The Pentagon has exempted the Navy from complying with the Marine Mammal Protection Act when using mid-frequency active sonar during Rimpac and other upcoming military exercises.

The exemption, issued yesterday, was in reaction to a lawsuit filed this week that tried to stop sonar use in Rimpac, which is under way in waters around Hawai'i. The suit contended that sonar threatens whales and other marine mammals.

Yesterday's decision angered environmental and marine conservation organizations.

"I think that the Navy is being reckless in simply plunging ahead without adopting better mitigation measures," said Paul Achitoff, an attorney with Earthjustice in Honolulu. "I think it's increasingly evident that there's the potential of real harm from what they're doing."

The Natural Resources Defense Council, which filed the suit that prompted the Department of Defense action, had even harsher criticism.

"This is an historic and unprecedented retreat by the U.S. Navy from our national commitment to protect whales, dolphins and other marine life," said council attorney Joel Reynolds. "It's not that the Navy can't comply with the law; it's that the Navy chooses not to."

The Navy said sonar is a key technology in locating enemy submarines and that there are more than 140 super-quiet diesel-electric submarines operating in the Pacific.

"Hawaiian waters offer Rimpac participants the opportunity to realistically and effectively train in a number of maritime disciplines and exercises essential to maintaining an edge over increasingly stealthy submarines," said Rear Adm. Gary A. Engle, director of environmental programs for the U.S. Pacific Fleet.

In a news release, the Department of Defense said the exemption means the Navy for the next six months will not need permits for activities that may harm marine mammals — but that the Navy will work with the National Oceanic & Atmospheric Administration on its environmental program.

The exemption covers a dozen training activities in two oceans over the next six months. The Navy must still comply with the National Environmental Policy Act, Endangered Species Act and other conservation legislation.

Congress granted the Department of Defense the authority to exempt military forces from environmental laws under the 2004 National Defense Authorization Act.

"The Navy will continue to employ stringent mitigation measures to protect marine mammals during all sonar activities, to include habitat controls, safety zones around ships, trained lookouts, extra precautions during chokepoint exercises, in coordination with the National Marine Fisheries Service," said the Navy director of environmental readiness, Rear Adm. James Symonds.

A chokepoint is a narrow channel, often shallower than surrounding ocean. There has been an indication that marine mammals may be more severely affected by sonar in these areas.

This year's Rimpac exercises take place two years after the July 3, 2004, event in which 200 deep-ocean melon-headed whales crowded into the shallows of Hanalei Bay on Kaua'i's north-facing coastline, behaving in what a marine mammal veterinarian said was an anxious manner.

Residents on canoes and kayaks wove a hukilau cable of beach vines and dragged it through the ocean to coax the whales back into deeper water. On July 5, a dead newborn melon-head washed ashore nearby.

The Navy acknowledged using sonar in Kaua'i waters during that time, and when NOAA Fisheries released its report on the near-stranding, NOAA Fisheries acoustics program director Brandon Southall said of Navy sonar responsibility for the event: "It's plausible and likely, if not probable." The Navy has continued to deny any conclusive link between its sonar use and the melon-headed whale activities.

"Our concern all along with the Navy has been its repeated denial that sonar has an impact," said Sierra Club Hawai'i chapter head Jeff Mikulina. "Whales and dolphins continue to beach themselves, and the Navy is not willing to acknowledge that there is a clear impact."

The Navy has worked with the National Oceanic & Atmospheric Administration to develop standards for the use of sonar during Rimpac, and NOAA this week had issued it a permit to proceed with its exercises under certain restrictions. Those include reducing sonar power if marine mammals are spotted and reducing it further if they move closer to the ships.

"The Navy and NOAA have worked hard these past several months to take the appropriate measures necessary to avoid harming marine life while also ensuring the realism of this vital multinational naval exercise," Symonds said.

Marjorie Ziegler, executive director of the Conservation Council for Hawai'i, said there was indication the Navy could have worked out a way to use its sonar in a way that it would not have been dangerous to marine mammals, but chose to exempt itself instead.

"I think this is unfortunate. They can train and protect marine mammals. I think this is really bad precedent," Ziegler said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.