The Wildland-Urban Interface is the zone where houses meet undeveloped wildland fuel. Utah's HB 48, and later HB 41, require local governments to define and maintain WUI boundaries. The legal text does not say how to build those boundaries in GIS. This project is that workflow. I developed it with the Unified Fire Authority, first presented it at a quarterly UGEM meeting in 2025, and expanded it for UGIC 2026. Other jurisdictions can use it instead of starting from nothing.
How the boundary was built
The boundary starts from statewide wildfire risk datasets: structure exposure, burn probability, and suppression difficulty. It layers those with USFS WUI and intermix classifications. Local street centerlines and parcel boundaries then adjust the raw risk surface into a line that planners and building officials can apply. Data sources include Millcreek, Salt Lake County, the Utah Geospatial Resource Center (UGRC), the U.S. Forest Service (USFS), USGS, and the Utah Division of Forestry, Fire and State Lands (FFSL).
Built to be reused
The 2026 version is a full update of the original HB 48 talk. It adds HB 41 coverage, updates for the Utah Wildfire Risk Assessment Portal (UWRAP), more supporting datasets, and clarifications from using the workflow in the field since the first version. The goal is the same each time: give planners and GIS staff in other jurisdictions something they can apply directly.
Separate from the state fee program
This workflow is separate from Utah's state High-Risk WUI fee program. It covers local and county WUI boundary mapping for jurisdictions that maintain HB 48 and HB 41 compliance. The two get confused often enough that it is worth stating here.
First presented at a quarterly UGEM meeting in 2025; expanded for UGIC (Utah Geographic Information Council) 2026.