Kenai Peninsula Borough, AK Environmental Rules: Flood Elevation Requirements (2026)

KPB 21.06.030(C) sets the Flood Protection Elevation (FPE), the height to which structures and utilities in the unincorporated borough's flood hazard areas must be raised under the building standards of KPB 21.06.050. In a mapped Special Flood Hazard Area, the FPE equals the Base Flood Elevation shown on the 100-year flood profiles in the Flood Insurance Study; in AH or AO zones it is the flood depth shown on the FIRM or DFIRM, or at least two feet if no depth is listed. Where no elevation or depth data exists at all, including much of the Seward Mapped Flood Data Area, KPB 21.06.030(C)(3) sets a floor of two feet above the highest adjacent grade, a freeboard-style minimum the planning department applies until better data or a locally determined elevation is available.

KPB 21.06.050(B)(1) then applies that number: new construction and substantial improvement of a residential structure must have its lowest floor, including any basement, elevated to or above the Flood Protection Elevation, and any fully enclosed space below that floor must either stay empty or carry engineered flood openings, with a minimum net area of one square inch per square foot of enclosed space and openings no higher than one foot above grade. Manufactured homes must be elevated on a permanent foundation to the same base flood elevation and anchored against flotation.

Before final approval, the owner must submit an elevation certificate, and the planning department will not release a final development permit for a residential structure with below-grade enclosed space until the owner signs a recorded non-conversion agreement.