6 – Wildfire Risks

6.1 Risk Drivers Associated with Design, Construction, Operation, & Maintenance

Wildfire risks related to the design, construction, and operation of utility equipment and facilities are influenced by several factors, including the age of equipment, difficult rural service territory access, budgetary issues, and the expansion of service territory into wildland-urban interface (WUI) areas.

Assets in remote areas with difficult terrain are more challenging to access, monitor, and maintain. In rural service territories, poor access can also delay fire crew response times, allowing fires to spread rapidly. Sparse populations mean fewer people are available to report issues or fires, reducing the likelihood of early detection and increasing the risk of large, uncontrolled fires.

The continued extension of service territory into WUI areas increases human activity, raising the potential for fires to start from construction, vehicle accidents, debris burning, and other activities. These areas often have significant vegetation, providing ample fuel for fires ignited by utility equipment. Urban expansion requires utilities to extend services into vegetated and fire-prone areas, necessitating careful planning to balance service needs with fire safety and environmental concerns.

6.2 Risk Drivers Associated With Topographic & Climatological Factors

Wildfire risks in Okanogan County are highly influenced by both topographic and climatological factors. The region's unique geography and climate contribute to a very high fire risk, with several specific drivers increasing the likelihood and severity of wildfires.

1 of the primary climatological drivers of wildfire risk in Okanogan County is the frequent drought conditions. The lack of moisture reduces the natural barriers that can slow fire progression, making the landscape more susceptible to large-scale outbreaks with rapid spread potential.

The diversity of vegetation across the county further complicates wildfire risks. The county's landscape includes a variety of terrain, from shrub-steppe valleys to timbered highlands, each presenting unique challenges and risks for wildfire management. In the valley bottoms, the presence of light, and flashy fuels, such as grasses and shrubs, can lead to fast-moving surface fires. These types of fuels ignite easily and burn quickly, often acting as a catalyst for larger fires by spreading flames to more substantial, harder-to-burn fuels. In contrast, higher elevations with timbered lands can support crown fires, which burn the canopy of trees and are difficult to control. The accumulation of dead wood and forest debris combined with dense tree cover creates a highly combustible environment that can sustain intense and long-lasting wildfires.

Climatologically, the county is prone to summer wind events that can rapidly expand the size and intensity of new fires by carrying embers over long distances and igniting spot fires well ahead of the main fire front. These conditions can overwhelm firefighting efforts and increase the difficulty of containment. Wind-driven fires are particularly dangerous because they can change direction suddenly and spread across vast areas. The varied topography of Okanogan County adds to the complexity of managing wildfire risks with its steep hills and valleys, can influence fire behavior by funneling winds and creating microclimates that affect fire intensity and spread. Additionally, there are a number of areas that do not allow automated vehicle location, radio, cell, or satellite phone communications.

6.3 Enterprise-Wide Safety Risks

All utilities face enterprise-wide safety risks that are specific to the organization and region. For OKPUD, some risk areas may include:

• Operational
  • Due to the remote areas we serve, response time can be a factor
  • Limited communications (radio, cell phone or satellite) due to topography
• Procedural
  • Effective processes to maintain vegetation encroachment or perceive when action is needed
  • Effective processes for distribution and transmission line inspections
• System Sensitivities
  • Line contact from objects.

6.4 Wildfire History & Outlook

While wildfires occur in all regions of the state, Washington’s largest wildfires occur on the drier east side of the Cascade Range due to hot, dry, and windy conditions. The 2014 lightning-caused Carlton Complex fire in Okanogan County is still the state’s largest wildfire to date. As shown in figure 3, large-scale wildfires occur regularly throughout the service area and adjacent counties.

Generally speaking, fire season in Washington lasts from April through the end of October, but wildland fires have occurred in every month of the year. Fire seasons from 2003 through 2012 averaged more than 84 days longer than in 1973 to 1982². According to NIFC data, the total number of fires and total number of acres burned are trending upward with a significant increase in the number of acres burned since 2000. The largest fire years coincide with warm spring and summer temperatures, and early spring snowmelt. Annual large wildfire frequency in US Forest Service (USFS), National Park Service, and Bureau of Indian Affairs (BIA) forests is significantly correlated with spring and summer temperatures. Projected warmer and drier summers, declining snowpack, and correlated decreases in summer soil moisture will increase the risk of wildfires, particularly in forested areas where fuels are abundant³.

Figure 2 illustrates the Red Flag Warning data from 2022 through 2024 for the 4 fire weather zones in proximity to the service area. All RFWs in these zones have occurred between June and September for the past 3 years.

Figure 2. Red Flag Warning by Year & Month (2022 to 2024)

² Westerling, A.L. 2016 Increasing Western US Forest Wildfire Activity

³ RMJOC 2018; Gergel et al 2017

Figure 3. Wildfire Perimeters 2000 to 2021

6.4.1 Wildfire Hazard Potential

The Wildfire Hazard Potential (WHP) map (Figure 4) used in this plan is a raster geospatial dataset produced by the USDA Forest Service, Fire Modeling Institute (FMI). It is intended to inform evaluations of wildfire risk or prioritization of fuels management needs across large landscapes. The specific objective of the WHP map is to depict the relative potential for wildfire that would be difficult for suppression resources to contain.

The WHP-2023 dataset was built upon:

• Spatial vegetation and wildland fuels data from LANDFIRE 2020 (version 1.4.0). The LANDFIRE Fire Behavior Fuel Models layer is a primary input to the FSim Burn Probability (BP) and Fire Intensity Level (FIL) datasets, and forms the foundation for WHP.
• Spatial datasets of wildfire likelihood and intensity were generated for the conterminous U.S. with the Large Fire Simulator (FSim). FSim simulates the growth and behavior of hundreds of thousands of fire events for risk analysis across large land areas using geospatial data on historical fire occurrence, weather, terrain, and fuel conditions. Effects of large-fire suppression on fire duration and size are also simulated. This research aims to develop a practical method of quantifying geospatial wildfire impacts, including annual probabilities of burning and fireline intensity distributions at any point on the landscape.
• Point locations of past fire occurrence from 1992 through 2020

Areas mapped with higher WHP values represent fuels with a higher probability of experiencing torching, crowning, and other extreme fire behavior under conducive weather conditions. An essential aspect of the WHP method is the use of "resistance to control weights" at the end of the mapping process. This serves to reduce the WHP index in areas with light fuels, such as grass and shrubs. This helps to inform where forest fuel reduction treatments might be most needed.

On its own, WHP is not an explicit map of wildfire threat or risk, but when paired with spatial data depicting highly valued resources and assets such as communities, structures, or powerlines, it can approximate relative wildfire risk to those resources and assets. WHP is not a forecast or wildfire outlook for any particular season as it does not include any information on current or forecasted weather or fuel moisture conditions.

Figure 4. Wildfire Hazard Potential