Pacific Gas & Electric Co. was scrambling Monday to salvage plans to conduct seismic surveys using sonic blasts off the coast near the Diablo Canyon nuclear power plant after a state regulatory agency staff report concluded it would disturb more than 7,000 marine mammals.
The California Coastal Commission staff, in a report released Friday, recommended that the commission deny PG&E;'s application for a coastal development permit needed to begin the project. The staff cited “significant and unavoidable impacts to marine resources,” including threatened and endangered whales, porpoises and sea otters.
The commission plans to vote Nov. 14 on PG&E;'s request to survey 130 square miles off the coast of Morro Bay in San Luis Obispo County with acoustic pulses capable of penetrating as much as nine miles into the seafloor.
The utility believes the seismic survey is the best way to define the amount of movement that faults in the area are capable of producing, and to develop emergency preparedness plans.
Analysis of the sonic reflections would provide detailed 3-D images of the geometry, relationships and ground motions of several fault zones near the plant, which generates enough energy to meet the needs of more than 3 million residents of Northern and Central California.
“PG&E; is committed to conducting this proposed seismic research safely and in an environmentally responsible manner,” spokesman Blair Jones said. The utility’s plan was developed carefully in consultation with state and federal agencies, he said.
Coastal Commission staff, however, said it could not determine whether alternative, less harmful technologies are available for the survey — or whether it is needed at all.
“The staff is saying that the potential impacts of this project are so severe that a seismic survey should be the last alternative,” said Alison Dettmer, the commission’s deputy director of ocean resources. “Theoretically, they could come back later and apply again.”
The staff’s major concerns are the survey’s potential effects on the basic biological functions of sea creatures in marine sanctuaries, and on a population of about 2,000 harbor porpoises that reside in and around scenic Morro Bay.
Harbor porpoises are acutely sensitive to man-made sounds. It is the species that would be most vulnerable to hearing loss and injury during the survey, which calls for a 235-foot vessel to tow a quarter-mile-wide array of submerged 250-decibel “air cannons” that would discharge every 15 seconds, night and day, for 17 days.
The entire population of harbor porpoises in Morro Bay would experience multiple disturbances and possibly be forced to move far outside their normal foraging grounds, which could threaten their survival, according to the staff report.
Overall, “more than 7,000 individual marine mammals from 17 species would be exposed to sound levels sufficient to result in some level of disturbance and behavioral disruption,” the report said. In addition, the project would “result in mortality to about 5 million fish and invertebrate larvae in the project area and an unknown number of fish eggs.”
PG&E; said it plans to station observers certified in monitoring protected species on vessels and in airplanes to check for injured animals and carcasses. The utility said it would halt the testing if marine mammals, which rely on communication and sensing of their environment for a variety of critical life functions, venture close to the operation.
But commission staffers said that potentially high seas, windy conditions and poor night visibility “would cause these measures to be ineffective much of the time.”
Michael Jasny, director of the Natural Resources Defense Counsel’s marine mammal protection project, said the staff report “reflects a thorough understanding of the issues involved.”
“Fundamentally, this project has not been justified along the coast where the impacts would be significant,” Jasny said. “If you are going to impact the coast, you better make sure it is essential to the public welfare and there is no safer way to do it.”