Utah County, UT Environmental Rules: Flood Elevation Requirements (2026)

16 sets numeric elevation standards once base flood elevation data exists for a site, drawn from the Flood Insurance Study, the FIRM map, or another accurate scientific flood study. Large-scale development proposals covering at least 50 lots or 5 acres, whichever is less, must submit base flood elevation data as part of their application. For residential construction, any new construction or substantial improvement to a dwelling must have its lowest floor, including any basement, raised 1 foot above the base flood elevation. In areas mapped AO or AH, the lowest floor must instead sit 1 foot above the flood depth number printed on the FIRM map, or at least 2 feet above the highest adjacent grade if no depth number is given, and drainage paths must route floodwater around structures built on slopes.

Fully enclosed areas below the lowest floor used only for parking, building access or storage must have flood vents: a minimum of two openings totaling at least one square inch of net area per square foot of enclosed floor space, with the bottom of every opening no higher than 1 foot above grade. Nonresidential buildings follow the same 1-foot freeboard rule but may instead be built below that elevation if flood-proofed watertight and certified by a Utah-licensed professional engineer or architect. Manufactured homes must have their lowest floor set 1 foot above base flood elevation on a permanent, anchored foundation, or rest on reinforced piers at least 36 inches above grade.

A property owner seeking to build below these elevations needs an Appeal Authority variance and must receive a written disclosure that flood insurance costs will reflect the increased risk; every variance granted is reported to FEMA.