Brackish water

Brackish water (less commonly brack water) is salt water and fresh water mixed together. It is saltier than fresh water, but not as salty as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. 

Some human activities can produce brackish water, mostly certain civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish pools for freshwater prawns. 

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 ‰). Thus, brackish covers a range of salinity regimes and is not considered a precisely defined condition. It is characteristic of many brackish surface waters that their salinity can vary considerably over space and/or time.

 Water salinity based on dissolved salts in parts per thousand (ppt) Fresh water Brackish water Saline water Brine < 0.5 0.5—35 35—50 > 50

 Etymology 
The term brackish water comes from the Low German word Brack, which is a small lake made when a storm tide breaks a dike and floods land behind the dike.

 Brackish water habitats 
 Estuaries 

The most important brackish water habitats are estuaries, where a river meets the sea, mixing salt and fresh water.  The River Thames flowing through London is one of the most familiar of river estuaries.

 Mangroves 
Another important brackish water habitat is the mangrove swamp or mangal.

 Brackish seas and lakes 
Some seas and lakes are brackish. The Baltic Sea is a brackish sea adjoining the North Sea.

The Caspian Sea is the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater. The Caspian is famous for its peculiar animal fauna, including one of the few non-marine seals (the Caspian seal) and the great sturgeons, the source of caviar.

 Important brackish bodies of water 
Brackish seas
 Baltic Sea (the world’s largest pool of brackish water)
 Black Sea
 Caspian Sea (world’s largest lake)

Brackish water lakes
 Lake Charles in Lake Charles, Louisiana, USA
 Chilika Lake, Odisha, India
 Pangong Tso (Lake) in Ladakh, Jammu and Kashmir, India 
 Lake Van, Turkey

Coastal lagoons, marshes, and deltas
 The Burgas Lakes near the Bulgarian Black Sea Coast
 Kaliveli Lake, near Pondichery, India
 Kerala Backwaters, Series of lagoons and lakes in Kerala
 Lagos Lagoon in Lagos, Nigeria
 Lake Pontchartrain, north of New Orleans, Louisiana, USA
 Pulicat Lake, north of Chennai, India
 The Rann of Kutch, on the border of India and Pakistan
 Parts of the Rhône Delta, France: An area known as the Camargue

Estuaries
 Amazon River, empties so much freshwater into the Atlantic Ocean that it reduces the salinity of the sea for hundreds of miles
 Chesapeake Bay, in Maryland, USA
 The Fleet lagoon, Dorset, England
 Hampton Roads, Virginia, USA
 Lower Hudson River, in New York and New Jersey, USA
 Lingding Yang, Guangdong, the People's Republic of China
 Port Royal Sound part of Beaufort County, South Carolina, USA  
 Saint Lawrence and Saguenay Rivers, the part downstream from Québec and Saguenay respectively
 The Thames Estuary in South East England

Related pages
 Salinity
 Desalination

Category:Water