The Colorado River is delivering less water to Phoenix and Las Vegas this year, and the reductions could get substantially worse. In its annual operating plan, the U.S. Bureau of Reclamation declared a Level 1 shortage for Lake Mead for the 2026 water year, triggering mandatory cuts of 512,000 acre-feet to Arizona, 21,000 acre-feet to Nevada, and 80,000 acre-feet to Mexico under separate binational agreements. Those reductions are already being built into utility planning across the region.
But the bigger fight is over what comes next. The legal framework that governs how shortage pain is divided among Western states, the 2007 Interim Guidelines and the 2019 Drought Contingency Plan, expired at the end of 2025. Federal officials are now evaluating five alternatives for post-2026 river operations through a Draft Environmental Impact Statement, and some of those options would impose cuts far deeper than anything the Lower Basin has absorbed so far.
What the 2026 shortage means right now
Under the current shortage declaration, Arizona takes the largest hit. Nearly all of the state’s 512,000 acre-foot reduction falls on the Central Arizona Project canal, the 336-mile aqueduct that carries Colorado River water uphill to the Phoenix metropolitan area and Tucson. CAP water is a critical supply source for roughly five million people in central Arizona, and the cuts reduce deliveries that cities, farms, and tribes had counted on for the year.
Nevada’s 21,000 acre-foot reduction is smaller in absolute terms, but it lands on a state with a far thinner margin. Nevada’s entire Colorado River allocation is just 300,000 acre-feet per year, the smallest of any Lower Basin state. The Southern Nevada Water Authority, which supplies Las Vegas and surrounding communities, draws about 90 percent of its water from Lake Mead.
Las Vegas has a significant buffer that Phoenix does not: the city’s aggressive water recycling program returns nearly every gallon used indoors back to Lake Mead, where it is re-credited to Nevada’s account. That system effectively stretches the state’s allocation well beyond its paper entitlement. Phoenix, by contrast, relies more heavily on a mix of Colorado River water, Salt River Project deliveries, and groundwater, and the CAP cuts directly reduce one of those three legs.
The post-2026 stakes
The expiration of the old rules has opened a high-pressure negotiation among Arizona, Nevada, California, the federal government, tribal nations, and Mexico. Reclamation’s Draft EIS lays out five possible paths forward, ranging from a No Action scenario that would essentially extend the expired guidelines to action alternatives that propose new combinations of coordinated cuts, reservoir management changes, and conservation commitments.
Phoenix officials have been among the most vocal critics of some federal proposals. In an official statement, Phoenix-area mayors warned that certain alternatives could slash CAP deliveries so deeply that municipal water planning would be destabilized. The statement framed the potential reductions as a direct threat to household water service and called on federal negotiators to protect cities that have already invested heavily in conservation and alternative supplies.
Tom Buschatzke, director of the Arizona Department of Water Resources, has said publicly that Arizona is committed to reaching a consensus agreement with its Lower Basin partners before the federal government finalizes new rules. “Arizona has been at the table from the beginning, and we intend to stay there,” Buschatzke stated in an agency release, while noting that the state, along with Nevada and California, has each submitted proposed reduction percentages as part of the negotiations. But the three states have not yet converged on a single framework, and the gap between their positions remains wide enough that a consensus deal before a final EIS is published is far from guaranteed.
Lake Mead’s trajectory
Everything hinges on the reservoir. Lake Mead’s surface elevation determines which shortage tier is triggered, and the lake has spent years hovering dangerously close to the thresholds that would escalate cuts. The Level 1 shortage now in effect kicks in when the reservoir’s projected January elevation falls below 1,075 feet. A Level 2 shortage, which would bring steeper reductions, is triggered below 1,050 feet. Dead pool, the point at which water can no longer flow through Hoover Dam, sits at 895 feet.
Reclamation’s 24-Month Study, the primary modeling tool used to set operating conditions, projects reservoir elevations based on the most probable inflow forecasts from the National Weather Service’s Colorado Basin River Forecast Center. Those projections are useful for near-term planning but represent a single expected scenario, not the full range of possible outcomes. The Draft EIS models a broader set of hydrologic conditions, including less favorable sequences, to stress-test each of the five alternatives.
A strong snowpack season in the Upper Basin can temporarily stabilize or even raise Lake Mead’s level, as happened in 2023 and 2024. But long-term trends driven by rising temperatures and aridification across the basin have reduced average flows by roughly 20 percent compared to the 20th-century average, according to peer-reviewed research published in the journal Science. That structural decline means even good water years may not be enough to keep the reservoir above shortage thresholds over time.
What Mexico’s role means for U.S. cities
Mexico’s 80,000 acre-foot reduction is governed by binational agreements, specifically Minutes 319 and 323 to the 1944 U.S.-Mexico Water Treaty, rather than by the domestic shortage framework that applies to Arizona and Nevada. Those agreements allow Mexico to defer deliveries in dry years and recover them in wet years, creating a flexible but separate track from the state-by-state cuts within the United States.
The post-2026 alternatives in the Draft EIS do not yet spell out how future binational coordination will be structured. That matters for Phoenix and Las Vegas because Mexico’s share of the river is part of the overall system balance. If binational terms shift, the amount of shortage risk borne by U.S. states could increase or decrease accordingly. Negotiators on both sides of the border are aware of the linkage, but detailed proposals have not been made public as of May 2026.
Signals to watch as federal rules take shape
For residents in Phoenix and Las Vegas, the distinction that matters most is between what is locked in and what is still being negotiated. The 2026 Level 1 shortage and its associated delivery cuts are confirmed. Municipal utilities are already adjusting supply plans around those numbers. The deeper reductions described in some of the Draft EIS alternatives remain hypothetical until a final post-2026 operating plan is adopted by the Secretary of the Interior.
Three signals will indicate where this is heading. First, any updates to Reclamation’s reservoir modeling that incorporate new snowpack data or revised inflow forecasts will clarify whether Lake Mead is tracking toward improvement or toward a Level 2 shortage declaration. Second, public statements from Arizona, Nevada, and California that move beyond general principles to specific, agreed-upon reduction percentages will show whether a consensus framework is forming. Third, the release of a final Environmental Impact Statement, expected later in 2026, will reveal which alternative federal officials prefer and how they propose to divide the costs of a shrinking river among states, tribes, and Mexico.
The Colorado River has been over-allocated for decades, and the reckoning is no longer theoretical. For the millions of people in Phoenix and Las Vegas who turn on a tap every morning, the question is no longer whether cuts are coming but how deep they will go and who will bear the heaviest burden.
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*This article was researched with the help of AI, with human editors creating the final content.
