SACRAMENTO – A new report by the Ocean Protection Council Science Advisory Team, or OPC-SAT, provides scientific guidance on ways to restore coastal areas impacted by power plants using once-through cooling technology.

The report, “Ocean Restoration Methods: Scientific Guidance for Once-Through Cooling Mitigation Policy,” continues California’s significant investment in 124 marine protected areas, or MPAs, to help safeguard the long-term health of California’s marine life.

Once-through cooling technology pulls water from the ocean to cool power plants. Marine animals, seaweeds, and billions of eggs and larvae of fish and invertebrates are taken in with the seawater and killed as they are subjected to thermal, physical, and/or chemical stresses. Larger organisms may also be pinned against seawater intake screens, causing injury or death.

These impacts contribute to the decline of fisheries and the degradation of marine habitats near power plants using once-through cooling.

To address these damaging impacts, the State Water Resources Control Board established a policy in 2010 requiring power plants to stop using once-through cooling technology.

Until power plants transition to less harmful cooling systems, the policy requires them to make mitigation payments to the California Coastal Conservancy and the Ocean Protection Council to support projects that will offset negative ecological effects and increase marine life associated with MPAs in the geographic area of the facilities.

A Working Group of the OPC-SAT, convened by the Ocean Science Trust, applied the best science available to help identify projects that would meet the requirements of the Once-Through Cooling Policy to bolster marine life associated with California’s MPA network.

Their report determined that due to oceanographic currents connecting locations both inside and outside of MPAs, harmful effects of once-through cooling could extend hundreds of kilometers from a power plant’s intake pipe.

Given the geographic extent of power plants still using once-through cooling, the findings of this report define the areas impacted as the entirety of State waters (3 nautical miles from the coastline) from San Diego to Big Sur, including the waters around the Channel Islands.

The Ocean Protection Council’s Once-Through Cooling Interim Mitigation Program directs mitigation payment investment through four critical components: 1) enforcement of MPA rules and regulations statewide; 2) outreach and education to improve compliance; 3) research to understand how existing MPAs may be mitigating for OTC impacts; and 4) restoration that increases marine life in the geographic regions of the facilities.