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This is a map of estuaries in the Mid-Atlantic region of the U.S. eastern coast including the well-known Chesapeake Bay Estuary. Notice how the rivers get very wide as they get closer to the ocean? This is where the salt water of the ocean is mixing with the fresh water of the rivers.
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Courtesy of the EPA.

Estuaries

An estuary is a very special place where fresh water and salt water come together. Estuaries are found on the coast where fresh water like a river or a bay has access to the ocean. A good example of an estuary is a salt marsh that can be found close to the coast. Another example is when a river feeds directly into the ocean. The largest estuary in the United States is the Chesapeake Bay estuary.

The mixing of fresh and salt water creates a different environment, but estuaries are still home to a lot of plants, animals and bacteria! When looking at estuaries, scientists quickly realized that these areas were extremely nutrient-rich because of sediment deposit of rivers, creeks or streams feeding into the salt water environment.

Unfortunately, estuaries haven't always been seen as valuable. In the past, they were seen as worthless and were even used as dumps! In 1972, Congress created the National Estuarine Research Reserve System (NERRS) to protect the estuaries around the U.S.

Last modified June 1, 2010 by Lisa Gardiner.

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