What is the MS4 permit? 

Often called an MS4 permit for short, the Municipal Separate Storm Sewer System permit program is a nationwide program created to manage and clean up stormwater, prevent pollution and protect lakes and streams. A Municipal Separate Storm Sewer System is a system that collects or moves stormwater. This includes streets, ditches, stormwater ponds, curbs, gutters, storm drains, and underground pipes that make up the storm sewer. These systems are referred to as separate because they are separate from the system that collects and treats household wastewater. Wastewater from sinks, tubs, and toilets is sent to a wastewater treatment facility or a septic system where bacteria and other pollutants are removed. Stormwater runoff often flows to lakes and rivers untreated.

Why have a permit?

Compared to natural areas, lakes and streams in developed areas have a higher risk of begin polluted. Developed areas contain many hard surfaces like roads, driveways, roofs, and parking lots. These hard surfaces are impervious, meaning they don’t let rainwater soak through. Water drains off hard surfaces quickly, flows into storm drains, and is carried to the nearest lake, stream, or pond as stormwater runoff.

As stormwater flows across surfaces, it picks up pollutants such as oils, chemicals, bacteria, and sediment. When the polluted runoff flows into lakes and streams, it causes muddy waters, algae blooms, and bacteria problems affecting wildlife and recreational activities like fishing, swimming, and boating.

Who needs a permit?

The Municipal Separate Storm Sewer System program helps reduce the amount of pollutants flowing into lakes and streams from stormwater systems. In Minnesota, permits are issued by the Minnesota Pollution Control Agency. Counties, many cities, college campuses and other areas of land with high amounts of stormwater draining from them are required to participate, get a permit, and create a plan to prevent stormwater pollution. View Carver County's Stormwater Pollution Prevention Plan. A printed copy is available at the Planning and Water Management counter at the Carver County Government Center 600 East 4th. St. in Chaska. 

Permit activities 

Permit holders are expected to complete these and more activities to help protect water:

• Use street sweepers to clean streets of leaves in fall and spring. Leaves have lots of phosphorus. If left on streets, leaves can wash off into lakes where the phosphorus will cause algae blooms. 
• Educate citizens about home and lawn care habits that protect water. For example, blowing grass clippings back into your lawn after mowing or adopting a stormdrain.
• Find and stop illegal discharges to storm sewer systems. Only rainwater should flow down storm drains. Soapy water, paint, septic tank discharge, chlorinated pool water are all examples of illegal discharges to storm drains.
• Prevent sediment pollution from construction sites. Construction sites have a lot of bare soil that easily wash away. Practices like silt fences and erosion control blankets, keep soil from moving around on site and from washing off site.
• Ensure new developments have practices that collect and treat stormwater runoff. Practices can include raingardens, permeable pavers, and stormwater ponds.

Role of residents 

The Municipal Separate Storm Sewer program is important, but residents also have a part to play in protecting lakes and rivers. It’s very important to keep storm drains clean and that only rain goes down the drain.  Follow these tips to prevent pollution from washing down storm drains.

• Don’t dump anything into storm drains. If you see something flowing into a storm drain that shouldn’t be, contact your city.
• Take used oil, unwanted chemicals and other household hazardous wastes to the Carver County Environmental Center or special waste drop off.
• Pick up after your pet and place waste into the garbage.
• Wash your car at a professional car wash. The water there goes to wastewater treatment facilities.
• Keep your surfaces clean. If you spill paint, oil, salt, etc. clean it up.
• De-chlorinate your pool water before draining. Chlorine is not good for wildlife.
• Sweep or blow leaves, grass clippings and dirt off driveways and sidewalks.