A tributary is a stream or river that eventually flows into a larger body of water. For example, the James River is a tributary of the Chesapeake Bay.

An ecosystem is a complex set of relationships among animals, plants, habitats, people and non-living things. All parts of an ecosystem interact with and depend on each other in some way.

The Chesapeake Bay is about 200 miles long, stretching from Havre de Grace, Maryland, to Norfolk, Virginia. The Bay’s width varies from its narrowest point (3.4 miles across near Aberdeen, Maryland) to its widest point (35 miles across near the mouth of the Potomac River).

On average, the Chesapeake Bay is about 21 feet deep. However, most parts of the Bay are extremely shallow. A person who is 6 feet tall could wade through more than 700,000 acres of the Bay and barely get his or her hat wet. The Bay also has a few channels that are more than 100 feet deep, which provide important habitat for aquatic life and passageways for ships.

The Choptank, James, Nanticoke, Patapsco, Patuxent, Potomac, Rappahannock, Susquehanna and York rivers are just a few of the many rivers that flow into the Chesapeake Bay. These rivers are fed by hundreds of thousands of streams and creeks that flow throughout the Chesapeake Bay watershed.

Anadromous fish live in the ocean, but must migrate to freshwater rivers and streams to spawn. American shad is one type of anadromous fish that lives in the Chesapeake Bay region.

More than 17 million people live in the Chesapeake Bay watershed.

A watershed is an area of land that drains to a particular river, lake, bay or other body of water.

The Chesapeake Bay watershed stretches across more than 64,000 square miles.

Salinity is a measure of the amount of dissolved salts in the water. Water can be fresh, salty or brackish (a mixture of salt and fresh water).