National Pollution Discharge Elimination System

National Pollution Discharge Elimination System (NPDES)

Federal and state regulations require that the City of Northfield create a Storm Water Pollution Prevention Plan (SWPPP) that monitors storm water run-off and establishes policies to reduce contamination of local water bodies by run-off from streets and properties within city limits. Permitting, public education, and run-off reduction policies must also be developed. 

The federal National Pollutant Discharge Elimination System (NPDES) is run by the Environmental Protection Agency (EPA). The state NPDES program is run through the Minnesota Pollution Control Agency (MN PCA).

The EPA defines a Municipal Separate Storm Sewer System (MS4) as: "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 and 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 district, 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 (CWA) 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 (POTW)."

It is the desire of the City of Northfield to keep its storm sewer free of pollution in order to better serve the community and to maintain a healthy environment. The EPA has developed a National Menu of Storm Water Best Management Practices (BMPs) for MS4s. These are also referred to as the six minimum control measures. The City of Northfield is implementing programs and activities in order to execute these measures. 

The six best management practices are:

  1. Public Education and Outreach
  2. Public Participation and Involvement
  3. Illicit Discharge Detection and Elimination
  4. Construction Site Runoff Control
  5. Post-Construction Site Runoff Control
  6. Pollution Prevention and Good Housekeeping