NASA Data Helps Manage Rivers After Low Snow in the West

In 2026, western parts of the United States received much less snow than usual. This low snow remained a problem through the summer. NASA collects information from space that feeds into forecast tools. These tools use computer systems that learn from data to estimate river water volumes. The estimates support decisions about water use, electricity generation, and protection in Washington. Erin Urquhart leads the Water Resources program at NASA in Washington, D.C. She said that making satellite views useful on the ground is one of the agency’s goals.

Tacoma Power is a public utility that consults estimates from Upstream Tech’s HydroForecast tool. HydroForecast unites weather forecasts and stream readings with NASA satellite data that show snow distribution and plant conditions. Volume estimates extend from hours to multiple days and update every two hours. The main power plants at Mayfield Dam and Mossyrock Dam on the Cowlitz River deliver electricity for more than 151,000 homes each year. People who manage storage basins, produce water power, supply water, and serve in government roles use the estimates. They prepare for strong weather, arrange releases from storage, or face periods of low flow.

During the colder season linking 2025 with 2026, higher temperatures caused more rain than snow across broad western zones. Some districts also recorded amounts below normal. Snow cover across the West in January, February, and March was the lowest for each month. This came from NASA’s continuous satellite series that began in 2001. The Cowlitz River displayed extreme variations under these conditions. In December 2025, a strong band of moisture from the Pacific arrived. It generated one of the largest single-day increases in inflow ever recorded at Tacoma Power’s plants. More rain sent water quickly to lower areas instead of building snow reserves high in the mountains for later melting. Snow amounts stayed between 20 and 50 percent of normal, and once spring began, rainfall lessened. On April 8, officials in Washington declared a drought emergency across all watersheds of the state, including the Cowlitz. Highest daily inflows from April to June ranked among the smallest in the historical series. Saul Villarreal is senior manager for hydroelectric operations at Tacoma Power. He noted that the limited water restricted the volume available for filling storage basins ahead of summer needs. The HydroForecast tool with NASA data helped Tacoma Power plan responses to the high water in December. In spring, longer-range estimates showed the chance of limited water from melting snow. This led the utility to keep storage levels higher than usual to retain water for summer. By the start of summer 2026, the reservoirs approached normal levels, and stored water supports consistent electricity generation. It maintains required flows for fish and other water life, enables recreation, and provides extra capacity for high temperatures or unexpected problems. This is one example of NASA science assisting water decisions in western territories. NASA also helped prepare the U.S. Drought Monitor for the first time during the week of August 17, 2026.

How do better river forecasts help communities during times of low snow or heavy rain?