Arizona has joined Nevada in a lawsuit challenging the federal government’s plan to implement significant cuts to the Lower Basin states’ allocation of Colorado River water. The Arizona Department of Water Resources and Arizona Gov. Katie Hobbs announced Friday they had filed a motion to intervene in a lawsuit originally initiated by the state of Nevada in August. This legal action targets the U.S. Interior Department’s framework, which proposes mandatory water reductions for Nevada, Arizona, and California.
The federal government finalized its new operating plan for the Colorado River in August, mandating a reduction of 1.25 million acre-feet in water use from Arizona, California, and Nevada for both 2027 and 2028. This figure represents more than double the largest reductions required under the current guidelines, which are set to expire at the end of the year. Notably, under this plan, the Upper Basin states—Colorado, New Mexico, Wyoming, and Utah—would not face mandatory water reductions.
Under the proposed federal framework, Nevada would be required to give up 50,000 acre-feet of its Colorado River allocation over the next two years. An acre-foot, equivalent to 325,851 gallons, is the amount of water needed to cover an acre of land a foot deep or typically enough to supply two to three households for a year. Arizona faces a substantial reduction of 760,000 acre-feet, while California would need to cut approximately 440,000 acre-feet from its water use.
Nevada Governor Joe Lombardo welcomed Arizona’s decision to join the lawsuit, describing it as a crucial step in disputing a federal plan that, in his view, unfairly burdens the Lower Basin and fails to require meaningful reductions from the Upper Basin. Governor Lombardo stated that Nevada would not accept a framework that jeopardizes its water supply and the future of its communities.
Similarly, Arizona Governor Katie Hobbs characterized the proposed cuts as "draconian." She asserted that Arizona would not accept a federally imposed plan that seeks to resolve the water crisis by burdening families, farmers, and businesses within the state. Governor Hobbs emphasized that Arizona is taking legal action alongside Nevada because the federal government, she contends, is not holding the Upper Basin accountable for water deliveries owed to Arizona.
Concerns about potential future reductions for Nevada were also highlighted. If conditions on the river system worsen, Nevada’s 300,000 acre-foot Colorado River entitlement could see cuts exceeding 213,000 acre-feet, which amounts to about 71% of its total allocation. Nevada already holds the smallest allocation of Colorado River water among the three Lower Basin states.
Statements from water resource officials further underscored the basis of the legal challenge. Tom Buschatzke, director of the Arizona Department of Water Resources, affirmed that intervening in the Nevada lawsuit is essential for Arizona to safeguard its legal rights to Colorado River water. He also indicated that this action aims to preserve a path toward achieving a collaborative resolution with California and Nevada to protect the overall Colorado River system. John Entsminger, general manager of the Southern Nevada Water Authority, echoed criticisms, noting that Arizona, like Nevada, identifies significant flaws in the federal government’s Environmental Impact Statement and the National Environmental Policy Act process utilized to develop the post-2026 Colorado River operations framework.
The original lawsuit by Nevada was filed three days after the Trump administration unveiled its 10-year plan for managing the Colorado River and the nation's two largest reservoirs, Lake Powell and Lake Mead. This broader context includes ongoing drought conditions and record low water storage levels across the basin.
A central point of contention between the two regions revolves around responsibility for cuts. Lower Basin states have consistently argued that the Upper Basin should also be required to implement mandatory water reductions to prevent downstream states from having to make even steeper cuts. Conversely, Upper Basin states contend they lack the necessary infrastructure to store water during dry years, unlike the Lower Basin states, and maintain that they are already restricted by their available supply annually.
