NEW YORK — The water is saved, for now.
Seven Western states have agreed on a plan to manage the Colorado River amid a 19-year drought, voluntarily cutting their water use to prevent the federal government from imposing a mandatory squeeze on the supply.
State water officials signed the deal Tuesday after years of negotiations, forestalling what would have been the first federally enforced restrictions on the river’s lower basin. But any victory may be short-lived. Climate change promises to make the American West increasingly hot and dry, putting further pressure on the Colorado and the 40 million people who depend on its water.
“We all recognize we’re looking at a drier future,” said Tom Buschatzke, director of the Arizona Department of Water Resources.
The water in Lake Mead, the vast reservoir formed by the Hoover Dam that supplies the lower basin, has dropped to levels not seen since it began to fill in the 1960s. Lake Mead and Lake Powell, another reservoir on the river, are essential sources of water for Southern California and Arizona, and sit at less than 40 percent full.
By the beginning of March, the water level in Lake Mead had dropped to 1,088 feet above sea level. At 1,075 feet, under guidelines agreed to in 2007, the federal government would declare a shortage on the lower Colorado River, and mandatory water restrictions would go into effect.
Without sacrifices by the states — Colorado, New Mexico, Utah, and Wyoming in the upper basin, and Arizona, California, and Nevada in the lower basin — the reservoir could reach the trigger point next year, though recent heavy snowfall in the mountains that feed the river may help for a time.
Brenda W. Burman, commissioner of the Bureau of Reclamation, the federal agency that oversees the river, pressured states and their water agencies to make a deal. Without an agreement, she said, she would “take action to protect the river,” without specifying what that action would be.
The seven states and participating water districts sent a drought contingency plan to Congress, seeking legislation “for immediate implementation,” according to a statement from the bureau.
“It’s a hard-to-put-together puzzle, all about sharing some burdens,” said Sharon B. Megdal, director of the Water Resources Research Center at the University of Arizona. The plan builds on water conservation efforts that have, for example, kept Southern California water use relatively flat for decades despite a population boom.
The Imperial Irrigation District, California’s largest user of water from the river, threatened to derail the process when it demanded $200 million from the federal government to help restore the Salton Sea, the state’s largest lake. But other state water districts said they would cover Imperial’s share of water cuts without requiring flows to the Salton Sea be reduced.
The Salton Sea is drying up in part because of measures taken by California farmers to use less water, which result in less runoff flowing into the lake. As it dries, fine dust from the lake bed blows into the air, which has been linked to childhood asthma and other illnesses.
Robert D. Schettler, a spokesman for the Imperial District, called the decision to move forward without its participation “unfortunate,” adding that a pact without the Imperial District “may mean getting it done, but not getting it right.”