Lake Powell, the second-largest reservoir in the United States, dropped to a water surface elevation of 3,517.24 feet on September 10, 2026, the lowest level ever measured at the reservoir since it began filling behind Glen Canyon Dam in the 1960s. The reading, reported by NASA’s Earth Observatory, breaks the previous record of 3,519.92 feet set in April 2023 by more than two and a half feet. It caps a summer in which the reservoir straddling the Utah-Arizona border slid past its old floor around mid-August and kept falling through early September.
NASA’s Earth Observatory, which tracks the reservoir with satellite imagery and elevation data supplied by the U.S. Bureau of Reclamation, traced the decline to an exceptionally dry and warm winter across the Upper Colorado River Basin during the 2025-2026 snow season. Mountain snowpack that normally melts into the river through spring and summer came in thin, and unusually warm temperatures sped up what little snow there was. The basin has been in a drought stretching back to the early 2000s, but the 2025-2026 winter compounded it with what NASA described as a snow drought layered onto storage already run down by two decades of shortfall.
Record low breaks the 2023 mark by more than two feet
The new low is not a marginal dip. Lake Powell first crossed below its 2023 record around August 15, 2026, and continued sinking through early September before NASA’s Earth Observatory logged 3,517.24 feet on September 10. Reclamation’s own hourly gauge data showed the lake at 3,517.69 feet on September 23, holding within half a foot of the record and far below the roughly 3,700-foot mark the reservoir reaches near full pool. At that elevation, the reservoir held about 5.13 million acre-feet against a maximum capacity of roughly 23.3 million acre-feet — close to 22% full. ScienceDaily first flagged the milestone publicly on September 22, drawing on the same NASA elevation data.
The reservoir’s minimum power pool sits at 3,490 feet, the elevation below which Glen Canyon Dam can no longer reliably generate hydropower through its main turbines. September’s record leaves Lake Powell roughly 27 feet above that floor, a buffer that has been shrinking for years as the basin’s dry stretch has outpaced operating rules written when the reservoir still sat close to full.
Reclamation has already cut releases once this year
The Bureau of Reclamation started responding months before the record fell. Its July 2026 24-month study shows the Department of the Interior reduced Lake Powell’s scheduled annual release from 7.48 million acre-feet to 6.00 million acre-feet for water year 2026 after “historically dry conditions persisted” and projections showed the reservoir sliding below 3,500 feet without a cut. Reclamation also released additional water from the smaller Flaming Gorge Reservoir in Wyoming to prop up Powell’s elevation, canceled its planned spring “controlled flood” release that normally redistributes sediment and supports fish habitat below the dam, and skipped an August “cool mix” release meant to protect native fish that depend on cooler water.
Those moves bought time rather than reversing the trend. Lake Mead, the largest U.S. reservoir and Lake Powell’s downstream counterpart on the Colorado River, also hit a record low in August 2026, and Reclamation’s September 23 gauge data put it at 1,038.06 feet and about 26% of capacity. The two reservoirs form a single managed system for seven basin states, so a shortfall at one increasingly shows up at the other within weeks.
40 million people depend on the river behind the record
The Colorado River system that Lake Powell anchors supplies water and hydroelectric power to more than 40 million people across the Southwest, including Las Vegas, Phoenix, Los Angeles and San Diego, and irrigates about 5 million acres of farmland. That reach is why a single elevation reading at a reservoir most of those 40 million people will never see still moves through municipal water agencies, farm districts and power utilities from Wyoming to the Mexican border.
A separate August 2026 report from the water-policy outlet Western Water described basin states bracing for the possibility that Lake Powell could enter formal “low-elevation operations” as soon as 2027 if the coming winter fails to deliver a strong snowpack, a step that would force further cuts to hydropower generation and downstream releases. The Bureau of Reclamation’s own Glen Canyon Dam operations page notes the dam’s turbines were engineered around a reservoir close to full pool, and running near minimum power pool degrades how efficiently they generate electricity even while they keep operating.
Reclamation’s July study projects the lake could fall as low as 3,491.75 feet by April 2027, less than two feet above the 3,490-foot power pool threshold, before spring runoff begins pulling it back up. Whether that recovery holds now depends on a winter snowpack the agency will not be able to measure until the storms that build it either arrive or do not.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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