Portage County, WI Environmental Rules: Flood Zones (2026)

Portage County Code § 7.6.2(a) sets four baseline construction standards for every new building and substantial improvement the county determines sits in a flood-plain area: the structure must be designed and anchored to prevent flotation, collapse, or lateral movement from hydrodynamic and hydrostatic loads, including buoyancy; it must be built with flood-resistant materials; it must use construction methods and practices that minimize flood damage; and its electrical, heating, ventilation, plumbing, and air conditioning equipment must be designed or located to keep water from entering or accumulating in those components during a flood.

The same section extends parallel obligations to new subdivisions or developments proposed in a flood-prone area under § 7.6.2(b): the community must confirm the project is consistent with minimizing flood damage, that utilities are located and built to minimize or eliminate flood damage, that drainage is adequate to reduce flood exposure, and that any subdivision proposal includes regional flood elevation and floodway data. These standards sit under the county's Floodplain Zoning ordinance, adopted under Wis. Stats. §§ 59.69, 59.692, and 59.694, which per § 7.6.1(5)(a) regulates every area shown as a special flood hazard zone (A, AO, AH, A1-30, AE, VE, V1-30, or V) on the FEMA Flood Insurance Rate Map, plus any additional area the county and the DNR identify on their own maps.

The Floodway, Floodfringe, and General Floodplain Districts created by § 7.6.1(5)(c) each layer additional, more specific requirements on top of this general standard, and § 7.6.1(5)(g) makes compliance mandatory for cities, villages, towns, and the county itself, not just private landowners.