Nevada officials have filed a federal lawsuit challenging the U.S. Department of the Interior’s recently issued Record of Decision governing Colorado River operations, arguing that the plan places disproportionate reductions on Lower Basin states while requiring no mandatory cuts from the Upper Basin states.

Under the plan, Nevada’s 300,000-acre-foot Colorado River allocation could be reduced by as much as 213,556 acre-feet, leaving Southern Nevada with less than 86,500 acre-feet annually. The Southern Nevada Water Authority said that amount is insufficient to meet the region’s basic water needs. Southern Nevada used slightly less than 212,500 acre-feet in 2024.

Nevada officials argue the plan also fails to adequately assess the economic consequences of the proposed reductions on Southern Nevada, whose economy is valued at approximately $180 billion. The lawsuit seeks to set aside the Record of Decision and prevent its implementation while legal and technical issues are addressed.

SNWA General Manager John Entsminger said Southern Nevada has reduced its Colorado River consumption by about 40% over the past 25 years despite adding more than 800,000 residents.

The lawsuit adds another layer of uncertainty to ongoing efforts to establish long-term operating rules for the Colorado River, which supplies water to seven Western states and Mexico. A preliminary hearing date has not yet been set.