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.
Click on image for full size
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.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Salinity

About 70% of the Earth is covered with water. Over 97% of that water is found in the oceans. Everyone who has taken in a mouthful of ocean water while swimming knows that the ocean is really salty! Dissolved...more

Tidewater

Have you ever walked along a beach at low tide? Everyone likes to look for uncovered sea shells or the small creatures in leftover puddles of water during low tide. One thing is for sure, low tide can...more

Rivers

Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground...more

Step 2: Sediments on the Move!

If you sneeze into a pile of dust, the little particles fly everywhere. But if you sneeze into a pile of rocks, they will stay put. It takes more force than a sneeze to move those rocks. Winds and water...more

Aquifer

An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more

Carbonates

Carbonate is a name for rocks and minerals which contain a molecule made of both carbon and oxygen known as CO32-. (CO32- is also known as the molecule carbonate). Limestone is an example of a calcium...more

Evaporation

One process which transfers water from the ground back to the atmosphere is evaporation. Evaporation is when water passes from a liquid phase to a gas phase. Rates of evaporation of water depend on things...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA