No drop in flow here but mayfly activity on the lower river is similar (good) to that of the South Fork. Tiny BWOs (pseudocloeon edmunsi) are coming out on the lower river in numbers good enough to interest trout into near surface feeding. That means presenting very small (#18-22) life cycle patterns. Good luck if you tie into a trophy individual using one of these patterns!
Flying ants have arrived along the upper river, so add these to the grasshopper abundance, and terrestrial insect patterns of these should accompany your visit to this part of the river. Mayflies activity is reduced to a spotty trico emergence with some speckled duns thrown in. Caddis are still active here, but seem to be less in favor than especially ants according to resident trout (and whitefish). As always occurs this time of year, extensive weed beds put some limits on wet fly fishing and make escape havens for large hooked trout (and whitefish).
Cooler mornings and less daylight means we are heading in the direction of the lower river to begin “perking up” with respect to offering better fishing. Look for the small BWO activity to become important in a few weeks and streamer fishing success to begin ramping up.
No big change here since our last report. Terrestrial insects “rule the roost” with respect to attracting trout just about everywhere on the river. Flying ants and trico spinners are coming closer to be available in important numbers up and down the river. It will take a lot of cooling off and some weeks before the late season BWO hatch begins.
Significant flying ant and trico activities are just around the corner along the upper river. For now concentrate on presenting terrestrial patterns during daytime, then switch to caddis life cycle in the evening. Try hopper- bead head dropper combos in Box Canyon, but be aware of recreational floaters there during mid-day. The same patterns apply to the warmed up lower river: those for terrestrial insects with and without droppers during daytime, those for caddis ( and streamers) during evening hours.
Hoppers, caddis and rusty spinners; patterns imitating these provide the best chance for dry fly action up and down the river. Responses to these will be slower on the lower river during daytime, so try them during early morning or evening if you are considering fishing that part of the river.
At almost every location on the river rusty spinners in the AM, caddis during evenings will get you into action. Hoppers and other terrestrial insects make for action along the upper river, but mid-day hours on the lower river are a good time for a siesta.
Wading wet is comfortable in the lower river. Fishing there is fair early mornings (a few spinners) and evenings (caddis activity). The big early summer mayfly emergences are pretty much done on the upper river. Now it is time to of think terrestrial insects, PM caddis and a few speckled duns.
The lower river, especially below Ashton Dam, is comfortable enough for swimming. For the river in the Island Park area it is soon time to break out terrestrial insect patterns. Flows in the river in the Flat Ranch Preserve are beginning to drop, so look for fish there to begin moving to the cooler river below. The flow there is dominated by the Big Springs outflow, so should be quite hospitable.
Lower river is warm enough to minimize fishing success. Not many boats around. Early AM with spinners and streamers or evenings with the same plus caddis life cycle patterns may bring some interest.