Brackish water, also sometimes termed brack water, is water occurring in a natural environment having more salinity than fresh water, but not as much as seawater. It may result from mixing seawater (saltwater) with freshwater together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root brak. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater shrimp farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.