CAMERON, Ariz. — In the summer of 2010, a Navajo cattle rancher named Larry Gordy stumbled upon an abandoned uranium mine in the middle of his grazing land and figured he had better call in the feds. Engineers from the Environmental Protection Agency arrived a few months later, Geiger counters in hand, and found radioactivity levels that buried the needles on their equipment.
The abandoned mine here, about 60 miles east of the Grand Canyon, joins the list of hundreds of such sites identified across the 27,000 square miles of Navajo territory in Arizona, Utah and New Mexico that are the legacy of shoddy mining practices and federal neglect. From the 1940s through the 1980s, the mines supplied critical materials to the nation’s nuclear weapons program.
For years, unsuspecting Navajos inhaled radioactive dust and drank contaminated well water. Many of them became sick with cancer and other diseases.
The radioactivity at the former mine is said to measure one million counts per minute, translating to a human dose that scientists say can lead directly to malignant tumors and other serious health damage, according to Lee Greer, a biologist at La Sierra University in Riverside, Calif. Two days of exposure at the Cameron site would expose a person to more external radiation than the Nuclear Regulatory Commission considers safe for an entire year.
The E.P.A. filed a report on the rancher’s find early last year and pledged to continue its environmental review. But there are still no warning signs or fencing around the secluded and decaying site. Crushed beer cans and spent shell casings dot the ground, revealing that the old mine has become a sort of toxic playground.
“If this level of radioactivity were found in a middle-class suburb, the response would be immediate and aggressive,” said Doug Brugge, a public health professor at Tufts University medical school and an expert on uranium. “The site is remote, but there are obviously people spending time on it. Don’t they deserve some concern?”
Navajo advocates, scientists and politicians are asking the same question.
The discovery came in the midst of the largest federal effort to date to clean up uranium mines on the vast Indian reservation. A hearing in 2007 before the House Committee on Oversight and Government Reform led to a multiagency effort to assess and clean up hundreds of structures on the reservation through a five-year plan that ends this year.
Yet while some mines have been “surgically scraped” of contamination and are impressive showpieces for the E.P.A., others, like the Cameron site, are still contaminated. Officials at the E.P.A. and the Department of Energy attribute the delay to the complexity of prioritizing mine sites. Some say it is also about politics and money.
“The government can’t afford it; that’s a big reason why it hasn’t stepped in and done more,” said Bob Darr, a public relations specialist for the environmental consulting firm S.M. Stoller, which does contracting work for the Department of Energy. “The contamination problem is vast.”
If the government can track down a responsible party, he said, it could require it to pay for remediation. But most of the mining companies that operated on the reservation have long since gone out of business, Mr. Darr said.
To date, the E.P.A., the Department of Energy and other agencies have evaluated 683 mine sites on the land and have selected 34 structures and 12 residential yards for remediation. The E.P.A. alone has spent $60 million on assessment and cleanup.
Cleaning up all the mines would cost hundreds of millions of dollars, said Clancy Tenley, a senior E.P.A. official who oversees the uranium legacy program for the agency in the Southwest.
Some say the effort has been marred by bureaucratic squabbles and a tendency to duck responsibility. “I’ll be the first to admit that the D.O.E. could work better with the E.P.A.,” said David Shafer, an environmental manager at the energy agency.
Determining whether uranium is a result of past mining or is naturally occurring is “a real debate” and can delay addressing the problem, Mr. Shafer said. He cited seepage of uranium contaminants into the San Juan River, which runs along the boundary of the reservation, as an example. “We need to look at things like this collectively and not just say it’s E.P.A.’s problem or D.O.E.’s problem,” he said.