Texas Hoping for Edge Over New Mexico in Battle Over Rio Grande

With the official support of the U.S. government, Texas now hopes it has a substantial edge over New Mexico in an interstate legal battle over water from the Rio Grande.

Earlier this week, the U.S. Supreme Court granted the U.S. solicitor general’s motion to sit on the same bench as Texas in the state’s suit against New Mexico. 

For the Texas Commission on Environment Quality and other supporting parties, this puts the state one step closer to regaining rights — and water — for Texas farmers.

“This is nowhere near a victory in litigation, but it’s certainly an interim victory,” said Andrew Miller, an attorney who has filed a brief in support of the state’s position.

New Mexico has maintained its position that its obligations are to its own reservoirs — not to the water needs of Texas or Mexico. 

In June 2013, Texas filed a complaint before the U.S. Supreme Court alleging that New Mexico farmers were tapping too much water from the Rio Grande, the river the two states share. New Mexico in turn argued that the Rio Grande Compact — a 1938 interstate deal meant to ensure Texas received flows from the river — never specified how much water was earmarked for Texas. 

The Rio Grande starts in Colorado and flows south through New Mexico, crossing into Texas near El Paso, where it turns southeast and effectively serves as the border between the U.S. and Mexico for over 800 miles.

In 1910, the federal government embarked on the Rio Grande Project, establishing an interstate irrigation system aimed at helping agriculture and industry in the states the river flows through. The project, which also upheld a 1906 treaty that promises Mexico 60,000 acre-feet of water annually, didn’t address a specific state-by-state water allocation. Historically, that ratio has meant 43 percent of the river’s water goes to Texas and 57 percent goes to New Mexico.

In 1929, Congress authorized Colorado, New Mexico and Texas to negotiate a temporary deal to determine how much water Texas — the most downstream state — was entitled to, and in 1938 that contract was permanently adopted as the Rio Grande Compact. The compact, however, didn’t explicitly say how much water was supposed to end up in Texas — the crux of the states’ disagreement.

Texas claims New Mexico is breaching the compact and using more water than it’s entitled to. New Mexico, meanwhile, maintains that the compact never required a set quantity of water to go to Texas, regardless of the historical allocation.

“New Mexico’s compact delivery obligation is to the Elephant Butte Reservoir in New Mexico and not to the New Mexico-Texas state line,” Gary King, the New Mexico attorney general, wrote in response to Texas’ complaint.

The federal government disagrees. In a brief filed in December, the solicitor general argued that New Mexico has an obligation to ensure that 43 percent of the Rio Grande’s flows reach Texas because this figure was already “frozen” by the time the compact went into effect.  

The federal government also believes it has a stake in the outcome because of its international duties to provide Rio Grande water to Mexico, as detailed in the 1906 treaty.

“The government would of course have a direct stake,” said Jeremy Brown, an energy research fellow at the University of Texas School of Law. “I’m not surprised that the court granted its motion for intervention.”

New Mexico has 30 days to file a motion for dismissal — which water rights experts say it mostly likely will — before the Supreme Court would hear the case.

Aside from the dispute over allocation, the lawsuit is complicated by the nature of the river and the irrigation systems. New Mexico’s water depletion is largely from groundwater (water tapped below ground) rather than surface water (water tapped from river flow). But the 1938 compact governing use of the Rio Grande does not differentiate between the two types of water.

Drought is also at the heart of the debate. Farmers in both states continue to struggle with dwindling water supplies. Even if Texas wins this legal battle, it’s still facing unpredictable and long-term challenges.  

“The outcome of this litigation could have a significant impact on the regional economy in the El Paso area, which in turn has a significant impact on the state’s economy as a whole,” TCEQ spokesman Terry Clawson said in a statement. “We also believe that farmers in the southern [New Mexico] water district ... will benefit.”

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