Montana Fish, Wildlife & Parks, along with partners from the East Bench Joint Board and the U.S. Bureau of Reclamation, will conduct a flushing flow out of Clark Canyon Reservoir beginning Friday, May 1, to move sediment deposited in the Beaverhead River, helping restore and maintain aquatic habitat.
River users should be aware that the flushing flow regime will be released May 1 through May 3. Beaverhead River discharges will increase from overwinter releases of 90 cubic feet per second (cfs) to 600 cfs on May 1. Flows will be reduced to meet irrigation season demands over the next two days.
The Beaverhead River is a renowned trout fishery; however, trout populations have declined by as much as 50 percent immediately following large sediment deposits from Clark Canyon Creek, and habitat recovery has been slow. These events occur randomly after large rain or snowstorms that coincide with low flow releases from the reservoir.
After studies were conducted to determine the cause of these events and what it would take to avoid negative impacts on fish populations, the partner agencies decided to store 2,100 acre feet of water and conduct a flushing flow from Clark Canyon Reservoir to move sediment and maintain habitat health.
The first flushing flow was released in 2017, and it was effective in clearing sediment and improving river health.
The Beaverhead River supports 2,000 to 3,000 trout per mile in its upper reach. The river sees about 40,000 angler days per year, and recreationists who come to enjoy the river spend several million dollars locally each year.