Lake Powell dropped to a record low of roughly 1,072.9 metres on Saturday, the latest sign that prolonged drought is pushing the two largest reservoirs in the United States toward dangerous limits. Combined storage at Lake Powell and Lake Mead was last this diminished in 1957, during construction of the Glen Canyon Dam, federal data shows. Lake Mead fell to its own historic low about a week earlier.
Powell now sits roughly 9.1 metres above the level where hydropower turbines would stop operating. Federal officials warned in April that major intervention was necessary to prevent breaching that threshold by year's end. The Colorado River system, fed largely by Rocky Mountain snowfall, supplies water and electricity to more than 40 million people across seven states.
In response, the Department of the Interior released an Environmental Impact Report calling for mandatory water-use reductions of 3 million acre-feet annually through 2036 for the Lower Basin states. The Bureau of Reclamation also proposed a 10-year plan in July that could substantially cut allocations to Arizona, California and Nevada. Officials announced Thursday they will not release cool water from Glen Canyon Dam this year.