Illicit Stormwater Discharges

If stormwater flows off your property, you may be adding pollutants to stormwater runoff. The following information can help you reduce stormwater runoff and pollutant concentrations that result from business operations. 

MSD LogoMetropolitan St. Louis Sewer District

24-hour Hotline: 314.768.6260 Web Site:

What is an Illicit Discharge? 

An illicit discharge is any discharge to the storm sewer system that is not composed entirely of stormwater (rainwater or snow melt), except for discharges allowed under a National Pollutant Discharge Elimination System (NPDES) permit. * 

An illicit discharge or connection may result from:

 • Illegal dumping practice i.e., improper disposal of hazardous waste.

 • A direct connection from the sanitary sewer to the storm sewer. 

• Indirect connection from improper surface discharges to the storm sewer i.e., hosing down outdoor areas on a parking lot or other impervious surface. 

How can I prevent illicit discharges or connections from my business? Since industrial facilities have the potential to impact stormwater by improper day-to-day activities, implementing Best Management Practices (BMPs) is a tool you can employ to minimize pollution and protect our environment. Here are a few simple practices you can follow: 

*NPDES permits are issued by the Missouri Department of Natural Resources 

Waste Management 

Good housekeeping is required to keep pollutants out of stormwater.

 • Recycle or properly dispose of waste. 

• Place waste receptacles and materials under cover, if possible, or cover with a lid. 

• Empty receptacles frequently and provide an adequate supply. 

• Regularly inspect waste receptacles for structural damage or leaks.

 • Keep waste collection areas clean and clean up spills immediately.

 • Properly label all waste to ensure appropriate handling and disposal.

 • Keep storm drains clear of debris, dirt, or other waste.

 • Store containers under cover or ensure lids are clean and leak proof. 

Facility and Grounds 

Implement facility inspection protocols that protect stormwater quality such as: 

• Maintain a site plan of the facility identifying sanitary and storm sewer connections.

 • Label storm drains on site to discourage improper disposal and train employees on BMPs. 

• Verify interior floor drains are plumbed to the sanitary sewer.

 • Regularly inspect equipment and/or vehicles for leaks. 

• Minimize the use of landscaping chemicals and ensure proper disposal of yard waste.

 • Routinely sweep parking lots and pick up litter. 

Fleet Maintenance and Vehicle Washing 

Oil, grease, dirt, wastewater and other fluids can pollute stormwater runoff when we service our vehicles and equipment. You should: 

• Perform activities indoors if possible, to protect from rain/snow. 

• Store equipment or vehicles under cover to protect from the elements.

 • Service and maintain vehicles and equipment regularly. 

• Check for leaks and repair promptly. Use a catch pan to capture leaks and drips. 

• During cleaning, wash water discharges into the sanitary sewer.

 • Wash bay is covered to keep stormwater out of the sanitary sewer. 

• Use biodegradable, phosphate free detergents.

 • Post signs to clearly identify the vehicle/equipment cleaning area. 

Spill Prevention and Cleanup 

Develop a policy to address the impact from an accidental spill. 

• Store hazardous materials away from high traffic areas to avoid spills.

 • Keep all outdoor drums and tanks in a bermed area.

 • Contain and clean up all spills immediately using dry methods. 

• Do not hose down spill materials to the storm sewer. 

• Use absorbents and sweep to pick up fluids. 

• Keep spill kits stocked and readily accessible.

 • Train employees on cleanup procedures. 

Metropolitan St. Louis Sewer District 

24-Hour Hotline: 314.768.6260 

Web Site: 

Why Should I Care? 

Stormwater runoff can easily become polluted by metals, chemicals, sediment, fertilizers, and trash it picks up as it flows. Many industrial activities contribute to stormwater pollution (such as metal grinding and polishing, vehicle/equipment maintenance, improper disposal of hazardous waste, and more) during daily operations. Waste, residues, and byproducts from these activities enter storm drains, and flow into creeks and rivers harming aquatic life and impacting water quality. 

What is MSD doing? 

We continue to develop and implement programs to reduce non-stormwater discharges into area creeks and streams.

• Annually, a stream team surveys 280 miles of creeks and channels for dry weather discharges.

 • Regulate and/or permit all industrial users served by the District to ensure compliance with federal and local regulations. 

• Monitor industrial waste discharge activities of users by conducting routine industrial pretreatment inspections. 

Who We Are 

The Metropolitan St. Louis Sewer District's (MSD) mission is to responsibly provide sewer service and stormwater management to protect the public’s health and safety. 

Established by a vote of the citizens of the City of St. Louis and St. Louis County in 1954, MSD today serves a population of approximately 1.4 million. MSD is responsible for one of the largest and most complex sewer systems in the United States, represented by the maintenance and operations activities we perform on over 8,900 miles of sewer lines. MSD’s 8 wastewater treatment facilities process an average of 312 million gallons of wastewater every day. 

At MSD, we work closely with the communities we serve and prioritize our resources to make the greatest impact for our customers in the shortest time possible. With a clear focus on customer service, we establish priorities and deliver effective performance. We will continue to build and maintain the infrastructure our St. Louis community needs now and for the future. 

Metropolitan St. Louis Sewer District 2350 Market Street St. Louis, MO 63103 Phone: 314.768.6200