Willamette River, Oregon

Expanding efforts for holistic watershed management

Nearly 70 percent of all Oregonians live within 20 miles of the Willamette River, making this waterway crucial to the social and economic well-being of the region. Corps dams in the basin provide numerous benefits such as flood risk management, hydropower generation and water supply. Environmental flow releases as part of the Sustainable Rivers Program activities are improving in-stream and side-channel habitats for salmon while maintaining important human uses of the river. Healthy habitats can support increased recreation and help the salmon industry.

The U.S. Army Corps of Engineers Portland District operates 13 dams in the Willamette Basin that provide a range of human benefits, including flood risk management, hydropower, irrigation, and recreation. However, operation of these dams has changed the volume and timing of water flow in the river, resulting in reduced peak flows, lower spring flows, increased summer low flows, and infrequent bankfull events. Alterations to the natural flow regime affect the health and viability of the freshwater ecosystems and the aquatic and terrestrial species and communities they sustain. To address this issue, the Corps and The Nature Conservancy have worked together to determine environmental flow requirements downstream of the dams, and to identify opportunities to restore key aspects of the flow regime.
Nearly 70 percent of all Oregonians live within 20 miles of the Willamette River, making this waterway crucial to the social and economic well-being of the region. Corps dams in the basin provide numerous benefits such as flood risk management, hydropower generation and water supply. Environmental flow releases as part of the Sustainable Rivers Program activities are improving in-stream and side-channel habitats for salmon while maintaining important human uses of the river. Healthy habitats can support increased recreation and help the salmon industry.
The U.S. Army Corps of Engineer’s system of 13 dams and reservoirs in the Willamette River basin are primarily for flood risk management; however, Oregon residents benefit from reservoir storage in other ways. The Corps is studying storage reallocation and is seeking comments on its draft integrated feasibility study report/environmental assessment and draft finding of no significant impact for the study.
The U.S. Army Corps of Engineers conducts a deep drawdown of Fall Creek Reservoir, southeast of Eugene Ore. to enable juvenile Chinook salmon passage, Nov. 26, 2011. Deep drawdowns at Fall Creek have been highly successful in passing these fish. Studies indicate a 98-99% survival rate for these out-migrating juveniles and is an important step in meeting the 2008 Biological Opinions for the Willamette Valley.
The U.S. Army Corps of Engineers built a temperature control tower (left) in 2005 at Cougar Dam, in Oregon’s Willamette Valley, which necessitated a drawdown of the reservoir. Corps plans to create downstream fish passage at the dam could affect reservoir levels during construction and installation. However, the Corps’ goal is to minimize impacts to stakeholders throughout the region.

Willamette River

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Story

The U.S. Army Corps of Engineers Portland District operates 13 dams in the Willamette Basin that provide a range of human benefits, including flood risk management, hydropower, irrigation, and recreation. However, operation of these dams has changed the volume and timing of water flow in the river, resulting in reduced peak flows, lower spring flows, increased summer low flows, and infrequent bankfull events. Alterations to the natural flow regime affect the health and viability of the freshwater ecosystems and the aquatic and terrestrial species and communities they sustain. To address this issue, the Corps and The Nature Conservancy have worked together to determine environmental flow requirements downstream of the dams, and to identify opportunities to restore key aspects of the flow regime.

 

Authorities

The Sustainable Rivers Program works within the Congressionally authorized purposes of dams that includes environmental benefits. Efforts on the Willamette River system focus on identifying opportunities to improve overall downstream ecosystem health and resiliency by modifying dam operations within the existing operational constraints, thus meeting existing federal and state mandates and authorities.

 

Partners

  • The Nature Conservancy
  • US Army Corps of Engineers
  • City of Salem, Oregon
  • US Geological Survey,
  • North Santiam Watershed Council
  • NOAA Fisheries
  • Oregon Department of Fish and Wildlife
  • North Santiam Water Control District
  • Confederated Tribes of the Grand Ronde
  • South Santiam Watershed Council
  • Oregon State University
  • Oregon Department of Environmental Quality
  • US Forest Service
  • US Forest Service PNW Research Station
  • GeoEngineers (consultant)
  • University of Oregon
  • Calapooia Watershed Council
  • Bonneville Power Administration
  • Eugene Water and Electric Board
  • McKenzie River Trust
  • Oregon Water Resources Department
  • McKenzie River Watershed Council
  • Bureau of Land Management
  • Willamette Riverkeepers
  • Friends of Buford Park
  • David Evans and Associates (consultant)
  • Ecohydrology Northwest (consultant)
  • Jones and Stokes (consultant)
  • Middle Fork Willamette Watershed Council
  • Coast Fork Watershed Council 

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    Resources

    1. Bach, L., Nuckols, J. and Blevins, E. 2013. Summary Report: Environmental Flows Workshop for the Santiam River Basin, Oregon. The Nature Conservancy, Portland, OR.
    2. Gregory, Stan, Ashkenas, Linda and Nygaard, Chris, 2007a. Summary Report to Assist Development of Ecosystem Flow Recommendations for the Coast Fork and Middle Fork of the Willamette River, Oregon. Oregon State University, Corvallis, OR.
    3. Gregory, Stan, Ashkenas, Linda and Nygaard, Chris 2007b. Summary Report Environmental Flows Workshop for the Middle Fork and Coast Fork of the Willamette River, Oregon. Oregon State University
    4. Jones, K.L., Mangano, J.F., Wallick, J.R., Bervid, H.D., Olson, Melissa, Keith, M.K., and Bach, Leslie, In press, Summary of environmental flow monitoring done in 2014-2015 for the Sustainable Rivers Project on the Middle Fork Willamette and McKenzie Rivers, Oregon.
    5. McDowell, P.F. Marcus, W.A. Walther, S. 2012. Willamette Sustainable River Project Phase 1: Development of a Monitoring Plan for Environmental Flow Recommendation on the Middle Fork Willamette River, Oregon Final Report. Eugene, OR.
    6. McDowell, P.F. Marcus, Dietrich, J. 2013. Willamette Sustainable River Project Phase 2: Development of a Monitoring Plan for Environmental Flow Recommendation on the Middle Fork Willamette River, Oregon. Eugene, OR.
    7. Risley, John, Wallick, J.R., Waite, Ian and Stonewall, Adam. 2010a. Development of an environmental flow framework for the McKenzie River basin, Oregon. U.S. Geological Survey Scientific Investigations Report 2010-5016, 94 p.
    8. Risley, John C., Bach, Leslie and Wallick, J. Rose 2010b. Environmental Flow Recommendations Workshop for the McKenzie River, Oregon. The Nature Conservancy, Portland, OR.
    9. Risley, J.C., Wallick, J.R., Mangano, J. F.,and Jones, K. L. An Environmental Streamflow Assessment for the Santiam River Basin, Oregon. U.S. Geological Survey
      Open File Report 2012-1133, 60 p. plus appendixes.
    10. Risley, John, Wallick, Rose, Waite, Ian and Stonewall, Adam, 2010. Development of an environmental flow framework for the McKenzie River basin, Oregon. U.S. Geological Survey Open File Report 2010-5016, 94 p.
    11. R, Wallick, L Bach, M. Olson, M. Keith, J. Mangano and K. Jones, 2017. Monitoring framework for evaluating hydrogeomorphic and vegetation responses to environmental flow releases in the Middle Fork Willamette, McKenzie and Santiam River Basins, Oregon. USGS Open File Report
    12. U.S. Army Corps of Engineers. 2013. Final Report Sustainable River Project Evaluation of E-Flow Implementation and Effects in the Willamette Basin using ResSim Modeling. Portland District, Portland, OR

    Publications

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    TitleSiteDate
    McKenzie - Environmental flows science summaryWillamette River2010
    McKenzie - Environmental flows workshop report Willamette River2010
    Willamette - Monitoring plan for environmental flowsWillamette River2012
    Santiam - Environmental streamflow assessmentWillamette River2012
    Santiam - Environmental flows workshop report Willamette River2012
    Willamette - Reservoir system modelingWillamette River2013
    Willamette - Considerations for environmental flowsWillamette River2015
    Willamette - Summary of implementation process Willamette River2015
    Willamette - Implementation of environmental flows NWPWillamette River2015
    Willamette - Implementation of environmental flows NWDWillamette River2015
    Willamette - Summary of environmental flow monitoringWillamette River2015
    Willamette - Integration of tributaries for basin-wide implementationWillamette River2017
    Willamette - Environmental flows science summaryWillamette River2007
    Willamette - Environmental flows workshop reportWillamette River2007
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