This morning flow out of Island Park Dam was increased by 900 cfs to 2000 cfs to test low-head hydro turbines at Chester Dam. Flow will remain at 2000 cfs for two-three days, then at least by Friday, July 24th, should be returned to around 1000 cfs. Because of this near doubling in flow, take caution while wading and consider that there will be some reaction from fish. By this coming weekend, fishing success should return to what it was last weekend. By then consider that hopper and other terrestrial insect patterns are going to be increasingly important occupants in your fly box anywhere along the river.
If you wish to get away from the effects of the flow increase, consider trying the river (Henry’s Lake Outlet to some folks) in the Flat Ranch Preserve. Flow out of Henry’s Lake Dam is nearly 100 cfs,and cooling effects on shallow, slow running water through nighttime heat radiation help fish stay active. Therefore morning spinner falls can bring good responses from them and terrestrial insect activity should interest them well into daytime hours.