Arizona Joins Nevada in Fight Over Colorado River Cuts
Arizona has joined Nevada in a legal challenge to the Trump administration's proposed cuts to Colorado River water deliveries. Arizona officials announced the intervention in October 2026, backing Nevada's lawsuit against the U.S. Interior Department over the plan for the next two years. The Guardian
Gov. Katie Hobbs said Arizona was taking legal action alongside Nevada because the federal government refuses to hold the Upper Basin accountable. She said the federal proposal threatens draconian cuts beyond the Lower Basin Agreement, a two-year voluntary water conservation pact among Arizona, California and Nevada. Arizona Department of Water Resources Director Tom Buschatzke said intervention in the Nevada lawsuit is necessary to protect Arizona's legal rights to Colorado River water.
Arizona, California and Nevada make up the river's lower basin. Wyoming, Colorado, Utah and New Mexico make up the upper basin, which was spared from cuts under the federal intervention plan.
Lake Mead and Lake Powell, the river's major reservoirs, have fallen to historically low levels due to overuse and a changing climate. States sharing the river missed several deadlines to reach consensus on new sharing rules before the federal government intervened.
The Interior Department issued its 2027-2028 Operating Guidelines and Record of Decision for post-2026 Colorado River operations on Aug. 21, 2026, signed by Interior Secretary Doug Burgum. Interior Department The guidelines call for reductions of 1.25 million acre-feet per year in deliveries to lower basin states in each of the next two years. Under a lower basin sharing proposal cited by Interior, that would mean annual reductions of 760,000 acre-feet for Arizona, 440,000 acre-feet for California and 50,000 acre-feet for Nevada, plus voluntary conservation and storage of at least 700,000 acre-feet over the two-year period.
The decision also sets criteria for releases from Lake Powell based on actual hydrology, while maintaining a minimum elevation of 3,510 feet to support operational reliability at Glen Canyon Dam. It provides for operation of the Aspinall, Flaming Gorge and Navajo reservoirs under the secretary's authorities to help protect dam infrastructure, and for a federally managed pool to meet tribal firming obligations and provide limited offsetting to reduce tribal impacts.
Interior said both Lake Powell and Lake Mead hit record lows in the weeks before the August announcement, and that their combined contents had not been that low since before Lake Powell began filling after closure of the gates at Glen Canyon Dam in 1963. The Bureau of Reclamation released an August 2026 24-Month Study to determine 2027 operations, projecting Lake Powell would begin the Oct. 1 water year between elevations 3,540 and 3,510 feet. The decision also establishes a 10-year framework to develop future operating guidelines for Lake Powell and Lake Mead.
Nevada filed a lawsuit challenging the plan to cut deliveries. The administration's plan would impose 21% water cuts on California, Nevada and Arizona starting in 2027, according to earlier reporting. Reuters
