The Navy and environmental groups have reached an agreement that lifts a federal court restraining order and allows the Navy to conduct mid-frequency active sonar training during its Rimpac 2006 multinational war games, which are under way around Hawai'i and continue throughout July.

The agreement was approved by the U.S. District Court in Los Angeles. It includes restrictions on the sonar use to improve protection of marine mammals and to keep the sonar training out of the new Northwestern Hawaiian Islands Marine National Monument.

"It is critically important that we have been able to turn active sonar on for the rest of the RIMPAC exercise," Rear Adm. James Symonds, director of environmental readiness, said in a news release.

"We want to ensure that the U.S. Navy and its partner navies get the benefit of this opportunity to train in anti-submarine warfare."

Environmental groups said that kind of training needs to be used with care.

"This settlement confirms that measures to protect our oceans can and must be part of the Navy's training for submarine defense," said Joel Reynolds, senior attorney at Natural Resources Defense Council and director of its Marine Mammal Protection Project, also in a press release.

The monthlong Rimpac training exercises include military forces from eight nations. After NOAA Fisheries granted the Navy a Marine Mammal Protection Act permit last week to conduct its mid-frequency sonar, environmental groups sued to try to stop it.

Then the Department of Defense issued a statement declaring that national defense concerns pre-empt the act.

Finally, on Monday, a federal judge said other environmental laws still apply and ordered the Navy and environmental groups to negotiate. The judge said she had seen convincing evidence that sonar can harm marine mammals.

Under the agreement that lifted the judge's restraining order, the Navy must not use the sonar within 25 miles of the national monument, must report the presence of marine mammals detected through underwater listening devices or visual scanning, and must make public a number for people to call to report marine mammals in distress.

The NOAA Fisheries marine mammal hotline number is (888) 256-9840. Callers are asked to provide the time, date, location, description and kind of activity they are reporting.

Additionally, the Navy is to have one person whose job it is to search the waters for marine mammals during exercises, and three others keeping an eye out but who are not required to be only dedicated to watching for them. In channels between the islands, ships are to have two dedicated observers.

Under previous requirements, the Navy will reduce the volume of sonar signals when animals are present, or shut them off entirely if the animals are too close.

"We are pleased that the highest leadership in the U.S. Navy hierarchy has agreed to protective measures never before included in RIMPAC exercises. This is a significant step forward in the protection of our oceans," Richard Kendall, a private attorney representing the NRDC in the legal action, said in a press release.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.