Marathon County, WI Environmental Rules: Stormwater Management (2026)
Key Facts
- Applies to
- Unincorporated county land only
- Approval needed
- DNR + Commissioner/town engineer
- Governing chapter
- Ch. 18, Land Division Code
- Excluded
- Wausau, Mosinee, Rothschild, other cities
Summary
Marathon County requires every major subdivision built on unincorporated land to have its stormwater management plan approved by the DNR and county or town engineer, using facilities like retention ponds or infiltration trenches, before final plat approval.
18.008.03.Stormwater management requirements.A.The design and construction of stormwater management facilities shall require the review and approval of the DNR, Commissioner and town engineer if applicable, in accordance with all other applicable laws and regulations.1.Allowable types of stormwater management facilities include but are not limited to:a.Retention ponds.b.Detention basins.c.Underground storage tanks.d.Rooftop storage areas.e.Parking lot storage areas.f.Infiltration trenches/recharge ditches.g.Swales/buffer strips...
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 59).
Full Breakdown
Marathon County's Land Division and Surveying Code (Chapter 18) requires major subdivisions to submit a stormwater management plan for review and approval by the DNR, the County Commissioner, and the town engineer where applicable. Acceptable facility types include retention ponds, detention basins, underground storage tanks, rooftop or parking-lot storage, infiltration trenches, and buffer swales. The code applies only to unincorporated Marathon County land under Section 18.001.04: it does not reach inside Wausau, Mosinee, Rothschild or the county's other incorporated cities and villages, and a town's own subdivision ordinance controls if it is more restrictive than the county's.
Violations & Fines
Final plat approval can be withheld if a developer hasn't complied with the approved stormwater and soil erosion control plan in any prior phase, under Section 18.009.05, until the deficiency is fixed.
Frequently Asked Questions
Does Marathon County's stormwater rule apply in Wausau or Mosinee?
What stormwater facilities does the county code accept?
Sources & Official References
Other rules in Marathon County
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