About 20 whales were feeding and behaving normally Monday morning, when whale-watch operator Tom McMillen lowered an underwater microphone into the water to listen to their calls.

He picked up a sound he had bever heard before - a high, shrill whistle that repeated every 25 seconds or so.

"As the sound got louder, the whales gathered up. They do this when they rest or if there's a stress," McMillen, owner of Salish Sea Charters, said in a phone interview from Friday Harbor on Thursday.

Soon after, the orcas started swimming away from the noise.

"They moved north and got out of there," McMillen said. "They looked distressed."

As many as 100 porpoises leaped through the water, appearing to distance themselves from the sound.

"The porpoises were going north," McMillen said. "They were all going the same direction, and they all looked like they were getting out of there."

As the pinging noise grew louder, McMillen said, he and others on his boat spotted what appeared to be a Navy ship about 10 miles away.

Cmdr. Karen Sellers, spokeswoman for Navy Region Northwest, confirmed the 511-foot USS Shoup was using its sonar "briefly" in Haro Strait, a body of water just west of San Juan Island, on Monday. The Everett-based ship was headed to the Canadian Forces Maritime Experimental Test Range in Nanoose Bay, British Columbia, she said.

"The Navy is looking into the Shoup's transit in Haro Strait on May 5 to determine what occured that day," Sellers said. She declined to comment further.

Use of Navy sonar has come under intense scrutiny since March 2000, when at least 16 whales and two dolphins beached themselves on an island in the Bahamas. Eight whales died, and scientists found hemorrhaging around their brains and ear bones, injuries consistent with exposure to loud noise.

In that case and a similar incident in the Canary Islands off northwest African last year, Navy ships were present and using a type of mid-frequency sonar called SQS-53C.

The Navy has not said what type of sonar was used in Haro Strait.

"Based upon the reports of biolgists on Haro strait, we believe it may be the same system," said Michael Jasny, a policy analyst with the Natural Resources Defense Council in Los Angeles.

Meanwhile, the Bush Administration is seeking to exempt the Department of Defense from five federal laws protecting wildlife and the environment: the Clean Air Act, the Endangered Species Act, the Marine Mammal Protection Act and two laws governing cleanup of toxic waste.

The House Resources Committee passed the bill, sponsored by Rep. Elton Gallegly, R-Calif., 25-13 on Wednesday.

Rep. Jay Inslee, D-Wash., voted against it.

"Obviously national security is of utmost importance," Inslee said in a phone interview Thursday, "but if we're going to be exposing endangered species to risk, we should go the last mile to look for alternatives" that balance environmental and military concerns.

The bill has rankled environmental activists.

"Here we have a case where the Navy ran thorough Haro Strait with their sonar blaring. It was a mistake, but if these exemptions pass, it won't be considered a mistake because the Navy will be able to deploy these systems wherever they like - off the coast of Washington, California, Maine," Jasny said. "There would be little accountability for the damage that they do."

The National Resources Defense Council and other environemental groups filed a lawsuit in August 2002 seeking to bar the Navy from using a powerful, low-frequency sonar system, which travels much farther than mid- or high-frequency sonar.

In October, a federal judge in San Francisco temporarily blocked the Navy from deploying low-frequency sonar.

"It is undisputed that marine mammals, many of whom depend on sensitive hearing for essential activities like finding food and mates and avoiding predators, and some of whom are endangered species, will at a minimum be harassed by extremely loud and far-traveling ... sonar," U.S. Magistrate Elizabeth D. Laporte wrote.

A hearing is scheduled for late June.