New Mexico to update public on LANL chromium plume cleanup
State regulators briefed the public in Santa Fe on LANL’s chromium plume cleanup as compliance orders, dispute talks and Pueblo land impacts sharpened the stakes.
New Mexico environmental regulators met with the public in Santa Fe on June 25 to update residents on the hexavalent chromium plume cleanup beneath Los Alamos National Laboratory, a problem now moving through active compliance orders and technical dispute resolution. The session ran from 5:30 p.m. to 7 p.m. at Harold Runnels Auditorium, with a WebEx option for people who could not make the trip.
The plume has been tracked for more than two decades. It was first detected in 2004 in a regional aquifer monitoring well above New Mexico’s groundwater standard of 50 micrograms per liter. The contamination traces to potassium dichromate used from 1956 to 1972 as a corrosion inhibitor at LANL’s non-nuclear power plant. It sits in the regional groundwater aquifer about 1,000 feet beneath Mortandad and Sandia Canyons.
On Feb. 11, 2026, the New Mexico Environment Department issued two Administrative Compliance Orders related to the plume and the groundwater discharge permit. DOE and Newport News Nuclear BWXT-Los Alamos LLC filed answers and requests for hearings on March 13, and technical dispute resolution with the department began March 18.
In November 2025, chromium contamination had migrated onto Pueblo de San Ildefonso land, the New Mexico Environment Department said. The department said there was no imminent threat to drinking water on the pueblo or in Los Alamos County, but also that the migration showed DOE’s containment efforts had been inadequate.
DOE is working with NMED, the New Mexico Office of the State Engineer, Pueblo de San Ildefonso and Los Alamos County on the plume. DOE has installed a network of wells, continues groundwater monitoring and operates a treatment system to remove hexavalent chromium from the aquifer. The 2016 Compliance Order on Consent remains the regulatory framework for the work, the Fiscal Year 2026 updates to its appendices were completed in October 2025, and an independent technical review of the chromium interim measures remediation system began in early 2024.
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