the HMP as mitigation projects.

The overall community-wide Greenhouse gases (GHG) emissions for the unincorporated County (excluding UC Davis, the Yocha Dehe Wintun Nation and special districts) was 1,082,801 metric tons (MT) of carbon dioxide equivalent (CO2e) in 2016. The largest proportion of GHG emissions in the County in 2016 came from the On-Road Transportation sector, followed by Agriculture, Energy Consumption, Off-Road Transportation, Solid Waste and Wastewater Treatment. The total GHG emissions for 2016 indicates a decrease of 96,012 MTCO2e or ~8 percent from the adjusted 2008 inventory. GHG reductions, compared to the 2008 inventory, occurred in the Energy Consumption, On-Road Transportation, Agriculture, and Wastewater Treatment sectors.

To reach net-negative emissions, the County will need to reduce emissions across all sectors, and also increase adoption of carbon sequestering practices across natural and working lands. To do this, the County has developed a Natural and Working Lands Technical Advisory Committee (NWL TAC) comprised of small and large-scale farmers and ranchers that will identify and prioritize sequestration strategies that are feasible and mutually beneficial to Yolo County growers. The 2030 CAAP update is still in process and is expected to be completed in 2024. This update will include an updated emission inventory for the unincorporated area as well as recommendations for policies, programs, and specific sequestration and emissions reduction strategies and actions.

1.6 NEW ITEMS FOR THE 2023 UPDATE
The 2018 Yolo County Multi-Jurisdictional Hazard Mitigation Plan (MJHMP) contained descriptions of their planning process, the risk assessments of identified hazards for the Yolo County Operational Area and mitigation strategies for reducing the risk and vulnerability from these hazards. This document is, in concept, a revision of the Yolo County MJHMP composed and approved in 2005, updated and reapproved in 2013 and 2018. As part of this 2023 MJHMP Update, a thorough review and update of the 2018 Yolo County MJHMP was conducted to 223
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41 Section 1: Introduction Yolo County Operational Area ensure that this plan update reflects current community conditions and priorities in order to realign the updated mitigation strategy for the next five-year planning period. This update also represents a major refinement of the hazard mitigation planning process for Yolo County in accordance with FEMA’s latest planning guidance the Local Mitigation Planning Policy Guide released in 2022 and implemented in 2023. This section of the MJHMP update includes the following:
• What’s New in the Plan Update. Section 1.6.1 provides an overview of the approach to updating the Plan and identifies new analyses, data and information included in this HMP Update to reflect current community conditions. This includes a summary of new hazard and risk assessment data as it relates to the Yolo County Operational Area as well as information on how the mitigation planning process has shifted due to internal changes at Yolo County. The actual updated data, discussions, and associated analyses are contained in their respected sections within this HMP update.
• Summary of Significant changes to current conditions and Hazard Mitigation Priorities.

Section 1.6.2 provides a summary of significant changes in current conditions, changes in vulnerability, and any resulting modifications to the community’s mitigation program priorities.

The revision of the MJHMP has been a collaborative effort, involving various local and tribal government jurisdictions, public authorities, special districts, and selected community-based organizations that represent a broad composite of the operational area. Additionally, selected state agencies and organizations have also contributed to this planning effort and are represented within the document by direct participation or supplemental reference.

The bulk of the revision was conducted as a collaborative partnership between several local and tribal government organizations, organized as the HMP Steering Committee, and coordinated and facilitated by the Yolo County Office of Emergency Services (OES). This was a major inter-organizational undertaking, requiring a commitment of staff time, organizational resources, ongoing communication, and data collection to achieve the desired hazard mitigation planning goals. The specific jurisdictions represented in the plan that will formally approve this 2023 update are as follows: Cities of Davis, Winters, West Sacramento and Woodland, the Yocha Dehe Wintun Nation; Yolo County; Reclamation Districts and Special Districts in Yolo County that wish to approve it, specifically Reclamation District 108, Reclamation District 787, Dunnigan Water District, Knights Landing River Drainage District, Sacramento River West Side Levee District, and University of California Davis.

In addition to governmental efforts, community involvement was a major objective of the planning process, with online and participative outreach conducted at various stages within the 224
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42 Section 1: Introduction Yolo County Operational Area planning process. Although not every aspect of the broader community was directly involved in the planning process, significant effort was made to ensure that the public and non-governmental entities had a voice in the plan’s development.

Completion of this MJHMP update further provides documentation of the Yolo County communities’ continued commitment and engagement in the mitigation planning process.

1.6.1 WHAT’S NEW IN THE PLAN UPDATE
This MJHMP update involved a comprehensive review and update of each section of the 2018 Plan. Only the information and data still valid from the 2018 MJHMP was carried forward as applicable into this 2023 MJHMP Update.

Also to be noted, in Section 6.0 Plan Evaluation and Maintenance of this MJHMP Update identifies key requirements for updating future plans:
• Consider changes in vulnerability due to mitigation action implementation. • Document success stories where mitigation efforts have proven effective. • Document areas where mitigation actions were not effective. • Document any new hazards that may arise or were previously overlooked. • Incorporate any new data or studies on hazards and risks. • Incorporate new capabilities or changes in capabilities. • Incorporate new action recommendations or changes in action prioritization.

These requirements and others as detailed throughout this plan were addressed during this MJHMP Update process.

As part of the comprehensive review and update of each section of the 2018 MJHMP, Yolo County decided to broaden the Steering Committee Members to not only include participating jurisdictions but also selected members to represent a cross-section of views and interests within the planning area. Through this inclusion of diverse interests, the MJHMP Steering Committee sought to enhance the robustness of the planning effort and to build support for hazard mitigation activities across the Stakeholder groups. The Steering Committee recognized that updated data, if available, would enhance the analysis presented in the risk assessment and utilized in the development of the updated mitigation strategy. Specific data used is sourced throughout this MJHMP update. This new data and associated analysis provided valuable input for the development of the updated mitigation strategy presented in Section 5.0 of this MJHMP Update.

Highlights of new information and analyses contained in this MJHMP Update includes the following:
• Most natural hazards from the 2018 MJHMP were profiled in this 2023 MJHMP Update.

However, the Steering Committee decided to not fully profile all Non-Natural Hazards to 225
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43 Section 1: Introduction Yolo County Operational Area better focus mitigation efforts that could be funded by FEMA Mitigation grants. NonNatural hazards will be mentioned, and their effects briefly described for situation awareness purposes.
• The County created a list of critical facilities that were spatially quantified in GIS, and then over-lay each mapped hazard to determine vulnerability. • Disaster declarations were updated, including federal, state, and USDA disaster declarations.
• Yolo County partnered with Yolo County Climate Action and Sustainability group to better address hazards that are exacerbated by climate change and to address public comments and concerns.
• Community Lifelines were added to reflect the 2022 FEMA Local Mitigation Planning Policy Guide.
• A more detailed GIS analysis was performed for wildfire hazard, including Community Lifelines, population at risk, historic, cultural, and natural locations at risk, and general community impacts.
• An updated GIS analysis was performed for the flooding hazard for the 1%/0.2% annual chance floods, including Community Lifelines at risk, population at risk, future development, and general community impacts.
• Each risk assessment was re-evaluated for each identified hazard to reflect new information and to reflect the updated FEMA Plan review tool. This included reworking the hazard profiles such as new hazard event occurrences and updating the vulnerability assessment based on more recent hazard data.
• Utilizing updated Community Lifelines GIS mapping for the Operational Area, an analysis was conducted to provide an updated inventory of critical facilities and those that fall within mapped hazard areas.
• Also, as required by current FEMA planning guidance, an analysis of ongoing and continued compliance with the NFIP was included in this MJHMP Update.

1.6.2 CLIMATE CHANGE
According to the California Natural Resource Agency (CNRA), climate change is already affecting California and is projected to continue to do so well into the foreseeable future.

Current and projected changes include increased temperatures, seal level rise, a reduced winter snowpack altered precipitation patterns, and more frequent storm events. Over the long term, reducing greenhouse gases can help make these changes less severe, but the changes cannot be avoided entirely. Unavoidable climate impacts result in a variety of secondary consequences including detrimental impacts on human health and safety, economic continuity, ecosystem integrity and provision of basic services. Climate change is being profiled as it is applicable to the Natural Hazards profiled in Section 3.0. Yolo County is considering climate change issues when identifying future mitigation actions and continuing to work with the Sustainability Department on Climate Change and Adaptation plans. Since the 2018 HMP, there has been 226
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44 Section 1: Introduction Yolo County Operational Area significant effort made to increase the partnership, collaboration, and planning efforts with the Climate Change and Adaption Planning group to integrate hazards, mitigation efforts, and bring awareness to our jurisdictions.

1.6.3 CONTINUED PARTICIPATION IN THE COMMUNITY RATING SYSTEM

PROGRAM
Yolo County has participated in the Community Rating System Program (CRS) since 2012. The CRS program is designed to recognize floodplain management activities that go above and beyond the National Flood Insurance Program’s (NFIP) minimum requirements. CRS is designed to reward a community for implementing public information, mapping, regulatory, loss reduction and/or flood preparedness activities. On a scale of 10 to 1, Yolo County is currently ranked Class 8. One of the overall priorities of Yolo County is to continue in this program and improve the class ranking in the next cycle verification process in 2024. Yolo County completed the FEMA Community Rating System Annual recertification in 2023.

Finally, the extent to which this revised plan will or will not be a success locally is dependent upon the commitment at all levels of the designated operational area, whether it be governmental or community-based, to monitor the progress of the identified mitigation strategies, and to ensure that appropriate projects are implemented in accordance with identified need, overriding policy, and funding availability.

1.7 HAZARD MITIGATION PRINCIPLES
• Hazard Mitigation is any sustained action taken to eliminate or reduce long-term risk to human life, property, and the environment posed by a hazard. • Hazard Mitigation Planning is the process of making any sustained plan or course of action taken to reduce or eliminate long-term risk to people and property from both natural hazards and their effects. The planning process includes establishing goals and recommendations for mitigation strategies.
• Hazard Mitigation may occur during any phase of a threat, emergency or disaster.

Mitigation can and should take place during the preparedness (before), response (during), and recovery (after) phases.
• The process of hazard mitigation involves evaluating the hazard’s impact and identification and implementation of actions to minimize the impact.

1.8 PLAN ORGANIZATION AND STRUCTURE
The Plan has been set up in two volumes so that the elements that are jurisdiction-specific can easily be distinguished from those that apply to the whole County.

Volume 1 includes the required elements of a hazard mitigation plan from FEMA’s Local Mitigation Planning Policy Guide, dated April 19, 2022, effective April 19, 2023. This includes 227
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45 Section 1: Introduction Yolo County Operational Area the planning process, public involvement strategy, hazard risk assessments, countywide mitigation actions, and a plan maintenance strategy. Since this is a multi-jurisdictional plan, Volume 1 addresses the entirety of Yolo County Operational Area, participating Jurisdictions, Special Districts, and the Unincorporated Areas.

Volume 2 contains the Jurisdictional Annexes, which detail the hazard mitigation planning elements specific to each participating Jurisdiction in Yolo County Operational Area MJHMP Update and includes all federally required jurisdiction-specific elements. Each Annex is not intended to be a standalone document, but annexes to, supplements, and incorporates by reference information in Volume 1 of the Plan. As such, all information in Volume 1, including the planning process and other procedural requirements and planning elements apply to the participating jurisdictions as well. The Annexes provide additional information specific to each participating jurisdiction, including additional details on the risk assessment and mitigation strategy specific to the participating jurisdiction.
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46 Section 2: Planning Process Yolo County Operational Area SECTION 2.0: PLANNING PROCESS
This section describes each stage of the planning process used to develop the Yolo County Operational Area Multi-Jurisdictional Hazard Mitigation Plan. The planning process provides a framework for document development and follows the FEMA recommended steps as described in Table 2-1 below. The Yolo County Operational Area Multi-Hazard HMP is a communitydriven, living document. The planning process encourages communities to integrate mitigation with day-to-day decision making.

When undergoing the update process for the 2018 Yolo Operational Area Hazard Mitigation plan, the lead coordinating agency recognized the need to have a specific planning committee that would be tasked with establishing a mechanism for the development and update of the Jurisdictional Annexes, formerly called Community Profiles in the 2018 update, and implementation of jurisdictional mitigation projects. Each participating local jurisdiction would undergo the same planning process prescribed by FEMA as briefly outlined in the table below.

Table 2-1: FEMA Hazard Mitigation Planning Process
Disaster Mitigation Act Regulation FEMA Planning Process

1. Organize the Planning Process and Resources
201.6(c)(1) 1) Organize the Planning Effort
201.6(b)(1) 2) Involve the Public
201.6(b)(2) and (3) 3) Coordinate with other Departments and agencies

2. Assess Risks and Capabilities
201.6(c)(2)(i) 4) Identify the Hazards
201.6(c)(2)(ii) 5) Assess the Risks

3. Develop the Mitigation Strategy
201.6(c)(3)(i) 6) Set Goals
201.6(c)(3)(ii) 7) Review Possible Mitigation Activities 201.6(c)(3)(iii) 8) Draft an Action Plan

4. Adopt and Implement the Plan, Monitor Progress
201.6(c)(5) 9) Adopt the plan
201.6(c)(4) 10) Implement, Evaluate, and Revise the Plan Revision of the Hazard Mitigation Plan requires collaboration and partnering at a multitude of levels.
• Identifying the primary local stakeholders – Formation of inter-jurisdictional Hazard Mitigation Steering Committee and Planning Committee
The planning process began with the organizational phase to establish the Hazard Mitigation Planning Committee Members comprised of all jurisdictions wishing to seek approval of the Hazard Mitigation Plan such as key County representatives, and other jurisdictional stakeholders. 229
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47 Section 2: Planning Process Yolo County Operational Area We contacted all our operational area partners asking if they wanted to participate in the Hazard Mitigation Plan update process and to what degree of participation. Partners who wanted to be part of the planning process, previously submitted an annex in 2018 HMP, and those who would like to apply for HMP grant funds independently in the future, agreed to a planning partner expectation letter (Letter of Interest) and submitted their intent to full participate in the planning process to the Office of Emergency Services. Those partners formed the Planning Committee. A Steering Committee was also established and tasked with guiding the overall plan update process. Members of the Steering Committee were selected to represent a cross-section of views and interests within the planning area. A similar process was followed in which we contacted all our operational area partners asking if they would like to participate as a steering committee member, outlining the expectations of what a steering committee member would do during the planning phase and after the plan was approved (see Section 2.2.1, 2.2.2). If they were interested, they submitted a letter of interest to encourage continued participation in the HMP process.

There were kick off meetings for both groups (see Appendix A). • Determining how public input will be considered and incorporated in the planning process.

The first task of the Steering Committee was to determine how the public would be considered and incorporated into the planning process. It was determined to conduct a survey to determine what the public considers hazards in their community. Modifying a public survey that was conducted in 2018, the Steering Committee distributed the survey widely, Yolo County PIO sent a press release, and the survey was available to the public on the Yolo County website. It was also determined to create a more public facing HMP site on the Yolo County website, and to better explain what hazard mitigation issue, publishing the results of the community/public surveys, and creating an accessible map where residents could look at the hazards that affect their community. This would later evolve to a Story Map idea for HMP and serves as a partnership with our IT Department GIS Manager. The Steering Committee also established some dates, times for public meetings in various jurisdictions to solicit feedback and comments on the hazards, mitigation projects, and HMP drafts. See Section 2.4 for more information on public involvement.
• Establishing project goals and objectives
During our first kickoff meetings, we examined the project goals and objectives from the 2018 HMP and discussed whether we would keep or modify these project goals and objectives. The Planning and Steering Committees continued to examine and modify these goals until the committees reached a consensus on wording, language. The Planning and Steering Committees also discussed timelines/timeframes to meet various measures in the planning process – such as conducing public surveys, analyzing hazards and vulnerabilities, drafting mitigation strategies, drafting initial HMP update, conducing more public meetings, incorporating public feedback/comments, finalizing HMP update.
230
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48 Section 2: Planning Process Yolo County Operational Area • Organizing the project work plan based upon identified goals and objectives. • Review of existing Hazard Mitigation Plan
The Planning Committee then went on to start their project work, reviewing the previous 2018 HMP and their respective annexes. Due to staff turnover, many planning partners did not write the 2018 Jurisdictional annexes and needed assistance with prioritizing a work plan to meet the local mitigation planning criteria. During this planning process, FEMA also released an updated 2023 HMP Local Mitigation Planning Policy Guide, in which the planning team then needed to discuss the modification and changes from the 2011 Local Mitigation Plan Review Guide. These discussions led to further modifications made in the 2023 HMP Update (see Section 1.6). • Identification and refined assessment of real or potential hazards and threat conditions A detailed risk assessment was conducted by participating planning jurisdictions including Yolo County, Unincorporated areas, Cities, and Special Districts. This risk assessment looked at vulnerabilities, critical infrastructure, and existing capabilities (section 4.0) to determine vulnerability risks. The hazard profiles are further discussed in Section 3.0. • Revision of jurisdictional demographic and organizational data, and reformatting of information presentation
It was determined by the Planning and Steering Committees, given the staff turnover to update jurisdictional demographic and organizational data. The Planning Committee members, discussed with their planning teams how this information should be updated, changed, or better presented/communicated to their communities. This process allowed new planning team members to learn about new data sources and gave an opportunity for jurisdictions to update their existing data sources.
• Development of prioritized hazard mitigation strategies and projects, keyed to identified hazards.

After the risks and hazards were identified, vulnerabilities and mitigation capabilities assessed, there were discussions around developing a focused mitigation strategy by all participating jurisdictions. The planning partners understood that for every hazard their jurisdiction identified as high and medium priority, that a mitigation project would need to be identified and tied to the hazards and vulnerabilities identified. There was then discussion on mitigation strategy priorities, alternative mitigation strategies, how would mitigation projects be ranked, and a discussion around the mitigation projects identified. Which led to the mitigation strategy discussed in Section 5.0.

The Office of Emergency Services compiled the information, led meetings, and led the efforts to 231
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49 Section 2: Planning Process Yolo County Operational Area update the 2018 HMP. Once approved by CalOES and FEMA, this Hazard Mitigation Plan update will be adopted and implemented by the County and all jurisdictions over the next five years.

2.1 PARTICIPATING JURISDICTIONS AND ORGANIZATIONS
The representatives of the jurisdictions participating in the 2023 Yolo County Operational Area Hazard Mitigation Plan Update and seeking FEMA approval of the plan include:

The County of Yolo (Base Plan)
Susan Hensley, Emergency Services Coordinator, Office of Emergency Services Kristin Weivoda, Chief of Emergency Services, Office of Emergency Services Tonia Murphy, Procurement Manager, Yolo County General Services Jason Roberts, Emergency Preparedness Coordinator, Health and Human Services Agency April Meneghetti, Director of Environmental Health, Community Services Department The City of Davis (Jurisdictional Annex)
Jean Lyon, Deputy Director of Police Services
Joseph Tenney, Fire Chief
Benton Best, University of California, Davis - Campus Emergency Manger The City of West Sacramento (Jurisdictional Annex)
Brenna Howell, Emergency Services Coordinator
Bryan Johnson, Fire Marshal
The City of Winters (Jurisdictional Annex)
Jack Snyder, Fire Chief
John Miller, Police Chief
The City of Woodland (Jurisdictional Annex)
Eric Zane, Fire Chief
The Yocha Dehe Wintun Nation (Jurisdictional Annex)
Shawn Kinney, Fire Chief
Sarah Morgan, Natural Resources Manager
Sofia Ortiz, Administrative Assistant
Special Districts:

Joint Reclamation District 108 (Sacramento River West Side Levee District, Knights Landing Ridge Drainage District, Dunnigan Water District) – (Jurisdictional Annex) Meegan Nagy, Deputy Manager RD108
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50 Section 2: Planning Process Yolo County Operational Area Elizabeth Ramos, Civil Engineer – Overall HMP Project Manager William Vanderwaal, Deputy Manager RD108 and General Manager Dunnigan Water District Lewis Bair, General Manager, Sacramento River West Side Levee District and Knights Landing Ridge Drainage District
Cathy Busch, Executive Secretary, Sacramento River West Side Levee District and Knights Landing Ridge Drainage District
Reclamation District 787 (Fair Ranch) – Jurisdictional Annex Meegan Nagy, Deputy Manager
Elizabeth Ramos, Civil Engineer
Brian Gee, Junior Civil Engineer
Dominic Bruno, General Manager Reclamation District 787 Roger Cornwell, Member of the Board Reclamation District 787 Yolo County Flood Control & Water Conservation District – Jurisdictional Annex Jennifer Reed, Project Manager
Kristen Sicke, General Manager
During the response phase, the agencies that are charged with responsibilities in this plan focus on the following five goals:
• Mitigate hazards.
• Meet basic human needs.
• Address needs of people with disabilities and other access and functional needs. • Restore essential services.
• Support community and economic recovery.

The Yolo County Office of Emergency Services (OES) was delegated with the role of lead agency for the coordination and facilitation of the joint multi-jurisdictional hazard mitigation plan update. Yolo County OES functioned as the central point of contact for all partnering jurisdictions and organizations, as well as the liaison between the Yolo Operational Area and the State regarding plan revision. Finally, OES performed the bulk of actual plan format and development, in conjunction with the Steering and Planning Committee members.

Counties that border Yolo as well as regional partners, were also invited to participate in the planning efforts through a discussion of natural hazards that could impact neighboring jurisdictions. Given that natural hazards from a bordering county could affect Yolo, neighboring counties were invited to participate in the planning process to discuss and determine hazards that affect Yolo County as well as discuss hazards that neighboring counties identified that could affect Yolo County. The Counties that border Yolo County as well as regional partners, who 233
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51 Section 2: Planning Process Yolo County Operational Area were invited to participate in the planning process include: (see Appendix A for more information). Their participation was crucial in discussing cross-jurisdictional hazards and future collaborative mitigation projects and efforts.

Regional/Neighboring County Partners:

Sutter County
Zachery Hamill, Emergency Operations Manager
Sacramento County
Daniel Bowers, City of Sacramento
Mary Jo Flynn, Emergency Operations Coordinator
Solano County
Tina De Leon, Assistant Emergency Services Manager
Jenny Novelli, Emergency Services Coordinator
Napa County
Brieanna Jones, Emergency Services Officer
Colusa County
Kristopher Cooper, Lieutenant Support Services
Lake County
Leah Sautelet, Emergency Services Manager
Glenn County
Amy Travis, Deputy Director OES
Sonoma County
Jeff DuVall, Director of Emergency Management
Placer County
David Atkinson, Assistant Director of Emergency Services Regional Disaster Medical Health Specialist, Region IV
Brian Cross, RDMHS II
Jared Gunter, RDMHS I

2.2 STEERING COMMITTEE
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52 Section 2: Planning Process Yolo County Operational Area Yolo County decided to broaden the Steering Committee Members to include selected members to represent a cross-section of views and interests within the planning area. Email notifications were sent out to each HMP Steering Committee member to solicit their participation in the HMP Steering Committee meetings.

The HMP Steering Committee agreed to make and pass plan-based general policy recommendations by a vote of a simple majority of those members present. The Committee will also seek input on future hazard mitigation programs and strategies from a representative from each of the participating jurisdictions.
• Contact and work with each Hazard Mitigation Strategy's Lead Agency for an annual progress report on funding and implementation of the program recommended. • Receive an annual report from each jurisdiction on the status of the strategies adopted and implemented.
• Meet annually to identify new hazard mitigation strategies to be pursued by jurisdictions, and review the progress and implementation of those programs already identified. • Meet annually to review the progress of the Hazard Mitigation program and bring forth community input on new strategies.
• Coordinate with and support the efforts of the Yolo County Office of Emergency Services to promote and identify resources and grant money for implementation of recommended hazard mitigation Strategies within local jurisdictions and participating public agencies.

Members of the Steering Committee include:

Dignity Woodland Memorial Hospital
Lorraine Todden, Safety Manager, Environment of Care, PBX, and Emergency Preparedness/Management
Fire Representative
Breanna Howell, Emergency Services Coordinator, City of West Sacramento Fire Department Flood District Representative
Kristin Sicke, General Manager, Yolo County Flood Control and Water Conservation District Police Representative
Darren Pytel, Police Chief, City of Davis Police Department Rural Fire Representative
David Garrison, Fire Chief, Dunnigan Fire
Sutter Davis Hospital
Vinnie Ryan, RN Nursing Supervisor
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53 Section 2: Planning Process Yolo County Operational Area Tribal Representative, Yocha Dehe Wintun Nation
Shawn Kinney, Fire Chief, Yocha Dehe Wintun Nation Fire Department Yolo Commission on Aging and Adult Services
Jim Bohon
Yolo County, County Administrators Office
Mark Bryan, Deputy Chief Administrative Officer
Yolo County Climate Action & Sustainability Program
Kristen Wraithwall, Sustainability Manager
Yolo County Fire Safe Council
Tanya Meyer, Senior Program Manager
Yolo County, Health and Human Services Agency
Julie Cross, Executive Assistant, Yolo County Health and Human Services Agency Yolo County Housing Authority
Ian Evans, Executive Director
Yolo County In-Home Support Services Advisory Committee Kate Laddish, Chair
Yolo County Office of Education
Garth Lewis, Yolo County Superintendent of Schools
Yolo County, Office of Emergency Services
Susan Hensley, Emergency Services Coordinator
Yolo County Public Health, Emergency Medical Services Agency Douglas Brim, Emergency Medical Services Administrator
Yolo County Sheriffs Office
Sam Machado, Sheriffs Operational Area Coordinator
The HMP Steering Committee will meet and review the mitigation recommendations and strategies identified within this plan:
• This Committee will support the recommendations adopted by each jurisdiction for implementation and coordination on a state and regional basis. • Each jurisdiction will review and adopt, as necessary, the work of the Committee on an annual basis.
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54 Section 2: Planning Process Yolo County Operational Area • The Committee will review the progress reports on the implementation of the adopted hazard mitigation strategies brought forth by participating local and tribal government entities within the Yolo Operational Area.
• As required under prevailing state and federal requirements, this plan will be reviewed and updated on a five-year cycle. The strategies may be updated based on changing priorities and relieved constraints as identified below.

When constituted and organized, local hazard mitigation Steering Committees or entities may perform the following mitigation functions to meet local goals and objectives:
• Continue to review and assess local hazard mitigation needs and capacities in conjunction with this plan and other supporting documents and information. • Revise key local mitigation data and information.
• Receive and process supplemental and supporting hazard mitigation reference information and guidance as released by the state and/or FEMA. • Provide guidance to local emergency management in the integration of adopted risk information and adjustments to local mitigation activities. • Provide local hazard mitigation information and guidance to resident populations, inquiring organizations, vendors, and other interested parties. • Provide information and guidance to the local governing body relative to hazard mitigation issues, needs, gaps, and project activities.

2.2.1 STEERING COMMITTEE TASKS
Specific tasks were identified for the Steering Committee to ensure that project goals for the MJHMP revision were undertaken and completed. The following represents those primary Steering Committee tasks:
• Coordinate tasks and activities with the Office of Emergency Services to develop allhazards disaster mitigation plan and oversee the planning process. • Prioritize hazards vs. resources.
• Select highest and best mitigation recommendations and develop those recommendations for further action by the Yolo Operational Area.
• Review planning drafts, recommendations and updates.
• Develop and implement long and short-term goals.
• Integrate the plan with all phases of comprehensive emergency management planning. • Provide for the implementation of committee decisions. • Encourage, coordinate and provide a methodology for the implementation of public input. • Provide for the implementation of committee decisions. • Establish Hazard Mitigation Steering Committee Tasks to Include but not be limited to the following:
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55 Section 2: Planning Process Yolo County Operational Area o Determine implementation ability and constraints for proposed Hazard Mitigation planning steps and development of strategies.
o Bring forward community concerns through private and public input. o Identify implementation resources.
o Evaluate and carry out mitigation activities.
o Assist in implementation of funding identification and procurement. o Ensure that adjacent jurisdictions, pertinent private entities and citizens are informed of the Yolo Operational Area Hazard Mitigation Planning Process and offer each the opportunity for input into the plan.

2.2.2 STEERING COMMITTEE FUTURE TASKS
Specific future tasks were identified for the Steering Committee to ensure that project goals for the HMP revision were continued. The Steering Committee will continue to meet on a tri-annual meeting schedule to identify hazard priorities and review local hazard mitigation strategy recommendations. The following represents those primary Steering Committee future tasks:
• Define the mitigation constraints that the Yolo Operational Area is required to follow in implementing recommendations from the Hazard Mitigation Steering Committee. o Protection of sensitive information
o Apply budget constraints to recommended hazard mitigation strategies. o Apply state policy and legal constraints to mitigation strategies brought forward by the Steering Committee.
• Meet on an annual basis to review the work of and contribute to the Yolo Operational Area Hazard Mitigation Steering Committee activities.
• Bring forth the concerns and views of the community to the Steering Committee for consideration in the ongoing Hazard Mitigation planning process. • Assist in informing the public and community of the Hazard Mitigation strategies recommended by both the Steering Committee and individual jurisdictional Steering Committees.
• Define the constraints for implementation of prioritized mitigation strategies within the authorities, laws, and regulations of the local and tribal government entities existing within the Yolo Operational Area.
• Carry out the goals and objectives of the Yolo Operational Area Multi- Jurisdictional Hazard Mitigation Plan.
• Support and review the input from meetings of the adjunct members with individuals, agencies and jurisdictions.
• Assure that the public is kept informed of changing strategies and implementation actions periodically.

2.3 STAKEHOLDER ENGAGEMENT
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56 Section 2: Planning Process Yolo County Operational Area Per 44 CFR Section 201.6(b)(2), the planning process included 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 non-profit interests to be involved. Agencies from whom stakeholders were invited to participate in the 2023 MJHMP update process include:
• Yolo County Transportation District
• CalFIRE
• Pacific Gas & Electric
• Sutter Davis Hospital
• Dignity Woodland Memorial
Hospital
• University of California, Davis
• Yocha Dehe Fire Department
• Winters Fire Department
• Winters Police Department
• Arbuckle Fire Department
• Capay Valley Fire Department
• Dunnigan Fire Department
• Esparto Fire Department
• Madison Fire Department
• Yolo Emergency Communications
Agency
• West Plainfield Fire Department
• Zamora Fire Department
• California Highway Patrol
• American Red Cross
• Yolo County Fairgrounds
• Yolo County School District
• Esparto Community Services District
• City of Davis Fire Department
• UC Davis Fire Department
• City of Woodland Fire Department
• City of West Sacramento Fire
Department
• Community Medical Centers
• Elica Health Centers
• Northern Valley Indian Health
• Yolo Commission on Aging
• Yolo Hospice
• Yolo County Sheriff’s Department
During the 2023 MJHMP update process, stakeholders were invited via invitation email to each HMP meeting.

2.4 PUBLIC INVOLVEMENT
Due to significant staff turnover in the lead coordinating agency from 2019-2023, there were significant gaps in the HMP Process including an initial public meeting November 2018 (see Appendix A for documentation) and minor progress made in the subsequent years until 2022. No public meetings were held between 2018-2023. However, since the hiring of dedicated staff to hazard mitigation planning in 2022, there has been several opportunities for the public to comment on the planning process during the 2018 HMP update process. A plan that reflects the community’s values and priorities is likely to have greater legitimacy and “buy-in” and greater success in implementing mitigation actions and projects to reduce risk. In 2022, Public surveys soliciting community input on their perceived threats, hazards, and mitigation ideas were 239
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57 Section 2: Planning Process Yolo County Operational Area distributed through press releases, on social media, County Website, and through HMP Stakeholders group (see Appendices).

The development of the Steering Committee provided another avenue of community input as committee members would report back to their stakeholders regarding plan updates, and opportunities for feedback and input. Public meetings were held after the first plan draft was completed to solicit feedback and comments, as well as a final public meeting after public comments and feedback were incorporated prior to submission for FEMA review. Notices for these public meetings were posted on the Yolo County website, as well as media outlets and social media sources.

Public meetings were conducted at various locations and times to allow for underserved communities as well as vulnerable populations to attend and provide feedback and comments. In particular for the 2023 MJHMP Update, there were significant efforts to incorporate input from the aging population, those with access and functional needs, and those who reside in the unincorporated areas. We included various locations and times for the public meetings such as in an unincorporated area, senior centers during the daytime, as well as a zoom option for those who may not be able to attend an in-person meeting due to varying factors and circumstances (see appendix for more information)

2.4.1 INTEGRATION OF PUBLIC INPUT
At the onset of the 2023 MJHMP Update in 2022, a Community Survey was created and distributed via press release and through existing governmental websites (see Appendix A) to solicit public input on the general perception of threats within their community, the importance of individual preparedness, and the level of hazard mitigation. Information collected from this survey was analyzed by the Hazard Mitigation Steering Committee and County OES staff and used to help identify public concern and perceptions on identified threats. A public facing platform was also created to highlight the public’s concerns and perceptions on hazards and threats in their communities and educating the public on Hazard Mitigation efforts and opportunities.

Jurisdictions were also encouraged to solicit input in their hazard vulnerability analyses. As planning committee members developed their individual hazard prioritization matrices, the information from their respective communities was also considered in formulating the hazard list and subsequent analysis of each of those hazards. The result was a listing of High, Moderate and Low Risk Priority natural hazards that can or could impact the Yolo Operational Area. Out of that general assessment, prioritized mitigation strategies, with identified implementation projects, and was developed by inter-jurisdictional consensus. The public meetings gave the public an opportunity to learn about Hazard Mitigation, the identified hazards within their communities, and an opportunity to provide feedback into mitigation project ideas. The public was also given one month to review the draft 2023 MJHMP update and provide feedback to the lead 240
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58 Section 2: Planning Process Yolo County Operational Area coordinating agency for the 2023 MJHMP Update (see appendices for Public Meeting documentation). All comments and feedback were then incorporated into the 2023 MJHMP Update prior to submission to FEMA for review.

2.4.2 CONTINUED PUBLIC INVOLVEMENT
The Yolo Operational Area Hazard Mitigation Steering Committee has made the commitment to periodically bring this plan before the public through public meetings and community posting so that citizens may make input as strategies and implementation actions change. Public meetings will continue to be held annually. As well as an Annual Report on Hazard Mitigation Updates will be distributed Annually to inform the public of any Hazard Mitigation project updates or Plan updates. The public will continue to be invited to public meetings via social media messaging, newspaper invitations, and through the website for each jurisdiction participating in the plan. Each jurisdiction including the Cities of Davis, West Sacramento, Winters, Woodland and the Yocha Dehe Wintun Nation is responsible for assuring that their citizens are informed when deemed appropriate by the Steering Committee.

Yolo County Office of Emergency Services will also maintain a website to keep the public informed on plan updates, mitigation projects, and contain GIS Mapping resources for hazard mitigation awareness (see Section 6.0 “StoryMap” for more information).

2.5 INCORPORATION OF 2018 HMP INTO EXISTING PLANS
Hazard Mitigation planning must include review and incorporation, if appropriate, of existing plans, studies, reports, and technical information (44 CFR, Section 201.6 (b)(3)). Section 4.0 of this plan provides a review of laws and ordinances in effect within the planning area that can affect hazard mitigation actions.

Yolo County planning efforts are supportive of each other. Information from the Yolo County MJHMP is incorporated into and used to support the 2030 Yolo County General Plan, Yolo County Climate Action and Adaptation Plan, Yolo County Emergency Operations Plan, and the continuity plans for each County and jurisdictional department. Many of these planning efforts incorporate all Yolo County jurisdictions and special districts (i.e. flood response plans for each city and Reclamation District with their input). Yolo County coordinates emergency plans with all four cities in Yolo County, the Yocha Dehe Wintun Nation, and the Housing Authority of Yolo County; information from the MJHMP (including the risk assessment) is incorporated into each of their city’s Emergency Operations Plans and accompanying hazard annexes as well as their city’s continuity plans. Information from several of these plans were used to support the Yolo County MJHMP update as well.

The 2018 Yolo County Hazard Mitigation plan was incorporated into several County-wide planning mechanisms, as shown in the table below.
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Planning Mechanism 2018 HMP Was
Incorporated/Implemented In.

Details: How was the 2018 plan incorporated? How
the 2023 plan will be incorporated?
2030 Yolo County General Plan Health and Safety Element – The 2018 HMP was used to update and amend the General Plan. When
the 2023 HMP update is approved, the Health and
Safety element will be updated and the General Plan
Amended.
2023 Yolo County HMP Update Used original existing data sources from 2018 HMP to update 2023 HMP, Critical infrastructure
identification from 2018 HMP.

Yolo County EOP 2017 2018 HMP was used to determine hazards. Once the 2023 HMP update is approved, the Yolo County
EOP will also be updated with respective hazards
and vulnerabilities identified.

Community Rating System (CRS) Used document to support CRS reporting and compliance. Cycle verification to increase CRS
rating will occur in 2024, upon completion of the
2023 HMP Update.
5th Cycle Housing Element Housing Plan, 2013-
2021
Used 2018 HMP hazard data to review building
codes and current housing development plans. 2023
HMP hazard data will incorporate into the 6th cycle
housing element plan.

In addition, the following programs can affect mitigation within the planning area:
• Housing Element 2013-2021, 5th Cycle Housing Element Housing Plan • Housing Element 2021-2029, 6th Cycle Housing Element Housing Plan • California Fire Code
• 2022 California Building Code
• California State Hazard Mitigation Forum
• Capital Improvement Programs
• Yolo County Land Development and Zoning Ordinances
• Yolo County Floodplain Ordinances
Following the 2023 HMP update approval, data and information from the HMP will be further incorporated into these programs. Hazard information from the 2023 HMP incorporates into the Climate Action and Adaptation plan, sharing hazard and vulnerability information and incorporating information on how climate change affects hazards. 242
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SECTION 3.0: HAZARD IDENTIFICATION AND RISK

ASSESSMENT
The Federal Emergency Management Agency (FEMA) defines risk as a combination of hazard, vulnerability, and exposure. “It is the impact that a hazard would have on people, services, facilities, and structures in a community and refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.” The risk assessment process identifies and profiles relevant hazards and assesses the exposure of lives, property, and infrastructure to these hazards. This process allows for a better understanding of a community’s potential risk to natural hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

Yolo County is at risk from a variety of potential hazards: natural, technological and human conflict related. Many of these hazards, under the right circumstances, could result in a disastrous impact to the county. However, for the purposes of the 2023 MJHMP Update, the Operational Area focused this risk assessment on natural hazards and covers the entire geographical extent of the Yolo County Operational Area, including the incorporated communities, unincorporated communities, special districts, and other participating jurisdictions. This section of the HMP will look at both hazards and vulnerabilities. In accordance with FEMA requirements, this risk assessment describes how the hazards and risks vary across the Operational Area and from jurisdiction to jurisdiction. Specific hazards and risks for each jurisdiction is expanded upon in the annexes of the participating jurisdictions in Volume 2. If no additional data is provided in an annex, it should be assumed that the risk and potential impacts to the affected jurisdiction are like those described here for the entire Yolo County Operational Area.

This 2023 MJHMP Update involved a review and update of each section of the 2018 risk assessment. Information from the 2018 HMP was used in the Update were valid and applicable.

As part of the risk assessment update, new data was used, where available, and new analyses were conducted where appropriate. Where data from existing studies and reports were used, the source is referenced throughout this risk assessment.

3.1 HAZARD IDENTIFICATION
In the early meetings with Yolo County and the Planning and Steering Committee, data was reviewed from previously prepared hazard mitigation plans and other relevant documents to determine the realm of natural hazards that have the potential to affect the county and the nearby region. These sources were:
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 Federal Disaster Declaration Database
 State Disaster Declaration History
 State of California Office of Emergency Services (CalOES)  State of California Hazard Mitigation Plan (2018, 2023)  National Oceanic and Atmospheric Administration (NOAA)  National Climatic Data Center (NCDC)
 FEMA National Risk Index
 California’s Fourth Climate Change Assessment: Sacramento Valley Region Report  CalOES Hazard Exposure and Social Vulnerability Map
 2018 Yolo County Hazard Mitigation Plan
This initial analysis provided a preliminary hazard list, providing a framework for the Planning and Steering committee to evaluate which hazards were truly relevant to participating jurisdictions and which hazards should be omitted.

The process of identifying hazards that do or could potentially affect Yolo County at various levels was the next step in assessing overall risk. Recognizing the potential required an analysis of known, suspected, and emerging hazards existing within or directly affecting the Yolo OA.

This also involved a discussion with neighboring jurisdictions to assess the natural hazards that impact neighboring jurisdictions and their impacts on Yolo County. Some of the following questions were used during the analysis:
• What are the known hazards?
• What are the suspected hazards?
• What are the potentially emerging hazards?
• What are the elements of the hazard?
• What are the conditions associated with the occurrence of a hazardous event? • What factors are required for an event to turn hazardous?

3.1.1 HAZARD PRIORITIZATION AND RISK RANKING
FEMA requires all hazard mitigation planning partners to have jurisdiction-specific mitigation actions based on local risk, vulnerability, and community priorities. This plan included a risk ranking protocol for each participating jurisdiction, in which “risk” was calculated by adding the extent of hazard, the likelihood of future occurrence, the severity, and the impact on people, property and the economy.

Planning partners were directed to identify mitigation actions addressing hazards that had a “high” and “moderate” degree of risk ranking. Those hazards identified as a high or medium significance are considered priority hazards for mitigation planning. Those hazards that occur 244
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infrequently or have little or no impact on the Operational Area were determined to be low significance and not considered a priority hazard (see Table 3-3 for omitted hazards). This assessment was used by the Planning and Steering Committees to prioritize those hazards of greatest significance to the Yolo County Operational Area, enabling the County to focus resources where they are most needed.

Variables were based on FEMA, Local Mitigation Planning Handbook. The following variables, questions, and guidance shaped the ranking on the matrices:

Geographic Extent: What geographic area is affected by this hazard?

1. Negligible: No known or negligible geographic extent

2. Limited: Less than 10% of Planning Area

3. Significant: 10-50% of Planning Area

4. Extensive: 50-100% of Planning Area
Likelihood of Future Occurrences: What is the likelihood of a hazard event occurring each year?

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

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

3. Likely: Between 10 and 100% chance of occurrence in next year or has a recurrence interval of 10 years or less.

4. Highly Likely: Near 100% chance of occurrence in next year or happens every year.

Magnitude/ Severity: What is the expected magnitude and severity of the hazard event based on historic events or future probability?

1. Negligible: Less than 10% of property severely damaged, shutdown of facilities and services for less than 24 hours; and/or injuries treatable with first aid

2. Limited:10-25% of property severely damaged; shutdown of facilities for more than a week; and/or injuries treatable do not result in permanent disability

3. Critical: 25-50% of property severely damaged; shutdown of facilities for at least two weeks; and/or injuries and/or illnesses result in permanent disability

4. Catastrophic: More than 50% of property severely damaged; shutdown of facilities for more than 30 days; and/or multiple deaths
Significance: In terms of injuries, damage, or death, would you anticipate impacts to be negligible, limited, critical, or catastrophic when a significant hazard event occurs?

1. Low: minimal potential impact
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2. Medium: moderate potential impact

3. High: widespread potential impact

RANKING METHODOLOGY
To determine the rank, each variable was weighted on a scale from 0-4, 0=none, to 4=highly likely/catastrophic/extreme. Each hazard was ranked based n the probability/likelihood of future occurrence, geographic extent, impact (magnitude/severity) to property, resources and human impact, and the mitigation capacity in terms of preparedness, internal response, and external response. The risk score was the determined by multiplying the probability by the extent and total impact and subtracting that total from the sum of the mitigation capacity. Scores on each variable were added together to determine a score between 0 and 12. (see Appendix for sample spreadsheet for Hazard Vulnerability Analysis)
Degree of risk was determined by a total risk score of:
 High: 10-12
 Moderate: 7-9
 Possible: 4-6
 Negligible: 1-3
Severity of damage uses a basic scale of high, moderate, and possible. Severity of damage is based on hazard risk assessments, previous occurrences/incidences and other historical data, and mitigation measures that may/may not be in place.

3.1.2 RESULTS
Using existing hazards data and input gained through jurisdictional hazard vulnerability assessments, the HMP Steering Committee and Planning Committee agreed upon a list of hazards that could affect Yolo County Operational Area. Hazards data from CalOES, FEMA, the NOAA NCDC database, and many other sources were analyzed to assess the significance of these hazards to the Operational Area.

The following hazards in Table 3-1, lists the Hazard Rankings that were identified and investigated for this 2023 HMP Update. As a starting point, the 2023 California State Hazard Mitigation Plan was consulted to evaluate the applicability of hazards of concern to the State, to the Yolo County Operational Area. Building upon this effort, hazards from the 2018 Yolo Operational Area HMP were also identified, and comments explain how hazards were updated from this 2018 HMP. Most natural hazards from the 2018 plan were profiled in this 2023 MJHMP Update. Certain hazards were omitted from consideration for this 2023 MJHMP Update due to either their low probability of occurrence, minimal impact, or lack of mitigation actions. 246
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They are shown in Table 3-3. For the 2023 Plan update, Climate change impacts were also incorporated into relevant hazards rather than analyzed as a separate hazard.

Although Yolo County Operational Area recognizes that should these hazards occur, it would impact Yolo County Operational Area. They were determined to have low significant impacts and thus removed from analysis for the 2023 MJHMP Update.

Table 3-1: 2023 Yolo County Operational Area Hazard Rankings Ranking Hazard Risk Score Degree of Risk
1 Levee Failure 12.0 High
2 Wildfire 9.75 High
3 Drought 8.81 Moderate
4 Severe Weather: Extreme Heat 7.75 Moderate
5 Flooding 7.13 Moderate
6 Severe Weather: High Wind 6.5 Possible
7 Dam Failure 6.25 Possible
8 Earthquake 5.5 Possible
9 Severe Weather: Freeze 4.56 Possible
10 Land Subsidence 4.25 Possible
11 Severe Weather: Fog 0.26 Negligible
12 Severe Weather: Tornado 0.13 Negligible
13 Landslide 0 Negligible
14 Volcano 0 Negligible
Table 3-2: Yolo County Hazard Identification Assessment with Degree of Risk Hazard
Geographic
Extent
Likelihood of
Future
Occurrences
Magnitude/
Severity Significance
Degree of
Risk
Profiled
(Y/N)?
Dam Failure Extensive Unlikely High High Possible Yes
Drought Significant Likely Moderate High Moderate Yes
Earthquake Limited Likely Possible Medium Possible Yes
Flooding Extensive Likely High High Moderate Yes
Landslide Limited Unlikely Negligible Low Negligible No Land Subsidence Limited Likely Negligible Medium Possible Yes Levee Failure Extensive Likely High High High Yes
Severe Weather:

Extreme Heat Extensive Highly Likely High* High Moderate Yes Severe Weather:

Freeze Extensive Likely Possible* Medium Possible Yes
Severe Weather:

Fog Significant Highly Likely Negligible Medium Negligible Yes Severe Weather:

High Wind Extensive Highly Likely High High Possible Yes Severe Weather:

Tornado Limited Occasional Possible Medium Negligible Yes 247
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Volcano Negligible Unlikely Negligible Low Negligible No Wildfire Limited Highly Likely Moderate Medium High Yes Geographic Extent
Negligible: Less
than 10% of
Operational Area
affected
Limited: 10-25% of
Operational area
affected
Significant:

Between 35-50% of
Operational area
affected
Extensive: 50-100%
of planning area
affected

Likelihood of Future Occurrences
Highly Likely: Near 100% chance of occurrence in next year, or happens every year.

Likely: Between 10 and 100% change 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 internal of 11 or 100 years.

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

Magnitude/Severity
High – More than 50% of property severely damaged; shutdown of facilities for more than 30 days; and/or multiple deaths.

Moderate – 25-50% of property severely damaged; shutdown of facilities for at least two weeks; and/or injuries and/or illness result in permanent disability.

Possible – 10-25% of property severely damaged; shut down of facilities for more than a week; and/or injuries/illnesses treatable to do not result in permanent disability.

Negligible – Less than 10% of property severely damaged, shutdown of facilities and services for less than 24 hours; and/or injuries/illness treatable with first aid. *incorporating agriculture and farm land as property
Significance
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact
Degree of Risk:

Degree of risk was determined by a total risk score of:

High: 10-12
Moderate: 7-9
Possible: 4-6
Negligible: 1-3
Table 3-3: Yolo County – Omitted Hazards
Hazard Excluded Why Excluded
Landslide
Yolo County has not experienced landslides directly, but could have secondary impacts due to landslides in neighboring counties. This impact would potentially be increased traffic into the County.

Volcano
The most likely volcanic hazard for Yolo County is the deposition of ash from an eruption in any of the volcanic areas. However due to the distance from volcanic areas, the likelihood of future occurrence, and the lack of mitigation actions from the County and participating jurisdictions, this hazard was omitted from consideration.

In the 2023 MJHMP Risk Assessment and Hazard Vulnerability discussions with the Planning and Steering Committee teams, it was decided to remove Non-Natural hazards from the Hazard Analysis and 2023 MJHMP Update. The reason for removing technological and human-caused hazards was in part to focus efforts on natural hazards and mitigation actions to reduce losses from those hazards. However, the 2023 MJHMP Planning and Steering Committee wanted to 248
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acknowledge the Technological and Human-caused hazards in the 2023 MJHMP Update without performing a full hazard analysis. The identified technological and human-caused hazards are described in Table 3-4: Technological and Human-Caused Hazards.

Table 3-4: Yolo County – Technological and Human-Caused Hazards Hazard Impact
Epidemic/Pandemic Some outbreaks that have occurred in Yolo County include Norovirus, Pertussis, Measles (UCDavis 2014), COVID-19, and a small number of cases of malaria, dengue fever, legionnaire’s disease, and typhoid have been found in Yolo County.

Hazmat Incidents:

Radiological Incidents
The only operating nuclear plant in California is the Diablo Canyon Nuclear Power Plant in San Luis Obispo County, over 300 miles away which is outside the Emergency Planning Zone and the Ingestion Pathway Zone for Diablo Canyon. Rancho Saco Nuclear Generating Station in Sacramento closed in 1989 but is still undergoing decommissioning as it still as spent fuel onsite.

Hazmat Incidents:

Chemical Incidents
There has been no major chemical incidents in Yolo County, however due to several incidents around the area in surrounding Sacramento County, these incidents have the ability to affect residents in Yolo who live near or work in Sacramento County.

Hazmat Incidents:

Biological Incidents
There has been no recorded hazmat biological incidents in and around Yolo County.

Transportation Accidents:

Vehicle Accidents
There are several major highways in Yolo County including Interstate 80, State Highway 113, 16, and 84. Multi-vehicle accidents would overwhelm responding units and cause multi-jurisdictional response.

Transportation Accidents:

Train Accidents
There are Class 1 railroads in Yolo County, with Amtrak and Burlington Northern and Santa Fe (BNSF) railroads operating on the Union Pacific (UP) owned line. There are no Class 2 railroads that operate in Yolo County. There are two Class 3 railroads that operate in Yolo County: Sierra Northern Railway and the California Northern Railroad. There have been no major train accidents in Yolo County with the last train derailment occurring in 1894.

Transportation Accidents:

Airplane Accidents
There are several airports and heliports in Yolo County, though none of them serve commercial flights. Sacramento International Airport is located approximately one mile east of the Yolo County border, and have several flight paths over Yolo County. Aviation accidents that have occurred over the years in Yolo County have been due to agricultural planes, like crop dusters, or personal plane issues such as engine failure.

Transportation Accidents:

Ship Accidents
Yolo County has two navigable waterways where large vessels can be found: the Sacramento River and the Sacramento Deepwater Ship Channel. The Deepwater Ship Channel connects the lower Sacramento River to the Port of West Sacramento. The only potential impacts from a ship incident in the Deepwater Ship Channel would be environmental damage due to excess ballast water or elements of the fueling system being released into the water.

Power/Utility Failure Numerous gas pipelines as well as gas and oil storage facilities exist in and around Yolo County.

Communications/IT
Failure
There have been a few instances of Comcast and fiber-optic lines being cut in 2015 which interrupted service to thousands of customers and residents.

Terrorism There have been several terrorist incidents and threats in Yolo County and the surrounded areas of Sacramento, the latest being in 2017.

Cybersecurity This is a new hazard that appeared on jurisdictional hazard vulnerability assessments. There has been effort to prepare for cybersecurity incidences throughout the County including increasing awareness and education on threats 249
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to cybersecurity.

Civil Disturbance The primary concern for Yolo County is the University of California Davis and large events that occur on the campus, as well as protests that have previously occurred there. Civil Disturbances have occurred in Woodland as well as areas around Yolo County.

Urban Conflagration There is potential for Urban Conflagration in Yolo County due to the high risk of wildfires that could spread into urban areas. Fire mitigation measures have been put in place to try to mitigate this hazard.

3.1.3 DISASTER DECLARATION HISTORY
One method to identify hazards is to look at the events that have triggered federal and/or state disaster declarations that included Yolo County. Federal and/or state disaster declarations may be granted when the severity and magnitude of an event surpasses the ability of the local government to respond and recover. Disaster assistance is supplemental and sequential. When the local government’s capacity has been surpassed, a state disaster declaration may be issued, allowing for the provision of state assistance. If the disaster is so severe that both the local and state governments’ capacities are exceeded, a federal emergency or disaster declaration may be issued allowing for the provision of federal assistance.

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

The following table lists the disaster declarations where Yolo County was designated federal and/or state disaster declarations since 1965. Details on federal and state disaster declarations were obtained by FEMA and CalOES and compiled in chronological order in Table 3-5. The USDA Disasters below are indicated as Primary or Contiguous designations for Yolo County.

Table 3-5: Yolo County State and Federal Disaster Declarations, 1965-2023 Year Disaster Name Disaster Type Disaster #
State
Declaration #
Federal
Declaration #
1965 Heavy rains & flooding Flood DR-183-CA - 12/24/1964 1977 Drought Drought EM-3023-CA - 1/20/1977
1983
Coastal storms, floods,
slides & tornadoes Coastal Storm DR-677-CA
- 2/9/1983
1986
Severe storms &
flooding Flood DR-758-CA
- 2/21/1986
1991 Severe freeze Freezing DR-894-CA - 2/11/1991
1995
Severe winter storms,
flooding landslides, mud
flow Severe Storm DR-1046-CA
- 3/12/1995
1995
Severe winter storms,
flooding, landslides,
mud flows Severe Storm DR-1044-CA
- 1/10/1995
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1997
Severe storms, flooding,
mud and landslides Severe Storm DR-1155-CA
- 1/4/1997
1998
Severe winter storms
and flooding Severe Storm DR-1203-CA
- 2/9/1998
2005
Hurricane Katrina
evacuation Hurricane EM-3248-CA
- 9/13/2005
2006
Severe storms, flooding,
mudslides, and
landslides Severe Storm DR-1628-CA
- 2/3/2006
2012 Drought Drought
USDA Primary
S3452
12/19/2012 -
2013
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3569
8/21/2013 -
2014 Tree Mortality Drought 10/30/2015 -
2014 Drought Drought
USDA Primary
S3743
9/17/2014 -
2014 Drought Drought
USDA
Contiguous
S3797
2/25/2014 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3637
1/23/2014 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK
USDA
Contiguous
S3626
1/15/2014 -
2015 Wragg fire Fire FM-5091-CA - 7/23/2015
2015
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3784
2/4/2015
2016
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK S3952
USDA Primary
2/17/2016
2016
Severe Weather – High
Winds, Excessive Rain Severe Weather S4164
USDA
Contiguous
3/3/2016
2017
Severe winter storms,
flooding, and mudslides Flood DR-4308-CA
- 4/1/2017
2017
Severe winter storms,
flooding, and mudslides Flood DR-4305-CA
- 3/16/2017
2017 Drought
Drought –
FAST TRACK S4163
USDA Primary
3/22/2017
-
2017
Severe winter storms,
flooding, and mudslides Severe Storm DR-4301-CA
3/7/2017 2/14/2017
2019 Excessive Rain
Excessive Rain,
moisture,
humidity S4656
USDA
Contiguous
3/11/2020
-
2019
Severe winter storms,
flooding, landslides, and
mudslides Severe Storm DR-4431-CA
USDA
Contiguous
5/1/2019
-
2019
Severe winter storms,
flooding, landslides, and
mudslides Severe Storm DR-4434-CA
USDA Primary
and Contiguous
5/17/2019
5/17/2019
2020
LNU lightning fire
complex Fire FM-5331-CA
8/18/2020 8/18/2020
2020 Wildfires Fire DR-4558-CA 8/22/2020 8/22/2020
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2020 Wildfires Fire DR-4569-CA
USDA
Contiguous
10/16/2020
-
2020 Drought
Drought –
FAST TRACK S4691
USDA
Contiguous
6/10/2020
-
2020 Drought
Drought –
FAST TRACK S4697
USDA Primary
6/16/2020
-
2020 Covid-19 Biological EM-3428-CA - 3/13/2020
2020 Covid-19 pandemic Biological DR-4482-CA - 3/22/2020 2021 Drought
Drought –
FAST TRACK S4916
USDA Primary
3/5/2021
-
2022 Drought
Drought-FAST
TRACK S5146
USDA Primary
4/8/2022
-
2022 Freeze
Severe weather
– Freeze S5229
USDA Primary
7/1/2022
-
2022 Freeze
Severe weather
– Freeze S5230
USDA
Contiguous
7/1/2022
-
2022 Freeze
Severe weather
– Freeze S5332
USDA Primary
11/4/2022
-
2023
Severe winter storms,
flooding, landslides, and
mudslides Flood DR-4683-CA
1/4/2023 1/14/2023
2023
Severe winter storms,
flooding, and mudslides Flood EM-3591-CA
1/4/2023 1/19/2023
2023
Severe winter storms,
flooding, and mudslides Flood DR-4699-CA
4/20/2023 4/3/2023

3.2 HAZARD PROFILES AND VULNERABILITY ASSESSMENT
The hazards identified in Section 3.1.1 Results and Methodology, are profiled individually in this section. These Hazard Profiles set the stage for the Vulnerability Assessment, where the vulnerability is quantified for each of the hazards. The methodologies for the Hazard Profiles and the Vulnerability Assessment is presented first in this section followed by the Hazard Profiles and Vulnerability Assessment for each identified hazard.

3.2.1 HAZARD PROFILES
Each hazard is presented in the following format:
 Hazard/Problem Description – This section gives a description of the hazard and associated issues followed by details on the hazard specific to the Yolo County Operational Area and the unincorporated County. Where known, this includes information on the hazard type, location, extent, and any secondary effects.  Past Occurrences – This section contains information on historical hazard events, including location, impacts, and damages where known. Hazard research, historical 252
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incident information, any state or federal major disaster declarations, and previous HMPs were used to capture information on past occurrences.
 Frequency/Likelihood of Future Occurrence – The frequency of past events is used in this section to gauge the likelihood of future occurrences. Where possible, frequency was calculated based on existing data. It was determined by dividing the number of events observed by the number of years on record and multiplying by 100. This gives the percent change of the event happening in any given year (e.g., three droughts over a 30- year period equates to a 10% chance of experiencing a drought in any given year). This likelihood of future occurrences is categorized into one of the following classifications:
o Highly Likely – Near 100 percent chance of occurrence in next year or happens every year.
o Likely – Between 10 and 100 percent chance of occurrence in next year or has a recurrence interval of 10 years or less.
o Occasional – Between 1 and 10 percent chance of occurrence in next 100 years of has a recurrence interval of greater than every 100 years. o 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 – this section contains the effects of climate change (if applicable). The possible ramifications of climate change on each hazard are discussed.

3.2.2 VULNERABILITY ASSESSMENT
With Yolo County’s hazards identified and profiled, a vulnerability assessment was conducted to describe the vulnerability and impact that each hazard would have on the County. The vulnerability assessment quantifies, to the extent feasible using best available data, assets at risk to identified hazards and estimates potential losses. This section focuses on the vulnerabilities of the Yolo County Operational Area as a whole, as well as the unincorporated Yolo County.

An estimate of the vulnerability of the Yolo County Operational Area and unincorporated Yolo County to each identified hazard provided in each of the hazard-specific vulnerability sections that follow. Vulnerability is measured in general, qualitative terms and is a summary of the potential impact based on past occurrences, geographical extent, assessing the damage and casualty potential of structures, facilities, and systems that are exposed to each hazard. It is categorized into the following classifications:
 Extremely Low – The occurrence and potential cost of damage to life and property is very minimal to nonexistent.
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 Low – Minimal potential impact. The occurrence and potential cost of damage to life and property is minimal.
 Medium – Moderate potential impact. This ranking carries a moderate threat level to the general population and/or built environment. Here the potential damage is more isolated and less costly than a more widespread disaster.
 High – Widespread potential impact. This ranking carries a high threat to the general population and/or built environment. The potential for damage is widespread. Hazards in this category may have occurred in the past.
 Extremely High – Very widespread with catastrophic impact.

Vulnerability can be quantified in those instances where there is a known, identified hazard area, such as mapped floodplain. In these instances, the numbers and types of buildings subject to the identified hazard can be counted and their values tabulated. Other information can be collected in regard to the hazard area, such as the location of community lifelines, historic structures, and valued natural resources. Social vulnerability was also examined including underserved communities and socially vulnerable populations (population under 15 years of age, population over 65 years of age, people of color, limited English-speaking households, persons with access and functional needs, families below the poverty level, renter occupied housing units). Together, this information conveys the impact, or vulnerability, of the Yolo County Operational Area to that hazard.

If there was sufficient data to support a quantifiable vulnerability analysis, hazards were analyzed using GIS and County Data. If the vulnerability and potential impacts from priority hazards did not have specific mapped areas nor data to support additional vulnerability analysis, vulnerability is discussed in more general terms.

The following sections provide the hazard profile and vulnerability assessments for each of the hazards identified. Severe Weather hazards are discussed first to paint the picture of the County’s climate and hazard environment, which often lead to other hazards such as flood, wildfire, and droughts. The remainder of the hazards follow alphabetically.

3.2.3 POWER SHORTAGE/FAILURE
An additional impact of extreme heat is power outage or power failure. Although power shortage and power failures are not a natural hazard, it has become a direct consequence of natural hazards such as extreme heat, high winds, freeze/cold weather, and wildfires. To appreciate the impacts of these natural hazards on power shortages/failures, more detail is provided in this section.
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According to statistics gathered by the Department of Energy, major blackouts have impacted at least 50,000 customers in the past two decades. It’s important to recognize different types of outages so that plans may be made to handle them effectively. Electric power disruptions can be generally grouped into two categories: intentional and unintentional.

INTENTIONAL DISRUPTIONS
There are four types of intentional disruptions:
• Planned: Some disruptions are intentional and can be scheduled based on maintenance or upgrading needs.
• Unscheduled: Some intentional disruptions must be done immediately in response to an emergency.
• Demand-Side Management: Some customers (i.e., on the demand side) have entered into an agreement with their utility provider to curtail their demand for electricity during periods of peak system loads.
• Load Shedding: When the power system is under extreme stress due to heavy demand and/or failure of critical components, it is sometimes necessary to intentionally interrupt the service to selected customers to prevent the entire system from collapsing, resulting in rolling blackouts.

The California Independent System Operator (CAISO) is tasked with managing the power distribution grid that supplies most of California, except in areas served by municipal utilities.

CAISO is thus the entity that coordinates statewide flow of electrical supply. CAISO uses a series of stage alerts to the media based on system conditions. The alerts are:
• Stage 1 – reserve margin falls below 7 percent.
• Stage 2 – reserve margin falls below 5 percent.
• Stage 3 – reserve margin falls below 1.5 percent.

Rotating blackouts become a possibility when Stage 3 is reached. Rotating outages and/or blackouts such as those experienced in 2000/2001 and 2006 can occur due to losses in transmission or generation and/or extremely severe temperatures that lead to heavy electric power consumption.

On January 17, 2001, CAISO declared a Stage 3 Emergency and notified the Governor’s Office of Emergency Services (Cal OES) that PG&E was dropping firm load of 500 megawatts (MW) in Northern California leading to rolling blackouts. Cal OES, in turn issued an Electrical Emergency Message to all Emergency Services Agencies to prepare for rolling blackouts. This situation occurred again on January 18, 2001, and March 19, 2001. 255
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More recently, in 2020, due to Statewide extreme heat and wildfires, the CAISO declared a Stage 3 emergency in which PG&E then initiated rotating outages in August at the request of California’s grid operator. The outages impacted 220,000 customers and occurred during periods of high heat.

UNINTENTIONAL DISRUPTIONS
Unintentional or unplanned disruptions are outages that occur with no advanced notice. These disruptions can be caused by:
• Accident by the utility, utility contractor, or others • Malfunction or equipment failure.
• Equipment overload (utility company or customer)
• Reduced capability
• Tree contact
• Vandalism or intentional damage
• Weather, including lightning, wind, earthquake, flood, and broken tree limbs taking down power lines.
• Wildfire that damages transmission lines

PUBLIC SAFETY POWER SHUTOFF (PSPS)
Since the 2018 HMP Update, a new intentional disruption type of power shortage/failure is the Public Safety Power Shutoffs. In response to several wildfires that started because of downed power lines or electrical equipment, California’s largest energy companies, at the direction of the California Public Utilities Commission (CPUC), shut off electric power during extreme weather events in an effort to prevent a wildfire. PG&E were one of the energy companies that started to announce PSPS events whenever there were certain criteria that were met, such as:
• A Red Flag Warning declared by the National Weather Service • Low humidity levels generally 20% and below
• Forecasted sustained winds generally above 25 mph and wind gusts more than approximately 45 mph, depending on location and site-specific conditions such as temperate, terrain, and local climate.
• Condition of dry fuel on the ground and live vegetation (moisture content) • On-the-ground, real time observations from PG&E’s Wildfire Safety Operations Center and field observations from PG&E crews.
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Although no single factor would drive a PSPS event, these were the factors that would be considered if a PSPS event were to occur. The electric lines that would be most likely considered for shutting off for safety will be those that pass-through areas that have been designated by the CPUC as at elevated (Tier 2) or extreme (Tier 3) risk for wildfire (see Figure 3-1 below). This would include both distribution and transmission lines. The specific area and number of affected customers will depend on forecasted weather conditions and which circuits PG&E needs to turn off for public safety. Although a customer may not live or work in a high fire threat area, their power may also be shut off if their community relies on a line that passes through an area experiencing extreme fire danger conditions.
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Figure 3-1: CPUC Fire-Threat Map
Source: State of California – Public Utilities Commission 258
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PG&E noted that although extreme weather threats can change quickly, whenever possible, PG&E will provide customers with advance notice prior to turning off the power, as well as updates until power is restored. Timing of notifications (when possible) are:
• Approximately 48 hours before power is turned off
• Approximately 24 hours before power is turned off
• Just before power is turned off
• During the public safety outage
• Once power has been restored
Previous PSPS events that have affected Yolo County include:

Table 3-6: Previous PSPS Events affecting Yolo County
Date of Occurrence Areas affected
# of Critical
Customers
#of Medical Baseline
Customers
October 2019 Dunnigan, Madison, Woodland,
Capay, Esparto, Winters, Davis,
Rumsey, Guinda, Brooks
33 221

3.2.4 CLIMATE CHANGE
Climate change is the distinct change in measures of weather patterns over a long period of time, ranging from decades to millions of years. More specifically, it may be a change in average weather conditions such as temperature, rainfall, snow, ocean and atmospheric circulation, or in the distribution of weather around the average. While the Earth’s climate has cycled over its 4.5- billion-year age, these natural cycles have taken place gradually over millennia, and the Holocene, the most recent epoch in which human civilization developed, has been characterized by a highly stable climate – until recently.

This MJHMP is concerned with human-induced climate change that has been rapidly warming the Earth at rates unprecedented in the last 1,000 years. Since industrialization began, the burning of fossil fuels (coal, oil, and natural gas) at escalating quantities has released vast amounts of carbon dioxide and other greenhouse gases responsible for trapping heat in the changes in precipitation patterns, the global water cycle, melting glaciers and ice caps, and rising sea levels. According to the Intergovernmental Panel on Climate Change (IPCC), climate change will “increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems” if unchecked.

Through changes to oceanic and atmospheric circulation cycles and increasing heat, climate change affects weather systems around the world. Climate change increases the likelihood and exacerbates the severity of extreme weather – more frequent or intense storms, floods, droughts, 259
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and heat waves. Consequences for human society include loss of life and injury, damaged infrastructure, long-term health effects, loss of agricultural crops, disrupted transport and freight, and more. Climate change is not a discrete event but a long-term hazard, the effects of which communities across California are already experiencing.

Climate change adaptation is a key priority of the State of California. The 2013 State of California Multi- Hazard Mitigation Plan stated that climate change is already affecting California, and in 2015, Assembly Bill 1482 (Gordon) mandated the development of the California Climate Adaptation Strategy, a comprehensive plan linking together the state’s existing and planned climate adaptation efforts, showing how they fit together to achieve California’s six climate resilience priorities. According to the Strategy’s 2022 Progress report, since 1895, annual average air temperatures in California have increased by about 2.5 degrees Fahrenheit (°F) and eight of the ten warmest years on record occurred between 2012 and 2022.

Extreme heat events have stressed the electrical grid to its limits and have impacted human health and wellbeing.

Sea levels have risen by as much as eight inches along the California coast over the last century, increasing erosion and pressure on the state’s infrastructure, water supplies, and natural resources. The State has also seen increased average temperatures, more extreme hot days, fewer cold nights, a lengthening of the growing season, shifts in the water cycle with less winter precipitation falling as snow, and earlier runoff of both snowmelt and rainwater in the year. A 2022 study by the National Oceanic and Atmospheric Administration estimates that California’s sea level could rise by an additional 10-12 inches by 2050. In addition to changes in average temperatures, sea level, and precipitation patterns, the intensity of extreme weather events is also changing. Data suggests that the effects of climate change have already been felt in the Sacramento region.

Anticipated climate change effects in Yolo County include temperature rise, change in precipitation patterns, impacted water resources, increased risk of wildfires, sea level rise in the Delta, and extreme weather events. There is a large scientific consensus about general categories of climate change effects and their likely consequences over continent-scale geography; however, understanding of the magnitude, timing and region-scale geographic effects and the interrelationships between them is still evolving. Adaptation measures establish a basic framework for integrating climate change risk assessment and management into current planning processes, culminating in an adaptation planning framework to guide preparation for the effects of climate change in Yolo County. Measures address agriculture, water resources, sea level rise, and health risks.
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According to the 2011 Yolo County Climate Action Plan (CAP), some anticipated consequences of climate change in Yolo County include:
• Warm-season horticultural crops (e.g., tomatoes, cucumbers, sweet corn, and peppers) could be less viable by 2050. This may prompt a shift to hot season crops such as melon and sweet potato.
• Climate change could worsen air quality by increasing emissions, accelerating chemical processes, and raising inversion temperatures during summer periods of air stagnation. • Sea level rise is expected to exacerbate flooding in already vulnerable regions of Yolo County. Combined with increased potential for winter flooding, this could threaten the structural integrity of levee and flood control systems, which would place more people and property at risk from flooding. See Figure 3-2 for the areas of Yolo County within one meter of the daily tidal range:
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Figure 3-2: 1-Meter Sea Level Rise Scenario in Yolo County Source: Yolo County General Plan – USGS
Yolo County’s 2011 Climate Action Plan defined five strategies to help it reach its climate protection goals by 2030. These goals will be updated as part of the new Climate Action and Adaptation Plan, which is expected to be finalized in Summer 2024:
• Agriculture: Agriculture measures aim to reduce GHG emissions associated with nitrogen fertilizer application and the use of fossil fuels in field equipment and irrigation pumping. 262
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The agriculture strategy also presents measures and actions to “sequester” or store carbon in agricultural and natural landscapes.
• Transportation and Land Use: The transportation and land use measures implement General Plan Land Use and Circulation policies. These measures promote sustainable development patterns and investments in alternative transportation to reduce vehicle travel and associated emissions.
• Building Energy: Building energy measures are designed to increase energy and water efficiency in existing buildings, enhance energy and water performance in new construction, and encourage installation of building-scale renewable energy systems. This strategy also proposes a community choice aggregation program that would increase the ability for residents and businesses to purchase low and carbon-free electricity from a variety of energy providers.
• Solid Waste and Wastewater: This strategy presents one measure related to the reduction of solid waste emissions. The measure calls for increasing the efficiency of the methane control system at the County landfill. Supporting measures include increasing or expanding the diversion of organic wastes, and construction and demolition wastes from disposal, as well as increased recycling services in the county. The strategy also provides supporting measures that address emissions resulting from the treatment and conveyance of sewage and storm water. Methane control systems and low-impact development techniques that treat storm water on-site are the primary approaches. • Adaptation: Adaptation describes how the County plans to address the potential effects of climate change on the existing and planned environment. These measures direct the County to incorporate strategies into existing plans, and to develop new documents where appropriate, to ensure that Yolo County remains responsive to the challenges created by climate change. Specific attention is given to impacts related to agriculture, water resources, sea level rise, wildfires, and public health.

LOCATION AND EXTENT
There are numerous effects of climate change, each of way play an interconnected role in the natural hazards that Yolo County faces. Specific effects of climate change on natural hazards will be described in each hazard profile.

PAST OCCURRENCES
Climate change has never been directly linked for any declared disasters. Past flooding, wildfire, levee failure, and drought disasters may have been exacerbated by climate change, but it is impossible to make direct connections to individual events. Unlike earthquake and floods that occur over a finite time period, climate change is a slow onset, long term hazard, the effects of which some communities may already be already experiencing, but for which little empirical 263
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data exists. Further, given the science, it is likely that measurable effects may not be seriously experienced for years, decades, or may be avoided altogether by mitigation actions taken today.

LIKELIHOOD OF FUTURE OCCURRENCE
Highly Likely – Climate change is virtually certain to continue without immediate and effective global action. Without significant global action to reduce greenhouse gas emissions, the Intergovernmental Panel on Climate Change (IPCC) concludes in its Fifth Assessment Synthesis Report (2014) that average global temperatures is likely to exceed 1.5 C by the end of the 21st century, with consequences for people, assets, economies and ecosystems, including risks from heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scarcity, sea level rise and storm surges. The probability of future occurrences in the next 100 years is Highly Likely: Between 10 percent and 100 percent chance of occurrence next year or happens every year.

CLIMATE CHANGE AND SECONDARY IMPACTS
Climate change affects many other aspects of life in Yolo County which we are calling secondary impacts. These impacts affect the quality of life and can be potential hazards to the Yolo County Operational Area.

Air Quality
Throughout California, air quality is highly impaired compared to most of the nation. While predicting the effect of climate change on air quality is difficult due to complex physical, chemical, social, and policy variables, studies indicate that climate change could further worsen air quality throughout the State, including Yolo County. Higher temperatures may lead to increased ozone formation. Emissions of methane and nitrous oxide are projected to increase global ozone concentrations by 4% to 25% by 2100. If ozone levels rise to the high end of this range, attainment of ozone air quality standards could be impaired, which would have local effects in Yolo County. Highly air quality could result in increased incidence of respiratory disease and asthma.

Vector-borne Diseases
Temperature increases also could contribute to higher populations of mosquitoes and other disease-spreading organisms, or vectors. In California, three vector-borne diseases are of particular concern: human Hantavirus cardiopulmonary syndrome, Lyme disease, and West Nile virus. Disease transmission, however, depends on additional factors such as the interaction of humidity and rainfall, the maturation cycles of both the vector and the pathogen, and human vector control activities. Yolo County’s current low level of vector-borne disease is largely due 264
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to vector control measures. These measures would likely need to be enhanced and expanded, if vectors changed or risk of disease increased.

See the Yolo County Climate Action and Adaptation Plan for more information on specific climate change effects for Yolo County.

VULNERABILITY
The susceptibility of Yolo County to climate change is discussed in the applicable hazards.

3.2.5 AGRICULTURAL HAZARDS
Another impact of natural hazards is on the agricultural landscape of Yolo County Operational Area. California is the top agricultural producing state in the nation, and Yolo County is a major contributor with over 85% of County land used for Agricultural production. Significant crops include tomatoes, wine grapes, almonds, walnuts, rice, hay/alfalfa, and seed crops. Given the large source of economic revenue, as well as land coverage, agricultural hazards and the impact of natural hazards on the agricultural landscape will be discussed and analyzed further in this section, although it is not considered a natural hazard. Specific impacts of natural hazards on agriculture is also mentioned under each natural hazard.

According to the Yolo County HMP Planning and Steering Committees, agricultural losses occur on an annual basis and are usually associated with severe weather events, including heavy rains, extreme heat, freeze, droughts and floods. The 2018 State of California Multi-hazard Mitigation Plan attributes most of the agricultural disasters statewide to drought, freeze, and insect infestations. Other agricultural hazards include fires, crop and livestock disease, insects and noxious weeds.

In addition to severe weather, invasive species can affect the agricultural industry in the County.

Invasive species are organisms that are introduced into an area beyond their natural range and become a pest in the new environment. This hazard addresses the issues related to invasive pests including those that pose a significant threat to the agricultural industry and are therefore a concern in the Yolo County Operational Area. This hazard does not address pests and plants that cause impacts to human health, as those issues are addressed in other plans in the County.

According to the California Department of Conservation’s Farmland Mapping and Monitoring Program (FMMP), as of 2018 the County has approximately 243,961 acres of prime farmland, 19,320 farmland of statewide importance, 43,932 unique farmland, 49,731 farmland of local importance, and 165,921 grazing land. (see Table 3-6)
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Table 3-7: Yolo County Farmland Inventory – 1998, 2008, 2018 Soil Category 1998 Acres 2008 Acres 2018 Acres
Prime Farmland 265,915 255,193 243,961
Farmland of
Statewide Importance 18,202 16,793 19,320
Unique Farmland 55,243 45,750 43,932
Farmland of Local
Importance 74,303 60,345 49,731
Grazing Land 143,385 157,963 165,921
Urban and Built-up
Land 25,586 30,225 31,353
Water 7,371 7,814 4,233
Other Land 63,446 79,370 94,999
Total Area
Inventoried 653,451 653,453
653,450
In Section 1.4.4 Economics, the gross value of agricultural crops and products is described.

NATURAL DISASTERS AND SEVERE WEATHER
According to the USDA, every year natural disasters, such as droughts, earthquakes, extreme heat and cold, floods, fires, earthquakes, hail, landslides, and tornadoes, challenge agricultural production. Because agriculture relies on the weather, climate, and water availability to thrive, it is easily impacted by natural events and disasters. Agricultural impacts from natural events and disasters most commonly include contamination of water bodies, loss of harvest or livestock, increased susceptibility of disease, and destruction of irrigation systems and other agricultural infrastructure. These impacts can have long lasting effects on agricultural production including crops, tree growth, and arable lands, which require time to mature.

LOCATION AND EXTENT OF SEVERE WEATHER
Severe weather events that can affect agriculture are often widespread events (droughts, wind, freeze, heavy rains, and extreme heat). The entirety of the agriculture producing areas of the County are at risk to these severe weather events. Winds, freeze, extreme heat, and heavy rains can have short onset speeds, the onset of drought is much longer. Duration of events varies as well, with longer durations possible for drought and extreme temperatures and shorter durations for winds and heavy rains.

AGRICULTURAL PESTS AND DISEASES
Agricultural can be prone to pests and diseases. Some invasive and/or non-native plant species in Yolo County include:
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 Yellow Starthistle: Yellow starthistle is a long-lived winter annual, and occasionally, a biennial broadleaf plant. It is highly competitive and often develops impenetrable stands, displacing desirable vegetation. It is common in the Sacramento Valley, including in Yolo County. In addition to being a serious rangeland weed, yellow starthistle is sometimes problematic in grain fields where it can contaminate grain harvest, lowering grain value and quality. The plant also contains an unidentified compound that can cause a nervous system disorder in horses. A positive quality of yellow starthistle is that bees produce flavorful, high-quality honey when they forage on yellow starthistle.  Japanese Dodder: Dodder, Cuscuta species, is a parasitic annual plant that infests many crops, ornamentals, native plants, and weeds. Japanese dodder, C. japonica, which is native to Asia, recently has been found in California attacking and covering ornamental shrubs and fruit trees, with a preference toward citrus. However, Japanese dodder also can parasitize annuals, perennials, and native trees such as oaks and willows. Impact varies from moderate to severe reductions of plant growth and, in some cases, complete loss of vigor and death. The severity of an infestation depends on the growth stage of the host plant at the time of initial dodder attachment. Japanese dodder can cover and kill most large shrubs and small trees. The weakened state of infected plants also predisposes them to diseases and insect and nematode invasions. Japanese dodder is currently under an eradication program in California and has spread to more than a dozen counties including Yolo County, where it has been found in West Sacramento and Clarksburg.

See Figure 3-3 for a picture of Japanese Dodder on a tomato plant.

Figure 3-3: Japanese Dodder on a Tomato Plant
Source: UC Davis
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Effective management requires control of the current population, prevention of dodder seed production, and suppression of new seedlings in subsequent years.  Branched Broomrap: Branched broomrape is an annual and sometimes perennial parasitic plant that has no chlorophyll and lacks conspicuous leaves. It attaches to plant roots and is visible above ground only when flowering and inhabits ornamental and vegetable crop fields and margins, especially tomato fields. Branched broomrape has been associated with tomato plant die off in Yolo County in 2018. It can be treated with chemicals.

Invasive and/or non-native creatures include:
 Walnut Twig Beetle: The Walnut twig beetle (Figure 3-4) Pityophthorus juglandis is a tiny bark beetle that spreads a fungus Geosmithia morbida, also known as Thousand cankers disease (TCD). The disease can kill both black and English walnut trees. In California, native black walnuts (Juglans hindsii) infected with TCD were first confirmed in Yolo County in June 2008. Management includes installing Walnut Twig Beetle traps as well as applying insecticides and fungicides on black walnut trees.

Figure 3-4: Walnut Twig Beetle (expanded size for reference)  California Ground Squirrel: Ground squirrels damage many food-bearing and ornamental plants. Particularly vulnerable plants are grains as well as nut and fruit trees such as almond, apple, apricot, orange, peach, pistachio, prune, and walnut. Ground squirrels will enter gardens and devour vegetables in the seedling stage. They can damage young shrubs, vines, and trees by gnawing bark, girdling trunks (the process of completely removing a strip of bark from a tree's outer circumference), eating twigs and leaves, and burrowing around roots. Ground squirrels can also burrow into levees, destabilizing the structure of the levee and increasing the threat of levee failure. Numerous ground squirrel burrows have been observed on the CSA #6 levee. Baiting ground squirrels with treated grain is effective in summer and fall, because squirrels primarily feed on seeds during this period. Fumigation is most effective in spring when moist soil helps seal gasses in the burrow system. Fumigating at this time also is more effective, because squirrels die before they can reproduce.
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Additional pests and diseases of common crops in Yolo County include3:

Pests and disorders of Almonds
Invertebrates Diseases
Ants Armillaria root rot (Oak root fungus)
Armored scales
• San Jose Scale
Bacterial Canker
Borers
• American plum borer
• Pacific flatheaded borer
• Peachtree borer
• Shothole borer
Bacterial leaf scorch (similar to Oleander leaf
scorch)
Brown rot
Crown gall
Phytophthora root and crown rot
Leafhoppers Scab
Leafrollers Shot hole disease (Coryneum blight)
Mites
• Brown mite
• European red mite
• Spider mite
Verticillium wilt
Navel orangeworm Environmental Disorders
Nematodes Frost injury
Oriental fruit moth Poor or incomplete pollination
Redhumped caterpillars Sunburn
Soft scales Wind injury
Tent caterpillars
Pests of Disorders of Walnuts
Invasive Pests Diseases
Thousand Cankers Disease Anthracnose
Invertebrates Armillaria root rot (Oak root fungus)
Aphids
• Dusky-veined Walnut Aphid
• Walnut Aphid
Blackline
Branch wilt
Crown Gall
Armored Scales
• San Jose Scale
• Walnut Scale
Deep Bark Canker
Phytophthora root and crown rot
Shallow Bark Canker
Bark Beetles and Borers
• Pacific Flatheaded Borer
• Shothole Borer
• Twig Beetles
Walnut Blight
Wood decay
Carpenter worm Environmental Disorders
Codling moth Frost damage
Fall webworm Molds
Fruittree leafroller Overwatering
Lace bugs Sunburn
3 From the University of California Statewide Integrated Pest Management Program 269
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Navel orangeworm Wind injury
Nematodes Parasitic Plants
Mites
• European Red Mite
• Spider Mite
Broadleaf Mistletoe
Redhumped Caterpillar
Softscales
• European Fruit Lecanium
• Frosted Scale
Tent Caterpillars
Walnut husk fly
Pests and Disorders of Grapes
Invertebrates
Aphids Leafhoppers
Black Vine weevil Mealybugs (Gill’s Mealybug, Grape Mealybug) Boxelder bug Mites (Grape erineum mite, Spider mites)
Branch and twig borer Nematodes
Cutworms Omnivorous leafroller
Glassy-winged sharpshooter Saltmarsh Caterpillar
Grape bud beetle Scales
Grape leaffolder Sphinx moth
Grape phylloxera Thrips
Grasshoppers Western grapeleaf skeletonizer
Hoplia beetle Whiteflies
Katydids
Diseases Diseases cont’d
Armillaria root rot (Oak root fungus) Phomopsis cane and leaf spot Bunch rots Phytophthora root and crown rot
Crown gall Pierce’s Disease
Downy mildew Powdery Mildew
Eutypa dieback Viruses
Measles Environmental Disorders
Herbicide injury
Pests and Disorders of Tomatoes
Invertebrates Diseases
Aphids Black mold
Armyworms Curly top fungus
Buffalo Treehopper Damping off
Cutworms Early blight
Flea beetles Fusarium wilt
Hornworms Late blight
Leaffooted bug Phytophthora root rot
Leafminers Powdery Mildew
Loopers Tobacco Mosaic Virus
Lygus bugs Tomato Spotted wilt virus
Nematodes Verticillium wilt
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Potato Tuberworm White mold
Snails/slugs Environmental Disorders
Stink bugs Blossom end rot
Thrips Catfacing
Tomato fruitworm Fruit cracks
Tomato pinworm Sunscald
Tomato russet mite Tomato Leaf roll
Vegetable weevil
Whiteflies
Wireworms
Diseases than can affect rice include the aggregate sheath spot of rice, bakanae, kernel smut, rice blast, seed rot, and stem rot. Creatures that can affect rice include the armyworm, aster leafhopper, crayfish, rice leafminer, rice seed midge, rice water weevil, and tadpole shrimp.

PAST OCCURRENCES
The agricultural lands of Yolo County have historically been affected by weather related events such as high wind, heavy rain, extreme heat, freeze, and drought. The severe weather events can have devasting effects leading to losses in yield and affecting quality. The US Farm Services Agency provided information on disaster declarations from 2012 through 2023 (the length of data available on their website). These are show in Table 3-8.

Table 3-8 Yolo County – USDA Disaster Declarations 2012-2023 Year Declaration Number Primary or
Contiguous County
Disaster Type
2012 S3452 Primary Drought
2013 S3569 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3626 Contiguous Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3637 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3743 Primary Drought
2014 S3797 Contiguous Drought
2015 S3784 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2016 S3952 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2016 S4164 Contiguous Excessive rain/moisture/humidity, High 271
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winds
2017 S4163 Primary Drought
2018 N/A N/A N/A
2019 S4656 Contiguous Excessive rain/moisture/humidity
2020 S4691 Contiguous Drought
2020 S4697 Primary Drought
2021 S4916 Primary Drought
2022 S5146 Primary Drought
2022 S5229 Primary Frost, Freeze
2022 S5230 Contiguous Frost, Freeze
2022 S5332 Primary Frost, Freeze
2023 4683 Primary Flood/Flash Flooding, Winter
Storms/Ice Storms/Snow/Blizzard,
Mudslides/Debris flows/Landslides
2023 4683 Contiguous Flood/Flash Flooding, Winter
Storms/Ice Storms/Snow/Blizzard,
Mudslides/Debris flows/Landslides

LIKELIHOOD OF FUTURE OCCURRENCE
Highly Likely – As long as severe weather events, insects, pests, and diseases continue to be an ongoing concern to Yolo County Operational Area, the potential for agricultural losses remains.

VULNERABILITY ASSESSMENT
Vulnerability – High
Given the importance of agriculture in Yolo County, agricultural hazards continue to be an ongoing concern. The primary causes of agricultural losses are severe weather events, such as drought, freeze, extreme heat, high winds, insect/pest infestations and diseases. According to the County, agricultural losses occur on an annual basis throughout the County and are usually associated with these types of events.

According to the USDA, every year natural disasters, such as droughts, extreme heat and cold, floods, fires, hail, landslides, high winds and tornadoes, challenge agricultural production.

Because agriculture relies on the weather, climate, and water availability to thrive, it is easily impacted by natural events and disasters. Agricultural impacts from natural events and disasters most commonly include contamination of water bodies, loss of harvest or livestock, increased susceptibility to disease, and destruction of irrigations systems and other agricultural infrastructure. These impacts can have long lasting effects on agricultural production including 272
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crops, forest growth, and arable lands, which require time to mature. Specific impacts by hazards are listed below:
• Drought’s most severe effects on agriculture include water quality and quantity issues.

Other impacts include decreased crop yields, impact to feed and forage, altered plant populations, and tree mortality.
• Earthquakes are rare in Yolo County but can strike without warning and cause dramatic changes to the landscape. These dramatic changes could have devastating impacts on agricultural production and the environment. These impacts could include loss of harvest or livestock and destruction of irrigation systems and other agricultural infrastructure. • Extreme cold and freeze may result in loss of livestock and increased use of generators if any power lines are downed. Though crops in Yolo County are adaptable to freeze, they can become vulnerable to prolonged periods of low temperatures. Almond production can decrease during periods of low temperatures which is a significant impact on the agricultural community in Yolo County.
• Hot weather and extreme heat can worsen ozone levels and air quality as well as leading to drought conditions. Excessive heat and prolonged dry or drought conditions can impact agriculture by creating worker safety issues for farm field workers, severely damaging crops, and reducing availability of water and food supply for livestock. • Wildfires can spread quickly and devastate thousands of acres of land, which may include agricultural lands. This devastation could lead to large losses in crops, forestry, livestock, and agricultural infrastructure.
• Flooding causes many impacts to agricultural production, including water contamination, damage to crops, loss of livestock, increased susceptibility of livestock to disease, flooded farm machinery, and environmental damage to and from agricultural chemicals. • Landslides and debris flow occur in all 50 states, but commonly occur in connection with other major natural disasters such as earthquakes, volcanoes, wildfires, and floods. Some of the threats from landslides and debris flow include rapidly moving water and debris that can cause trauma; broken electrical, water, gas, and sewage lines; and disrupted roadways and railways. This can lead to agricultural impacts including contamination of water, change in vegetation, and harvest and livestock losses.

In addition to threats to agriculture from weather and other natural hazard events, agriculture in the County is at risk from insects, pests, and other diseases. Establishment of an invasive species would be detrimental to the agricultural industry of Yolo County because of product losses, stringent quarantine regulations, loss of exporting opportunities and increased treatment costs. 273
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The introduction of exotic plants influences wildfire by displacing forage species, modifying habitat structure, or changing species interactions within the ecosystem. In addition, invasive plants:
• Increase wildfire potential.
• Reduce water resources.
• Accelerate erosion and flooding.
• Threaten wildfire.
• Degrade rangeland, cropland, and timberland.
• Diminish outdoor recreation opportunities.

Agricultural pests and diseases can occur on crops anywhere in Yolo County. Pest detection in Yolo County involves preventing the introduction and spread of injurious pests not known to occur in the county through a systematic search for such pests. This is accomplished by deploying insect traps, making visual surveys, inspecting selected hosts, and informing and educating the public.

3.3 HAZARD RISK ASSESSMENT – NATURAL HAZARDS

3.3.1 SEVERE WEATHER - GENERAL
Severe weather is generally described as any destructive weather event, which in Yolo County includes high wind, fog, tornado, heavy rain, extreme heat, and freeze. For the purposes of this HMP, high rain is covered under flooding.

The National Oceanic and Atmospheric Administration (NOAA)’s National Centers for Environmental Information has tracked severe weather since 1950. Their Storm Events Database contains data on the following events shown in Figure 3-5.

Figure 3-5: NOAA NCEI Storm Database Period of Record
Source: NCDC NOAA
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The National Climatic Data Center’s (NCDC) Storm Events Database contains 261 severe weather events reported between February 1, 1950, and February 23, 2023. Table 3-9 summarizes these events. This provides an overview of Yolo County’s hazard environment.

Table 3-9: NCDC’s Severe Weather Events for Yolo County 1950-2/23/2023* Event Type
Number
of
Events Deaths Injuries
Property
Damage
Crop
Damage
Cold/Wind Chill 13 1 0 0 0
Debris Flow 2 0 0 $757,000 0
Dense Fog 7 6 38 $2,120,000 0
Dense Smoke 1 0 0 0 0
Drought 47 0 0 0 0
Excessive Heat 16 10 2 0 0
Extreme Cold/Wind
Chill
1 0 0 0 0
Flash Flood 1 0 0 0 0
Flood 37 0 0 $15,327,000 $7,800,000
Frost/Freeze 7 0 0 $200,000 $5,000,000
Funnel Cloud 4 0 0 0 0
Hail 2 0 0 $500,000 $510,000
Heat 29 0 18 0 0
Heavy Rain 6 0 0 0 0
Heavy Snow 1 0 0 0 0
High Surf 1 0 0 0 0
High Wind 31 0 0 $8,267,000 $37,000
Strong Wind 36 4 2 $3,723,400 0
Thunderstorm
Wind
4 0 0 $42,000 0
Tornado 4 0 0 $3,000 $20,000
Wildfire 6 2 8 $500,000 0
Winter Storm 1 0 0 0 0
Totals: 23 68 $31,439,400 $13,367,000
*Notes: Losses reflect totals for all impacted areas, some of which are categorized as the Southern Sacramento Valley
As previously mentioned, many of Yolo County’s state and federal disaster declarations have been a result of severe weather. For this 2023 MJHMP Update, severe weather is discussed in the following subsections:
 Extreme Heat
 Fog
 Freeze
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 High Wind
 Tornadoes
Extreme Weather Events
Climate change effects on weather patterns, storms, and extreme events in California are not well-understood currently. Some models suggest increased variations in weather cycles and an increase in intense storms. Others point to increased potential for drought resulting from higher temperatures and evaporation with lower precipitation. Still others suggest that the west coast may have fewer extreme droughts than other areas while experiencing higher average annual rainfall. A separate study predicted higher risks of large storms and floods in California. These conflicting conclusions about climate variability and extreme weather events support the need for additional studies employing models that can provide region-scale predictions. Given uncertainties surrounding the type and extent of expected changes in climate variability and the speculative nature of predicting extreme weather events, effects of changing storm patterns and other extreme weather remain unclear.

Precipitation
Precipitation projections are more uncertain than those for temperature, because complex temporal variability is inherent in precipitation patterns. The International Panel on Climate Change (IPCC) predicts that increasing global surface temperatures are likely to result in changes in precipitation. Global climate models for a wide range of GHG emission scenarios also predict that average global precipitation will increase during the 21st century because of climate change. However, such models are generally not well-suited for predicting regional precipitation changes given that factors affecting precipitation vary by regional geography and meteorology. Thus, significant regional differences in precipitation trends are expected. Some recent regional modeling efforts conducted for the western United States indicate that overall precipitation will increase, but considerable uncertainty remains. Projected precipitation increases are generally centered in Northern California in the winter months. However, various California climate models provide mixed results regarding changes in total annual precipitation in the State through the end of this century. One potential scenario of concern would be longer periods of drought punctuated by more intense storms during non-drought years. An IPCC review of multiple global models identifies much of California as an area where models generally did not agree on whether annual precipitation would increase or decrease; therefore, no firm conclusion on an increase or decrease can be provided, and the California climate could be either warmer-wetter or warmer-drier. Considerable uncertainties about the precise effects of climate change on California hydrology and water resources will remain until more precise and consistent information about how precipitation patterns, timing, and intensity will change is available. Given these uncertainties, regional conclusions regarding the potential effects of 276
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climate change on precipitation are speculative. Climate change may increase the number, duration, and intensity of atmospheric river events that can cause significant flooding in Yolo County. As temperatures warm, wetter storms will create more runoff. Increased precipitation and runoff in the mountainous areas of Yolo County can increase its susceptibility to landslides.

3.3.2 EXTREME HEAT

HAZARD/PROBLEM DESCRIPTION
According to FEMA and the National Weather Service (NWS), extreme heat is defined as temperatures that hover 10 degrees or more above the average high temperature for the region and lasts for several weeks. A heat wave is an extended period of extreme heat, often with high humidity. When relative humidity is factored in, the temperature can feel much hotter as reflected in the Heat index (see Figure 3-6). According to the NWS, heat waves are abnormally and uncomfortably hot and unusually humid weather, typically lasting two or more days. Heat waves normally coincide with little overnight cooling/relief, and do not cause damage or elicit the immediate response that floods, fires, earthquakes, and other disasters do. However, they rank among the deadliest of natural hazards and claim many more lives compared with other disasters.

Figure 3-6 – Heat Index
Source: NOAA
Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans 277
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succumb to the demands of summer heat. Among natural hazards, only cold weather takes a greater toll. In the 40-year period from 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the heat wave of 1980, more than 1,250 people died.

A key concern of extreme heat is the effects on Vulnerable populations. Vulnerable persons as the elderly, children, those with chronic illnesses, those on certain medications and drugs, persons with weight problems, persons with substance abuse issues, those who do not have stable housing, and those whose social or physical limitations prevent them from easily accessing a cooler environment are particularly susceptible to the dangers of extreme heat situations. Heat disorders generally have to do with a reduction or collapse of the body’s ability to shed heat by circulatory changes and sweating or a chemical (salt) imbalance caused by too much sweating.

When heat gain exceeds levels at which the body can remove heat, the temperature of the body’s inner core begins to rise, and heat-related illnesses may develop. Anyone can develop heat stress if engaged in intense physical activity and/or exposed to environmental heat (and humidity).

When the body is hot for long periods, it loses its ability to perspire, which is how the body handles high temperatures. Heat exhaustion is a common reaction to severe heat and can include symptoms such as excessive perspiration, dizziness, headache, and fainting. It can usually be treated with rest, a cool environment, and hydration. When a person stops perspiring, they can move from heat exhaustion to heatstroke very quickly. Heatstroke is more severe and requires immediate medical attention. It is often accompanied by dry skin, body temperature above 103 degrees Fahrenheit, confusion, and sometimes unconsciousness. Untreated heatstroke may lead to death.

Extreme heat conditions can also compound the effects of other hazards, such as drought and wildfire, can contribute to increases in tree mortality. In Yolo County, agriculture is also largely affected by extreme heat in both the vulnerability to crop production damage and on field workers and farmers. During times of heightened risk conditions of accidental fire ignitions due to a combination of high heat, low humidity, high winds, and the presence of fuel such as vegetation, PG&E can issue a Public Safety Power Shutoff (PSPS) for specific areas within the County. The PSPS program allows the de-energizing distribution or shut-off electric facilities pro-actively during dangerous conditions to prevent wildfire ignitions.

LOCATION AND EXTENT
Extreme heat has the potential to impact all areas of Yolo County, though people who live in cities can be at greater risk because concrete and asphalt store heat for longer and release it throughout the night. The geographic extent of extreme heat is Extensive with 50-100% of the 278
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Yolo County Operational Area affected by this hazard, most commonly occurring during the start of wildfire season between June through August (hottest months). According to the NOAA Online Weather Data, Yolo County’s monthly average maximum temperatures in the summer months (June through August) range from the upper-50s to the mid-90s. The highest recorded daily extreme was 116°F in 1925. Figure 3-7 shows the average daily high temperatures and extremes for the County.

Figure 3-7 – Average Daily High Temperature and Extremes (Jun-Aug 2022) Source: NOAA, National Weather Service
The National Weather Service (NWS) has a system in place to initiate alert procedures (advisories or warnings) when extreme heat is expected to have a significant impact on public safety. The expected severity of the heat determines whether advisories or warnings are issued.

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days, relative to a particular date and location. The heat risk is portrayed in a numeric (0-4) and color (green/yellow/orange/red/magenta) scale ranging from little to no risk, up to extreme risk to individuals. This can be seen in Figure 3-8.

Figure 3-8 – NWS Heat Risk Forecast
Source: NOAA, National Weather Service (NWS)
The NWS office in Sacramento can issue the following heat-related advisories as conditions warrant.
• Heat Advisories are issued during events where the HeatRisk is on the Orange/Red threshold (Orange will not always trigger an advisory)
• Excessive Heat Watches/Warnings are issued during events where the HeatRisk is in the Red/Magenta output.
• Red Flag Warnings are issued when warm temperatures, very low humidity levels, and stronger winds are expected to combine to produce an increased risk of fire danger.

According to the 2018 California State Hazard Mitigation Plan, the worst single heat wave event in California occurred in Southern California in 1955, when an eight-day heat wave resulted in 946 deaths. According to NCDC, several heat events have occurred in and around Yolo County since the last plan update in 2018:
• 8/14-8/20/2020: A prolonged and significant heat wave occurred in mid-August due to high pressure parked over California. High temperatures soared between 100 to 115 degrees for much of the Valley and lower elevation foothills, while higher elevation areas in the mountains range from the mid-80s to low 100s. Overnight lows were oppressive during this time frame as well, with Valley and foothill locations holding in the 70s to low 80s. Many emergency room visits were recorded in the Sacramento area in addition to 3 confirmed heat related deaths. One out of these deaths also involved drug use. • 8/18-8/23/2020: A heat wave was forecast for the initial part of this event; however, with many massive wildfires over northern California, intense heating was suppressed to 280
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wildfire smoke. Temperatures still rose to the mid-90s and low 100s, which was not much of a reprieve from the previous week's temperatures. A heat related death occurred during this time frame on August 22. The decedent was doing yard work in heat and fell ill. He was taken to Kaiser and died 3 days later. In addition to lingering heat, a renewed chance of thunderstorms and fire weather concerns were forecast August 23 and 24. This generated a lot of media attention as the state just suffered from a widespread lightning event and it looked like another could form. Similar conditions were in place, with tropical moisture forecast to move over norther California; however, the system did not produce as nearly much lightning. Strikes generally remained confined, but not limited to, the west slopes of the Sierra.
• 5/30-5/31/2021: High pressure ridging brought a heat wave to Northern California over the Memorial Day weekend holiday. Temperatures reached upwards of 20 to 25 degrees above climatology. Several new record daily high temperatures and one record monthly high temperature record were set in the area. At the peak of the heat wave on the 31st, Redding reached 109 breaking both the daily and monthly high temperature records. Red Bluff reached 108, setting a new daily high temperature record. Downtown Sacramento hit 106 tying the daily high temperature record. Sacramento Executive Airport reached 105 setting a new daily high temperature record. There were three cooling centers open in Sacramento County, one in Yolo County, one in Butte County and one in San Joaquin County.
• 6/1/2021: The first major heat event of the year brought widespread moderate to high heat risk Memorial Day weekend to Northern California. Some Valley locations reached over 100 degrees for the first time this year. Several new record daily high temperatures and one record monthly high temperature record were set in the area. • 6/16-6/19/2021: High pressure originating from the Desert Southwest built westward into California resulting in very hot daytime temperatures across the region and warm overnight low temperatures, particularly in the thermal belts. High to very high heat risk impacted the region with a four-day heatwave. Several daily high temperature records were either tied or broken on the 18th. During the event, cooling centers were made available to the public across interior Northern California. A list of the cooling centers available are as follows: five cooling centers in Sacramento County, one in Butte County, seven in Calaveras County, one in Placer County, two in San Joaquin County, two in Tuolumne County, two in Yolo County, and Solano County had two libraries available for cooling.
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• 7/9-7/11/2021: High pressure originating from the four-corners region built westward into California resulting in very hot daytime temperatures and warm overnight low temperatures across interior Northern California. High to very high heat risk impacted the region with a several day heatwave. The Sacramento region saw high temperatures reach more than 110 degrees on the 9th and 10th. On the 9th, downtown Sacramento tied its daily high temperature record of 109 degrees and on July 10th set a new daily high temperature record of 113 degrees. During the event, cooling centers were made available to the public across interior Northern California.
• 8/14-8/15/2021: High pressure over California resulted in very hot daytime temperatures and warm overnight low temperatures across interior Northern California. High to very high heat risk impacted the region. The Sacramento region saw high temperatures reach 105 degrees. On the 14th, downtown Sacramento recorded a high temperature of 103 degrees. During the event, cooling centers were made available to the public across interior Northern California.
• 9/7-9/9/2021: High pressure over California resulted in very hot daytime temperatures and warm overnight low temperatures across interior Northern California. High to very high heat risk continues to impact the region. One daily high temperature record was broken. The Sacramento region saw high temperatures reach more than 105 degrees. On the 8th, downtown Sacramento reached 106 degrees. During the event, cooling centers were made available to the public across interior Northern California. • 6/10-6/11/2022: High pressure over interior northern California brought widespread moderate to locally high heat risk to the region. Triple digit temperatures were observed across much of the Valley on June 10th and 11th with the hottest temperatures on June 10th ranging from 100 to 104 degrees in the Sacramento area. A daily high temperature record was tied in the area. Four cooling centers were open through 8:00 pm in Sacramento County.
• 9/4-9/9/2022: The Southern Sacramento Valley region saw all-time, monthly and daily record highs set, reaching up to 116 degrees during the event. On the 6th Downtown Sacramento recorded a high temperature of 116, which broke the all-time record high of 114 degrees set on July 17, 1925. This also broke the September record of 113 which was set the day before on the 5th. The previous monthly record of 109 was set on September 1, 1950, and tied on September 2, 1955, and September 6, 2020. The record of consecutive days over 110 was tied at 2. Daily highs were also set with 113 on the 5th 282
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and 8th and 109 on the 7th. The low of 80 on the 7th was the warmest on record in September and in all months was surpassed only on July 23, 2006, which had a low of 84.

Sacramento International Airport set an all-time daily record high of 116 on the 5th and 6th, and set a record of 4 consecutive days of 110 or higher. Sacramento Executive Airport set an all-time daily record high of 114 on the 5th and 6th. There was one death of an unhoused man attributed to the heat in Sacramento County.

From 1950 through 1999, there have been no noticeable heat wave sin Yolo County according to the National Climatic Data Center (NCDC); heat events were observed in 1999, 2000, 2005, 2007, 2008, 2013, 2015, 2017, and those listed above.

PAST OCCURRENCES
There has been no Federally declared extreme heat disasters, no Cal OES disasters related to extreme heat, but five USDA disaster declarations between 2013-2016 related to extreme heat, as shown on Table 3-10.

Table 3-10: Declared Disaster History (2013-2016)*
Year Disaster Name Disaster Type Disaster #
State
Declaration #
Federal
Declaration #
2013
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3569
8/21/2013 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3637
1/23/2014 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK
USDA
Contiguous
S3626
1/15/2014 -
2015
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3784
2/4/2015 -
2016
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK S3952
USDA Primary
2/17/2016
-
* Data from Table 3-5: Yolo County State and Federal Disaster Declarations, 1965-2023. All years that did not have Extreme heat declarations were removed
The NCDC data showed 45 extreme heat incidents for Yolo County since 1950, This can be see in Table 3-11.

Table 3-11: NCDC Heat Events for Yolo County 1950-2023* Event Type
Number
of
Events Deaths Injuries
Property
Damage
Crop
Damage
Excessive Heat 16 10 2 0 0
Heat 29 0 18 0 0
Total: 45 10 20 0 0
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*Data from Table 3-6: NCDC’s Severe Weather Events for Yolo County 1950-2/23/2023. All other event types were removed.

LIKELIHOOD OF FUTURE OCCURRENCE
Highly Likely - Temperature extremes are likely to continue to occur annually in Yolo County Operational Area. The probability of future occurrences in the next 100 years is Highly Likely:

Near 100 percent chance of occurrence next year or happens every year.

CLIMATE CHANGE AND EXTREME HEAT
Temperature
Increased concentrations of Greenhouse Gasses in the atmosphere result in increased air, surface, and ocean temperatures. Increased temperatures, in turn, drive most other climate change effects. Most regional climate model projections predict that annual average temperatures will increase in California during the next 100 years (see Figure 3-9). The California Climate Action Team projects that temperatures in California will rise between 1.8 degrees F and 5.4 degrees F by mid-century, and 3.6 degrees F and 9 degrees F by the end of the century. The exact level and timing of such a temperature increase in Yolo County is correspondingly uncertain.

Snowpack and Runoff
By delaying runoff during the winter months when precipitation is greatest, snow accumulation in the Sierra Nevada and Cascade Range to the east and the Coast Ranges and Klamath Mountains to the west of the Sacramento River acts as a massive natural reservoir for California.

Snowpack typically accumulates from November through the end of March and melts from April through July. The length and timing of each year’s snowpack accumulation and melting periods vary based on both temperature and precipitation. Hydrologic models indicate that higher temperatures associated with global warming would affect the timing and magnitude of both snowmelt and runoff in California. Despite uncertainties surrounding climate change precipitation effects, there is very high confidence that higher temperatures will change both snowfall and snowmelt in many watersheds. This is particularly relevant to those areas in Yolo County that are dependent on the Sacramento River. These changes could diminish water supplies, increase flooding, and reduce summer soil moisture. 284
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Figure 3-9: Average July Temperatures in California
Source: Yolo County Climate Action Plan - 2009 California Climate Adaptation Strategy According to the U.S. Climate Resilience Toolkit modeling, Yolo County has a relatively moderate national risk index rating to Extreme Heat due to Climate change (see Figure 3-10). 285
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Figure 3-10: Yolo County Hazard Report: Extreme Heat (page 1) Source: U.S Climate Resilience Toolkit

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – High
All of Yolo County is vulnerable to high temperatures that typically plague the Central Valley of California. The effects can be felt greater in the cities, where the urban heat island effect takes over. Although extreme heat rarely affects buildings in the County, there are secondary impacts when there are PSPS events due to extreme heat which then causes power outages and affects the temperatures inside the buildings. The greatest impact extreme heat has Yolo County Operational area is the population, as well as the County’s agricultural industry.

Agriculture/Land Use
Heat can cause stress to agricultural crops and livestock in the County. Though crops in Yolo County are adaptable to heat, they can become vulnerable to prolonged periods of high temperatures. Extreme heat also dries out vegetation in the County, creating greater risks from 286
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wildfire. When combined with low humidity, extreme heat also can contribute to the start and spread of wildfires. Hot weather and extreme heat can worsen ozone levels and air quality as well as leading to drought conditions. Excessive heat and prolonged dry or drought conditions can impact agriculture by creating worker safety issues for farm field workers, severely damaging crops, and reducing availability of water and food supplies for livestock. Although extreme heat has not directly caused property or crop damage losses, the added impact it has on drought conditions, and lack of water, has affected our agricultural community economics as described in Section 1.4.

Heat-Related Illness
While Heat waves do not cause damage or elicit the immediate response of floods, fires, earthquakes, or other more “typical” disaster scenarios, they are potentially deadlier. Heat emergencies are often slower to develop, taking several days of continuous, oppressive heat before a significant or quantifiable impact is seen. Heat waves do not strike victims immediately, but rather their cumulative effects slowly take the lives of vulnerable populations. Sickness can occur if someone has been in extreme heat for too long or has over-exercised for his or her age or physical condition. As mentioned previously, Extreme heat can be more dangerous for vulnerable populations. Areas lacking air conditioning or electricity, including mobile home parks and rural buildings, can become susceptible to extreme heat effects.

Access and Functional Needs
The most notable impact of extreme heat hazards is increased levels of heat stress and risk of health effects caused by extreme temperatures. This is particularly important for the elderly and infirm, as well as those with heart or respiratory problems and mental health issues. The percentage of Yolo County residents over the age of 65 was 9.6% in 2008. That number is expected to climb to 16.0% by 2030. With the prevalence of air-conditioner use during heat waves, demand for power could also increase putting more stress on power supply. The 2022 California Climate Adaptation Strategy reported that a preliminary analysis of the September 2022 heatwave showed a 5% increase in death rates statewide compared to the rest of the summer. Excess deaths were seen for heat-related illnesses, as well as cardiovascular, respiratory, endocrine, digestive, and renal diseases. In addition, rates of deaths among persons injured while at work were significantly higher during the heat wave period.

Vulnerable populations to extreme heat include:
• Homeless or unhoused ~700 individuals based on data collected in 2023. • Infants and children under age five ~ 23% (51,000) of Yolo County residents but projected to increase to 52,329 by 2060.
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• Elderly (65 and older) ~ 13.5% of Yolo County residents but estimated to increase 172.68% during the period of 2010-2060.
• Individuals with disabilities ~6.8% of Yolo County residents, under the age of 65. • Individuals’ dependent on medical equipment ~ 0.5% of Yolo County residents are dependent on electrical medical equipment, ~ 15% are Medicare beneficiaries dependent on medical equipment
As the County population continues to age, and more residents become senior citizens with a projected 172.68% increase by 2060, special attention needs to be given to those of the adult and aging population and the effects that this hazard could have on this vulnerable population. The residents of nursing homes and elder care facilities are especially vulnerable to extreme temperature events and these facilities are encouraged to have emergency plans or backup power to address power failure in times of extreme heat and PSPS events. Lower income residents, homeless or unhouse populations are also vulnerable. Cooling centers for these populations are utilized when necessary, in extreme heat situations as described more fully in Yolo County’s Emergency Support Function 6 Annex.

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
Yolo County’s land use, building code, and zoning ordinances regulate development to mitigate hazards. In the County’s General plans, there have been updates to building requirements that align with Climate adaption goals, to reduce the impact of greenhouse gas emissions by 2050.

Additionally, the Yolo County Climate Action Commission has been tasked with developing and proposing a new Climate Action Plan designed to reduce all greenhouse gas emissions in Yolo County and achieve a carbon negative footprint by 2030. These regulations on land use and development would reduce the impact of extreme heat on vulnerable populations and agricultural assets in the County. Although the population in Yolo County is projected to increase in Yolo County, overall population patterns, either an increase or decrease in population, will not affect the vulnerability of extreme heat events in Yolo County. Given the proactive steps that are currently being taken to reduce greenhouse gas emissions, a rise in population would not affect extreme heat impacts.

FUTURE CLIMATE INDICATORS
According to the Climate Resilience Toolkit modeling (Figure 3-10), future climate indicators predicts that the maximum temperature days above 90℉ and above 100℉ may increase by 2099.

With predicted future annual days in extreme heat temperatures increasing, climate change would negatively impact vulnerable populations, and have negative impacts on the agricultural economy. These rising temperatures would exacerbate existing drought conditions, potentially increasing risk of wildfires, and negatively affect air quality. Future Climate change would 288
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negatively impact vulnerable populations and put more stress on agriculture, especially as it increases drought risk and air quality.

3.3.3 FOG

HAZARD/PROBLEM DESCRIPTION
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth’s surface. Fog results from air being cooled to the point where it can no longer hold all the water vapor it contains. Fog can form in several ways, depending on how the cooling that caused the condensation occurred. The most common types in Yolo County are radiation and advection fog.

A think, dense fog known as tule fog is a radiation fog that also can become present in Yolo County particularly from late fall through early spring. Tule fog occurs when there is relative high humidity, calm winds, and rapid cooling. The longer nights during the winter months create this rapid ground cooling and results in a pronounced temperature inversion at a low altitude, creating a thick ground fog. Above the cold, foggy layer, the air is typically warm and dry. Once the fog has formed, turbulent air is necessary to break through the inversion. Daytime heating can also work to evaporate the fog in some areas.

While fog is not likely to damage property or lead to large impacts on the population within the planning area, reduced visibility caused by fog can impact transportation corridors in the County.

Nighttime driving in the fog is dangerous and multi-car pileups have resulted from drivers using excessive speed for the conditions and visibility. A study conducted by the University of California, Berkeley, identified a strong correlation between air pollution and naturally occurring tule fog. Pollution becomes a factor in fog formation because soot, dust and vehicle exhaust provide the tiny airborne particles, or condensation nuclei, around which water vapor condenses to form clouds, fog and haze. Visibility in tule fog is usually less than an eighth of a mile, and visibility can reach near zero.

A warm moist air mass blowing over a cold surface also can cause fog to form, which is called advection fog. Once formed, it may move across the landscape, pushed by low level winds.

Advection fog can last for several days and is most common in the U.S. on the West Coast.

LOCATION AND EXTENT
Fog, including tule fog, can occur in all areas of Yolo County though it is found more in lower elevations where the air is denser. Tule fog is characteristically confined mainly to the Central Valley of Northern California due to the mountain ranges surrounding it, including the Blue Ridge Mountains on the western border of Yolo County. Fog is most often experienced in Yolo County during the winter.
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Fog was rated as Critical with between 35-50 percent of the operational area potentially affected. Fog with near 0-foot visibility could potentially be experienced anywhere in Yolo County.

There has been two major recorded traffic accident in Yolo County due to fog:

On February 3rd, 1984, a 70-vehicle pileup occurred on the Yolo Causeway in West Sacramento due to fog. Cars, oil trucks, and a garbage truck were involved, and the causeway was covered in debris for two miles. There were no fatalities, but at least two motorists suffered broken legs and others received minor injuries. The westbound lanes of the causeway were closed for four hours.

On November 29, 2021, a major overturned big rig crash with a smaller pickup truck led to a complete closure of northbound Interstate 5 at the Yolo Bypass during the morning commute.

There were no fatalities, but the northbound lanes were closed for hours to clean up debris spilled on bypass and down at the ground level.

Other traffic accidents due to fog have occurred on highways in the Central Valley. In December 1997, an accident due to fog on Interstate 5 in Sacramento County resulted in five deaths and 28 injuries. On November 3, 2007, heavy fog caused a pileup on State Route 99 near Fresno that resulted in two deaths and 39 injuries. Similar accidents have the potential to occur in Yolo County on any of its major interstates.

One minor accident due to fog has been recorded in Yolo County since the last plan update:
1/15/2015: A West Sacramento fire engine was rear ended by a car while stopped on Interstate 80 responding to an incident. Even with lights and flares laid out, visibility was only 30-100 feet with heavy fog present. No injuries were reported.

PAST OCCURRENCES
There has been no Federally declared fog weather disasters, no Cal OES disasters related to fog, and no USDA disaster declarations between 2013-2016 related to fog.

The NCDC data showed 7 fog incidents for Yolo County since 1950, This can be seen in Table 3-12.

Table 3-12: NCDC’s Severe Weather Events for Yolo County 1950-2/23/2023* Event Type
Number
of
Events Deaths Injuries
Property
Damage
Crop
Damage
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Dense Fog 7 6 38 $2,120,000 0
Totals: 7 6 38 $2,120,000 0
*Notes: Losses reflect totals for all impacted areas, some of which are categorized as the Southern Sacramento Valley

LIKELIHOOD OF FUTURE OCCURRENCE
The probability of future occurrences in the next 100 years is Highly Likely: Near 100 percent chance of occurrence next year or happens every year.

CLIMATE CHANGE AND FOG
California’s winter tule fog has declined dramatically over the past three decades due to falling levels of air pollutions, raising a red flag for the state’s multibillion-dollar agricultural industry, according to researchers at UC Berkeley. Crops such as almonds, pistachios, cherries, apricots and peaches go through a necessary winter dormant period brought on and maintained by colder temperatures. Tule fog that descends upon the State’s Central Valley between late fall and early spring, helps contribute to this winter chill.

When there is an insufficient rest period (or lack of dormant time for crops) it impairs the ability of farmers to achieve high quality fruit yields. The UC Berkeley findings have implications for the entire country since many of these California crops account for 95 percent of U.S. production. The researchers also paired NASA and NOAA satellite records with data from a network of University of California weather stations, covering 32 consecutive winters. Based on the data, there was a great deal of variability from year to year, but on average, the researchers found a 46 percent drop in the number of fog days between the first of November and the end of February. Climate forecasts suggest that the accumulation of winter chill will continue to decrease in the Central Valley. Tule fog was also less prevalent in recent years in part due to the multi-year drought.

While the short‐term fog variability is dominantly driven by climate fluctuations, the longer‐term temporal and spatial changes in fog have been driven by changes in air pollution. The Clean Air Act has also greatly reduced the air pollution that would form fogs.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – Medium
The most common impacts from fog are traffic accidents, particularly on roads with higher speed limits including interstate and major state highways. Major accidents associated with fog can result in injury and death, as has occurred in several incidents close to Yolo County. 291
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The areas of Yolo County most vulnerable to fog include Interstates 5 and 80 as well as US 50 and State Route 113 where a potential multi-casualty vehicle incident could occur. Fog can also be hazardous for aircraft as well as for ships attempting to navigate the Deepwater Ship Channel.

Economic impacts due to dense fog are generally related to road closures leading to a decrease in travel to businesses. Other economic impacts relate to property damages to vehicles from accidents.

The impact of fog on government services structures and buildings should be like the impacts on general property. Dense fog can create serious problems for responders by slowing down the speed of responders and preventing them from arriving at accident scenes on time. The impact of dense fog on public confidence in government is minimal. Population pattern changes would not affect the vulnerability or the impacts of fog.

3.3.4 FREEZE

HAZARD/PROBLEM DESCRIPTION
Freeze is defined as a period in which temperatures fall below the freezing point of 32 degrees Fahrenheit or 0 degrees Celsius. A hard freeze is a period of at least four consecutive hours of air temperature that are below 25 degrees Fahrenheit. Freeze and extreme cold often accompany a winter storm or are left in its wake. Although not as prevalent in California as heat waves, this this type of hazard still poses a real danger to life, property, and agriculture during the winter months of December, January, and February when they are most likely to occur. Prolonged exposure to freezing temperatures can cause frostbite to exposed skin, typically fingers, toes, ear lobes, or nose tip.

When the wind is factored in, the temperature can feel even colder as reflected in the wind chill index (see Figure 3-11). This was developed in 2001 by NWS to describe the relative discomfort/danger resulting from the combination of wind and temperature. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Hypothermia is another cold-related issue when the core body temperature drops below 95 degrees Fahrenheit. Medical attention is needed immediately for this condition.

The NWS office in Sacramento can issue the following freeze-related warning as conditions warrant.
• Freeze Warnings - Are issued for areas with significant commercial agriculture whenever the first winter freeze is expected. The first freeze is defined as "when minimum shelter temperature is forecast to be 32 degrees or less during the locally 292
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defined growing season." Freeze warning can also be issued for the first freezing spell in autumn especially after a spell of warmer-than-normal temperatures. A freeze watch can be issued for the same criteria up to 48 hours or longer in advance. • Wind Chill Warning- Are issues a wind chill warning when dangerously cold wind chill values are expected or occurring.

Figure 3-11: Wind Chill Index
Source: National Weather Service

LOCATION AND EXTENT
Freeze has the potential to impact all areas of Yolo County. The geographic extent of freeze is Extensive with 50-100% of the Yolo County Operational Area affected by this hazard during the winter months (December through February). Temperatures could potentially reach into the low 20 degrees Fahrenheit for several days, and below freezing for several weeks, as has historically occurred in the Sacramento area. According to NCDC there has been a few incidents of cold/wind chill, freeze events in Yolo County Operational Area since the last update:
• 5/15/2021: Warm weather combined with cold and fast-moving area waterways lead to 5 deaths across the region in the month of May. CNRFC gauges near Rancho Cordova had water temperatures in the low to mid 60s.
• 2/24-2/25/2022: Temperatures dropped below the critical threshold of 28 degrees for several days in late February. Several locations in the region reported temperatures as low 293
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as 25 degrees during the event with subfreezing conditions persisting for several hours each day. The Sacramento executive airport set new daily minimum temperatures on the 24th and the 25th of February of 27 and 28 degrees respectively. Farmers anticipate damage to their orchards with final damage costs expected to be determined when crops are harvested. Regional agriculture was severely impacted with temperatures dipping below critical thresholds for spring buds, specifically on fruit and nut trees. Blooms were also about 10 days sooner than average leading to greater impacts to farmers. Mitigation efforts were used to save crops, however the Colusa County Agricultural Commissioner reported as many as 5 counties were severely impacted.

The lowest temperature ever recorded in Sacramento was 17 degrees in 1932. From December 20th, 1990 – January 1st 1991, Sacramento had a record number 13 consecutive days with minimum temperatures below freezing. Other notable freeze events documented in and around Yolo County occurred in 2007, 2008, and 2009. According to the NOAA Online Weather Data, Yolo County’s monthly average maximum temperatures in the winter months (December through February) range from the upper-30s to the upper-60s.

PAST OCCURRENCES
There has been one Federally declared extreme freeze disaster in 1991, no Cal OES disasters related to freezing weather, but three USDA disaster declarations in 2022 related to freezing temperatures, as shown on Table 3-13.

Table 3-13: Declared Disaster History (1991, 2022)*
Year Disaster Name Disaster Type Disaster #
State
Declaration #
Federal
Declaration #
1991 Severe freeze Freezing DR-894-CA - 2/11/1991
2022 Freeze
Severe weather
– Freeze S5229
USDA Primary
7/1/2022
-
2022 Freeze
Severe weather
– Freeze S5230
USDA
Contiguous
7/1/2022
-
2022 Freeze
Severe weather
– Freeze S5332
USDA Primary
11/4/2022
-
* Data from Table 3-5: Yolo County State and Federal Disaster Declarations, 1965-2023. All years that did not have Extreme Weather: Freeze declarations were removed
The NCDC data showed 24 freeze-type incidents for Yolo County since 1950, This can be see in Table 3-14.

Table 3-14: NCDC Freeze Events for Yolo County 1950-2023* Event Type Number Deaths Injuries Property Crop
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of
Events
Damage Damage
Cold/Wind Chill 13 1 0 0 0
Extreme Cold/Wind Chill 1 0 0 0 0
Frost/Freeze 7 0 0 $200,000 $5,000,000
Hail 2 0 0 $500,000 $510,000
Heavy Snow 1 0 0 0 0
Totals: 24 1 0 $700,000 $5,510,000
*Data from Table 3-6: NCDC’s Severe Weather Events for Yolo County 1950-2/23/2023. All other event types were removed.

LIKELIHOOD OF FUTURE OCCURRENCE
Likely - The probability of future occurrences in the next 100 years is Likely: Between 10 percent and 100 percent chance of occurrence in next year or has a recurrence interval of 10 years or less.

CLIMATE CHANGE AND FREEZE
According to Climate change indicators like Freeze-Thaw conditions, overall, there seems to be a trend in increased unfrozen days in a year (see Figure 3-12). The figure shows the number of days the ground is unfrozen compared with 1979-2021 averages. For each year listed, the bar represents the number of days shorter or longer than average. Positive numbers represent years with more unfrozen days than average.

Figure 3-12: Number of Unfrozen Days in the Contiguous 48 States, 1979-2021 Source: Environmental Protection Agency
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The number and timing of days with temperatures below freezing affects many aspects of life such as crops/agriculture, pest control, and water supplies through snowpack. As the number of days below freezing has decreased, it affects snowpack levels, which affects water supplies in California which depends on snowpack levels to mitigate drought conditions. Freezing temperatures also help to reduce populations of insects and other pests that damage crops or spread diseases to humans. Climate change would decrease the number of freezing days, potentially exacerbating drought conditions without more robust snowpack levels, and increases issues with pests which may affect agricultural industry.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – Medium
All of Yolo County is vulnerable to freeze. The effects can be felt greater in the mountainous areas, where the lower temperatures occur. These areas of the County are not heavily populated.

Susceptible populations include the young and elderly, as well as those without adequate heating.

Though crops in Yolo County are adaptable to freeze, they can become vulnerable to prolonged periods of low temperatures. Almond production can decrease during periods of low temperatures which is a significant impact on the agricultural community in Yolo County. As mentioned in the NCDC data above, there has been significant crop damage losses due to freeze events in Yolo County.

Pipes may freeze and burst in homes or buildings that are poorly insulated or without heat.

Extreme cold can disrupt or impair communications facilities. Prolonged exposure to the cold can cause frostbite or hypothermia and can become life-threatening.

Vulnerable populations that are more susceptible to cold and freeze include:
• Homeless or unhoused ~700 individuals based on data collected in 2023. • Infants and children under age five ~ 23% (51,000) of Yolo County residents but projected to increase to 52,329 by 2060.
• Elderly (65 and older) ~ 13.5% of Yolo County residents but estimated to increase 172.68% during the period of 2010-2060.
• Individuals with disabilities ~6.8% of Yolo County residents, under the age of 65. • Individuals’ dependent on medical equipment ~ 0.5% of Yolo County residents are dependent on electrical medical equipment, ~ 15% are Medicare beneficiaries dependent on medical equipment.
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Although Yolo County has not had to open Heating Centers due to Freeze events, our concern as with extreme heat events are vulnerable populations, such as the populations mentioned above and residents of nursing homes and elder care facilities who are vulnerable to extreme temperature events. In additional to vulnerable populations, pets and livestock are at risk to freeze and cold and should have emergency plans or backup power to address power failure during times of extreme cold and freeze.

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
Yolo County’s land use, building code, and zoning ordinances regulate development to mitigate hazards. To reduce greenhouse gas emissions and to achieve a carbon negative footprint by 2030, there are efforts to require existing residential units to install solar water heaters, focus on reducing energy and converting to solar energy, improving energy efficiency in residential and commercial units, and reducing water consumption on farms, residential and commercial units.

These performance goals, although not directly addressing extreme freeze hazards, will overall have beneficial secondary impacts to reducing the frequency of extreme freeze events and thus reducing the negative impact on agriculture and even vulnerable populations which are more affected by these events. Population patterns, either an increase or decrease in population, will not affect the vulnerability and will not affect the impact of extreme freeze events in Yolo County.

FUTURE CLIMATE INDICATORS
Although it is expected for overall global temperatures to continue to rise, the effect of climate change on extreme freeze events would overall decrease the frequency of extreme freeze events occurring. One impact of rising temperatures is its effect on snowfall and snowmelt in many watersheds. This is relevant for areas in Yolo County dependent on the Sacramento River, and could overall dimmish water supplies, increase flooding, and reduce summer soil moisture.

Although it would improve the negative impacts that extreme freeze has on vulnerable populations and put less stress on agriculture due to less damage to crops on prolonged freeze days, it still impacts these areas due to the impacts of rising temperatures effecting snowfall and snowmelt.

3.3.5 HIGH WIND

HAZARD/PROBLEM DESCRIPTION
High winds, often accompanying severe storms and thunderstorms, can cause significant property and crop damage, threaten public safety, and have adverse economic impacts from business closures and power loss. High wind is defined as a one-minute average of surface winds 40 miles per hour or greater lasting for one hour or longer, or winds gusting to 58 miles per hour 297
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or greater regardless of duration that are either expected or observed over land4. The Beaufort scale is an empirical measure that relates wind speed to observed conditions on land and is a common measure of wind intensity (see Figure 3-13). These winds may occur as part of a seasonal climate pattern or in relation to other severe weather events such as thunderstorms.

Straight-line winds may also exacerbate existing weather conditions by increasing the effect on temperature and decreasing visibility due to the movement of particulate matters through the air, such as dust. The winds may also exacerbate fire conditions by drying out the ground cover, propelling fuel around the region, and increasing the ferocity of existing fires. These winds may also damage crops, damage roofs and structures due to downed trees, and cause secondary damage due to flying debris. When there is extreme heat, and high winds, PG&E also considers PSPS events as a possibility creating a secondary impact of power outages.

The NWS office in Sacramento can issue the following wind-related advisories and warning as conditions warrant.
• High Wind Advisories: are issued when winds that last longer than 1 hour at sustained speeds 25-39 mph/22-34kt or gusts 40-57 mph/ 34-49kt of any duration. • High Wind Warnings: are issued when sustained winds are greater than 40 mph/ 35kt, lasting an hour or gusts less than 58 mph/ 50kt of any duration. 4 NOAA.
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Figure 3-13: Beaufort Wind Scale
Source: National Weather Service

LOCATION AND EXTENT
High wind has the potential to affect all areas of Yolo County, as weather patterns are only marginally predictable and long-term forecasting is only marginally effective for specific area forecasts. The geographic extent of high winds is Extensive with 50-100% of the Yolo County Operational Area affected by this hazard. High winds often occur with the onset of atmospheric river events. Figure 3-14 depicts wind zones for the United States. The map denotes that Yolo County falls into Zone I (indicated by the black circle), which is characterized by high winds of up to 130 mph.
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Figure 3-14: Wind Zones in the United States
Source: FEMA
The National Climatic Data Center (NCDC) provides a listing of all the high wind events to affect Yolo County since 1950. Several high wind events have occurred in and around Yolo County since the last plan update in 2018:
• 1/7/2019: High Wind: A wind gust to 60 mph was measured at McClellan Airfield.

Numerous trees were reported down in the area. A cool, wet Pacific system brought hazardous driving over mountain roads, local road flooding in the Central Valley, and damaging winds.
• 2/27/2019: Strong Wind: CHP reported numerous trees down across the area due to strong winds and wet ground, causing road blockages and power outages. A gust to 49 mph was measured at Sacramento International Airport. Examples include downed power lines in roadway which were reported.
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• 10/27/2019: Strong Wind: Sacramento International Airport a non-thunderstorm related wind gust up to 55 mph. Within the zone there was at least two reports of downed trees in roadways in the Davis Sacramento metro areas. Critical fire weather conditions were forecast for Oct 23-24 and again on October 27-28 with the eastern Pacific High allowing trough to slide into the Great Basin/Nevada areas. This caused the pressure gradients to tighten over the county warning area, which lead to additional rounds of strong northerly and easterly winds. With these winds forecast, dry conditions still in place, and fuels still being primed a Red Flag Warning was issued for most of interior northern California.

Fortunately, no major wildfires resulted from this, but utility power lines did suffer from wind and tree damage across much of northern California. Time stamps for events are based on strongest wind gusts that occurred between Oct 23-38. • 1/18-1/19/2021: Strong Wind: Law enforcement reported multiple downed trees and powerlines across Sacramento and Yolo counties. Damage costs are estimated for this report. Wind reports across the area include Sacramento International, Sacramento Executive, and Davis airports reporting peak wind gusts of 41, 43, and 37 mph respectively. Additional peak wind gust reports around Sacramento County varied from 30 to 43 mph and around Yolo County they varied from 35 to 59 mph. Upper-level ridging combined with a series of troughs led to the tightening of pressure gradients over interior northern California. The first trough slipped down and paralleled the California coast causing the north and east pressure to develop and tighten. This brought gusty winds Sunday night into Monday. A brief reprieve in winds occurred mid-Monday, before a second shortwave further reinforced the offshore flow Monday night into Tuesday. This shortwave trough dug south from eastern Washington toward the central and southern portion of the Sierra Nevada. Strong and damaging winds developed across interior northern California resulting in power outages, downed trees, downed power lines, and several small wildfires. Peak gusts ranged from 30 to 60 mph in the Valley, and generally between 40 and 80 mph for the mountains and foothills. • 2/23/2021: Strong Wind: Breezy winds developed across interior northern California on February 23 as a shortwave trough slid across the Pacific Northwest. High pressure was developing east of the region causing the pressure gradient to tighten over the region.

Wind speeds at nearby Davis Airport, within in Yolo County, were 21.9 mph gusting to

35.7 mph at 9:55 am, 25.3 mph gusting to 38.0 mph at 10:35 am, 20.7 mph gusting to

39.1 mph at 10:55 am. Sustained winds briefly met Wind Advisory criteria at that location, but not wind gust criteria. A Wind Advisory was not in effect during that time. • 10/10-10/11/2021: Strong north winds impacted portions of interior northern California late Sunday the 10th through Monday the 11th. CHP reported numerous down trees, tree limbs and powerlines across the region.
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• 12/10/2022: Strong Wind: Sacramento International Airport reported a max gust of 52 mph. California Highway Patrol reported multiple downed trees and power lines across the Sacramento Area, resulting in 32,431 customers across the Sacramento region without power according to broadcast media. Another weekend storm delivered widespread rain, mountain snow and gusty winds to interior NorCal. Localized flooding, downed trees, and mountain travel impacts were observed starting on 12/9/22 through early 12/12/22.
• 12/13/2021: High Wind: High winds caused a significant number of trees and powerlines to fall across the area causing widespread power outages leading to tens of thousands of people left without power, roadways were closed and blocked, and dangerous driving conditions were observed including a vehicle struck by a powerline. Peak wind gusts reported for the zone reached 47 to 56 mph. Damage costs are estimated. • 12/27/2022: A strong and very wet atmospheric storm brought extended periods of moderate to heavy rain and periods of strong winds to much of the region, along with heavy high-elevation snow. Precipitation totals were around 1-3 inches for the Central Valley, 3-6 inches in the foothills, and 5-8 inches of liquid equivalent in the mountains.

The rain brought widespread flooding to the region. This included significant river flooding on the Cosumnes River around Wilton due to multiple levee breaks, resulting in the area being evacuated and area highways and roads being closed, including SR-99.

River flooding was also reported along the Mokelumne River near Benson's Ferry and Mormon Slough at Bellota. Flooding of streams, in low areas and from clogged storm drains also closed many other roads across Northern California, with several small communities being evacuated. High winds gusting 50-65 mph in the Central Valley caused large numbers of trees to fall, bringing widespread power failures across the area, with hundreds of thousands of customers impacted. Many local roads were closed to downed trees blocking them. Trees were also reported to have fallen on homes and automobiles. The storm with flooding continued into January, with several fatalities reported due to drowning and wind-downed trees.
• 12/31/2022: High Wind: There were many reports of trees uprooted & large branches down. Over 145,000 customers were without power in the Sacramento area due to falling trees knocking down several power lines in high winds. Power was still out for 40,000+ customers as of 9:30am on 1/1/2023. Sacramento International Airport reported sustained winds above 40 mph with wind gusts above 45 to 50 mph from 6:50 pm through 9 pm with a peak gust of 61 mph at 736 pm. Sacramento Executive Airport reported wind gusts above 45 mph from 6:50 pm through 9:25 pm with a peak gust of 64 mph at 814 pm.

Sustained winds exceeded 40 mph from 7:45 pm to 9 pm. McClellan Airfield Airport reported wind gusts above 45 mph from 7:15 pm through 9:15 pm with a peak gust of 60 mph at 815 pm. Sustained winds exceeded 40 mph from 7:35 pm to 8:55 pm. Many local 302
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roads were closed to downed trees blocking them. Trees were also reported to have fallen on homes and automobiles. The storm with flooding continued into January, with several fatalities reported due to drowning and wind-downed trees. • 1/4-1/5/2023: High Wind: A powerful atmospheric river brought very strong winds with moderate to heavy rain and renewed flooding of the already elevated waterways. There was flooding of roadways, urban areas, rivers, streams, and creeks. There were dangerous mountain travel conditions at Sierra pass levels with 6 to 18 inches of snow above 6500 feet. The warm nature of the storm limited snow amounts further down, with just a few inches of accumulation down to 6000 feet. Winds gusted up to 50-60 mph in the Valley, with gusts up to 70 to 100 mph in the mountains. There were widespread trees down, blocking roads and causing numerous power outages across the area. Rainfall amounts were 1 to 3 inches in the Central Valley and 2 to 6 inches in the foothills and mountains.

There were 2 fatalities reported, one due to drowning, and the other due to a rain-related car accident.
• 1/7-1/8/2023: High Wind: A major winter storm brought strong winds with moderate to heavy rain bringing renewed flooding of already elevated waterways. There were high winds around midnight for the Sacramento metro area, bringing numerous reports of damage. There was flooding of roadways, urban areas, rivers, streams and creeks, with rockslides and mudslides also reported. There were widespread downed trees, power lines, and power outages. Winds gusted up to 60-70 mph in the Central Valley.

Other notable high wind events occurred in 2014, 2016, and 2017.

PAST OCCURRENCES
There has been no past Federally or state disaster declarations due to high winds. However, there has been several USDA disaster declarations related to high winds, as shown on Table 3-15.

Table 3-15: Declared Disaster History (2013, 2016)*
Year Disaster Name Disaster Type Disaster #
State
Declaration #
Federal
Declaration #
2013
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3569
8/21/2013 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3637
1/23/2014 -
2014
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK
USDA
Contiguous
S3626
1/15/2014 -
2015
Extreme Heat, High
Winds, High Fire Risk
Drought –

FAST TRACK
USDA Primary
S3784
2/4/2015
2016
Extreme Heat, High
Winds, High Fire Risk
Drought- FAST
TRACK S3952
USDA Primary
2/17/2016
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2016
Severe Weather – High
Winds, Excessive Rain Severe Weather S4164
USDA
Contiguous
3/3/2016
* Data from Table 3-5: Yolo County State and Federal Disaster Declarations, 1965-2023. All years that did not have High Wind declarations were removed
The NCDC data showed 67 High Wind incidents for Yolo County since 1950, This can be see in Table 3-16.

Table 3-16: NCDC High Wind Events for Yolo County 1950-2023* Event Type
Number
of
Events Deaths Injuries
Property
Damage
Crop
Damage
High Wind 31 0 0 $8,267,000 $37,000
Strong Wind 36 4 2 $3,723,400 0
Totals: 67 4 2 $1,990,400 $37,000
*Data from Table 3-6: NCDC’s Severe Weather Events for Yolo County 1950-2/23/2023. All other event types were removed.

LIKELIHOOD OF FUTURE OCCURRENCE
Highly Likely - The probability of future occurrences in the next 100 years is Highly Likely:

Near 100 percent chance of occurrence next year or happens every year.

CLIMATE CHANGE AND HIGH WIND
The main cause of wind is differential heating. Researchers have found that the global average wind speed has increased. But they are also finding that as temperatures increase, and the difference in temperature between the equator and the poles shrink, it could lead to slower average wind speeds. Slower wind speeds affect the rate of evaporation and have downstream affects on agriculture. It could also lead to increased wildfire risks and aggravate drought conditions.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – High
High winds can cause a wide range of damages including to mobile homes, power lines, billboards, airplanes, vehicles, roofs and other structures. Trees toppled over by high winds can fall onto power lines and rupture underground water mains, disrupting services to customers.

Trees can also cause damages by falling onto structures, cars and even people. As shown in previous events in Yolo County, high winds also have the potential to cause traffic and aviation accidents, which could result in injuries and possibly even death. Based on previous data from NCDC, High wind events caused significant property and crop damage and Yolo County 304
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Operational Area has an extensive history of previous occurrences of high wind/strong wind events.

Secondary Impact: Fallen Trees
No one area of Yolo County is more vulnerable to wind than any other, though certain locations are more susceptible to damage due to building construction and the amount of tree canopy. The cities of Davis and Woodland are particularly susceptible to wind damage from fallen trees, particularly on many of their main streets. There are two small airports in Yolo County, the University Airport in the City of Davis and the Watts-Woodland airport outside of Woodland, is susceptible to high winds, which can cause damage to aircrafts and affect airport operations.

Winds can also cause trees to fall on numerous buildings throughout the University of California Davis campus, damaging buildings, blocking campus walkways and paths. Due to the vast number of trees in both the City of Davis and Woodland, high winds can cause trees to fall on power lines, causing power outages, and can also fall on people and cars. People who live in homes with large tree branches over their roofs are particularly susceptible to high winds.

Mobile home parks are vulnerable to high wind due to their light frame construction. There are mobile home parks located in all four cities and in the unincorporated county (see figure 3-15 below, red circles indicate mobile home parks).

Access and Functional Needs
There are times when high wind events coincide with PG&E Public Safety Power Shutoffs.

When a high wind event coincides with PG&E’s PSPS event, access and functional needs individuals are impacted either due to being a medical baseline customer, requiring an electrically dependent medical device, or requiring electricity to meet other needs. Other high wind events that affect power, such as when a tree falls on a power line, can also impact those who are dependent on electricity for their medical needs. 305
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Figure 3-15: Mobile Home Locations in Yolo County
Source: GIS
During periods of high winds and dry vegetation, wildfire risk also increases. High winds that occur during periods of extreme heat can cause PSPS events to be declared in the County as well.

Although high winds do affect our agricultural community and has previously resulted in crop damage losses, it’s greatest affect is when this hazard is compounded with extreme heat and already drought conditions which affects our agricultural community. The agricultural community is most vulnerable with this combination of extreme heat, high winds, and high fire risks as noted by the previous USDA Drought declarations.

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
Yolo County’s land use, building code, and zoning ordinances regulate development to mitigate hazards. These regulations on land use and development would reduce the impact of high wind on buildings, residences, and critical infrastructure. As Yolo County continues to adopt development standards and designs that account for and help to reduce future climate change impacts, future development trends should reduce the impact of high wind on property, assets, and critical infrastructure in Yolo County. Population patterns will not affect the vulnerability or impacts of high wind events in Yolo County. New housing developments that may arise due to increased populations would continue to follow land use and development regulations which would continue to reduce the impact of high winds on buildings and residences. 306
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FUTURE CLIMATE INDICATORS
Climate change effects on weather patterns such as high wind are still not well understood.

However, given that high wind continues to impact Yolo County through increased wind/rain winter storms, future climate change would negatively impact not only vulnerable populations, but will continue to affect populations living in Yolo County due to the damage potential high winds have throughout the county.

3.3.6 TORNADO

HAZARD/PROBLEM DESCRIPTION
Tornadoes are rotating columns of air marked by a funnel-shaped downward extension of a cumulonimbus cloud whirling at destructive speeds of up to 300 mph, usually accompanying a thunderstorm. Tornadoes are the most powerful storms that exist, and damage paths can be more than one mile wide and 50 miles long. Tornadoes can affect the Yolo County area primarily during the rainy season in the late fall and early spring. The Enhanced Fujita Scale (see Figure 3-16) is commonly used to rate the intensity of tornadoes in the United States based on the damages that they cause.

Figure 3-16: Enhanced Fujita Scale

LOCATION AND EXTENT
Compared to the areas east of the Rocky Mountains, tornado occurrence over the western United States is much less frequent. However, climatological studies reveal certain subregions throughout the west where there is a significant increase in tornado occurrence. Two of the regions are in California: the Los Angeles area, and the Central Valley of California comprising the Sacramento and San Joaquin Valleys. A tornado could essentially form anywhere in Yolo County, though they are rare and often of low intensity. The geographic extent of tornado is 307
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Limited with 10-25% of the Yolo County Operational Area affected by this hazard. The largest recorded tornado in the Yolo County area formed in Sacramento in 1978 and registered as an EF2, damaging an elementary school and several homes and businesses. Since the last plan update, there has been one documented accordance of a tornado in Yolo County according to NCDC:
• 9/28/2019: An unseasonably cold upper-level low pressure system brought showers and thunderstorms to the Valley, which brought accumulating and damaging hail and a weak tornado to the Davis. A tornado was reported by a University of California Davis atmospheric science student. The student was reported to be east of highway 101a and highway 29 around 5:41 pm (PST) and filmed the tornado.

Additional historic tornado touchdowns in Yolo County include:
• 3/20/2005: An EF-0 tornado traveled through an agricultural area. Damage was caused to a property fence and to a grove of almond trees in Dunnigan (see figure 3-17) • 2/21/2005: An EF-0 tornado touched down in the Southport neighborhood of West Sacramento. Primarily tree and fence damage occurred, though other minor damage from flying debris was noted.
• 1/28/2014: An EF-0 tornado was observed and recorded over Conaway Ranch just southeast of Woodland, touching down near County Roads 103 and 25. The tornado traveled about 100 yards before lifting up and touching down again and traveling another 100 yards. No visible damage was observed. (see figure 3-18) The geographical extent of a Tornado in the Yolo County Operational Area would be Limited with only 10-25% of the operational area affected. Although a tornado could be potentially experienced at any of the lower elevations of Yolo County and could potentially be an EF-2. 308
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Figure 3-17: EF-0 Tornado in Dunnigan
Source: GIS
Figure 3-18: EF-0 Tornado southeast of Woodland
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Source: GIS

PAST OCCURRENCES
There have been no Federally or state disaster declarations due to tornadoes in Yolo County, according to Table 3-5.

LIKELIHOOD OF FUTURE OCCURRENCE
Occasional - The probability of future occurrences in the next 100 years is Occasional:

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

CLIMATE CHANGE AND TORNADOES
The different components that contribute to tornadoes include warm, moist air, an unstable atmosphere, and wind at different levels moving in different directions at different speeds, known as wind shear. As the global temperature rises, the hotter atmosphere can hold more moisture. This increases atmospheric instability. However, as global temperature increases, it decreases wind shear. So, with these varying factors, it is hard to determine how climate change affects tornadoes.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – Medium
Tornadoes can cause damage to property and loss of life. While most tornado damage is caused by violent winds, most injuries and deaths generally result from flying debris. Property damage can include damage to buildings, fallen trees and power lines, broken gas lines, broken sewer and water mains, and the outbreak of fires. Agricultural crops and industries may also be damaged or destroyed. Access roads and streets may be blocked by debris, delaying necessary emergency response. Trees and other infrastructure may experience minor damage, as has occurred in the previous occurrences of tornadoes touching down in Yolo County. The potential does exist for an EF-0 or an EF-1 tornado to cause injury and death, as has occurred with other tornadoes of this intensity across the Country.

While unlikely, a stronger EF-2 tornado does have the potential to occur in Yolo County and could cause considerable damage to buildings and infrastructure. Such a tornado could destroy mobile homes, tear roofs off well-constructed houses, shift the foundations of frame houses, and lift cars off the ground. Figure 3-15 showing the locations of the mobile home parks in Yolo County can be found in Section 3.3.5 High Wind.
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A greater amount of property is vulnerable to damage from a tornado than a regular wind due to the higher wind speeds of tornado. Like high winds, tornadoes could cause damage to agricultural lands from erosion (soil loss), dry land farming seed loss, windblown weeds, and downed trees. Livestock that may be contained in these structures may be injured or killed, causing economic harm to the rancher who owns both the structure and the livestock.

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
All future development will be affected by adverse weather/storms. The continued ability to withstand impacts lies in sound land use practices and consistent enforcement of codes and regulations for new construction areas. Land use policies, zoning and building ordinances, identified in the County’s General Plan address the secondary impacts of severe weather. With these regulations, the County is equipped to deal with future growth and associated impacts of severe weather. As Yolo County continues to adopt development standards and designs that account for and help to reduce future climate change impacts, future development trends should reduce the impact of tornadoes on property, assets, and critical infrastructure in Yolo County. It is anticipated that population increases would occur in the Cities of Yolo and not in the unincorporated or rural areas of Yolo County, where previous tornado occurrences were more likely. Thus population patterns would not affect vulnerability or the impacts of tornado events in Yolo County.

FUTURE CLIMATE INDICATORS
Climate change effects on weather patterns, storms, and extreme events like tornadoes are not well understood. High wind events continue to impact Yolo County, and the potential of tornadoes may increase with increase in storm severity and more extreme weather patterns. If it is determined that climate change increases the risk of tornadoes in Yolo County, this would negatively impact vulnerable populations, and increase the impact that a tornado would have on critical infrastructure, assets, and property.

3.4 DAM FAILURE
Dams are manmade structures built for a variety of uses including flood protection, power generation, agriculture, water supply, and recreation. When dams are constructed for flood protection, they are usually 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.

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Dam failure is the uncontrolled release of impounded water from behind a dam. Flooding, earthquakes, blockages, landslides, lack of maintenance, improper operation, poor construction, vandalism, and terrorism can all cause a dam to fail. Dam failure causes downstream flooding that can affect life and property. Dam failures can result from any one or a combination of the following causes:
• Earthquake
• Inadequate spillway capacity resulting in excess overtopping flows. • Internal erosion caused by embankment or foundation leakage, or piping or rodent activity.
• Improper design
• Improper maintenance
• Negligent operation
• Failure of upstream dams on the same waterway
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. Electric generating facilities and transmission lines could also be damaged and affect life support systems in communities outside the immediate hazard area. Associated water supply, water quality and health concerns could also be an issue. Factors that influence the potential severity of a full or partial dam failure are the amount of water impounded; the density, type, and value of development and infrastructure located downstream; and the speed of failure.

In general, there are three types of dams: concrete arch or hydraulic fill, earth and 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 earth-rockfill dam fails gradually due to erosion of the breach; a flood wave will build gradually to a peak and then decline until the reservoir is empty. And a concrete gravity dam can fail instantaneously or gradually with a corresponding buildup and decline of the flood wave.

The California Department of Water Resources (DWR) Division of Safety of Dams (DSOD) has jurisdiction over impoundments that meet certain capacity and height criteria. Embankments that are less than six feet high and impoundments that can store less than 15 acre-feet are nonjurisdictional. Additionally, dams that are less than 25 feet high can impound up to 50 acre-feet without being jurisdictional. The Cal DWR DSOD assigns hazard ratings to large dams within 312
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the State. The following two factors are considered when assigning hazard ratings: existing land use and land use controls (zoning) downstream of the dam. Dams are classified in three categories that identify the 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.

Since 1929, the state has supervised all non-federal dams in California to prevent failure for the purpose of safeguarding life and protecting property. Supervision is carried out through the state’s Dam Safety Program under the jurisdiction of DWR. The legislation requiring state supervision was passed in response to the St. Francis Dam failure and concerns about the potential risks to the general populace from several water storage dams. The law requires:
• Examination and approval or repair of dams completed prior to August 14, 1929, the effective date of the statute.
• Approval of plans and specifications for and supervision of construction of new dams and the enlargement, alteration, repair, or removal of existing dams. • Supervision of maintenance and operation of all dams under the state’s jurisdiction.

The 1963 failure of the Baldwin Hills Dam in Southern California led the Legislature to amend the California Water Code to include within state jurisdiction both new and existing off-stream storage facilities.

Dams and reservoirs subject to state supervision are defined in California Water Code §6002 through §6004, with exemptions defined in §6004 and §6025. In administering the Dam Safety Program, DWR must comply with the provisions of the California Environmental Quality Act (CEQA). As such, all formal dam approval and revocation actions must be preceded by appropriate environmental documentation.

In 1972, Congress moved to reduce the hazards from the 28,000 non-federal dams in the country by passing Public Law 92-367, the National Dam Inspection Act. With the passage of this law, Congress authorized the U.S. Army Corps of Engineers (USACE) to inventory dams located in the United States. The action was spurred by two disastrous earthen dam failures during the year, in West Virginia and South Dakota that caused a total of 300 deaths.

The Water Resources Development Act of 1986 (P.L 99-662) authorized USACE to maintain and periodically publish an updated National Inventory of Dams (NID). The Water Resources 313
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Development Act of 1996 (P.L. 104-303), Section 215, re-authorized periodic updates of the NID by USACE.

LOCATION AND EXTENT
In the area around Yolo County there are seven dams of various types of construction and the failure of any one would cause some degree of flooding in Yolo County:
• Cache Creek Dam (Clear Lake) – Yolo County Flood Control and Water Conservation District
• Monticello Dam (Putah Creek) – U.S. Bureau of Reclamation • Indian Valley Dam (Cache Creek) – Yolo County Flood Control and Water Conservation District
• Shasta Dam (Sacramento River) – U.S. Bureau of Reclamation • Oroville Dam (Feather River) – California Department of Water Resources • Folsom Dam (American River) – U.S. Bureau of Reclamation • Nimbus Dam (American River) – U.S. Bureau of Reclamation According to the California Department of Water Resources Division of Safety of Dams, there are Jurisdictional Dams located within Yolo County. Details on these dams are listed below in Table 3-17. These jurisdictional dams are not anticipated to have adverse effects to populated areas due to either their size and/or control features.

Table 3-17: Jurisdictional Dams – Dams within Jurisdiction of the State of California, Sept 2022.

Dam No. Dam Name Owner
Name
Dam
Height
Reservoir
Capacity
Certified
Status
Condition
Assessment
County
National
ID No.

Latitude Longitude Owner Type Crest
Length
Dam
Type
Downstream
Hazard
Reservoir
Restrictions
Year
Built
1-84 Cache Creek
Settling Basin Weir
Central
Valley
Flood
Protection
Board
29 3,800 Certified Satisfactory Yolo
CA01348 36.68 -121.67 State
Agency
40,083 Earth Low No 1993
1391-3 Davis Creek Dam Homestake
Mining
Company
105 6,079 Certified Satisfactory Yolo
CA01223 38.86 -122.35 Private
Company,
Corporation,
LLC,
partnership
953 Earth High No 1985
Source: California Department of Water Resources, Division of Safety of Dams 314
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The geographic extent of a Dam failure in Yolo County is Extensive with 50-100 percent of the operational area potentially being affected by a failure of any one major dam. Parts of the County would be completely inundated.

Cache Creek Dam
Cache Creek Dam is five miles from Clear Lake in Lake County. It was built in 1914 to store winter water in Clear Lake that would normally runoff into the Sacramento River. The dam has fifteen 6-foot-wide by 7-foot-high, concrete, low-level bay openings for releasing water for irrigation and flood control. A failure of Cache Creek Dam could cause inundation over the length of Cache Creek itself and could overbank the creek at various points (especially low lying). This could cause evacuation by Yolo County of properties close to the creek and sheltering.

Monticello Dam
Monticello Dam is a thin arch concrete structure 270 feet high. It impounds a maximum of 1,602,300 acre-feet creating Lake Berryessa in Napa County, 10 miles west of Winters. In the event of failure, Monticello Dam presents a high hazard to downstream areas and extensive loss of life and property would likely occur. Waters from a Monticello Dam failure will travel East along Putah creek. This would cause an evacuation of the entire City of Winters and most of the outlying residents in the unincorporated area (the responsibility of the County). The majority of the City of Davis and the University of California Davis would also be affected by inundation of varying heights.

Large uncontrolled water releases into Putah Creek could occur resulting from either a major or partial dam failure, or earthen slides into Lake Berryessa, which could cause overtopping of the dam. Seismic evaluation of Monticello Dam indicates it could withstand an earthquake of Richter magnitude 6.5 with the epicenter located 0.5 miles from the dam. Thus, the dam is considered secure from such an occurrence. The topography of the lake relative to the size of potential slides makes the possibility of dam overtopping very unlikely. Any landslide that would move into the outlet works or spillway area would be especially dangerous to the dam.

The unstable area adjacent to the dam crest at its contact with the left abutment will be closely monitored by the dam tender during the raining season and after seismic activity. Landslides into the downstream channel could impound water but releases would be expected to be gradual as the new “dam” was eroded away. Severe storms are not expected to cause rapid rises in the water surface of Lake Berryessa.
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Indian Valley Dam
Indian Valley Dam is an earth-filled dam producing a lake of 359,000 acre-feet storage capacity (maximum). The dam is located in Lake County, northwest of Yolo County, on the North Fork of Cache Creek. Depending upon the rate of discharge following dam failure the area of potential inundation extends along the Cache Creek all the way to the I-80 and the Yolo Bypass.

The Yocha Dehe Wintun Nation as well as unincorporated communities in the Capay Valley are vulnerable to an Indian Valley Dam failure. Tribal housing and agricultural lands are particularly susceptible, as is the State Route 16 transportation corridor. An Indian Valley Dam failure would cause an evacuation of Yocha Dehe Wintun Nation citizens in the Tribe’s primary housing area, evacuations throughout the unincorporated area from Rumsey through to Brooks, areas within Esparto and potentially inundate areas on the northwest side of the cities of Woodland and Davis.

Shasta Dam
Shasta Dam is a concrete gravity dam. The reservoir (Lake Shasta) has a maximum storage capacity of 4,552,000 acre-feet. The dam is in Shasta County north of Summit City. Dam failure would result in varying degrees of inundation to eastern and northeastern Yolo County, waters travelling South from a failure at Shasta could affect the town of Dunnigan and West Sacramento if the waters are held to the east by the Yolo Bypass levee system. Knights Landing and West Sacramento are particularly susceptible.

Oroville Dam
Oroville Dam is an earth-filled dam. The reservoir (Oroville Lake) has a maximum storage capacity of 3,500,000 acre-feet. The dam is in Butte County, northeast of Yolo County, above the Sacramento River. Failure of the dam would overwhelm the Yolo Bypass, where agricultural land is susceptible to flooding, and would threaten West Sacramento and the eastern side of Woodland. Cal OES also maintains a buffer evacuation boundary within their “Oroville Dam Failure Response Plan”, which indicates an evacuation of Woodland, Davis, and West Sacramento should the Oroville Dam fail.

Folsom Dam
Folsom Dam is a concrete and earth dam. The lake has a maximum storage capacity of 977,000 acre-feet. The dam is in Sacramento County, east of Yolo County on the American River.

Waters from a Folsom Dam failure will travel west to the Sacramento River. If the Sacramento Weir were opened to alleviate pressure, waters would flow into the Yolo Bypass as part of normal flood control design. Dam failure would result in some degree of inundation to areas of Yolo County bounded by the west levee of the Yolo Bypass, on the north by a point on Old River Road one-half mile south of Kiesel Crossing and on the south by the county line. West Sacramento is vulnerable to flooding if the Sacramento River levee surround it were to fail. 316
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Nimbus Dam
Nimbus Dam is a concrete gravity dam. The reservoir (Lake Natomas) has a maximum storage capacity of 8,760 acre-feet. The dam is in Sacramento County, east of Yolo County. All actions relating to a failure of Nimbus Dam would be identical to those required by a failure of Folsom Dam except the resulting inundation would be less severe.

See Figure 3.19 for a map of dams and dam inundation zones in and around Yolo County 317
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Figure 3.19: Dams and Dam Inundation Zones in and around Yolo County Source: California Office of Emergency Services GIS Department California has had about 45 failures of non-federal dams. The failures occurred for a variety of reasons, the most common being overtopping. Other reasons include specific shortcomings in the dams themselves or an inadequate assessment of surrounding geomorphologic characteristics.

California’s first notable dam failure was in 1883 in Sierra County, while the most recent failure occurred in 1965. The most catastrophic event was the failure of William Mulholland’s infamous St. Francis Dam, which failed in 1928 and killed an estimated 450 people, only slightly fewer than the 1906 San Francisco earthquake. The actual number of dead from the St. Francis Dam failure was likely substantially higher. San Francisquito Canyon, which was flooded in the event, was home to hundreds of transients and illegal immigrants who were never accounted for in the death totals.

No previous occurrences have occurred in Yolo County, however, there have been recent minor failures to dams (Folsom and Oroville Dams) located outside of Yolo County. Based on information from the Sacramento County Hazard Mitigation Plan, there have been two dam failure incidents at Folsom Dam since 1994 that could have had the potential to affect Yolo County. However, these incidents were quite limited in scope and since the incidents occurred, improvements to the Folsom Dam system have been made.

July 17, 1995 – At the Folsom Dam, a spillway gate, gate #3 of Folsom Dam failed, increasing flows into the American River significantly. The spillway was repaired, and the U.S. Bureau of Reclamation carried out an investigation of the water flow patterns around the spillway using numerical modeling. No flooding occurred because of the partial failure, but due to the location of the dam in proximity to the City of Folsom, possible flooding was a major concern.

May 15, 1997 – Cavitation damage to river outlet works occurred at Folsom Dam. Damage was discovered just downstream of gate #3. The damage consisted of a hole in the floor of the conduit measuring approximately 42 feet long, 15 feet wide, and 6 feet deep. Subsequent inspections of the other conduits revealed similar damage downstream of gate #4. Also, the beginning of cavitation damage was found downstream of gate #2. Minor damage was found in the other five conduits. No flooding was associated with this damage.

A steady barrage of storms in early 2017 resulted in serious damage to the Lake Oroville spillways. This included a concrete failure on the lower chute of the gated flood control spillway, severe erosion under the gated spillway, and erosion in the areas on the hillside beneath 318
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the emergency spillway. A mandatory evacuation was ordered in Butte, Yuba, and Sutter Counties. Yolo County acted swiftly to support the evacuees by opening a shelter located at the Yolo County Fairgrounds. The shelter was open for four days until the evacuation order was lifted.

A federal emergency declaration was declared for the Oroville Dam incident. The February storms of 2017 were exacerbated by the potential failure of the Lake Oroville Emergency Spillway and Yolo County proclaimed an emergency for the February storms (2/1 - 2/23/2017) and due to the impacts from the Oroville incident.

PAST OCCURRENCES
There has been no Federally or state disaster declarations due to dam failure in Yolo County, as shown in Table 3-5.

LIKELIHOOD OF FUTURE OCCURRENCE
Unlikely - Yolo County remains at risk to dam breaches/failures from numerous dams under a variety of ownership and control and of varying ages and conditions. Given the number and types of dams in and around the County, the potential exists for future dam issues in Yolo County. The probability of a catastrophic dam failure that would impact Yolo County and its jurisdictions is 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 AND DAM FAILURE
Increases in both precipitation and heat causing snow melt in areas upstream of dams could increase the potential for dam failure and uncontrolled releases that may affect Yolo County.

Dam designs and operations are based on hydrographs from historical records. If the hydrographs change significantly over time because of climate change, current dam designs and operations may become overwhelmed. Specified release rates and impounded thresholds may have to be changed, which could result in increased discharges downstream of these dams, thus increasing the probability and severity of a dam inundation.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – Medium
Portions of Yolo County are located downstream of several dams with large inundation areas. In the unlikely event that any of these dams were to fail, the inundation zones indicate areas that could potentially be flooded. If the dams at Indian Valley Reservoir, Lake 319
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Berryessa or along the Sacramento, Feather or American rivers were to fail, the cities of West Sacramento, Winters and Davis would be entirely inundated by floodwaters, as would much of the city of Woodland. The unincorporated communities of Rumsey, Capay, Madison, Knights Landing and Clarksburg and parts of Guinda, Esparto, Monument Hills and Yolo are also located entirely within dam inundation zones.

Dam failure flooding would vary by community depending on which dam fails and the nature and extent of the dam failure and associated flooding. Based on the risk assessment, it is apparent that a major dam failure could have a devastating impact. Dam failure flooding presents a threat to life and property, including buildings, their contents, and their use (such as water treatment). Large flood events can affect crops and livestock as well as lifeline utilities (e.g., water, sewerage, and power), transportation, jobs, tourism, the environment, and the local and regional economies.

The failure of any of the dams previously mentioned could flood downstream areas and would result in loss of life and property. According to the jurisdictional dam response plans, a catastrophic failure of any of these dams would have a significant impact on Yolo County.

Complete devastation could occur in and along the river bottoms and up the banks above normal river levels at a point from the dams themselves down river to near the ocean where the rivers widen. Water levels could be many times higher than those recorded in the worst floods. The potential magnitude of a dam failure depends on the time of year and the base flow in the river when the failure occurs. During the winter months when the river flows are higher, the impact to the area would be much greater and evacuation times much less.

Vulnerability of the Yolo County Operational Area to dam failure is reflected in the profile for each dam above. See Table 3-18 for the number of parcels and structure value of properties within the indentation of four dams that can impact the Yolo County Operational Area:

Table 3-18: Parcel Count and Structure Value Vulnerability within Inundation Zones Dam Inundation Zone Parcel Count Structure Value Areas Affected by Dam (Inundation Area)
Folsom 16,250 $3,195,682,113 25,655 Acres
Monticello 21,347 $5,128,545,854 111,530 Acres
Indian Valley 8,238 $1,901,870,208 92,087 Acres
Shasta 930 $63,035,925 71,775 Acres
Oroville No information available
Nimbus No information available
Source: Yolo County Assessor’s Office

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
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Dam failures are low probability, high-consequence events which is not typically practical for local governments to regulate new development in dam failure inundation areas. Our County General Plan does direct land use and zoning ordinances adopted under state law. The Health and Safety element of the General Plan establishes standards and plans for the protection of the community from hazards. However, dam failure is not a stand-alone aspect of the General plan, whereas flood hazards are. Yolo County has established comprehensive policies regarding sound land use in identified flood hazard areas and established flood protection agencies as discussed throughout the levee failure and flood hazard profiles. Most of the areas vulnerable to the more severe impacts form dam failure intersect the mapped flood hazard areas. Flood-related policies in the general plan will help to reduce the risk associated with the dam failure hazard for all future development in the City. Any new developments outside of a flood hazard area will most likely not include provisions that would mitigate the impacts from a dam failure. As mentioned previously dam failures would flood downstream areas and increases in populations to those areas would result in increased vulnerabilities. Population patterns would affect the impact of dam failures, if populations expand into the unincorporated areas which are within the dam inundation zones. However, there is more anticipated population growth within the Cities in Yolo County rather than the unincorporated areas.

3.5 DROUGHT
Drought is a gradual phenomenon. A drought is a deficiency in precipitation over an extended period, usually a season or more, resulting in a water shortage causing adverse impacts on vegetation, animals, and/or people. It is a normal recurrent feature of climate that occurs in virtually all climate zones, from very wet to very dry. Drought is a temporary aberration from normal climatic conditions and can thus vary significantly from one region to another. Because droughts occur slowly, over a multi-year period, and it is often not obvious or easy to quantify when a drought begins and ends. Water districts normally require at least a 10-year planning horizon to implement a multiagency improvement project to mitigate the effects of a drought and water supply shortage.

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. There are several types of droughts which can often be defined regionally based on its effects:
• Meteorological drought is usually defined by a period of below average water supply, based on the degree of dryness (in comparison to normal or average) and the duration of the dry period. Drought onset generally occurs with a meteorological drought. • Agricultural drought occurs when there is an inadequate water supply to meet the needs of the state’s crops and other agricultural operations such as livestock. Agricultural drought links various characteristics of meteorological (or hydrological) drought to 321
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agricultural impacts, focusing on precipitation shortages, soil water deficits, reduced ground water or reservoir levels needed for irrigation. • Hydrological drought is defined as deficiencies in surface and subsurface water supplies. It is generally measured as stream flow, snowpack, and as lake, reservoir, and groundwater levels. Hydrological drought usually occurs following periods of extended precipitation shortfalls.
• Socioeconomic drought occurs when a drought impacts health, well-being, and quality of life, or when a drought starts to have an adverse economic impact on a region.

LOCATION AND EXTENT
Since drought is a regional phenomenon, it affects the whole County. Speed of onset of drought is slow, while the duration varies from short (months) to long (years). Drought in the United States is monitored by the National Integrated Drought Information System (NDIS). A major component of this portal is the U.S. Drought Monitor. The Drought Monitor is a process that synthesizes multiple indices, outlooks and local impacts, into an assessment that best represents drought conditions. The outcome of each Drought Monitor is a consensus of federal, state, and academic scientists who are familiar with the conditions in their respective regions. A snapshot of the drought conditions in California and Yolo County (May and Jan 2023) can be found in Figure 3-20. Snapshots from 2018 through 2022 is shown in Figure 3-21. 322
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Figure 3-20: California and Yolo County – Current Drought Status (May and Jan 2023) 324
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Figure 3-21: California and Yolo County Drought Status (2018-2022) 325
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As shown in the previous figures, drought is tracked by the U.S. Drought Monitor. The Drought Monitor includes a scale to measure drought intensity:
 None
 D0 (Abnormally Dry)
o Short-term dryness slowing planting, growth of crops
o Some lingering water deficits
o Pastures or crops not fully recovered
 D1 (Moderate Drought)
o Some damage to crops, pastures
o Some water shortages developing
o Voluntary water-use restrictions requested
 D2 (Severe Drought)
o Crop or pasture loss likely
o Water shortages common
o Water restrictions imposed
 D3 (Extreme Drought)
o Major crop/pasture losses
o Widespread water shortages or restrictions
 D4 (Exceptional Drought)
o Exceptional and widespread crop/pasture losses
o Shortages of water creating water emergencies
In Yolo County, the Yolo County Flood Control and Water Conservation District is the General Maintaining Agency under the Sustainable Groundwater Management Act (SGMA). Through SGMA, the groundwater user community will decide what types of rules will, or will not, be enacted to protect groundwater resources.

Drought affects all areas of Yolo County, though drought conditions can be greater in the southeastern part of the county. The geographic extent of a drought in Yolo County is Significant with 35-50 percent of the operational area potentially being affected by drought.

Drought conditions of D4 on the U.S. Drought Monitor could cover most of Yolo County, east of the Blue Ridge Mountains.

Historically, California has experienced multiple severe droughts. According to the California DWR, droughts exceeding three years are relatively rare in Northern California, the source of much of the State’s developed water supply. The 1929-34 drought established the criteria commonly used in designing storage capacity and yield of large northern California reservoirs.

The driest single year of California’s measured hydrologic record was 2013. A drought 326
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emergency was declared for the state in 2014, and lifted in 2017 after a series of strong winter storms. Drought also occurred throughout California in 1976-77 and in 1987-92 causing depletion of water throughout the Yolo County Operational Area but overall impacts were minimal and Yolo County did not issue a local emergency for either event.

PAST OCCURRENCES
There has been one Federal disaster related to drought in Yolo County issued in 1977. And no state disaster declarations due to drought, as shown in Table 3-19.

Table 3-19 Yolo County State and Federal Disaster Declarations, 1965-2023* Year Disaster Name Disaster Type Disaster #
State
Declaration #
Federal
Declaration #
1977 Drought Drought EM-3023-CA - 1/20/1977
* Data from Table 3-5: Yolo County State and Federal Disaster Declarations, 1965-2023. All years that did not have Drought declarations were removed
Another database of disaster declarations comes from the USDA. This database shows agricultural disasters that result from natural hazards like drought. This database was searched from 2012-2023, and the results for drought for Yolo County are shown in Table 3-20.

Table 3-20 Yolo County – USDA Disaster Declarations 2012-2023 Year Declaration Number Primary or
Contiguous County
Disaster Type
2012 S3452 Primary Drought
2013 S3569 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3626 Contiguous Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3637 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2014 S3743 Primary Drought
2014 S3797 Contiguous Drought
2015 S3784 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2016 S3952 Primary Drought, High winds, Wildfire,
Heat/Excessive heat/high temp (incl.
low humidity), Insects
2017 S4163 Primary Drought
2020 S4691 Contiguous Drought
2020 S4697 Primary Drought
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2021 S4916 Primary Drought
2022 S5146 Primary Drought
* Data from Table 3-8: Yolo County -USDA Disaster Declarations 2012-2023. All years that did not have Drought declarations were removed.

There have been 47 NCDC drought events in Yolo County. No deaths, injuries, property damage or crop damage were reported to the NCDC from these events.

Table 3-21: NCDC’s Drought Events for Yolo County 1950-2/23/2023* Event Type
Number
of
Events Deaths Injuries
Property
Damage
Crop
Damage
Drought 47 0 0 0 0
In the unincorporated County, droughts have been recorded in 1976-1977, 1988-1992, 2007- 2009, and 2014-2016. Groundwater levels reached the lowest point ever recorded in the 1976- 1977 drought, and the second lowest point ever recorded in 2014. Collapsed well housings in the Knights Landing area occurred during the height of the drought.

LIKELIHOOD OF FUTURE OCCURRENCE
Likely - The probability of future occurrences in the next 100 years is Likely: Between 10 percent and 100 percent chance of occurrence next year or happens every year. Drought levels can be greatly reduced with a strong winter storm season, as had occurred in 2023 and previously in 2017.

CLIMATE CHANGE AND DROUGHT
According to the U.S. Climate Resilience Toolkit modeling, Yolo County has a very high national risk index rating to drought due to Climate change (see Figure 3-22). 328
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Figure 3-22: Yolo County Hazard Report: Drought (page 2) Source: U.S Climate Resilience Toolkit
The most critical indicators of climate change impacts in Yolo County are temperature change and wildfire projections. Increased temperatures could increase water supply demands from users, evapotranspiration, and others, therefore increasing vulnerability to drought and/or water shortage impacts. Projected increased temperature values are expected to range from 4.6℉ to

5.2℉, with the greatest shifts in the eastern portion of the county which would affect multiple domestic wells. Increasing wildfire frequency and severity can increase vulnerability of water sources. The most susceptible area being the northwestern portion of Yolo County, again affecting multiple domestic wells. These climate change impacts would increase vulnerability to populations living in these areas that rely on well water/ground water sources. A dry year increases physical vulnerability. Due to the higher number of recent dry years, it will also increase physical vulnerability of water supply conditions to the northwestern part and some western border areas of the county which have already experienced a higher frequency of dry years in 2018-2022.

VULNERABILITY ASSESSMENT AND IMPACTS
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Vulnerability – High
Drought is different than many of the other natural hazards in that it is not a distinct event and usually has a slow onset. Drought impacts are wide-reaching and may be economic, environmental, and/or societal. The most significant impacts associated with drought in Yolo County are those related to water intensive activities such as agriculture, wildfire protection, municipal usage, commerce, tourism, recreation, and wildlife preservation. Also, allocations go down during a drought which results in reduced water availability. These issues become particularly evident in shallow wells, such as the ones near Capay. Voluntary conservation measures are typically implemented during extended droughts. A reduction of electric power generation and water quality deterioration are also potential problems. Drought conditions can also cause soil to compact and not absorb water well, potentially making an area more susceptible to flooding. Drought has the potential to significantly impact Yolo County’s agriculture commodities, requiring changes in irrigation practices, changes in crop patters, greater reliance on groundwater, and discontinuation of certain agricultural activities. Two critical dry years (2021-2022) following a dry year (2020) resulted in declining groundwater levels. Although wet conditions of 2019 provided for 5 feet of groundwater recovery between Fall 2018 and 2019, the dry and critical conditions of 2020, 2021, and 2022 led to 4 feet, 13 feet, and 5 feet of groundwater decline. Communities that rely on well water, such as our unincorporated areas like Dunnigan, Zamora, and Yolo are susceptible to drought when groundwater levels are lower, and experience dry wells from drought conditions, resulting in the County needing to provide water hauling resources to domestic well owners experiencing drought. Drought conditions increase vulnerability in our county to those who live in the unincorporated areas of Yolo County who depend on well water sources, those residences are also in the areas were vulnerable populations reside such as those who have lower incomes, elderly, or have other contributing factors such as disability/mobility issues.

Water Supply
Several recent studies have shown that Yolo County’s water supply systems are sensitive to climate change. However, experts are uncertain about what the overall effects will be on water supply. Some models indicate that drier conditions will cause decreased reservoir supplies and river flows. Other models predict wetter conditions with increased reservoir inflows and storage, and increased river flows. Increased reservoir inflows can put stress on dams, increasing the susceptibility of Yolo County to dam failure. Increased river flows can put stress on levees, increasing the susceptibility of Yolo County to levee failure. Despite this uncertainty, it is still widely accepted that changes in water supply will occur and that water yields from reservoirs are expected to be unreliable. Yolo County must prepare for a future where competition for water resources between farming, cities, and the environment is greater than at the present time.

Furthermore, climate change is also expected to result in more variable weather patterns, leading 330
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to longer and more severe droughts, which could lead to lower aquifer levels for those farmers dependent on groundwater. Additional groundwater pumping can increase the susceptibility of Yolo County to land subsidence.

The Sustainable Groundwater Management Act (SGMA) establishes a framework for sustainable, local groundwater management. SGMA requires groundwater-dependent regions to halt overdraft and bring basins into balanced levels of pumping and recharge. The Yolo County Flood Control and Water Conservation District is the oversight agency for SGMA in the Yolo Sub-basin. Ground water levels are measured in the Yolo County Flood Control and Water Conservation District’s 160-well network each spring and fall. The graph below (Figure 3-23) shows the average ground water level of the wells with long periods of record. After a sharp decline in the fall of 2022 caused by an exceptionally dry winter and spring that prevented the district from providing any surface water for irrigation, the 2023 spring’s groundwater levels showed the second-largest recovery on record, just behind the spring of 1978.

Figure 3-23: Average Groundwater Depth in Yolo County 1975-2023 Source: Yolo Subbasin Groundwater Agency
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The current groundwater conditions show 38 wells (25% of total) are at below normal or worse conditions. And out of 3700 monitoring wells in the State of California, 150 are in Yolo County.

There are 4 State Smal Water Systems in Yolo County as indicated in the Figure 3-24 below (shown with black circles), there are 1727 Domestic wells (show in orange dots), and according to Department of Water Resources (DWR) risk/vulnerability score ranging from 0 (low vulnerability) to 100 (high vulnerability), DWR ranks Yolo County with an average total physical vulnerability score of 24.61. Areas with high physical vulnerability are somehow scattered throughout the county, but seems to be concentrated in the central, southern, and northwest of the County in the Capay Valley, as show in Figure 3-25 (darker colors represent higher vulnerability). Between 2019-2022, there have been a few number of wells in the southern border and small portion of southeast of the county that have experienced significant groundwater declines which indicate increase vulnerability as it puts wells at higher risk of shortage. Examining the water quality risk, a higher water quality risk contributes to a higher physical vulnerability for water sources. In the east and central part of the County, there is a higher water quality risk.

Figure 3-24: State Small Water Systems & Domestic Wells in Yolo County Source: Yolo County Drought and Resilience Plan, Risk Assessment DWR Tool, 2024 332
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Figure 3-25: Physical Vulnerability Total Score
Source: Yolo County Drought and Resilience Plan, Risk Assessment DWR Tool, 2024 Access and Functional Needs Populations
However, physical and social vulnerabilities do not directly overlap with a CDC’s Social Vulnerability Index Score of 0.68 in Yolo County (see Figure 3-26). High social vulnerability scores are more prevalent in the northern half of the county, especially around Dunnigan Hills, regardless of physical vulnerability scores, suggesting a higher influence of socioeconomic factors in those regions. On the contrary, areas with lower social vulnerability scores are more prevalent in the eastern and southern parts of the County. The percentage of the population below the poverty levels are higher in the central, northwest and a portion of the east compared to the rest of the county. It is also in the northwest and northeast of the county with more than 70% of their population above 65 years. There are also areas in the northeast, central south, and southwest where more than 70% of the population lives in mobile homes. Given that there are a number of wells that are considered highly physically vulnerable tend to be in the northern part of the county where there is also high social vulnerability, with some in the southern part of the county, with medium social vulnerability, these populations would be significantly impacted by drought if their wells were to run dry. In addition, areas that have already experienced the presence of domestic wells running dry, will likely experience it during future dry years. 333
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Figure 3-26: CDC/ATSDR Social Vulnerability Index, 2020 Source: CDC/ATSDR
Agriculture/Land Use
Agriculture throughout the County is susceptible to drought, which can cause a decrease in crop production. Crops that rely heavily on water, such as rice, are most susceptible while nut crops and vine grown fruit are least susceptible. Other impacts include feeding and forage, altered plant populations and tree mortality. During periods of drought, vegetation can dry out which increases fire risk. Drought that occurs during periods of extreme heat and high winds can cause PSPS events to be declared in the County. Agriculture can also strain groundwater and raise water quality concerns, increasing vulnerability for domestic wells and small water systems during drought. Yolo County is heavily farmed mostly in the southern, central, and eastern parts (except a portion in West Sacramento) of the county, as well as small areas on the west alongside the Capay Valley. Drought will continue to be a concern to the Operational Area as agriculture is a major source of income and the impact of agriculture/land use in these ways will further 334
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increase the impacts of drought in Yolo County. More information on power shortage and failure can be found in Section 3.2.3.

Wildfire
A secondary impact associated with drought is wildfire. A prolonged lack of precipitation dries out vegetation, which becomes increasingly susceptible to ignition as the duration of drought extends. Drought is also associated with extreme heat, exposing people to the risk of sunstroke, heat cramps, and heat exhaustion. A higher risk of wildfire contributes to higher physical vulnerability for water sources. The eastern and central part faces little risk of wildfire, but the western part of the county, tends to have a higher risk of wildfires. More information on extreme heat and fire hazards can be found in their respective hazard profiles.

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
The demand that society places on water systems and supplies – such as expanding populations, irrigation, and environmental protection – contributes to drought impacts. There are also issues such as growing conflicts between agricultural uses of surface water and instream uses, surface water and groundwater interrelationships, and the effects of growing water demand on uses of water. One project developed to mitigate impacts of drought is Woodland-Davis Clean Water Agency Project. This regional surface water supply project provides water to more than twothirds of the urban population of Yolo County. It also serves UC Davis, a project partner. This projects largely replaces deteriorating groundwater supplies with safe, more reliable surface water supplies from the Sacramento River. Additional water conservation projects are being discussed such as groundwater recharge, re-directing/reusing water supplies and focusing on agricultural impacts which would decrease vulnerability to drought conditions in Yolo County.

Additional projects are forthcoming with the Climate Action and Adaptation plan update in 2024, which will also incorporated into the 2030 General Plan. There has also been a Yolo County Drought Taskforce that has been created to create a Yolo County Drought Resilience Plan. These efforts would decrease the impact drought would have on Yolo County.

Population patterns have the potential to increase the impact of drought due to growing water demands with increased populations. However, given the efforts being made to reduce the impact of drought in Yolo County, population increases are not anticipated to affect vulnerability to or the impacts of drought. There continues to be efforts made to mitigate drought in Yolo County which account for future anticipated population growth patterns.

3.7 EARTHQUAKE
Earthquakes are sudden rolling or shaking events caused by movement under the earth’s surface.

Earthquakes happen along cracks in the earth's surface, called fault lines, and can be felt over 335
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large areas, although they usually last less than one minute. 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.

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.

Earthquakes may also cause collateral emergencies including dam and levee failures, seiches, hazmat incidents, fires, avalanches, and landslides. The degree of damage depends on many interrelated factors. Among these are: the magnitude, focal depth, distance from the causative fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction.

The amount of energy released during an earthquake is usually expressed as a magnitude and is currently measured by seismologists on the Moment Magnitude (Mw Scale). The Mw Scale was developed to succeed the previously used Richter Scale and is measured on a scale of zero to ten with increasing values reflecting increasing intensity.

The other commonly used measure of earthquake severity is intensity, which is an expression of the amount of shaking at any given location on the ground service. Intensity is most measured on the Modified Mercalli Intensity (MMI) Scale (see Figure 3.27). 336
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Figure 3.27: Modified Mercalli Intensity Scale
Figure 3.28 gives intensities (measured on the MMI scale) that are typically observed at locations near the epicenter or earthquakes of different magnitudes.

Figure 3.28: Mercalli Scale vs. Magnitude
Ground shaking
Ground shaking is motion that occurs as a result of energy release during faulting. The damage or collapse of buildings and other structures caused by ground shaking is among the most serious seismic hazards. Damage to structures from this vibration, or ground shaking, is caused by the transmission of earthquake vibrations from the ground to the structure. The intensity of shaking and its potential impact on buildings is determined by the physical characteristics of the underlying soil and rock, building materials and workmanship, earthquake magnitude and location of epicenter, and the character and duration of ground motion.

The extent of ground shaking depends in large part on how soft the underlying soil is. Soft soils amplify ground shaking (see Figure 3.29). This was observed during the 1989 Loma Prieta Earthquake when the most significant damages experienced in San Francisco were in the Marina District, which was built on fill.
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Figure 3.29: Soil Types
Actual ground breakage generally affects only those buildings directly over or near the fault.

Ground shaking generally has a much greater impact over a greater geographical area than ground breakage. The amount of breakage and shaking is a function of earthquake magnitude, type of bedrock, depth and type of soil, general topography, and groundwater.

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

The susceptibility of a structure to damage from ground shaking is also related to the underlying foundation material. A foundation of rock or very firm material can intensify short-period motions which affect low-rise buildings more than tall, flexible ones. A deep layer of waterlogged soft alluvium can cushion low-rise buildings, but it can also accentuate the motion in tall buildings. The amplified motion resulting from softer alluvial soils can also severely damage older masonry buildings.
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Other potentially dangerous conditions include, but are not limited to: building architectural features that are not firmly anchored, such as parapets and cornices; roadways, including column and pile bents and abutments for bridges and overcrossings; and above-ground storage tanks and their mounting devices. Such features could be damaged or destroyed during strong or sustained ground shaking.

Liquefaction Potential
Liquefaction, which can occur in earthquakes with strong ground shaking, is mostly found in areas with sandy soil or fill and a high-water table located 50 feet or less below the ground surface. Liquefaction can cause damage to property with the ground below structures liquefying making the structure unstable causing sinking or other major structural damage. Evidence of liquefaction may be observed in “sand boils”, which are expulsions of sand and water from below the surface due to increased pressure below the surface.

Settlement
Settlement can occur in poorly consolidated soils during ground shaking. During settlement, the soil materials are physically rearranged by the shaking to result in a less stable alignment of the individual minerals. Settlement of sufficient magnitude to cause significant structural damage is normally associated with rapidly deposited alluvial soils or improperly founded or poorly compacted fill. These areas are known to undergo extensive settling with the addition of irrigation water, but evidence due to ground shaking is not available.

Other Hazards
Earthquakes can also cause seiches, landslides, and dam and levee failures. A seiche is a periodic oscillation of a body of water resulting from seismic shaking or other factors that could cause flooding. Earthquakes may cause landslides, particularly during the wet season, in areas of high water or saturated soils. Finally, earthquakes can cause dams to fail.

LOCATION AND EXTENT

California is seismically active because it sits on the boundary between two of the earth’s tectonic plates. Everything east of the San Andreas Fault- is on the North American Plate. The cities of Monterey, Santa Barbara, Los Angeles, and San Diego are on the Pacific Plate, which is constantly moving northwest past the North American Plate. The San Andreas Fault is considered the boundary between the two plates, although some of the motion is taken up on faults as far west as central Utah.

A fault is a “fracture or fracture zone in the earth’s crust along which there has been displacement of the sides relative to one another. For planning there are two types of faults, 339
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active and inactive. Active faults have experienced displacement in historic time, suggesting that future displacement may be expected. Inactive faults show no evidence of movement in recent geologic time, suggesting that these faults are dormant. This does not mean, however, that faults having no evidence of surface displacement within the last 11,000 years are necessarily inactive.

For example, the 1975 Oroville earthquake, the 1983 Coalinga earthquake, and the 1987 Whittier Narrows earthquake occurred on faults not previously recognized as active. Potentially active faults are those that have shown displacement within the last 1.6 million years. An inactive fault shows no evidence of movement in historic (last 200 years) or geologic time, suggesting that these faults are dormant.

Fault creep and sudden fault displacement are two types of fault movement that are possible hazards to structures in the vicinity of the fault. Fault creep is a slow movement of one side of a fault relative to the other. It can cause cracking and buckling of the sidewalks and foundations even without perceptible ground shaking. Sudden fault displacement occurs during an earthquake event and may result in the collapse of buildings or other structures that are found along the fault zone when fault displacement exceeds an inch or two. The only protection against damage caused directly by fault displacement is to prohibit construction in the fault zone.

There are several known faults in Yolo County, the primary ones being the Hunting Creek Fault system, which includes the Wilson Fault, and the Dunnigan Hills Fault, as shown in Figure 3.30.

The Geographic extent of earthquake is rated as Limited with between 10-25% percent of the operational area affected. However, an earthquake with a magnitude as high as 6.8 on the Mercalli Scale could potentially occur in the southwestern area of the County around Winters as had occurred in 1892.
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Figure 3-30: Fault Lines in Northern Yolo County
Source: USGS
The Hunting Creek Fault, part of the Hunting Creek-Berryessa fault system, is located in the far northwestern portion of the County. This is the only known active fault in the County subject to surface rupture. The Hunting Creek-Berryessa is an active (Holocene) dextral strike-slip fault system associated with the larger San Andreas fault system. The Hunting Creek-Berryessa fault system extends from the vicinity of Wilson Valley south-southeast to the Cedar Roughs area west of Lake Berryessa. In this compilation, the fault zone is divided from north to south into the Wilson, Hunting Creek, and Lake Berryessa sections. The Wilson section most likely transfers dextral slip to the Bartlett Springs fault system. The Hunting Creek-Berryessa fault system is expressed as a zone of discontinuous fault traces as much as 3.5 km wide. The Hunting Creek-Berryessa fault system locally is delineated by geomorphic evidence of Holocene dextral strike-slip displacement, predominantly along the Hunting Creek fault, which comprises the Hunting Creek section. Late Pleistocene and probable Holocene displacement has occurred along traces of the Hunting Creek fault. The late Pleistocene dextral slip occurred at a rate of

0.09–0.4 mm/yr., based on apparent vertical separation of a late Pleistocene to Holocene colluvium. The geomorphic expression of the Hunting Creek fault indicated a dextral slip rate of at least 1 mm/yr. Only a small portion of the fault lies within Yolo County and is in an area that is sparsely populated and not planned for any growth or development other than individual farm dwellings that might be built in the future. Development near a fault subject to surface rupture is regulated by the Alquist-Priolo Act. The Act requires a detailed fault-rupture hazard investigation and prohibits development directly over any traces of the active fault line. 341
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The other potentially active fault is the Dunnigan Hills Fault, a segment of the Hunting Creek Fault, extending west of Interstate 5 between the town of Dunnigan and northwest of the town of Yolo. This fault has been active in the last 10,000 years but has not been active in historic times.

In addition to the Hunting Creek and Dunnigan Hills faults, major faults in the Coast Ranges and in the Sierra Nevada, foothills can produce ground shaking that could affect Yolo County residents. See Figure 3-31 for a map of faults surrounding Yolo County. Most of the active fault lines lie outside of the Sacramento Valley where the most of Yolo County is located.

Figure 3-31: Fault Lines around Yolo County
Source: USGS
There are also several other inactive faults located in Yolo County, specifically in the Capay Valley, which itself is formed over an offset synclinal fault and is an area of seismic activity.

Several inactive mapped faults, including the Sweitzer and Capay faults, pass through the Capay Valley.

The only earthquake to significantly affect Yolo County in recent history is the April 1892 Vacaville-Winters earthquake that measured 6.9 on the Richter Scale and caused severe damage to Winters and lesser damage to Davis, Woodland, and other parts of the County. It is believed to have originated from the Midland Fault (see Winters Community Profile), which is a segment 342
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of a complex zone of blind thrust faults referred to as the Coast Range-Sierran Block Boundary (CRSBB) that lie to the south of Yolo County in Solano County on the western side of the lower Sacramento Valley. Eleven moderate earthquakes have been documented along the CRSBB zone during the last 150 years, most recently the 1983 Coalinga Earthquake which registered 6.7 on the Richter Scale and VII (Severe) on the Mercalli Intensity Scale.

A 4.2 magnitude earthquake occurred near Madison in Yolo County in 1978 but did no damage.

Several minor earthquake swarms from unmapped faults occurred west of Woodland in Yolo County in 2016, but these earthquakes only caused minimal shaking and did not cause any damage.

PAST OCCURRENCES
There have been no disaster declarations in the County related to earthquakes, as shown in Table 3-5. The County had no USDA disaster declarations since 2012 related to earthquake, as shown in Table 3-8.

The United States Geologic Survey (USGS) National Earthquake information Center database contains data on earthquakes in the Yolo County area. Table 3-22 show the approximate distances earthquakes can be felt away from the epicenter.

Table 3-22: Approximate Relationships Between Earthquake Magnitude and Intensity Richter Scale Magnitude Maximum Expected Intensity* Distance Felt (miles)

2.0-2.9 I-II 0

3.0-3.9 II-III 10

4.0-4.9 IV-V 50

5.0-5.9 VI-VII 90

6.0-6.9 VII-VIII 135

7.0-7.9 IX-X 240

8.0-8.9 XI-XII 365
*Modified Mercalli Intensity Scale
Source: United States Geologic Survey, Earthquake Intensity Zonation and Quaternary Deposits, Miscellaneous Field Studies Map 9093,1977.

According to the USGS data, a magnitude 5.0 earthquake could be felt up to 90 miles away. The largest earthquake within 30 miles of Yolo County was a 4.4 magnitude quake in 1978.

Earthquakes that have occurred near areas of Yolo County are listed in the table below:

Table 3-23: Previous measured Earthquakes near/around Yolo County Date Richter Magnitude Depth Location
9/17/1973 4.2 2.0 mi 9 mi from Esparto
12/17/1976 3.3 2.0 mi 6 mi from Guinda
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9/8/1978 4.4 18.0 mi 2 mi from Monument Hills
5/26/1985 3.1 2.0 mi 7 mi from Guinda
12/26/1991 3.8 3.0 mi 7 mi from Esparto
7/18/2002 2.9 20.1 mi 5 mi from Knights Landing
10/19/2012 1.4 4.8 mi 4 mi from Guinda
6/27/2013 2.3 2.9 mi 5 mi from Winters
6/29/2013 1.2 4.8 mi 2 mi from Winters
7/3/2013 2.0 5.1 mi 4 mi from Madison
5/23/2014 2.0 23.6 mi 10 mi from Esparto
6/20/2014 1.6 5.0 mi 8 mi from Esparto
7/7/2014 2.4 2.8 mi 4 mi from Dunnigan
7/30/2014 2.0 5.2 mi 7 mi from Winters
8/24/2014 2.3 3.1 mi 10 mi from Esparto
8/29/2014 1.8 0.0 mi 11 mi from Esparto
4/30/2015 2.4 27.0mi 14 mi from Esparto
5/8/2015 2.0 4.7 mi 2 mi from Esparto
7/15/2015 2.4 1.7 mi 7 mi from Winters
10/2/2016 2.3 13.4 mi 9 mi from Winters
10/7/2016 1.9 4.1 mi 5 mi from Esparto
11/7/2016 2.0 10.4 mi 6 mi from Woodland
11/22/2016 2.3 1.5 mi 6 mi from Woodland
12/15/2016 2.5 10.7 mi 6 mi from Woodland
5/9/2017 2.8 10.9 mi 7 mi from Woodland
5/15/2017 2.5 0.0 mi 4 mi from Dunnigan
6/7/2017 2.5 5.2 mi 7 mi from Dunnigan
7/26/2017 2.0 4.1 mi 8 mi from Dunnigan
7/27/2017 2.8 13.1 mi 7 mi from Esparto
8/20/2017 2.3 7.8 mi 8 mi from Esparto
7/22/2018 1.9 20.6 mi 10 mi from Woodland
12/21/2018 1.5 7.0 mi 12 mi from Winters
7/26/2019 1.2 4.9 mi 11 mi from Winters
10/9/2020 2.9 10.6 mi 6 mi from Esparto
10/19/2020 2.9 10.6 mi 6 mi from Esparto
10/19/2020 2.6 9.5 mi 6 mi from Esparto
7/22/2021 2.8 15.8 mi 5 mi from Dunnigan
9/14/2021 1.5 4.8 mi 6 mi from Winters
12/15/2021 1.4 7.0 mi 13 mi from Esparto
4/3/2022 1.6 2.0 mi 5 mi from Winters
4/21/2022 1.8 -0.5 mi 1 mi from Winters
9/8/2022 0.9 14.3 mi 12 mi from Esparto
10/13/2022 2.2 5.6 mi 3 mi from Davis
11/21/2022 2.5 -0.5mi 8 mi from Winters
12/31/2022 1.4 4.6 mi 6 mi from Winters
Source: HomeFacts Yolo County Earthquake Data & Risk

LIKELIHOOD OF FUTURE OCCURRENCE
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Occasional - Based on the earthquake shaking potential for Yolo County, the proximity to the Bay Area, and the history of ground shaking in the area, the probability of damaging seismic ground shaking in Yolo County and its jurisdictions is Occasional: Between 1 percent and 10 percent chance of occurrence in the next year or has a recurrence interval of 11 to 100 years.

In 2014, the USGS and the California Geological Survey (CGS) released the time-dependent version of the Uniform California Earthquake Rupture Forecast (UCERF III) model. The UCERF III results have helped to reduce the uncertainty in estimated 30-year probabilities of strong ground motions in California. The UCERF map is shown in Figure 3-32 and Figure 3-33 and indicates that Yolo County has a low to moderate risk of earthquake occurrence, which coincides with the likelihood of future occurrence rating of occasional.

Figure 3-32: Uniform California Earthquake Rupture Forecast (Version 3) 345
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Source: USGS
Figure 3-33 Probability of Earthquake Probabilities Occurring in 30 Year Time Frame Source: USGS

CLIMATE CHANGE AND EARTHQUAKES
Scientists know that earthquakes can be triggered or inhibited by changes in the amount of stress on a fault. The largest climate variable that could change fault stress loads is surface water in the form of rain and snow. Although they have detected micro-seismicity, they haven’t yet determined if it is linked to larger quakes. However, they have determined that droughts can cause significant changes on earth’s crust and increase the stress load. For Yolo County specifically, periods of droughts cause increase groundwater pumping from underground aquifers which can impact patterns of stress loads. This can cause tectonic plates to shift and slip, 346
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resulting an earthquake. Another climatic change affect is due to human usage of water – which can induce seismicity. According to NASA, in 1975, eight years after the Oroville Dam was created, there was a series of earthquakes nearby, the largest registering a magnitude of 5.7.

Shortly after the water in the reservoir was drawn down to its lowest level since it was originally filled, to make some repairs, the earthquakes occurred. For Yolo County, with several surrounding dams, seismicity can decrease as the reservoirs fill in winter and spring, and as the reservoir levels fall in the summer and fall, there would be an increase in seismicity. With drought conditions, it could exacerbate lower levels in the reservoir, triggering increased seismic activities.

VULNERABILITY ASSESSMENT AND IMPACTS
Vulnerability – Medium
Yolo County could experience ground shaking as a result of an earthquake, including from the major regional fault lines located outside of the County. As shown in Figure 3-34, the area is subject to a range of ground shaking levels.

Figure 3-34: Regional Ground Shaking Hazard – Yolo County (2016) Source: California Geological Survey, California Department of Conservation The effects of ground shaking during a maximum intensity earthquake would likely involve structural damage to stucco, masonry walls and the chimneys of buildings, which could expose people to falling objects and possible building collapse. The degree of such hazards is controlled by the nature of the underlying soil and rock materials, the magnitude of and distance from the quake, the duration of ground motion and the structural characteristics of the building.

Earthquakes can also trigger landslides, debris flows, and natural gas leaks if a pipeline is impacted. Earthen dams and levees are also susceptible to seismic events, and the impacts of their failures can be considered secondary risks for earthquakes. 347
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According to the Yolo County General Plan, the maximum expected earthquake for the Hunting Creek Fault area would be 6.9 on the Richter Scale. As the Hunting Creek fault is in a remote corner of the County, it is expected that damages to property would be minimal. This is also an area that is sparsely population and not planned for any growth or development other than individual farm dwellings that might be built in the future. However, landslide triggered by an earthquake in the area could impact local stream flows and recreational areas. Development near a fault subject to surface rupture is regulated by the Alquist-Priolo Act. This Act requires a detailed fault-rupture hazard investigation and prohibits development directly over any traces of the active fault line.

The other active or potentially active fault line is the Dunnigan Hills Fault, which extends west of interstate 5 between the town of Dunnigan and northwest of the town of Yolo. This fault has been active in the last 10,000 years but has not been active in historic times. There would be minimal damage caused by this earthquake. Depending on the magnitude of the earthquake, there could be damage to interstate 5, radio towers, PG&E Substations along the route.

Mudslides and Landslides (Secondary Impacts)
Yolo County also faces exposure to mudslides that could be caused by earthquakes. This could occur primarily along Cache Creek, in the same areas where landslides are a risk. At the Yolo County/Colusa County boundary, State Route 16 passes through the open preserve area of the Cache Creek Regional Park. For about a mile, the highway is bordered by Cache Creek on the west and canyon walls on the east. The canyon walls are subject to rock and mud slides during heavy winter rains, or potential earthquakes. The rock and mudslides create traffic hazards by occasionally blocking the highway. A road closure gate is along that segment of the highway.

This gate prohibits traffic from entering this segment when major rock and mudslides occur.

Liquefaction (Secondary Impacts)
Liquefaction may also lead to lateral spreading during an earthquake. Areas most prone to lateral spreading are those that consist of fill material that has been improperly engineered, that have steep, unstable banks, and that have high groundwater tables. The banks along the Deep Water Ship Channel and Turning Basin in West Sacramento may have such a condition.

Numerous non-project levees throughout Yolo County are built on fill from the Sacramento River and are subject to liquefaction.

Access and Functional Needs Individuals
According to the FEMA National Risk Index, Yolo County’s Risk Index rating is relatively high when compared to the rest of the United States. Risk Index scores are calculated using an 348
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equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability, and Community Resilience. It is estimated that Yolo County will total an annual loss of around $44,054,185 due to earthquake damages, which is relatively high when compared to the rest of the U.S. About 84% of the population will be affected and per population equivalence, it will cost around $9,757,558. Communities in Yolo County, have a Relatively High ability to prepare for anticipated natural hazards, adapt to changing conditions, and withstand and recover rapidly from disruptions when compared to the rest of the U.S. Social groups in Yolo County, have a Relatively High susceptibility to the adverse impacts of natural hazards when compared to the rest of the U.S.

Whether directly impacted or indirectly impact, the entire population will have to deal with the consequences of earthquakes to some degree. Business interruption could keep people from working, road closures could isolate populations, and loss of functions of utilities could impact populations that suffered no direct damage from an event itself.

Residents in high-risk areas are more vulnerable to the impact of earthquakes. The degree of vulnerability is dependent on many factors, including the age and construction type of the structures people live in, the soil their homes are constructed on, and their proximity to the fault location, etc.

Two groups are particularly vulnerable to earthquake hazards: the population below the poverty level and those with access and functional needs. The first group consists of those below the poverty level who may lack the financial resources to improve their homes to prevent or mitigate earthquake damage. Economically disadvantaged residents are also less likely to have insurance to compensate for losses in earthquakes. Currently, about 16.1% of total residents are living below the poverty level. The second group consists of those with access and functional needs.

Earthquakes strike sometimes with little pre-notice unlike other natural hazards. Following an earthquake event, the evacuation of people with disabilities and access and functional needs poses additional requirements with respect to alert and notification, information dissemination, evacuation, emergency transportation, and sheltering requirements. Many people with disabilities are completely self-sufficient. However, damage caused to roads, buildings, and other infrastructure during an earthquake, could leave those with disabilities unable to evacuate without assistance. Other potentially at-risk individuals include those with cognitive or emotional disabilities that may impair their ability to make decisions during an emergency and should be transported with their caregivers or other mental health professionals when possible. Of consideration include senior apartments in Winters and elderly that may live independently near Dunnigan or the town of Yolo. According to Census data, in the City of Winters, there are about

8.5% of persons 65 years and older, 7.5% with a disability under 65 years, 6.5% persons in poverty, and 9.0% persons without health insurance. Although these percentages do not seem 349
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high, given the proximity of the City of Winters to a fault line, these vulnerabilities need to be considered in planning.

Yolo County HHSA maintains a database of registered persons with access and functional needs, as well as a list of facilities where persons with access and functional needs are housed. If needed, law enforcement will work closely with Yolo County HHSA and the local EOC on the evacuation of persons with access and functional needs following an earthquake event.

Critical Facilities
All critical facilities in the County are exposed to the earthquake hazard. Earthquakes pose numerous risks to critical facilities and infrastructure. Hazardous materials releases can occur during an earthquake from fixed facilities or transportation-related incidents. Facilities holding hazardous materials are of particular concern because of possible isolation of neighborhoods surrounding them. During an earthquake, structures storing these materials could rupture and leak into the surrounding area or an adjacent waterway, having a disastrous effect on the environment. Depending on the year of build and construction of each facility containing hazardous materials, the earthquake-initiated hazardous material release potential will vary.

Hazardous materials contained within masonry or concrete structures built before certain benchmark years may be particularly vulnerable.

Earthquake vulnerability is based primarily upon population and the built environment. To mitigate this hazard, building codes in California have been steadily improved over the past 80 years as understanding of seismic shaking has improved. Current California building codes include provisions for considering the potential shaking from earthquakes, including stronger shaking near faults and amplification by soft soils. The building code has been the main mitigation tool for seismic shaking in most buildings, although hospitals, schools, and other critical facilities are subject to additional mitigation measures. Yolo County adheres to the Universal Building Code and the California Building Standards Code. Areas of Yolo County most susceptible to earthquake include those near active fault zones and where ground shaking is primarily with a wave velocity of 350 m/sec or lower. These areas include the western side of the County, including the City of Winters and the Capay Valley.

The most significant impacts would be felt from the CRSBB zone, which is currently recognized as a potential seismic source capable of generating moderate to large earthquakes that could affect Yolo County. An earthquake of this size has the potential to significantly affect the area around Winters as had the 1892 Vacaville-Winters Earthquake. Total damages from the 1892 Vacaville-Winters Earthquake were $225,000-$250,000 and one person was killed. Damages today from a similar magnitude earthquake in the Winters area would be exponentially greater and could significantly impact the downtown area. In Winters, an earthquake could potentially 350
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cause natural gas leaks, water main breaks, and fires, would potentially destroy homes and businesses downtown, as well as cause damage to interstate 505, County Road 29, 93. There would be several schools in Winters that could sustain some damage due to an earthquake. Of concern would be damage to Winters Healthcare Clinic and senior apartments in Winters. The City of Winters also has a Water treatment facility that would sustain damage due to an Earthquake. Further details on City of Winters impact from earthquake could be found in the City of Winters Annex.

Transportation corridors can be disrupted during an earthquake, leading to the release of materials to the surrounding environment. Linear utilities and transportation routes are vulnerable to rupture and damage during and after a significant earthquake event. The cascading impact of a single failure can have affects across multiple systems and utility sectors. Degrading infrastructure systems and future large earthquakes with epicenters near critical regional infrastructure could result in system outages that last weeks for the most reliable systems, and multiple months for others. State Route 113, US Highway 50, and Interstates 5, 80 and 505 could be damaged by strong shaking or ground failure. Within 36 hours, some routes should be open.

More remote highways and roads may remain blocked for a considerable time, especially in canyon areas subject to landslide activity. Rail transport through the county likely will be nonoperational for at least three days. This interruption in service will impact both freight and passenger movement along the route.

Telecommunication systems can be affected by system failure, overloads, loss of electrical power and possible failure of some alternate power systems. Immediately following an event, numerous failures will occur, compounded by system use overload.

Large ground motions resulting from liquefaction, especially lateral spreading, can cause damage to buried pipelines. The Sacramento Municipality Utility District (SMUD) currently owns and operates 76 miles of natural gas transmissions pipeline, delivering fuel to four SMUD power plants in southern Sacramento County. This pipeline runs straight across from Winters in Yolo County to Rancho Seco in southern Sacramento County.

Due to smaller anticipated impacts of earthquake to the City of Davis, City of West Sacramento, and City of Woodland, the water treatment plants located in these cities are not anticipated to have significant damage due to earthquake.

ESTIMATING POTENTIAL LOSSES
A large earthquake could have a large impact on Yolo County; however the number of economic damages will likely vary due to a variety of factors such as magnitude and location of the 351
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epicenter. Other than direct economic losses due to an earthquake, indirect economic consequences can occur due to business interruption and loss of utility functions.

In 2016, the California Department of Conservation did an update of HAZUS annualized earthquake loss estimates for California, of which the results of Yolo County are in the table and figures below:

Table 3-24: Estimated Annualized Earthquake losses (AEL), percentage of statewide AEL, and annualized earthquake percent losses (APEL).

County AEL ($1,000) % of Statewide AEL APEL (%)
Yolo 9,223 0.25 0.045
Source: California Department of Conservation, Update of Hazus Annualized Earthquake Loss Estimates for California A 2023 Study done by USGS and FEMA demonstrates that the new estimate of loss is twice that of previous annual estimates due to increased building values and incorporates the latest hazards as well as improvements to building inventories. Compared to previous estimates done in 2001, 2008, 2017, the annualized earthquake loss ratios have decreased demonstrating mitigation measures to reduce building vulnerability has been successful. Figure 3-35 below shows the annualized loss in the United States, with Yolo County circled. Annualized loss was derived from combining earthquake hazards, building exposure, and vulnerability, thus representing a long-term average. The annualized earthquake loss ratio expresses the estimated annualized loss as a fraction of the building-inventory replacement value. According to this figure, Yolo County’s Annualized Earthquake loss ratio is $100-500 per million dollars. 352
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Figure 3-35: Average Annualized Earthquake Loss by Region Source: USGS, April 2023

FUTURE TRENDS IN DEVELOPMENT & POPULATION PATTERNS
New construction has modern seismic codes, engineering research, versus vulnerable older buildings which continue to bear the underlying risk seen in these loss estimates. Yolo County enforces seismic building codes and design standards to prevent loss of life and property from earthquakes. Continual public education, cooperation with the development community, and individual preparedness are essential to reduce the vulnerability of earthquakes.

Yolo County’s General plan contains policies directing land use and issues of geologic and seismic safety. There are policies such as regulating land development to avoid unreasonable exposure to geologic hazards, all development and construction proposals will be reviewed by the County to ensure conformance to applicable building standards, and requiring environmental documents prepared in conjunction with CEQA to address seismic safety issues and providing adequate mitigation measures. There are also implementation measures such as requiring 353
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geotechnical analysis for construction in areas with potential geological hazards, relying upon the most current and comprehensive geological hazard mapping in evaluating potential seismic hazards associated with proposed new development, and integrating geologic hazard information into the County Geographical Information System (GIS). These implementation measures protect the public and reduces damage to property from earthquakes and other geologic hazards which would decrease the vulnerability of the effects of earthquakes in Yolo County. This plan continues to provide capabilities to protect future development from the impacts of earthquakes utilizing deficiencies identified as mitigation actions to increase capabilities to deal with future trends in development, which would also decrease vulnerability to earthquake in Yolo County.

Any persons living in the earthquake prone areas will be affected by this hazard. New housing developments that may arise due to population increases, would be held to seismic safety standards. This implies that population patterns would not necessarily directly affect the vulnerability or the impacts of earthquakes.

3.8 FLOODING
Flooding is the rising and overflowing of a body of water onto normally dry land. History clearly highlights floods as one of the most frequent natural hazards impacting Yolo County.

Floods are among the costliest natural disasters in terms of human hardship and economic loss nationwide. Floods can cause substantial damage to structures, landscapes, and utilities as well as life safety issues. Floodwaters can transport large objects downstream, which can damage or remove stationary structures. Ground saturation can result in instability, collapse, or other damage. Objects can also be buried or destroyed through sediment deposition. Floodwaters can also break utilities lines and interrupt services. Standing water, because of extensive flooding, can cause damage to crops, road, foundations, and electrical circuits. Standing water can also cause septic tank failure and well contamination. Standing water and wet structures can become breeding grounds for microorganisms such as bacteria, mold, and viruses which can cause disease, trigger allergic reactions, and damage materials long after the flood. When floodwaters contain sewage or decaying animal carcasses, infections become a concern.

Certain health hazards are also common to flood events. While such problems are often not reported, three general types of health hazards accompany floods. The first comes from the water itself. Floodwaters carry anything that was on the ground that the upstream runoff picked up, including dirt, oil, animal waste, and lawn, farm and industrial chemicals. Pastures and areas where cattle and other livestock are kept, or their wastes are stored can contribute polluted waters to the receiving streams. Floodwaters also saturate the ground, which leads to infiltration into sanitary sewer lines. When wastewater treatment plants are flooded, there is nowhere for the sewage to flow. Infiltration and lack of treatment can lead to overloaded sewer lines that can 354
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back up into low-lying areas and homes. Even when it is diluted by flood waters, raw sewage can be a breeding ground for bacteria such as e. coli and other disease-causing agents.

Direct impacts, such as drowning, can be limited with adequate warning and public education about what to do during flood events. Where flooding occurs in populated areas, warning and evacuation will be of critical importance to reduce life and safety impacts from any type of flooding.

The area adjacent to channels of water and in the lowlands of the Sacramento River, Cache Creek, and the Yolo Bypass in Yolo County are known as floodplains. Floodplains are illustrated on inundation maps, which show areas of potential flooding and water depths. In its common usage, the floodplain most often refers to that area that is inundated by the 100-year flood, the flood that has a one percent chance in any given year of being equaled or exceeded.

The 100-year flood is the national minimum standard to which communities regulate their floodplains through the National Flood Insurance Program. The 200-year flood is one that has

0.5% chance of being equaled or exceeded each year. The 500-year flood is the flood that has a

0.2 percent chance of being equaled or exceeded in any given year. The potential for flooding can change and increase through various land use changes and changes to land surface, which 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.

Yolo County is susceptible to various types of flood events:
 Riverine flooding – defined as when a watercourse exceeds its “bank-full” capacity, generally occurs because of prolonged rainfall, or rainfall that is combined with snowmelt and/or 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 and is often characterized by high peak flows combined with a large volume of runoff. 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. In Yolo County, riverine flooding can occur anytime from November through April and is largely caused by heavy and continued rains, sometimes combined with snowmelt, increased outflows from upstream dams, and heavy flow from tributary streams. These intense storms can overwhelm the local waterways as well as the integrity of flood control structures. Flooding is more severe when antecedent rainfall 355
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has resulted in saturated ground conditions. The warning time associated with slow rise riverine floods assists in life and property protection.  Flash flooding – Flash flooding describes localized floods of great volume and short duration. This type of flood usually results from a heavy rainfall on a relatively small drainage area. Precipitation of this sort usually occurs in the winter and spring. Flash floods often require immediate evacuation within the hour and thus early threat identification and warning is critical for saving lives.  Localized/Stormwater flooding – Localized flooding problems are often caused by flash flooding, severe weather, or an unusual amount of rainfall. Flooding from these intense weather events usually occurs in areas experiencing an increase in runoff from impervious surfaces associated with development and urbanization as well as inadequate storm drainage systems.
 The area is also at risk to flooding resulting from levee failures and dam failures. Dam failure flooding is discussed separately in the Dam Failure Section of this document; levee failure flooding is discussed separately in the Levee Failure Section of this document.

Regardless of the type of flood, the cause is often the result of severe weather and excessive rainfall, either in the flood area or upstream reach.

Atmospheric River
A weather pattern called the “Atmospheric River” contributes to the flooding potential of the area. An Atmospheric River brings warm air and rain to West. A relatively common weather pattern brings southwest winds to the Pacific Northwest or California, along with warm, moist air. The moisture sometimes produces many days of heavy rain, which can cause extensive flooding. The warm air also can melt the snowpack in the mountains, which further aggravates the flooding potential. In the colder parts of the year, the warm air can be cooled enough to produce heavy, upslope snow as it rises into the higher elevations of the Sierra Nevada or Cascades. Forecasters and others on the West Coast often used to refer to this warm, moist air as the “Pineapple Express” because it comes from around Hawaii where pineapples are grown. A diagram of an atmospheric river event is shown in Figure 3-36. 356
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Figure 3-36: Diagram of an Atmospheric River Event
Source: NOAA

LOCATION AND EXTENT
California has 10 hydrologic regions. Yolo County sits in the Sacramento and San Joaquin hydrologic region. A map of the California’s hydrological regions is provided in Figure 3-37:
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Figure 3-37: California Hydrologic Regions
Source: 2018 State of California Hazard Mitigation Plan Yolo County encompasses multiple rivers, streams, creeks, and associated watersheds. Figure 3- 38 illustrates the major waterways of Yolo County.
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Figure 3-38: Waterways of Yolo County
Source: KSN Engineers
The following streams listed below are found in Yolo County:
• Cache Creek
• Putah Creek
• Dry Creek
• Buckeye Creek
• Oat Creek
• Bird Creek
• Willow Slough
• Cottonwood-Willow Slough
• Dry Slough
• Chickahominy Slough
• Lamb Valley Slough
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The geographic extent Flooding is rated as Extensive with between 50-100 percent of the operational area affected by any one storm. The county itself is drained by the Sacramento River and Yolo Bypass, an integral part of the Sacramento River Flood Control Project. Two major streams, Cache Creek and Putah Creek, cross the county from west to east but drain only a small part of the county. Cache Creek originates at the outlet of Clear Lake in Lake County to the west. With its main tributaries (North Fork Cache Creek, Bear Creek, and Clear Lake), it drains 1,140 square miles, and has a maximum elevation of 6,100 feet. Putah Creek originates in the west at an elevation of 3,000 feet and drains 634 square miles in Lake, Napa, and Yolo Counties.

Both Cache and Putah Creeks empty into Yolo Bypass on the eastern side of the county.

Willow, Cottonwood, Chickahominy, and Dry Sloughs, located in the southern part of the county between Cache Creek and Putah Creek, drain approximately 204 square miles at the western edge of the county and convey flows to the leveed Willow Slough Bypass that drains to Yolo Bypass; maximum elevations are near 2,500 feet. The Hungry Hollow watershed, located north of Cache Creek and between the Capay and Dunnigan Hills, drains 55 square miles and is a tributary of Cache Creek.

Dry Creek, which drains an area of 22.7 square miles, flows southeasterly near the western edge of the City of Winters and joins Putah Creek south of the city. Dry Creek originates on the steep slopes of Rocky Ridge, a part of the Coast Range.

The northern part of the county is drained by intermittent streams, such as Buckeye, Oat, and Bird Creeks that flow easterly from the Dunnigan Hills to the Colusa Basin Drainage Canal. The canal drains 1,700 square miles in Glenn, Colusa, and Yolo Counties and conveys flows to the Sacramento River at Knights Landing or to Yolo Bypass via Knights Landing Ridge Cut, depending on water-surface elevations in the Sacramento River. The area between the Sacramento River and Yolo Bypass in the southeastern part of the county is drained mostly by pumping. Flows in Yolo Bypass return to the Sacramento River near Rio Vista, 10 miles south of the southern limits of Yolo County.

Historically, Yolo County has always been vulnerable to flooding because of its relatively flat terrain and the number of water courses that traverse the County. Yolo County is vulnerable to a number of flooding sources caused by river floods, levee failures, drainage pump failures, and dam failures. Flooding caused by levee failure or overtopping remains a significant threat to valley locations. Flood zones in Yolo County are quite extensive. Floodwater is a common occurrence for communities adjacent to and in the lowlands of the Sacramento River, Cache Creek, and the Yolo Bypass in Yolo County.

Specific spots near tribal lands that have flooded is the past are as follows:
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• The unincorporated area of Rumsey along Hwy 16 in 1986 • Various spots of localized flooding across Hwy 16 and O Leary Ln in Rumsey to Capay at least 6” deep in 24 hr period
• Near the Capay Valley Fire District on Hwy 16 in Brooks. • The Town of Madison in 2017
See the following figures for community floodplains throughout the unincorporated County:

Figure 3-39: Brooks Floodplain
Source: KSN Engineers
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Figure 3-40: Capay Floodplain
Source: KSN Engineers
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Figure 3-41: Clarksburg Floodplain
Source: KSN Engineers
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Figure 3-42: Dunnigan Floodplain
Source: KSN Engineers
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Figure 3-43: Esparto Floodplain
Source: KSN Engineers
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Figure 3-44: Guinda Floodplain
Source: KSN Engineers
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Figure 3-45: Knights Landing Floodplain
Source: KSN Engineers
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Figure 3-46: Madison Floodplain
Source: KSN Engineers
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Figure 3-47: Rumsey Floodplain
Source: KSN Engineers
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Figure 3-48: Zamora Floodplain
Source: KSN Engineers
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Figure 3-49: Yolo Floodplain
Source: KSN Engineers
Localized flooding issues can occur throughout the County from rainfall events presenting minor but still significant issues to local districts. With excess rainfall, farmers modify their fields to facilitate proper drainage off their crops. Rainfall can also pose a risk to County roads and 371
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culverts because it impacts flow and “natural” drainage patterns. See Figure 3-50 for a map of road flooding frequency in Yolo County.

Figure 3-50: Road Flooding Frequency in Yolo County
Source: Yolo County Flood Control & Water Conservation District Cache Creek
Originating at the outlet of Clear Lake in Lake County, Cache Creek drains approximately 1,100 square miles and has an elevation drop of 6,100 feet from its headwaters to its discharge into the Yolo Bypass. The Sacramento Maintenance Yard (SMY) area of responsibility begins at 6,000 feet upstream of the California Northern Railroad on the north bank of Cache Creek and approximately 3,000 feet upstream of the same railroad on the southern bank of Cache Creek.

SMY’s responsibilities continue downstream until Cache Creek discharges into the Yolo Bypass.

SMY is also responsible for the East Training Levee which is located along the western edge of the Cache Creek Settling Basin. Areas of the Capay Valley, particularly sections of Yocha Dehe 372
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Wintun Nation housing, are susceptible to flooding from Cache Creek where there are no levees in place.

The channel design capacity of Cache Creek is 33,000 cubic feet per second (cfs) which according to the FEMA Flood Insurance Study for Yolo County equates to approximately a 10- year flood event.

West Sacramento City CouncilApril 9, 2025

West Sacramento City Council
April 9, 2025