Texas v. New Mexico: How the Court’s Decision for the Rio Grande May Affect Colorado River Negotiations

By Kyra Haas. 

The United States Supreme Court’s forthcoming decision in Texas v. New Mexico and Colorado may drastically change the federal government’s involvement (or lack thereof) in how states form agreements with other states regarding water resources. 

A deadline looms large over Arizona and the other six Colorado River Basin states to devise new plans for the Colorado River, and Texas v. New Mexico threatens to inject unnecessary uncertainty into ongoing negotiations. The current rules for how Colorado River water is allocated are set to expire in 2026. Unless the states come together and put forward an agreement for federal approval, they run the risk of the federal government making decisions for them. If the Supreme Court allows the federal government to undo the interstate agreement at issue in Texas v. New Mexico, the Colorado River Basin states may be further disincentivized from finding a suitable compromise among themselves, as it could be thrown out if the federal government objects.

The States Agree But the Feds Demand a Say

Texas v. New Mexico involves a decade-long dispute between Texas, New Mexico, and Colorado regarding allocations of the Rio Grande. Texas initially accused New Mexico in 2013 of violating the Rio Grande Compact of 1938 by overdrawing its allotments through groundwater pumping. The Compact requires Colorado to deliver a certain amount of Rio Grande water to the New Mexico border and requires New Mexico to deliver a certain amount of water to the Elephant Butte Reservoir, which is about 100 miles inside New Mexico. This water is stored and then some is released for irrigation in Texas and deliveries to Mexico.

Eventually, the three states came to an agreement about the River in January 2023. The Special Master signed off, finding their proposed consent decree reasonable and compatible with the 1938 Compact. The Special Master recommended the United States Supreme Court approve the plan.

But then the United States, which was not a party to the agreement, objected and sought to override the states’ compromise, arguing that it should have a say in the agreement as an intervener in the case; that the decree imposes undue obligations on the federal government; and that the consent decree is contrary to the Compact. The United States’ demand for unprecedented involvement set off alarm bells for 23 states, who argued in an amici brief that allowing this level of federal intervention is an “obvious affront to federalism and States’ sovereign powers.”

Using Colorado River-related statutes as support, the states also argue that federal water projects involving Compact water are subject to that compact and “must operate within the compact framework.”

To avoid disrupting interstate agreements, the Court should approve the states’ proposed consent decree, which factors in issues like climate change, groundwater use, and modern environmental laws that were not top of mind when many interstate compacts were first drafted. To do otherwise would chill negotiations among states because the federal government could essentially trump any state-level agreement.

Modern Compacts, Modern Concerns

Since the three states signed the Rio Grande Compact of 1938, the world of water has evolved in ways early-twentieth-century interstate water compacts did not contemplate. This is also true for the Colorado River Compact of 1922, which overallocated its resources from the start and failed to consider the water use of tribes and Mexico. Subsequent twentieth-century Colorado River agreements that make up “the law of the River” have addressed several of these issues while still omitting some of the basin’s current concerns.

Groundwater pumping and climate change in particular greatly affect water levels and their associated allocations. Groundwater use swelled after World War II, thanks to pumping innovations and rural electrification. Most early interstate compacts exclusively dealt with surface water. But groundwater and surface water, while sometimes separately regulated, are deeply intertwined, as Texas v. New Mexico illustrates, with groundwater pumping affecting the flow of surface water in the River.

Climate change manifests differently in different parts of the country but greatly affects interstate water compacts. The Colorado River Compact, of which Arizona is a party, is a good example, as the ongoing drought intensifies state negotiations about who should bear the brunt of necessary water cuts.

Effects On the Colorado River Basin

Of the seven Colorado Basin states, Utah, Wyoming, and Arizona signed onto the states’ amici brief in Texas v. New Mexico. Basin states Colorado and New Mexico, both parties to the agreement in dispute, also oppose federal intervention in their states-level compromise. The only Colorado Basin states that did not weigh in were two of the three Lower Basin states: California and Nevada. 

The Bureau of Reclamation has asked the Colorado River Basin states to submit proposals for post-2026 plans in March, which appears unlikely as the Upper and Lower basins continue to hash out an agreement that must factor in drought and climate change. The states can still submit a unified proposal after the March deadline if they come to an agreement. 

But depending on the scope of the ruling, if the United States Supreme Court allows the federal government to essentially nix the Texas, New Mexico, and Colorado consent decree, this would dissuade the states from pursuing an amicable state-level outcome. 

To be sure, the federal government has more involvement in the Colorado River Basin than many other waterways that cross state lines, but this involvement has always been subject to the states’ agreements. As the amici expressed: “Unless a compacting State expressly cedes its sovereign authority, the United States does not have a role in the management of state water, including the interpretation or enforcement of interstate water compacts.”

To protect state sovereignty and efforts to update longstanding interstate water compacts among many states across the country, the Supreme Court should approve the states’ consent decree. 

The Court will hear oral arguments on this issue on March 20, 2024.

"Grand Canyon National Park: Marble Canyon - Colorado River" by Grand Canyon NPS is licensed under CC BY 2.0.