The California Interagency Fuel Mapping Group (CAIFMG), a consortium of State and Federal agencies, is developing regional "surface fuel" maps that span jurisdictional boundaries. Surface fuels are vegetative materials near the ground through which fire will spread. These materials range from downed woody material (leaf litter, dead branches and logs) to brush and grass. The amount, size and moisture content of surface fuels determines how fast a fire spreads, how hot it burns and how high its flames reach.

CAIFMG develops surface fuel maps by translating vegetation information from a variety of sources (see figure 1) into fuel characteristics, combining them with topographic and historical fire data and patching them together to form a seamless GIS fuels coverage. This process, known as "crosswalking," was originally developed by the Sierra Nevada Ecosystem Project (SNEP), and translates information on plant species, crown cover and tree size into 13 fuel behavior models based on the "Fire Behavior Prediction System" (FBPS). The "crosswalk" process also includes other factors, such as slope, aspect and elevation data to further refine fuel models. Finally fire history information defines areas where surface fuel characteristics change in order to account for past fires and subsequent regrowth (see fuel dynamic pathways for more details).

The scale and date of vegetation data from local, state and federal agencies often vary and therefore the scale and date of the resulting fuel data vary. The scale of the source data control the minimum mapping unit (MMU), the smallest area that can be uniquely identified on the map . The MMU for fuels data developed by CAIFMG ranges from 900 square meters up to 100 hectares. The final data are maintained as raster GIS coverages in an Albers equal area projection with a cell size of 30 meters on a side.

State and Federal fire protection agencies combine regional fuel maps with other geographic information to identify and prioritize projects. CDF combines surface fuels with slope data to rank areas as moderate, high and very high fuel rank. This initial surface fuel rank is then associated with generalized ladder and crown fuel estimates to derive a final fuel assessment and ranking. As part of the California Fire Plan, CDF combines these fuel rankings with weather, assets at risk and historic level of service to identify and prioritize pre-fire projects. Similarly, the USFS, BLM and NPS use surface fuel maps to implement the Federal Wildland Fire Policy and to identify and plan pre-fire projects that reduce fire hazard and ultimately improve ecosystem health. These data are also used by the USFS in a variety of planning and assessment projects, including environmental impact reports, the Sierra Conservation Strategy and detailed Land Management Planning documents.

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