NMED to brief Los Alamos Board on LANL chromium plume March 4

Michael Petersen, MS, hydrogeologist with the New Mexico Environment Department, and Caitlin Martinez, acting NMED LANL Group Manager, are scheduled to appear before the Los Alamos Board of Utilities work session at 5:30 p.m. March 4 in Council Chambers at the Municipal Building to present on the San Ildefonso Mortandad Regional 3 monitoring well.

"San Ildefonso Mortandad Regional 3 (SIMR-3) a groundwater monitoring well located on Pueblo de San Ildefonso land within Mortandad Canyon that was installed as part of the cleanup effort for the hexavalent chromium plume beneath Los Alamos National Laboratory." The SIMR-3 site sits on Pueblo land inside Mortandad Canyon and was installed specifically for monitoring the LANL hexavalent chromium plume, a subject that drew NMED enforcement action late last year.

"In November 2025, NMED ordered DOE-EMLA immediately cease all injection operations associated with the plume due to analytical results showing that the sole source regional aquifer beneath the Pueblo exhibits hexavalent chromium concentrations exceeding the regulatory standards set forth in the New Mexico Administrative Code." That cease-order to the U.S. Department of Energy’s Environmental Management Los Alamos field office is the most recent regulatory action tied to the plume and frames what NMED says will be covered in the March 4 briefing.

Local utilities governance provides the meeting context: the Los Alamos Board of Public Utilities previously recommended County Council approve Ordinance No. 7-45 and related resolutions to fund wastewater treatment plant upgrades and pursue state funding. Utilities staff member James told the board the award totals $2,000,000 and that $250,000 of that amount is a loan subsidy (a grant-like subsidy within the loan package). The proposed work program items include repairing cracks and applying protective coatings to aeration basins, replacing the fine screen at the headworks, replacing ultraviolet disinfection equipment, improving HVAC in the blower building to prevent overheating of motors, and replacing various motor control centers and electrical controls.

NMED and DOE-EM-LA have a record of public meetings on LANL cleanup planning dating back to January 16, 2018 and December 16, 2019, and most recently an annual planning public meeting held March 29, 2023 for FFY 2023 Appendix B under the 2016 Consent Order Section VIII.C.3.d. Technical correspondence and documents tied to LANL groundwater oversight include identifiers such as EM2024-0761 and N3B 2024, and a June 28, 2023 NMED letter titled "Review Fate and Transport Modeling and Risk Assessment Report for RDX Contamination in Deep Groundwater, Revision 1" addressed to A. Duran at DOE-EM-LA from R. Shean at NMED.

The Northern New Mexico Citizens’ Advisory Board meeting minutes from July 16, 2025 list DOE and EM-LA participants including Sarah "Ellie" Gilbertson, Kelly Snyder, John Evans, Allison Scott Majure, Robert Reine, Jeff Silvera, and Patrick Moss, and show ongoing interagency engagement around LANL corrective actions. For archival contact on LANL environmental surveillance materials, the Environmental Assessments and Resource Evaluations Group at Los Alamos National Laboratory can be reached, attention Julie Johnston, Mail Stop M887, P.O. BOX 1663, Los Alamos, NM 87545, telephone (505) 665-0231.

The March 4 work session in Council Chambers is the next scheduled public briefing where Petersen and Martinez will present monitoring well information on SIMR-3 and the regulatory backdrop after the November 2025 injection cease-order; county officials and tribal land stewards will have the opportunity to hear the latest monitoring and enforcement updates at 5:30 p.m.