Freshwater estuaries are a unique ecosystem. They form as a freshwater river or creek empties into a large lake. The different chemicals and temperatures of the river and lake waters create the estuary. Old Woman Creek National Estuarine Research Reserve, near Huron, Ohio, is the only reserve that monitors a freshwater estuary: where Old Woman Creek empties into Lake Erie.

Photograph by Rich Delombard, MyShot
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estuary Encyclopedic Entry

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6 - 12 and up

Earth science, Biology, Geography

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An estuary is an area where a freshwater river or stream meets the ocean. When freshwater and seawater combine, the water becomes brackish, or slightly salty.