South Fork & Henry's Fork Fishing Reports

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Fishing Reports

Jimmy's All Seasons Angler / Fishing Reports (Page 3)

Henry’s Fork, January 5th, 2021

Many fly-fishers are interested in how winter’s progress will impact fishing quality in the Henry’s Fork and its drainage during the upcoming season. Dr. Rob Van Kirk, Henry’s Fork Foundation Senior Scientist, compiles and offers a water supply report sequentially throughout the year for the river and drainage. We at Jimmy’s believe that placing on our web site Rob’s presentation and analysis of data impacting Henry’s Fork water supply provides to a wider range of interested fly fishers more information with which to judge quality in its upcoming season. We therefore will provide Rob’s updates here during the winter season and into the irrigation season. The first of these is below.

Henry’s Fork water supply, Jan 05 2021


  • Another warm, wet day increased water-year precipitation to 82% of average and SWE to 85% of average.
  • At an outflow of 329 cfs, Island Park Reservoir gained 443 ac-ft yesterday, one-third of which was from direct precipitation on the reservoir surface.
  • The reservoir is 82% full and filling at well over twice the rate needed to reach the April-1 target.


Mean temperature yesterday was 10 degrees F above average, and precipitation was recorded at all stations except Alta. As predicted, precipitation heavily favored the upper Henry’s Fork for a change, where amounts through midnight ranged from 0.3 inch at Island Park to 0.7 inch at White Elephant and Black Bear. Ashton was again the winner in the valleys with 0.16 inch. Water-year total precipitation increased to 82% of average, and snow water equivalent (SWE) increased to 85% of average. Precipitation is continuing this morning, so storm totals will end up being quite a bit higher than reported through midnight. Only light precipitation is forecast for the next seven days, and the long-term outlooks call for generally dry conditions next week.


At an outflow of 329 cfs, Island Park Reservoir gained 443 ac-ft yesterday, one-third of which was from direct precipitation on the reservoir surface. The reservoir is 82% full, compared with 70% full on average. Fill rate has averaged 229 ac-ft/day since December 1, and a fill rate of only 103 ac-ft/day is needed for the rest of the winter to meet the April-1 target. Reservoir content is 1,880 ac-ft ahead of my November 19 prediction, which assumed an outflow of 330 cfs. As mentioned previously, higher-than-expected fill rate is due to a combination of slightly higher inflow and slightly lower outflow, at least according to our streamflow measurements earlier in December and to the power plant operator. According to USGS data, updated in mid-December, outflow since December 1 has averaged 344 cfs, compared with 341 cfs on average.



  • Watershed SWE
  • Island Park Reservoir inflow/outflow: 15-minute data
  • Island Park Reservoir volume: 15-minute data
  • Island Park Reservoir volume: predicted vs. observed


Station guide and disclaimer

Glossary of Terms


Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-652-3567 OFFICE

208-881-3407 CELL

208-652-3568 FAX


[email protected]

Rob’s blog


Main Stem Snake River, January 5th, 2021

Float fishing is a very popular activity on the Snake River, thus IDF&G strives to maintain boat launch facilities in good shape. Here are descriptions of recent repairs and improvements to the much used Menan Boat Launch Site by Darin Schneider Idaho Fish and Game.

Menan Boat Dock Repair

After spending time in the Big Lost drainage, the maintenance crew switched gears and worked on the Snake River’s Menan Access site where they made boat ramp repairs and replaced the dock. Prior to repairs, the boat ramp was too short at low water, with broken ramp tiles that needed replaced. The old dock was rough on boats, and was often too far away from the ramp to be useful or too far from the bank to allow one to step on the dock from the bank.

Big Lost River Campsite

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Darin Schneider Idaho Fish and Game

An additional 7 feet of boat ramp were added using concrete tiles to extend this ramp (pictured below), and replaced broken tiles in the upper part of the ramp (pictured above).

Boat Ramp

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Darin Schneider Idaho Fish and Game

The new tiles were connected together prior to installing them into the river and then used diving equipment to attach the new set of tiles to the existing ramp.

Menan Boat Dock

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Darin Schneider Idaho Fish and Game

The repaired/extended boat ramp and the new dock in Menan are ready for use, but renovations are ongoing with plans for the installation of a gangway in 2021.

Menan Boat Dock

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Darin Schneider Idaho Fish and Game

The Upper Snake maintenance crew is always thinking outside of the box in an effort to provide the best public access sites possible in terms of usability and safety. “We enjoy what we do because we know how much the public values these access sites and the recreation activities these sites make possible,” says Recreational Site Maintenance Foreman Darin Schneider.  “I hope everyone is as happy as we are for what we have accomplished so far and stay tuned for more as we remain dedicated to continue maintaining and improving public access sites in the Upper Snake Region.”

Anglers are Reminded of Special Fishing Regulations on the Snake River Below American Falls Dam

Monday, December 28, 2020 – 3:49 PM MST

The tailrace fishery on the Snake River downstream of American Falls Dam to Eagle Rock has really grown in popularity over the past decade. This stretch of the Snake River has long produced a fabulous recreational fishery, one that has increased in both quality and diversity over recent history. Angler effort has followed suit, and for good reason—the fishing can be downright great throughout much of the year! The fishery is primarily supported by a combination of rainbow trout, brown trout, smallmouth bass, and white sturgeon. Anglers from near and far enjoy this stretch of river and it has become somewhat of a destination trout fishery.  This winter has been no exception, with recent angler effort being fairly high. Along with that, Fish and Game has documented an unusually high rate of non-compliance with the winter fishing regulations. In fact, Conservation Officers have detected several hundred angling-related violations over the past year along this stretch of river. The intention here is to provide some clarity and guidance that will help anglers stay in compliance with the special rules used to manage this fishery. Hopefully, this will break-down the regulation complexity and help make anglers feel at ease when they check-out this section of the Snake River.

Some fish populations in this portion of the Snake River are managed using special angling regulations, or exceptions to the general Southeast Region Rules found in the Idaho Fish and Game fishing proclamations. The Snake River is divided into two distinct reaches based on fishery management: 1) the section from American Falls Dam downstream to Eagle Rock, and 2) the section from Eagle Rock downstream to the western boundary of the Gifford Springs boating fishing zone. The special fishing regulations for these two river reaches are as follows:

Snake River

Section: From the downstream side of the Gifford Springs boat fishing zone (western boundary) upstream to Eagle Rock

• Bass limit is 2, any size

• Trout limit is 6, only 2 may be Cutthroat Trout

Section: From Eagle Rock upstream to American Falls Dam

• October 16 through Friday before Memorial Day weekend – limit is 0 for game fish species, catch-and-release, no bait allowed, barbless hooks required

• Saturday of Memorial Day weekend through October 15 – bass limit is 2, any size; trout limit is 6, only 2 may be Cutthroat Trout, only 2 trout over 16 inches

With respect to the section from Eagle Rock to American Falls Dam, no harvest of game fish species is allowed between October 16th and the Friday before Memorial Day (that’s May 28th in 2021). In addition, anglers are not allowed to use bait and must use barbless hooks during this period. Bait and barbed hooks are allowed starting the Saturday before Memorial Day; however, the regulations still differ from the general fishing regulations. During this time, the daily bag limit for bass is two (both species combined) and the trout daily bag limit is six. Only two of a six trout daily bag may be cutthroat trout, and only two trout of any species may be longer than 16 inches.

From Eagle Rock downstream to the Gifford Springs area, the bass limit is two and trout limit is six. Again, only two of any trout in a six limit daily bag may be cutthroat trout. Any size trout may be harvested in this reach.

The intent of special angling regulations is to control angler interactions in a way that supports management direction and provides specific angling experiences. Special rules are an important tool that fishery managers use throughout the state to shape fisheries and angling experiences congruent with the state’s Fisheries Management Plan. Remember, nongame fish species may be harvested by any legal method at any time during the year.

Anglers are encouraged to contact the Southeast Regional office or try out IDFG’s fishing planner ( for additional guidance and regulation-related information. For more about how to interpret and use the IDFG fishing proclamations, check out this video resource (

  • img_2434

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    D Teuscher

South Fork, January 2nd, 2021

It looks like about 900 cfs will be the maintenance flow out of Palisades Dam until the upcoming irrigation season. That seems a bit small to some folks, but consider that tributaries add a considerable amount of water to the river on downstream at least to Heise where the flow increases to around 1300 cfs.

In any case, the South Fork is arguably our most popular river for angling. That being said, IDF&G spends a good deal of its fishing resource allocations on studying and maintaining its salmonid population. Below are results of recent studies that indicate good news for the salmonid population, the wildlife that depends on it, and anglers.


High trout numbers continue in the South Fork Snake River

By Pat Kennedy

The South Fork Snake River (SFSR) in eastern Idaho supports the largest river population of native Yellowstone cutthroat trout in Idaho as well as other popular game fish including Rainbow trout and Brown trout. Idaho anglers have repeatedly asked Fish and Game managers to focus management efforts on protecting native trout species when possible. This public sentiment is reflected in our state fish management plan where the goals for the South Fork Snake River include: protecting the genetic integrity and population viability of cutthroat, and reducing rainbow trout abundance to less than 10% of the trout in the upper river near Conant, as was the case in the mid-1980’s. These goals are also reflected by the Yellowstone cutthroat trout management plan. Each fall, IDFG employees use boat electrofishing techniques to estimate trout numbers in order to gauge management efforts relative to goals stated in the management plan. Results from 2020 surveys suggest two things; trout numbers are at a record high and Rainbow trout still comprise more of the population in the upper South Fork than called for in the management plan.


Almost every year since 1986 IDFG conducted abundance estimates in October near the Conant boat ramp to monitor trout abundance in the upper river. At our Conant monitoring reach, we estimated trout densities to be 6,302 fish/mile. The 10-year average is 4,710. Good trout numbers are expected to contribute to continued good catch rates for anglers. Rainbow trout, which are the biggest threat to cutthroat trout through competition and hybridization, continue to provide management challenges. Rainbow trout made up 43.1% of the trout catch, so IDFG plans to continue efforts to lower their abundance using the angler incentive program and other tactics.


Pat Kennedy, IDF&G

Figure 1.               Estimates of fish per mile for Yellowstone cutthroat trout (YCT), rainbow trout (including hybrids; RBT), and Brown Trout (BNT) at the Conant monitoring reach from 1982 through 2020 with 95% confidence intervals.

Figure 1

Abundance surveys have been conducted near the Lorenzo boat ramp most years since 1987 to monitor abundances in the lower river.  At Lorenzo, Yellowstone cutthroat were estimated at 1,260 fish/mile, the highest on record (Figure 2)! The ten-year average for cutthroat is 407 fish/mile. The total trout estimate was 2,650 trout/mile which was significantly higher than the ten-year average of 1,889 trout/mile. Brown trout are doing well here too with 1,390 fish/mile which is slightly lower than the ten-year average (1,477 fish/mile).


Figure 2.              Estimates of fish per mile for Yellowstone cutthroat trout (YCT) and brown trout (BNT) at the Lorenzo monitoring reach of the South Fork Snake River from 1987 through 2020 with 95% confidence intervals.

Electrofishing boat

Pat Kennedy, IDF&G

The most important take-home message from these surveys is that trout abundance is high in the SFSR. The total trout estimate is higher than ever estimated at Conant, since 1982. Cutthroat appear to be doing fairly well, despite the continued threats from rainbow trout. Unfortunately, what’s good for one species seems to be good for the other, as rainbow trout continue to comprise a greater proportion of the population.


Other rivers in the western U.S. also host estimates of trout per mile in the thousands, but few boast estimates higher than 5,000 trout/mi. Within Idaho, the South Fork Boise, Big Lost, and Henry’s Fork rivers boast some of our highest abundance estimates, but none have exceeded 6,000 fish/mi. Other rivers in the west such as the Green River below Flaming Gorge reports 10,000 trout/mi, but stocked 14,500 RBT in the summer of 2020. Similarly, the Idaho rivers with high abundance typically receive at least some hatchery trout supplementation. The SFSR is not supplemented with hatchery trout. The exceptional wild trout population in the South Fork highlights the extremely high productivity observed in recent years in the river and the potential this tailwater fishery possesses. For anglers, high abundances of trout should ensure that fishing will remain great into next year and beyond.







Big Lost River, January 2nd, 2021

Here are some improvements to access in the Big Lost River area that will benefit all anglers from 2021 into the future

Access site improvements in the Upper Snake

Wednesday, December 23, 2020 – 11:17 AM MST

The year 2020 with a pandemic has changed a lot of things for many of us. One change noticed by Fish and Game was an increase to the amount of use that occurred on department owned and managed public access sites. The increased demand for recreational opportunities made it abundantly clear how valuable our public access areas are to sportsmen and women.

Fish and Game maintains 70 access sites within the Upper Snake. This year the focus was on making improvements to existing access points which needed some attention, including several sites in the Big Lost drainage. Here are some highlights from the past year.



New vault toilets at Mackay Hatchery-

Vaulted toilets were installed near the fishing pond at Mackay Hatchery. This new amenity is located near the visitor parking area and fishing pond and makes the fishing or sight-seeing trips to the hatchery more enjoyable for you and the family. This was placed in early spring and features an Americans with Disabilities Act (ADA) compliant parking pad close to the fishing pond so you won’t miss out on any of the family fun.

Mackay Hatchery Vault Toilet

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Darin Schneider Idaho Fish and Game

Dock repairs at Mackay Reservoir-

After installing the new toilet at Mackay Hatchery, the maintenance crew worked on access sites along Mackay Reservoir. They fixed the boat dock at the Mackay Reservoir-lower site by fixing the anchor that holds the dock in place and cleaning sediment from off the lower portions of the ramp while low water levels in the reservoir allowed us to work in the “dry”. In the picture below, they are repairing the dock’s wheels that lets the floating dock roll up or down the bank as water levels change, allowing the dock to self-adjust during changing water levels to maintain the position of the dock at the edge of the water.

Mackay boat dock

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Darin Schneider Idaho Fish and Game

One of the unique challenges faced this year was the need to reposition the anchor for the Mackay dock. After several years of wind and shifting ice, the anchor and the dock had moved to a point where the dock became dysfunctional relative to where the boat ramp is located. In the picture below, they are moving the concrete anchor block and dock back into the correct position using lift bags and scuba diving equipment. Once the anchor became suspended with the lift bags,  a boat was used to drag the anchor back to the correct position.

Mackay dock anchor

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Darin Schneider Idaho Fish and Game

Big Lost River-Lower Site updates-

Several updates were made to the Big Lost River-lower site. Truckloads of gravel were hauled in to repair roads and dead trees were removed from the campground making it easier to access and safer to use.

Stennett Access Site parking improvements-

The Stennett Access site had the parking lot extended with a new turn-around area which will make it easier to load/unload small watercraft.

Additional camping at Rothwell Access Site-

Additional camp sites were added to the Rothwell Access site with parking pads and an improvement to the roundabout, making it more convenient to pull campers into and out of the site.




Today at Jimmy’s, January 2nd, 2021

Unfortunately we will not offer fly tying and fly casting classes for the foreseeable future. The ongoing virus situation is the reason.  When administration of vaccines reduces infections to a rate acceptable to State of Idaho health authorities to normal social conditions, we will resume these classes.  We regret this announcement, but public safety comes first.


South Fork, December 1st , 2020

It looks like about 900 cfs coming out of Palisades Dam will be the basis for the South Fork maintenance flow through the winter.  Resulting flow at Hesie will be around 1300 cfs and at Lorenzo around 600 cfs.   Where roads and bank ice permit, there will be a good choice of walk-in wade fishing locations. Be aware that the South Fork River Road above Heise closes to motorized vehicle travel from Table Rock to Black Canyon on December 15th.  This closure protects wintering wildlife.


It’s Time for Season Ending Tasks

Old Man Winter is knocking on our doors, and those “bluebird days” are getting rarer. Soon only the few hardiest of fly-fishers will be out on the water.  Most of us are saying good-bye to ice in the guides, ice clogged reels, frigid winds, and chilled fingers. For many of us there could be a final trip to the river where it remains accessible or to one of the diminishing number of still waters remaining ice free. True, memories from the good times of the season past will sustain us until faded by events coming in the next season.  We, of course, our lucky because Idaho Department of Fish and Game grants us the Catch and Release season on many streams and many still waters remain open even though for ice fishing. The only problem will be travel to many of these places will not be possible, so our where-to-go choice will be limited. But for those bidding adieu to the season, there remains some actions born out of prudence to prepare for either the upcoming Catch and Release or when the next general season begins. All this revolves around, cleaning, repairing, and even updating that equipment we all treasure.

Perhaps nothing in the fly-fishing equipment world suffers wear and tear like a fly line.  It is always under some kind of stress when in motion.  Any loop whether formed during casting or drifting applies a differential stress on a line.   The best action here is to unload the line and inspect it for surface breaks that eventually will expose the core or for areas of exposed core. Either one signals it is time to buy a new line. After inspection it is time to clean the line. Immersion in a warm water-detergent mixture to loosen grime deposits works, then a wipe dry with a soft fabric towel under gentle pressure from index finger and thumb works. After drying I like to lubricate with a product such as Mucilin before storage.

Fly line backing also suffers wet-dry cycles, so it is a good idea to inspect it for damage. If you are lucky enough to tackle a number fish that get into your backing, a cleaning with that detergent-warm water mixture then drying before storage is a good idea.

For cleaning that reel an old tooth brush to apply the detergent-warm water mixture followed up with lubrication works. Nothing, however, works as well as an ultrasonic cleaning. Jewelers use these as a standard for cleaning all kind of jewelry. Ask your jeweler friend to immerse your reel and separated spool in the cleaner tank and turn the cleaner on. If the jeweler allows you to watch it in action, you will be amazed to see the dirt literally flying off these into the tank’s water. After a minute or so the immersed equipment will be totally cleaned of a seasonal accumulation of grease and grime. By the way, ultra sonic cleaning also works great for cleaning lines.

Leaders and tippets should be replaced at the end of the season.   They suffer the same differential stress as the line and “wind knots”  are a death knell to any leader or tippet.

No one wants leaking waders regardless of the season. Inspection after any use is always a good practice for nipping emerging damage at the bud.  But if significant repairs are needed, now is the best time to send them to the manufacturer for doing such.

At the end of a season the contents of that fly box can be mixed up. So complete drying of each then reorganizing or placing in storage is the next step. But while doing either of these, have that nearby tea kettle going in a steaming mode.  Using tweezers, place any fly with disorganized hackle in the out-coming steam jet. Hackles will jump back into position. Allow the steamed flies to dry thoroughly, then move to storage.

Sad as it is, these actions signal a general season coming to an end. But they also are prudent for beginning the next begin season with minimum equipment failures.



Small Streams, November 10th, 2020

Any stream with a reservoir is seeing flows cut back to begin storage for the next agricultural season. For example, the flow out of Blackfoot River Reservoir is reduced to 73 cfs, out of Henry’s Lake reduced to 3 cfs, out of Mackay Reservoir reduced to 57 cfs.  Of course the problem with fishing many small waters now is getting there. Maintenance on many back country roads has or will soon cease, and there will be times when highways will offer difficult passage.  All this means less information coming into the shop with respect to fishing, so look for our fishing reports being reduced accordingly.


South Fork, November 7th, 2020

Water flow in the river has been stable (about 1300 cfs at Irwin) for almost two weeks. BWOs remain active, and rubber legs and streamer patterns will produce especially under low light conditions. But winter is coming, and next week looks like ice in the guides and reels and chilled fingers expected. Is it time to clean up the gear and store it for next year? Not quite. There will be some “half decent” weather as we move through November with decreasing BWO activity and more reliance on nymph and streamer patterns for fishing success.  So enjoy the remnant of our season, and what ever you do: don’t go for a dunking!