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Fire Hazard Severity Zones
San Luis Obispo County


FHSZ in State Responsibility Area:

Adopted, 11/2007:
PDF (46 inches x 34 inches; 4.9MB)
JPG (8.5 inches x 11 inches; 4.2MB)
GIS layer (Shapefiles in .zip folder)


FHSZ Local Responsibility Area:

Recommended, 7/2009: 
PDF (46 inches x 34 inches; 6.6MB) 
JPG (8.5 inches x 11 inches; 1.1MB) 
GIS layer (Shapefiles in .zip folder) 

Other City Maps for Approval VHFHSZ

Atascadero (PDF; 2.2MB)
Morro Bay (PDF; 1.0MB)

Pismo Beach (PDF; 1.4MB)
San Luis Obispo (PDF; 1.5MB) 


Note: In the default display for city maps, all areas outside of the city boundary are masked out. To remove the mask, click the "Layers" tab in the left margin. Then click the eye icon next to "City Mask."

Note: In the default display for city maps, all areas outside of the city boundary are masked out. To remove the mask, click the "Layers" tab in the left margin. Then click the eye icon next to "City Mask."

PRC 4201-4204 and Govt. Code 51175-89 direct the California Department of Forestry and Fire Protection (CAL FIRE) to map areas of significant fire hazards based on fuels, terrain, weather, and other relevant factors. These zones, referred to as Fire Hazard Severity Zones (FHSZ), then define the application of various mitigation strategies to reduce risk associated with wildland fires.


The project will be driven by Geographic Information System (GIS) data in conjunction with modeling techniques designed to describe potential fire behavior and fire probability. Areas will be mapped in Moderate, High and Very High Categories. The project will run along two concurrent tracks: one designed to develop and refine the model itself regarding its scientific rigor, spatial accuracy, and data delivery mechanisms designed to facilitate end use by a wide variety of clients. The other track will focus on the roll-out and implementation process whereby local CAL FIRE units and local fire agencies review/comment and adjust the zones to conform to local knowledge not captured in the draft model.

Finally, the maps will follow established adoption processes required by state statute, consistent with implementation of new Wildand-Urban Interface (WUI) building codes that have been adopted by the California Building Standards Commission. 


The basic elements of the Fire Hazard Zone model will be built from existing data and hazard constructs developed by CAL FIRE’s Fire and Resource Assessment Program (FRAP) used to develop Fire Threat and Communities at Risk listing in the Federal Register pursuant to the National Fire Plan (see for details). The model will work from these products as starting points, and refine characterization of the zones to directly attempt to characterize fire exposure mechanisms that cause ignitions to structures. These basic constructs follow classical quantitative risk assessment whereby probabilities of fire behaviors define the hazard component of risk analysis. CAL FIRE, FRAP is partnering with researchers at UC Berkeley and the private sector to develop this model and it promises to use innovative techniques to meet the objectives and usage of the data.

Specific model components will focus on characterizing potential fire behavior arising for vegetation fuels that are by nature dynamic. Since many of the applications of the zones involve permanent engineering mitigations associated with structure construction, it is desirable that the nature of the zone reflect changes in fire behavior/exposure relative to the length of time the structure will be in place. While obviously significant land-use changes will need to be captured through period maintenance routines, basic vegetation dynamics and maximal hazard levels will be used to develop the model such that mitigations match potential exposure over the horizon of the mitigation design.

The model will also incorporate a measure of fire probability predicated on frequency of fire weather, ignition patterns, expected rate-of spread, and/or past fire history similar to techniques uses to calculate fire rotation as used in the development of Fire Threat. A detailed description of components used in Fire Threat can be found here.

Finally, the model will characterize flying ember (brand) production from vegetation fuels, and zoning hazard based on the area of influence that those brands are likely to land and cause potential ignitions. This functional mechanism of hazard is the principal driver of hazard in densely developed areas. A related concern in already built-out areas is the relative density of vegetative fuels that can serve as receptive sites for new spot fires to initiate within the urban core, and then spread to adjacent structures. The project will explore techniques to model accurately both the brand production/reception element, as well as fire spread potential in urbanized areas.




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