
The first sign of serious trouble for the drought-stricken American Southwest could be a whirlpool. It could happen if the surface of Lake Powell, a man-made reservoir along the Colorado River that’s already a quarter of its former size, drops another 38 feet down the concrete face of the 710-foot Glen Canyon Dam here. At that point, the surface would be approaching the tops of eight underwater openings that allow river water to pass through the hydroelectric dam. The normally placid Lake Powell, the nation’s second-largest reservoir, could suddenly transform into something resembling a funnel, with water circling the openings. If that happens, the massive turbines that generate electricity for 4.5 million people would have to shut down — after nearly 60 years of use — or risk destruction from air bubbles. The federal government projects that day could come as soon as July.