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

320 requires a development permit before any construction or development begins in an area of special flood hazard, issued by the County Zoning Administrator on plans showing the lowest floor elevation, any floodproofing certification, and the extent of any watercourse alteration. Where a regulatory floodway hasn't been mapped, no new construction, fill or substantial improvement is allowed in Zones A1-30 or AE unless the applicant shows it won't raise the base flood's water surface elevation more than one foot anywhere in the unincorporated county. 330's general standards require new construction and substantial improvements to be anchored against flotation, collapse and lateral movement, built with flood-resistant materials and utility equipment, and designed so electrical, heating, plumbing and HVAC components stay above flood conditions; manufactured homes need frame or over-the-top tie-downs capable of carrying 4,800 pounds of force at each anchor point.

Any enclosure below the base flood elevation is flatly prohibited, and larger subdivisions (fifty lots or five acres, whichever is less) must supply base flood elevation data. 390. Variances require a showing of good cause and exceptional hardship and cannot increase flood heights or public safety risk.