Environmental study backs adding 117 feet to California dam

An environmental assessment by a California water agency and the Corps of Engineers supports adding 117 feet to the top of the 220-foot-tall San Vicente Dam, and accomplishing that task in a single construction project.

San Diego County Water Authority and the Corps identify the proposed action in a draft environmental impact statement of a plan to raise the dam’s height by 63 feet beyond that of an already approved 54-foot increase. (HNN 11/2/06) Adding the 63 feet would provide 100,000 acre-feet of carryover storage at San Vicente Reservoir.

�Because it would not be feasible or practicable to construct two separate raises of the dam due to issues such as cost, safety of the raised dam structure, and construction logistics, the two increases would be combined and constructed at the same time,� the document said.

Raising the height of the concrete gravity dam by 117 feet would provide additional capacity for emergency water storage and increase the reliability and flexibility of the regional water supply. The modification would increase the usable volume of the reservoir by up to 152,100 acre-feet. The proposed action calls for using roller-compacted concrete to increase the dam’s height.

The water agency released the draft EIS Aug. 24, setting in motion a 45-day public review period for comments ending Oct. 15. Public hearings to accept comments are planned Oct. 4 in Valley Center and Oct. 8 in Lakeside.

The draft EIS is available from the water authority’s Internet site, www.sdcwa.org. Comments can be submitted to Kelly Gage, Senior Water Resources Specialist, San Diego County Water Authority, 4677 Overland Ave., San Diego, CA 92123-1233; E-mail: kgage@sdcwa.org; Fax: (1) 858-268-7881.

Responses to comments will be included in a final EIS. If the water authority’s board of directors certifies the final document, the Corps will sign a record of decision authorizing the project.

In addition to its interest in raising the dam, San Diego Water Authority holds a preliminary permit from the Federal Energy Regulatory Commission to study the feasibility of developing a 570-MW San Vicente pumped-storage project (No. 12747). San Vicente Reservoir would form the project’s lower reservoir; the water authority is to consider several locations for the upper reservoir.

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