Waukesha County, WI Environmental Rules: Stormwater Management (2026)
Key Facts
- Permit trigger
- 3,000 sq ft land disturbance
- Also triggers permit
- 400 cubic yards excavation/fill
- Development trigger
- 0.5 acre new impervious surface
- Administering agency
- Land Resources Division (LRD)
- Town opt-out
- allowed under Sec. 14-331(a)
- Violation forfeiture
- $100 to $1,000 per day
Summary
Waukesha County requires a Storm Water Permit before any land-disturbing project on unincorporated land clears 3,000 square feet, moves more than 400 cubic yards of material, or adds half an acre or more of new impervious surface. The Land Resources Division administers the program, and any town can opt out by adopting its own ordinance that is at least as strict.
(a) Jurisdictional Boundaries. This ordinance applies to all unincorporated lands within the jurisdictional boundaries of Waukesha County, unless a town board: 1. Adopts an ordinance that complies with the minimum standards established by the Wisconsin Department of Natural Resources and is at least as restrictive as this ordinance, as determined by the LRD; and 2. Provides reasonable notice to the LRD of the effective date of the town ordinance and the enforcement contract(s), if not the LRD. ... (a) Construction Site Erosion Control. Unless otherwise exempted under sub. (c) below, a stormwater permit under sec. 14-334 shall be required and all erosion control and other provisions of this ordinance shall apply to all proposed land disturbing activity that meets any of the following: 1. Disturbs a total land surface area of 3,000 square feet or more; or 2. Involves excavation or filling, or a combination of excavation and filling, in excess of 400 cubic yards of material; or...
Full Breakdown
Article VIII of Chapter 14, adopted under Wis. 33, is Waukesha County's storm water and erosion control ordinance, administered and enforced by the Department of Parks and Land Use's Land Resources Division (LRD) under Sec. 14-330. Sec. 14-333(a) requires a storm water permit for construction-site erosion control whenever a project disturbs 3,000 square feet or more of land, moves more than 400 cubic yards of excavation or fill, disturbs 300 feet or more of an underground utility trench or open channel, involves maintaining an existing storm water best management practice, or is flagged by the LRD as likely to harm an environmentally sensitive area.
A separate permit trigger in Sec. 5 acres or more of new impervious surface built after May 28, 1998, or any new public or private road. Exemptions in Sec. 14-333(c) cover farming and pasturing activity, state- or federally-exempt projects, private on-site waste disposal system work, and one- and two-family home construction under the state Uniform Dwelling Code unless disturbance reaches one acre. Under the jurisdiction rule in Sec. 14-331(a), this county ordinance governs all unincorporated town land unless a town board adopts its own ordinance meeting or exceeding the DNR's minimum standards and notifies the LRD of its effective date, meaning a town can genuinely opt out of the county's storm water rules the same way towns can opt out of county zoning under Wis. 69.
Violations & Fines
Sec. 14-345 makes noncompliance with any permit condition, plan or BMP maintenance requirement an enforceable violation, letting the LRD combine remedies: a forfeiture of $100 to $1,000 per violation plus prosecution costs, with each day of noncompliance a separate offense; a stop-work order; permit revocation with site stabilization at the violator's expense; injunctive relief; and treatment as a nuisance per se. The LRD may also take emergency action and bill the cost, and may cite under Wis. Stat. § 66.0113.
Frequently Asked Questions
What projects require a Waukesha County storm water permit?
Which agency administers Waukesha County's storm water ordinance?
Can a town opt out of the county storm water ordinance?
What happens if I disturb land without a storm water permit?
Sources & Official References
Other rules in Waukesha County
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