U.S. officials on Monday issued an official shortage declaration for the massive Western reservoir of Lake Mead for the first time, triggering water cuts to the drought-stricken Southwest.
The shortage will reduce water apportionments to Arizona, Nevada and Mexico for the year beginning in October, the U.S. Bureau of Reclamation said in a statement.
Arizona will lose 18% of its annual apportionment, while Nevada will see cuts of 7%. Apportionments to Mexico will be slashed by 5%.
Lake Mead, formed in the 1930s from the damming of the Colorado River at the Nevada-Arizona border, is the largest reservoir in the United States. It is crucial to the water supply of 25 million people in the cities of Los Angeles, San Diego, Phoenix, Tucson and Las Vegas.
Crippling drought in the U.S. West has brought Lake Mead and Lake Powell, the nation’s second-biggest reservoir, to historic lows. Total water storage in the Colorado River system is at 40% of capacity, down from 49% a year ago, the bureau said.
Water releases in a given year are determined by an annual study anticipating the reservoirs’ water levels in winter. In January, Lake Mead is expected to be 1,065.85 feet (324.9 m), which is 9 feet below the official trigger for a shortage.
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