The U.S. government finalized a 10-year plan on Friday to reduce water allocations from the Colorado River for California, Nevada, and Arizona. The two-year operating guidelines, signed by Interior Secretary Doug Burgum, mandate a roughly 21% reduction in water supplies for these three Lower Basin states during 2027 and 2028 to address declining reservoir levels.
The federal intervention follows three years of unsuccessful negotiations between the seven states that rely on the river. While a 1922 agreement divided water rights between the Upper and Lower Basins, the Lower Basin states—California, Arizona, and Nevada—have historically consumed more than their allocation. Recent drought conditions have pushed Lake Powell and Lake Mead, the nation’s largest reservoirs, to record lows this month.
Under the finalized plan, the three Lower Basin states will see their combined water allocation reduced by 1.6 million acre-feet (MAF) per year in 2027 and 2028. The four Upper Basin states—Colorado, Utah, New Mexico, and Wyoming—will not face mandatory cuts. However, the federal government reserved the authority to increase mandatory cuts to 3.0 MAF per year after 2028 if reservoir levels continue to drop.
For residents in the affected states, the impact could manifest as changes in water availability or costs for municipal use and irrigation starting in 2027. If the Bureau of Reclamation determines that reservoir levels have reached critical thresholds after 2028, these cuts could nearly double to 3.0 MAF. Arizona officials warned that such a scale of reduction would cause significant economic disruption. Furthermore, because the Glen Canyon Dam was reported to be less than 30 feet above the minimum level required for power generation as of Thursday, further declines could threaten the electricity supply for 6 million people.
The plan establishes a precedent for federal intervention in Western water management when states fail to reach a consensus. While Arizona Governor Katie Hobbs (D) indicated the state would use legal means to protect its water rights, state negotiators suggested that a new consultation process might avoid immediate litigation. The Interior Department will review operating guidelines every two years, with the next major assessment likely to determine if the deeper 3.0 MAF cuts will be triggered for the period between 2029 and 2036.