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

Sauk County Code Sec. 9.005 defines 'flood protection elevation' as an elevation of two feet of freeboard above the Regional Flood Elevation (RFE), the two-foot margin the county's floodplain ordinance calls 'freeboard' to compensate for factors, such as ice jams, debris accumulation, wave action, and watershed urbanization, that can push flood heights above the calculated level. Sec. 9.014(3)(a)1, in Subchapter V governing the Flood Fringe District, applies that definition to new construction: any residential structure or manufactured home that is newly built or moved into the flood fringe, and any substantial improvement of an existing residential structure, must have its lowest floor elevated to or above the flood protection elevation on fill, with the fill extending at least one foot above the RFE for a minimum of 15 feet beyond the structure's limits.

Sec. 9.014(3)(a)2 allows an exception for a basement or crawlspace floor to sit at the RFE itself only if it is designed watertight, with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads; no floor of any kind may be placed below the RFE. Commercial and manufacturing structures in the flood fringe face the same elevation standard under Sec. 9.014(3)(c) and (d), and manufactured home standards for replacement or substantially improved units in existing parks require the lowest floor at or above the flood protection elevation under Sec. 9.014(3)(k)2. The Sauk County Zoning Administrator issues the land use permit and reviews the fill and elevation plans before construction begins.