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Delta Watch

Power Plant Diversions and Discharges

Two power plants owned and operated by Mirant Delta LLC are located in the Delta. Both plants utilize once-through cooling systems, which divert water into the plants then return the water back into the Delta. When in operation, the plants can entrain aquatic organisms including at-risk fishes, which generally results in mortality of such organisms. Use of the plants has declined steadily since 2002, but their impacts on at-risk species are not well understood. Therefore, the plants’ current operations are being studied for their potential impacts on delta smelt and other species protected under the federal Endangered Species Act and California Endangered Species Act. In 2010, the Coalition and other parties entered into a settlement with Mirant whereby: (a) the impact of current operations will be monitored and (b) regulatory review of the effects of the Plants on listed species will be completed by October 2011.

Additional Information
International Desalination & Water Reuse Quarterly US powerplant water emission rules to be tightened, say environmentalists (Nov. 14, 2010)

Press Release: Water Users Settle Lawsuits Over Delta Power Plants (Feb. 17, 2010)