Stormwater runoff is rain water or snowmelt that doesn’t soak into the ground. Instead, it flows across the land surface, picking up pollutants along the way before entering local water bodies. As it travels across the land and impervious surfaces (roofs, driveways, sidewalks, roads), stormwater carries trash and pollutants such as sediment, nutrients, pesticides, bacteria, oil, and gasoline to local lakes, streams, rivers, and wetlands. To see how this happens, see the illustration below!
These pollutants can make water unsafe for drinking and water-based recreation. People and animals may become sick from drinking the water or from eating the fish from contaminated lakes, rivers, and streams.Stormwater runoff also contributes to flooding and can lead to expensive repairs for municipalities and homeowners.