Arizona has officially joined Nevada in a lawsuit that challenges the federal government’s plan for drastic cuts to the Colorado River water share allocated to Lower Basin states. The Arizona Department of Water Resources and Arizona Gov. Katie Hobbs announced Friday that they filed a motion to intervene in the lawsuit. This legal action was originally initiated by the state of Nevada in August, disputing the U.S. Interior Department’s proposed mandatory water reductions for Nevada, Arizona, and California.
The federal government finalized a new operating plan for the Colorado River in August. This plan mandates Arizona, California, and Nevada to collectively reduce their water use by 1.25 million acre-feet in both 2027 and 2028. These required cuts are more than double the largest reductions imposed under the current guidelines, which are set to expire at the end of the current year. Under this new federal framework, the Upper Basin states—Colorado, New Mexico, Wyoming, and Utah—would not be subjected to mandatory water reductions.
Nevada Gov. Joe Lombardo welcomed Arizona’s decision to join the lawsuit, describing it as "an important step" in challenging a federal plan that he stated unfairly burdens the Lower Basin and fails to require meaningful reductions from the Upper Basin. Governor Lombardo affirmed in a statement that Nevada would not accept a framework that jeopardizes its water supply and the future of its communities.
Under the federal government’s proposed plan, Nevada faces a reduction of 50,000 acre-feet from its Colorado River allocation over the next two years. An acre-foot, which is a volume of water equal to 325,851 gallons, is enough to cover an acre of land one foot deep, or to supply two to three households for an entire year. Additionally, Arizona is slated for a reduction of 760,000 acre-feet in its water use, while California would need to cut approximately 440,000 acre-feet.
The potential for even more severe cuts exists if conditions worsen. Nevada, which already holds the smallest Colorado River water allocation among the three Lower Basin states, could see its 300,000 acre-foot entitlement cut by over 213,000 acre-feet, representing about 71% of its total allocation.
Governor Hobbs characterized the proposed cuts as “draconian” in a statement. She conveyed Arizona’s firm stance, stating that the state would not accept a forced federal plan that seeks to resolve the water crisis on the burden of its families, farmers, and businesses. Nevada’s initial lawsuit was filed in August, three days after the Trump administration released its 10-year plan for managing the Colorado River and the nation’s two largest reservoirs, Lake Powell and Lake Mead. This plan was introduced amidst ongoing drought conditions and record-low water storage levels.
Tom Buschatzke, director of the Arizona Department of Water Resources, emphasized that Arizona’s intervention in the Nevada lawsuit is crucial at this time. He stated it is necessary for the state to protect its legal rights to Colorado River water, while simultaneously maintaining a path toward a collaborative outcome with California and Nevada to ensure the protection of the entire Colorado River system.
Echoing similar concerns, John Entsminger, general manager of the Southern Nevada Water Authority, indicated that both Nevada and Arizona recognize significant flaws in the federal government’s Environmental Impact Statement. He also noted concerns regarding the National Environmental Policy Act process used to develop the framework for post-2026 Colorado River operations. Lower Basin states have consistently argued that Upper Basin states should be required to share in mandatory water cuts to prevent downstream states from enduring even steeper reductions. Conversely, Upper Basin states contend they lack the necessary infrastructure to store water during dry years, unlike their Lower Basin counterparts, and are already restricted by their available water supply each year.
