MS4 Part 2 Permit Application Public Notice
The Minnesota Pollution Control Agency (MPCA) has placed the City of Chanhassen’s Stormwater Pollution Prevention Program (SWPPP) Document, submitted for coverage under the 2020 MS4 General Permit MNR040000, on a 30-day public notice comment period from August 3, 2021 to September 3, 2021The SWPPP Document can be found Here

Any public comments or requests can be sent to the City’s Water Resources Coordinator, Matt Unmacht at or 952-227-1168.  

  1. Matt Unmacht

    Water Resources Coordinator
    Phone: (952) 227-1168

What is Stormwater
Storm water generally refers to any water running off the landscape after a precipitation event. In an undeveloped
state, storm water runoff is a much smaller constituent of the water budget but as land becomes increasingly urbanized storm water runoff increases as well.

This change leads to increased runoff volumes, increased peak discharges, increased runoff velocities, increased flooding and lower baseflows in our streams and rivers. This has an impact on erosion, water quality and aquatic habitat. You can learn more about why storm water matters by going to the Minnesota Pollution Control Agencies Stormwater Program webpage.

Importance of Stormwater

In 1983 the Environmental Protection Agency published the Final Report of the Nationwide Urban Runoff Program as
well as the Results of the Nationwide Urban Runoff Program. These findings recognized the importance of urban runoff as it relates to the quality of our streams and lakes.

Largely as a result of this program, local units of government began to construct stormwater detention ponds as a means of treating stormwater and controlling the rates at which water leaves a site. As the science of stormwater management has grown, so have the practices used to manage and treat runoff.

As a homeowner and citizen you have an impact on the health of Chanhassen water bodies. Chemicals, lawn clippings, fallen leaves, and sediment can be introduced directly into the pond or flow into the street and will travel to our lakes, streams, and wetlands through storm sewers. The result of these components draining into our water bodies are excess nutrients and pollutants that can cause ugly algae blooms and unsafe drinking and swimming water.

Find out how you can play an active role in stormwater runoff prevention and management in your own backyard.