Walworth County, WI Environmental Rules: Stormwater Management (2026)

Walworth County's Storm Water Management Ordinance, codified at Chapter 26, Article I, was adopted by the County Board under Wis. Stats. §§ 59.693, 92.07(15) and 236.45 to meet the state's post-construction runoff objectives in Wis. Stats. § 281.33. The Board designated the Walworth County Land Conservation Division, part of the Land Use and Resource Management Department, to administer and enforce it. Sec. 26-12(a) makes clear no landowner or responsible party may commence a land-disturbing or land-development activity covered by the ordinance without first obtaining a storm water management permit; applicants submit an application, a storm water management plan meeting the Sec. 26-10 performance standards, a long-term maintenance agreement, and a non-refundable fee, and the Division has 30 days to review it under Sec. 26-13.

The ordinance reaches subdivision plats, certified survey maps or other developments adding 0.5 acres or more of impervious surface, new roads serving more than five lots, and any post-construction site with an acre or more of land-disturbing activity, plus smaller projects the Land Conservation Division decides are likely to overload drainage or damage water quality. Table 3 of Sec. 26-10 sets total suspended solids reduction targets of 80 percent for new and infill development and 40 percent of the parking- and road-generated load for redevelopment. Agricultural cultivation, silviculture, underground utility work and state DOT road projects within their right-of-way are exempt.

Starting construction before a permit is applied for and issued triggers a double permit fee under Sec. 26-12(c)(2), which does not excuse the landowner from full compliance or from prosecution.