Henry's Fork still offers some good top-water fishing if you venture there early in the day. PMDs are on the water everywhere, with activity peaks from mid-morning to midafternoon. Major evening caddis activity continues up and down the river. Box Canyon, a bit tough on wading, is in ideal flow for drift boating but will attract recreational boaters through Labor Day weekend. Dry-dropper rigs, large nymph and streamer patterns are working there.

Overcast conditions offer the best fishing days from Last Chance through the Harriman State Park section. PMD, flav (including spinners) and caddis life cycle patterns are bringing trout up during mornings. Stealth, long fine leaders and precise casts are required for successful fishing. Larger trout are more likely to approach exhaustion when very fine leaders are used in the warm daytime water. Please play any trout no longer than necessary and do all you can to revive it enough to swim away on release — we want those big guys back in the gene pool! Aquatic vegetation is becoming dense enough to make landing large fish a task.

Consider that the warmest water temperatures take place from 3 PM to midnight on the entire river. Terrestrial insects are beginning to appear up and down the river. From Warm River downstream, summer heat makes early and late in the day the best time to fish. Dry-dropper rigs and PMD life cycle patterns work well throughout the lower river, but terrestrial insect patterns — from ants and beetles to small hoppers — fished tight to banks are becoming very effective. Try dead-drifting that hopper pattern with occasional twitches in front of vegetated banks.

Flow at Box Canyon is about 1,370 cfs, below Ashton Dam is about 1,720 cfs, and about 1,240 cfs at St. Anthony.