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 on 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.