Officials say Washington’s most promising site for a Columbia River Basin off-channel reservoir, at Crab Creek, could support a pumped-storage project of up to 392 MW.
The Bureau of Reclamation and Washington’s Department of Ecology completed an appraisal level study in June, seeking at least one reservoir to improve water supply: for irrigation; for anadromous fish habitat by supplementing Columbia River flows; and for future water consumption needs.
They investigated four off-channel sites — Crab Creek, Sand Hollow, Foster Creek, and Hawk Creek -ï¿½ to determine if one or more should be recommended for investigation at a feasibility level of detail.
The appraisal study found the Crab Creek site to be a potentially viable reservoir location, preferable to either Sand Hollow or Hawk Creek, based on cost and technical feasibility. However, it added, construction at Crab Creek could have significant environmental, socioeconomic, and cultural effects that would need thorough evaluation.
The Crab Creek site is east of the Columbia River between Wanapum and Priest Rapids dams, the developments of Grant County Public Utility District’s 1,893-MW Priest Rapids hydroelectric project. (HNN 6/8/07)
The study was preceded by a review of reports and documents on 21 potential storage sites near the mainstem Columbia River. Eleven sites originally were considered for further review. (HNN 2/23/06) Of those, five were eliminated because they: were located too far downstream to be integrated into the operation of BuRec’s Columbia Basin project; were too small; or represented a high risk of failure or excessive leakage.
Two additional sites on the Colville Reservation were dropped at the request of the Confederated Tribes of the Colville Reservation. As a result, the study looked at Crab Creek and Sand Hollow in Grant County, Foster Coulee in Douglas County, and Hawk Creek in Lincoln County. Foster Coulee was eliminated early in the study due to concerns over geologic stability and failure risk.
Scenarios propose 69-MW, 216-MW, 392-MW projects
The study looked at three scenarios for Crab Creek. The first scenario would feature a 137-foot-tall dam and a 69-MW powerhouse, storing 1 million acre-feet. The second scenario would feature a 199-foot-tall dam and a 216-MW powerhouse, storing 2 million acre-feet. The third scenario would feature a 236-foot-tall dam and 392-MW powerhouse, storing 3 million acre-feet.
Transmission facilities would be required to deliver power to the large reversible pump-turbines that would lift water from the Columbia River into Crab Creek reservoir. The study said the same transmission facilities would deliver electricity generated when water is released through the pump-turbines back into the Columbia River.
Appraisal level studies are brief preliminary investigations to determine the desirability of proceeding to a more detailed feasibility study. They generally rely on existing information to develop plans for meeting current and projected needs and for solving problems in planning areas.
BuRec, Ecology, and Columbia Basin irrigation districts will review the study report and consult with stakeholders, agencies, and other entities. Based upon that review and consultation, officials are to decide whether to seek congressional authorization and funding for a feasibility study and environmental impact statement of the Crab Creek site.
The appraisal level study did not look at water storage for Washington’s Yakima Valley, where a Black Rock Dam and reservoir and a Wymer Dam and reservoir are under consideration. Both storage projects could include hydropower plants. (HNN 1/15/07)