Summary
Lake Powell fell below its previous record-low elevation in August 2026 and stood at 3,517.24 feet on September 10. NASA links the decline to scarce mountain snow and unusually warm conditions in the Upper Colorado Basin.
Lake Powell, the second-largest reservoir in the United States, reached a record-low water level in August 2026 and continued falling into early September, according to NASA Earth Observatory. NASA’s comparison of Landsat 8 images shows the reservoir near Glen Canyon Dam on September 1, 2017, and September 10, 2026, when its elevation was 3,517.24 feet.
The earlier record low was 3,519.92 feet, set on April 13, 2023. Lake Powell first reached a new record low on August 15, 2026, and its level continued to decline through early September.
Why the reservoir fell
The decline followed a winter with unusually little snow accumulation in the Upper Colorado Basin. NASA describes those conditions in 2025–2026 as a snow drought. Stretches of record warmth further reduced the snowpack, leaving less meltwater to flow into the reservoir in spring, when snowmelt typically replenishes it.
Lake Powell sits on the Colorado River upstream of Lake Mead. In an arid and semi-arid basin, mountain snowmelt supplies a large share of the river’s flow, so a poor snow season can affect water storage downstream. Lake Mead also reached record-low levels in August 2026, NASA reports.
The Colorado River system supplies water and electric power to more than 40 million people, including residents of Las Vegas, Phoenix, Los Angeles and San Diego, and water to about 5 million acres of farmland in the Southwest. Lake levels therefore matter not only for stored water, but also for the operation of infrastructure along the river.
Measures to protect hydropower levels
In April 2026, the U.S. Bureau of Reclamation took steps to keep Lake Powell from dropping below the elevation needed for hydropower production. The agency released water from Flaming Gorge Reservoir into Lake Powell and reduced releases from Powell into Lake Mead. It also canceled an April controlled flood intended to build sandbars for fish habitat and skipped an August “cool mix” release aimed at protecting native species.
Lake Powell remained above the minimum power pool elevation of 3,490 feet in early September. Below that level, Glen Canyon Dam’s hydroelectric turbines can no longer generate energy effectively. The record-low elevation was therefore close to, but still above, this operational threshold.
NASA’s Landsat comparison documents the changing shoreline, while water-level measurements cited by the agency come from the Bureau of Reclamation. NASA also describes tools that combine Earth observations and other data to help decision-makers monitor drought across the basin, including systems for tracking snow, soil moisture and water storage.