The distant, fog-shrouded Aleutian Island of Amchitka holds a cornucopia of sea life. Sea otters, dwindling elsewhere in the Aleutian chain, gorge on the plentiful invertebrates that live in kelp forests within the reefs surrounding the island. Large flocks of emperor geese winter there. Nearby are fish-rich waters that support some of the world's biggest commercial seafood harvests.
And buried beneath the sea grasses of the island, which is part of the sprawling Alaska Maritime National Wildlife Refuge, are three deep, bomb-carved cavities filled with radioactive waste.
On Amchitka, an uninhabited island about 1,400 miles southwest of Anchorage, the Atomic Energy Commission detonated three bombs between 1965 and 1971 in the last underground US nuclear-weapons tests. The last and mightiest, the five-megaton Cannikin blast in 1971, was almost 400 times as powerful as the bomb that destroyed Hiroshima. The detonations caused the equivalent of a magnitude 7 earthquake and killed hundreds, perhaps thousands, of sea otters.
They shook the political earth as well. Anger over the tests spurred the creation of the environmental group Greenpeace. Frustration over the secrecy of reports from scientists warning about the environmental risks of the blasts was channeled into the creation of the Freedom of Information Act.
Federal officials issued abundant assurances at the time. "Based on extensive experience in underground nuclear weapon testing, any significant release of radioactivity does not appear even remotely possible," said a 1969 report from the Atomic Energy Commission.
But worries about radioactive leakage continue decades later.
On Sunday, Amchitka became the most remote of more than 100 former US nuclear sites to be managed under a new Department of Energy Legacy Management program. The three-year-old program oversees long-term monitoring and record-keeping. In addition, an ongoing Department of Labor program is helping former workers on Amchitka who have developed serious illnesses or disabilities.
Under the Legacy Management program, "long-term monitoring" means essentially forever, officials say. "Right now, there's really no end to it," says Peter Sanders, a Department of Energy project manager who recently traveled to Amchitka to check on its condition.
The drill holes and waste pits associated with the blasts are now covered with a multilayered mat, topped by new vegetation. There is no outward sign of any nuclear explosions, Mr. Sanders says. "If you didn't know what you were looking for, you wouldn't know what had happened out there," he says.
Under the Legacy Management program, the island will be monitored every five years to see if any radioactive contamination has leaked out, according to the department's plans. Such leakage has not happened, despite the frequent powerful earthquakes that shake that part of the Aleutians, according to Department of Energy studies.
After a five-year environmental restoration program on the island, the Department of Energy commissioned a comprehensive study to determine whether any seafood or other marine life was being harmed from lingering contamination. The conclusion of the study, released last year: There was no evidence that radioactive waste had entered the marine food chain.
But things could change, so the Legacy Management plan envisions periodic follow-up monitoring and some type of contingency planning after big earthquakes.
Environmentalists are skeptical. "The Department of Energy isn't assuming any real responsibility for ongoing monitoring or cleanup of what I think is inevitable leakage of radioactive waste into the Bering Sea," says Pam Miller, project manager of Alaska Community Action on Toxics, an environmental and public-health watchdog based in Anchorage.
A decade ago, Ms. Miller was a Greenpeace scientist who evaluated Amchitka vegetation. She and her colleagues say they found elevated levels of americium, a radioactive element.
Some also worry that high costs might limit the effectiveness of monitoring. The bare-bones Department of Energy expedition taken by Sanders and others in August cost nearly $500,000. Future trips will probably have to be coordinated with other agencies so that costs can be shared, officials say.
For many of the people who once worked on Amchitka, there is a different legacy. Former workers have high rates of certain kinds of cancer, such as leukemia, according to medical studies.
One worker is John Fletcher, who was sent to the island in the early 1970s. In his half-year on Amchitka, he left the island only twice, including a flight out to Anchorage on the morning of the Cannikin test. "Didn't think a thing about it. They said it was safe," he says.
Now, Mr. Fletcher works in an Anchorage office, helping administer a medical-claims program established for former Amchitka workers. The program was transferred from the Department of Energy to the Department of Labor recently after complaints that claims were being processed too slowly.
About 2,000 people who worked on the island from 1965 to 1971 are eligible. More than 600 had applied for compensation as of mid-2005.