4 min read
Snow drought and unusually warm temperatures in the Colorado Basin in 2026 helped drive down reservoir water storage in the U.S. West.
NASA Earth Observatory
The effects of a meager mountain snowpack across the Upper Colorado Basin in winter 2025-2026 had made their way downstream to Lake Powell by summer. After seasonal snowmelt declined to a relative trickle, the second-largest reservoir in the U.S. sat at record-low levels in late August and early September.
These images show a portion of Lake Powell just above Glen Canyon Dam as observed by the OLI (Operational Land Imager) on the NASA-USGS Landsat 8 satellite on September 1, 2017 (left), and September 10, 2026 (right). In the 2026 image, the water level stood at 3,517.24 feet. About a month prior, it had dipped below the previous record-low level of 3,519.92 feet, set on April 13, 2023, and continued to tick downward in early September. The 2017 image represents one of the highest water levels of the past decade.
The Colorado River feeds Lake Powell and then Lake Mead farther downstream, which also hit record-low levels in August 2026. Managed by the U.S. Bureau of Reclamation (USBR) and other agencies, the river provides water and electric power to more than 40 million people—including in Las Vegas, Phoenix, Los Angeles, and San Diego—and water to some 5 million acres of farmland in the Southwest.
Much of the Colorado Basin is arid or semi-arid, so a large portion of the river’s flow originates as snowmelt from higher elevations. The Upper Colorado Basin, like many mountainous areas across the U.S. West, saw unusually little snow accumulation in winter 2025-2026, constituting a snow drought. Stretches of record warmth further sapped the snowpack. As a result, water from snowmelt did little to replenish lake levels in spring, as it typically does.
The USBR took steps in April 2026 to stabilize Lake Powell and keep it from falling below the level needed for hydropower production—an outcome the agency deemed possible by August 2026 without intervention. USBR began releasing water from Flaming Gorge Reservoir in northern Utah and southern Wyoming into Lake Powell. It also reduced releases from Lake Powell into Lake Mead, canceled a “controlled flood” in April intended to build sandbars for fish habitat, and skipped a “cool mix” release in August aimed at protecting native species.
Drought in the U.S. Southwest has been ongoing since about the start of the 21st century—what experts have called a megadrought—and continues to strain water resources. Several projects and tools funded by NASA and powered in part by NASA Earth observations are helping decision-makers throughout the Colorado Basin monitor drought and respond to its effects.
At the Colorado River headwaters, for example, a dashboard based on the Western Land Data Assimilation System (WLDAS) provides real-time soil moisture, snow water equivalent, and evapotranspiration visualizations that inform Colorado’s drought task force, as well as weekly U.S. Drought Monitor maps.
Nearer to Lake Powell, the Drought Severity Evaluation Tool, co-developed with the Navajo Nation, helps leaders monitor localized drought indices, precipitation trends, and vegetation health across tribal lands. (With funding from NOAA’s National Integrated Drought Information System, its adoption expanded to Oklahoma’s Chickasaw and Choctaw Nations in 2025.) And the Colorado River Integrated Assessment tool, developed by Arizona State University researchers in partnership with the Central Arizona Project, consolidates improved modeling and NASA-satellite-validated information on snowpack, surface and groundwater storage, soil moisture, and more across the entire basin into a single interactive view.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey and lake elevation data from the U.S. Bureau of Reclamation. Story by Lindsey Doermann.

JPEG (9.55 MB)

JPEG (10.77 MB)
Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet.
Relentless rains are threatening a lake in Kenya’s Great Rift Valley that has become a key hub in the global…
Drought in the Rio Grande basin contributed to New Mexico’s largest reservoir dwindling to its lowest level in decades.
Drought and water releases drained the Arizona reservoir to levels that have led to widespread fish deaths.
Subscribe to the Earth Observatory and get the Earth in your inbox.
NASA's Earth Observatory brings you the Earth, every day, with in-depth stories and stunning imagery.
Explore Earth Science
Open access to NASA’s archive of Earth science data
NASA explores the unknown in air and space, innovates for the benefit of humanity, and inspires the world through discovery.