Chesapeake Bay Watershed
The Chesapeake Bay watershed is a prominent feature within this image of the Mid-Atlantic region.
This 64,000 square mile drainage basin encompasses parts of New York (as far North as Cooperstown), Pennsylvania, Delaware, Maryland, Virginia, and West Virginia. The Chesapeake Bay (located in the lower left of the image) is the largest estuary in North America and is an important fishery and recreation area.
There are important linkages between upstream and downstream: any activity that takes place with the Bay watershed impacts its water quality. One major environmental problem in the Bay is caused by excess nutrients, a process called "eutrophication".
Rainfall carries materials from the surface into the stream network of the watershed and ultimately into the Bay itself. Some of these materials, such as nitrogen and phosphorus, stimulate the growth of algae. When the algae die, they are decomposed by a type of bacteria that depletes the oxygen that is dissolved in the water; without this dissolved oxygen, fish and other aquatic organisms cannot survive.
The Chesapeake Bay Program reported recently that areas with low oxygen (hypoxic) or no oxygen (anoxic) conditions were more prevalent this Summer than at any time in the last 21 years since monitoring began.