El Paso filed a lawsuit Tuesday in U.S. District Court against the Department of Energy and other federal agencies, seeking cleanup of debris from an old uranium processing mill that the company operated.
The company also has offered to press Congress for funding and to take protective steps at two old dump sites where radioactive material has surfaced.
The moves come in response to a recent ultimatum from the tribe, which is pursuing a cleanup across the Navajo Nation of contamination left by the uranium industry in its quest for atomic-bomb fuel. The tribe hired California lawyer John C. Hueston to oversee the effort.
El Paso was responding to evidence the Navajos presented showing its links to buried radioactive debris that has been exposed by erosion.
The response is "just what we were hoping for," Hueston said. "This will establish an important precedent for other companies."
Elsewhere on the reservation, the U.S. Environmental Protection Agency, after prodding from the tribe, has begun moving a small group of residents to temporary lodging while radium-tainted soil is removed from their homes. A pile of mine waste looms nearby.
Four abandoned uranium processing mills and more than 1,000 old mines are scattered across the Navajo Nation, which spans parts of Arizona, Utah and New Mexico. The federal government was the sole customer for the privately operated mines and mills, from the days of the Manhattan Project in the 1940s until 1971.
The U.S. says all four mill sites and about 900 mines have been reclaimed. But the recent steps highlight the shortcomings of the cleanup effort and the extent to which the job remains unfinished.
A four-part series in the Los Angeles Times in November chronicled the lags as well as evidence Navajos have died from toxic exposure. Hueston, a former federal prosecutor who won convictions in the Enron Corp. fraud case, read the series and contacted the tribe.
El Paso and a former subsidiary, Rare Metals Corp. of America, ran a processing mill in Tuba City, Ariz., from 1956 to 1966. For 20 years after it closed, desert winds spread radioactive dust from the tailings pile.
The Energy Department finally covered the pile, but Navajo lawyers contend that the agency's failure to install a lining beneath it polluted the groundwater.
In 2003, erosion exposed long-buried mill debris, but Energy Department officials say their cleanup authority has expired.
Dangerous levels of uranium have recently been recorded in wells on both Navajo and adjacent Hopi lands.
In a Monday meeting in Los Angeles, El Paso outlined a plan to lobby members of Congress from Arizona and New Mexico and those on key committees to get federal financing for additional work.
The company also pledged to install a chemical seal over the old dump sites and erect chain-link fencing.
To read the Navajo series online, go to latimes.com/navajo.