Oregon — The U.S. Army Corps of Engineers (USACE) Portland District is asking the public to weigh in on a new Supplemental Environmental Impact Statement (SEIS) that could reshape future operations of the agency’s 13 Willamette Valley dams.
The draft SEIS builds on a six-year environmental study completed in April 2025 but incorporates major new requirements that emerged just before the earlier study concluded—including updated endangered species protections and a mandate to consider eliminating hydropower at multiple dams.
USACE officials said the agency’s goal is to assess how potential operational changes may affect endangered fish, water quality, dam operations, communities, and recreation.
“Public input is the cornerstone of success when we’re working with projects that impact our communities,” said Liz Oliver, project manager for the supplemental study. “Comments will help us better understand how the proposed changes in the SEIS may affect communities, the environment, and reservoir users.”
Key Issues in the Supplemental Study
The SEIS focuses on two major updates:
New Biological Opinion:
The National Marine Fisheries Service issued a new environmental review requiring a deeper fall drawdown at Detroit Reservoir to aid endangered fish passage. The change—expected no earlier than fall 2026—will be evaluated for its impacts on water quality and nearby communities.
Hydropower Removal Alternative:
The Water Resources Development Act of 2024 requires USACE to examine an additional alternative that would remove hydropower as an authorized purpose at eight Willamette Valley dams.
“We’re moving quickly to complete this study and ensure we’re meeting our obligations, while also considering potential impacts to communities,” said Col. Dale Caswell, commander of the Portland District. He encouraged the public to participate so the agency can “make informed decisions about the future management of the Willamette Valley dams.”
How to Participate
The public has 45 days—from Nov. 14 to Dec. 29—to submit comments.
The draft SEIS will be available starting Nov. 14 at:
www.nwp.usace.army.mil/WVS-EIS/
USACE will host multiple opportunities to learn about the proposal and ask questions.
Virtual Information Sessions
Nov. 19, 2025 — Noon
- Meeting ID: 993 148 805 804
- Passcode: md3qN7xc
- Phone: +1 601-262-2433 (Conference ID: 849 999 963)
Nov. 19, 2025 — 5:30 p.m.
- Meeting ID: 993 353 552 564
- Passcode: mH9Yy3n2
- Phone: +1 601-262-2433 (Conference ID: 870 696 779#)
In-Person Meetings
Detroit City Council Chambers
Dec. 6, 2025 — 10 a.m.–Noon
345 Santiam Ave, Detroit, OR 97342
Broadway Commons, Salem
Dec. 10, 2025 — Noon–2 p.m.
Dec. 10, 2025 — 5:30–7:30 p.m.
1300 Broadway St. NE, Room 307, Salem, OR 97301
Submitting Comments
Comments must be submitted in writing:
Email:
willamette.eis@usace.army.mil
Mail:
U.S. Army Corps of Engineers
Attn: CENWP-PME-E / Willamette SEIS
P.O. Box 2946
Portland, OR 97208-2946
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