By Susan Montoya Bryan, Associated Press

ALBUQUERQUE, N.M. (AP) — The tribal community of San Ildefonso Pueblo sits in the shadow of Los Alamos National Laboratory, one of the nation's premier laboratories and the birthplace of the atomic bomb.

The tribe is on the front lines of a battle to rein in contamination left behind by decades of bomb-making and nuclear research.

Pueblo Gov. James Mountain says he's encouraged that New Mexico regulators, under a revamped cleanup proposal, have identified as a priority a plume of chromium contamination at the tribe's border with the lab.

San Ildefonso Pueblo, in northern New Mexico's high desert, has a tribal enrollment of about 750. Its members are known for their artistry, creating jewelry, paintings, traditional black-on-black pottery and other works.

Groundwater sampling shows increasing chromium concentrations at the edges of the plume, indicating it's migrating through an area considered sacred by the tribe and closer to the Rio Grande, which provides drinking water to communities throughout the region.

The plume has stretched about 1 mile into the upper part of the regional aquifer, and is about a half-mile wide and 100 feet thick.

It's about a half-mile from the closest drinking water well.

"Without a doubt, it definitely raises concerns," Mountain said.

The contamination was first detected more than a decade ago, and officials traced it to potassium dichromate used to prevent corrosion inside cooling towers at Los Alamos lab's power plant. As part of regular maintenance from 1956 to 1972, the chemicals were discharged into canyons below.

The lab has spent years trying to better understand the plume to ensure actions taken to address the contamination don't make matters worse.

Federal officials last fall proposed using a combination of extraction and injection wells to keep the plume from making it to tribal land. The first of the injection wells were drilled in March.

Under the draft cleanup proposal unveiled by the state, a series of reports would be required, and initial pumping and treatment could begin next fiscal year.

Officials would then have to develop a final corrective action plan. Implementation could take four to five years.

The U.S. Energy Department's Office of Environmental Management is asking for $189 million for work at the lab next fiscal year. That would pay for handling radioactive waste stored at the lab, as well as completing the chromium investigation.

Ryan Flynn, head of the New Mexico Environment Department, has said the amount the federal government needs to funnel to contamination at Los Alamos should be closer to $255 million a year. He said the potential effect of chromium on the groundwater supply is just one reason the project is a priority.

"The essence is groundwater is precious in New Mexico so we take threats to groundwater very seriously," he said. "We certainly think there's an elevated risk associated with any contamination to groundwater."

The current plan calls for extracting up to 230 million gallons a year over several years, treating that water so it meets health standards and injecting it back into the aquifer or spreading it in select areas using water trucks or irrigation systems.

All the work would be done on lab property, which boasts dozens of archaeological sites — from dwellings carved into the canyon walls to a large pueblo that once had 100-plus rooms, a plaza and kiva.

The area also is home to flaked stone tools, ceramic shards and even a wagon road that dates back to the homestead period of the 1800s.

"It's a very important area to the pueblo," Mountain said. "And it's not just on the parameters of physical inhabitation. There's an effect on the pueblo's health and welfare, on our mental well-being, our spiritual well-being."

To Learn More:

New Mexico Fines U.S. over Nuclear Waste Violations (by Danny Biederman and Noel Brinkerhoff, AllGov)

The Nuclear Waste Leak in New Mexico…Maybe It Wasn’t the Kitty Litter After All (by Noel Brinkerhoff, AllGov)