Sun Prairie, WI Environmental Rules: Erosion Control (2026)
Key Facts
- Permit trigger
- 4,000 sq ft disturbed or 12% slope
- Fill/excavation trigger
- 400 cubic yards or more
- Minor project review
- Decision within 7 days
- Major project review
- 20-45 days depending on acreage
- 1-2 family exemption
- Unless disturbance exceeds 1 acre
- Minor-project first offense
- $100 to $250 forfeiture
Summary
Sun Prairie requires an erosion control permit before disturbing 4,000 square feet or more of land, grading on slopes steeper than 12%, or moving 400 cubic yards of dirt, and separately bans letting eroded dirt or sediment reach adjacent land, streets or waterways from any site.
An area of four thousand (4,000) square feet or greater that will be disturbed by grading, removal of protective ground cover or vegetation, excavation, land filling or other land disturbing activities, or activities on a slope steeper than twelve percent (12%); ... In addition to the permit requirements set forth in this chapter, no person shall cause or permit erosion or the tracking or dropping of dirt or sediment deposits upon adjacent lands, public streets or bodies of water from any land, whether or not otherwise subject to this chapter. ... A forfeiture of not less than one hundred dollars ($100.00), nor more than two hundred fifty dollars ($250.00), together with the costs of prosecution and any costs incurred by the city in connection with the claims of third parties;
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
030: a subdivision plat or certified survey map, disturbance of 4,000 square feet or more, work on a slope steeper than 12%, excavation or fill of 400 cubic yards or more, construction of a public street or utility line, or disturbance of more than 100 lineal feet of a road ditch or drainage channel. 035(B). Larger projects, 20,000 square feet or more or on steep slopes, must submit a full control plan with site maps, soil-loss calculations under the universal soil loss equation, and a construction schedule; smaller residential lots can instead file the shorter erosion control checklist plan.
Minor projects get a decision within seven days, major projects under two acres within 20 days, and larger major projects within 45 days. 070(C) flatly prohibits causing or permitting erosion, or the tracking or dropping of dirt or sediment onto adjacent land, public streets or bodies of water, from any site, whether or not that site is otherwise subject to the chapter. The city engineer or building inspector enforces the chapter, can post a stop-work order, and after 72 hours may complete corrective work and bill the landowner at 5% over the city's borrowing rate.
Violations & Fines
Minor-project violations of Chapter 15.28 draw a forfeiture of $100 to $250 for a first offense, $250 to $500 for a second, and $500 to $1,000 for later offenses; major-project violations run $200 to $500, then $500 to $1,000, then $1,000 to $1,750, plus prosecution costs each time, with every day of continued violation counted separately. The city may also seek a court injunction.
Frequently Asked Questions
Does building a house trigger an erosion control permit in Sun Prairie?
How much dirt can I move before needing a permit?
Is it illegal to let dirt wash onto my neighbor's yard during construction?
What are the fines for an erosion control violation in Sun Prairie?
Sources & Official References
Other rules in Sun Prairie
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Erosion Control in Nearby Cities
How other cities in Dane County handle erosion control.