Damage to ocean life is one of the main environmental concerns surrounding plans to conduct high-energy seismic surveys off the shore of Diablo Canyon nuclear power plant.
Local residents voiced these concerns Wednesday when the National Science Foundation held a public hearing in San Luis Obispo. The foundation is one of 12 federal, state and local agencies that must approve of the survey work.
Concern centers on the use of air guns that will emit extremely loud sounds into the ocean over a 33-day period beginning as early as Oct. 1. A report by the foundation examines the damage those sounds could do to fish and marine mammals.
Possible harm includes causing deafness in animals or driving them away from the area. The foundation has tentatively concluded that these effects would be minimal.
It is unlikely that the proposed action would result in any cases of temporary or especially permanent hearing impairment, or any significant non-auditory physical or physiological effects, the agency concluded in its environmental assessment. Some behavioral disturbance is expected, if animals are in the general area during seismic operations, but this would be localized, short-term, and involve limited numbers of animals.
This conclusion disappointed many who attended Wednesdays hearing. Its hard to imagine that the levels of sound to be emitted would not harm wildlife, they said.
I dont think there is any way you can conclude that from your assessment, said Christine Heinrichs of Cambria.
The air gun would emit frequent blasts of sound that measure 250 decibels. There is no everyday equivalent for that level of sound. Most decibel charts list the loudest sound as a military jet aircraft taking off at 140 decibels.
The survey protocols call for a variety of steps to be taken to minimize the effect of the loud sounds on marine life. These include deploying airborne and seaborne wildlife observers who could stop the survey work if a whale or other marine mammal got too close, as well as ramping up the sounds to warn animals away from the area.
PG&E, owner of Diablo Canyon, this week announced it will fund two research projects that will give biologists a better understanding of the effects this kind of seismic survey work has on marine life, said Jearl Strickland, Diablo Canyon manager of nuclear projects.
One project calls for federal wildlife officials to capture 60 sea otters in and around the study area before and again after the surveys. These animals would be tagged and a series of biological samples taken from them. The data collected would tell researchers how the otters respond to the survey work by moving away or experiencing injury or stress.
The other would fund the continued work of a fisheries research project at Cal Poly. The project already has six years of data, and the PG&E funding would continue it for an additional five years. The research will tell biologists how fish populations react to the loud survey work and how quickly they recover.