MPCA MS4 Regulations

BRRWD MS4 Boundary Map

Municipal Stormwater Management

Rain and melting snow create runoff as they move across the landscape to lakes, streams, rivers, and wetlands. In urban areas, most stormwater falls on streets, sidewalks, parking lots, roofs, and other hard surfaces and carries pesticides, fertilizers, oils, metals, salt, bacteria, litter, yard waste, sediment, and other materials down storm drains and into lakes and streams. Unlike wastewater, most stormwater is not treated before it empties into nearby bodies of water. Not surprisingly, stormwater runoff is a leading source of water pollution.

In addition to the contaminants it carries, stormwater runoff from hard, urban surfaces travels faster and in larger quantities, the force of which damages rivers, streams and wetlands and can destroy habitats for fish and other aquatic life. Impervious surfaces also prevent stormwater from filtering into the ground and recharging groundwater.

A public entity’s stormwater system (ditches, stormwater ponds, curbs and gutters, storm drains, catch basins, storm sewer pipes, and so on) is called a municipal separate storm sewer system (MS4). This does not include systems where wastewater and stormwater are combined. The Minnesota Pollution Control Agency (MPCA) regulates MS4 systems as mandated by the federal Clean Water Act with the goal of improving water quality by reducing pollutants in stormwater discharges. MS4 regulations require that owners/operators educate citizens on stormwater management issues and include them in solving stormwater problems, make plans to detect and stop illicit discharges, control runoff on construction sites, and more.

The MPCA has identified the portion of the Buffalo-Red River Watershed District (BRRWD) near Moorhead and Dilworth as a MS4 area.  Additional rules apply to projects in this area.  See the BRRWD MS4 Boundary Map on this page.  If you have a project in this area draining to a BRRWD project, additional rules apply.  See Section 8 of the BRRWD Rules.

The MPCA conducts outreach efforts intended to educate city staff, contractors, governmental units and their constituents on the State of Minnesota Construction Stormwater (CSW) permitting and erosion and sediment control requirements associated with construction activities. These requirements apply on sites disturbing more than 1 acre of soil and on sites disturbing less than one acre of soil but part of a larger plan; for example, a subdivision where cumulatively, the construction activities on all of the lots would result in more than one acre of soil disturbance.

Included below are educational materials and tools that can assist you in meeting the MS4 requirements. Links have been provided below that hit the highlights of the Construction Stormwater (CSW) program. They can be useful in understanding the CSW permitting requirements.

  • Construction Stormwater Brochure
    https://www.pca.state.mn.us/sites/default/files/wq-strm2-111.pdf
    We developed a brochure that may be of use to the counties and would be an easy thing to hand out. It covers the permitting requirements and the “Why” on one side and on the inside it has a 10 steps to compliance that could be very helpful to the permittees, developers, builders, etc.