Washington County, UT Environmental Rules: Flood Zones (2026)

Title 12 of the Washington County Code adopts the FEMA flood insurance rate map (FIRM) dated December 6, 2006, and the county's own erosion hazard zone delineation study dated May 2007, by reference under section 12-3-2; both documents are on file at the county administration building in St. George. Section 12-3-1 applies the title to all areas of special flood hazard within the county's jurisdiction, and section 12-3-3 bars construction, location, extension or alteration of any structure or land without full compliance with the title.

Section 12-4-1 requires a development permit before construction or development begins in a special flood hazard area, obtained on forms from the building inspector, with duplicate plans showing elevations, existing or proposed structures (including manufactured homes), fill, storage of materials and drainage facilities. Applicants must submit the elevation of the lowest floor (including basement) in relation to mean sea level, any floodproofing elevation, engineer certification of floodproofing methods, and a description of any watercourse alteration or relocation. The floodplain administrator weighs the danger to life and property from flooding or erosion, the susceptibility of the proposed facility to flood damage, the risk that materials could be swept onto other lands, and compatibility with existing and anticipated development before approving or denying the permit.

Subdivision proposals of 50 lots or five acres (whichever is less) must supply base flood elevation data under section 12-5-1D. Encroachments, including fill and new construction, are prohibited in any floodway under section 12-5-1E unless a technical evaluation shows no increase in flood levels during the base flood discharge. A property owner who disagrees with a permit denial may seek a variance from the county appeal board under section 12-4-2, which must find good cause, exceptional hardship, and no increase in flood levels within a floodway before granting relief.