Technically, brackish water contains between 0.5 and 30 grams of salt per litre — more often expressed as 0.5 to 30 parts per thousand (ppt or o/oo). Thus, brackish covers a range of salinity regimes.
Etymology
The term brackish water derives from the Low Saxon word brackwater, which is the water of a brack. A brack is a small lake created when a storm tide breaks a dike and floods land behind the dike.
See also: Baltic Sea, Biosalinity, Slough
nds:Brackwater