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The U.S. Supreme Court rejected a deal struck between Texas and New Mexico on Friday over the management of water in the Rio Grande, ruling the federal government should have a say in any agreement reached.

The 5-4 opinion is the latest twist in a conflict dating back to the 1930s, when Colorado, New Mexico and Texas agreed to share water in the Rio Grande.

Most recently in 2022, Texas and New Mexico sought an agreement that side-stepped the federal government. Federal regulators objected because it would impact an international water treaty with Mexico.

In the majority opinion, the court said “we cannot now allow Texas and New Mexico to leave the United States up the river without a paddle.”

The ruling comes as Texas and other states clamor for water. The region along the Rio Grande, in particular, is still considered in a drought.

Water “is never an issue until there isn't enough. When there isn't enough, suddenly everybody starts to look at the various agreements that share this water source," said Amy Hardberger, a water law professor at Texas Tech School of Law, about the water conflicts.

The decades-long dispute centers around an 80 year-old water agreement, known as the Rio Grande Compact, which legally binds Colorado, New Mexico and Texas to share the water in the Rio Grande. The 1938 agreement ended years of water disputes between the three states and directed how the states should split surface water.

Under the compact, Colorado must deliver a proportion of water each year to New Mexico at the state line and New Mexico must deliver a certain amount of water to the Elephant Butte Reservoir, located in southern New Mexico, for Texas.

In a 2013 complaint, Texas sued New Mexico, alleging groundwater pumping by New Mexico was taking water from the Rio Grande owed to Texas, causing river levels in the state to drop and depriving Texans of the water they're obligated to.

Texas accused New Mexico of violating the interstate compact that has governed water allocations between the two states and Colorado for decades.

Water law experts say the Supreme Court's recent decision has significant implications for future interstate water disputes, which would allow the federal government to intervene in water conflicts between states moving forward.

Texas and New Mexico came up with a compromise that allowed for a higher number of water pumping from New Mexico than the original 1938 agreement stated, but not big enough to run Texas dry.

The U.S. Bureau of Reclamation, which is also responsible for delivering water to Texas and New Mexico, did not agree with their allocations and requested intervention because that same water, in the Rio Grande, impacted the international 1906 water treaty that requires the U.S. to deliver 60,000 acre-feet of water from the Elephant Butte Reservoir to Mexico. The federal government argues it cannot meet its obligation if New Mexico does not comply with their obligations.

“You’ve got all these competing responsibilities here that have never been put together in one agreement,” said Gabriel Eckstein, a legal expert on water issues at Texas A&M University. “It’s a number of different projects and agreements that now have to work together so this is why the U.S. government thought to intervene in the dispute.”

The U.S. Supreme Court decided that the U.S. needs to be in agreement with Texas and New Mexico.

The U.S. Bureau of Reclamation and the International Boundary and Water Commission, which oversees the international treaty, both declined to comment on the ruling. A spokesperson for the Texas Commission on Environmental Quality said the agency does not comment on pending litigation.

Gage Zobell, a water law expert and attorney with Dorsey & Whitney said today’s decision will allow for the potential increase of federal involvement in water management.

“This has turned that long held principle on its head,” Zobell said. “What we have here is Supreme Court precedent that states that there are federal interests that can actually be brought forward as claims when two states are fighting over water, and that the federal government has a seat at the table, and that has been unheard of.”

Hardberger, the water law professor at Texas Tech, said that the Texas, U.S. and New Mexico will need to go back to the drawing board to figure out how they are going to resolve this conflict. She said there's an opportunity to continue negotiating, but the court has made it clear that all parties have to be in agreement.

“There's definitely not enough water in South Texas and Southwest Texas. I think everyone knows that,” Alex Ortiz, the volunteer Water Reservoir Chair for the Lone Star Chapter of the Sierra Club, adding the ruling doesn’t mean there will be more water or less water available. “It means that it's possible that there's more water than what the consent decree would have allowed for but it's up to the United States now."

The water disputes come at a time when South Texas battles severe drought conditions, tremendous water shortage issues impacting farmers, and there were these impending conflicts between the U.S. and Mexico about how that water is being shared.

While the water in dispute is not directly related to water deliveries in South Texas, one environmentalist group argues there are downstream effects.

“If there's not enough water coming into the state as a whole, that puts more pressure on the upper part of the Rio Grande,” Ortiz said. “It changes a little bit of the management strategies for reservoirs that might already be struggling."

Disclosure: Texas A&M University and Young President's Organization - Lone Star Chapter have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.

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This article originally appeared in The Texas Tribune at https://www.texastribune.org/2024/06/21/supreme-court-rejects-texas-new-mexico-water-agreement/.

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