A new Boise River system feasibility study has been launched to look into 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, officials said.
The Bureau of Reclamation and the Idaho Water Resource Board are working on options to increase water storage capacity at the Arrowrock, Anderson Ranch, and/or Lucky Peak dams.
Experts say additional water storage would enhance long-term water supply for irrigation, domestic, industrial, and municipal needs in the Boise area, while continuing to meet endangered species and power generation needs.
The effort could also 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, they said.
“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 Bureau of Reclamation’s Arrowrock Dam (a raise of about ten feet/20,000 acre feet)
•the Bureau of Reclamation’s Anderson Ranch Dam (a raise of about six feet/29,000 acre feet) and/or
•the U.S. Army Corps of Engineers’ Lucky Peak Dam (a raise of about four feet/10,000 acre feet)
“The Treasure Valley is experiencing significant growth and may be unable to support this new demand with groundwater 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. The termination 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, officials explained.
The study would cost some $6 million, including a non-federal, cost-share contribution of $3 million, which the Idaho Water Resource Board has committed to fund.
The Board 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.