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Stormwater Program for Municipal Separate Storm Sewer Systems (MS4)


A reminder to MS4 permittees: The 2013 MS4 Annual Report, which details permit activities from 2013, is due for submittal by Monday, June 30, 2014.  Further information as well as the Report Form can be found on the MS4 Annual Reports page.

Who to Contact

Having trouble finding who to contact with questions regarding you MS4?  Any member of the MS4 staff, listed under the Contacts tab below is available to answer your questions or direct you to the appropriate staff member.  Additionally, you can find which staff member your MS4 is assigned to on the MS4 Permit Staff Assignments page.  The list can be sort alphabetically by clicking on the header: MS4 Name. 



According to the 1996 National Water Quality Inventory, stormwater runoff is a leading source of water pollution. Stormwater runoff can harm surface waters such as rivers, lakes, and streams which in turn cause or contribute to water quality standards being exceeded.

Stormwater runoff can change natural hydrologic patterns, accelerate stream flows, destroy aquatic habitats, and elevate pollutant concentrations and loadings. Development substantially increases impervious surfaces thereby increasing runoff from city streets, driveways, parking lots, and sidewalks, on which pollutants from human activities settle.

Aerial photo of urban storm-water runoff in Minnesota - Photo by Todd Smith, MPCACommon pollutants in runoff include pesticides, fertilizers, oils, metals, pathogens, salt, sediment, litter and other debris are transported via stormwater and discharged - untreated - to water resources through storm sewer systems.

The Stormwater Program for MS4s 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 regulated through the use of National Pollutant Discharge Elimination System (NPDES) permits. NPDES permits are legal documents. Through this permit, the 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 is an MS4

A municipal separate storm sewer system is a conveyance or system of conveyances (roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains):

  • Owned or operated by a state, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) 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.

Types of small MS4s

There are three categories of regulated small MS4s: mandatory, designated and petition. Small MS4s include municipalities, townships, counties, military bases, hospitals, prison complexes, highway departments, and universities.

  1. Mandatory MS4s: MS4s in urbanized areas as defined by the 2000 Census are required to obtain a NPDES/SDS stormwater permit. An "urbanized area" is defined as a land area comprising one or more places (“central places”) and the adjacent densely settled surrounding area (“urban fringe”) that together have a residential population of at least 50,000 and a density of at least 1,000 people per square mile. The definition also includes any other public storm sewer system located fully or partially within an urbanized area.

    The following list identifies Minnesota’s mandatory small MS4 cities, townships, and counties. The list also includes non-traditional mandatory MS4s identified by MPCA staff as requiring permit coverage. Non-traditional MS4s are publicly owned systems at military bases, hospitals, prisons, universities, highways and other thoroughfares.

Note: The cities of Minneapolis and St. Paul received individual stormwater permits in 2000.

  1. Designated MS4s:  MS4s outside of urbanized areas that have been designated by the MPCA for permit coverage under Minn. R. ch 7090 are required to obtain a NPDES/SDS stormwater permit. MS4s designated by rule are cities and townships with a population of at least 10,000; and cities and townships with a population of at least 5,000 and discharging or the potential to discharge to valuable or polluted waters. These designated MS4s are required to obtain permit coverage by February 15, 2007.

The rules also establish criteria that can be applied to designate future MS4s under a designation process identified in the rule. Visit the Stormwater Program Rulemaking Web page for details.

  1. Petition MS4s:  MS4s that are designated through the petition process under Minn. R. ch. 7090 are required to obtain a NPDES/SDS stormwater permit. The public can petition the Commissioner for the designation of an MS4 based on the designation criteria established in the rules. Visit the Stormwater Program Rulemaking Web page for details.

Maps of MS4s

MS4 mapping tool

  • MS4 mapping tool: This is an electronic map tool using Geographic Information Systems (GIS) technology.
    Note: This is best viewed using Internet Explorer 5.0 or higher or Netscape 6.0 or higher, with pop-up blockers disabled and screen resolution set to 1024x768 or higher.
  • PDF Document Guidance Document: Use of the MS4 Mapping Tool (wq-strm4-73) Minnesota Map showing regional areas for Mandatory MS4s

Mandatory MS4s

Note: The maps above for Duluth, Minneapolis/St. Paul and St. Cloud areas are interactive.  Once you've opened one of those maps, click on a numbered area within the grid on the map to open a new map showing details of the grid area.

Designated MS4s

Maps of MS4s designated under the Minnesota Rules Chapter 7090 are available on the Stormwater Program Rulemaking Web page.

Special waters and impaired waters

The MS4 General Permit for MS4s near specially-protected waters require additional controls, conditions or an individual permit:

  • MS4s that discharge near waters with qualities that warrant extra protection (special waters) must use additional best management practices and enhanced runoff controls (see permit Part IX).
  • MS4s that discharge near an “impaired water” for which there is a total maximum daily load (TMDL) allocation for stormwater sources must meet special conditions (see permit Part IV.D).

The MPCA has several documents and an interactive map called Special Waters Search to help owners and operators of MS4s identify those waters near their MS4 that may require extra protections or an individual permit. The specific requirements are outlined in the MS4 General Permit.


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 Document 2013 Reissuance of the General NPDES/SDS Permit MNR040000 for Municipal Separate Storm Sewer Systems (MS4s) (wq-strm4-59k)


PDF Document 2006 Reissuance of the General NPDES/SDS Permit MNR040000 for Municipal Separate Storm Sewer Systems (MS4s) (wq-strm4-51)

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

PDF Document Revisions to MS4 SWPPP Requirements: (wq-strm4-49g)


Application Items


Fact Sheets and Instructions

MS Word Document MS4 SWPPP Application for Reauthorization (SWPPP Document) (PDF Version) (wq-strm4-49a)

Application for Reauthorization

PDF Document MS4 SWPPP Application for Reauthorization (SWPPP Document) Example (wq-strm4-49b)
PDF Document Filling out the SWPPP Document - FAQs (wq-strm4-49h)

Individual MS4 SWPPP Document Submittal Dates

MS Excel Document MS4 Permit TMDL Attachment Spreadsheet (wq-strm4-49c)

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

PDF Document Guidance for MS4 TMDL Requirements (wq-strm4-49f)
PDF Document TMDL FAQs (wq-strm4-49k)
MS Excel Document Master List MS4 Permit TMDLs Spreadsheet (PDF Version) (wq-strm4-49d)
MS Word Document Alum or Ferric Chloride Phosphorus Treatment Systems Form (PDF Version) (wq-strm4-49e)

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.

Use SWPPP Pollution Prevention Guidance on the right. To update your current SWPPP to reflect changes in needs or when completing Annual Reports to aid in assessment of appropriateness of identified BMPs.

PDF Document MS4 Inspection and Recordkeeping (wq-strm4-05)

PDF Document Pollution Prevention and the MS4 Program (wq-strm4-26)

MS Excel Document Summary of Stormwater Pond Sediment Testing Results (wq-strm4-79)

Construction Stormwater General Permit

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

PDF Document Managing Stormwater Sediment Best Management Practice Guidance for Municipalities (wq-strm4-16)
MS Excel Document MS4 Pond, Wetland and Lake Inventory Form (PDF Version) (wq-strm4-30)

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.


Guidance and BMPs

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:

Duane Duncanson, 651-757-2323

Technical assistance and compliance enforcement:

Scott Fox, 651-757-2368
Claudia Hochstein, 651-757-2881
Cole Landgraf, 651-757-2880
Dan Miller, 651-757-2246
Rachel Stangl, 651-757-2879

Individual MS4 Staff Assignments

TMDL/MS4 Permit technical assistance:

Josh Stock, 651-757-2235

Application processing

Wendy Gardner-Pritchard, 651-757-2090

Last modified on May 19, 2014 13:36