Nevada has filed a lawsuit against the U.S. federal government to contest proposed reductions in its share of Colorado River water, initiating the first major legal dispute over the Southwest’s declining water supply.
The state has petitioned the U.S. District Court in Nevada to halt the Bureau of Reclamation’s plans that would significantly cut water allocations for Nevada, California, and Arizona over the next decade if the river basin continues to experience severe drought.
Nevada argues the federal plans inequitably burden the three lower basin states while bypassing mandatory restrictions on four upstream states—Wyoming, Colorado, Utah, and New Mexico. The lawsuit claims violations of the “law of the river,” complex legal frameworks governing water rights, as well as federal administrative procedure and environmental laws.
Notably, Nevada did not name upstream states as co-defendants, avoiding a high-risk litigation strategy that could escalate to the U.S. Supreme Court with unpredictable outcomes.
Discussions among the seven Colorado River basin states regarding long-term water allocation have stalled, though lower basin states have previously agreed to temporary water-use restrictions for the next two years.
“The Department of the Interior cannot unilaterally address the Colorado River shortage by shifting the burden to lower basin states,” said Nevada Governor Joe Lombardo, a Republican. “We have demonstrated willingness to cooperate, but a sustainable solution requires collective action. Until then, Nevada is ready to pursue legal action if necessary.”
Interior Department officials have refrained from commenting on the lawsuit.
The state’s complaint targets a long-term federal plan issued in April, which could reduce Nevada’s river allocation by up to 70% from 2029 to 2036. Despite Nevada implementing 40% water-use reductions—the smallest proportional cut among basin states—the federal proposal remains contentious as its population continues growing.
Arizona officials have also signaled intent to challenge the federal plan through litigation.
Environmental law professor Mark Squillace of the University of Colorado noted the lawsuit lacks the legal complexity often feared in Colorado River disputes. Decades of drought have reduced the river’s natural flow well below entitlement levels allocated to seven basin states and Mexico.
“The greatest litigation risk lies in interstate lawsuits,” Squillace explained.
