The United States federal government has proposed sweeping mandatory reductions in water use from the Colorado River for three western states — Arizona, California and Nevada — after years of failed negotiations left the 2,334-kilometre (1,450-mile) waterway at critically low levels. The proposal, released Friday by the US Bureau of Reclamation, would require the three Lower Basin states to collectively cut their water use by up to 3 million acre-feet annually through 2036 — roughly the combined allocation of Arizona and Nevada, and enough to serve more than 25 million people per year. The four Upper Basin states — Colorado, New Mexico, Utah and Wyoming — are spared mandatory reductions for now, though they may pursue voluntary agricultural cuts.

The urgency stems from a convergence of long-term drought, climate change and structural overuse that has left the river delivering roughly 20 percent less water than originally envisioned. The Colorado River Compact of 1922, which divided the river between the Upper and Lower Basins and guaranteed each 7.5 million acre-feet, was signed during an unusually wet period that proved unrepresentative of the river's long-term flows. Today, Lake Mead and Lake Powell — the two largest human-made reservoirs in the United States, created by the Hoover and Glen Canyon Dams respectively — are at their lowest combined levels since they began filling, approaching the point where they could no longer generate hydropower. A record-dry winter worsened an already dire situation. Because the seven affected states, several tribal nations and Mexico could not agree on a shared plan, the Bureau of Reclamation stepped in with what experts describe as an unprecedented federal intervention.

Reactions from the states have been largely critical, though for different reasons. Arizona, which holds the lowest-priority water rights in the Lower Basin, called the plan flawed, while its Department of Water Resources warned the cuts would devastate the state's water users and economy. Nevada's governor described the proposed reductions as unrealistic and devastating. California acknowledged the proposal as an important milestone while stopping short of endorsing it. The Upper Basin governors offered a cautiously positive initial assessment, welcoming guidelines that would better reflect actual river supply. A central point of contention has been the Lower Basin states' longstanding demand that all seven states share in specific, measurable reductions — a position the Upper Basin has consistently rejected as legally impermissible under existing compacts.

The practical consequences of the cuts could be far-reaching. Agriculture stands at the centre of the debate: approximately 75 percent of Colorado River water goes to farming, and producers in Southern California and Yuma, Arizona, grow the majority of North America's winter leafy greens. Experts warn that cuts could mean fields left unplanted, higher food prices and farmers being pressured to exit the business entirely. For cities, the picture is more nuanced. Major urban centres like Phoenix — roughly 40 percent dependent on Colorado River water — and Tucson are not expected to lose tap access, but residents are already seeing the cost of water rise sharply. One Arizona city, Gilbert, has raised residential water rates by 50 percent since April 2025 alone.

The proposal is designed to be adaptive, with actual reduction levels reassessed every two years based on hydrological conditions, and binding operating guidelines are expected by October 1. Legal challenges are widely anticipated; existing water law frameworks governing the river, some of which expire at the end of 2026, have long been a source of interstate conflict. As Arizona State University water law professor Rhett Larson put it succinctly: "We are not running out of water. We're running out of cheap water." The coming months of state-level deliberation and potential courtroom battles will determine how the burden of a shrinking river is ultimately shared.