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Pacific Northwest Region
Boise, Idaho
Media Contact:
Diana Cross
(208) 378-5020

Released On: July 31, 2003

Arrowrock Reservoir to be Drawn Down
The Bureau of Reclamation will draw down the reservoir behind Arrowrock Dam in September for the third and final stage of the Arrowrock Dam Outlet Works Rehabilitation Project.

Arrowrock Dam, located on the Boise River about 13 miles east of Boise, Idaho, has been undergoing a three-year construction project aimed to replace antiquated valves with an improved system.

The reservoir elevation at Arrowrock is estimated to be at 3135 feet on July 31, and will be drawn down to elevation 3027 feet to install stoplogs in the trashrack structure, said Jerry Gregg, Reclamation Snake River Area Manager. In order to ensure a safe working environment and to keep the project on schedule, Arrowrock Reservoir elevation will be held to a reservoir elevation of 3027 feet from September 15, to March 1, 2004. Lucky Peak Reservoir must be held at or below an elevation of 2962 feet from October 15, to March 1, 2004.

These elevations are typical for the type of dry year this area has experienced this year, due to below-normal snow pack conditions and the above-normal July temperatures.

Construction for this third season will be on the upstream face of Arrowrock Dam. Actual construction will include removal of 10 Ensign valves, installation of bell mouth liners, installation of one bulkhead gate, installation of bulkhead guides, and completion of the control system. The contractor, Record Steel, began mobilizing equipment in August.

"Arrowrock Dam was the first dam designed by Reclamation to use the Ensign valve and is the last one to have these valves in operation," Gregg said. "We are replacing the older valves with a clamshell design that will improve overall efficiency, while ensuring the continued safe operation of the dam."

As the water recedes in both Arrowrock and Lucky Peak reservoirs this summer, Arrowrock Dam will be given a new lease on life that could not have been foreseen at the time of its completion in 1915.

"When this dam was first built, it was considered by many as a showpiece of modern technology," Gregg said. "These improvements today will ensure its productive life expectancy for future generations."

For more information please call John Tiedeman at (208) 378-5034.

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