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MS4 Permit

The City of Isanti is committed to protecting local water quality through the management of its Municipal Separate Storm Sewer System (MS4). This program is regulated by the State of Minnesota under the National Pollutant Discharge Elimination System (NPDES) permit, a framework developed from the federal 1972 Clean Water Act.

The Minnesota Pollution Control Agency (MPCA) initiated the MS4 program in 2007. The City of Isanti was first issued its MS4 permit in 2016, authorizing the City to discharge stormwater while implementing Best Management Practices (BMPs) to reduce the reach of pollutants into our local water bodies.

What is an MS4?

An MS4 is a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) that is:

  • Owned or operated by a public body.

  • Designed or used for collecting or conveying stormwater.

  • Not a combined sewer or part of a Publicly Owned Treatment Works (sewage treatment plant).

Our Commitment to Water Quality

As part of our permit requirements, the City maintains a Stormwater Pollution Prevention Program (SWPPP). Key focus areas include:

  • Public Education: Informing residents and businesses on how to prevent pollutants from entering storm drains.

  • Illicit Discharge Detection and Elimination (IDDE): Identifying and stopping the discharge of non-stormwater substances (such as oil, chemicals, or grass clippings) into the system.

  • Construction Site Oversight: Ensuring erosion and sediment control BMPs are followed during land-disturbing activities.

  • Post-Construction Management: Long-term maintenance of infrastructure like the pollinator gardens at Bluebird Park, which provide natural filtration for runoff.

Annual Reporting and Public Involvement

The City is required to submit an annual report to the MPCA and the Isanti City Council. This report summarizes the previous year's activities and identifies any illicit discharges that occurred within City limits.

  • View the 2021 MS4 Permit 

External Resources

For more information on state-wide stormwater regulations and permitting, visit the Minnesota Pollution Control Agency (MPCA) website:

Minnesota NPDES/SDS Stormwater Permitting

Report a Concern

If you witness an illicit discharge (e.g., someone dumping chemicals or debris into a storm drain), please contact the Community Development Department at763-444-5512 or permits@cityofisanti.us