The Bureau of Reclamation and the U.S. Corps of Engineers manage three upstream dams on the Boise River drainage. The dams provide irrigation water storage and flood control. The need for water storage and space reserves for flood control is a balancing exercise based upon snow pack levels, historic runoff records of snow pack, and reservoir level conditions.
Attempts are made to keep flows below 6500 cubic feet per second (cfs) in the spring. However, this flow rate is generally exceeded about once every five years. For the Boise River, 7000 cfs is considered to be at the lower level flood stage; 16600 cfs is considered a 100-year flood event.