Boise Valley Fly Fishers
Since 1971



News and information on BVFF conservation projects

  • 30 Oct 2023 4:05 PM | Troy Pearse (Administrator)


    November is peak spawning time for Brown Trout on the Owyhee and Boise River. Please watch for redds as you wade and avoid walking through them. Browns like to build their redds in 1-3 feet of slower moving water and love tail-outs and next to gravel banks. Here is a look at brown trout redds on the Boise River and a short YouTube video on how to spot redds when you are wading.

    The high water on the Boise this spring moved a lot of gravel and we expect to see Browns spawning throughout the river this Fall! If you are interested in participating in a Boise River Redd Mapping float later in November and December, please reach out to Troy Pearse at Volunteers should have good rowing skills as the water is skinny and there are downed trees to contend with.  Float days will depend on weather conditions as we need sunny weather to see the redds.


    We have hired HDR Engineering in Boise to help us with the Floodplain Development Plan that Malheur County Planning and Zoning is requiring. We met with them last month and have a path forward—it will just take some time to calculate the hydrological impacts of adding the gravel. Many thanks to those who bought $Greenbacks to help fund this augmentation. If all goes well we will be adding gravel this Spring!


    BVFF has been working with IDFG on restoring year-round flows to two side channels behind Expo Idaho that were closed off by the high runoff from Snowmageddon. IDFG is leading the effort and is getting great support from local city and permitting agencies. This fall IDFG monitored the side-channel as it dewatered and confirmed that trout fry are getting stranded. They did a “fry rescue” in a couple of pools and plan to monitor other pools to see if the fry make it through the winter or not. BVFF will be assisting by helping monitor and measure water in those side channels over the winter.


    Earlier this month, a group of volunteers from BVFF and WFFI did a river cleanup at our Side Channel Gravel Augmentation site. The group wadered-up and pulled trash out of the river as well as cleaning up the river banks.

    A BIG THANK YOU! to those who volunteered: Elizabeth Pollard, Lisa Sventes, Jose DeSousa, Barbara Emerich, Wayne Frederick, Brian Martin, Frank Jenks, Doug Olds, Mike Stahl, Matt Housel, George Butts, Jack Truschel, Ray Arguerllo, Tim DeMarco, Barbara Wagner, Mary Black, Wanda Shearer, Brenda Schwartz, Jane Mc Kevitt, Mallory Wilson, Karen Shein, Serrita Beauleu, Joe Schwartz, John Bourne. And THANK YOU! to Johnny Rogers for his efforts to coordinate and lead the cleanup. 

  • 30 Sep 2023 4:29 PM | Troy Pearse (Administrator)

    Side channel habitat is one of the most important factors for a healthy wild trout population. They provide good spawning habitat for adult trout and more importantly good rearing habitat for young trout—the reduced flows in the side channel are much easier for the young trout to handle than the main river and the side channel’s extra bankside woody-cover gives young trout a place to hide from birds and other predators. Side channels that flow year-round are the most important because they provide shelter during the winter which is critical for young trout to survive into adulthood.

    The Boise River through town is an urban tailwater river which over time has reduced its side channel habitat and has become a limiting factor for wild trout reproduction. Idaho Fish and Game does trout fry surveys in the Fall that show the Boise River has a healthy population of wild rainbow and brown trout. And their surveys show that trout fry populations are 7-10 times higher in the side channels than the main river. Unfortunately, there are very few side channels on the Boise River that flow in the winter.


    Two years ago the Intermountain Bird Observatory led a Boise River side channel restoration project at the Diane Moore Nature Center, which is located a couple of miles downstream of Lucky Peak Dam—above Barber Dam. The side channel was engineered to provide good habitat for fish and wildlife including plenty of woody cover for small fish to seek shelter.

    BVFF got involved in the Diane Moore Nature Center side channel project in 2022 and helped design and install Trout Habitat signs along the side channel, followed by building an Angler Access at the site. BVFF has been thrilled to be involved in this project because it supports all three of our mission goals: Fly Fishing Conservation, Access, and Education.

    The first spring the side channel had water (2022) there was limited trout spawning observed, likely because Boise River flows came up late. And in the second season (2023) we had high spring flows making it impossible to see if trout were spawning there. This summer while walking the side channel we saw small “minnow-sized” fish but were not able to identify them. So, we decided to stick our heads underwater to see what we would find! Our goal was to see how trout are using the new side channel and get an idea on numbers and distribution.

    A snorkel survey is a standard way to count trout fry. We talked with Tracy Hillman, Senior Ecologist at BioAnalysts who specializes in trout habitat restoration, and he talked us through the process and gave us a great document on how to do a snorkel survey. August 29th, volunteers from Boise Valley Fly Fishers (Troy Pearse, Klaus Kissman and Dennis Moore) did a fry snorkel survey in the new side channel at the Diane Moore Nature Center. Even though it was summer, we wriggled into wetsuits to protect us from the extended cold-water exposure and debris in the water. We started at the bottom and had 2 people snorkel upstream side-by-side counting the fish they saw. This was our first snorkel survey and we didn’t know what to expect, but we were flabbergasted when we went underwater and started seeing rainbow trout fry everywhere! The side channel is about 0.4 miles long and we snorkeled sections from the bottom to the top—covering about 3/4 of the total length—counting over 2,000 trout fry which were evenly distributed throughout the side channel!

    A large part of the success of this side channel is the extra effort made to add woody-cover: There are numerous downed trees and log-piles in the side channel which give the trout fry a good place to seek shelter. Observing the trout fry underwater was a great way to see this as many of the fry were tucked under pieces of wood in the water with some large pods of trout fry by logjams.

    The vast majority of trout in this stretch of water are wild, as Idaho Fish and Game does not actively stock this section of river. We are excited about the potential of the side channel to increase the population of wild rainbow trout in this section of the Boise River, which is isolated between two dams: Barber Dam below and the New York Canal Diversion Dam above.

    The side channel has restricted inflows in the winter but talking with Greg Kalteneker (who lead the side channel project), the side channel was designed to connect with groundwater and last winter the water station installed on the side channel showed it flowed at 1cfs - 3cfs. Hopefully that will be enough inflow to keep it from freezing. We plan to check it a few times this winter to see how it is flowing and if it is icing over.

    IDFG Historical Fish Stocking Records


    As good as the trout population is on the Boise River, it is not reaching its full potential. One of the best things we can do for the Boise River wild trout population is increase the number of side channels that have year-round flow for trout spawning and rearing. BVFF is working with Idaho Fish and Game to restore winter flows to two side channels behind Expo Idaho that were cut-off from winter flows after Snowmageddon in 2017. Idaho Fish and Game will be on-site at these side channels this Fall when Boise Rivers flows drop. They will be documenting the side channel dewatering and evaluating possible trout-fry stranding, including possibly rescuing stranded trout fry and moving them to the main river. BVFF is volunteering to assist them. Stay tuned for more details and sign up if you are interested. The current estimate for flow-reductions on the Boise river is the morning of Monday October 15th, but that time could change.

    UPDATE 10/5/2023: The Boise River dropped earlier than expected. IDFG sampled the side channels and identified several pools with stranded trout fry and thousands of minnows.  They electrofished a couple of pools and rescued several dozen trout fry. We will help them monitor the pools over the winter to see if they ice-over and IDFG may electrofish them in the spring to evaluate overwinter survival.   

  • 10 Aug 2023 9:42 AM | Troy Pearse (Administrator)

    I spent the day at the Diane Moore Nature Center and Barber Pool with Brian Martin and Dennis Moore, reviewing the side channel and evaluating trout spawning habitat in the Barber Pool. We even did a little fishing!

    When we arrived at 9am there were PMD Spinners, trico spinners and some caddis on the water, and there were a couple of anglers out fishing below the NYC Diversion Dam. We did a little seining and found good numbers of mayfly nymphs, some green netspinning caddis and a cranefly larva.

    At the current flow of 630cfs, the water was up to the bottom stone on our Angler Access and it was easy to get down to the river.  The new side channel is doing well and was widened a bit from the high flows. The banks are very sandy, making the side channel bottom sandy in areas but we found several areas with spawning size gravels. The high water moved the woody debris around, but there is still excellent woody cover and we saw trout fry scattered throughout the side channel.

    Floating down into the Barber Pool, we found 4 areas that had large deposits of gravel that look to be great trout spawning habitat. Once you get into the Barber Pool the water velocity slows down considerably and deepens. There is some bank-side woody cover that is available to fish at the current flows of 630cfs, but it may be out of the water in the winter. Water clarity in this section is much better than in town and you can see 6-8 feet.

    There are 2 mandatory portages on the float from the Diane Moore Nature Center to Barber Park. The first is Barber Dam, which you portage on river right. There is a set of landscape timber stairs and then a long, but well developed portage trail around the dam site. The second is Eckert Diversion, which you also portage on the right. That portage trail is much rougher with boulders and tree roots to navigate through. Definitely best for smaller, lighter craft such as a canoe or kayak.

    This Fall we will be wrapping up our angler access project, including adding hillside retaining along the path; Filling in the lower stone steps with roadmix; and Installing signage. Stay tuned for more details.

    Troy Pearse
    Conservation Director
    Boise Valley Flyfishers

  • 03 Aug 2023 7:33 PM | Brian Martin (Administrator)

    Ada County Parks & Waterways Master Plan Focus Group

    Executive Summary of BVFF Positions

    For the Focus Group Representatives

    March 7 and 8, 2023

    Key Messages to Convey

    A. BVFF is a non-profit, member organization that promotes fly fishing through our core missions of:

    • Access

    • Education

    • Conservation

    B. Overarching Position:

    Add fishing to the Ada County Parks & Waterways Master Plan as a major recreational activity and consider the impact to fish and anglers when making changes to the master plan, including prioritizing protecting and improving fish habitat that will improve fishing in the Boise River and other public waterways within Ada County

    C. Reflect in the Ada County Parks & Waterways Master Plan:


    BVFF Specific Requests to be Included in the Master Plan of Ada County Parks & Waterways:

    A. Protect wild trout in the DMNC/Barber Pool area by supporting catch and release regulations/size limitations, placing monofilament collectors to protect bald eagle and other wildlife, and providing wild fish habitat protection and enhancement. Also, provide and maintain public restrooms.

    B. Maintain the Barber Park to Ann Morrison Park reach for unskilled water users and improve/provide the services necessary to protect the river corridor from the negative impacts of heavy traffic by: Partnering with Boise City and BVFF to add educational signage at access points for anti-litter, provide trash bags at all access points, provide restrooms along the corridor with signage as to location, provide trash receptacles at all takeout locations, and place monofilament collectors at fishing access points. In addition, partner with Boise City, IDF&G, BVFF and other organizations to repair and protect riparian areas and improve fish habitat through protection and management of side channels, promoting woody cover, providing spawning gravel, and increasing winter flows.

    C. Oppose expansion of any unskilled water craft and removal of wild fish habitat or woody cover from Ann Morrison Park downriver to Ada County Line. If expansion is done, it should be for skilled water users only - Place warning signage at any access points stating that this section of river is for SKILLED BOATERS ONLY and is dangerous to unskilled water users

    D. Along the Snake River corridor, support the development of a Regional Park and provide anti-litter signage, trash receptacles and mono collectors

    E. Support wild trout habitat including year-round side channels, woody cover, spawning gravel, and increased winter flows in the Boise River to improve fish habitat for spawning and rearing for higher recruitment of fry

    F. BVFF would like to partner with Ada County on preventing and cleaning up litter in the river by:

    1. Leveraging anti-litter signs from the Diane Moore Nature Center (BVFF developed with IDFG) to major access points, such as Barber Park

    2. Work with BVFF to add mono collectors in key locations where mono is a problem, such as at Barber Park where steelhead are released

    3. Encourage organizations to join the Living Lands Adopt-a-River program. Support BVFF adding an Adopt-A-River sign on the Boise River downstream of Garden City Limits

    Areas of Concern:

    A. Increase in motorized jetboat use on the river at Eagle Island State Park into the Boise reach which is hazardous to fishers

    B. The conversion of Eagle Island State Park to an Ada County Regional park might include increased unskilled floater access. Any conversion from State Park to County Park that negatively impacts trout habitat is opposed by BVFF

    C. Rampant trash in the Swan Falls area. Also, monofilament line being left behind by anglers. This is a raptor nesting area, and they might use the monofilament in their nests creating an entanglement hazard

    D. Boise River winter flows are too low to support side channel spawning and rearing habitat

    E. Fishing is not listed as a major recreation activity in the current master plan. According to the Outdoor Industry Organization, nationally fishing is the third most popular outdoor activity, after jogging and hiking.

    ( and we expect that fishing may rank even higher in Idaho. The Boise River through town is a blue ribbon trout stream that is gaining national attention through fishing magazines. Idaho Tourism data shows that fishing is one of the top activities for tourists at twice the national rate

    F. The Eagle Island (including Eagle Island State Park) north and south channels are premium trout spawning and rearing habitat and should be left in their natural wild state

    Go to for more information about our organization.

    Thank You for inviting us to participate!

    BVFF Board of Directors

  • 02 Aug 2023 6:06 PM | Troy Pearse (Administrator)

    Members from the Boise Valley Fly Fishers Board of Directors attended Flood District 10's Retirement Celebration for Mike Dimmick.  Bill Clayton, Chairman of the Flood Department's Board recognized Mike for his efforts to join transform the Flood District and connect with the community, including calling out his work with Boise Valley Fly Fishers.  Mike has been instrumental in our two Boise River gravel augmentations, both in planning the activity and helping us wade through the permitting process as well as coordinating the effort with the Flood District's winter maintenance cycle so we could utilize their heavy machinery to move the gravel into the river. 

    After the first gravel augmentation we asked Mike if the excavator driver knew how to identify and avoid brown trout spawning redds/nests. Mike said no, but they would like to be able to do that, if we could show them how.  From that we developed our Boise River Brown Trout Redd Protection Program which provides the flood district's excavator driver maps of the locations of the redds which they have been able to use to avoid the spawning zones.  

    As a token of our gratitude for all of Mike's help, the BVFF Board of Directors presented Mike with a handmade fishing net with his name engraved along with a Lifetime Membership to the club.  For more information about Mike's work at the flood district, see this article in the Capital Press .

    BVFF is already working with the new District Manager, Mark Zirschky, who is very supportive of our efforts and wants to continue working with Boise Valley Fly Fishers on Trout Habitat Improvement and Protection on the Boise River.

    (Steve Stuebner Photo)

  • 31 Jul 2023 11:51 AM | Troy Pearse (Administrator)



    The Boise River experienced high runoff this spring with flows staying above 4,000cfs for 2 months and reaching “bank full” flows of 6,000cfs for 2 ½ weeks. High runoff is a healthy part of the lifecycle of a river as it helps clean the bottom of accumulated debris and improves trout spawning habitat by redistributing smaller gravels. On a naturally flowing Freestone river, high water refreshes trout spawning habitat with new smaller gravels from upstream, however, on a Tailwater river like the Boise River, these new smaller gravels get trapped upstream behind the dam (Lucky Peak) which keeps them from refreshing the trout spawning habitat below the dam, which is why BVFF and TU have been doing gravel augmentations in the Boise River.

    At "bank full" flows, the Boise River does harvest some smaller gravels from the banks and islands which improves trout spawning habitat in some places. We will be able to quantify that this fall when we do our annual Brown Trout Redd Counting and Mapping project. It will be very interesting to see how the high-water event impacts brown trout spawning, but my expectation is we will see an increase in the number of redds on the Lower Boise River.  Watch for our Brown Trout Redd Surveys this Fall and come see for yourself!


    In February of 2023 BVFF added 15 cubic yards of spawning gravel on the inside bend of a side channel of the Boise River. On a normal runoff year we would expect most of the gravel to stay on that inside bend, but on a high water year like 2023 Mother Nature is going to relocate it downstream (Mother Nature knows what she is doing and is very good at placing it in locations that are suitable for trout spawning). The below photos show the gravel augmentation location at winter flows (250cfs), in May at 6,000cfs, and then in August at 650cfs. At 6,000cfs you can see water coming into the side channel across a wider area, but the river velocity is still significantly less than the main river channel and there are plenty of soft-spots behind the woody cover for trout to shelter.


    Flows on the Boise River recently dropped to 650cfs (a very fishable flow!!) and I walked the side channel to see where Mother Nature decided to relocate our gravel. The good news is that the gravel is still in the side channel and Mother Nature left it in good locations for trout to use for spawning! The figure below shows the side channel, the gravel augmentation location, and where new gravel has accumulated. It is impossible to identify our gravel from natural gravels, but I can say that there are significant new deposits of small gravel about 500 feet downstream of our augmentation-zone, below where the side channel has an “S Curve”. This is a typical location for the river to drop gravel as they like to drop it on the inside bend where water velocity is reduced, which is one reason why sinuosity is important to a healthy river (sinuosity is a measure of how many curves a river has). And because the flows were so high, some gravel was dropped above the normal summer high water mark, leaving a kind of “bathtub ring” in some locations. This bathtub ring effect can also be observed in the entry area of the side channel from new gravels being dug up from the water spilling over the banks.


    As a part of our trout habitat improvement work on the side channel we worked with IDFG and the Boise Flood District to incorporate woody cover to give trout fry shelter (shown in the figure above and the photo to the right). Woody cover is just as important to improving the trout population as spawning gravel. Early observations this summer have shown some rainbow trout fry in the side channel and we hope to join IDFG on their annual Trout Fry Survey later this fall to see how the juvenile trout handled the high flows. The large pieces of woody cover that were anchored are still in place but some of the smaller pieces were carried away by the high flows and could use to be refreshed and anchored.

    The high water event left some debris at the entry to the side channel and broke through the nearby New Dry Creek diversion dam, dropping the water level and reducing flows into the side channel. At 650cfs we are getting about the same inflows to the side channel as we did at 250cfs last winter. We will be doing some maintenance on the side channel in August to help clear debris to improve inflows and improve the woody cover. If you are interested please sign up for the event posted on our website


    Below are some examples of how Mother Nature “terraformed” the side channel and where she moved our gravel. There is now good spawning gravel in the S-Turns and the tail-out below that. Before high water there was a 100' long narrow trench with a bottom of large cobble. That trench is now filled with spawning gravel and is an awesome long spawning run!  Some of these locations are more suitable to rainbows to spawn at higher flows and others are perfect for brown trout spawning at lower flows.  We will continue to monitor the side channel for spawning activity and report what we see.


  • 31 Jul 2023 11:24 AM | Brian Martin (Administrator)

    Please welcome BVFF member Johnny Rogers as the new Leave It Better Lead. He replaces Brian Martin who has moved into the role of BVFF president. Johnny has been a member since December of 2021 and has volunteered for many projects including river cleanups, Diane Moore Nature Center access, and Expo 2023 where he posed as Eddy Trout.

    Johnny Filling The Net On The SF Boise 2023

    The Leave It Better Lead is responsible for coordinating our Spring and Fall "Real" Boise River Cleanups, informing us of partner organization river cleanups on the Boise and Owyhee rivers, and assisting with the Adopt-A-Stream program through Snake River Waterkeeper.

    Thank you, Johnny, for volunteering for this Conservation mission role! We're here to help in any way you need.

  • 03 Jul 2023 10:17 AM | Jim Kazakoff (Administrator)

    A bill to permanently protect fish and wildlife on Owyhee River Canyonlands was introduced by Oregon legislators on June 8th.  The bill is supported by a coalition of ranchers, native tribes, anglers, hunters, and conservation groups, and will protect approximately one million acres of fish and wildlife habitat.  This Trout Unlimited article describes the bill and the support that will be needed to get it passed.

    Trout Unlimited has also released a short film, produced by the Owyhee Sportsmen Coalition on fishing the Owyee River, which can be viewed HERE.

  • 21 May 2023 1:37 PM | Troy Pearse (Administrator)

    With the Idaho General Trout Season Opener approaching, people are wondering when the Boise River System will be fishable. The Boise River Reservoirs (Lucky Peak, Arrowrock and Anderson Ranch) are managed primarily for irrigation and their objective is to capture the maximum amount of water in the reservoirs. They release water from the reservoirs as needed to capture the runoff and have “rule curves” they use to manage reservoir outflows. Looking at the Bureau of Reclamation Hydromet site you can see that the reservoirs typically reach their peak levels the 3rd or 4th week of June. This means the river flows below Lucky Peak and Anderson typically drop to their normal summer levels around that same time—a bit later on high water years.

    Our Boise Tailwater rivers tend to come into shape quicker than the Freestone sections because of how they are managed. While the MF of the Boise will continue to run high well into July the SF of the Boise below Anderson Ranch and the Main Boise River below Lucky Peak will drop into shape quicker.

    Here is a look at this year’s runoff flows on the South Fork, Middle Fork and Lower Boise Rivers compared to similar years of 2011 and 2019. Based on those years, the SF Boise will be running very high when the season opens and won’t drop to normal summer levels until early July. In 2011 and 2019 the Main Boise river dropped to normal summer flows by early July. This year we had more space in the reservoirs so it is possible that flows on the Lower Boise will stabilize a bit sooner in late June.

    The rivers are running high and cold and are dangerous to wade. Do not attempt to wade the SF of the Boise River until flows drop below 600cfs this Fall. Same goes for the Boise in town. Make sure you check BVFF’s Local Waters page for the latest conditions, including streamflows, water temperature and reservoir/boat ramp levels.

  • 06 May 2023 9:30 AM | Troy Pearse (Administrator)

    This winter’s excellent snowpack is turning into runoff and our local rivers are running high. Spring runoff’s impact on river flows, both timing and magnitude, depends on whether the river is a Tailwater River (below a dam, like the Lower Boise River through town), a Freestone River (naturally flowing like the Middle Fork of the Boise River) or a Spring Creek (like Silver Creek). Spring river flows can be dangerous, so it is important to know the river before you venture out. Both the Lower Boise River in town and the South Fork of the Boise River become dangerous to wade when flows rise above 600cfs. Flows on the Owyhee below the dam have started to come up and with the reservoir filling should reach normal 200cfs flows this summer, which is a very wadable level. Checking river flows on BVFF’s Local Waters page is an important part of planning your fishing trip.


    Our Tailwater rivers are primarily managed for irrigation and flood control and spring flows below the dam depend on both the snowpack and the reservoir carryover from the previous year. If you have a good snowpack but low carryover—like the Owyhee drainage this year—then you aren’t likely to have high river flows below the dam. But if you have a good snowpack and good reservoir carryover—like the Boise drainage this year—then you are going to see high spring flows.

    Dam managers are currently draining water in the Boise reservoirs (Anderson Ranch, Arrowrock and Lucky Peak) to make room for our great snowpack. The Lower Boise River in town is running high and expected to flow at 5,000cfs to 6,500cfs through June. Flows like this are not uncommon, Figure-1 shows how often we’ve had high flows over the last 25 years, which includes 13 years over 5,000cfs and 9 years when we reached or exceeded “bank full” conditions (6,500cfs or higher).

    The South Fork of the Boise River is also running higher than normal and we will likely see flows reach 4,000cfs – 6,000cfs in May with continued high flows when the season opens Memorial Day weekend, so make sure you check BVFF’s Local Waters page before you go.

    High flows on a Tailwater river tend to happen earlier in spring in order to make room in the reservoirs for the anticipated snowmelt. It is a calculated game of letting out just enough water to avoid flooding while capturing the maximum amount of water in the reservoirs. They are pretty good at managing flows to avoid major flooding—although it has been close a few times. Figure 2 shows runoff from the 2017 Snowmageddon year, and while flows on the Lower Boise River did exceed “bank full” flows of 6,500cfs and caused some minor flooding, the natural (undammed) combined flows of the N.F., M.F. and S.F. of the Boise rivers reached peaks of 15,000cfs – 24,000cfs which would have been a major flood event for Boise.

    The Owyhee reservoir was sitting at 35% of capacity this winter (significantly below average) but has started to fill and is rising fast, as shown in Figure 3. Over the last 25 years the Lower Owyhee River has seen 7 years with high flows, but even though the Owyhee drainage had an excellent snowpack this year, Owyhee Reservoir had so little water carryover that it is unlikely that the lower Owyhee river will see high flows, which is too bad because that river could really benefit from higher flows to clean sediment left by side stream blowouts.


    Spring flows on freestone rivers like the M.F. Boise and the Wood River are 100% dictated by the snowpack and the weather. A quick warmup on a high snowpack year results in the highest flows, and with our high snowpack and cool spring there is likely to be some flooding when it finally warms up, so stay tuned to the BVFF Local Waters page and be careful. Spring Creeks can be a good place to escape high flows because they are not fed by runoff (make sure to check fishing regulations before you go to ensure it is open). Spring Creeks, such as Silver Creek, don’t see as significant range of flows, but high and low snowpack years do impact groundwater springs which changes flows some.


    High spring flows are very healthy for a river: They clean out accumulated sediment which improves the river’s carrying capacity and keeps it connected to the floodplain. High flows clean and redistribute gravel for trout spawning, although rivers below a dam don’t get new gravel from upstream because it gets trapped behind the dam. Over time this limits the amount of wild trout spawning habitat, which is why we recently added gravel to the Boise River and are working to add gravel on the Owyhee. Luckily the S.F. of the Boise has some good tributaries that bring in gravel when they blow-out which periodically refreshes the spawning gravel on that river.

    Removing accumulated sediment is good for insect life as well. For example, after high flows on the Owyhee, caddis and stonefly populations improve although some slow water insects like callibaetis mayflys get swept away and take a few years to recolonize. When planning your summer fishing trips keep in mind that high water years usually delay hatch timing because of the colder runoff, compared to low water years when rivers warm up sooner which accelerates hatches. For an example of how runoff impacts hatches see this month’s Bug Corner.


    As flows come up the Lower Boise River stays “in bank” until the river reaches 7,000cfs and the water gets very fast, compared to the Lower Owyhee River which comes out of bank quickly, spreads out and stays at a much lower velocity. High velocity flows are difficult for juvenile trout, especially brown trout fry that recently emerged from their redds/nests in March. Side channels provide refuge for trout to escape the hurtling velocities of the main river. Figure 4 shows the “BVFF Side Channel” on the Boise River at winter flows and at high runoff flows. While the main river is raging with little place for trout to hide, you can see numerous areas of softer water and good woody cover in the side channel where trout can hold. The location of our gravel augmentation is circled in the photo: We intentionally added it on an inside corner to protect it from higher flows and it will be interesting to see how much of it stays put and where Mother Nature decides she wants to relocate some of it. We will volunteer with IDF&G on their Fall Shoreline Fry Surveys again this Fall to evaluate the side channel gravel and see how the juvenile trout population fared.

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The Boise Valley Fly Fishermen, Inc is a non-profit corporation organized under section 501(c)(3) of the Internal Revenue Code, incorporated in the State of Idaho
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