Upper Henry’s Fork
As of today we are seeing some cooler weather. We expect to see temperatures in the 50's the rest of the week. Unfortunately, it has not brought too many clouds yet. The cooler weather should bring on a good Mahogany Dun and Blue Wing Olive hatch. We have seen some of these bugs already, but it hasn’t been anything too strong yet.
Box Canyon is flowing fairly steady at 354 CFS. It is possible to float, but isn’t entirely recommended. Even with the lower flows the streamer fishing has still been quite good. We have seen good nymph fishing with a double nymph rig with zebra nymphs, hot wire princes, and flashback tungsten pheasant tails. A hopper/dropper still works in the lower sections of the float.
Flat Water
The Ranch is still fishing well enough. With the weather dropping in temperature we should start to see some really good hatches of Mahogany Duns and Blue Wing Olives. With the changing weather you will see some wind, so if you can get out there early you have a chance of catching a nice trout before the wind picks up. Not a lot of action in the evenings though. You’re better off to go have a nice dinner and get ready for the next morning of fishing.
Riverside to Ashton Reservoir
The Canyon below Riverside Campground down to Upper Mesa falls is a gorgeous section of river. The fish very rarely get hit down there and some of them surprise you with lightning fast runs. Granted there is not a lot of rod breaking fish down there. We very rarely get reports from this section because it is not that famous spring creek water like the Ranch. Hoppers and chubby chernobyls are still an option but the terrestrials are pretty much gone for the season but the fish have seen them recent enough that it is still an option. Nymphing is the way to go through this section and a pheasant tail or copper john would be the fly to use.
The Warm River to Ashton section of the river has been pretty good as of late. It involves a lot of nymph fishing as well as a good possibility of catching a nice brown trout on a streamer. A hopper/dropper pattern is still effective with throwing a chubby chernobyl trailed with a pheasant tail, zebra midge, or even a copper john along the banks and in the deeper holes and channels. There are quite a bit of white fish, but it is worth it to catch those when you land that big brown trout.
Ashton Tailwater
The lower end of the Henry’s Fork is a great stretch to fish in the fall. As the temperatures continue to drop we will see an increase in surface feeding fish. It seems that nymph fishing is the best way to fish right now. A chubby chernobyl is useful as an indicator. Don’t be surprised if you get a few hits on it. Streamer fishing and the Blue Wing Olive hatch are the best ways to go but be prepared with some Mahogany Duns. With work still in progress on the Ashton Dam there is still some flow fluctuation that kicks up a lot of weeds at certain times of the day. If possible watch the flow charts from the regional water information link on this page to predict the best time to avoid the weeds and such.
Madison River
A lot of nymph fishing right now on the Madison. The most consistent fishing would probably be to throw a streamer with a midge trailing it. Work the banks but not too hard. There are fish in the middle of the river too. Large stonefly nymphs and also some terrestrials are turning heads. Best option is to find holding water and pattern the river on places you have been caught up before.
South Fork of the Snake
Streamers are probably the best bet right now to catch a nice solid fish. A mutant stonefly is a great choice to get some work done along the banks. You can also hit the riffles with the adult stonefly along with a pink attractor of some sort. Maybe a pink PMD or a Yellow Sallie.
Yellowstone Park
With all the rivers opening up again in the park due to cooling weather, the fishing has been acceptable. Dark streamers are the thing to use at this time along with leech patterns, baetis parachutes, and pink bellied hoppers. Green and Gray Drakes are bringing up fish in the Lamar drainage areas. With the cooler mornings, being on the river before 11 AM wouldn't do anyone any good.
Tributaries
Fall River is a great river to fish during this transitional period. There is nothing of real size, but if you can’t help but get out on the river then put a hopper on the end of your line, trail it with a nymph (Pheasant Tail preferably) and throw behind any rock, and you’re sure to catch a fish. It may not be very big but if that’s all you want to do is catch fish then you should do just fine.
Warm River is another smaller river that won’t hold anything of real size, but you can catch plenty of fish on a parachute adams in the slower moving pockets and also in the riffles.
Lakes
The Henry's Lake County Dock and the State Park have seen some good action as of late. With this time of year comes the time for fish to “come home” to spawn. Henry’s Lake sees many cutthroat come up to spawn. Be ready with some nymphs and attractors. They will mostly hit the nymph but you will get them to occasionally roll on your attractor. The mouth of tributaries is great places to be to catch a real nice brook trout or hybrid.
Due to all the water needed in the valley, the Island Park Reservoir is pretty low. Leeches and other nymphs are recommended. A darker color or olive color damsel is a choice fly along with a san juan worm or even a rubberlegs.