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Risk Assessments

The US Fish and Wildlife Service assesses the risk of species using an "ecological risk" approach. High-risk species are species for which particular caution is needed to reduce the risk of invasive problems to ecosystems of the United States. Great caution is needed when trading or acquiring high-risk species, particularly in parts of the United States where the environmental conditions in the wild have been identified as suitable for the survival of the high-risk species of interest. If the species you want is categorized as high risk, then please consider choosing an alternative species from the low-risk category. If new species are being considered for trade, then we do not recommend high-risk species.

For more information on how ERSSs are prepared, go to Ecological Risk Screening Summaries.

Vulnerability Assessments

 Vulnerability assessments [1] itemize and inspect all hydropower facility structures and components that come into contact with raw water, and make an informed judgment on the degree to which dreissenid mussels will impair the performance of the structures and components.[2]


A facility assessment process usually requires considerable time for planning and coordination, background research, site visits, evaluation of data and preparation of a report.[3] It is likely that a team approach with two or three people is most effective at carrying out the assessment with at least one person with operational knowledge/experience of the specific facility. The assessment team lead should become familiar with general mussel characteristics and behavior or possibly have a support person familiar with mussels as part of the assessment team.


The specific risks and problems that a particular facility will have with the dreissenids will depend on:

  • The size of the dreissenid population in the area – actual/anticipated.

  • How the raw water gets into the facility.

  • Any processes to treat or transform the water for various facility applications.

  • The routing of all piping branches and location of components and equipment, including materials of construction.

  • The operating envelope of the various water systems (such as maximum and minimum flow rates, frequency of operation, temperature ranges).

[1] U.S. Department of the Interior Bureau of Reclamation, May 2009, Facility Vulnerability Assessment Template, Invasive Quagga and Zebra Mussels. Prepared for Reclamation by: RNT Consulting Inc., 823 County Road 35, Picton, Ontario, Canada K0K 2T0, 26pp.

[2] Prescott, T. Vulnerability Assessment of Zebra and Quagga Mussels on Facilities from Intake to Discharge. RNT Consulting, Inc. (PowerPoint Presentation).

[3] U.S. Department of the Interior Bureau of Reclamation, May 2009, Facility Vulnerability Assessment Template, Invasive Quagga and Zebra Mussels. Prepared for Reclamation by: RNT Consulting Inc., 823 County Road 35, Picton, Ontario, Canada K0K 2T0, 26pp.

Status of Vulnerability Assessments in the CRB

The map and list below illustrates vulnerability assessments that have been completed on hydropower facilities in the CRB (green pushpins) and vulnerability assessments planned for completion (yellow stickpins). Click on the pushpins and stickpins for the names of the hydropower facilities. Click on the "view larger map" in the lower lefthand corner of the map to view the online version of the map as well as all hydropower facilities in the CRB.

Columbia River

Bonneville Dam (US Army Corps of Engineers)

Dalles Dam (US Army Corps of Engineers)

John Day Dam (US Army Corps of Engineers)

McNary Dam (US Army Corps of Engineers)


Dworshak Dam (US Army Corps of Engineers)

Chief Joseph Dam (US Army Corps of Engineers)

Ice Harbor Dam (US Army Corps of Engineers)

Lower Monumental Dam (US Army Corps of Engineers)

Little Goose Dam (US Army Corps of Engineers)

Lower Granite Dam (US Army Corps of Engineers)

Mud Mountain (US Army Corps of Engineers)

Howard Hanson (US Army Corps of Engineers)

Grand Coulee Dam (US Bureau of Reclamation)

Banks Lake (Dry Falls and North Dams) (US Bureau of Reclamation)

Rocky Reach (Chelan PUD)

Rock Island (Chelan PUD)



Owyhee Dam (Bureau of Reclamation)


Albeni Falls Dam (US Army Corps of Engineers)

Libby Dam (US Army Corps of Engineers)

Hells Canyon (Idaho Power)

Oxbow Dam (Idaho Power)

Swan Falls (Idaho Power)

CJ Strike (Idaho Power)

Cascade Dam (Bureau of Reclamation)

Arrowrock Dam (Bureau of Reclamation)

Ririe Dam (Bureau of Reclamation)

Palisades Dam (Bureau of Reclamation)

American Falls (Bureau of Reclamation)

Milner Dam (Milner Dam, Inc.)


Jackson Lake Dam (Bureau of Reclamation)

British Columbia

Waneta Dam (BC Hydro)

Waneta Expansion (BC Hydro)

Arrow Lakes Generating Station (BC Hydro)

Brilliant Expansion (Columbia Power Corp)

Corra Lim Dam (Fortis BC)

Hugh Keenleyside Dam (Fortis BC)

You will also note that we are displaying additional layers of data in the new online Vulnerability Assessment mapping tool. 

This dataset shows the locations of facilities used for fisheries management or passage within the Columbia River basin.  For the purposes of this dataset, a 'fish facility' is a fixed or semi-fixed location where fish are managed, counted or passed, and generally where there is at least one data record in a Pacific States Marine Fisheries Commission (PSMFC) database.  Not all dams fit neatly within this definition, but are included because they are a significant factor in fish distribution.  A primary objective of this dataset is to link PSMFC's Columbia Basin fish data programs through a common location framework, while eliminating the redundancy of location data being mapped and managed by the individual programs.  While the facility location data will be managed by PSMFC GIS Center as a single dataset, facilities can be separated and published into multiple map layers based on facility type or other attributes.


Sources for these point data came primarily from programs within PSMFC, including StreamNetPIT Tag Information System (PTAGIS), and the Regional Mark Processing Center (RMPC), and their various state and federal partners.  Locations have been checked and in some cases modified to more closely match available imagery or regional hydrography, as appropriate.  Inclusion in the dataset or depiction in the map application does not mean that the facility is currently active.


Basic types of fish facilities currently include:

·       Hatcheries, and acclimation / release sites

·       Dams (categorized further for display purposes)

·       Fish traps & collection facilities (including screw traps, weirs traps, etc.)

·       Fish passage facilities (including fish ladders and juvenile fish bypasses)

·       PTAGIS instream remote detection sites*

*Note that not all PTAGIS sites are depicted in this dataset. We strive for accuracy and completeness, but expect that improvements to the dataset can be made.  If you have any corrections, additions, suggestions, or concerns, please contact

Columbia River Basin Vulnerability Assessment Team

Lisa DeBruyckere, Creative Resource Strategies, LLC (Coordinator)
Arnie Aspelund, Puget Sound Energy

Dave Beedle, Seattle City Light

Sarah Branum, BPA
Chris Brueske, Whatcom County

Lori Campbell, PGN
Tom Dresser, Public Utility No. 2 of Grant County, WA
Todd Gatewood, GE Power and Water
Micah Goo, Centralia City and Light

Maureen Grainger, FortisBC

Nate Hall, Avista
Michele Hanson, USACE
Doug Johnson, BC Hydro
Keith Kirkendall, NOAA
Chas Kyger, Douglas County PUD

Scott Lindsay, Northwest Public Power Association

Nate Hall, Avista

Heidi McMaster, USBR
Stephen Phillips, PSMFC
Andrew Talabere, EWEB
Michael Stephenson, Idaho Power
Andrew Talabere, EWEB
Michael Hounjet, Columbia Power

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