Arizona has joined Nevada in pursuing legal action against the Trump administration’s recent proposal to reduce their allocated shares of Colorado River water. The Department of the Interior’s announcement this summer outlined restrictions that could significantly cut water deliveries to the three lower basin states—Arizona, California, and Nevada—over the coming two years, depending on the condition of the river.
The Colorado River’s two main reservoirs, Lake Mead and Lake Powell, have fallen to historically low levels amid prolonged drought, increased demand, and the impacts of climate change. The states that rely on the river have long been divided over how to address shrinking supplies. The upper basin states—Wyoming, Colorado, Utah, and New Mexico—maintain that lower basin users have overconsumed water, leading to reservoir shortages, and argue that they should bear the brunt of any cuts. Conversely, lower basin states contend that upper basin states have not fulfilled their delivery obligations.
Federal authorities stepped in after the states repeatedly missed deadlines to reach a voluntary agreement on water reductions. The Department of the Interior’s plan exempts the upper basin states from any mandatory cuts, a decision that lower basin officials say is unjust and threatens their water security.
“This is a line in the sand,” Arizona Governor Katie Hobbs said in a statement issued on Friday. Hobbs emphasized that Arizona’s legal challenge, joined with Nevada, aims to hold the upper basin accountable for water deliveries while opposing what she described as “draconian cuts” that exceed the terms of the Lower Basin Drought Contingency Plan—a voluntary conservation agreement between Arizona, California, and Nevada.
Tom Buschatzke, director of Arizona’s Department of Water Resources, underscored the necessity of the legal response. He noted that the intervention in Nevada’s lawsuit is critical for safeguarding Arizona’s legal rights to Colorado River water and maintaining prospects for a collaborative resolution with California and Nevada to manage the river sustainably.
An official from the Department of the Interior did not immediately comment on the joint lawsuit when contacted.
The legal dispute highlights the ongoing tensions among Colorado River basin states over diminishing water supplies and the federal government’s role in apportioning scarce resources amid persistent drought and changing environmental conditions.