Rainbows spawning with many in the tributaries from Holter Dam to Cascade, small mayflies and midges, streamers; river above Canyon Ferry Lake can have some great early streamer fishing for rainbows.
Water cold; numerous caddis and mayfly hatches but often nymph or streamer fishing best.
Water Temperature and level are excellent for dry fly fishing; lots of caddis, hoppers, tricos start in mid to late July.
Very predictable, heavy trico hatch which tapers off in late August; hopper; water sometimes quite warm in late August which creates slow fishing in the afternoons.
A wonderful time of year to be on the Missouri or for that matter, almost any stream in Montana; blue-winged olives, hoppers, and streamers.
The most dominant hatch are these two times of year are Montana River Guides. They are terrestrial but seem to migrate in the water en masse with a frenzy bordering on the humorous. Human angles are advised to be aware of aggressive and unpredictable nature of the organisms populating rivers in later fall and early spring in Montana.