Willamette Valley Biological Opinions

On July 11, 2008, the U.S. Fish and Wildlife Service and National Oceanic and Atmospheric Administration Fisheries issued biological opinions, which were part of a consultation process with the U.S. Army Corps of Engineers, the Bonneville Power Administration and the Bureau of Reclamation on the impact of the 13 Willamette Valley Project dams on ESA-listed species in the Willamette River Basin.

The Endangered Species Act requires action agencies, in this case the Corps, BPA and the BOR, proposing to do anything that might affect an ESA-listed species to first seek the opinion of USFWS or NMFS about the impacts of the action on the species. These resource agencies issue biological opinions to the agencies making the proposal. The goal of a biological opinion is ensuring that the proposed federal action won't reduce the likelihood of survival and recovery of the listed endangered species. 

The Corps requested the consultations to ensure continued operations of the dams, reservoirs and riverbank protection projects without precluding fish survival.

Corps completed actions

North Santiam River:

- Interim Temperature Control/Downstream Fish Passage through Operational Modifications at Detroit (2009) 

Detroit Dam, southeast of Salem, Ore., on the North Santiam River, provides a variety of functions including flood risk management and power production. However, it also blocks fish passage and the U.S. Army Corps of Engineers is in the process of building temperature control and fish passage at this site.

Adult Upstream Passage – Minto Adult Fish Collection Facility (2012)

- Design underway for Long-term Temperature/Downstream Passage at Detroit (ongoing)


South Santiam River:

- Extended Foster Dam Fish Weir Operations (2013) 

- Adult Upstream Passage – Foster Adult Fish Collection Facility (2014)

- Downstream Fish Passage Spillway Weir Modifications at Foster Dam (2017/2018)


McKenzie River:

- Water Temperature Control Tower at Cougar Dam (2005)

- Operational Dowsntream Fish Passage (2009)

- Adult Upstream Passage – Cougar Adult Fish Collection Facility (2010)

- Downstream Passage Testing w/ Portable Floating Fish Collection (PFFC) at Cougar (2014)


Middle Fork River: 

- Downstream fish passage through Fall Creek Deep Drawdowns (2009)

- Adult Upstream Passage – Fall Creek Fish Collection Facility Design (Construction 2016-2018)

- Implementation of Middle Fork Willamette Research Monitoring and Evaluation Plan (2017)

- Completed alternative evaluations and design for Dexter Adult Fish Collection Facilities



- Habitat Technical Team work – land purchases/habitat restoration funded (ongoing)

Willamette Basin fish program

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The Willamette River Basin historically supported large numbers of salmon, steelhead, Oregon chub and bull trout. However, significant population growth and the accompanying changes to the natural landscape have contributed to the decline of habitat necessary to support the natural lifecycle of those fish species.  (click for more)

Our Willamette Valley Project dams provide tremendous flood risk management, power generation, water quality improvement, irrigation, fish and wildlife habitat and recreation benefits to the region.


However, they also block access to significant amounts of high-quality fish spawning and rearing habitat, and prevent movement of sediment and large wood.  They have also degraded downstream habitat by altering seasonal flows and water temperature patterns that are important for fish.  Hatchery fish produced to mitigate the loss of their wild cousins have also had a negative effect on the genetic diversity and productivity of wild fish in the basin.


The U.S. Fish and Wildlife Service listed Oregon chub as endangered under the Endangered Species Act in 1993, and bull trout as threatened in 1999. The National Marine Fisheries Service listed Upper Willamette River spring Chinook and Upper Willamette River winter steelhead as threatened species in 1999.


The Endangered Species Act required us to seek the opinions of the U.S. Fish and Wildlife Service and the National Marine Fisheries Service about the effects of our Willamette Valley Project operations on these ESA-listed species. These agencies’ 2008 biological opinions include “reasonable and prudent alternatives” – actions to minimize adverse effects on listed species and their critical habitat.


Our efforts in progress or completed to increase survival of ESA-listed fish include:

 Improved adult salmon and steelhead upriver passage
  • We completed the Cougar Adult Fish Collection Facility in 2010, and have witnessed increasing returns of wild adult spring Chinook salmon each year.
  • Our construction of a new Minto Fish Collection Facility is underway, with an expected completion date in spring 2013.
  • Our construction of a new Foster Fish Collection Facilityis underway, with an expected completion date in spring 2014.
  • We are conducting advanced design and planning for upgrades to fish facilities at Dexter and Fall Creek dams.
 Improved juvenile salmon and steelhead passage downriver
  •  We have been conducting a deep drawdown operation at Fall Creek Dam for the past six years to assist passage of juvenile spring Chinook salmon.
  • We awarded a contract in winter 2012-2013 to build a Portable Floating Fish Collector to evaluate options for collecting and transporting juvenile salmon at several of our dams.
  • We are evaluating downstream passage options for juvenile salmon at Cougar, Detroit and Lookout Point dams.
 Better regulation of downriver water temperatures for ESA-listed fish species' lifecycles
  •  We completed a temperature control tower at Cougar Dam in 2005 to improve water quality for spring Chinook salmon.
  • We are conducting advanced design and planning for a temperature control solution at Detroit Dam.