Pacific Gas & Electric (PG&E) is poised to begin weeks of sonic earthquake fault testing off the coast of its Diablo Canyon Nuclear Power Plant at San Luis Obispo that will affect the “migration, breathing, nursing, breeding, feeding or sheltering” of marine animals, but hopefully won’t kill or injure them.

A Morro Bay population of harbor porpoises is expected to take the worst of the beatings, but at least three-quarters of the 2,830 whales, dolphins and seals known to be in the area will feel the effects. The harbor porpoises would be forced to flee their feeding and habitat areas to escape loud, 250-decibel bursts of sound emitted by sound cannons every 15 seconds in November and December. The marine mammals are extremely sensitive to sounds and are vulnerable to hearing loss and injury.

The California Public Utilities Commission was considering a 20-year license extension for Diablo Canyon in 2011 when Japan was rocked by an earthquake and tsunami that devastated the country’s nuclear power industry. PG&E was already scheduled to update seismic studies by 2014, but the nuclear plant’s vulnerability has long been a contentious issue.

A previously undetected 15-mile fault line was discovered in 2008, just 330 yards from the power plant. State lawmakers unanimously approved legislation in 2009 that would have compelled PG&E to perform specific seismic tests, but it was vetoed by Governor Arnold Schwarzenegger.

The expanse to be tested includes two state marine protected areas. The State Lands Commission signed off on the PG&E plan in August, although its report found that the project “will have a significant effect on the environment.” 

The National Marine Fisheries Service’s Office of Protected Resources has issued a proposed Incidental Harassment Authorization, but PG&E still has to weather the state regulatory system that includes a November 10 hearing before the California Coastal Commission. It was originally hoping to start on November 1, but PG&E recently scaled back its proposal in hopes of winning quick approval from the commission and the California Department of Fish and Game.    

The plan is for18 air guns to be lugged behind a boat, blasting sound into the water over hundreds of square nautical miles. Sensors on the sea floor would pick up the echoes for computers to create three-dimensional maps.

PG&E wants to run the tests to map the several fault zones that lie close to the vulnerable nuclear reactors. Although some of the environmental groups that oppose the testing are in favor of better understanding the threats posed by an earthquake there, they feel that the tests could be done with less harmful technology.

If the project comes off without a hitch, it could be expanded next year to include two more areas.

The Diablo Canyon Nuclear Power Plant generates electricity for 3 million Central and Northern Californians.

–Ken Broder

To Learn More:

Environmentalists Oppose PG&E Plans for Undersea Air Blasts (by Louis Sahagan, Los Angeles Times)

Officials Mull Seismic Tests Near California Nuclear Plant (by Jason Dearen, Associated Press)

More than 2,000 Marine Mammals Will be Harassed in Diablo Canyon Seismic Survey (Associated Press)

Seismic Uncertainty at Diablo Canyon (by John Upton, The Bay Citizen)

Notice of Determination (State Lands Commission) (pdf)