Hoppers are providing nearly all of the dry fly action on the Yellowstone River right now. Nymphers and streamer anglers are finding fish as well. The trout are definitely in the faster water so target riffles and faster banks. Deeper holes are producing some fish but because the faster water is the most oxygenated, trout are hanging there. Hatches have stalled out with really only some morning tricos and evening caddis providing most of the insect life. A few Drakes are being spotted on the river in Yellowstone National Park.
The second half of August on the Yellowstone is sort of a "secret season." The nights are cooling down enough that water temps are still providing a long window during the day for the trout to feed. The hopper bite is just starting and should improve in the coming weeks. If the trout are not committing to your hopper, try downsizing to a beetle or flying ant pattern. The best fishing is still early in the morning. Hot days have pushed trout into the fast water so avoid the long frog water slicks right now and look for the riffles--most trout are not holding in the faster, more oxygenated water. Avoid slow runs, sunny banks, and even slower banks. Trout on the Yellowstone want cool, flowing water.
Most of the hatches have subsided so dry fly anglers are prospecting a lot more than matching any hatches. There are still some nocturnal stones down low and dry fly fishing is good at dawn down there, with rubber legs underneath also producing some fish. There is some algae drifting on the lower river but it is still fishable. Nymphing tight bankside structure has been quite good but the trout are moving to riffles and runs. Streamer fishing has also been very, very good during low light levels as is nymphing large stonefly patterns and sculpins trailed by basic bead head nymphs.
Best Flies for the Yellowstone River Right Now:
Heneberry Hopper #8-12
Thunder thighs Hopper #8-12
Lil Spankers in various colors #12-18
Mega Prince #10-12
Pat's Rubberlegs #8-12
FKA prince #12-16
Foam run caddis #14-18
The Month Ahead:
The current conditions will hold out for the next few weeks. Trout will transition more to terrestrials on the surface and the standard nymphing patterns will hold out underneath. The most important factor is time of day and water temps. If hot days persist get up early and fish the fast water.
Long Term Fishing Forecast:
The Yellowstone should be a great option in the fall. As temperatures drop trout will move back into the slower slicks, eddies and glides and the small mayfly fishing will improve over baetis and the random drakes. October fishing is always solid on the stone to aggressive browns.