State experts brief committee on brackish groundwater and desalination options

The Senate Conservation Committee heard a technical briefing Thursday on brackish groundwater resources and desalination methods from Stacey Timmons of the New Mexico Bureau of Geology and Robert Fowley of Jacobs Engineering.

Stacy Timmons, associate director for hydrogeology programs at New Mexico Tech's Bureau of Geology, summarized statewide data showing brackish water (roughly >1,000 parts per million total dissolved solids) occurs in many basins and at varying depths. She said the bureau's mapping work has identified basins such as Albuquerque, San Juan, Tularosa, Roswell and the Capitan Reef as areas with brackish resources and emphasized the need for site‑specific geology, hydrology and water‑chemistry work before treatment design. "As you're looking just at the color scheme across the map, you can see that Alamogordo and Tularosa have a lot of brackish water," Timmons said, noting domestic and irrigation wells in some places already use slightly saline water.

Timmons described the types of data needed before a desalination project: aquifer characterization, exploratory wells, geophysics, water‑chemistry analyses (including environmental tracers and radionuclide screening) and hydraulic testing. She noted that state rules and the Water Data Act generally require data from state‑funded studies be made available to the state.

Robert Fowley, vice president at Jacobs Engineering, described treatment processes in current use. He said reverse osmosis (RO) is the standard, time‑tested method for reducing TDS from brackish sources; RO produces a low‑TDS "permeate" and a higher‑TDS concentrate. Fowley explained common concentrate disposal options used in the region: lined evaporation ponds, deep injection wells (used outside New Mexico in some cases) and, in limited circumstances, sanitary sewer disposal when permitted and appropriate. He described the Alamogordo desalination plant, noting its roughly 1,000,000‑gallon‑per‑day design and that site topography reduced pumping energy needs there.

Senators asked about costs, recovery rates and constituents. Fowley said construction costs for treatment plants vary with scale and market conditions; the Alamogordo plant had cost about $10 million when built and current estimates for a one‑million‑gallon‑a‑day treatment plant are in the low‑to‑mid tens of millions of dollars. He and Timmons said pilot testing is required for design and regulatory approvals, and that RO permeate is typically very low in TDS while concentrate requires controlled disposal. Committee members discussed operational costs and disposal pathways; one senator noted typical operational cost estimates he had seen ranged from a few cents to tens of cents per gallon, and witnesses said operational costs depend on recovery rate, energy needs and how often the plant runs.

Both presenters stressed that brackish desalination is a site‑specific process requiring substantial upfront study and regulatory coordination. Timmons said projects can take multiple years from study to construction and that state monitoring and data collection are important to evaluate recharge, aquifer interactions and potential impacts to existing water users.

Committee members said the briefing would inform upcoming floor votes on water measures.