Henry’s Fork, May 16th, 2023

Forget about fishing the Warm River to Ashton section for a while. Robinson Creek and even Warm River (right now a run-off stream thanks to Island Park snow pack) are putting in cold, discolored water. Nevertheless, big stonefly nymphs are moving, and as we close in on the end of the month will be out and hatching along the lower river. Mother’s Day caddis remain along the lower river and best to encounter fish feeding on them is below Ashton Dam. Avoid using the Ora Bridge boat launch to minimize road damage until water level in the gravel pit drops.

Headlines from Dr. Rob Van Kirk’s Water Supply Report filed yesterday for the Henry’s Fork Drainage.

• Temperatures and snowmelt were well above average yesterday; 71% of this year’s peak snowpack remains, compared with 66% on average.
• Natural streamflow is 140% of average.
• At an average outflow of 1195 cfs, Island Park Reservoir gained 2000 ac-ft yesterday and is 94% full, compared with 96% full on average.
• Although 95% full physically, the three reservoirs in the Henry’s Fork watershed are 57% full on paper, as the American Falls 1921 right is still being filled.