Arizona announced its intention Friday to join a lawsuit filed by Nevada challenging the federal government's most recent operating framework for the Colorado River. This action follows years of unsuccessful negotiations among the seven states that rely on the river for water, aiming to address decreasing water availability amidst a 25-year mega-drought.
Arizona Department of Water Resources Director Tom Buschatzke stated during a press conference that the federal government’s new plan ignores the basic elements of the law of the river and could result in cuts to the state apportionment that would "devastate Arizona’s economy."
The federal framework, revealed in August by the Trump administration, proposes substantial reductions in Colorado River water for the Lower Basin states of Arizona, California, and Nevada. These states would also engage in voluntary conservation to temporarily prevent more severe cuts initially suggested by the federal government. Under this framework, the Lower Basin states are mandated to collectively reduce their water usage by 1.25 million acre-feet in both 2027 and 2028. This represents more than double the largest reductions required under the current guidelines, which are set to expire at the end of the year. Arizona is slated to bear the largest portion of these cuts, with annual reductions of 760,000 acre-feet. California faces reductions of 440,000 acre-feet per year, and Nevada 50,000 acre-feet annually. An acre-foot of water is equivalent to covering an acre of land one foot deep, roughly 325,851 gallons, which is enough to supply three homes in Arizona for a year on average.
A key point of contention for the Lower Basin states is that the Upper Basin states—Colorado, New Mexico, Utah, and Wyoming—do not currently face and are not prescribed any government-mandated cuts under the new federal plan. Colorado’s water commissioner, Becky Mitchell, maintained that her state already contends with mandatory cuts, attributing them to natural factors rather than federal directives, noting record low snowpack in the Rocky Mountains, which feeds the Colorado River. Conversely, the Lower Basin states, after decades of reducing their water use, have consistently argued that the Upper Basin states must agree to government-mandated reductions in dry years.
In addition to the mandated cuts, the Lower Basin states have committed to conserving an extra 700,000 acre-feet of water through 2028. An agreement on this additional conservation is still being finalized and requires approval from each state’s legislature.
The federal plan also stipulates that the Lower Basin and Upper Basin states would need to negotiate new terms every two years for a decade, following the expiration of the initial two-year plan covering 2027 and 2028. Some of the potential cut options outlined for this 10-year period could be significantly detrimental to Arizona. Buschatzke warned that such reductions could effectively dry up the Central Arizona Project, as well as many of our on-river communities, and would more than double the water cuts agreed to in the Lower Basin Agreement. The Central Arizona Project is a vital system, delivering Colorado River water to cities, tribes, and farms across Maricopa, Pinal, and Pima counties, home to nearly 6 million people. It serves as the primary water source for communities like Tucson.
Nevada initiated its lawsuit challenging the federal plan shortly after its announcement in August, despite Arizona initially commending the federal government’s temporary avoidance of more extreme cuts it had proposed earlier in the year. Nevada Governor Joe Lombardo characterized challenging the federal plan as a matter of survival for Southern Nevada. The lawsuit seeks an injunction to halt the plan's implementation, alleging violations of the Administrative Procedure Act, the National Environmental Policy Act, and the Law of the River. Nevada officials stated in their complaint that the federal government failed to consider a reasonable range of alternative plans, did not adequately assess the environmental and socioeconomic impacts, and failed to respond to Nevada’s comments.
Arizona’s attorneys, in their Friday motion to intervene, asserted that the challenged actions would have direct and potentially catastrophic effects on Arizona. They further stated that the outcome would determine Arizona’s water allocation over the next decade and affect its rights and obligations within the Colorado River Basin. As a party to the 1922 Compact and the Lower Basin state facing the largest share of cuts in the coming two years, Arizona believes it has a right to be heard.
Buschatzke also informed reporters that Arizona had not dismissed the possibility of filing its own lawsuit against the federal government if the terms of the 1922 Colorado River Compact are breached. The 1922 Compact allocated 7.5 million acre-feet to each basin, obligating the federal government to deliver that amount to the Lower Basin. Buschatzke emphasized that Arizona believes the federal government is obligated to operate the Colorado River system in compliance with the compact's terms, including the volume of water designated to flow from the Upper Basin to the Lower Basin. However, Colorado water officials disagree, contending the compact was based on a flawed model that overestimated the river system's annual supply at 15 million acre-feet.
The cuts and conservation efforts in the Lower Basin are primarily aimed at stabilizing water levels in Lake Powell and Lake Mead, the Colorado River system's two primary reservoirs. These reservoirs saw their water levels drop in July to their lowest point since 1957. Brad Udall, a water and climate scientist at Colorado State University, noted in an August 19 PBS special that both reservoirs were just above deadpool, a critical level where water becomes too low to flow past a dam by gravity. Reaching this point would render the reservoirs ineffective, turning them into basins where water merely evaporates.
Despite the legal actions, all states involved have expressed a preference for resolving the water agreement outside of court. Nevertheless, Buschatzke stressed the importance of Arizona participating in the Nevada case, stating, "We have to have a seat at that table to be able to give Arizona’s viewpoints."
