Miners digging for prosperity and national security in the 1950s left Stanislaus National Forest a riskier place.
Forest Service officials announced yesterday that the abandoned Juniper Uranium Mine, two miles southwest of Kennedy Meadows, is emitting more gamma radiation than previously thought.
The U.S. Environmental Protection Agency deemed the levels potentially harmful to people, and yesterday the Forest Service closed access to the site and to a half-mile of nearby Red Rock Creek.
The mine is located off Forest Road 5N33 on the Summit Ranger District.
The Forest Service will spend $2 million of federal Superfund dollars to put the mining waste back in the open mining pit and bury it. Superfund money pays to clean up hazardous material that could threaten people or the environment. Funds for this project are coming from the Comprehensive Environmental Response, Compensation and Liability Act.
The radiation comes from waste rock and tailings left after 10 years of mining that ended in 1966. The United States was in the middle of the Cold War, and prospectors would often take backhoes into the National Forest to search for uranium to produce weapons and power, said Stanislaus National Forest Historian Pam Connors.
Uranium occurs naturally in the Sierra Nevada, and, "there still are a lot of prospect pits in the high country," Connors said.
"It was just an area that was prospected a lot when that, as a strategic mineral, was really being sought after," she added.
Instead of complying with regulations that mining companies must meet today, prospectors in the '50s could enter the forest under an 1872 mining act and just start digging, Stanislaus spokesman Jerry Snyder said.
The mine was owned by three people whose names have not been released. Two of the people have since died, Snyder said, though both lived into their 80s and died of heart disease not cancer or any other problem related to working around uranium.
Tests that recorded elevated levels of radiation were taken last fall, Snyder said. Forest Service officials attributed the spike to waste rock from which dirt eroded and exposed uranium underneath.
The Forest Service was notified in March, but to comply with cleanup fund regulations, officials had to alert various parties from California senators to health officials to Tuolumne County supervisors before they could tell the public.
Snyder said the weather worked well for the Forest Service, as snow covered the site and restricted its access all spring. This gave officials time to make notifications without worrying about public health threats. Now that drifts are melting and high-country roads are accessible, Forest Service officials are blocking access to the site.
John Buckley, director of Twain Harte's Central Sierra Environmental Resource Center, said he didn't expect radiation to threaten wildlife around the old mine.
Still, he said, "I've never stood there for very long without thinking, 'you know, this probably isn't the best place to stand around and have a chat.'"