Answer:
An estuary is a partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. The fresh water in an estuary typically comes from rivers and streams that flow into the estuary from the surrounding land. These rivers and streams may be fed by a variety of sources, such as melting snow, rainwater, and underground springs.
The amount of fresh water that flows into an estuary can vary greatly depending on the location and the climate. In some cases, the fresh water may be the dominant component of the estuary, while in other cases the salt water may be more dominant. The mix of fresh and salt water in an estuary is known as brackish water.
Estuaries are important habitats for a wide variety of plants and animals, and they are often called the "nurseries of the sea" because they provide a safe and productive environment for many species of fish and other marine life to grow and reproduce.