Public comments are open until June 6 on whether and how the U.S. Army Corps of Engineers should implement a deeper fall drawdown at its Detroit Reservoir as well as whether the agency should permanently end hydropower production at eight dams in Oregon’s Willamette River basin.
The Corps completed an Environmental Impact Statement for its 13 Willamette Valley System dams this spring, but two new federal requirements – the Detroit drawdown and ending hydro operations at its projects – popped up as the agency was finishing its EIS. The new requirements prompted the need for a Supplemental EIS, which is now open for public scoping, the Corps said.
The Corps completed and released April 11 its first environmental impact statement since 1980 of its Willamette Valley system of 13 dams. The Final EIS analyzes the environmental and social benefits and impacts of seven action alternatives and a No-action Alternative. The Corps chose alternative 5 as its preferred alternative.
“As part of the National Environmental Policy Act process, we collect public comments to help us shape what we study in the SEIS – we call this process public scoping,” said Liz Oliver, the Portland District project manager leading the SEIS process. “Comments will help USACE better understand how these proposed changes may affect communities, the environment and reservoir users.”
The Corps prepares a SEIS when significant new information or requirements come up that need additional analysis and public input, the agency said in a news release.
This SEIS will evaluate:
- Implementing a Deeper Fall Drawdown at Detroit Reservoir: On Dec. 26, 2024, NOAA Fisheries issued a Biological Opinion requiring the Corps to perform a deeper fall drawdown at Detroit Reservoir to support upper Willamette wild spring Chinook salmon and wild winter steelhead listed as threatened under the federal Endangered Species Act. The drawdown is not expected to occur until fall 2026, at which time the Corps will evaluate its effects—such as potential impacts to water quality and local communities—in the SEIS.
- Ending Hydropower Production at the eight Willamette Valley Dams equipped with generators: In December 2024, Congress passed the Water Resources Development Act of 2024, which directed the Corps to study an additional alternative that would remove hydropower as an authorized purpose and end hydropower operations at some Willamette Valley dams. This step is necessary to complete federal consultations and environmental compliance under NEPA, the Corps said.
Because these two requirements came late in the EIS process, the Corps said, it went ahead and finalized and published the EIS and issued an interim Record for Decision while the SEIS is developed.
The interim ROD was published May 16 and can be found here: https://www.nwp.usace.army.mil/Media/Public-Notices/Article/4188310/public-notice-record-of-decision-for-interim-operations-willamette-valley-syste/
The Corps’ Portland District will publish a new ROD after the completion of the SEIS, expected in 2026. That ROD will select an alternative for the continued operation of the Willamette Valley System into the future.
For more information on the EIS or the SEIS, visit https://www.nwp.usace.army.mil/WVS-EIS/
USACE will accept comments via email or postal mail, or in person at public scoping comment sessions via written comment cards.
Email: [email protected]
Mail: U.S. Army Corps of Engineers
Attn: CENWP-PME-E / Willamette EIS
P.O. Box 2946
Portland, OR 97208-2946
The public will have the opportunity to check in on four scoping sessions. Two are virtual and two are in person. They are:
Virtual Meeting log-in information is here: https://www.nwp.usace.army.mil/WVS-EIS/
Wednesday, May 28 • 6-7 p.m.
Thursday, May 29 • noon to 1 p.m.
In-Person Meetings are:
Saturday, May 31 • 10 a.m. to noon
Detroit City Hall
345 Santiam Ave.
Detroit, Oregon 97342
Tuesday, June 3 • 6-8 p.m.
Broadway Commons
1300 Broadway St. NE
Salem, Oregon 97301
The Corps’ preferred alternative includes both structural and operational measures that, taken as a whole, prove to be best for the ESA-listed threatened spring Chinook and winter steelhead, according to the Corps’ FEIS. The preferred alternative, which is alterative 5, rates high for viable salmonid population metrics, as well as passage efficiency for juveniles at the dams and their survival through the dams.
The preferred alternative includes:
- Floating Screen Structure and Temperature Control Tower at Detroit
- Adult fish facility at Green Peter Dam
- Spring and fall draw down to Diversion Tunnel at Cougar Dam
- Floating Surface Collector at Lookout Point
- Pacific lamprey passage and infrastructure
- Integrated Habitat and temperature flow regime
For more details of the Corps’ preferred alternative, see CBB, April 21, 2025, “Corps Final EIS For Willamette Valley’s 13 Dams Selects Alternative Best For ESA-Listed Fish, Next Comes Supplemental EIS,” https://columbiabasinbulletin.org/corps-final-eis-for-willamette-valleys-13-dams-selects-alternative-best-for-esa-listed-fish-next-comes-supplemental-eis/
The Willamette River is 180 miles long and drains 11,487 square miles or nearly 12 percent of the state of Oregon. It meets the Columbia River at Portland. Today, over 70 percent of Oregonians live in the Willamette River basin.
The Corps’ Willamette Valley System consists of 13 reservoirs, encompass 11 multiple purposes with 2 re-regulating dams and 8 hydropower dams. The dams were built between 1939 and 1969 and the last EIS was in 1980. Most of the dams are “high head” dams, over 250 feet tall and as a result, the Project blocks about 70 percent of Chinook and 33 percent of steelhead historic habitat in the upper Willamette basin while also modifying downstream habitat, the DEIS says.
The WVS also includes 5 fish hatcheries, a Willamette bank protection program and 100 miles of revetments (bank support and changes). The WVS provides approximately $1 billion in annual flood risk benefits, 26 million in hydropower revenue, and 5.4 million in recreation benefits, the EIS says.
More information about WRDA 2024 is here: https://www.usace.army.mil/Missions/Civil-Works/Project-Planning/Legislative-Links/wrda_2024/
NOAA Fisheries 2024 BiOp is here: https://www.fisheries.noaa.gov/s3/2024-12/WCRO-2023-00324-PERM-BiOp-WillametteValleySystem-20241226.pdf
For background, see:
— CBB, April 21, 2025, Corps Final EIS For Willamette Valley’s 13 Dams Selects Alternative Best For ESA-Listed Fish, Next Comes Supplemental EIS, https://columbiabasinbulletin.org/corps-final-eis-for-willamette-valleys-13-dams-selects-alternative-best-for-esa-listed-fish-next-comes-supplemental-eis/
— CBB, March 23, 2023, Comments On Corps’ Draft EIS for 13 Willamette Valley Dams Question Whether Plan Avoids Jeopardy For ESA-Listed Salmonids, https://columbiabasinbulletin.org/comments-on-corps-draft-eis-for-13-willamette-valley-dams-question-whether-plan-avoids-jeopardy-for-esa-listed-salmonids/
— CBB, March 9, 2023, SCIENCE PANEL GIVES THUMBS-UP ON FISH RESPONSE MODELS CORPS USED TO DEVELOP DRAFT WILLAMETTE RIVER BASIN EIS, https://cbbulletin.com/science-panel-gives-thumbs-up-on-fish-response-models-corps-used-to-develop-draft-willamette-river-basin-eis/
— CBB, December 2, 2022, CORPS RELEASES DRAFT EIS FOR 13 WILLAMETTE BASIN DAMS INTENDED TO AID ESA-LISTED SALMON, STEELHEAD; DRAWDOWNS, STRUCTURAL CHANGES, LESS POWER, https://cbbulletin.com/corps-releases-draft-eis-for-13-willamette-basin-dams-intended-to-aid-esa-listed-salmon-steelhead-drawdowns-structural-changes-less-power/
— CBB, February 24, 2022, CORPS DETAILS TO COUNCIL NUMEROUS MEASURES TAKEN AT WILLAMETTE PROJECTS TO AVOID JEOPARDIZING LISTED SALMON, STEELHEAD, HTTPS://CBBULLETIN.COM/CORPS-DETAILS-TO-COUNCIL-NUMEROUS-MEASURES-TAKEN-AT-WILLAMETTE-PROJECTS-TO-AVOID-JEOPARDIZING-LISTED-SALMON-STEELHEAD/
— CBB, September 2, 2021, JUDGE ISSUES FINAL ORDER FOR OPERATIONS AT CORPS’ WILLAMETTE VALLEY DAMS TO AID ESA SALMON, STEELHEAD; DEEP DRAWDOWNS, SPILL, HTTPS://CBBULLETIN.COM/JUDGE-ISSUE-FINAL-ORDER-FOR-OPERATIONS-AT-CORPS-WILLAMETTE-VALLEY-DAMS-TO-AID-ESA-SALMON-STEELHEAD-DEEP-DRAWDOWNS-SPILL/
— See CBB, July 15, 2021, “Federal Judge Orders Corps To Take Immediate Action To Protect ESA-Listed Willamette Valley Wild Spring Chinook, Steelhead; ‘No Patience For Further Delay,’” https://cbbulletin.com/federal-judge-orders-corps-to-take-immediate-action-to-protect-esa-listed-willamette-valley-wild-spring-chinook-steelhead-no-patience-for-further-delay/
— CBB, June 17, 2021, GROUPS WANT EXPEDITED STUDY TO DEAUTHORIZE POWER PRODUCTION AT TWO CORPS’ WILLAMETTE DAMS TO REDUCE COSTS, AID ESA-LISTED SALMON, STEELHEAD, https://cbbulletin.com/groups-want-expedited-study-to-deauthorize-power-production-at-two-corps-willamette-dams-to-reduce-costs-aid-esa-listed-salmon-steelhead/.