Municipal Stormwater General Permit - Stormwater Permit

We invite you to comment on the draft MS4 general permit.

Currently, the MPCA regulates Municipal Separate Storm Sewer Systems (MS4s) in approximately 226 municipalities under the MS4 general permit. An MS4 is a conveyance or system of conveyances (roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains, etc.) that is designed or used for collecting or conveying stormwater. Rain and snow melt (stormwater) flows over the many hard surfaces in urbanized areas (e.g., roads, sidewalks, driveways, parking lots, etc.) and picks up pesticides, fertilizers, oils, metals, road salt, sediment, trash, and other pollutants and carries them into MS4s that eventually drain to lakes, rivers, streams, and wetlands.

The MS4 general permit is designed to reduce the amount of pollutants entering state waters from stormwater systems. The permit includes requirements for public education, finding and stopping illegal dumping and other non-stormwater discharges to the MS4, overseeing construction activity, and implementing best management practices (BMPs) for municipal operations.