Such a comprehensive cleanup is "exactly what Superfund was designed for," said Paul Connor, a lawyer who once directed Superfund enforcement policy for the Environmental Protection Agency.

It hasn't happened. Bureaucratic delays and misunderstandings between the tribe and the EPA have prevented the Navajos from tapping Superfund's deep pockets and broad legal authority.

Instead, the tribe reluctantly settled for a partial cleanup under a separate program. That effort left many hazards untouched.

One of them is in Church Rock Mine, a Navajo community named for an abandoned uranium site. A 30-foot-high heap of grit and dynamited stone from the mine looms over a cluster of 15 homes. The wind roars for hours at a time, scattering radioactive dust throughout the settlement.

For years, residents appealed to tribal leaders and the U.S. government for help. In 2003, tired of waiting, they joined forces with Navajo activists who were using a foundation grant to conduct radiation testing.

In a dry wash where generations of children had played catch and tag, they discovered elevated radiation levels.

As word spread of the citizen effort, authorities stirred at last. Under pressure from the tribe, the EPA opened negotiations with the mine's operator, United Nuclear Corp., and its parent, General Electric Co., to clean up the mess.

If the companies eventually foot the bill, it would mark the first time a polluter has been held to account under Superfund for contaminating the reservation.

But like the Church Rock families, members of other Navajo communities are done waiting for the government to act. They have reached out to environmental groups or university scientists, hoping to fashion their own solutions.

"The Navajos need a champion," said Glynn R. Alsup, a retired Army Corps of Engineers official who served as a liaison to the Navajos. "The EPA and the tribe should be knocking on doors in Congress every year if they need money. I don't see that happening."

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Thwarted efforts

The Navajos allowed intensive uranium mining by private companies starting in the 1940s. The lone buyer of the uranium was the federal government. The nuclear arms race with the Soviet Union was just beginning, and U.S. officials were desperate for material to make atomic bombs.

In contracts typed on onion-skin paper, the companies promised to leave the land "in as good condition as received." The federal Bureau of Indian Affairs approved all leases and was supposed to enforce their terms.

When demand for uranium eased in the late 1950s, mines and processing mills began to close. The operators often left behind open tunnels and shafts and piles of radioactive tailings. Rarely did they fence off the sites or post warning signs. Federal inspectors knew of the hazards but seldom intervened.

Decades passed. As former miners were dying of lung cancer and respiratory disease in the 1970s, their widows started to wonder whether they and their children were endangered by the detritus of the uranium boom.

In 1982, the tribal government demanded $6.7 million from a federal claims court to seal and clean about 300 mines. The tribe argued that federal inspectors had failed to enforce safety standards in order to keep down the price of bomb material.

A judge rejected the claim in 1985, calling the allegations "entirely speculative."