Dec. 9—Ahead of mediation over Rio Grande water use, New Mexico’s attorney general is concerned the federal government will support stricter limits on groundwater pumping, which could inhibit the growth of southern New Mexico municipalities like Las Cruces.
Mediation between New Mexico, Texas, Colorado and the federal government is scheduled to begin Tuesday for a decade-long lawsuit about Rio Grande water use. The federal government wants to base water allocations on water usage in 1938 when the Rio Grande Compact was signed, which New Mexico Attorney General Raúl Torrez believes “would be devastating” to the state’s residents and economy.
“I would insist that New Mexico go to trial before conceding this issue,” Torrez wrote in a September letter to Interior Secretary Deb Haaland. The 1938 Rio Grande Compact between Colorado, New Mexico and Texas governs the division of water from the Rio Grande. Texas sued New Mexico in 2013 for excessive groundwater pumping, and the states reached a deal in 2022. But the federal government objected to the deal, and in June the Supreme Court ruled 5-4 the agreement needs the federal government’s support.
The states and the federal government will begin mediation Tuesday.
Torrez has written three letters to Haaland urging her to “prioritize a reasonable and amicable resolution” and met with Haaland, the former 1st District U.S. House representative from New Mexico, in August.
“Time is running out, and I am pleading with you to resolve this issue for the benefit of all the parties, but especially for the people of southern New Mexico, rather than leaving the matter to become a political bargaining chip for the next administration,” Torrez wrote in November.
New Mexico’s congressional delegation also asked Haaland and U.S. Attorney General Merrick Garland to quickly resolve the litigation in a November letter. The Department of Interior had not responded to a request for comment by the time this story went to press.
Torrez believes the United States’ position, that the Compact should use 1938 allocations as a baseline for water use, could have “disastrous consequences for water users and communities in southern New Mexico,” he wrote in a July letter.
The 1938 baseline would reflect water use in that year, when the compact was signed before widespread groundwater pumping.
In the late 1940s and 1950s, there was a serious drought, so farmers began using groundwater pumping to supplement their surface water. Both agricultural users and municipalities continue to use groundwater pumping.
The Bureau of Reclamation developed a linear regression model called the D2 Curve to reflect water use between 1951 and 1978, to allocate water between New Mexico and Texas farmers. That equation has been used by Reclamation since 1978 and was in the operating agreement for the Rio Grande Project in 2008.
Using a D2 baseline for water allocation is “from New Mexico’s perspective, non-negotiable,” Torrez wrote in a September letter.
The state has already conceded it exceeded groundwater pumping under the D2 condition in 2003 and 2004, said New Mexico Department of Justice Deputy Chief James Grayson.
“New Mexico is not advocating for more groundwater pumping than D2, but New Mexico and Texas and Colorado are all on the same page in terms of advocating for the D2 baseline as the baseline measure for how the compact and the requirements in the compact should be effectuated. If things went back to the 1938 condition, essentially what that would mean is that you have about a third of the total acreage in New Mexico that would have to be dried up.”
The Las Cruces City Council and the Doña Ana County Commission also opposed the U.S. litigation stance in resolutions passed in September and October.
The estimated annual economic loss to New Mexico of changing to the 1938 baseline could be up to $75 million, according to the Doña Ana County resolution.
“Pecan and chile farmers rely on groundwater and without access would not have enough water for their industries to survive,” the resolution reads.
The City of Las Cruces would not have enough water to maintain its current size, much less accommodate growth, under the 1938 standard, according to the Las Cruces City Council resolution. Las Cruces is the second most populous city in the state, with an estimated 115,000 residents.
Creating access to a different source of groundwater would cost an estimated $1 billion and take 15 years to implement, the resolution says.
The conflict over how to use Rio Grande water is not just state to state, but also about surface water irrigation versus groundwater irrigation, according to Burke Griggs, a water law professor at Washburn University in Kansas.
“I am encouraged to see the United States assert its interests in protecting federal irrigation infrastructure, because by protecting surface flows, you are protecting at least in part, the hydrologic integrity of a river system,” Griggs said.
“If you allow groundwater to take over, and that will come at the expense of surface flows, then you’re causing all sorts of harms, not just to surface irrigators, but also to environmental flows and potential endangered species issues.”