Portage County, WI Zoning Overlays & Bonuses: Density Bonus Law (2026)

Portage County Code § 7.5.5(1)(c) gives developers using the county's Open Space Design Option a density bonus: acreage on the tax parcel zoned conservancy, other than water bodies, can be folded into the calculation of total lot density for the proposed development, as long as the additional lots created that way do not violate any other provision of the zoning ordinance. This sits inside the broader density framework of § 7.5.5(1): the number of dwelling units allowed in an open space development is first set by submitting a conventional subdivision plan showing the buildable lots the parcel could otherwise support, and the Planning and Zoning Department uses that conventional layout to cap the maximum lots available under the open space option, making the conservancy-acreage bonus in subsection (c) the listed way to push past that cap.

The tradeoff is size: to use the open space option and its smaller lots at all, § 7.5.5(1)(b) requires the tax parcel be 20 acres or larger, with a formula for how much acreage must be deed-restricted against future lot splits. Once lots are laid out, § 7.5.5(1)(d) requires residential lots to be grouped so designated open space covers at least 50 percent of the parcel's secondary open space and all of its primary open space, with every lot abutting that open space. A final development plan that increases density more than five percent over what the Portage County Board of Supervisors approved at the preliminary stage is treated by § 7.5.5(2)(b) as a substantial departure, forcing the applicant back through Planning and Zoning Committee review rather than proceeding on the density bonus alone.