Ashwaubenon, WI Environmental Rules: Flood Elevation Requirements (2026)

Wisconsin's floodplain zoning mandate under Wis. 30 requires every municipality to adopt these standards, and the Village's own Chapter 14, last amended by Ordinance No. 2-2-23 on February 28, 2023, supplies the operative numbers. 'Flood Protection Elevation' is defined in Section 14-1-5 as two feet of freeboard above the Regional Flood Elevation, a safety margin that accounts for ice jams, debris accumulation, wave action and other factors that push actual flood heights above the calculated level. Section 14-4-3(A) applies that definition to the Floodfringe District: any newly constructed or substantially improved residential structure, including a manufactured home, must have its lowest floor elevated to or above the flood protection elevation on fill, and the fill itself must rise at least one foot above the regional flood elevation and extend at least 15 feet beyond the structure's limits.

A basement or crawlspace floor may instead sit at the regional flood elevation, one foot lower, only if it is engineered watertight to the flood protection elevation and can resist hydrostatic and hydrodynamic loads; no floor of any kind may go below the regional flood elevation. Contiguous dryland access outside the floodplain is required unless Ashwaubenon Public Safety gives written assurance that wheeled-vehicle rescue is available or the Village has a DNR-approved evacuation plan. The same flood protection elevation standard extends to accessory structures under Section 14-4-3(B) at the regional flood elevation on fill, to manufacturing and industrial buildings under Section 14-4-3(D) at the flood protection elevation or dry-floodproofed under Section 14-8-7, and to sewage systems, wells and stored hazardous materials under Sections 14-4-3(E), (G) and (H).