(June 11, 2010) Last month the State Water Resources Control Board adopted its once-through cooling policy for coastal power plants—a plan that could force 19 California power plants to phase out once-through cooling systems if it’s approved by the state Office of Administrative Law (OAL).

Once-through cooling refers to power plant systems that use open intakes to pump water from an ocean, estuary or bay to cool generators or turbines and then discharge the water after one cycle of cooling.

The new once-through cooling policy is expected to reduce the impact on aquatic wildlife as this process is currently used by 19 power plants in California.

This new policy is intended to provide clear standards and consistency in implementing the federal Clean Water Act, which requires the use of best technology available in the interest of protecting marine life.

Cost to Power Plants

If approved by the OAL, plant operators will have about six months to submit details of how they would comply with the new regulations. Options include installing closed-cycle systems such as cooling towers. The cost for retrofitting, or using the best technology available could ultimately cost power plants millions of dollars.

The new provision would allow the California Independent System Operator to make its recommendations to the State Water Resources Control Board on power plants that are essential to maintaining the reliability of the electric system, a recommendation that the State Water Board will weigh significantly in considering whether to suspend or amend final compliance dates.

Most plants will have until 2015 to phase out once-through cooling systems, while those in the Los Angeles area will have until 2020 due to the city’s more complex and challenging power needs. The San Onofre and Diablo Canyon nuclear power plants have until 2022 and 2024 to comply.

More Information

For more information about state policy on coastal and estuarine water use for power plant cooling, refer to the State Water Resources Control Board website at www.swrcb.ca.gov.

Staff Contact: Brenda M. Coleman