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Lake Powell
Glen Canyon Dam's reservoir on the Colorado River in Utah and Arizona
Lake Powell fills a canyon many people never got to see. When Glen Canyon Dam closed its diversion tunnels on September 13, 1963, the Colorado River began backing up over Glen Canyon, a maze of sandstone alcoves, side canyons and Ancestral Puebloan sites that photographer Eliot Porter later called the place no one knew. Seventeen years later, on June 22, 1980, the reservoir reached full pool at 3,700 feet (1,128 m), stretching about 186 miles (299 km) through Utah and Arizona with roughly 1,900 miles (3,060 km) of shoreline. It is named for John Wesley Powell, who led the first known expedition down the river in 1869.
Full, Lake Powell holds about 24.3 million acre-feet (30 km³), second only to Lake Mead. It anchors Glen Canyon National Recreation Area, established in 1972, and gives boaters access to Rainbow Bridge. Its role is to bank Upper Basin water for delivery downstream and to spin Glen Canyon Dam's hydropower turbines. The dam itself was a compromise. The Sierra Club, led by David Brower, defeated a dam at Echo Park in Dinosaur National Monument in the 1950s, and Brower long regretted not fighting Glen Canyon too.
In 2026 the reservoir reached its lowest point since it first filled. On August 15, 2026, it dropped to 3,519.91 feet (1,072.9 m), just below the April 2023 record, and by September 10 it stood at 3,517.24 feet (1,072 m). That left it less than 30 feet above 3,490 feet (1,064 m), the minimum power pool where the turbines can no longer run reliably. Reclamation projects further decline in 2027, and drained canyons and stranded marinas have become the lake's most visible landmarks.