The Bureau of Reclamation and Washington Department of Ecology have found proposals for two Yakima River Basin reservoirs to be technically viable, but not necessarily cost-effective, at least based on their preliminary review.
The agencies said Nov. 30 they are moving into the feasibility phase of a storage study focusing on a Black Rock Dam and reservoir and a Wymer Dam and reservoir, both of which could include hydropower plants. BuRec previously found both proposals sufficiently viable to merit further study. (HNN 8/31/06)
�Both alternatives have high construction and annual operating costs and benefit/cost ratios considerably below 1,� the latest report found.
However, the agencies said, the next feasibility phase will look more closely at the cost/benefit factors, in addition to implementing National Environmental Policy Act and Washington Environmental Policy Act processes.
�Further evaluation of the Black Rock and Wymer dams and reservoirs concepts, including options to the current alternatives, may show additional recreation, irrigation, fish, hydropower, or municipal benefits, and may, through downsizing of facilities or different operational scenarios, provide better benefit/cost ratios,� the report said.
The agencies have narrowed their options to the two dams, plus a no-action alternative. The Yakima River Basin Water Storage Feasibility Study, authorized by Congress in 2003, is to evaluate storage options to improve anadromous fish habitat, boost reliability of the 25-MW Yakima project’s water supply during dry years, and provide water to meet future municipal demand. The Yakima project has six storage reservoirs, five diversion dams, and the 12-MW Chandler and 12.9-MW Roza hydropower developments.
Possible hydropower plants outlined
The original Black Rock Dam and reservoir proposal called for storing up to 1.3 million acre-feet and could include as many as four new hydropower plants totaling more than 390 MW. However, in the new report, BuRec said Black Rock Alternative includes two or three potential hydropower facilities, two Black Rock plants of 23 MW and 38 MW and a 15- to 29.5-MW Sunnyside power plant. The report estimated two plants would generate a total of 249,000 megawatt-hours annually.
A proposal for Wymer Dam and reservoir would feature a 415-foot-tall dam, outlet works designed at the appraisal level to permit the future addition of a hydropower plant, and a 174,000-acre-foot off-stream reservoir. The reservoir would be filled by pumping water from the Yakima River. The possibility for hydro generation when releasing water from the reservoir back into the river will be a consideration in future work, the parties said.
The feasibility phase will include public scoping activities and more detailed evaluations of estimated costs, operations, economic and financial analyses, and environmental considerations. If the evaluations are favorable, BuRec will identify a preferred alternative that could be the basis for seeking congressional authorization.
Meetings will be held in 2007 to explain storage study progress and to gather information for the environmental review processes. When the new study phase is complete, results of the analyses will be presented in a draft feasibility report/environmental impact statement.
The latest study document, �Storage Study Team Technical Information and Hydrologic Analysis for Plan Formulation,� and other information, is available on the Internet at www.usbr.gov/pn/programs/storage_study/index.html.
