What is a watershed?

    Watershed Defined
A watershed is the land area that drains water to a particular stream, river, or lake. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge.

Watershed Diagram
The diagram below suggests a typical watershed that starts with small headwater streams in the higher elevations of the drainage basin. Water flows downhill from the drainage divide into larger streams, eventually joining a river. As more tributary streams join the river, the volume of water increases. This river eventually flows downstream into an even larger river at the confluence.
    River Diagram  

National Geographic's interactive river system.

EPA's Surf Your Watershed

RiverSmart: What is a Watershed?

This page was last updated 4/15/11