Environmental Rules in Sun Prairie, WI (2026)

Flood Zones

Sun Prairie participates in the National Flood Insurance Program (NFIP) and regulates floodplain development under Wis. Stat. Sec. 87.30 and Wisconsin Administrative Code Chapter NR 116, plus 44 CFR Parts 59-72. Koshkonong Creek is the principal regulated waterway through the city, with secondary drainage to Token Creek (northwest) and the Maunesha River (northeast). Hydric soils, spring snowmelt, and proximity to Koshkonong Creek make portions of the city flood-prone, as demonstrated by the June 2008 flood event. New residential structures are prohibited in the regulatory floodway, and structures in the flood fringe must be elevated to the flood protection elevation. Floodplain permits and FEMA Flood Insurance Rate Maps are administered through the city zoning office and the Wisconsin DNR.