As Western states haggle over reducing water use because of declining flows in the Colorado River Basin, a more hopeful drama is playing out in Glen Canyon.

Lake Powell, the second-largest U.S. reservoir, extends from northern Arizona into southern Utah. A critical water source for seven Colorado River Basin states, it has shrunk dramatically over the past 40 years.

An ongoing 22-year megadrought has lowered the water level to just 22.6% of “full pool,” and that trend is expected to continue. Federal officials assert that there are no plans to drain Lake Powell, but overuse and climate change are draining it anyway.

As the water drops, Glen Canyon – one of the most scenic areas in the U.S. West – is reappearing.

This landscape, which includes the Colorado River’s main channel and about 100 side canyons, was flooded starting in the mid-1960s with the completion of Glen Canyon Dam in northern Arizona. The area’s stunning beauty and unique features have led observers to call it “America’s lost national park.”

Lake Powell’s decline offers an unprecedented opportunity to recover the unique landscape at Glen Canyon. But managing this emergent landscape also presents serious political and environmental challenges. In my view, government agencies should start planning for them now.

Glen Canyon Dam, which towers 710 feet high, was designed to create a water “bank account” for the Colorado River Basin. The U.S. Bureau of Reclamation touted Lake Powell as the “Jewel of the Colorado” and promised that it would be a motorboater’s paradise and an endless source of water and hydropower.

Lake Powell was so big that it took 17 years to fill to capacity. At full pool, it contained 27 million acre-feet of water – enough to cover 27 million acres of land to a depth of one foot – and Glen Canyon Dam’s turbines could generate 1,300 megawatts of power when the reservoir was high.

Soon the reservoir was drawing millions of boaters and water skiers every year. But starting in the late 1980s, its volume declined sharply as states drew more water from the Colorado River while climate change-induced drought reduced the river’s flow. Today the reservoir’s average volume is less than 6 million acre-feet.

Nearly every boat ramp is closed, and many of them sit far from the retreating reservoir. Hydropower production may cease as early as 2024 if the lake falls to “minimum power pool,” the lowest point at which the turbines can draw water. And water supplies to 40 million people are gravely endangered under current management scenarios.

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