Flow out of Mackay Dam has been constant at around 180 cfs for at least a week. So wading is relatively easy and water conditions stable. Weather features crisp, cool AMs with some frost and sunny, bright afternoons. BWOs, midges, a few remaining hoppers and other terrestrial insects make top water fishing attractive during afternoons. Certainly presenting traditional nymph patterns and small woolly bugger and rubber leg patterns will be effective any time of day.
From the Henry’s Fork confluence to American Falls Reservoir the Snake River is flowing at or below its normal amount because irrigation season is over and water storage routines are starting in upstream reservoirs. Thus both boating and walk-in-wade opportunities on the river are more attractive and numerous than in past months.
.It is also the time of the season when brown trout begin migrating to spawning areas. Being aggressive during the migration, they make good sport for fly fishers presenting streamer patterns. Choose the heads and tails of deep water and along banks with good vegetation and deep water to concentrate your presentations, Avoid spawning areas. With our unusually sunny, warm weather, the best time to encounter these browns is under low light conditions because they settle in deep water for overhead cover during daytime. So the best chance for encounters is during early morning or evenings hours when the sun is off the water. The shortening days make being on the water more convenient, so consider a “pre-breakfast” or “pre-dinner” visit to the river.
Sunny, comfortable days make afternoons enjoyable times to be almost anywhere on the river. BWOs, mahogany and midge activity will be somewhat muted because of bright skies, so evenings will offer best times for top water fishing.
Headlines:From Dr. Rob Van Kirk’s Henry’s Fork drainage water status report of yesterday
Warm, dry weather continues, with no end in sight.
Natural flow is 74% of average, and diversion is 110% of average.
At an average outflow of around 280 cfs, Island Park Reservoir gained 100 ac-ft yesterday and is 46% full, compared with 48% full on average.
Next week during October 11th & 12th, IDF&G will be doing an electroshocking survey from Warm River to Ashton. The purpose is to study the Rocky Mountain whitefish health status and population. Until some unsettled weather moves in no change in fishing strategy should take place. Look for BWO, mahogany, and caddis activities peaking during PMs and during day time warmth hopper and ant patterns being effective. Streamers presented around first light, during evenings, and any low light conditions will be increasingly effective for migrating brown trout throughout the lower river.
The Idaho Department of Environmental Quality has determined that cyanobacteria (blue-green algae) have released toxins at dangerous concentrations around the lake. At these concentrations they can be toxic to animals including dogs and livestock. Water contaminated with these toxins can also be poisonous to humans. Thus consider washing hands with clean water after such actions as releasing fish, handling lines or nets, getting out of wading gear and before eating, all after being in the lake.
Fishing success remains slow. Improvement will come after spells of cold, unsettled weather take place.
If you are a walk-in wade fly fisher, the South Fork is now a “piece of heaven.” Flows have decreased significantly ( now about 4500 cfs at Irwin, 4200 cfs at Heise, 2100 cfs at Lorenzo) and will do so further as the irrigation season winds down and Palisades Reservoir, presently at 10% of capacity, needs to be filled . So the choice of walk-in-wade locations on the river below are quite numerous. We can help in choosing locations to fish, so get in touch. With the fall colors, fine weather, concentrated fish populations, and safer wading the river is now as inviting as it can be.
No significant changes in either flow or fishing strategy since our last report. Some unsettled weather would certainly help the top water fishing by enhancing the BWO and mahogany dun hatches.
Brown trout are migrating to spawning areas throughout the river below lower Mesa Falls. In contrast to the brown trout runs in Yellowstone park waters, the Henry’s Fork run is attended primarily by local fly fishers. Thus with fewer anglers on the river, a better chance of solitude can be realized.
In addition, the lower river still offers good terrestrial insect hatches on sunny, warm days and BWO, mahogany dun, and caddis activity. So the river offers good fishing for the top water enthusiast as well as those preferring to try wet flies to encounter the migrating brown trout.
With exception of the Firehole River’s BWO and white miller activity above its falls, the brown trout spawning runs in the Madison and Snake River River drainages are the big attractions for fly fishers this month. So popular have these runs become that only the boat use restriction on park waters keeps them from rivaling, in terms of angler attendance, the famed green drake and large stone fly emergences on such as the Henry’s Fork and the Madison Rivers (June flood road damage will decrease the number of fly fishers attending the Gardner River brown trout run). Thus whether you plan to try the runs on the Madison River or on the Lewis and the Snake Rivers, be ready to accept that tolerance and courtesy will be required to have an enjoyable visit.
With flow out of Mackay Dam just below 200 cfs and likely to drop further, the river is a good option for a visit. BWO and midge activities will supply most of the action for feeding trout, so their life cycle patterns are good choices Don’t overlook trying a medium sized woolly bugger type or rubber leg pattern into deeper holes, and on warmer, sunny day try hopper and ant patterns still produce.
