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Fishing Reports

Jimmy's All Seasons Angler / Fishing Reports (Page 49)

Henry’s Lake, May 16th, 2022

Fish are in the shallows all around the lake and fishing is great. Most are cutthroat trying to spawn and just about any wet fly will work. Any easy access place such as the state park, Bill Fromm county park, the cliffs area, and the hatchery, anglers are almost ” shoulder to shoulder” trying to hook up. Using a boat or flotation devise gets you away from the crowds and the stories, believable and unbelievable. The catch and release season is on until general season opens.on the last Saturday of the May. So expect crowding and good fishing until warming water signals to fish it is time to move to more comfortable deeper water.

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Henry’s Lake, May 10th, 2022

Th catch and release season is on at the lake. Access is limited, and weather is at least stormy. Places open, such as the hatchery access, tend to become populated with anglers wading and using flotation devices. Leech, Halloween variations and fly rod jigs patterns are among those being effective.

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Henry’s Fork, May 10th, 2022

When not blown away or put down by wind, BWO March brown mayflies and early season caddis can offer good top water fishing afternoons on the lower river. sweeping big stone fly nymph patterns along the bottom is also effective.

Excepts from Dr. Rob Van Kirk’s Henry’s Fork drainage snow-water report of May 9th are below.

Headlines:  

  • Mean temperature yesterday was 14 degrees F below average, and precipitation was heavy enough to move the water-year total up another notch to 85% of average.
  • New snow accumulated at all SnoTel stations and was by far heaviest in the northern and eastern portions of the Island Park area.
  • Natural flow dropped yesterday in response to colder weather but will increase in a day or two when yesterday’s new snow melts.  
  • At an outflow of 276 cfs, Island Park Reservoir gained 449 ac-ft yesterday and is still on track to fill on May 20.

Details:

Mean temperature yesterday was 14 degrees F below average, setting a new low for the date in the 1989-2022 record. Precipitation ranged from 0 in valley areas to nearly one inch of water equivalent in areas of the upper Henry’s Fork watershed and was enough to move the water year total up one more percentage point to 85% of average. For the two-day storm, mean temperature was 11 degrees below average, and precipitation totaled 0.42 inch over the watershed. Valley areas received only a few hundredths, while White Elephant and Black Bear SnoTel each received over 1 inch of new snow water equivalent (SWE). Precipitation heavily favored the Island Park area, where driving yesterday was very difficult and people reported 20 inches of new snow in places. Over the whole watershed, net change in SWE for the two-period was a gain of 0.5 inch, compared with an average change for the date of 0.7 inch of melt.

Very light precipitation is possible Thursday and Friday, before what appears to be an extended period of dry weather sets in. Temperatures remain below average into the weekend but will creep back up to average or even above early next week. So, it appears that our five-week run of cool, wet weather will end soon.

Natural stream flow dropped yesterday in response to cold weather, but I expect it to rise again in a few days as yesterday’s new snow melts. With temperatures back up to average by the weekend, I expect stream flow to increase substantially early next week, especially on Fall River. Watershed-total natural flow is 73% of average for the water year so far, the lowest in the 1978-2022 record by quite a margin. Natural flow system-wide has increased enough relative to diversion that the American Falls Reservoir storage right is accruing water again after a week or so without any accrual. Physical storage in the upper Snake River system has been increasing very slightly over the past few days but is still no higher than its peak a few weeks ago at 59% full.

At an average outflow of 276 cfs, Island Park Reservoir gained 449 ac-ft of physical water yesterday t0 reach 97% full. At this rate, the reservoir will fill around May 20. However, some of yesterday’s gain came from direct precipitation on the reservoir surface, and with only very light precipitation forecast for the next week, fill rate will likely be a little lower than yesterday’s. On the other hand, stream inflow will get a small boost as fresh snow from the past few days melts.

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-881-3407 CELL

208-652-3568 FAX

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Henry’s Fork, May 2nd, 2022

Good BWO weather continues. The same continues for successful streamer presentation and for responses to big stone fly nymphs as these bugs begin moving along the bottom towards banks.

Dr. Rob Van Kirk’s latest water report for the Henry’s Fork drainage follows.

Headlines:  

  • Heavy precipitation across the watershed last night and this morning increased water-year precipitation to 84% of average.
  • At an outflow of 425 cfs, Island Park Reservoir gained 520 ac-ft yesterday, of which 180 ac-ft was from direct precipitation on the reservoir surface.
  • Recent cold weather has delayed snowmelt, but peak SWE this year was 8.3 inches below average, equivalent to 620,000 ac-ft (4.5 times the capacity of Island Park Reservoir) of water that has not fallen on the watershed this year and will not contribute to stream flow or reservoir fill.
  • Water-year natural flow to date is 75% of average and the lowest in the 1978-2022 record. The best-case outcome for the water year is 77% of average stream flow, 6th driest on record.
  • The best water-management outcome possible is that spring and summer precipitation is high enough that reservoir draft is lower than expected, and the reservoir system ends the season better than expected.

Details:

A strong and unusually wet cold front brought heavy precipitation to the entire watershed last night and this morning. Precipitation prior to midnight was enough to move the water year total up a percentage point to 84% of average. Much more precipitation fell after midnight. Warmer temperatures over the past few days increased natural stream flow, but diversion increased just as much. Current natural flow is only about 1,500 cfs greater than diversion right now. After another reduction in outflow, Island Park Reservoir gained 520 ac-ft yesterday, 180 of which was from direct precipitation on the reservoir surface. Outflow will be reduced again tomorrow to around 275 cfs to fill the remaining 7,838 ac-ft as soon as possible, hopefully in 10 days or so.  

Will additional snow gained over the past month increase water supply? The short answer is: only very slightly. Here’s why. Current snow water equivalent (SWE) is 80% of average for the date. That may sound good, but there are three reasons why it is not. First, 80% of average is 20% below average and still only in the bottom one-third of years since 1989. Second, on average, 15% of the snowpack has already melted at this point, so the current value is being compared to one that is already lower than the peak. Third, this year’s peak of 20.1 inches of SWE is 8.3 inches below the 1989-2021 average. That 8.3 inches did not fall on the watershed this winter and will not fall over the remainder of the spring, no matter how slowly our remaining snowpack melts.

About 70% of the Henry’s Fork watershed, or 1.49 million acres, accumulates snowpack. Over that area, the 8.3 inches of missing SWE (relative to average) is a little over 1 million ac-ft of volume in SWE. Around 60-65% of that, when melted, ends up as stream flow during the subsequent spring and summer. The remainder replenishes soils and aquifers to support future stream flow or is lost to evapotranspiration. So, that 8.3 inches of missing SWE is worth about 620,000 ac-ft of missing stream flow that will not flow down the river this spring and summer. For perspective, 620,000 ac-ft is 4.5 times the volume of Island Park Reservoir, 2.6 times the volume of the three reservoirs in the watershed combined, and 70% of total annual irrigation diversion in the watershed. Across the whole upper Snake River basin, the analogous deficit means that there is not enough water to fill the reservoir system beyond its current level of 59% full and meet ongoing irrigation demand.

Can a cool, wet spring and summer increase water supply? The short answer: again, very little. First, long-range forecasts call for a hot, dry summer. But, even if those are wrong, spring and summer rain cannot make up for missing snowpack, because most rain is taken up by plants and soils and does not contribute to stream flow the way winter snowpack does. So far this water year, natural streamflow is only 75% of average (25% below average) and the lowest in the 1978-2022 record. Considering poor base flow (the fall and winter “base” on which this year’s snowmelt is added) and a still very poor snowpack, even well above-average precipitation from here on out will yield natural flow over the remainder of the water year that is only around 78% of average. That would be much higher than last year’s May-September stream flow and an outcome that is very unlikely. But, even if this best-case scenario occurs, total water-year natural flow will end up at 77% of average and the sixth driest in the 1978-2022 record. It is just not possible to make up for 9 months of very low base flow (reflective of the long-term state of soils and aquifers) and a very low snowpack with spring and summer rain. Only several years of high snowpack will do that.

Can a cool, wet spring and summer increase end-of-summer reservoir levels? This one gets a definite “yes,” if precipitation is heavy enough. The previous two answers explain why overall water supply (natural streamflow) is not going to improve much over the next five months and also why the reservoir system will not fill much more than it already has. However, if rain is heavy enough and temperatures are cool enough, irrigation demand will be low because direct precipitation will make up a greater fraction of crop needs than average. In the Henry’s Fork watershed, precipitation makes up around 10-15% of irrigated crop needs in the watershed. A wet summer could move that up to 15-25%. That alone would reduce the need for diversion by 40,000-80,000 ac-ft. That’s 17-34% of the total volume of the Henry’s Fork watershed’s three reservoirs. In addition, continued rain will keep streamflow a little higher than it would otherwise be, in line with the 78% of average (vs the current 75% of average) referred to above. This would not necessarily limit reservoir draft but would keep natural flow water rights priorities a little higher, allowing irrigators to divert more water with their natural flow rights, on top of already limited storage rights they have. Thus, the best-case scenario would reduce the need for reservoir draft by 40,000-80,000 ac-ft. Compared with expected conditions, this would make the difference between Henry’s Lake, Island Park, and Grassy Lake combined ending up at 64% full instead of 39% full as expected. For reference, average carryover is 62% full. 

If this happened across the whole upper Snake River system, then reservoir carryover will be higher than it would have been without the spring and summer rain. This scenario adds very little to the water supply, but it reduces the need for reservoir draft. This has happened in the past, albeit not in a year with this poor of a water supply and low system-wide reservoir carryover. Years with heavy spring/summer rain that greatly limited reservoir draft were 2010, 2011 and 2014. Even last year, rain limited reservoir draft due to decreased demand. However, the cost in 2014 and 2021 was in poor hay and grain yields and quality for many producers.Bottom line: the best outcome possible this year is lower-than expected reservoir draft that will put end-of-season reservoir storage near average here in the Henry’s Fork watershed. Carryover in the upper Snake River system as a whole will still below average but better than the ~10% carryover expected at this point. For agricultural producers, the “best case” water situation will likely come at the expense of crop yields and quality this year but provide a greater chance of reservoir fill and higher storage allocations next year. For anglers, this “best case” will keep outflow from Island Park Reservoir lower than expected this year, leading to better water quality this summer and higher winter flows next year. The cost will be very low stream flows between Island Park Dam and Chester Dam for much of the summer, due to decreased need for high outflows from Island Park Reservoir but ongoing low

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Henry’s Fork, April 26th, 2002

A Message from the Henry’s Fork Foundation.

Hi all,

Fremont County is beginning work on N 3100E at Vernon today (4/26) and the road will be closed coming from the north until early afternoon. The boat ramp area can still be accessed on that road from the south side during that time.

Also, on Wednesday (4/27), crews will be conducting rock crushing work. Anticipate possible delays as heavy equipment moves in and out of the gravel pit and parking area.

I know this is lining up to be a very busy season. We will continue to stay in contact with the county with the primary goal of avoiding loss of access. Yellow Sally is working hard to park shuttled vehicles in a way that makes the most of limited available parking at Vernon. We will continue to ask non-guided anglers and river users to do the same. 

Thank you for all you do to lead by example when it comes to how this river deserves to be treated.

Jamie

Jamie Laatsch 
Communications and Outreach Director
Henry’s Fork Foundation

Good top water fishing can be had on the lower river during wind-free PMs as small stone flies,midges, BWO and March brown mayflies are active. Streamers are effective especially during unsettled weather and anywhere good overhead cover is present. Presenting large stone fly nymph patterns will become increasingly effective as we move into May.

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South Fork, April 26th, 2022

Flow discharge trace on the USGS gage aIrwin looks like a step function. as flow out of the reservoir is being increased in relatively small amounts. Currently flow at Irwin is 3580 cfs( raised ) , 4860 cfs at Heise, and 2410 cfs at Lorenzo. Look flow increases out of the reservoir to remain conservative but frequent until more information on run-off quantity is better known. These increases should not impact fishing success. Patterns such as streamers, rubber legs and various nymphs should work well.

The gate at the Burns Creek Road will be unlocked on May 1st. The road is closed during winter months to minimize human impacts on wintering wildlife.

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