The National All-Lands Wildfire Risk Assessment (NaWRA) is a quantitative analysis of how resources and assets may be impacted by wildfire based on: 1) the intensity of a wildfire if one should occur, 2) the exposure of resources and assets based on their locations, and 3) the susceptibility of those resources and assets to wildfire. Data users are encouraged to access the companion report (NaWRA 2025 Methods) for the full details of the assessment.

Wildfire hazard was modeled using 2025 capable fuels data. Potential wildfire intensity was estimated at 30-m resolution in the form of conditional probabilities of burning in six different flame length bins (0-2, 2-4, 4-6, 6-8, 8-12, and 12+ ft) using the Pyrologix WildEST Model (Scott et al. 2024). WildEST is a deterministic wildfire modeling tool that integrates spatially continuous weather inputs weighted based on how likely they are to be realized on the landscape. Potential wildfire burn probability was estimated for the 11 Western States by running the USDA Forest Service FSim Model (Finney et al. 2011) at 120-m resolution with post-processing to upsample results to 30-m resolution and estimate burn probability in non-burnable areas adjacent to wildland fuels. Wildfire burn probability for the remainder of CONUS came from the Wildfire Risk to Communities Project (Scott et al. 2024) or the Southern Wildfire Risk Assessment (SouthWRA 2024) modeled with FSim using similar methods.

The People and Property, Critical Infrastructure, Historic Structures and Buildings, and Drinking Water layer represents the potential combined impact to human assets and water.

The People and Property Highly Valued Resource and Asset (HVRA) Theme represents the spatial distribution and density of housing units. Wildfire has the potential to damage or destroy homes, apartments, other housing units, outbuildings, and their contents. In extreme cases, housing unit exposure to wildfire also results in human injuries or deaths. The People and Property HVRA was mapped using the housing unit density raster from the USDA Forest Service Wildfire Risk to Communities Project, which estimates housing unit density with 2020 census housing unit data and a comprehensive building footprint dataset (Jaffe et al. 2024). Fuel type was used as a covariate for the response functions to reflect the expectation for higher losses with increasing fire intensities, fire residence times, and resistance to control across the grass-shrub-tree fuel type gradient.

The Critical Infrastructure Highly Valued Resource and Asset (HVRA) Theme represents important healthcare, emergency service, communication, and energy infrastructure. Wildfire has potential to temporarily disrupt the use of or permanently damage infrastructure. Critical Infrastructure was mapped using Homeland Infrastructure Foundation Level Data (HIFLD; <https://www.dhs.gov/gmo/hifld>) accessed in early 2024 to represent Hospitals, Emergency Services, Communication Devices, Electric transmission lines, Power Plants, Substations, Natural Gas Pipelines, and Oil & Natural Gas Wells. The HIFLD program provides consistent spatial data for homeland security analysis and planning.

The Historic Structures and Buildings Highly Valued Resource and Asset (HVRA) Theme represents features that society has deemed culturally significant and worthy of preservation. Historic Structures and Buildings were mapped using the National Register of Historic Places (NRHP; <https://www.nps.gov/subjects/nationalregister/database-research.htm>) accessed in early 2024. The Historic Structures and Historic Building point layers were extracted from the NRHP database and merged into a single layer. Each point feature was buffered by 60-m to represent the approximate zone in which wildfire could impact the feature. Fuel type was used as a covariate for the response functions to reflect the expectation for higher losses with increasing fire intensities, fire residence times, and resistance to control across the grass-shrub-tree fuel type gradient.

The Surface Drinking Water Highly Valued Resource and Asset (HVRA) Theme represents the potential for wildfire to impact municipal drinking water systems with surface water sources through the effects of post-fire erosion, sedimentation, and flooding on infrastructure and water quality based on watershed extent, fuel type, and population served. Surface drinking water source areas were mapped and valued using source water protection areas and associated population served data maintained by the EPA (https://www.epa.gov/sourcewaterprotection/drinking-water-mapping-application-protect-source-waters-dwmaps). The EPA source water protection areas and associated attributes are sensitive information. Therefore, we generalized the full resolution results to comply with EPA information sharing guidelines for all users. The source water protection areas are polygon representations of the watershed area that can contribute flow to an intake point (e.g., reservoir or diversion) within 24-hrs based on modeling completed by EPA. The effects assessment was based on fuel type mapped for this project and slope steepness from LANDFIRE. Relative importance per pixel was set proportional to the population served by the water source, and inversely proportional to the distance from the intake to each location in the source water protection area.