BW : Brackish Water
Brackish Water :
Brackish water condition commonly occurs when fresh water meets seawater. In fact, the most extensive brackish water habitats worldwide are estuaries, where a river meets the sea.
Some seas and lakes are brackish :
The Baltic Sea : salt water at the bottom and freshwater at the top.
The Caspian Sea is the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater.
The Black Sea the surface water is brackish.