Short answer:
When fresh water meets salt water and they mix, the result is brackish water. (See related questions.)
An estuary may be formed when this occurs at the mouth of a river. (See related link.)
More:
An estuary is a partially enclosed area where a fresh water source such as a river flows into a salt water body such as a sea or ocean. The area is termed an estuary if both ocean and salt water influxes substantially determine the nature of the body of water, hence it would normally be partially enclosed and retaining a significant portion of fresh water influx that is not immediately diluted into the seawater.
Estuaries are often both interesting biological systems and interesting geological formations.
Note: For the more general question of where fresh and salt water meet, see related questions.
Note: If one is interested in the halocline, which is a strong vertical gradient of salt concentration form sometimes at the interface of fresh water and salt water, then that is a different question.
An estuary is the place when river water mixes with seawater (salty ocean water).
The Miss. River is fresh water, and when it collides with the Gulf Of Mexico, it mixes with the salt ocean water, thus becoming salt water!!
WHAT MEAN SALT WATER MIXES IN A Ecosysten
it mixes to create brackish water
All rivers are fresh. When they get near the ocean, the fresh river water mixes with the ocean water in the river "delta" as the tides go in and out.
The coastal ocean is the narrow strip of ocean from the outer edge of the continental shelf to the greatest distance upstream that salt water mixes with the fresh water of a river flowing into the ocean.
Water that is a mixture of fresh water and salt water is called brackish water.
The body of water where fresh water from a river mixes with salt water is called an estuary. This commonly an enclosed body of water.
The place where a river flows into an ocean and fresh water mixes with salt water is known as a delta. The water that is less salty than seawater is known as brackish water.
the river runs into the ocean.... its called brackish water
Ocean water contains salt. River water is fresh water.
As in the case of all rivers which flow into seas or oceans, the Nile River mixes its fresh water with the salt water of the Mediterranean at its delta. There is no exact point at which a river ceases to be fresh water and become salt water.