California coastal regulators have rejected a proposal by a utility to map earthquake faults near Diablo Canyon nuclear power plant by firing air cannons offshore.
Wednesday's unanimous vote to deny a permit came after an hours-long public hearing attended by environmentalists, fishermen and residents who were overwhelmingly opposed to the seismic testing.
California ratepayers are paying $64 million for seismic studies that the California Public Utilities Commission said are needed to see if the plants are threatened, and a ship has already been brought from the East Coast to do the studies.
But more than 150 people showed up at the California Coastal Commission meeting to protest using high-powered air guns to shoot high-decibel soundwaves deep into the ocean floor.
Michael Jasney of the Natural Resources Defense Council said it would cause tremendous harm to acoustically-sensitive marine mammals.
"The ocean is an acoustic world, it’s a world of sound not of sight," he said. "A blue whale has trouble seeing its own flukes in the water, but can communicate over hundreds, if not thousands, of miles. Like dynamite, air guns put out intense broadband noise across the frequency spectrum."
Even the staff of the California Coastal Commission urged the panel to reject the plan. It said more than 7,000 sea mammals including fin whales, blue whales, humpback whales and harbor porpoises would be affected.
Pacific Gas & Electric countered that the study, which would make 3-D maps of quake faults, is needed to understand the seismic hazards near the Diablo Canyon plant.
Coastal Commissioner Dayna Bochco said PG&E explained what the soundwaves would do.
"They did convince me that there is a target there, 7 or 8 miles below the ocean, that would give them more information about the Hosgri Fault that maybe dips down under the plant, maybe not," she said.
But Bochco said when she asked if finding the fault line would prove definitively that the nuclear plant was safe, she was told it was highly unlikely.
"And if it's not going to tell you, then why am I doing this to the ocean?" she asked.
Scientists at the Scripps Institution of Oceanography had originally planned to begin seismic testing off San Onofre nuclear power plant this year. Because the plant is offline, its operator, Southern California Edison, had postponed that study.
The Coastal Commission's decision makes it unlikely the testing will happen any time soon.