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.
What is a municipal separate storm sewer system (MS4)?
<a href="javascript:history.back()">Go Back</a>
- Why is a municipality regulated under the MS4 permit?
- What is a municipal separate storm sewer system (MS4)?
- Why is a municipality regulated under the MS4 permit?
Contents
2020 MS4 General Permit
- Link here to the 2020 MS4 General Permit - this is the wiki version of the permit
- Link here to the 2020 MS4 General Permit - this links to a pdf of the permit
- MS4 General Permit reissuance - Links to the 2020 MS4 General Permit reissuance page
MS4 stormwater permit
Previous permits
Minimum Control Measures
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).
- Minimum Control Measures 1 - Public Education and Outreach
- Minimum Control Measures 2 - Public Participation/Involvement
- Minimum Control Measures 3 - Illicit Discharge Detection and Elimination
- Minimum Control Measures 4 - Construction Site Stormwater Control
- Minimum Control Measures 5 - Post-Construction Stormwater Management
- Minimum Control Measures 6 - Pollution Prevention/Good Housekeeping
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
- 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.
- NEW Assessing total suspended sediment and total phosphorus removal efficiency of permittee owned/operated constructed stormwater ponds: guidance related to assessing the total suspended sediment (TSS) and total phosphorus (TP) removal efficiency of MS4 (Municipal Separate Storm Sewer System) permittee owned/operated ponds constructed and used for the collection and treatment of stormwater.
- Pollution prevention guidance fact sheets: A collection of links to a variety of Minnesota Stormwater Manual fact sheets on stormwater pollution prevention methods within MS4s.
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:
- Phase II MS4 audit process
- Self-audit guidance for Phase II MS4s
- General Stormwater Program Management - examples of how to track activities applicable to your SWPPP, enforcement response procedures
MPCA MS4 technical assistance
- MPCA MS4 website
- MPCA MS4 staff contact information
- MS4 case studies
- MS4 webinars and videos
- 2017 MS4 Technical Assistance and Outreach Needs Survey Results
- Checklist Documents and Examples of Procedures