In 2000, Lake Mead was full of deep, midnight-blue water that flooded the banks of the rivers that fed it. But 20 years later it has shrunk drastically. And the pools are lighter, too, almost teal in places, a sign of shallower waters, connected by extraordinarily thin canyons.
In new images from this month, the lake is now surrounded by a puckered shoreline and a white shadow called the bathtub ring, remnants of salts and minerals left on the canyon walls by receding water.
“These reservoirs were staggeringly full 20 years ago,” said Jennifer Pitt, Colorado River program director for the National Audubon Society, referring to Lake Mead and Lake Powell, the two major reservoirs on the Colorado River. The low levels at Lake Mead are indicative of dangerously low levels throughout the Colorado River basin. Now the basin is “dangerously close to a Day Zero situation,” Ms. Pitt said, referring to the point where the reservoir dries up.