The dispute between Texas and New Mexico over the water rights of the Rio Grande has reached a new level of intensity after the U.S. Supreme Court ruled in June that the federal government must play a central role in any settlement between the two states.
With the Court's decision effectively nullifying a proposed agreement between Texas and New Mexico, both sides must return to the negotiating table under federal oversight by December 16, marking a major shift in a case that could reshape water management in the arid Southwest.
The fight began in 2013 when Texas filed a lawsuit against New Mexico, alleging that groundwater pumping in New Mexico was depleting the flow of the Rio Grande and diverting water allocated to Texas under the Rio Grande Compact, an agreement signed in 1938.
After nearly a decade of costly litigation, Texas, New Mexico, and Colorado, which had become party to the suit, proposed a settlement in 2022, only for the federal government to oppose the deal, citing concerns over its treaty obligations with Mexico and the Bureau of Reclamation's role in managing the river.
In a 5-4 decision in June, the Supreme Court ruled that the federal government's approval is required for any agreement.
The ruling has forced the states to reengage with federal authorities, sparking a renewed round of mediation set for December in Washington, D.C.
"We cannot now allow Texas and New Mexico to leave the United States up the river without a paddle," Justice Ketanji Brown Jackson wrote for the majority.
This decision has set a new legal precedent, raising questions about the extent of federal intervention in inter-state water disputes.
The case highlights the growing friction between states' rights and federal oversight, especially as water scarcity becomes a critical issue across the West.
Water law expert and Washburn University professor Burke Griggs told Inside Climate News (ICN) that "States that settle water disputes are now going to think twice," noting the Supreme Court's unexpected power to block settlements crafted by the states involved.
In this case, Texas and New Mexico's tug-of-war over water rights is complicated by the region's dwindling water supplies and the increasing impacts of climate change.
Since the Compact was signed, groundwater pumping has become a critical resource for New Mexico farmers and cities as surface water has become scarcer.
But hydrologists now understand that extensive groundwater pumping can reduce stream flow, compounding the strain on water resources.
Scientists have warned that climate change is reducing snowmelt in Colorado, which feeds the Rio Grande, and increasing evaporation from Elephant Butte Reservoir, an essential water storage site in New Mexico.
"Whatever agreement is arrived at needs to have provisions for how it's going to be implemented in the case of a steadily declining water supply," Fred Phillips, emeritus professor of hydrology and environmental science at New Mexico Tech in Socorro, told ICN.
Recent studies predict that New Mexico will face a 25 percent reduction in water availability in rivers and aquifers over the next 50 years, and a 2022 paper projected a 10 percent decline in water released from Elephant Butte over the coming decades.
As the case heads toward a potential trial in 2025, a settlement remains preferable, according to Griggs.
He argued that skilled lawyers with expertise in water law are better suited to negotiate complex agreements than justices from outside the drought-ridden West.
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