Watershed

"Area that drains or contributes water to a particular point, stream, river, lake or ocean. Water- sheds are also referred to as basins. Watersheds range in size from a few acres for a small stream basin, to large areas of the country like the Chesapeake Bay Basin that includes parts of six states. (see river basin)" (Virginia Polytechnic Institute and State University, n.y.)

Sources

Virginia Polytechnic Institute and State University. "A Glossary  of Water-Related Terms", by Brian Benham. Publication 442-758