Threats to recreation and human health


The stretch of coast between Montana de Oro State Park through Morro Bay and up to Cayucos is rich with both biological and recreational resources. This is the stretch that will be impacted by the proposed Diablo Canyon seismic testing. Pretty much everything you can see in the photo above will be off limits during the 17 days of testing because the underwater sounds generated by the seismic airguns pose a hazard to human heath if you are in the water.

This map produced by the Coastal Commission  (above) shows the area that will be exposed to 160 db sound from underwater blasts (red dotted line). The blasts will go off every 11-20 seconds 24/7 during the survey period.  The Environmental Impact Report (EIR) for this project  concluded that any sound over 154 db is considered harmful for recreational divers and swimmers in the project area. The EIR notes that studies have shown that high levels of underwater noise can cause dizziness, hearing damage, or other sensitive organ damage to divers and swimmers, as well as indirect injury due to startle responses. More concerning is that the 160 db limit is just a best estimate. There is reason to believe that the sound could amplify (like ocean waves do) as it enters shallow water and increase in power.

While 160 db doesn’t seem a lot higher than 154 db, it is because decibels are logarithmic. So a 6 db difference equates to 4 times more powerful noise. Further, the Navy standard for exposure to underwater noise is 145 db. Exposure to 160 db is 30 times higher than the Navy standard. The Coastal Commission concludes, “Individuals engaged in water-oriented recreational activities in these areas during active survey operations may therefore be at an increased risk of injury” 


The Coastal Commission also concludes that PG&E has proposed inadequate plans to warn ocean users (surfers, swimmers, divers & snorkelers) about these hazards, provide updated sound propagation maps in the sound is more powerful, or any plans to mitigate for the lost recreational use. This is yet another important reason why this project should be stopped.

What can you do? 

1. Attend the Coastal Commission meeting on November 14th in Santa Monica. Info here.

2. Send an email to the Coastal Commission opposing this project here.