A watershed is an area of land where all rain and snowmelt run downhill to the same place.

A watershed can be as small as the creek in your backyard that drains only a few acres.

Or a watershed can be as large as the Chesapeake Bay watershed, which drains 64,000 square miles.
Virginia has 14 main watersheds.

Four of these watersheds drain to the Chesapeake Bay: the Potomac, the Rappahannock, the York and the James.

Why are watersheds important?

Because when pollution is carried into a stream in one part of the watershed, it affects the rest of the watershed as it is carried downstream.

Also, when land is developed, it changes the capacity of the land and waterways to handle stormwater. See Stormwater for more information.

How do you think the way land is used in the picture on the right might affect the stream health and water quality in the rest of the watershed?