Portage County, WI Environmental Rules: Flood Elevation Requirements (2026)

Portage County Code § 7.1.6(10) defines 'flood protection elevation' as an elevation of two feet of freeboard above the water surface profile elevation designated for the regional flood, the extra margin the county builds in above the base flood level to absorb wave action, debris, and mapping uncertainty. That defined elevation becomes an operative construction standard in the Floodfringe District under § 7.6.4(3)(a)1: any new construction, including placement of a manufactured home, and any substantial improvement of a residential structure in the floodfringe must have its lowest floor elevated to or above the flood protection elevation on fill, and the fill itself must extend at least one foot or more above the regional flood elevation for a minimum of 15 feet beyond the structure's limits.

Section 7.6.4(3)(a)2 allows one narrow alternative to full fill: a basement or crawlspace floor can sit at the regional flood elevation itself, without the two-foot freeboard, only if it is engineered watertight, with walls substantially impermeable to water and structural components capable of resisting hydrostatic and hydrodynamic loads and buoyancy, and the code adds flatly that 'no floor of any kind is allowed below the regional flood elevation.' Contiguous dryland access from the structure to land outside the floodplain is required under § 7.6.4(3)(a)3, unless the county grants a documented exception for a road below the regional flood elevation under § 7.6.4(3)(a)4, which itself requires written assurance from police, fire, and emergency services that they can still reach the structure by wheeled vehicle during a regional flood.