December 3, 2025 — New research uses more than 40 years of data from NASA and the U.S. Geological Survey’s (USGS) Landsat satellites to help dam operators improve the health of salmon fisheries.
The Columbia and Snake rivers in the Pacific Northwest contain nearly 20 dams, which provide flood control, hydroelectric power, and water for irrigation. But they also change the way the rivers flow. For the study, researchers tracked temperature up and downstream of dams using surface temperature data from Landsat satellites. Data from these satellites support our nation’s agricultural industry, including farmers and food production. Researchers found warm water downstream of dams stressed salmon, making them swim faster. The scientists developed a tool called THORR, or Thermal History of Regulated Rivers, to perform this research.
“NASA’s focus on advancing our understanding of Earth’s freshwater resources is reflected in tools like THORR, which leverage decades of satellite data to improve water management strategies,” said Erin Urquhart, program manager, Earth Action Water Resources Program at the agency’s headquarters in Washington. “By making this information accessible and useful, NASA is ensuring its science directly benefits the communities and industries that depend on these resources.”
The recent study, funded by NASA, provides regularly updated information about river temperature that dam operators can use to fine-tune their operations. Faisal Hossain, a civil and environmental engineering professor at the University of Washington and one of the study authors, explained that when water spills over the dam from the top layer of the reservoir, the water tends to be hotter, as it was warmed by the Sun. That warmer water can stress and even kill salmon, while water that’s discharged through the turbines cools the river downstream. Strategically discharging water from lower levels of the reservoir could help salmon thrive, saving dam operators time and other, costlier interventions, Hossain said.