Watershed

What is a watershed?

A watershed—sometimes called a basin or drainage basin—is an area of land that drains into a particular river, lake or other body of water. We all live in a watershed. Some watersheds, like that of a stream or creek, are small. Others, like the Chesapeake Bay watershed, are large.

We asked people in Alexandria, Virginia, to share their definition of a watershed:

What is the Chesapeake Bay watershed?

The Chesapeake Bay watershed spans more than 64,000 square miles, encompassing parts of six states—Delaware, Maryland, New York, Pennsylvania, Virginia and West Virginia—and the entire District of Columbia. More than 18 million people live in the Chesapeake Bay watershed.

The land-to-water ratio of the Chesapeake Bay is 14:1—the largest of any coastal water body in the world. This is why our actions on land have such a big impact on the Bay’s health.

What rivers flow through the Bay watershed?

The Susquehanna, Potomac, Rappahannock, York and James rivers are the five largest rivers in the Chesapeake Bay watershed.

More than 100,000 streams, creeks and rivers—called tributaries—thread through this watershed. Each watershed resident lives within a few miles of one of these local waterways, which act like pipelines that connect our communities to the Bay.

Each of the streams, creeks and rivers in the Bay watershed has its own watershed, called sub-watersheds, small watersheds or local watersheds.