Columbia River Basin Storage Options - Columbia River Mainstem

The Department of Ecology (Ecology) is looking at the feasibility of building new water storage facilities along the Columbia River. By law, storage funded from the Columbia River Basin Water Supply Development Account shall be allocated two thirds for out-of-stream (e.g. agriculture, industrial, municipal) uses and one third will remain instream to enhance river flows.

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At a Glance

Columbia River Mainstem

The U.S. Bureau of Reclamation and the Department of Ecology have completed an appraisal level study of potential Columbia River mainstem off-channel storage sites. Appraisal studies are brief preliminary investigations used to determine the desirability of proceeding to a more detailed feasibility study. Appraisal studies generally rely on existing data and information to develop plans for meeting current and projected needs and for solving problems in a planning area.

Appraisal Evaluation of Columbia River Mainstem Off-Channel Storage Options Report

Mainstem off-channel storage appraisal study

The mainstem off-channel storage appraisal study was conducted as element of a Memorandum of Understanding (MOU) entered into in 2004 by the Bureau of Reclamation (Reclamation), the State of Washington, and the three Columbia Basin irrigation districts. The MOU is intended to promote improved water management of the Columbia River and Columbia Basin. As part of Sections 6 of the MOU, Reclamation and the State committed to conducting an appraisal level study of potential Columbia River mainstem off-channel storage sites.

The MOU further commits the state and the participating irrigation districts to request federal legislation to authorize and fund a mainstem storage program, including feasibility studies by Reclamation of proposed storage projects, if warranted based on results of the appraisal study. Feasibility studies involve generation and collection of detailed, site specific data concerning a project and reasonable alternatives. Feasibility studies are usually integrated with National Environmental Policy Act (NEPA) compliance, potentially including development of a NEPA EIS.

The appraisal study was preceded by a review of existing reports and documents regarding 21 potential storage sites near the Columbia River mainstem. Eleven sites were originally considered for further review.  Of the 11 sites, five sites were eliminated from consideration because they:

  • Were located too far downstream in the Columbia River to be integrated into the operation of Reclamation’s Columbia Basin Project,
  • Were too small, or
  • Represented a high risk of failure or excessive leakage.

Two additional sites located on the Colville Reservation were dropped from further consideration at the request of the Confederation Tribes of the Colville Reservation. As a result, the appraisal study was initiated with four potential sites: Foster Coulee in Douglas County, Hawk Creek in Lincoln County, and Sand Hollow and Crab Creek in Grant County. Foster Coulee was eliminated from consideration early in the study due to concerns over geologic stability and failure risk.

The appraisal study evaluated whether any of the sites appear capable of safely providing a minimum of 1,000,000 acre-feet of active storage. It also included a preliminary assessment of the potential impacts of reservoir development on the built and natural environment, including impacts to cultural resources.

The appraisal study determined that the Crab Creek site represents a potentially viable reservoir location. This site appears to be preferable to the Hawk Creek site based on both cost and technical feasibility criteria.  However, construction of a facility at the lower Crab Creek site would have potential significant environmental, socioeconomic, and cultural impacts that would need to be thoroughly evaluated in an EIS.

Crab Creek


Hawk Creek

Crab Creek – A site in western Grant County on a tributary to Priest Rapids Lake with potential active storage capacity of 2,300,000 acre-feet.
Hawk Creek - A site in northern Lincoln County on a tributary to Lake Roosevelt with potential active reservoir capacity of 1,400,000 acre-feet.

Ecology, Reclamation, and the Columbia Basin irrigation districts will review the study report and will consult with stakeholders, agencies, and entities, including the Columbia River Basin Policy Advisory Group, prior to decision making as to whether to request from Congress authorization and funding for a feasibility study and EIS.

Columbia River Mainstem Storage Options, Washington Off-Channel Storage Assessment Pre-Appraisal Report - December 2005 - Prepared for Washington State Department of Ecology and U.S. Bureau of Reclamation by MWH (Large File 7.4 MB pdf)

Why the Black Rock Reservoir is not evaluated in the Columbia River Mainstem Storage Options Off-Channel Assessment Pre-Appraisal Report (90.5kb pdf)