Minnesota Department of Transportation

511 Travel Info

Municipal Separate Storm Sewer System (MS4)

Twin Cities Metro

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Terms explained

  • Best Management Practices (BMPs) - BMPs may include practices which prevent or reduce the pollution, prohibitions of practices, operating procedures and practices to control runoff, spillage or leaks, waste disposal or drainage from raw material storage.
  • EPA - U.S. Environmental Protection Agency - Federal environmental agency.
  • General Permit - a permit issued by MPCA to a category of permittees whose operations, activities, discharges, or facilities are the same or substantially similar.
  • Maximum Extent Practicable (MEP) is the statutory standard that establishes the level of pollutant reductions that an owner or operator of regulated MS4s must achieve. The USEPA has intentionally not provided a precise definition of MEP to allow maximum flexibility in MS4 permitting. The pollutant reductions that represent MEP may be different for each Small MS4, given the unique local hydrologic and geologic concerns that may exist and the differing possible pollutant control strategies. Therefore, each permittee will determine appropriate BMPs to satisfy each of the six minimum control measures through an evaluative process.
  • MPCA - Minnesota Pollution Control Agency - State environmental agency.
  • MS4 or Municipal Separate Storm Sewer System - a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains). Owned or operated by a state, city, county or district, association, having jurisdiction over stormwater that discharges to waters of the United States;
  • Outfall - the point where a Municipal Separate Storm Sewer System discharges from a pipe, ditch, or other conveyance to receiving waters, or toother Municipal Separate Storm Sewer Systems.
  • Storm Water - storm water runoff, snowmelt runoff, surface runoff and drainage.
  • Storm Water Pollution Prevention Program (SWPPP) - a compilation of BMPs to address the six minimum control measures and other provisions of the MS4 permit, that is designed and managed to reduce the discharge of pollutants from your MS4 to the maximum extent practicable as appropriate to your community.

 

Note: Definitions were simplified from those listed in the MPCA General Permit. For exact language, please refer to MPCA's website at http://www.pca.state.mn.us/