PORTLAND, Ore. -- The U.S. Army Corps of Engineers (USACE), Portland District has released the Willamette Valley System Operations and Maintenance Final Environmental Impact Statement (FEIS).
USACE manages the Willamette Valley System (WVS) to store and release water from 13 reservoirs within the Willamette River Basin to meet its congressionally authorized purposes such as flood control, fish and wildlife, hydropower, recreation, irrigation, water supply, water quality, and navigation.
The primary purpose of the WVS is flood risk management. It has prevented an average of $1.08 billion in damages annually. Water managers must keep reservoir elevations low to maintain storage space, capture rainfall and minimize flooding potential through spring. This must be balanced with what seem to be conflicting purposes: refilling the reservoirs before summer for irrigation, hydropower generation, water quality improvement and recreation.
USACE completed the previous programmatic National Environmental Policy Act evaluation of the WVS in 1980. Since then, USACE has optimized operations and built structures to improve conditions for fish species listed under the Endangered Species Act. Considerable information has become available since the 1980 EIS was completed, which has been incorporated into the existing conditions and analyses in this FEIS.
This FEIS analyzes the environmental and social benefits and impacts of seven action alternatives and a No-action Alternative. The alternatives are distinguished by operational or structural measures, designed to improve flow, water quality, and fish passage.
Publication of the FEIS is the first step in a two-step approach to continue operations and comply with the Water Resources Development Act of 2024 (WRDA 2024), which requires USACE to analyze an alternative that ceases hydropower operations at the eight dams in the WVS that generate electricity. The second step will be a supplemental EIS (SEIS) to include this new analysis and the effects of a deeper drawdown of Detroit reservoir as required by the 2024 National Marine Fisheries’ Biological Opinion (BiOp).
“The completion of this EIS is a significant milestone that deserves celebration, but there is more to do,” said COL Dale Caswell, Jr., Portland District commander. “over the next year, we will have another opportunity to listen to the public and work with our partners to finalize how we will operate these dams for future generations.”
USACE expects to complete the SEIS in the spring of 2026 and decide how to operate and maintain the WVS for 2026 and beyond.
Learn more at the USACE Willamette Valley System EIS webpage.