Boise Valley Fly Fishers
Since 1971



News and information on BVFF conservation projects

  • 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.

  • 01 May 2023 2:25 PM | Troy Pearse (Administrator)

    The Owyhee River below Owyhee Reservoir in Oregon is one of the best brown trout streams in the West and a favorite place for anglers from the Treasure Valley to Fish. But as good as it is, the Owyhee River could even be better if it had more trout spawning habitat.

    Boise Valley Fly Fishers (BVFF) has worked with the Oregon Department of Fish and Wildlife (ODFW) to monitor brown trout spawning since 2016. The brown trout population and number of redds varies year to year, but one common theme every year is that most of the brown trout spawning happens in the top 5 miles of river and very few fish spawn downstream by the Owyhee River Ranch even though the water quality and insect population in that reach is very good.

    In Fall of 2021 we began an effort with ODFW to do a gravel augmentation to improve the spawning habitat on the lower reaches of the Owyhee River. We have determined that the run below the intermittent Sand Hollow creek has the right water depth and velocity for trout spawning but it lacks the smaller gravels needed. By adding gravel to this location trout will have a productive place to spawn which will improve the trout population in the lower reaches of the river.

    BVFF’s gravel augmentations on the Boise River in Idaho have been very successful and we have high expectations for the potential improvement to the trout population on the Owyhee River. We have secured partial funding through grants from Fly Fishers International and ODFW, but the cost of doing a large gravel augmentation at a remote location is considerably higher than our small gravel augmentations on the Boise River. The costs are also higher for doing any stream alteration work in Oregon because of additional permitting.

    We are raising money for the gravel augmentation through our internal club fundraiser “Greenbacks For Redds” and through the Idaho Gives Campaign which runs May 1st through May 4th, 2023. Please consider helping us reach our gravel augmentation goal by contributing to the Idaho Gives Campaign. Donations made through Idaho Gives will be generously matched up to $1,000 by St. Clair Contractors, who has been a great partner in helping with BVFF’s Boise River gravel augmentation and our Angler Access project at the new Diane Moore Nature Center.

    OUR THANKS goes to the people who have already purchased Greenbacks to support our gravel augmentation effort on the Boise River. Funds left over from that project will be applied to the Owyhee River gravel augmentation.


    George Butts, Troy Pearse, Brian Martin, Robert Boatright, Fairlee Frey, Greg Mondin, Dennis Moore,

    Dennis Fomin, Gary Gettman, Larry Hill, Kathi Rothner, Scott Lenz, Kent Christensen, Tim Hall, Terry Burton,

    Klaus Kissman, Jack Truschel, Johnny Rogers, Robert Hurley, Brad Stewart, Ray Arguello, Michael Stahl,

    John Slovick, Jason Hansen, Tim Opp, Jim Kazakoff, Guy Beaudine, Ron Gambassi, James Murry, Joel Peterson, Ralph Stark, Joe Barberio, and Mike Schwiebert.

  • 27 Apr 2023 3:47 PM | Troy Pearse (Administrator)

    When river flows come up, side channels are a safe haven for trout to seek shelter from the heavy currents. Side channel protection is especially important for juvenile trout, including baby brown trout that recently emerged from their redds/nests and don’t swim very well yet.

    Here is a photo of the side channel where BVFF has been working to improve trout habitat. You can see the main river is raging but there are numerous soft areas in the side channel for trout, including the corner where we added some woody cover. The gravel BVFF added to the side channel this Spring is tucked out of the main current and is at a good depth and flow for rainbows to spawn. We will keep an eye on it and report spawning activity.

  • 25 Apr 2023 1:55 PM | Troy Pearse (Administrator)

    Our weather is finally heating up and there is still lots of snow in the mountains to melt and runoff. Keeping on track of water conditions can help you avoid showing up at the river only to find it is blown-out, unsafe and unfishable. BVFF’s Local Waters webpage has links to current flows and water temperatures for nearby rivers as well as reservoir and boat ramp conditions and is a good tool to help you plan your fishing trip.

    I also use the “” app on my Android phone to track river flows on my favorite rivers. I like that it includes both USGS stations and AHPS (Advanced Hydrologic Prediction Service) stations that give you insights into how the river is expected to rise or drop over the next week.

    Here is a look at the main screen of my river “favorites”. For some stations you will notice both a USGS and AHPS entry. Here is a look at both of those water flow graphs. You can see that the USGS graph goes back further in time, but the AHPS graph includes a forecast for the next week.  As you can see in the MF Boise forecast, flows are headed up! So be safe out there.

  • 07 Mar 2023 9:19 PM | Troy Pearse (Administrator)

    Boise Valley Fly Fishers has wrapped up their Brown Trout Redd mapping on the Lower Boise River and delivered updated waterproof maps to Boise Flood District 10 for use in their annual winter river maintenance. Now that the redd map is complete we plan to refloat the river yearly to identify which sites are active and communicate that to the Boise Flood District and Idaho Fish and Game. Last year the Boise Flood District reported that the redd mapping had enabled them to avoid all but one of the redd areas and the Flood District excavator driver, shown in Figure 1 holding the Redd Map along with new Assistant District Manager Mark Zirschky, told me that he has also been able to identify and avoid smaller redd areas that were not on the map. Well done and thank you to the Boise Flood District!

    BVFF is tracking 50 redd sites across 22 miles of the Boise River, from the Willow Lane boat ramp in Boise down to Star. This year we were able to add the South Chann el around Eagle Island, which had fewer redd sites than the North Channel, but some of the sites had quite large gravel deposits and many brown trout redds. Figure 2 shows the area of the Boise River that we are tracking, and you can see how many more redd sites are in the North Channel vs the South Channel. There are many factors that could be responsible, but one reason is the North Channel has more “sinuosity” (a measure of the number of curves in a river channel) resulting in more areas where smaller gravels settle out that trout can use to spawn.

    This year spawning redds were observed as early as the first week of November and as late as the 2nd week of December. Spawning locations were consistent between 2021 and 2022 but this year we counted fewer total numbers of redds. This is partially due to being more conservative in our counting and not including some areas that IDF&G fish biologist Tim D’Amico thought could be caused by scour from higher velocity flows, but even then the overall redd numbers appear to be down. On a positive note, the number of redds in our BVFF Side Channel increased this year because of gravel shifting into prime locations and having a little more water flowing into the channel. Idaho Fish and Game is very interested in tracking the redd locations from year to year and we will continue to report our findings to them.

    This year we piloted a process of noting the location of downed trees as we floated the river, to help the Boise flood district plan their winter maintenance work, which has opened the door for more discussions with the Flood District and Idaho Fish and Game on identifying trees that would be good to try and retain for trout fry protection. A great continuation of our partnership on the Boise River.

    Last year we floated in November and missed some of the brown trout redds because browns were not done spawning so this year we waited until December to make sure that brown trout spawning activity was complete. Next year we will switch to checking known redd-zones for activity which should allow us some weekend outings in November. Thanks to our volunteers (George Chen, Klaus Kissman, George Butts, Johnny Rogers, and Troy Pearse) who braved cold days on the river to count redds.

  • 06 Mar 2023 11:12 PM | Troy Pearse (Administrator)

    In February, Boise Valley Fly Fishers added 15 cubic yards of gravel to a side channel on the Lower Boise River located by the New Dry Creek diversion below Glenwood Bridge. Thanks to our awesome volunteers (Ray Arguello, Tim Opp, Dwane May, Guy Beaudine, Jose' DeSousa, Mike Stahl, Klaus Kissman, George Butts , Scott Lenz , Russ Dodd, Johnny Rogers, Jeff Jones, Troy Pearse and Dennis Fomin) who stuck with the project thru several delays and complications.

    Two years ago we added 15 cubic yards of gravel but spread it out in 3 locations on the side channel. That worked well as a way to seed the channel with spawning gravel and since then we have seen a significant increase in trout spawning. The gravel has slowly been working its way down the side channel and Mother Nature has been sorting and depositing it in productive locations for trout to use. This time we decided to add all of the gravel at the top both to refresh the gravel in a location that rainbows like to spawn and to give Mother Nature more building materials to move downstream.

    In addition to adding spawning gravel we also worked with fish habitat restoration experts at BioAnalysts and Idaho Fish and Game to improve the woody cover on the side channel to give trout fry refuge after they hatch. Idaho Fish and Game tells us that having this woody cover is the key to helping trout fry survive into adulthood.

    One issue we have had during the low water fall and winter is keeping good flows coming into the side channel because the public throws rocks and logs across the top in order to cross, which reduces inflows.Brown Trout

    need sufficient flows to spawn in Fall and their nests/redds need those flows continued through the winter to oxygenate the eggs. This year the Boise Flood District placed some large boulders near the top of the side channel that can be used as steps to cross--let’s hope the public uses them.

    A BIG Thank You to our project partners: To Sunroc for donating the gravel again and to Boise Flood District 10 for their assistance moving it into the side channel.

    A special thanks to those people who bought Greenbacks to support our gravel augmentation projects (Robert Boatright, Dennis Moore, Larry Hill, Scott Lentz, Kent Christensen, Tim Hall, Terry Burton, Klaus Kissman, Jack Trushel, Johnny Rogers, Bob Hurley, Brad Stewart, Ray Arguello, Mike Stahl, John Slovick, Jason Hansen, Tim Opp, Guy Beaudine, Jim Kazakoff, George Butts, Brian Martin, Troy Pearse, Ron Gambassi, James Murry, Joel Peterson, Ralph Stark, and Joe Barberio). We are still working to raise money for the Owyhee Gravel Augmentation. If you are interested in helping please consider buying a $25 Greenback at the BVFF Store.

    Newspaper Stories about the project can be found at:

    Idaho Press

    Capital Press

    Idaho Statesman (March 15)

    KTVB Channel 7 News

  • 18 Jan 2023 7:27 PM | Troy Pearse (Administrator)

    The Lower Boise River (Boise River) is a unique resource that makes the Treasure Valley a special place to live, play and visit. The trout population is better now than it ever has been thanks to the many organizations that are actively working to improve trout habitat on the Boise River, including Idaho Fish and Game (IDFG), Boise Valley Fly Fishers (BVFF), Trout Unlimited (TU), the Boise River Enhancement Network (BREN) and the Intermountain Bird Observatory (IBO). Together, these organizations are protecting the river and helping improve wild trout reproduction, resulting in better fishing for all of us.

    The river below Lucky Peak Dam is considered a Tailwater fishery because the outflows from Lucky Peak come from the bottom of the dam, which helps keep water cool during the summer. IDFG regularly stocks the main Boise river with rainbow trout and brown trout (trout stocked now are called “Triploids” and are sterile). IDFG historical stocking records show that in the last three years significantly more rainbow trout have been stocked than brown trout, with most of the trout being stocked from Middleton up to Barber Park.

    In addition to stocked trout, the Boise River has a good population of wild reproducing rainbow and brown trout, as well as some remaining native redband trout. The river could have more wild trout if it had better trout spawning and rearing habitat. Here is a great video presentation by Idaho Fish and Game on the Fish of the Boise River that gives an overview of the history of the river, its trout population, and factors that are important to help improve the fishery.

    Spawning Size Gravels

    The primary limiting factor for wild trout spawning is availability of smaller gravels. This is because the higher spring flows every year since Lucky Peak was built in 1955 have washed most of the smaller sized gravel downstream and newer gravels from up-river are blocked from refreshing the river because of the series of dams above. One way to replace those lost gravels is through a gravel augmentation where spawning sized round gravels (1/2” to 2” in size) are added to the river to improve trout spawning habitat. Side channels are the best area to do gravel augmentations both because they are the preferred location for trout to spawn and gravel is less likely to wash away because the side channels have less water velocity. The Ted Trueblood chapter of Trout Unlimited has done gravel augmentations up in the Park Center reach of the river in the side channels at Warm Springs (in 2005) and Heron Creek (in 2009), and since then the IDFG shoreline fry surveys have found that the best population of “baby” trout fry are in those areas, which is strong feedback that their gravel augmentations are working.

    BVFF was inspired by TU’s success and wanted to do additional gravel augmentations on the Boise River to continue to improve trout spawning habitat. BVFF consulted with IDFG and fish habitat restoration experts at BioAnalysts to identify a suitable side channel on the Boise River in Garden City. Prior to the gravel augmentation this section of the river was considered to have a low density of trout fry, compared to the upstream areas where TU did their gravel augmentations. In 2019 BVFF obtained the needed stream alteration permits and added 12 cubic yards of gravel to three areas in the “BVFF Side Channel” that runs around New Dry Creek Diversion on the south side of the river, between Glenwood Bridge and the head of Eagle Island. Since then, we have seen a significant increase in both rainbow and brown trout spawning. Rainbow trout spawn in the Spring and they preferred to make their redds in the upper section of the side channel, while brown trout spawn in the Fall and have liked the slower water in the middle and lower sections of the side channel.

    Last Fall (Nov 2022) we were able to accompany IDFG on one of their Shoreline Fry Surveys that included the BVFF Side Channel. We sampled 6 sites on the main Boise River from Willow Lane down to the BVFF Side Channel and 3 sites in the BVFF Side Channel. We netted approximately 20 trout fry at the 6 sites on the Main Boise river and 84 trout fry in the BVFF Side Channel—good evidence that the gravel augmentation is helping improve the number of trout fry. It is exciting to see this “Field of Dreams” scenario playing out, and we anticipate we will see improvements in the adult trout population over the coming years. 

    The gravel we added in 2019 is slowly shifting downstream in the BVFF Side Channel and Mother Nature is putting it into locations that are suitable for trout to spawn. We have applied for another stream alteration permit and plan to refresh gravel in the side channel this winter so the rainbow trout have fresh gravel for spawning and Mother Nature has more building materials to work with during the next spring runoff. The gravel refresh is estimated to cost around $1,200. We are raising money to fund the gravel refresh by selling “Greenbacks for Redds”. If you are interested in helping fund the donation, please buy a Greenback at the BVFF Online Store.

    Woody Cover

    Another issue that limits the wild trout population is the lack of good woody debris that helps protect young trout fry from predators as well as provide shade and habitat for aquatic insects. And although Gravel Augmentations are much “sexier”, improving woody cover is just as important to helping those fry survive their first year. But because the Boise River flows through an urban area, much of the natural downed trees are removed to reduce flood risks and improve public safety for recreational floating. This results in less cover for young trout and a lower rate of survival. IDFG would like to see more woody debris in the Boise River and in 2016 they did a project at Barber Park to improve aquatic habitat by adding engineered logjams and boulders. These logjams and boulders created sheltered areas for fish to rest, hide from predators and feed on bugs.

    As a part of BVFF’s Gravel Augmentation project in 2019 we worked with Boise Flood District 10 to retain downed trees in the side channel that would have normally been removed. This woody cover gave trout fry a place to hide after hatching out of the nests/redds resulting in a higher survival rate. The value of this woody cover was evident last Fall when IDFG did their Shoreline Fry Survey as the majority of the juvenile trout found in the BVFF Side Channel were tucked underneath the woody cover. Here is a short video segment of the IDFG Shoreline Fry Survey in the BVFF Side Channel—note how the trout fry were hiding in the downed tree along the bank. FrySurveyVideo.mp4

    In recent years the Boise Flood District has been working to improve their management of tree hazards along the Boise River Corridor to keep trees that are leaning over the river and providing shade. BVFF has continued partnering with Boise Flood District 10 and IDFG to look for opportunities to improve woody debris in the river where it is safe to do so. Side channels are one of the best places to do this because downed trees there are not a danger to floaters and are less likely to come loose and float away. Downed trees in side channels also provide high value cover for trout fry that hatched from trout redds in the side channel. Bank stabilization and plantings by BREN, TU, the City of Boise, and others are also helping improving woody cover on the Boise River.

    Side Channel Habitat

    Side channels are the preferred spawning location for trout because of reduced velocities and a naturally higher amount of spawning sized gravels that are pulled from the banks. Side channels are considered the best rearing locations because they offer protection for young trout from higher velocity flows and have a higher amount of natural woody cover. Side channels that flow during both the summer and the winter are especially important, however one systemic issue with rivers below dams is the loss of side channel habit. Essentially over time the river fills in its side channels and becomes one large “channelized ditch”. This occurs because the high water flows (such as from Snowmageddon) move large cobble into the mouths of side channels but river flows on years after that are artificially restricted by Lucky Peak which keeps the river from reestablishing flows into those side channels.

    Two side channels of the Lower Boise River that were lost from the 2017 Snowmageddon high runoff flows are behind the Les Bois racetrack. These two side channels represent a mile of premium year-round trout spawning and rearing habitat but now do not flow during the fall and winter seasons. BVFF is working with IDFG on a plan to “un-plug” the entry to these two Les Bois side channels so they will again flow in fall and winter, which will open them back up for brown trout spawning and over-winter protection for young rainbow and brown trout. Stay tuned for more information as this project progresses over the next few years.

    One side channel that has been reopened recently is at the new Diane Moore Nature Center. The project, lead by the Intermountain Bird Observatory, worked through the permitting to restore a historic side channel and rebuilt it, including adding spawning size gravel for trout and copious amounts of woody cover for trout fry protection. BVFF partnered with the Intermountain Bird Observatory on trout habitat signs that have been installed along the restored side channel, as well as building a new angler access at the site. BVFF is very excited to be working up at the Diane Moore Nature Center and we plan to stay involved helping protect and improve trout habitat there. One of the Trout Habitat signs we installed and a photo taken at the side channel this summer are shown below. It is rewarding to see the small fish hiding in the woody cover—just like the Trout Habitat sign depicts!

    Trout Redd Protection

    Rainbow trout spawn in the higher flows of spring and brown trout spawn in the lower flows of fall. Because of the lower flows the brown trout redds (nests) are more vulnerable to being trampled by unknowing anglers or equipment in the river doing irrigation or flood control work. BVFF has partnered with IDFG and Boise Flood District 10 to map the location of Brown Trout Redds so the flood district can avoid them during their annual winter maintenance activities. Mapping Brown Trout redds has been a great opportunity learn about trout spawning habitat while improving the Brown Trout reproductive potential in the Boise River. Angler education is also important, and many fishermen do not know what a trout redd looks like. BVFF has been working on angler “Redducation” so they can recognize and avoid redds in the Boise River while out fishing.  BVFF has made Redducation the focus at their Fly Fishing Expo booth the last two years and are planning to attend the Boise Sportsman Show in March to increase the impact of this message.  Here is a short Redducational video we did on the Boise River.

    Minimum Winter Flows

    Winter water flows are important to a healthy trout population, especially trout fry going into their first winter. Before the mid 1980s the Boise River would often drop to 50cfs to 100cfs during the winter, which was very hard on the overwinter survival of trout and whitefish. Over time IDFG has worked to improve the winter flows on the Boise River, and typical winter flows today are 240cfs which has dramatically improved the health of the river and the trout population. Lucky Peak is unique in that IDFG has a storage water right for streamflow maintenance. Currently IDFG does not fully use all their water right and they are investigating raising winter flows to 300cfs or even 350cfs, which would increase the number of side channels that have water in the winter and give trout access to more spawning and rearing habitat.

    The split of water on the Boise River between the north and south channels around Eagle Island varies year to year, and although the main Boise River had more water the Fall of 2022 than it did in 2021, the flows in the north channel were down by 25% due to changes at the head of Eagle Island made for irrigation. In our fall 2022 Brown Trout Redd Survey we noticed fewer redds in the north channel than the year before. Our observation was that some of the spawning areas did not have sufficient water depth for brown trout to make their redds due to the lower water levels. IDFG is very interested in tracking brown trout redd trends and we will continue to share our yearly brown trout redd location information with them to help show the need for higher winter flows on the Boise River.

    A Winning Recipe

    When you put together spawning gravel and woody cover in a side channel that flows year-round, you have a winning recipe for improving the trout population. The spawning gravel gives you more “trout seeds” and the woody cover increases the yield of the “trout crop” that is available at the end of the year. And having an overwinter side channel helps that crop of young trout make it through their first winter and into adulthood. The BVFF Side Channel has all three of these winning ingredients, and we will be continuing to look for other side channels in the Boise River where we can apply the same approach.

    References For More Information

    - IDFG Boise River Aquatic Habitat Project

    - BREN Boise River Plan 


    - Boise River Winter Flows

  • 17 Jan 2023 11:54 AM | Troy Pearse (Administrator)


    In January of 2021, Boise Valley Fly Fishers added 12 Cubic Yards of gravel to a side channel of the Lower Boise River, on the south side around New Dry Creek Diversion. Based on Idaho Fish and Game’s (IDFG) recommendations we used a combination of 3/4” round rock, which ranged in size from ½” to 1” in size and 2” round drain rock, which ranged in size from 1.5” to 2”. The year before adding the gravel we observed very little spawning in the side channel, but the 2 years after adding the gravel we have seen a significant increase in brown and rainbow trout spawning and last fall, IDFG found a large number of trout fry in their shoreline fry survey. We are excited and encouraged by this success. We have observed the gravel is shifting downstream from high spring flows and we want to refresh it to help continue the spawning success. One question that both Idaho Fish and Game and the Army Corps of Engineers asked us about the gravel refresh was “Where did the gravel go that we put in last time”? A fair question that needed an answer.

    We had taken measurements of gravel at the augmentation locations, and I was intimately familiar with the thousand foot side channel, having walked it with my dogs hundreds of times over the years. So, when the Boise River flows dropped to their lower winter levels I went on a gravel hunt, and here is what I found.

    Figure-1 shows the locations where we placed gravel in the side channel. We made 3 rectangular beds, each approximately 8 feet wide x 20 feet long x 6” deep (shown as rectangles 1, 2 and 3 in Figure 1). One bed was near the top of the side channel, a second in the middle, and a third in the lower section of the side channel. We also ended up with some secondary gravel zones below where the piles of gravel were staged (shown as circles A, B & C).

    I walked the side channel from the top to the bottom, looking for smaller gravels and changes in the side channel. Inspecting the top locations (1 & A) I found no smaller gravels left from the augmentation. I think this is because these areas are in the direct path of incoming flows and higher spring flows moved the gravel downstream. But, although the gravels weren’t in their original location, I observed that some of it had shifted downstream and settled on the inside bend directly below, which I observed rainbows using to spawn the previous spring.

    Walking down to the middle location (2) I could see that gravel was also gone—moved by higher flows. But I didn’t have to go far to find it as Mother Nature carried it about 100 feet downstream and created a new little riffle area that brown trout used to spawn last Fall. Well done, Mother Nature!

    Continuing my inspection down the side channel I found another new riffle about 50 feet below the secondary “Zone B”, and a pile of smaller gravels that had accumulated on the next inside bend. This gravel accumulation is out of the water now but it will be underwater come spring and looks to be in a prime location for Rainbow Trout spawning. Similarly, I found that all the gravel that we had painstakingly wheelbarrowed into “Zone C” was gone and deposited onto an existing cobble bar below. We will have to watch these two new gravel accumulations this spring to see if rainbow trout use them to spawn.

    Just below this little cobble bar is the third augmentation zone. I had to be careful here because it has quite a few brown trout redds, but from what I could see all of the gravel in this zone appears to still be in place with possibly some minor shifting. This location is protected from higher flows by the cobble bar above and is a lower gradient area that brown trout have used to spawn the last two years.

    In summary, the gravels BVFF placed in the side channel are all still in the side channel, but spring flows are slowly working them downstream. The river is good at transporting and sorting gravel, depending on gravel size and river velocity, and the locations that the river chooses are ultimately the best spots for trout spawning. We are working to refresh the gravel at the top of the side channel, which will add gravel in the zone where rainbow trout like to spawn as well as give the river more building materials to continue to shape the side channel below. We are raising money for this gravel augmentation. It takes about $25 worth of gravel to make one trout redd, and each trout redd will support 2,000 or more eggs. The more redds we get in the river, the more wild-trout we will have! If you are interested in helping us, please donate by purchasing a “Greenback” from the BVFF Store.

    On a related side-note, while doing our brown trout redd mapping this fall we started at Heron Park in Garden City to take a look at the area where Trout Unlimited did a gravel augmentation in 2019. The gravels added along the left bank of the main Boise River have since been carried away by high spring flows and we did not see any brown trout redds until about a half a mile below. This reinforces the value of adding gravel into side channels where the reduced velocities help retain them longer than in the main river.

  • 08 Jan 2023 10:37 AM | Troy Pearse (Administrator)

    BVFF's gravel augmentation two years ago on the Boise River has been a HUGE SUCESS! We have seen a dramatic increase in trout spawning in our side channel and this Fall IDFG's Fry Survey found a large number of trout fry there!

    Mother nature has been taking the gravel we added to the side channel and repositioning it into new gravel deposits that trout have been using to spawn.  We want to refresh the gravel at the top of the side channel before spring so that Rainbow trout have gravel where they like to spawn, and Mother Nature has more "building materials" to work with during Spring runoff.

    We have submitted for a permit to add 15 cubic yards of gravel to the head of the side channel and Boise Flood District 10 has volunteered again to help us move the gravel into the side channel. We expect the permit to be issued in January and we will coordinate with the Flood District to do the gravel refresh later this winter.

    To help fund the gravel augmentation we have started the Greenbacks For Redds program.  I estimate it takes about $25 worth of gravel for a trout to make one redd on the Boise river. If you want to help sponsor a redd, buy a Greenback at our BVFF Online Store.

    The Owyhee Gravel Augmentation has been delayed due to long permitting times. If all goes well it will happen in the Spring, but it could have to wait until Fall if we don't get our permits in time.  We have received grants from FFI and ODFW to help pay for the Owyhee gravel augmentation, but we have had some unexpected expenses that are raising the cost.  If you want to help sponsor a redd on the Boise River, you can buy Greenbacks at our BVFF Online Store.

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