NASA Data Feeds River Forecasts as Snow Drought Effects Linger

This item describes how NASA Earth observations are being integrated into machine-learning river-flow forecasts used by Tacoma Power in Washington state during the 2026 snow drought. Tacoma Power operates the largest hydroelectric project on the Cowlitz River, using water behind Mayfield and Mossyrock dams to generate electricity for more than 151,000 homes per year.

The forecasts come from Upstream Tech's HydroForecast, which combines weather forecasts and river measurements with NASA satellite data on snow cover and vegetation conditions to predict river flow from hours to days ahead. Updated every two hours, the forecasts help reservoir managers, hydropower producers, water utilities, and government agencies prepare for storms, plan reservoir releases, and navigate dry periods. NASA's Earth-observing satellites, including MODIS and VIIRS, provide information on snow cover and vegetation greenness across entire watersheds, even where ground monitors are sparse.

The 2025-26 winter brought unusual warmth, with more precipitation falling as rain than snow across much of the West. January, February, and March each saw the lowest Western snow cover in the NASA MODIS record since 2001. On the Cowlitz River, a December 2025 atmospheric river caused one of the largest one-day inflow surges ever recorded at Tacoma Power's project, but snowpack remained only 20–50% of normal. By April 8, Washington state placed every watershed, including the Cowlitz, under a drought emergency, and from April to June peak daily inflows were among the lowest on record, leaving reservoirs short of water for summer demand, according to Saul Villarreal, Tacoma Power's senior hydro operations manager.

The collaboration illustrates NASA's mission to make space-based observations useful on the ground. As Erin Urquhart, NASA Water Resources program manager, said, when an American company incorporates NASA's freely available data into forecasts that help prepare for floods, generate power, and steward water supplies, that is NASA delivering practical value to the nation.