Fishing Report - September 19th, 2026

Upper Henrys Fork:

 Flows in Box Canyon are currently 836 CFS. 

Box Canyon has had several large changes in streamflow in the last several weeks, so the quality of the fishing has been swinging like a pendulum. For the time being, fishing a small streamer or focusing on nymphing with mic-drops, blowtorches, rubber-legs, and zebra midges can get the job done. Have some BWO’s and Mahogany Duns ready to go in case you find a pod of rising fish. Expect streamflow to continue to drop as we head into winter. 

Railroad Ranch has had its ups and downs in the last several weeks, but the Mahogany Duns are active and hatching mid mornings and early evenings, with a spattering of BWO’s. The Mahogany Last Chance Cripple is a go to for the end of September, and a small BWO sparkle flag, or vis-a-dun will help rise a big rainbow if the mayflies are active. It seems that the loose weeds we saw in early September are starting to clear out of the system, and hopefully make the fishing a little easier.

Lower Henrys Fork:

Flows Below Ashton Dam are currently 1090 CFS.

The flows on the Lower Henrys Fork are being bumped out of Ashton Reservoir. This is causing the water in the Ora-Chester stretch to be off color. Streamer fishing can be productive, and the word is that some larger lake-run Browns are staging in the mouth of the Henry’s Fork near Jump-Off. Rusty Spinners and Blue-Winged Olives are going to be the ticket when fish are rising, so have a few patterns in your fly-box. Nymphing is always effective in these stretches, so think small mayfly imitations, zebra midges, and incorporating small streamers to dead-drift in your rigs. 

South Fork of the Snake: 

Flows near Irwin are currently 4550 CFS.

Flows at Lorenzo are currently 2200 CFS.

The flows on the South Fork have consistently dropped, exposing lots of gravel bars and now making walking and wading an option for those on foot. If floating in a boat, there may be side-channels which are not safe to take, and there may be some gravel bars that you may have to get out and walk the boat across. Mahogany duns and BWO’s are available, but streamer fishing or nymphing has been the ticket for the most part. The guides here in the shop fish the duracell, black bullet quill, and rubberlegs quite a bit on the South Fork.

Madison River: 

Flows Below Hebgen currently 760 CFS

This time of year, the Brown trout on the Madison river start to get more active. Fish start moving upstream from Ennis Lake, Quake Lake, and Hebgen into the river to make their annual spawning migration. Expect to catch these larger fish mostly on streamer patterns, swung across the current or stripped close to cover, and jigged in deep runs. Nymphing deep with a prince nymph, leech, small dead-drifted sculpin, paired with a quill nymph can be productive if the streamer bite is slow. Blue-winged olives will hatch in the afternoons when the wind stays down.

Teton River:

Flows on the Upper Teton near Driggs are currently 305 CFS 

The Teton river has been fishing well with some grasshoppers and ants still active in the valley. Drakes, mahoganys, and olives are a great option to try to feed a rising fish in the upper river. Grey Drake mayflies are hatching in the Fox Creek region, bringing the largest fish in the river up to the surface this time of year, so if dry-fly fishing is your thing, this is probably the place to be. The Lower Teton river can be fished with a dry-dropper setup still, and never discount the effectiveness of a streamer run through this reach.

Yellowstone National Park:

The hoot owl restrictions on the Madison, Gibbon, and Firehole rivers were lifted earlier in September. Reports of drakes hatching on the Lamar river could be a good reason to explore around the east side of the park. The Yellowstone river slows down this time of year, but occasional small mayfly emergences can occur, and swinging a small streamer or a soft hackle can be productive. Lake-run fish are making their appearance in the Madison river. 

Lakes:

Henry's Lake-

The cooler temperatures have improved the fishing in Henry’s lake, but beware that the lower lake level has made it difficult to launch a boat. Small leech patterns, crystal buggers, scuds, and chironomids are productive. By targeting the mouths of inlet creeks such as Targee or Howard creek, you can catch a big brookie this time of year as they prepare to move upstream. 

Hebgen-

The gulpers have slowed down, although some dry-fly action will pick up from time to time as BWO’s and small mayflies make appearances occasionally on Quake lake and the Madison and Grayling arms. Significant numbers of Brown trout can be found stacked up in the channel of the Madison arm, and nymphing deep with an indicator or stripping leeches is probably the best course of action this time of year.