An 8-year-old Supreme Court lawsuit about a dispute over groundwater pumping on the Rio Grande between Texas and New Mexico is making its way to trial.

Texas alleges in the lawsuit that New Mexico farmers’ pumping of groundwater has reduced Texas’ water supplies by millions of gallons each year. Texas is asking for damages from New Mexico for water used over decades. If the court decides in Texas’ favor, that could mean paying more than a billion dollars in damages, on top of the $15 million it spent on legal fees.

This isn’t the first water dispute between the states, however, and decisions by the United States Supreme Court more than three decades ago could shed light on the current battle’s outcome.  

Animosity between New Mexico and Texas over water stretches back before 1974, over a fight in the U.S. Supreme Court about the 1948 Pecos River Compact. Texas sued, alleging that upstream New Mexico chronically shorted Texas at the state line and used too much water. 

The Supreme Court delivered landmark decisions in 1983 and 1987 that reshaped the legal landscape over  penalties for non-compliance and the framework for ending disputes over water. Those decisions  could directly impact how the court might handle the current Rio Grande fight.

The Pecos case sheds some light on how the Supreme Court sees its role in the current Rio Grande case and other major water disputes, said Reed Benson, a law professor at the University of New Mexico.

Benson covered the Pecos case for SCOTUSblog during its latest development in October 2020. It was a disagreement over evaporation losses in a one-time event in 2014 and 2015 that won’t have much impact beyond the Pecos Basin.

Instead, he said, the historical decisions earlier in the dispute are the keys to understanding the consequences of states’ high-stakes lawsuits over water. 

A history of Texas v. New Mexico

The headwaters of the Pecos start in the Sangre de Cristo mountains in north-central New Mexico, flowing across West Texas, before emptying into the Rio Grande near the Amistad Reservoir, 400 miles southeast of El Paso. The Pecos River follows a 900-mile course.

The two states agreed in 1949 to split the water at the Texas state line at the border between Loving and Reeves counties.

The compact established the Pecos River Commission to ensure the terms of the document were met. But the compact only allowed for two commissioners – one from each state – which meant deadlocked votes in disputes. 

Tensions boiled over in 1974, when Texas sued New Mexico in the Supreme Court over groundwater pumping and other activities that Texas argued depleted flows of the Pecos River.

While the problem sounds simple, Benson cautioned that the water dispute itself includes several technical issues.

“The compact was written in a way that made New Mexico’s duty very unclear. Then there was a major technical undertaking to determine how to quantify New Mexico’s obligation and determine the extent the state fell short,” Benson said. “It ended up being a very complex case over the seemingly simple question of whether New Mexico sent enough water to Texas every year.”

After a decade of litigation, the Supreme Court found in 1983 that New Mexico violated the compact and delivered less water to Texas than what was required. The court issued a remedy for past noncompliance, paid in water or money. That penalty set the precedent that New Mexico – and other states in water fights – are required to comply with compacts, and can face penalties for not doing so.

“If an upstream state hasn’t met its obligations under the compact, the Supreme Court determined it has a full array of powers and discretion to order a remedy,” Benson said.

Those powers are limited by one measure – the court said its own solution can’t violate the terms states agreed to in the compact. For example, a compromise floated in the Pecos lawsuit was to ask the court to appoint a tie-breaking third vote on the Pecos River Commission. The court declined, citing the compact’s limits on voting members.

Instead, the Supreme Court ordered New Mexico to provide an additional 10,000 acre feet annually to Texas, and would appoint a “river master” to determine if New Mexico met its obligations. (An acre-foot of water is about 325,850 gallons.). It also set up a new formula to determine how much water would make its way downstream to Texas, which would be evaluated at a later time.

The ruling was finalized in 1987, where the Supreme Court laid out the duties and responsibilities for the river master’s position, only the second one in the nation. The other river master is in Delaware.

The court has denied other states’ requests for river masters in different water disputes.

 “They’re not real eager to set up these arrangements where somebody like the Pecos River master is going to make a decision, and the only way that can get reviewed is if the Supreme Court does it. That’s a pretty messed up structure,” Benson said.

Texas claimed damages over $100 million, and New Mexico settled for $14 million for past noncompliance.

However, the state spent more than $100 million in buying water rights, drilling different wells, all to make sure it could make the extra 10,000 acre-foot delivery to Texas.

“Going forward, the upstream state can’t keep under-delivering and paying, they’ve got to actually come into compliance,” Benson said. “That, in the end, is where New Mexico spent all the money: figuring out how to deliver an extra 10,000 acre feet on average, every year to Texas on the Pecos.”

Benson said the high profile of the Supreme Court’s involvement in these water cases can be a detriment to settlements, or other solutions compared to expensive, drawn-out litigation.

“The stakes are really high for these disputes,” Benson said. “It can make for some political grandstanding. In other words, sometimes these cases should settle (out of court) and they don’t.”

Cover illustration by Danielle Prokop/El Paso Matters