Council Bluffs, IA Environmental Rules: Flood Elevation Requirements (2026)

CBMC 13.25.150, part of the Floodplain Management Standards article, sets Council Bluffs' freeboard requirement for residential construction: the lowest floor, including any basement, of a new or substantially improved residential structure must be elevated a minimum of one foot above the one-hundred-year flood level, one foot above the FEMA-mapped base flood elevation for the site. Where fill is used to achieve that elevation, the fill must be no lower than one foot above the flood level at every point and extend at least 1.8 feet beyond the structure's limits, and any alternate elevation method such as piers requires favorable city council consideration where topography or street grades make filling impractical.

New residential structures must also have access passable by wheeled vehicles during a one-hundred-year flood. Nonresidential buildings face a parallel one-foot elevation or floodproofing standard under CBMC 13.25.160, certified by a professional engineer registered in Iowa when floodproofing is used instead of elevation. CBMC 13.25.240 provides a narrow accessory-structure exemption from the base flood elevation rule: detached garages, sheds, and similar structures incidental to a residential use may skip the one-foot elevation if the structure is under 600 square feet, designed for low flood-damage potential, used only for parking or limited storage, anchored against flotation, and built with flood-resistant materials below one foot above the base flood elevation. The city warns applicants that using this exemption can raise flood insurance premiums.