Corps studies need for hydropower

By Sarah Brown
Of The New Era/Lebanon Local

UPDATE Oct. 31, 2023: The dates for the public listening sessions to be recorded for the report to Congress have been posted. They are: Monday, Nov. 13, 2 to 4 p.m. (virtual), Monday, Nov. 13, 5:30 to 7:30 p.m. (virtual), and Tuesday, Nov. 14, 5:30 to 7:30 p.m. (in-person).

The U.S. Army Corps of Engineers, Portland District, is undergoing multiple studies to evaluate and improve conditions for ESA-listed fish across the Willamette Basin. In September, the USACE held two public sessions last month to inform the public about a study it is performing to determine federal interest in the continuation of hydropower production in its Willamette Valley System (WVS).
The study is a response to the Water Resource Development Act of 2022 (WRDA22) (section 8220), which requires the USACE to determine whether there would be any national benefits to deauthorizing hydropower at one or more federal dams in the Willamette River Basin. The system consists of 13 dams and reservoirs between Detroit and Cottage Grove, including Green Peter and Foster.

Water is released through Green Peter’s regulating outlet.

“We’ll be looking at several scenarios in the report to Congress,” said Kathryn Tackley, technical lead of the project. “These include partial deauthorization, meaning the turbines would provide station service power for the dam and for our facilities only; so no power would be marketed. The second scenario is full deauthorization and decommissioned penstock, and the third scenario being evaluated is full deauthorization with reconfigured penstock, meaning that we reconfigure the penstocks to allow for the continual release of water through those outlets.
“For the three scenarios, we are comparing the scenarios against what we’re considering our baseline operations, which is the operations we’re currently carrying out to 2023 operations. Once we provide this report to Congress, if they ask us to take a deeper look into deauthorization of hydropower at one or more dams in the Willamette Basin, then we could at that point look at various reservoir operations that would include variable or different reservoir elevations than we currently operate with.”
Separate from the WRDA22 study, Green Peter is already experiencing disruption following a 2021 order from Federal Judge Marco Hernandez which requires the dam to be drawn down approximately 140 feet below typical winter reservoir levels by mid-November in an effort to preserve young Chinook salmon and steelhead. This would be the lake’s lowest level since it was built in the mid-1960s.

Docks at Sunnyside Park jut out into nothingness as water levels decrease from the first deep drawdown.

The move impacts access to the Thistle Creek and Whitcomb Creek boat ramps on Green Peter and also impacts the dam’s ability to produce hydropower during the drawdown. According to the plan, the operation “will severely reduce power generation” at Green Peter starting in fall of 2023 as the drawdown begins. The production of electricity is expected to cease by mid-October through mid-January.
Prior to the injunction, USACE would lower the dams to winter reservoir levels by December and begin refilling in February (concluding in mid-May), but levels remained high enough to continue producing power. The power produced by the dams was transferred to and marketed by Bonneville Power Administration (BPA), but also supplied backup power to the dams.

Diagram courtesy of USACE

Green Peter dam is designed with a spillway near the top, penstock (which flows water to the powerhouse turbines) near the center, and regulating outlet near the bottom. Foster is equipped with a spillway and penstock, but no regulating outlets.
As part of another study, in January of this year, the USACE held public meetings to discuss a draft of its programmatic environmental impact statement (EIS) for the Willamette River Basin system. The EIS was last updated in 1980, since which time lawsuits and court orders have demanded the Corps retrofit dam operations to help native salmon and steelhead avoid extinction.
At that meeting, the Corps presented multiple options for how the agency could manage the 13 dams and reservoirs. For Green Peter and Foster, the Corps’ preferred option comprised of operational measures at Green Peter and structural measures at Foster for improving downstream fish passage. Similar to current injunction-related operations, Geen Peter operations would include an annual “spring spill” over the dam by filling Green Peter and using the spillway to pass young fish downstream. At Foster, fish would spill in spring and fall.
The new deep drawdown exercise would begin in summer/early fall at Green Peter to meet a target elevation in the fall, with the lowest elevation occurring in mid- to late-November, which would help the fish find the regulating outlet and keep swimming downstream.
Residents who attended that meeting expressed concern about loss of recreational access and fisheries, while others were worried about loss of hydropower under the plan. Kathryn Warner, technical lead of the EIS, said “the plan is not to remove hydropower; it’s to figure out how to feasibly operate it.”
In February, the USACE Portland District held public meetings to discuss updating its master plan for the dams, essentially serving as blueprints outlining strategies for overseeing and protecting all recreational, natural and cultural resources within the managed area of the land. The Corps last updated its master plan in 1987.

Following the first deep drawdown of Green Peter, dead juvenile Kokanee salmon appeared on the river below the dam. Photo courtesy of Steve D’Accardo

The ruling ordered the Corps to make changes to its dams in the Willamette Basin so that juvenile salmon and steelhead could pass through them more easily. The fish are listed under the Endangered Species Act and, according to environmentalists, dams on the Willamette River have blocked access to spawning grounds, which has contributed to population declines.
Just this past weekend, dead juvenile Kokanee fish littered the river downstream of Green Peter dam. A pathology report indicated the fish died from barotrauma, caused by the deep drawdown. Read our story at https://www.lebanonlocalnews.com/drawdown-results-in-thousands-of-dead-fish/.
The deep drawdowns now require the Corps to lower the elevation of the reservoirs to within 25 feet or less of the dams’ regulating outlets, prioritizing water flow through the outlets rather than through the penstock to the hydropower turbines, especially during the night when fish have higher rates of migration.
The September meetings (Sept. 13-14) hosted by USACE Portland District were held virtually and served only as a public service to inform Oregonians about its current work of study for the federal government. The WRDA22 tasked the USACE with assessing the future of hydropower in the Willamette Valley Basin, providing initial information in a report that will help inform Congress on potential future decisions.
Kelly Janes, USACE senior planner and public involvement specialist, led the presentation, emphasizing it was solely the perspective of the Corps and not any other involved entities.
The 13 dams operated by the Portland District were built between 1940 and 1969 following the implementation of the Flood Control Act of 1938 with the primary purpose of flood management. Between $1 billion to $2 billion in flood damage is reportedly prevented every year.

The Green Peter reservoir reveals what lies beneath its surface as water levels decline.

Other uses of the dams were also authorized, including hydropower, municipal and industrial water supply, irrigation, fish and wildlife, recreation, and water quality and navigation.
The hydropower facilities were designed to produce as much marketable hydropower as possible, Janes said. A 2008 Endangered Species Act Jeopardy Biological Opinion, however, required the Corps to change how they operate flow management in order to improve conditions for listed endangered species.
Now, she said, it’s not about how much power they can produce, but about figuring out how much power they are able to produce within the restrictions. The 2021 injunction further reduced the Corps’ ability to generate power.
Of the 13 dams, four do not have hydropower, one has a private hydropower facility (licensed by the Federal Energy Regulatory Commission), and eight are federally operated for hydropower.
“Three of those (eight with federal hydropower) are what we call power peaking facilities,” said Dustin Bengtson, deputy Willamette operating projects manager. “Detroit, Green Peter and Lookout Point have what we call re-regulating projects below them that, as originally designed, allow for an increase in generation to meet peak demand in the system without having wild fluctuations in down river levels, and allow us then to capture that water and generate power again from that downstream facility.”
USACE Park Ranger Christie Johnson said the eight Corps hydropower dams could collectively provide enough power to service about 300,000 homes (500 megawatts) and make electricity in Oregon less costly than other states.
However, due to changes in the operation of the system under the injunction, they are estimated to provide around 120 megawatts of power, enough to power approximately 95,000 homes.

Recreationists set out for a day on the river at Sunnyside Park on Oct. 8. Photo by Sarah Brown

Responding to a question from someone at the Sept. 14 meeting, Operations Project Manager Erik Petersen said, “I can’t predict whether there would be brown-outs. I do know we’ve had a number of concerns raised about the local stability of both transmission and distribution (of electrical power) if we don’t have generation or condensing capability, in particular on the South Santiam.
“That’s a legitimate concern of people and we have elevated that issue to both the BPA as well as the utilities that serve that area, and are making sure that we understand all of those dynamics, as power generation is being impacted right now at Green Peter by a deep drawdown to comply with the injunctive order. We certainly need more information on that and before, I think, anything changes in a substantive way, we’re gonna understand that and the folks responsible for transmission and generation will ensure that they’re taking that into consideration in their operation.”
For the last 80 years the Corps has been trying to maintain a balance between the multiple demands on the system (power, irrigation, recreation, etc), and changes in one of those demands affects the other demands, Bengtson said.

Diagram courtesy of USACE

Janes listed several benefits of the penstock, stating the dams were designed so the penstock would be a primary outlet for passing flow. She said the penstock allows better temperature control of released water, attracts fish that are seeking water flow for upstream spawning, offers a more managed flow of released water, and can be used as flowthrough during maintenance of the regulating outlet and other areas of the dam.
Since many of the dams are located in remote areas where power can be cut off due to snow storms, fires or earthquakes, being able to produce reliable power through the penstock for the facility is important, Janes said. If the power goes out, the dams will be able to continue functioning for their intended use. Also, turbines reduce total dissolved gas that is released downstream.
“This is important because high levels of total dissolved gas can cause gas bubble disease in fish, which could cause mortality or injury,” she said.
As part of its report to Congress, which is due in June 2024, the Corps will host a public listening session during which time the public can provide their perspective and opinions on the future of hydropower across the Corps’ Willamette Valley system of dams.
The Corps will record the comments during those sessions and include them in its report to Congress verbatim to help inform Congress’ decision-making process. When the dates of these future sessions have been determined, they will be published on the Portland District website at https://www.nwp.usace.army.mil/Locations/Willamette-Valley/WRDA22-Report/.