Not much change since our report ten days ago. Flow in the lower river from Warm River to Chester is fairly constant and a bit below normal for this time of year. You can bet that the lower river will have plenty of fishing enthusiasts present later this week if the predicted nice weather happens.
Flow out of Palisades Reservoir was raised slightly to 4770 cfs ( now 5600 cfs at Heise, 3320 cfs at Lorenzo) last Sunday. Should be no effect on fishing as flow is below normal for this time of year. With the not quite normal snow pack last winter many reservoirs are being filled as much as possible before big irrigation demands arrive. A few midges are appearing up and down the river, but best success for now comes through pitching rubber legs and streamer patterns.
The high side of our fishing season is beginning. Already the South Fork is being visited by drift and jet boaters, the numbers of which are increasing every day with nearly all launch sites open and fishing success picking up. Drift boaters are floating the lower Henry’s Fork where launch sites are becoming more and more crowded, particularly those below Ashton Dam where the river offers excellent dry fly, streamer, and stone fly nymph fishing. Even the main stem Snake River has a drift boat-jet boat population pitching streamers. So we at Jimmy’s are seeing the beginning of floating fishing season.
Increasingly we get inquiries on “where to go”, “what is it like”, information from folks new to or outside of this area. We pass on as much information as we can, but in the interest of safety we have to stress that there are some basics that anyone should consider if not experienced with any water to be boated.
First, being a responsible boater requires thorough character knowledge of the river section to be floated. If unfamiliar with launch and take-out sites to be used, visit these beforehand, especially if they are of primitive nature to detect short falls or hazards. Consult with someone familiar (reputable fly shops and resorts should have character and hazards information on all these) with the physical nature of the section of interest.
Second, even after obtaining character information on the river section to be visited, it is prudent to stop while in the act of floating to observe its downstream character during an initial visit. It is also wise to do so during a first trip of the season because many places on the river change character. The lower South Fork is notorious for cutting new channels and abandoning old ones. Going down a channel that has been cut off from the main river and the necessary walk back out pulling a boat can ruin a visit, especially with little daylight left. Uprooted trees, brush piles, and barely submerged rock features can be unpleasant, even dangerous surprises. Irrigation diversions are particular dangers especially on lower reaches of the Henry’s Fork and South Fork and throughout the main stem Snake River. For example, there are four irrigation diversion on the lower Henry’s Fork from the Fun Farm Bridge down through St. Anthony.
Third, many of us rely on such as Google Earth or Maps software to observe a river’s character. We suggest not doing so. Here is why: changes in river channels occur almost annually. Uprooted trees can happen any time especially during the high flow of irrigation waters and even or run-off. Depending on irrigation demands flow particularly in the South Fork and main stem Snake River change considerably. Such changes can make new hazards and delete those in place. Detailed launch and take-out sites character and up to date hazard identification are not given. Electronic media is incapable of identifying these changes.
We offer these thoughts in the interest of having unforgettable positive experiences floating our rivers to enjoy some excellent fishing. We ask that you consider these in order to increase the chance that you will return to have another great experience.
Fun Farm Bridge
Currently the best stream fishing in the area is on the lower Henry’s Fork. From the Ora Bridge down to Chester, BWO, midge and a scattering of March Browns bring top water action. Drifting big stonefly nymphs through riffles will is become more effective as we progress toward mid-May. Streamers under low light conditions continue to produce for browns and post-spawning rainbows. These comments also apply to the river from Chester Dam to below St. Anthony. Drift boat fishers cause “traffic jams” at all launch sites from the Ora Bridge to Chester Dam, but there is room for walk-in wade fishing. From Warm River to Ashton Reservoir there is less crowding because distance spreads anglers around. The same comments apply with respect to fishing strategy but with drift boat fishing obviously the best way to cover water.
Springfield Reservoir offers fair fishing these days with midge pupa patterns producing at the taking depth. Small black leech and bead head nymph patterns are also effective. Hawkins Reservoir offers about the same, but its boat ramp-dam area can be a bit crowded especially on week ends. The Dairy Creek road from Hawkins Reservoir over the top to Daniels Reservoir is open but rough. All these reservoirs have turned over, so fishing on each should improve. We have no information on Chesterfield Reservoir to date, but being at a higher elevation it is likely behind the above mentioned with respect to fishing.
Flow out of American Falls Reservoir was raised from around 2500 cfs cfs to 5080 cfs at the Neeley gauge on Tuesday, April 13th.
Flow out of Palisades Dam was raised to 3430 cfs On Thursday, April 15th ( now 3880 cfs at Heise, 2100 cfs at Lorenzo) continuing the stair-step increase defined in the April 13th report. These flows are a bit below the mean flows for this date. Use the same flies and the same strategies we suggested in the April 13th report. Water remains clear and cold.
Flow out of Palisades Dam was increased from around 1750 cfs to 2460 cfs (2970 cfs at Heise, 1700 cfs at Lorenzo) last Friday. River water is cold and clear, in fishing condition throughout, but too cold for anything but midges to hatch. Look for USBUREC to raise flows in a step-wise manner from now on to the irrigation season. Rubberlegs, big stonefly nymph patterns and streamers work well as do small nymph patterns around riffles. All boat ramps are open. The USBLM Stinking Springs Human Entry road closure will be lifted at sunrise on May 1.
Water is back in the Dry Bed because irrigation structure repair there is complete.
Expect to have plenty of company if you visit the river from the Ora Bridge launch down to the Chester launch. BWO and midge life cycle and stonefly nymph patterns along with streamers under low light conditions are best bets for action. With more river to visit from Stone Bridge to Ashton, visiting anglers are more dispersed than in the river below Ashton Dam.
Here is Rob VanKirk’s latest summary of snow pack and water conditions in the Henry’s Fork drainage. Notice that snow pack conditions appear to be a bit below normal at the time of his report.
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Details:
Yesterday was dry yet again, but at least temperatures were cooler. Mean temperature was 9 degrees F below average and the coolest since March 31. Water-year precipitation to date stayed at 81% of average. Despite cool temperatures, all but one SnoTel station lost snow water equivalent (SWE) yesterday. Island Park lost the most, at 0.5 inch of melt, and the watershed total was 0.2 inch. Melt rate has averaged 0.13 inch/day over the first 12 days of April so far. SWE is 78% of average and lower than it was on this date in 2016, the last very dry year experienced in the watershed.
Light precipitation—in the form of snow at all elevations—is expected tomorrow and Thursday. Forecast amounts range from around 0.1 inch in the northeastern corner of the watershed to 0.5 inch in the southern part of the Teton Range. Valley areas and the Teton subwatershed are expected to receive the highest amounts. Cool temperatures will stick around through the end of the week. Warm, dry conditions are expected after that.
Natural streamflow continued to drop yesterday, despite ongoing snowmelt. Natural flow was 84% of average yesterday: 81% in upper Henry’s Fork, 83% in Fall River, and 91% in Teton River. Diversion continues to increase slowly, although data are not yet being reported for all canals. Moisture availability in the agricultural areas—defined by my crude difference between precipitation and evapotranspiration—continues to drop and is now almost 7 inches below average. I have already had to extend the vertical axis on the chart twice since last summer and may need to do so again in a week or so.
At an average outflow of 418 cfs, Island Park Reservoir gained 22 ac-ft yesterday. Current content is 120,795 ac-ft (89% full), compared with an average of 115,907 ac-ft (86% full). Although ice is starting to melt at the edges at some locations around the reservoir, Fall River Electric personnel report solid ice cover around the dam.
Graphics:
Watershed SWE
Natural Stream Flow
Another few days of sunshine and wind will clear all the snow from Stone Bridge boat ramp. Flow is normal and water is clear. Floating the river from there on down to Ashton offers good fishing for those presenting stone fly nymphs and such fished deep. Some BWOs emerge during PMs to offer some dry fly fishing.
Below Ashton Dam windy days make fishing tough and blows away any midges and BWOs making the mistake of emerging. During calm days top water fishing for these can be good. Use life cycle patterns for each. Streamers produce when presented deep and around overhead cover near banks out of the sunlight.