What happens to dirt in stormwater?

When soil, dirt, sand, clay, or other tiny bits of earth end up in stormwater, we then call it “sediment” because those pieces can eventually settle out to the bottom of a body of water. However, moving water such as stormwater runoff through our neighborhoods and cities keeps the sediment from settling and can cause serious problems for water quality.

What does sediment do in the environment?

Sediment pollution creates many issues in the environment; here are just a few!

• Clogs fish gills and suffocates small insects and other animals;
• Creates murky, cloudy water that blocks sunlight from reaching plants;
• Transports hundreds of other chemicals and pollutants to our drinking water that are hitching a ride on the sediment;
• Encourages growth of toxic algae that can make people and animals sick;
• Completely changes the course of a river or stream by depositing new banks!

What can we do to reduce stormwater pollution from sediment?

Sediment can come from many sources, such as construction sites or digging, erosion when vegetation has been removed, and even just dust and grime from your driveway, car, and sidewalk. You can help keep this dirt from getting in our streams and rivers by sweeping up instead of hosing down!

If you see muddy brown water being deliberately sent into the storm drain like in the photo below, or if you see lots of sediment coming from a construction site, call your local water department (contact info here) and let them know right away.