New forecast shows anticipated risks to Columbia Basin water supplies

Changes in climate, agricultural practices, groundwater use, and growing populations are critical factors influencing water supplies in Washington's Columbia River Basin. Challenging trends in these areas are expected to create vulnerabilities in the region's water availability by the mid-2040s, according to a draft forecast from the Washington Department of Ecology and the State of Washington Water Research Center at Washington State University.

Every five years, Washington law requires Ecology to report on how changing water supply and demand could affect communities, farms, and fish over the following 20 years. The findings are intended to help elected officials and water managers identify current vulnerabilities and plan for long-term water supply needs.

Some of the factors studied in the report are the same that led Ecology to issue a statewide drought declaration in April this year - the fourth year in a row for the Yakima River Basin and other parts of Eastern Washington.

"We are already experiencing the increased pressures that come from consecutive droughts," said Melissa Downes, projects section manager for Ecology's Office of Columbia River.

"These pressures will grow as back-to-back droughts happen more often and for longer periods of time. That makes it even more important to understand the science and what challenges are coming our way. We use this framework to guide our decisions and help communities become more climate resilient."

Supply and demand will change in timing and location

The 2026 forecast supports previous estimates that, by the 2040s, less water will be available in summer and early fall. As the region warms, more annual precipitation will fall as rain instead of snow, and what snowpack does build up in winter will run off earlier.

The forecast also finds that groundwater levels remain at risk of declining, particularly the deeper aquifer layers. In some areas, this risk can be lowered by reducing future pumping or increasing recharge to the aquifer.

"We think of Washington as being a water-rich state. Unfortunately, our water supplies and demands are unevenly distributed across the state and seasons, which leads to vulnerable communities and ecosystems," said Sasha McLarty, associate professor in Washington State University's Department of Civil and Environmental Engineering and the lead of the research team. "These new findings can help to inform actions that we can take now to mitigate future vulnerabilities."

Other forecast highlights include:

• An increase in multi-year droughts, which could cause significant economic and environmental impacts
• Benefits and tradeoffs of water conservation efforts
• Emerging housing demands for water that are not included when assessing current needs

Washington's Water Future

This forecast is another indication of the widespread challenges facing water supplies statewide. Earlier this year, Washington Gov. Bob Ferguson launched the Washington's Water Future initiative to identify strategies to ensure clean, reliable water for people, fish, agriculture, and the economy. Although the water initiative is separate from the five-year Columbia Basin forecast, the issues are largely the same.

Ecology is holding discussions in river basins around the state this summer to gather local input and ideas on these water supply challenges. The agency will publish key findings from those meetings later this year.

Learn more and provide feedback

Ecology is accepting public comments on the draft Columbia Basin Long-Term Water Supply and Demand Forecast from July 1 to 31. After reviewing comments, the agency will send a final report to the Legislature in November.

How to comment:

• Go online to view the draft and leave comments.
• Attend in-person workshops to hear findings, ask questions, and submit comments in breakout groups:
  • July 9, 10 a.m. - 1 p.m.
    Department of Ecology Central Region Office
    1250 W Alder St., Union Gap
  • July 28, 10 a.m. - 1 p.m.
    Moses Lake City Hall
    401 S Balsam St, Moses Lake
• Register on Zoom for a virtual public comment workshop 4-6 p.m. July 20.
• Comments may also be submitted by mail to:
  • Jennifer Stephens
    Department of Ecology
    1250 W. Alder Street
    Union Gap, WA 98903-0009