Snake River
Flows from Jackson Lake Dam will be ramping down starting September 24th and will be at winter levels of approximately 325cfs on September 27th.
Every reach is fishing well with the lower reaches from Wilson Bridge down to Sheep Gulch taking the cake as usual in autumn. There is still a good smorgasbord of mayflies with Hecubas, infrequen PMDs, and mahoganies out each day and BWOs making a little bit of an appearance with cloud cover and precipitation. Leftover Claassenia should be out for another week or so and micro caddis can be found in a smattering fashion each day. Riffles, seams, and eddies are the primary water producing along with banks with slow to moderate currents.
Streamers are producing in the same waters as dry flies and dropper nymphs with moderately sized patterns that are dark or neutral in hue working best. Fish your baitfish imitations on floating lines or sinking tips in the INT to 3ips range. Moderate speed retrieves with an even cadence is the default presentation. Lean towards hesitations and faster retrieves if moderate line strips isn’t doing the trick.
South Fork
Flows from Palisades Reservoir currently stand at approximately 6,000cfs. Surface action is best with mayfly imitations – primarily BWO and mahogany duns – which are emerging most days from around noon until 5:30am when there is unstable weather in the cards. Riffles, seams, side channels, and eddies are prime targets. Mutant stones are waning fast but some leftovers are still out there. As such, it is still worthwhile to fish foam attractors, especially as part of a dry-dropper system. Action with this type of rigging has been producing from around 9am until 1:30pm, with some eats occurring well after this time period. Target banks, submerged structure, troughs, parallel drop-offs, and the inside current margins of riffles.
Streamers are working best on the lower reaches of the South Fork from around the Pine Creek confluence down to Lorenzo with production being consistent from 9am until dusk some days. Both large and moderately sized baitfish imitations are working equally well. The old adage “dark day dark fly, bright day bright fly” is appropriate at the moment. Fish your patterns on floating lines or sinking tips in the INT to 6ips range and, while moderate retrieves have been producing best, there is still some inconsistency, so vary line strip speeds up if there are lulls in action.
Flat Creek
Cooler weather has turned Flat Creek on in a big way. Mahogany duns and infequen PMDs are out in greater numbers and BWOs will be out when there with cloud cover and rain, as well as better numbers of mahoganies. Although we have had killing frosts recently, expect to see a smattering of grasshoppers for another couple weeks or so. Undercut banks, seams, eddies, and confluence riffles are the best waters to fish with just about any imitation. Fishing small streamers, dragonfly nymphs, and damsel nymphs have been producing better over the past week when fished along submerged structure, banks, and eddy seams.
Salt River
This is a favorite time of year to be on the Salt River with stunning foliage, lots of birdlife, moose browsing the banks, and trout eating eagerly in preparation for the coming winter. While terrestrials are still out, they are waning strong. Aquatic invertebrates, however, are abundant. BWOs and mahogany duns are prevalent each day with both emerging heavily on days with precipitation and cloud cover. You will also find a good number of micro caddis and midges. There is no prime time of day on the Salt right now, but if splitting hairs, 9:30am until 5pm seems to be the sweetspot. On the lower gradient reaches, target eddies and seams primarily. These waters will fish on higher gradient reaches, as will riffles, flats, and submerged structure.