Mexico agreed to a 250,000-acre-foot annual reduction in Colorado River deliveries during 2027 and 2028 under a new binational pact intended to slow the decline of Lake Mead and Lake Powell.
The United States and Mexico signed Minute 334 Sept. 2 in El Paso, Texas, and both governments approved it Sept. 8. The temporary addition to the 1944 water treaty coordinates Mexico’s reductions with new federal operating rules requiring Arizona, California and Nevada to collectively cut Lower Basin deliveries by 1.25 million acre-feet each year.
Under the states’ proposed sharing arrangement, Arizona would absorb 760,000 acre-feet of the annual cut, compared with 440,000 for California and 50,000 for Nevada. Mexico normally receives 1.5 million acre-feet, making its reduction roughly 17% of its treaty allocation.
Both reservoirs sit near 27% capacity after prolonged drought and water use exceeding supply. Sarah Porter, director of Arizona State University’s Kyl Center for Water Policy, told Arizona’s Family the combined Lower Basin and Mexico reductions may provide only about half the conservation needed to stabilize the system. She estimated annual demand must fall by 3 million to 4 million acre-feet.
Minute 334 continues Mexico’s option to store some unused water in Lake Mead through its Water Reserve and extends work on salinity, new water supplies and desalination. If forecasts worsen, the countries will consult on additional 2028 reductions.
Environmental groups welcomed protections for Colorado River Delta restoration and monitoring. The Nature Conservancy said conservation partners have enough secured water to sustain more than 1,000 acres of restored riparian habitat while the shortage persists.
The deal expires Dec. 31, 2028, leaving the seven Colorado River Basin states and federal officials to negotiate longer-term rules. Without consecutive wet winters, experts say deeper and more permanent reductions will remain necessary.
