Ames, IA Environmental Rules: Flood Zones (2026)

Ames Municipal Code Chapter 9, Flood Plain Zoning Regulations, applies wherever the city's Official Flood Plain Zoning Map, adopted from the Story County Flood Insurance Rate Maps dated January 15, 2021, shows a mapped flood hazard area. Sec. 9.2(4) sets the baseline rule: no structure or land shall hereafter be used, and no structure shall be located, extended, converted or structurally altered, without full compliance with the chapter. The map divides the flood plain into three zoning overlay districts under Sec. 9.3: the Floodway Overlay District, the Floodway Fringe Overlay District, and the General Flood Plain Overlay District, each carrying its own permitted-use list.

Inside the Floodway Overlay District, Sec. 9.4(2) requires any development involving structures, fill, or storage of materials or equipment, such as a shed, driveway or grading project, to obtain a Major Site Development Plan under Section 29.1103 and to meet the district's performance standards, including a rule that no development may raise the base flood elevation at all. The Flood Plain Administrator, defined in Sec. 9.7 as the Director of the Department of Planning and Housing or a designee, reviews every flood plain development permit application, keeps elevation and floodproofing records, and reports to the City Council on conflicts with subdivision proposals.

Property owners contesting a district boundary get a chance to present technical evidence to the Administrator under Sec. 9.2(3). Sec. 9.8 additionally restricts expansion of any nonconforming use already inside the flood plain.