At a glance: Weapons sites converted into wildlife refuges

Six sites where the U.S. government manufactured or tested some of its most lethal weapons have been converted to wildlife refuges managed by the U.S. Fish and Wildlife Service:

- Amchitka Island, part of Alaska Maritime National Wildlife Refuge. Amchitka was the site of three U.S. underground nuclear tests in the 1960s and early 1970s. An unknown volume of radioactive material remains in caverns blasted out by the detonations. Part of the island is designated a wilderness area. The island is closed to the public.

- Big Oaks National Wildlife Refuge, Indiana, formerly Jefferson Proving Ground. The Army test-fired more than 24 million artillery rounds over half a century at the proving ground. The firing range remains littered with an estimated 154,000 pounds (70,000 kilograms) of shell fragments made of depleted uranium. The refuge is designated a globally important bird area by an avian conservation coalition. Part of the site is open to the public.

- Hanford Reach National Monument, Washington state. Nine reactors produced plutonium for U.S. nuclear weapons at Hanford. Amid the urgency of World War II and the Cold War, Hanford left behind vast quantities of contaminated soil and water. Its shrubby grassland and Columbia River habitat support mink and otters, threatened salmon and many other species. Part of the site is open to the public.

- Johnston Atoll National Wildlife Refuge in the central Pacific. Johnston Island, part of the atoll, was a launching pad for U.S. atmospheric nuclear tests in the 1960s. In 1962, two launches failed, scattering radioactive debris on the 1-square-mile (2.5-square-kilometer) island. The refuge is home to abundant seals and corals. It is closed to the public.

- Rocky Flats National Wildlife Refuge northwest of Denver. The U.S. Energy Department manufactured plutonium triggers for nuclear warheads at Rocky Flats. It had a long history of leaks, fires and environmental violations. Its rare tallgrass prairie is home to hundreds of species, including an endangered jumping mouse. Part of the site is open to the public.

- Rocky Mountain Arsenal National Wildlife Refuge in the northeast Denver suburbs. The Army manufactured chemical weapons at the arsenal and private companies made pesticides there. Bald eagles nested at the site, and wildlife officials have reintroduced bison and endangered ferrets. Part of the site is open to the public.