Supreme Court Rules on Once-Through Cooled Power Plants

Apr 1, 2009

Baykeeper Urges State Action to Protect Imperiled Fisheries

Amy Chastain, Staff Attorney, San Francisco Baykeeper, 415-856-0444 x106

The U.S. Supreme Court ruled today that the Environmental Protection Agency (EPA) could weigh industry costs when establishing environmental protections for power plants with cooling water intake structures. The Court’s ruling states that a cost-benefit analysis is not categorically forbidden by the Clean Water Act, leaving it to the new Obama Administration to decide whether and how to compare costs to benefits when it issues new regulations for existing power plants.

San Francisco Baykeeper, a pollution watchdog group, has been calling for the elimination of oncethrough cooling at Bay plants for years and sees the ruling as an impetus for state action. “We hope that this decision will spur EPA to revise and strengthen once-through cooling regulations, but California should not wait any longer for federal action,” says Amy Chastain, Staff Attorney for San Francisco Baykeeper. “California has the responsibility and the authority to stop this assault on our rapidly declining fisheries before EPA comes out with a new rule.”

This Supreme Court ruling on the regulation of cooling water intake structures comes as California considers phasing out once-through cooling technology, an outdated process which is extremely detrimental to fish and wildlife. San Francisco Baykeeper and other environmental groups urge the swift passage of a state law currently working its way through the California Legislature, SB 42 (Corbett, DSan Leandro), that would direct the State Water Board to phase out the use of once-through cooling in California because of the environmental damage it causes.

Once-through cooling is widely regarded as an outdated technology which uses marine waters to absorb excess heat generated by power plants. The plants’ cooling water intakes pull larvae and small fish into the plant, and trap larger fish and sea mammals on the intake screens, killing nearly everything alive in the water that is used in the process. The plants also release heated water that can reach temperatures as high as 90 degrees Fahrenheit, an occurrence that is extremely detrimental to delicate marine ecosystems and the animals living in it.

Once-though cooling has been used at three Bay Area power plants for decades, in San Francisco, Pittsburgh, and Antioch. These plants operate at the detriment of Bay wildlife, killing organisms from all levels of the food chain and disrupting the normal processes of the Bay’s ecosystem. Records for Bay Area once-through cooling plants show that they have killed endangered species, including the Delta smelt and the Chinook salmon.


Founded in 1989, Baykeeper is a nonprofit organization dedicated to protecting the water quality of the San Francisco Bay for the benefit of the fish, wildlife and human communities who depend on it. Baykeeper uses advocacy, science and litigation to hold polluters accountable and enforce our clean water laws.

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