The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Virginia and Maryland. The Chesapeake Bay's watershed covers 64,000 mi² (165,800 km²) in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia. More than 150 rivers and streams drain into the Bay. The Bay itself is about 189 miles (304 km) long, from the Susquehanna River in the north to the Atlantic Ocean in the south. Geologically, the Bay is the drowned valley of the Susquehanna, meaning that was where the river flowed when sea level was lower, but the Bay's geology and its present form and its very location have also been affected by a bolide impact event at the end of the Eocene (about 35.5 million years ago), forming the recently discovered submerged Chesapeake Bay impact crater. At its narrowest point, near Annapolis, Maryland, it is only 4.3 miles (6.9 km) wide and is spanned by the Chesapeake Bay Bridge. Near its mouth, it is spanned by the 23 mi. (37 km) long Chesapeake Bay Bridge-Tunnel.

Much of the bay is quite shallow. A person 6'7" (2 m) tall could not only walk across the mouth of the Susquehanna at the upper bay, but could also traverse some 700,000 acres (2,800 km²) of the bay without being entirely submerged. On average, the depth of the Bay is less than 5 fathoms (30 feet or 9 meters).

The Chesapeake Bay Bridge.

The Chesapeake Bay was the site of the Battle of the Chesapeake in 1781, during which the French fleet defeated the Royal Navy, allowing the United States to become independent.

The largest rivers flowing into the Bay are:

• Susquehanna River
• Potomac River
• James River
• Appomattox River
• Rappahannock River
• Patuxent River
• Choptank River
• York River formed by:
  • Mattaponi River
  • Pamunkey River

The word Chesepiooc is an Algonquian word meaning "Great Shellfish Bay". The Bay was once known for its great seafood production, especially blue crabs, clams and oysters. The plentiful oyster harvests led to the development of the Skipjack, the State Boat of Maryland, which is the only remaining working boat type in the United States still under sail power. Today, the body of water is less productive than it used to be, because of fertilizer runoff from agricultural development on the Eastern Shore and throughout the watershed, urbanization, particularly on its western shore, overharvesting, and invasion of foreign species. The bay though, still yields more fish and shellfish (about 45,000 short tons or 40,000 metric tons yearly) than any other estuary in the United States.

In the 1970s, the Chesapeake Bay contained one of the planet's first identified marine dead zones, where hypoxic waters were so depleted in oxygen they were unable to support life, identified when massive fish kills resulted. Chesapeake Bay's oyster industry has also suffered from two diseases: MSX and dermo. Harmful algae blooms such as Pfiesteria which can effect both fish and humans is also a problem. The depletion of oysters due to overharvesting has had a particularly harmful effect on the quality of the Bay. The reduction of oysters, which serve as natural water filters for the Bay, has led to reduced water quality of the Bay.

The bay is also known for the Chesapeake Bay Retriever, a dog breed developed in this area.

External links

• Chesapeake Bay Program
• Chesapeake Bay Foundation
• Alliance for the Chesapeake Bay
• Chesapeake Bay Bridge (near Annapolis, MD)
• Chesapeake Bay Bridge-Tunnel
• Maryland Sea Grant
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