Mitigation and Fees for the Intake of Seawater by Desalination and Power Plants

Raw seawater is used for a variety of purposes, including as source water for desalination plants and to cool coastal power plants. Raw seawater is, however, not just cold and salty but an ecosystem that contains diverse and abundant organisms including the young stages of numerous invertebrates and fishes. Whether impinged (large individuals stuck on screens prior to entering the plant or killed during other plant processes such as heat treatment) or entrained (small individuals carried into the plant with the water) the organisms are killed, essentially eliminating the living production in the water used (review in York and Foster 2005).

Considerable research has have been done in California to better estimate losses to this ecosystem by coastal power plant intakes (York and Foster 2005, Steinbeck et al. 2007), and to determine how these losses can be mitigated (Strange et al. 2004).  The information from this research has contributed to State of California policy regulating water used by power plants.  The policy now applies only to power plants but the intent to protect marine organisms is also broadly applicable to desalination plants and other users of large volumes of seawater.

The State’s Once-through Cooling Policy (Policy) states that plants must implement measures to mitigate interim impacts occurring after October 1, 2015, and until the plant comes into full compliance through conversion to closed cycle cooling or by using operational controls and/or structural control technology that results in comparable reductions in impingement and entrainment (IM&E).