Minnesota MS4 Stormwater Permit Program Statewide Standards

Under the federal Clean Water Act and Minn. Stat. 115.03, MPCA issues a general MS4 permit to municipal separate storm sewer systems serving urbanized areas. Permittees must implement six minimum control measures: public education, public participation, illicit discharge detection, construction site runoff control, post-construction stormwater management, and pollution prevention for municipal operations. Cities must adopt ordinances regulating sediment, erosion, and volume control on construction sites disturbing one acre or more, generally requiring 1.0 inch volume retention in many areas. Local rules may be stricter but must meet MPCA's permit baseline.

MPCA may issue administrative penalty orders, civil fines up to $25,000 per day per violation under Minn. Stat. 115.071, and require corrective discharge controls.