What is Stormwater Runoff?

Stormwater runoff is the result of precipitation from rain or snow flowing over the ground. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater from naturally soaking into the ground and filtering out pollutants. These pollutants eventually work their way into our watershed.

We think of rainwater as “clean” water.  But rain water picks up everything in its path and carries the filth along until it  flows untreated directly into our waterbodies and sometimes directly into our water supplies.  This fast flow of rainwater erodes streambanks and streambeds, and carries suspended particles and sediment. Erosion can be gradual, or can occur rapidly through a sudden collapse of a streambank. Debris picked up by rainwater often clogs culverts and drains and Stormwater conveyances may fail. Flashflooding also increases because the quantity of water runoff is greater than stormwater system can handle.

Additional information about stormwater runoff is available through the EPA stormwater runoff website.