Oshkosh, WI Environmental Rules: Flood Zones (2026)

Wisconsin requires every municipality with mapped floodplain or that participates in the NFIP to adopt a floodplain zoning ordinance meeting the minimum standards of Chapter NR 116 (Wis. Admin. Code) and 44 CFR 59-72, under the authority of Wis. Stat. Sec. 87.30. Oshkosh implements these requirements through Article VI of Chapter 30, which creates the Floodplain Overlay District (FP-O) and the Shoreland Overlay District (SL-O), supplemented by the Lakefront Residential Overlay (LR-O) for properties along Lake Winnebago and the Riverfront Overlay (RF-O) for properties along the Fox River. Under NR 116 the regulatory floodway prohibits new residential structures and most fill, while the flood fringe allows development if the lowest floor of habitable space is elevated to or above the flood protection elevation (regional flood elevation plus a freeboard, typically 2 feet under NR 116.13). Wisconsin's shoreland definition - 1,000 feet from the ordinary high-water mark of a navigable lake/pond/flowage and 300 feet (or to the floodplain, whichever is greater) of a navigable river or stream - covers large portions of Oshkosh because of Lake Winnebago and the Fox River. A Wisconsin DNR-approved local zoning permit is required before any building permit may be issued for development in the FP-O or SL-O. The authoritative Flood Insurance Rate Maps for Winnebago County are issued by FEMA and viewable at msc.fema.gov and through the county's adopted floodplain viewer. Winnebago County's own Chapter 26 Floodplain Zoning Code applies in unincorporated areas.