Henrys Fork Streamflows
Island Park Dam: 385 cfs
Ashton Dam: 1320 cfs
St. Anthony: 1170 cfs
Fall River: 459 cfs
These days in the middle of September mark for me the real beginning of fall fishing on the Henry’s Fork. The nights have been cooler for long enough to generate fall hatches with a little more regularity and brown trout are showing some signs of deepening hues in their coloring. This is the time of year that Henry’s Fork trout get busy maintenance feeding on small but regular food with the last period of water temperatures that are optimum for activity. Flows on the Fork are relatively low but stable, and clarity has been excellent throughout the system with the exception of just below Island Park Dam, where is some color to the water on the west side of the river.
The Box is fishing well but getting low, it’s a bit hard to get through here without leaving some gel coat on a few rocks and enduring a few bumps. Lower flows help to consolidate fish into prime holding lies, and make the rest of the river very fishable with dry/dropper rigs or streamers with floating lines. Indicator rigs, as ever, reign supreme and anglers will do best to focus on flies that represent the smaller flies of fall: midges, baetis, and mahoganies. Stoneflies are always present and worth trying. Most of the time anglers can get by with a single B shot or no shot and a tungsten beaded fly. Our favorite patterns in here at the moment are: PTs, R/L Tactical PT, Juju Baetis, Split Backs 14-18, Rubberlegs stonefly nymphs #8-12, red and brown Zebra midges in 14-18 and black Zebra midges in 18-20, as well as your favorite perdigons (Olive Hot Spot, Tungsten PMD, Spanish Bullet, Bullet Quill, red Jig Napoleons and Hollow Points, SH Perdigon 14-18) are all doing the trick out there. For streamers, we like olive and black BFEs, Bouface Leeches, and Zonkers in both copper and pearl. Lots of room for experimentation here as well.
Spinners, Mahoganies, Baetis, Tricos, Ants and Grasshoppers are all on the menu down here, varying with the trends of the weather, so it will be best to come prepared for it all. Sunny days will have hoppertunity in the afternoons, but those days are coming to a close and the window of efficacy is getting smaller. Baetis should become more regular in the coming weeks and mahoganies are present in greater numbers when clouds are involved. Best bets are for spinner falls in the mornings, maybe some ants mixed in, with a late morning and early afternoon of mahogany duns emerging. This should keep anglers looking for opportunity out there. Many days have sparse numbers of insects on the water and trout are a little more concentrated, so observation skills are of particular importance, and the skillset to get a fly to a fish that is rising infrequently is particularly useful. Widening your search is also a good idea, cover some ground to find a target if you find insects on the water. Remember to let them eat it when they try and set the hook with confidence! Weeds are present in the river and can make for an insurmountable obstacle, do your best to stay close to a fish that’s on the line and steer around potential issues. 5X has its limits and it will be put to the test, 6X has more restrictive limits and will at times be needed.
The sunny and warmer days of fall are the best kinds of days to venture into canyon country, no one wants to be stuck deep in this country with a fall storm overhead. On sunny days, the water is more easily read and anglers can fish more tactically with structures easily seen. On overcast days, the streamer bit may be better but plan on losing a few more flies along the way. Dry/Dropper rigs with a rubberlegs or large perdigon are a good choice, but streamers make a great option as well. Remember to bring extra clothing, boat handling skills and a rubber raft to get into these sections!
Warm River to Ashton
Fun fishing with good action can be found down here with dry/dropper rigs, indicator nymph rigs and a variety of streamer options. Fishing is typically good in about 2/3 of this float this time of year, weather and time of day will dictate which 2/3 produces so don’t be afraid to experiment for a portion of the float or enjoy the scenery when things slow down. Nymph selection should mirror that of the Box Canyon, with a focus on hopper patterns for the dry/droppers and a little more flexibility to experiment with small streamers or leeches under the indicator. For stripping streamers, now is a fun time to play with intermediate lines, sink tips and tight line presentations.
Below Ashton Dam
We are starting to see some good fishing down here, with cloudy days presenting more opportunity than sunny ones. Plan on fishing wet in the morning and hoping for some dry fly activity in the afternoons. Baetis have been present and mahoganies are on the horizon, some caddis may appear from time to time as well. In the absence of other bugs, a faithful approach with hoppers will typically result in a handful of good opportunities. Streamers are a great option until noon on a sunny day and all day long if overcast conditions prevail. Nymph fishing with lightly weighted rigs are producing as well.
Have fun out there and good luck!