Treaty Deal Cuts Colorado River Water Use Across U.S. and Mexico

YUMA, AZ — Mexico has agreed to voluntarily reduce its Colorado River water usage over the next two years, joining Arizona, California, and Nevada in a coordinated effort to prop up dangerously low reservoir levels at Lake Mead and Lake Powell.

Under a temporary treaty amendment known as Minute 334, Mexico will reduce its annual consumption by 250,000 acre-feet of water. That is the equivalent of more than 100,000 Olympic-sized swimming pools in both 2027 and 2028. The move comes as the U.S. Bureau of Reclamation withholds 1.2 million acre-feet from the three Lower Basin states over the same two-year span.

Both Lake Mead and Lake Powell currently sit at approximately 27 percent capacity amid an enduring drought, leaving the river system in a critical state.

Experts see only a partial fix

Water policy experts warn that while the international pact offers temporary relief, it does not resolve the long-term crisis facing the basin.

"The plan now — the Lower Basin plan plus Mexico — is probably around half of where we need to get to stabilize the reservoirs," said Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University.

Porter noted that annual demand across the basin must decrease by 3 million to 4 million acre-feet to achieve stability, roughly a quarter of the river system's overall 15 million to 16 million acre-foot demand.

"It is not likely enough to keep the reservoir levels stable," Porter said. "The only thing that would be wrong about that would be if we had more than one year of extremely good snowpack."

Environmental restoration in focus

Beyond slowing the decline of reservoir storage, the agreement aims to protect environmental restoration efforts. Portions of the water will help sustain wetlands and river deltas in the Lower Colorado River that have previously run dry, supporting broader multi-agency initiatives across Arizona, California, and Mexico.

The deal also establishes an environmental work group and a pilot program to manage the salinity of Colorado River water as it reaches Mexico.

More to come, officials say

The U.S. and Mexico signed the amendment to extend cooperative measures for the river through 2028. Mexico's reduction represents roughly 17 percent of its original allocation under the 1944 International Water Treaty.

Officials emphasized that without consecutive wet winters to replenish the watershed, deeper and more permanent conservation measures will be required across the region. If conditions worsen, the two governments have agreed to consult on potential additional reductions for both countries in 2028.