New Mexico environment officials and the federal officials charged with overseeing the treatment of contaminated groundwater below Los Alamos told lawmakers Monday that cleanup has stopped and remains at an impasse.

“At this date, we do not have a path forward,” said Michael Mikolanis, who heads the Office of Environmental Management in Los Alamos, said during a Radioactive and Hazardous Waste Materials interim committee meeting.

The hexavalent chromium plume was discovered in 2005. Chromium was used to line pipes to prevent rusting in the cooling towers for a power plant. Between 1956 and 1972, Los Alamos National Laboratory periodically flushed water down Sandia Canyon. It eventually seeped into the groundwater. The plume extends south of East Jemez Road toward San Ildefonso Pueblo.

NMED’s groundwater standard for chromium limits contamination to 50 parts per billion. Levels on the eastern edge of the plume showed concentrations at nearly 200 parts per billion, nearly four times the limit. Levels before treatment in the same area were at 300 parts per billion.

Hexavalent chromium – also called chromium-6 – can cause cancer if inhaled, but federal officials have not determined if it is classified as a carcinogen if ingested. A 2015 review by the National Institutes of Health noted there were “limited studies,” on the impacts of ingesting chromium-6 but linked to studies in China, noting higher rates of stomach cancer mortality in areas with higher chromium levels in aquifers.

State and federal officials agreed to the current method of treating the plume in 2015, after a year of disputes. The work plan included a series of wells to suck up the water, treat the water, and then pump treated water back into the aquifer. A similar plan was put forward in September last year.

An escalating disagreement over whether the data collected by the DOE on that treatment plan was sufficient, and concerns from state officials that the plan is further contaminating water brought cleanup to a halt in April, with no progress since.

Mikolanis said the changes to the plan are too extensive for an interim plan, and circumvent public approval requirements. NMED’s response is that the current plan may be worsening the plume, and the interim plan should change, while seeking a full remedy.

The cleanup stoppage on the chromium plume has meant the contamination has backslid, and potentially threatens drinking water for San Ildefonso Pueblo. San Ildefonso Pueblo officials did not respond to emailed requests for comment Monday.

The New Mexico Environment Department and the Department of Energy are currently in settlement discussions regarding the cleanup efforts but said they couldn’t provide any insight into those discussions or offer a timeline for resolution. Both said they thought the other was “acting in good faith,” and hoped lawsuits were unnecessary.

Rick Shean, the director at the Environment Protection Division at NMED, disagreed with Mikolanis’ assessment, telling lawmakers that reinjecting clean water at the current sites may be pushing chromium plume beyond detection areas.

“It will turn clean water – particularly under San Ildefonso – into contaminated water, because the plume will slip past the measures already in place to extract and clean it,” Shean said.

Mikolanis told Source NM his models do not support NMED’s conclusion.

“They have a hypothesis it’s pushing the plume down, there’s no evidence to show that we’re pushing the plume down, our model shows we’re containing it,” he said.

Shean told Source NM NMED doesn’t see evidence that the plume is being contained.

“It’s our interpretation of the data. We can sit in the same room and look at the same data and come to different conclusions,” Shean said.

Currently, Department of Energy officials said the plume does not threaten Los Alamos’ drinking water supplies. However, Los Alamos County shut down its highest producing groundwater well earlier this year because of its proximity to the plume, said Linda Matteson, the deputy county manager.

Mikolanis disputed that decision was solely made based on the plume’s proximity.

After a two-hour, often tense hearing, lawmakers agreed to direct the New Mexico Environment Department and the Department of Energy to contract with a third party to examine the DOE’s data and resolve the technical issues.

Mikolanis said the Department of Energy will make the funding available for hiring a third-party consultant. To ensure independence, he said the grant will be given to NMED to put out for bid.

Sen. Stefani Lord (R-Sandia Park) said she was dissatisfied with Mikolanis’ answers about the stoppage, saying that “that’s not a good answer to any of this stuff.” She asked if the DOE would restart water treatment within a year.

“I should hope by this time next year, we’ll resume the interim measure operation,” Mikolanis responded.

Rep. Christine Chandler (D-Los Alamos) said the conversation was always “in the weeds,” and had been since the discovery of the plume.

“Our conversation seems to just be constantly, just constantly disputes about where we should be drilling, what the appropriate corrective action is, et cetera,” she said.

Chandler asked Mikolanis in an exchange to define success, without going into the weeds.

“Tell me what real success is,” she asked.

“Real success is getting a remedy in place that’s going to get approval,” Mikolanis responded.

“And what outcome are we looking for?” Chandler prompted.

“We’re looking for clean water,” he said.