Three Rivers Ranch’s Newsfeed

Thank you for visiting our newsfeed.  You’ll find the latest news on the Henry’s Fork of the Snake River, fishing news from around Idaho, and other news from Three Rivers Ranch.


Streamflow Still Above Average on Fall and Teton Rivers

Natural streamflow is still above average in Fall River and Teton River but below average in the upper Henry's Fork. Total watershed natural flow is 3,400 cfs, right on average for this time of year. Total watershed diversion is also average, at 3,300 cfs. Delivery of storage water from Island Park Reservoir began last week; current flow out of Island Park is 1,060 cfs, compared with the long-term average of 1,300 cfs for the date and last year's value of 1,420 cfs. Island Park Reservoir is currently 96% full, compared with 49% full at this time last year. Total Watershed Natural Flow at Long-Term Average Current natural streamflow is 1,044 cfs in Teton River above the Crosscut Canal, 1,109 cfs in Fall River, and 1,267 cfs in the upper Henry's Fork. Natural flow is above average in both Fall River and Teton River, reflecting above-average precipitation for the water year. However, natural flow is only 83% of average in the upper Henry's Fork subwatershed, reflecting slightly lower water-year precipitation there, as well as the cumulative effect of four years of drought on the deep Yellowstone Plateau aquifers that feed Big Springs, Buffalo River, Warm River, and other streams. The graph

Streamflow Still Above Average on Fall and Teton Rivers 2017-07-22T08:10:25+00:00

Current water temperatures through the Ranch and Pinehaven reaches

Headlines: Water temperatures through the Ranch have been on the warm side. Temperature has climbed above 71˚F for a couple of hours each day over the last week. However, daily maximum temperatures have not been deadly for rainbow trout, and only a few daily averages have been at the lowest levels that would stress fish.  This is the same pattern we saw in both 2015 and 2016, when streamflows were about 800 cfs higher than current flows. Thus, releasing additional water from IP dam does not result in significantly cooler summertime water temperatures, but we do know that increasing flow out of Island Park Dam decreases water clarity and will reduce winter flows, which reduces survival of juvenile trout next winter and hence recruitment of 2-year old fish into the population in 2019. There have been some concerns expressed to us about water temperatures being too high through the Ranch section of Harriman State Park. This blog discusses what our water quality monitoring data collected from Pinehaven (just below the Ranch reach) can tell us about current conditions in the context of trout habitat requirements and recent in-house statistical analyses. Figure 1 displays water temperature data taken every 15 minutes

Current water temperatures through the Ranch and Pinehaven reaches 2017-07-15T08:06:56+00:00

Wilderness Wandering

The past six weeks have flown by. I’ve spent the time working, exploring, and adventuring around, enjoying every minute of the wild west that I get to experience. My original project was to develop a mobile app for android for the Henry’s Fork Foundation website. Due to the limited time that I have and the difficulty of application development, I proposed an alternative project-  a revamp of the Foundation’s mobile website. This was deemed a good option and I spent a few weeks learning CSS and HTML; the languages of web development. The project is coming along nicely and I will definitely have it finished by the end of my time here. Check out a preview of the homepage.  Aside from programming, I have also been assisting in the field work that the Foundation performs. I’ve gotten to help taking water samples at a variety of sites along the Henry’s Fork and assisted in the creel and economic value surveys that are being administered this year.   My free time has been focused on getting outside as much as possible. This got much easier when my roommate, the Stanford intern, Zac, arrived. I had been in desperate need of a

Wilderness Wandering 2017-07-15T08:07:56+00:00

Gill Lice Study 2017

  Just a quick reminder that we are continuing our collaborative gill lice study in the Upper Snake River region through 2017 and we need your help!   Click on these links if you’d like to: Learn about gill lice Learn about the 2016 gill lice summary Help collect data (data sheet) Submit your data   If you forget to print off a data sheet, HFF has put up red document boxes with data sheets at Box Canyon, Log Jam, Mailbox, Harriman visitor center, Osborne Bridge, Stone Bridge, Ora Bridge, Vernon Bridge, and at the launch below Chester Dam. Feel free to take one and return the sheet to the HFF office (512 Main St., Ashton, ID), local guide shop, or submit the information online here.     Thanks in advance for your help monitoring the fishery!   Additional Information If you have questions, comments, or concerns, feel free to contact me at or 208-652-3567.  

Gill Lice Study 2017 2017-07-11T20:07:25+00:00

Water Supply Still Strong Well Into July

Total natural streamflow in the Henry's Fork watershed is 122% of average and 2,500 cfs greater than irrigation diversion, which remains slightly below average. No water has been delivered out of Island Park Reservoir yet this season, compared with 40,566 ac-ft (30% of reservoir capacity) last year at this time. Island Park Reservoir outflow will remain roughly equal to inflow until release is needed to meet irrigation demand, which now looks to be another week out. Streamflow Above Average; Diversions Below Average Despite the arrival of the hottest weather of the summer this past week, showers and high-elevation snowmelt continue to maintain above-average streamflow in Fall River and Teton River. The cumulative effects of above-average precipitation since the beginning of the water year last October are also helping to keep streamflow above average and irrigation demand below average. Current natural streamflow in the watershed is 5,690 cfs, compared with an average of 4,648 cfs, and with paltry 2,334 cfs at this time last year. Meanwhile, total irrigation diversion is around 3,000 cfs, a little below the long-term average. The graphs below illustrate total supply and total diversion. No Delivery Needed from Island Park Reservoir Yet The graph below shows that

Water Supply Still Strong Well Into July 2017-07-07T20:08:03+00:00

More Showers Keep Water Supply Above Average

Most locations around the watershed received around one-half inch of rain this week. Natural streamflow supply in the watershed is 7,000 cfs, well above average for the date and well above diversion rate, which is 3,000 cfs. Delivery of storage water from Island Park Reservoir will not be needed until at least July 5. Showers Buy Another Four Days of Good Streamflow Although not as heavy as the rainfall received during the week of June 12, this week's showers were heavy enough to increase streamflows again for a few days. Showers began on Monday evening and lasted through Thursday evening. Notable precipitation totals around the region were 0.9 inches at the Island Park SnoTel site, 0.5 inches at Ashton, and a whopping 1.5 inches at the Crab Creek SnoTel site in the Centennial Range west of Island Park Reservoir. This resulted in a large increase in inflow to Island Park Reservoir, which added a bonus 800 ac-ft to an already-full reservoir and increased outflow a bit as a small amount of flow spilled over the spillway. Streamflows watershed-wide this morning (June 30) were the same as they were on Monday morning (June 26), so the rain bought an additional four

More Showers Keep Water Supply Above Average 2017-07-01T08:11:07+00:00

Rain Boosts Water Supply as Peak Irrigation Season Arrives

Over two inches of rain fell in parts of the watershed last week, providing another peak in streamflow in Fall River and Teton River. Total watershed streamflow remains around 8,000 cfs, compared with irrigation diversion of 3,000 cfs. Island Park Reservoir will remain full until delivery is needed to meet irrigation demand, which now looks to be at least two weeks away. Outflow from Island Park Reservoir is being reduced frequently to keep pace with natural streamflow recession in the upper Henry's Fork. Rain and Cool Weather Provide Bonus Supply The week of June 11-18 brought cool weather, above-average precipitation, and even some snow at high elevations. The table below summarizes climate for the week. The resulting rain and new snow extended good streamflows out at least another two weeks. The graphic below shows total natural streamflow in the watershed, which remains around 8,000 cfs. This is about 2,000 cfs above average for the date and far above last year's 3,000 cfs. Teton River and Fall River continue to increase, even as the upper Henry's Fork continues to recede. Total watershed diversion dropped from over 3,000 cfs back to around 2,500 cfs during and after the rain, but it has

Rain Boosts Water Supply as Peak Irrigation Season Arrives 2017-06-24T08:11:18+00:00

Henry’s Fork Reservoir Storage and Streamflow at Peaks

Week of June 5 highlights: Island Park Reservoir, Grassy Lake and Henrys Lake have all filled. Natural streamflow in the watershed is around 9,500 cfs and at its final peak for the season. Total watershed-wide irrigation diversion is around 3,000 cfs, right at average for this time of year. Outflow from Island Park Reservoir is being set to keep the reservoir full. Only small changes are anticipated over the next week, and outflows should remain around 950 cfs plus or minus 150 cfs, depending on rain. Delivery of water from Island Park Reservoir in excess of inflow is not expected to be needed until early July. Water Supply Better than Average and Double Last Year's The graphic below shows total Henry's Fork watershed surface-water supply, which is combined natural streamflow in Henry's Fork at Ashton, Fall River at Chester, and Teton River upstream of the Crosscut Canal. Natural streamflow is essentially the water that would be in these streams in absence of reservoirs and diversions. It's easy to see that current supply is better than average by about 20% and is twice that of 2016 at this time. Although the natural streamflow peak we experienced back in May was slightly

Henry’s Fork Reservoir Storage and Streamflow at Peaks 2017-06-10T08:08:35+00:00

2017 Box Canyon Rainbow Trout Population Estimate

Every year the Idaho Department of Fish and Game (IDFG) conducts multi-pass electrofishing surveys on various river reaches in the Upper Snake River region. These surveys provide valuable information on abundance, age-class structure, fish size, and species composition within the fishery. Most recently, IDFG finished its annual survey in the Box Canyon reach of the Henry’s Fork. This post will highlight and explain some of the results of that survey.   Highlights Abundance estimate for fish greater than 6 inches in length: 2,913 Rainbow Trout per mile 2016 abundance estimate: 2,264 Rainbow Trout per mile Average length 11.5 inches 2016 average length: 10.5 inches Max length 20 inches Max length from 2015-2017: 20 inches Size structure for 2017 is fairly uniform with a median size of 12 inches Abundance estimate of age-2 class fish was higher than predicted (see below for more details) Link to IDFG brochure   Multi-pass electrofishing Electrofishing is a non-lethal technique commonly used to sample fish in both large and small river systems. In small rivers (first and second order streams), multi-pass surveys can be conducted where crews block off a section of river, perform multiple passes (typically three passes), and remove fish from the reach

2017 Box Canyon Rainbow Trout Population Estimate 2017-06-08T20:07:05+00:00

Invasive Species

Two weeks ago salmonflies started showing up on the lower Henry’s Fork. Once the word got out, fisherman flooded from near and far for the opportunity to catch big fish on big dries.  More than once I heard the classic “you don’t need to bring a boat, you can walk down the river on all the other ones” line. While the river was busy, it wasn’t that bad. After seeing lines of cars and trailers at Ora, Vernon, Chester, etc. with license plates from as far away as Michigan (there were probably plates from further but I was more focused on catching big Browns than taking inventory of license plates), it reminded me that we all need to be diligent about making sure we don’t transfer invasive species as we travel from river to river and state to state looking for the next hatch and the hot bite. Here are some steps you can take to minimize the chance you inadvertently transport an invasive species1: Before leaving any waterbody, always inspect equipment (boats, planes, trailers, decoy anchors, SCUBA gear, and lures) for visible plants and animals. Remove this material on site. Carefully check places that are still damp. Dispose of

Invasive Species 2017-06-06T20:06:22+00:00