Public comment period extended, additional public info session added for Detroit Reservoir deep drawdown, potential end to Willamette Valley hydropower

PORTLAND, Ore. – The U.S. Army Corps of Engineers (USACE) Portland District is extending the public comment period by 15 days and adding an in-person information session in Stayton, Ore., for a draft study that considers changes to how the agency operates its Willamette Valley dams.

The new deadline for submitting comments on the draft Supplemental Environmental Impact Statement (SEIS) is Jan. 13, 2026.

The SEIS builds upon a six-year study completed in April 2025 and addresses new requirements regarding endangered fish and hydropower production that emerged shortly before that study was finalized:

• A new environmental review for protected species, called a Biological Opinion (BiOp), from the National Marine Fisheries Service. The BiOp requires a deeper fall drawdown at Detroit Reservoir to support endangered fish. This drawdown is not expected to occur until late fall/early winter 2026, and the SEIS evaluates its potential effects on water quality and local communities.
• Compliance with the Water Resources Development Act (WRDA) of 2024. This act directs USACE to study an additional alternative that would remove hydropower as an authorized purpose at some Willamette Valley dams.

The SEIS will analyze the potential impacts of these changes on the environment, local communities, and dam operations.

“Extending the deadline will give Oregonians more time after the holidays to provide meaningful input.” said Liz Oliver, the project manager for the supplemental study. “The feedback will help guide our decisions, while we keep our forward momentum to complete this study.”

Comments on the draft SEIS must be submitted in written form and can be submitted via email, postal mail, in-person at the Stayton information session. USACE will accept comments sent to:

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

The draft SEIS is available to view at https://usace.contentdm.oclc.org/digital/collection/p16021coll7/id/28486/rec/2.

For more information, visit https://www.nwp.usace.army.mil/WVS-EIS/.

The in-person meeting is open-house style; USACE biologists and other technical experts will be available to take questions and explain the actions the agency is studying.

In-Person Meeting

📅 Dec. 16, 2025 
⏰ 6 p.m.
🏢 400 W Virginia St.
 Stayton, OR 97383

A recording of the previous public information session is available on YouTube.

Background:

USACE operates and maintains 13 dams in the Willamette River Basin. These dams provide flood risk management, water for irrigation and communities, recreation opportunities, in addition to supporting fish and wildlife. Managing these dams is a complex task that requires balancing a variety of needs and interests. The Willamette Valley System saves the region an estimated $900 million annually by preventing flood damages.