Western Reservoirs: Lake Powell and the Megadrought

The reservoirs of the American West are the lifeblood of a dry region — and many have shrunk alarmingly. Driven by the worst drought in over a thousand years, Lake Powell on the Colorado River fell more than 40 feet, while other Western water bodies have declined too. This guide tracks how the West's major reservoirs have changed since 2015 and explains why their levels matter for water and power across the Southwest.

How low are Western reservoirs?

The chart shows the change in surface elevation of major Western reservoirs since 2015, in feet. The standout is Lake Powell, the giant reservoir behind Glen Canyon Dam, which plunged dozens of feet during the drought years before a wet winter brought partial relief. Others — the shrinking Salton Sea and the much-watched Great Salt Lake — show their own troubling declines. The lines tell the story of a region running short of water.

Lake Powell and the Colorado River crisis

Lake Powell and Lake Mead, the two largest U.S. reservoirs, store water from the Colorado River for some 40 million people across seven states and Mexico. Two decades of megadrought, combined with chronic over-allocation of the river's water, drained both to record lows — at one point approaching the level below which Glen Canyon Dam could no longer generate hydroelectric power, or even release water downstream. A wet 2023 winter offered a reprieve, but the long-term trend remains deeply concerning, forcing unprecedented negotiations over who must cut their water use.

The Great Salt Lake's decline

Utah's Great Salt Lake — the largest saltwater lake in the Western Hemisphere — has also shrunk dramatically, hitting record lows as drought and upstream water diversions starved it of inflow. A falling lake doesn't just shrink a landmark: it exposes a dry lakebed laden with toxic dust that blows into nearby Salt Lake City, and it threatens the ecosystem and the industries that depend on the lake. Like the Colorado River reservoirs, it's a warning sign of a water system under severe stress.

Why it matters: water for the West

These aren't just scenic lakes — they're the storage tanks that let the arid West function. They supply drinking water for major cities, irrigation for the farms that grow much of the nation's produce, and hydroelectric power for millions. When they fall toward critical thresholds, the consequences cascade: water restrictions, power concerns, crop losses, and fierce political fights over a shrinking resource. Their levels are among the most important environmental numbers in the West.