Definition of Stormwater Runoff
Stormwater runoff is rainwater that does not soak into the ground but instead runs off buildings, streets, parking lots, and other surfaces. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater runoff from naturally soaking into the ground.

The Problem with Stormwater Runoff
Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the waterbodies we use for swimming, fishing, and providing drinking water.