The lower Boise River flows approximately 64 miles through Ada and Canyon counties, from Lucky Peak Dam to its confluence with the Snake River. This area has experienced rapid growth over the past several decades; land use is changing from agricultural to urban.

Three federal dams upstream of the city of Boise are jointly operated for flood control and irrigation by the Corps and Bureau of Reclamation. The reservoir system provides significant flood protection because the Corps is able to reduce the 100-year, natural water discharge from 41,000 cfs to 16,600 cfs. However, even at this reduced level, the levees along the Boise River do not provide publicly acceptable levels of protection.

Localized minor flood damages occur with flows of 4,500 cfs; however, damages to structures and infrastructure begin when flows exceed 6,500 cfs. Boise River flood stage is 7,000 cfs at the Glenwood Bridge. Significant development in the river corridor and population growth results in renewed interest in flood control and water supply. There is also increasing interest in environmental restoration, keeping habitat preservation in mind when considering aesthetics and recreation along the Boise River.

The Idaho Water Resource Board (IWRB) initiated the Treasure Valley Comprehensive Aquifer Management Plan (CAMP) to address the next 50 years of water supply and demand for the Lower Boise River basin. The Corps developed a two-phased feasibility study approach for the Boise River General Investigation (GI) to assist the IWRB with its regional planning effort. The Boise River GI - Interim Feasibility Study will provide technical information about water storage potential in the Treasure Valley CAMP.

The evaluation of water storage will build upon the Bureau of Reclamation’s Boise/Payette Water Storage Assessment Study completed in July 2006.

The Interim Feasibility Study will

1) evaluate and document the existing conditions on the Boise River,
2) evaluate public safety issues related to flooding,
3) conduct detailed analysis of storage opportunities in the Boise River Basin, and
4) develop a plan to complete the rest of the feasibility study.

A draft report documenting study analysis will be prepared and made available for public review and comment in 2012. Completion of phase 1 of the feasibility study is anticipated in 2013.

For more information or to be placed on a mailing list to receive updates on the study, please contact Boise.Office@usace.army.mil