Forecast Informed Reservoir Operations: Willamette Valley Syetem
FIRO is a reservoir-operations strategy that better informs decisions to retain or release water by integrating additional flexibility in operation policies and rules with enhanced monitoring and improved weather and water forecasts (American Meteorological Society; 2020). Since 2014, CW3E and federal, state, and local partners have developed, tested, and implemented FIRO at reservoirs across the Western United States. FIRO is now being assessed nationwide.
PROJECT STATUS
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FIRO Evaluation |
Work Plan in progress |
OVERVIEW
The Willamette River Basin spans roughly 11,500 square miles between the Cascade Range and the Oregon Coast Range in western Oregon, draining north into the Columbia River and encompassing the cities of Portland, Salem, and Eugene. The Willamette River and its tributaries support 70% of Oregon’s population, rich agricultural production, and aquatic habitat for 34 native fish species, including federally listed Upper Willamette spring Chinook salmon, Upper Willamette winter steelhead, and bull trout.
The U.S. Army Corps of Engineers (USACE) Portland District operates the Willamette Valley System, a coordinated network of 13 multipurpose dams and reservoirs constructed between 1940 and 1969. The system supports seven authorized purposes: flood risk management, hydropower, irrigation, water quality, water supply, fish and wildlife, and recreation. The Willamette Valley system faces challenges balancing water reliability and flood risk management. The motivation for evaluating FIRO’s potential here is to strengthen USACE’s ability to carry out approved storage reallocations for irrigation and municipal industrial water supply. Project partners are evaluating whether FIRO can help manage the Willamette Valley System more adaptively under increasing hydroclimate variability, evolving regulatory requirements, and more frequent water shortages. The first FIRO Steering Committee Meeting for the Willamette Valley System took place in September 2025.
FIRO PROGRESS
FIRO implementation progress at the Willamette Valley System. Purple circles with checkmarks indicate completed milestones, green, blue, and gold circles without checkmarks indicate upcoming milestones.
KEY FEATURES
13 Dams
presenting a unique opportunity to test FIRO across an extensive, interconnected river basin system
70%
of Oregon’s population lives in the Willamette basin
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Steering Committee partners working collaboratively across federal, state, and research institutions to advance FIRO
STEERING COMMITTEE
Co-Chairs
Marty Ralph, Center for Western Weather and Water Extremes, Scripps Institution of Oceanography, UC San Diego
Cary Talbot, US Army Corps of Engineers, Engineer Research and Development Center
Ivan Gall, Oregon Water Resources Department
Salina Hart, US Army Corps of Engineers, Portland District
Members
Elissa Yeates, US Army Corps of Engineers, Engineer Research and Development Center
Joseph Forbis, US Army Corps of Engineers, Engineer Research and Development Center
Stephen King, NOAA National Weather Service, Northwest River Forecast Center
Alexandra Etheridge, United States Geological Survey
Chris Frans, United States Bureau of Reclamation
Anne Mullan, NOAA National Marine Fisheries Service
Rose Wallick, United States Geological Survey
Support Staff
Kathy Warner, US Army Corps of Engineers, Portland District
Jay Jasperse, Sonoma Water/CW3E
Rob Hartman, RKH Consulting Services
Arleen O’Donnell, Eastern Research Group
Taylor Dixon, Center for Western Weather and Water Extremes, Scripps Institution of Oceanography, UC San Diego
Kristiana Chan, Center for Western Weather and Water Extremes, Scripps Institution of Oceanography, UC San Diego
RESOURCES & REPORTS
Work Plan — in development; final approval anticipated in mid-late 2026
USACE Willamette Tea Cup Diagram
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Contact Kyla Van Maanen at kvm@ucsd.edu for more information
Last updated: June 30, 2026