The U.S. Bureau of Reclamation announced the first shortage declaration for Lake Mead and the lower Colorado River Basin in its history, triggering cuts to individual states' water allocations beginning in January.
After an inordinately dry spring, the river’s Upper Basin saw runoff into Lake Powell that was just over a quarter of average runoff. Projected rates for unregulated inflow into Lake Powell — that is, the amount that without storage behind Glen Canyon Dam would have flowed into Lake Mead — is around 32 percent of the average.
Overall, the bureau said, total system storage for the Colorado River is at 40 percent capacity, a decline of 49 percent from this point in 2020.
“Like much of the West, and across our connected basins, the Colorado River is facing unprecedented and accelerating challenges,” Assistant Secretary for Water and Science Tanya Trujillo said in a statement Monday. “The only way to address these challenges and climate change is to utilize the best available science and to work cooperatively across the landscapes and communities that rely on the Colorado River. That is precisely the focus of the White House Interagency Drought Working Group—a multi-agency partnership created to collaborate with States, Tribes, farmers and communities impacted by drought and climate change to build and enhance regional resilience.”
Lake Mead will operate under shortage status for the entirety of calendar 2022. Under the 2007 Colorado River Interim Guidelines and the 1944 Water Treaty with Mexico, this includes required reductions and contributions for each individual state forming the Lower Basin. These requirements include about 18 percent of Arizona’s annual apportionment, 7 percent of Nevada’s annual apportionment and 5 percent of Mexico’s annual apportionment.
Last month, a similar compact governing the Upper Basin enacted drought operations.
In June, water levels in Lake Mead reached an all-time low of 1,071.56 feet above sea level, or just 37 percent full. The Southwest has recently seen its worst drought in two decades, drastically reducing snowpack and thus the river’s flow.