Agenda packet — Portola City Council, June 10, 2026 (part 8 of 14)

Plumas County GMCSD Annex D-2
Local Hazard Mitigation Plan Update
January 2026
Figure D-1 GMCSD
D.3.1. Overview and Background
Gold Mountain Community Services District (GMCSD) provides fire suppression, fire prevention, emergency medical, retail water delivery, and wastewater collection and disposal. Fire and EMS services are provided via a contract with the City of Portola. Road maintenance and snow removal are provided by the Gold Mountain Homeowner’s Association.

GMCSD was formed in 1996 as a dependent special district, when members from the Board of Supervisors were designated as the District’s Board of Directors. In 2005, the board of directors was expanded to include five members and GMCSD became an independent service district. The principal act that governs the District is the State of California Community Services District Law. CSDs may potentially provide a wide array of services, including water supply, wastewater, solid waste, police and fire protection, street lighting and landscaping, airport, recreation and parks, mosquito abatement, library services; street maintenance and drainage services, ambulance service, utility undergrounding, transportation, abate graffiti, flood protection, weed abatement, hydroelectric power, among various other services.

The District was formed to serve the water, wastewater, and fire protection requirements for the Gold Mountain planned development, a predominately senior, retirement golf course and mountain community.

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Plumas County GMCSD Annex D-3
Local Hazard Mitigation Plan Update
January 2026
Two thirds of the developed residential structures are second homes or vacation homes resulting in a higher population during the summer months and a low winter population. Open year round, the resort population fluctuates dramatically between winter and summer, with upwards of several hundred guests during peak season weekend events. The District provides domestic water to residences and the resort from four deep granite wells, distributing water though nine pressure zones served by seven lift stations. The resort maintains its own golf course irrigation system fed by wells using the same deep granite aquifers shared with the District. To date, there is little evidence of any aquifer deterioration.

GMCSD is located in the eastern part of Plumas County, about three miles south and west of the City of Portola. The District borders the Feather River in the west, EPRFPD in the north, and the Plumas National Forest in the east and south. GMCSD’s boundary is entirely within Plumas County. The District’s boundaries encompass approximately 1,294 acres or two square miles. Since its formation, there have been no annexations to or detachments from GMCSD. There are elevation changes inside the District, as shown on Figure D-2.

Figure D-2 GMCSD - Elevation Map

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Plumas County GMCSD Annex D-4
Local Hazard Mitigation Plan Update
January 2026
D.4 Risk Assessment
As defined by FEMA, risk is a combination of hazard, vulnerability, and exposure. “It is the impact that a hazard would have on people, services, facilities, and structures in a community and refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.” The GMCSD risk assessment identifies and profiles relevant hazards and assesses the exposure of lives, property, infrastructure, and the environment to these hazards. The process allows for a better understanding of the District’s potential risk and vulnerability to hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

Building on the District Profile above, a risk assessment was performed for the District. This includes the following sections:
➢ D.4.1 Assets Inventory and Growth and Development Trends ➢ D.4.2 Hazard Identification
➢ D.4.3 Hazard Profiles and Vulnerability to Specific Hazards D.4.1. Assets Inventory and Growth and Development Trends This section provides an inventory of the GMCSD’s total assets potentially at risk to hazards and an overview of growth and development trends. This section is broken into two parts:
➢ Asset Inventory – The assets inventory identifies the GMCSD’s total assets, including the people and populations; structures; critical facilities and infrastructure; community lifelines; natural, historic, and cultural resources; and economic assets and community activities of value. This data is not hazard specific, but is representative of total assets within the District, potentially at risk to identified hazards as discussed in Section D.4.3 Hazard Profiles and Vulnerability to Specific Hazards. ➢ Growth and Development Trends – A discussion of growth and development trends in the District, both current and future, is presented.

Assets Inventory
The District’s asset inventory is detailed in the following sections:
➢ People and Populations
➢ Structures
➢ Critical Facilities and Infrastructure
➢ Community Lifelines
➢ Natural, Historic, and Cultural Resources
➢ Economic Assets and Community Activities of Value
A discussion of each of these assets follows and serves as the template for the asset discussion for each hazard in Section D.4.3.

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Plumas County GMCSD Annex D-5
Local Hazard Mitigation Plan Update
January 2026
People and Populations
The most important asset within any community are the people and populations that reside in the community. People and populations in the District include both District staff and workers as well as those populations located within District boundaries and are served by the District. This section includes an inventory of past and current populations of the District and also discusses vulnerable populations and underserved communities as a subsection of people and populations located within the District and potentially at risk to hazards. Information from the District and other sources as detailed below form the basis of this discussion.

Historic Population Trends and Current Population
The most important asset within any community are the people and populations that reside in the District.

The District has 5 staff. In In addition to District staff, the District provides services to 102 private residential structures, seven commercial residential properties, and two private residences under construction. Based on a household size slightly less than the County average of 2.1 people per household, the estimated population of GMCSD is 180. However, the District estimates that less than one quarter of these residences are occupied on a full-time basis. Summer resort business adds significant numbers to the local population including the hotel, rental units, and resort guests. Based on GIS analysis of 2020 Census data, it is estimated that there are approximately 76 residents that make use of the area as their primary residence. The population of the area tends to be mostly those over the age of 50.

Structures and Critical Facilities
This section considers the GMCSD’s assets at risk, with a focus on key District assets such as critical facilities and infrastructure, and other District assets and their values. With respect to District assets, the majority of these assets are considered critical facilities as defined for this Plan. Critical facilities are defined for this Plan as:

Any facility, including without limitation, a structure, infrastructure, property, equipment or service, that if adversely affected during a hazard event may result in severe consequences to public health and safety or interrupt essential services and operations for the community at any time before, during and after the hazard event.

A critical facility is classified by the following categories: (1) Essential Services Facilities: (2) At-Risk Populations Facilities, and (3) Hazardous Materials Facilities.

Table D-2 lists critical facilities and other District assets identified by the District Planning Team as important to protect in the event of a disaster. GMCSD’s physical assets, valued at over $1.8 million, consist of structures and infrastructure to support the District’s operations.

Table D-2 GMCSD Critical Facilities and Infrastructure, and Other District Assets Name of Asset Replacement Value Which Hazards Pose Risk Booster #3 Pump House Addition $44,727 Flood, landslide, high wind, fire Booster Pumps #1-#7 $557,767 Flood, landslide, high wind, fire

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Plumas County GMCSD Annex D-6
Local Hazard Mitigation Plan Update
January 2026
Name of Asset Replacement Value Which Hazards Pose Risk Emergency Standby Generator House and
Pump House (2)
$237,534 Long term power outage,
Landslide, wind, fire
Water tanks (2) $689,051 Earthquake, Landslide, high
wind, fire, drought
Well 17 and Well 29A $80,804 Drought, fire
Well 33 and 37 $124,919 Drought, fire
Dosing Station $85,991 Landslide, high wind, fire
Total $1,820,793
Source: GMCSD
Note: In addition to the above, there are over 13 miles of underground pipes of varying size and value that are at risk.

Community Lifelines
Assessing the vulnerability of the GMCSD to natural hazards and disasters also involves reviewing and inventorying the community lifelines in place that could be affected. It is important to include these items in hazard discussions as the continuous operation of critical government and business functions is essential to human health and safety, property protection, and economic security. The importance of community lifelines is discussed below:
➢ Lifelines are the most fundamental services in the community that, when stabilized, enable all other aspects of society to function.
➢ FEMA has developed a method for objectives-based response that prioritizes the rapid stabilization of Community Lifelines after a disaster.
➢ The integrated network of assets, services, and capabilities that provide lifeline services are used dayto-day to support the recurring needs of the community and enable all other aspects of society to function.
➢ When disrupted, decisive intervention (e.g., rapid re-establishment or employment of contingency response solutions) is required to stabilize the incident.

Community lifelines, as defined by FEMA, include the following:
➢ Safety and Security – Law Enforcement/Security, Fire Service, Search and Rescue, Government Service, Community Safety
➢ Food, Hydration, Shelter – Food, Water, Shelter, Agriculture ➢ Health and Medical – Medical Care, Public Health, Patient Movement, Medical Supply Chain, Fatality Management
➢ Energy – Power Grid, Fuel
➢ Communications – Infrastructure, Responder Communications, Alerts Warnings and Messages, Finance, 911 and Dispatch
➢ Transportation – Highway/Roadway/Motor Vehicle, Mass Transit, Railway, Aviation, Maritime ➢ Hazardous Material – Facilities, HAZMAT, Pollutants, Contaminants ➢ Water Systems – Potable Water Infrastructure, Wastewater Management

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Plumas County GMCSD Annex D-7
Local Hazard Mitigation Plan Update
January 2026
It should be noted that these community lifelines are all in place and functional as part of regular government operations in the Plumas County Planning Area serving as a partnership between the city, local special districts and agencies, and Plumas County. Due to its more rural nature, there is an interplay in community lifelines between all jurisdictions in the County. Most all of the District’s community lifelines overlap with the Planning Area’s. It should also be noted that these lifelines collectively include many of the critical facilities and infrastructure assets inventoried for this LHMP, including those assets owned by the District. As such, specific information on these community lifelines in the District and how they may be affected by a hazard event or disaster are discussed in the Base Plan.

Natural, Historic, and Cultural Resources
Assessing the vulnerability of the GMCSD to natural hazards and disasters also involves inventorying the natural, historic, and cultural assets of the area. This step is important for the following reasons:
➢ Environmental and natural resources add to a community’s identity and quality of life. They also help the local economy through agriculture, tourism, and recreation. They support ecosystem services, such as clean air and water.
➢ Conserving the environment may help people mitigate risk. It can also protect sensitive habitats, develop parks and trails, and build the economy.
➢ The community may decide that these types of resources warrant a greater degree of protection due to their unique and irreplaceable nature and contribution to the overall economy. ➢ If these resources are impacted by a disaster, knowing so ahead of time allows for more prudent care in the immediate aftermath, when the potential for additional impacts are higher. ➢ The rules for reconstruction, restoration, rehabilitation, and/or replacement are often different for these types of designated resources.
➢ Natural resources can have beneficial functions that reduce the impacts of natural hazards, such as wetlands and riparian habitat, which help absorb and attenuate floodwaters.

Natural Resources
GMCSD has a variety of natural resources of value to the District. These natural resources parallel that of Plumas County as a whole. Information can be found in Section 4.2.1 of the Base Plan.

Historic and Cultural Resources
GMCSD has a variety of historic and cultural resources of value to the District. These historic and cultural resources parallel that of Plumas County as a whole. Information can be found in Section 4.2.1 of the Base Plan.

Economic Assets and Community Activities of Value
Assessing the vulnerability of the GMCSD to natural hazards and disasters also involves inventorying the economic assets and community activities of value in the District.

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Plumas County GMCSD Annex D-8
Local Hazard Mitigation Plan Update
January 2026
Economic Assets
After a disaster, economic resiliency is one of the major drivers of a speedy recovery. Each community has specific economic drivers. Economic assets for the County were discussed in Section 4.2.1 of the Base Plan and are assumed to be the same or similar for the District. In addition, the District’s summer resort business, which includes the hotel, rental units, and a golf course, contributes to the economic viability of the District.

Community Activities of Value
Inventorying economic assets in the District and their vulnerability to natural hazards and disasters also involves inventorying activities that have value to the community. This includes activities that are important to a community, like long-standing traditions such as a festival or fair or other activities that bring money into the communities such as sports tournaments and other recreational activities. Community Activities of Value for the County were discussed in Section 4.2.1 of the Base Plan and are assumed to be the same or similar for the District.

Growth and Development Trends
As part of the planning process, the District looked at changes in growth and development, both current and future, and examined these changes in the context of hazard-prone areas, and how the changes in growth and development affect loss estimates and vulnerability over time. This inventory section details future development/redevelopment projects that are likely to occur over the next five years covered by this 2026 LHMP. For Districts, this generally includes the following:
➢ Construction/development projects related to adding new District facilities, infrastructure, land acquisition, etc.
➢ Plans for expansion or build out of the District’s service area, including new service hookups, and other District functions related to where the District will be expanding services.

Population Trends and Projections
Future growth in the District for 2026 and over next 5 years is expected to stay at about 2%, with between 1 to 4 new homes built annually. As of 2025, with this estimated rate of growth, the District does not expect to need to add more staff or service providers. If growth exceeds expectations, a review of staff numbers will be needed to ensure full service capabilities.

Future Development Areas
It is important to review future development plans for the District. Future development should be sited in areas that are away from known hazard risks. If this is not possible, mitigation should be done to ensure that future development is protected against future hazards. The District has a slow growth rate, and development is occurring at sporadic areas of the District. As described above, over the next five years, the District will add between 1-4 new residences annually that will require water and wastewater infrastructure and will be served by the GMCSD.

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Plumas County GMCSD Annex D-9
Local Hazard Mitigation Plan Update
January 2026
In addition, while the existing domestic water infrastructure is capable of meeting current peak community demands, the GMCSD understands that the domestic water infrastructure will need to be increased to meet requirements at full buildout. The CSD maintains a professionally engineered "trigger point" study that allows the District to keep capacity ahead of demand. The District is currently in the process of developing one new well. There are 5 active wells with plans to have a sixth well online by the year 2028 Longer term plans include installing a new higher elevation water tank in the district to increase overall storage capacity, provide for additional gravity flow connections, and to increase flow rates for district fire hydrants. The CSD also has room in their existing tank farm to eventually install another large capacity storage tank to support future growth.

D.4.2. Hazard Identification
The GMCSD identified the hazards that affect the District and summarized their location, extent, likelihood of future occurrence, potential magnitude, and significance (or priority of a hazard) specific to the District.

Note: Those hazards identified as a high or medium significance in Table D-3 are considered priority hazards for mitigation planning. Those hazards that occur infrequently or have little or no impact in the District were determined to be of low significance and not considered a priority hazard to the District.

Significance was determined based on the hazard profile, focusing on key criteria such as frequency, extent, and resulting damage, including deaths/injuries and property, natural and cultural resources, and economic damage. The ability of a jurisdiction to reduce losses through implementation of existing and new mitigation measures was also considered as to the significance and priority of a hazard. This assessment was used to prioritize those hazards of greatest significance, enabling the District to focus resources where they are most needed.

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Plumas County GMCSD Annex D-10
Local Hazard Mitigation Plan Update
January 2026
Table D-3 GMCSD—Hazard Identification Assessment
Hazard
Geographic
Extent
Probability of
Future
Occurrences
Magnitude/
Severity Significance
Climate
Change
Influence
Ag Hazard: Severe Weather /
Insects/Pests
Extensive Highly Likely Limited Low Medium
Climate Change Extensive Likely Limited Low --
Dam Failure Limited Unlikely Negligible Low Medium
Drought & Water Shortage (w/tree
mortality)
Extensive Likely Critical High High
Earthquake Extensive Occasional Limited Medium Low
Flood: 1%/0.2% annual chance
(w/levee failure)
Limited Unlikely Negligible Low Low
Flood: Localized Stormwater Extensive Highly Likely Critical High Medium Haz Mat Transportation Limited Likely Critical Low Low
Landslide, Mudslide, and Debris Flow Extensive Highly Likely Critical High High Severe Weather: Extreme Cold,
Freeze, and Snow (w/avalanche)
Extensive Highly Likely Critical High Medium
Severe Weather: Extreme Heat Limited Likely Limited Medium High Severe Weather: Heavy Rains and
Storms
Extensive Highly Likely Critical High Medium
Severe Weather: High Winds and
Tornadoes
Significant Likely Critical Medium Low
Volcano Limited Unlikely Catastrophic Low Low
Wildfire (w/smoke and air quality) Extensive Highly Likely Catastrophic High High Geographic Extent
Limited: Less than 10% of planning
area
Significant: 10-50% of planning area
Extensive: 50-100% of planning area
Likelihood of Future Occurrences
Highly Likely: Near 100% chance of
occurrence in next year, or happens
every year.

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

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

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

Magnitude/Severity
Catastrophic: More than 50 percent of property severely damaged; shutdown of facilities for more than 30 days; and/or multiple deaths Critical: 25-50 percent of property severely damaged; shutdown of facilities for at least two weeks; and/or injuries and/or illnesses result in permanent disability
Limited: 10-25 percent of property severely damaged; shutdown of facilities for more than a week; and/or injuries/illnesses treatable do not result in permanent disability
Negligible: Less than 10 percent of property severely damaged, shutdown of facilities and services for less than 24 hours; and/or injuries/illnesses treatable with first aid
Significance
Low: Minimal potential impact
Medium: Moderate potential impact
High: Widespread potential impact
Climate Change Influence
Low: Minimal potential impact
Medium: Moderate potential impact
High: Widespread potential impact

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Plumas County GMCSD Annex D-11
Local Hazard Mitigation Plan Update
January 2026
D.4.3. Hazard Profiles and Vulnerability to Specific Hazards This section includes the hazard profiles and vulnerability assessment for hazards ranked of medium or high significance specific to the GMCSD (as identified in the Significance column of Table D-3). This section focuses on where and how the District is affected by their priority hazards. Chapter 4 of the Base Plan provides more detailed information about these hazards and their impacts on the Plumas County Planning Area. Methodologies for evaluating vulnerabilities and calculating loss estimates are the same as those described in Section 4.2 of the Base Plan.

Hazard Profiles and Vulnerability Assessment
Each hazard is profiled in the following format:
➢ Hazard Profile – A hazard profile is included for each hazard. This includes information on:
✓ Hazard Overview – A general discussion of the hazard and related issues is detailed here. ✓ Location and Extent – Location is the geographic area within the District that is affected by the hazard. Extent is the expected range of intensity for each hazard. These are discussed in specific detail for mapped hazards, and in more general detail for those hazards that do not have discrete mapped hazard areas.
✓ Past Occurrences – Past occurrences are discussed for each hazard. A discussion of disaster declarations is included in each hazard section. NCDC events are also discussed. Other past occurrences data specific to the District follow the disaster declarations and NCDC events for each hazard.
✓ Climate Change – This section contains the effects of climate change (as applicable). The possible influence of climate change on the hazard is discussed.

After the hazard profile, a vulnerability assessment is presented. As part of the vulnerability assessment, an estimate of the vulnerability of the District to each identified hazard, in addition to the estimate of risk of future occurrence, is provided in each of the hazard-specific sections. Vulnerability is measured in general, qualitative terms and is a summary of the potential impact based on past occurrences, spatial extent, and damage and casualty potential. It is categorized into the following classifications:
➢ Extremely Low—The occurrence and potential cost of damage to life and property is very minimal to nonexistent.
➢ Low—Minimal potential impact. The occurrence and potential cost of damage to life and property is minimal.
➢ Medium—Moderate potential impact. This ranking carries a moderate threat level to the general population and/or built environment. Here the potential damage is more isolated and less costly than a more widespread disaster.
➢ High—Widespread potential impact. This ranking carries a high threat to the general population and/or built environment. The potential for damage is widespread. Hazards in this category may have occurred in the past.
➢ Extremely High—Very widespread with catastrophic impact.

After this classification, a general discussion of hazard vulnerabilities occurs. This is done in the following format:

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Plumas County GMCSD Annex D-12
Local Hazard Mitigation Plan Update
January 2026
➢ Vulnerability Overview – A general discussion of the hazard vulnerability and related issues is detailed here.
➢ Local Concerns – This includes District provided information on how the District is uniquely affected by or vulnerable to each hazard.
➢ Assets at Risk – A discussion of the assets at risk follows, presented in the same order as in Section D.4.1 above, with a few exceptions. This includes sections on: People and Populations; Structures and Critical Facilities and Infrastructure; and Natural, Historic, and Cultural Resources. These are discussed in specific terms for mapped hazards, and in more general terms for those hazards that are unmapped. Sections on Community Lifelines and Economic Assets and Community Activities of Value are not included in the Sections below, as they are common to all jurisdictions and are fully covered in Section D.4.1 above and Chapter 4 of the Base Plan.
➢ Impacts – A discussion on hazard impacts follows. Impacts describe how each hazard can affect the District, its assets, and the ability to provide continued and reliable services. The type and severity of impacts reflect both the potential magnitude of the hazard and the vulnerability of the asset. ➢ Future Conditions/Future Development – A discussion of how future conditions and future development will affect or influence each hazard over time is also included. This considers both new District assets and improvements as well as any changes in service area.

Power Interruption/Power Failure: A Common Vulnerability of all Hazards An impact of almost all hazards evaluated as part of this LHMP Update relates to power shortage and/or power failures. The US power grid crisscrosses the country, bringing electricity to homes, offices, factories, warehouses, farms, traffic lights and even campgrounds. According to statistics gathered by the U.S.

Department of Energy, major blackouts are on the upswing. Incredibly, over the past two decades, blackouts impacting at least 50,000 customers have increased 124 percent. The electric power industry does not have a universal agreement for classifying disruptions. Nevertheless, it is important to recognize that different types of outages are possible so that plans may be made to handle them effectively. In addition to blackouts, brownouts can occur. A brownout is an intentional or unintentional drop in voltage in an electrical power supply system. Intentional brownouts are used for load reduction in an emergency.

Electric power disruptions can be generally grouped into two categories: intentional and unintentional.

More information on types of power disruptions can be found in Section 4.3 of the Base Plan.

Public Safety Power Shutoff (PSPS)
An intentional disruption type of power shortage/failure event has been recently implemented in California as a result of wildfires starting as a result of downed power lines or electrical equipment. This was the case for the Camp Fire in 2018. As a result, California’s three largest energy companies (including PG&E), at the direction of the California Public Utilities Commission (CPUC), are preparing all Californians for the threat of wildfires and power outages during times of extreme (fire) weather. To help protect customers and communities during extreme fire weather events, electric power may be shut off for public safety in an effort to proactively prevent wildfire. This is called a PSPS. More information on PSPS criteria can be found in Section 4.3 of the Base Plan.

In addition to PSPSs, to help prevent wildfires, electric utilities have begun to evolve safety efforts. This includes installing safety settings on powerlines in and around high fire-risk areas. These are known as Enhanced Powerline Safety Settings (EPSS), and they help prevent falling tree branches, animals and other

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Plumas County GMCSD Annex D-13
Local Hazard Mitigation Plan Update
January 2026
hazards from causing a wildfire. By stopping ignitions, it helps prevent wildfires from starting and spreading. According to PG&E, if ignitions occur, the size of fires can be much smaller due to EPSS. In 2022, there was a 99% decrease in acres impacted by ignitions (as measured by fire size from electric distribution equipment (compared to the 2018-2020 average). This decrease occurred despite dry conditions.

Local Concerns
The District has not been affected by power outage events or PSPS in the past. The District has backup generators to help critical infrastructure and Services continue when outside source power outages occur.

The primary concern is the dollars needed to purchase adequate fuel, and the access/availability to adequate fuel, to keep the backup generators functioning to ensure system will supply water to community.

Drought & Water Shortage (w/tree mortality)
Likelihood of Future Occurrence–Likely
Vulnerability–High
Hazard Profile
Drought and water shortage are complex issues involving many factors—it occurs when a normal amount of precipitation and snow is not available to satisfy an area’s usual water-consuming activities. Drought can often be defined regionally based on its effects. Drought is different than many of the other natural hazards in that it is not a distinct event and usually has a slow onset. Drought can severely impact a region both physically and economically. Drought affects different sectors in different ways and with varying intensities. Adequate water supply is the most significant issue and is critical for agriculture, manufacturing, tourism, recreation, and commercial and domestic use. Drought has also affected tree mortality in the area in the past. As the population in the area continues to grow, so will the demand for water.

Tree Mortality and Drought
One of the secondary hazards of drought in the Plumas County Planning Area, that can also affect GMCSD, is the increased risk to trees from beetle kill and other insects, pathogens and parasites, and other tree mortality and die back issues. Drought weakens trees and makes them more susceptible to insect infestation and other pathogens. Insects, such as bark beetles and others, frequently attack trees weakened by drought, disease, injuries, or other factors that may stress the tree. These insects and other pathogens can contribute to the decline and eventual death of trees throughout the District. The tree mortality and dieback problems are a high priority because of the issue of hazardous trees and an increased wildfire hazard. In addition to an increase in wildfire fuels, hazardous trees can fall onto structures causing damage and a result in a reduction on the tree canopy within the District that provides relief during extreme heat days.

Location and Extent
Drought and water shortage are regional phenomenon. The whole of the District and County is at risk. The US Drought Monitor categorizes drought conditions with the following scale:

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Plumas County GMCSD Annex D-14
Local Hazard Mitigation Plan Update
January 2026
➢ None
➢ D0 – Abnormally dry
➢ D1 – Moderate Drought
➢ D2 – Severe Drought
➢ D3 – Extreme Drought
➢ D4 – Exceptional Drought
Drought has a slow speed of onset and a variable duration. Drought can last for a short period of time (which does not usually affect water shortages) or for longer periods (which may challenge water supplies).

Should a drought last for a long period of time, water shortage becomes a larger issue.

The Plumas County Planning Area, including the District, has been in and out of drought since 2014. Over the last six years since the 2019 LHMP, drought conditions have ranged from none to exceptional. Drought conditions are expected to continue to be cyclical in nature depending on the year. Current drought conditions in the District are shown in Section 4.3.9 of the Base Plan.

Past Occurrences
Disaster Declaration History
There have been 2 state and 1 federal disaster declarations for Plumas County. This can be seen in Table D-4. Additionally, there have been 16 USDA Secretarial Disaster Declarations from drought in the County since 2012.

Table D-4 Plumas County –State and Federal Drought Disaster Declarations 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Drought 2 1976, 2015 1 1977
Source: Cal OES, FEMA
NCDC Events
There have been 2 NCDC drought events in Plumas County since 1993. These most likely had some impact on the District.

GMCSD Events
Based on historical information, the occurrence of drought in California, including the GMCSD, is cyclical, driven by weather patterns. Section 4.3.9 of the Base Plan notes that five droughts have occurred in the past 86 years that likely affected the District. Drought has occurred in the past and will occur in the future.

There have been no past drought events that directly affected the District’s services. The only related impact was a State Mandated Water Usage and Limitations.

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Plumas County GMCSD Annex D-15
Local Hazard Mitigation Plan Update
January 2026
Climate Change and Drought and Water Shortage
It is likely that climate change will increase the chance of future occurrence as well as future impacts associated with drought and water shortage. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Climate scientists studying California find that drought conditions are likely to become more frequent and persistent over the 21st century due to climate change. The experiences of California during recent years underscore the need to examine more closely the state’s water storage, distribution, management, conservation, and use policies. The 2021 CAS (as well as the 2024 Draft CAS) stresses the need for public policy development addressing long term climate change impacts on water supplies. The CAS notes that climate change is likely to significantly diminish California’s future water supply, stating that: California must change its water management and uses because climate change will likely create greater competition for limited water supplies needed by the environment, agriculture, and cities.

A 2018 report from the Public Policy Institute of California noted that thousands of Californians – mostly in rural, small, disadvantaged communities – already face acute water scarcity, contaminated groundwater, or complete water loss. Climate change would make these effects worse.

Cal Adapt scenarios for modeled future drought scenarios were shown in Section 4.3.9 of the Base Plan.

Vulnerability to Drought and Water Shortage
Based on historical information, the occurrence of drought and water shortage in California, including the District, is cyclical, driven by weather patterns. Drought has occurred in the past and will occur in the future. Periods of actual drought with adverse impacts can vary in duration, and the period between droughts can be extended. Although an area may be under an extended dry period, determining when it becomes a drought is based on impacts to individual water users. The vulnerability of the GMCSD to drought may vary and include reduction in water supply, turf losses, impacts to natural resources, and an increase in dry fuels and tree dieback.

The whole of the District is at some measure of vulnerability to drought and water shortage. An assessment of a community’s vulnerability to drought and water shortage begins with an understanding of local exposure to drought. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

Local Concerns
The District has specific concerns and unique vulnerabilities regarding this hazard. These concerns form a portion of the basis for the mitigation strategy and mitigation actions that seek to reduce risk and vulnerability to this hazard.

The GMCSD provides the district with water from deep fractured granite aquifers. The district's domestic water system includes three producing wells, two 140,000-gallon water storage tanks, and a distribution system including both gravity fed and pressurized connection to District customers. The quality of the water is excellent and requires no specialized treatment. The CSD constantly monitors water quality in

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Plumas County GMCSD Annex D-16
Local Hazard Mitigation Plan Update
January 2026
accordance with state regulations and provides notification to all customers on the rare occasion that tests for any contaminants exceed state defined levels.

GMCSD staff is very experienced with tracking water production and managing pumping to allow the wells to recharge and maintain natural hydrologic functions. The Nakoma Resort is the CSD's largest customer for domestic water, however Nakoma maintains its own private wells for golf course irrigation.

The GMCSD supports the California Water Board's position that efficient water use is the most costeffective way to achieve long term conservation goals, as well as to provide for water supply reliability.

GMCSD water district depends on ground/deep well water for supply of potable water to community. There are no alternatives for water supply to community. In the event of a fire, water usage for hydrants vs community may be an issue, as seen in Gold Complex Fire of 2024.

Assets at Risk
Assets at risk from this hazard include people and populations; structures and critical facilities and infrastructure; and natural, historic, and cultural resources. These are discussed in the following sections.

People and Populations
The people and populations (both staff and those served by the District) of the District are not directly affected by general drought conditions; although, their turfed areas, trees, and other water dependent resources can all be affected. In extreme drought conditions, however, residents and other populations within the District may be vulnerable to drought and water shortage issues. Water quality can be impacted causing health problems, especially to vulnerable populations where access to clean water supplies can be more challenging. Water shortages can have an effect on all of the populations in the District, but often have a greater effect on the unhoused and other vulnerable populations that may be unable to access and afford clean drinking water during shortages. During periods of drought as the costs of water usage may increase, those who are economically disadvantaged may be unable to afford the increased costs of potable water.

Structures and Critical Facilities and Infrastructure
Most District structures, critical facilities, and infrastructure have a limited vulnerability to drought and water shortage. Should drought conditions be severe enough to cause water shortage reliability issues, some facilities and infrastructure may be affected. Water and wastewater systems (like those of the District) may be impacted during times of reduced water supply and need to employ contingencies to remain functional and fully operational. Other water dependent systems may also be adversely affected. Further, the secondary hazard of drought (increased potential for spread of urban fires and wildfire) can pose a significant risk to District facilities. Drought can also stress trees, causing die off. These trees may fall on critical infrastructure adjacent to them and impact power lines and other utilities.

As shown in Table D-2, Well 17, 29A, 33, and 37 are at risk to drought.

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Plumas County GMCSD Annex D-17
Local Hazard Mitigation Plan Update
January 2026
Natural, Historic, and Cultural Resources
Drought and water shortage can have a significant impact on natural resources. Water levels in reservoirs and lakes may be reduced and a loss of wetlands and marsh areas may occur. Severe drought conditions can contribute to an increase in erosion of soils and lead to poor soil quality. Further, all of the trees and the community golf course in the District are at risk to drought impacts and a reduction in water supply.

These trees provide a wealth of social and environmental benefits to District residents and visitors, from shade and beauty to air quality, carbon reduction and stormwater management. Drought can devastate crops and dry out pastures, dry out forests and critical habitat areas, and reduce food and water available for wildlife and livestock. Additionally, drought conditions can also cause soil to compact and not absorb water well, potentially making an area more susceptible to flooding. It is unlikely that drought and water shortage would have a significant impact on historic and cultural resources in the District.

Impacts from Drought and Water Shortage
The vulnerability of the District to drought is District-wide, but impacts may vary and include reduction in water supply and an increase in dry fuels. The potential for a reduction in water supply during drought conditions generally leads to both mandated and voluntary conservations measures during extended droughts. During these times, the costs of water can also increase. Also of concern, the increased dry fuels, fuel loads, and tree mortality events associated with drought conditions can result in an increased fire danger. In areas of extremely dry fuels, the intensity and speed of fires can be significant. Water supply and flows for fire suppression can also be an issue during extended droughts. Drought can also lead to turf losses and cause tree die off within the District.

Other qualitative impacts associated with drought in the District are those related to water intensive activities such as municipal usage, tourism, and recreation use. With more precipitation likely falling as rain instead of snow in the Sierra’s, and warmer temperatures causing decreased snowfall to melt faster and earlier, water supply is likely to become more unreliable. In addition, drought and water shortage is predicted to become more common. This means less water available for use over the long run, and additional challenges for water supply reliability, especially during periods of extended drought. This is however less of a concern due to the access to groundwater wells that the District uses.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile discussion above), changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. These are discussed below.

Future Conditions/Future Development
This section provides a discussion of how future conditions will influence or affect the hazard over time and also discusses future development relative to each hazard.

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Plumas County GMCSD Annex D-18
Local Hazard Mitigation Plan Update
January 2026
Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the GMCSD include the following:
➢ Climate change is likely to exacerbate future drought conditions and associated impacts and vulnerability of the District to drought and water shortage. ➢ Population projections for the area served by the District show the population to be slowly increasing with an additional 1-4 residences added annually. This could cause additional impacts and increase the vulnerability of the District to drought and water shortage over time. The District may also add staff, but this number would be small. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ It is unknown how changes in land use and development will affect drought and water shortage in the District’s Service Area. With limited growth and development occurring in the District, estimated at 1-4 new residences annually, current growth predictions are unlikely to increase or decrease the vulnerability of the District to drought and water shortage. The District conducts water supply planning to ensure a continued water supply to address future drought conditions.

Future Development
While the existing domestic water infrastructure is capable of meeting current peak community demands, the GMCSD understands that the domestic water infrastructure will need to be increased to meet requirements at full buildout. The CSD maintains a professionally engineered "trigger point" study that allows the District to keep capacity ahead of demand. The District is currently in the process of developing one new well. There are 5 active wells with plans to have a sixth well online by the year 2028. Longer term plans include installing a new higher elevation water tank in the district to increase overall storage capacity, provide for additional gravity flow connections, and to increase flow rates for district fire hydrants. The CSD also has room in their existing tank farm to eventually install another large capacity storage tank to support future growth. However, population growth in the District will add additional pressure to the District as a water company during periods of drought and water shortage.

Earthquake
Likelihood of Future Occurrence–Occasional (minor)/ Unlikely (major) Vulnerability–Extremely High
Hazard Profile
An earthquake is caused by a sudden slip on a fault. Stresses in the earth’s outer layer push the sides of the fault together. Stress builds up, and the rocks slip suddenly, releasing energy in waves that travel through the earth’s crust and cause the shaking that is felt during an earthquake. Earthquakes can cause structural damage, injury, and loss of life, as well as damage to infrastructure networks, such as water, power, gas, communication, and transportation. Earthquakes may also cause collateral emergencies including dam and levee failures, seiches, hazmat incidents, fires, avalanches, and landslides. The degree of damage depends on many interrelated factors. Among these are: the magnitude, focal depth, distance from the causative

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Plumas County GMCSD Annex D-19
Local Hazard Mitigation Plan Update
January 2026
fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction.

Location and Extent
Since earthquakes are regional events, the whole of the District is at risk to earthquake. The GMCSD, Plumas County, and surrounding areas have some level of risk from seismic and geologic hazards. Faults in and around the District are shown in Section 4.3.10 of the Base Plan. These include the Almanor Fault, Butt Creek Fault Zone, the Mohawk Valley Fault, and others that traverse the County. The Indian Valley Fault is also considered an active fault located within the County. A significant seismic event on any of these major faults could cause damage in the GMCSD.

The amount of energy released during an earthquake is usually expressed as a magnitude and is measured directly from the earthquake as recorded on seismographs. An earthquake’s magnitude is expressed in whole numbers and decimals (e.g., 6.8). Seismologists have developed several magnitude scales, as discussed in Section 4.3.10 of the Base Plan.

Another measure of earthquake severity is intensity. Intensity is an expression of the amount of shaking at any given location on the ground surface. Seismic shaking is typically the greatest cause of losses to structures during earthquakes. The District is located in an area where earthquakes of some magnitude occur. Seismic shaking maps for the area in Section 4.3.10 of the Base Plan show Plumas County and the District fall within a low to moderate shake risk.

Past Occurrences
Disaster Declaration History
There has been no state or federal disaster declarations in Plumas County from earthquake.

NCDC Events
The NCDC does not track earthquake events.

GMCSD Events
As shown in the Base Plan, no disaster declarations have occurred in the County due to earthquake. The HMPC noted no past occurrences of earthquakes that affected the District in any meaningful way.

Climate Change and Earthquake
Climate change is unlikely to increase earthquake frequency or strength. More information on future impacts can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

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Plumas County GMCSD Annex D-20
Local Hazard Mitigation Plan Update
January 2026
Vulnerability to Earthquake
The combination of plate tectonics and associated California coastal mountain range building geology generates earthquakes as a result of the periodic release of tectonic stresses Earthquake vulnerability is primarily based on population and the built environment. More urban areas in high seismic hazard zones are the most vulnerable, while uninhabited areas are less vulnerable. The primary impacts of concern are life safety and property damage. Although several faults are in and near the Plumas County Planning Area, seismic hazard mapping indicates that the District has low to moderate seismic hazard potential. There is the potential for the District and Plumas County Planning Area to be subject to some level of moderate seismic shaking. Some degree of structural damage due to stronger seismic shaking could be expected.

Earthquake shaking can also cause liquefaction to occur. Areas with loose soil and high water tables are at risk from liquefaction. There are limited areas in and near the District prone to liquefaction.

More information on the vulnerability of the Plumas County Planning Area, including all participating jurisdictions, to earthquake shaking events can be seen in the Hazus scenarios developed for this LHMP (Great Valley Fault 6.53, Hat Creek/McArthur/Mayfield 7.29, Honey Lake 7.03, Warm Springs Valley

6.92). More information on the Hazus scenarios and how the Plumas County Planning Area is affected is included in Section 4.3.10 of the Base Plan.

The whole of the District is at some measure of vulnerability to earthquake. An assessment of a community’s vulnerability to earthquakes begins with an understanding of local exposure to earthquakes.

This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

Much of the District’s water and wastewater infrastructure is vulnerable to a large earthquake event. The District’s greatest threat from earthquake is damage to its underground pipes, as well as its above ground appurtenances. Should a damaging earthquake occur, this could further impact the ability of the District to provide water and wastewater services in the immediate aftermath of an earthquake event until repairs can be made. A damaging earthquake may also damage infrastructure required for fire fighting for fires that may occur as a result of an earthquake event.

Assets at Risk
Assets at risk from this hazard include people and populations; structures and critical facilities; and natural, historic, and cultural resources. These are discussed in the following sections.

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Plumas County GMCSD Annex D-21
Local Hazard Mitigation Plan Update
January 2026
People and Populations
All people and populations (both District staff and those residing in the District Service Area) are at risk from earthquake shaking and associated hazards. The greatest risk to people and populations from earthquake is death and injury. More information on people and populations at risk to earthquake shaking events can be seen in the Hazus scenarios developed for this LHMP. More information on the Hazus scenarios and how the County and District may be affected is included in Section 4.3.10 of the Base Plan.

Structures and Critical Facilities and Infrastructure
All structures and critical facilities and infrastructure in the District are vulnerable to earthquakes, depending on the severity and location of the event. The Hazus scenarios conducted for the entire Plumas County Planning Area show how structures and critical facilities and infrastructure may be affected. The 2 water tanks and the 13 miles of underground pipes are especially vulnerable as shown in Table D-2.

Should a damaging earthquake occur, this could further impact the ability of the District to provide water and wastewater services in the immediate aftermath of an earthquake event until repairs can be made. A damaging earthquake may also damage infrastructure required for fire fighting for fires that may occur as a result of an earthquake event.

Natural, Historic, and Cultural Resources
The 2023 State Hazard Mitigation Plan noted that environmental problems from earthquakes can be numerous. It is possible for earthquakes to reroute streams, which can change the water quality, possibly damaging habitat and feeding areas. Streams fed by groundwater and/or springs may dry up because of changes in underlying geology. Another threat to the environment from earthquakes is the potential release of hazardous materials. Water supply sources could be contaminated. Historical and cultural resources are at risk, often due to their age and construction types. The Hazus scenarios in Section 4.3.10 of the Base Plan and included below are relatively silent on the vulnerability to natural, historic, and cultural resources, but impacts to these resources could be long lasting.

Impacts from Earthquake
Earthquakes can strike without warning and cause dramatic changes to the landscape of an area that can have devastating impacts on the built environment. The greatest impact is to life safety of the GMCSD staff, residents, and visitors. Other impacts to the District could include damages to infrastructure such as roads, bridges, and dams; damages and loss of services to utilities and critical infrastructure, including those related to gas, power, water, wastewater and communication systems; damages to structures and other development; and possible loss of life and injuries.

Earthquakes can also cause failure of dams, levees, and reservoirs. Facilities and land downslope from dams or water reservoirs might be subject to flooding, if the dams, reservoirs, or other flood control structures fail as a result of an earthquake.

Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;

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Plumas County GMCSD Annex D-22
Local Hazard Mitigation Plan Update
January 2026
➢ Structural and property damage;
➢ Disruption of and damage to public infrastructure, utilities, and services; ➢ Damage to roads/bridges resulting in loss of mobility; ➢ Significant economic impact (jobs, sales, tax revenue) to the community.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the Likelihood of Future Occurrence discussion above), changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. These are discussed below.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the GMCSD include the following:
➢ As discussed in the hazard profile section, climate change is not anticipated to affect this hazard over time.
➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. This could cause additional impacts from a damaging earthquake affecting the District. The District may also add staff, but this number would be small. The District noted that it continues to accommodate additional populations in the District by providing additional services.
➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to increase the vulnerability of the District to earthquake. The District also has plans to add additional infrastructure to their water and wastewater systems as previously described. Additional infrastructure will also be vulnerable to a damaging earthquake event. However, adherence to protective building codes for new development, including critical facilities, will assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, additional development is unlikely to significantly increase the vulnerability of the District to this hazard.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. Although new growth and development would fall in the area affected by earthquake, given the limited chance of major earthquake and the building codes in effect, development in areas prone to earthquakes will continue to occur. The District follows the California Building Code, which mandates construction techniques that minimize seismic hazards. Future development in the District is subject to these building codes and land use planning.

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Plumas County GMCSD Annex D-23
Local Hazard Mitigation Plan Update
January 2026
Flood: Localized Stormwater Flooding
Likelihood of Future Occurrence–Highly Likely
Vulnerability–Medium
Hazard Profile
Flooding occurs in areas other than the FEMA mapped 1% and 0.2% annual chance floodplains. Flooding may be from drainages not studied by FEMA, lack of or inadequate drainage infrastructure, or inadequate maintenance. Localized, stormwater flooding occurs throughout the District and the Plumas County Planning Area, especially during the rainy season from November through April. Prolonged heavy rainfall (including that from atmospheric river events) contributes to a large volume of runoff resulting in high peak flows of moderate duration.

Location and Extent
The GMCSD is subject to localized flooding throughout the District. Flood extents are usually measured in areas affected, velocity of flooding, and depths of flooding. Expected flood depths in the District vary by location. Flood durations in the District tend to be short to medium term, or until either the storm drainage system can catch up or flood waters move downstream. Localized flooding in the District tends to have a shorter speed of onset, especially when antecedent rainfall has soaked the ground and reduced its capacity to absorb additional moisture.

Past Occurrences
Disaster Declaration History
There have been no state or federal disaster declarations specific to localized floods. There would most likely have been localized flood events during the 22 state and 19 federal disaster declarations for flood events, including heavy rains and storms, as shown in the previous 1%/0.2% annual chance flood section.

Some of these may have affected the District.

NCDC Events
The NCDC occurrences of localized flooding are included in the 1% and 0.2% annual chance flood hazard profile where past flood events were noted. These include 15 flood related events for the entire County Planning Area reported since 1993.

GMCSD Events
Localized flooding occurs in areas around the District every year. The District noted an event during April/May of 2025 where heavy rains caused localized flooding that damaged a community leachfield.

Heavy rains caused a failure of one of two community leachfields requiring a complete rebuild. This caused $160,367 in damages. Leachfields were never intended to be the long-term wastewater treatment for the development. Due to low occupancy of community at that time, the District was able to re-route wastewater flows to the other leachfield. If this were to occur when community occupancy is high, the District would

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Plumas County GMCSD Annex D-24
Local Hazard Mitigation Plan Update
January 2026
suffer major losses in having wastewater removed and dumped. Heavy use, compounded by heavy rains and localized flooding, continues to stress the leachfields while the District looks for alternatives.

Climate Change and Localized Flood
It is likely that climate change will increase the chance of future occurrence as well as future impacts from localized floods. Atmospheric river events, occurring in recent years, is thought to be attributed to climate change and reflect storms of greater volume and intensity. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Even if average annual rainfall may decrease slightly, the intensity of individual rainfall events is likely to increase during the 21st century, increasing the likelihood of overwhelming stormwater systems built to historical rainfall and storm averages. This makes localized flooding more likely.

Vulnerability to Localized Flood
Flood vulnerability and their impacts vary by location and severity of any given flood event and will likely only affect certain areas of the District during specific times. Based on the risk assessment, it is evident that floods will continue to have potentially significant impacts to certain areas of the District. However, while flooding can cause significant impacts, depending on the duration and volume of precipitation and the drainage in any given area, many of the floods in the District are minor, localized flood events that are more of a nuisance than a disaster.

Many areas of the District are at some measure of vulnerability to localized flooding. An assessment of a community’s vulnerability to localized flooding begins with an understanding of local exposure to localized flooding. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

Historically, the District has been affected by localized flooding occurring during heavy rain and storm (including atmospheric river) events. Additional development in the District and in the watersheds of these streams affects both the frequency and duration of damaging floods through an increase in stormwater runoff and contributes to localized flooding occurring in areas throughout the District. The lack of or inadequate drainage infrastructure in the District contributes to localized flooding issues. The District is also concerned with rain on snow events, which can cause greater flooding in the District.

Localized flooding could render leachfields useless, clog pipes, and cause vegetation to fall on facilities and impact accessibility to CSD facilities for repair. The District does not track localized flooding areas.

Depending on the location and nature of future storm events, localized flooding will continue to be an issue in the District.

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Plumas County GMCSD Annex D-25
Local Hazard Mitigation Plan Update
January 2026
Assets at Risk
Assets at risk from this hazard include people and populations; structures and critical facilities; and natural, historic, and cultural resources. These are discussed in the following sections.

People and Populations
All District staff and populations served (including vulnerable populations) are traditionally not highly vulnerable to localized flooding, but their structures and contents can be at risk. Localized flooding may also cause transportation issues as roads and lanes are impacted or closed and affect the ability for District staff and residents to travel throughout the District.

Structures and Critical Facilities and Infrastructure
Structures and critical facilities and infrastructure in areas with localized flooding can be affected if floodwaters intrude into the structure. Structures in low lying areas, can be at greater risk. Buildings with older foundations that are prone to water intrusion are also at greater risk. Once water finds its way into a structure, it tends to continue to do so until the path that brings water into a structure is mitigated. Structures can also be damaged by trees that have become uprooted and fall during rain and storm events. Large trees falling onto structures can cause significant damage.

As previously described, the District’s two leachfields are vulnerable to damage from localized flood events.

Natural, Historic, and Cultural Resources
Natural resource assets may have some vulnerabilities to localized flood during major storm events, but can also benefit from floodwaters, often by design. Many open spaces take overflow water and release it into the underlying soils and natural areas. Wetlands areas in the District actually help reduce the risk of flooding, as they can absorb excess rainfall that would have to be drained away from impervious surfaces.

Flooding can provide many benefits to the natural environment, including recharging wetlands and groundwater, increasing fish production, creating wildlife habitat, and rejuvenating soil fertility. These smaller localized flooding events often provide more benefits to the environment in comparison to negative impacts associated with large flood events. Historic and cultural resources may be at some measure of vulnerability if they are located in areas subject to repeated localized flooding.

Impacts from Localized Flood
Primary concerns associated with stormwater flooding include impacts to infrastructure that provide a means of ingress and egress throughout the community. Ground saturation can result in instability, collapse, or other damage to trees, structures, roadways and other critical District water and wastewater infrastructure. Objects can also be buried or destroyed through sediment deposition. Floodwaters can break utility lines and interrupt services to District facilities. Standing water can cause damage to crops, roads, and foundations of District facilities. Other problems connected with flooding and stormwater runoff include erosion, sedimentation, degradation of water quality, losses of environmental resources, and certain health hazards.

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Plumas County GMCSD Annex D-26
Local Hazard Mitigation Plan Update
January 2026
Life safety issues from localized flooding would be more limited. The amount and type of damage or flooding that occurs varies from year to year and from storm to storm, depending on the quantity of precipitation and runoff.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the GMCSD include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over time.
➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to localized flooding. Additional development traditionally leads to additional flooding. The District also has plans to add additional infrastructure to their water and wastewater systems as previously described. Additional infrastructure may also be vulnerable to future flooding events. However, adherence to protective building codes for new development, including critical facilities, will assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, additional development is unlikely to significantly increase the vulnerability of the District to this hazard. In addition, should the District identify viable alternatives to using leachfields for the long term management of wastewater, any associated infrastructure development may actually limit the or decrease the vulnerability of the District to the future effects of localized flooding.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. The risk of stormwater/localized flooding to future development can be minimized by accurate recordkeeping of repetitive localized storm activity. Mitigating the root causes of the localized

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Plumas County GMCSD Annex D-27
Local Hazard Mitigation Plan Update
January 2026
stormwater or choosing not to develop in areas that often are subject to localized flooding will reduce future risks of losses due to stormwater/localized flooding. Future development in the District will add to the drainage issues already faced by the District, unless adequate drainage facilities are installed in new development locations.

Landslide, Mudslide, and Debris Flow
Likelihood of Future Occurrence–Highly Likely
Vulnerability–High
Hazard Profile
Like its earthquake‐generating faults, California’s mountainous terrain is a consequence of dynamic geologic processes in operation as the North American Plate grinds past the Pacific Plate. According to the CGS, a landslide is a general term for a variety of mass-movement processes that generate a down-slope movement of mud, soil, rock, and/or vegetation. Landslides are classified into many different types based on form and type of movement. They range from slow‐moving rotational slumps and earth flows, which can slowly distress structures but are less threatening to personal safety, to fast‐moving rock avalanches and debris flows that are a serious threat to structures and have been responsible for most fatalities during landslide events. For the purposes of this LHMP Update, the term landslide includes mudslides, debris flows, and rockfalls that tend to occur suddenly; as well as hillside erosion, which is a similar process that tends to occur on smaller scales and more gradually but can exacerbate landslide events.

Landslides, debris flows and mudslides are closely related to flooding, as both processes are related to precipitation, runoff, and the saturation of ground by water. In addition, landslides, mud flows, and debris flows can occur on small, steep stream channels and are often mistaken for floods. However, landslide events may be much more destructive than floods because of their higher densities, high debris loads, and high velocities.

Natural conditions that contribute to landslide, mudslides, debris flows, hillside and streambank erosion, include the following:
➢ Degree of slope
➢ Water (heavy rain, river flows, or wave action)
➢ Unconsolidated soil or soft rock and sediments
➢ Lack of vegetation (no stabilizing root structure)
➢ Previous wildfires and other forest disturbances (discussed in the Wildfire section below) ➢ Road building, excavation, and grading
➢ Earthquake
The 2023 California State Hazard Mitigation Plan noted that more than one third of California is mountainous terrain that generally trends parallel to the coast, forming a barrier that captures moisture from offshore storms originating in the Gulf of Alaska and Mexico. Steep topography, weak rocks, heavy winter rains, and occasional earthquakes all lead to slope failures more frequently than would otherwise occur under gravity alone. This is true in the sloped areas that exist in much of the District.

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Plumas County GMCSD Annex D-28
Local Hazard Mitigation Plan Update
January 2026
Location and Extent
Landslides can occur in areas with steep slopes and weak soils. It can also occur in areas where erosion has previously occurred. Both winter storms (precipitation-induced) and earthquake triggered landslides tend to occur in or near places that have experienced previous landslides. However, landslides may also occur in other locations over time. Landslides and debris flows may also occur in fire burn scar areas.

Figure D-3 shows the CGS areas at susceptible to deep-seated landslides. The legend on Figure D-3 shows the susceptibility scale (from 0-X with 0 being the least and X being the most susceptible) that the CGS uses to show the susceptibility of landslides. It is a primarily a combination of slope class and rock strength.

Geographic extents of these classes are shown on Table D-5. According to the 2023 State Hazard Mitigation Plan, the susceptibility classes were further categorized into Very High (susceptibility class X) and High (susceptibility classes VII, VIII, & IX) for exposure analysis. The rest of the classes were not categorized. CGS mapping indicates that portions of the District and surrounding area are at high to very high susceptibility areas for landslides. This can be seen in the darker orange and red colors. The speed of onset of landslide is often short, especially in past landslide areas as well as in post-wildfire burn scar areas, but it can also take years for a slope to fail. Landslide duration is usually short, though digging out and repairing landslide areas can take some time.

Figure D-3 GMCSD – Susceptibility to Deep-Seated Landslides

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Plumas County GMCSD Annex D-29
Local Hazard Mitigation Plan Update
January 2026
Table D-5 GMCSD – Susceptibility to Deep-Seated Landslide Geographical Extents by Class Susceptibility
to DeepSeated
Landslide
Class
Total Acres % of Total
Acres
Improved
Acres
% of Total
Improved
Acres
Unimproved
Acres
% of Total
Unimproved
Acres
0 123 10% 54 13% 69 8%
III 0 0.0% 0 0.0% 0 0.0%
V 441 34% 153 36% 288 33%
VI 0 0.0% 0 0.0% 0 0.0%
VII 150 12% 64 15% 86 10%
VIII 264 20% 58 14% 207 24%
IX 292 23% 80 19% 212 24%
X 26 2% 13 3% 13 1%
Grand Total 1,297 100% 422 100% 875 100%
Source: CGS
Past Occurrences
Disaster Declarations
There have been no disaster declarations associated with just landslides in Plumas County; however, as shown in Table D-6, there have been 9 state and 10 federal disaster declarations for flood (including heavy rains and storms) which included landslides as a component.

Table D-6 Plumas County – Federal and State Disaster Declarations Summary 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Flood (events that
included landslide)
9 1995 (twice), 2006 (twice), 2017
(twice), 2019, 2023 (twice)
10 1995 (twice), 2006 (twice), 2017
(twice), 2019, 2023 (three)
Source: Cal OES, FEMA. Retrieved March 2025.

NCDC Events
The NCDC contains 21 records for landslides or debris flows in Plumas County since 1993. There was one event that affected the District in April/May of 2005 as discussed below.

GMCSD Past Occurrences
The District noted the following event:

April/May 2005 – There was a landslide on a cut bank above District water storage tanks at Lot 188/189 Dream Maker. No deaths or injuries occurred. There was property damage of $93,269, due to significant

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Plumas County GMCSD Annex D-30
Local Hazard Mitigation Plan Update
January 2026
remediation and stabilization. In addition, there were other damages of $46,731 for repairs to tank and water plumbing infrastructure. There were temporary traffic restrictions during repairs. Damage and subsequent repairs required the District to put water use restrictions in place until tanks could be returned to full operational capability.

Climate Change and Landslide and Debris Flows
According to the 2021 CAS (as well as the 2024 Draft CAS), climate change may result in precipitation extremes (i.e., wetter wet periods and drier dry periods). More information on precipitation increases can be found in Section 4.3.4 of the Base Plan. While total average annual rainfall may decrease only slightly, rainfall is predicted to occur in fewer, more intense precipitation events. The combination of a generally drier climate in the future, which will increase the chance of drought and wildfires, and the occasional extreme downpour is likely to cause more mudslides, landslides, and debris flows.

Vulnerability from Landslide
Portions of the District are at some measure of vulnerability to landslide. This is true when atmospheric rivers or heavy rain and storm events occur. Post wildfire areas are also more prone to landslide events.

An assessment of a community’s vulnerability to landslide begins with an understanding of local exposure to landslide. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

District staff noted that Gold Mountain is in an area of mountainous terrain with steep hillsides and canyons.

Depending on ground saturation and levels of precipitation, further ground shifts can be expected in these sloped areas. Future landslides could damage a booster station, well system, or water tank, causing reduction of services to community until repair is completed which could be weeks. Landslides could also make access to the area or equipment limited for a longer time than just repair.

People and Populations
All populations (both District staff and District residents) located within areas of landslide susceptibility, especially in the High to Very High hazard areas (i.e., Classes VII to X) are at some vulnerability to landslide. Most vulnerable are those people working or residing in these landslide potential areas as well as those that might reside or work within the landslide run out areas. People residing in the District service areas as well as District staff may also be cut off from transportation routes if roads and streets providing a

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Plumas County GMCSD Annex D-31
Local Hazard Mitigation Plan Update
January 2026
means of ingress and egress are impacted. Certain vulnerable populations may be at greater risk due to the often sudden onset of a landslide event and include: the unsheltered, those with limited mobility, and those that lack the resources to leave the area.

Structures and Critical Facilities and Infrastructure
Landslides can affect the built environment of the District and those structures and critical facilities located within the High to Very High hazard areas (i.e., Classes VII to X) are especially vulnerable, as are the structures located within the landslide run out areas. The District noted (in Table D-2.) that the Booster #3 Pump House Addition, Booster Pumps #1-#7, Emergency Standby Generator House and Pump House (2), Water tanks (2), and Dosing Station are all at risk to landslide.

Natural, Historic, and Cultural Resources
Landslides can affect natural, historic, and cultural resources that lie in the landslide area, or the landslide run out area. Landslides can destroy large tracts of forest and open space areas, destroy wildlife habitat, and remove productive soils and vegetation from slopes. It can also fill in waterways, impact water quality, and potentially affect flooding potential. Natural resources that fall in the High or Very High susceptibility areas shown on Figure D-3 would be most vulnerable, as well as those in the run-out areas. As shown on the map, this would include a moderate area of the developed area of the District.

Impacts from Landslide
Any type of landslide may result in damages or complete destruction of buildings in their path, as well as deaths and injuries. Landslides can cause road blockages by depositing debris on road surfaces or road damage if the road surface itself slides downhill. Utility lines and pipes are also prone to breakage in slide areas, as are the various infrastructure components that comprise water and wastewater systems and other key critical facilities and infrastructure that provide services in the Plumas County Planning Area Large landslides can collapse into water bodies, causing seiches. Landslides can relocate river channels.

Landslides and debris flows can also impact water quality and the storage capacity of surface water reservoirs used to store potable water.

Landslides, debris flows, and mud flows impacts vary by location and severity of any given event and will likely only affect certain areas of the District susceptible to landslide. Based on the risk assessment, there is potential for significant landslides to occur in the District. Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;
➢ Disruption of and damage to public infrastructure, utilities, and services; ➢ Damage to roads/bridges resulting in loss of mobility; and ➢ Significant economic impact (jobs, sales, tax revenue) to the community.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile above), changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. These are discussed in the Future Conditions/Future Development discussion below.

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Plumas County GMCSD Annex D-32
Local Hazard Mitigation Plan Update
January 2026
Future Conditions/Future Development
This section provides a discussion of how future conditions will influence or affect the hazard over time and also discusses future development relative to each hazard.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the District include the following:
➢ Climate change is likely to exacerbate future landslide, mudslide, and debris flow conditions and associated impacts and vulnerability of the District to landslide. ➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to this hazard. Building that occurs in the VI or higher deep seated landslide classes may increase risk to additional lands. County building codes are in effect to reduce this risk and should be updated as necessary to continue to address future landslide or erosion conditions.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. Additional growth and development within moderate or higher deep-seated landslide susceptibility classesin the District would place additional values at risk to landslide. New District facilities will take landslide into account when siting new facilities.

Severe Weather: Extreme Cold, Freeze, and Snow (w/avalanche) Likelihood of Future Occurrence–Highly Likely
Vulnerability–Medium
Hazard Profile
According to the National Weather Service (NWS) and the Western Regional Climate Center (WRCC), extreme cold often accompanies a winter storm or is left in its wake. Snow can occur during these events.

Excess snow can cause avalanches to occur. Prolonged exposure to cold can cause frostbite or hypothermia and can be life-threatening. Infants and the elderly are some of the most susceptible. Pipes may freeze and burst in homes or buildings that are poorly insulated or without heat. Freezing temperatures can cause

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Plumas County GMCSD Annex D-33
Local Hazard Mitigation Plan Update
January 2026
impacts to utilities and critical facilities and infrastructure as well as cause significant damage to the agricultural industry.

Location and Extent
According to the WRCC, in Plumas County monthly average minimum temperatures from November through April range from the low-20s to upper-40s. Extreme cold and freeze events occur on a regional basis. There is no scale for extreme cold and freeze other than temperatures below 32°F, which can occur with some regularity in the winter months in the District. Extreme cold and freeze have a slow onset and can generally be predicted in advance for the County. Freeze events can last for hours (in a cold overnight), or for days to weeks at a time. Extreme cold can occur in any location of the City. All portions of the District are at risk to extreme cold and freeze.

Snowfall can affect almost all areas of the County and the District. In the elevations of the District, severe snowstorms are some of the most common extreme weather events that occur in the District and Plumas County. There is no scale (i.e. Richter, Enhanced Fujita) to measure the effects of snowfall other than snow depths. Heavy snow has a slow to moderate onset and can generally be predicted in advance for the County.

Snow events can last for hours or for days, and snow can stay on the ground for weeks to months at a time.

Avalanche affects only certain areas of the County and the District. The combination of steep slopes, abundant snow, weather, snowpack, and an impetus to cause movement to create an avalanching episode.

This is rare in the District. Speed of onset of avalanche is short, as is the duration of each event. Most avalanches occur during and shortly after storms between January and March. A scale of avalanche danger has been created for North America. This scale can be seen in Section 4.3.2 of the Base Plan.

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

There were no disasters from snow or from avalanche. Table D-7 shows the dates of the disaster declarations. There have been USDA disaster declarations (2016, twice in 2022, 2023) from freeze since 2012.

Table D-7 Plumas County – Federal and State Disaster Declarations for Freeze 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Freeze 1 2007 0 –
Source: Cal OES, FEMA
NCDC Events
The NCDC data shows 549 extreme cold, freeze, and snow incidents for Plumas County since 1993, some of which likely affected the District.

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Plumas County GMCSD Annex D-34
Local Hazard Mitigation Plan Update
January 2026
GMCSD Events
The District noted that cold, freeze, and snow occur every year, but could recall no events where damages to District facilities occurred.

Climate Change and Extreme Cold, Freeze, and Snow (w/avalanche) According to the 2021 CAS (as well as the 2024 Draft CAS), freezing spells and snow are likely to become less frequent in California as climate temperatures increase; if emissions increase, freezing events could occur only once per decade in large portion of the State by the second half of the 21st century. According to a California Natural Resources Report in 2014, it was determined that while fewer freezing spells would decrease cold related health effects, too few freezes could lead to increased incidence of disease as vectors and pathogens do not die off.

Vulnerability to Extreme Cold, Freeze, and Snow (w/avalanche) Extreme cold and freeze events happen in the District each year. Snow occurs regularly and can contribute to avalanches occurring in sloped areas. Cold, freeze, snow, and avalanche can impact both structures and populations in the Planning Area and in extreme conditions, may affect the ability of the District to operate.

The whole of the District and County Planning Area has some measure of vulnerability to extreme cold, freeze, and snow, including avalanches.

An assessment of a community’s vulnerability to this hazard begins with an understanding of local exposure to District. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

The District noted that employees are its greatest concern. The District is seeking to review, maintain, and expand upon District employee access to all facilities during extreme cold, freeze and snow. The District is also concerned with rain on snow events, which can cause greater flooding in the District.

Power outages can also occur during large storm events impacting facility operations. Should a power outage occur, it is important that the District has backup systems in place to prevent or limit the loss of services to the community.

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Plumas County GMCSD Annex D-35
Local Hazard Mitigation Plan Update
January 2026
People and Populations
All District staff and populations the District serve are at some vulnerability to extreme cold, freeze, and snow. Some employees may face a risk while working outdoors. All populations served by the District are vulnerable to extreme cold and freeze, but this hazard generally affects people spending large amounts of time outside (including District staff). Prolonged exposure to cold can cause frostbite or hypothermia and can be life-threatening. Vulnerable populations to cold and freeze include the unhoused; individuals who exercise or train outdoors; outdoor workers; individuals that lack the resources to afford heat; and the young, old, or medically fragile individuals that are more susceptible to cold related impacts. In addition to vulnerable populations, pets and livestock are at risk to freeze and cold. Snow has an effect on buildings, but its effect on people and populations are minimal. Avalanche can affect populations, including both District staff and the residents of the community. These populations could be at risk to heavy snow resulting in avalanches if they are working or recreating in some of the more landslide prone areas of the District.

Structures and Critical Facilities and Infrastructure
Structures and critical facilities and infrastructure in the District have some measure of risk from extreme cold and freeze. Buildings can be affected directly by freeze, pipes that feed buildings can be damaged during periods of extreme cold and cause water damage and other related impacts to a structure. Structures can also be damaged by downed trees during freeze and winter storm events. Snowfall can occur and can be heavy enough to damage structures. Transportation networks, communications, and utilities infrastructure are the most vulnerable physical assets in the District. Infrastructure such as roads, highways, and bridges can become slippery or blocked by large snow events, causing accidents and road closures.

As shown in Table D-2, booster pumps and wells may be impacted by extreme cold and freeze. There has been no identified past events of these damages occurring. As noted above, during periods of extreme cold, freeze, and snow, District employee access to all facilities can be challenging.

Natural, Historic, and Cultural Resources
Depending on how low the temperatures go and the duration of an extreme cold and freeze event, natural resources in the District may be affected. During periods of freeze, trees in the District may be damaged.

This is especially true if a freeze occurs during a winter storm with winds and precipitation. Other natural resources like wildlife may be at risk during a period of freeze. While it is rare for historic buildings to be affected directly by freeze, damages to pipes that feed historic buildings can be damaged during periods of extreme cold and cause additional impacts to the structures.

Impacts from Severe Weather: Extreme Cold, Freeze, and Snow Extreme cold and freeze can affect critical facilities and infrastructure, down trees, break pipes, and can be a life safety issue. Transportation networks, communications, and utilities infrastructure are often the most vulnerable physical assets in the District. Infrastructure such as roads and utilities are at risk to freezing temperatures and snow, causing operational failures and hazardous road conditions. When extreme cold is coupled with high winds, snows, and freezing storms, power lines may be downed, resulting in power outages and an interruption of utilities and critical services. During periods of extremely low or prolonged cold temperatures, other impacts to the District can include interruption in business and school activities.

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Plumas County GMCSD Annex D-36
Local Hazard Mitigation Plan Update
January 2026
The elderly, the young, and those experiencing medical issues are often more vulnerable to temperature extremes, but anyone can be affected. Exposure to cold temperatures can cause hypothermia and frostbite.

Those exercising or recreating outdoors, outdoor workers, and the unhoused may be at a higher risk.

One of the most significant impacts from snow avalanches are the closure of transportation corridors, which can isolate populations and interrupt commodity flows. Avalanches tend to occur during extended periods of snow when new snow is deposited on the existing snowpack causing stress on the layers beneath and triggering a collapse resulting in an avalanche. Avalanches can also be triggered by severe weather such as high winds and unusually warm weather and even earthquake events. There may be occasions where avalanches contribute to the presence of other hazards, such as flash floods resulting from mountainside erosion. Avalanches might cause erosion on sloped terrain, thereby increasing the likelihood of future landslides. In addition, debris deposited in a river or stream because of avalanches might alter its flow and contribute to flooding later.

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Plumas County GMCSD Annex D-37
Local Hazard Mitigation Plan Update
January 2026
Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. Future development built to code should be able to withstand extreme cold and freeze.

Pipes at risk of freezing should be mitigated by either burying or insulating them from freeze as new facilities are improved or added. Current State of California and Plumas County codes provide such provisions for new construction. New wells and appurtenances should be built inside insulated buildings, reducing the risk of loss of potable water due to frozen pipes and other operational failures.

Severe Weather: Extreme Heat
Likelihood of Future Occurrence–Highly Likely
Vulnerability–Medium
Hazard Profile
According to FEMA, extreme heat is defined as temperatures that hover 10 degrees or more above the average high temperature for the region and lasts for several weeks. Heat kills by taxing the human body beyond its abilities. In extreme heat and high humidity, evaporation is slowed, and the body must work extra hard to maintain a normal temperature.” Most heat disorders occur because the victim has been overexposed to heat or has over-exercised for his or her age and physical condition. Older adults, young children, those who are sick or overweight, and those that work or recreate outdoors are more likely to experience heat exhaustion or succumb to extreme heat.

In addition to the risks faced by citizens of the District, there are risks to the built environment from extreme heat. While extreme heat on its own does not usually affect structures, extreme heat during times of drought can cause wildfire risk to heighten. Extreme heat can lead to interruptions in power, power outages, and when combined with high winds, to Public Safety Power Shutdown (PSPS) events, creating significant issues in the District. Extreme heat can also affect air quality conditions making certain populations more vulnerable to heat related issues.

Location and Extent
Extreme heat events occur on a regional basis. According to the WRCC, in Plumas County, monthly average maximum temperatures in the warmest months (May through October) range from the low-70s to the upper-80s. The District experiences temperatures in excess of 100°F during the summer and fall months. The temperature moves to 105-110°F in rather extreme situations. Extreme heat can occur in any location of the District. Extreme heat occurs throughout the District primarily during the summer months.

The NWS has in place a system to initiate alert procedures (advisories or warnings) when extreme heat is expected to have a significant impact on public safety. The expected severity of the heat determines whether advisories or warnings are issued. The NWS HeatRisk forecast provides a quick view of heat risk potential over the upcoming seven days. The heat risk is portrayed in a numeric (0-4) and color (green/yellow/orange/red/magenta) scale which is similar in approach to the Air Quality Index (AQI) or the UV Index. This can be seen in Section 4.3.3 of the Base Plan.

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Plumas County GMCSD Annex D-38
Local Hazard Mitigation Plan Update
January 2026
Past Occurrences
Disaster Declaration History
There have been no federal or state disaster declarations from extreme heat.

NCDC Events
The NCDC data shows 7 extreme heat incidents for Plumas County since 1993, some of which likely affected the District.

GMCSD Events
The District noted that extreme heat occurs every year, but no damages to District facilities could be recalled. No injuries to District personnel could be recalled.

Climate Change and Extreme Heat
The 2021 CAS (as well as the 2024 Draft CAS), citing a California Energy Commission study, states that “over the past 15 years, heat waves have claimed more lives in California than all other declared disaster events combined.” This study shows that California is getting warmer, leading to an increased frequency, magnitude, and duration of heat waves. These factors may lead to increased mortality from excessive heat.

As temperatures increase, California and Plumas County will face increased risk of death from dehydration, heat stroke, heat exhaustion, heart attack, stroke and respiratory distress caused by extreme heat. According to the 2021 CAS (as well as the 2024 Draft CAS) report and the 2023 State of California Hazard Mitigation Plan, by 2100, hotter temperatures are expected throughout the state, with projected increases of 3-5.5°F (under a lower emissions scenario) to 8-10.5°F (under a higher emissions scenario). These changes could lead to an increase in deaths related to extreme heat in Plumas County.

Vulnerability to Severe Weather: Extreme Heat
Extreme heat is becoming more frequent, intense, longer lasting and geographically widespread. Extreme heat occurs on an annual basis in the County and the District. In recent years, compounded by climate change conditions, summer months continue to get a bit hotter. The whole of the District is at some measure of vulnerability to extreme heat. An assessment of a community’s vulnerability to extreme heat begins with an understanding of local exposure to extreme heat. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

The District supplies water from underground systems and water tanks. During periods of extreme heat (and drought) there is a need to track and identify population growth and usage to ensure adequate potable

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Plumas County GMCSD Annex D-39
Local Hazard Mitigation Plan Update
January 2026
water supply. Action plans include ongoing education and possible regulation on the non-essential use of water. Plans are being reviewed to request water meters on homeowner dedicated irrigation systems to monitor non-essential water usage.

People and Populations
All District staff and the populations served by the District are at some vulnerability to extreme heat. Those District employees that work outdoors or inside facilities without proper cooling systems are likely to be most affected by extreme heat conditions.

Extreme heat can also affect air quality conditions making certain populations more vulnerable to heat related issues. All populations served by the District are vulnerable to extreme heat, but it generally affects people spending large amounts of time outside or without means of cooling indoor structures. During extended periods of high temperatures, extreme heat may overload the demands for electricity to run air conditioners and can present health concerns to individuals. When interruptions in power occur during extreme heat, the risk of heat related illnesses and deaths increase. Extreme heat is a significant concern to vulnerable populations. The unhoused; individuals who exercise or train outdoors; outdoor workers (like District staff); individuals that lack the resources to afford heat; and the young, old, or medically fragile individuals are more susceptible to heat related impacts. In addition to vulnerable populations, pets and livestock are at risk to extreme heat conditions.

Structures and Critical Facilities and Infrastructure
Extreme heat normally does not generally impact structures and critical facilities and Infrastructure, but individuals working in structures may be affected during periods of extended heat, especially in structures that might not be equipped with air conditioning or other means of cooling. The District noted that extreme heat has caused interruptions to power in the past. Also depending on the structure, sensitive contents such as IT and other electronic equipment such as SCADA systems for operational monitoring and control, can be impacted, especially if a power outage occurs.

While no facilities in Table D-2 are at direct risk to extreme heat, wildfires that occur during these times could affect District facilities. Those are discussed in the Wildfire section below.

Natural, Historic, and Cultural Resources
Natural resource assets, including those located in District, may be vulnerable during periods of extreme heat. These include turfed areas; landscapes, trees, wildlife and habitat areas, and wetlands and marsh

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Plumas County GMCSD Annex D-40
Local Hazard Mitigation Plan Update
January 2026
lands. Recently, trees were lost in areas of the District that were weakened by drought and extreme heat.

Extreme heat may also cause drought-like conditions, contributing to other issues. For example, several weeks of extreme heat increases evapotranspiration and reduces moisture content in vegetation, leading to higher wildfire vulnerability in the region for that time period, even if the rest of the season is relatively moist. Historic and cultural resources are not expected to be affected by extreme heat.

Impacts from Severe Weather: Extreme Heat
The District experiences temperatures in excess of 100°F during the summer and fall months. The temperature moves to 105-110°F in rather extreme situations. During these times, drought conditions may worsen, and the District may see an increase in dry fuels contributing to the wildfire hazard. Extreme heat can damage agricultural assets in the District service territory. Also, power outage and PSPS events may occur during these times as well. Health issues are a primary concern with this hazard, especially to vulnerable populations, although economic impacts can also be an issue.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile section above), changes in population patterns, and changes in land use and development. The influencing effects of these factors on this hazard are discussed further in the Future Conditions/Future Development discussion below.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for District include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over time.
➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to this hazard. This limits heat and associated impacts to the District. In addition, adherence to protective building codes for new development will also assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, future losses to new development should be minimal.

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Plumas County GMCSD Annex D-41
Local Hazard Mitigation Plan Update
January 2026
Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. Future development in the District will take extreme heat into account. In the event of grid-tied power outages, a reliable backup power source should be included in development plans.

Additionally, implementing energy efficiency and conservation efforts to reduce stress on electricity systems during heat waves should be considered by the District.

Severe Weather: Heavy Rains and Storms
Likelihood of Future Occurrence–Highly Likely
Vulnerability–Medium
Hazard Profile
Storms in the District occur annually and are generally characterized by heavy rain often accompanied by strong winds and sometimes lightning and hail. Approximately 10 percent of the thunderstorms that occur each year in the United States are classified as severe. A thunderstorm is classified as severe when it contains one or more of the following phenomena: hail that is three-quarters of an inch or greater, winds in excess of 50 knots (57.5 mph), or a tornado. Heavy precipitation in the District falls mainly in the fall, winter, and spring months. It can come normally, or as part of an atmospheric river event. Those events were discussed in Section 4.3.4 of the Base Plan. Wind often accompanies these storms; hail and lightning are rare in the District. Rain coming during times of snow are of particular concern to the District, as even smaller rains can melt snow, causing flooding issues.

Location and Extent
Heavy rains in Plumas County vary by season and location. Plumas County is located in the Northern portion of the Sierra Nevada region and has significant topographic variation, which causes it to experience a more severe and geographically variable winter climate (discussed in more detail in Section 4.3.2 of the Base Plan). In Plumas County the leeward side of the mountains represents the eastern portion (where the District sits) of the County where precipitation typically averages around two inches in the wettest months of the year.

Rains and storms can occur in any location of the District. All portions of the District are at risk to heavy rains and storms. Most of the severe rains occur during the fall, winter, and spring months in the District as discussed below (with problem flooding areas associated with heavy rains and storms discussed in the Flood: Localized Stormwater section). There is no scale by which heavy rains and severe storms are measured. Magnitude of storms is measured often in rainfall and damages. The speed of onset of heavy rains can be short, but accurate weather prediction mechanisms often let the public know of upcoming events. Hail and lightning are rarer in the District and Plumas County. Duration of severe storms in the District can range from minutes to hours to days.

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Plumas County GMCSD Annex D-42
Local Hazard Mitigation Plan Update
January 2026
Past Occurrences
Disaster Declaration History
According to historical hazard data, severe weather, including heavy rains and storms, is an annual occurrence in the District. This contributes to many of the federal disaster declarations related to flooding.

Disaster declarations from flooding, including heavy rains and storms, are shown on Table D-8. In addition, there have been two USDA disaster declarations from heavy rain and storms (once in 2016 and once in 2017) since 2012.

Table D-8 Plumas County – State and Federal Disaster Declarations from Flood (Heavy Rain and Storms) 1950-2025
Disaster Type State Declarations Federal Declarations
Count Years Count Years
Flood (including heavy
rains and storms)
22 1950, 1955, 1958 (twice), 1964,
1963, 1964, 1969, 1970 1980,
1986, 1993, 1992*, 1995
(twice*), 1996, 1997, 2006, 2017
(twice*), 2023 (twice*)
19 1950, 1955, 1958 (twice), 1963,
1964, 1969, 1970, 1986, 1992
(twice), 1995 (twice), 1997,
2006*, 2017 (twice*), 2023
(twice*)
Source: Cal OES, FEMA
NCDC Events
The NCDC data recorded 132 hail, heavy rain, and storm incidents for Plumas County since 1950.

GMCSD Events
The District noted that heavy rains and storms are an annual occurrence often resulting in flooding.

Climate Change and Heavy Rains and Storms
It is likely that climate change will increase the chance of future occurrence as well as future impacts from heavy rains and storms. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

According to the 2021 CAS (as well as the 2024 Draft CAS), while average annual rainfall may increase or decrease slightly, the intensity of individual rainfall events is likely to increase during the 21st century.

It is unlikely that hail will become more common in Plumas County and the GMCSD. The amount of lightning is not projected to change.

Cal-Adapt noted that, on average, the projections show little change in total annual precipitation in California. Furthermore, among several models, precipitation projections do not show a consistent trend during the next century. Cal-Adapt modeled scenarios are shown in Section 4.3.4 of the Base Plan.

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Plumas County GMCSD Annex D-43
Local Hazard Mitigation Plan Update
January 2026
Vulnerability to Heavy Rain and Storms
Heavy rain and severe storms are the most frequent type of severe weather occurrences in the District.

These events can cause both significant and localized flooding. Flooding can be worse during times where the ground is already saturated. Wind often accompanies these storms and has caused damage in the past.

Hail and lightning are rare in the District, but also can cause damage, with lightning occasionally igniting wildfires.

The whole of the District is at some measure of vulnerability to heavy rain and storms. An assessment of a community’s vulnerability to heavy rains and storms begins with an understanding of local exposure to heavy rain and storms. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

Flooding (from heavy rains and localized flooding) can render leachfields useless, clog pipes and cause vegetation to fall on facilities and impact accessibility to CSD facilities for repair. Power outages can also occur during large storm events impacting facility operations. Should a power outage occur, it is important that the District has backup systems in place to prevent or limit the loss of services to the community.

The District noted that one of the primary issues associated with heavy rains and storms is the resulting flooding caused by large precipitation events. The District is also concerned with rain on snow events, which can cause greater flooding in the District.

People and Populations
All District staff and the populations served by the District are at some vulnerability to heavy rains and storms. Those District employees that work outdoors could be affected to a limited extent by this hazard.

All populations served by the District have some measure of risk to heavy rains and storms. Those populations that work or recreate outside and unhoused individuals are more vulnerable to impacts from heavy storm events. Heavy rains and storms occur every year and do not generally cause significant adverse impacts to individuals; it is the secondary hazard, flooding, which poses the biggest impact to people.

Structures and Critical Facilities and Infrastructure
District facilities and structures have some risk to heavy rains and storms. Heavy rain and storms can affect critical facilities and infrastructure during large events. Structures built to modern building codes are built

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Plumas County GMCSD Annex D-44
Local Hazard Mitigation Plan Update
January 2026
to withstand heavy rains and storms (including thunderstorm winds and lightning); older structures may be more vulnerable. During a heavy storm, localized flooding may cause water intrusion into buildings and critical infrastructure from the outside. Trees can be downed causing impacts to structures. Older homes and buildings may be at increased risk to heavy rains and storms. Power outages during severe storm events can occur, impacting the use of structures until the power is back online. Local roads, streets, and bridges can be impacted resulting in closures restricting traffic flow in the District. In certain areas, large storms can cause erosion and localized landslides which can impact affected facilities.

While no facilities in Table D-2 were identified at specific risk to heavy rains and storms, they are at risk to the water intrusion and resulting flooding that can occur during these and other events.

Natural, Historic, and Cultural Resources
Large rain and storm events and associated flooding can affect natural, historic, and cultural resources. Silt and sediment can damage natural areas. Trees can be uprooted and downed by high winds. Extended periods of rainfall can erode natural banks along waterways and degrade soil stability for terrestrial species.

While some natural systems can be adversely impacted during these large storms, heavy rain events can also provide benefits. Groundwater and wetland areas can be recharged and water supplies replenished.

Historic and cultural resources may also be affected. Generally, the impacts are associated with damage to structures affected by large storm events, but other cultural resources such as those associated with Native Americans and old tribal areas can also be disturbed, damaged, and lost during extreme rain and storm and events.

Impacts from Heavy Rain and Storms
Impacts from heavy rains and storms include damage to property, critical facilities and infrastructure, and the natural landscape. This includes: erosion; downed trees; damaged utility structures and infrastructure; power outages; road damage and blockages; and even lightning strikes to critical infrastructure and people.

Lightning can also cause wildfires and urban fires to occur. Landsliding and erosion occur when the soil on slopes becomes oversaturated and fails. Climate change may cause these impacts to worsen.

Actual damage associated with the primary effects of severe storms and heavy rains has been somewhat limited. It is the secondary hazards caused by these severe weather events, such as floods and erosion that would likely have the greatest impact.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile section above), changes in population patterns, and changes in land use and development. The influencing effects of these factors on this hazard are discussed further in the Future Conditions/Future Development discussion below.

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Plumas County GMCSD Annex D-45
Local Hazard Mitigation Plan Update
January 2026
Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the District include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over time.
➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to this hazard. This limits heavy rains and storm and associated impacts to the District. In addition, adherence to protective building codes for new development will also assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, future losses to new development should be minimal.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. New District facilities follow state and local building codes which should reduce the risk to future development in the District from heavy rains and storms. New critical facilities should be built to withstand heavy rains, hail damage, lightning, and thunderstorm winds.

Severe Weather: High Winds and Tornado
Likelihood of Future Occurrence–Likely
Vulnerability–Medium
Hazard Profile
High winds, as defined by the NWS glossary, are sustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or winds of 58 mph or greater for any duration. High winds can cause significant property damage, threaten public safety, and have adverse economic impacts from business closures and power loss.

High winds, can cause power outages, and when combined with high temperatures and low humidity can also lead to PSPS events. Winds can also drive fires in and near the District.

Portions of the District are also located in or near a special wind hazard region, which is a result of foehn winds. A foehn wind is a type of dry down-slope wind that occurs in the lee (downwind side) of a mountain range. Winds of this type are called "snow-eaters" for their ability to make snow melt or sublimate rapidly.

These types of winds are also associated with the rapid spread of wildfires, making some regions which experience these winds particularly fire prone.

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Plumas County GMCSD Annex D-46
Local Hazard Mitigation Plan Update
January 2026
Another special type of wind event, microbursts, can occur in the District and the County. Microbursts have occurred in the County in the past. According to the National Weather Service, a microburst is a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale. Some microbursts can pose a threat to life and property, but all microbursts pose a significant threat to aviation. Although microbursts are not as widely recognized as tornadoes, they can cause comparable, and in some cases, worse damage than some tornadoes produce. In fact, wind speeds as high as 150 mph are possible in extreme microburst cases.

Tornadoes are rotating columns of air marked by a funnel-shaped downward extension of a cumulonimbus cloud whirling at destructive speeds of up to 300 mph, usually accompanying a thunderstorm. Tornadoes form when cool, dry air sits on top of warm, moist air. Tornadoes are the most powerful storms that exist.

Tornadoes, though rare in Plumas County, can affect areas of the District, primarily during the rainy season in the late fall, winter, and early spring.

Location and Extent
The entire District is subject to significant, non-tornadic (straight-line), winds (both straight line and microburst). Each area of the District is at risk to high winds. Magnitude of winds is measured often in speed and damages. These events are often part of a heavy rain and storm event but can occur outside of storms. The speed of onset of winds can be short, but accurate weather prediction mechanisms often let the public know of upcoming events. Duration of winds in California is often short, ranging from minutes to hours. The Beaufort scale is an empirical 12 category scale that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort Wind Force Scale. The Beaufort Scale was shown in Section

4.3.5 of the Base Plan.

Tornadoes, while rare, can occur at any location in the District. Prior to February 1, 2007, tornado intensity was measured by the Fujita (F) scale. This scale was revised and is now the Enhanced Fujita scale. Both scales are sets of wind estimates (not measurements) based on damage. The new scale (EF) provides more damage indicators (28) and associated degrees of damage, allowing for more detailed analysis and better correlation between damage and wind speed. It is also more precise because it considers the materials affected and the construction of structures damaged by a tornado. The F Scale and EF Scale are shown in Section 4.3.5 of the Base Plan.

Past Occurrences
Disaster Declarations
There have been no federal or state disaster declarations in the County for winds and tornadoes.

NCDC Events
The NCDC data recorded 94 high wind and 0 tornado incidents for Plumas County since 1950. Many of these wind events likely affected the District.

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Plumas County GMCSD Annex D-47
Local Hazard Mitigation Plan Update
January 2026
GMCSD Past Occurrences
The District could recall no events where high winds or tornadoes caused direct damage to District facilities.

Climate Change and High Winds and Tornado
According to the 2021 CAS (as well as the 2024 Draft CAS), while average annual rainfall may increase or decrease slightly, the intensity of individual thunderstorm events is likely to increase during the 21st century. This may bring stronger thunderstorm winds. The CAS does not discuss non-thunderstorm winds or tornadoes.

Vulnerability to Severe Weather: High Wind and Tornadoes The District is subject to potentially destructive high winds and tornadoes. High winds are common throughout the area and can happen during most times of the entire year and outside of a severe storm event.

Tornadoes are rare. High winds and tornadoes can be a significant public safety and economic concern.

The whole of the District is at some measure of vulnerability to wind and tornadoes.

An assessment of a community’s vulnerability to high winds begins with an understanding of local exposure to wind and tornadoes. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

As previously described, the District is concerned with foehn winds which often occur with warmer temperatures and low relative humidity. They are often associated with the rapid spread of wildfires, making some regions which experience these winds particularly fire prone. Burn patterns of almost all historic large wildfires in the larger County indicate they occurred during foehn winds.

High winds are a permanent factor in the weather impact on the Nakoma Community, and GMCSD facilities. High winds could cause trees to fall on a booster station, well system, or water tank, causing reduction of services to community until repair is completed which could be weeks. High winds can also cause power outages and can lead to PSPS events. Should a power outage occur, it is important that the District has backup systems in place to prevent or limit the loss of services to the community.

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Plumas County GMCSD Annex D-48
Local Hazard Mitigation Plan Update
January 2026
People and Populations
All District staff and the populations served by the District are at some vulnerability to high winds and tornadoes. Certain vulnerable populations are at the greatest risk to the effects of high winds and tornadoes.

These include the unsheltered, those with access and functional needs, the medically fragile experiencing power outages as a result of wind events, and those working or caught outdoors during a wind or tornado event.

Structures and Critical Facilities and Infrastructure
All structures and critical facilities and infrastructure in the District have some measure of risk from high winds and tornadoes. Though rare, a tornado could cause damage to virtually all District facilities in the tornado touchdown path. During a wind or tornado event, power lines in the District can be damaged by falling trees caused by wind. High winds are a cause for PSPS events to be declared, causing power outages to occur. High winds and tornadoes could cause sparks from electric wires and other sources, which could lead to wildfire ignition. Once ignited, high winds can also cause wildfires to rapidly spread and become out of control. High wind conditions can cause wildfires to move into more developed areas destroying structures and whole communities, as seen in recent wildfire events in the West.

The following District assets from Table D-2 are at risk to high winds (and the unlikely tornado):
➢ Booster #3 Pump House Addition
➢ Booster Pumps #1-#7
➢ Emergency Standby Generator House and Pump House (2)
➢ Water tanks (2)
➢ Dosing Station
Natural, Historic, and Cultural Resources
Natural resources, such as trees, are vulnerable to high winds. Increased streambank erosion can occur during periods of high water and high winds. High wave action during significant wind events can impact marsh lands and habitat areas. Soil erosion can also occur during high winds. Most all natural, historic, or cultural resources are at risk to tornadoes. Tornadoes can tear apart habitats, causing fragmentation across ecosystems and can damage and destroy historic structures and cultural resources.

Impacts from Severe Weather: High Winds and Tornado
Wind and tornadoes can cause damage to property and loss of life. While most tornado damage is caused by violent winds, the majority of injuries and deaths generally result from flying debris. Property damage can include damage to buildings, fallen trees, and power lines. District facilities may also be damaged or destroyed. Access roads and streets may be blocked by debris, delaying necessary emergency response.

Winds can push automobiles off roads, damage roofs and structures, cause power outages, and cause secondary damage due to flying debris and hazardous trees. High winds can also contribute to the spread and intensity of wildfires. High winds during periods of high water can cause impacts to and streambanks from accelerated erosion. Climate change may affect this hazard and cause winds to increase in velocity in the District.

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Plumas County GMCSD Annex D-49
Local Hazard Mitigation Plan Update
January 2026
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile section above), changes in population patterns, and changes in land use and development. The influencing effects of these factors on this hazard are discussed further in the Future Conditions/Future Development discussion below.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the District include the following:
➢ Climate change is likely to exacerbate future wind conditions and associated impacts and vulnerability of the County. Climate change is not likely to affect future tornado conditions. ➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to this hazard. Land use planning should be proactive to address future hazard conditions. Building codes in the County ensure that new development is built to current building standards to withstand high winds, which should reduce the risk to future development in the County from high winds and tornadoes. With adherence to development standards, future losses to new development should be minimal. Changes in land use and increased development may amplify the impacts of high winds and tornadoes, as additional structures in the District increase the number of buildings at risk to high winds and tornadoes.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. The District relies on the County to enforce the local building codes which includes standards for new development to minimize damage from windstorms. New District facilities are built to state and local codes. New critical facilities and infrastructure should also consider adding backup power systems to limit impacts associated with future power outages.

Wildfire (with smoke and air quality)
Likelihood of Future Occurrence–Highly Likely
Vulnerability–Extremely High

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Plumas County GMCSD Annex D-50
Local Hazard Mitigation Plan Update
January 2026
Hazard Profile
Wildland fire and the risk of a conflagration is an ongoing concern for the GMCSD. Throughout California, communities are increasingly concerned about wildfire safety as increased development in the foothills and mountainous areas and subsequent fire control practices have affected the natural cycle of fire regimes.

Wildland fires affect grass, forest, and brushlands, as well as structures. Where there is human access to wildland areas, the risk of fire increases due to a greater chance for human carelessness and historical fire management practices. Historically, the fire season extends from early spring through late fall of each year during the hotter, dryer months; however, in recent years, the risk of wildfire has become a year around concern.

Fire conditions arise from a combination of high temperatures, low moisture content in the air and fuel, accumulation of vegetation, and high winds. These weather conditions can result in red flag (e.g., fire weather) days, and can result in PSPS events in the District. While wildfire risk has predominantly been associated with more remote forested areas and wildland urban interface (WUI) areas, significant wildfires also occur in more populated, developed areas. There is also the concern of wildfires occurring in these more remote, forested areas, that under certain weather conditions, can extend into areas not generally considered at a high risk to wildfire. Smoke and air quality also become an issue, both from fires occurring inside and outside of the Plumas County Planning Area and the District.

Wildfire Smoke and Air Quality
Smoke from wildfires is made up of gas and particulate matter, which can be easily observed in the air. Air quality standards have been established to protect human health with the pollutant referred to as PM2.5 which consists of particles 2.5 microns or less in diameter. These smaller sizes of particles are responsible for adverse health effects because of their ability to reach the lower regions of the respiratory tract.

Wildfire smoke can have negative effects to those who live in or near a fire burn area. Smoke and air pollution from wildfires can be a severe health hazard. Significant wildfires occurring in both Plumas County, nearby northern California communities, and elsewhere have created significant air pollution affecting area residents. This was the case during the 2021 Caldor Fire, as well as others that affected the Plumas County Planning Area.

Location and Extent
Wildfire can affect all areas of the District. CAL FIRE through recent mapping efforts has created updated wildfire maps showing risk variance across the District and the Plumas County Planning Area. Following the methodology described in Section 4.3.16 of the Base Plan, wildfire maps for the GMCSD were created.

Figure D-4 shows the CAL FIRE State Responsibility Areas (SRA) and Federal Responsibility Areas (FRA) and their associated Fire Hazard Severity Zones (FHSZ) in the District. Figure D-5 shows the CAL FIRE Local Responsibility Areas (LRA) and their associated Fire Hazard Severity Zones (FHSZ) in the District. As shown in the SRA/FRA map, the entirety of the District lies in the Extremely High FHSZ. The LRA maps do not cover the portion of the County where the District is located.

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Plumas County GMCSD Annex D-51
Local Hazard Mitigation Plan Update
January 2026
Figure D-4 GMCSD – CAL FIRE SRA/FRA Fire Hazard Severity Zones

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Plumas County GMCSD Annex D-52
Local Hazard Mitigation Plan Update
January 2026
Figure D-5 GMCSD – CAL FIRE LRA Fire Hazard Severity Zones Wildfires tend to be measured in structure damages, injuries, and loss of life as well as on acres burned.

Fires can have a quick speed of onset, especially during periods of drought or during hot dry summer months. Fires can burn for a short period of time or may have durations lasting for a week or more.

Geographical FHSZ extents in the SRA/FRA are shown in Table D-9. No District area falls in the LRA; as such, no tabular analysis is presented here.

Table D-9 GMCSD – CAL FIRE SRA/FRA Fire Hazard Severity Zone Geographical Extents Fire Hazard
Severity
Zones
Total Acres % of Total
Acres*
Improved
Acres
% of Total
Improved
Acres*
Unimproved
Acres
% of Total
Unimproved
Acres*
Very High 1,297 100.0% 422 100.0% 875 100.0%
High 0 0.0% 0 0.0% 0 0.0%
Moderate 0 0.0% 0 0.0% 0 0.0%
NonWildland/NonUrban0 0.0% 0 0.0% 0 0.0%

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Plumas County GMCSD Annex D-53
Local Hazard Mitigation Plan Update
January 2026
Fire Hazard
Severity
Zones
Total Acres % of Total
Acres*
Improved
Acres
% of Total
Improved
Acres*
Unimproved
Acres
% of Total
Unimproved
Acres*
Outside of
Federal / State
Responsibility
Area
0 0.0% 0 0.0% 0 0.0%
Grand Total 1,297 100.0% 422 100.0% 875 100.0%
Source: CAL FIRE
* CAL FIRE's FHSZ SRA (FHSZSRA_23_3) released in April 2024. CAL FIRE's FHSZ FRA not updated as part of the new SRA release. The new data (SRA areas) and the old FRA areas were merged in GIS to provide countywide SRA/FRA coverage. Dataset does not include any LRA coverage nor does it include any old SRA coverage. The percentages in the table below are calculated by the total acreage of the SRA/FRA data coverage within each jurisdiction Past Occurrences
Disaster Declaration History
There have been eight state and six federal disaster declarations due to fire, as shown in Table D-10.

Table D-10 Plumas County – State and Federal Wildfire Disaster Declarations 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Fire 8 1960 (unnamed), 1987(Clarks
Fire), 1999 (Bucks Fire), 2020
(twice – Bear Fire, North
Complex Fire), 2021 (three –
Dixie Fire, Monument Fire,
Lava Fire/Beckwourth
Complex)
6 1999 (Bucks Fire), 2008 (BTU
Lightning Complex), 2020
(twice – Bear Fire, North
Complex Fire), 2021 (twice –
Dixie Fire, Lava
Fire/Beckwourth Complex)
Source: Cal OES, FEMA
NCDC Events
The NCDC has tracked 15 wildfire events in the County dating back to 1993. Many more fires have occurred, but were not reported to the NCDC database.

GMCSD Events
The District noted that there were the following significant event that affected the District:

July 22-29, 2024 – The Gold Complex Fire occurred, which was a major wildfire event adjacent to the GMCSD community. It occurred on National Forest Service lands and private forestry lands east of Hwy 89 and south of GMCSD. This was the most severe event resulting from lightning strikes in or near the community since its inception in 1996. Collateral damage resulted due to CSD’s support providing water from our system to fight the fire. Drawdown resulted in a negative pressure situation and system contamination. The Community was evacuated, and the Nakoma Resort shutdown and had all their events cancelled. Loss of income was high, but no estimates were available. All CSD resources including

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Plumas County GMCSD Annex D-54
Local Hazard Mitigation Plan Update
January 2026
personnel and fire apparatus were dedicated to support firefighting efforts and providing water to supporting fire departments. Due to the Fire, Highway A15 and access to the Gold Mountain community was shut down for 4 days.

Climate Change and Wildfire
It is likely that climate change will increase the chance of future occurrence as well as future impacts from wildfire. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Warmer temperatures can exacerbate drought conditions. Drought often kills plants and trees, which serve as fuel for wildfires. Warmer temperatures could increase the number of wildfires and pest outbreaks, such as the western pine beetle. Cal-Adapt’s wildfire tool predicts the potential increase in the amount of burned areas for the year 2090-2099, as compared to recent (2010) conditions. This is shown in Section 4.3.16 of the Base Plan. Based on this model, Cal-Adapt predicts that wildfire risk in Plumas County will increase moderately at the end of the century. However, wildfire models can vary depending on the parameters used. Cal-Adapt does not take landscape and fuel sources into account in their model. In all likelihood, in the Plumas County Planning Area, precipitation patterns, high levels of heat, topography, and fuel load will determine the frequency and intensity of future wildfire.

Vulnerability to Wildfire
Risk and vulnerability to the District from wildfire is of significant concern. Wildfires in the District occur from a variety of both natural and manmade causes. The District can be affected both by fires that start on or near District lands as well as those that start elsewhere and move into the District. In addition to burning large areas of land, air quality can be affected in the District by smoke from fires occurring inside the District as well as those from many miles away.

The whole of the District is at some measure of vulnerability to wildfire. An assessment of a community’s vulnerability to wildfire begins with an understanding of local exposure to wildfire. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

The 2024 Gold Complex Fire highlighted areas that need annual review and identified upgrades. .Heavy use of one fire hydrant caused an area in the community to have no water for a few days until the tank could refill. If heavy ground/ladder fuel exists around water tanks or booster stations, water supply to the community could be negatively impacted. The GMCSD would be unable to perform its obligation to supply potable water to the community.

The GMCSD is charged with providing structural fire protection and emergency medical services to the Gold Mountain community. These services are provided through an agreement (annual contract) with the

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Plumas County GMCSD Annex D-55
Local Hazard Mitigation Plan Update
January 2026
Beckwourth Fire District. The Nakoma community is a FireWise Community, which certifies the community’s efforts to reduce fire risk. The mission of the Nakoma Community Firewise Committee is to support and encourage activities which reduce hazardous fire fuel loads in our community.

The changes in climate have been motivation to create a “Forest Management” Program, started in 2024.

The “joint” committee is made up of both Gold Mountain CSD and HOA members. Its goal is to identify and act upon best fuel mitigation practices to keep the community at a reduced fire risk within budgeted annual funding. To facilitate fuels management efforts, the District was mapped into 12 zones which are used to prioritize and conduct fuel mitigation actions such as mastication, tree removal, and chipping. It is important for these local community efforts to continue.

Assets at Risk
Assets at risk from this hazard include people and populations served; structures and critical facilities; and natural, historic, and cultural resources. These are discussed in the following sections.

People and Populations
All populations (both District staff and District Service Area populations) are at some vulnerability to wildfire. Certain vulnerable populations are at greater risk to the effects of wildfire as well as smoke and air quality issues that wildfires bring. Vulnerable populations include the unhoused, infants and children under age five and their caregivers, the elderly (65 and older), individuals with disabilities, individuals’ dependent on medical equipment, individuals who exercise, recreate, or work (like District staff) outdoors, and individuals with impaired mobility.

Structures and Critical Facilities and Infrastructure
All structures in the District have some risk to wildfire. Wildfire presents a threat to critical facilities and infrastructure. Key GMCSD assets at risk from Table D-2 include the Booster Stations, and Emergency Standby Generator, and Pump Houses; although all assets in the path of an out of control wildfire are at risk.

Natural, Historic, and Cultural Resources
Natural, historic, and cultural resources located within areas at risk to wildfire would be vulnerable. Should a wildfire occur in the District, the impacts to natural, historic and cultural resources could be extensive and include air pollution, contamination from water runoff containing toxic products, other environmental discharges or releases from burned materials affecting soils, habitat areas, wildlife, and aquatic resources, and total destruction of natural resources. Debris and runoff from burned areas can affect reservoirs and rivers in the District. Historic and cultural resources can be damaged or destroyed and are often more vulnerable due to their older age, construction type, and lack of fire prevention infrastructure such as sprinklers.

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Plumas County GMCSD Annex D-56
Local Hazard Mitigation Plan Update
January 2026
Impacts from Wildfire
Potential impacts from wildfire include loss of life and injuries; damage to structures, critical facilities and infrastructure, and other improvements, natural and cultural resources, croplands, and timber; and loss of recreational opportunities. Out of control wildfires can have catastrophic impacts. Wildfires can cause short-term and long-term disruption to the District. Fires can have devastating effects on watersheds through loss of vegetation and soil erosion, which may impact the District by changing runoff patterns, increasing sedimentation, reducing natural and reservoir water storage capacity, and degrading water quality. Fires can also affect air quality in the District; smoke and air pollution from wildfires can be a severe health hazard. Smoke impacts may come from wildfires outside the District, as well as from within.

Although the physical damages and casualties arising from wildland-urban interface or conflagration fires may be severe, it is important to recognize that they also cause significant economic impacts by resulting in a loss of function of buildings and infrastructure. Economic impacts of loss of transportation and utility services may include traffic delays/detours from road and bridge closures and loss of electric power, potable water, and wastewater services. Schools and businesses can be forced to close for extended periods of time.

Recently, the threat of wildfire, combined with the potential for high winds, heat, and low humidity, has caused PG&E, Plumas Sierra REC, or Liberty Utilities to initiate a PSPS which can also significantly impact a community through loss of services, business closures, and other impacts associated with loss of power for an extended period. In addition, catastrophic wildfire can create favorable conditions for other hazards such as flooding, landslides, and erosion during the rainy season.

The impacts of a fire are felt long after the fire is extinguished. In addition to the loss of property in fires, the loss in vegetation and changes in surface soils alter the environment. When supporting vegetation is burned, hillsides become destabilized and prone to erosion. The burnt surface soils are harder and absorb less water. When winter rains come, this leads to increased runoff, erosion, and landslides in hilly areas.

Wildfire smoke can also have negative effects to those who live in or near a fire burn area. Smoke and air pollution from wildfires can be a severe health hazard. Significant wildfires occurring in nearby northern California communities since the previous LHMP have created significant air pollution affecting area residents. District residents have been affected by wildfire smoke and poor air quality, from fires both within the County and from those much further away.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the hazard profile above), changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. These are discussed in the Future Conditions/Future Development discussion below.

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Plumas County GMCSD Annex D-57
Local Hazard Mitigation Plan Update
January 2026
Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the GMCSD include the following:
➢ Climate change is likely to exacerbate future wildfire conditions and associated impacts and vulnerability of the District to wildfire.
➢ Population projections for the area served by the District show the population to be slowly increasing, with an additional 1-4 residences added annually. The District may add staff, but this number would be small. It is unlikely that this limited growth would increase the vulnerability of the District to localized flooding over the next 5 years. The District noted that it continues to accommodate additional populations in the District by providing additional services. ➢ Changes in land use and development in the District are expected to be limited in the near future, estimated at 1-4 new residences added annually, and thus are not likely to significantly increase the vulnerability of the District to this hazard. In addition, adherence to protective building codes for new development will also assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, future losses to new development should be minimal.

The District will take wildfire into account when siting new facilities. Fire hydrants, defensible space, well production, water storage, and distribution should all be considered when assessing future development.

New facilities will be built to the most current California Building standards for wildfire.

Future Development
As previously described, the District has plans for future development including additions to their current water and wastewater facilities and infrastructure and adding new customer hookups as the community continues to grow. Additional growth and development within the very high fire hazard severity zone, which covers the entirety of the District, would place additional assets at risk to wildfire. More vulnerable populations may experience a disproportionate impact from wildfire, and this should be considered as development occurs. District building codes are in effect and should continue to be updated as appropriate to reduce future impacts.

D.5 Capability Assessment
Capabilities are the programs and policies currently in use to reduce hazard impacts or that could be used to implement hazard mitigation activities. This capabilities assessment is divided into five sections:
regulatory mitigation capabilities, administrative and technical mitigation capabilities, fiscal mitigation capabilities, mitigation education, outreach, and partnerships, and other mitigation efforts.

D.5.1. Regulatory Mitigation Capabilities
Table D-11 lists regulatory mitigation capabilities, including planning and land management tools, typically used by local jurisdictions to implement hazard mitigation activities and indicates those that are in place in the GMCSD.

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Plumas County GMCSD Annex D-58
Local Hazard Mitigation Plan Update
January 2026
Note: The District does not have the authority to regulate land use and development within its jurisdiction.

Authority for promulgating and enforcing zoning, land use, and development requirements falls to counties and incorporated communities. As such development within the District’s jurisdictional boundaries will conform to the zoning and land use development ordinances and building codes of the county or incorporated community in which the District is located.

Table D-11 GMCSD’s Regulatory Mitigation Capabilities
Plans
In Place
Y/N
Does the plan address hazards? Can the plan be used to
carry out mitigation actions? When was it last updated?? Capital Improvements Plan Y Capital Improvements Planning is in process Climate Change Adaptation Plan N
Community Wildfire Protection Plan N
Comprehensive/Master Plan Y A 5-year/2024 Master Plan included hazards. It is being updated in 2026.

Continuity of Operations Plan N
Economic Development Plan N
Land Use Plan N
Local Emergency Operations Plan N
Stormwater Management Plan N
Transportation Plan N
Other None/Not applicable to CSD
Land Use Planning and Ordinances Y/N
Is the ordinance an effective way to reduce hazard
impacts?
Is the ordinance adequately administered and enforced?
Acquisition of land for open space and
public recreation use
N
Building code N
Flood insurance rate maps N
Floodplain ordinance N
Natural hazard-specific ordinance
(stormwater, steep slope, wildfire)
N
Subdivision ordinance N
Zoning ordinance N
Other Y GMCSD 5-year Plan
How can these capabilities be expanded and improved to reduce risk? The District is updating its Master Plan in 2026. Outside of that, the District has few of these capabilities. The District will continue to work with the County (who provides these capabilities) to reduce risk in the District area.

Source: GMCSD

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Plumas County GMCSD Annex D-59
Local Hazard Mitigation Plan Update
January 2026
D.5.2. Administrative/Technical Mitigation Capabilities Table D-12 identifies the District department(s) responsible for activities related to mitigation and loss prevention in the GMCSD.

Table D-12 GMCSD’s Administrative and Technical Mitigation Capabilities Administration
In
Place
Y/N
Describe capability
Is coordination effective?
Staff
Is staffing adequate to enforce regulations?
Is staff trained on hazards and mitigation?
Is coordination between agencies and staff effective?
Chief Building Official N
Civil Engineer, including dam and levee
safety
N
Community Planner N
Emergency Manager N
Floodplain Administrator N
GIS Coordinator N
Planning Commission N
Other Y District General Manager has some measure of understanding of risk reduction. GM coordinates with County and local agencies on hazard related issues.

Technical Y/N
Has capability been used to assess/mitigate risk in the past?
Grant writing N
Hazard data and information N
GIS analysis N
Mutual aid agreements N
Other
How can these capabilities be expanded and improved to reduce risk? The District could seek a grant writer (on a contract basis) to help write grants to reduce risk in the District.

Source: GMCSD
D.5.3. Fiscal Mitigation Capabilities
Table D-13 identifies financial tools or resources that the District could potentially use to help fund mitigation activities.

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Plumas County GMCSD Annex D-60
Local Hazard Mitigation Plan Update
January 2026
Table D-13 GMCSD’s Fiscal Mitigation Capabilities
Funding Resource
In Place
Y/N
Has the funding resource been used in past
and for what type of activities?
Could the resource be used to fund future
mitigation actions?
Capital improvements project funding N
Community Development Block Grant N
Federal funding programs (non-FEMA) N
Fees for water, sewer Y
Capacity fees for new development N
State funding programs N
Stormwater utility fee N
Other Y GMCSD 5-year Plan includes identification and
allocation of funding through District
generated fees.

How can these capabilities be expanded and improved to reduce risk? The District is looking to find grant funding from state or federal sources for hazard risk reduction. A grant writer may be needed to assist with this.

Source: GMCSD
D.5.4. Mitigation Education, Outreach, and Partnerships Table D-14 identifies education and outreach programs and methods already in place that could be/or are used to implement mitigation activities and communicate hazard-related information.

Table D-14 GMCSD’s Mitigation Education, Outreach, and Partnerships Program/Organization
In Place
Y/N
How widespread are each of these in your
community?
Community newsletters Y To all members who provided names and posted to GM CSD website
Hazard awareness campaigns (such as Firewise,
Storm Ready, Severe Weather Awareness Week,
school programs, public events)
Y Firewise, meetings and posts to GMCSD
website
Local news N
Organizations that interact with underserved and
vulnerable communities
N
Social media Y Posts to GMCSD website
How can these capabilities be expanded and improved to reduce risk? The District works to outreach to the population it serves. Additional outreach may be needed in terms of how the Agency is reducing risk. Outreach to homeowners in the District to do the same may need to occur.

Source: GMCSD

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Plumas County GMCSD Annex D-61
Local Hazard Mitigation Plan Update
January 2026
D.5.5. Other Mitigation Efforts
The District has many other completed or ongoing mitigation projects/efforts that include the following:

When Gold Mountain was developed, only seven fire hydrants were required, all serving commercial uses.

Over time the District has added 15 additional hydrants at strategic locations to cover the community. It is important to understand that the fire department uses the hydrants to fill their trucks, not to connect a hose to fight the fire. We work closely with our fire providers to identify the best location for hydrants to strategically cover the entire community and will continue to add additional hydrants as the community grows.

GMCSD maintains two 140,000 gallon water storage tanks to ensure we have adequate water supplies for firefighting. In addition, the CSD partnered with the Nakoma Resort to ensure its new 90,000 gallon recreational pool was equipped with hookups to make that additional water source available in the case of an emergency. Nakoma's golf course also includes a number of large holding ponds as part of its irrigation and landscape plans. Rural fire departments all include suction equipment to ensure such pools are also available as a water source in an emergency.

The GMCSD has partnered with the GM Homeowners Association (HOA) to develop a limited quick attack firefighting capability. Using a large pickup equipped with a water tank. Foam generators, and gasoline powered pump, we have created a Quick Attack Vehicle (QAV) to provide an initial response capability in the community. Each year the CSD's Fire Coordinator provide training to a cadre of community volunteers on this system, first aide, and basic wild land firefighting techniques. There have been a number of incidents where community volunteers using the QAV were first on scene to knock down small fires.

The GMCSD sponsors a highly recognized Firewise (Community) Committee that has received accolades at county and state levels for their aggressive and creative approach towards fire safety within the community. Committee holds regular awareness meetings year round, evacuation drills during the fire season, and a pancake breakfast as part of the annual owners meeting.

In conjunction with the Gold Mountain HOA, and in cooperation with the Firewise Committee, the District has been very active in developing and implementing a hazardous fuel treatment (HFT) program at Gold Mountain. Reducing the fuel load is a significant step towards ensuring our resilience to wildfire. Wildland fire protection is provided by the United States Forest Service and all local volunteer fire departments.

D.6 Mitigation Strategy
D.6.1. Mitigation Goals and Objectives
The GMCSD adopts the hazard mitigation goals and objectives developed by the HMPC and described in Chapter 5 Mitigation Strategy.

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Plumas County GMCSD Annex D-62
Local Hazard Mitigation Plan Update
January 2026
D.6.2. NFIP Mitigation Strategy
The District does not participate in the NFIP, as it is not an eligible participant. Some of the District’s projects work to reduce impacts from flooding thus furthering the objectives of the NFIP.

D.6.3. Mitigation Actions
The Planning Team for the GMCSD identified and prioritized the following mitigation actions based on the risk assessment. Background information and information on how each action will be implemented and administered, such as ideas for implementation, responsible office, potential funding, and timeline are also included. The following hazards were considered a priority to the District for purposes of mitigation action planning based on criteria detailed in Chapter 5:
➢ Drought & Water Shortage (w/tree mortality)
➢ Earthquake
➢ Floods: Localized Stormwater
➢ Landslide, Mudslide, and Debris Flow
➢ Severe Weather: Extreme Cold, Freeze, and Snow (w/avalanche) ➢ Severe Weather: Extreme Heat
➢ Severe Weather: Heavy Rain and Storms (Wind, Hail, Lightning) ➢ Severe Weather: High Winds and Tornado
➢ Wildfire (w/smoke and air quality)
Non-priority hazards to the District for mitigation planning include:
➢ Agricultural Hazards (Severe Weather/Pests/Invasive Species) ➢ Climate Change
➢ Dam Failure
➢ Floods: 1%/0.2% annual chance (w/levee failure)
➢ Hazardous Materials Transport
➢ Volcano
It should be noted that many of the projects submitted by each jurisdiction in Table 5-4 in the Base Plan benefit all jurisdictions whether or not they are the lead agency. Further, many of these mitigation efforts are collaborative efforts among multiple local, state, and federal agencies. In addition, the countywide public outreach action, as well as many of the emergency services actions, apply to all hazards and jurisdictions regardless of hazard priority. Collectively, this LHMP’s multi-jurisdictional mitigation strategy includes only those actions and projects which reflect the actual priorities and capacity of each jurisdiction to implement over the next 5-years covered by this plan. It should further be noted, that each jurisdiction has focused on identifying those mitigation actions and projects to address their priority hazards, which are both realistic and reasonable for them to implement for this 5-year planning process, and would like to preserve their right to modify hazard priorities should future projects be identified where the implementing jurisdiction has the future capacity to implement.

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Plumas County GMCSD Annex D-63
Local Hazard Mitigation Plan Update
January 2026
Mitigation Actions
Action 1. Drought Impact on CSD Service
Hazards Addressed: Drought and water shortage (that may cause low potable water supplies, lack of or low water for hydrants-impacting fire protection), Severe Weather: Extreme Heat, Severe Weather: High Winds, Wildfire
Goals Addressed: 1, 2, 3, 4, 5, 6, 7, 8, 9
Issue/Background (Problem Statement): GMCSD water district depends on ground/deep well water for supply of potable water to community. There are no alternatives for water supply to community. In the event of a fire, water usage for hydrants vs community may be an issue, as seen in Gold Complex fire of 2024. Fires occur during periods of high temperatures, drought, and high winds.

Project Description: Identify cost and location for additional water tank. Prepare a plan to implement an effective wastewater capture system to help homeowners reduce potable water use. Identify non potable equipment for use in areas such as exterior irrigation systems and educate community on potable water conservation actions, such as during red flag days to request limited use of water.

Other Alternatives: Explore alternate water sources such as adjacent water rights owners, major rehabilitation of existing wells, add an additional well. Plan for additional water tank(s) to increase storage capacity. Plan for Wastewater Plant to aid in recapture of water and reuse accordingly. Update engineering plans based on current planned construction demands in the community. Develop Finance Strategy for next phase of capital projects based on Engineering Plans.

Existing Planning Mechanism(s) through which Action Will Be Implemented: GMCSD 5-year/Master Plan
Responsible Office/Partners: Gold Mountain Community Services District Director in coordination with District Board.

Benefits (Losses Avoided): Ability to provide water and septic services to Nakoma Community as required.

Potential Funding (Local Budgets, Grant Funds, etc.): None at this time other than GMCSD Operating Budget, GMCSD water and sewer fees. Will pursue possible grant funding as identified such as FEMA HMA grants; possible grant funding through new legislation associated with California Drinking Water State Revolving Fund (DWSRF) for projects that support both drinking water systems and wildfire suppression
Timeline: 2025-2030
Project Priority (High, Medium, Low): High – Water tank, Booster Station; Medium –Wastewater Plant

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Plumas County GMCSD Annex D-64
Local Hazard Mitigation Plan Update
January 2026
Action 2. Earthquake/Flood/Landslide/Severe Weather/Wildfire Mitigation Hazards Addressed: Earthquake, Flood, Localized Flood, Landslide, Severe Weather: Extreme Cold, Freeze, and Snow, Severe Weather: Extreme Heat, Severe Weather: Heavy Rain and Storms, and Severe Weather: High Winds, Wildfire (all have a potential impact on infrastructure of GM CSD water tanks, booster stations, pipes, and septic fields).

Goals Addressed: 1, 2, 3, 4, 5, 6, 7, 8, 9
Issue/Background (Problem Statement): A large damaging earthquake event in or near the District could cause significant damage to its underground pipes, as well as its above ground appurtenances. Critical damage to District systems could interrupt services for an extended period of time until repairs can be made.

High winds are a permanent factor in the weather impact on the Nakoma Community, and GMCSD facilities. High winds could cause trees to fall on a booster station, well system, water tank, causing reduction of services to community until repair is completed which could be weeks. Landslides can also cause same issues to impact on GM facilities, perhaps making access to the area or equipment limited for a longer time than just repair. Flooding (including heavy rains and localized flooding) could render leachfields useless, clog pipes and cause vegetation to fall on facilities and impact accessibility to CSD facilities for repair. Rain on snow events often compound the impacts associated with heavy rains and flooding to District facilities. Extreme temperatures can also cause issues to CSD systems. Wildfire can damage and destroy CSD assets. All of these hazard concerns could render the District inoperational and unable to perform its obligation to supply water and wastewater to the community.

Project Description: Multi-hazard assessment of the impact of all CSD identified hazards of concern on critical water and wastewater systems. Identify, evaluate, and prioritize potential impacts from low to high on CSD equipment from all priority hazards, such as water tanks, booster stations, water pipes, septic field and update both action and dollars needed to support, enhance , harden ,or rectify any noted issues to make them more resilient to future hazard events.

Other Alternatives: none
Existing Planning Mechanism(s) through which Action Will Be Implemented: Annual survey and recommendations with help from outside professional sources if needed Responsible Office/Partners: Gold Mountain Community Services District Director in coordination with District Board.

Benefits (Losses Avoided): Prevent/reduce loss of GM CSD’s ability to service community as required.

Potential Funding (Local Budgets, Grant Funds, etc.): As of 2025, funding is only through GM CSD Operating Budget, GMCSD water and sewer fees and Community fees. Will pursue possible grant funding as identified such as FEMA HMA grants
Timeline: 2025-2030
Project Priority (High, Medium, Low): High

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Plumas County GMCSD Annex D-65
Local Hazard Mitigation Plan Update
January 2026
Action 3. Fire Prevention Hazard and Impact on CSD Services Hazards Addressed: Wildfire, Severe Weather: Extreme Heat, Severe Weather: High Winds Goals Addressed: 1, 2, 3, 4, 5, 6, 7, 8, 9
Issue/Background (Problem Statement): The 2024 Gold Complex Fire (driven by heat and high winds) highlighted areas that need annual review and upgrades if needed. Heavy use of one fire hydrant caused an area in the community to have no water for a few days until tank could refill. If heavy ground/ladder fuel exists around water tanks or booster stations, impact on water supply to the community could be negatively impacted. CSD would be unable to perform its obligation to supply potable water.

Project Description: Identification of Fire Hazards and Impact in community near CSD facilities, water towers, booster stations, fire hydrants. Annual fire hazard identification for remediation plans, including the following:
➢ annual survey to map and identify all territories in GM that can create fire hazards ➢ annual identification and removal of fire hazards close to water towers, booster stations, CSD properties ➢ create and post updated signage on each fire hydrant in CSD district for flow rate, usage and map of additional nearby hydrants for First Responder usage.
➢ hold annual meeting with First Responders to ensure all are familiar with availability and location of fire hydrants, gate codes, community topography.
➢ continue Forest Management 8 zone mapping which will identify areas for remediation and help map out timing to best implement fuel reduction based on projected finances available.

Other Alternatives: None
Existing Planning Mechanism(s) through which Action Will Be Implemented: There is a 5 year /Master Plan that identifies work and upgrades on water and well systems-total dollars identified is $6,077,936.98. CSD Board Meetings where Directors will vote on projects to be first acted upon based upon both ranking of probability hazard and dollars available vs. to be set aside from CSD fees to community.

Responsible Office/Partners: Gold Mountain Community Services District Director in coordination with District Board.

Benefits (Losses Avoided): Infrastructures such as stable water tanks, potable well systems will allow CSD to perform its role to supply water and septic to community. There are no other options for Nakoma Community for water or septic access other than GMCSD
Potential Funding (Local Budgets, Grant Funds, etc.): As of this time, the only funding is through GMCSD Operating Budget and GMCSD water and sewer fees. Grant funds, such as FEMA HMA funding will be identified and sought. Possible grant funding through new legislation associated with California Drinking Water State Revolving Fund (DWSRF) for projects that support both drinking water systems and wildfire suppression

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Plumas County GMCSD Annex D-66
Local Hazard Mitigation Plan Update
January 2026
Timeline: 5 year plan starting in 2025
Project Priority (High, Medium, Low): High
Action 4. Gold Mountain Community Service District Policy Title; Water Service Policy, Policy Number: 5100
Hazards Addressed: Drought and Water Shortage, Severe Weather: Extreme Heat Goals Addressed: 1, 2, 3, 4, 5, 6, 7, 8, 9
Issue/Background (Problem Statement): Gold Mountain water is obtained through drilled Wells that have been identified in Fault Lines in Community. Residential overuse of potable water occurs on irrigation, residential landscaping and open air water features such as pools or ponds that exceed normal household usage, and homes that have had a broken pipe without residential knowledge. Overuse creates potential shortage of potable water supply for all residences currently and for future growth, caused by water pipe leaks, excessive use of water on irrigation and landscaping features Project Description: Updated Water Service Policy 5100-for approval by Board. Adopt new standards for potable water monitoring and usage. Mandate 2 meters on homes with irrigation. One for residence, one for landscape irrigation. All Landscape over 5000 sq ft must have separate water meter per WELO/ (California Water Efficient Landscaping Ordinance). All new residential applications must submit plans for landscaping or ponds. All recirculating open-air features or ponds will not exceed 5,000 gallons if using potable water. Exceeding 5,000 gallons must then use non-potable such as rainwater or gray water. Any rooftop sprinkler system must utilize non-potable water supplied by storage tank or pond.

Other Alternatives: Homeowners can supply own non-potable water through use of run-off, rainwater, but must check with HOA if structure would be in compliance with home finishing rules.

Existing Planning Mechanism(s) through which Action Will Be Implemented: GMCSD to vote on amendment to water policy 5100 at the January 16th Board Meeting. Amendment will then become enforceable. If it does not get majority vote, amendments will be presented at later meetings to address Board Concerns.

Responsible Office/Partners: Gold Mountain Community Services District Director in coordination with District Board.

Benefits (Losses Avoided): Potable water shortage potential will be limited due to consistent monitoring and restrictions to usage.

Potential Funding (Local Budgets, Grant Funds, etc.): Funding through Budget of GMCSD Residential Sewer and Water fees as part of Operating Budget. Must be voted on for use in Budget or additional financing will need to be sought. Possible grants include FEMA HMGP, Small Community Drinking Water Program, grants/loans via drinking water state revolving funds, USDA’s programs for rural systems and state funding through DWR for groundwater management.

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Plumas County GMCSD Annex D-67
Local Hazard Mitigation Plan Update
January 2026
Timeline: If Ordinance passes, action on follow through and identification of homes that need meters will be started within the year and completed within 5 years.

Project Priority (High, Medium, Low): High
Action 5. Supplemental/Alternative Water Sources
Hazards Addressed: Drought and Water Shortage; Earthquake, Wildfire, Severe Weather: Extreme Heat Goals Addressed: 1, 2, 3, 4, 5, 6, 7, 8, 9
Issue/Background (Problem Statement): Potable Water in Nakoma Community is circulated through Wells that are drilled into mapped Fault Lines in the community. In the event the existing Wells cannot fill Community minimum requirements, or new Wells not easily drilled, there is no current back up source easily accessed. It is necessary to identify potential Water Sources and Supplies in the event of drought, earthquake, excessive use, or other events that cause current potable Well Water to be insufficient to serve Community needs.

Project Description: The system is reviewed by Engineers every 5 years and updated as needed for- water flow, wells that are not performing as needed, and updating the data on maps for potential spots for new wells in Fault lines to be drilled. New reviews to include viability for locations and costs for Recharge Basins to capture ground water, and the return on investment.

Other Alternatives: Build a surface water treatment plant for groundwater to create potable water in the event wells not refilling to extent needed. This is an expensive alternative.

Existing Planning Mechanism(s) through which Action Will Be Implemented: Engineering reviews the output of the system every five years. Identification of best possible land for recharge basins is updated.

Building Blueprint and Cost to change the system would need to be proposed to the CSD Board and voted on how and when the money would be available.

Responsible Office/Partners: Gold Mountain Community Services District Director in coordination with District Board.

Benefits (Losses Avoided): Use “run off” water for community non-potable needs, and if needed, build a surface water treatment plant that would supplement existing well output for potable needs.

Potential Funding (Local Budgets, Grant Funds, etc.): Would need to reach out for funding, most likely through Grants, especially if surface water treatment plant is needed. Possible grants include FEMA HMGP, Small Community Drinking Water Program, grants/loans via drinking water state revolving funds, USDA’s programs for rural systems and state funding through DWR for groundwater management.

Timeline: 2026-2031, review every 5 years, or if conditions such as drought become severe Project Priority (High, Medium, Low): Low

Page 1063 ends

Plumas County IVCSD Annex E-1
Local Hazard Mitigation Plan Update
January 2026
Annex E Indian Valley Community Services District
E.1 Introduction
This Annex details the hazard mitigation planning elements specific to the Indian Valley Community Services District (IVCSD or District), a new participating jurisdiction to the 2026 Plumas County Local Hazard Mitigation Plan (LHMP) Update. This Annex is not intended to be a standalone document but appends to and supplements the information contained in the Base Plan document. As such, all sections of the Base Plan, including the planning process and other procedural requirements apply to and were met by the District. This Annex provides information specific to the IVCSD, with a focus on providing additional details on the planning process, risk assessment, and mitigation strategy for this jurisdiction.

E.2 Planning Process
As described above, the IVCSD followed the planning process detailed in Chapter 3 of the Base Plan. In addition to providing representation on the Plumas County Hazard Mitigation Planning Committee (HMPC), the District formulated their own internal planning team to support the broader planning process requirements. Internal planning participants, their positions, and how they participated in the planning process are shown in Table E-1. Additional details on Plan participation and District representatives are included in Appendix A.

Table E-1 IVCSD – Planning Team
Name Position/Title How Participated
Jamie Little Interim GM Attended meetings, Planning and coordination, Provided input to Annex, Developed mitigation actions and reviewed Plan drafts Charles Slagter Operations Manager Provided historical information.

Bob Orange Previous fire chief
and current
community member
Provided historical information.

Source: IVCSD
E.3 District Profile
The community profile for the IVCSD is detailed in the following sections. Figure E-1 shows the District’s boundaries and the location of the District in the County. This map shows both the Fire District and the Water/Wastewater District. It also displays the elevations of IVCSD and the surrounding area.

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Plumas County IVCSD Annex E-2
Local Hazard Mitigation Plan Update
January 2026
Figure E-1 IVCSD Location and Elevation Map
E.3.1. Overview and Background
Indian Valley Community Services District (IVCSD) was formed in 1993 after a reorganization of Greenville Community Services District, Taylorsville Fire Protection District and Taylorsville County Service Area into a single district. The formation resolution does not identify which services the newly formed district is authorized to provide. The District continued providing services that were offered by its predecessor agencies.

The principal act that governs the District is the State of California Community Services District Law.

CSDs may potentially provide a wide array of services, including water supply, wastewater, solid waste, police and fire protection, street lighting and landscaping; airport, recreation and parks; mosquito abatement, library services; street maintenance and drainage services; ambulance service, utility undergrounding, transportation, abate graffiti, flood protection, weed abatement, hydroelectric power, among various other services.

IVCSD is located in the middle of northern Plumas County and encompasses the communities of Greenville, Crescent Mills, and Taylorsville. The nearest providers of similar services are Crescent Mills Fire Protection District and Indian Valley Parks and Recreation District, both of which IVCSD overlaps.

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Plumas County IVCSD Annex E-3
Local Hazard Mitigation Plan Update
January 2026
IVCSD provides retail water, fire protection, emergency medical, lighting, park and recreation, and wastewater treatment and collection services. Additionally, the District provides contract general manager services to the Indian Valley Ambulance Service Association through a joint powers agreement.

The District covers an area of approximately 18.6 square miles and has undergone five annexations since its formation. The latest annexation, in 1999, expanded the District to include the North Valley and Diamond Mountain areas.

E.4 Risk Assessment
As defined by FEMA, risk is a combination of hazard, vulnerability, and exposure. “It is the impact that a hazard would have on people, services, facilities, and structures in a community and refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.” The IVCSD risk assessment identifies and profiles relevant hazards and assesses the exposure of lives, property, infrastructure, and the environment to these hazards. The process allows for a better understanding of the District’s potential risk and vulnerability to hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

Building on the District Profile above, a risk assessment was performed for the District. This includes the following sections:
➢ E.4.1 Assets Inventory and Growth and Development Trends ➢ E.4.2 Hazard Identification
➢ E.4.3 Hazard Profiles and Vulnerability to Specific Hazards E.4.1. Assets Inventory and Growth and Development Trends This section provides an inventory of the IVCSD’s total assets potentially at risk to hazards and an overview of growth and development trends. This section is broken into two parts:
➢ Asset Inventory – The assets inventory identifies the IVCSD’s total assets, including the people and populations; structures; critical facilities and infrastructure; community lifelines; natural, historic, and cultural resources; and economic assets and community activities of value. This data is not hazard specific, but is representative of total assets within the District, potentially at risk to identified hazards as discussed in Section E.4.3 Hazard Profiles and Vulnerability to Specific Hazards. ➢ Growth and Development Trends – A discussion of growth and development trends in the District, both current and future, is presented.

Assets Inventory
The District’s asset inventory is detailed in the following sections:
➢ People and Populations
➢ Structures
➢ Critical Facilities and Infrastructure

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Plumas County IVCSD Annex E-4
Local Hazard Mitigation Plan Update
January 2026
➢ Community Lifelines
➢ Natural, Historic, and Cultural Resources
➢ Economic Assets and Community Activities of Value
A discussion of each of these assets follows and serves as the template for the asset discussion for each hazard in Section E.4.3.

People and Populations
The most important asset within any community are the people and populations that reside in the community. People and populations in the District include both District staff and workers as well as those populations located within District boundaries and are served by the District. This section includes an inventory of past and current populations of the District and also discusses vulnerable populations and underserved communities as a subsection of people and populations located within the District and potentially at risk to hazards. Information from the District and other sources as detailed below form the basis of this discussion.

Historic Population Trends and Current Population
The most important asset within any community are the people and populations that reside in the District.

Due to the Dixie Fire in 2021, staffing levels dropped from 15 volunteers to 10 as a result of the destruction of homes and loss of jobs. Over the past three years, however, the number of volunteers has doubled to 20, including a paid part-time Chief. Along with this, IVCSD employs 9 people and contracts 1 general manager. In addition to District staff, the District provides services to around 1,600 residents.

The District did note that there are vulnerable and underserved populations in the District. For elderly and disabled residents, limited mobility raises challenges during evacuation. Hazards disrupt local supportive services for elderly, disabled, and low-income residents that they depend on. There are programs that provide resources during disasters but connectivity and isolation can prevent access. Mental and emotional health can be severely affected by a disaster and the stress of starting over for an elderly person can be immense. Low income and under employed residents face significant barriers to recovery after a disaster especially if many rental properties are destroyed. Many low-income residents lack the resources to secure new housing or replace belongings. Residents with limited resources may find it overwhelming to navigate the complex process of applying for disaster aid. Affordable housing options may become sparse due to a disaster.

The California Department of Water Resources (DWR) has developed a mapping tool to assist in determining which communities meet the disadvantaged community's median household income definition.

DWR is not bound by the same law as the Plumas County Local Area Formation Commission (LAFCO) to define communities with a minimum threshold of 12 or more registered voters. Because income information is not available for this level of analysis, disadvantaged unincorporated communities with smaller populations that meet LAFCO's definition cannot be identified at this time. The DWR Mapping Tool is an interactive map application that allows users to overlay the following three US Census geographies as separate data layers—Census Place, Census Tract, and Census Block Group. The specific dataset used in the tool is the US Census American Community Survey Five-Year Data: 2016 - 2020. Only

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Plumas County IVCSD Annex E-5
Local Hazard Mitigation Plan Update
January 2026
those census geographies that meet the disadvantaged community (DAC) definition are shown on the map (i.e., only those with an annual median household income (MHI) that is less than 80 percent of the Statewide annual MHI). The statewide MHI for 2017-2021, according to Census Bureau data, is estimated at $84,097, and hence, the calculated threshold of $67,277 defines whether a community was identified as disadvantaged. Per the DWR Mapping Tool, the entirety of the IVCSD fire service area is considered a disadvantaged community.

Structures and Critical Facilities
This section considers the IVCSD’s assets at risk, with a focus on key District assets such as critical facilities and infrastructure, and other District assets and their values. With respect to District assets, the majority of these assets are considered critical facilities as defined for this Plan. Critical facilities are defined for this Plan as:

A critical facility is classified by the following categories: (1) Essential Services Facilities: (2) At-Risk Populations Facilities, and (3) Hazardous Materials Facilities.

Table E-2 lists critical facilities and other District assets identified by the District Planning Team as important to protect in the event of a disaster. IVCSD’s physical assets, valued at over $2.1 million, consist of structures and infrastructure to support the District’s operations.

Table E-2 IVCSD Critical Facilities and Infrastructure, and Other District Assets Name of Asset Facility Type Replacement Value Hazard Info Water Plant (building only) Crescent Mills Water $29,247 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Water Plant Equipment Crescent Mills Water $93,589 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Storage tank Water $292,465 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
pumphouse Water $12,869 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
Water treatment & equipment Greenville Water $250,000 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Concession stand & contents Park $35,096 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure

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Plumas County IVCSD Annex E-6
Local Hazard Mitigation Plan Update
January 2026
Name of Asset Facility Type Replacement Value Hazard Info Softball facility restrooms Park $52,000 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Community park Park $104,000 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
Pump Station Greenville Water $81,890 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Pump station Greenville Water $70,192 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Lift station Sewer $87,740 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
Leach field equipment Sewer $35,096 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Pool facility & contents Park $108,679 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Triangle park-small seating Park $4,679 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Sewer pond equipment Sewer $9,359 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Sewer pond equipment Sewer $23,397 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Lift station #1 Greenville Sewer $29,247 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Lift station #2 Greenville Sewer $40,945 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Lift station #3 Sewer $29,247 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
Office contents Water/Sewer/Park $11,699 Fire, earthquake, flood, landslide, mudslide debris
flow
Water tank Greenville Water $100,000 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
Round Valley Dam Water $100,000 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure

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Plumas County IVCSD Annex E-7
Local Hazard Mitigation Plan Update
January 2026
Name of Asset Facility Type Replacement Value Hazard Info APN 110330007 Greenville Vacant lot $0 Fire, earthquake, flood, landslide, mudslide debris
flow
4290 Nelson Street Taylorsville Fire Station $391,537 Fire, earthquake, flood, landslide, mudslide debris
flow, dam failure
6344 North Arm Road Taylorsville North Arm Fire
Station
$55,189 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
5497 Fir Fork Genesee Genesee Fire
Station
$58,803 Fire, earthquake, flood,
landslide, mudslide debris
flow, dam failure
Total $2,106,965.00
Source: IVCSD
Community Lifelines
Assessing the vulnerability of the IVCSD to natural hazards and disasters also involves reviewing and inventorying the community lifelines in place that could be affected. It is important to include these items in hazard discussions as the continuous operation of critical government and business functions is essential to human health and safety, property protection, and economic security. The importance of community lifelines is discussed below:
➢ Lifelines are the most fundamental services in the community that, when stabilized, enable all other aspects of society to function.
➢ FEMA has developed a method for objectives-based response that prioritizes the rapid stabilization of Community Lifelines after a disaster.
➢ The integrated network of assets, services, and capabilities that provide lifeline services are used dayto-day to support the recurring needs of the community and enable all other aspects of society to function.
➢ When disrupted, decisive intervention (e.g., rapid re-establishment or employment of contingency response solutions) is required to stabilize the incident.

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Plumas County IVCSD Annex E-8
Local Hazard Mitigation Plan Update
January 2026
It should be noted that these community lifelines are all in place and functional as part of regular government operations in the Plumas County Planning Area serving as a partnership between the city, local special districts and agencies, and Plumas County. Due to its more rural nature, there is an interplay in community lifelines between all jurisdictions in the County. Most all of the District’s community lifelines overlap with the Planning Area’s. It should also be noted that these lifelines collectively include many of the critical facilities and infrastructure assets inventoried for this LHMP, including those assets owned by the District. As such, specific information on these community lifelines in the District and how they may be affected by a hazard event or disaster are discussed in the Base Plan.

Natural, Historic, and Cultural Resources
Assessing the vulnerability of the IVCSD to natural hazards and disasters also involves inventorying the natural, historic, and cultural assets of the area. This step is important for the following reasons:
➢ Environmental and natural resources add to a community’s identity and quality of life. They also help the local economy through agriculture, tourism, and recreation. They support ecosystem services, such as clean air and water.
➢ Conserving the environment may help people mitigate risk. It can also protect sensitive habitats, develop parks and trails, and build the economy.
➢ The community may decide that these types of resources warrant a greater degree of protection due to their unique and irreplaceable nature and contribution to the overall economy. ➢ If these resources are impacted by a disaster, knowing so ahead of time allows for more prudent care in the immediate aftermath, when the potential for additional impacts are higher. ➢ The rules for reconstruction, restoration, rehabilitation, and/or replacement are often different for these types of designated resources.
➢ Natural resources can have beneficial functions that reduce the impacts of natural hazards, such as wetlands and riparian habitat, which help absorb and attenuate floodwaters.

Natural Resources
IVCSD has a variety of natural resources of value to the District. Specifically, there are critical water resources, abundant timber, and mineral deposits such as gold, limestone, copper, silver and iron within the boundaries of the District. These natural resources parallel that of Plumas County as a whole. Information can be found in Section 4.2.1 of the Base Plan.

Historic and Cultural Resources
IVCSD has a variety of historic and cultural resources of value to the District. Specifically, Ancient trails, archaeological sites, ceremonial & story sites, as well as Maidu artifacts. These historic and cultural resources parallel that of Plumas County as a whole. Information can be found in Section 4.2.1 of the Base Plan.

Economic Assets and Community Activities of Value
Assessing the vulnerability of the IVCSD to natural hazards and disasters also involves inventorying the economic assets and community activities of value in the District.

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Plumas County IVCSD Annex E-9
Local Hazard Mitigation Plan Update
January 2026
Economic Assets
After a disaster, economic resiliency is one of the major drivers of a speedy recovery. Each community has specific economic drivers. Economic assets for the County were discussed in Section 4.2.1 of the Base Plan and are assumed to be the same or similar for the District.

Population Trends and Projections
The Dixie Fire has led residents in various communities to mandatory evacuations and displacement of residents. Many have had to relocate to safer areas temporarily or permanently, impacting local population numbers and demographics. Communities within the IVCSD fire and EMS service boundaries, such as the town of Greenville and Indian Falls, are part of the communities that were forced to migrate. Therefore, the area may see minimal growth in the coming years, depending on the pace of recovery, housing availability, and economic opportunities.

Additionally, the Department of Finance (DOF) projects a 30 percent decline in Plumas County's population from 2024 (18,593) to 2060 (13,025). This represents an average annual growth rate (AAGR) of negative one percent, indicating an approximate one percent annual population decline from 2024 through 2060.

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Plumas County IVCSD Annex E-10
Local Hazard Mitigation Plan Update
January 2026
the Dixie Fire. The economic future largely depends on rebuilding efforts, tourism, and recreation. The District is currently rebuilding the Greenville fire station. This is being done after the station was destroyed in the 2021 Dixie Fire. The new facility will be both an IVCSD Fire Station and a County Sheriff Substation. This is the only new development currently planned by the District. With respect to future development within its service area, new development and rebuilds continue with recovery efforts ongoing in the aftermath of the Dixie Fire. The District has no control over where future development occurs, it reacts to the development by providing increase (or decreased) services.

E.4.2. Hazard Identification
The IVCSD identified the hazards that affect the District and summarized their location, extent, likelihood of future occurrence, potential magnitude, and significance (or priority of a hazard) specific to the District.

Note: Those hazards identified as a high or medium significance in Table E-3 are considered priority hazards for mitigation planning. Those hazards that occur infrequently or have little or no impact in the District were determined to be of low significance and not considered a priority hazard to the District.

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Plumas County IVCSD Annex E-11
Local Hazard Mitigation Plan Update
January 2026
Table E-3 IVCSD—Hazard Identification Assessment
Hazard
Geographic
Extent
Likelihood of
Future
Occurrences
Magnitude/
Severity Significance
Climate
Change
Influence
Agricultural Hazards (severe
weather/pests/invasive species)
Extensive Highly Likely Limited Low Medium
Climate Change Extensive Likely Critical Low –
Dam Failure Extensive Occasional Critical High Medium
Drought & Water shortage (w/ tree
mortality)
Extensive Likely Limited Medium High
Earthquake (w/subhazards) Extensive Likely Catastrophic High Low Floods: 1%/0.2% annual chance (w/
levee failure)
Significant Occasional Catastrophic High Medium
Floods: Localized Stormwater Significant Highly Likely Limited Medium Medium Hazardous Materials Transport Significant Occasional Critical Low – Landslide, Mudslide, Debris Flow Significant Likely Limited High Medium Severe Weather: Extreme Cold, Freeze,
and Snow
Extensive Likely Limited Low Medium
Severe Weather: Extreme Heat Extensive Highly Likely Negligible Low High Severe Weather: Heavy Rains and Storms
(Hail, Lightning)
Extensive Highly Likely Limited Medium Medium
Severe Weather: High Winds and
Tornadoes
Extensive Occasional Limited Low Medium
Volcano Extensive Unlikely Catastrophic Low Low
Wildfire (w/smoke and air quality) Extensive Highly Likely Catastrophic High Medium Geographic Extent
Limited: Less than 10% of planning area
Significant: 10-50% of planning area
Extensive: 50-100% of planning area
Likelihood of Future Occurrences
Highly Likely: Near 100% chance of
occurrence in next year, or happens
every year.

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

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

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

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Plumas County IVCSD Annex E-12
Local Hazard Mitigation Plan Update
January 2026
E.4.3. Hazard Profiles and Vulnerability to Specific Hazards This section includes the hazard profiles and vulnerability assessment for hazards ranked of medium or high significance specific to the IVCSD (as identified in the Significance column of Table E-3). This section focuses on where and how the District is affected by their priority hazards. Chapter 4 of the Base Plan provides more detailed information about these hazards and their impacts on the Plumas County Planning Area. Methodologies for evaluating vulnerabilities and calculating loss estimates are the same as those described in Section 4.2 of the Base Plan.

After this classification, a general discussion of hazard vulnerabilities occurs. This is done in the following format:

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Plumas County IVCSD Annex E-13
Local Hazard Mitigation Plan Update
January 2026
➢ Vulnerability Overview – A general discussion of the hazard vulnerability and related issues is detailed here.
➢ Local Concerns – This includes District provided information on how the District is uniquely affected by or vulnerable to each hazard.
➢ Assets at Risk – A discussion of the assets at risk follows, presented in the same order as in Section E.4.1 above, with a few exceptions. This includes sections on: People and Populations; Structures and Critical Facilities and Infrastructure; and Natural, Historic, and Cultural Resources. These are discussed in specific terms for mapped hazards, and in more general terms for those hazards that are unmapped. Sections on Community Lifelines and Economic Assets and Community Activities of Value are not included in the Sections below, as they are common to all jurisdictions and are fully covered in Section E.4.1 above and Chapter 4 of the Base Plan.
➢ Impacts – A discussion on hazard impacts follows. Impacts describe how each hazard can affect the District, its assets, and the ability to provide continued and reliable services. The type and severity of impacts reflect both the potential magnitude of the hazard and the vulnerability of the asset. ➢ Future Conditions/Future Development – A discussion of how future conditions and future development will affect or influence each hazard over time is also included. This considers both new District assets and improvements as well as any changes in service area.

Electric power disruptions can be generally grouped into two categories: intentional and unintentional.

More information on types of power disruptions can be found in Section 4.3 of the Base Plan.

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Plumas County IVCSD Annex E-14
Local Hazard Mitigation Plan Update
January 2026
hazards from causing a wildfire. By stopping ignitions, it helps prevent wildfires from starting and spreading. According to PG&E, if ignitions occur, the size of fires can be much smaller due to EPSS. In 2022, there was a 99% decrease in acres impacted by ignitions (as measured by fire size from electric distribution equipment (compared to the 2018-2020 average). This decrease occurred despite dry conditions.

Local Concerns
The District noted that there have been no Power Outages, including those associated with PSPS events, that have affected them.

Dam Failure
Likelihood of Future Occurrence–Occasional
Vulnerability–Extremely High
Hazard Profile
Dams are manmade structures built for a variety of uses including flood protection, power generation, agriculture, water supply, and recreation. When dams are constructed for flood protection, they are usually engineered to withstand a flood with a computed risk of occurrence. For example, a dam may be designed to contain a flood at a location on a stream that has a certain probability of occurring in any given year. If prolonged periods of rainfall and flooding occur that exceed the design requirements, that structure may be overtopped or fail. Overtopping is the primary cause of earthen dam failure in the United States.

Dam failure is a natural disaster from two perspectives. First, the inundation from released waters resulting from dam failure is related to naturally occurring floodwaters. Second, a total dam failure would most probably happen as a consequence of the natural disaster triggering the event, such as an earthquake.

Bidwell Lake Dam impounds Round Valley Reservoir in Greenville, CA (Plumas County). It is owned by the Indian Valley Community Services District. It is a high hazard dam. The earthen dam was built in 1865. The dam is 325 feet long and 35 feet high. It impounds 5,975 acre feet of water. It was repaired in 2018 as a result of the 2017 January-February flood event. The reservoir is used as the backup water system for the residents of the community of Greenville. The water from Bidwell Dam flows into North Creek, then Wolf Creek, then Indian Creek, and then the Feather River.

The spillway consists of two concrete walls that direct water over the crest of a concrete monolith built into bedrock. The spillway toe is 11.5 feet below its crest. The spillway flashboards are 20 inches long and aligned at an angle from the vertical plane. A valve in the spillway can be used to release water. The spillway capacity is estimated to be approximately 3,000 cfs when the water level in the reservoir is at the dam crest and the flashboards are not installed. There are no other outlets. The downstream channel capacity is approximately 257 cfs.

Per DSOD, there are no critical appurtenant structures. There are no upstream or downstream dams.

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Plumas County IVCSD Annex E-15
Local Hazard Mitigation Plan Update
January 2026
If the dam were to fail, the flood waters would follow Wolf Creek downhill to the city of Greenville, arriving in 30 minutes. The waters would spread out over the community and the downstream agricultural land at depths of mostly less than 5 feet. Within Greenville, the two schools and the Feather River Hospital would be inundated. Highway 89 would be flooded at two points Location and Extent
An inventory map of dams located within Plumas County was shown in Section 4.3.8 in the Base Plan.

Dams with an inundation area within the IVCSD are shown on Figure E-2. This includes 3 high hazard dams: Antelope, Bidwell Lake (owned by ICCSD), and Silver Lake.

Note: There are no extremely high hazard dams that intersect the District. As such, no maps or tabular analysis are provided below.

There is no scale with which to measure dam failure. However, FEMA and CA DWR Division of Safety of Dams (DSOD) assign hazard potential classifications to dams within the State that provides information on the potential impact should a dam fail. The following two factors are considered when assigning hazard ratings: existing land use and land use controls (zoning) downstream of the dam. FEMA categorizes the downstream hazard potential into three categories in increasing severity: Low, Significant, and High.

DSOD adds a fourth category of Extremely High. Dams are classified in these four categories that identify the potential hazard to life and property. These were discussed in more detail in Section 4.3.8 of the Base Plan.

While a dam may fill slowly with runoff from winter storms, a dam break has a very quick speed of onset.

The duration of dam failure is generally not long – only as long as it takes to empty the reservoir of water the dam held back. For dam overtopping, the speed of onset is somewhat slower than that of a dam break, and the duration is longer (as evidenced in the 2017 Oroville Dam spillway event). The District would be affected for as long as the flood waters from the dam failure took to drain downstream.

Geographic flood extent from the DSOD dam inundation areas is shown on Figure E-2, as well as in Table E-4 for both the Fire District and the Water/Wastewater District.

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Plumas County IVCSD Annex E-16
Local Hazard Mitigation Plan Update
January 2026
Figure E-2 IVCSD – High Hazard Dam Inundation Areas
Table E-4 IVCSD – Dam Inundation Areas Geographical Extents Dam
Inundation
Area
Total Acres % of Total
Acres
Improved
Acres
% of Total
Improved
Acres
Unimproved
Acres
% of Total
Unimproved
Acres
Fire District
Antelope 1,104 6% 188 3% 916 8%
Bidwell Lake 231 1% 50 1% 181 2%
Water/Wastewater District
Antelope 1,951 13% 696 15% 1,254 13%
Bidwell Lake 1,227 8% 229 5% 998 10%
Silver Lake 2 0.02% 2 0.05% - 0%
Source: Cal OES, DSOD, Plumas County GIS

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Plumas County IVCSD Annex E-17
Local Hazard Mitigation Plan Update
January 2026
Past Occurrences
Disaster Declaration History
There have been no state or federal disaster declarations for dam failure in Plumas County.

NCDC Events
The NCDC does not contain any dam failure events for Plumas County.

IVCSD Events
There have been no past dam failure events in the District since its inception. There was a large storm event in 2017 where the Bidwell Lake dam and Round Valley Reservoir were impacted. A FEMA grant helped to pay for repairs. That grant application noted that during the declared incident period, February 1 through 23, 2017, Plumas County, CA, experienced severe rainstorms and flooding. As a direct result of the incident, some of the large rocks from the IVCSD Bidwell Dam Round Valley Reservoir Spillway were washed out and a portion of the existing 4-in. HDPE water pipe (300 ft. long) was damaged.

Climate Change and Dam Failure
It is likely that climate change will increase the chance of future occurrence as well as future impacts associated with dam failure. More information on future impacts to the District can be found below and in the Future Conditions/Future Development section of the Vulnerability Assessment below.

The 2023 California State Hazard Mitigation Plan noted that modeling described in California’s Fourth Climate Change Assessment projects less frequent but more extreme daily precipitation. Year-to-year precipitation will become more volatile, and the number of dry years will increase by mid-century. As the climate continues to warm, atmospheric rivers will carry more moisture, and extreme precipitation may increase. Climate model projections show a tendency for the northern part of the State to become wetter.

Increases in both precipitation and heat causing snow melt in areas upstream of dams could increase the potential for dam failure and uncontrolled releases in Plumas County and the District.

Vulnerability to Dam Failure
The vulnerability of the District to dam failure flooding would vary depending on which dam fails and the nature and extent of the dam failure and associated flooding. An assessment of a community’s vulnerability to dam failure begins with an understanding of local exposure to dam failure. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

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Plumas County IVCSD Annex E-18
Local Hazard Mitigation Plan Update
January 2026
Dam failure is the foremost concern for the District. The Round Valley Reservoir is impounded by Bidwell Lake dam. The District owns this dam. There are concerns regarding earthquakes causing an already weak and aging dam to fail. There are additional concerns about the dam failing due to the age and condition of the dam. In the event of a dam failure, the community of Greenville could face significant flooding and catastrophic casualties. To mitigate this hazard, the District either needs to repair or rebuild this dam and make sure it is retrofitted and upgraded.

The Indian Valley Community Service District was critically impacted by the 2021 Dixie Fire. The building that housed their physical records of the dam was destroyed. The District also experienced staff turnover in the subsequent years, resulting in the loss of institutional knowledge.

Assets at Risk
Assets at risk from this hazard include people and populations ; structures and critical facilities; and natural, historic, and cultural resources. These are discussed in the following sections.

People and Populations
All people and populations (including both District staff and District residents) located in dam inundation areas are vulnerable to dam failure. Certain vulnerable populations may be at increased risk to dam failure, especially during a large event with minimal advance notice. These vulnerable populations may include:
the unhoused, those with limited mobility, and those that lack the resources to leave the area.

The District’s ability to operate may be compromised during an event limiting their ability to provide services to the populations in their service area. For example, water and wastewater services may be cut off during and after an event until the District can get systems functioning and back on line.

Structures and Critical Facilities and Infrastructure
Many structures and critical facilities and infrastructure in the District have some measure of risk to dam failure. Dam failure flooding can affect the built environment of the District. Structures in dam inundation areas are at risk and depending on flood depths, can range from slight damage to totally inundated. The District noted that the dam as well as most of the assets on Table E-2 would be at risk to dam failure.

Natural, Historic, and Cultural Resources
A major dam failure event and associated flooding could have a devastating impact on the District. Large flood events can affect all natural, historic, and cultural resources that lie in the dam inundation areas. There are a number of ways floodwaters associated with a dam failure event can impact natural resources and the environment: Wildlife habitats can be destroyed by floodwaters. Contaminated floodwater can pollute rivers and habitats. Silt and sediment can destroy natural areas. Riverbanks and natural levées can be eliminated as rivers reach bankfull capacity. Rivers can be widened, and deposition can increase downstream. Trees can be uprooted by high-velocity water flow. Plants that survive the initial flood may die due to being inundated with water. Historic and cultural resources may also be affected. Generally, the impacts are associated with damage to these structures within the inundated areas, but other cultural

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Plumas County IVCSD Annex E-19
Local Hazard Mitigation Plan Update
January 2026
resources such as those associated with Native Americans and old tribal areas can also be disturbed, damaged, and lost during extreme dam failure flood events.

Impacts from Dam Failure
Impacts to the District from dam failure flooding could be extensive and widespread and include loss of life and injury, flooding and damage to property and structures, damage to critical facilities and infrastructure, loss of natural resources, and all other flood related impacts. Additionally, mass evacuations may be necessary and compounded by impacts to transportation systems and infrastructure. Economic losses to the District and Plumas County Planning Area can also be significant.

Other impacts associated with dam failure include landslides, bank erosion, and destruction of habitat. Dam failures can cause downstream flooding and can transport large volumes of sediment and debris and contaminants from the floodwaters. Other environmental impacts can include contamination from septic system failures and releases of contaminants from hazardous materials facilities, contamination of potable water supplies; changes in configurations of streams; loss of wildlife habitats; and degradation of wetlands.

A large dam failure event could have significant and catastrophic impacts.

Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected in the future by climate change (which was discussed in the Climate Change and Dam Failure discussion above), changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. These are discussed in the Future Conditions/Future Development discussion below.

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Plumas County IVCSD Annex E-20
Local Hazard Mitigation Plan Update
January 2026
aftermath of the Dixie Fire. The District noted that it has no control over land use and development within its service area. With limited future growth and development occurring, the vulnerability of the District to dam failure is unlikely to change.

Future Development
Land use planning should be proactive to address future hazard conditions. The District is currently rebuilding the Greenville fire station that was destroyed in the 2021 Dixie Fire. This is the only new development currently planned by the District. With respect to future development within its service area, new development and rebuilds continue with recovery efforts ongoing in the aftermath of the Dixie Fire.

Future dam failure events may occur in the District. Locating new development, structures, and critical facilities and infrastructure within or near areas of dam failure risk may put additional development at risk.

Although new growth and development may fall in the area flooded by a dam failure, given the limited potential of total dam failure and the large area that a dam failure would affect, development in the dam inundation area may continue to occur.

Drought & Water Shortage (w/tree mortality)
Likelihood of Future Occurrence–Likely
Vulnerability–Medium
Hazard Profile
Drought and water shortage are complex issues involving many factors—it occurs when a normal amount of precipitation and snow is not available to satisfy an area’s usual water-consuming activities. Drought can often be defined regionally based on its effects. Drought is different than many of the other natural hazards in that it is not a distinct event and usually has a slow onset. Drought can severely impact a region both physically and economically. Drought affects different sectors in different ways and with varying intensities. Adequate water supply is the most significant issue and is critical for agriculture, manufacturing, tourism, recreation, and commercial and domestic use. Drought has also affected tree mortality in the area in the past. As the population in the area continues to grow, so will the demand for water.

Tree Mortality and Drought
One of the secondary hazards of drought in the Plumas County Planning Area, that can also affect IVCSD, is the increased risk to trees from beetle kill and other insects, pathogens and parasites, and other tree mortality and die back issues. Drought weakens trees and makes them more susceptible to insect infestation and other pathogens. Insects, such as bark beetles and others, frequently attack trees weakened by drought, disease, injuries, or other factors that may stress the tree. These insects and other pathogens can contribute to the decline and eventual death of trees throughout the District. The tree mortality and dieback problems are a high priority because of the issue of hazardous trees and an increased wildfire hazard. In addition to an increase in wildfire fuels, hazardous trees can fall onto structures causing damage and a result in a reduction on the tree canopy within the District that provides relief during extreme heat days.

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Plumas County IVCSD Annex E-21
Local Hazard Mitigation Plan Update
January 2026
Location and Extent
Drought and water shortage are regional phenomenon. The whole of the District and County is at risk. The US Drought Monitor categorizes drought conditions with the following scale:
➢ None
➢ D0 – Abnormally dry
➢ D1 – Moderate Drought
➢ D2 – Severe Drought
➢ D3 – Extreme Drought
➢ D4 – Exceptional Drought
Drought has a slow speed of onset and a variable duration. Drought can last for a short period of time (which does not usually affect water shortages) or for longer periods (which may challenge water supplies).

Should a drought last for a long period of time, water shortage becomes a larger issue.

The Plumas County Planning Area, including the District, has been in and out of drought since 2014. Over the last six years since the 2019/2020 LHMPs, drought conditions have ranged from none to exceptional.

Drought conditions are expected to continue to be cyclical in nature depending on the year. Current drought conditions in the District are shown in Section 4.3.9 of the Base Plan.

Past Occurrences
Disaster Declaration History
There have been 2 state and 1 federal disaster declarations for Plumas County. This can be seen in Table E-5. Additionally, there have been 16 USDA Secretarial Disaster Declarations from drought in the County since 2012.

Table E-5 Plumas County –State and Federal Drought Disaster Declarations 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Drought 2 1976, 2015 1 1977
Source: Cal OES, FEMA
NCDC Events
There have been 2 NCDC drought events in Plumas County since 1993. These most likely had some impact on the District.

IVCSD Events
Based on historical information, the occurrence of drought in California, including the IVCSD, is cyclical, driven by weather patterns. Section 4.3.9 of the Base Plan notes that five droughts have occurred in the past 86 years that likely affected the District to varying degrees. Drought has occurred in the past and will occur in the future.

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Plumas County IVCSD Annex E-22
Local Hazard Mitigation Plan Update
January 2026
Climate Change and Drought and Water Shortage
It is likely that climate change will increase the chance of future occurrence as well as future impacts associated with drought and water shortage. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Cal Adapt scenarios for modeled future drought scenarios were shown in Section 4.3.9 of the Base Plan.

Vulnerability to Drought and Water Shortage
Based on historical information, the occurrence of drought and water shortage in California, including the District, is cyclical, driven by weather patterns. Drought has occurred in the past and will occur in the future. Periods of actual drought with adverse impacts can vary in duration, and the period between droughts can be extended. Although an area may be under an extended dry period, determining when it becomes a drought is based on impacts to individual water users. The vulnerability of the IVCSD to drought may vary and include reduction in water supply, water quality issues, impacts to natural resources, and an increase in dry fuels and tree dieback.

Ground water supply is source water for the Water District. The distribution system is fed by one main line into town from the treatment plant. Loss of electricity could affect redundancy to supply of maximum demands of system.

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Plumas County IVCSD Annex E-23
Local Hazard Mitigation Plan Update
January 2026
2019 Greenville Water System Planning Report noted that over recent years, the Greenville water system has struggled with efficiency in that the District only sells about 50% of the water that is produced. The 50% water loss is thought to be due to due to leaks io the distribution system and other inefficiencies such as meter inaccuracies.

Chief concerns to the District include wildfire, water shortage and long-term ecosystem damage. Hazard mitigation measures can be implemented with extra water storage. There are significant number of large trees that were lost in recent drought years. This was primarily due to drought stress and the Dixie Fire.

The economy in the area has been reshaped by the Dixie Fire. The economic future largely depends on rebuilding efforts, tourism, and recreation. Along with the cost of rebuilding, disasters disrupt the customer base. This impacts not only the rebuilding but also the replacement of aging infrastructure. Funding limitations are of high concern.

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Plumas County IVCSD Annex E-24
Local Hazard Mitigation Plan Update
January 2026
The District noted that drought will likely not directly affect District facilities, but the District is concerned about drought increasing the wildfire hazard. All of the facilities listed in Table E-2 with wildfire as a concern could be affected by drought exacerbated wildfire.

Natural, Historic, and Cultural Resources
Drought and water shortage can have a significant impact on natural resources. Water levels in reservoirs and lakes may be reduced and a loss of wetlands and marsh areas may occur. Severe drought conditions can contribute to an increase in erosion of soils and lead to poor soil quality. Further, all of the trees in the District are at risk to drought impacts and a reduction in water supply. These trees provide a wealth of social and environmental benefits to District residents and visitors, from shade and beauty to air quality, carbon reduction and stormwater management. Drought can devastate crops and dry out pastures, dry out forests and critical habitat areas, and reduce food and water available for wildlife and livestock.

Additionally, drought conditions can also cause soil to compact and not absorb water well, potentially making an area more susceptible to flooding. It is unlikely that drought and water shortage would have a significant impact on historic and cultural resources in the District.

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Plumas County IVCSD Annex E-25
Local Hazard Mitigation Plan Update
January 2026
Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the IVCSD include the following:
➢ Climate change is likely to exacerbate future drought conditions and associated impacts and vulnerability of the District to drought and water shortage. ➢ Population projections within the District’s service area show the population to be slightly declining. It is unknown how population patterns and demographics will change in the near future. The District may add staff, but this number would be relatively small. The District noted that it has no control over population changes within its service area. With no notable changes in populations numbers and makeup, the vulnerability of the District to a dam failure is unlikely to change. ➢ Changes in land use and development within the District’s service area are expected to be limited in the near future and thus are not likely to affect dam failure impacts to the District. The District is currently rebuilding its Greenville Fire Station. No other development is currently being planned by the District. New development continues in the District’s service area with recovery efforts ongoing in the aftermath of the Dixie Fire. The District noted that it has no control over land use and development within its service area. With limited future growth and development occurring, the vulnerability of the District to this hazard is unlikely to change.

The District has access to large quantities of water through its existing groundwater supplies. However, future population growth and development in the District will add additional pressure to the District as a water company during periods of drought and water shortage. The District should conduct water supply planning to ensure a continued water supply to address future development and future drought conditions.

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Plumas County IVCSD Annex E-26
Local Hazard Mitigation Plan Update
January 2026
fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction.

Location and Extent
Since earthquakes are regional events, the whole of the District is at risk to earthquake. The IVCSD, Plumas County, and surrounding areas have some level of risk from seismic and geologic hazards. Faults in and around the District are shown in Section 4.3.10 of the Base Plan. These include the Almanor Fault, Butt Creek Fault Zone, the Mohawk Valley Fault, and others that traverse the County. The Indian Valley Fault is also considered an active fault located within the County. A significant seismic event on any of these major faults could cause damage in the IVCSD.

Past Occurrences
Disaster Declaration History
There has been no state or federal disaster declarations in Plumas County from earthquake.

NCDC Events
The NCDC does not track earthquake events.

IVCSD Events
As shown in the Base Plan, no disaster declarations have occurred in the County due to earthquake. The District did note an earthquake at Lake Almanor May 11, 2023, affected a large portion of Northern California. The immediate area near Lake Almanor experienced the highest intensity such as Greenville & Chester. The foothills, greater Sacramento area, Chico, Susanville, & Nevada county also felt shaking. In the District, there was no major structural damage reported. Roads were damaged. Businesses had minor damage to inventory such as inventory falling from shelves and breaking.

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Plumas County IVCSD Annex E-27
Local Hazard Mitigation Plan Update
January 2026
Climate Change and Earthquake
Climate change is unlikely to increase earthquake frequency or strength. More information on future impacts can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Vulnerability to Earthquake
The combination of plate tectonics and associated California coastal mountain range building geology generates earthquakes as a result of the periodic release of tectonic stresses Earthquake vulnerability is primarily based on population and the built environment. More urban areas in high seismic hazard zones are the most vulnerable, while uninhabited areas are less vulnerable. The primary impacts of concern are life safety and property damage. Although several faults are in and near the Plumas County Planning Area, seismic hazard mapping indicates that the District has low to moderate seismic hazard potential. There is the potential for the District and Plumas County Planning Area to be subject to some level of moderate seismic shaking. Some degree of structural damage due to stronger seismic shaking could be expected.

To further evaluate the potential vulnerability of the County Planning Area including the District to earthquake shaking events, four Hazus scenarios were developed for this LHMP (Great Valley Fault 6.53, Hat Creek/McArthur/Mayfield 7.29, Honey Lake 7.03, Warm Springs Valley 6.92). More information on the Hazus scenarios and how the Plumas County Planning Area, including areas covered by the District, may be affected is included in Section 4.3.10 of the Base Plan.

This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

The District is concerned about a dam failure being caused by an earthquake. The District also has substantial above ground infrastructure that is well built, but would be at risk to a large earthquake. In addition, the District has below ground piping that would be at risk from earthquakes. The District noted that it can help mitigate by integrating seismic resilience in infrastructure, retrofitting existing infrastructure, such as the dam at Round Valley Reservoir and ensuring that district facilities are hardened and the community and District are prepared for future events.

The District also has concerns about other cascading issues from earthquake such as earthquake-induced landslides, liquefaction, and wildfire risk. If these other events were to occur, the operational resilience of an already stressed district would cause delays in emergency responses, additional trauma to residents impacted, and increased uncertainty.

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Plumas County IVCSD Annex E-28
Local Hazard Mitigation Plan Update
January 2026
Assets at Risk
Assets at risk from this hazard include people and populations; structures and critical facilities; and natural, historic, and cultural resources. These are discussed in the following sections.

People and Populations
All people and populations (both District staff and those residing in the District Service Area) are at risk from earthquake shaking and associated hazards. The greatest risk to people and populations from earthquake is death and injury. More information on people and populations at risk to earthquake shaking events can be seen in the Hazus scenarios developed for this LHMP. More information on the Hazus scenarios and how the County and District may be affected is included in Section 4.3.10 of the Base Plan.

Structures and Critical Facilities and Infrastructure
All structures and critical facilities and infrastructure in the District are vulnerable to earthquakes, depending on the severity and location of the event. The Hazus scenarios conducted for the entire Plumas County Planning Area show how structures and critical facilities and infrastructure may be affected. The District noted (in Table E-2) that all District assets are at risk from a damaging earthquake.

Impacts from Earthquake
Earthquakes can strike without warning and cause dramatic changes to the landscape of an area that can have devastating impacts on the built environment. The greatest impact is to life safety of the IVCSD staff, residents, and visitors. Other impacts to the District could include damages to infrastructure such as roads, and bridges; damages and loss of services to utilities and critical infrastructure, including those related to gas, power, water, wastewater and communication systems; damages to structures and other development; and possible loss of life and injuries.

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Plumas County IVCSD Annex E-29
Local Hazard Mitigation Plan Update
January 2026
Earthquakes can also cause failure of dams, levees, and reservoirs. Facilities and land downslope from dams or water reservoirs might be subject to flooding, if the dams, reservoirs, or other flood control structures fail as a result of an earthquake. The District has locations with significant flood risk that include facilities downslope from dams or reservoirs that could be affected by a significant earthquake event.

Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;
➢ Structural and property damage;
➢ Disruption of and damage to public infrastructure, utilities, and services; ➢ Damage to roads/bridges resulting in loss of mobility; ➢ Significant economic impact (jobs, sales, tax revenue) to the community.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the IVCSD include the following:
➢ As discussed in the hazard profile section, climate change is not anticipated to affect this hazard over time.
➢ Population projections within the District’s service area show the population to be slightly declining. It is unknown how population patterns and demographics will change in the near future. The District may add staff, but this number would be relatively small. The District noted that it has no control over population changes within its service area. With no notable changes in populations numbers and makeup, the vulnerability of the District to a dam failure is unlikely to change. ➢ Changes in land use and development within the District’s service area are expected to be limited in the near future and thus are not likely to affect dam failure impacts to the District. The District is currently rebuilding its Greenville Fire Station. No other development is currently being planned by the District. New development continues in the District’s service area with recovery efforts ongoing in the aftermath of the Dixie Fire. The District noted that it has no control over land use and development within its service area. With limited future growth and development occurring, the vulnerability of the District to this hazard is unlikely to change.

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Plumas County IVCSD Annex E-30
Local Hazard Mitigation Plan Update
January 2026
Future Development
Land use planning should be proactive to address future hazard conditions. The District is currently rebuilding the Greenville fire station that was destroyed in the 2021 Dixie Fire. This is the only new development currently planned by the District. With respect to future development within its service area, new development and rebuilds continue with recovery efforts ongoing in the aftermath of the Dixie Fire.

Although new growth and development would fall in the area affected by earthquake, given the limited chance of major earthquake and the building codes in effect, development in areas prone to earthquakes will continue to occur. The County enforces the California Building Code, which mandates construction techniques that minimize seismic hazards. Future development in the District is subject to these building codes and land use planning.

Flood: 1%/0.2% Annual Chance (w/Levee Failure)
Likelihood of Future Occurrence–Occasional (1%)/Unlikely (0.2%) Vulnerability–High
Hazard Profile
This hazard analyzes the FEMA DFIRM 1% and 0.2% annual chance floods. These tend to be the larger floods that can occur in the District and have caused damage in the past. Flooding can be a significant problem in the District. Historically, the District has been at risk to flooding primarily during the winter and spring months when river systems in the District swell with heavy rainfall and snowmelt runoff. The District has also been at risk during atmospheric river flood events. Normally, storm floodwaters are kept within defined limits by a variety of storm drainage and flood control measures (like levees) located throughout the Plumas County Planning Area and the IVCSD. Occasionally, extended heavy rains result in floodwaters that exceed normal high-water boundaries and cause damage. Flooding has occurred both within the 1% annual chance floodplains and in other localized areas in the District. Levee failure flooding is also an issue in the District (though a minor one).

Location and Extent
The IVCSD has areas located in the 1% annual chance flood zone. This is seen in Figure E-3. The District also has a small area within its boundaries that is protected by a levee (though the levee is not certified by FEMA as protecting against the 1% annual chance flood). This can be seen in Figure E-4.

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Plumas County IVCSD Annex E-31
Local Hazard Mitigation Plan Update
January 2026
Figure E-3 IVCSD – FEMA DFIRM Flood Zones

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Plumas County IVCSD Annex E-32
Local Hazard Mitigation Plan Update
January 2026
Figure E-4 IVCSD – FEMA DFIRM Flood Zones with Leveed Area Table E-6 details the DFIRM mapped flood zones located within the District.

Table E-6 IVCSD – DFIRM Flood Hazard Zones
Flood Zone Description Present in District
A 1% annual chance flooding: No base flood elevations provided X AE 1% annual chance flooding: Base flood elevations provided AE Regulatory Floodway 1% annual chance flood: Regulatory floodway; Base flood elevations provided
AH 1% annual chance flood areas of shallow flooding between one to three feet deep. Regulatory floodway; Base flood elevations provided
Shaded X 0.2% annual chance flooding: The areas between the limits of the 1% annual chance flood and the 0.2-percent-annual-chance (or 500-year) flood
X
Zone D Areas with possible but undetermined flood hazards. No flood hazard analysis has been conducted.

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Plumas County IVCSD Annex E-33
Local Hazard Mitigation Plan Update
January 2026
Flood Zone Description Present in District
X (unshaded) Area of minimal flood hazard X
Source: FEMA DFIRM 03/02/2005
Additionally, flood extents can generally be measured in volume, velocity, and depths of flooding.

Expected flood depths in the District vary, depending on the nature and extent of a flood event; specific depths are unknown. Flood durations in the District tend to be short to medium term, until either the storm drainage system can catch up or flood waters move downstream. Flooding in the District tends to have a shorter speed of onset, due to the amount of water that flows through the District.

Geographical flood extents for the District from the FEMA DFIRMs are shown in Table E-7.

Table E-7 IVCSD – Geographical DFIRM Flood Zone Extents Jurisdiction/
Flood Zone
Total Acres % of Total
Acres
Improved
Acres
% of Total
Improved
Acres
Unimproved
Acres
% of Total
Unimproved
Acres
Fire District
1% Annual
Chance Flood
Hazard
1,319 8% 254 5% 1,065 9%

0.2% Annual
Chance Flood
Hazard
0 0% 0 0% 0 0%
Other Areas 1,639 9% 565 10% 1,074 9%
Total 2,958 17% 819 15% 2,139 18%
Water/Wastewater District
1% Annual
Chance Flood
Hazard
3,287 19% 1,360 25% 1,927 16%

0.2% Annual
Chance Flood
Hazard
30 0.2% 5 0.1% 25 0.2%
Other Areas 11,247 64% 3,306 60% 7,941 66%
Total 14,564 83% 4,671 85% 9,893 82%
Grand Total 17,522 100% 5,490 100% 12,032 100%
Source: FEMA DFIRM 03/02/2005
Chester Area Levees and Flood Control Structures
A search of the National Levee Database identified the Plumas County Levee 2 (near Greenville) as shown on Figure E-5. This is the same levee shown on Figure E-5 above. This levee is not certified as providing protection from the 1% annual chance or other flood. As such, no mapping of these areas is included in the Vulnerability Assessment below as part of the DFIRM analysis as no X-protected by levee flood zones are included in that dataset.

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Plumas County IVCSD Annex E-34
Local Hazard Mitigation Plan Update
January 2026
Figure E-5 Plumas County –Levee 2
Source: National Levee Database
Past Occurrences
Disaster Declaration History
A list of state and federal disaster declarations for Plumas County from flooding is shown on Table E-8.

These events also likely affected the District to some degree.

Table E-8 Plumas County – State and Federal Disaster Declarations from Flood 1950-2025 Disaster Type State Declarations Federal Declarations
Count Years Count Years
Flood (including heavy
rain and storm)
22 1950, 1955, 1958 (twice), 1964,
1963, 1964, 1969, 1970 1980,
1986, 1993, 1992*, 1995
(twice*), 1996, 1997, 2006, 2017
(twice*), 2023 (twice*)
19 1950, 1955, 1958 (twice), 1963,
1964, 1969, 1970, 1986, 1992
(twice), 1995 (twice), 1997,
2006*, 2017 (twice*), 2023
(twice*)
Source: Cal OES, FEMA
*included a landslide component
NCDC Events
The NCDC tracks flooding events for the County. Events have been tracked for flooding since 1993.

Plumas County has seen 15 events. Depending on the location, these events most likely had some impact on the District.

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Plumas County IVCSD Annex E-35
Local Hazard Mitigation Plan Update
January 2026
IVCSD Events
The District noted that the following events had affects or damages to the District:

April 2023 – Spring snowmelt cased increased waterflow. The Indian Creek overflowed and various roads in the District became submerged.

October 2021 – A bomb cyclone brought heavy rain to the region.

August 2020 – A heavy rain prompted a flash flood warning.

January 2017 – Plumas County experienced heavy rainfall and snowmelt during the incident period of January 3 - 12, 2017, which resulted in roadway flooding and washout, property flooding, and wastewater lift station damages. As a direct result of the storm, IVCSD sustained generator damages at two distinct lift stations. One lift station was part of the Greenville Sewer Wastewater system. The other station was part of the Taylorsville Sewer Wastewater facility. These damages were fixed using FEMA grant funds.

January of 1997 – A flood and localized flood event occurred after rains on January 1,1997. This occurred throughout Plumas County, Feather River Watershed, Greenville, and the larger Central Valley. There was minimal property damage in the District. There was significant public infrastructure damage such as roads, bridges and culverts. Significant economic impact due to transportation disruptions and infrastructure damage. There was environmental & geological damage due to channels of local creeks and streams being significantly altered.

Climate Change and Flood
It is likely that climate change will increase the chance of future occurrence as well as future impacts associated with flood. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

According to the 2021 CAS (as well as the 2024 Draft CAS), climate change may affect flooding in California, the Plumas County Planning Area, and the IVCSD. While average annual rainfall may increase or decrease slightly, the intensity of individual rainfall events is likely to increase during the 21st century.

It is possible that average soil moisture and runoff could decline, however, due to increasing temperature, evapotranspiration rates, and spacing between rainfall events. Reduced snowpack and increased number of intense rainfall events are likely to put additional pressure on water infrastructure which could increase the chance of flooding associated with breaches or failures of flood control structures such as levees and dams. Cal Adapt future precipitation projections were shown in Section 4.3.4.

Vulnerability to Flood: 1% and 0.2% Annual Chance
Floods have been a part of the District’s historical past and will continue to be so in the future. During winter months, long periods of precipitation and the timing of that precipitation are critical in determining the threat of flood, and these characteristics further dictate the potential for widespread structural and property damage. Predominantly, the effects of 1% and 0.2% annual chance flooding are generally confined to areas near the waterways of the District. As waterways grow in size from local drainages, so

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Plumas County IVCSD Annex E-36
Local Hazard Mitigation Plan Update
January 2026
grows the threat of flood and dimensions of the threat. In addition, there is a small area at risk to levee failure flooding in the District.

The whole of the District is at some measure of vulnerability to floods. An assessment of a community’s vulnerability to flood begins with an understanding of local exposure to flood. This is included in the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.

If the dam fails from heavy rains and storms, chief concerns would be the likelihood of a catastrophic flash flood. The rapid inundation of Indian Valley, destruction of infrastructure, and significant risk to human life. The flash flooding risk is compounded by the areas current vulnerability following the Dixie Fire. The District is also concerned with rain on snow events, which can cause greater flooding in the District.

Along with dam failure, the District is concerned with aging infrastructure being affected by large flooding events. Also, cascading events such as wildfire burn areas increasing chance of floods & mudflow and existing flood maps may underestimate the risk of floods, especially with climate change possibly exacerbating weather events. The impact on property, residents, and various financial risks are of concern as well.

People and Populations
All people and populations (both District staff and those in the Service Area) located in the 1% and 0.2% annual chance floodplains are at some risk to flooding. Certain vulnerable populations located within areas prone to flooding may be at increased risk to this hazard, especially during a large event with minimal advance notice. These vulnerable populations include: the unhoused, those with limited mobility, and those that lack the resources to leave the area.

Populations served by the District can be the most vulnerable. Not only are the residents at risk, but their homes and contents are all at risk, compounding the impacts associated with significant hazard events. The District’s ability to provide services to its populations during flood events is paramount.

Structures and Critical Facilities
Certain District structures are at risk of DFIRM flooding and primarily include those structures located within the 1% and 0.2% annual chance floodplains. All District assets listed in Table E-2 would be at risk to flooding.

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Plumas County IVCSD Annex E-37
Local Hazard Mitigation Plan Update
January 2026
Flooding presents a threat to both critical facilities and infrastructure, as well as community lifelines.

Critical infrastructure plays an immensely important role in our communities. As previously noted, communities rely on roads, rail corridors, and related biking and pedestrian routes for transportation, and on water infrastructure for drinking water, wastewater service, and draining streets of rainwater. Damage to any one of these systems can threaten public safety, wreak havoc on daily life, impact properties far from flood zones, and result in economic impacts that cascade throughout California.

Natural, Historic, and Cultural Resources
Large flood events can affect natural, historic, and cultural resources. There are a number of ways floodwaters can impact natural resources and the environment. Wildlife habitats can be destroyed by floodwaters. Contaminated floodwater can pollute rivers and habitats. Silt and sediment can destroy natural areas. Riverbanks and natural levees can be eliminated as rivers reach bankfull capacity. Rivers can be widened, and deposition can increase downstream. Trees can be uprooted by high-velocity water flow.

Plants that survive the initial flood may die due to being inundated with water. Historic and cultural resources may also be affected. Generally, the impacts are associated with damage to structures within the flooded areas, but other cultural resources such as those associated with Native Americans and old tribal areas can also be disturbed, damaged and lost during extreme flood events. Any of these that fall in the flood zones and leveed areas shown on Figure E-3 would be vulnerable.

Impacts from Flood: 1% and 0.2% Annual Chance
Floods are among the costliest natural disasters in terms of human hardship and economic loss nationwide.

Large flood events, including those associated with 1% and 0.2% annual chance floods, can cause substantial damage to structures, landscapes, and utilities as well as life safety issues. People may be swept away in floodwaters, causing injuries or deaths. Floods can be extremely dangerous, and even six inches of moving water can knock over a person given a strong current. During a flood, people can also suffer heart attacks or electrocution due to electrical equipment short outs. Direct impacts, such as drowning, can be limited with adequate warning and public education about what to do during floods. Floodwaters can transport large objects downstream which can damage or remove stationary structures. Structures can be damaged directly from floodwaters and can also be damaged from trees falling as a result of water-saturated soils. Ground saturation can result in instability, collapse, or other damage. Objects can also be buried or destroyed through sediment deposition. Floodwaters can also break utility lines and interrupt services causing power outages. The interruption of power causes major problems and can result in the closure of governmental offices and community businesses. Roads can be damaged and closed, causing safety and evacuation issues.

Standing water can cause damage to crops, roads, foundations, and electrical circuits. Other problems connected with flooding and stormwater runoff include erosion, sedimentation, degradation of water quality, loss of environmental resources, and economic impacts.

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Plumas County IVCSD Annex E-38
Local Hazard Mitigation Plan Update
January 2026
Future Conditions/Future Development
This section provides a discussion of how future conditions will influence or affect the hazard over time and also discusses future development relative to each hazard.

Future Conditions
Future conditions may be affected by climate change, changes in population patterns (migration, density, or the makeup of socially vulnerable populations), and changes in land use and development. Findings on this for the IVCSD include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over time.
➢ Population projections within the District’s service area show the population to be slightly declining. It is unknown how population patterns and demographics will change in the near future. The District may add staff, but this number would be relatively small. The District noted that it has no control over population changes within its service area. With no notable changes in populations numbers and makeup, the vulnerability of the District to a dam failure is unlikely to change. ➢ Changes in land use and development in the District are expected to be limited in the near future and thus are not likely to affect flooding and associated impacts to the District. Some redevelopment of the areas of the District burned in the Dixie Fire may occur, but this will occur where previous development existed. Additional development traditionally leads to additional flooding. In addition, adherence to protective building codes for new development will also assist in limiting future impacts and associated vulnerabilities of the District to this hazard. With adherence to development standards, future losses to new development should be minimal.

Future development in the District may be built in the floodplain, as long as it conforms to the standards of the floodplain ordinance. The County enforces their floodplain management ordinance on areas inside the District. More detail on the specifics of the floodplain ordinance can be found in Section 4.4.1 of the Base Plan. New District facilities and assets will be sited in such a way as to reduce the risk from flooding to District structures.

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Plumas County IVCSD Annex E-39
Local Hazard Mitigation Plan Update
January 2026
Flood: Localized Stormwater Flooding
Likelihood of Future Occurrence–Highly Likely
Vulnerability–Medium
Hazard Profile
Flooding occurs in areas other than the FEMA mapped 1% and 0.2% annual chance floodplains. Flooding may be from drainages not studied by FEMA, lack of or inadequate drainage infrastructure, or inadequate maintenance. Localized, stormwater flooding occurs throughout the District and the Plumas County Planning Area, especially during the rainy season from November through April. Prolonged heavy rainfall (including that from atmospheric river events) contributes to a large volume of runoff resulting in high peak flows of moderate duration.

Location and Extent
The IVCSD is subject to localized flooding throughout the District. This is discussed in Table E-9 below.

Flood extents are usually measured in areas affected, velocity of flooding, and depths of flooding. Expected flood depths in the District vary by location. Flood durations in the District tend to be short to medium term, or until either the storm drainage system can catch up or flood waters move downstream. Localized flooding in the District tends to have a shorter speed of onset, especially when antecedent rainfall has soaked the ground and reduced its capacity to absorb additional moisture.

NCDC Events
The NCDC occurrences of localized flooding are included in the 1% and 0.2% annual chance flood hazard profile above where past flood events were noted. These include 15 flood related events for the entire County Planning Area reported since 1993.

IVCSD Events
Localized flooding occurs every year. Starting with the great flood of 1997 and as part of other events identified for the District, large storm and flood events continue to cause damages within the District. This was discussed in the Past Occurrences section of the Flood: 1%/0.2% Annual Chance above.

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Plumas County IVCSD Annex E-40
Local Hazard Mitigation Plan Update
January 2026
change and reflect storms of greater volume and intensity. More information on future impacts to the District can be found in the Future Conditions/Future Development section of the Vulnerability Assessment below.

Historically, the District has been affected by flooding of streams and creeks occurring during heavy rain and storm (including atmospheric river) events. Additional development in the District and in the watersheds of these streams affects both the frequency and duration of damaging floods through an increase in stormwater runoff and contributes to localized flooding occurring in areas throughout the District. The lack of or inadequate drainage infrastructure in the District contributes to localized flooding issues. The District is also concerned with rain on snow events, which can cause greater flooding in the District.

The District tracks localized flooding areas. Affected localized flood areas identified by the IVCSD are summarized in Table E-9.

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Portola City CouncilJune 10, 2026

Portola City Council
June 10, 2026