Water Board Weighs Phasing Out Diablo Canyon's Cooling System

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The Diablo Canyon Nuclear Power Plant. (Craig Miller/KQED)

Diablo Canyon Nuclear Power Plant, located near San Luis Obispo on California's Central Coast, pulls in 2½ billion gallons of seawater every day, and then lets it out, 20 degrees warmer, back into the ocean. The system is known to cause marine damage, harming billions of fish larvae.

In 2010, California’s water board required all coastal power plants in the state to phase out this type of system, called once-through-cooling, bringing the state in line with part of the federal Clean Water Act. The State Water Resources Board held a hearing Tuesday afternoon to discuss whether PG&E should have to comply with that policy at Diablo Canyon.

The two nuclear power plants in operation on the California coast when the policy was adopted were given until 2015 to show how or if they could comply. San Onofre Nuclear Generating Station has since ceased to operate. PG&E is arguing that the cost to phase out once-through-cooling at Diablo Canyon is too high.

"And due to the fact that Diablo Canyon is a significant contributor of clean energy to the state and is helping the state reduce greenhouse gas emissions and combat climate change, it’s important that alternative compliance measures are considered," said Blair Jones, a spokesman for PG&E.


The hearing centered around a study by the Bechtel Corp., commissioned by PG&E, to show compliance options. It included possibilities from mesh screens to the tall cooling towers that many people think would be the best solution. Part of the rub lies in the cost. Bechtel says it could be somewhere between $6.5 billion and $11.5 billion to build the towers.

Environmental advocates argued for the cooling towers, citing other studies with much lower costs, in the $1.5 billion to $4.5 billion range. Damon Moglen is with Friends of the Earth, an environmental group that opposes nuclear power.

“The question that we face here with Diablo Canyon is, does PG&E deserve to be excluded from two of the key environmental protection policies that the state of California has set up? And the answer is no! If they say they can generate energy safely and cleanly, then they need to comply with the law,” said Moglen.

Some members of a review committee, including the California Public Utilities Commission and the California Energy Commission, say there is no basis for exempting Diablo Canyon from phasing out once-through cooling. They recommend making compliance a minimum condition for relicensing the plant.

Water board staff say they received 7,000 public written comments calling for full compliance. They hope to make recommendations regarding the nuclear power plant early next year.