Information: We recently updated this page and will continue to work on information about MS4 stormwater management. If you have suggestions, we welcome comments using the comment box at the bottom of most pages in the manual.
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The municipal separate storm sewer system (MS4) stormwater program is designed to reduce the amount of sediment and pollution that enters surface and ground water from storm sewer systems. Public entities that own or operate an MS4 play a key role in preventing or reducing the negative impacts stormwater runoff has on our valuable water resources.

Proper stormwater runoff management in urbanized areas is especially important for restoring and protecting surface waters. Urbanized areas are more likely to have activities that contribute pollutants to stormwater runoff, like applying anti/deicing mixtures to roads; fueling vehicles; grease, oil, and other spills; landscaping; and using pesticides and fertilizers. Urbanized areas have a large amount of impervious surfaces, or surfaces that rain and snowmelt cannot pass through, such as streets, driveways, rooftops, parking lots and sidewalks. Stormwater runoff from these surfaces travels faster and in higher amounts, damaging rivers, streams, and wetlands; destroying aquatic habitats; increasing the amount of pollutants that enter surface waters; and limiting groundwater recharge.

2020 MS4 General Permit

2020 MS4 General Permit reissuance

Visit the MS4 General Permit reissuance page for updates on the new MS4 General Permit.

MS4 stormwater permit

Previous permits

Minimum Control Measures

Information: NOTE: Minnesota uses the term Stormwater Pollution Prevention Program (SWPPP) for MS4 stormwater, while several states and EPA may use the term Stormwater Management Plan (SWMP). These terms refer to the same thing.

When seeking to manage a Municipal Storm Sewer System (MS4), an effective Stormwater Pollution Prevention Program (SWPPP) has six different components known as Minimum Control Measures (MCMs). Follow this link to learn more about each MCM along with resources and guidance.

Total Maximum Daily Loads (TMDLs)

Total Maximum Daily Loads (TMDLs) are EPA approved amounts of pollutant loading that can occur and have a water body meet water quality standards. Follow this link to learn more about them along with guidance and resources.

Tools and resources

  • Municipal Separate Storm Sewer System (MS4) toolkit: A collection of resources for use by stormwater program staff. It is intended to help entities regulated under the MS4 program meet the requirements of the general permit. It offers a wide range of downloadable stormwater education information including sample fact sheets, newsletters, videos, and other resources.
  • MS4 Digital Document Library: Provides guidance to help local MS4 staff meet the requirements of the six Minimum Control Measures (MCMs) in the 2013 MS4 General Permit and assist with overall stormwater management. In addition to general guidance documents and photos/graphics, the Digital Document Library has example documents that stormwater staff are using to manage their stormwater pollution prevention programs (SWPPPs). All documents in the Digital Document Library are MPCA reviewed and available for anyone to download and use.
  • MS4 mapping tool: An interactive online map tool that can be used to view and explore Minnesota MS4 boundaries, defined urbanized areas, impaired waters, outstanding resource value waters, trout waters and approved TMDL study areas.

MS4 audit guidance

The U.S. Environmental Protection Agency (EPA) mandates the Minnesota Pollution Control Agency (MPCA) to evaluate MS4 permittees for compliance with the MS4 General Permit. The MPCA does this through compliance audits. To find out more information about the audit process see the pages below:

MPCA MS4 technical assistance

Other resources and documents

This page was last edited on 1 December 2022, at 22:34.