Washington: NASA satellite data is being used to improve river-flow forecasts and support water management decisions in the western United States, where the effects of an unusually dry winter are continuing into summer.

The technology is helping utilities, reservoir managers and government agencies prepare for changing water conditions, including floods, drought and fluctuating electricity demand.

Snow drought creates water challenges

During the winter of 2025-26, unusually warm conditions caused more precipitation to fall as rain instead of snow across large parts of the western US. Lower-than-normal precipitation also worsened water shortages in several areas.

NASA’s MODIS satellite record showed the lowest monthly snow cover in January, February and March since observations began in 2001.

On Washington’s Cowlitz River, mountain snowpack remained at only 20% to 50% of normal levels. A powerful atmospheric river in December brought a major surge of water into the river, but the rain-heavy winter meant less snow was available to melt gradually during summer.

By April, Washington state had declared a drought emergency across all its watersheds.

Satellite data strengthens river forecasts

Tacoma Power is using HydroForecast, a system developed by Upstream Tech that combines weather forecasts, river measurements and NASA satellite observations.

The system uses information on snow cover and vegetation conditions to predict river flows from hours to days ahead. Forecasts are updated every two hours and help operators decide how to manage reservoirs and prepare for changing weather conditions.

NASA data from the VIIRS instrument aboard the Suomi-NPP satellite provides information across large watersheds, including areas where ground-based monitoring is limited.

Supporting water security

Tacoma Power entered summer with reservoir levels close to average despite the dry spring. Stored water is supporting hydropower generation, environmental flows and public needs while providing greater flexibility during heat waves and unexpected outages.

NASA is also working with US agencies to incorporate satellite-based snow and groundwater information into water-supply forecasts and drought assessments.

The initiative highlights how observations from space are increasingly being transformed into practical tools for managing one of the world’s most vital resources — water.