Canyon County, ID Environmental Rules: Flood Elevation Requirements (2026)

Canyon County's floodplain ordinance, Article 10A of Chapter 7, defines two terms that set the actual construction standard. 'Freeboard,' at Canyon County Code § 07-10A-03, is fixed at one foot (1'), a safety margin the code adds on top of the Federal Insurance Administrator's base flood elevation to cover unknowns like wave action, debris jams and urbanization effects on runoff. Add the two together and the code gets the Flood Protection Elevation (FPE): the base flood elevation plus the freeboard. Section 07-10A-11(2)A, 'Residential Construction,' then applies that combined figure as the actual building standard: new construction, substantial improvements, and development of any residential structure, including manufactured homes, must have the lowest floor, including any basement, elevated no lower than the flood protection elevation.

Non-residential buildings face the same elevation standard under § 07-10A-11(2)B, though commercial and industrial structures in Zones A, AE, AH and AO may floodproof to the flood protection elevation instead of physically elevating, certified by a registered professional engineer or architect. The special flood hazard areas that trigger these standards come from the Flood Insurance Study for Canyon County, Idaho and Incorporated Areas dated June 7, 2019, and the accompanying FIRM maps, both adopted by reference and on file at the Development Services Department office in Caldwell.

A floodplain development permit under § 07-10A-05(3) is required before any development activity begins in a mapped hazard area, and the Floodplain Administrator, the Director of Development Services or a designee, verifies the elevation with certified as-built surveys before signing off. This standard governs only unincorporated Canyon County parcels in the mapped floodplain; it does not reach Caldwell, Nampa or the other cities' own floodplain ordinances.