PG&E seismic mapping will have significant impact on environment

Study cites effects on everything from noise and air quality to animals and land use

dsneed@thetribunenews.comMarch 21, 2012 

The State Lands Commission has released its environmental analysis of high-energy offshore seismic mapping planned by PG&E for late this year.

The study concludes that the work will have significant impacts on air quality, land and marine animals, greenhouse gas emissions, land use, recreation and noise. PG&E plans to do the work from September to December, with the offshore surveys being conducted continuously for as many as 82 days.

The agency has scheduled hearings to get public feedback on the project at 2 and 6 p.m. April 19 in the county Board of Supervisors chambers in San Luis Obispo. The public comment period closes May 3.

The surveys are set to employ a 235-foot research vessel, the Marcus G. Langseth, which will tow an array of instruments. These instruments will emit noises into the ocean loud enough to penetrate as far as nine miles into the Earth’s crust. Hydrophones will then be used to collect the returning sound for analysis.

The survey work is to be conducted over 530 square miles of ocean from Cambria to Guadalupe. The surveys will give researchers a clearer picture of earthquake faults in the area of Diablo Canyon nuclear power plant. That information is a prerequisite for PG&E applying to extend Diablo Canyon’s two operating licenses to 2044 and 2045.

Environmentalists and fishermen have raised a number of concerns about the project. These include potential harm to marine mammals and other animals, long-term disruption of commercial fishing, and impacts to protected marine areas.

The report says several types of whales, the Morro Bay population of harbor porpoises and sea otters would be the most affected by the project’s noise.

Commercial fishing will be precluded in the study area during the time the surveys are conducted. The report estimates that 10 percent or more of some fisheries could be lost for that season.

In an effort to minimize these impacts, the agency is recommending that the northernmost survey area near Cambria be eliminated as unnecessary. The U.S. Geological Survey already has significant information about the geological features of that area, said Jearl Strickland, director of nuclear projects at Diablo Canyon.

Bypassing the area would reduce the number of days needed for the survey by seven. In addition, this shorter period would eliminate the need for the ship to refuel in Port Hueneme, saving another seven days — a total reduction from 82 days to 68. This could allow the survey work to begin as late as Oct. 1, allowing for possible delays in the permitting process, Strickland said.

PG&E must also get permits from the National Science Foundation to do the work. The utility expects to get those permits by Sept. 1, Strickland said.

The draft environmental impact statement is available online at Comments can be emailed to Jennifer DeLeon at

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