New Mexico plans Supreme Court settlement filing in Texas v. New Mexico; ISC to reduce Lower Rio Grande groundwater depletions by about 18,200 acre‑feet

New Mexico officials said Tuesday they plan to file proposed settlement documents with the U.S. Supreme Court’s special master on Aug. 29 to resolve Texas v. New Mexico, and outlined a framework that would require the state to reduce groundwater depletions in the Lower Rio Grande by roughly 18,200 acre‑feet.

What the state will file Nat Shakiris, general counsel to the Office of the State Engineer, told the committee that the settling parties have agreed in principle on a package of documents. The package will ask a magistrate or special master appointed by the U.S. Supreme Court to enter consent decrees resolving the interstate compact dispute, and will include settlement agreements among New Mexico, the irrigation districts and federal reclamation authorities to facilitate balance transfers of project water.

The central compliance measure disclosed to the committee is a reduction of ground‑water depletions in the Lower Rio Grande “to approximately the levels that we had” in the 1951–1978 (D‑2) period, Shakiris said. The state expects most of the reductions to be achieved by acquiring and retiring water rights presently used for irrigation; the settlement gives New Mexico up to about 10 years to complete purchases, though state officials said they plan to act more rapidly where possible.

Why it matters: the scale, costs and timing Shakiris and Hannah Risley White, director of the Interstate Stream Commission, said the package is intended to provide a predictable, implementable path to compact compliance. ISC described ongoing programs that would run alongside a purchase program: a voluntary groundwater conservation program implemented in partnership with local conservation districts that enrolled more than 6,000 acres and is projected to conserve 12,000–16,000 acre‑feet through 2025; cooperative work with Elephant Butte Irrigation District to improve conveyance efficiency and identify stormwater capture and managed aquifer recharge locations; and airborne electromagnetic surveys and test drilling to support brackish‑water development.

Elephant Butte Irrigation District (EBID) manager Josh Smith told the committee EBID is pursuing piping and lining projects to cut conveyance losses (the district estimated irrigation efficiency currently around 55%) and is pursuing stormwater capture locations at diversion points. Smith said EBID has spent roughly $2.8 million under a cooperative agreement with the state and expects additional funds (roughly $11 million referenced in testimony) will be used for maintenance, dam and drain work and stormwater infrastructure.

City of Las Cruces utilities director Adrienne Widmer described municipal water‑and‑wastewater operations: the city returns treated effluent to the river, runs two wastewater plants (Jacob Hands plant average about 9.5 million gallons per day), and uses active monitoring, advanced metering infrastructure and a “Utility Hawk” customer portal for leak notification and conservation outreach. Widmer noted the city currently diverts a small share of total groundwater (about 7.3% of annual groundwater diversions cited in testimony) and returns nearly half of its diversion as treated effluent to the river.

Immediate conditions and next steps EBID reported extremely low reservoir storage: Caballo was shown with roughly 4,000 acre‑feet and Elephant Butte at under 4% capacity. EBID’s standard allotment is 3.024 acre‑feet per water right; this year EBID delivered six inches (0.5 foot) in many cases, and Smith said that low delivery forced increased pumping and pressure on the system.

Shakiris said the settlement will require a multi‑year procurement and verification program to acquire irrigation water rights or other reductions and that the state will be working with stakeholders to reduce negative externalities and to phase changes so municipal, industrial and essential uses are preserved.

Ending note State counsel said the filing next month will be followed by briefings to the legislature (an executive session and additional briefings were planned) and by more detailed economic cost assessments. Officials told the committee they will work with water users, districts and municipalities to finalize implementation mechanisms, and that the Lower Rio Grande Water Alliance and other work groups will help coordinate habitat, stormwater and recharge work alongside any rights purchases or fallowing programs.