The Arizona Department of Water Resources has officially filed a motion to join a high-stakes lawsuit against the United States federal government, challenging a ten-year operational framework for the Colorado River that state officials claim unfairly penalizes Arizona while threatening its economic stability. By intervening in the litigation originally spearheaded by Nevada, Arizona is escalating a regional conflict over the dwindling water resources of one of the most critical river systems in the Western United States. The legal action targets the Department of the Interior and the Bureau of Reclamation, alleging that the federal government’s proposed management plan for 2027 through 2037 violates established legal precedents and places an asymmetrical burden of water conservation on the Lower Basin states of Arizona, California, and Nevada.
Tom Buschatzke, Director of the Arizona Department of Water Resources, announced the motion during a press conference, emphasizing that the federal government’s new operating framework overlooks fundamental components of the "Law of the River." Buschatzke warned that the proposed mandatory cuts to Arizona’s water apportionment could result in catastrophic consequences for the state’s multi-billion-dollar economy. The move signals a breakdown in the collaborative spirit that has historically governed the seven-state basin, as the Lower Basin states now move to legally compel the federal government to hold the Upper Basin states—Colorado, Wyoming, Utah, and New Mexico—accountable for shared sacrifices.
Historical Context and the Law of the River
The Colorado River is managed under a complex web of interstate compacts, federal laws, court decrees, and international treaties collectively known as the "Law of the River." The foundational document, the Colorado River Compact of 1922, divided the river into two basins: the Upper Basin and the Lower Basin, with Lee Ferry, Arizona, serving as the dividing point. At the time of the compact’s signing, negotiators estimated the river’s annual flow at roughly 17.5 million acre-feet. However, tree-ring data and modern hydrological modeling have since revealed that the 1920s were an atypically wet period. The historical average natural flow is now understood to be closer to 14.7 million acre-feet, and that figure has plummeted further in the 21st century due to a persistent "mega-drought" exacerbated by climate change.
Between 2020 and 2024, provisional data from the Bureau of Reclamation indicates that the river’s natural flow averaged only 11.2 million acre-feet. Despite this shrinking supply, the legal allocations established a century ago remain on the books, creating a "structural deficit" where more water is legally promised than physically exists. Arizona, which holds some of the most junior water rights among the Lower Basin states, is particularly vulnerable. Under the 1968 Colorado River Basin Project Act, Arizona agreed to a junior status for its Central Arizona Project (CAP) water in exchange for federal funding to build the 336-mile canal system. This means that in times of shortage, Arizona is required to take substantial cuts before California loses a single drop.
The Timeline of the Current Crisis
The current legal battle is the culmination of years of failed negotiations and temporary fixes. In 2007, the basin states agreed to "Interim Guidelines" to manage Lake Mead and Lake Powell during shortages. As the drought intensified, the states signed the 2019 Drought Contingency Plan (DCP), which required additional voluntary cuts. However, as reservoir levels dropped to historic lows in 2022 and 2023, the federal government warned that the existing agreements were insufficient to prevent the "dead pool" status of the river’s major dams, which would halt hydropower production and water deliveries.
In July 2024, the Bureau of Reclamation issued its Record of Decision for the post-2026 operations of the Glen Canyon and Hoover Dams. This 10-year plan, scheduled to begin in 2027, was intended to provide a stable framework for a drier future. However, the plan focused almost exclusively on mandatory reductions for the Lower Basin. While the first two years of the plan incorporate a proposal submitted by Arizona, California, and Nevada—reducing their collective usage by roughly 1.25 million acre-feet—the long-term framework allows for future cuts of up to 3 million acre-feet. Arizona officials argue that the federal government is attempting to solve the river’s systemic deficit by targeting the Lower Basin while allowing the Upper Basin to continue its current usage patterns without mandatory federal intervention.
Arizona’s Legal and Economic Grievances
Governor Katie Hobbs has taken a firm stance against the federal framework, describing it as an attempt to solve a basin-wide crisis "on the backs of Arizona families, farmers, and businesses." The state’s primary concern is the preservation of the Central Arizona Project (CAP). The CAP delivers water to nearly 80% of Arizona’s population, including the Phoenix and Tucson metropolitan areas, and supports vast agricultural regions in Pinal, Maricopa, and Pima counties.
The lawsuit contends that the federal plan ignores the "equal protection" of the basins and fails to enforce the Upper Basin’s delivery obligations at Lee Ferry. Under the 1922 Compact, the Upper Basin is technically required to ensure that a minimum of 75 million acre-feet of water passes Lee Ferry over any ten-year period. Arizona argues that the Bureau of Reclamation is effectively allowing the Upper Basin to bypass these requirements, which in turn forces the Lower Basin to deplete its own reservoirs, Lake Mead and Lake Powell, to maintain system stability.
"Arizona has always been willing to do our part to protect the Colorado River," Governor Hobbs stated. "But we are drawing a line in the sand. The federal government refuses to hold the Upper Basin accountable for the water deliveries they owe Arizona and is threatening to force draconian cuts that go well beyond the Lower Basin Agreement."
Supporting Data and State Contributions
To support its claim of disproportionate sacrifice, Arizona points to its history of voluntary conservation. Since 2014, Arizona has left more than 5.5 million acre-feet of its water entitlement in Lake Mead to prop up reservoir levels and prevent the Bureau of Reclamation from declaring more severe shortage tiers. Under the current short-term agreement, Arizona is already absorbing a reduction of 760,000 acre-feet—nearly 27% of its total annual allocation. By comparison, California’s current reduction is 440,000 acre-feet, and Nevada’s is 50,000 acre-feet.
The economic stakes are significant. Arizona’s agricultural industry, which produces a large percentage of the nation’s winter leafy greens and high-quality alfalfa, relies heavily on Colorado River water. In Pinal County, many farmers have already seen their surface water deliveries cut to zero, forcing them to fallow land or return to groundwater pumping, which is strictly regulated under the state’s 1980 Groundwater Management Act.
Federal Response and Political Climate
The Department of the Interior has pushed back against the litigation, characterizing it as a political distraction from the physical realities of the river. A spokesperson for the Department stated that "litigation won’t create a single additional drop of water or change the hydrologic realities facing the Colorado River Basin." The federal government maintains that the current plan is the most viable path to prevent a total system collapse and that it remains committed to working in good faith with all seven states, 30 Tribal nations, and the Republic of Mexico.
The Trump administration, which oversees the current Bureau of Reclamation operations mentioned in the litigation, has emphasized that its goal is a long-term, sustainable solution. Federal officials argue that the Upper Basin states face different challenges, as their water supply is largely dependent on annual snowpack and lacks the massive storage capacity of the Lower Basin’s Lake Mead. The Upper Basin states have consistently argued that they cannot be forced to make the same types of cuts as the Lower Basin because they have never fully utilized their legal 7.5-million-acre-foot allocation.
Broader Implications for the West
The outcome of this lawsuit could redefine western water law for the next century. If Arizona and Nevada are successful, the federal government may be forced to reconsider how it allocates "system losses"—water that evaporates from reservoirs or seeps into the ground—which currently count against the Lower Basin’s total. Furthermore, a court ruling could compel the Upper Basin to participate in mandatory reductions, a move that would likely trigger counter-lawsuits from Colorado and Utah.
The conflict also highlights the growing importance of Tribal water rights. Thirty federally recognized Tribes in the Colorado River Basin hold rights to roughly 25% of the river’s flow, yet many lack the infrastructure to utilize their full allocations. As states fight over their shares, Tribal nations are increasingly demanding a seat at the table, asserting that any long-term management plan must respect their senior water rights.
As the legal proceedings move forward, the Colorado River remains in a state of precarious balance. While recent winters have provided some relief through above-average snowpack, scientists warn that "aridification"—a permanent shift to a drier climate—is the new baseline. The litigation between Arizona, Nevada, and the federal government underscores a harsh reality: the era of abundant water in the American Southwest has ended, and the legal battle to decide who loses the most has only just begun. For now, Arizona’s "line in the sand" serves as a signal that the state will no longer accept the status of being the first and most severely impacted by the river’s decline without a fight in the highest courts of the land.
