By Martha Pskowski, Inside Climate News, The Texas Tribune.

EL PASO—The Rio Grande flows over 1,800 miles from the mountains of southwestern Colorado to the Gulf of Mexico. A lawsuit filed in 2013 between Texas and New Mexico over Rio Grande water has taken as many twists and turns as the river itself.

A settlement signed this week by New Mexico, the Department of Justice and two irrigation districts, and reviewed by Inside Climate News, lays out agreements for irrigation management on the Rio Grande. It is one part of a larger settlement package that will be presented to a special master in the case, Judge D. Brooks Smith of the U.S. Third Circuit Court of Appeals, for approval next month.

The outcome of the case is expected to have broad implications for cities that rely on the Rio Grande and farmers throughout New Mexico and far west Texas.

The settlement package includes new formulas to calculate how much water each entity is owed; an agreement for New Mexico to reduce groundwater depletion, and changes to the operating manual for the Bureau of Reclamation’s Rio Grande Project.

Under the settlement, New Mexico could transfer water rights from the Elephant Butte Irrigation District (EBID) in Southern New Mexico in order to meet its obligations to Texas. The state agrees in the settlement that it would compensate EBID.

The case began when Texas alleged that groundwater pumping in Southern New Mexico deprives the state of water it is owed under the Rio Grande Compact. Colorado and the United States are also parties to the case. Local irrigation districts, cities and agricultural interest groups have been involved as friends of the court. The case has evolved from a dispute between Texas and New Mexico to encompass conflicts between groundwater and surface water users in the area.

“We are ecstatic to have reached a settlement and look forward to continue delivering water to our farmers and the City of El Paso,” said Jay Ornelas, general manager of the El Paso Water Improvement District No. 1, an irrigation district. “The agreement provides long-term protection to El Paso farmers and the City of El Paso that rely on water from the federal Rio Grande Project.”

A Strained Inter-State Compact

The Rio Grande Compact, signed in 1938, lays out how much water Colorado, New Mexico and Texas can use from the Rio Grande. The compact only addresses surface water in the river. But hydrologists now understand that aquifers and rivers are connected. Wells drilled into adjoining aquifers can reduce the flow of water into the Rio Grande.

At issue in the case is a 100-mile stretch of the river between Elephant Butte Reservoir in Southern New Mexico and the Texas-New Mexico state line. Water is released from the reservoir for both Southern New Mexico and far West Texas, including El Paso.

As agriculture expanded and severe droughts hit the region, farmers drilled more wells into the aquifer. Texas argues these wells in Southern New Mexico are siphoning off water that should flow to Texas.

“In one way it’s a conflict between the state of Texas and the state of New Mexico,” said Burke Griggs, a professor of water law at Washburn University in Topeka, Kansas. “But the conflict that really matters here is the conflict between surface water rights and groundwater pumping.”

Climate change is impacting snowmelt in the river’s headwaters. Extreme heat is increasing evaporation rates from the river where it flows downstream through the desert. The case is closely watched in New Mexico, where scientists predict that within 50 years water supply from rivers and aquifers will decline by 25 percent. The City of El Paso, which relies on Rio Grande water, has diversified its water sources as the river became less reliable.

The Supreme Court rejected a settlement that the states reached in 2022 because the federal government had not consented to its terms. The parties went back to the drawing board . A new settlement was announced on May 15, with the United States on board.

“The United States got what it needed in terms of firm commitments by New Mexico to reduce groundwater depletions,” Griggs said.

In a statement, the El Paso Water Improvement District No. 1 said that the settlement will improve efficiency, conserve scarce water resources and ensure that water is available for the district’s farmers and the City of El Paso. EBID has also signed on to the settlement.

Judge Smith, the special master, has called the parties to appear in court in Philadelphia on September 30 to explain the agreements. The details of the other parts of the settlement package have not been made public. As surface water dwindles across the Southwest, the settlement could bring to an end years of uncertainty surrounding the Rio Grande.

“We’ll know with this settlement, I think with much greater precision, how much water there is to be used, how much water people are going to be able to pump a year or two out,” Nat Chakeres, general counsel for New Mexico’s Office of the State Engineer, told lawmakers in Santa Fe earlier this month.

While Texas v. New Mexico may soon come to a close, water challenges in the desert Southwest are becoming ever more urgent. The settlement comes as Elephant Butte reservoir is at less than four percent capacity, nearly a record low, and the Rio Grande south of Albuquerque has run dry for over a month.

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