icon for MS4 stormwater

Important Links

  1. MS4 General Permit. This permit went into effect on August 1, 2013.
  2. MS4 General Permit Application Information
  3. Total Maximum Daily Loads (TMDLs)
  4. MS4 Annual Report

Link to MS4 website


image of MS4 home page
Link to MPCA MS4 home page

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.

Common 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:

MS4 staff contact information

Supervisor/Permit writer:
Duane Duncanson, 651-757-2323

MS4 Permit technical assistance and compliance enforcement:
Scott Fox, 651-757-2368
Cole Landgraf, 651-757-2880
Megan Handt, 651-757-2843

MS4 Permit technical assistance, TMDL
Josh Stock, 651-757-2235

For New MS4s:
Click here to view the list of staff assignments
This list is subject to change.

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.

MS4 mapping tool

  • MS4 mapping tool is an electronic map tool using Geographic Information Systems (GIS) technology.