The Chesapeake Bay watershed is approximately 64,000 sq. miles long and encorporates six states of New York, Pennsylvania, West Virginia, Virginia, Delaware, Maryland, and the entire District of Columbia. 17 million people live, work, and play in this watershed, and each individual directly affects the Bay.

The Chesapeake Bay proper is approximately 200 miles long, stretching from Havre de Grace, Maryland to Norfolk, Virginia. It varies in width from about 3.4 miles near Aberdeen, Maryland to 35 miles at its widest point, near the mouth of the Potomac River. Including its tidal tributaries, the Bay has approximately 11,684 miles of shoreline. It is a key commercial waterway, with two major Atlantic ports located here: Hampton Roads (which includes Norfolk, Hampton, Portsmouth, and Newport News) and Baltimore.

Fifty major tributaries pour water into the Chesapeake every day. 80 to 90 percent of the freshwater entering the Bay comes from the northern and western sides. The remaining 10 to 20 percent is contributed by the Eastern Shore. Nearly an equal volume of saltwater enters the Bay from the ocean.

On average, the Chesapeake holds more than 15 trillion gallons of water. Although the Bay’s length and width are dramatic, the average depth is only about 21 feet. The Bay is shaped like a shallow tray, except for a few deep troughs believed to be remnants of the ancient Susquehanna River. The troughs form a deep channel along much of the length of the Bay. The channel allows passage of large commercial vessels. Because it is so shallow, the Chesapeake is far more sensitive to temperature changes and wind than the open ocean.