Flow out of Palisades Dam was essentially doubled to 1790 cfs on March 29th. This begins flow increases to answer irrigation demands for the upcoming growing season. We will keep track of these increases throughout the season and log them on this fishing report.
Flow out of American Falls Dam was raised from 1250 cfs to 2430 cfs yesterday. A visit to fish is a good option, but be careful when wading.
The Henry’s Fork below St. Anthony is a productive fishery with an increasing brown trout population. Recently IDF&G fisheries personnel have completed a survey of its salmonid population. The results of this survey are given below.
Trout Populations are Strong in the Henry’s Fork near St. Anthony
By John Heckel
Regional Fisheries Biologist
In early October 2020, we conducted our 6th population estimate on the St. Anthony reach of the Henry’s Fork of the Snake River. This estimate is conducted in the fall every three years and extends from the Railroad Bridge downstream to the Red Road Bridge. Based on our sampling data since 2010, we can see an increasing trend in Brown Trout abundance in this reach.
We can see in the figure above that the number of Brown Trout per mile has been increasing since we started surveying the reach in 2004 while Rainbow Trout abundance has remained low and relatively constant. Currently, Brown Trout make up 96% of the trout composition in this reach where we caught 1,468 trout in total. As can be seen in the images, there are some very large Brown Trout with fish up to 25” in this reach!
The trout population in this portion of the Henry’s Fork is managed as a wild trout fishery, so these large trout captured in this reach are in fact wild fish. Therefore, referring to the length distribution of fish captured here, this section of river grows some very large trout.
Although water temperature in this section of the Henry’s Fork can become warmer than 70°F during portions of the summer, trout can find thermal refugia from groundwater and spring inputs that help coldwater fish remain cool. In addition to Brown and Rainbow trout, we also estimated Mountain Whitefish abundance in the reach. There were 685 whitefish per mile. Based on our length frequency data from Mountain Whitefish we observed several age classes present, which is evident by the multiple peaks in different length groups.
Survey results indicate sport fish populations in the St. Anthony reach are healthy and in good numbers. Managing this section of the river as a wild trout fishery with a 2 trout limit appears to be conducive for growing large fish and allowing population numbers to increase.
2021 fishing and boating regulations for the Park are in this link (note the fee increases and justification for such). Final-signed 2021 Fishing Vendor Permit Letter
The flow out of American Falls Dam was raised from 370 cfs to 1250 cfs on 3/18. That means you’d better hurry if you want to fish the river below with relatively easy access! Wading is still safe, but more flow increases are coming making wading tougher and spreading fish throughout the river. Streamers pitched and retrieved or drifted under an indicator at taking depth remain as effective strategies.
Flow out of American Falls Dam remains just under 400 cfs, but any day a BIG increase will happen to satisfy Magic Valley agricultural demands. Streamer presentation remains the name of the game. The further downstream from the dam one goes, the fewer anglers will be encountered.
Midge and BWO activities are bringing fly fishers to locations from Ora Bridge downstream to the Fun Farm Bridge area. Use life cycle patterns for each activity. Presenting streamer and woolly bugger patterns is effective for encountering post spawning rainbows. Some rainbow spawning remains, so avoid places where such is ongoing. Stream flow in this area is near normal.
Here’s a bit of info if you are considering a float trip during this beautiful weekend. The Conant boat ramp has enough snow to make getting to the river a bit difficult. Kitty litter, tow rope, and shovels may be in order. Other than that, flow out of the dam remains around 900 cfs increasing on downstream to around 1300 cfs at Heise. Water is ultra cold and clear with midges emerging best in backwaters and calm channels. Rubber legs, streamers, etc., best bet for encountering bigger fish. Nymphs with and without beads give best results around riffles.
It’s Just Around the Corner
We bet you’ve heard the words in the above title a time or two recently! Also, it’s been a windy winter, both politically and seasonally. But within a matter of days we will advance into springtime. Expect the usual transition weather period which varies yearly. But with increasing daylight hours and warmth, fly fishing will come out of essential hibernation for most of us. True, a few hearty souls braved winters extremes to be on the water, but “Just Around the Corner” is that for which most of us have been waiting. If you are new to the area, here is an overview of what to expect as the season progresses, if you are a long-time resident, what you have been anticipating is about to arrive.
It begins with midge activity on streams that remain open year-round and those for which the catch and release season applies. It’s mainly limited to lowland water because most higher elevation waters remain snow bound or iced over and secondary roads are yet to open. As daytime lengthen and atmosphere warms, blue wing olive (BWO) and March brown mayflies begin to appear. Streamers become effective in fooling post spawning cutthroat and rainbow trout. Caddis at lower elevation waters begin working their maturing way up the rivers in increasing number to be important salmonid food through the season. When mid-May arrives major fly fishing events begin. Back country roads begin to open to allow access to an expanded variety of waters including low land still waters.
Now happenings resembling a series of gold rushes begin. First comes the Henry’s Fork giant and golden stone fly events. Waders and boaters converge to follow “the hatch” up the river from mid May into mid-June. But that is not the only premier angling event happening. Ice usually leaves Henry’s Lake in late May, but Old Man Winter not always cooperates. Cool springtime waters make for excellent fishing on lakes and reservoirs. In mid-May the Montana general season opens. The Yellowstone Park season opens to feature Firehole River fly fishing. So begins the “high season“ for area fly fishing retailers. As the Henry’s Fork stone fly event dwindles, another massive event, the Henry’s Fork mayfly emergence begins. From all corners of the earth fly-fishers converge on the middle river and Island Park to enjoy salmonid responses to drake mayflies, PMDs, BWOs, flavs and types of lesser renown. Some visiting fly-fishers bring accents of and attempts at the English language that confound understanding. Run-off declines in such as the Teton River drainage, South Fork and Salt River tributaries and still waters attract fly-fishers with damselfly and the beginning of season-long speckled dun activity. Stone fly activity begins on these streams as waters clear and warm. It is the turn for the South Fork and Teton River stone fly events by early July, and the same on the Madison River works its way upstream extending the “high season.” It continues into July as the South Fork drainage mayfly event expands to last into early autumn and terrestrial insects join caddis flies, mayflies and stone flies as a major salmonid food form on all streams. By now social turmoil on so many waters, much added by floating recreationists, drives many fly-fishers to seek solitude and tranquility. Some turn to lightweight equipment and seek small waters to find these conditions as all secondary roads are open. Fall River Basin in the SW corner of Yellowstone Park, Southwest Montana waters, Big Lost River Copper Basin waters, upper Blackfoot, and Teton River drainages offer relief from icon water crowds (Go to the Articles section of our website to find strategy and character details on many of these waters: so many of them offer more than solitude and tranquility). The August gulper phenomenon takes place on not just Hebgen Lake, but on many of our still waters, and fly fishing success on streams begins to dwindle if one is not equipped to present terrestrial insect patterns.
Late August and September are likely the most pleasant times to be on the water in our area. Insect pests have much diminished, air temperatures have mellowed, most visiting fly-fishers have departed for jobs, school, or family obligations. Fall colors make carrying a camera a good idea. The fall peak of mayfly activity takes over with early-in-the-day tricos, BWOs, and on some waters the mahogany dun. Early September is a good time to enjoy quality Wyoming waters such as Flat Creek, the Grays, Gros Ventre, and Salt Rivers. By October frosts work their way down in elevation and begin the end of the dry fly season excepting for the hardy midge and BWO activity. Killing frosts will soon dampen terrestrial insect populations to further decrease dry fly fishing. However, the cooling waters return streamer fishing to its early spring effectiveness as brown trout begin spawning migrations on all waters they occupy. Presentation particulars overwhelm pattern selection during these times. Low light and unsettled weather offer the best success opportunities whether the South Fork, Henry’s Fork, main stem Snake River, Lewis, Madison and Beaverhead Rivers and Silver Creek are targeted. But those cooling mornings and chilling breezes suggest that again Old Man Winter is arriving re-establish ice in the guides and reels and to push so many fly-fishers back inside to savor the season that was.
Idaho Falls is the Greater Yellowstone Area’s southwest fly-fishing hub. The town is surrounded by quality waters, still or moving, large or small, and the town offers all services in quality to fly-fishers. We at Jimmy’s All Seasons Angler feel duty bound to capture information that impacts all forms of fly-fishing on area waters throughout the season and relate such to you to help choose which to enjoy at any time. We offer quality fly-fishing items, Idaho, Montana and Yellowstone Park fishing licenses, we maintain our web site fishing report as up to date as possible, and we offer instant information to those visiting Jimmy’s or making email or telecommunication inquiries.
Bruce and the All Seasons Angler Crew
It’s been a long cold winter on the river, but here are a few things worth some words. First, the flow from Palisades Dam has been near consistent at around 900 cfs all winter. Downstream because of tributary contribution flow increases to around 1300 cfs near Heise. Flow decreases somewhat downstream to the Henry’s Fork confluence. Midge activity seems to be increasing and will continue to do so as we warm up. Activity can be particularly good were spring water enters. Rubber legs patterns have been the best “go to” fly. Try them in traditional black , brown, olive, or tan (#4-8, all colors). Present these to run deep at the top of holes and runs drifting deep with an end-of-the-drift swing upward through the water column. The best access is around the Heise bridge and there are some such points on downstream.
Stay warm, and wade carefully. The water is awfully cold!