The Navy says its explosives and sonar training program needs to be as realistic as possible. The program had been scheduled to begin next January off the Southern California coast.
But at a packed hearing in San Diego, the California Coastal Commission said "no" to the Navy's plans. Environmental groups are concerned it could hurt endangered blue whales and other marine mammals.
"We're really, really pleased with the verdict today," said Stephanie Sekich, Surfrider Foundation California policy manager. "The state just recently established these marine protected areas. It took 10 years, a lot of resources. They're supposed to be protected and they're not supposed to have sonar and explosives going off inside of them."
Commissioners say the Navy didn't have enough information to back up its argument that the harm to marine mammals would be negligible.
The Navy estimates the training program would kill 130 marine mammals and cause hearing loss in 1,600 over five years.
"The harm the U.S Navy proposes to inflict on Southern California marine mammals and other species is not only extraordinary and unprecedented, it is shameful," said Dr. Jack B. Hamlin, San Diego Council Green Party.
The Coastal Commission's staff recommended approval of the plan be contingent on a list of conditions, including the navy creating "safety zones" that would prevent high-intensity sonar activity near marine protected areas, and spots where there are large numbers of blue, fin and gray whales seasonally.
The Commission listed similar conditions in 2007 and 2009 but the Navy refused to follow them. The Commission sued the Navy, leading to a preliminary injunction in 2008. However, then-President George w. Bush gave an exemption to the training. The U.S. Supreme Court later overturned the lower court's decision.
"Our goal continues to be to try and reach agreement with the state and so that's why I said we'll look carefully at the decision the Coastal Commission reached today," said Navy environmental program manager Alex Stone.