The Army still has not determined the location of most of the more than 8,000 tons of chemical munitions dumped off O'ahu at the end of World War II, but says that if their containers fail, most of the chemicals would break down into nontoxic compounds.

The exception, according to an Army report released yesterday, is the blister agent lewisite, which could leave elevated levels of arsenic in seafloor sediment and in ocean water.

U.S. Rep. Neil Abercrombie, D-Hawai'i, a member of the House Armed Services Committee, and U.S. Sen. Daniel Akaka, D-Hawai'i, a member of the Senate Armed Services Committee, are writing legislation that would call for a complete underwater survey of dumping sites, and for research into their long-term threats to public and environmental health and the possibility and cost of cleaning them up.

Abercrombie said the legislators hope to include the provisions in the 2007 National Defense Authorization Act.

"No one knows exactly where these weapons are, how many tons are out there, what impact they're having on health and the environment or what we can do about it. It's important to start getting a handle on these questions," Abercrombie said in a statement released with the Army report, "Military Sea Disposal Operations Near Hawai'i."

The chemical dumping investigation is continuing, and yesterday's report is preliminary and brief — just seven pages. It is based primarily on a search of the National Archives at College Park, Md., and Washington, D.C.

The report indicates that rules about the dumping of toxic weapons were changing annually near the end of World War II. The War Department in 1944 required that such munitions be dumped in water at least 300 feet deep and 10 miles from shore. The next year, that was increased to 600 feet and 10 miles out, but dumping was allowed closer to shore if the water was deep enough.

In 1946, the War Department put the dumping into the hands of the Army Chief of Transportation, and required ocean depths of at least 6,000 feet for chemical weapons and 3,000 feet for conventional weapons.

The Army report also found evidence there is a great deal of material on the ocean floor in water much shallower and closer than required by those rules.

"In 2002, the Army surveyed an area near the Wai'anae sewage outfall — referred to locally as Ordnance Reef — and identified over 2,000 military munitions at depths ranging from 15 to 240 feet, with the majority of munitions observed at depths below 60 feet," the report said.

A 1996 survey found munitions off the Fort Weaver and Alum Point firing ranges at depths of 820 to 1,740 feet. All these were assumed to be conventional, not chemical, munitions.

There are also munitions on the ocean floor in much deeper water. Deep submersible vehicles have spotted a field off Barbers Point in water ranging from a depth of 4,300 feet to more than 6,000 feet, said Terry Kerby, director of facilities and submersible operations for the University of Hawai'i's Hawai'i Undersea Research Laboratory.

The Hawai'i dumping came to light last year with the discovery of an unclassified 2001 report by the Historical Research and Response Team of the U.S. Army Research, Development and Engineering Command. It briefly outlined chemical weapons dumping worldwide after World War II. Three dumping incidents are listed for Hawai'i

In 1944, somewhere off Pearl Harbor, 4,220 tons of hydrogen cyanide was dumped, apparently in various loose containers. It was not clear how far from shore they were dumped, but a Pentagon official said he thought they were in about 1,000 feet of water.

Also in 1944, the military moved 16,000 100-pound mustard bombs from upper Kipapa and Ala Moana and dumped them at an unspecified location listed as "about five miles off of O'ahu."

In 1945, off Wai'anae, the Army dumped seven tons of 1,000-pound hydrogen cyanide bombs, 461 tons of 1,000-pound cyanogen chloride bombs, 28 tons of 500-pound cyanogen chloride bombs, 800 tons of 114-pound mustard bombs, 510 tons of 4.2-inch mustard mortar shells, 1,817 tons of one-ton mustard containers and 300 tons of one-ton lewisite containers.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.