Municipal stormwater (MS4)

MPCA plans for reissuance of the MS4 General Permit in Fall 2019

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Contact us. Having trouble finding who to contact with questions regarding your MS4?  Look under the Contacts tab below for a list of MS4 Technical staff and Individual MS4 staff assignments.


According to the 1996 National Water Quality Inventory, stormwater runoff is a leading source of water pollution and can harm surface waters such as lakes, rivers, streams and wetlands. Common pollutants in stormwater runoff include pesticides, fertilizers, oils, metals, pathogens, salt, sediment, litter and other debris. These pollutants are transported via stormwater from a variety of sources including construction projects, industries and urbanized areas.

Aerial photo of urban storm-water runoff in Minnesota - Photo by Todd Smith, MPCAManagement of stormwater runoff from urbanized areas is very important for restoring or protecting surface waters. Urbanized areas are associated with activities that contribute pollutants to stormwater runoff, such as application of anti/deicing compounds, vehicle fueling, spills, landscaping and lawn maintenance, and application of pesticides and fertilizers. Additionally, urbanized areas are characterized by large amounts of impervious surfaces, such as streets, driveways, roof tops, parking lots and sidewalks. Stormwater runoff from impervious surfaces travels faster and in larger quantities, which results in damage to rivers, streams and wetlands; destruction of aquatic habitats; and elevated pollutant levels reaching surface waters. Impervious surfaces also inhibit infiltration and subsequent groundwater recharge. Local public entities that own or operate a municipal separate storm sewer system (MS4) in urbanized areas play a key role in preventing or reducing the negative impacts stormwater runoff may have on Minnesota’s valuable water resources.

What is an MS4

A municipal separate storm sewer system (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 also:

  • owned or operated by a public entity (which can include cities, townships, counties, military bases, hospitals, prison complexes, highway departments, universities, etc.) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage districts, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act that discharges to waters of the United States;
  • designed or used for collecting or conveying stormwater;
  • which is not a combined sewer; and
  • which is not part of a publicly owned treatment works.

The MS4 General Permit is designed to reduce the amount of sediment and pollution that enters surface and ground water from storm sewer systems to the maximum extent practicable. Stormwater discharges associated with MS4s are subject to regulation under the National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS). Through the MS4 General Permit, the system owner or operator is required to develop a stormwater pollution prevention program (SWPPP) that incorporates best management practices (BMPs) applicable to their MS4. See the following fact sheet for additional information:

What criteria make an MS4 subject to stormwater regulation?

Only certain MS4s in Minnesota are subject to stormwater regulation under the Clean Water Act and Minnesota Rule 7090. The MPCA regulates the following:

  1. An MS4 located fully or partially within an urbanized area as determined by the latest Decennial Census and owned or operated by a publicly owned entity that has the potential resident capacity, bed count occupancy, or average daily user population of 1,000 or more.
  2. The entire jurisdiction of a city or township that is located fully or partially within an urbanized area as determined by the latest Decennial Census and owns or operates an MS4.
  3. An MS4 owned or operated by a municipality with a population of 10,000 or more.
  4. An MS4 owned or operated by a municipality with a population of at least 5,000 and discharges or has the potential to discharge stormwater to one of the following:
    1. A water identified as an outstanding resource value water as identified in Minn R. 7050.0180, subparts 3 and 6.
    2. A water identified as a trout lake or trout stream as identified in Minn. R. 6264.0050, subparts 2 and 4.
    3. A water listed as impaired under section 303(d) of the Clean Water Act, 33 U.S.C. § 1313.

Minnesota state rule (Minn. R. 7090) establishes criteria that can be applied to designate future MS4s under a formal process. MS4s designated through this process are required to obtain a NPDES/SDS stormwater permit. The public can petition the Commissioner of the MPCA for the designation of an MS4 based on the criteria established in Minn. R. 7090.1010 subpart 3.

Note: The cities of Minneapolis and St. Paul are Large MS4s (population of 250,000 or more) and received reissued individual NPDES/SDS permits on January 21, 2011.

Visit the Stormwater Program Rulemaking Web page for further details.

MS4 mapping tool

  • MS4 mapping tool: This is an interactive, online map tool that can be used to view and explore MS4 boundaries, defined urban areas, impaired waters, outstanding resource value waters, trout waters and approved TMDL study areas.

Impaired waters and TMDLs

MS4 Permittees with assigned Waste Load Allocations (WLA) as part of a Total Maximum Daily Load (TMDL) project approved by US EPA prior to the effective date of the latest Permit reissuance must address additional information in their Stormwater Pollution Prevention Program (SWPPP). Permittees must develop a compliance schedule that outlines interim milestones it will achieve during the permit term, strategies for continued implementation beyond the permit term, and target dates to achieve the applicable WLAs.

MS4 permit requirements

MS4s are required to develop and implement a stormwater pollution prevention program (SWPPP) to reduce the discharge of pollutants from their storm sewer system to the maximum extent practicable. The SWPPP must cover six minimum control measures.

The MS4 must identify best management practices (BMPs) and measurable goals associated with each minimum control measure. An annual report on the implementation of the SWPPP must be submitted each year.

Public process for SWPPPs

The MPCA will provide public notice and opportunity for public comment and hearing on each MS4s proposed SWPPP. Information on the public notice process is available at the MPCA Web page Public Notice Process for MS4 General Permit Applications.

Permit and program forms



Fact sheets and instructions

PDF icon 2013 Reissuance of the General NPDES/SDS Permit MNR040000 for Municipal Separate Storm Sewer Systems (MS4s)

PDF icon 2006 Reissuance of the General NPDES/SDS Permit MNR040000 for Municipal Separate Storm Sewer Systems (MS4s)

The reissued permit (MNR040000) became effective on August 1, 2013.

PDF icon Revisions to MS4 SWPPP Requirements:


Application items


Fact sheets and instructions

Microsoft Office document icon Part 2 Application for MS4 General Stormwater Permit (SWPPP Document)

Application for Authorization

PDF icon Filling out the SWPPP Document - FAQs

Individual MS4 SWPPP Document Submittal Dates

Office spreadsheet icon MS4 Permit TMDL Attachment Spreadsheet

Application supplement for MS4s with approved TMDL with a Waste Load Allocation (WLA) prior to the effective date of Permit.

PDF icon Guidance for MS4 TMDL Requirements




Office spreadsheet icon Master List MS4 Permit TMDLs Spreadsheet

Microsoft Office document icon Alum or Ferric Chloride Phosphorus Treatment Systems Form

Application supplement for MS4s with alum or ferric chloride phosphorus treatments systems.

If applicable, must be submitted with MS4 SWPPP Application for Reauthorization (SWPPP Document).



Additional items


Fact sheets and instructions

MS4 Annual Reports

Annual Reports are due June 30 of each year.



Office spreadsheet icon Summary of Stormwater Pond Sediment Testing Results (wq-strm4-79)

Construction Stormwater General Permit

Use these forms to meet permit requirements for stormwater pond dredging for maintenance purposes.

PDF icon Managing Stormwater Sediment Best Management Practice Guidance (wq-strm4-16)

Office spreadsheet icon MS4 Pond, Wetland and Lake Inventory Form

Inventory of all ponds, wetlands and lakes within permittee’s jurisdiction pertaining to 2009 Minnesota Session Law, Ch. 172. Sec. 28.

Must be submitted within 12 months of the date permit coverage is extended.


Minnesota Rules

Best management practices


Public Education and Outreach

Public Participation & Involvement

Illicit Discharge, Detection and Elimination

Construction Site Stormwater Runoff Control

Post Construction Stormwater Management

Pollution prevention/good housekeeping for municipal operations

2013 Permit Reissuance: Filling out the SWPPP document

MPCA staff held workshops following the reissuance of the General NPDES/SDS Permit MNR040000 for Municipal Separate Storm Sewer Systems (MS4s), which became effect August 1, 2013. These events provided information to assist MS4s in filling out their SWPPP Documents, which are due for submittal on October 30 (Group 1), December 2 (Group 2) and December 30 (Group 3). See the video below for a recorded version of one of these workshops.

Video timeline guide:

  • Intro
  • 0:06:31 - Municipal Stormwater Regulations, Revisions to 2013 MS4 Permit, SWPPP Document Format
  • 0:26:18 - Application Process & Public Notice, BMP Table Examples
  • 0:48:20 - Questions on SWPPP Document
  • 0:58:26 - Guidance Documents on the MS4 webpage
  • 1:00:23 - TMDL Requirements in MS4 Permits
  • 1:55:56 - Questions on TMDL Requirements

Stormwater financial assistance

The MPCA has various opportunities for receiving grants or loans for stormwater projects in Minnesota. Visit the following MPCA webpages for information on water-related financial assistance:

For more information regarding the MS4 Stormwater Program, please contact the following staff. If outside the metro area, please call 1-800-657-3864.


Duane Duncanson, 651-757-2323

Permit writer:

Cole Landgraf, 651-757-2880

Technical assistance and compliance enforcement:

Cole Landgraf, 651-757-2880
Scott Fox, 651-757-2368

TMDL/MS4 Permit technical assistance:

Rachel Olmanson, 651-757-2473

Application processing:

Melanie Preczewski, 651-757-2085

To see the MPCA staff assigned to your MS4, visit the Stormwater Manual’s Staff Assignment Page