A watershed is an area of land where all water drains to a particular waterbody, usually a stream, river, or the ocean. Watersheds cover the entire land surface of the earth. Watersheds contain homes, neighborhoods, cities, forests, farmland, and more. Watersheds come in all shapes and sizes and can even cross state lines.

The graphic above shows how water travels over a landscape and eventually forms streams and rivers. In a natural environment, this water would be pretty clean; however, when rain hits an impervious surface it creates stormwater runoff, which picks up pollutants and enters the nearest creek or stream. This creek or stream will join others to form larger streams, which join others to flow into larger rivers. Just like streams, smaller watersheds join together to form larger watersheds. That means any pollution that enters our stormwater can transported throughout an entire watershed.

All of us live in a watershed – let’s keep them clean! Use this EPA tool to Surf Your Watershed and find out more about how stormwater, runoff, and streams connect to form watersheds in your area.