Stormwater Frequently Asked Questions

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Q: What is stormwater runoff?

A: Stormwater runoff occurs when precipitation from rainfall event or snowmelt flows over the ground flowing into streams, rivers, ponds, lakes and oceans.


Q: How does stormwater runoff become polluted?

A: Rainwater or snowmelt encounters materials on the ground including loose sediment, oil and grease, heavy metals, toxic household cleaners, organic debris, excessive nutrients, bacteria and viruses and litter. Often the chemicals, oils and trash are carried in in the runoff and discharged to streams rivers and lakes. To find out more about stormwater visit our Educational Resources  page.


Q. Is stormwater runoff treated at a waste water facility?

A: Sewer systems and stormwater drains are two different things. The water that goes down your house drain flows to a wastewater treatment plant where it is treated and filtered, then released to a receiving stream. But water that flows down driveways and streets into a gutter or ditch is not treated and flows directly to a lake, river or stream. The pollutants in the stormwater, are discharged to the lake, river or stream too.

Q: What is an Illicit Discharge?

A: An illicit discharge is the illegal dumping of any pollutant into the storm drain system. Pollutant examples include, but are not limited to, pesticides, fertilizers, weed killers, detergents, oils and grease, litter and illegal activities such as dumping materials into storm drains or connecting waste water pipes into storm drains.

Q: How do I report an Illicit Discharge?

A: We need your help. If you see someone dumping chemicals or trash, a spill or discolored water in the MoDOT right-of way, please let us know. Information about reporting an illicit discharge can be found here: Report A Stormwater Concern Page.

Q: what can we do to prevent stormwater pollution?


  • Don't litter, put trash in a closed receptacle
  • Rake leaves and compost or mulch yard waste
  • Use fertilizers and herbicides sparingly
  • Repair leaks and dispose of vehicle fluids and batteries at designated drop-off locations.
  • Have your septic tank serviced regularly
  • Pick up pet waste and dispose of it properly
  • Direct gutter downspouts into grassy areas and away from driveways
  • Participate in community clean-ups and litter pick-ups
  • Help educate people in your community
  • Find out where you can recycle items or properly dispose of household hazardous waste here


Q: What does MoDOT do to keep our waters clean?

A: MoDOT takes our responsibility to reduce water quality impacts from our construction, maintenance and other roadway activities seriously. Whenever one acre or more of land is disturbed for roadwork, it is MoDOT’s responsibility to implement control measures to prevent the excessive release of sediment and pollutants into nearby waterways. We use advanced technology (calibrated salt/sand spreaders, etc.) to reduce the amount of salt and sand used on snowy and icy winter roads. The department also promotes the Adopt-A-Highway program that encourages community and area groups to pick up litter from the highways.



Q: Does MoDOT also utilize stormwater best management practices?

A: Yes, we have a stormwater management plan for the department and we have continuous training and education for our employees and contractors. MoDOT requires that all environmental permits be in place before construction begins. Contractors are required to abide by all environmental regulations and laws when performing road construction activities. These include air pollution, spill response, solid waste management, and water pollution control. We use best management practices to reduce the amount of water quality impacts from our construction projects (MoDOT incorporates specific requirements and procedures into our construction Standard Specifications and Job Special Provisions).