Colorado was also a source of uranium, with many mines along the Dolores River corridor, and mills were built in Grand Junction, Durango, and Uravan.

As with the Navajo, little heed was paid to the dangers of uranium mill waste in Colorado, most of which was stockpiled in unsecured heaps in mining areas like Uravan. That’s where waste was piled high immediately adjacent to the Dolores River. Tailings piles were also located at the Climax Uranium Co. mill in Grand Junction.

When Grand Junction residents found out that the Climax Uranium mill operator didn’t care what happened to the sandy tailings and had opened the waste pile to the public, community members began loading up truckloads to use as fill and, because it was slightly acidic, to apply to their gardens to help plants grow.

Grand Junction residents weren’t told the waste was still radioactive either.

“In 1966, the Colorado Department of Health accidentally discovered that the tailings had been used in houses, churches and schools, generally as bedding on which floors and foundations were placed. The state officials, alarmed, made sure this stopped,” said Judy Pasternak, who authored the acclaimed 2010 book on the subject; “Yellow Dirt — A Poisoned Land and the Betrayal of the Navajos.” “To have the people of Grand Junction irradiated in their own homes, even at low levels, was unacceptable at best, perilous at worst.”

Concerned that the fill created an “incubator for radon gas,” Colorado authorities asked the U.S. Public Health Service for funding to look for radon emissions that might be associated with the fill material. But, in 1968, the Atomic Energy Commission, predecessor to the Nuclear Regulatory Commission, denied funding, saying that any radon found was probably from naturally occurring soil sources.

According to Pasternak, the AEC tried to suppress its own report, but Wayne Aspinall, then Grand Junction’s representative in the U.S. House of Representatives, convinced officials to act, and some 4,000 private and commercial properties had the radioactive fill removed at a cost of $250 million.

Remediation of radioactive waste in and around homes and other structures on the Navajo Nation received no such concerted effort. Even today, the Navajo Nation doesn’t have the money to perform detailed radiation scans of all homes, much less remediate them, said Stephen Etsitty, executive director of the Navajo Nation Environmental Protection Agency.