Calistoga City Council
October 6, 2026

HAZARD MITIGATION PLAN 2026 UPDATE

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Table 2-2: Napa County Breakout Meetings
Meeting & Date Agenda / Topics Goals / Key Inputs
County-Wide Steering Group and HMPT Meetings #1 & #2
February – July 2024
County Planning Team
Breakout Meeting #1
November 11, 2024
▪ County-wide HMPT meetings #1 and #2 recaps
▪ Community engagement progress and results
▪ Risk assessment and community vulnerability
▪ Demographics and vulnerable populations
▪ Overview of jurisdiction-specific hazard risks and
exposure
▪ Introduction to Risk Assessment Mapping Platform
(RAMP)
▪ Jurisdiction-specific hazard risk ranking exercise
▪ Project schedule updates and next steps
▪ Consensus on jurisdictionspecific priority hazards
▪ Identify capabilities and
potential mitigation actions
▪ Community engagement
volunteers
County-Wide HMPT Meeting #3
March 2025
County Planning Team
Breakout Meeting #1.5
February 20, 2025
▪ Validate priority hazards
▪ Review areas of concern in RAMP
▪ Project schedule updates and next steps
▪ Consensus on jurisdictionspecific priority hazards and areas of concern
County Planning Team
Breakout Meeting #2
June 11, 2025
▪ Breakout Meeting #1 and HMPT #3 recaps
▪ Review capabilities assessment
▪ Review areas of concern and define problem
statements
▪ Principles of effective mitigation strategies and
actions, and mitigation alternatives
▪ Refine and align jurisdiction-specific mitigation
actions exercise
▪ Project schedule updates and next steps
▪ Consensus on jurisdictionspecific capabilities
▪ Consensus on jurisdictionspecific areas of concern
▪ Consensus on priority
mitigation actions and
collaboration opportunities
▪ Community engagement
volunteers
County-Wide HMPT Meeting #4
December 2025
Key Stakeholders
Key Stakeholders serve as liaisons to the greater community outside of the Steering Group and planning teams. These are people representing local, regional, state, and federal agencies involved in hazard mitigation or with the authority to regulate development, such as neighboring jurisdictions. Also included were representatives of local businesses, academia, community-based organizations and non-profits, and members of the public. Outreach with Key Stakeholders consisted of email correspondence, informal interviews, and community events, which covered topics such as basic project information, primary hazard concerns and front-line experience, needs and challenges of vulnerable populations, coordinating CAL OES SUBMITTAL - JUNE 2026
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engagement events, and advertising for the project. Organizations and individuals involved in the planning process as Key Stakeholders are listed in Table 2-4.

Many of the Key Stakeholders engaged represent agencies and organizations that support underserved communities and vulnerable populations, providing channels to those who are often most impacted by hazard events and with the least resources for disaster preparedness, response, or recovery. In particular, Key Stakeholders offered opportunities to engage with community members through known and trusted networks and voices, ensuring that people in all corners of the county and from all backgrounds were provided with opportunities to influence the 2026 MJHMP and mitigation strategy. Key Stakeholders were engaged by Napa County and the Consultant Team on behalf of each participating jurisdiction at various points during the planning process. These efforts and the findings thereof are summarized in Section 2.1.2 and documented in Appendix B.

Consultant Team
Napa County enlisted Dynamic Planning + Science (DP+S) as the Consultant Team to assist in the development of the 2026 MJHMP. DP+S was chosen based on its extensive experience and expertise in helping public sector entities with developing hazard mitigation plans. DP+S staff facilitated the planning process from start to finish, collected and analyzed local data, produced meeting and public engagement materials, and developed drafts of the MJHMP for review. The Consultant Team members are listed in Table 2-5 and consisted of a variety of hazard mitigation, data analysis, and certified planning professionals.

Table 2-3: Members of Steering Group and All Planning Teams Name Title CRS Expertise Department
Napa County
Brieanna Jones Emergency Services Officer Emergency Management/ Public Safety
Office of Emergency
Services
Andrew Eaman Senior Information Systems
Specialist Public Information Napa County GIS
Anthony Halstead Director of Library Services &
Community Outreach Public Information Library
Brian Bordona
Director of Planning,
Building & Environmental
Services
Planning/Zoning/Building/
Code Enforcement
Planning - Building &
Environmental Services
Brian Ham Emergency Management/
Public Safety County Fire/CalFire
Casey LoCurto GIS Public Information Napa County GIS/IT Cullen Dodd Undersheriff Emergency Management/
Public Safety Sheriff
Dave Cardwell Assistant Superintendent
Roads Division Engineering/Public Works Planning - Roads Division CAL OES SUBMITTAL - JUNE 2026
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Name Title CRS Expertise Department
David Gludice Chief Building Official
Building/Code
Enforcement/CRS
Coordination
Planning - Building &
Environmental Services
David Kamlan EMS Specialist Emergency Management/
Public Safety
Emergency Medical
Services
David Shew Fire Administrator Emergency Management/
Public Safety
Doug Calhoun Environmental Health
Coordinator
Environmental Protection/
Public Health
Division of Environmental
Health
Frank Lucido Engineering Manager Engineering/Public Works Planning - Engineering J.R. Rogers Fire Administrator Emergency Management/
Public Safety Fire
James Bales Cal Fire/Napa County Fire
Marshall
Emergency Management/
Public Safety Cal Fire / County Fire
Jason Martin Cal Fire/Napa County Deputy
Fire Chief
Emergency Management/
Public Safety Cal Fire / County Fire
Jason Novak Battalion Chief Emergency Management/
Public Safety Cal Fire
Jay Gardner Chairman Elected Official Napa River Reclamation District #2109
JC Greenberg Deputy Fire Chief Emergency Management/
Public Safety Fire
Jeff Skinner Stormwater Program
Manager
Engineering/Public Works/
Drainage Stormwater Program
Jennifer Palmer Director of Housing and
Homeless Services Public Health Housing and Community Services Jennifer Yasumoto Health and Human Services
Agency Director
Environmental Protection/
Public Health
Health and Human
Services
John Tuteur Assessor Elected Official Assessor
Jon Gjestvang Chief Information Officer Public Information IT Juan Arias Deputy Director, County
Engineering Engineering/Public Works Planning - Engineering Katherine Bales Assistant Airport Manager Public Works Public Works - Airport Mark Witsoe Airport Manager Public Works Public Works - Airport Matt Lamborn GIS Coordinator Public Information Planning - Building & Environmental Services
Matt Ryan Emergency Management/
Public Safety Fire
Michael Parker Planning Manager CRS Coordination/
Planning/Zoning
Planning - Building &
Environmental Services
Oscar Ortiz Sheriff Emergency Management/
Public Safety Sheriff
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Name Title CRS Expertise Department
Ryan Alsop County Executive Officer Emergency Management/ Public Safety Cal Fire / County Fire
Shaun Vincent EMS Administrator Emergency Management/
Public Safety
Emergency Medical
Services
Stacey Harrington Environmental Health
Manager
Environmental Protection/
Public Health
Planning - Building &
Environmental Services
Steve Lederer Public Works Director CRS Coordination/Public Works Public Works
Steve Stangland Public Works Superintendent Public Works Public Works Toosdi Malito Assistant Agriculture
Commissioner
Environmental Protection/
Public Health/Elected
Official
Agriculture Commission
City of American Canyon
Alexandra Ikeda Deputy City Manager Planning/Public Works/ Public Safety City Manager
Dominic Patrick Water Systems Manager Engineering/Public Works Maintenance & Utilities Brent Cooper Community Development
Director
Planning/Zoning/Building/
Code Enforcement Planning
Erica Ahmann Smithies Public Works Director Engineering/Public Works Public Works Ijeoma Njoku Environmental Services
Specialist
Environmental Protection/
Public Works Maintenance & Utilities
Jason Holley City Manager Planning/Public Works/
Public Safety City Manager
Joshua Anderson Contract Building Official Building/Code Enforcement Planning
Rick Greenberg Police Chief Emergency Management/
Public Safety Police
Will Harder Maintenance Worker II Engineering/Public Works Public Works City of Calistoga
Jed Matcham Fire Chief Emergency Management/
Public Safety Fire
Mitchell Celaya Interim City Manager Planning/Public Works/ Public Safety City Manager
David Fradelizio Associate Engineer Engineering/Public Works Public Works Derek Rayner Public Works Director Engineering/Public Works Public Works Greg Desmond Planning and Building
Director
Planning/Zoning/Building/
Code Enforcement Planning
Hamid Heidary Senior Civil Engineer Engineering/Public Works Public Works Jason Tamagni Fire Captain Emergency Management/
Public Safety Fire
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Name Title CRS Expertise Department
Laura Snideman City Manager Planning/Public Works/
Public Safety City Manager
Mark Woods Building Official Building/Code
Enforcement
Planning & Building
Department
City of Napa
Zach Curren Fire Chief Emergency Management/
Public Safety Fire
Brandon Veyna Fire Prevention/Inspector Emergency Management/ Public Safety Fire
Charles Rhodes Battalion Chief Emergency Management/
Public Safety Fire
Doug DeMaster Senior Civil Engineer Engineering/Public Works Water Ed Moore Engineering Assistant Engineering/Public Works Public Works -
Transportation
Engineering
Jaina French Community Relations &
Media Manager Public Information City Manager
Jason Berens Deputy Chief Emergency Management/
Public Safety Fire
Jason Williams Chief Building Official Building/Code
Enforcement Buildings
Jeff Gittings Parks and Urban Forestry
Manager Parks and Recreation Parks & Recreation
Joy Eldredge Deputy Utilities Director Engineering/Public Works Utilities Julie Lucido Public Works Director Engineering/Public Works/ CRS Coordination Public Works
Kristopher Jenny Lieutenant - Administration Emergency Management/ Public Safety Police
Magdiel Frayre Parks, Trees & Facilities
Supervisor Parks and Recreation Parks & Recreation
Matthew Price Public Works Maintenance
Superintendent Engineering/Public Works Public Works
Michael Walker Senior Planner Planning/Zoning Community Development.

Molly Rattigan
Deputy City Manager/Interim
Community Development
Director
Planning/Zoning/Building/
Code Enforcement Community Development
Paul O'Neill Assistant Planner Planning/Zoning Planning Phil Brun Utilities Director Engineering/Public Works Utilities Stephanie Emmons Stormwater Program
Coordinator
Engineering/Public Works/
Drainage
Public Works -
Development Engineering
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Name Title CRS Expertise Department
Vincent Smith Director Community
Development
Planning/Zoning/Building/
Code Enforcement/CRS
Coordination
Community Development
City of St. Helena
Anil Comelo City Manager Planning/Public Works/
Public Safety City Manager
John Sorenson Fire Chief Emergency Management/
Public Safety Fire
Aaron Hecock Senior Planner Planning/Zoning Community Development - Planning
Andrew Bradley Program Manager Planning/Public Works/
Public Safety Consultant
Chris Hartley Police Chief Emergency Management/
Public Safety Police
Dave Jahns Parks & Recreation Director Parks and Recreation Community Services - Parks & Recreation
Jackie Oneal Senior Planner Planning/Zoning Community Development - Planning
Joseph Leach Public Works Director, City
Engineer Engineering/Public Works Public Works
Justin Tharp Lieutenant Emergency Management/
Public Safety Police
Lesley Milton Deputy City Manager Planning/Public Works/ Public Safety City Manager
Mandy Kellogg Administrative Services
Director Public Information Administrative Services
Maya DeRosa Planning and Building
Director
Planning/Zoning/Building/
Code Enforcement
Community Development -
Planning
Philip Henry Chief Building Official Building/Code
Enforcement
Community Development -
Building
Town of Yountville
Hilary Gaede Communications Director/
Town Clerk Public Information Town Clerk & Communications John Ferons Public Works Director Engineering/Public Works/ Drainage Public Works
Beatriz Becerra Management Fellow Planning/Public Works/ Public Safety Town Manager
Brad Raulston Town Manager Planning/Public Works/
Public Safety Town Manager
Diane Levine Associate Planner Planning/Zoning Planning & Building Irene Borba Planning and Building
Director
Planning/Zoning/Building/
Code Enforcement Planning & Building
Jacob Solis Engineering Tech - GIS Public Information/Public Works Planning & Building
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Name Title CRS Expertise Department
Mike Milat Sergeant - Sheriff's Office Emergency Management/ Public Safety Sherrif
Nick Hickman Water System Maintenance
Worker II Engineering/Public Works Public Works
Rosalba Ramirez Deputy Public Works Director Engineering/Public Works Public Works Samantha Holland Parks & Recreation Director Parks and Recreation Parks & Recreation American Canyon Fire Protection District
Geoff Belyea Fire Chief Emergency Management/
Public Safety
Cliff Campbell Assistant Fire Chief Emergency Management/ Public Safety
Howell Mountain Mutual Water Company
Shannon Damonte Administrative Manager Public Information Tanner Hiers General Manager Planning/Public Works/
Public Safety
Napa County Flood Control and Water Conservation District Andrew Butler District Engineer Engineering/Public Works/ Drainage
Jeremy Sarrow Watershed & Flood Control
Operations Manager
Engineering/Public Works/
Drainage
Leif Bryant Logistics Chief Engineering/Public Works/
Drainage
Ross Murphy Engineering/Public Works/
Drainage
Phillip Miller Deputy Director Engineering/Public Works/ Drainage
Richard Thomasser Deputy Director of Public
Works / District Manager
Engineering/Public Works/
Drainage
Napa County Office of Education
Joshua Schultz Deputy Superintendent
Allen Rossi General Services Director Planning/Public Works/ Public Safety
Angel Hernandez OES Officer Emergency Management/
Public Safety
Janet Tufts Superintendent/Principal
Howell Mountain School
Planning/Public
Information
Jeremy Smith Director of General Services Engineering/Public Works Julie McClure Deputy Superintendent Planning/Public
Information
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Name Title CRS Expertise Department
Rosanna Mucetti
Superintendent of Napa
Valley Unified School
District
Planning/Public
Information
Seana Wagner Communications & Special
Projects, Director Public Information
Napa Sanitation District
Matthew Lemmon Engineering Director /
District Engineer
Engineering/Public Works/
Drainage
Amy Walcker Human Resources Manager Public Information
Andrew Damron General Manager Planning/Public Works
Nick Hunter
Safety, Training and Fleet
Maintenance Officer
(STFMO)
Emergency Management/
Public Safety
Napa Valley College
Amber Wade Chief of Police Emergency Management/
Public Safety
Miguel Vargas Director of Facilities Planning/Public
Information
Matt Christensen Facilities Director Planning/Public
Information
Samantha Maddox Facilities Planning Manager Planning/Public Works Napa Valley Transportation Authority
Libby Payan Senior Program Planner –
Administrator
Planning/Public Works/
Public Information
Danielle Schmitz Deputy Executive Director Planning/Public Information
Dexter Cypress Transit Planner Planning/Public Works
Rebecca Schenck Transit Manager Planning/Public Works
Note: Jurisdiction leads in the Steering Group are presented in light purple rows with bold names.

Table 2-4: Key Stakeholders
Name Title Agency
Michael Cahill Emergency Planning Consultant MPCahill Solutions LLC CAL OES SUBMITTAL - JUNE 2026
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Table 2-5: Consultant Team Members
Name Title Project Role
Ethan Mobley, AICP Owner / Principal Planner Project Manager Brian Greer Co-Owner / Data Visualization Manager GIS Lead / Data Analyst Raini Ott, AICP, CFM Principal Planner Assistant Project Manager / Outreach Lead / Hazard Mitigation Planner
Cory Schreiner Fire Prevention Service Manager Assistant Project Manager / Hazard Mitigation Planner
Alex Krebs Data Visualization Associate GIS Assistant / Data Analyst Cassidy Baumann Planning Associate Hazard Mitigation Planner / Data Analyst Christopher Velasco Senior Planner (former) Outreach Assistant / Hazard Mitigation Planner
`

2.1.2 Public & Stakeholder Engagement
Stakeholder engagement is a critical component in producing any effective and meaningful public planning process and actionable planning document, and public outreach is also a required component of the MJHMP. (44 CFR § 201.6(c)) As such, it is vital that early and continued engagement is facilitated through a diverse range of mediums to ensure community members, neighboring jurisdictions, and other stakeholders have an adequate opportunity to provide input, especially on the mitigation strategy.

The public and stakeholder engagement efforts deployed for this plan exceed the minimum state and federal requirements for outreach. But more than that, the engagement strategy was developed, implemented, and refined over the course of the MJHMP update planning process to ensure an abundance of enhanced opportunities for all types of community members to provide input.

By engaging with stakeholders and members of the public at specific points during the process, perspectives from an array of stakeholder categories were integrated throughout the MJHMP rather than being mentioned as an afterthought or an appendix. This extensive public and stakeholder engagement process and the results thereof are further described in this section and fully documented in Appendix B.

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On behalf of all the participating jurisdictions, Napa
County conducted outreach and engagement
following a six-step strategy and work plan with
support from the Consultant Team and county-wide
HMPT. The outreach strategy for this 2026 MJHMP
maximized stakeholder input and public
involvement throughout the planning process,
utilizing a diverse range of channels, mediums, and
formats to ensure residents, business owners, and
other community members were solicited for input
on the plan from start to finish. Other community
stakeholders, such as non-profits serving
vulnerable populations, were also engaged using a
variety of methods.

Implementation of the six-step strategy and work
plan was conducted by the Steering Group and
consisted of first identifying goals and the
timeframe for engagement followed by identifying
the planning team members, key stakeholders,
tools, and resources to support the effort. Then a
work plan was developed to organize the timeframe,
teams, key stakeholders, and engagement tools and
resources into a usable framework to guide the process toward accomplishing its stated goals. As the process progressed, it was continually assessed for its effectiveness and adjusted accordingly. This adaptive management approach ensured the engagement process supported the three goals identified in step one.

In executing this engagement strategy and work plan, Napa County accomplished the following three goals:

1. Understand public safety and hazard concerns, problem areas, assets, and policy and mitigation priorities on a neighborhood scale, with intentional outreach to socially vulnerable and underserved populations, including Spanish-speaking residents and people with access and functional needs.

2. Provide accessible, inclusive information and tools — offered in multiple languages and formats — to community members, residents, and businesses to increase safety and decrease hazard risk at the private property level, ensuring engagement with socially vulnerable populations.

3. Collaborate with adjacent communities, special districts, utility providers, and other local and regional regulatory agencies providing public safety services, while prioritizing coordination that supports underserved and socially vulnerable populations.

The overall timeframe for public and stakeholder engagement stretched across the development of the MJHMP, occurring at regular intervals and important junctures. This schedule is illustrated below in Figure 2-2. Engagement efforts outside of the planning team meetings and breakout sessions discussed in Section CAL OES SUBMITTAL - JUNE 2026
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2.1.1, along with the various tools and resources used and the feedback gained from community members, are summarized in the following sections. Appendix B documents the outreach process, as required by FEMA, Cal OES, and the California Office of LCI.

Outreach Tools & Resources
More than just informing the public of the plan’s development, a good community engagement effort educates the public and motivates them to act. It must also be recognized that equal opportunity to participate does not result in equal participation. In every community, there are those who might otherwise engage but go unheard for various reasons, such as lack of internet access, time constraints, and/or childcare needs which may inhibit in-person engagement. It was Napa County’s goal to identify and overcome these barriers and achieve equitable participation and meaningfully engage with the local community on their terms. The following tools and resources aided in achieving this.

Key Stakeholders
Because public safety and hazard issues are not tied to jurisdictional boundaries, Napa County consulted with a variety of stakeholders throughout the development of this MJHMP, as described in Step 1 of the planning process in Section 2. This included gathering jurisdictional staff and other stakeholders with specific local expertise to contribute to the planning process and forming the county-wide Hazard Mitigation Planning Team (HMPT) as well as internal planning teams for each jurisdiction. In addition, Napa County consulted with a range of Key Stakeholders that represented a broader range of local and regional agencies, including those that work closely with underserved and vulnerable populations.

Key Stakeholders consisted of people from a variety of public and private organizations within Napa County and the surrounding region that possess knowledge about local public safety and hazard conditions, issues, and priorities. These included representatives of local businesses, community-based and non-profit organizations, academia, and neighborhood groups (see Table 2-4). While some Key Stakeholders were involved in the HMPT or jurisdictional planning teams, others were engaged through different means, such Figure 2-2: Overview of Public and Stakeholder Engagement Timeline CAL OES SUBMITTAL - JUNE 2026
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as emails and project announcements, informal interviews and phone calls, and collaboration on community engagement events.

Most importantly, Key Stakeholders that work with vulnerable populations and underserved communities provided critical channels and opportunities to meaningfully engage with those groups. Many of the Key Stakeholders consulted are trusted community figures and leaders, with voices that carry across language, cultural, and socioeconomic barriers to reach those who face some of the greatest risks and challenges in preparing for, responding to, and recovering from hazard events. By engaging with these community voices, Napa County and other jurisdictions were able to develop more comprehensive mitigation strategies that were not only tailored to local hazard conditions and capacities, but that also addressed some of the most pressing needs of their most vulnerable community members. In this way, Key Stakeholders were central in developing the MJHMP goals and mitigation strategies that will make Napa County safer and more resilient.

Websites, Social & Other Media
Napa County and the other participating jurisdictions used their websites, social media platforms, and other media to widely advertise the update of the MJHMP and solicit input from a diverse array of community members. In addition, a project portal was created through the Mitigate Hazards website maintained by the Consultant Team (mitigatehazards.com/napacountymjhmp), which served and will continue to serve as a centralized project information and file-sharing
platform throughout the lifecycle of the plan. This
website provides a tool for project management,
collaborative content, and one-stop-shop for
mitigation planning resources.

Project participants from each jurisdiction and key stakeholders used the website as a project resource for the duration of the planning process and will continue to have access during the five-year cycle and beyond.

The page hosts secure information, including a point of contact database and a mapping application built specifically for mitigation planning called the Risk Assessment Mapping Platform (RAMP). RAMP allows for interactive discovery of the robust risk assessment data that was developed for the MJHMP. It displays facilities and buildings overlaid with natural hazards layers to bring interactivity and individual discovery to the GIS analysis performed for the plan. The website also hosts the Mitigation Action Support Tool (MAST) to help each jurisdiction track and update their mitigation strategy (see 2.3.4.3).

In addition to internal coordination, the project website played a critical role in community engagement throughout the planning process and documenting public involvement, including for the public survey, engagement events, planning team meetings and breakout sessions, and public review of the draft plan.

Resources such as home-based mitigation measures, background documents, the Risk Assessment Mapping Platform (RAMP), links to meeting summaries, and the final plan are available to the public via the website.

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Jurisdiction-maintained websites and social media are valuable and authoritative resources for the public that were used in addition to the project website to advertise the planning process and ways for community members to get involved. In general, users were directed from the jurisdiction websites and social media posts to the primary project website to avoid inactive or outdated information. Information on the MJHMP update was distributed through multiple social media platforms, such as Instagram and Facebook, using visually-oriented posts tailored to that jurisdiction’s audience, often including posts in Spanish.

Alongside general project advertising, these websites, social media platforms, and local media outlets were used to publicize project milestones, the public survey, and community engagement events, as documented in Appendix B. The websites and media listed in Table 2-6 were used in the engagement effort.

Table 2-6: Summary of Community Outreach Media Tools
Jurisdiction / Agency Media Tools Used Example Links
Key Stakeholders and Other Partner Agencies
KVON / The Vine Radio advertisement regarding
survey
Radio Website
Participating Jurisdictions
Napa County Newsletter, Facebook November 2025 Newsletter November 2025 Facebook
City of Napa Newsletter December 2025 Newsletter
City of American Canyon
City of Calistoga Newsletter November 2025 Newsletter
City of St. Helena Newsletter, Instagram, Facebook November 2025 Newsletter May 2026 Facebook
Town of Yountville Newsletter, Instagram November 2025 Newsletter November 2025 Instagram
Napa County Flood Control and Water
Conservation District See Napa County
Napa County Office of Education See Napa County
Napa Valley College See Napa County
Howell Mountain Mutual Water Company See Napa County
Napa Valley Transportation Authority See Napa County
Napa Sanitation District Facebook December 2025 Facebook American Canyon Fire Protection District See Napa County CAL OES SUBMITTAL - JUNE 2026
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Public Outreach Events
During the planning process, community
outreach events were hosted across the
county. These in-person public
engagement events were generally
scheduled in conjunction with existing
community events to “piggyback” off their
large attendance. Such events provided
opportunities to go beyond other outreach
efforts and engage members of the
community who might not have otherwise
participated in the planning process.

Primarily, these events consisted of
hosting tables at local famers’ markets and
making presentations at public meetings.

The main outreach event for this 2026
MJHMP was held at the City of Napa
Farmers’ Market on April 29, 2025 (Figure
2-3).

Online Public Survey
A primary tool used in informing the development of this MJHMP was an online survey, which provided an easy and powerful way of gathering qualitative and quantitative data to inform plan preparation. The survey was open to the public between April 2024 and February 2026, ending just prior to the release of the public draft for review, ensuring as many responses as possible were collected. The survey was distributed in both English and Spanish and was widely advertised across the county through the websites and other platforms of participating jurisdictions, Key Stakeholders, and other partner agencies. To incentivize greater public participation, Napa County offered all survey participants the chance to win a gift card towards a home mitigation item.

A total of 75 responses were received, which are summarized in Section 4.3 (Figure 4-2) and documented in Appendix B. As intended through a series of 16 questions, the results from the survey were used to gauge community members’ knowledge of local hazards, perceptions of different hazards, greatest safety concerns, and mitigation priorities. These results were used to ensure that the priorities of Napa County and the other participating jurisdictions match those of their respective community members.

Figure 2-3: April 2025 Napa Farmers' Market Outreach Event CAL OES SUBMITTAL - JUNE 2026
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Interactive Meeting Materials
Napa County and the other participating jurisdictions, with assistance from the Consultant Team, conducted a series of county-wide and jurisdiction-specific planning team meetings (see Section 2, Step 1) and many community outreach events, as described elsewhere in this section. All of these meetings and most of the events were arranged in ways that were conducive to interactive engagement, providing enhanced opportunities for participants to learn and express their perceptions and priorities through a variety of tools.

The stakeholder and community feedback collected through interactive methods is documented in Appendix B. Examples of the tools and meeting materials that were used to create these engagement opportunities include:
▪ Take-Home Cards: Cards with important project information, such as the project website url and a QR code to the online survey or public draft review page.
▪ Feedback Boards: Prompts on large boards with mapping information or visualized data were provided to help collect public feedback. Community members were able to respond to the information on the board by attaching stickers or post-it notes, or by writing, drawing, or highlighting directly on it.
▪ Hard Copy Surveys: Hard copies of the survey were provided at events in both English and Spanish, to provide increased accessibility, especially for those who lack computer access or literacy. ▪ Earthquake Kit Demonstration: Using a custom display board, several in-home earthquake safety measures were made available for members of the public to interact with. The display board featured different ways to secure furniture and heavy objects like TVs, as well as museum putty to help keep fragile valuables such as glassware in place.

Public Review Period
After a complete draft of the MJHMP was developed based on the updated risk and capabilities assessments and on feedback from stakeholders and the public, community members across all participating jurisdictions were provided an opportunity to review and comment on the proposed hazard mitigation plan and strategy. This public review period was open for more than two weeks, between May 15 and June 2, 2026, and widely advertised through Napa County and other jurisdiction’s websites, social media, and other media platforms.

Reviewers were directed to the project website where the draft MJHMP was provided in a collaborative PDF format to allow quick and easy live commenting. In addition, an online commenting form and direct emailing to the Steering Group via the Consultant Team were offered as options to give input on the draft.

All comments received were reviewed and incorporated into the plan as appropriate.

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Reaching Underserved Communities & Vulnerable Populations As discussed in Section 1.5.3 of the Community Profile, there are populations in Napa County that are disproportionately impacted by hazard events than others, including Spanish-speakers, agricultural workers, seniors, and people with access and functional needs. Recognizing that traditional engagement methods, such as public hearings or submitting comments in emails or letters, are often inaccessible or intimidating ways to participate in the planning process, the engagement strategy for this MJHMP sought input directly from these communities and populations and from trusted voices within them through different means.

Partnering with Key Stakeholders to reach underserved and vulnerable populations through existing community lifelines and organizations was critical to understanding the concerns, needs, challenges, and priorities of these groups across Napa County. This was aided by the deployment of intentional outreach efforts using accessible and inclusive tools to engage residents in a variety of ways and on their own terms, including:
▪ Translation of Materials: Napa County
translated all engagement materials into
both English and Spanish, including
content on the project website, the public
survey, and social media posts in order to
effectively exchange information with
Spanish-speaking residents (Figure 2-4).
▪ Utilization of Community Gathering
Spaces: Creating safe and welcoming
environments for community members to
participate in the planning process was a
key component of successfully engaging
with some of the vulnerable populations
in Napa County. This was especially
important to reach community members
who were potentially fearful or distrusting
of governmental organizations.
▪ Virtual Participation: Virtual participation
through the online survey and the project
website (e.g., to review the draft plan) were
also offered to provide flexibility for Key Stakeholders and community members who were not able to attend in-person meetings or events due to inconvenience or other constraints.

Figure 2-4: Online Public Survey Advertisement in
Spanish
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Incorporating Public & Stakeholder Feedback
The stakeholder and public feedback gained through the various engagement efforts described in this section and Section 2, Step 1, shaped the development of the MJHMP from start to finish. The Steering Group, county-wide Hazard Mitigation Planning Team, and jurisdiction-specific planning teams laid the foundation for and provided critical input on the plan, including the history of hazard events, existing community conditions and hazard concerns, the successes of previous mitigation efforts, current capabilities and improvement opportunities, the overarching plan goals, and the final mitigation strategy.

Key Stakeholders representing a range of interests, from neighboring jurisdictions to disproportionately impacted communities, were also instrumental in setting the tone and direction of the plan from the beginning.

Building upon the local expertise and experience of these formalized groups, Napa County and the other participating jurisdictions incorporated comments from the public throughout the plan to tailor the goals and mitigation strategy toward specific community concerns and needs. Public feedback was collected on an ongoing basis and at major injection points, such as the conclusion of the online survey and following the public review period. These results are fully documented in Appendix B, and Section 4.3 highlights key findings, including summarizing feedback gained from the public survey.

2.1.3 Planning Process Library
During the update process for this MJHMP, the Steering Group, county-wide HMPT, and each jurisdictional planning team engaged in and completed five different exercises to assess risk, prioritize hazards, identify areas of concern and hazard problems, assess existing capabilities and opportunities for improvement, and develop the mitigation strategy. These exercises, facilitated by the Steering Group and Consultant Team, were integral components of the planning team meetings described in Section 2.1.1. A description of each exercise and its purpose are provided below.

The outcomes of the five exercises completed by each participating jurisdiction are organized and documented in the form of a Planning Process Library (Table 2-7). Specific results from these exercises are incorporated into Volume 1 for Napa County; the results for other participating jurisdictions are further described in their Volume 2 annex.

Exercise #1: Risk Assessment
The risk assessment exercise aimed to thoroughly identify both county-wide and jurisdiction-specific vulnerabilities based on the best available data. Hazard overlay maps, demographics reports, and other tools were utilized to educate and engage stakeholders with deep-dive discussions on local hazard concerns and priorities, guiding the development of the risk assessment. This exercise was facilitated by the Steering Group and Consultant Team and engaged all the planning teams in reviewing and discussing the many factors that can impact community hazard risk. The Planning Process Library contains the snapshot hazard CAL OES SUBMITTAL - JUNE 2026
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maps for each participating jurisdiction and a county-wide demographics report that were refined through this exercise and formed the foundation for identifying and understand hazard risks.

Exercise #2: Hazard Prioritization
The county-wide HMPT and each of the jurisdictional planning teams considered and screened a broad range of hazards presented in relevant local, regional, and statewide hazard mitigation planning documents. The risk assessment (Exercise #1), past hazard events, and climate change projections also informed the selection of hazards for profiling in this plan. Each jurisdictional planning team then reviewed and prioritized all potential hazards, deciding which are most likely to happen (probability) vs how severe the impacts could be from an event (impact) (Figure 2-5). The crosswalk of documents reviewed, as well as the results of screening and prioritizing relevant hazards, are outlined in Section 3.1. The Planning Process Library contains the completed risk matrixes resulting from this exercise, ranking hazards based on probability in and potential impact on each participating jurisdiction.

Exercise #3: Areas of Concern
All of the planning teams engaged in this exercise to identify areas of concern and the potential effects of each of the identified priority hazards on the planning area in terms of impacts, victims, or threats. Problem statements were developed for these areas of concern, which describe the specific nature of the consequences of a hazard occurrence on the community and its assets. This ensured that the mitigation Figure 2-5: Napa County Planning Team Breakout Meeting #1.5 (Hazard Prioritization) CAL OES SUBMITTAL - JUNE 2026
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actions developed through the fifth exercise were tailored for each community and to the specific problems created by various hazard scenarios within it. The Planning Process Library contains the resulting problem statements for each jurisdiction.

Exercise #4: Capabilities & Opportunities Assessment
The capabilities and opportunities assessment exercise involved analyzing the existing planning and regulatory, administrative and technical, financial, and education and outreach resources of each participating jurisdiction, as well as opportunities for future improvement of those capabilities. Various tools are used to implement hazard mitigation activities, depending on that jurisdiction’s authority, such as long-range planning documents; building, subdivision, and zoning regulations; trained staff; information systems; various funding mechanisms; and community preparedness education.

Each of the Steering Group members, supported by their planning team and the Consultant Team, evaluated their jurisdiction’s current capabilities in comparison to previous mitigation planning efforts and provided updated information to reflect recent developments. As part of the exercise, they also explored opportunities to improve capabilities and the various funding options available to support implementation of their mitigation strategy. The Planning Process Library contains the resulting capabilities and opportunities assessment for each participating jurisdiction.

Review & Incorporation of Existing Documents
In organizing resources for the plan update, one of the initial steps was for each jurisdiction to identify and review their existing community plans, regulations, strategies, studies, and other documents with relevance to local community planning and hazards to help inform the development of the MJHMP. This effort was led by the Steering Group with support from the Consultant Team, county-wide HMPT, and jurisdictional planning teams. Many documents reviewed already incorporate hazard topics and mitigation planning while others, some seemingly unrelated, would be appropriate to integrate in the future. Relevant documents are cited throughout the MJHMP and in each hazard profile of the risk assessment.

As part of Exercises #1 through #4, the planning teams reviewed existing planning, policy, and regulatory documents for their relevance to hazard mitigation planning. The review included many documents into which previous mitigation plans are already incorporated, as reflected in the works cited, capabilities and opportunities assessment, and each the hazard profiles. Since the adoption of the 2020 MJHMP, Napa County and other jurisdictions have incorporated the plan into their various planning and regulatory mechanisms, including development standards and general, capital improvement, and hazard-specific plans.

The capabilities and opportunities assessment for each participating jurisdiction identifies the past and current usage of the documents found to be relevant to hazard mitigation, and opportunities for their future integration with the MJHMP directly or indirectly (Section 4.2). The documents were also closely examined as part of the hazard prioritization exercise completed by each jurisdiction’s planning team. The objective CAL OES SUBMITTAL - JUNE 2026
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of this review was to ensure plan alignment with ongoing efforts, identify opportunities for integration, and avoid redundancy.

A summary of county-related documents which were identified, reviewed, and incorporated into this 2026 MJHMP, or that may be integrated with the county’s hazard mitigation planning efforts in the future, is provided in the Planning Process Library and Section 2.1.3.

Exercise #5: Strategy Development
The final exercise conducted as part of the interactive and comprehensive development of this MJHMP was the creation of the mitigation strategies. Based on the results from all the previous exercises and background information surrounding them, including strategies from past mitigation plans, the Steering Group and Consultant Team led each of the planning teams through the review of potential mitigation actions and a variety of alternatives to consider for their particular jurisdiction during Breakout Meeting Series #2. Following individual strategy development, the county-wide HMPT met again to construct a collaborative mitigation strategy that leverages resources to address shared needs among all the jurisdictions to better protect Napa County as a whole (Figure 2-6).

The draft actions were then further refined by the Steering Group and jurisdictional leads to incorporate community feedback received during the public draft review period. The final county-wide and individual mitigation action plans are provided in the Planning Process Library. More details on the county-wide and Napa County strategies are found in Section 4, and the action plans for the other participating jurisdictions are found in the Volume 2 annexes.

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Table 2-7: Planning Process Library
Jurisdiction Exercise No. / Title Library Links
County-Wide
1 Risk Assessment County-Wide Demographics Report
2 Hazard Prioritization County-Wide Risk Matrix
5 Strategy Development Table 4-3: County-Wide Mitigation Action Plan Individual
Jurisdictions
1 Risk Assessment Hazard and Demographic Maps
2 Hazard Prioritization Risk Matrices
3 Areas of Concern Problem Statements
4 Capabilities and Opportunities
Assessment Assessments
5 Strategy Development Alternatives Considered (see Action Plans for final Strategies)
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2.2 Assessing Risk
This section describes the second major step in the planning process: the comprehensive assessment of risks associated with natural hazards in Napa County. The county-wide HMPT and each of the jurisdictional planning teams conducted a risk assessment for their planning areas. This involved identifying and prioritizing the natural hazards affecting Napa County as a whole and each participating jurisdiction individually, followed by assessing vulnerabilities to those identified hazards. Results from this risk assessment process aided the identification of an effective mitigation strategy.

The process for, and results from, identifying and prioritizing which hazards to assess are described in Sections 3.1 and 0. This section describes the procedures, methods, and support tools used in assessing the hazard risks to all the planning areas. The hazard-specific vulnerability assessments are documented in the nine hazard profiles.

Wildfire
SECTION 3.3.1
Flood
SECTION 3.3.2
Dam Failure
SECTION 3.3.3
Earthquake
SECTION 3.3.4
Slope Failure
SECTION 3.3.5
Drought
SECTION 3.3.6
Severe Weather
SECTION 3.3.7
Extreme Heat
SECTION 3.3.8
Climate Change
SECTION 3.3.9
Assessing risks and vulnerabilities exposes the unique characteristics of individual hazards and begins the process of narrowing down which areas within the county are vulnerable to specific hazard events. The vulnerability assessment included field visits and a Geographic Information System (GIS) overlaying method for examining such vulnerabilities more in depth. The planning teams of participating jurisdictions completed this exercise both singly and jointly with the county-wide HMPT. The hazards ultimately identified and prioritized varied widely depending on the geographic make up of, priorities of, and services provided by the individual participating jurisdiction. Using these methods, participating jurisdictions estimated the potential losses of populations, property, and facilities and infrastructure from their priority hazards.

The risk assessment process was conducted in alignment with FEMA’s Local Mitigation Planning Handbook and used best practices to identify vulnerabilities in populations, property and private assets, and critical facilities and infrastructure.

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The purpose of the risk assessment in Section 3 is to evaluate the locations and causes of the priority natural hazards affecting significant parts of the planning area, as well as the existing regulatory environment around them, their probability, the extent and severity of their potential impacts, and the vulnerabilities within the community. The findings serve as the foundation for developing targeted mitigation strategies that are both proactive and cost-effective. The risk assessment is comprised of the following:
▪ Section 1.4, Community Profile: Providing a geographic and demographic overview of Napa County as the basis for the assessment, highlighting the populations most vulnerable to hazards in the planning area.
▪ Section 3.1, Hazard Identification & Prioritization: Identifying hazards that pose the most significant threats and prioritizing them based on probability and potential impact in the county and other participating jurisdictions.
▪ Section 3.3, Vulnerability to Specific Hazards (Hazard Profiles): Detailing the characteristics, history, probability, and potential impacts of each hazard, including:
• Exposure Analysis: Mapping or describing the populations, assets, and critical facilities and infrastructure exposed to each hazard.
• Vulnerability Analysis: Assessing how susceptible different populations, structures, and other assets are to hazard impacts.

Risk assessment data is provided for all county-wide priority hazards and for Napa County, specifically, in 3.3 of this volume; other participating jurisdictions are profiled individually in Volume 2.

2.2.1 RAMP (Risk Assessment Mapping Platform)
A highly interactive, web-based mapping platform was used to assist in the vulnerability assessment.

RAMP, the Risk Assessment Mapping Platform, is hosted by and accessed through the project website (mitigatehazards.com/napacountymjhmp) and allows the interactive discovery of robust risk, vulnerability, and exposure data developed especially for Napa County and the other participating jurisdictions. RAMP was built specifically for mitigation planning and is a vital tool in identifying hazard exposure and risk (Figure 2-7).

RAMP displays the total population, total parcels and property values, and a jurisdiction’s facilities and buildings overlaid with natural hazards layers. Users can filter these layers by hazard and inventory type, as well as by jurisdiction. RAMP’s robust data filtering and summation calculations allow the user to understand and visualize vulnerabilities at the property-level with detailed information on the number of people and structures exposed to various hazards. This brings interactivity and individual discovery to the GIS analysis performed for the vulnerability assessment, allowing for the exploration of various hazard risks posed within and around a community and, ultimately, aiding in the prioritization of mitigation resources.

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RAMP enabled Napa County and the other participating jurisdictions to pinpoint their vulnerabilities and reinforce problem statements to support the mitigation strategy. The county-wide HMPT and each of the jurisdictional planning teams used RAMP in meetings and as needed to understand vulnerabilities both county-wide and to their planning areas, and especially to vulnerable populations and critical facilities and infrastructure.

2.2.2 Vulnerability Assessment Methodology
This subsection explains the methodologies used to assess vulnerabilities across the county and in individual communities. The approach includes both qualitative and quantitative analyses to evaluate the risks associated with specific hazards. Methodologies were selected based on FEMA guidelines, state-level best practices, and local policy and expertise to ensure accuracy and relevance, and all data sources used in the analysis meet standards appropriate for hazard mitigation planning. The vulnerability assessment includes:
▪ GIS-Based Mapping: Visually representing hazard-prone areas, critical infrastructure and facilities, and vulnerable populations.
▪ Data Collection and Analysis: Utilizing historical disaster data, climate projections, and demographic information to estimate risk.
▪ Scenario Modeling (Earthquake and Climate Change): Conducting hypothetical disaster scenarios to understand potential impacts under varying conditions, including climate change. ▪ Community Surveys and Stakeholder Feedback: Incorporating local knowledge to identify vulnerabilities not captured in traditional data.

Figure 2-7: RAMP User Interface
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This section also describes how the vulnerability assessment accounts for climate change impacts, which are expected to increase the frequency and severity of hazards like wildfire, flood, and extreme heat.

In order to describe vulnerability for each hazard, it is important to first understand the total population and assets at risk. This section provides an overview of the methods used in the hazard-specific vulnerability assessments of Section 3.3. For each type of hazard, the assessment begins with a general explanation of the phenomenon. Vulnerabilities to each hazard are then assessed through a two-step process. First, population, critical facilities and infrastructure, and all parcels across the county are inventoried to establish a comprehensive understanding of the area (“lay of the land”). Second, the inventories are used to calculate the exposure of and potential impacts to people and assets at various levels of severity. A more detailed explanation of the explanation on risk assessment methods, see Appendix A.

Population & Asset Inventory
This subsection details the process for developing the inventory of populations and assets that are vulnerable to hazard events. It includes the following examples:
▪ Critical Facilities: Hospitals, fire stations, police stations, and emergency shelters. ▪ Critical Infrastructure: Roads, bridges, utilities, and communication networks. ▪ Essential Services: Water treatment facilities, power plants, and public health facilities. ▪ Vulnerable Populations: Areas with high concentrations of elderly residents, disabled individuals, low-income households, and non-English-speaking communities.

The inventory was mapped using GIS tools to clearly illustrate hazard exposure and support data-driven decision-making for developing the mitigation strategies. The population and asset inventory provides a baseline to measure the significance of or vulnerability to natural hazard events. The asset inventory can also be used to estimate damages and financial losses expected during a “worst-case scenario” event for each hazard.

Each participating jurisdiction’s assets have been inventoried to use as inputs for the vulnerability assessment, including people, parcels, property values, and critical facilities and infrastructure.

Population
The primary purpose of the MJHMP is to better protect people; thus, determining the population located near each geographically defined natural hazard is critical. The demographic data for Napa County and the other participating jurisdictions discussed is derived from the U.S. Census Bureau’s American Community Survey 5-Year Estimates (ACS 5-Year) from 2017 to 2022. The figures presented are intended to highlight broader regional trends relevant to hazard mitigation planning efforts rather than inform specific decision-making or administrative actions.

Each natural hazard scenario affects county residents differently depending on the location of the hazard, the population characteristics and density where the hazard event could occur, and other local factors. In CAL OES SUBMITTAL - JUNE 2026
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the Community Profile, Section 1.5, specific characteristics of Napa County’s population are discussed in detail, including highlighting which populations are most vulnerable to hazard events and impacts. The hazard-specific vulnerability assessments presented in the hazard profiles of Section 3.3 summarize the population exposure for each priority hazard, if definable.

Parcel Value Inventory
The Napa County Assessor’s data was essential in identifying parcel and property value exposures to each priority hazard. The data includes 2023 to 2024 fair market values of at-risk private parcels and improvements as well as jurisdictional properties and assets. The parcel value inventory for Napa County is summarized in Table 2-8 and includes market value1, content replacement value, and total assessed value (“total value”). These elements are called out in the table because, in the event of a disaster, the value of the infrastructure or improvements to the land is usually the focus of concern, as structures can be rebuilt or contents replaced. Although there may be severe environmental impacts that result from a hazard event, the land itself is generally not a total loss.
▪ Total market value as presented in this MJHMP reflects Napa County Assessor data, including fair market value where available. If no fair market value was available for a given property, the value reflects the assessed improvement value, which is often an underestimate of actual value. ▪ Total content value was calculated based on the Assessor's use codes, translated to occupancy-based multipliers.

Each occupancy class prescribes a specific content cost multiplier used to calculate the content cost values shown in the summary and in the hazard profiles in Section 3.3. Occupancy-based content cost multipliers used in this plan reflect those found in the FEMA HAZUS-MH (Hazards U.S. Multi-Hazard) 4.2 technical manuals.

The hazard profiles in Volume 1 outline predicted impacts to Napa County’s parcel value inventory for each hazard’s geographic extent. The annexes in Volume 2 contain the same information for other participating jurisdictions.

Table 2-8: Napa County Parcel Counts and Values
Total Parcels Total Market Value ($) Total Content Value ($) Total Value ($) Unincorporated County 13,668 $11,215,199,644 $9,248,691,039 $20,463,890,683 American Canyon 7,245 $6,967,924,501 $7,565,767,223 $14,533,691,724 Calistoga 2,099 $1,062,206,651 $610,632,454 $1,672,839,105 City of Napa 36,814 $17,554,595,166 $14,323,871,166 $31,878,466,332 St Helena 3,000 $2,028,106,739 $1,390,754,675 $3,418,861,414 1 Market Value Includes a long-term asset which indicates the cost of the constructed improvements to land, such as buildings, driveways, walkways, lighting, and parking lots.

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Total Parcels Total Market Value ($) Total Content Value ($) Total Value ($) Yountville 1,310 $617,098,970 $445,216,581 $1,062,315,551 Total Napa County 64,136 $39,445,131,670 $33,584,933,139 $73,030,064,808 Note: Parcel value is calculated by summing the value of all of the buildings on a given parcel. Each building's value is calculated by multiplying the square footage (Napa Assessor's Office) by a replacement cost of $425/sq ft . Content value calculated using content multipliers per HAZUS occupancy classes.

Critical Facilities & Infrastructure Inventory
Critical facilities and infrastructure, such as a fire station or bridge along an evacuation route, are of particular concern when conducting hazard mitigation planning. These critical assets can be structures, infrastructure, or other improvements that, because of their function, size, service area, or uniqueness, have the potential to cause disruption of vital socioeconomic activities if destroyed, damaged, or functionally impaired. As such, the vulnerability assessment for each profiled hazard qualitatively discusses critical facilities and infrastructure with regard to each hazard’s severity footprint.

The critical facilities and infrastructure inventory for this MJHMP was developed from a variety of sources, including datasets from participating jurisdictions as well as state, federal, and private industry sources.

Although the inventory is not comprehensive due to data limitations, all data sources have a level of accuracy acceptable for planning purposes. For additional information on sources, see Appendix A. Based on the inventory, a spatial database developed to translate this information into georeferenced2 points and lifelines that represent physical locations.
▪ Points include critical facilities such as government buildings, police stations, fire stations, shelters, hospitals, elder care facilities, childcare facilities, schools, and transportation and utility structures.

Points also include facilities that handle hazardous materials. ▪ Lifelines include critical infrastructure related to transportation routes; delivery of water, wastewater, electrical power, liquid fuel, and natural gas; and other crucial utility infrastructure lines.

Figure 2-8 provides an overview of the critical facility points and infrastructure lifelines located within the participating jurisdictions. Some critical facility information has been omitted from this document due to security concerns and requirements, and a detailed list of these assets is not provided. More detailed lists are on file with the individual jurisdictions that oversee those assets. 2 To georeference something means to define its existence in physical space; that is, to establish its location in terms of map projections or coordinate systems. The term is used both when establishing the relation between raster or vector images and coordinates and when determining the spatial location of other geographical features.

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Hazard Exposure
This subsection describes how the exposure of populations and assets to hazards was quantified. Damage estimation uses analytical tools to project financial impacts and loss estimations under various disaster scenarios and footprints. The analysis estimated potential damage based on factors such as:
▪ Hazard Intensity and Frequency: Historical data on past events, combined with climate projections. ▪ Building Stock and Infrastructure Vulnerabilities: Age, construction materials, and resilience of existing infrastructure.
▪ Geographic Distribution: Identification of floodplains, wildfire zones, landslide-prone areas, seismic fault lines, and other hazard areas with geospatial extents. ▪ Socioeconomic Impacts: Potential economic losses to businesses, critical services, and residential properties.

Alongside a study of past hazard events, geospatial data plays a critical role in these assessments by pinpointing the population and assets vulnerable to the hazards identified in this plan. This analysis is particularly effective when hazards have distinct spatial footprints that can be overlaid onto the locations of people and assets. In Napa County’s planning area, such hazards as flood, wildfire, and earthquake have known geographic extents and corresponding spatial information; drought and severe weather hazards, on the other hand, impact large areas and do not have specific geospatial extents.

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Figure 2-8: Critical Facilities Point Locations
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Once the geographic extents of spatially-discreet hazards were established, the population and asset inventories were then used to generate specific exposure and damage estimations based on the severity of specific hazard event scenarios. The hazards in Napa County which have known geographic extends and corresponding spatial information, and thus have exposure and damage estimations, are:

Wildfire
SECTION 3.3.1
Flood
SECTION 3.3.2
Dam Failure
SECTION 3.3.3
Earthquake
SECTION 3.3.4
Slope Failure
SECTION 3.3.5
Climate Change
(Sea-Level Rise)
SECTION 3.3.9
Several data sources are necessary to conduct a thorough vulnerability analysis. Figure 2-9 provides an exhibit of the data inputs and outputs used to create the vulnerability analysis results presented in the hazard profiles of Section 3.3.

Figure 2-9: Data Inputs and Outputs
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Population & Asset Exposure
“Exposure” of assets and population refers to the total counts of people, parcels, facilities, and other assets within the planning area in which a hazard event may occur. A natural hazards overlay was developed to reflect the combination of many known natural hazard spatial footprints. The spatial overlay method enables summarization of building values, parcel counts, population, and critical facility and infrastructure exposure within a hazard’s geographic extents. Exposure numbers were generated using Napa County Assessor information, address points, and parcel data for replacement and content cost estimates. See Figure 2-10 as a hypothetical exposure to flood hazards.

2.3 Developing a Mitigation Strategy
This MJHMP was prepared in accordance with DMA 2000 plan update requirements, FEMA’s mitigation guidance, Cal OES policies, and the California Office of Land Use and Climate Innovation (LCI) recommendations. The development of this plan included identifying hazard problems across the planning area, setting goals for a mitigation strategy, assessing existing capabilities, considering the costs and benefits of alternatives, and developing new and improved mitigation actions.

Section 4 provides an explicit mitigation strategy and blueprint for reducing potential losses identified in the risk assessment based on the existing capabilities of Napa County; the same is provided in Volume 2 for each of the other participating jurisdictions.

2.3.1 Identify the Problem
As part of the mitigation action identification process, the HMPT and the jurisdictional planning teams identified areas of concern in and the potential impacts of each of the prioritized hazards, both county-wide and in their respective communities. Specific statements were developed to describe each jurisdiction’s hazard problems based on the risk assessment contained in Section 3 and lengthy discussions about unmapped vulnerabilities. These “problem statements” are organized by three major areas of concern, which describe the nature of the consequences or effects of a hazard occurrence on the community and its assets as victim, impact, or threat. This categorization ensures that the identified actions in the mitigation strategy are tailored to each jurisdiction and the specific problems created by various hazard scenarios.

Figure 2-10: Hazard Exposure Explanation Graphic
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Each hazard problem statement that was developed is addressed by at least one mitigation action; however, most are mitigated with a combination of short- and long-range activities, through planning, regulatory, operational, physical, or other projects. Napa County’s problem statements are identified at the end of each hazard profile in Section 3.3 and those of other participating jurisdictions are identified in their individual annexes in Volume 2.

The problem statements are also available as part of the Mitigation Action Support Tool (MAST), which is summarized in Section 2.3.5 and will be available via the project website throughout the plan’s lifecycle to assist the participating jurisdictions in monitoring and improving the mitigation strategy.

Interpreting Areas of Concern (AOCs)
Areas of concern describe how hazards impact different aspects of a community and set the stage for identifying mitigation actions that reduce risk by changing the victims, impacts, or threats of different hazards. Each problem statement identifies which type of hazard problem (i.e., AOC) it concerns the most.

Victim
Who is (most) impacted?
Impact
What are the direct and indirect
impacts of hazard events?
Threat
What local conditions create
location-specific risk?
Example Statement Example Statement Example Statement
Seniors and people with mobility
limitations lack adequate
evacuation support during a fastmoving wildfire.

Heavy rain events overwhelm aging
and inadequate drainage
infrastructure such as undersized
culverts.

FEMA floodplain maps do not reflect
localized or future flood conditions,
limiting the ability to plan for or
fund effective mitigation.

2.3.2 Identify Mitigation Goals
Hazard mitigation plans must identify goals for reducing long-term vulnerabilities to identified hazards. (44 CFR § 201.6(c)(3)(i)) The county-wide HMPT and jurisdictional planning teams reviewed past mitigation goals from the 2020 Napa County MJHMP or their plan, as applicable, and from the 2023 California State Hazard Mitigation Plan (SHMP) and other relevant plans to determine their present validity. The teams also reviewed the updated risk assessment (Section 3.3) and public survey results (Section 4.3) in defining the goals for this plan.

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with the current policies and goals of participating jurisdictions. The four resulting goals, which are presented in Section 4.1, formed the basis for the development of the Mitigation Strategy and specific mitigation actions.

2.3.3 Conduct Capabilities Assessment
A capabilities assessment is a comprehensive review of participating jurisdictions’ existing capabilities to implement the mitigation actions in the MJHMP and tools available to address known issues and weaknesses from identified natural hazards. The Steering Group and planning teams identified their jurisdiction’s capabilities to implement the mitigation strategy. These capabilities were also reviewed for future opportunities for integration or enhancement, including the development of new policies, expansion of training programs, and increased collaboration with regional and state partners.

Napa County’s assessment of its capabilities and future opportunities is found in Volume 1, Section 4.2.2; Volume 2 of this plan includes assessments for all other participating jurisdictions as part of their specific annex. For more information on the regulatory environment surrounding each hazard, see the hazard profiles in Section 3.3.

2.3.4 Develop Mitigation Actions
The county-wide HMPT and jurisdictional planning teams developed mitigation actions, as both planning activities and other types of projects, to address identified hazard problems from the risk assessment in line with their capabilities. As part of this process, the teams reviewed and analyzed the status of mitigation actions from previous plans, determining which have been completed, which are no longer relevant, and which need to be updated to reflect current circumstances. Alternative actions considered and the final mitigation action plans adopted are provided as part of the Planning Process Library (Table 2-7).

After reviewing mitigation actions from past hazard plans and priorities, projects, and activities other relevant documents, the planning teams developed potential new actions through interactive exercises and discussions, as outlined in Section 2.1.3. The potential mitigation actions were then further scrutinized based on their relevance to the priority hazards, support from community members, realistic implementation parameters, and alternative measures that could be used to address various aspects of the hazard problems.

Public & Stakeholder Input
As part of the mitigation strategy development, Napa County and the other participating jurisdictions reviewed and incorporated stakeholder feedback and public comments collected throughout the planning process to tailor the goals and mitigation actions toward specific community concerns and needs. Public input was collected on an ongoing basis via an online survey and at major injection points, such as during community outreach events and during the public review period. These engagement efforts and results are CAL OES SUBMITTAL - JUNE 2026
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fully documented in Appendix B and summarized in Section 2.1.2. Section 4.3 highlights public and stakeholder input that was specifically used in developing the mitigation strategies.

SMARTIE Principles
In developing the mitigation actions for this 2026 MJHMP, the planning teams used the principles of “SMARTIE” to ensure the mitigation strategy was realistic and actionable. These principles provided a framework for defining actions and evaluating their costs and benefits. A mitigation action that meets SMARTIE principles is:
▪ Specific: Clearly defined project scope and goals.
▪ Measurable: Outcomes and milestones can be tracked.
▪ Attainable: Designed to align with the agency’s
capabilities or those of partners.
▪ Relevant: Tied directly to risks identified in the plan. ▪ Timely: Includes deadlines for completion.
▪ Inclusive: Intentionally involves or benefit diverse
populations.
▪ Equity Minded: Acknowledges impacts to access and
functional needs populations and other special
considerations.

Mitigation Alternatives
Once hazard problems were defined (problem statements) and local resources and capabilities accounted for (capabilities assessment), a range of mitigation solutions are identified that could be used to address concerns. These mitigation alternatives are evaluated for their associated costs and benefits to pinpoint which actions provide the greatest risk reduction using available resources and should be made part of the final mitigation strategy. This section describes the process that was used in identifying and evaluating a range of mitigation alternatives to address the hazards prioritized in the risk assessment (0). Alternatives include both structural measures (e.g., flood barriers, firebreaks, seismic retrofitting) and non-structural measures (e.g., zoning changes, public education, early warning systems) and were assessed based on:
▪ SMARTIE Principles
▪ Cost-Effectiveness
▪ Community Acceptance
▪ Alignment with Mitigation Goals
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The Consultant Team drafted many mitigation actions for each jurisdiction to consider, including refined actions from the previous mitigation plan, as applicable, and new alternative actions. FEMA’s six broad mitigation categories, listed below, provide the framework for identifying and evaluating potential mitigation actions. Categorizing mitigation actions in this way ensures a comprehensive approach to mitigation in the county, addressing various facets of vulnerability reduction and resilience enhancement across the community and its natural environment.
▪ Prevention (PRV): Measures aimed at avoiding or minimizing hazard impacts through planning and the implementation of building codes, land use regulations, and other preventative measures. ▪ Property Protection (PPRO): Actions to safeguard individual properties from hazard damage by modifying or relocating existing buildings and structures to enhance resilience. ▪ Public Education and Awareness (PE&A): Efforts to engage and inform community members about hazard risks and effective mitigation strategies to foster preparedness and resilience. ▪ Natural Resource Protection (NRP): Strategies that preserve, restore, or manage natural resources, systems, and functions to reduce hazard impacts.
▪ Emergency Services (ES): Measures that help minimize the impacts of hazard events on people and property by enhancing emergency preparedness and response capabilities. ▪ Structural Projects (SP): Projects to construct, install, or improve infrastructure and systems designed to reduce hazard impacts.

During Breakout Meeting Series #2 and HMPT Meeting #4, the planning teams drafted, evaluated, and refined mitigation actions that considered a wide range of implementation strategies, relevant to both county-wide needs and individual jurisdictions, using FEMA’s six broad categories. Early discussions focused on reviewing previous mitigation strategies, identifying current hazard-related challenges, and developing potential actions to address priority hazard concerns. These ideas were then further reviewed and prioritized through collaborative sessions involving input from jurisdictional staff and a diverse group of stakeholders. The planning teams selected the most efficient and cost-effective actions by assessing vulnerabilities, evaluating existing capabilities, and building consensus on how best to address identified problems and meet the community’s mitigation goals.

The final mitigation actions selected by each participating jurisdiction’s planning team are presented in the Mitigation Action Plan. The Napa County Mitigation Action Plan is found in Volume 1, Section 4.5; action plans for all other participating jurisdictions are found in the Volume 2 annexes. In addition, the collaborative, County-Wide Mitigation Action Plan presented in Section 4.4 identifies combined efforts to address common hazard problems to increase the overall resilience of the county.

The following subsections provide examples of mitigation actions according to the six FEMA mitigation categories that were considered by the planning teams. This alternatives evaluation process is documented as part of the Planning Process Library discussed in Section 2.1.3 and provided in Table 2-7 (Alternatives Considered) to demonstrate transparency and support future funding applications.

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PREVENTION (PRV)
Preventative (PRV) activities keep hazard problems from getting worse and are typically administered through government programs or regulations addressing building and land development. Preventative actions are particularly effective in reducing a community’s future vulnerability in areas where development has not yet occurred or where capital improvements have not been substantial. Examples of preventative activities include:
▪ Planning and zoning
ordinances
▪ Building codes
▪ Riverine or fault zone
setbacks
▪ Open space preservation
▪ Floodplain regulations
▪ Stormwater management
regulations
▪ Drainage system
maintenance
▪ Capital improvements
programming
Examples of Local PRV Alternatives
▪ Update Land Use and Development Regulations: Revise development codes and standards to better address natural hazards such as wildfire, flood, slope failure, drought, and climate change. ▪ GIS and Hazard Mapping Enhancements: Conduct detailed mapping for hazards such as flood and slope failure and expand GIS capabilities to increase utility of the data. ▪ Restrict Development in High-Risk Zones: Adopt policies to limit new development and capital investments in coastal and high wildfire risk zones.

PROPERTY PROTECTION (PPRO)
Property protection (PPRO) measures involve the modification, relocation, or removal of existing buildings and structures to help them better withstand the forces of a hazard. Examples include:
▪ Building elevation
▪ Retrofitting (e.g., seismic
design techniques, etc.)
▪ Safe rooms, shutters,
shatter resistant glass
▪ Insurance
▪ Critical facilities
protection
Examples of Local PPRO Alternatives
▪ Backup Power for Critical Facilities and Services: Secure backup power supplies for emergency shelters, water treatment plants and pumps, and other critical facilities to ensure continuity of service during outages.
▪ Structure Hardening Incentives: Create a program that incentivizes private property owners to conduct structural improvements to protect homes, such as low-interest loans for elevation above the base flood or rebates for installing flashing and vents in high-risk wildfire zones.

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PUBLIC EDUCATION & AWARENESS (PE&A)
Public education and awareness (PE&A) activities advise community members and elected officials about hazards, hazardous areas, and mitigation techniques they can use to protect themselves and their property.

Measures to educate and inform the public include:
▪ Outreach projects,
including neighborhood
and community outreach
▪ Hazard mapping
▪ Materials library
▪ Speaker series/
demonstration events
▪ Real estate disclosures
▪ School children
educational programs
▪ Hazard expositions
Examples of Local PE&A Alternatives
▪ Hazard Awareness Events: Develop annual community outreach events and educational activities to increase awareness of local hazards and mitigation strategies. ▪ Water Conservation Campaign: Develop a public outreach campaign to promote water conservation during drought conditions.
▪ Flood Insurance Information: Make National Flood Insurance Program (NFIP) and flood risk information available at public locations, such as libraries, and via a virtual planning desk.

NATURAL RESOURCE PROTECTION (NRP)
Natural resource protection (NRP) activities reduce the impacts of hazards by preserving or restoring natural areas and their protective functions. Such areas include floodplains, wetlands, steep slopes, and sand dunes.

Parks, recreation, or conservation agencies and organizations often implement these protective measures.

Examples of these measures include:
▪ Erosion and sediment
control
▪ Floodplain protection
▪ Vegetation management
(e.g., fire-resistant
landscaping, fuel breaks)
▪ Watershed management
▪ Wetland and habitat
preservation/restoration
Examples of Local NRP Alternatives
▪ Groundwater Recharge Infrastructure: Preserve and improve natural areas and ecosystems that support groundwater recharge to enhance water availability during drought conditions. ▪ Fuel Management Projects: Implement vegetation management strategies outlined in the CWPP, including thinning, prescribed burning, and invasive species removal. ▪ Slope Stabilization Projects: Develop a priority list of areas at high risk for slope failures, then implement stabilization projects using natural and engineered techniques to prevent landslides and erosion.

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EMERGENCY SERVICES (ES)
Emergency services (ES), while not traditionally categorized as mitigation, play a critical role in minimizing the impacts of natural hazard events on people and property. These services focus on preparedness, response, and recovery efforts to protect lives, reduce damages, and ensure the continuity of critical operations. The measures often include pre-disaster planning, resource staging, and infrastructure improvements to enhance emergency response capabilities. Examples include:
▪ Warning systems
▪ Sandbag staging for flood
protection
▪ Identification /
construction of
evacuation routes
▪ Installing temporary
shutters on buildings for
wind protection
Examples of Local ES Alternatives
▪ Expand Emergency Shelter Capacity: Work with partner jurisdictions to expand shelter capacity and improve shelter accessibility and safety across the county. ▪ Communications System Improvements: Improve the reliability and coverage of emergency communications and alter systems to ensure consistent messaging and enhanced interagency coordination during emergencies.

STRUCTURAL PROJECTS (SP)
Structural projects (SP) are intended to lessen the impacts of a hazard by modifying the environment and natural progression of a hazard event through construction. They are usually designed by engineers and managed or maintained by public works staff. Examples include:
▪ Utility facility /
infrastructure upgrades
▪ Stormwater detention /
retention facilities
▪ Dam Retrofits
Examples of Local SP Alternatives
▪ Transportation Infrastructure Improvements: Evaluate bridges, roads, and other transportation infrastructure located in high-hazard areas and implement improvements as necessary to ensure reliability of emergency access and evacuation routes.
▪ Drainage Structure Replacement Program: Develop an inventory of culverts and other drainage structures and establish a program for replacing and improving inadequate and failure-prone stormwater infrastructure.
▪ Electrical Grid Hardening: Collaborate with utility providers to harden electrical grid infrastructure against hazards such as high wind and wildfire, including burying power lines, installing reinforced poles or protective devices, and managing nearby trees.

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Cost/Benefit Review
Mitigation action plans must be prioritized according to a cost/benefit analysis of the proposed projects and programs and their associated costs. (44 CFR §2 01.6(c)(3)(iii)) The benefits of proposed actions were weighed against estimated costs as part of the project prioritization process; however, it should be noted that this review does not meet FEMA Hazard Mitigation Grant Program (HMGP) and Pre-Disaster Mitigation (PDM) grant program requirements. A less formal, less costly approach was used because some projects may not be implemented for up to 10 years, and associated costs and benefits could change dramatically in that time. Parameters were established for assigning subjective ratings (high, medium, and low) to the costs and benefits of these projects.

Cost ratings were defined as follows:
▪ High: Existing funding will not cover the cost of the project; implementation would require new revenue through an alternative source (for example, bonds, grants, and fee increases). ▪ Medium: The project could be implemented with existing funding but would require a reapportionment of the budget or a budget amendment, or the cost of the project would have to be spread over multiple years.
▪ Low: The project could be funded under the existing budget. The project is part of or can be part of an ongoing existing program.

Benefit ratings were defined as follows:
▪ High: Project will provide an immediate reduction of risk exposure for life and property. ▪ Medium: Project will have a long-term impact on the reduction of risk exposure for life and property, or project will not provide an immediate reduction in the risk exposure for property. ▪ Low: Long-term benefits of the project are difficult to quantify in the short-term.

Using this approach, projects with positive benefit versus cost ratios (such as high over high, high over medium, medium over low, etc.) were considered cost-beneficial and prioritized accordingly. For many of the strategies identified in this action plan, the partners may seek financial assistance under the HMGP or PDM programs, both of which require detailed benefit/cost analyses. These analyses will be performed on projects at the time of application using the FEMA benefit-cost model. For projects not seeking financial assistance from grant programs that require detailed analysis, the partners reserve the right to define “benefits” according to parameters that meet the goals and objectives of this MJHMP.

Prioritization Framework
In addition to considering public and stakeholder input and the initial cost/benefit analysis, mitigation actions were prioritized according to four criteria (see Section 4.3). This prioritization framework was developed by the Steering Group to further focus the individual and county-wide mitigation strategies on those efforts that address the most concerning hazards, can realistically achieve multiple outcomes, will have positive equity impacts, and align with existing jurisdictional strategies.

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2.3.5 MAST (Mitigation Action Support Tool)
Development of the mitigation strategy for this 2026 MJHMP was strengthened by using an online platform called MAST, the Mitigation Action Support Tool. MAST is a web-based interactive tool that enables multiple users to search, view, enter, and update mitigation actions, ideas or projects, and other information.

As the planning cycle progresses, MAST will also be used to monitor and revise the mitigation strategy. As a living document, mitigation activities will be updated through this web interface application developed specifically for this 2026 MJHMP.

State & Federal Funding Application Assistance
Using MAST, participating jurisdictions can improve their ability to apply for state and federal funding, including in the initial grant application processes through Cal OES. MAST provides participating jurisdictions and plan reviewers (Cal OES and FEMA) easy access to mitigation action details that can be leveraged to support future risk reduction efforts and specific mitigation projects within the planning area.

Additionally, MAST can be used to assist jurisdictions in tracking project progress for grant and other required reporting.

Monitoring & Evaluating the Strategy
As local circumstances change and the plan evolves, mitigation actions will be updated through MAST. The online interface provides jurisdictions the ability to easily record changes and progress and to make adjustments to the strategy as needed. MAST will assist mitigation project managers across all the participating jurisdictions in making adjustments reporting on the status and effectiveness of the mitigation action and overall strategy.

As described in Section 2.4.1, a county-wide advisory team will oversee the collection and review of progress reports on jurisdiction-specific strategies and will develop a county-wide progress report to deliver to the public and appropriate governing bodies annually. With MAST, updating the status and details of mitigation projects throughout the planning lifecycle will be greatly simplified and consolidated into one location.

2.4 Adopting & Implementing the Plan
Ensuring the MJHMP serves as a practical and accessible tool for Napa County and other participating jurisdictions is crucial for effective implementation and minimizing community hazard impacts. Section

2.4.2 describes the planning frameworks, maintaining ongoing public engagement, and establishing procedures for implementation, monitoring, evaluation, and regular updates to keep the plan current and responsive to evolving needs. These efforts aim to enhance resilience and safeguard community well-being against hazards.

Napa County and all participating jurisdictions adopted the plan in compliance with DMA 2000. See Adoptions Records in the Executive Summary of this plan.

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2.4.1 Monitoring, Evaluating & Updating
This section describes the strategies for monitoring, evaluating, and updating the 2026 MJHMP throughout its lifecycle. Napa County and the other participating jurisdictions will monitor and adjust this plan in accordance with all FEMA and Cal OES requirements in order maintain eligibility for federal and state funding opportunities. The strategy includes designating an advisory team, monitoring progress and conducting annual reviews, continuing public and stakeholder engagement, and integrating the plan with other mechanisms to ensure its success.

Hazard Mitigation Advisory Team (HMAT)
The Steering Group oversaw the development of the 2026 MJHMP and made decisions on key elements of the plan, including the maintenance strategy; however, a Hazard Mitigation Advisory Team (HMAT) led by the Napa County Sheriff’s Office will oversee the implementation phase of the five-year planning cycle. The primary roles of the HMAT in overseeing the implementation of the MJHMP are:
▪ Acting as a forum for hazard mitigation issues and continuing to solicit community input ▪ Facilitating interjurisdictional collaboration on hazard mitigation ▪ Coordinating implementation efforts across jurisdictions and partner agencies ▪ Reviewing annual progress reports and developing a county-wide progress report ▪ Tracking county-wide strategy progress and making recommendations on improvements The HMAT will strive to include representation from all participating jurisdictions, Key Stakeholders and other partner agencies, and members of the public. Keeping the HMAT intact for the duration of the planning cycle will also assist in jump-starting the next plan update.

Duties of the HMAT
The HMAT will coordinate with the participating jurisdictions and other responsible parties for each countywide mitigation action to assess its effectiveness and make modifications as appropriate. In addition, the HMAT will collect and review annual progress reports from participating jurisdictions and develop a countywide report to provide input to the Napa County Board of Supervisors and, as appropriate, elected officials of other participating jurisdictions.

The progress reports will cover possible improvements to the county-wide and jurisdiction-specific strategies and changes to be considered at the next update, in addition to progress on mitigation actions. In evaluating the MJHMP’s effectiveness, the following questions should be considered:
▪ Has the nature or magnitude of hazards affecting the planning area changed? ▪ Are there new hazards that have the potential to impact the planning area? ▪ Do the identified goals and actions address current and expected conditions? ▪ Have mitigation actions been implemented or completed? ▪ Has the implementation of identified mitigation actions resulted in expected outcomes? CAL OES SUBMITTAL - JUNE 2026
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▪ Are current resources adequate to implement the MJHMP? ▪ Should additional local resources be committed to address identified hazards? Completion of the individual jurisdiction progress reports will be the responsibility of each participating jurisdiction annually. The reports will also be posted online for public review and released to the media. It will be the HMAT’s role to help identify revisions and issues to be addressed by in the next update or other community plans.

The HMAT will also play a key role in preparing for the next MJHMP update by maintaining records and identifying emerging risks. Future updates to the plan will account for any new hazard vulnerabilities, special circumstances, or information or methodologies that become available. Issues that arise or updates made during the interim monitoring and evaluating period will be incorporated into the next update of the MJHMP, and the questions identified above will remain valid during its preparation.

Monitoring & Update Schedule
Monitoring the progress of mitigation actions will continue through the five-year period between adoption of this plan and the next update effort. The newly formed HMAT will meet annually, at a minimum, to monitor implementation, develop a progress and improvement report, and deliver that report to the Napa County Board of Supervisors and other jurisdictional decision-makers, as appropriate. The team’s meeting schedule will be posted online, and meetings will be open to the public.

The MJHMP will be updated again after five years, as required by DMA 2000, and the update process will begin at least one year prior to the plan’s expiration in 2031. However, should a significant hazard event occur within Napa County in the meantime, the HMAT will reconvene within 30 days of the disaster to review and update the plan as appropriate. As a DMA 2000 requirement, the County Board of Supervisors and decision-makers of other participating jurisdictions, as appropriate, will adopt any written updates. 5-Year Update
Future updates to the MJHMP will account for any new hazard vulnerabilities, special circumstances, or new information or methodologies that become available. Issues that arise or updates made during the interim monitoring and evaluating period will be incorporated into the next update of the MJHMP, and the questions identified above will remain valid during its preparation.

The next five-year update will follow the same four-step FEMA planning process used for this 2026 update, including public and stakeholder engagement through meetings and other means to inform changing risks and priorities. Led by the Napa County Sheriff’s Office, the HMAT will initiate the process at least one year before the plan expires and, depending on the scope of the update, will procure outside consultation to guide the process as needed. The HMAT will review the 2026 plan and process undertaken and make adjustments to methods and tools to strengthen the next update effort.

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As detailed in Section 2, FEMA’s four hazard mitigation planning process steps that will be followed for the next update are:
▪ Step 1: Organize Resources
▪ Step 2: Assess Risk
▪ Step 3: Develop a Mitigation Strategy
▪ Step 4: Adopt and Implement the Plan
Funding Assistance Monitoring
The true worth of any mitigation plan is its implementation and success under grant and other funding programs. This MJHMP was assembled to reduce the risk of natural hazards and also to meet the requirements of DMA 2000 to maintain eligibility under FEMA’s Hazard Mitigation Assistance (HMA) grant programs. FEMA’s HMA Program is the catalyst that drives increased understanding and supports proactive community action to reduce losses from natural hazards. As discussed further under Section 4.2.3, FEMA administers several programs that provide funding for local agencies with approved mitigation plans, including:
▪ Hazard Mitigation Grant Program (HMGP): Assists in implementing long-term hazard mitigation planning and projects following a Presidential major disaster declaration. ▪ Flood Mitigation Assistance (FMA): Provides funds for planning and projects to reduce or eliminate risk of flood damage to buildings that are insured under the National Flood Insurance Program (NFIP) on an annual basis.

Post-Disaster HMGP Process
Following a disaster, Cal OES and Napa County officials would perform Preliminary Damage Assessments (PDA) of areas that sustained damage in a joint effort with FEMA. Cal OES then submits the information collected through the FEMA Regional Office, along with a damage estimate to request a declaration from the President. A Presidential Major Disaster Declaration provides for the availability of HMGP funds at the request of the Governor in eligible communities. Figure 2-11 shows a timeline of how projects should be developed and administered by local government and FEMA under the HMGP program. HMGP grant recipients have 36 months from the close of the application period to complete projects.

Figure 2-11: HMGP Timeline
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Mitigation Action Support Tool (MAST) Updates
Hazard problem statements and mitigation activities will be updated through a web-based interface application developed specifically for the county and other participating jurisdictions, which is available on the project website. This Mitigation Action Support Tool (MAST) will assist jurisdictions in making adjustments to their mitigation strategy as circumstances evolve, and will assist mitigation project managers across all the participating jurisdictions in reporting on the status and effectiveness of the mitigation action and overall strategy. Plan maintenance will be primarily performed through MAST, with most updates to the MJHMP occurring easily through this tool. MAST is further described in Section 2.3.4.4.

Continuing Public & Stakeholder Engagement
The strategy for continuing engagement will utilize the same goals and resources as the strategy for developing the 2026 update, as described in Section 2.1.2 and documented in Appendix B. During the fiveyear planning cycle, the HMAT and individual jurisdictions will continue to involve members of the community in the implementation phase of the process through public gatherings, meetings, and workshops. In addition, the Key Stakeholders involved in this update and other partner organizations will be invaluable resources for supporting continued public engagement, especially with underserved populations.

An electronic copy of the 2026 MJHMP document will be accessible through the Napa County website and at the Napa County Sheriff’s Office.

Information on events related to hazard mitigation or the MJHMP will be announced via the same media tools discussed in Section 2.1.2.1, including jurisdictional and partner websites, social media, and the project website (mitigatehazards.com/napacountymjhmp) and on the county’s webpage.

2.4.2 Plan Integration
For the MJHMP to be successful, the recommendations and underlying principles of the plan should be incorporated into various aspects of local governance, including community planning and development (e.g., capital improvement budgeting) as well as everyday operations. Integration into a variety of departments and roles within the county and participating jurisdictions provides an opportunity to network, identify, and highlight mitigation activities and opportunities at all levels of government. It is also important to monitor resources and opportunities which can be leveraged to implement the mitigation strategy.

As the plan evolves, the following should be considerations for implementing and integrating the mitigation strategy:

1. Use processes that already exist. Take advantage of tools and procedures identified in the capability assessment in Section 4.2.2. Leaning on mechanisms already in use and familiar to participating jurisdictions will give the planning implementation phase a strong initial boost.

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2. Update work plans, policies, and procedures. Incorporating hazard mitigation concepts and activities can help integrate the HMP into daily operations. These changes can include how major development projects are addressed in hazard-prone areas or can ensure that hazard mitigation concerns are considered in the approval of major capital improvement projects.

3. Revise job descriptions. Work with department or agency leads to revise job descriptions to include mitigation-related duties. Designating a “mitigation lead” within a department can further institutionalize hazard mitigation with little financial expenditure or programmatic overhaul.

The capabilities assessment for each participation jurisdiction identifies the past and current usage of various planning and regulatory mechanisms relevant to hazard mitigation, and opportunities for their future integration with the MJHMP directly or indirectly. This integration helps to ensure plan alignment with ongoing efforts, identify opportunities for integration, and avoid redundancy. In general, information from this MJHMP will be incorporated into:
▪ General Plans: The MJHMP will provide information that can be incorporated into the safety, land use, and other elements of general plans for the county and municipalities as they are updated, and many jurisdictions will update their safety element to incorporate the MJHMP in compliance with Assembly Bill (AB) 2140. Specific risk and vulnerability information from the MJHMP will also assist in identifying areas where development may be at risk to potential hazards for integration with land use, circulation, economic, and other elements.
▪ Land Use and Development Regulations: The MJHMP provides information that enables the county and other participating jurisdictions to make decisions on appropriate land use and development codes, such as zoning or construction standards which can increase resilience against natural disasters. Some participating jurisdictions’ mitigation actions directly recommend updates to or adoption of new regulations to better address hazard risks. ▪ Hazard and Other Specific Plans: The MJHMP will provide information that can be incorporated into drought, water, and other specific or areas plans, and the MJHMP likewise captured mitigation actions derived from these types of documents. The MJHMP will provide risk assessment information that can be included in updates to groundwater, stormwater, floodplain management, and other plans. In addition, the MJHMP may be integrated with capital improvement, operational, maintenance, or emergency response plans with valuable information from this plan such as geospatial hazard footprints, exposure summaries, and damage estimations.

A summary of county-related mechanisms into which hazard mitigation and this 2026 MJHMP have been or could be incorporated is provided in the Capabilities and Opportunities Assessment, Section 4.2.2.

Capabilities assessments for other participating jurisdictions are provided in the Volume 2 annexes.

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Section 3.Risk Assessment
The risk assessment measures the potential impacts of hazards on life, property, and the economy within the Napa County planning area. The intent of a risk assessment is to identify the qualitative and quantitative vulnerabilities of a community to the greatest extent possible given available data. These assessments increase understanding of hazard impacts and provide the foundation to develop and prioritize mitigation actions. In turn, mitigation actions reduce damage from disasters through increased preparedness and focusing resources on areas of the greatest vulnerability.

This risk assessment section evaluates potential losses from a given hazard event by analyzing the vulnerabilities of buildings, infrastructure, and people. It identifies the characteristics and potential consequences of hazards, explores how much of the planning area could be affected by a hazard, and assesses the impacts on Napa County assets. Assessments for other participating jurisdictions are found in their individual annex in Volume 2. The risk assessment methodology used to analyze hazard vulnerabilities is described in Section 2.2 and Appendix A. The risk assessment approach consists of four components:
▪ Community Profile (Section 1.4)
▪ Hazard Identification and Screening (Section 3.1)
▪ Hazard Prioritization (Section 3.2)
▪ Vulnerability to Specific Hazards (Section 3.3)
The Community Profile in Section 1.4 offers a geographic and demographic overview of Napa County, highlighting detailed demographics of the community members most vulnerable to hazards. Each Volume 2 annex contains a similar discussion of that jurisdiction’s characteristics. By tailoring risk-informed development to the needs of underrepresented communities, planners and policymakers can foster more resilient, equitable, and sustainable environments. This approach not only safeguards the most vulnerable populations but also enhances the overall resilience of the entire community.

3.1 Hazard Identification & Screening
Per FEMA guidance, the first step in developing the risk assessment is to identify which hazards should be the focus. Hazard selection is a twofold process. First, the planning teams considered and screened a broad set of hazards profiled in local, regional, and state-wide hazard planning documents. A crosswalk of this first step is outlined in Section 3.1.1. Second, the planning teams reviewed historic hazard events which had significant impacts on the planning area to inform the prioritization process, as summarized in Section 3.1.2.

3.1.1 Potential Hazards
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planning area and nearby region. Table 3-1 provides a crosswalk of hazards identified in the 2020 Napa County MJHMP, 2023 Napa County General Plan Safety Element, and 2023 California State Hazard Mitigation Plan (SHMP). Ten different potential hazards were identified based on this thorough document review.

The crosswalk was used to develop a preliminary hazards list, providing a framework for HMPT to evaluate which hazards were truly relevant county-wide and which were not. For example, volcanoes were considered to have no relevance to Napa County, while earthquake, flood, and wildfire were indicated in every hazard document. The preliminary hazards list was then used as the basis for prioritizing which hazards should be profiled and analyzed in detail in this 2026 MJHMP, as discussed in Section 3.3.

Each planning team for other participating jurisdictions also completed this document review and crosswalk identifying potential hazards relevant to their individual jurisdiction, the results of which are reported in their Volume 2 annex.

Table 3-1: Document Review Crosswalk of Potential County-Wide Hazards Hazard 2020 Napa County
MJHMP
2023 Napa County
Safety Element
2023 California
SHMP
Agricultural Pests ■ ■ ■
Avalanche ■
Climate Change ■ ■ ■
Coastal ■
Dam Failure ■ ■ ■
Drought ■ ■ ■
Earthquake / Liquefaction ■ ■ ■
Extreme Cold ■
Extreme Heat ■
Extreme Weather / Storms ■ ■ ■
Flood ■ ■ ■
Geologic / Mass Movement ■ ■ ■
Human-Caused ■ ■
Insects ■
Levee Failure ■
Pandemic Disease ■ ■ ■
Sea Level Rise ■
Soil ■
Subsidence ■
Tornado ■
Tsunami / Seiche Wave ■
Volcano ■
Wildfire ■ ■ ■
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3.1.2 Past Major Hazard Events
One important consideration in identifying and prioritizing hazards is past major hazard events, especially those that triggered federal or state disaster declarations. The HMPT reviewed and considered past major hazard events in Napa County as part of the screening and identification process.

Most available information on major past hazard events comes from federal or state disaster declarations.

These declarations may be granted when the severity and magnitude of an event surpasses the ability of the local government to respond and recover. Additional federal or state disaster funding (or both) is generally available in response to a disaster declaration. State funding assistance is provided when a local government’s capacity to respond to the disaster is exceeded. Should the disaster be so severe that both the local and state governments’ capacities are exceeded, a federal emergency or disaster declaration may be issued allowing for the provision of federal assistance.

The federal government may issue a disaster declaration through FEMA, the U.S. Department of Agriculture (USDA), and the Small Business Administration (SBA). FEMA also issues emergency declarations, which are more limited in scope and do not include the long-term federal recovery programs that accompany major disaster declarations. The quantity and types of damage are the determining factors.

A USDA disaster declaration occurs when agricultural areas are particularly impacted by an event. This type of declaration certifies that the affected county has suffered at least a 30% loss in one or more crop or livestock areas and provides affected producers with access to low-interest loans and other programs to help mitigate the impacts. Importantly, all counties neighboring those receiving USDA disaster declarations are eligible for the same assistance. Drought declarations may also occur through the USDA, as agricultural areas such as Napa County can be particularly impacted by drought. In recent history, Napa County has qualified for USDA assistance in 2020, 2021, and 2025.

Hazard events occurring outside the county can also directly or indirectly impact the planning area. For example, dam failures or wildfires may occur outside Napa County but either hazard event could affect watersheds that drain into it, resulting in flooding or longer-term watershed health impacts. Power supply also could be interrupted due to extraterritorial hazard occurrences.

Napa County has received 39 federal disaster declarations3 since 1964, some of which were statewide. Figure summarizes the number of disaster declarations by type since 1964, and Table 3-2 lists the more recent declarations for Napa County since 1995. Wildfire, severe weather, and flooding events have caused the most declared disasters, accounting for 31 out of 39. Wildfires have historically occurred during the late summer and fall months, July to October, while severe weather and flooding events typically hit during the winter months, December through March.
3 California was declared as part of Hurricane Katrina evacuation; however, no disaster occurred in California.

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Table 3-2: Napa County Federal Disaster Declarations 1995 to Present Year Month / Day Incident Description Disaster No.
2023
04/02 Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, & Mudslides
DR-4699-CA
2023 03/09 Severe Winter Storms, Flooding, Landslides, & Mudslides EM-3592-CA 2023 01/13 Severe Winter Storms, Flooding, Landslides, & Mudslides DR-4683-CA 2023 01/08 Severe Winter Storms, Flooding, & Mudslides EM-3591-CA 2020 10/15 Wildfires DR-4569-CA
2020 09/26 Glass Fire FM-5376-CA
2020 08/21 Wildfires DR-4558-CA
2020 08/17 Lnu Lightning Fire Complex FM-5331-CA
2020 03/12; 03/21 Covid-19 Pandemic EM-3428-CA/DR-4482-CA 2019 05/01; 05/17 Severe Storm, Winter Storm, Mud & Landslides, Flooding DM-4431/4434 2017 10/09 California Atlas Fire FM-5214
2017 10/09 California Patrick/Nuns Fire FM-5222
2017 2/14; 3/16; 04/01 Severe Storm, Winter Storm, Mud & Landslides, Flooding DM-4301/4305/4308 2017 10/08 California Tubbs Fire FM-5215
2017 10/10 Wildfire DM-4344
2015 07/23 California Wragg Fire FM-5091
2015 09/13 California Valley Fire FM-5112
2014 09/11 California Earthquake DR-4193
2014 03/12 California Butts Fire FM-5057
2008 06/22 Wildfire DR-2776
2006 03/29 Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1646 2006 12/17 Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1628 Figure 3-1: Napa County Federal Disaster Declarations by Hazard Type 1964 to Present CAL OES SUBMITTAL - JUNE 2026
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Year Month / Day Incident Description Disaster No.
2000 09/03 California Earthquake DR-1342
1999 08/24 California Extreme Fire Hazards EM-3140
1998 02/02 Severe Storms, Flooding DR-1203
1997 02/16 Severe Storms, Flooding, Mud & Landslides DR-1155 1995 01/03 Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1044 1995 02/13 Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1046 Source: FEMA Disaster Database

3.2 Hazard Prioritization
Based on review of past hazard events and existing plans, reports, and other technical studies, data, and information about hazards with the potential to affect Napa County, the county-wide HMPT determined the realm of regional hazards that could affect the planning area. From this preliminary list, the HMPT then completed a hazard risk ranking exercise (described in Section 2.1.3) to determine which hazards should be prioritized for assessment in this MJHMP and, consequently, which hazards should be the focus in the mitigation strategy.

The hazard prioritization process combines historical data, local knowledge, and consensus opinions to produce a risk matrix that illustrates whether each profiled hazard is an extreme, high, medium, or low priority for the planning area. Criteria for probability verses impact were also used to evaluate hazards and identify those that pose the highest risks.

Probability: What is the likelihood of an event?
▪ Unlikely: Less than a 1% annual probability, or occurs rarely ▪ Possible: Between 1% and 10% annual probability, or could occur but is uncommon ▪ Likely: Between 10% and 100% annual probability, or recurrent but not frequent ▪ Highly Likely: 100% or higher annual probability, or occurs frequently Impact: In terms of deaths, injuries, damage, or disruption, what are the anticipated impacts? ▪ Minor: Very few or no injuries, only minor property damage, or minimal disruption of critical facilities and services
▪ Limited: Minor injuries only, 10% to 25% of property in affected area damaged or destroyed, or disruption of critical facilities and services for more than a day ▪ Critical: Multiple deaths or injuries possible, 25% to 50% of property in affected area damaged or destroyed, or disruption of critical facilities and services for more than a week ▪ Catastrophic: High number of deaths or injuries possible, more than 50% of property in affected area damaged or destroyed, or disruption of critical facilities and services for a month or more CAL OES SUBMITTAL - JUNE 2026
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The results of the risk ranking exercise for Napa County are identified in the county’s Hazard Risk Matrix (Figure 3-2) and detailed in Table 3-4, which summarizes why the county-wide priority hazards were chosen and why other hazards were not prioritized. This hazard risk prioritization exercise was completed by the planning team for each of the participating jurisdictions, the results of which are described in the jurisdictional annexes of Volume 2.

Figure 3-2: Napa County Hazard Risk Matrix
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Secondary & Compounding Hazard Events
The MJHMP primarily examines the vulnerabilities of hazard events individually within the planning area.

However, it is recognized that hazards often occur in combination, leading to compounded effects.

Frequently, a secondary hazard is triggered by or occurs following the first event, such as a severe rain event following a wildfire that causes debris flows in the burn scar. Other events are compounded by outside factors, like wildfire evacuations occurring during Public Safety Power Shutoff (PSPS) events. This plan discusses these multi-hazard risks within the hazard profiles of Section 3.3 by highlighting potential secondary and compounding hazards that could result from initial events or intensify impacts.

The plan also considers the implications of pairing hazard events with the need for emergency evacuation or response, particularly in light of experiences during the COVID-19 pandemic. This includes local governments actively considering response and mitigation strategies that address the impacts of multiple hazard events, such as a pandemic occurring alongside other hazards like floods, severe weather, or wildfires.

By understanding the interplay among different hazards and preparing for compounded events, the MJHMP aims to enhance the resilience and preparedness of the planning area against a wide range of potential disaster scenarios.

3.2.1 Climate Change Impacts
Climate change is a global phenomenon that can impact many aspects of society including public health, natural and managed resources, critical facilities, buildings, infrastructure, and services. Projected changes to the climate are dependent on location. In California, the University of California Berkeley Geospatial Innovation Facility developed a platform called Cal-Adapt funded by the California Energy Commission (CEC). This platform provides tools and data on climate change across the state, including for Napa County, from global scale models that have been localized (downscaled) to 3.7-mile by 3.7-mile grids.

Napa County is experiencing climate change in various forms, including increasing frequency and severity of severe weather and wildfires, which offer a tangible glimpse of future conditions. Existing conditions combined with predictive modeling indicate that the impacts of climate change will continue to be significant and will increase over time impacting all aspects of the local environment, built and natural.

Recent events, including the COVID-19 pandemic, reveal another clear truth: the impacts of climate change will disproportionately be experienced by the most vulnerable and marginalized populations.

Table 3-3 summarizes the potential impacts of climate change on various hazards, noting that all impacts will disproportionately affect vulnerable populations.

Cal-Adapt data combined with information from the California Fourth Climate Change Assessment was used to model future changes in specific types of hazards. Projections are outlined by two separate Representative Concentration Pathways (RCP):

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▪ RCP 4.5 is a medium emissions scenario where global emissions peak by the year 2040 and then decline.
▪ RCP 8.5 is a high emissions scenario in which global emissions continue to rise through the end of the twenty-first century.

Table 3-3: Climate Change Impacts on Hazards
Hazard Summary of Impacts
Extreme Heat
By 2100, annual number of extreme heat days above 98.6°F increase from 4 to 22 and number of warm nights above 59.5°F increase from 5 to 39 (RCP 4.5). Increases in average maximum temperature also contribute to worsening air quality.

Wildfire Approximately 20% increased probability of wildfire in a 10-year period. Increases in wildfires also contribute to worsening air quality.

Slope Failure Increased susceptibility of landslides as precipitation variability increases and wildfires increase in frequency, area, and severity.

Flood
Low-lying areas experiencing more frequent and intense flooding, with the area of flooding potentially expanding. Precipitation will arrive in more intense storms, increasing runoff and flash flooding. Additionally, increased moisture transport and delivery from atmospheric river storms.

Sea-Level Rise Up to 6.0 feet of sea level rise by 2100, inundating areas along the San Pablo Bay and Napa River through.

Drought
More frequent and severe periods of drought, challenging drinking water supplies and aquatic species habitat. Precipitation will arrive in more intense storms, increasing runoff and reducing the amount of water recharging local aquifers, further exacerbating the impacts of drought on water supply. Increases in longer periods of drought also contribute to worsening air quality.

3.2.2 Disproportionately Impacted Populations
Certain populations face heightened risks following disasters due to factors such as age, economic status, mobility limitations, physical or mental disabilities, and geographic location. Vulnerability is not static; individuals may be more at risk from some hazards than others. For instance, a low-income family without transportation may struggle during rapid evacuations for wildfires or floods but could be adequately prepared for an earthquake event. Mitigation efforts can reduce personal vulnerability for some but not all individuals, especially those reliant on caregiving networks like children, the elderly, and persons with disabilities. Further, environmental risk often disproportionately burdens lower-income and marginalized communities, who typically reside in hazard-prone areas with fewer mitigation resources. (National Center for Disaster Preparedness, 2020)
In considering which hazards to prioritize and profile in this risk assessment, the county-wide HMPT reviewed local demographics and identified communities that have been disproportionately affected by hazard events in the past and those that could be impacted by such disasters in the future. In the vulnerability assessments for profiled hazards, these disproportionately impacted populations are more specifically identified and discussed in the context of the demographics of the respective jurisdiction. For CAL OES SUBMITTAL - JUNE 2026
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the county-wide hazards profiled in this Volume 1, Napa County’s Community Profile in Section 1.5 is the basis for the population vulnerability discussions summarized herein.

3.2.3 County-Wide Priority Hazards
The results of the initial risk ranking exercise completed by the county-wide HMPT and then refined by the County Planning Team are identified in the county’s completed matrix in Figure 3-2. Table 3-4 provides the final list of priority hazards and subhazards with additional details about why the county-wide priority hazards were chosen and why other hazards were not prioritized. However, it should be noted that many hazards not prioritized for profiling are briefly discussed as secondary or compounding hazards, and subhazards that were profiled and included in the risk assessment are listed specifically. This prioritization exercise was also completed by all other jurisdictional planning teams, the results of which are described in the jurisdictional annexes of Volume 2 and provided in the Planning Process Library (Section 2.1.3).

Table 3-4: County-Wide Hazards Prioritization Summary
Hazard Priority Explanation
Earthquake / Liquefaction Extreme Profiled in Section 3.3.4, including Liquefaction Wildfire Extreme Profiled in Section 3.3.1
Flood High Profiled in Section 3.3.2, including Levee Failure Levee Failure High Profiled in Section 3.3.2 under Flood Extreme Weather / Storms High Profiled in Section 3.3.5 as Severe Weather, including High Wind, Heavy Rain, and Winter Weather
Drought High Profiled in Section 3.3.6
Geologic / Mass Movement High Profiled in Section 3.3.5 as Slope Failure Extreme Heat High Profiled in Section 3.3.8
Agricultural Pests High Profiled in Section 3.3.9 under Climate Change as part of Agricultural Impacts
Sea Level Rise High Profiled in Section 3.3.9 under Climate Change Climate Change High Profiled in Section 3.3.9, including Sea Level Rise and Agricultural Impacts, and discussed as a compounding hazard in relevant profiles Dam Failure Medium Profiled in Section 3.3.3
Avalanche - Not a priority due to low probability
Coastal - Not a priority due to low probability and impact potential Extreme Cold - Not a priority due to low probability
Human-Caused - Not a priority due to being addressed in other plans Insects - Not a priority due to being addressed in other plans Pandemic Disease - Not a priority due to being addressed in other plans Soil - Not a priority due to low probability and impact potential Subsidence - Not a priority due to low probability and impact potential Tornado - Not a priority due to low probability
Tsunami / Seiche Wave - Not a priority due to low probability and impact potential Volcano - Not a priority due to no exposure
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3.3 Vulnerability to Specific Hazards
This section provides profiles of the various priority hazards affecting Napa County, including an overview of characteristics, historical information, and the existing regulatory environment pertaining to the hazard.

In addition to county-wide considerations for each, the profiles in this Volume 1 document also analyze vulnerabilities specific to unincorporated county areas and how the priority hazards may affect populations, property, and critical facilities and infrastructure within Napa County’s jurisdiction.

Most importantly, Napa County’s county-wide hazard mitigation strategy presented in Section 4 responds to the particular vulnerabilities outlined in this section. The mitigation strategy provides prescriptions or actions to achieve the greatest reduction of vulnerability based on this section, which results in saved lives, reduced injuries, reduced property damage, and protection for the environment in the event of a natural hazard. Methods for calculating exposure and loss estimates are described in Section 2.2 and Appendix A.

The hazard profiles in this section provide quantifiable exposures to people, property, and county assets where possible and describe other vulnerabilities particular to Napa County; similar analyses for the other participating jurisdictions are presented in the Volume 2 annexes for their priority hazards.

Wildfire
SECTION 3.3.1
Flood
SECTION 3.3.2
Dam Failure
SECTION 3.3.3
Earthquake
SECTION 3.3.4
Slope Failure
SECTION 3.3.5
Drought
SECTION 3.3.6
Severe Weather
SECTION 3.3.7
Extreme Heat
SECTION 3.3.8
Climate Change
SECTION 3.3.9
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3.3.1 Wildfire Hazard Profile
A wildfire is any uncontrolled fire occurring on undeveloped land that requires fire suppression. Wildfires can be ignited by lightning or by human activity such as smoking, campfires, equipment use, and arson. The 2023 California State Hazard Mitigation Plan defines wildfires as:

Any free-burning vegetative fire that initiates from an unplanned ignition, whether natural (e.g., lightning) or human-caused (e.g., powerlines, mechanical equipment, escaped prescribed fires), where the management objective is full suppression.

Wildfire is one of the most significant hazards affecting Napa County due to the county’s combination of rugged topography, extensive vegetation, recurring drought conditions, and widespread development in the wildland-urban interface (WUI). Napa County’s fire environment includes forested uplands, shrublands, grasslands, and agricultural landscapes, all of which can contribute to wildfire ignition and spread under the right weather and fuel conditions. The county’s wildfire risk is heightened by steep slopes, narrow canyons, limited access in rural areas, and the presence of dispersed residential development in high and very high fire hazard severity zones.

Napa County is characterized by a complex and highly fire-prone landscape defined by a central valley bounded by the Mayacamas and Vaca Mountains, with extensive watersheds, canyons, and diverse microclimates that influence wildfire behavior. Vegetation across the county ranges from grasslands and shrublands to oak woodlands and coniferous forests, creating a continuous and varied fuel profile. These natural conditions, combined with dispersed rural development and significant WUI areas, contribute to elevated wildfire risk throughout much of the county. Steep terrain and limited access in mountainous areas further complicate suppression efforts and increase the likelihood of rapid fire spread under extreme weather conditions.

Wildfire is a persistent and recurring hazard in Napa County, with a long history of large, damaging fires across the landscape. Recent events, including the LNU Lightning Complex and Glass Fire in 2020, burned hundreds of thousands of acres and destroyed thousands of structures, demonstrating the scale and intensity of wildfire potential in the region. Fire behavior modeling indicates that under severe weather conditions, a significant portion of the county is capable of supporting high-intensity fire, including flame lengths exceeding 20 feet and the potential for torching and crown fire, which generate embers capable of igniting spot fires well ahead of the main fire front (Napa Firewise, 2021). This dynamic significantly increases the risk of structure-to-structure ignition within developed areas.

The County’s wildfire risk is further compounded by increasing development in fire-prone areas, climatedriven changes in fuel conditions, and the growing frequency of extreme weather events. Napa County’s Emergency Operations Plan recognizes wildfire as a major hazard requiring coordinated, multijurisdictional response and long-term preparedness, particularly given the potential for large-scale CAL OES SUBMITTAL - JUNE 2026
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incidents to overwhelm local resources and require mutual aid . As wildfire seasons lengthen and fuels become more receptive to ignition, the potential for large, fast-moving fires and urban conflagration is expected to increase, underscoring the need for sustained mitigation efforts, including fuel management, defensible space, and coordinated emergency response planning.

Secondary & Compounding Hazards
Wildfires can produce a wide range of secondary and compounding hazards that extend beyond the immediate fire perimeter. These hazards can increase damage to infrastructure, worsen environmental impacts, and prolong recovery time. The secondary and compounding hazards are briefly discussed in this section in relation to wildfire, and some are discussed in other profiles. In Napa County, these include slope destabilization from post-fire flooding in the Slope Failure Hazard Profile (Section 3.3.5), high wind in the Severe Weather Profile (Section 3.3.7), drought (Section 3.3.6), and climate change (Section 3.3.9).

Slope Destabilization & Sedimentation
Wildfires remove vegetation that stabilizes soil, increasing the likelihood of erosion, slope failure, debris flows, and sedimentation during subsequent rain events. In Napa County, steep terrain in the Mayacamas Mountains, Vaca Range, and other upland areas make post-fire landscapes especially vulnerable to landslides and flooding. Loss of vegetation can allow rainfall to mobilize ash, soil, and rock, which may damage roads, bridges, culverts, reservoirs, and water supply infrastructure. Sediment runoff can also affect streams and the Napa River, reducing water quality and increasing flood risk downstream.

High Wind
High wind events are a major factor in wildfire ignition and spread in Napa County. Strong winds, low humidity, and high temperatures can create conditions favorable for rapid fire growth, long-range ember transport, and extreme fire behavior. Wind-driven fires can spread quickly across ridges and valleys, threatening communities and overwhelming suppression efforts. High winds also increase the risk of powerline damage and equipment failure, which can lead to ignition during dry conditions.

The Napa Valley has a characteristic southerly wind that originates from the San Francisco Bay and, during the dry season, strong winds come from the north occasionally. Both are significant factors in the spread of wildland fires. In addition, local topographic wind effects within canyons and along ridgelines intensify fire behavior and contribute to the long-distance transport of embers.

Climate Change & Drought
Fire in western ecosystems is determined by climate variability, local topography, and human intervention.

Climate change has the potential to affect multiple elements of the wildfire system: fire behavior, ignitions, fire management, and vegetation fuels. Hot, dry spells create the highest fire risk. Drought and increased temperatures intensify wildfire danger by drying out and stressing vegetation. Climate change also may increase winds that spread fires. Faster fires are harder to contain and, thus, are more likely to expand into CAL OES SUBMITTAL - JUNE 2026
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residential neighborhoods. Prolonged drought conditions can also reduce water availability for firefighting and increase the vulnerability of forests and grasslands to insect damage, disease, and tree mortality, all of which add to fuel loads.

Napa County is already considered to be an area that is at high-risk for wildfires. Climate change is projected to increase this current risk by anywhere from 10% to 20%, and the county will need to continue to adapt to this projected increase and the additional threats it brings to emergency services, roads, water supplies, housing access, and quality of life.

As climate conditions shift toward longer fire seasons and drier fuels, secondary wildfire effects are expected to increase in both frequency and severity across Napa County. A changing climate is expected to subject forests to increased stress due to drought, disease, invasive species, and insect pests, such as the shothole borer. These stressors are likely to make forests more vulnerable to catastrophic fire due to increased standing dead biomass. While periodic fires are natural processes and fulfill an important ecological function, catastrophic fire events that cannot be contained or managed can cause serious threats to homes and infrastructure, especially for properties located in or adjacent to the WUI. Moreover, rain events are predicted to become more severe in our changing climate, and post-fire flooding and slope stabilization could worsen as well.

Smoke
Wildfire smoke can affect large portions of Napa County, including areas far from the active fire. Smoke contains fine particulate matter (PM2.5), and other pollutants that can cause respiratory and cardiovascular problems, particularly for sensitive populations such as children, older adults, outdoor workers, and individuals with existing health conditions. Agricultural workers may be especially vulnerable because they often work outdoors during harvest and other peak seasons that coincide with wildfire season. Smoke can also disrupt transportation, tourism, schools, and outdoor activities, creating economic and social impacts beyond the burn area.

Urban Conflagration
In areas where homes and businesses are closely spaced, wildfire can transition into an urban conflagration, where structures ignite one another through radiant heat, ember intrusion, or direct flame contact. This risk is highest in the wildland-urban interface and in developed areas located within High and Very High Fire Hazard Severity Zones. Once multiple structures ignite, firefighting resources may be overwhelmed, and fire spread may continue even after the wildland fire front has passed. Building materials, landscaping, and inadequate defensible space can increase the likelihood of structure-to-structure fire spread.

According to FEMA and the National Fire Protection Association (NFPA), an urban conflagration occurs when a structural fire spreads from building to building in a continuous, uncontrollable manner, often involving multiple city blocks. This type of hazard is exacerbated by high winds, limited firefighting access, compromised water supply, and inadequate building separation or fire-resistance standards.

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The 2020 LNU Lightning Complex Fire demonstrated the destructive potential of wildfires transitioning into residential zones. High winds, dry fuels, and closely spaced structures enabled rapid fire spread, resulting in the loss of homes and the displacement of tens of thousands of residents. Key factors contributing to urban conflagration include:
▪ Flying embers (firebrands) igniting structures and vegetative fuels far ahead of the main fire front ▪ Limited defensible space around structures
▪ Combustible building materials
▪ Narrow, steep, or dead-end access roads that hinder evacuation and response The risk of urban conflagration is highest in areas with dense housing, limited infrastructure resilience, and poor access for fire suppression, such as in the areas of Atlas Peak, Calistoga, Howell Mountain, and Pope Valley. As wildfire behavior intensifies due to climate and fuel conditions, the potential for fires to escalate into community-scale conflagrations will remain a critical concern for hazard mitigation and land use planning in Napa County.

Power Outages & Public Safety Power Shutoffs (PSPS)
Wildfires and extreme fire weather conditions can lead to widespread power outages, either from damage to electrical infrastructure or from Public Safety Power Shutoff (PSPS) events implemented to reduce ignition risk. Power outages can disrupt communications, water supply systems, fuel distribution, medical equipment, and emergency response operations. Rural and mountainous areas may be particularly vulnerable due to long transmission lines and limited backup power.

Evacuation, Transportation & Access Constraints
Wildfire events can create significant evacuation challenges in Napa County due to limited road networks, steep terrain, and dispersed rural development. Road closures caused by fire, smoke, or falling debris may isolate communities and delay emergency response. Heavy traffic during evacuations can reduce the ability of residents to leave threatened areas and may hinder access for firefighting equipment.

Policies, Plans & Regulatory Environment
Wildfire risk management in Napa County is governed by a combination of federal, state, and local policies, plans, and regulatory programs that define fire protection responsibilities, establish development standards in fire-prone areas, and guide mitigation and preparedness activities. These authorities include the designation of State Responsibility Areas (SRA), Local Responsibility Areas (LRA), and Federal Responsibility Areas (FRA), as well as requirements contained in the Napa County General Plan, Safety Element, Community Wildfire Protection Plan (CWPP), Hazard Mitigation Plan, and California fire safety regulations. Together, these frameworks establish the regulatory environment for wildfire hazard reduction and emergency response in Napa County.

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Wildfire Protection Responsibility
Local, state, tribal, and federal organizations all have legal and financial responsibility for wildfire protection.

In many instances, two fire organizations have dual primary responsibility on the same parcel of land—one for wildfire protection and the other for structural fire protection. To address wildfire jurisdictional responsibilities, in 1981 the California State Legislature outlined various wildfire responsibilities, described below, in Public Resources Code § 4291.5 and Health and Safety Code § 13108.5:
▪ Federal Responsibility Areas (FRAs): FRAs are fire-prone wildland areas that are owned or managed by a federal agency such as the U.S. Forest Service, National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, or U.S. Department of Defense. Primary financial and rule-making jurisdictional authority rests with the federal land agency. In many instances, FRAs are interspersed with private land ownership or leases. Fire protection for developed private property is usually not the responsibility of the federal land management agency but of the relevant local government agency. Federal lands in and near Napa County include national forest and recreation lands in the surrounding mountain ranges and watershed areas. ▪ State Responsibility Areas (SRAs): SRAs are lands in California where the California Department of Forestry and Fire Protection (CAL FIRE) has legal and financial responsibility for wildfire protection and where CAL FIRE administers fire hazard classifications and building standard regulations. SRA boundaries are those adopted by the California Board of Forestry and are reviewed and updated every five years. Where SRAs contain structures or development, the responsibility for fire protection of those improvements falls to the relevant local government agencies. Las Posadas Demonstration State Forest (LPDSF) is a 796-acre mixed conifer forest located in Napa County, which also incorporates the most eastern stand of redwood trees in California. (Strategic Fire Plan Sonoma-LakeNapa Unit, 2017) SRAs are defined as lands that:
▪ Are unincorporated county areas;
▪ Not federally owned;
▪ Have wildland vegetation cover rather than agricultural or ornamental plants; or ▪ Have watershed, range, or forage values.
▪ Local Responsibility Areas (LRAs): LRAs include land in cities, cultivated agriculture lands, unincorporated non-flammable areas, and lands that do not meet the criteria for SRA or FRA. LRA fire protection is typically provided by city or county fire departments, fire protection districts, or by CAL FIRE under contract to local governments. LRAs may still include areas of flammable vegetation and WUI. In Napa County, LRAs include the cities of Napa, American Canyon, Calistoga, St. Helena, Yountville, and developed portions of the unincorporated valley floor served by local fire protection districts. Local agencies in LRAs enforce building and fire codes, maintain fire departments, and coordinate with CAL FIRE and other agencies during major wildfire events. Although LRAs may have lower wildfire hazard overall, many LRA areas are still located within or adjacent to the wildlandurban interface and remain vulnerable to wildfire impacts.

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Wildfire Protection Responsibilities in Napa County
California has adopted a number of statewide regulations intended to reduce wildfire risk, particularly in Fire Hazard Severity Zones and SRA’s. These regulations include building standards, defensible space requirements, and fire-safe development rules that apply to new construction and in some cases to existing structures.

State fire safety requirements include the California Fire Code, California Building Code Chapter 7A (materials and construction methods for exterior wildfire exposure), and Public Resources Code requirements for defensible space around structures in fire-prone areas. CAL FIRE also adopts Fire Hazard Severity Zone maps that must be used by local governments when planning development and enforcing fire safety regulations. These requirements are intended to reduce structure ignitability, improve firefighter access, and limit the spread of wildfire into developed areas.

The California State Hazard Mitigation Plan also identifies wildfire as one of the state’s most significant hazards and encourages local jurisdictions to integrate wildfire mitigation into land use planning, infrastructure design, vegetation management, and emergency preparedness programs.

Fire Protection Agencies in Napa County
Primary Agencies Volunteer / Supporting Agencies
▪ CAL FIRE Sonoma-Lake-Napa Unit (LNU) ▪ Rutherford Volunteer Fire ▪ Napa County Fire Department ▪ Pope Valley Volunteer Fire ▪ City of Napa Fire Department ▪ Gordon Valley Station
▪ American Canyon Fire Protection District ▪ Soda Canyon Station ▪ St. Helena Fire Department ▪ Spanish Flat / Lake Berryessa Stations ▪ Calistoga Fire Department ▪ Dry Creek–Lokoya Volunteer Fire ▪ Yountville Fire / Napa County Fire (contract service) ▪ Angwin / Deer Park Volunteer Fire ▪ Knights Valley Volunteer Fire
▪ Mountain Volunteer Fire Company
▪ Napa County Volunteer Fire Companies (various
stations)
Fire protection in Napa County is provided through a cooperative system involving municipal fire departments, special districts, volunteer fire companies, Napa County Fire, CAL FIRE, and federal agencies.

Responsibility for wildfire suppression varies depending on whether the incident occurs within FRA’s, SRA’s, or LRA’s. All agencies participate in the California mutual aid system and coordinate through the Napa County Emergency Operations Plan during large incidents.

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Federal Regulatory Environment
Healthy Forests Restoration Act
In 2003, the federal Healthy Forests Restoration Act (HFRA) appropriated specific funding to address five main sub-categories through the National Fire Plan (NFP): preparedness, suppression, reduction of hazardous fuels, burned-area rehabilitation, and state and local assistance to firefighters. Appropriations under this Act continue through the present. The spirit of the HFRA and NFP is reflected in the many CWPP developed in Napa County. The CWPP meets the requirements of HFRA by:

1. Identifying and prioritizing fuels reduction opportunities across the landscape;

2. Addressing structural ignitability;

3. Assessing community fire suppression capabilities; and

4. Collaborating with stakeholders.

State Regulatory Environment
Wildfire hazard mitigation in Napa County is strongly influenced by statewide regulations that apply to development, vegetation management, and fire protection in wildfire-prone areas. Because large portions of Napa County are located within SRA and High or Very High Fire Hazard Severity Zones, state fire safety laws play a significant role in land use planning, building design, and emergency access requirements.

These regulations are enforced by CAL FIRE, Napa County, and local fire agencies depending on jurisdiction.

Fire Hazard Severity Zones (FHSZ)
Fire Hazard Severity Zones (FHSZ) are geographic areas identified by the California Department of Forestry and Fire Protection (CAL FIRE) that reflect the potential for wildfire based on fuel loading, slope, fire weather, and other environmental conditions. These zones are classified as Moderate, High, or Very High Fire Hazard Severity Zones and are used by local governments to guide land use planning, building standards, defensible space requirements, and wildfire mitigation activities. The designation of FHSZ is required under California Government Code and is incorporated into local planning documents, including the Safety Element and hazard mitigation planning efforts.

To characterize wildfire risk at a landscape-scale, CAL FIRE has developed and maintains FHSZ. These zones are established using a statewide fire behavior modeling system that incorporates the following variables:
▪ Vegetation type and fuel load
▪ Topography (slope and aspect)
▪ Historical fire frequency and ignition density
▪ Weather conditions, including the number of days per year with extreme fire behavior potential ▪ Spot fire potential and ember cast range
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According to the most recent FHSZ data, large areas of unincorporated Napa County fall within “High” or “Very High” severity zones, as identified on Figure 3-5, particularly in and around Atlas Peak, Calistoga, Howell Mountain, and Pope Valley. These zones correspond closely with regions impacted by recent major wildfires, such as the 2020 LNU Lightning Complex and 2017 Tubbs Fire.

Development within High and Very High Fire Hazard Severity Zones presents additional challenges for emergency response, evacuation, and infrastructure protection. Many communities in these zones are served by limited road networks, narrow access routes, and overhead utilities, which can be damaged during wildfire events and restrict evacuation or firefighting access.

Fire Hazard Severity Zone mapping is also used to prioritize wildfire mitigation activities identified in the CWPP, including fuel reduction, shaded fuel breaks, evacuation route improvements, and community preparedness projects.

California Public Resources Code § 4290
California Public Resources Code § 4290 establishes minimum wildfire protection standards for the design and construction of structures, subdivisions, and developments in SRA. These regulations require that new development provide adequate emergency access, road width and grade standards, turnaround areas, signage and address identification, water supply for fire protection, and vegetation modification. The purpose of these requirements is to ensure that emergency responders can safely access structures during wildfire events and that development in fire-prone areas does not increase risk to life or property. Because much of Napa County’s unincorporated area lies within the SRA, these standards are applied to many rural and hillside developments.

California Public Resources Code § 4291
California Public Resources Code § 4291 requires property owners in fire-prone areas to maintain defensible space around structures, generally consisting of a minimum 100-foot buffer free of hazardous vegetation.

This requirement applies to structures located in mountainous areas, forested lands, grasslands, or other locations containing flammable vegetation. If a full 100-foot clearance cannot be achieved, vegetation must be reduced to the property line to the extent possible. Defensible space requirements are intended to reduce structure ignitability, improve firefighter safety, and slow the spread of wildfire. In Napa County, defensible space regulations are enforced in both SRA’s and many LRA’s where wildfire hazard is present.

California Building Standards Code
The California Building Standards Code (Title 24 of the California Code of Regulations) incorporates the California Fire Code and establishes construction standards intended to reduce wildfire risk in fire-prone areas. These standards include requirements for ignition-resistant construction materials, fire-resistant roofing, ember-resistant vents, address signage, fire apparatus access, road and driveway design, water supply, and clearance around structures. Building standards are updated on a regular cycle and are enforced by local jurisdictions through the building permit process. In areas designated as Fire Hazard Severity CAL OES SUBMITTAL - JUNE 2026
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Zones, additional requirements may apply to ensure that new development can be safely accessed by emergency responders and is less likely to ignite during a wildfire.

Local Regulatory Environment
CAL FIRE Sonoma-Lake-Napa Unit Strategic Fire Plan
The CAL FIRE Sonoma-Lake-Napa Unit (LNU) serves the counties of Sonoma, Lake, Napa, Solano, Yolo, and Colusa. The LNU Strategic Fire Plan is a product of the implementation of the 2018 State Fire Plan. The State Fire Plan provides an analysis procedure to assess fire fuel hazards and risks in order to design and implement mitigating activities. The LNU plan provides background information, fuels and fire data, proposed projects, and individual Battalion reports outlining mitigating activities commonly carried out each year. The plan is a local road map for the fire service and the public to create and maintain defensible landscapes to protect those assets vital to the state and its citizens.

The LNU Strategic Fire Plan outlines a comprehensive program designed to reduce total government costs and citizen losses from wildland fire in the unit. It also strives to assist the public with assistance and education to create fire adapted communities that can more safely withstand a wildland fire. To accomplish this, CAL FIRE continues to implement this plan to address such factors as:
▪ Firefighter and Public Safety: Prioritizing safety through improved access, defensible space compliance, and community evacuation planning.
▪ Hazardous Fuel Reduction: Targeted treatment of high-risk vegetative fuels, including shaded fuel breaks, prescribed burning, and mechanical thinning.
▪ Fire Suppression Preparedness: Enhancing capabilities for rapid and effective response, supported by pre-attack plans, infrastructure improvements, and real-time fire intelligence systems such as drones.
▪ Public Information and Education: Expanding outreach through programs such as Firewise USA® and Community Emergency Response Teams (CERT), with a focus on homeowner responsibility and structural hardening.
▪ Interagency Collaboration: Strengthening coordination among local fire districts, county emergency services, non-profits, and land management agencies to align priorities and pool resources for mitigation and response.

Napa County Community Wildfire Protection Plan
Napa County maintains a CWPP that provides a countywide framework for reducing wildfire risk through coordinated planning, fuel management, emergency preparedness, and public education. The CWPP was developed collaboratively with Napa County, CAL FIRE, local fire agencies, Fire Safe Councils, community organizations, and state and federal partners. The plan identifies wildfire hazards, evaluates areas of greatest risk, and prioritizes mitigation projects intended to reduce the likelihood of catastrophic wildfire and improve community resilience. The CWPP serves as a roadmap for wildfire mitigation and CAL OES SUBMITTAL - JUNE 2026
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preparedness at both the countywide and neighborhood level and is intended to align with federal, state, and local fire planning efforts.

The CWPP identifies several key categories of wildfire mitigation activities, including hazardous fuel reduction, community preparedness, protection of critical infrastructure, evacuation planning, and improvements to firefighting capability. Priority projects identified in the plan include vegetation management and shaded fuel breaks, roadside clearance, improvement of evacuation corridors, development of community fire protection plans, and programs to increase defensible space and structure hardening. These projects are often focused in areas located within High and Very High Fire Hazard Severity Zones and in the wildland-urban interface where the potential for structure loss is greatest.

The CWPP also supports coordination between local agencies and community organizations such as Fire Safe Councils and homeowner groups, recognizing that wildfire mitigation requires participation from both public agencies and private property owners. The plan encourages ongoing maintenance of defensible space, public outreach, and implementation of fuel reduction projects on both public and private lands.

Because wildfire risk extends across jurisdictional boundaries, the CWPP provides an important mechanism for coordinating mitigation activities among Napa County, municipalities, special districts, CAL FIRE, and federal land management agencies.

Napa County Emergency Operations Plan
Napa County maintains an Emergency Operations Plan (EOP) that establishes procedures for emergency response, coordination, and recovery during disasters, including wildfires. The EOP describes how Napa County and participating jurisdictions organize emergency operations using the National Incident Management System (NIMS), the Incident Command System (ICS), and California’s Standardized Emergency Management System (SEMS). These systems provide a structured framework for coordinating multiple agencies during large incidents that exceed the capability of a single department.

The EOP identifies the roles and responsibilities of County departments, local fire agencies, law enforcement, public works, public health, utilities, and partner organizations during emergencies. During wildfire incidents, the County may activate the Emergency Operations Center (EOC) to coordinate response activities, support evacuation operations, manage resource requests, and provide public information. The EOP also describes procedures for emergency notifications, evacuation warnings and orders, mutual aid coordination, and damage assessment following an incident.

Wildfire response in Napa County often involves multiple jurisdictions and agencies, particularly when fires occur in SRA’s, FRA’s, or near incorporated cities. The EOP establishes how local, state, and federal agencies coordinate through the operational area system to ensure that personnel, equipment, and support resources can be shared as needed. This coordination is critical during large wildfires, which may require regional or statewide mutual aid.

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measures to reduce future risk. Because wildfire can cause long-term impacts such as erosion, flooding, and infrastructure damage, the EOP supports integration between emergency response and hazard mitigation planning. Continued maintenance and periodic updates of the EOP help ensure that Napa County remains prepared to respond to large wildfire events and other natural hazards.

Napa County General Plan
The Napa County General Plan includes comprehensive goals, policies, and implementation measures aimed at minimizing wildfire risks and protecting residents, property, and natural resources from fire hazards. These provisions reflect a longstanding commitment to fire-adapted community planning and resilience in the WUI, but integration of wildfire risk considerations into the element is also a state requirement, particularly in SRAs and Very High FHSZs.

Under Senate Bill (SB) 1241 from 2012 and Government Code § 65302(g)(3), the county must include policies and implementation measures that address wildfire hazards in these high-risk areas. Guidance to support these updates is provided by the Governor’s Office of Land Use and Climate Innovation (LCI), which issues wildfire planning recommendations and California Environmental Quality Act (CEQA) checklist updates for local adoption. These requirements are further reinforced by AB 2140 and SB 379, which encourage integration of the local hazard mitigation plan and climate adaptation planning into the safety element.

Together, these statutory requirements shape Napa County’s wildfire policies within the General Plan, ensuring alignment with statewide mitigation, land use, and climate resilience goals.

The Napa County General Plan includes the following policies and goals pertaining to wildfire mitigation:
▪ Goal SAF-3 (Safety): It is the goal of Napa County to effectively manage forests and watersheds, and to protect homes and businesses from fire and wildfire and minimize potential losses of life and property.
• Policy SAF-14: The County will prepare a fire management plan and will continue, enhance, and implement programs seeking to reduce losses and costs associated with catastrophic fires.
• Policy SAF-15: The County shall coordinate with CAL FIRE and fire agencies in neighboring counties to plan for future fire prevention and suppression needs. • Policy SAF-16: Consistent with building and fire codes, development in high wildland fire hazard areas shall be designed to minimize hazards to life and property. o Action Item SAF-16.1: Develop site criteria and construction standards for development in high fire hazard areas and adopt standards to restrict urbanizing these areas as defined in Policy AG/LU-27 unless adequate fire services are provided. o Action Item SAF-16.2: Continue to implement “Napa Firewise” through information and education programs, community outreach, and fuel modification. • Policy SAF-17: The County supports the use of prescribed fuel management programs, including prescribed burns and brush clearing, for managing fire hazardous areas; to reduce CAL OES SUBMITTAL - JUNE 2026
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wildfire hazard, improve watershed capabilities, promote wildlife habitat diversification, and improve grazing.
▪ Policy ROS-10 (Trails): As appropriate, combine trails with fire breaks and design trails to facilitate access for control of wildfires. Utilize temporary and seasonal trail closures, and type and intensity of use restrictions as appropriate during periods of high wildfire risk and to protect sensitive species and habitats and avoid conflict with agricultural operations.

Building & Development Codes
Napa County and municipalities have adopted the California Building Standards Code, including Chapter 7A of the California Building Code (CBC) and Section R337 of the California Residential Code (CRC). As codified in Chapter 15.13 of the county’s code, local amendments to the state codes strengthen wildfire resilience in new construction and exterior remodels. These amendments are designed to protect life and property in the county’s extensive SRAs and WUI zones.

Title 7A of the California Building Code establishes minimum construction standards for buildings located in designated FHSZs and WUI areas. It aims to reduce wildfire ignition risk by requiring fire-resistant materials and designs for key exterior components, such as Class A roofing, ember-resistant vents, noncombustible siding, tempered windows, enclosed eaves, and ignition-resistant decking. These requirements apply to all new construction and substantial remodels after July 1, 2008, helping prevent structure-to-structure fire spread and improving building survivability during wildfire events.

The county’s refinements to building and fire codes include the following:
▪ Residential Fire Protection and Hazard Abatement: Napa County regulations require property owners to maintain a defensible space in accordance with the Defensible Space Guidelines. Failure to maintain defensible space, including the accumulation or storage of materials within established boundaries, is considered a nuisance and subject to County enforcement. (§8.36.60) ▪ Road and Street Standards: The Napa County Road and Street Standards are developed to be consistent with the State Responsibility Area (SRA) Fire Safe Regulations. (Cal. Code Regs. tit. 14, § 1270 et. seq.) The County is only one of four Counties to have road standards that meet these stringent requirements. (Napa County Climate Action Plan, 2018, p. 4.10) ▪ Telecommunications Facilities: Requires all radio, television and voice communication facilities providing service to government or the general public be designed to survive a natural disaster without interruption in operation, including structural modifications to reduce flammability.

Telecommunication facilities also shall be designed and operated in such a manner so as to minimize the risk of igniting a wildfire or intensifying one that otherwise occurs, including many related structural and operational requirements. (§18.119.080, §18.119.150) Past Events, Location & Extent
Napa County has experienced numerous wildfires over the past several decades Figure 3-3, including several large and destructive events that have caused damage to homes, infrastructure, and natural CAL OES SUBMITTAL - JUNE 2026
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resources. These events demonstrate the county’s vulnerability to fast-moving, wind-driven fires and highlight the importance of continued mitigation and preparedness efforts.

There are four major factors that influence where and when wildfire events occur in Napa County:
▪ Extreme vegetation diversity
▪ Diverse fire weather and fire behavior
▪ Dynamic fire history
▪ Complex land use patterns
Notable Wildfire Events
One of the most significant wildfire events affecting Napa County in recent years was the 2017 wildfire siege, which included multiple fires across Napa, Sonoma, and surrounding counties. These fires resulted in widespread evacuations, destruction of homes, and major impacts to transportation, utilities, and the regional economy. The event demonstrated the potential for wildfire to spread rapidly across jurisdictional boundaries and overwhelm local response resources, requiring regional and statewide mutual aid.

In 2020, the LNU Lightning Complex fires burned extensively across Napa County and neighboring counties following a series of lightning strikes during dry and windy conditions. These fires affected large areas of wildland and rural communities and required prolonged evacuation orders. The event highlighted the role of extreme weather, drought conditions, and heavy fuel loads in producing large wildfire incidents.

Napa County has also experienced numerous smaller wildfires that have caused localized damage, road closures, and evacuations. These incidents often occur in hillside areas, along transportation corridors, or in locations where vegetation, weather, and human activity combine to create ignition risk. In addition to direct fire damage, past wildfire events in Napa County have resulted in secondary impacts such as erosion, flooding, poor air quality, and power outages.

From 2015 to 2025, there were 10 wildfire events that burned over 1,000 acres in Napa County. These events are listed in Table 3-5 and displayed in Figure 3-3. The most recent events are described in detail below.

Table 3-5: Wildfires in Napa County 1,000 Acres or Greater, 2015-2025 Year Name Size in Acres
2015 Jerusalem Fire 25,118
2015 Wragg Fire 8,051
2015 Valley Fire 76,067
2016 Cold Fire 5,730
2017 Tubbs Fire 36,807
2017 Nuns Fire 56,556
2017 Atlas Fire 42,349
2018 Snell Fire 2,463
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2018 County Fire 89,836
2020 Glass Fire 67,484
2020 Hennessey Fire (part of LNU Lightening Complex) 305,352 2020 LNU Lightning Complex Fire 363,220
2025 Pickett Fire 6,820
Source: CAL FIRE
Butts & Wragg Fires(2014/2015)
The Butts Fire began on July 1, 2014, near Butts Canyon Road north of Pope Valley in northeastern Napa County and spread into Lake County. The fire burned approximately 4,300 acres, destroyed multiple structures, and forced evacuations in rural communities near Lake Berryessa and Pope Valley. The fire occurred during hot, dry summer conditions and spread rapidly through grass, brush, and timber fuels in steep terrain, requiring a large multi-agency response.

The Wragg Fire occurred in July 2015 in the eastern portion of Napa County near Lake Berryessa and spread into Solano and Yolo counties. The fire burned approximately 8,000 acres and forced evacuations in rural communities. Although structural damage was limited compared to larger fires, the Wragg Fire demonstrated how quickly fire can spread under hot, dry, and windy conditions in grassland and brush fuels. The fire also affected transportation corridors and required closure of major roadways, illustrating the vulnerability of evacuation routes in rural areas. (Strategic Fire Plan Sonoma-Lake-Napa Unit, 2017) Atlas, Tubbs & Nunn Fires(2017)
The October 2017 Northern California wildfires, also known as the Northern California firestorm, North Bay Fires, and Wine Country Fires, were a series of 250 wildfires that started burning across California. The fires broke out throughout Napa, Lake, Sonoma, Mendocino, Butte, and Solano Counties during severe fire weather conditions. (Nix, 2017) The Atlas Tubbs and Nunn Fires started on October 8th, 2017 in Napa County and together damaged over 1,110 structures and destroyed over 5,756. (Cal Fire, 2018). At the time, the Tubbs Fire was the most destructive wildfire in California history, burning parts of Napa, Sonoma, and Lake counties and inflicting its greatest losses in the City of Santa Rosa. Its destructiveness was surpassed only a year later by the Camp Fire of 2018.

LNU Lightning Complex Fire (2020)
The LNU Lightning Complex Fire began in August 2020 following a widespread lightning storm that ignited numerous fires across Northern California, including the Hennesey. The complex included multiple fires burning in Napa, Sonoma, Lake, Solano, and Yolo counties and became one of the largest wildfire events in California history. The LNU Lightning Complex burned approximately 363,220 acres, destroyed hundreds of structures, and required large-scale evacuations throughout the region. Portions of the fire burned in eastern CAL OES SUBMITTAL - JUNE 2026
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and northern Napa County, including areas near Lake Berryessa, Pope Valley, and other rural communities located in steep, heavily vegetated terrain.

The fire occurred during a period of extreme fire weather characterized by dry fuels, high temperatures, low humidity, and limited firefighting resources due to multiple simultaneous incidents across the state.

Lightning ignitions combined with drought-stressed vegetation allowed the fire to spread rapidly across wildland areas, including locations within SRA’s and High and Very High Fire Hazard Severity Zones. The incident required a prolonged multi-agency response involving local fire departments, CAL FIRE, federal agencies, and mutual-aid resources from throughout California.

The LNU Lightning Complex demonstrated the potential for a single weather event to ignite multiple large fires across the region at the same time, overwhelming local response capability and requiring regional coordination. The fire also caused secondary impacts including road closures, power outages, smoke impacts across the Napa Valley, and damage to natural resources and infrastructure. The event highlighted the importance of vegetation management, evacuation planning, defensible space, and interagency coordination in reducing wildfire risk in Napa County.

The 2020 lightning fire siege, including the LNU Lightning Complex, is considered one of the most significant wildfire events affecting Napa County in recent history and illustrates the continuing risk of large, wind-driven, or lightning-caused fires under extreme weather conditions.

Pickett Fire (2025)
The Pickett Fire occurred in August 2025 in Napa County near the community of Calistoga. Fueled by strong winds, dry vegetation, and extreme heat conditions, the fire spread to over 6,800 acres within the first 24 hours and destroyed or damaged several structures, disrupted livelihoods, and placed entire communities under severe stress before being contained. The burn area was within the 2020 Glass Fire burn scar, much of which had regrown with dense fuels. At its peak, more than 3,500 structures were threatened, prompting large-scale evacuations and road closures in the Napa Valley region.

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Figure 3-3: Historic Large Fires Map
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Frequency & Probability of Future Occurrences
Generally, Napa County faces a wildland fire threat each and every year. In 2010 Ernie Loveless, Chief of the CAL FIRE Napa-Lake-Sonoma Unit at the time, stated, “We must be honest with ourselves. Wildland fires are part of our history and will certainly be part of our future. Being prepared is critical.” The probability of wildfire occurring in Napa County is highly likely (100% annual probability).

The wildland fire risk in Napa County can be attributed to three factors: ignition sources and fuel loading.

Ignition sources, or fuels, in Napa County range include grass/oak woodland, 15- to 50-year-old chaparral, redwood forests, and timber over 50 years old. Critical concerns are when the chaparral dead-to-live ratio exceeds 50%, and live fuel moisture approaches 60% in late summer and early fall. (Strategic Fire Plan Sonoma-Lake-Napa Unit, 2017)
To better quantify wildfire frequency, Napa County uses the Mean Fire Return Interval (MFRI), a metric that estimates the average number of years between fires at a given location. As shown in Figure 3-4, the spatial distribution of MFRI indicates that large portions of Napa County, particularly across the valley floor and lower elevation areas, are characterized by shorter fire return intervals, generally ranging from approximately 0 to 12 years and 12 to 35 years. These areas are dominated by grasses and other fine, flashy fuels that cure seasonally and are highly receptive to ignition, resulting in more frequent fire occurrence.

In contrast, portions of the mountainous terrain in the Mayacamas and Vaca Mountains exhibit moderate to longer fire return intervals, generally ranging from 35 to 70 years or greater. These areas tend to support denser shrublands and forested vegetation types, where fuel accumulation occurs over longer periods, leading to less frequent but potentially higher-intensity wildfire events. Despite these longer intervals, these areas are capable of producing extreme fire behavior under severe weather conditions, including crown fire and long-range ember cast.

As climate change continues to influence wildfire dynamics through increased temperatures, prolonged drought, and more variable precipitation patterns, fire regimes across Napa County may shift. Short-interval fire areas dominated by grasses may experience even more frequent ignitions, while longer-interval forested areas may be increasingly susceptible to large, high-severity fires. These trends underscore the importance of fuel management strategies tailored to vegetation type, as well as coordinated planning to address both frequent, lower-intensity fires and less frequent but more destructive wildfire events.

Development in the wildland-urban interface also contributes to the probability of wildfire impacts. Homes, vineyards, and rural communities are often located near or within areas of dense vegetation, increasing the likelihood that fires will threaten structures and require evacuation. As development continues in fire-prone areas, the potential consequences of wildfire may increase even if the number of fires does not change. The CWPP emphasizes the importance of continued fuel reduction, defensible space, and fire-safe development standards to reduce the risk associated with future wildfire events.

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Figure 3-4: Mean Fire Return Interval (MFRI) Map
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Severity
Wildfire severity in Napa County ranges from small, quickly contained vegetation fires to large, highintensity wildfires capable of causing widespread damage to structures, infrastructure, agricultural resources, and natural areas. The severity of a wildfire event depends on a combination of fuel conditions, weather, topography, and the proximity of development to wildland vegetation. Because Napa County contains extensive grasslands, oak woodland, chaparrals, and forest fuels located in steep terrain and wildland-urban interface areas, wildfire events have the potential to become large, fast-moving, and difficult to control.

Areas located within High and Very High Fire Hazard Severity Zones, Figure 3-5, are most likely to experience severe wildfire behavior. These areas are generally located in the mountainous and foothill regions of the County, including the Mayacamas Mountains, the Vaca Range, and other upland areas where vegetation is dense and access may be limited. Fires burning in these areas can spread rapidly upslope, generate long flame lengths, and produce ember showers that ignite structures at a distance. Strong winds and low humidity can further increase fire intensity and allow fires to move quickly across large areas.

These conditions have contributed to several major wildfire events in Napa County, including the Atlas Fire, Nunn Fire, and the LNU Lightning Complex.

Wildfire severity is also influenced by the type and age of vegetation fuels. Grass fuels can support fastmoving fires that spread quickly across open areas, while chaparral and brush fuels can produce intense heat and long flame lengths. Forest and heavy timber fuels can support longer-duration fires that are difficult to extinguish and may continue burning for extended periods. Older vegetation and accumulated dead material can increase fire intensity and make suppression more difficult. During drought conditions, even normally moist fuels such as oak woodland and conifer forest may burn with high intensity.

Development in the wildland-urban interface increases the potential severity of wildfire events because structures, utilities, and transportation routes may be exposed to fire. Homes located in hillside and rural areas may be difficult to access during an emergency, and limited road networks can complicate evacuation and firefighting operations. Fires that reach developed areas may transition from wildland fire to structureto-structure fire, increasing the potential for large losses. In addition to direct fire damage, severe wildfire events in Napa County have caused evacuations, road closures, power outages, poor air quality, and damage to water supply and natural resources.

Weather conditions play a major role in determining wildfire severity. Periods of high temperature, low humidity, and strong winds can create extreme fire behavior and allow multiple fires to occur at the same time. Lightning storms, wind events, and prolonged drought have contributed to several of the most severe wildfire incidents affecting Napa County and Northern California. Climate change is expected to increase the likelihood of extreme fire weather conditions, which may lead to more severe wildfire events in the future.

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Figure 3-5: Fire Hazard Severity Zones
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Warning Time
Warning time for wildfire events in Napa County can vary significantly depending on the cause of ignition, weather conditions, and location of the fire. In some cases, wildfire may develop slowly and provide hours or days of warning, while in other situations fires can spread rapidly with little advance notice. Because Napa County contains large areas of grassland, chaparral, woodland, and forest fuels, and frequently experiences hot, dry, and windy conditions during fire season, warning time for wildfire is often limited, particularly during extreme fire weather events.

Wildfires caused by human activity, such as equipment use, vehicles, or powerline failures, may occur without warning and can spread quickly if fuels are dry. Lightning-caused fires may occur during summer thunderstorms and can ignite multiple fires across a wide area at the same time. Events such as the 2020 lightning storms that caused the LNU Lightning Complex demonstrated that numerous fires can start within a short period, reducing the time available for response and evacuation.

Wind-driven fires present the greatest challenge for warning and evacuation. Strong winds, low humidity, and steep terrain can allow fires to spread rapidly toward populated areas, sometimes during nighttime hours when residents are less likely to be aware of the danger. Past wildfire events in Napa County and the surrounding region have shown that fire conditions can change quickly, requiring evacuation warnings and orders to be issued with little notice.

Napa County uses multiple systems to provide warning and notification during wildfire incidents.

Emergency alerts may be issued through the County’s emergency notification systems, law enforcement and fire agency notifications, wireless emergency alerts, and public information releases. The EOP describes procedures for issuing evacuation warnings and orders, activating the Emergency Operations Center, and coordinating public information during large incidents. These systems are intended to provide residents with as much notice as possible; however, the unpredictable nature of wildfire means that warning time may still be limited in some situations.

Because wildfire can occur with little advance notice and may spread rapidly under certain conditions, the warning time for wildfire in Napa County is considered minimal to moderate, with the possibility of very little warning during extreme fire weather events.

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Wildfire Vulnerability Assessment
Napa County remains vulnerable to wildfire impacts despite ongoing efforts to reduce risk through planning, policies, and mitigation programs. This section evaluates wildfire vulnerability in relation to people, property, critical facilities, and infrastructure. Estimates of population exposure, parcel values, critical facilities, and lifeline infrastructure were developed by overlaying these asset inventories with CAL FIRE’s Fire Hazard Severity Zones (FHSZs). Figure 3-6 provides a summary of wildfire exposure across the county. It is important to note that this risk assessment evaluates exposure only; results are based on whether assets are located within mapped hazard zones and do not account for structural characteristics, defensible space, or site-specific mitigation measures.

Wildfire vulnerability in Napa County is shaped by the interaction of hazard exposure, land use patterns, and environmental conditions. As shown in Figure 3-6, much of the county, particularly in unincorporated and upland areas, is located within High and Very High Fire Hazard Severity Zones and includes extensive WUI areas where residential development, agricultural operations, and infrastructure are adjacent to or intermixed with flammable vegetation. Additionally, large portions of the county exhibit relatively short fire return intervals associated with grassland and light fuel types, increasing the likelihood of frequent ignitions, while forested and shrub-dominated areas may experience less frequent but more intense fire behavior. These conditions, combined with steep terrain, limited access in rural areas, and reliance on transportation and utility corridors that traverse fire-prone landscapes, contribute to elevated wildfire risk.

It is important to recognize that FHSZs have a regulatory basis; CAL FIRE is responsible for their designation under state law, and these zones trigger specific requirements in the California Building and Fire Codes.

However, FHSZs are designed primarily to represent hazards associated with wildland fuels and do not fully capture the complexity of wildfire risk, including ember-driven structure ignition and the potential for urban conflagration. Additionally, insurance providers often rely on proprietary risk models that incorporate higher-resolution data and localized conditions, which may result in different risk classifications at the parcel level. Understanding these distinctions is critical for effective risk communication, land use planning, and prioritization of mitigation actions to enhance Napa County’s resilience to future wildfire events.

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Figure 3-6: Exposure Summary – Napa County Wildfire Risk CAL OES SUBMITTAL - JUNE 2026
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3.3.1.7.1 Population
Wildfire exposure in the unincorporated areas of Napa County is substantial, with a majority of residents located within mapped Fire Hazard Severity Zones (FHSZ). As shown in Figure 3-7 and Table 3-6, almost 14,000 people (61% of the unincorporated population) reside within Moderate, High, or Very High hazard areas, demonstrating that wildfire a widespread hazard affecting a significant portion of the county’s population.

The highest concentration of exposed residents in the High and Very High FHSZs is located in the foothills and mountainous areas on either side and to the north of the Napa Valley, and up to Lake Berryessa, where more than 40% of the unincorporated county’s population resides.

High and Very High FHSZs often coincide with State and Federal Responsibility Areas (SRAs and FRAs).

These jurisdictional distinctions indicate additional layers of vulnerability, with SRAs and FRAs being rural by definition. Residents living in High or Very High FHSZs, particularly in or near FRAs, are generally among the most exposed populations and may also be more vulnerable due to access and service limitations. These communities are often located in rural or isolated areas with limited road access, longer emergency response times, and fewer nearby services. Evacuation in these areas can be challenging due to narrow roads, limited route options, and potential congestion during wildfire events.

Figure 3-7: Napa County Population Exposure to Wildfire Table 3-6: Napa County Population Exposure to Wildfire
Total Population
Unincorporated County 22,468
Wildfire Severity Zone (FHSZ) Population Count % of Total 5,512
3,576
3,044
0 1,000
2,000
3,000
4,000
5,000
6,000
Very High High Moderate
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Moderate 3,862 17.19%
LRA Moderate 2,824 12.57%
SRA Moderate 1,038 4.62%
High 4,157 18.50%
LRA High 582 2.59%
SRA High 3,575 15.91%
Very High 5,646 25.13%
LRA Very High 205 0.91%
SRA Very High 5,441 24.22%
Total 13,664 60.82%
Disproportionately Impacted Populations
Wildfire impacts in Napa County are not experienced equally across all populations. Certain groups may be disproportionately impacted due to social, economic, geographic, or physical vulnerabilities that limit their ability to prepare for, respond to, or recover from wildfire events.

Older adults, individuals with disabilities, and those with limited mobility may face additional challenges during evacuation, particularly in remote areas where assistance may be delayed. Similarly, low-income households may have fewer resources to implement mitigation measures such as defensible space, home hardening, or insurance coverage, increasing their vulnerability to wildfire impacts.

Napa County’s agricultural workforce, including farmworkers, may also be disproportionately affected by wildfire. Many agricultural workers are employed outdoors in areas that overlap with wildfire-prone landscapes and may be exposed to hazardous smoke conditions during fire events. In addition, language barriers, housing constraints, and transportation limitations may reduce access to emergency information and evacuation resources.

Climate change is expected to exacerbate existing disparities in wildfire vulnerability across Napa County by increasing the frequency, duration, and intensity of wildfire conditions. Rising temperatures, prolonged drought, and shifts in precipitation patterns contribute to drier vegetation and longer fire seasons, increasing the likelihood that communities, particularly those in High and Very High Fire Hazard Severity Zones, will experience repeated or more severe wildfire impacts. These conditions may place additional strain on vulnerable populations, including older adults, low-income households, and outdoor workers, who may have limited capacity to adapt to worsening conditions.

Increased wildfire activity also contributes to more frequent and prolonged smoke exposure, which can disproportionately affect individuals with pre-existing health conditions and those without access to adequate indoor air quality protections. As climate-driven wildfire risk increases, targeted mitigation, outreach, and resilience strategies will be essential to reduce disproportionate impacts and protect vulnerable populations.

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3.3.1.7.2 Property
Wildfire exposure to property in unincorporated Napa County is substantial. As shown in Table 3-7, approximately 63.5% of parcels are located within Moderate, High, or Very High Fire Hazard Severity Zones.

These areas represent over $10.4 billion in total property value, accounting for roughly half of all property value in the unincorporated county, underscoring the significant economic risk posed by wildfire.

The greatest concentration of exposure occurs in Very High and High Fire Hazard Severity Zones, which are largely located in State Responsibility Areas (SRAs). This reflects the pattern of development in hillside, rural, and wildland-urban interface areas, where wildfire risk is highest and access may be more limited.

Overall, the distribution of exposure closely follows the County’s topography, with high-value residential properties, agricultural lands, and rural development concentrated in fire-prone areas. In addition to potential structural losses, wildfire can damage infrastructure, disrupt access, and impact essential services, increasing the overall consequences of an event.

Vineyards and wineries are also exposed to wildfire risk. While vineyards may provide some fuel reduction benefits, associated facilities remain vulnerable to fire damage, smoke impacts, and operational disruption, which can result in broader economic impacts across the County.

Table 3-7: Napa County Property Exposure to Wildfire
Total Parcels Total Market Value
($)
Total Content
Value ($) Total Value ($)
Unincorporated County 13,668 $11,215,199,644 $9,248,691,039 $20,463,890,683 Wildfire Severity Zone
(FHSZ) Parcel Count % of Total Market Value Exposure ($) Content Value
Exposure ($) Total Exposure ($) % of Total
Moderate 2,026 14.82% $1,380,582,754 $958,926,985 $2,339,509,738 11% LRA Moderate 820 6.0% $622,654,135 $461,532,370 $1,084,186,505 5.3% SRA Moderate 1,206 8.8% $757,928,618 $497,394,615 $1,255,323,233 6.1% High 2,555 18.69% $1,729,602,921 $1,286,514,012 $3,016,116,933 15% LRA High 494 3.6% $339,656,856 $279,327,266 $618,984,121 3.0% SRA High 2,061 15.1% $1,389,946,065 $1,007,186,747 $2,397,132,812 11.7% Very High 4,096 29.97% $3,049,499,321 $2,011,762,587 $5,061,261,909 25% LRA Very High 493 3.6% $420,642,535 $344,341,570 $764,984,105 3.7% SRA Very High 3,603 26.4% $2,628,856,786 $1,667,421,017 $4,296,277,803 21.0% Total 10,703 63.5% $6,159,684,996 $4,257,203,585 $10,416,888,580 50.9% CAL OES SUBMITTAL - JUNE 2026
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3.3.1.7.3 Critical Facilities & Infrastructure
Wildfire poses a significant risk to critical facilities and infrastructure in unincorporated Napa County, particularly within High and Very High FHSZs. These facilities and lifelines are essential to emergency response, public safety, economic activity, and community lifelines, and their disruption before, during, or after a wildfire event can have cascading impacts across the county. As shown in Table 3-8 and Table 3-9 a significant number and miles of these assets are located within wildfire-prone areas.

Critical Facilities
Wildfire exposure to critical facilities in Napa County is significant, particularly in the highest hazard areas.

As shown in Table 3-8, over 200 critical facilities and high-consequence sites are located within Very High Fire Hazard Severity Zones, with additional concentrations in High and Moderate zones. This indicates that a large share of the County’s most important assets are located in areas most susceptible to severe wildfire behavior.

Key emergency response facilities—including fire stations, essential service facilities, and a hospital—are located within these high hazard areas. While this supports response capabilities, it also highlights that the same facilities needed during emergencies are themselves at risk, which could impact response effectiveness during major wildfire events.

Facilities that serve vulnerable populations or provide essential services—such as dams, shelters, mobile home parks, and community facilities—are also widely distributed in wildfire-prone areas. Damage to these sites could have disproportionate impacts on public safety and recovery, particularly for populations with limited resources or mobility.

Hazardous material sites present an additional concern. Dozens of these sites are located within wildfire hazard zones, creating the potential for secondary environmental and public health impacts if damaged during a fire event.

Transportation & Lifelines
Wildfire exposure to transportation and utility lifeline infrastructure is extensive across Napa County. As shown in Table 3-9, more than 600 miles of roadway and linear infrastructure are located within Very High Fire Hazard Severity Zones, with hundreds more miles in High and Moderate zones. These networks are critical for evacuation, emergency response, and daily economic activity.

A large portion of this infrastructure is located in rural and hillside areas, where road networks are often limited and access may be constrained. During wildfire events, these conditions can significantly complicate evacuations, delay emergency response, and isolate communities.

Utility systems, including electrical transmission lines, substations, water systems, and wastewater facilities, are also exposed to wildfire risk. Damage to these systems can result in widespread power outages, loss of communications, and disruption of critical services, creating cascading impacts across the County.

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Other key transportation assets, including bridges and regional connections, are also located within wildfire-prone areas. Damage to these assets can further limit access and prolong recovery efforts following a major event.

Table 3-8: Napa County Critical Facilities Exposure to Wildfire Critical Infrastructure - Wildfire Severity Zone
Infrastructure Type SRA Very
High
LRA Very
High
Very
High
Total
SRA
High
LRA
High
High
Total
SRA
Moderate
LRA
Moderate
Moderate
Total
Essential Facilities 10 - 10 4 - 4 2 1 3

EOC - - - - - - - - -
Fire Station 9 - 9 2 - 2 2 1 3
Hospital 1 - 1 - - - - - -
Law Enforcement - - - 2 - 2 - - -
High Potential Loss 81 1 82 34 34 68 17 4 21
Adult Residential Care - - - - - - - - -
Child Care Center 4 - 4 1 - 1 1 - 1
Church 6 - 6 3 - 3 3 - 3
Communication Tower - - - 6 - 6 4 1 5
Dam 25 - 25 17 - 17 5 - 5
Emergency Shelter 5 - 5 1 2 3 - 1 1
Farm Worker Housing - - - - 2 2 - 1 1
Historic Building 1 1 2 2 - 2 1 - 1
Library - - - 1 - 1 - - -
Mobile Home Park 5 - 5 - - - - - -
Res Elder Care Facility 5 - 5 - 1 1 - - -
Private School 3 - 3 - - - - - -
Public School - - - - - - - - -
Real Property Asset 27 - 27 3 29 32 3 1 4
Transportation and Lifeline 49 9 58 14 10 24 10 12 22
Airport 3 - 3 - - - 2 1 3
Bridge 22 9 31 12 8 20 5 9 14
Bus Stop - - - - - - - - -
HMMWC Asset - - - - - - - - -
HMMWC Dam - - - - - - - - -
HMMWC Hydrant - - - - - - - - -
NG Station - - - - - - 1 - 1
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Critical Infrastructure - Wildfire Severity Zone
Infrastructure Type SRA Very
High
LRA Very
High
Very
High
Total
SRA
High
LRA
High
High
Total
SRA
Moderate
LRA
Moderate
Moderate
Total
Power Plant - - - - 2 2 - - -
Substation 3 - 3 - - - 2 - 2
Wastewater Treatment Facility 10 - 10 - - - - - -
Water Supply Intake 1 - 1 - - - - - -
Water Tank 7 - 7 2 - 2 - 2 2
Water Treatment Facility 3 - 3 - - - - - -
Hazmat 47 7 54 24 15 39 13 22 35
Geotracker CleanupSite 1 - 1 - - - - - -
HWTS Active Facility 44 7 51 24 14 38 13 22 35
Landfill 2 - 2 - 1 1 - - -
Grand Total 187 17 204 76 59 135 42 39 81
*Real Property Assets are digitized insurance rolls for demonstrating value and ownership and may have overlapping points with other categories such as fire stations and law enforcement.

Table 3-9: Napa County Lifeline Infrastructure Exposure to Wildfire Lifelines (miles) - Wildfire Severity Zone
Infrastructure Type (Linear) SRA Very
High
LRA Very
High
Very High
Total SRA High LRA High
High
Total
SRA
Moderate
LRA
Moderate
Moderate
Total
Levee - - - - - - - - -
NG Pipeline - 0.00 0.00 2.61 0.00 2.61 6.84 4.96 11.80
Railroad - - - 0.07 - 0.07 3.01 0.05 3.06
Transmission Line 31.93 - 31.93 29.75 0.01 29.76 16.99 3.78 20.77 Street OSM 568.79 0.06 574.83 320.71 0.05 320.76 126.28 58.95 185.22 Highway & Interstate - - - - - - 2.67 - 2.67
Major Road 10.84 - 10.84 3.85 0.00 3.85 5.13 1.74 6.87
Residential Road 91.99 0.00 94.51 64.13 0.00 64.13 16.85 9.85 26.69 Road - Secondary 50.77 - 50.77 6.02 - 6.02 8.60 3.30 11.89 Road -Tertiary 60.80 0.00 63.45 33.78 - 33.78 7.32 0.88 8.20 Service Road 296.25 0.06 297.12 201.14 0.05 201.18 80.80 39.05 119.85 Unclassified 58.14 - 58.14 11.79 - 11.79 4.91 4.13 9.05 Grand Total 600.72 0.06 606.77 353.15 0.05 353.20 153.12 67.74 220.86 CAL OES SUBMITTAL - JUNE 2026
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Development Trends
Wildfire risk in Napa County is closely tied to historical and future development patterns, particularly the expansion of residential and agricultural uses into wildfire-prone areas. Development trends influence both the exposure of people and property to wildfire and the potential consequences of wildfire events, making land use a critical factor in long-term hazard vulnerability.

Past Development Patterns
Historically, Napa County has maintained a strong emphasis on agricultural preservation and limited urban expansion, with most growth directed toward incorporated cities and designated urbanized areas. However, significant development has occurred in rural and hillside areas, including residential estates, vineyardrelated structures, and agricultural facilities located within or adjacent to wildland vegetation. These areas often fall within SRA’s and High or Very High Fire Hazard Severity Zones, where wildfire hazard is elevated due to terrain, fuel conditions, and limited access.

Development in the wildland-urban interface (WUI) has increased the number of structures exposed to wildfire and introduced additional ignition sources such as vehicles, equipment, and utilities. Many of these developments are served by narrow roads, long driveways, and limited water supply infrastructure, which can complicate emergency response and evacuation. As a result, past development patterns have contributed to increased wildfire vulnerability in certain parts of the County, particularly in mountainous and rural areas.

Anticipated Future Growth
Future development in Napa County is expected to remain relatively constrained and focused within existing communities, consistent with General Plan policies that prioritize agricultural land protection and limit sprawl. However, some level of growth is anticipated in both incorporated areas and unincorporated communities, including infill development, redevelopment, and continued use of rural properties for residential and agricultural purposes.

Even with limited overall growth, incremental development in wildfire-prone areas may continue, particularly in hillside locations and rural parcels. This type of growth can increase the number of structures located within High and Very High Fire Hazard Severity Zones and may place additional demand on emergency services, evacuation routes, and infrastructure systems. In addition, ongoing investment in vineyards and winery facilities may expand the presence of high-value assets in wildfire-exposed areas.

Climate Change Impacts
Climate change is expected to significantly influence wildfire risk in Napa County by increasing the frequency, duration, and intensity of conditions that contribute to wildfire ignition and spread. Rising temperatures, prolonged drought, reduced soil moisture, and changes in precipitation patterns contribute to drier vegetation and longer fire seasons. These changes increase the likelihood of both frequent small fires CAL OES SUBMITTAL - JUNE 2026
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and large, high-severity wildfire events. The County’s mountainous terrain, extensive vegetation, and development in the wildland-urban interface further amplify these risks, particularly in areas already classified as High and Very High Fire Hazard Severity Zones.

Direct Impacts
Climate-driven wildfire conditions may lead to more frequent exposure of populations and structures to wildfire hazards. Direct impacts include increased risk of structure ignition, property loss, displacement of residents, and damage to critical infrastructure such as transportation networks, power systems, and water supply facilities. Higher temperatures and prolonged dry periods can also increase vegetation stress and fuel accumulation, allowing fires to burn more intensely and spread more rapidly. These impacts are expected to be most severe in rural and hillside areas where development is located near dense vegetation and emergency access may be limited.

Secondary & Compounding Hazards
Climate change also contributes to secondary hazards associated with wildfire. Post-fire environments are more susceptible to erosion, landslides, debris flows, and sedimentation, particularly during heavy rainfall events. Increased wildfire frequency may therefore lead to greater risk of slope instability and flooding in burn scar areas. In addition, wildfire events can cause power outages, infrastructure failure, and disruption to transportation systems, especially where utilities and roadways traverse wildfire-prone landscapes.

Extended wildfire seasons and more frequent fire events can also lead to cumulative impacts, where communities experience repeated disruptions over time. These compounding effects can strain emergency response systems, delay recovery, and increase long-term vulnerability for both people and infrastructure.

Public Health Impacts
Wildfire smoke is one of the most significant public health concerns associated with climate-driven wildfire. Smoke contains fine particulate matter (PM2.5) and other pollutants that can cause respiratory and cardiovascular illness. As wildfire frequency increases, residents may experience more frequent and prolonged periods of poor air quality.

Sensitive populations, including older adults, children, individuals with pre-existing health conditions, and outdoor workers, are particularly vulnerable to smoke exposure. Agricultural workers, who are a key part of Napa County’s workforce, may face elevated risk due to prolonged outdoor exposure during wildfire season.

Repeated smoke events can also contribute to chronic health issues and increased healthcare demand.

Social & Economic Impacts
Climate change may also exacerbate existing social and economic vulnerabilities. Wildfire events can lead to temporary or long-term displacement, loss of housing, and increased insurance costs or reduced CAL OES SUBMITTAL - JUNE 2026
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insurance availability in high-risk areas. These impacts may disproportionately affect low-income households, renters, and residents in rural communities who have fewer resources to recover from disaster.

Disruptions to the County’s agricultural economy, including vineyards and wineries, may also have broader economic consequences. Smoke exposure can affect crop quality, and wildfire events can disrupt tourism, employment, and local businesses. These impacts may disproportionately affect workers in agriculture, hospitality, and service industries.

Wildfire Hazard Problem Statements
As part of the mitigation action identification process, the Napa County Planning Team developed areas of concern (i.e., problem statements) that summarize the county’s most pressing wildfire-related vulnerabilities and challenges. The problem statements were developed based on the updated risk assessment and vulnerability analysis contained herein, as well as the team’s local knowledge and experience and community input.

The problem statements address a broad spectrum of concerns, from direct impacts on residents and vulnerable populations to threats to critical infrastructure, essential facilities, economic assets, natural resources, and long-term recovery. They also recognize systemic barriers to effective mitigation, such as fragmented land ownership and post-fire hazards.

These problem statements are not intended to be all-encompassing or to describe each and every issue associated with wildfire. Instead, they highlight the most urgent concerns that can be addressed within the scope of this MJHMP. Each statement will be linked to at least one mitigation action, ensuring that identified needs are met with specific, measurable, and equitable solutions. Table 3-10 presents the wildfire hazard problem statements for Napa County, along with their associated areas of concern and reference numbers for cross-linking to the mitigation actions in Table 4-4.

Table 3-10: Napa County Wildfire Hazard Problem Statements Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-CC-NCo-14 Wildfire Threat Napa County Increasing average temperatures and changes in precipitation patterns associated with
climate change are expected to increase the
risk of wildfire in the County by approximately
10 to 20% by the end of the century.
ma-AH-NCo-5,
ma-SW-NCo-83,
ma-CC-NCo-15,
ma-AG-NCo-1,
ma-WF-NCo-90,
ma-WF-NCo-96,
ma-WF-NCo-94,
ma-WF-NCo-95
ps-WF-NCo-153 Wildfire Threat Napa County Angwin's primary evacuation and emergency access route, Howell Mountain Road, is narrow
and winding with only two secondary routes,
creating major evacuation and response
challenges during wildfire event.
ma-WF-NCo-102,
ma-WF-NCo-94
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-WF-NCo-154 Wildfire Victim Napa County There are approximately 384 facilities and 991 miles of critical infrastructure located in High
or Very High FHSZs, including key systems
like power, water, bridges, and dams as well as
high potential loss facilities like childcare
centers and fire stations, which could be
severely impacted or destroyed during a
wildfire.
ma-WF-NCo-97,
ma-AH-NCo-4,
ma-WF-NCo-96,
ma-WF-NCo-94,
ma-WF-NCo-95
ps-WF-NCo-155 Wildfire Threat Napa County Human activities, including equipment use, debris burning, and arson are the leading
cause of wildfires in the Sonoma-Lake-Napa
Unit, requiring enhanced prevention,
enforcement, and public education.
ma-WF-NCo-95,
ma-WF-NCo-101,
ma-AH-NCo-6,
ma-DR-NCo-26,
ma-WF-NCo-90
ps-WF-NCo-156 Wildfire Threat Napa County Many of the rural areas of the county, especially in the foothills and mountains, are
heavily vegetated and in need of fuel
management and access improvements to
reduce wildfire risks to people, property,
infrastructure, and the environment.
ma-WF-NCo-102,
ma-AH-NCo-6,
ma-WF-NCo-90,
ma-WF-NCo-96,
ma-WF-NCo-95
ps-WF-NCo164Wildfire Victim Napa County Thousands of county residents (approximately 7% of the total population) live in High or Very
High FHSZs and are at risk of injury, death,
displacement, and property loss.
ma-WF-NCo-90,
ma-WF-NCo-91,
ma-WF-NCo-92,
ma-CC-NCo-15,
ma-WF-NCo-96,
ma-WF-NCo-95
ps-WF-NCo-172 Wildfire Threat Napa County Steep slopes, limited fire suppression access, inadequate water supply, and flammable
vegetation create major wildfire risks for
residential development in hilly areas of
unincorporated Napa County.
ma-WF-NCo-91,
ma-WF-NCo-92,
ma-WF-NCo-101,
ma-WF-NCo-90,
ma-WF-NCo-96,
ma-WF-NCo-95
ps-WF-NCo-181 Wildfire Impact Napa County Firesafe Councils need greater financial capacity to support coordination, education,
and outreach in unincorporated areas.
ma-WF-NCo-93,
ma-WF-NCo-95,
ma-WF-NCo-90,
ma-WF-NCo-96
ps-WF-NCo-182 Wildfire Threat Napa County BAAQMD regulations limit the use of prescribed burns, making it more difficult to
reduce hazardous fuels in fire-prone areas of
unincorporated Napa County.
ma-WF-NCo-96
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3.3.2 Flood Hazard Profile
Flooding is one of the three primary natural hazards in California, along with earthquakes and wildfires, and statewide it represents the second most destructive source of hazard vulnerability and risk. (CalOES, 2018) Flooding is a priority hazard for Napa County due to its exposure to both riverine and coastal flooding, steep watershed conditions that produce rapid runoff, and the presence of populated areas and critical infrastructure in floodplains.

A floodplain is the low-lying land adjacent to rivers, creeks, and other watercourses that becomes inundated during flood events. In Napa County, floodplains range from broad alluvial valleys associated with the Napa River system to narrower, confined corridors along tributaries such as Napa Creek, Salvador Creek, and Tulucay Creek, as identified in the countywide Flood Insurance Study . These areas function as dynamic natural systems that provide important benefits, including temporary storage of floodwaters, sediment transport, groundwater recharge, and water quality improvement, all of which help reduce downstream flood risk. Local watershed management programs further support these functions through ongoing channel maintenance, restoration, and flood management activities . However, when rivers are separated from their floodplains by levees, channel modifications, or development, these natural processes are diminished, often resulting in increased flood depths and velocities, greater downstream impacts, and reduced ecological function.

In Napa County, flooding is most pronounced along the Napa River corridor, where broad valley topography, historical floodplain development, and converging tributaries contribute to recurring overbank flooding during major storm events. Unincorporated areas are particularly vulnerable, as many rural properties, agricultural lands, and transportation corridors are located within or adjacent to natural floodplains and rely on a combination of limited structural protection and natural drainage systems. In these areas, flooding is often driven by a combination of watershed-scale runoff, localized drainage constraints, and sedimentation that reduces channel capacity over time. Floodplains in these settings may extend across wide valley floors or follow narrower tributary channels, functioning as natural storage and conveyance areas that help moderate peak flows. However, land use patterns, aging infrastructure, and modifications to natural channels can constrain these functions, increasing the frequency and extent of flooding impacts in unincorporated Napa County, particularly along smaller creeks and agricultural drainage networks connected to the Napa River system.

Definitions & Hazard Area Designations
Flood hazards are mapped and regulated using specific terms and categories established by the Federal Emergency Management Agency (FEMA) through its Flood Insurance Rate Maps (FIRMs) and Flood Insurance Studies (FIS). Understanding these definitions is essential for interpreting flood hazard maps, administering floodplain management regulations, and guiding development in at-risk areas. The terms described in Table 3-11 apply to flood hazard mapping and floodplain management in Napa County and are consistent with FEMA standards, including inland and coastal hazard area designations.

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Table 3-11: Flood Hazard Terms
Term Description
100-YR / 1% Annual
Chance Floodplain
The boundaries of the 100-year floodplain coincide with the base flood and an annual flood risk of 1%, consisting of both the regulatory floodway and the flood fringe. These areas are identified as various A Zones on FIRMs, depending on the risk and level of study conducted. 500-YR / 0.2% Annual
Chance Floodplain
The boundaries of the 500-year floodplain encompass the 100-year floodplain and coincide with an annual risk of 0.2%. The 500-year floodplain is advisory only for NFIP purposes.

Base Flood A flood having a 1% chance of being equaled or exceeded in any given year. This is the regulatory standard also referred to as the "100-year flood." The base flood is the national standard used by the NFIP and all federal agencies for the purposes of requiring the purchase of flood insurance and regulating new development.

Base Flood Elevation
(BFE)
The elevation of surface water resulting from the base flood that has a 1% chance of equaling or exceeding that level in any given year. BFEs are shown on Flood Insurance Rate Maps (FIRM) for various flood zones where detailed studies have been conducted (e.g., Zone AE and V Zones).

Best Available Map
(BAM)
The California Department of Water Resources (DWR) provides Best Available Maps displaying 100-, 200-, and 500-year floodplains across the state as supplemental information to FIRMs.

Coastal A Zone (CAZ) Coastal A Zones are within the SFHA, landward of a V Zone or along the open coast, where wave heights are between 1.5 and 3 feet during the base flood event. Structures in CAZs are subject to design and construction standards similar to V Zones.

Coastal High-Hazard
Area (V Zones)
V Zones are areas along open coasts subject to high-velocity wave action from storms or other triggering events. These zones require elevated construction methods and other protective measures that can withstand the additional forces of waves.

Flood Fringe This is the remaining portion of the 100-year floodplain, excluding the floodway. This zone can be obstructed or developed if certain criteria are met.

Flood Insurance Rate
Map (FIRM)
The official map of a community on which FEMA has delineated the SFHAs, BFEs, and the insurance risk premium zones applicable to a particular community.

Flood Insurance Study
(FIS)
A compilation and presentation of flood risk data accompanying the FIRMs for specific watercourses, lakes, and coastal flood hazard areas within a community. When a flood study is completed for the NFIP, the information and maps are assembled into an FIS report, which contains detailed flood elevation data in flood profiles and tables.

Floodway The channel of a river or other watercourse and the adjacent land areas, where the highest velocities and damage potential are present during a flood, that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. Communities must regulate development in these floodways to ensure that there are no increases in upstream flood elevations.

Limit of Moderate
Wave Action (LiMWA)
The Limit of Moderate Wave Action is a line shown on FIRMs that marks the inland limit of wave heights between 1.5 and 3 feet during the base flood event. Areas seaward of the LiMWA face higher risks from wave damage and must meet applicable construction standards.

Special Flood Hazard
Area (SFHA)
An area having special flood, mudflow, or flood-related erosion hazards and shown on a Flood Insurance Rate Map (FIRM), including all A and V Zones. The SFHA is the area where the National Flood Insurance Program's (NFIP) floodplain management regulations must be enforced and where the mandatory purchase of flood insurance may apply.

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Floodplain Ecosystems
Floodplains are critical natural systems that support diverse and highly productive ecosystems. These areas often host an abundance of plant and animal species, with densities many times greater than those found along the river channel alone. Periodic flooding replenishes soils with nutrients from decomposed organic material, triggering rapid growth in plants and microorganisms. This productivity attracts a wide range of wildlife, including migratory birds and opportunistic feeders, and sustains agricultural uses due to the fertility of the soil. Vegetation in floodplains and riparian areas is typically adapted to disturbance, with species that are fast-growing and tolerant of saturated soils and root disruption.

Undisturbed or restored floodplains provide important benefits to both human communities and natural environments. When maintained in their natural state, floodplains:
▪ Slow the rate at which runoff enters streams, reducing peak flows and moderating flood impacts. ▪ Improve water quality by trapping sediment and filtering pollutants before they reach waterways. ▪ Recharge groundwater aquifers by allowing water to infiltrate into the soil. ▪ Provide habitat for a wide variety of plant and animal species, including sensitive and threatened species.

However, like elsewhere in California, floodplains in Napa County have been heavily affected by human development. Historically, they have been attractive locations for settlement due to proximity to water, fertile farmland, accessible transportation routes, and flat terrain suitable for building. Urbanization, agricultural expansion, and infrastructure construction can disrupt natural floodplain functions, altering drainage patterns, increasing downstream velocities, and reducing the capacity of channels to safely convey floodwaters. These changes can elevate flood risk both locally and downstream.

Responsible land use planning and floodplain management can allow human activity to coexist with floodplain ecosystems. Development within these areas must incorporate design measures that preserve or restore floodplain functions to the greatest extent feasible.

In Napa County, many areas that provide natural floodplain benefits are designated as wetlands, riparian corridors, open space, or protected lands under the county’s General Plan and other regulatory measures.

These areas are typically shielded from intensive development and, when development is proposed, must comply with the county’s floodplain management regulations and the NFIP. Maintaining these lands in their current condition helps reduce future flood losses while supporting ecosystem health and resilience.

An analysis of areas providing natural floodplain functions in Napa County (Figure 3-8) illustrates that a substantial portion of the Napa River corridor—particularly in unincorporated areas—is already serving as active floodplain, including wetlands, federally managed lands, and vacant or undeveloped parcels. These areas, concentrated along the mainstem Napa River and its tributaries, play a critical role in attenuating flood flows by allowing water to spread across the landscape, thereby reducing peak discharges and downstream impacts. The map also highlights that many of these lands remain free of structural development, which preserves their ability to function as natural storage and conveyance areas during flood CAL OES SUBMITTAL - JUNE 2026
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events. However, it also underscores the spatial relationship between these functional floodplains and adjacent agricultural and rural lands, where encroachment or modification could diminish these benefits over time. Protecting and enhancing these identified areas represents a key opportunity for Napa County to maintain natural floodplain functions while minimizing long-term flood risk to unincorporated communities and infrastructure.

Figure 3-8: Areas Providing Natural Floodplain Functions in Napa County Secondary & Compounding Hazards
Flooding in Napa County often triggers or contributes to other hazards that can significantly increase the overall impact of an event. One of the most persistent is bank erosion, which can, in some cases, cause more lasting damage than the initial flood. Erosion of riverbanks and stream channels can undermine infrastructure, damage private property, and alter flow patterns, increasing vulnerability to future floods.

These secondary and compounding hazards are briefly discussed in this section in relation to flood; some are further discussed in other profiles, including wildfire burn scars (Section 3.3.1), heavy rain (Section 3.3.7), slope failure (Section 3.3.5), and climate change (Section 3.3.9).

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Slope Failure
Flooding can lead to landslides, mudslides, debris flows, and other types of slope failure, particularly in steep mountain watersheds where saturated soils lose cohesion and fail. These secondary events can block roadways, isolate communities, and further disrupt drainage systems, sometimes creating temporary dams from accumulated debris that can release suddenly and worsen downstream flooding.

Wildfire Burn Scars
The presence of wildfire burn scars can significantly increase flood risk. Loss of vegetation and soil damage from the intense heat produced by severe wildfires reduces the land’s ability to absorb rainfall, increasing both the speed and volume of runoff. The combination of rapid runoff and elevated sediment loads can cause severe erosion, degrade water quality, and increase slope failure hazards like debris flows in downstream communities.

Climate Change, Sea-Level Rise & Atmospheric Rivers
Climate change is expected to increase flood risk in Napa County by intensifying storm events, altering watershed response, and contributing to rising water levels in downstream tidal areas. While much of the County’s flood-prone land remains undeveloped, particularly within the Napa River corridor, certain developed areas and critical infrastructure are increasingly exposed and should be incorporated into longterm planning efforts. Sea-level rise primarily affects the southern portion of the County near the Napa River estuary and San Pablo Bay, where higher base water levels can reduce drainage capacity and exacerbate riverine flooding during storm events. As illustrated in climate change profile in this d, exposure to sea-level rise is concentrated in low-lying areas near American Canyon and downstream of the City of Napa, with relatively limited impacts to the overall population but notable exposure to parcels, infrastructure, and key facilities.

Climate-driven changes are also expected to increase the frequency and intensity of atmospheric river events, which are a primary driver of major flooding in Napa County. These events can produce prolonged, high-intensity rainfall across the watershed, leading to rapid runoff and elevated flows along the Napa River and its tributaries. In unincorporated areas, where drainage infrastructure is less extensive and land use is more dispersed, these conditions can result in widespread overbank flooding, road overtopping, and isolation of rural communities. Additionally, sediment transport and channel capacity limitations may further exacerbate flood conditions over time.

Critical infrastructure located within low-lying and flood-prone areas—including transportation corridors, wastewater facilities, and utilities—may face increasing risk under combined storm and sea-level rise scenarios. Portions of the Napa River corridor, including areas near downtown Napa and extending south toward American Canyon, are particularly susceptible to these compounded hazards. These trends highlight the importance of incorporating climate-informed flood projections into hazard mitigation, land CAL OES SUBMITTAL - JUNE 2026
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use planning, and capital improvement strategies to reduce long-term vulnerability and enhance resilience throughout Napa County.

Hazardous Materials and Sewage Release
Hazardous materials and sewage releases are another secondary concern during a flood event. When floodwaters overtop or breach containment systems, above ground storage tanks, or other facilities storing chemicals, fuels, or other hazardous substances, contaminants or sewage can enter storm drains, streams, or the ocean. These releases create environmental hazards to people and natural ecosystems and further complicate cleanup and recovery efforts.

Subhazard: Levee Failure
Levee failure is a recognized subhazard associated with riverine flooding in Napa County, particularly along the Napa River corridor and in downstream areas influenced by tidal conditions near San Pablo Bay. Levees and flood control structures in Napa County are primarily non-federal systems designed to reduce flood risk by confining flows within constructed channels and protecting adjacent developed and agricultural lands.

While these systems provide a level of protection, they do not eliminate flood risk, and failure can occur due to overtopping during extreme storm events, erosion of embankments, seepage through or beneath levees, or structural instability caused by prolonged saturation or poor foundation conditions.

In Napa County, levee and flood management infrastructure is most prominent along the Napa River and in the southern portion of the county, including areas near the City of Napa and American Canyon. These systems are part of a broader flood management approach that includes both structural improvements and restoration-based strategies implemented through the Napa County Flood Control and Water Conservation District. However, many levee segments are not designed to withstand extreme flood events beyond their intended level of protection, and some areas rely on a combination of levees, bypass channels, and natural floodplain function rather than continuous structural barriers.

Failure of levees in Napa County could result in rapid inundation of adjacent lands, particularly in low-lying unincorporated areas and agricultural zones where floodwaters can spread quickly across wide valley floors. Compared to gradual overbank flooding, levee breaches may produce higher velocities and deeper flooding with limited warning time, increasing the potential for damage to structures, disruption of transportation corridors, impacts to agricultural production, and risks to public safety. Areas downstream, where floodwaters interact with tidal influences, may experience prolonged inundation due to reduced drainage capacity.

Factors contributing to levee failure in Napa County include extreme precipitation events associated with atmospheric rivers, sediment accumulation that reduces channel capacity, deferred maintenance, vegetation or animal activity that weakens embankments, and seismic activity that can compromise structural integrity. Additionally, climate change may increase the likelihood of conditions that stress levee systems, including higher peak flows and coincident high tide conditions in downstream areas.

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Mitigation strategies focus on continued inspection and maintenance of levee systems, targeted structural improvements, integration of nature-based flood management approaches, and emergency preparedness planning for areas located behind levees. Napa County’s approach emphasizes a balance between structural protection and restoration of natural floodplain processes to reduce long-term risk and enhance system resilience.

Policies, Plans & Regulatory Environment
Federal Regulatory Environment
National Flood Insurance Program (NFIP)
The National Flood Insurance Program (NFIP) makes federally backed flood insurance available to homeowners, renters, and business owners in participating communities. In most participating communities, FEMA has prepared a detailed Flood Insurance Study (FIS). This study presents water surface elevations for floods of various magnitudes, including the 1% annual chance or base flood (also known as the 100-year flood) and the 0.2% annual chance flood (or 500-year flood).

Base Flood Elevations (BFE) and the boundaries of the 100- and 500-year floodplains are shown on Flood Insurance Rate Maps (FIRMs). These maps are the primary tools for identifying the extent and location of flood hazards. FIRMs also designate the regulatory floodway which is the channel of the river or stream and the adjacent land that must remain free from obstruction so that the base flood can be conveyed downstream. FIRMs represent the most detailed and consistent data source available and, in many communities, they define the minimum regulatory area for floodplain management.

The most recent county-wide FIRM for Napa County became effective on August 3rd 2016. This update produced a digital flood insurance rate map (DFIRM) that allows for easier integration with geographic information systems (GIS) and more precise identification of flood risk areas.

Communities that participate in the NFIP must, at a minimum, regulate development in flood hazard areas according to NFIP criteria. Before issuing a permit to build in a mapped floodplain, participating jurisdictions must ensure that:
▪ New buildings and substantially improved structures are elevated or otherwise protected to resist damage from the base flood.
▪ New floodplain development does not increase flood hazards or cause additional damage to other properties.
▪ Floodplain development incorporates reasonable and prudent measures to reduce impacts on natural floodplain functions and ecosystems, including threatened and endangered salmonid species.

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for reduced flood insurance rates because they were constructed under floodplain management regulations intended to reduce flood damage. Pre-FIRM buildings are often more vulnerable to flooding because they were built before modern construction standards and land use regulations were adopted.

Community Rating System (CRS)
FEMA’s Community Rating System (CRS) is a voluntary program within the NFIP that encourages floodplain management activities that exceed the minimum NFIP requirements. Flood insurance premiums are discounted to reflect the reduced flood risk resulting from community actions that meet the three goals of the CRS: 1) reduce flood losses, 2) facilitate accurate insurance rating, and 3) promote awareness of flood insurance.

For participating communities, flood insurance premium rates are discounted in increments of 5% according to the community’s classification on a scale from ten to one. On this scale, a Class 1 community would receive a 45% premium discount, and a Class 9 community would receive a 5% discount. Class 10 communities are those that do not participate in the CRS and they receive no discount. The CRS classes for local communities are based on 18 creditable activities related to public information, mapping and regulations, flood damage reduction, and flood preparedness.

CRS activities can help to save lives and reduce property damage. Communities participating in the CRS represent a significant portion of the nation’s flood risk; over 66% of the NFIP’s policy base are communities in the CRS. Communities receiving premium discounts through the CRS range from small to large and represent a broad mixture of flood risks, including coastal and riverine.

Napa County NFIP & CRS Participation
Napa County and all five incorporated municipalities—Napa, American Canyon, St. Helena, Calistoga, and Yountville—participate in the NFIP. Each jurisdiction is currently in good standing with NFIP requirements. (Refer to the municipal annexes for jurisdiction-specific details). Compliance is monitored by FEMA Region 9 and by the California Department of Water Resources (DWR) under contract with FEMA.

Maintaining NFIP compliance is a key element of the county’s overall flood risk management strategy. All participating jurisdictions have identified ongoing initiatives to maintain their standing in the NFIP and to continue reducing flood risks.

The Planning Division within the County plays a central role in Napa County’s flood hazard mitigation program. Its responsibilities include administering regulatory permitting for development in flood-prone areas, ensuring compliance with the NFIP, and managing participation in the CRS program. These functions help guide safe development, maintain eligibility for flood insurance, and provide residents with premium discounts through the CRS program. Together, these activities form a major component of the County’s overall strategy to reduce long-term flood risk while supporting resilient growth.

Table 3-12 lists NFIP and CRS information for Napa County, which shows flood insurance claims paid since 1986.

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Table 3-12: Napa County NFIP Status and Flood Insurance Statistics Napa County NFIP Status and Flood Insurance Statistics
NFIP Status Participating Since 1980
Community Identification (CID) 060205
CRS Class (Entry Date) Class 7 (May 2018)
Policies in Force (Total Coverage) 377 Policies ($109,741,000 in Coverage) Policies Inside SFHA / Outside SFHA 287 Inside / 99 Outside Policies in Coastal Zones (Total Coverage) N/A
Total Claims (Total Paid) 383 Claims ($7,305,119 Paid)
Repetitive Loss (RL) / Severe Repetitive Loss (SRL) Properties 33 RL /6 SRL (unmitigated insured) Repetitive Loss Payments $2,578,028 for Buildings / $718,251 for Contents Note: The number of policies is by property and does not count policies for individual buildings. The Privacy Act of 1974 (5 USC 522a) restricts the release of certain types of data to the public. Flood insurance policy and claims data is included in the list of restricted information. FEMA can only release such data to state and local governments, and only if the data is used for floodplain management, mitigation, or research purposes. Therefore, this plan does not identify the repetitive loss properties or include claims data for any individual property.

U.S. Army Corps of Engineers (USACE)
The U.S. Army Corps of Engineers (USACE) plays a key role in flood risk management in Napa County through planning, engineering, and implementation of large-scale, multi-benefit flood control projects in partnership with local sponsors, most notably the Napa County Flood Control and Water Conservation District. USACE’s involvement in Napa County has focused primarily on the Napa River Flood Risk Management Project, a congressionally authorized effort that integrates flood protection, ecosystem restoration, and community enhancement. This project includes a combination of levees, floodwalls, bypass channels, and restored floodplain areas designed to reduce flood risk while maintaining and enhancing natural river functions.

Key USACE responsibilities and activities in Napa County include:
▪ Napa River Flood Risk Management Project: USACE, in partnership with local agencies, has supported the design and implementation of improvements along the Napa River through the City of Napa and downstream areas. The project emphasizes a “living river” approach, combining structural flood protection measures with restored wetlands and floodplain expansion to provide flood risk reduction while improving habitat and water quality.
▪ Technical Assistance: USACE provides hydrologic and hydraulic modeling, sediment transport analysis, and engineering support for flood management and watershed planning efforts. These services are delivered through programs such as Floodplain Management Services (FPMS) and Planning Assistance to States (PAS), helping local agencies evaluate flood risk and develop mitigation strategies.

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▪ Ecosystem Restoration: In Napa County, USACE has supported projects that integrate habitat restoration with flood risk reduction, particularly along the Napa River and in downstream tidal areas. These efforts enhance riparian corridors, wetlands, and estuarine systems while also improving flood storage capacity and system resilience.
▪ Emergency Operations: During major flood events, USACE may provide technical and operational support to local jurisdictions, including flood fight assistance and post-event recovery support for flood control infrastructure. This includes coordination with local agencies to assess damages and implement emergency measures to reduce immediate risks.

USACE activities in Napa County are carried out through formal partnerships with local sponsors and typically involve shared funding responsibilities among federal, state, and local agencies. These efforts complement ongoing work by regional and local entities and support an integrated, watershed-based approach to flood risk reduction.

State Regulatory Environment
California Department of Water Resources (DWR)
The California Department of Water Resources (DWR) serves as the lead state agency for water management and flood risk reduction and plays an important supporting role in Napa County through planning, technical assistance, data development, and funding. While DWR does not directly operate local flood control infrastructure in Napa County, it works closely with the Napa County Flood Control and Water Conservation District and other regional partners to advance both structural and non-structural flood mitigation efforts.

DWR’s responsibilities and activities in Napa County include:
▪ Floodplain Mapping and Data: DWR collaborates with FEMA and local agencies to support the development and refinement of flood hazard mapping, including provision of hydrologic and hydraulic data used in Flood Insurance Studies and risk assessments. DWR’s Best Available Mapping (BAM) and related datasets help identify areas vulnerable to flooding beyond mapped regulatory floodplains, supporting local planning, capital improvement decisions, and hazard mitigation efforts throughout the Napa River watershed.
▪ Flood Forecasting and Operations Support: During major storm events, DWR operates the Flood Operations Center (FOC), which provides real-time hydrologic data, precipitation forecasts, and watershed conditions. This information supports local emergency response, reservoir operations (including Lake Berryessa releases), and coordination with flood control agencies in Napa County. ▪ Technical Assistance: DWR provides engineering, hydrologic modeling, and watershed planning support to local agencies. In Napa County, this includes assistance with evaluating flood risk along the Napa River and its tributaries, sediment management considerations, and integration of climate-informed data into local planning efforts.

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▪ Grant Funding: DWR administers multiple grant programs that support flood risk reduction projects in Napa County, including planning, design, and construction activities. These programs fund multi-benefit projects such as floodplain restoration, channel improvements, stormwater management, and resilience planning, particularly in areas vulnerable to riverine and downstream tidal flooding. ▪ Climate Adaptation and Resilience: DWR supports local agencies in Napa County through climate science, guidance, and funding focused on changing hydrologic conditions, including more intense storm events and sea-level rise impacts in southern portions of the county. These efforts promote integrated watershed management approaches that combine flood risk reduction with ecosystem restoration.

Through these activities, DWR serves as a key partner to Napa County and its jurisdictions, helping to advance a coordinated, watershed-based approach to flood management that aligns state resources with local priorities.

Local Regulatory Environment
Napa County Flood Control & Water Conservation District The Napa County Flood Control and Water Conservation District (NCFCWCD) was established by the California State Legislature in 1951. Napa County supported District formation to create a separate government entity responsible for developing and managing domestic water supplies and managing flood and storm waters in Napa County. The District participates in government programs and joint-use activities to augment and enhance local water supplies and obtain federal and state assistance to finance flood risk management projects.

Since its formation, NCFCWCD has developed two principal and distinct service activities: water conservation and flood control. The District’s water conservation services primarily involve administering contracts with the State of California and the United States Bureau of Reclamation for annual water supply entitlements from the State Water Project and the Solano Project, respectively. As part of its administrative duties, the District subcontracts its imported water supply entitlements to cities and special districts throughout Napa County.

The District’s flood management services focus on managing and coordinating projects intended to protect local communities from inundation by maintaining and clearing tributary channels and sponsoring capital improvements. This includes implementing the voter-approved “Napa River/Napa Creek Flood Protection Project,” which includes projects to protect the City of Napa from a 100-year flood.

Prior to NCFCWCD’s formation, organized flood control activities in Napa County were primarily the responsibilities of local jurisdictions. However, in 1938, the United States Congress passed legislation authorizing and funding the Army Corps of Engineers (USACE) to study flood-hazard waterways throughout the nation for the purpose of developing and implementing protection plans. The Napa River, on record as having severely flooded more than a dozen times, was among the subjects studied. (County, 2016) CAL OES SUBMITTAL - JUNE 2026
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Napa County Floodplain Management Regulations
Napa County has participated in the NFIP since 1980 and has adopted the most recent FIRMs and FIS issued by FEMA (dated August 3rd 2016) as well as local floodplain development regulations in compliance with the minimum NFIP standards (Chapter 16.04 of the County Code). These minimum standards include procedures and provisions for substantial improvements and substantial damages to existing structures, the latter of which are employed by the floodplain administrator and county building inspectors following any hazard event affecting structures located in the flood hazard area in accordance with NFIP requirements. Regulations for substantial or cumulative improvements are enforced via permitting procedures. By code, implementation and enforcement of the County’s floodplain regulations are assigned to the county Director of Planning, Building and Environmental Services or their designee.

The provisions of Chapter 16.04 are intended to promote public health, safety, and welfare, and to minimize public and private losses due to flood conditions. The regulations restrict land uses that could increase erosion, obstruct flood flows, or exacerbate flooding; require that new construction and substantial and cumulative improvements over a 5-year period be protected against flood damage at the time of initial construction; limit the alteration of natural floodplains, stream channels, and protective barriers; and avoid development practices that could unnaturally divert floodwaters or increase flood hazards in other areas.

County Code Title 18 (Zoning Regulations) provides additional protections for riparian corridors to maintain their natural flood and erosion control functions.

The Napa County Code addresses flooding through regulation of land use activities (§ 16.04). Regulations include prohibiting land uses that could result in increases erosion and flooding; requiring flood protection at initial construction; limiting the alternation of natural floodplains and stream channels during construction; and avoiding constructing barriers that could unnaturally divert floodwaters or increase flood hazards. The regulations also include development restrictions for the protection of riparian areas.

Napa County Code outlines requirements for drainage and flood control facilities and flood control protection for new development, based on the size of development. Drainage facilities should be designed to capture projected runoff from a storm with a frequency of one in one hundred years, and must be approved by the County before installation. Similar requirements are in place for improvement plans for flood control facilities.

Napa County General Plan
The Napa County General Plan Safety Element (August 2023 Update) establishes a comprehensive policy framework to reduce flood risk through land use regulation, infrastructure improvements, and hazard mitigation strategies, consistent with California Government Code §65302(g) requirements for flood hazard planning.

Goal SAF-6: Protect life, property, and environmental resources from flood hazards through integrated planning, regulatory standards, and capital improvements. (Goal context derived from Flooding section, SAF-32–34) Key supporting policies include:

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▪ Policy SAF-6.2: Maintain flood-prone areas in agricultural or open space uses to reduce exposure of structures and preserve natural floodplain functions.
▪ Policy SAF-6.3: Require review of development within mapped floodways using FEMA Flood Insurance Rate Maps (FIRMs), ensuring compliance with the County’s FEMA-approved Floodplain Management Ordinance and maintaining flood protection performance (e.g., Napa River freeboard). ▪ Policy SAF-6.4: Evaluate development proposals using dam failure inundation maps to inform siting decisions and evacuation planning.
▪ Policy SAF-6.5: Support dam and levee safety by coordinating with responsible agencies and operators to ensure proper maintenance and risk reduction. ▪ Policy SAF-6.15: Adopt enhanced regulatory standards consistent with a no-adverse-impact floodplain management approach, reducing future flood risk and cumulative impacts. ▪ Policy SAF-6.16: Require elevation of new or substantially improved structures above the 100-year flood level to provide a margin of safety, including consideration of extreme weather and sea level rise.
▪ Policy SAF-6.17: Ensure updated FEMA floodplain mapping reflects future conditions, including climate change and sea level rise, to guide development and land use decisions.

Additional policies support structural and programmatic mitigation actions, including:
▪ Stormwater and drainage improvements (Policy SAF-6.14); ▪ Bridge and culvert retrofits for 100-year flows (Policy SAF-6.13); ▪ Flood risk reduction in unprotected areas and NFIP participation outreach (Policies SAF-6.6 and SAF-6.7); and
▪ Watershed and channel management measures (Policies SAF-6.8–6.12).

Past Events
Flooding in Napa County is a recurring hazard driven primarily by prolonged, high-intensity winter storm events affecting the Napa River watershed. As documented in the FEMA Flood Insurance Study, floodproducing streamflow typically results from rainfall events lasting more than 12 hours, most commonly during the winter months, and the Napa Valley floor has historically experienced frequent inundation along the Napa River and its tributaries . Historical records indicate repeated major flood events dating back to the 19th century, with continued damages throughout the 20th century, culminating in the February 1986 flood, which caused approximately $100 million in damages and widespread impacts to residences and infrastructure. More recent federally declared disasters, summarized in Table 3-13, demonstrate that flooding remains a persistent and significant hazard, with multiple declarations in 1995, 1997, 1998, 2006, 2017, 2019, and 2023 associated with severe winter storms, flooding, landslides, and mudslides.

Supplementing these federal disaster records, the NOAA Storm Events Database provides detailed, eventlevel documentation of flooding impacts across Napa County, as summarized in Table 3-14. These data indicate that flooding is most frequently associated with atmospheric river systems, which deliver intense rainfall, saturate soils, and produce a combination of riverine flooding, urban flooding, debris flows, and CAL OES SUBMITTAL - JUNE 2026
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landslides. For example, a series of atmospheric river events in 2017 caused widespread flooding across the Napa River watershed, with stream gauges exceeding flood stage and numerous roadway closures in both incorporated and unincorporated areas. Similarly, multiple atmospheric river events in February 2019 produced over 10 inches of rainfall in some locations, resulting in widespread roadway flooding, debris flows, and hazardous conditions, including vehicles being swept from flooded roadways.

NOAA records further highlight the frequency of localized but impactful flood incidents that may not rise to the level of federal disaster declarations but still result in significant disruptions. These include roadway washouts, such as the failure of Big Ranch Road during the February 2025 atmospheric river event; landslides and rockfalls along key transportation corridors such as State Route 29; and repeated flooding along rural roads including Deer Park Road, Silverado Trail, and Pope Valley areas. In addition, coastal and tidal influences contribute to flood risk in southern portions of the county, where King Tide events in 2020 and 2022 caused minor but recurring flooding along the San Francisco Bay shoreline.

Recent events from 2024 and 2025 demonstrate that these patterns are ongoing, with successive winter storms and atmospheric rivers producing heavy rainfall, localized flooding, and debris-related impacts, particularly in steep, unincorporated areas where drainage infrastructure is limited. Notably, a November 2024 atmospheric river delivered extreme rainfall totals, approaching one foot in valley areas and significantly higher in upland regions, triggering landslides that blocked major routes. Additional storm sequences in December 2024 and December 2025 caused travel disruptions, roadway flooding, and debris deposition during peak holiday periods.

Together, the FEMA disaster data and NOAA event records illustrate that flooding in Napa County occurs across a spectrum of scales—from large, federally declared disasters impacting the entire watershed to frequent, localized events affecting transportation networks and rural communities. These datasets collectively demonstrate that flood hazards in Napa County are closely tied to atmospheric river activity, saturated watershed conditions, and the geomorphic characteristics of the Napa River basin. The combined evidence underscores the need for comprehensive mitigation strategies that address both large-scale flood events and the cumulative impacts of smaller, recurring incidents, particularly in vulnerable unincorporated areas.

Table 3-13: Napa County FEMA Declared Flood Disasters Since 1995 Year Month / Day Incident Description Disaster No.
2023 2-Apr
Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, & Mudslides DR-4699-CA
2023 9-Mar Severe Winter Storms, Flooding, Landslides, & Mudslides EM-3592-CA 2023 13-Jan Severe Winter Storms, Flooding, Landslides, & Mudslides DR-4683-CA 2023 8-Jan Severe Winter Storms, Flooding, & Mudslides EM-3591-CA 2019 05/01; 05/17 Severe Storm, Winter Storm, Mud & Landslides, Flooding DM-4431/4434 2017 2/14; 3/16; 04/01 Severe Storm, Winter Storm, Mud & Landslides, Flooding DM-4301/4305/4308 2006 29-Mar Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1646 2006 17-Dec Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1628 CAL OES SUBMITTAL - JUNE 2026
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Year Month / Day Incident Description Disaster No.
1998 2-Feb Severe Storms, Flooding DR-1203
1997 16-Feb Severe Storms, Flooding, Mud & Landslides DR-1155 1995 3-Jan Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1044 1995 13-Feb Severe Storm, Winter Storm, Mud & Landslides, Flooding DR-1046 Source: FEMA Disaster Database
Table 3-14: Napa County NOAA Recorded Flood Events Since 1995 Date Event Type Consolidated NOAA Narrative
12/22/2025 Flood A series of winter storm systems from December 19–25 produced heavy rainfall, roadway impacts, and widespread disruptions across the region, including boulders blocking Highway 121 near Wild Horse Valley Road. The storms significantly affected holiday travel, caused major flight delays, and resulted in widespread power outages.
2/3–2/4/2025 Flood An intense atmospheric river brought heavy rain and strong winds to Napa County, causing roadway flooding, washouts (Big Ranch Road), and rockslides along State Route 29, with broader regional flooding including the Russian River. 12/29/2024 Flood Multiple storm systems between December 26–29 generated localized flooding, gusty winds, and debris movement, including rocks obstructing Deer Park Road. 11/22/2024 Flood A powerful atmospheric river with rapid cyclogenesis delivered extreme rainfall (up to ~1 foot in valleys), triggering significant landslides and roadway blockages along State Route 29 and surrounding areas.
1/31/2024 Flood A fast-moving cold front and narrow cold frontal rainband produced intense rainfall and high winds, resulting in roadway flooding along State Route 221 and Route 29. 7/11–7/13/2022 Coastal Flood Exceptionally high astronomical tides (King Tides) caused minor coastal and bay shoreline flooding, resulting in roadway closures and localized inundation over multiple days.
11/15/2020 Coastal Flood King Tides combined with rough seas produced minor coastal flooding and hazardous ocean conditions, including roadway inundation and dangerous surf.

Feb 2019
(multiple
dates)
Flood A series of atmospheric rivers delivered extreme rainfall (over 20 inches in some areas), resulting in widespread flooding, roadway inundation, debris flows, and hazardous conditions including vehicles swept from roadways. Strong winds and regional river flooding compounded impacts.
2/12–2/15/2019 Flood A strong atmospheric river and cold front produced heavy rainfall (up to 10 inches), widespread flooding, debris flows, and dangerous roadway conditions, along with high winds causing downed trees, infrastructure damage, and fatalities regionally. 1/2019
(multiple
events)
Flood Multiple winter storms and atmospheric rivers caused repeated roadway flooding, debris flows, and high wind impacts, including flooding along Silverado Trail and Deer Park Road, with some events producing tornadoes and fatalities elsewhere in the region.
11/29/2018 Flood A low-pressure system produced heavy rain, thunderstorms, and gusty winds, resulting in roadway flooding, debris flows, and downed trees in Napa County.

Feb 2017
(multiple
events)
Flood / Flash
Flood
A sequence of atmospheric river events saturated soils and produced widespread flooding, stream exceedances (Napa River and Milliken Creek), roadway inundation, and debris flows throughout the county.
12/15/2016 Flood A slow-moving winter storm produced prolonged moderate to heavy rainfall, causing widespread roadway flooding and wind-related damage across Napa County.

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2/2015 Flood / Heavy
Rain
A strong winter storm ended a prolonged dry period, producing heavy rainfall (5–10 inches in higher elevations), localized flooding, debris flows, and wind damage. 12/11/2014 Flood A high-intensity atmospheric river with a narrow cold frontal rainband produced extreme short-duration rainfall rates (up to 2 inches/hour), causing widespread urban flooding, debris flows, and storm-related impacts. 12/23/2012 Flood A series of atmospheric river storms during late December caused widespread flooding, including Hopper Creek overflow, roadway inundation, and disruptions to transportation such as rail service.
11/30/2012 Flood / Heavy
Rain
Multiple winter storms produced heavy rainfall, urban and small stream flooding, and power outages across Napa County.
12/2002 Flood / Flash
Flood
One of the wettest Decembers on record produced prolonged rainfall, resulting in mainstem flooding along the Napa River (exceeding flood stage), widespread urban flooding, and saturated soil conditions increasing landslide risk. 12/31/2005–
1/1/2006
Flood Severe flooding occurred as the Napa River exceeded flood stage, inundating downtown Napa and surrounding areas, damaging hundreds of homes and businesses, and causing significant economic losses.
1997–1998 Flood / Flash
Flood
Intense rainfall events caused rapid rises in the Napa River and tributaries, exceeding flood stage and producing widespread flooding and infrastructure impacts, including levee-related failures in the region.

Source: NOAA Event Database (1995 – 2025)
Location
Flooding in Napa County is concentrated along a north-to-south corridor following the Napa River, with the highest flood exposure occurring in the central and southern portions of the county where the river widens and topography flattens. As illustrated in Figure 3-9, mapped flood hazard areas are primarily located along the Napa River mainstem and its associated floodplain, extending from the upper valley near Calistoga through St. Helena and Yountville, and becoming more expansive downstream of the City of Napa toward American Canyon. In these southern reaches, floodplains broaden significantly and are further influenced by tidal conditions from San Pablo Bay, increasing both the extent and duration of inundation.

While the Napa River serves as the primary drainage system, flood risk is also distributed across a network of tributary creeks that contribute substantial runoff during storm events. On the west side of the watershed, creeks such as Sulphur Creek, Dry Creek, Hopper Creek, Redwood Creek, Napa Creek, and Browns Valley Creek drain steep upland areas and convey flows through developed portions of the valley floor, often resulting in localized flooding where channel capacity is limited or crossings are constrained. On the east side, tributaries including Conn Creek, Rector Creek, and Milliken Creek exhibit similar behavior, with rapid runoff from higher elevations contributing to downstream flood conditions. Many of these tributaries intersect rural roadways and developed parcels in unincorporated areas, where infrastructure limitations and proximity to channels increase vulnerability.

The map also indicates that a substantial portion of the floodplain, particularly in the central and southern valley, overlaps with agricultural lands and open space, although developed areas and critical infrastructure CAL OES SUBMITTAL - JUNE 2026
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are present within or adjacent to these zones. Flood risk is therefore not limited to the main river channel but extends across interconnected floodplain and tributary systems throughout the watershed. These patterns highlight that, despite improvements associated with the Napa River Flood Protection Project, residual flood risk persists, particularly along tributary corridors and in low-lying areas where floodwaters can spread beyond defined channels.

Flood Awareness Zones
In addition to FEMA-designated Special Flood Hazard Areas, the California Department of Water Resources (DWR) Best Available Mapping (BAM) program identifies Flood Awareness Zones that represent areas of potential flood risk not fully captured in detailed FEMA studies. These zones, shown in Figure 3-10 and Figure 3-11 highlight smaller tributaries, upper watershed channels, and localized drainage areas where flooding has been observed or is anticipated under larger storm events, including the 200-year flood. In Napa County, these mapped areas are primarily concentrated in unincorporated, upland, and transitional valley areas where hydrologic response is rapid and drainage infrastructure is limited.

As illustrated in Figure 3-10 (Dry Creek and Surrounding Area), Flood Awareness Zones are prevalent in the northern Napa Valley and Calistoga area, including Dry Creek, York Creek, Cyrus Creek, and Blossom Creek, as well as tributaries to Garnett Creek. These systems drain steep terrain and convey flows into the upper Napa River, where narrow channels and confined valleys can produce localized flooding, roadway overtopping, and debris-related impacts during intense rainfall. Additional mapped areas include small tributaries of Pope Creek and drainage networks within Elder Valley, Soda Valley, and Soda Canyon, where topography and watershed characteristics contribute to rapid runoff and increased flood potential.

Further south, Figure 3-11 (South Napa 200-Year Awareness Zones) shows expanded Flood Awareness Zones in lower elevation areas near the Napa River and San Pablo Bay, including Carneros Creek and other tributaries draining toward tidal floodplains. In these areas, flood risk may be influenced by a combination of upstream runoff, flat topography, and backwater effects from tidal conditions, resulting in prolonged inundation and limited drainage capacity.

Although these BAM-identified areas are not regulated as FEMA floodplains, they indicate locations where flooding can occur outside mapped Special Flood Hazard Areas, particularly during extreme storm events such as atmospheric rivers. These zones are especially relevant in unincorporated Napa County, where development patterns, rural road networks, and proximity to creeks increase exposure. The identification of Flood Awareness Zones underscores the importance of incorporating watershed-scale planning, maintaining natural drainage systems, and carefully managing land use in headwater and tributary areas to reduce both localized and downstream flood risks.

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Figure 3-9: Napa County FEMA Flood Risk Exposure Map
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Figure 3-10: DWR Awareness Zones (Dry Creek and Surrounding Area) CAL OES SUBMITTAL - JUNE 2026
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Figure 3-11: DWR 200-YR Awareness Zones (South Napa)
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Levee Systems
Levee systems in Napa County differ substantially from traditional urban flood control systems, with the majority of levees located in the southern portion of the county serving agricultural, wetland, and reclamation functions rather than providing engineered flood protection to developed areas. As shown in Figure 3-12, an extensive network of levees is concentrated around the Napa River estuary, lower Napa River corridor, and the Napa-Sonoma Marshes Wildlife Area. These levees were historically constructed to support agriculture, salt pond operations, and land reclamation, and today many function to manage water levels in wetlands, protect habitat restoration areas, and maintain access to low-lying lands. As a result, these systems generally do not provide a consistent or engineered level of flood protection and may be overtopped during high river flows, storm surge, or elevated tidal conditions.

In contrast, there are a limited number of levee and flood management structures along the Napa River system designed to reduce flood risk to developed areas, particularly in and around the City of Napa and adjacent unincorporated communities. These include features associated with the Napa River Flood Protection Project, which incorporates a combination of levees, floodwalls, bypass channels, and restored floodplain areas to manage flood flows through the central Napa River corridor. While these improvements have significantly reduced the risk of catastrophic flooding in developed areas, they do not eliminate flood risk, particularly during extreme storm events that exceed design capacity or when tributary flooding occurs outside of the protected system.

Levees in southern Napa County, particularly those protecting low-lying areas near the bay and along corridors such as Milton Road, are often subject to additional stressors including tidal influence, sea level rise, subsidence, and limited maintenance resources. These conditions can increase the likelihood of overtopping, erosion, or structural degradation over time. Failure or overtopping of these levees can result in rapid inundation of adjacent lands, including agricultural areas, rural residences, transportation routes, and ecological preserves.

Overall, Napa County’s levee systems present a complex risk profile: while some structures provide targeted flood risk reduction in developed areas, much of the levee network in the southern county functions primarily for water management and habitat purposes and should not be relied upon for flood protection.

As illustrated in Figure 3-12, areas behind these levees remain vulnerable to flooding, particularly under combined riverine and tidal conditions, underscoring the importance of continued monitoring, maintenance, and integration of levee performance into broader flood risk management and land use planning efforts.

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Figure 3-12: Southern Napa County Levee System
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3.3.2.5.1 Repetitive Loss (RL)
A repetitive loss (RL) property is a FEMA designation, defined as an insured property that has made two or more claims of more than $1,000 in any rolling 10-year period since 1978. The term “rolling 10-year period” means that both qualifying claims happen within 10 years of each other. For example, a property would be designated as RL if there was a claim of $1,500 in January 2006 and another claim for $2,000 in December 2015, but not if the second claim occurred after January 2016. Claims must be at least 10 days apart but within 10 years of each other.

RL properties may be classified as Severe Repetitive Loss under certain conditions. A Severe Repetitive Loss property (SRL) has had four or more claims of at least $5,000, or at least two claims that cumulatively exceed the buildings reported value. A property that sustains repetitive flooding may or may not be on Napa County’s RL property list for a number of reasons:
▪ Owners who have completed the terms of the mortgage or who purchased their property outright may not choose to carry flood insurance and instead bear the costs of recovery on their own. ▪ The owner of a flooded property that does carry flood insurance may choose not to file a claim. ▪ Even insured properties that are flooded regularly with filed claims may not meet the $1,000 minimum threshold to be recognized as an RL property.
▪ The owner adopted mitigation measures that reduce the impact of flooding on the structure, removing it from the RL threat and the RL list (in accordance with FEMA’s mitigation reporting requirements).

A property does not have to be currently carrying a flood insurance policy to be considered a RL or SRL property. Often homes in communities are not carrying flood insurance but are still on the community’s RL list. The RL designation follows a property from owner to owner, from insurance policy to no insurance policy, and even after the property has been mitigated. Having an insurance policy and making claims that fall into the repetitive loss criteria will put a property on the RL list. Even after the policy on a property has lapsed or been terminated, the property will remain on the county’s RL list.

Extensive FEMA NFIP databases are used to track claims for every participating community, including unincorporated Napa County. Currently, unincorporated portions of Napa County contain 39 RL properties under their jurisdictional umbrella. Of the 39 properties, 6 are SRL properties. The total dollar amount of claims paid to date by the NFIP for RL properties is $2,578,028 of structural and $718,251 content claims.

Together, the total claims paid by the NFIP are $3,296,280 for the unincorporated areas of the County.

Since 2010, Napa County has successfully mitigated several RL/SRL properties, primarily through elevation and relocation to reduce exposure in certain repetitive loss areas (RLA). However, 394 properties remain unmitigated and insured under the NFIP which continue to generate claims during significant flood events.

Addressing these remaining properties through cost-effective mitigation measures remains a priority in the county’s flood risk reduction strategy. Loss statistics under the NFIP are presented in Table 3-12. 4 * According to FEMA data, 4 RL properties assigned to local participating jurisdictions are in the unincorporated County.

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3.3.2.5.2 Repetitive Loss Areas Analysis (RLAA)
A Repetitive Loss Areas Analysis (RLAA) identifies clusters of RL and SRL properties located in close proximity and subject to similar flood hazard conditions. These repetitive loss areas (RLA) typically share the same flooding source—such as a river, creek, or coastal reach—and are susceptible to repetitive damage during high-water events. In unincorporated Napa County, repetitive loss properties are concentrated in the riverine corridors and smaller narrow tributaries.

The county-wide repetitive loss areas map in depicts all 7 identified RLAs in unincorporated Napa County.

Each RLA represents a geographic cluster of RL and SRL properties that share similar flooding sources and conditions. The boundaries are based on FEMA NFIP claim records, spatial clustering of affected parcels, and local knowledge of flood hazard patterns. These areas capture the most concentrated repetitive flooding risks in the county, occurring in predominantly in the Napa River corridor.

The RLA map series prepared for this plan delineates these clusters and provides aggregated data on claim history, historic losses, and current property values for each identified RLA. These RLAs represent the most concentrated geographic expression of repetitive flooding in the county and are the logical focus for targeted mitigation actions such as structure elevation, acquisition, or floodproofing. Each RLA is profiled individually in this section, contains a summary of its location, flood source, historical flooding patterns, NFIP claims history, known mitigation actions, and recommended strategies for reducing RL exposure.

Under the Privacy Act of 1974 (5 U.S.C. 552a), FEMA restricts public release of flood insurance policy and claims data. Individual property-level information can only be shared with state and local governments for floodplain management, mitigation, or research purposes. Accordingly, this plan presents only aggregated information for each RLA and does not identify specific properties or individual claim records.

Other sources used to inform the RLAA and recommended mitigation measures include: the 2020 Napa County Multi-Jurisdictional Hazard Mitigation Plan, the 2022 City of Napa Hazard Mitigation Plan, the FEMA Local Mitigation Planning Policy Guide (2022), the FEMA Local Mitigation Planning Handbook (2023), the FEMA Flood Insurance Study (FIS) for Napa County, the California Department of Water Resources Best Available Mapping (BAM) datasets, and FEMA Mitigation Ideas (2013).

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Figure 3-13: Napa County Repetitive Loss Areas
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Napa River at Howell Mountain Road (RL Area A)
The Howell Mountain Road RLA lies along the Napa River near the intersection of Howell Mountain Road and Silverado Trail, where the river corridor narrows and development is situated in close proximity to the active channel (Figure 3-14). Upstream watershed areas draining the eastern hillslopes can generate rapid runoff during intense winter storm events, particularly during atmospheric river conditions common between December and February. The confined floodplain and presence of transportation crossings contribute to localized increases in water surface elevations during peak flows.

Historical flood impacts in this area have included overbank flooding affecting residential structures, roadway inundation along Silverado Trail, and localized erosion along the riverbanks. The proximity of structures to the floodway increases susceptibility to direct inundation, while limited overbank storage capacity exacerbates flood depths.

Past mitigation efforts have largely focused on regional improvements associated with the Napa River Flood Protection Project downstream; however, localized measures in this area have been limited. Property-level adaptations, including minor grading and drainage improvements, have been implemented in some cases.

Mitigation options are constrained by the narrow floodplain and existing development patterns adjacent to the river corridor. These constraints limit opportunities for channel widening or major structural improvements.

Future recommendations for the Howell Mountain Road RLA include:
▪ Evaluating bridge and roadway crossing capacity to reduce backwater effects. ▪ Enhancing riparian corridor management to improve conveyance and reduce debris accumulation. ▪ Promoting property-level mitigation measures such as elevation and floodproofing through FEMA programs.

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Figure 3-14 Howell Mountain Rd. Repetitive Loss Area
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