West Des Moines, IA Environmental Rules: Flood Elevation Requirements (2026)

City Code section 8-8-2 defines base flood elevation (BFE) as the elevation floodwaters would reach during a base flood, the flood with a one percent annual chance of being equaled or exceeded. Section 8-8-6(B)(2) requires new or substantially improved residential structures to have the lowest floor, including a basement, elevated a minimum of one foot above the BFE, built on compacted fill that stays at or above 1.0 foot over the BFE and extends at least eighteen feet beyond the structure. Piers or other elevation methods may substitute for fill only with Board of Adjustment approval where topography or street grades make fill impractical, and any new residential structure must keep a means of access passable by wheeled vehicles during a base flood.

Section 8-8-6(B)(3) applies the same one-foot freeboard to non-residential structures, or allows floodproofing to that level instead, certified by an Iowa-registered professional engineer as watertight and able to withstand flood forces. Enclosed areas below the lowest floor that are not basements must have at least two openings totaling one square inch of net area per square foot of enclosed area, with the lowest opening no higher than one foot above grade, so floodwater can enter and exit automatically. The Building Official, acting as Administrator, records the certified elevation of every covered structure and requires a floodplain development permit before any of this construction may begin.