Time to think terrestrial patterns on streams and shorelines of lakes. That thought applies to almost all Park waters. One exception is the big stoneflies moving up through the Yellowstone River canyon above Gardner. A good way to enjoy fish responding to them is to take a four-mile walk to the river down Blacktail Deer Creek. It’s a big river here, nearly the size of the South Fork reach of the Snake River, and you will have to commit to either side.
Fish deep and early or late in the day on all irrigation reservoirs. Some of better still water fishing is on the west end of Island Park Reservoir around Grizzly Springs and Trude Bay. Try bloodworm patterns under an indicator. You will have to find the taking depth.
Riffle fishing has not reached its peak on the river. Best riffle fishing method these days is to use dry-dropper combination. Otherwise try hitting the banks with your favorite chernobyl type big enough to support a small bead head dropper. This technique has been working very well on the upper river. Be ready to break out streamers at the end of the day.
From a fishing standpoint we have been fortunate to have stable flows below Palisades Dam for several weeks. According to US Bureau of Reclamation it is likely that flow out of Palisades could remain constant through August to replenish water in American Falls Reservoir and to maintain flows for irrigation just above the reservoir. When water in the reservoir is at a comfortable volume to cover irrigation and demand for it just above the reservoir slows, look for flow out of Palisades to drop. We will be in contact with US Bureau of Reclamation to keep on top of flows in the South Fork.
Hoppers are becoming a significant food item for trout in most streams now. Be sure to have patterns for them wherever you fish. On higher gradient small streams remember that traditional attractor patterns are as effective as ever and that some are meant to imitate terrestrial insects.
Only significant change here is that flow out of Henry’s Lake has been dropped from 100 cfs to 71 cfs. This drop in flow means especially larger fish in the Outlet section will begin moving downstream to find cooler water and more cover. So the best fishing here is ending for the year. Look for further drops in flow as we move through summer. Elsewhere along the river start gearing up for terrestrial patterns being the most effective during daytime hours.
Not much change since our 7-17 report. Look for best fishing to happen during days when thundershowers start to build.
Draw down is warming water in our irrigation reservoirs. With temperatures near the surface as high as the low seventies in degrees F. one must fish deep for any action. Be ready to put those small midge pupa patterns deep below your indicator.
On all of these terrestrial patterns are working very well. Other than midge and evening caddis swarms, these are the most numerous insects available to trout. Late morning and late afternoon to evening hours are best times to be on most of these.
Because flow out of Mackay Dam is near 500cfs, wading in the river below is still a bit tough.
No big change since the 7-17 report. Creek mouths provide best action, but expect crowds.