Calistoga City Council
October 6, 2026

HAZARD MITIGATION PLAN 2026 UPDATE

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Social Vulnerability Index (SVI)
The Centers for Disease Control and Prevention (CDC) Social Vulnerability Index (SVI) provides a composite measure of community characteristics that influence the ability of populations to prepare for, respond to, and recover from hazard events. The SVI incorporates multiple demographic and socioeconomic variables, including income, age, disability status, housing characteristics, minority status, and transportation access, to identify areas where residents may experience increased sensitivity to external stressors. Within the HMMWC service area, Figure 7-9 indicates generally low to moderate levels of social vulnerability across most of the service boundary.

The predominance of lower SVI values is consistent with other demographic indicators observed within the service area, including higher median household incomes, relatively low poverty rates, and high owneroccupancy levels. Lower social vulnerability scores often suggest increased household capacity to absorb certain economic shocks, access insurance mechanisms, and implement preparedness measures.

However, social vulnerability is multifaceted, and lower composite scores do not eliminate hazard exposure or risk. In geographically constrained mountain communities, physical isolation, terrain-driven infrastructure limitations, and hazard intensity may offset aspects of socioeconomic capacity.

The HMMWC service area’s rural mountain setting introduces vulnerability factors not fully captured by traditional socioeconomic indicators. Steep terrain, limited roadway connectivity, and dispersed development patterns can significantly influence emergency response, evacuation logistics, and postdisaster recovery. Even populations with comparatively higher incomes may face elevated risk due to wildfire exposure, infrastructure fragility, and limited redundancy in lifeline systems. The concentration of development within a wildland-urban interface environment further amplifies these considerations, as hazard events such as wildfire can produce widespread structural losses, prolonged displacement, and cascading service disruptions.

Social vulnerability within the service area is also influenced by the presence of dependent populations, elderly residents, and individuals with disabilities. While mapped disability and dependent age group percentages appear relatively low to moderate, these populations may still require targeted consideration during hazard events. Disruptions to potable water supply, power systems, or transportation networks may have disproportionate effects on individuals with access and functional needs. The interdependence of utility services and household resilience reinforces the importance of reliable water system operations.

Utility disruptions themselves represent a key component of community vulnerability. HMMWC functions as critical lifeline infrastructure supporting domestic water supply, sanitation, fire protection, and public health. Hazard events affecting water quality, storage capacity, treatment operations, or distribution reliability may produce consequences that extend beyond physical infrastructure damage. Water shortages, contamination events, or prolonged outages may affect household habitability, emergency response capabilities, and economic stability.

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Figure 7-9: HMMWC CDC Social Vulnerability Index Map
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7.2.3 Economy
The economy of the HMMWC service area is closely tied to its function as a rural, predominantly residential mountain community within Napa County. Unlike incorporated cities or urbanized districts, the local economy is not defined by concentrated commercial or industrial centers but rather by residential land uses, small-scale service activities, and employment patterns linked to the broader Napa County region.

Many residents commute to employment centers located on the Napa Valley floor or in surrounding communities, reflecting the service area’s role as a residential and institutional enclave rather than a primary employment hub.

Property ownership represents a central component of the local economic structure. Housing characteristics within the service area indicate high rates of owner-occupied residences, suggesting a community where wealth and financial stability are significantly influenced by real property assets.

Residential property values, insurance coverage, and long-term investment in structures collectively shape household economic conditions. This ownership pattern also introduces substantial financial exposure to hazard events. Wildfire, earthquake, and landslide impacts may produce significant economic losses through structural damage, rebuilding costs, and prolonged displacement. Hazard-driven fluctuations in property values and insurance availability may therefore have pronounced effects on household financial stability.

The regional economy of Napa County exerts a strong influence on the HMMWC service population.

Employment sectors commonly associated with Napa County include tourism, hospitality, agriculture, viticulture, professional services, education, healthcare, and local government. The Angwin area’s institutional presence, including educational facilities, contributes to localized economic activity through employment, housing demand, and service needs. These institutional and commuter-based economic linkages underscore the interconnected nature of the service area with surrounding jurisdictions.

Household income indicators suggest that the service area generally reflects higher median income levels relative to many rural communities. Higher income characteristics may support greater capacity for property maintenance, insurance participation, and hazard mitigation investments. However, economic resilience varies among households. Fixed-income residents, retirees, and individuals facing insurance or rebuilding cost constraints may experience disproportionate impacts following hazard events. Even in higher-income communities, large-scale disasters such as wildfire can produce significant uninsured losses, extended reconstruction timelines, and economic uncertainty.

HMMWC itself functions as an economically critical entity within the community. As a member-owned mutual benefit corporation, the company’s financial sustainability depends on rate structures, membership contributions, infrastructure maintenance, and regulatory compliance obligations. Utility operations require ongoing investment in treatment systems, reservoirs, pipelines, electrical infrastructure, and watershed management. Hazard events affecting infrastructure may generate repair costs, capital improvement demands, and revenue variability associated with service disruptions or changes in customer demand.

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The economic consequences of utility disruptions are also an important consideration. Reliable potable water service supports residential occupancy, sanitation, fire suppression capability, and property protection. Interruptions to water supply or water quality may produce cascading economic effects, including temporary habitability challenges, increased emergency response costs, and potential impacts to insurance recovery processes. Water availability during wildfire events is particularly critical, as it directly supports firefighting operations and structural defense.

7.2.4 Growth Trends & Future Development
Growth patterns within the HMMWC service area are shaped primarily by the region’s rural mountain setting, infrastructure constraints, and environmental conditions. Unlike urbanized areas experiencing rapid expansion, the HMMWC service boundary reflects development characteristics typical of low-density residential communities where growth occurs gradually and is closely tied to parcel-level construction, redevelopment, and property improvements. The mountainous terrain, limited roadway access, and presence of watershed lands collectively constrain large-scale development, resulting in relatively stable long-term population and housing trends.

Land use within the service area is predominantly residential, with development occurring on dispersed parcels situated within forested and WUI environments. Physical limitations associated with steep slopes, drainage corridors, and geologic conditions influence both the location and intensity of new construction.

These geographic constraints naturally moderate development pressure, as buildable areas are limited, and infrastructure expansion often requires significant investment. As a result, future growth is expected to occur primarily through incremental infill, residential redevelopment, and improvements to existing properties rather than through concentrated subdivision activity.

Water supply availability represents a defining factor influencing future development potential. HMMWC’s Drought and Water Shortage Contingency Plan explicitly recognizes that system capacity is governed by watershed storage conditions and raw water availability. The Plan establishes staged response measures linked to reservoir storage levels, emphasizing that water supply variability is an inherent operational consideration. In systems dependent on stored surface water, extended drought conditions may constrain new connections, intensify conservation requirements, and influence development feasibility. Water resource limitations therefore serve as both operational and planning determinants.

Connection policies further illustrate the relationship between system capacity and development. The Consumer Water Connection Guidance outlines procedures for obtaining new water service, noting that feasibility determinations are required and that properties located far from existing mains may incur additional costs. These requirements reflect the practical constraints associated with extending infrastructure in mountainous environments. System expansion decisions must balance hydraulic capacity, treatment capability, storage adequacy, and long-term operational sustainability.

Hazard exposure also influences growth dynamics within the service area. The Howell Mountain region is subject to elevated wildfire risk, periodic drought conditions, seismic hazards, and localized slope CAL OES SUBMITTAL - JUNE 2026
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instability. Past wildfire events, including the Glass Fire, have demonstrated the potential for structural losses and long-term displacement within the community. Hazard-related rebuilding and redevelopment may therefore represent a more significant driver of construction activity than net-new growth. Recovery processes following hazard events often involve code compliance upgrades, defensible space improvements, and infrastructure reinvestment, all of which shape development trajectories.

Future development patterns are expected to remain consistent with existing land use characteristics, with continued emphasis on residential occupancy, property maintenance, and incremental improvements.

While regional housing pressures within Napa County may influence long-term demand, geographic constraints, water supply variability, and hazard exposure collectively moderate large-scale expansion potential. Infrastructure resilience, water reliability, and hazard mitigation investments will remain critical factors supporting both existing development and future growth.

7.3 Planning Process
HMMWC followed the planning process detailed in Volume 1, Section 2, including participating in the county-wide Hazard Mitigation Planning Team (HMPT) and formulating their own internal planning team to support the broader planning process.

The district’s representatives in the Steering Group led stakeholder and public engagement efforts alongside the Consultant Team, with assistance from the county-wide HMPT and their internal planning team. This engagement process is described in Volume 1. Specifically, for the district, this included postings to the district website and social media, and outreach events, as documented in Appendix B. Examples of Key Stakeholders engaged by Napa County on behalf of the district with relevance to the development of HMMWC’s mitigation strategy include the USDA and other federal agencies; CAL FIRE and other state agencies; other jurisdictions; community-based organizations such as local Chamber of Commerce chapters; utility providers like PG&E; UC Davis and other academia; and local businesses.

All Key Stakeholders that were invited to participate in the planning process are listed in Volume 1, Section 2, and the input received from stakeholders was integrated into the district’s annex, as described in Volume 1 Table 2-9. The district’s internal planning team participants, their positions, and how they participated in the planning process are shown in Table 7-1.

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Table 7-1: HMMWC Planning Team and Steering Group Members Team Members Title Description of Involvement
Shannon Damonte Administrative Manager Lead Point-of-Contact, HMPT #1, #2, #4, BO #1 and #2 Tanner Hiers General Manager Alternate Point-of-Contact, HMPT #1, #2 HMMWC staff participated in a comprehensive hazard mitigation planning process as part of the 2026 Napa County MJHMP update. This included a series of breakout meetings, listed in Table 7-2 that engaged the district’s planning team, which included key district personnel and stakeholders in evaluating hazards, identifying local vulnerabilities, and prioritizing mitigation strategies The process began with a County-Wide Steering Group Kickoff Meeting on February 28, 2024. This initial meeting focused on welcoming participants, establishing a shared understanding of the project scope and schedule, clarifying roles and responsibilities of the Steering Group, the county-wide Hazard Mitigation Planning Team (HMPT), and individual jurisdictional planning teams, and included a review of key changes since the 2020 Local Hazard Mitigation Plan The meeting set the foundation for coordinated participation throughout the planning effort.

On December 10, 2025, participants engaged in a hexagon mapping activity designed to visually identify mitigation actions that could benefit from or require inter-jurisdictional coordination. These collaborative efforts helped shape a refined set of mitigation alternatives, establish shared planning goals, and align local strategies with FEMA’s Hazard Mitigation Assistance (HMA) funding framework.

Throughout the series of breakout meetings, the district engaged in a structured and collaborative planning process focused on assessing hazard risks, identifying vulnerabilities, and developing targeted mitigation strategies. The meetings began with recaps of the county-wide HMPT meetings to ensure alignment of goals and progress.

During the September 10, 2024 breakout out meeting, discussions concentrated on community engagement outcomes, initial risk assessments, and the integration of demographic data to better understand vulnerable populations. Jurisdictional teams reviewed their specific hazard exposures using the Risk Assessment Mapping Platform (RAMP) and participated in prioritization exercises to identify their top hazards.

The June 3, 2025, breakout meeting shifted toward reviewing local capabilities and defining specific areas of concern, which informed the drafting of problem statements. Teams worked collaboratively to refine mitigation alternatives, align actions with FEMA guidelines, and develop a shortlist of priority mitigation actions and inter-jurisdictional collaboration opportunities.

The meetings also included consensus-building activities around hazard rankings, capabilities, and planned actions, while providing regular updates on the overall project schedule.

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Table 7-2: HMMWC Planning Team Meetings
Meeting & Date Agenda / Topics Goals / Key Inputs
County-Wide Steering Group and HMPT Kick-off and Meetings #1 & #2 February 28, 2024– July 18, 2024
HMMWC Planning Team
Breakout Meeting #1
September 10, 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 25, 2025
HMMWC Planning Team
Breakout Meeting #2
June 3, 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 10, 2025

7.3.1 Public Input & Draft Review
As detailed in Volume 1, Section 2, the draft plan was available for public review and comment from May 15 to June 2, 2026. Public comments received during that time were similar to those gathered throughout the public engagement process, including the need for more equity in the distribution of mitigation activities and funding and the need for enhanced cooperation among jurisdictions, utility providers, and state agencies. These comments were incorporated into the city’s mitigation strategy, as appropriate; although, most were already addressed by the Mitigation Action Plan which was based on previous public input.

Public and stakeholder input was gathered and incorporated throughout the plan development process, before the public review period, such as from the online public survey (see Volume 1, Section 2.1.2 and Appendix B, for details). During the review period, jurisdictional staff and stakeholders that participated in the plan development also reviewed the public draft and provided comments on minor corrections and revisions, which were addressed in the final plan.

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7.4 What’s New
This section provides an overview of hazard mitigation planning efforts for the planning area and highlights the updates made in the 2026 MJHMP. HMMWC previously participated in and maintained a Hazard Mitigation Plan, which guided resilience planning and hazard mitigation actions at the district level.

HMMWC is updating their current plan on a county wide level. This integration reflects the district’s ongoing commitment to regional resilience and acknowledges that many hazards such as coastal flooding, severe storms, and earthquakes cross jurisdictional boundaries.

Through participation in the MJHMP, HMMWC has identified its highest priority hazards, developed hazard specific problem statements, and proposed actionable strategies to reduce risks. By aligning with countywide partners and leveraging regional resources, HMMWC has strengthened its capacity to prepare for, withstand, and recover from disasters while continuing to protect its unique coastal community character.

7.4.1 Mitigation Activities
HMMWC has implemented and continues to pursue a range of mitigation activities designed to reduce system vulnerability, enhance infrastructure reliability, and improve resilience to natural hazards. As a small, watershed-dependent utility operating within a hazard-prone mountain environment, mitigation planning is closely integrated with routine operations, capital improvements, and long-term resource management strategies. These efforts reflect both regulatory requirements and operational necessities, given the system’s exposure to drought, wildfire, seismic hazards, and terrain-related risks.

Water supply management represents a central component of HMMWC’s mitigation framework. The adopted Drought and Water Shortage Contingency Plan establishes a structured response system tied to raw water storage capacity, allowing the company to proactively manage water demand during periods of reduced supply. The Plan defines staged conservation measures triggered by declining reservoir levels, thereby reducing the likelihood of severe shortages and supporting system stability under drought conditions. This staged approach functions as both an operational control mechanism and a hazard mitigation strategy, addressing one of the most persistent climate-related risks affecting the region.

Wildfire risk reduction and watershed management activities are also integral to HMMWC’s mitigation strategy. HMMWC performs ongoing vegetation management efforts within company-owned watershed lands, including tree removal, fuel reduction, and coordination with specialized crews. These measures are designed to reduce wildfire intensity, limit infrastructure exposure, and protect source water quality.

Wildfire mitigation within watershed areas is particularly important, as post-fire conditions can significantly degrade raw water quality through increased sedimentation, ash transport, and altered runoff dynamics.

Administrative and policy-based mitigation activities complement physical infrastructure improvements.

The Water Rate Plan and Company Policies establish mechanisms that support financial stability, conservation behavior, and system sustainability. Financial resilience is a key component of hazard CAL OES SUBMITTAL - JUNE 2026
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mitigation for small utilities, as adequate revenue streams and reserve capacity enable timely repairs, capital investments, and emergency response actions. Conservation-oriented policies further reduce stress on limited water supplies during drought and peak demand periods.

Collectively, HMMWC’s mitigation activities demonstrate a comprehensive approach that integrates water supply management, infrastructure investment, watershed protection, water quality control, and financial planning. These efforts reduce system vulnerability, improve operational reliability, and enhance the company’s capacity to withstand and recover from hazard events. Continued mitigation investment will remain essential given the region’s evolving climate conditions, persistent wildfire exposure, and infrastructure aging considerations.

7.4.2 Mitigation Successes
Water Tank Replacement
As part of ongoing infrastructure resilience and water system reliability improvements, HMMWC designed and inspected a new 500,000-gallon treated water storage tank. The project addressed long-standing deficiencies associated with the existing underground concrete storage tank, which had experienced chronic leakage that compromised both water quantity and water quality. Persistent water loss reduced effective storage capacity and increased operational strain on the system, while aging infrastructure contributed to elevated risks of contamination.

The newly constructed tank and associated piping system replaced the deteriorated concrete facility, improving system integrity, reducing leakage, and enhancing treated water storage reliability. The upgraded design also reduced water quality concerns associated with organics and chlorine interactions, thereby supporting regulatory compliance and public health protection. Although the original master plan contemplated installation of two 500,000-gallon tanks, construction-phase discoveries revealed that leakage within the legacy tank and piping network was substantially higher than previously documented.

Following system repairs and loss reduction, daily water loss declined to levels that allowed elimination of the second tank, resulting in cost efficiencies while maintaining adequate storage capacity.

The new 500,000-gallon treated water tank is now fully operational and serves as a critical component of the water company’s distribution system. By replacing storage infrastructure that was more than fifty years old, the project significantly reduced system vulnerability, improved operational reliability, and enhanced resilience to hazards including drought, wildfire, seismic events, and emergency demand conditions.

Vegetation Management
Board meeting records document ongoing vegetation management activities conducted within HMMWC’s watershed properties. These efforts include systematic tree removal, thinning of hazardous vegetation, and fuel reduction work performed in coordination with specialized contractors and forestry crews. Such activities are essential within heavily forested mountain environments, where accumulated fuels, ladder CAL OES SUBMITTAL - JUNE 2026
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vegetation, and drought-stressed trees can significantly increase wildfire intensity and fire spread potential.

Vegetation management within company-owned watershed lands serves multiple risk-reduction objectives. By reducing fuel loading and modifying fire behavior characteristics, these measures decrease the likelihood of high-severity wildfire impacts that could damage reservoirs, storage facilities, treatment infrastructure, and distribution assets. Fuel reduction also supports firefighter access and improves defensibility of critical water system components during wildfire events. In addition to protecting physical infrastructure, watershed vegetation management plays a critical role in safeguarding source water reliability.

Wildfire mitigation within watershed areas is particularly important because post-fire environmental conditions can produce substantial secondary impacts to water systems. High-severity burn areas often experience increased erosion, destabilized soils, and altered hydrologic responses, leading to elevated sediment transport, ash deposition, and organic loading in surface water sources. These changes may degrade raw water quality, increase treatment complexity, and strain system operations. Ash, debris, and nutrient influx following wildfire events can also contribute to disinfection byproduct formation and other water quality challenges. Proactive vegetation management therefore functions as both an infrastructure protection strategy and a source water quality mitigation measure, enhancing the overall resilience of the water supply system.

Deer Park Pipeline Replacement
The Deer Park Pipeline Replacement Project, supported in part by FEMA and CalOES funding, exemplifies resilience-oriented infrastructure improvements. Pipeline replacement initiatives reduce the probability of system failures associated with aging materials, seismic stresses, ground movement, and wildfire-related damage. Such projects enhance both operational continuity and emergency response capability.

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7.5 Risk Assessment
This section focuses on profiling hazards specific to HMMWC and assessing their vulnerability independent of the broader county-wide planning area, which has been evaluated in Section 3 of Volume 1. The hazard profiles in Volume 1 discuss overall impacts to the planning area and describe relevant plans, policies, and regulations; past events; location; frequency and probability of future occurrences; severity and extent; warning time; secondary hazards; and climate change impacts. For more information on risk assessment methodologies, see Volume 1, Appendix A.

This section includes a tailored vulnerability assessment, analyzing assets at risk such as population, property, and critical facilities and infrastructure unique to the district, and information on district-specific differences in hazard vulnerability across the planning area. It also identifies total district assets at risk, including people, property, and critical facilities and infrastructure within the district. In addition, this section presents growth and development trends for the community, offering insights into vulnerabilities and risks that represent the broader context of assets at risk.

7.5.1 Hazard Screening & Prioritization
Members of the Planning Team from each participating jurisdiction came together to collaboratively decide which county-wide hazards would be included in the MJHMP, and which would be excluded. Hazard screening and prioritization took place early in the process and integrated historic data, local knowledge, and consensus opinions to create a risk assessment matrix for the county as well as for each participating jurisdiction. These matrices indicate the priority of hazards prior to further refinement. Details about this process, the results of the discussion, and in-depth profiles for county-wide hazards can be found in Volume 1, Sections 2 and 3.

HMMWC’s internal planning group used the same hazard identification and prioritization process as the county-wide Planning Team. They reviewed previously prepared hazard mitigation plans and other relevant documents to determine the realm of natural hazards that have the potential to affect the district. Table 7-3 provides a crosswalk of hazards identified in select planning documents, including the 2020 Napa County MJHMP, 2020 HMMWC HMP, 2022 Climate Change Adaptation Plan and the 2023 State of California HMP.

The crosswalk was used to develop a preliminary hazards list, providing a framework for the group to evaluate which hazards were truly relevant to HMMWC and which ones were not.

The internal planning group then ranked hazards based on their probability of affecting HMMWC and potential impacts on the community. Figure 7-10 displays the results of the hazard risk ranking exercise that was performed before further refinement. All hazards have been profiled in Volume 1 of this document.

The purpose of this annex is to specifically address the district’s vulnerability to specifically identified hazards.

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Table 7-3: HMMWC Document Review of Potential Hazards
Hazard 2020 Napa County
MJHMP
2020 HMMWC
HMP
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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Figure 7-10: HMMWC Risk Assessment Matrix
Note: Hazard naming in the Risk Assessment Matrix may not match the final naming used. Refer to hazards prioritization summary table.

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Priority Hazards
The results of the initial risk ranking exercise completed by the district’s Planning Team, before further refinement, are identified in the county’s completed matrix in Figure 7-10. Table 7-4 provides the final list of priority hazards and subhazards with additional details about why certain hazards were chosen and why others 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.

Table 7-4: HMMWC Hazards Prioritization Summary
Hazard Priority Explanation
Earthquake / Liquefaction High Profiled in Volume 1, Section 3.3.4, and Section 7.5.2.3 in this annex (not including Liquefaction due to low probability and impact potential) Wildfire High Profiled in Volume 1, Section 3.3.1, and Section 7.5.2.1 in this annex Flood -
Profiled in Volume 1, Section 3.3.2; not a priority due to low probability and impact potential
Levee Failure -
Profiled in Volume 1, Section 3.3.2; not a priority due to low probability and impact potential
Extreme Weather / Storms High
Profiled in Volume 1, Section 3.3.5, and Section 7.5.2.5 in this annex as Severe Weather, including High Wind and Heavy Rain (Winter Weather not a priority due to low probability and impact potential) Drought High Profiled in Volume 1, Section 3.3.6, and Section 7.5.2.4 in this annex Geologic / Mass Movement -
Profiled in Volume 1, Section 3.3.5; not a priority due to low probability and impact potential
Extreme Heat -
Profiled in Volume 1, Section 3.3.8; not a priority due to being outside jurisdictional mission and authority
Agricultural Pests -
Profiled in Volume 1, Section 3.3.9; not a priority due to being outside jurisdictional mission and authority
Sea Level Rise -
Profiled in Volume 1, Section 3.3.9; not a priority due to low probability and impact potential
Climate Change Medium Profiled in Volume 1, Section 3.3.9, and Section 7.5.2.6 in this annex and discussed as a compounding hazard in relevant profiles
Dam Failure Medium Profiled in Volume 1, Section 3.3.3, and Section 7.5.2.2 in this annex CAL OES SUBMITTAL - JUNE 2026
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7.5.2 Vulnerability to Specific Hazards
Assessing vulnerabilities exposes the unique characteristics of individual hazards and begins the process of narrowing down which areas within the district are vulnerable to specific hazard events. The vulnerability assessment considered unique local knowledge of hazards and impacts and a GIS overlaying method for examining such vulnerabilities in more depth. Using these methods, the district’s planning group estimated vulnerable populations, properties, and assets, and potential losses. In addition, the exposure of district assets to drought, earthquake, wildfire, flood, and climate change hazards were also considered.

Many of the hazard profiles include a snapshot map and damage estimation tables that illustrate the district’s vulnerabilities to those specific hazards. These maps assisted the planning group in understanding the hazard exposure of populations, parcels, and critical facilities and infrastructure. Each snapshot map contains an exposure summary that displays the percentage of the population, the improvement and content value of parcels, and the amount of critical infrastructure that is exposed. For hazards without geospatial extents, such as drought and severe weather, narratives are provided instead of exposure maps and tables.

Based on the hazard prioritization exercise, this vulnerability assessment focuses on six hazards for the HMMWC, some of which encompass subhazards such as Heavy Rain.

Wildfire
SECTION 7.5.2.1
Dam Failure
SECTION 7.5.2.2
Earthquake
SECTION 7.5.2.3
Drought
SECTION 7.5.2.4
Severe Weather
SECTION 7.5.2.5
Climate Change
SECTION 7.5.2.6
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Wildfire Hazard
Wildfire represents one of the most significant hazards affecting the HMMWC service area. The company operates within a heavily vegetated, mountainous environment characterized by forested lands, steep terrain, and development patterns typical of the WUI. These physical conditions, combined with seasonal climate patterns marked by hot, dry summers and periodic wind events, create an environment highly conducive to wildfire ignition and rapid-fire spread.

Figure 7-11 indicates that the majority of the HMMWC service area is classified within very high wildfire risk zones, consistent with regional hazard designations for Napa County. Exposure metrics demonstrate that approximately 847 residents, representing roughly 52 percent of the mapped population, are located within the wildfire hazard area. Similarly, approximately 740 parcels, or 54 percent of the mapped parcels, fall within wildfire exposure zones. The concentration of residential development within high-risk wildfire areas underscores the direct relationship between hazard exposure, housing vulnerability, and utility system risk.

Wildfire hazards present both direct and indirect risks to HMMWC operations. Direct impacts may include damage to reservoirs, storage tanks, treatment facilities, pump stations, electrical infrastructure, and distribution pipelines. Wildfire events can also disrupt access routes, delay maintenance activities, and hinder emergency repair operations. Extended power outages, which frequently accompany wildfire events or Public Safety Power Shutoff (PSPS) actions, may further affect treatment and pumping capabilities, placing additional strain on system reliability.

Indirect wildfire impacts may be equally consequential. Post-fire watershed conditions often produce elevated erosion rates, destabilized soils, and altered hydrologic responses. These environmental changes can result in increased sedimentation, ash transport, organic loading, and contaminant introduction into raw water sources. Degradation of source water quality may increase treatment complexity, elevate operational costs, and challenge regulatory compliance. Secondary effects such as debris flows, slope failures, and flooding may also occur following high-severity burn events, compounding infrastructure vulnerability.

The economic exposure associated with wildfire hazards is substantial. The snapshot map indicates that parcels within the wildfire hazard area represent hundreds of millions of dollars in total assessed value, reflecting the significant financial consequences associated with structural losses and infrastructure damage. Wildfire events may therefore produce cascading impacts affecting property values, insurance availability, reconstruction timelines, and community stability.

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Figure 7-11: Exposure Summary – HMMWC Wildfire Risk
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Dam Failure Hazard
Dam failure represents a low-frequency but potentially high-consequence hazard within the HMMWC service area. Dam failure refers to the partial or complete structural failure of an upstream dam, resulting in the uncontrolled release of stored water. Figure 7-12 indicates that limited portions of the service boundary fall within mapped dam inundation zones. Exposure metrics identify approximately 89 residents, representing roughly 6 percent of the mapped population, and 65 parcels, or approximately 5 percent of parcels, as located within potential inundation areas. While the overall exposure footprint is comparatively small relative to other hazards, dam failure scenarios warrant consideration due to their rapid onset characteristics and potential severity.

Dam failure hazards are typically associated with structural failure, overtopping, seismic impacts, internal erosion, extreme precipitation events, or operational malfunctions affecting reservoir containment systems. In mountainous environments such as Howell Mountain, failure scenarios may produce sudden downstream flooding, high-velocity flow conditions, debris transport, and localized erosion. The steep terrain and confined drainage corridors characteristic of the region can amplify flow velocities and reduce warning times, increasing the potential for infrastructure damage and life safety risks.

Potential dam failure impacts within the HMMWC service area primarily relate to downstream flooding and associated secondary effects. Sudden inundation may damage residential structures, roadways, utility infrastructure, and distribution system components located within flood pathways. Floodwaters may also transport sediment, debris, and contaminants that affect water quality and treatment operations. Access routes critical for emergency response and infrastructure repair may be disrupted or rendered impassable.

Seismic hazards represent a particularly relevant consideration for dam failure risk. Earthquake events may induce structural stress, foundation instability, or embankment damage affecting reservoir systems. Given the region’s known seismic exposure, dam safety considerations are closely linked to broader geologic hazard planning. Extreme weather events, including intense rainfall or prolonged storm activity, may also influence reservoir performance through increased inflows, slope saturation, and erosion processes.

Although the mapped exposure rates for dam inundation are relatively low, the economic implications may be significant at the parcel level. Structures located within inundation zones may face elevated risk of damage, financial loss, and prolonged recovery timelines following a failure event. The Dam Inundation Exposure snapshot indicates tens of millions of dollars in parcel value within the hazard area, illustrating the potential economic consequences of a low-probability but high-impact scenario.

Dam safety oversight, inspection, and emergency action planning are managed at the state and regional levels, including by the California Department of Water Resources and the California Division of Safety of Dams. These agencies work with dam owners and local jurisdictions to monitor dam conditions and coordinate emergency notification procedures.

For HMMWC, dam failure hazards also intersect with operational considerations. Reservoir integrity is fundamental to raw water storage, treatment reliability, and distribution continuity. Structural compromise CAL OES SUBMITTAL - JUNE 2026
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of storage facilities may reduce system capacity, disrupt service delivery, and necessitate emergency repairs. Secondary effects such as sedimentation, contamination, or infrastructure access constraints may further affect system performance.

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Figure 7-12: Exposure Summary – HMMWC Dam Failure Risk
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Earthquake Hazard
Earthquake hazards represent a persistent and regionally significant risk factor for the HMMWC service area. Napa County is located within one of California’s most seismically active regions, influenced by multiple fault systems capable of generating moderate to strong ground shaking. The mountainous terrain, dispersed development pattern, and infrastructure dependencies characteristic of the Howell Mountain area introduce specific vulnerabilities associated with seismic events.

The earthquake exposure snapshot maps illustrate the range of potential shaking intensities under modeled seismic scenarios. The Hunting Creek – Berryessa Earthquake Scenario (M7.1), Figure 7-13, indicates that substantial portions of the HMMWC service area may experience strong to very strong shaking intensities, corresponding to Modified Mercalli Intensity (MMI) levels VII and VIII. Exposure estimates associated with this scenario identify approximately 329 residents, representing roughly 20 percent of the mapped population, and 221 parcels, or approximately 16 percent of parcels, within higher shaking intensity zones.

The modeled parcel value exposure exceeding $100 million underscores the potential economic consequences of a significant regional seismic event.

By contrast, the West Napa Earthquake Scenario (M6.7), Figure 7-14, indicates minimal direct exposure within the HMMWC service boundary. This variation reflects the influence of epicenter location, fault geometry, and attenuation effects on localized shaking intensities. Although scenario-specific exposure may vary, the broader seismic risk environment for Napa County remains substantial, with the potential for damaging ground motion affecting utility infrastructure and community assets.

Earthquake hazards pose both direct and cascading risks to HMMWC operations. Strong ground shaking may result in structural damage to storage tanks, reservoirs, pump stations, treatment components, and ancillary facilities. Buried distribution pipelines may be susceptible to joint failure, ground displacement effects, differential settlement, or slope-related stresses. Electrical systems, telemetry equipment, and mechanical components may also be disrupted, potentially affecting system monitoring and operational control.

Secondary hazards associated with earthquakes are particularly relevant within mountainous environments. Ground shaking may trigger slope failures, landslides, rockfalls, and soil instability, which can damage pipelines, obstruct roadways, and impair access to critical infrastructure. Seismic events may also affect watershed conditions, alter groundwater pathways, or introduce sediment into storage and treatment systems. Infrastructure accessibility constraints following an earthquake may significantly complicate damage assessment and repair operations.

Water systems play a critical role during and after seismic events. Reliable water supply is essential for fire suppression, emergency response operations, and community recovery. Earthquake-related damage to storage or distribution assets may reduce available firefighting capacity at precisely the time when postearthquake fire risk is elevated. Maintaining structural integrity, redundancy, and operational flexibility within the water system is therefore a core resilience objective.

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Although earthquake occurrence probabilities are inherently uncertain, the potential consequences of moderate to strong seismic events necessitate continued mitigation planning. Infrastructure design standards, seismic considerations in capital improvement planning, and system maintenance practices all contribute to reducing earthquake-related risk. The exposure patterns illustrated in the modeled scenarios reinforce the importance of evaluating both shaking impacts and secondary hazard interactions.

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Figure 7-13: Exposure Summary – HMMWC Earthquake Risk (M7.1 Hunting Creek–Berryessa) CAL OES SUBMITTAL - JUNE 2026
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Figure 7-14: Exposure Summary – HMMWC Earthquake Risk (M6.7 West Napa) CAL OES SUBMITTAL - JUNE 2026
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Drought Hazard
The National Drought Monitor provides drought data and maps nationally and on a localized, watershed scale. The National Drought Monitor is the product of 11 agencies, including the NDMC, NOAA and USDA, and is available at http://droughtmonitor.unl.edu/. The National Drought Monitor categorizes the level of drought from D0 through D4, with D4 being the highest “exceptional drought.” Table 7-5 depicts drought classifications and impacts from the level of drought occurrence in California, while Figure 7-15 shows a time series of the level of drought in Napa County from 2000 to 2026 according to the National Drought Monitor.

Drought represents one of the most consequential and persistent hazards affecting the HMMWC service area. Unlike rapid-onset hazards such as wildfire or earthquake, drought hazards develop gradually but may produce prolonged and system-wide impacts. The Mediterranean climate characteristic of Napa County, marked by highly seasonal precipitation patterns, inherently exposes mountain water systems to variability in annual rainfall, extended dry periods, and multi-year drought cycles.

HMMWC operates within a region where water supply reliability is closely tied to precipitation, watershed conditions, groundwater availability, and storage capacity. Reduced rainfall and diminished snowpack in surrounding upland areas may decrease surface water inflows, limit groundwater recharge, and lower reservoir storage levels. Prolonged dry conditions may therefore directly affect raw water availability, system pressure stability, and operational flexibility.

Drought hazards present both supply-side and demand-side challenges. On the supply side, declining source water levels may require increased reliance on stored reserves, pumping adjustments, or conservation measures. Extended drought conditions may also affect groundwater production, as declining water tables increase pumping depths, energy demands, and well performance variability. Reduced surface flows and diminished watershed moisture conditions may further influence water quality characteristics, including temperature, turbidity, and constituent concentrations.

Demand-side pressures often intensify during drought periods. Elevated temperatures and reduced precipitation typically increase outdoor water use, landscape irrigation demands, and evaporative losses.

These consumption patterns may strain system capacity precisely when source water availability is constrained. In mountain communities with dispersed development and storage-dependent distribution systems, maintaining adequate reserves becomes a critical operational objective.

Drought conditions also interact strongly with other hazards, particularly wildfire. Extended dry periods increase vegetation stress, fuel loading, and ignition susceptibility, contributing to elevated wildfire risk.

Wildfire events occurring under drought conditions may further degrade watershed function, reduce infiltration capacity, and impair long-term water supply resilience. Post-fire landscapes frequently exhibit increased runoff, erosion, and sediment transport, compounding drought-related supply challenges.

Operational impacts associated with drought hazards may include mandatory conservation measures, supply restrictions, infrastructure stress, and increased system management complexity. Reduced CAL OES SUBMITTAL - JUNE 2026
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revenues associated with conservation mandates may affect financial stability, while increased operational costs related to pumping, monitoring, and treatment adjustments may strain budget resources. These dynamics highlight the interconnected nature of hydrologic, operational, and economic resilience.

Climate variability projections for California indicate the potential for more frequent and more severe drought cycles, increasing the long-term relevance of water supply planning and adaptive management strategies. Rising temperatures, shifting precipitation patterns, and altered hydrologic responses may intensify both drought duration and severity. For HMMWC, drought hazards therefore represent not only a recurring operational challenge but also a central driver of long-term system planning.

Table 7-5: Drought Classifications and Impacts
Category Description Possible Impacts
D0 Abnormally
Dry
▪ Soil is dry; irrigation delivery begins early
▪ Dryland crop germination is stunted
▪ Active fire season begins
D1 Moderate
Drought
▪ Dryland pasture growth is stunted; producers give supplemental feed to cattle ▪ Landscaping and gardens need irrigation earlier; wildlife patterns begin to change ▪ Stock ponds and creeks are lower than usual
D2 Severe
Drought
▪ Producers increase water efficiency methods and drought-resistant crops ▪ Grazing land inadequate
▪ Fire season is longer, with high burn intensity, dry fuels, and large fire spatial extent, more fire crews on staff
▪ Lake- and river-based tourism declines; boat ramps close ▪ Trees are stressed; plants increase reproductive mechanisms; wildlife diseases increase
▪ Water temperatures increase; programs to divert water to protect fish begin ▪ River flows decrease; reservoir levels are low and banks are exposed D3 Extreme
Drought
▪ Federal water is not adequate to meet irrigation contracts; extracting supplemental groundwater is expensive
▪ Fire season lasts year-round; fires occur in typically wet parts of the state; burn bans are implemented
▪ Ski and rafting business are low; mountain communities suffer ▪ Low water levels impede fish migration and cause lower survival rates ▪ Wildlife encroaches on developed areas; little native food and water is available for bears, which hibernate less
▪ Water sanitation is a concern; reservoir levels drop significantly; surface water is nearly dry; flows are very low; water theft occurs
▪ Livestock need supplemental feed, cattle and horses are sold; little pasture remains ▪ Well and aquifer levels decrease; homeowners drill new wells CAL OES SUBMITTAL - JUNE 2026
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Category Description Possible Impacts
D4 Exceptional
Drought
▪ Fire season is very costly; number of fires and areas burned are extensive ▪ Many recreational activities are affected
▪ Fields are left fallow; orchards are removed; vegetable yields are low; honey harvest is small; agricultural unemployment is high, food aid is needed ▪ Fish rescue and relocation begin; pine beetle infestation occurs; forest mortality is high; wetlands dry up; wildlife death is widespread; algae blooms appear ▪ Poor air quality affects health: greenhouse gas emissions increase as hydropower production decreases; West Nile outbreaks rise
▪ Water shortages are widespread; surface water is depleted; federal irrigation water deliveries are curtailed; water prices are extremely high; wells are dry, more and deeper wells are drilled; water quality is poor
Source: Adapted from U.S. Drought Monitor Drought Classifications and Impacts Figure 7-15: Drought Severity Timeline 2000-2026
Severe Weather Hazard
Severe weather hazards affecting the HMMWC service area include extreme heat, high wind events, heavy rainfall, and occasional winter snow and freeze conditions. Due to the mountainous terrain, elevation variability, and rural development pattern, weather-related hazards within the service area often manifest differently than in valley environments. Localized microclimates, steep slopes, and vegetation-dominated landscapes can amplify both the direct and secondary impacts of severe weather events.

Severe weather conditions primarily function as stressors that influence water demand, infrastructure reliability, watershed stability, and emergency response conditions. These hazards are closely interconnected with other risks affecting the region, particularly wildfire, drought, erosion, and power disruptions. Evaluating severe weather within the hazard mitigation framework provides important context for understanding system vulnerabilities, operational constraints, and resilience planning considerations.

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Heavy Rainfall & Storm Events
Although drought conditions are common, California increasingly experiences episodic, high-intensity rainfall events. Atmospheric river systems can deliver large volumes of precipitation over short durations, contributing to urban flooding, roadway impacts, and localized drainage failures.

Heavy rainfall and storm events represent a recurring severe weather hazard within the HMMWC service area. The Mediterranean climate characteristic of Napa County produces highly seasonal precipitation patterns, with the majority of annual rainfall occurring during winter months. While most seasonal storms are beneficial for reservoir recharge and watershed recovery, episodic high-intensity rainfall events may generate hazardous conditions, particularly within mountainous terrain.

The steep slopes, confined drainage corridors, and variable soil conditions present throughout the Howell Mountain region increase sensitivity to storm-related impacts. Intense rainfall may saturate soils, reduce slope stability, and trigger localized landslides, debris flows, and erosion events. These processes may damage pipelines, access roads, reservoirs, and appurtenant facilities. Stormwater runoff may also transport sediment, organic material, and debris into surface water sources, affecting raw water quality and treatment operations. In post-wildfire landscapes, storm-related hazards may be amplified due to vegetation loss, hydrophobic soils, and increased erosion susceptibility.

Heavy rainfall events may also influence water system operations through flooding, power disruptions, and infrastructure stress. Although widespread riverine flooding is less common in elevated mountain environments, localized flooding may occur along drainage pathways, culverts, and low-lying infrastructure corridors. Storm conditions frequently coincide with high winds and falling vegetation, increasing the potential for roadway obstructions and electrical outages. Power interruptions may affect pumping, treatment, and monitoring systems, thereby influencing operational reliability.

Despite these risks, storm events also play a critical role in regional water supply sustainability. Seasonal precipitation replenishes reservoirs, supports watershed recovery, and restores soil moisture conditions following extended dry periods. However, increasing climate variability, including projections for more intense storm systems and altered precipitation patterns, introduces greater uncertainty into watershed behavior and infrastructure performance. Periods of prolonged drought followed by intense rainfall may increase the likelihood of erosion, slope instability, and sediment transport.

Strong Winds
High wind events represent a significant severe weather hazard within the HMMWC service area. The mountainous terrain, elevated ridgelines, and exposure to regional weather patterns contribute to periodic wind conditions capable of producing both direct and cascading impacts. Wind events may occur in association with winter storm systems, frontal passages, and seasonal offshore wind patterns, each presenting distinct operational and hazard implications.

High winds pose several risks to water system infrastructure and operations. Strong wind conditions may result in downed trees, falling branches, and windborne debris capable of damaging above-ground facilities, CAL OES SUBMITTAL - JUNE 2026
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electrical components, communication systems, and access routes. Buried infrastructure, while less directly exposed, may be affected by secondary impacts such as uprooted vegetation, slope destabilization, or debris movement. Roadway obstructions caused by fallen trees or limbs may restrict access to reservoirs, treatment facilities, pump stations, and distribution assets, potentially delaying maintenance or emergency response activities.

Power reliability is particularly sensitive to high wind events. Wind conditions frequently contribute to electrical outages through damage to transmission lines, poles, and distribution equipment. In wildfireprone regions such as Napa County, high wind conditions may also trigger PSPS events intended to reduce ignition risks. Power disruptions may affect pumping systems, treatment operations, telemetry equipment, and system monitoring functions, introducing operational challenges and reducing system flexibility during severe weather periods.

High wind hazards are strongly interconnected with wildfire risk. Wind-driven fire behavior is a welldocumented characteristic of major wildfire events within Napa County and surrounding regions. High winds may accelerate fire spread, increase ember transport, and intensify fire severity, thereby increasing the potential for damage to watershed lands, reservoirs, pipelines, and storage facilities. Extended wind events combined with dry vegetation and elevated temperatures may therefore amplify regional wildfire conditions.

Environmental impacts associated with high wind events may include increased tree fall, vegetation damage, and localized erosion. Wind-related disturbances to forested landscapes may alter watershed stability, increase debris loading, and affect drainage patterns. These effects may influence both infrastructure vulnerability and raw water quality conditions.

Climate Change Hazard
Average annual temperatures across most of California have already increased by more than 1°F, with some areas experiencing rises of over 2°F when comparing the 1901–1960 average to that of 1986–2016. Daily maximum temperatures, a key indicator of extreme heat, are projected to increase by 4.4°F to 5.8°F by 2050 and by 5.6°F to 8.8°F by 2100. Heat waves that impact public health, known as heat-health events, are also expected to intensify across the state. By 2050, these events are projected to last up to two weeks longer in the Central Valley and occur four to ten times more often in the Northern Sierra region (California Natural Resources Agency, 2022).

California is already experiencing significant impacts from climate change, including prolonged drought, a lengthened wildfire season, increased coastal flooding and erosion, and widespread tree mortality. The state has observed rising average temperatures, more extreme heat days, fewer cold nights, a longer growing season, and shifts in the water cycle, with less winter precipitation falling as snow. In addition, summertime fog has declined by approximately 33%, and both snowmelt and rainwater runoff are occurring earlier in the year (Cal OES, 2018).

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Long-term trends indicate a 12% to 20% decline in fog across California from 1900 through projections to 2070. Climate experts suggest that warming temperatures reduce the ability of air masses to cool enough to produce fog, which plays a critical role in supporting California’s ecosystems (Grantham, Teodore; University of California, Berkeley, 2018).

Climate change represents a long-term stressor that influences the frequency, intensity, and interaction of hazards affecting the HMMWC service area. Observed and projected climate trends throughout California indicate rising average temperatures, increased variability in precipitation patterns, more frequent extreme heat events, and a greater likelihood of prolonged drought conditions. These changes introduce evolving risks that directly affect water supply reliability, infrastructure performance, watershed stability, and overall system resilience.

Temperature increases are among the most significant climate-related factors affecting the region. Rising temperatures may contribute to higher evapotranspiration rates, reduced soil moisture retention, and increased reservoir evaporation. These processes may intensify drought severity, reduce effective water storage capacity, and increase system demand, particularly during extended warm-season periods.

Elevated temperatures may also exacerbate water quality challenges by influencing constituent concentrations, biological activity, and disinfection byproduct formation within storage and treatment systems.

Changes in precipitation patterns further complicate water resource management. Climate projections suggest increasing variability characterized by longer dry periods punctuated by more intense storm events. Reduced snowpack, altered runoff timing, and shifts in seasonal rainfall distribution may affect watershed recharge dynamics and reservoir inflows. Periods of prolonged drought followed by highintensity rainfall may increase the potential for erosion, sediment transport, slope instability, and infrastructure stress. These hydrologic shifts introduce greater uncertainty into long-term water supply planning and operational management.

Climate change also amplifies wildfire risk within the HMMWC service area. Warmer temperatures, extended dry seasons, and vegetation stress contribute to increased fuel loading, reduced live fuel moisture, and heightened ignition susceptibility. Wildfire events may produce both immediate infrastructure impacts and long-term watershed disturbances affecting water quality, sedimentation rates, and hydrologic function. Post-fire landscapes may exhibit increased runoff, erosion, and contaminant transport, compounding operational challenges.

Severe weather hazards are similarly influenced by changing climate conditions. Increasing frequency and intensity of extreme heat events may elevate peak water demand and strain infrastructure systems. More intense storm systems may increase risks associated with flooding, erosion, and slope failure. Variability in winter weather patterns may alter watershed recovery processes and reservoir recharge behavior.

Collectively, these factors illustrate the interconnected nature of climate-driven hazards.

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management, and operational flexibility remain central to long-term adaptation strategies. Mitigation considerations include maintaining adequate storage capacity, enhancing system redundancy, integrating climate projections into capital planning, and supporting conservation measures designed to moderate demand during periods of stress.

7.5.3 Climate Change Impacts & Vulnerable Populations
Climate change introduces compounding stressors that may disproportionately affect vulnerable populations within the HMMWC service area. While climate-related impacts influence the entire community, certain groups may experience heightened sensitivity due to age, health status, mobility limitations, economic conditions, or housing characteristics. Understanding these differential effects is essential for evaluating risk, supporting equitable resilience, and maintaining reliable utility service under changing environmental conditions.

Increasing temperatures represent one of the most significant climate-driven factors affecting vulnerable populations. More frequent and prolonged extreme heat events may elevate health risks, particularly for elderly individuals, young children, and persons with pre-existing medical conditions. Reliable potable water becomes critically important during heat events to support hydration, sanitation, and cooling needs.

Disruptions to water service or reduced system capacity during high-demand periods may therefore produce disproportionate consequences for individuals with greater physiological sensitivity or limited adaptive resources.

Climate change may also intensify drought conditions, influencing both water availability and affordability considerations. Extended drought periods may necessitate conservation measures, demand restrictions, and rate adjustments that affect household water use patterns. While many households may adapt through behavioral or technological changes, lower-income residents or individuals with fixed incomes may face increased challenges associated with rising utility costs, landscape modification expenses, or infrastructure repair needs. Water shortages may further affect households reliant on consistent water access for medical, sanitation, or caregiving purposes.

Wildfire risk, which is strongly influenced by climate conditions, presents additional implications for vulnerable populations. Increased wildfire frequency and severity may result in evacuation events, property damage, prolonged displacement, and degraded air quality. Individuals with mobility limitations, disabilities, or access and functional needs may face elevated challenges during evacuations and recovery processes. Post-fire disruptions to water quality, infrastructure, or power systems may further affect households with limited capacity to manage extended service interruptions.

Severe weather variability may also introduce indirect effects. Heavy rainfall following prolonged dry periods may increase erosion, slope instability, and infrastructure disruptions that influence service reliability. Power outages associated with heat events, storms, or wildfire prevention measures may affect pumping and treatment operations. Vulnerable populations may be particularly sensitive to cascading utility disruptions involving water, power, and transportation systems.

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Housing characteristics further shape vulnerability under climate change conditions. Residential structures located within wildfire-prone or terrain-sensitive areas may face elevated exposure to hazard impacts.

Homeowners may encounter increasing insurance costs, mitigation expenses, and rebuilding challenges following hazard events. Renters may experience displacement or reduced housing stability in postdisaster environments. These dynamics influence both household resilience and community recovery capacity.

Although demographic indicators within the HMMWC service area suggest relatively lower overall social vulnerability compared to more densely urbanized regions, climate change functions as a hazard multiplier that may amplify existing sensitivities. Adaptive capacity is influenced not only by income or ownership patterns but also by infrastructure reliability, mobility, health conditions, and access to resources.

Maintaining water system resilience, supporting clear communication strategies, and integrating climate considerations into planning efforts are therefore critical for protecting vulnerable populations.

7.5.4 Hazard Problem Statements
As part of the mitigation action identification process, the Planning Committee for each jurisdiction identified areas of concern (aka problem statements) for their respective facilities based on the risk assessment and vulnerability analysis, utilizing the RAMP mapping and static snapshot maps. Problem statements focused on the impact, victim, or threat that the hazard could create in the jurisdiction, as described in Table 7-6. Identifying common issues and weaknesses through these problem statements assisted the planning group in understanding the realm of resources needed for mitigation.

The goal is to have at least one mitigation action for every problem statement. Projects or actions have been developed to mitigate each problem identified. See Table 7-8 for a full list of mitigation actions and corresponding problem statements that they address. Each problem statement is coded with a problem number for cross-referencing between Table 7-6 and Table 7-8 Table 7-6: HMMWC Hazard Problem Statements
Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-CCHMMWC-22Climate
Change
Threat Howell
Mountain
Mutual
Water
Company
Climate change is increasing the frequency
and severity of multiple hazard affecting
HMMWC, including drought, severe weather,
and wildfire.
ma-CC-HMMWC119, ma-AHHMMWC-112, maFL-HMMWC-118,
ma-DR-HMMWC114, ma-WFHMMWC-246,
ma-WF-HMMWC115
ps-DFHMMWC-34Dam Failure Impact Howell
Mountain
Mutual
Water
Company
HMMWC has multiple small reservoirs in steep
terrain; dam failure could release water and
debris into downstream drainages, damaging
infrastructure and roads.
ma-FL-HMMWC118, ma-DF-NCo120
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-DFHMMWC-35Dam Failure Impact Howell
Mountain
Mutual
Water
Company
Failure of Friesen Lakes dam could result in
downstream flooding with risk to life, property,
and infrastructure.
ma-CC-HMMWC119, ma-DF-NCo120, ma-FLHMMWC-118
ps-DFHMMWC-36Dam Failure Impact Howell
Mountain
Mutual
Water
Company
The Treatment Plant is located in a dam
inundation zone and, if impacted, would result
in the loss of ability to provide water.
ma-FL-HMMWC118, ma-DF-NCo120
ps-DFHMMWC-40Dam Failure Victim Howell
Mountain
Mutual
Water
Company
A dam failure could disrupt water supply to
~1,500 residents and damage access to the
treatment plant.
ma-AH-HMMWC117, ma-DF-NCo120, ma-FLHMMWC-118
ps-DFHMMWC-382Dam Failure Threat Howell
Mountain
Mutual
Water
Company
The final Emergency Action Plans (EAPs) for
high-hazard dams that were previously
developed are not currently available, limiting
their use in disaster planning.
ma-FL-HMMWC118
ps-DFHMMWC-383Dam Failure Impact Howell
Mountain
Mutual
Water
Company
Lack of warning gauges and monitoring
around dams reduces detection of overtopping,
structural issues, or storm-related failures.
ma-FL-HMMWC118, ma-AHHMMWC-112
ps-DRHMMWC-48Drought Impact Howell
Mountain
Mutual
Water
Company
HMMWC’s reservoirs are in a small watershed
highly vulnerable to multi-year drought,
requiring staged water restrictions and risking
depletion of both lake and well supplies.
ma-DR-HMMWC114, ma-WFHMMWC-115
ps-DRHMMWC-51Drought Impact Howell
Mountain
Mutual
Water
Company
Drought conditions could reduce available
water pressure and volume for firefighting
operations, limiting suppression effectiveness
during wildfires.
ma-WF-HMMWC115
ps-DRHMMWC-52Drought Victim Howell
Mountain
Mutual
Water
Company
Extreme drought may force reliance on
trucked water if wells and reservoirs fall below
operational levels.
ma-DR-HMMWC114, ma-WFHMMWC-115
ps-DRHMMWC-53Drought Victim Howell
Mountain
Mutual
Water
Company
Customers face service limitations during
long-term drought, including higher
surcharges, reduced availability, and tighter
restrictions.
ma-DR-HMMWC114, ma-WFHMMWC-115
ps--HMMWC380Drought Impact Howell
Mountain
Mutual
Water
Company
Lack of automated lake-level monitoring limits
real-time drought management and early
warning capabilities.
ma-WF-HMMWC115, ma-FLHMMWC-118, maAH-HMMWC-112
ps--HMMWC381Drought Impact Howell
Mountain
Mutual
Water
Company
Public education and outreach requirements
during prolonged drought events place
additional strain on HMMWC’s small team and
resources.
ma-DR-HMMWC114, ma-WFHMMWC-115
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-EQHMMWC-93Earthquake Threat Howell
Mountain
Mutual
Water
Company
Aging critical facilities are vulnerable to
seismic damage, threatening water production
and distribution.
ma-EQ-HMMWC111
ps-EQHMMWC-94Earthquake Impact Howell
Mountain
Mutual
Water
Company
Severe earthquakes could compromise the
structural integrity and trigger failure of
upstream dams, leading to downstream
flooding, loss of life, and disruption of water
service for HMMWC customers particularly if
aging earthen structures are not seismically
retrofitted.
ma-EQ-HMMWC111, ma-FLHMMWC-118
ps-EQHMMWC-97Earthquake Victim Howell
Mountain
Mutual
Water
Company
Earthquakes may disrupt service to customers
and hinder emergency response due to narrow
mountain roads and facility inaccessibility.
ma-EQ-HMMWC111, ma-WFHMMWC-115
ps-EQHMMWC-101Earthquake Threat Howell
Mountain
Mutual
Water
Company
Warning signals/alarms from the treatment
plant will not function if there is no cell phone
service due to a severe earthquake.
ma-AH-HMMWC112, ma-AHHMMWC-116, maEQ-HMMWC-111
ps-EQHMMWC-374Earthquake Impact Howell
Mountain
Mutual
Water
Company
Pipelines in steep terrain may experience
earthquake-induced slope failure, causing
leaks, breaks, and access issues despite no
historical damages to date.
ma-EQ-HMMWC111
ps-EQHMMWC-375Earthquake Threat Howell
Mountain
Mutual
Water
Company
Lack of seismic retrofits for tanks and pump
houses increases vulnerability to strong
shaking
ma-EQ-HMMWC111
ps-SWHMMWC-376Severe
Weather
Impact Howell
Mountain
Mutual
Water
Company
Severe weather events (windstorms and heavy
rain) cause power failures at the water
treatment plant and well sites, risking loss of
water production and system
depressurization.
ma-AH-HMMWC112
ps-SWHMMWC-377Severe
Weather
Impact Howell
Mountain
Mutual
Water
Company
Heavy rain events can trigger landslides and
blocked access roads, hindering staff’s ability
to reach reservoirs, dams, and treatment
facilities.
ma-EQ-HMMWC111, ma-WFHMMWC-246
ps-SWHMMWC-378Severe
Weather
Victim Howell
Mountain
Mutual
Water
Company
Power and water outages during severe
weather events disproportionately affect
vulnerable populations served by HMMWC.
ma-AH-HMMWC112
ps-SWHMMWC-379Severe
Weather
Threat Howell
Mountain
Mutual
Water
Company
Lack of redundant power and monitoring
systems leaves critical facilities exposed
during storm-related outages.
ma-AH-HMMWC112, ma-FLHMMWC-118
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-WFHMMWC-201Wildfire Impact Howell
Mountain
Mutual
Water
Company
Wildfire impacts treatment plant operations,
including from power outages and PSPS
events, and creates operational hazards for
chemical storage, pump houses, and above
ground assets.
ma-WF-HMMWC115, ma-WFHMMWC-246,
ma-AH-HMMWC112
ps-WFHMMWC-202Wildfire Impact Howell
Mountain
Mutual
Water
Company
Wildfires degrade watershed quality, damage
water infrastructure, and block access roads,
interrupting service and reducing available
firefighting water.
ma-AH-HMMWC117, ma-WFHMMWC-246
ps-WFHMMWC-205Wildfire Impact Howell
Mountain
Mutual
Water
Company
Wildfires could impact communications
systems such as knocking out cell towers.
ma-AH-HMMWC116, ma-AHHMMWC-112, maFL-HMMWC-118
ps-WFHMMWC-372Wildfire Threat Howell
Mountain
Mutual
Water
Company
Limited staffing and reliance on manual
operations may delay post-wildfire system
inspections and emergency response.
ma-FL-HMMWC118, ma-WFHMMWC-246
ps-WFHMMWC-373Wildfire Threat Howell
Mountain
Mutual
Water
Company
Coordination gaps with emergency responders
during wildfire events may hinder timely
response, especially in areas with poor access
or signage.
ma-WF-HMMWC115
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7.6 Mitigation Strategy
This section provides the framework for how HMMWC will reduce hazard risk within its jurisdiction while supporting the broader goals of the Napa County MJHMP. It includes an overview of existing capabilities, opportunities to strengthen resilience, and the district’s prioritized mitigation actions. Together, these elements demonstrate how HMMWC integrates hazard awareness into its planning and development processes while contributing to a coordinated countywide approach.

Within the Napa County MJHMP, the mitigation strategy serves as the roadmap for future hazard mitigation efforts. For HMMWC, the strategy outlined in this annex reflects the outcomes of the countywide planning process while also addressing the district’s unique risks, priorities, and community needs. The strategy is designed to reduce vulnerabilities identified in the risk assessment, including the problem statements developed for wildfire, earthquakes and severe weather, and climate change.

Mitigation actions identified in this annex include both policy-based and project-based initiatives, with an emphasis on integrating resilience into land use planning, infrastructure investments, and community programs. Actions are structured to align with FEMA’s requirements and to coordinate with existing district, county, and regional planning mechanisms. Each action identifies responsible parties, potential funding sources, and the resources needed for implementation.

For HMMWC, this strategy provides a framework for strengthening resilience by combining district-led initiatives, such as infrastructure improvements, and community preparedness, with regional coordination through the MJHMP. By advancing these efforts in alignment with the Contingency Plan and other local planning documents, HMMWC enhances its ability to reduce hazard risk while supporting long-term community safety, sustainability, and economic stability.

The subsections that follow describe these elements in detail:
▪ Sections 7.6.1, Capabilities and Opportunities, provides a summary of the company’s capacity to address natural hazards.
▪ Section 7.6.2, Mitigation Action Plan, presents HMMWC’s prioritized actions to guide implementation in coordination with countywide strategies. ▪ Section 7.6.3, Status of Previous Mitigation Actions, provides a summary of all previous actions and their current status, whether completed, cancelled, or revised.

Aligning the Action Plan
This section connects HMMWC’s mitigation actions with its existing capabilities and areas for growth.

Capability assessments are a required element of hazard mitigation planning under the Disaster Mitigation Act of 2000 and FEMA’s 2023 guidance, ensuring that actions are realistic, achievable, and aligned with available resources.

The section begins with a summary of HMMWC’s capabilities across four areas: planning and regulatory, administrative and technical, fiscal, and education and outreach. This overview highlights the tools and CAL OES SUBMITTAL - JUNE 2026
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strengths that the district already uses to reduce hazard risk. The section then provides a detailed analysis of each capability area, identifying both current practices and opportunities to expand resilience.

7.6.1 Capabilities & Opportunities
This section provides a detailed assessment of the company’s current capabilities to support hazard mitigation, as well as future opportunities. This consists of describing how HMMWC is planning for hazards and growth and a summary of its existing capabilities and the potential for enhancement.

Planning for Hazards & Growth
Planning for hazards and future growth within the HMMWC service area requires balancing long-term water supply reliability, infrastructure resilience, environmental conditions, and development patterns characteristic of a rural mountain community. Unlike urbanized jurisdictions experiencing rapid expansion, growth within the HMMWC service boundary is generally incremental and closely tied to parcellevel development, residential improvements, and post-hazard reconstruction. Nevertheless, hazard exposure, resource constraints, and climate variability necessitate proactive planning strategies to maintain system sustainability.

Hazard conditions represent a defining influence on infrastructure planning and operational decisionmaking. The service area’s elevated wildfire risk, recurring drought cycles, seismic exposure, and terrainrelated vulnerabilities require that hazard considerations be integrated into capital improvement planning, system maintenance, and water resource management. Infrastructure investments, including storage expansion, pipeline replacement, and treatment upgrades, function not only as operational improvements but also as mitigation measures designed to reduce system vulnerability. Planning frameworks must therefore account for both routine service demands and stress conditions associated with hazard events.

Water supply variability is central to growth and development planning. HMMWC’s reservoir- and watershed-dependent system is inherently sensitive to precipitation patterns, drought severity, and climate-driven hydrologic changes. Future connections, system expansions, and demand projections must consider long-term supply reliability, storage capacity, and operational flexibility. Conservation policies and drought response measures serve as essential planning tools that support system stability during periods of reduced availability. This resource-dependent planning environment differs from systems with extensive interconnections or diversified supply portfolios.

Growth trends within the service area are strongly influenced by geographic constraints and hazard exposure. Steep slopes, limited developable land, and infrastructure extension challenges naturally moderate development intensity. In hazard-prone mountain environments, redevelopment and reconstruction following wildfire or storm-related events may represent a more significant driver of construction activity than net-new growth. Planning for these conditions requires evaluating not only anticipated demand increases but also potential fluctuations associated with housing loss, rebuilding cycles, and temporary population shifts.

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Hazard mitigation planning further supports long-term growth sustainability. By identifying vulnerabilities, assessing risk, and prioritizing resilience investments, HMMWC strengthens its capacity to accommodate future demand while reducing exposure to system disruptions. Infrastructure durability, storage adequacy, water quality protection, and operational continuity remain critical objectives. Planning for hazards and growth is therefore not solely a matter of accommodating expansion but rather ensuring that future conditions do not compromise system reliability or community resilience.

Climate change introduces an additional layer of planning complexity. Increasing temperature trends, evolving precipitation variability, and intensifying severe weather patterns may influence both water demand and hazard frequency. Adaptive management strategies, infrastructure modernization, and demand management policies provide mechanisms for addressing uncertainty. Long-term planning efforts must remain flexible, allowing the company to respond to changing environmental conditions while maintaining financial and operational stability.

Development & Hazard Considerations
Development within the HMMWC service area is strongly influenced by the region’s mountainous terrain, environmental constraints, and elevated exposure to natural hazards. The rural character of the community, combined with steep slopes, forested landscapes, and limited infrastructure corridors, shapes both the pattern and pace of growth. Unlike urbanized areas characterized by concentrated expansion, development within the service boundary generally occurs incrementally through parcel-level construction, residential improvements, and redevelopment activities.

Hazard exposure represents a defining factor affecting development feasibility and long-term sustainability. The service area’s location within a high wildfire risk environment introduces considerations related to defensible space, vegetation management, emergency access, and structural resilience. Wildfire hazards influence building design, site planning, insurance conditions, and infrastructure protection measures. Development decisions must therefore account for both life safety and the protection of critical lifeline systems, including water storage, treatment, and distribution assets.

Terrain-related hazards further shape development conditions. Steep slopes, variable soil stability, and localized drainage patterns contribute to potential risks associated with landslides, erosion, and stormwater impacts. Site grading, foundation design, and infrastructure placement must consider slope stability and runoff behavior, particularly during heavy rainfall events. Disturbance of natural slopes may alter drainage conditions and increase susceptibility to localized ground movement, creating long-term maintenance and risk management challenges.

Seismic hazards introduce additional development considerations. Earthquake-induced ground shaking may affect structures, buried utilities, storage facilities, and mechanical systems. Secondary effects, including slope failures and localized ground deformation, may compound infrastructure vulnerability.

Development patterns in mountainous environments must therefore integrate structural design standards and site-specific geotechnical evaluations to reduce seismic risks.

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Water supply reliability represents a central constraint influencing development potential. HMMWC’s reservoir- and watershed-dependent system is inherently sensitive to precipitation variability, drought cycles, and climate-driven hydrologic changes. New connections, demand increases, and infrastructure extensions must be evaluated within the context of long-term supply sustainability, storage capacity, and operational flexibility. Resource limitations associated with drought hazards may influence growth trajectories, conservation requirements, and system expansion decisions.

Hazard conditions also affect redevelopment and reconstruction dynamics. Historical wildfire events within Napa County have demonstrated the potential for structural losses, prolonged displacement, and rebuilding cycles within the Howell Mountain region. Post-disaster redevelopment may introduce updated building standards, infrastructure improvements, and hazard mitigation measures. These processes may alter demand patterns, infrastructure needs, and long-term community characteristics.

Climate change further amplifies the interaction between development and hazard conditions. Increasing temperature trends, evolving precipitation variability, and intensified severe weather patterns may influence both hazard frequency and infrastructure performance. Development planning must therefore consider not only existing hazard exposures but also projected future conditions that may affect water demand, watershed stability, and system resilience.

Capabilities & Opportunities Assessment
To develop a realistic and actionable mitigation strategy, it must account for existing jurisdictional capabilities and what future opportunities there are to enhance those capabilities for purposes of hazard mitigation. This section provides an assessment of the district’s existing capabilities and future opportunities, including planning and regulatory, administrative and technical, fiscal, and public outreach and education capabilities. This assessment also identifies opportunities to integrate this MJHMP into future planning, policies, or programs to weave mitigation efforts into daily operations and address hazard problems wholistically. Capabilities are categorized into four groups and include various mechanisms. ▪ Planning and Regulatory Capabilities: Existing long-range plans, emergency response plans, hazard-specific plans, land use policies, and building and development standards. ▪ Administrative and Technical Capabilities: Available expertise in emergency services, engineering, grant management, and community planning.
▪ Fiscal Capabilities: Budgetary capacity, taxing authority, grants, and other funding mechanisms that can support mitigation projects.
▪ Outreach and Education Capabilities: Existing programs for providing technical assistance, community education, public warnings, and stakeholder engagement.

A full description of the process used to develop the capabilities assessment is provided in Volume 1, Section

2.3.3. This capabilities and opportunities assessment for HMMWC lists the various types of capabilities along with how they have been, currently are, or will in the future be integrated into hazard mitigation planning efforts.

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The three “HMP Integration” columns that identify the capability’s status and usage are color-coded with green, yellow, or orange shading to communicate the following:
▪ Status: If the capability is present at all and what level of use it has generally. ▪ Current Mitigation Use: If the capability is currently being used in mitigation efforts, specifically, and at what level.
▪ Future Opportunity: If there is a future opportunity to integrate the capability into mitigation efforts and at what level.

Summary of Capabilities & Opportunities
This Capabilities and Opportunities Assessment for HMMWC summarizes the various types of capabilities it has for hazard mitigation currently. The assessment also identifies opportunities to integrate, expand, and improve the agency’s capabilities for future hazard mitigation. Table 7-7 provides a comprehensive list of capabilities and identifies the current status, current mitigation use, and future opportunities.

Planning & Regulatory
HMMWC’s planning and regulatory capabilities reflect its role as a small, member-governed mutual water company operating in a hazard-prone mountain environment. Hazard mitigation is primarily addressed through operational needs, regulatory compliance, targeted projects, and Board-directed actions rather than through comprehensive long-range planning programs or a formal Capital Improvements Program.

Recent improvements, including backup generator installations, VFD retrofits, system hardening, defensible space clearing, vegetation management, and fuel reduction work, demonstrate the company’s ability to implement practical resilience measures. These efforts help reduce vulnerability to wildfire, power outages, seismic impacts, and other operational disruptions, although they are generally project-based rather than part of formal hazard-specific plans.

Drought planning is one of HMMWC’s strongest capabilities. The adopted 2022 Drought and Water Shortage Contingency Plan provides a structured five-stage response system tied to raw water storage levels and is used to guide conservation, demand management, and public communication during water shortages.

HMMWC does not maintain formal stormwater, floodplain, groundwater, climate action, FireWise, seismic modernization, or CWPP programs, as many of these functions fall outside the company’s scope or capacity.

However, existing customer communication tools, including billing notices, hotline messaging, regulatory reporting, and service updates, provide a foundation for expanding wildfire, drought, and emergency preparedness outreach in the future.

Future integration of the MJHMP will occur through various processes and mechanisms outlined across multiple mitigation actions (Table 7-8). Key opportunities for future hazard mitigation integration with HMMWC’s existing planning mechanisms include incorporating updated risk assessment, hazard-specific vulnerability findings, and projected climate change impacts into the Dam Failure Planning & Warning CAL OES SUBMITTAL - JUNE 2026
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System Upgrades (ma-FL-HMMWC-118), and the Water Conservation Outreach & Education (ma-DRHMMWC-114).

Administrative & Technical
HMMWC’s administrative and technical capacity reflects the lean structure of a small, member-governed mutual water utility. Core functions focus on system operations, regulatory compliance, customer service, and infrastructure maintenance, while specialized engineering, planning, GIS, grant, and technical services are generally provided through outside consultants or partner agencies.

The company does not have a dedicated emergency manager, in-house civil engineer, GIS specialist, or outreach staff. Emergency coordination is likely handled by the General Manager, system operators, or Board leadership, while engineering, mapping, and hazard analysis are supported externally. This structure provides access to needed expertise but may limit internal capacity for advanced preparedness planning, rapid technical evaluation, and structured hazard education.

Customer outreach is conducted through billing notices, regulatory reporting, hotline messaging, and service updates, with expanded communication during drought or operational events. HMMWC has also demonstrated grant and funding coordination capacity by securing outside support for mitigation and infrastructure projects, although grant administration is largely supported through outside assistance.

The ongoing recruitment of a General Manager represents an important opportunity to strengthen organizational capacity. Once filled, this position is expected to improve operational oversight, infrastructure planning, financial management, and hazard preparedness, all of which are critical for a small utility operating in a hazard-prone environment.

Warning Systems & Services
HMMWC’s warning and notification capabilities are primarily supported through regional and county-level emergency alert systems rather than internally maintained warning platforms. As a small mutual water company, HMMWC does not operate a centralized public safety alert system or dedicated hazard warning interface for its service area.

Customer communications are generally handled through billing notices, regulatory reporting, hotline messaging, and service-related updates. While these tools support routine operational communication, they are not designed for real-time emergency warning. Flood, wildfire, earthquake, and landslide alerts are therefore managed through Napa County emergency services, CAL FIRE, Nixle, and other regional or statewide systems.

Wildfire warning is the most relevant alert function for HMMWC customers due to the company’s mountain setting and elevated wildfire exposure. Although HMMWC does not issue wildfire alerts directly, it can use existing customer communication channels to supplement regional messaging with preparedness reminders, conservation advisories, and service-related hazard information. Overall, the company’s CAL OES SUBMITTAL - JUNE 2026
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reliance on external warning systems is consistent with its size and capacity, but opportunities exist to strengthen supplemental customer messaging during hazard events.

Fiscal
HMMWC’s fiscal capabilities are shaped by its status as a private nonprofit mutual benefit corporation and member-owned water utility. The company does not have authority to levy taxes, impose voter-approved assessments, issue general obligation bonds, or collect stormwater fees. As a result, hazard mitigation and infrastructure resilience efforts are funded primarily through water service fees, capital charges, operating revenues, reserve funds, and external grants.

Water service fees support routine operations, regulatory compliance, maintenance, and incremental capital improvements, including backup power, equipment retrofits, system modernization, and infrastructure hardening. However, the small rate base, affordability concerns, drought-related conservation, seasonal demand changes, and hazard disruptions can limit available funding for larger mitigation projects.

HMMWC may collect hookup or connection-related charges that help offset growth-related infrastructure costs, but these are not organized as a formal system development fee program. Debt financing options are limited, making grants and cost-share programs especially important for funding larger resilience projects.

Capital and mitigation decisions are generally guided by operational needs, regulatory compliance, infrastructure condition, available resources, and Board priorities.

Education & Outreach
HMMWC’s education and outreach capabilities are typical of a small, member-governed utility. Customer communication primarily occurs through service updates, billing notices, regulatory reporting, website content, Facebook posts, and drought-related messaging. These tools provide functional outreach channels, but hazard-specific education programs are currently limited.

The company’s website and social media presence offer cost-effective opportunities to expand messaging related to wildfire preparedness, drought conditions, severe weather, seismic resilience, emergency procedures, conservation guidance, and service interruptions. HMMWC does not maintain a dedicated public-facing facility for hazard materials, and participation in formal annual preparedness events has not been documented.

HMMWC can respond to customer inquiries through standard contact channels, but structured hazard assistance or resilience guidance is not formalized. Future coordination with local partners, such as the Angwin Fire Safe Council and Napa County Resource Conservation District, could strengthen outreach related to wildfire risk reduction, defensible space, vegetation management, watershed resilience, erosion control, and emergency water supply considerations.

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ASSESSMENT LEGEND
HMP Integration
Status Current Mitigation Use Future Opportunity
Currently in use or present. Used widely for mitigation. Opportunity to expand and integrate. (Sort of) Seldomly used or limited
presence.

Limited use in mitigation planning. Limited opportunity to expand and integrate. (No) Not present or available. Not used in mitigation planning. No opportunity to expand or integrate.

Table 7-7: HMMWC Capabilities and Opportunities Assessment HMP Integration Notes / Additional Detail
Resource Status
Current
Mitigation
Use
Future
Opportunity
Planning and Regulatory
Capabilities
Hazard Reduction Programs
(Annually Conducted)
Capital Improvements Program
(CIP) or Plan
Green Green Yellow
Recent projects include backup generator
installations, VFD retrofits, and security
reinforcements. Improvements remain
project-based and not part of a structured CIP
Annual Fire Prevention Plan
Green Green Yellow
No formal annual plan, but defensible space
clearing and fuel reduction projects are now
conducted regularly with Cal Fire support.

Seismic Safety Program (Nonstructural)
Yellow Yellow Yellow
Non-structural seismic program still informal,
but VFD retrofits and EAP updates improve
preparedness. Staff rely on outside technical
support.

Earthquake Modernization Plan
(Building Safety) Yellow Yellow Yellow
No formal modernization plan, but
vulnerabilities documented and targeted
retrofits pursued (VFDs, hardening).

Stormwater Management
Program (Annual Inspections) Orange Orange Orange
Stormwater management remains outside
HMMWC’s scope; no systems or inspection
program exist.

Hazard Plans and Programs
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HMP Integration Notes / Additional Detail
Resource Status
Current
Mitigation
Use
Future
Opportunity
Floodplain Response Plan
Orange Orange Orange
No floodplain-specific plan or priority
identified in HMMWC planning documents.

Flood risk not included in drought plan or
breakout discussions.

Community Wildfire Protection
Plan (CWPP)
Orange Orange Orange
HMMWC does not maintain a CWPP. Wildfire
mitigation measures (e.g., vegetation
management) occur, but no formal plan or
CWPP reference exists.

Ground Water Management
Planning / Plans
Orange Orange Orange
HMMWC relies on surface water (Friesen
Lakes). No groundwater management plan or
documentation in drought or strategic
planning.

Climate Action Plan
Orange Orange Orange
No Climate Action Plan has been developed or
referenced. Climate change impacts are noted
generally in hazard discussions but not tied to
a plan.

Drought Mgmt/ Contingency
Plan
Green Green Yellow
Adopted 2022 Drought & Water Shortage
Contingency Plan with five escalating stages.

Actively used for conservation enforcement
and outreach. Expansion limited by staffing
and funding capacity.

FireWise Communities within
District Orange Orange Orange
No evidence of FireWise recognition or active
collaboration. Not mentioned in meetings or
planning documentation.

Hazard-Related Public Outreach
Program
Yellow Yellow Yellow
HHMMWC engages in general outreach (billing
notices, hotline, community events) but lacks
a formal hazard-specific outreach program.

Opportunities exist to formalize wildfire and
drought education.

Administrative and
Technical
Staff Capacity
Emergency Manager
Orange Orange Orange
No formal emergency manager role was
identified. Emergency coordination likely falls
to General Manager or shared services.

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HMP Integration Notes / Additional Detail
Resource Status
Current
Mitigation
Use
Future
Opportunity
Civil Engineer
Orange Orange Orange
No in-house civil engineer. Engineering
support is contracted out, typically to
consultants.

Dedicated Public Outreach
Personnel
Orange Orange Orange
Outreach occurs periodically (e.g., during
drought conditions) but no designated staff is
assigned to education or hazard outreach
roles.

GIS Specialist and Capability
Orange Orange Orange
GIS is not internally maintained. Mapping
support is likely done through external
vendors, and or County of Napa.

Grant Manager, Writer, or
Specialist Yellow Orange Yellow
Measure A funding from Napa County, FEMA
grants; relies on outside assistance for grant
writing and management.

Other
Yellow Yellow Green
HMMWC is recruiting for a General Manager
position. Once filled, this role is expected to
improve daily operations, funding
coordination, and emergency planning
capacity.

Warning Systems/Services
General
Orange Orange Orange No centralized general alert system or dedicated hazard warning page found.

Flood
Orange Orange Orange No flood-specific alert system mentioned in Drought Contingency Plan or minutes
Wildfire
Yellow Yellow Yellow
Wildfire alerts are available through Napa
County, CAL FIRE, and Nixle, but HMMWC has
no system tailored to its service area.

Expansion may include localized outreach or
integration into billing notices.

Geological Hazards
Orange Orange Orange
No seismic or landslide-specific warning
capability identified. Reliance is on county or
regional systems.

Fiscal Capabilities
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HMP Integration Notes / Additional Detail
Resource Status
Current
Mitigation
Use
Future
Opportunity
Financial Resources for
Hazard Mitigation
Levy for Specific Purposes with
Voter Approval Orange Orange Orange HMMWC is a private nonprofit mutual water company and not a taxing authority.

Utilities Fees
Green Green Yellow
Water service fees are collected and may
support hazard-resilient upgrades. Expansion
limited by small rate base and affordability
concerns.

System Development Fee
Yellow Orange Yellow
Not explicitly listed in documentation. Likely
incorporated into hookup or capital fees, but
not a formalized system development fee
structure.

General Obligation Bonds to
Incur Debt Orange Orange Orange HMMWC does not have the legal authority to issue general obligation bonds.

Special Tax Bonds to Incur Debt
N/A N/A N/A HMMWC is ineligible to issue special tax bonds as a private water entity
Withheld Spending in HazardProne Areas Orange Orange Orange No policy framework or prioritization system found.

Stormwater Service Fees
N/A N/A N/A HMMWC is not a stormwater management
agency and does not levy stormwater fees.

Capital Improvement Project
Funding
Green Green Green
CIP-type funding exists through operating
revenue and reserves. Supports upgrades such
as generators, retrofits, and security.

Expansion limited by ratepayer base.

Education / Outreach
Capabilities
Education/Outreach
Resources
Website Dedicated to Hazard
Topics
Yellow Yellow Yellow
Website includes drought updates and general
service info, but limited hazard-specific
content. Could be expanded to cover wildfire,
seismic, and emergency alerts.

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HMP Integration Notes / Additional Detail
Resource Status
Current
Mitigation
Use
Future
Opportunity
Dedicated Social Media
Orange Orange Yellow Limited social media
Hazard Info. Avail. at Library/
Planning Desk Orange Orange Orange No public-facing facility or repository with hazard materials.

Annual Public Safety Events
Orange Orange Orange No record of participation in local emergency preparedness fairs or events.

Ability to Field Public Tech.

Assistance Requests Yellow Yellow Yellow Website allows general inquiries, but not formal hazard-related assistance intake.

Public Safety Newsletters or
Printed Outreach Orange Orange Yellow
No routine safety bulletin or newsletter
program. Potential exists to include hazard
updates in mailings with bills.

Fire Safe Councils
Yellow Yellow Yellow
Angwin area is served by a community-level
Fire Safe Council. No direct HMMWC
involvement but potential exists to collaborate
more formally.

Resource Conservation Districts
Yellow Yellow Yellow Partnership potential with Napa County RCD, but no documented collaboration yet.

Other
Yellow Yellow Green
HMMWC is recruiting for a General Manager
position. Once filled, this role is expected to
improve daily operations, funding
coordination, and emergency planning
capacity.

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7.6.2 HMMWC Mitigation Action Plan
HMMWC’s mitigation
actions were developed
through a collaborative
process informed by the
updated risk
assessment, local
priorities, and extensive
stakeholder
engagement. As part of
this 2026 MJHMP
update, the district
reviewed mitigation
actions from its prior
Local Hazard Mitigation
Plan to determine
which actions to carry
forward, which to
consolidate, and where
entirely new strategies
were required. This
careful evaluation
ensured that the updated action plan builds upon past commitments while also responding to current risks and future challenges. These new actions were crafted to address the district’s highest priority hazards, align with FEMA’s hazard mitigation guidance, and reflect local infrastructure vulnerabilities and water resource challenges. The development of these mitigation strategies marks an important step in integrating resilience into the district’s operations and long-term planning. All mitigation actions are documented in Volume 2, Table 7-8. This careful evaluation ensured that the updated action plan builds upon past commitments while also responding to current risks and future challenges.

The plan addresses HMMWC’s most significant hazards, including wildfire, earthquake, severe weather, and climate change. Each mitigation action is designed to align with FEMA’s hazard mitigation guidance and the requirements of the Disaster Mitigation Act of 2000. Where appropriate, overlapping or redundant actions were consolidated into broader, more comprehensive strategies that improve clarity, increase feasibility, and strengthen regional coordination.

The mitigation action prioritization method used by all participating jurisdictions is described in Volume 1, Section 4. Each action specific to HMMWC is documented in Table 7-8, which identifies the responsible department, implementation timeframe, potential funding sources, and resources required to complete the Figure 7-16: Mitigation Action Number Key
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action. Each action is also assigned a unique alphanumeric identifier (see Figure 7-16) that links the strategy to its associated hazard and supports consistent monitoring and reporting.

HMMWC’s approach recognizes that some hazards are most effectively addressed through regional efforts.

Weather and wildfire risk reduction often extend beyond the district’s boundaries and require collaboration with county, regional, and state partners. By aligning local actions with regional strategies, HMMWC helps to consolidate resources, maximize funding opportunities, and ensure that mitigation projects achieve the greatest benefit for San Pablo Bay, the Napa Valley, and the wider Napa County community.

Collectively, these mitigation actions provide a roadmap for reducing hazard risk, protecting vulnerable populations, and strengthening the long-term resilience of HMMWC.

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Table 7-8: HMMWC Mitigation Action Plan
Mitigation No. Hazard
Type
SubHazardMitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-AHHMMWC-112All Hazard PPRO -
Property
Protection , ES
- Emergency
Services
2020 Howell
Mountain
Mutual
Water
Company
Backup Power
Expansion
Install backup generators, battery storage, or
other power redundancy systems at critical
facilities like the treatment plant and pump
stations.

Engineering Medium High 3-5 Years Project HMGP / BRIC , General Fund
High ps-EQ-HMMWC-101, ps-EQHMMWC-96, ps-WF-HMMWC204, ps-CC-HMMWC-22, psSW-HMMWC-376, ps-SWHMMWC-378, ps-SWHMMWC-379, ps-DFHMMWC-383, ps-DRHMMWC-380, ps-WFHMMWC-201, ps-WFHMMWC-205 ma-DFHMMWC-118Dam
Failure
PRV -
Prevention ,
ES -
Emergency
Services
2020 Howell
Mountain
Mutual
Water
Company
Dam Failure
Planning &
Warning
System
Upgrades
Update as necessary, complete, and file updated
Emergency Action Plans for all reservoirs.

Install real-time water-level sensors, flow
gauges, and other early-warning systems for the
highest priority reservoirs.

Engineering Medium High 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
High ps-DF-HMMWC-34, ps-DFHMMWC-36, ps-EQ-HMMWC94, ps-EQ-HMMWC-100, psDF-HMMWC-35, ps-DFHMMWC-40, ps-DF-HMMWC382, ps-DF-HMMWC-383, psCC-HMMWC-22, ps-SWHMMWC-379, ps-WFHMMWC-372, ps-DRHMMWC-380, ps-WFHMMWC-205 ma-DRHMMWC-114Drought PE&A - Public
Education &
Awareness
2020 Howell
Mountain
Mutual
Water
Company
Water
Conservation
Outreach &
Education
In collaboration with the County, develop a
drought outreach and education program and
regularly conduct water conservation
campaigns with customer incentives.

Administration Low Medium 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Medium ps-DR-HMMWC-48, ps-DRHMMWC-53, ps-DR-HMMWC52, ps-CC-HMMWC-22, ps-DRHMMWC-381 ma-DRHMMWC-115Drought SP - Structural
Projects
2020 Howell
Mountain
Mutual
Water
Company
Emergency
Water &
Supply
Diversification
Evaluate and develop emergency supply options
(interties, tanks, backwash reuse). Install
automated lake-level and well telemetry
systems for drought management.

Engineering High High 1-3 Years Project HMGP / BRIC ,
General Fund
High ps-WF-HMMWC-201, ps-WFHMMWC-206, ps-DRHMMWC-53, ps-DR-HMMWC50, ps-DR-HMMWC-51, ps-WFHMMWC-373, ps-EQHMMWC-97, ps-DR-HMMWC52, ps-DR-HMMWC-48, ps-DRHMMWC-381, ps-DRHMMWC-380, ps-CCHMMWC-22 ma-EQHMMWC-111Earthquake PPRO -
Property
Protection , SP
- Structural
Projects
2020 Howell
Mountain
Mutual
Water
Company
Seismic
Retrofit of
Critical
Facilities &
Infrastructure
Retrofit HMMWC buildings, tanks, pipelines, and
other critical system components to withstand
earthquake shaking. Replace vulnerable pipeline
segments with HDPE/flexible joints. Install
seismic triggers, shutoff valves, and alarms for
tanks and pumps.

Engineering High High 3-5 Years Project HMGP / BRIC ,
General Fund
High ps-EQ-HMMWC-93, ps-EQHMMWC-94, ps-EQ-HMMWC97, ps-EQ-HMMWC-101, psEQ-HMMWC-374, ps-EQHMMWC-375, ps-SWHMMWC-377 ma-WFHMMWC-246Wildfire PRV -
Prevention ,
NRP - Natural
Resource
Protection , SP
- Structural
Projects
2026 Howell
Mountain
Mutual
Water
Company
Fuel
Management
& Post-Fire
Watershed
Protections
Develop a program to conduct regular
defensible-space clearing around facilities and
water assets. Establish procedures to inspect
and install slope stabilization and erosion and
sediment controls in vulnerable areas post-fire
to reduce debris flows and contamination
potential.

Maintenance,
Engineering
Medium High 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-WF-HMMWC-201, ps-WFHMMWC-202, ps-SWHMMWC-377, ps-WFHMMWC-372, ps-CCHMMWC-22 CAL OES SUBMITTAL - JUNE 2026
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7.6.1 Status of Previous Mitigation Actions
In 2020, Howell Mountain Mutual Water Company adopted its previous FEMA-approved HMP. This 2026 MJHMP represents a comprehensive update from that previous plan, as discussed in Volume 1, Section 1.5.

Table 7-9 provides status updates for all of the previous mitigation actions in HMMWC HMP, from which many of the mitigation actions in Table 7-8 were sourced and revised.

Table 7-9: HMMWC Status of Previous Mitigation Actions
Mitigati
on No.

Hazard
Type
Status Year Primary
Agency
Title/Description Reason Cancelled/
Completed
ma-AHHMMWC112All Hazard Ongoing 2020 HMMWC Backup Power Expansion Revised ma-FLHMMWC118Flood Ongoing 2020 HMMWC Dam Failure Planning & Warning System Upgrades
Revised
ma-DRHMMWC114Drought Ongoing 2020 HMMWC Water Conservation Outreach & Education
Revised
ma-WFHMMWC115Wildfire Ongoing 2020 HMMWC Emergency Water & Supply Diversification
Revised
ma-EQHMMWC111Earthquake Ongoing 2020 HMMWC Seismic Retrofit of Critical Facilities & Infrastructure
Revised
ma-AHHMMWC116All Hazard Cancelled 2020 HMMWC Develop alternate access and evacuation routes to ensure
critical facilities are accessible
during emergencies.

Not within jurisdictional
authority
ma-AHHMMWC117All Hazard Cancelled 2020 HMMWC Water Quality may be affected by natural hazard events.

Cancelled to re-focus on
mitigating water quality
impacts via other actions
ma-CCHMMWC119Climate
Change
Cancelled 2020 HMMWC Severe weather may cause
increased flooding in the
District.

Cancelled to re-focus on dam
failure planning and warning
system upgrades
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Section 8. Napa County Flood Control and Water
Conservation District
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Napa County
2026 Multi-Jurisdictional Hazard Mitigation Plan Update Napa County Flood Control and Water Conservation District (NCFC) Special District Annex
Section 8. Napa County Flood Control & Water Conservation District..........................8-7

8.1 Scope & Purpose .....................................................................................................................................................................8-7

8.2 Jurisdictional Setting...........................................................................................................................................................8-7

8.2.1 Geography & Climate ..................................................................................................................................................8-8

8.2.2 Demographics & Vulnerable Populations..........................................................................................................8-11

8.2.3 Economy........................................................................................................................................................................8-19

8.2.4 Growth Trends & Future Development..............................................................................................................8-20

8.3 Planning Process ................................................................................................................................................................. 8-21

8.3.1 Public Input & Draft Review ...................................................................................................................................8-23

8.4 What’s New.............................................................................................................................................................................8-24

8.4.1 Mitigation Activities .................................................................................................................................................8-24

8.4.2 Mitigation Successes................................................................................................................................................8-26

8.5 Risk Assessment..................................................................................................................................................................8-30

8.5.1 Hazard Screening & Prioritization ......................................................................................................................8-30

8.5.2 Vulnerability to Specific Hazards........................................................................................................................8-34

8.5.3 Climate Change Impacts & Vulnerable Populations................................................................................... 8-44

8.5.4 Hazard Problem Statements..................................................................................................................................8-45

8.6 Mitigation Strategy ............................................................................................................................................................ 8-46

8.6.1 Capabilities & Opportunities..................................................................................................................................8-47

8.6.2 NCFCWCD Mitigation Action Plan......................................................................................................................8-58

8.6.3 Status of Previous Mitigation Actions...............................................................................................................8-62 CAL OES SUBMITTAL - JUNE 2026
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List of Figures
Figure 8-1: NCFCWCD Geographic Overview Map...............................................................................................................8-10 Figure 8-2: 2022 Napa River Dredging Project..................................................................................................................... 8-26 Figure 8-3: Napa River Flood Protection Project................................................................................................................. 8-28 Figure 8-4: Napa Creek.................................................................................................................................................................. 8-29 Figure 8-5: NCFCWCD Risk Assessment Matrix................................................................................................................. 8-32 Figure 8-6: NCFCWCD Flood Risk (FEMA and DWR Awareness Zones).................................................................... 8-37 Figure 8-7: Exposure Summary – NCFCWCD Sea Level Rise Risk.............................................................................. 8-43 Figure 8-8: Mitigation Action Number Key............................................................................................................................8-58 List of Tables
Table 8-1: Napa County Income and Poverty.........................................................................................................................8-12 Table 8-2: Napa County Renter- and Owner-Occupied Housing...................................................................................8-13 Table 8-3: Napa County Households with Seniors..............................................................................................................8-14 Table 8-4: Napa County Households with Children............................................................................................................8-15 Table 8-5: Napa County Population with Disabilities and Access to Transportation...........................................8-16 Table 8-6: Napa County Household Languages....................................................................................................................8-17 Table 8-7: NCFCWCD Planning Team and Steering Group Members......................................................................... 8-22 Table 8-8: NCFCWCD Planning Team Meetings ................................................................................................................. 8-23 Table 8-9: NCFCWCD Document Review of Potential Hazards......................................................................................8-31 Table 8-10: NCFCWCD Hazards Prioritization Summary..................................................................................................8-33 Table 8-11: NCFCWCD Hazard Problem Statements .......................................................................................................... 8-45 Table 8-12: NCFCWCD Capabilities and Opportunities Assessment............................................................................8-53 Table 8-13: NCFCWCD Mitigation Action Plan..................................................................................................................... 8-60 Table 8-14: NCFCWCD Status of Previous Mitigation Actions....................................................................................... 8-62 CAL OES SUBMITTAL - JUNE 2026
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Adoption Resolution
To comply with the Federal Disaster Mitigation Act of 2000 (DMA 2000), The Napa County Flood Control and Water Conservation District Board of Supervisors has officially adopted this 2026 Napa County MultiJurisdictional Hazard Mitigation Plan, including Volume 1 in its entirety as well as this Volume 2 municipal annex. The adoption of the MJHMP recognizes the district’s commitment to reducing the impacts of natural hazards within its jurisdiction and across Napa County.

A copy of the district’s adoption record is provided on the following pages. Adoption records for all jurisdictions are summarized in Volume 1, Table ES-1.

ADOPTION RECORD TO BE INSERTED UPON COMPLETION.

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Section 8. Napa County Flood Control & Water Conservation District

8.1 Scope & Purpose
This Jurisdictional Annex for the Napa County Flood Control and Water Conservation District (NCFCWCD) of the 2026 Napa County MultiJurisdictional Hazard Mitigation Plan (MJHMP) details the hazard mitigation planning elements specific to the district’s planning area. The annex is not intended to be a standalone document but appends to and supplements the information contained in the umbrella plan document (Volume 1). As such, all sections of the umbrella plan, including the planning process and other procedural requirements, apply to and were met by the district. This annex provides additional information specific to the district, with a focus on hazard identification and risk assessment, vulnerability assessment, problem statements, mitigation strategy, and capabilities assessment. Below are NCFCWCD’s Points of Contact:

Primary Point of Contact Alternate Point of Contact
Jeremy Sarrow, Watershed & Flood Control
Operations Manager
Napa County Flood Control and Water Conservation
District
804 First Street
Napa, CA 94559
Telephone: (707) 259-8600
email: [email protected]
Andrew Butler, District Engineer
Napa County Flood Control and Water Conservation
District
804 First Street
Napa, CA 94559
Telephone: (707) 259-8600
email: [email protected]

8.2 Jurisdictional Setting
NCFCWCD is a special district within the County of Napa, California, responsible for flood risk management, watershed stewardship, stormwater controls, and coordinated water planning across the entire county.

Established to serve both incorporated cities and unincorporated areas of Napa County, the District’s core mission is to protect lives and property by managing flood and storm waters in an environmentally sound manner and supporting sustainable water supply planning for the community. The district oversees a range of watershed and watershed‐related infrastructure programs and serves as the local sponsor for the Napa River Flood Management Plan, a comprehensive approach to long‐term flood protection and river corridor restoration along the Napa River and its tributaries.

NCFCWCD was created under the Napa County Flood Control and Water Conservation District Act of 1951, establishing it as an independent local public agency tasked with flood control, watershed management, and water supply planning for Napa County.

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Originally governed solely by the Napa County Board of Supervisors acting ex officio, the district’s governance structure was expanded in 1996 to include representatives from across the county. Governance of the NCFCWCD is vested in an 11‐member Board that incorporates both countywide and municipal representation, reflecting the regional scope of its responsibilities. The membership includes the five members of the Napa County Board of Supervisors, the mayors of Napa County’s five incorporated cities (Napa, St. Helena, American Canyon, Yountville, and Calistoga), and one additional member from the Napa City Council. This structure ensures that decisions regarding flood and watershed management reflect broad community interests and integrate policy priorities from both county and city levels. Meeting agendas, resolutions, and actions are published through County channels to provide transparency and public access to governance decisions.

The district’s functional responsibilities extend to the sponsorship and implementation of major flood protection projects, most notably the Napa River/Napa Creek Flood Protection Project, which is designed to reduce flood risk along the Napa River corridor through a combination of structural and non‐structural measures. In addition to flood risk reduction, NCFCWCD administers watershed management programs that are intended to protect surface water resources, reduce erosion and sedimentation, and promote healthy watershed processes countywide. The district’s involvement in stormwater management supports compliance with state and regional regulatory requirements and local stormwater quality objectives. It also serves as a coordinating entity in water supply planning and contract administration, working collaboratively with other agencies to support sustainable water resources for residents, agriculture, and industry.

The district’s jurisdictional coverage area spans all of Napa County, extending countywide and encompassing both incorporated cities and unincorporated areas. According to the Napa Local Agency Formation Commission (LAFCO), this service area covers approximately 506,517 acres, which is equivalent to roughly 792 square miles. The district routinely partners with federal entities, including the U.S. Army Corps of Engineers on authorized flood protection initiatives, and collaborates with the Napa County Flood Protection and Watershed Improvement Authority to facilitate funding and fiscal oversight of regional projects. Local municipalities also coordinate with the district on planning, operations, and emergency response to ensure that flood and stormwater issues are addressed consistently across jurisdictional lines.

NCFCWCD’s location within Napa County and the State of California are shown in Figure 8-1. ▪ Year of Incorporation: 1996
▪ 2023 Population Served: ~137,381 (CAS 5-Year, 2018-2023) ▪ Coverage Area: ~790 square miles

8.2.1 Geography & Climate
NCFCWCD is located within Napa County, California, a region characterized by diverse topography, water resources, and climatic influences. Napa County encompasses approximately 789 square miles, of which about 748 square miles is land and approximately 40 square miles (5.1%) is water, including rivers, lakes, and reservoirs that contribute to its watershed systems. Elevation varies widely across the county, from sea CAL OES SUBMITTAL - JUNE 2026
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level in the Napa Valley floor to Mount Saint Helena at around 4,344 feet and includes both the Mayacamas Mountains to the west and the Vaca Range to the east. (U.S. Census Bureau. “Napa County, 2025) The Napa Valley, which forms the central corridor of the county, is bounded by mountain ranges that influence both watershed dynamics and climate patterns. Elevations within the valley floor typically range from sea level to several hundred feet, with higher slopes and ridges rising into cooler, wetter conditions.

This varied topography contributes to a diversity of microclimates and seasonal weather variations, which are particularly important for local ecosystems, agriculture, and flood behavior.

The climate across Napa County is generally classified as Mediterranean, characterized by warm, dry summers and mild, wetter winters. Most annual precipitation occurs as rainfall primarily between late fall and early spring, with the rainy season typically extending from around November through April. Peak rainfall is usually observed in the winter months, while summer is marked by prolonged dry conditions with minimal precipitation. Napa’s Mediterranean climate also creates pronounced seasonal temperature changes; summer daytime temperatures often climb into the 70s and low 80s Fahrenheit, while winter lows average in the 30s to 40s Fahrenheit. Annual precipitation averages approximately 20 to 25 inches across the region, though totals vary with elevation and terrain.

The proximity of Napa County to the Pacific Ocean and the influence of San Pablo Bay help moderate temperature extremes and contribute to coastal fog penetration into the valley, especially in the summer months. These marine influences are more pronounced on the western side of the county near San Pablo Bay, while inland areas and higher elevations can experience greater diurnal temperature variation. The combined effects of terrain and coastal proximity foster a range of localized climate zones that affect everything from vegetation patterns to runoff processes and flood risk.

Together, the distinct geography and Mediterranean climate of Napa County shape the environmental conditions within the flood control district’s jurisdiction. These characteristics influence watershed hydrology, seasonal flood risk, water supply variability, and long-term climatic trends.

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Figure 8-1: NCFCWCD Geographic Overview Map
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8.2.2 Demographics & Vulnerable Populations
Napa County, which encompasses the full service area of the NCFCWCD, is home to a diverse and dynamic population. The county’s population includes a mix of age groups, family types, and economic profiles. While much of the county’s workforce and households enjoy relatively stable economic conditions, there remain portions of the population with characteristics that can increase vulnerability during natural hazards or disasters.

Among the characteristics relevant to hazard planning are the proportions of older adults and children, both of whom may require additional support during emergencies due to mobility, dependency, or caregiver needs. Older residents, in particular, may face challenges related to evacuation, medical needs, or extreme weather exposure. Similarly, households with young children often depend on stable care environments and services that can be disrupted during hazard events. While exact percentages vary with new census updates, these age groups represent significant segments of the community and are commonly recognized as populations with increased support needs in emergency planning.

Economic diversity within Napa County influences how different segments of the population experience disaster risk. Median household income in the county generally exceeds statewide averages, but it also masks variability among households. Some families and individuals contend with housing affordability challenges, limited financial reserves, or employment in sectors vulnerable to disruption during hazard events. Households with limited economic capacity may have fewer resources for preparedness measures, recovery costs, or access to private transportation, affecting their resilience in the face of floods, wildfires, or other hazards.

Language and cultural diversity also shape how information is accessed and acted upon during emergencies. A meaningful portion of Napa County residents speak languages other than English at home, and some residents are foreign-born, factors that can influence timely access to emergency alerts, preparedness resources, and community outreach efforts. Ensuring that communications are accessible and culturally appropriate is an important component of equitable hazard mitigation.

Other populations that may experience increased vulnerability include individuals with disabilities, households without reliable transportation, and residents living in rental or lower-income housing. While countywide data does not pinpoint specific counts for every subgroup, these broader demographic trends are consistent with social vulnerability frameworks used in emergency management planning and should be considered when identifying needs and prioritizing mitigation strategies.

Income & Housing
The economic and housing characteristics of Napa County play a critical role in shaping community vulnerability and resilience to natural hazards within the jurisdiction of the Napa County Flood Control and Water Conservation District. While Napa County overall demonstrates relatively strong economic indicators, variations in income levels, poverty rates, housing tenure, and rental occupancy patterns influence how different communities experience and recover from hazard events.

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Median household income levels, as shown in Table 8-1, vary considerably across Napa County jurisdictions.

Countywide, the median household income is approximately $105,809, with a poverty rate of 7.9 percent.

Among incorporated jurisdictions, income levels range from approximately $75,134 in the Town of Yountville to $135,781 in the City of St. Helena. Poverty rates also vary, with the Town of Yountville exhibiting the highest poverty rate at 10.6 percent, while the City of Calistoga reports a comparatively lower poverty rate of 5.4 percent. These differences are significant in hazard mitigation planning, as income levels influence household capacity to prepare for disasters, maintain insurance coverage, implement mitigation measures, and recover following hazard events. Households with limited economic resources are generally more vulnerable to displacement, property loss, and prolonged recovery periods following flooding, severe storms, wildfires, or other disasters.

Table 8-1: Napa County Income and Poverty
Area Median Income Poverty Rate
Napa County (Unincorporated) $105,809 7.9%
American Canyon $122,694 7.4%
Calistoga $96,667 5.4%
Napa (City) $100,273 8.1%
St. Helena $135,781 5.7%
Yountville $75,134 10.6%
Source: ACS 5-Year, 2017-2022
Housing tenure patterns shown in Table 8-2 further illustrate variations in community vulnerability. Across Napa County, approximately 49,738 housing units are occupied, of which 35.5 percent are renter-occupied and 64.5 percent are owner-occupied. Rental occupancy rates vary among jurisdictions, with renteroccupied housing comprising approximately 39.4 percent of units in the City of Napa, 40.3 percent in the City of Calistoga, and 44 percent in the City of St. Helena. By comparison, the City of American Canyon demonstrates a lower renter occupancy rate at 22.1 percent, indicating a higher proportion of owneroccupied housing.

These housing dynamics are relevant to hazard vulnerability because renters often face distinct challenges during disasters. Renter households typically have less control over structural mitigation measures, may lack adequate renter’s insurance, and are more susceptible to displacement following hazard-related damage. Communities with higher renter occupancy rates may therefore experience increased housing instability and longer recovery timelines following major hazard events. Conversely, higher owneroccupancy rates may correlate with greater long-term investment in property maintenance and mitigation, although lower-income homeowners may still face financial constraints.

In addition to tenure patterns, the distribution of income and poverty across jurisdictions influences the spatial distribution of vulnerability. Jurisdictions with lower median incomes or elevated poverty rates may CAL OES SUBMITTAL - JUNE 2026
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face greater constraints in implementing hazard mitigation measures, particularly those requiring private financial investment, such as structural retrofits, floodproofing, or defensible space improvements. These economic and housing factors intersect with hazard exposure, particularly in flood-prone or hazardsusceptible areas.

Table 8-2: Napa County Renter- and Owner-Occupied Housing Area Total Occupied Housing Units Renter Rent % Owner Own % Napa County (Unincorporated) 49,218 17,142 35% 32,076 65% American Canyon 5,725 1,205 21% 4,520 79%
Calistoga 2,116 776 37% 1,340 63%
Napa (City) 29,443 12,052 41% 17,391 59%
St. Helena 2,466 792 32% 1,674 68%
Yountville 1,516 514 34% 1,002 66%
Source: ACS 5-Year, 2017-2022
Dependent & Disabled Populations
Population characteristics associated with age, independence, and economic stability are important indicators of potential vulnerability within Napa County and the jurisdiction of the Napa County Flood Control and Water Conservation District. Older adults, particularly those living alone or experiencing poverty, may face elevated risk during hazard events due to mobility limitations, medical needs, social isolation, and reduced capacity to prepare for or recover from disasters.

Across Napa County, households with residents aged 65 years and older represent a substantial portion of the population. Countywide, approximately 33.8 percent of households include at least one resident aged 65 or older, reflecting the county’s relatively mature population profile, Table 8-3. Within incorporated jurisdictions, the proportion of households with older residents varies considerably. The Town of Yountville and the City of Calistoga exhibit particularly high concentrations of older adults, with approximately 47.9 percent and 43.0 percent of households, respectively, including residents aged 65 and older. The City of St.

Helena also demonstrates a comparatively elevated proportion at 38.9 percent.

Of particular relevance to hazard mitigation planning are households where older adults live alone, as these residents may face increased challenges during emergencies. Countywide, approximately 8.7 percent of households consist of individuals aged 65 or older living alone. This proportion is significantly higher in certain jurisdictions, including the Town of Yountville (19.2 percent) and the City of Calistoga (18.0 percent).

Older adults living alone may experience heightened vulnerability during hazard events due to reduced access to assistance, delayed evacuation, or difficulties receiving emergency communications.

Economic factors further influence vulnerability among older populations. Countywide, approximately 2.3 percent of households include residents aged 65 or older living below the poverty level. While this CAL OES SUBMITTAL - JUNE 2026
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percentage is relatively modest at the county level, higher concentrations are observed in specific jurisdictions, including the City of Calistoga (4.3 percent) and the Town of Yountville (4.2 percent). Older adults experiencing poverty may face compounded vulnerability due to limited financial resources, reduced housing stability, and constraints on preparedness or recovery expenditures.

Table 8-3: Napa County Households with Seniors
Households with 65+
Area Households 65+ %
65+
Alone %
65+
Poverty %
Napa County (Unincorporated) 55,588 18,777 33.8% 4,816 8.7% 1,271 2.3% American Canyon 5,924 1,772 29.9% 184 3.1% 111 1.9%
Calistoga 2,330 1,003 43.0% 419 18.0% 101 4.3%
Napa (City) 31,666 10,299 32.5% 2,674 8.4% 703 2.2%
St. Helena 2,963 1,153 38.9% 296 10.0% 42 1.4%
Yountville 1,824 873 47.9% 351 19.2% 77 4.2%
Source: ACS 5-Year, 2017-2022
Households with residents under the age of 18 represent a significant portion of Napa County’s population profile. Countywide, approximately 26.3 percent of households include individuals under 18 years of age, reflecting the presence of families with dependent children, Table 8-4. The proportion of households with children varies notably among jurisdictions. The City of American Canyon exhibits the highest concentration, where approximately 44.4 percent of households include residents under 18, indicating a community with a comparatively high number of families and dependent populations. The City of Napa also reflects a substantial share at 28.2 percent.

Particularly relevant for hazard planning are households headed by a single caregiver with children, as these households may face additional constraints during emergencies. Countywide, approximately 5.6 percent of households are classified as single-caregiver households with residents under 18. This proportion is elevated in certain jurisdictions, including the City of Napa (7.3 percent) and American Canyon (7.0 percent). Single-caregiver households may encounter greater challenges related to evacuation, childcare, employment disruption, and recovery capacity following hazard events.

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Table 8-4: Napa County Households with Children
Households with Children <18
Area Households <18 %
<18 Single
Caregiver %
Napa County (Unincorporated) 55,588 14,596 26.3% 3,109 5.6% American Canyon 5,924 2,633 44.4% 417 7.0%
Calistoga 2,330 471 20.2% 33 1.4%
Napa (City) 31,666 8,934 28.2% 2,315 7.3%
St. Helena 2,963 619 20.9% 168 5.7%
Yountville 1,824 160 8.8% 0 0.0%
Source: ACS 5-Year, 2017-2022
In addition to dependent children, Napa County includes a meaningful population of individuals with disabilities, shown in Table 8-5. Countywide, approximately 12.0 percent of residents report having a disability, with higher concentrations observed in certain jurisdictions. The Town of Yountville, for example, exhibits a notably elevated proportion at 20.1 percent, reflecting the community’s older demographic composition. Individuals with disabilities may experience increased vulnerability during hazard events due to mobility limitations, medical dependencies, communication barriers, and the need for accessible facilities or transportation.

Transportation access represents another important determinant of vulnerability. Countywide, approximately 4.4 percent of households do not have access to a vehicle, with higher proportions present in certain jurisdictions, including Yountville (11.5 percent) and St. Helena (7.4 percent). Households without vehicles may face increased evacuation challenges during rapidly developing hazard events such as flooding or wildfire. Similarly, a subset of residents are reliant on public transportation, which may be disrupted during emergencies. While the proportion of persons dependent on public transit is relatively small at the county level (0.6 percent), localized concentrations may influence evacuation logistics and emergency mobility planning.

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Table 8-5: Napa County Population with Disabilities and Access to Transportation Area Population
Persons w
Disability %
Persons
Reliant
on Public
Trans. % Households
HH w
No
Vehicle %
Napa County 137,384 16,544 12.0% 890 0.6% 55,588 2,421 4.4% American Canyon 21,669 2,201 10.2% 287 1.3% 5,924 138 2.3% Calistoga 5,191 573 11.0% 36 0.7% 2,330 83 3.6%
Napa (City) 79,233 9,837 12.4% 291 0.4% 31,666 1,554 4.9% St. Helena 5,426 683 12.6% 121 2.2% 2,963 219 7.4%
Yountville 3,397 683 20.1% 15 0.4% 1,824 210 11.5%
Source: ACS 5-Year, 2017-2022
These demographic and functional characteristics highlight important spatial variations in vulnerability across Napa County. Communities with higher concentrations of dependent children, single-caregiver households, individuals with disabilities, and households without vehicles may face elevated challenges during hazard events. These populations may require additional consideration in emergency preparedness, evacuation planning, sheltering strategies, and recovery assistance programs.

Race, Ethnicity & Language
NCFCWCD’s service area is characterized by substantial racial, ethnic, and cultural diversity. There are several areas in the county with higher concentrations of Hispanic or Latino residents, particularly in the central and southern Napa Valley, while other areas are characterized by predominance of White or Asian residents. Smaller but meaningful concentrations of additional racial and ethnic groups are distributed throughout the county. This diversity is especially pronounced in communities such as American Canyon, which is widely recognized as one of the most demographically diverse jurisdictions within Napa County.

Natural disasters compound racial disparities; non-white individuals and communities receive less recovery aid from FEMA than their white counterparts, even where the amount of damage is the same. (Howell, Junia; Elliott, James R., 2019) (National Advisory Council, 2020) These disparities are evidence of the complicated relationship between disaster recovery and overlapping social vulnerabilities including race, income, language, and health. Black and Latino residents are more likely to be low income and renters, conditions which create barriers to navigating FEMA’s Individual Assistance programs. Communities with more non-white residents may have lower tax revenue and property values, which means less investment in mitigation and rebuilding efforts before and after an emergency.

Demographic characteristics related to language proficiency and cultural diversity are important considerations in hazard mitigation planning, as they influence how residents receive, interpret, and respond to emergency information. Within Napa County and the jurisdiction of the Napa County Flood CAL OES SUBMITTAL - JUNE 2026
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Control and Water Conservation District, variations in language use and English proficiency may affect emergency communications, evacuation behavior, and access to disaster assistance.

Across Napa County, a substantial portion of households report speaking Spanish at home. Countywide, approximately 15.7 percent of households are Spanish speaking, reflecting the county’s significant Hispanic and Latino population. Spanish-speaking households are present throughout the county, with higher concentrations observed in several incorporated jurisdictions, shown in Table 8-6. The City of Napa and American Canyon each report Spanish-speaking households comprising approximately 18 to 20 percent of total households, while the City of Calistoga exhibits a slightly higher proportion at approximately 20.3 percent.

Language proficiency is particularly relevant when evaluating households with limited English proficiency (LEP). Countywide, approximately 3.9 percent of households are classified as limited English-speaking, indicating that one or more household members may experience difficulty communicating effectively in English. The City of Napa demonstrates a comparatively higher concentration of LEP households at approximately 5.2 percent, while other jurisdictions, including American Canyon, Calistoga, and St. Helena, report LEP rates closer to the countywide average.

Households with limited English proficiency may face increased vulnerability during hazard events due to potential barriers in accessing emergency alerts, preparedness information, evacuation instructions, and recovery resources. Timely comprehension of hazard warnings is critical during rapidly developing events such as flooding or wildfire, where delayed understanding can increase risk. Language barriers may also affect access to disaster assistance programs, insurance claims processes, and post-disaster recovery services.

While households speaking languages other than English or Spanish represent a comparatively small portion of the population, language diversity remains an important planning consideration. Even relatively small LEP populations may require targeted outreach strategies to ensure equitable access to emergency information and services.

Table 8-6: Napa County Household Languages
Area Households (HH) Spanish Speaking % Limited English % Napa County 55,588 8,738 15.7% 2,141 3.9%
American Canyon 5,924 1,069 18.0% 177 3.0%
Calistoga 2,330 474 20.3% 63 2.7%
Napa (City) 31,666 5,800 18.3% 1,653 5.2%
St. Helena 2,963 370 12.5% 88 3.0%
Yountville 1,824 49 2.7% 21 1.2%
Source: ACS 5-Year, 2017-2022
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Social Vulnerability Index (SVI)
The Centers for Disease Control and Prevention (CDC) Social Vulnerability Index (SVI) for Napa County reveals important spatial and demographic patterns that have direct implications for equitable hazard mitigation planning. As discussed in detail in Volume 1, Section 1.4.3.6, the SVI is a composite measure developed by the CDC to identify communities that are more likely to require support before, during, and after a disaster. It incorporates a range of factors across four key dimensions: socioeconomic status, household composition and disability, minority status and language, and housing type and transportation access. The resulting index score ranges from 0 (lowest vulnerability) to 1 (highest vulnerability).

The predominance of lower SVI values is consistent with other demographic indicators observed within the service area, including higher median household incomes, relatively low poverty rates, and high owneroccupancy levels. Lower social vulnerability scores often suggest increased household capacity to absorb certain economic shocks, access insurance mechanisms, and implement preparedness measures.

However, social vulnerability is multifaceted, and lower composite scores do not eliminate hazard exposure or risk. In geographically constrained mountain communities, physical isolation, terrain-driven infrastructure limitations, and hazard intensity may offset aspects of socioeconomic capacity.

Within Napa County, demographic patterns indicate variability in several indicators that contribute to social vulnerability. A meaningful portion of the population includes older adults, dependent children, and individuals with disabilities, groups that the SVI identifies as at potentially increased risk during hazard events due to functional, health, or mobility needs. Additionally, households with limited English proficiency, those without a vehicle, and households with a single caregiver represent social conditions that correlate with higher SVI rankings. These characteristics are important for the district to consider in flood risk communication, evacuation planning, sheltering support, and recovery assistance.

From an economic perspective, disparities in median household income and poverty rates across jurisdictions within Napa County also align with SVI themes. Jurisdictions with lower income levels and higher poverty rates may have reduced capacity for hazard preparedness investments, insurance coverage, or post-disaster recovery expenditures, further emphasizing social vulnerability considerations in mitigation planning.

Housing type and transportation, another SVI theme, are also relevant to the district’s planning area. Higher proportions of renter-occupied housing and households without personal vehicles may present challenges during rapid evacuation or sheltering in place during flood events. Renters, in particular, may have less control over structural mitigation measures and reduced capacity to invest in pre-event floodproofing improvements.

While the SVI offers a standardized way to gauge social vulnerability, it is most informative when paired with local demographic data such as that presented in this plan (e.g., household age, disability status, language proficiency, vehicle access, income, and housing tenure). Collectively, these indicators provide a nuanced understanding of areas and population segments within Napa County that may be at comparatively greater social vulnerability during flood events or other hazards.

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8.2.3 Economy
NCFCWCD operates within Napa County, a regional economy shaped by a combination of agriculture, tourism, government services, healthcare, and commercial activity. The county’s economic profile is strongly influenced by its nationally recognized wine industry, which plays a central role in employment, land use, infrastructure demand, and hazard exposure.

Agriculture represents a foundational component of the county’s economy, with viticulture serving as the dominant agricultural sector. Vineyards and wineries contribute significantly to local employment, revenue generation, and tourism activity. The agricultural economy is closely tied to environmental conditions, including precipitation patterns, water availability, temperature variability, and hazard events such as flooding, drought, and wildfire. Disruptions to agricultural production caused by natural hazards can produce cascading economic effects, including revenue loss, workforce impacts, and infrastructure strain.

Tourism and hospitality form another critical pillar of Napa County’s economy. The region attracts substantial visitor activity associated with wineries, culinary destinations, lodging, and recreational amenities. This visitor-serving economy supports a wide range of businesses, including hotels, restaurants, retail establishments, and transportation services. Hazard events, particularly floods, wildfires, severe storms, and extreme heat, can significantly affect tourism by disrupting transportation networks, damaging facilities, and reducing visitor confidence. Because tourism activity is geographically concentrated in valley corridors and urban centers, hazard impacts may create localized but economically significant consequences.

Government, public administration, and institutional services also represent a stable component of the county’s economic structure. Public agencies, educational institutions, and local government operations provide employment and essential services throughout the county. NCFCWCD itself contributes to economic stability by supporting flood protection, watershed management, and infrastructure resilience, which help reduce economic losses associated with hazard events.

Healthcare and social assistance sectors are increasingly important contributors to employment within Napa County. These services support both resident populations and visitor activity, while also playing a vital role during emergencies and disaster recovery. Hazard events may increase demand for healthcare services, particularly among vulnerable populations, while also posing risks to facility operations and accessibility.

While Napa County generally demonstrates strong economic indicators relative to broader regional averages, income variability, housing costs, and employment distribution patterns influence economic resilience across communities. Certain sectors, including agriculture, hospitality, and small businesses, may be particularly sensitive to hazard disruptions. Economic losses from hazard events may include direct damages to property and infrastructure, business interruption costs, workforce displacement, and reduced revenue generation.

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From a hazard mitigation perspective, the county’s economic structure presents both strengths and vulnerabilities. Economic diversity provides some resilience, while sector-specific dependencies and geographic concentrations of activity may amplify hazard impacts. Flooding, in particular, represents a key economic risk given its potential to affect transportation corridors, commercial districts, agricultural lands, and visitor-serving areas.

8.2.4 Growth Trends & Future Development
NCFCWCD encompasses all of Napa County, a region that has experienced modest but steady population and development growth over recent decades. Growth patterns in the county are shaped by a mix of agricultural preservation policies, land use designations that protect open space and viticultural lands, and localized intensification within incorporated cities and urbanized corridors. This combination has resulted in relatively moderate population increases compared with rapidly growing regions in the state, while also concentrating residential and commercial development in established communities.

Population growth in Napa County has generally occurred at a gradual pace, with demographic trends pointing toward continued increases in the number of county residents, albeit at a slower rate than many areas in the San Francisco Bay Area corridor. New housing construction, infill development, and redevelopment within urban and suburban areas of cities such as Napa, American Canyon, and St. Helena contribute to this trend. Growth has often been supported by economic activity tied to tourism, wine production, and service sectors, which sustain demand for housing and related services. As noted earlier, median household incomes and housing costs in many parts of the county are above regional averages, and this economic context can influence the pace and pattern of development.

Local land use policies and planning frameworks play a central role in shaping future development. The Napa County General Plan and individual city general plans emphasize agricultural land protection, open space conservation, and managed growth within designated urban limits. These policies limit extensive outward expansion by prioritizing the preservation of productive agricultural lands and environmentally sensitive areas. Growth is typically directed toward established urban boundaries, where infrastructure capacity, including water, sewer, transportation, and flood control systems, can be supported more effectively. However, even relatively contained growth can increase exposure to natural hazards if new development occurs in areas with defined flood risk, steep slopes, or near critical infrastructure.

Future projections for housing and commercial development anticipate continued demand for residential units, particularly rental housing and housing affordable to key workforce segments. This demand is reflected in ongoing planning efforts to increase housing supply within cities like Napa and American Canyon. As housing stock increases, attention to hazard risk during the planning and permitting process becomes increasingly important. Ensuring that new development incorporates appropriate mitigation measures, including flood risk reduction, stormwater management, and resilient infrastructure design, supports long-term community safety and reduces potential future losses.

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Infrastructure investment also reflects growth trends. Upgrades to transportation corridors, storm drains, and flood control facilities are ongoing priorities to accommodate existing needs and anticipate future demands. The Napa County Stormwater Management Program and initiatives aligned with the Napa River Flood Protection Project exemplify multi-jurisdictional efforts to integrate hazard mitigation into infrastructure planning, particularly as urbanized areas continue to evolve.

Climate change considerations further influence growth and development planning. Anticipated increases in extreme precipitation events, rising temperatures, and wildfire risk have prompted planners to reassess traditional development practices and incorporate resilience principles into comprehensive planning frameworks. Projects that enhance natural systems’ ability to absorb runoff, protect steep slopes, and maintain watershed function are increasingly prioritized in policy discussions.

8.3 Planning Process
NCFCWCD followed the planning process detailed in Volume 1, Section 2, including participating in the county-wide Hazard Mitigation Planning Team (HMPT) and formulating their own internal planning team to support the broader planning process.

The district’s representatives in the Steering Group led stakeholder and public engagement efforts alongside the Consultant Team, with assistance from the county-wide HMPT and their internal planning team. This engagement process is described in Volume 1. Specifically, for the district, this included postings to the district website and social media, and outreach events, as documented in Appendix B. Examples of Key Stakeholders engaged by Napa County on behalf of the district with relevance to the development of NCFCWCD’s mitigation strategy include the USDA and other federal agencies; CAL FIRE and other state agencies; other jurisdictions; community-based organizations such as local Chamber of Commerce chapters; utility providers like PG&E; UC Davis and other academia; and local businesses.

All Key Stakeholders that were invited to participate in the planning process are listed in Volume 1, Section 2, and the input received from stakeholders was integrated into the district’s annex, as described in Volume 1 Table 2-9. The district’s internal planning team participants, their positions, and how they participated in the planning process are shown in Table 8-7.

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Table 8-7: NCFCWCD Planning Team and Steering Group Members Team Members Title Description of Involvement
Jeremy Sarrow
Watershed & Flood Control
Operations Manager
Lead Point-of-Contact, Kickoff Meeting, HMPT #1, #2, BO #1 and #2
Andrew Butler District Engineer Alternate Point-of-Contact, HMPT #2, #3, BO #1 and #2 Leif Bryant Logistics Chief Alternate Point-of-Contact, Kickoff Meeting, HMPT, #2 Ross Murphy Alternate Point-of-Contact, HMPT #1, #3, BO #1 and #2 Richard Thomasser Deputy Director of Public
Works / District Manager Alternate Point-of-Contact, BO #1 NCFCWCD staff participated in a comprehensive hazard mitigation planning process as part of the 2026 Napa County MJHMP update. This included a series of breakout meetings, listed in Table 8-8 that engaged the district’s planning team, which included key district personnel and stakeholders in evaluating hazards, identifying local vulnerabilities, and prioritizing mitigation strategies The process began with a County-Wide Steering Group Kickoff Meeting on February 28, 2024. This initial meeting focused on welcoming participants, establishing a shared understanding of the project scope and schedule, clarifying roles and responsibilities of the Steering Group, the county-wide Hazard Mitigation Planning Team (HMPT), and individual jurisdictional planning teams, and included a review of key changes since the 2020 Local Hazard Mitigation Plan The meeting set the foundation for coordinated participation throughout the planning effort.

On December 10, 2025, participants engaged in a hexagon mapping activity designed to visually identify mitigation actions that could benefit from or require inter-jurisdictional coordination. These collaborative efforts helped shape a refined set of mitigation alternatives, establish shared planning goals, and align local strategies with FEMA’s Hazard Mitigation Assistance (HMA) funding framework.

Throughout the series of breakout meetings, the district engaged in a structured and collaborative planning process focused on assessing hazard risks, identifying vulnerabilities, and developing targeted mitigation strategies. The meetings began with recaps of the county-wide HMPT meetings to ensure alignment of goals and progress.

During the October 23, 2024 breakout out meeting, discussions concentrated on community engagement outcomes, initial risk assessments, and the integration of demographic data to better understand vulnerable populations. Jurisdictional teams reviewed their specific hazard exposures using the Risk Assessment Mapping Platform (RAMP) and participated in prioritization exercises to identify their top hazards.

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The November 4, 2025, breakout meeting shifted toward reviewing local capabilities and defining specific areas of concern, which informed the drafting of problem statements. Teams worked collaboratively to refine mitigation alternatives, align actions with FEMA guidelines, and develop a shortlist of priority mitigation actions and inter-jurisdictional collaboration opportunities.

The meetings also included consensus-building activities around hazard rankings, capabilities, and planned actions, while providing regular updates on the overall project schedule.

Table 8-8: NCFCWCD Planning Team Meetings
Meeting & Date Agenda / Topics Goals / Key Inputs
County-Wide Steering Group and HMPT Kick-off and Meetings #1 & #2 February 28, 2024– July 18, 2024
NCFCWCD Planning
Team
Breakout Meeting #1
October 23, 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 25, 2025
NCFCWCD Planning
Team
Breakout Meeting #2
November 4, 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 10, 2025

8.3.1 Public Input & Draft Review
As detailed in Volume 1, Section 2, the draft plan was available for public review and comment from May 15 to June 2, 2026. Public comments received during that time were similar to those gathered throughout the public engagement process, including the need for more equity in the distribution of mitigation activities and funding and the need for enhanced cooperation among jurisdictions, utility providers, and state CAL OES SUBMITTAL - JUNE 2026
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agencies. These comments were incorporated into the city’s mitigation strategy, as appropriate; although, most were already addressed by the Mitigation Action Plan which was based on previous public input.

Public and stakeholder input was gathered and incorporated throughout the plan development process, before the public review period, such as from the online public survey (see Volume 1, Section 2.1.2 and Appendix B, for details). During the review period, jurisdictional staff and stakeholders that participated in the plan development also reviewed the public draft and provided comments on minor corrections and revisions, which were addressed in the final plan.

8.4 What’s New
This section provides an overview of hazard mitigation planning efforts for the planning area and highlights the updates made in the 2026 MJHMP. NCFCWCD previously participated in and maintained a Hazard Mitigation Plan, which guided resilience planning and hazard mitigation actions at the district level.

NCFCWCD is updating their current plan on a county wide level. This integration reflects the district’s ongoing commitment to regional resilience and acknowledges that many hazards such as coastal flooding, severe storms, and earthquakes cross jurisdictional boundaries.

Through participation in the MJHMP, NCFCWCD has identified its highest priority hazards, developed hazard specific problem statements, and proposed actionable strategies to reduce risks. By aligning with countywide partners and leveraging regional resources, NCFCWCD has strengthened its capacity to prepare for, withstand, and recover from disasters while continuing to protect its unique coastal community character.

8.4.1 Mitigation Activities
NCFCWCD administers and supports a range of programs and activities that contribute to hazard risk reduction, watershed stability, and long-term community resilience throughout Napa County. The district’s mitigation efforts primarily emphasize flood risk management, watershed stewardship, and stormwater coordination, reflecting its statutory responsibilities and operational functions.

A core function of the district involves Watershed Management and Stream Maintenance, which includes the routine inspection, maintenance, and management of the Napa River and its tributaries. These activities are intended to preserve channel conveyance capacity, manage sedimentation, reduce erosion, stabilize streambanks, and minimize localized flooding risks. Stream maintenance operations serve as an important non-structural mitigation measure by addressing conditions that can exacerbate flood hazards, including debris accumulation, vegetation encroachment, and channel instability. These programs are supported through a combination of local assessments, State funding, and federal grant resources, enabling the district to maintain watershed infrastructure and functions on a countywide basis.

To guide these efforts, the district has updated its Stream Maintenance Program (SMP) Manual, which establishes the organizational and operational framework governing routine stream maintenance activities. The SMP provides standardized procedures, environmental protection measures, and regulatory CAL OES SUBMITTAL - JUNE 2026
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compliance mechanisms designed to balance hazard mitigation objectives with environmental stewardship. As part of this update, the district conducted environmental review consistent with the California Environmental Quality Act (CEQA). The district determined that implementation of the updated program could result in potentially significant but mitigable environmental effects and subsequently adopted a Mitigated Negative Declaration.

Stormwater management represents another important mitigation-related function within the district’s jurisdiction. Napa County and its incorporated cities, including American Canyon, Napa, St. Helena, Calistoga, and the Town of Yountville, collectively administer the Napa County Stormwater Pollution Prevention Program. This regional program supports water quality protection, runoff management, and compliance with State and federal stormwater regulations. Effective stormwater controls contribute to hazard mitigation by reducing localized flooding, managing peak runoff, and preserving watershed stability.

Coordination among jurisdictions supports consistent regulatory implementation and promotes integrated watershed management strategies.

The district also contributes to broader Water Resources planning and management efforts throughout Napa County. These activities support long-term water supply reliability, watershed function, and infrastructure resilience. Integrated water resources planning provides an important mitigation benefit by addressing hydrologic variability, drought conditions, and changing climate patterns that influence flood behavior, runoff dynamics, and system performance.

Groundwater resources and sustainability initiatives within Napa County are administered through the Planning, Building, and Environmental Services Department, reflecting a coordinated, multi-agency approach to water management. Although groundwater management is not a direct District function, groundwater sustainability efforts intersect with hazard mitigation objectives, particularly in relation to drought resilience, watershed stability, and the long-term protection of water resources.

Adjustments to Previous Mitigation Actions
Some of NCFCWCD's mitigation efforts remain ongoing or in the pipeline. These actions, ranging from infrastructure upgrades to restoration initiatives, represent the district’s proactive approach to addressing hazards as resources become available.

Recognizing constraints such as limited funding, staffing, and shifting priorities, the district has reevaluated certain initiatives, leading to their reprioritization or canceling of mitigation actions. Factors such as feasibility, cost-effectiveness, and emerging risks informed these decisions, ensuring alignment with the city’s updated hazard mitigation goals. Adjustments to previous mitigation actions are documented as part of the NCFCWCD’s Mitigation Action Plan (Table 8-13), and more specific status updates are provided in Table 8-14.

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8.4.2 Mitigation Successes
Since the adoption of the 2021 Hazard Mitigation Plan, NCFCWCD has made measurable progress in implementing mitigation actions that reduce risk and enhance community resilience. These successes reflect the district’s continued commitment to integrating hazard mitigation into local planning, capital improvement projects, and community programs.

The following success stories highlight completed and ongoing efforts that address key hazards such as wildfire, flooding, and infrastructure vulnerability. Collectively, these initiatives demonstrate the city’s ability to move from planning to implementation by leveraging partnerships, securing funding, and advancing projects that provide long-term risk reduction benefits to the community.

Napa Dredging Project
The 2022 Napa River Operations and Maintenance (O&M) Dredging Project was conducted through a partnership between the U.S. Army Corps of Engineers (USACE) San Francisco District and the NCFCWCD.

The project was part of the Corps’ Navigation Program, which focuses on maintaining safe and reliable waterways that support commerce, recreation, and public safety.

The project involved dredging portions of the Napa River navigation channel in Napa, California to restore channel depth and maintain navigability. Approximately 75,000 cubic yards of sediment were planned to Figure 8-2: 2022 Napa River Dredging Project
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be removed from the river. The dredging targeted two main channel depths: approximately 10 feet in the upper reach and 15 feet in the lower reach, measured relative to mean lower low water.

Dredging operations used a clamshell dredge, which was selected because the river contains coarse sediment and debris that are not well suited to hydraulic pipeline dredging methods. Material removed from the channel was loaded onto scows (barges) and transported to an offloading site at Coombs, where the sediment was transferred and hauled by truck to the South Jefferson placement site. Approximately 52,000 cubic yards of dredged material were expected to be placed at the disposal site.

Work was scheduled within an environmental operating window between August 1 and November 30, with active dredging anticipated to occur between mid-August and early November, lasting roughly six to nine weeks. Working hours varied depending on the location along the river corridor. In the downtown business district near 3rd Street, dredging was limited to weekday daytime hours, while residential areas allowed slightly longer daily operations and non-residential sections permitted extended or continuous work schedules.

Pre-construction activities included environmental approvals, contractor solicitation, and contract award prior to the start of dredging operations. The project also included defined dredging reaches along the upper portion of the Napa River, identified through hydrographic surveys conducted in February 2022 that documented sediment accumulation within the navigation channel.

Napa River & Creek Flood Protection Project
One of the District’s most significant mitigation initiatives is the Napa River and Creek Flood Protection Project, a comprehensive, multi-benefit flood management program. This project is designed to provide protection from 100-year flood events while integrating ecosystem restoration objectives. The project includes the restoration of more than 900 acres of high-value tidal wetlands within the San Francisco Bay Estuary, reflecting a balanced approach that combines flood risk reduction with environmental enhancement. In addition to ecological benefits, the project is designed to protect approximately 2,700 homes, 350 businesses, and more than 50 public properties from major flood events. The economic benefits associated with reduced flood damages are substantial, with estimated avoided losses of approximately $26 million annually in flood damage costs. This project represents a cornerstone mitigation investment that directly supports life safety, property protection, infrastructure resilience, and environmental sustainability.

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Watershed Management & Stream Maintenance
The NCFCWCD manages a comprehensive watershed management program designed to reduce flood risk, protect water resources, and maintain the ecological health of local waterways. Key activities include maintaining approximately 13 miles of district-owned channels, addressing problem areas along the Napa River and its tributaries, dredging sections of the river to maintain conveyance capacity, and repairing and stabilizing streambanks. The district also operates a countywide flood early warning system, supports installation and replacement of major storm drain trunk lines, and participates in federal and state flood protection grant programs to implement mitigation projects and watershed improvements.

In addition to infrastructure maintenance, the district conducts groundwater monitoring, oversees adjudicated watersheds, and prepares technical studies related to flood protection and watershed management. The district also works collaboratively with local agencies and communities to implement Figure 8-3: Napa River Flood Protection Project
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floodplain management regulations and comply with National Pollutant Discharge Elimination System (NPDES) stormwater requirements. Through its Stream and Watershed Maintenance Program, the District uses an adaptive management approach that balances flood protection with habitat preservation and riparian ecosystem health.

The program emphasizes stewardship of Napa County’s streams and rivers through coordinated maintenance, habitat restoration, and invasive plant management. To guide these activities, the District developed the Napa County Stream Maintenance Manual, which establishes consistent standards and best practices for maintaining channels while protecting sensitive environmental resources. Overall, the watershed management program integrates flood risk reduction, environmental stewardship, and interagency collaboration to protect life, property, and natural resources throughout Napa County.

Figure 8-4: Napa Creek
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8.5 Risk Assessment
This section focuses on profiling hazards specific to NCFCWCD and assessing their vulnerability independent of the broader county-wide planning area, which has been evaluated in Section 3 of Volume 1.

The hazard profiles in Volume 1 discuss overall impacts to the planning area and describe relevant plans, policies, and regulations; past events; location; frequency and probability of future occurrences; severity and extent; warning time; secondary hazards; and climate change impacts. For more information on risk assessment methodologies, see Volume 1, Appendix A.

This section includes a tailored vulnerability assessment, analyzing assets at risk such as population, property, and critical facilities and infrastructure unique to the district, and information on district-specific differences in hazard vulnerability across the planning area. It also identifies total district assets at risk, including people, property, and critical facilities and infrastructure within the district. In addition, this section presents growth and development trends for the community, offering insights into vulnerabilities and risks that represent the broader context of assets at risk.

8.5.1 Hazard Screening & Prioritization
Members of the Planning Team from each participating jurisdiction came together to collaboratively decide which county-wide hazards would be included in the MJHMP, and which would be excluded. Hazard screening and prioritization took place early in the process and integrated historic data, local knowledge, and consensus opinions to create a risk assessment matrix for the county as well as for each participating jurisdiction. These matrices indicate the priority of hazards prior to further refinement. Details about this process, the results of the discussion, and in-depth profiles for county-wide hazards can be found in Volume 1, Sections 2 and 3.

NCFCWCD’s internal planning group used the same hazard identification and prioritization process as the county-wide Planning Team. They reviewed previously prepared hazard mitigation plans and other relevant documents to determine the realm of natural hazards that have the potential to affect the district. Table 8-9 provides a crosswalk of hazards identified in select planning documents, including the 2020 Napa County MJHMP, 2022 Groundwater Sustainability Plan, Climate Adaptation and Interconnected Surface Water and Groundwater Stewardship, and the 2023 State of California HMP. The crosswalk was used to develop a preliminary hazards list, providing a framework for the group to evaluate which hazards were truly relevant to NCFCWCD and which ones were not.

The internal planning group then ranked hazards based on their probability of affecting NCFCWCD and potential impacts on the community. Figure 8-5 displays the results of the hazard risk ranking exercise that was performed before further refinement. All hazards have been profiled in Volume 1 of this document. The purpose of this annex is to specifically address the district’s vulnerability to specifically identified hazards.

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Table 8-9: NCFCWCD Document Review of Potential Hazards Hazard 2020 Napa County
MJHMP 2020 GSP 2023 CaliforniaSHMP
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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Figure 8-5: NCFCWCD Risk Assessment Matrix
Note: Hazard naming in the Risk Assessment Matrix may not match the final naming used. Refer to hazards prioritization summary table.

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Priority Hazards
The results of the initial risk ranking exercise completed by the district’s Planning Team, before further refinement, are identified in the county’s completed matrix in Figure 8-5. Table 8-10 provides the final list of priority hazards and subhazards with additional details about why certain hazards were chosen and why others 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.

Table 8-10: NCFCWCD Hazards Prioritization Summary
Hazard Priority Explanation
Earthquake / Liquefaction -
Profiled in Volume 1, Section 3.3.4; not a priority due to being outside jurisdictional mission and authority
Wildfire -
Profiled in Volume 1, Section 3.3.1; not a priority due to low probability and impact potential
Flood High Profiled in Volume 1, Section 3.3.2, and Section 8.5.2.1 in this annex Levee Failure -
Profiled in Volume 1, Section 3.3.2; not a priority due to low probability and impact potential
Extreme Weather / Storms Medium
Profiled in Volume 1, Section 3.3.5, and Section 8.5.2.2 in this annex as Severe Weather, including High Wind and Heavy Rain (Winter Weather not a priority due to low probability and impact potential) Drought -
Profiled in Volume 1, Section 3.3.6; not a priority due to being outside jurisdictional mission and authority
Geologic / Mass Movement -
Profiled in Volume 1, Section 3.3.5; not a priority due to low probability and impact potential
Extreme Heat -
Profiled in Volume 1, Section 3.3.8; not a priority due to being outside jurisdictional mission and authority
Agricultural Pests -
Profiled in Volume 1, Section 3.3.9; not a priority due to being outside jurisdictional mission and authority
Sea Level Rise High Profiled in Volume 1, Section 3.3.9, and Section 8.5.2.3 under Climate Change
Climate Change High
Profiled in Volume 1, Section 3.3.9, and Section 8.5.2.3 in this annex, including Sea Level Rise and discussed as a compounding hazard in relevant profiles
Dam Failure -
Profiled in Volume 1, Section 3.3.3; not a priority due to being outside jurisdictional mission and authority
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8.5.2 Vulnerability to Specific Hazards
Assessing vulnerabilities exposes the unique characteristics of individual hazards and begins the process of narrowing down which areas within the district are vulnerable to specific hazard events. The vulnerability assessment considered unique local knowledge of hazards and impacts and a GIS overlaying method for examining such vulnerabilities in more depth. Using these methods, the district’s planning group estimated vulnerable populations, properties, and assets, and potential losses. In addition, the exposure of district assets to drought, earthquake, wildfire, flood, and climate change hazards were also considered.

Many of the hazard profiles include a snapshot map and damage estimation tables that illustrate the district’s vulnerabilities to those specific hazards. These maps assisted the planning group in understanding the hazard exposure of populations, parcels, and critical facilities and infrastructure. Each snapshot map contains an exposure summary that displays the percentage of the population, the improvement and content value of parcels, and the amount of critical infrastructure that is exposed. For hazards without geospatial extents, such as drought and severe weather, narratives are provided instead of exposure maps and tables.

Based on the hazard prioritization exercise, this vulnerability assessment focuses on three hazards for NCFCWCD, some of which encompass sub hazards such as sea level rise and heavy rain.

Flood
SECTION 8.5.2.1
Severe Weather
SECTION 8.5.2.2
Climate Change
SECTION 8.5.2.3
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Flood Hazard
Flood hazards within the NCFCWCD occur primarily along the Napa River and its tributaries, which drain the Napa Valley watershed before discharging into San Pablo Bay. The Napa River watershed covers approximately 426 square miles, extending from the Mayacamas Mountains on the west and the Vaca Range on the east through the valley floor where the majority of development occurs. Flood hazards are most pronounced along the lower gradient portions of the watershed where river channels widen and flow velocities decrease. Areas particularly susceptible to flooding include the Napa River corridor, tributary streams, low-lying urban areas within the City of Napa, and agricultural lands throughout the valley floor.

Flooding within the watershed is typically riverine in nature, occurring when prolonged or intense rainfall causes the Napa River or its tributaries to exceed channel capacity. In downstream portions of the watershed, particularly near the southern end of the county, tidal influences from San Pablo Bay can exacerbate flooding by slowing drainage from the river system. Localized flooding can also occur within developed areas where stormwater drainage systems become overwhelmed during heavy rainfall events.

Flood severity in Napa County can range from nuisance flooding in localized drainage areas to large-scale riverine flooding that impacts homes, businesses, agricultural lands, and critical infrastructure.

Napa County has experienced numerous flood events throughout its history due to winter storms and atmospheric river events that produce large volumes of rainfall over short periods. Significant flood events have occurred in 1986, 1995, 1997, and 2005, each of which caused substantial property damage and disruption within the Napa Valley. The 1986 flood is widely considered one of the most severe events in the county’s history, resulting in widespread inundation throughout the City of Napa and surrounding communities. Subsequent floods in the 1990s and early 2000s again demonstrated the vulnerability of developed areas located along the Napa River floodplain.

Flood events have historically affected residential neighborhoods, commercial districts, agricultural operations, and transportation infrastructure throughout the watershed. These repeated events prompted the development of major flood management initiatives and ongoing watershed management activities by the Napa County Flood Control and Water Conservation District to reduce flood risk and improve system resilience.

Flooding in Napa County is considered a high probability hazard due to the region’s climate, watershed characteristics, and history of recurring flood events. The county experiences the majority of its annual precipitation during the winter storm season between November and April, when atmospheric river systems can deliver prolonged periods of heavy rainfall. These storms can rapidly increase river flows and produce flooding along the Napa River and its tributaries.

Future flood events are expected to occur periodically, particularly during extreme storm events or when saturated watershed conditions result in high runoff volumes. Given the region’s long history of flooding and the continued presence of development within flood-prone areas, flooding remains one of the most likely hazards affecting communities within the District.

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Climate change is expected to influence future flood risk in Napa County through changes in precipitation patterns and hydrologic conditions. Climate projections for California indicate an increased likelihood of more intense storm events and atmospheric rivers, which could produce higher peak runoff and increased flood potential. Warmer temperatures may also alter watershed processes, including soil moisture conditions and the timing of precipitation.

In addition, sea level rise may affect downstream portions of the Napa River system by increasing tidal influence and reducing the river’s ability to drain stormwater during high tide conditions. These factors may increase flood depths and the frequency of flooding in low-lying areas near the southern end of the watershed. As a result, long-term flood management planning must account for potential climate-driven changes in flood behavior.

Flood hazards within NCFCWCD have the potential to impact residential neighborhoods, commercial areas, agricultural lands, and critical infrastructure located along the Napa River and its tributaries. The City of Napa and surrounding developed areas within the valley floor represent the most concentrated exposure due to its proximity to the river and historic floodplain areas as shown in Figure 8-6.

In addition to structural damage, flood events can disrupt transportation routes, utilities, and public services, affecting emergency response and recovery operations. Agricultural lands throughout the Napa Valley are also vulnerable to flood impacts that may damage crops, disrupt irrigation infrastructure, and affect local economic activity. Vulnerable populations, including elderly residents and lower-income households located in flood-prone areas, may face additional challenges during flood events due to limited resources for evacuation or recovery.

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Figure 8-6: NCFCWCD Flood Risk (FEMA and DWR Awareness Zones) CAL OES SUBMITTAL - JUNE 2026
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Severe Weather Hazard
Severe weather in Napa County includes a range of meteorological conditions that can cause damage to infrastructure, disrupt services, and exacerbate other natural hazards. The most common severe weather hazards affecting the NCFCWCD include heavy rainfall and high wind events, but winter storms, thunderstorms, and hail also occur occasionally. These events typically occur during the winter months but can also occur during transitional seasons when strong atmospheric systems move through Northern California.

Heavy precipitation events are the most consequential severe weather hazard for the district because they directly influence watershed runoff and river levels within the Napa River watershed. Atmospheric river storms can deliver large volumes of rainfall over short periods, which may overwhelm stormwater systems, increase streamflow, and contribute to riverine flooding. Severe weather events can also generate strong winds capable of damaging trees, power lines, and infrastructure, which can create additional hazards such as power outages or debris accumulation in waterways and drainage systems.

Severe weather can affect the entire service area of NCFCWCD, which encompasses all of Napa County.

However, impacts can vary depending on local topography and land use patterns. Mountainous areas along the Mayacamas Mountains and Vaca Range often experience higher wind speeds and heavier rainfall due to orographic effects, while the Napa Valley floor may experience localized flooding or stormwater drainage issues during intense precipitation events.

Urbanized areas, particularly within the City of Napa, may be vulnerable to stormwater-related impacts such as street flooding, drainage system overload, and debris accumulation in storm drains. Agricultural lands throughout the valley may also be affected by severe weather events through crop damage, soil erosion, or flooding of low-lying fields.

Severe weather events occur regularly in Napa County, particularly during the winter months when Pacific storm systems move through Northern California. Atmospheric river storms have historically produced periods of intense rainfall, strong winds, and localized flooding throughout the region. Severe storms in the past have caused power outages, roadway flooding, fallen trees, and debris blockages in waterways and storm drainage systems.

Although severe weather events alone may not always cause widespread damage, they frequently contribute to or intensify other hazards, particularly flooding and slope instability. For example, heavy rainfall associated with winter storms has historically preceded major flood events within the Napa River watershed.

The probability of severe weather occurring in Napa County is high, as storm events occur annually during the winter wet season. Multiple storm systems typically affect the region each year, with occasional larger events producing higher wind speeds and more intense rainfall. While many storms result in limited impacts, stronger atmospheric river events can significantly increase hazard potential by producing prolonged rainfall and elevated runoff within the watershed.

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Climate projections for California suggest that storm intensity may increase in the future, even as the total number of storm events remains similar. Research indicates that atmospheric river storms may become more intense, producing heavier rainfall over shorter durations. These conditions could increase the likelihood of flooding, erosion, and stormwater management challenges within the Napa River watershed.

Additionally, warmer temperatures may influence storm patterns and watershed conditions, potentially leading to more extreme precipitation events. As a result, severe weather hazards may interact more strongly with flood hazards, requiring continued monitoring, watershed management, and infrastructure maintenance to maintain resilience.

Severe weather hazards can affect residents, infrastructure, and natural resources throughout Napa County.

Vulnerable assets include transportation corridors, utilities, stormwater infrastructure, agricultural lands, and residential neighborhoods located in low-lying areas. Strong winds may damage trees and structures, while heavy rainfall can cause localized flooding, erosion, and debris accumulation in waterways.

Severe weather also poses secondary risks by increasing pressure on flood control infrastructure and drainage systems managed by NCFCWCD. Effective watershed maintenance, stormwater management, and emergency coordination are therefore essential to reducing impacts associated with severe weather events.

Heavy Rainfall & Storm Events
Heavy rainfall is one of the most significant severe weather hazards affecting NCFCWCD. Napa County experiences a Mediterranean climate characterized by wet winters and dry summers, with most precipitation occurring between November and April. During this period, Pacific storm systems and atmospheric rivers can deliver large volumes of rainfall over short periods. These storms can generate intense runoff within the Napa River watershed, increasing stream flows and placing pressure on drainage systems, channels, and flood control infrastructure.

Heavy rainfall events can lead to several secondary hazards including riverine flooding, localized urban flooding, erosion, and slope instability. Low-lying areas along the Napa Valley floor, particularly within developed portions of the City of Napa, are especially vulnerable when stormwater systems are overwhelmed or when runoff exceeds channel capacity. Agricultural lands throughout the valley may also experience inundation during extended storm events. Because heavy rainfall is the primary driver of flooding in the region, it represents one of the most important weather-related hazards affecting the District’s watershed management responsibilities.

Thunderstorms occur less frequently in Napa County than in other parts of the United States but can still develop during periods of atmospheric instability, particularly during late spring, summer, and early fall.

These storms may produce short-duration intense rainfall, lightning, gusty winds, and occasionally small hail. Although thunderstorms are typically localized and short-lived, they can generate intense rainfall that produces rapid runoff and localized flooding.

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Localized thunderstorms can overwhelm storm drains, culverts, and small channels if rainfall intensity exceeds drainage capacity. Lightning associated with thunderstorms also presents a hazard to infrastructure, vegetation, and outdoor activities. In rural or agricultural areas, thunderstorms may contribute to soil erosion or localized crop damage. While thunderstorms do not generally produce widespread flooding in Napa County, their potential to generate sudden heavy rainfall and wind gusts means they remain a relevant severe weather hazard within the region.

Strong Winds
High wind events occasionally occur in Napa County during winter storms or during periods of strong pressure gradients associated with passing weather systems. Wind speeds may increase as storms move through the region, particularly in elevated areas along the Mayacamas Mountains and Vaca Range, where topography can amplify wind intensity. While winds in Napa County are typically moderate compared with coastal regions, strong gusts during storm events can still cause damage to trees, structures, and utility infrastructure.

High winds can create secondary hazards by downing trees, damaging power lines, and depositing debris into waterways and storm drainage systems. Fallen vegetation and debris can obstruct channels and culverts, reducing flow capacity and increasing the potential for localized flooding during heavy rainfall events. Wind-related impacts may also cause temporary power outages or transportation disruptions.

Although high winds alone may not produce widespread structural damage in Napa County, they can significantly contribute to the cascading impacts associated with winter storm events.

Climate Change Hazard
Average annual temperatures across most of California have already increased by more than 1°F, with some areas experiencing rises of over 2°F when comparing the 1901–1960 average to that of 1986–2016. Daily maximum temperatures, a key indicator of extreme heat, are projected to increase by 4.4°F to 5.8°F by 2050 and by 5.6°F to 8.8°F by 2100. Heat waves that impact public health, known as heat-health events, are also expected to intensify across the state. By 2050, these events are projected to last up to two weeks longer in the Central Valley and occur four to ten times more often in the Northern Sierra region (California Natural Resources Agency, 2022).

California is already experiencing significant impacts from climate change, including prolonged drought, a lengthened wildfire season, increased coastal flooding and erosion, and widespread tree mortality. The state has observed rising average temperatures, more extreme heat days, fewer cold nights, a longer growing season, and shifts in the water cycle, with less winter precipitation falling as snow. In addition, summertime fog has declined by approximately 33%, and both snowmelt and rainwater runoff are occurring earlier in the year (Cal OES, 2018).

Long-term trends indicate a 12% to 20% decline in fog across California from 1900 through projections to 2070. Climate experts suggest that warming temperatures reduce the ability of air masses to cool enough to CAL OES SUBMITTAL - JUNE 2026
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produce fog, which plays a critical role in supporting California’s ecosystems (Grantham, Teodore; University of California, Berkeley, 2018).

Climate change is expected to influence the frequency, intensity, and impacts of several natural hazards affecting Napa County and NCFCWCD. Changes in temperature, precipitation patterns, and sea level are projected to alter watershed processes and increase the likelihood of certain hazard events. Because the district is responsible for flood control, watershed management, and water resource planning within the Napa River watershed, climate-related changes have important implications for long-term hazard mitigation and infrastructure planning.

One of the most significant projected climate impacts for Northern California is the potential for more intense precipitation events associated with atmospheric rivers. While total annual rainfall may not increase substantially, future storms are expected to deliver larger volumes of rain over shorter time periods.

These conditions can increase peak runoff within the Napa River watershed, placing greater stress on river channels, stormwater systems, and flood control infrastructure. Higher runoff rates may increase the likelihood of flooding, erosion, and sediment transport within the Napa River and its tributaries. More intense storm events could also exacerbate urban drainage issues and increase localized flooding in developed areas.

Climate change is also expected to contribute to warmer temperatures and longer dry periods, which can influence watershed conditions and water resource availability. Prolonged dry periods may reduce soil moisture and vegetation cover, potentially increasing erosion when storms eventually occur. These shifts may affect stream stability, sediment loads, and overall watershed function. Changes in seasonal precipitation patterns may also alter the timing of runoff and water availability within the watershed.

In addition, sea level rise in San Pablo Bay has the potential to influence downstream portions of the Napa River system. Rising water levels in the Bay can increase tidal influence within the lower Napa River, which may reduce the river’s ability to drain stormwater during high tides. This backwater effect can contribute to higher flood elevations in low-lying areas during storm events. As sea levels continue to rise over time, tidal flooding and storm surge may increase flood risk in downstream portions of the watershed.

Sea Level Rise
Sea level rise is an emerging hazard that may affect portions of the Napa River watershed within NCFCWCD.

The lower Napa River flows into San Pablo Bay, which is part of the larger San Francisco Bay Estuary. As global sea levels rise due to climate change, water levels within San Pablo Bay are expected to increase over time. Higher tidal water levels can influence the downstream portions of the Napa River by reducing the river’s ability to discharge stormwater during high tide conditions. This phenomenon, often referred to as tidal backwater effects, can increase water surface elevations in the lower river and contribute to higher flood levels during storm events.

Sea level rise may also increase the likelihood and extent of tidal flooding in low-lying areas near the southern portion of Napa County (Figure 8-7), particularly during high tides combined with storm surge or CAL OES SUBMITTAL - JUNE 2026
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heavy rainfall events. When elevated tides coincide with significant precipitation and increased river flows, water levels in the Napa River can rise more quickly and remain elevated for longer periods. This interaction between coastal and watershed processes can increase the potential for flooding in downstream areas of the river corridor.

Over time, rising sea levels may also influence sediment transport, channel dynamics, and wetland conditions within the Napa River estuary. Changes in tidal patterns and sediment deposition may affect channel conveyance and the function of natural floodplain areas. Wetlands and tidal marshes within the estuary play an important role in attenuating wave energy, storing floodwaters, and supporting habitat.

Protecting and restoring these natural systems can help reduce the impacts of sea level rise while maintaining ecological benefits.

Although the majority of the Napa Valley lies inland and at elevations above tidal influence, the potential effects of sea level rise in downstream portions of the watershed highlight the importance of long-term planning and adaptive management. Continued monitoring of tidal conditions, coordination with regional climate adaptation initiatives, and integration of sea level rise projections into infrastructure planning can help ensure that flood protection and watershed management systems remain resilient as climate conditions evolve.

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Figure 8-7: Exposure Summary – NCFCWCD Sea Level Rise Risk CAL OES SUBMITTAL - JUNE 2026
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8.5.3 Climate Change Impacts & Vulnerable Populations
Climate change is expected to influence several natural hazards affecting Napa County and NCFCWCD, including flooding, severe weather, drought, and extreme temperatures. Changes in precipitation patterns, increasing temperatures, and rising sea levels may alter watershed conditions and increase the severity or frequency of certain hazards. These changes can place additional stress on flood control infrastructure, stormwater systems, and water resources while also affecting communities that are more vulnerable to environmental and economic disruptions.

One of the primary climate-related concerns for Napa County is the potential for more intense precipitation events, particularly during atmospheric river storms. These storms can produce large amounts of rainfall over short periods, increasing runoff within the Napa River watershed and elevating flood risk along the Napa River and its tributaries. At the same time, longer and more frequent dry periods are projected to occur between storm events, which may contribute to drought conditions, reduced soil moisture, and increased wildfire risk in surrounding upland areas. Rising temperatures can also increase the frequency of extreme heat events, affecting public health and increasing demand on water and energy systems.

Climate change may also influence downstream flooding through sea level rise in San Pablo Bay, which can increase tidal influence in the lower Napa River system. Higher water levels in the Bay may reduce the river’s ability to discharge stormwater during high tide conditions, potentially increasing flood elevations in low-lying areas. These combined climate impacts highlight the importance of continued watershed management, infrastructure maintenance, and long-term planning to ensure that flood protection and water resource systems remain resilient.

Certain populations within Napa County may be more vulnerable to the impacts of climate-related hazards.

These include older adults, individuals with disabilities, low-income households, and residents living in flood-prone or environmentally sensitive areas. Older adults living alone may face additional challenges during emergencies such as evacuations or extended power outages. Households with limited financial resources may also have fewer options for recovering from hazard-related damages or implementing protective measures. In addition, residents who rely on public transportation or lack access to a personal vehicle may face barriers when responding to emergency situations.

Communities with limited English proficiency may also encounter challenges accessing hazard information, emergency alerts, or recovery assistance if communication materials are not available in accessible languages. Because Napa County includes a diverse population with varying socioeconomic conditions, it is important that hazard mitigation and climate adaptation strategies consider the needs of vulnerable populations. Ensuring equitable access to hazard information, preparedness resources, and recovery assistance can help reduce the disproportionate impacts of climate-related hazards and support community resilience throughout the watershed.

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8.5.4 Hazard Problem Statements
As part of the mitigation action identification process, the Planning Committee for each jurisdiction identified areas of concern (aka problem statements) for their respective facilities based on the risk assessment and vulnerability analysis, utilizing the RAMP mapping and static snapshot maps. Problem statements focused on the impact, victim, or threat that the hazard could create in the jurisdiction, as described in Table 8-11. Identifying common issues and weaknesses through these problem statements assisted the planning group in understanding the realm of resources needed for mitigation.

The goal is to have at least one mitigation action for every problem statement. Projects or actions have been developed to mitigate each problem identified. See Table 8-13 for a full list of mitigation actions and corresponding problem statements that they address. Each problem statement is coded with a problem number for cross-referencing between Table 8-11 and Table 8-13 Table 8-11: NCFCWCD Hazard Problem Statements
Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-CC-NCFC370Climate
Change
Impact Napa County
Flood Control
and Water
Conservation
District
Sea level rise and climate-driven
precipitation variability, exacerbated by king
tides, has changed local hydrologic
conditions and water elevations along the
lower Napa River and southern County areas,
threatening infrastructure and agricultural
lands.
ma-CC-NCFC244, ma-CCNCFC-245, maFL-NCFC-65
ps-CC-NCFC371Climate
Change
Impact Napa County
Flood Control
and Water
Conservation
District
Climate change is increasing the frequency
and severity of severe weather and flood, as
well as droughts and extreme heat events,
straining water resources, reducing
recharge, and challenging the District’s
water supply coordination, flood control,
restoration projects, and water management
operations.
ma-CC-NCFC244, ma-CCNCFC-245, maFL-NCFC-64, maFL-NCFC-65, maFL-NCFC-66, maSW-NCFC-243, ma-FL-NCFC-67
ps-FL-NCFC104Flood Victim Napa County
Flood Control
and Water
Conservation
District
Flood-prone residential structures in select
areas along the Napa River and its tributaries
remain unprotected by the incomplete
Measure “A” Flood Project, leading to
continued NFIP repetitive losses.
ma-FL-NCo-53,
ma-FL-NCFC-64,
ma-FL-NCFC-65,
ma-CC-NCFC245, ma-FLNCFC-67, maSW-NCFC-243
ps-FL-NCFC105Flood Threat Napa County
Flood Control
and Water
Conservation
District
Annual restoration and sediment
management along the Napa River and
tributaries are needed to sustain floodplain
function, water quality, and channel
conveyance.
ma-FL-NCFC-67,
ma-FL-NCFC-66,
ma-FL-NCFC-67,
ma-SW-NCFC243
ps-FL-NCFC106Flood Threat Napa County
Flood Control
and Water
Conservation
District
Creeks, River, and channels require routine
inspection and maintenance to prevent
sediment buildup, vegetation overgrowth,
and erosion that reduce channel capacity
and cause recurring local flooding.
ma-FL-NCFC-66,
ma-FL-NCFC-67
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-FL-NCFC107Flood Threat Napa County
Flood Control
and Water
Conservation
District
Invasive vegetation and exotic weeds reduce
stream capacity and increase localized flood
risk. Continuous management and
monitoring are required within the Stream
Maintenance Program.
ma-FL-NCFC-66,
ma-FL-NCFC-67
ps-SW-NCFC142Severe
Weather
Impact Napa County
Flood Control
and Water
Conservation
District
Severe weather events, including heavy rain
and high winds, can cause downed trees,
debris accumulation, and higher volume
discharges than system design, impacting
channel conveyance in the creeks and the
Napa River.
ma-SW-NCo-81,
ma-SW-NCo-82,
ma-AH-NCo-5,
ma-SW-NCFC123, ma-CCNCFC-245, maFL-NCFC-64, maFL-NCFC-66, maSW-NCFC-243

8.6 Mitigation Strategy
This section provides the framework for how NCFCWCD will reduce hazard risk within its jurisdiction while supporting the broader goals of the Napa County MJHMP. It includes an overview of existing capabilities, opportunities to strengthen resilience, and the district’s prioritized mitigation actions. Together, these elements demonstrate how NCFCWCD integrates hazard awareness into its planning and development processes while contributing to a coordinated countywide approach.

Within the Napa County MJHMP, the mitigation strategy serves as the roadmap for future hazard mitigation efforts. For NCFCWCD, the strategy outlined in this annex reflects the outcomes of the countywide planning process while also addressing the district’s unique risks, priorities, and community needs. The strategy is designed to reduce vulnerabilities identified in the risk assessment, including the problem statements developed for wildfire, earthquakes and severe weather, and climate change.

Mitigation actions identified in this annex include both policy-based and project-based initiatives, with an emphasis on integrating resilience into land use planning, infrastructure investments, and community programs. Actions are structured to align with FEMA’s requirements and to coordinate with existing district, county, and regional planning mechanisms. Each action identifies responsible parties, potential funding sources, and the resources needed for implementation.

For NCFCWCD, this strategy provides a framework for strengthening resilience by combining district-led initiatives, such as infrastructure improvements, and community preparedness, with regional coordination through the MJHMP. By advancing these efforts in alignment with the GSP and other local planning documents, NCFCWCD enhances its ability to reduce hazard risk while supporting long-term community safety, sustainability, and economic stability.

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The subsections that follow describe these elements in detail:
▪ Sections 8.6.1, Capabilities and Opportunities, provides a summary of the district’s capacity to address natural hazards.
▪ Section 8.6.2, Mitigation Action Plan, presents the district’s prioritized actions to guide implementation in coordination with countywide strategies. ▪ Section 8.6.3, Status of Previous Mitigation Actions, provides a summary of all previous actions and their current status, whether completed, cancelled, or revised.

Aligning the Action Plan
This section connects NCFCWCD’s mitigation actions with its existing capabilities and areas for growth.

Capability assessments are a required element of hazard mitigation planning under the Disaster Mitigation Act of 2000 and FEMA’s 2023 guidance, ensuring that actions are realistic, achievable, and aligned with available resources.

The section begins with a summary of NCFCWCD’s capabilities across four areas: planning and regulatory, administrative and technical, fiscal, and education and outreach. This overview highlights the tools and strengths that the district already uses to reduce hazard risk. The section then provides a detailed analysis of each capability area, identifying both current practices and opportunities to expand resilience.

8.6.1 Capabilities & Opportunities
This section provides a detailed assessment of the district’s current capabilities to support hazard mitigation, as well as future opportunities. This consists of describing how the NCFCWCD is planning for hazards and growth and a summary of its existing capabilities and the potential for enhancement.

Planning for Hazards & Growth
NCFCWCD plays an important role in coordinating watershed management, flood protection planning, and water resource stewardship across Napa County as development and population growth continue within the region. While the District itself does not control land use decisions, it works closely with Napa County and the incorporated cities of Napa, American Canyon, Calistoga, St. Helena, and Yountville to ensure that flood hazards, stormwater management, and watershed protection are considered during planning and development activities. Through this coordination, the district helps integrate hazard mitigation into broader planning efforts that guide future development patterns within the Napa River watershed.

Local land use policies within Napa County emphasize managed growth and protection of agricultural lands, which has resulted in relatively concentrated development within established urban areas along the Napa Valley floor. This approach helps limit expansion into environmentally sensitive areas and flood-prone lands while directing development toward locations where infrastructure and services already exist.

Nevertheless, continued population growth, housing demand, and redevelopment within cities can increase exposure to hazards if development occurs near waterways, drainage corridors, or low-lying areas. The CAL OES SUBMITTAL - JUNE 2026
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district therefore provides technical expertise and coordination related to floodplain management, watershed conditions, and drainage infrastructure to help reduce hazard exposure as communities grow.

Planning for hazards and growth also involves maintaining and improving watershed infrastructure that supports flood protection and stormwater management. The district’s ongoing stream maintenance activities, sediment management efforts, and coordination with regional stormwater programs help ensure that river channels and drainage systems continue to function effectively as land use patterns evolve. These activities help maintain conveyance capacity and reduce the risk that increased runoff from urban development will contribute to flooding or erosion.

In addition to infrastructure management, the district participates in regional planning initiatives and collaborates with state and federal partners to pursue funding opportunities for watershed improvements and flood mitigation projects. By coordinating with local governments and resource agencies, the district helps ensure that hazard mitigation considerations are incorporated into long-term planning decisions affecting watershed health, water resources, and flood protection throughout Napa County. This collaborative planning approach supports the district’s mission of protecting life, property, and natural resources while accommodating responsible growth within the watershed.

Development & Hazard Considerations
Development NCFCWCD is closely tied to the natural characteristics of the Napa River watershed and the broader planning policies that guide growth throughout Napa County. While most land use authority rests with Napa County and the incorporated cities within the watershed, hazard considerations, particularly those related to flooding, stormwater management, and watershed protection, are an important factor in evaluating new development and redevelopment projects. The district provides technical coordination and watershed expertise to help ensure that development activities account for flood risk, drainage capacity, and watershed conditions.

A significant portion of development in Napa County occurs along the Napa Valley floor, where relatively flat terrain and existing infrastructure support residential, commercial, and agricultural uses. However, many of these areas are located near the Napa River and its tributaries, which can expose development to flood hazards during major storm events. As a result, development proposals within or near flood-prone areas must consider floodplain conditions, stormwater runoff, and potential impacts to existing drainage systems. Integrating flood risk considerations into development planning helps reduce future vulnerability to flooding and supports long-term watershed resilience.

Urban development can also increase impervious surface coverage, such as roads, parking areas, and rooftops, which can accelerate stormwater runoff and increase peak flows in local waterways. Without appropriate stormwater management measures, these changes can contribute to localized flooding, erosion, and sediment transport within the watershed. To address these risks, development projects often incorporate drainage improvements, stormwater controls, and other measures designed to manage runoff and protect downstream waterways. Coordination with regional stormwater programs and adherence to CAL OES SUBMITTAL - JUNE 2026
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regulatory requirements help ensure that new development minimizes adverse impacts on watershed systems.

In addition to flood hazards, development within Napa County must consider other natural hazards such as severe weather, erosion, and potential slope instability in areas with steeper terrain. Planning for these hazards helps protect public safety and infrastructure while preserving the natural functions of streams and riparian corridors. By incorporating hazard considerations into development planning and infrastructure design, communities within the district’s service area can support sustainable growth while reducing long-term exposure to natural hazards.

Capabilities & Opportunities Assessment
To develop a realistic and actionable mitigation strategy, it must account for existing jurisdictional capabilities and what future opportunities there are to enhance those capabilities for purposes of hazard mitigation. This section provides an assessment of the district’s existing capabilities and future opportunities, including planning and regulatory, administrative and technical, fiscal, and public outreach and education capabilities. This assessment also identifies opportunities to integrate this MJHMP into future planning, policies, or programs to weave mitigation efforts into daily operations and address hazard problems wholistically. Capabilities are categorized into four groups and include various mechanisms. ▪ Planning and Regulatory Capabilities: Existing long-range plans, emergency response plans, hazard-specific plans, land use policies, and building and development standards. ▪ Administrative and Technical Capabilities: Available expertise in emergency services, engineering, grant management, and community planning.
▪ Fiscal Capabilities: Budgetary capacity, taxing authority, grants, and other funding mechanisms that can support mitigation projects.
▪ Outreach and Education Capabilities: Existing programs for providing technical assistance, community education, public warnings, and stakeholder engagement.

A full description of the process used to develop the capabilities assessment is provided in Volume 1, Section

2.3.3. The capabilities and opportunities assessment for NCFCWCD lists the various types of capabilities along with how they have been, currently are, or will in the future be integrated into hazard mitigation planning efforts. The three “HMP Integration” columns that identify the capability’s status and usage are color-coded with green, yellow, or orange shading to communicate the following:
▪ Status: If the capability is present at all and what level of use it has generally. ▪ Current Mitigation Use: If the capability is currently being used in mitigation efforts, specifically, and at what level.
▪ Future Opportunity: If there is a future opportunity to integrate the capability into mitigation efforts and at what level.

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Summary of Capabilities & Opportunities
This Capabilities and Opportunities Assessment for the NCFCWCD summarizes the various types of capabilities it has for hazard mitigation currently. The assessment also identifies opportunities to integrate, expand, and improve the district’s capabilities for future hazard mitigation. Table 8-12 provides a comprehensive list of capabilities and identifies the current status, current mitigation use, and future opportunities.

Planning & Regulatory
NCFCWCD has strong planning and regulatory capabilities related to flood risk reduction, watershed management, and stormwater coordination. The district’s capital improvement and maintenance programs, including the Napa River/Napa Creek Flood Protection Project and Annual Stream Maintenance Program, provide key hazard mitigation benefits by improving flood conveyance, maintaining channels, managing vegetation and sediment, and supporting nature-based “living river” flood protection approaches.

The district also participates in regional planning efforts that support stormwater management, groundwater sustainability, drought resilience, and watershed health. These include the Countywide Stormwater Management Program, coordination with the Napa Valley Groundwater Sustainability Agency, and participation in the Napa Valley Drought Contingency Plan. These partnerships demonstrate strong interagency coordination and support integrated water resource management.

Some hazard planning areas, including wildfire planning, Firewise programs, fire prevention, seismic safety, and earthquake modernization, are led by other agencies rather than the district. However, opportunities exist to strengthen internal preparedness for District facilities, better align stream corridor vegetation management with wildfire mitigation goals, expand nature-based and green infrastructure projects, and improve public outreach through bilingual materials and additional flood and stormwater education tools.

Future integration of the MJHMP will occur through various processes and mechanisms outlined across multiple mitigation actions (Table 8-13). Key opportunities for future hazard mitigation integration with the NCFCWCD existing planning mechanisms include incorporating the updated risk assessment, flood hazard data, and projected climate change impacts into the Sea Level Rise & Climate Impact Flood Modeling (maCC-NCFC-244), Climate Change Resilience Plan & Outreach (ma-CC-NCFC-245), Enhance Countywide Storm Watch System (ma-FL-NCFC-64), and Improved Stream Channel Inspection & Maintenance (ma-FL-NCFC66).

Administrative & Technical
NCFCWCD has administrative and technical resources that support hazard mitigation, flood infrastructure management, and coordination with partner agencies. Although the District is not a primary emergency response agency and does not maintain dedicated emergency management staff, it works closely with Napa County OES and other partners during flood events to provide technical information, monitor watershed conditions, and support response operations.

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The district’s strongest technical capabilities include engineering and GIS support. The District Engineer provides oversight for flood control infrastructure, watershed management, capital improvement projects, and evaluation of flood risk conditions. GIS capabilities are supported through Napa County PBES and help with watershed analysis, infrastructure mapping, emergency coordination, and data-driven hazard mitigation planning.

Public outreach is conducted mainly through the Countywide Stormwater Management Program and flood protection project communications, which provide education, updates, and watershed management information. Grant management and funding coordination are handled by administrative and analyst staff rather than a dedicated grant specialist. Expanding grant coordination capacity could strengthen the district’s ability to pursue additional funding for flood protection, watershed restoration, and hazard mitigation projects.

Warning Systems & Services
NCFCWCD benefits from countywide warning and emergency communication systems administered primarily by Napa County OES. These systems support public notification for floods, wildfires, severe weather, geological hazards, and other emergencies, helping residents, businesses, and responders maintain situational awareness and make evacuation decisions.

Key notification tools include ALERT Napa County, which sends emergency messages by phone, text, and email; national alert systems such as IPAWS and Wireless Emergency Alerts; the Genasys Protect platform, which provides mapped evacuation zones and real-time status updates; and the Hi-Lo siren system, which signals urgent evacuation conditions in certain areas. During flood, wildfire, and other hazard events, these systems provide timely evacuation warnings, orders, and hazard updates.

Although existing warning systems provide strong multi-hazard coverage, opportunities remain to expand early warning capabilities, including potential integration with earthquake early warning tools such as ShakeAlert. Continued coordination between NCFCWCD, Napa County OES, and regional partners will help ensure timely and accurate emergency information for communities within the Napa River watershed.

Fiscal
NCFCWCD has several fiscal capabilities that support hazard mitigation, flood infrastructure maintenance, and watershed management. Historically, Measure A was a major funding source for large-scale flood protection projects, providing local sales tax revenue for projects such as flood risk reduction infrastructure.

Although the sales tax has sunset, a maintenance fund remains to support ongoing operation and maintenance of flood protection facilities.

The district does not function as a retail water utility and does not rely on traditional utility fees, development impact fees, or system development charges as primary revenue sources. Instead, its fiscal role is focused on flood control, watershed management, stormwater coordination, and regional CAL OES SUBMITTAL - JUNE 2026
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partnerships. The district also administers State Water Project contracts involving pass-through costs and administrative fees.

NCFCWCD has used debt financing and interagency funding mechanisms in the past, including State Revolving Fund loans and regional Flood Authority debt, to support infrastructure investments. Capital projects are typically funded through a mix of local assessments, grants, adopted District budgets, and partner agency contributions. The Napa Countywide Stormwater Pollution Prevention Program, funded by member agencies and administered through the district, further supports compliance, inspections, pollution prevention, watershed protection, and flood mitigation activities.

Education & Outreach
NCFCWCD benefits from a variety of education and outreach resources that support hazard awareness, emergency preparedness, and watershed stewardship. Many of these efforts are coordinated through Napa County OES and countywide programs, including Ready Napa County, which provides information on hazard awareness, emergency alerts, preparedness planning, evacuation readiness, and recovery.

Public communication is supported through county social media channels, NCFCWCD’s social media presence, emergency preparedness guides, stormwater program materials, and district website resources.

These tools help share emergency updates, flood protection project information, flood concern reporting procedures, watershed management updates, and stormwater education.

Additional outreach is supported through partnerships with Fire Safe Councils, Firewise programs, and the Napa County Resource Conservation District. These partners provide education related to wildfire risk reduction, fuels management, watershed protection, habitat stewardship, and environmental monitoring.

Together, these resources provide a strong foundation for public education, with opportunities to continue expanding hazard preparedness and watershed-focused outreach.

ASSESSMENT LEGEND
HMP Integration
Status Current Mitigation Use Future Opportunity
Currently in use or present. Used widely for mitigation. Opportunity to expand and integrate. (Sort of) Seldomly used or limited
presence.

Limited use in mitigation planning. Limited opportunity to expand and integrate. (No) Not present or available. Not used in mitigation planning. No opportunity to expand or integrate.

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Table 8-12: NCFCWCD Capabilities and Opportunities Assessment HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Hazard Reduction Programs
(Annually Conducted)
Capital Improvements Program
(CIP) or Plan
Green Green Green
Napa River/Napa Creek Flood Protection
Project uses “living river” design toward 100-
year protection; Stream Maintenance &
Watershed Management provide annual
vegetation/sediment/channel maintenance;
Board routinely approves annual SMP work
(e.g., CCC crews)
Annual Fire Prevention Plan
Orange Orange Orange
District is not a fire agency; no standalone
annual fire prevention plan—coordinate
vegetation/fuels work along channels with
County Fire/Cal Fire as a co-benefit
Seismic Safety Program (Nonstructural) Orange Orange Orange No standalone non-structural seismic safety
program published; opportunity to formalize
preparedness/continuity for District facilities
Earthquake Modernization Plan
(Building Safety)
Orange Orange Orange
District is not a building-safety AHJ; no
earthquake modernization plan—track hostjurisdiction building-safety updates for District facilities
Stormwater Management
Program (Annual Inspections)
Green Green Green
Countywide Stormwater Management
Program (NCSPPP) conducts compliance
activities and annual reporting; coordinates
inspections and pollution prevention across
jurisdictions; opportunity to expand green
infrastructure and monitoring
Hazard Plans and Programs
Floodplain Response Plan
Green Green Green
Napa County OES maintains the Emergency
Operations Plan; county floodplain regulations
guide response and recovery; opportunity to tie
actions to gauge thresholds and evacuation
zones
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Community Wildfire Protection
Plan (CWPP)
Orange Orange Yellow
District supports wildfire-related access/fuels
work where it intersects riparian/stream
corridors; primary CWPP ownership is fire
agencies; align channel vegetation with
evacuation-corridor priorities
Ground Water Management
Planning / Plans
Green Green Green
Participates with County GSA on the Napa
Valley Subbasin Groundwater Sustainability
Plan; coordinates data/GIS and watershed
linkages; expand multi-benefit recharge and
floodplain projects
Climate Action Plan
Orange Orange Yellow
Collaborates through the Regional Climate
Action & Adaptation Plan; integrate flood-risk
reduction and nature-based solutions into
RCAAP actions
Drought Mgmt/ Contingency
Plan
Green Green Green
Participates in the Napa Valley Drought
Contingency Plan with regional agencies;
coordinate drought–flood nexus projects such
as recharge and storage operations
FireWise Communities within
District
Orange Orange Yellow
Firewise administration lies outside the
District; coordinate stream access and fuels
work where relevant to Firewise
neighborhoods; use official county readiness
channels for public info
Hazard-Related Public Outreach
Program
Green Green Green
Countywide Stormwater Program (NCSPPP)
and Flood Project pages provide education and
annual reporting; expand bilingual materials
and project dashboards
Administrative and
Technical
Staff Capacity
Emergency Manager
Orange Orange Green
OES maintains County emergency plans and
ALERT Napa County; District coordinates
during flood events
Civil Engineer
Green Green Green Andrew S. Butler, P.E., District Engineer provides design/oversight for flood projects
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Dedicated Public Outreach
Personnel Orange Orange Green
Stormwater Program (NCSPPP) and Flood
Project pages provide outreach and public
information
GIS Specialist and Capability
Green Green Green GIS capability provided via County PBES GIS (Matt Lamborn); used by District/OES
Grant Manager, Writer, or
Specialist Orange Orange Green Grants handled by administrative/analyst staff; no dedicated grant specialist listed
Other

N/A N/A N/A
Warning Systems/Services
General
Green Green Green
ALERT Napa County provides county-wide
mass notifications; evacuation zones and
status are displayed in Genasys Protect;
County also uses IPAWS/WEA and Hi-Lo sirens
Flood
Green Green Green
Flood evacuations: ALERT Napa County sends
notices with a link to Genasys Protect to view
mapped zones; residents instructed to monitor
Genasys and official channels
Wildfire
Orange Orange Orange
Wildfire evacuations: ALERT Napa County +
Genasys zones with Hi-Lo siren as the audible
“time to go” signal
Geological Hazards
Orange Orange Orange
Geologic hazards: urgent messages delivered
through IPAWS/WEA and ALERT; opportunity
to explore ShakeAlert integration for
earthquakes
Fiscal Capabilities
Financial Resources for
Hazard Mitigation
Levy for Specific Purposes with
Voter Approval Yellow Yellow Yellow
Measure A funded local share of flood
protection; after sunset, a maintenance fund
remains for Flood Project costs
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Utilities Fees
Yellow Yellow Yellow
District administers State Water Project
contracts with pass-through costs and an
admin fee; not a retail utility
System Development Fee
Orange Orange Yellow District does not levy development impact fees; role centers on flood/watershed programs
General Obligation Bonds to
Incur Debt Yellow Yellow Green
Debt tools have been used via partner
mechanisms (e.g., SRF loan) and through the
Flood Authority during Measure A
Special Tax Bonds to Incur Debt
Yellow Yellow Yellow
Sales-tax backed debt was managed by the
Flood Authority; could be re-established only
with new voter revenue
Withheld Spending in HazardProne Areas Yellow Yellow Yellow Project approach emphasizes flood-risk
reduction; land-use siting policies lie with
cities/county
Stormwater Service Fees
Yellow Yellow Green
NCSPPP is funded by member agencies and
administered by the District’s stormwater
manager
Capital Improvement Project
Funding Green Green Green
Capital projects are funded through local
assessments, state/federal grants, and
annually adopted District budgets
Education / Outreach
Capabilities
Education/Outreach
Resources
Website Dedicated to Hazard
Topics Orange Orange Orange
Ready Napa County is the official county
emergency website with preparedness, alerts,
and recovery pages
Dedicated Social Media
Green Green Green
Official County Facebook and the District’s
Instagram highlight emergency updates and
flood control projects
Hazard Info. Avail. at Library/
Planning Desk Green Green Green Flood District Office
Annual Public Safety Events
Orange Orange Orange
Ready Napa County features preparedness
campaigns that can anchor recurring annual
public safety events
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Ability to Field Public Tech.

Assistance Requests Yellow Yellow Yellow
Flood Control District page provides reporting
guidance; county FAQ lists Floodplain
Management contact
Public Safety Newsletters or
Printed Outreach Green Green Green Materials available at Flood District Office Fire Safe Councils
Orange Orange Orange
County pages support Fire Safe
Council/Firewise efforts with fuels-reduction
resources and funding information
Resource Conservation Districts
Orange Orange Orange
Napa County RCD partners on watershed
education and monitoring with public
resources available online
Other

N/A N/A N/A
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8.6.2 NCFCWCD Mitigation Action Plan
NCFCWCD’s mitigation
actions were developed
through a collaborative
process informed by the
updated risk
assessment, local
priorities, and extensive
stakeholder
engagement. As part of
this 2026 MJHMP
update, the district
reviewed mitigation
actions from its prior
Local Hazard Mitigation
Plan to determine which
actions to carry forward,
which to consolidate,
and where entirely new
strategies were
required. This careful
evaluation ensured that
the updated action plan builds upon past commitments while also responding to current risks and future challenges. These new actions were crafted to address the district’s highest priority hazards, align with FEMA’s hazard mitigation guidance, and reflect local infrastructure vulnerabilities and water resource challenges. The development of these mitigation strategies marks an important step in integrating resilience into the district’s operations and long-term planning. All mitigation actions are documented in Volume 2, Table 8-13. This careful evaluation ensured that the updated action plan builds upon past commitments while also responding to current risks and future challenges.

The plan addresses NCFCWCD’s most significant hazards, including flood, severe weather, and climate change. Each mitigation action is designed to align with FEMA’s hazard mitigation guidance and the requirements of the Disaster Mitigation Act of 2000. Where appropriate, overlapping or redundant actions were consolidated into broader, more comprehensive strategies that improve clarity, increase feasibility, and strengthen regional coordination.

The mitigation action prioritization method used by all participating jurisdictions is described in Volume 1, Section 4. Each action specific to NCFCWCD is documented in Table 8-13, which identifies the responsible department, implementation timeframe, potential funding sources, and resources required to complete the Figure 8-8: Mitigation Action Number Key
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action. Each action is also assigned a unique alphanumeric identifier (see Figure 8-8) that links the strategy to its associated hazard and supports consistent monitoring and reporting.

NCFCWCD’s approach recognizes that some hazards are most effectively addressed through regional efforts. Weather and flood reduction often extend beyond the district’s boundaries and require collaboration with county, regional, and state partners. By aligning local actions with regional strategies, NCFCWCD helps to consolidate resources, maximize funding opportunities, and ensure that mitigation projects achieve the greatest benefit for San Pablo Bay, the Napa Valley, and the wider Napa County community.

Collectively, these mitigation actions provide a roadmap for reducing hazard risk, protecting vulnerable populations, and strengthening the long-term resilience of NCFCWCD.

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Table 8-13: NCFCWCD Mitigation Action Plan
Mitigation No. Hazard
Type
SubHazardMitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-CC-NCFC244Climate
Change
Sea Level
Rise
PRV -
Prevention
2026 Napa County
Flood
Control and
Water
Conservation
District
Sea Level
Rise &
Climate
Impact Flood
Modeling
Update hydrologic and flood models to account
for anticipated sea-level rise and climateadjusted rainfall intensities.

Engineering Medium Low 3-5 Years Project HMGP / BRIC ,
General Fund
Medium ps-CC-NCFC-370, ps-CCNCFC-371
ma-CC-NCFC245Climate
Change
PRV -
Prevention ,
PE&A - Public
Education &
Awareness
2026 Napa County
Flood
Control and
Water
Conservation
District
Climate
Change
Resilience
Plan &
Outreach
Collaborate with others to develop a climate
change resilience plan that identifies adaptive
water operation and conservation strategies, as
well as public outreach strategies for a range of
future scenarios (e.g., severe weather, sea-level
rise, extreme heat, and extended drought).

Administration Low Medium 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Low ps-CC-NCFC-371, ps-CCNCFC-370, ps-SW-NCFC-142,
ps-FL-NCFC-104
ma-FL-NCFC64Flood ES -
Emergency
Services
2013 Napa County
Flood
Control and
Water
Conservation
District
Enhance
Countywide
Storm Watch
System
Enhance stream flow/level and precipitation
monitoring system, including expanded data
sharing and collaboration with regional
partners and addition of key monitoring points
as needed.

Engineering Medium High 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
FMA , General
Fund
Medium ps-FL-NCFC-103, ps-FLNCFC-104, ps-SW-NCFC-142,
ps-CC-NCFC-371
ma-FL-NCFC65Flood SP - Structural
Projects
2013 Napa County
Flood
Control and
Water
Conservation
District
Measure “A”
Flood Control
Completion
Complete final construction phases of the
Measure “A” Flood Control Project and re-map
the City of Napa floodplain to reflect new
extent, including evaluation of areas outside
floodwall projects.

Engineering High High 3-5 Years Project HMGP / BRIC ,
FMA , General
Fund
High ps-FL-NCFC-103, ps-FLNCFC-104, ps-CC-NCFC-370,
ps-CC-NCFC-371
ma-FL-NCFC66Flood PRV -
Prevention ,
NRP - Natural
Resource
Protection
2013 Napa County
Flood
Control and
Water
Conservation
District
Improved
Stream
Channel
Inspection &
Maintenance
Implement improved annual inspection and
maintenance procedures for stormwater
channels to prevent trash and debris
accumulation, sedimentation and gravel
buildup, invasive species and vegetation
encroachment, and erosion and bank
stabilization impacts.

Engineering Low High 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
FMA , General
Fund
High ps-FL-NCFC-103, ps-FLNCFC-107, ps-FL-NCFC-106,
ps-SW-NCFC-142, ps-FLNCFC-105, ps-CC-NCFC-371
ma-FL-NCFC67Flood NRP - Natural
Resource
Protection
2013 Napa County
Flood
Control and
Water
Conservation
District
Napa River
Restoration
Program
Design and implement projects along the Napa
River that restore floodplain functionality and
connectivity to support increased flood
resilience, enhanced recreational opportunities,
and improved fish habitat.

Engineering High High 5-10 Years Project HMGP / BRIC ,
FMA , General
Fund
Medium ps-FL-NCFC-103, ps-FLNCFC-105, ps-FL-NCFC-104,
ps-FL-NCFC-105, ps-FLNCFC-106, ps-FL-NCFC-107,
ps-CC-NCFC-371
ma-SW-NCFC243Severe
Weather
NRP - Natural
Resource
Protection , SP
- Structural
Projects
2026 Napa County
Flood
Control and
Water
Conservation
District
Stormwater
Capacity
Improvement
Program
Identify, assess, and upgrade undersized
culverts, detention basins, storm drains, and
other stormwater infrastructure to manage
high-intensity rainfall, including through
nature-based and green infrastructure
solutions.

Engineering High High 3-5 Years Project HMGP / BRIC ,
FMA , General
Fund
Medium ps-SW-NCFC-142, ps-FLNCFC-104, ps-FL-NCFC-105,
ps-CC-NCFC-371
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8.6.3 Status of Previous Mitigation Actions
In 2020, the NCFCWCD adopted its previous FEMA-approved HMP. This 2026 MJHMP represents a comprehensive update from that previous plan, as discussed in Volume 1, Section 1.5. Table 8-14 provides status updates for all of the previous mitigation actions in the NCFCWCD HMP, from which many of the mitigation actions in Table 8-13 were sourced and revised.

Table 8-14: NCFCWCD Status of Previous Mitigation Actions Mitigation
No.

Hazard
Type
Status Year Primary
Agency
Title/Description Reason Cancelled/
Completed
ma-FLNCFC-64Flood Ongoing 2013 NCFCWCD Enhance Countywide Storm Watch System
Revised
ma-FLNCFC-65Flood Ongoing 2013 NCFCWCD Measure “A” Flood Control Completion
Revised
ma-FLNCFC-66Flood Ongoing 2013 NCFCWCD Improved Stream Channel Inspection & Maintenance
Revised
ma-FLNCFC-67Flood Ongoing 2013 NCFCWCD Napa River Restoration Program Revised ma-SWNCFC-123Severe
Weather
Cancelled 2020 NCFCWCD Routinely inspect storm water
channels for vegetation build up
or encroachment, trash and
debris, silt and gravel build up,
and erosion or bank failure
NFC-03-2013 & NFC-204-2020
combined and revised
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Section 9. Napa County Office of Education
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Napa County
2026 Multi-Jurisdictional Hazard Mitigation Plan Update Napa County Office of Education (NCOE)
Special Agency Annex
Section 9. Napa County Office of Education..........................................................................9-7

9.1 Scope & Purpose .....................................................................................................................................................................9-7

9.2 Jurisdictional Setting...........................................................................................................................................................9-7

9.2.1 Geography & Climate ..................................................................................................................................................9-8

9.2.2 Campus Building Inventory & Lifelines .............................................................................................................9-11

9.2.3 Student Body & Staff .................................................................................................................................................9-12

9.2.4 Income & Housing......................................................................................................................................................9-14

9.2.5 Race, Ethnicity & Language ...................................................................................................................................9-16

9.2.6 Social Vulnerability Index (SVI) ...........................................................................................................................9-18

9.2.7 Economy........................................................................................................................................................................9-19

9.2.8 Growth Trends & Future Development..............................................................................................................9-19

9.3 Planning Process .................................................................................................................................................................9-20

9.3.1 Public Input & Draft Review ...................................................................................................................................9-22

9.4 What’s New.............................................................................................................................................................................9-23

9.4.1 Mitigation Activities .................................................................................................................................................9-23

9.4.2 Mitigation Successes............................................................................................................................................... 9-24

9.5 Risk Assessment..................................................................................................................................................................9-25

9.5.1 Hazard Screening & Prioritization ......................................................................................................................9-25

9.5.2 Vulnerability to Specific Hazards........................................................................................................................9-29

9.5.3 Climate Change Impacts & Vulnerable Populations................................................................................... 9-47

9.5.4 Hazard Problem Statements................................................................................................................................. 9-48

9.6 Mitigation Strategy ............................................................................................................................................................. 9-51

9.6.1 Capabilities & Opportunities..................................................................................................................................9-52

9.6.2 Napa County Office of Education Mitigation Action Plan.........................................................................9-60

9.6.3 Status of Previous Mitigation Actions.............................................................................................................. 9-64 CAL OES SUBMITTAL - JUNE 2026
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List of Figures
Figure 9-1: NCOE Geographic Overview Map........................................................................................................................9-10 Figure 9-2: NCOE Risk Assessment Matrix........................................................................................................................... 9-27 Figure 9-3: NCOE Wildfire Risk...................................................................................................................................................9-31 Figure 9-4: NCOE Earthquake Risk (M7.1 Hunting Creek Berryessa).......................................................................... 9-34 Figure 9-5: NCOE Earthquake Risk (M6.7 West Napa) .......................................................................................................9-35 Figure 9-6: NCOE Flood Risk....................................................................................................................................................... 9-38 Figure 9-7: Drought Severity Timeline 2000-2025 ..............................................................................................................9-41 Figure 9-8: Mitigation Action Number Key........................................................................................................................... 9-60 List of Tables
Table 9-1: Napa County Schools Student and Staff Population .....................................................................................9-14 Table 9-2: Napa County Income and Poverty........................................................................................................................9-14 Table 9-3: Napa County Renter- and Owner-Occupied Housing...................................................................................9-15 Table 9-4: Student Homeless Counts by District .................................................................................................................9-16 Table 9-5: Student Ethnicity by District...................................................................................................................................9-17 Table 9-6: ELAS Learners by District........................................................................................................................................9-18 Table 9-7: Student Enrollment from 2015 to 2025 (All Districts)................................................................................... 9-20 Table 9-8: NCOE Planning Team and Steering Group Members ...................................................................................9-21 Table 9-9: NCOE Planning Team Meetings........................................................................................................................... 9-22 Table 9-10: NCOE Document Review of Potential Hazards............................................................................................. 9-26 Table 9-11: NCOE Hazards Prioritization Summary........................................................................................................... 9-28 Table 9-12: NCOE Facility Wildfire Exposure........................................................................................................................ 9-32 Table 9-13: Drought Classifications and Impacts ............................................................................................................... 9-40 Table 9-14: Cal-Adapt Extreme Heat Terms and Thresholds.........................................................................................9-44 Table 9-15: NCOE Hazard Problem Statements ................................................................................................................... 9-48 Table 9-16: NCOE Capabilities and Opportunities Assessment.....................................................................................9-57 Table 9-17: NCOE Mitigation Action Plan .............................................................................................................................. 9-62 Table 9-18: NCOE Status of Previous Mitigation Actions ................................................................................................ 9-64 CAL OES SUBMITTAL - JUNE 2026
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Adoption Resolution
To comply with the Federal Disaster Mitigation Act of 2000 (DMA 2000), the Napa County Office of Education has officially adopted this 2026 Napa County Multi-Jurisdictional Hazard Mitigation Plan, including Volume 1 in its entirety as well as this Volume 2 municipal annex. The adoption of the MJHMP recognizes the agency’s commitment to reducing the impacts of natural hazards within its jurisdiction and across Napa County.

A copy of the agency’s adoption record is provided on the following pages. Adoption records for all jurisdictions are summarized in Volume 1, Table ES-1.

ADOPTION RECORD TO BE INSERTED UPON COMPLETION.

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Section 9.Napa County Office of Education

9.1 Scope & Purpose
This Jurisdictional Annex for the Napa County Office of Education of the 2026 Napa County Multi-Jurisdictional Hazard Mitigation Plan (MJHMP) details the hazard mitigation planning elements specific to the agency’s planning area. The annex is not intended to be a standalone document but appends to and supplements the information contained in the umbrella plan document (Volume 1). As such, all sections of the umbrella plan, including the planning process and other procedural requirements, apply to and were met by the Napa County Office of Education.

This annex provides additional information specific to the city, with a focus on hazard identification and risk assessment, vulnerability assessment, problem statements, mitigation strategy, and capabilities assessment. Below are the Napa County Office of Education Points of Contact:

Primary Point of Contact Alternate Point of Contact
Joshua Schultz, Deputy Superintendent
Napa County Office of Education
2121 Imola Avenue
Napa, CA 94559
Telephone: (707) 253-6810
email: [email protected]
Angel Hernandez, OES Officer
Napa County Office of Education
2121 Imola Avenue
Napa, CA 94559
Telephone: (707) 253-6810
email: [email protected]

9.2 Jurisdictional Setting
The Napa County Office of Education is a county-wide agency that provides support and services to local school districts in Napa County. The agency responsibilities include: 1) ensuring school districts are fiscally accountable and solvent; 2) reviewing and approving school districts Local Control Accountability Plans; 3) providing professional development opportunities; 4) assisting school districts with academic performance initiatives; and 5) providing education to vulnerable students (i.e., those that have been expelled, are incarcerated, are on probation, have severe special needs, and who are early learners). The Office of Education is headed by a County Superintendent and governed by an elected Board of Trustees.

The Office of Education is headquartered in the City of Napa at 2121 Imola Avenue. Several programs are operated out of the Imola Avenue location, as well as the neighboring Camille Creek Community School.

The Office of Education also partners with various agencies and service providers who operate at various locations in Napa County that are owned by other public agencies or private entities. For example, the Office of Education partners with Early Learning Services and Child Start, Inc. to operate preschool programs at nine different classrooms across Napa County. One such location is at a property on Myrtle Avenue in the City of Napa owned and operated by the Napa Valley Unified School District that contains several other educational facilities and a football stadium.

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This planning effort for the Napa County Office of Education establishes a comprehensive risk assessment framework that encompasses all school districts operating under its jurisdiction. Consistent with the requirements of FEMA’s Local Mitigation Planning guidance, the risk assessment systematically identifies hazards, evaluates the exposure of educational facilities and populations, and analyzes potential impacts to school infrastructure, operations, and continuity of services. By integrating district-level data into a unified assessment, this effort ensures that vulnerabilities across all campuses and administrative facilities are consistently evaluated, supporting coordinated mitigation strategies and informed decision-making. This approach aligns with the multi-jurisdictional planning structure of the Napa County MJHMP, which incorporates annexes for participating entities, including the Napa County Office of Education , and reflects FEMA’s emphasis on risk-informed planning as the foundation for effective hazard mitigation and resilience-building .

Accordingly, the Office of Education’s role in facility-specific risk and emergency preparedness planning is inherently limited for sites that are owned or operated by third parties. While Office of Education staff may be present at these facilities to support educational services, responsibility for maintenance, structural safety, and primary emergency planning remains with the respective property owners or operating agencies. As a result, the Office of Education typically participates in preparedness and coordination efforts in a supporting or advisory capacity, rather than as the lead agency. This distinction is important for accurately defining roles and responsibilities within the mitigation strategy and ensures alignment with FEMA guidance emphasizing clear delineation of jurisdictional authority and capabilities in multijurisdictional planning efforts. ▪ Year of Establishment: 1955
▪ Student Population (All Napa County School District): 18,585 ▪ Staff Population (All Napa County School District): 849 ▪ Population Growth (2015-2025, All Napa County School Districts): -11.5% decrease

9.2.1 Geography & Climate
Napa County encompasses 788 square miles in the North Bay region of the San Francisco Bay Area metropolitan area. The County is bordered by Sonoma County (west), Lake County (north), and Solano County (east and south). Significant topographical features include Mount Saint Helena, the Mayacamas Mountains, the Howell Mountains, the Vaca Mountains, Napa Valley, Pope Valley, and Wooden Valley. The county encompasses several incorporated communities, including the cities of American Canyon, Calistoga, Napa, St. Helena, and the Town of Yountville, along with unincorporated areas such as Angwin, Berryessa Highlands, Deer Park, Oakville, Pope Valley, Rutherford, and Spanish Flat. Figure 9-1 provides a geographic overview of Napa County.

Hydrologically, most of Napa County is within the Napa River watershed, which conveys water from the slopes of Mount Saint Helena in the northern portion of the county to San Pablo Bay in the southern portion of the county. The eastern portion of the county is within the Lake Berryessa (Putah Creek) watershed. Lake Berryessa is impounded by Monticello Dam, owned by the United States Bureau of Reclamation, and operated by Solano Irrigation District. A significant amount of Lake Berryessa water is diverted into the CAL OES SUBMITTAL - JUNE 2026
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Putah South Canal, which is part of the Solano Project, and wheeled to Fairfiled, Suisun City, Vacaville, Vallejo and agricultural customers.

The general climate of Napa County can be described as Mediterranean, with cool, wet winters and warm, dry summers. It varies slightly across the county due to terrain and geography. For example, the southern end of the valley, where American Canyon and the City of Napa are located, is cooler than the northern part of the county due to its location near San Pablo Bay (the northern tip of the San Francisco Bay). Winds from the bay cool southern Napa County as far north as Yountville. The St. Helena and Calistoga areas do not encounter those cooling winds and thus tend to be much warmer.

Average annual rainfall in Napa County is less than 21 inches, with over half of the rain occurring in the winter months of December, January, and February. (U.S. Climate Data, 2020) The western side of the valley, in the Mayacamas Mountains, gets more rain and supports redwood and fir forests and numerous water bodies and features. The eastern side of the valley, in the Vacas Mountains, receives much less rain and has desert-like characteristics with scrub brush and cactus. Temperatures in Napa County typically range from a winter high temperature of 55 degrees Fahrenheit (°F) in January and an average summer high of 80°F.

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