Sun Prairie, WI Environmental Rules: Stormwater Management (2026)
Key Facts
- Permit trigger
- 20,000 sq ft new impervious surface
- Enforcing agency
- City engineering department
- Plan review time
- 20 days under 2 acres, 45 over
- Permit validity
- 180 days from issuance
- Sediment reduction goal
- 80% for new development
- Discharge penalty
- $50 to $2,000 per day
Summary
Sun Prairie requires a stormwater management permit from the city engineering department before any development adds 20,000 square feet of impervious surface, subdivides land, or files a certified survey map for commercial or industrial use. Discharging pollutants into the municipal storm sewer system, drainage ways, lakes, streams or wetlands anywhere in the city is a separate, standalone violation under Chapter 15.30.
Unless otherwise exempted by Section 15.30.040, a stormwater management permit shall be required and all stormwater management provisions of this chapter shall apply, to any of the following activities within the city of Sun Prairie:1.Any development(s) after August 22, 2001, that result(s) in the cumulative addition of twenty thousand (20,000) square feet of impervious surface to the site. ... It shall be unlawful for any person to cause or allow an illicit discharge, including permitting the escape of any potentially polluting substance into waters of the state, or into any municipal storm sewer system, or drainage way leading into any lake, wetland, or stream, or to permit the same to be so discharged to the ground surface. ... Any person who violates or refuses to comply with the provisions of this chapter shall be subject to a forfeiture of not less than fifty dollars ($50.00) nor more than two thousand dollars ($2000.00) and the costs of prosecution. Each day that a violation exists shall constitute a separate offense.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 71).
Full Breakdown
30 of the Sun Prairie Code of Ordinances, readopted in 2024 under Ordinance No. 11(5), Wisconsin Statutes. A stormwater management permit from the city engineering department is required before any zoning permit issues for a project that adds 20,000 square feet of cumulative impervious surface since August 22, 2001, requires a subdivision plat or a commercial or industrial certified survey map, or qualifies as redevelopment disturbing more than 4,000 square feet on a predominantly developed commercial, industrial, institutional or multifamily site. 040. Plan review runs 20 days for parcels under two acres and 45 days for larger parcels, and an approved permit is valid 180 days unless extended.
070 require new development to cut sediment loads by 80%, redevelopment by 40%, and to hold post-development infiltration volume to at least 90% of pre-development levels. 260 prohibit any illicit discharge of a potentially polluting substance, such as fuel, solvents, grease trap waste or chemical waste, into the municipal storm sewer system, a drainage way, lake, wetland, stream or the ground surface. A responsible person must immediately clean up any spill, report it to Public Health Madison and Dane County, and can be billed for the cost of remediation.
The city engineer or building inspector enforces both the permitting and discharge provisions, can post a stop-work order on an active project, and after 72 hours can enter the property to complete the required work and bill the owner, plus 5% interest over the city's borrowing rate.
Violations & Fines
Violating Chapter 15.30 carries a forfeiture of $50 to $2,000 plus costs of prosecution for illicit discharges, with each day of noncompliance a separate offense. Failing to obtain or follow a stormwater management permit can draw a stop-work order; if the permittee does not comply within 24 hours, the city may complete the corrective work itself and bill the owner at 5% over its borrowing rate, or pursue a court injunction under Section 15.30.090.
Frequently Asked Questions
Do I need a stormwater permit to build a new house in Sun Prairie?
What counts as an illegal discharge under Sun Prairie's stormwater ordinance?
How long is a Sun Prairie stormwater management permit good for?
What happens if I violate the stormwater ordinance more than once?
Sources & Official References
Other rules in Sun Prairie
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Stormwater Management in Nearby Cities
How other cities in Dane County handle stormwater management.