New Boise River system feasibility study launched

Media Contact: Annette Ross, (208) 378-5322,
Cynthia Clark, (208) 287-4817,

For Release: October 30, 2017

BOISE, Idaho – A new Boise River system feasibility study has been launched to investigate the possibility of increasing surface water storage in the Boise River watershed by raising the height of up to three dams on the Boise River.

The Bureau of Reclamation and the Idaho Water Resource Board (IWRB) are working together on options to increase water storage capacity at Arrowrock, Anderson Ranch, and/or Lucky Peak dams.

Additional water storage would enhance long-term water supply for critical irrigation, domestic, industrial, and municipal needs in the Boise area, while continuing to meet endangered species and power generation needs. Additionally, this effort could potentially provide greater flood risk protection. The additional water storage could provide a greater capacity to store more runoff in high water years similar to 2017.

“I appreciate the state’s commitment to partnering with Reclamation in exploring new water storage opportunities for the Treasure Valley,” said Roland Springer, Reclamation’s Snake River Area Manager. “This work will be an important part of the region’s sustainability for decades to come.”

The study will evaluate potential raises of the following dams:

• Reclamation’s Arrowrock Dam (raise of about ten feet/20,000 acre feet)

• Reclamation’s Anderson Ranch Dam (raise of about six feet/29,000 acre feet) and/or

• U.S. Army Corps of Engineers’ (Corps) Lucky Peak Dam (raise of about four feet/10,000 acre feet)

The initial alternatives selected for the study are based on Reclamation’s appraisal-level July 2006 Assessment Report recommendation to potentially expand storage at those dams and other locations in the Boise River system, as well as water storage analyses performed by the Corps in 2010 and 2016.

“The Treasure Valley is experiencing significant growth and may be unable to support this new demand with ground water alone. Supporting long-term water needs with available surface water is an important part of planning for the future in the Treasure Valley,” said Roger Chase, Chairman of the IWRB.

In 2016, the Corps terminated a feasibility study focused on raising Arrowrock Dam for increased flood control storage and water-supply benefits. Termination of that study was due to a low cost-benefit ratio for the flood control function and resulted in renewed state and local interest in a study by Reclamation focused on water supply. Reclamation plans to use relevant information from the Corps’ study to reduce study costs and accelerate the study process.

The estimated cost for the feasibility study is $6M, which includes a non-federal, cost-share contribution of $3M, which IWRB has committed to fund. IWRB was created by the Idaho Legislature and is responsible for the formulation and implementation of a state water plan, finance of water projects, and the operation of programs that support sustainable management of Idaho’s water resources.

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