Much of the uranium for Cold War weapons and the nation’s once-burgeoning nuclear power industry was mined on or near Navajo land in Arizona and New Mexico, and it left behind contamination.

When California Democrat Henry A. Waxman became chairman of the House Oversight and Government Reform Committee in 2007, he held a series of hearings on the toxic aftermath of the mining and was part of a group that persuaded the government to come up with a five-year plan to deal with it.

As Waxman nears retirement this year, he is trying again to draw the nation’s attention to the environmental and heath consequences of uranium operations in the Southwest.

“It is a modern American tragedy,” Waxman told the Nuclear Regulatory Commission at a hearing this month, repeating the same words he used seven years ago. “For decades, the Navajo nation has been dealing with the deadly consequences of radioactive pollution from uranium mining and milling.”

The commission is expected to hear a proposal to add more waste to the 3.5 million tons of mine tailings, capped to keep them from spreading, at a site 17 miles northeast of Gallup, N.M. The site is surrounded by Navajo land where farmers graze livestock on hillsides and live in homes near abandoned mines.

Without realizing the implications, and with no one to tell them, people in the area built houses with radioactive material, drank contaminated water and drove down dirt roads kicking up radioactive dust.

Waxman is intent on making sure the uranium waste issue does not fade into obscurity once he leaves his bully pulpit.

“The commission needs to make this project a priority,” he said.

Following decades of mining in the vicinity, the United Nuclear Corporation (now owned by General Electric) began milling operations along an intermittent streambed in 1977, crushing, grinding and acid-leaching uranium ore from the nearby Northeast Church Rock and Old Church Rock mines. The processed tailings were stored in impoundments and water was pumped from the drying cells — think of ponds or paddocks — treated and discharged into the arroyo, which flowed with effluent from water pumped out of mines.

In 1979, the mill was the site of what by some accounts was the nation’s worst nuclear accident when a breached dam released tons of acidic uranium slurry into the adjoining arroyo and down the Puerco River.

Due to its remoteness, the site has received less attention than Three Mile Island and other nuclear industry accidents. Cleanup from the spill was limited, and mill operations continued at the site until 1982.

From the Ground Down

The NRC took over the site from the state of New Mexico in 1986, and required that the tailings be capped and groundwater decontaminated. There has been limited progress. The water table, which had been elevated from decades of mine discharge, is now 17 feet to 70 feet below the capped tailings.

A grass-roots community group brought attention to high levels of contamination at the nearby Northeast Church Rock mine site in 2003. The Environmental Protection Agency excavated contaminated soil from around homes near the mine and required a plan to excavate more material. As part of those cleanup efforts, the agency wants to have the company excavate highly contaminated material from the mine site to be disposed of at a hazardous-waste facility. The agency has also proposed moving 1 million cubic yards of less contaminated material from around the mine to the nearby mill site, to be capped and monitored.

In March 2013, the EPA laid out general guidelines for the proposed project, including the use of an impermeable layer between the tailings deposits already on the mill site and the contaminated material to be added. Staff members from the Department of Energy and the NRC have expressed concern that a barrier layer between the two mounds of material could present engineering or contamination problems. Water seeping into the mound, for instance, could be pushed laterally along the inner impermeable layer, potentially destabilizing the mound and flushing contamination out to the surface.

Residents near the facility object to the plans as well, calling instead for the company to dispose of the material in other waste facilities.

“With simple earth movement or heavy rain, we would have another situation as the previous cell breakage,” wrote a woman whose family kept livestock near the site and who blamed her unsightly toes on wading into the yellow-green water to fix a fence after the accident in 1979. “Please store the waste offsite,” she wrote.

The EPA, which shares jurisdiction over the site with the NRC, has stipulated that the cover be designed to last 200 years and be constructed to resist erosion and other expected wear.

The company filed an application with the NRC to amend its license to extend the current site activities to 2019. “We have been proactively working with them,” NRC Chairwoman Allison Macfarlane told Waxman and other House members. “We’re trying to be proactive and meet with them and make sure they understand our requirements and understand our needs. We need a high-quality application.”

The commission will take two years to review the application, which it expects in 2016, she said.

Meanwhile, the Government Accountability Office issued a report this month calling for a deeper examination of uranium contamination on Navajo land.

“Congress,” the GAO wrote, “should consider requiring federal agencies to develop an overall estimate of the remaining scope of work, time frames, and costs to fully address uranium contamination.”