PORTLAND — The U.S. Army Corps of Engineers is re-evaluating how it will maintain and operate 13 dams in Oregon’s Willamette Valley to protect three species of endangered fish. 

The dams, collectively known as the Willamette Valley Project, were built more than 50 years ago to provide flood control from heavy spring rains. Other authorized purposes include irrigation, hydropower, recreation and fish and wildlife habitat.

Officials at the Corps’ Portland District outlined seven alternatives for project operations during a virtual public meeting on Jan. 19. The changes described in each alternative are intended to improve water quality, temperature and fish passage at the dams for spring chinook, winter steelhead and bull trout.

A federal judge in 2020 ruled the dams had pushed endangered Upper Willamette salmon and steelhead runs to the brink of extinction, while the Corps lagged years behind making scheduled upgrades that were agreed to in an earlier court settlement with environmental groups.

The Corps is now updating its Environmental Impact Statement, or EIS, for the Willamette Project, walking the tightrope between the needs of fish and the needs of other users.

“It is a delicate dance that has increasingly become more complex,” said Erik Petersen, operations project manager for the Corps. “Everyone is giving something up, and everyone is gaining something. No one is getting anything exactly the way they want it.” 

Public scoping for the updated EIS began in 2019. The Corps received 717 suggestions for measures that could be implemented at one of the dams. From there, the list was whittled down to 23 measures based on their feasibility and benefits.

The measures are divided into four sub-categories — fish passage, water quality, flow and “common to all,” which includes hatchery improvements and gravel augmentation.

The Corps mixes and matches these measures into each of the seven alternatives, looking to strike the right balance of actions to maximize the dams’ benefits. 

For example, alternatives 3A and 3B focus on boosting fish passage by modifying operations, rather than substantially changing any of the structures. That would involve a deep spring and fall season reservoir drawdowns, boosting river flows at a time when adult and juvenile salmon are migrating. 

Alternative 4, on the other hand, takes a more building-based approach, adding new downstream passage and water quality facilities to keep fish healthy and moving.

Kelly Wingard, project manger, said the Corps is still assessing the impact of alternatives. The agency will release its draft EIS sometime in the fall, which will include a preferred alternative. A final EIS and Record of Decision could be finished by 2024.

The last time an EIS was done for the Willamette Project was in 1980, Wingard said. Since then, the project’s demands have changed substantially.

“Really, we’re re-looking at how we balance the different priorities for the system,” Wingard said. 

Last year, irrigators gained access to 328,000 acre-feet of water stored in the project’s reservoirs, part of a reallocation plan that divvied 1.6 million acre-feet of water among farmers, cities and fish and wildlife. 

But Kathy Warner, a technical expert and water supply specialist for the Willamette Project EIS, said changes in dam operations could mean changes in timing and availability of water for irrigation. Agriculture, she said, is part of the Corps’ analysis of the alternatives. 

“Each of these alternatives could have a different level of impact, or effect,” Warner said. “They’re looking at the different ways the system could operate.” 

For more information about the Willamette Valley Project EIS, including details about each alternative, visit https://gather.cdmsmith.com/v/NkjxE7ErqlQ