News and information on BVFF conservation projects
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
- IDFG 2019 SW Region FISHERIES MANAGEMENT ANNUAL REPORT
- Boise River Winter Flows
GRAVEL MIGRATION OBSERVATIONS ON THE BOISE RIVER
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.
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.
Boise Flood District 10 has begun their annual winter maintenance in the Boise River to remove debris that could be a flood risk come higher spring runoff flows. This year the Flood District will again be using a map of Brown Trout redds to avoid inadvertently driving through them. Last year the Flood District reported that with the help of the BVFF Redd Map they were able to successfully avoid the Brown Trout Redds--and the machinery drivers even identified some redds that BVFF missed!
This Fall, BVFF members floated the river from Veterans Park to Star, marking redds and updating the Redd Map for the Flood District. There were noticeably fewer Brown Trout redd counts this year, especially on the North Channel around Eagle Island, which was where the most brown trout redds were last year. We think there were fewer redds because although flows on the main Boise River were slightly higher than last year, the flows on the North Channel were 25% lower. BVFF is partnering with Idaho Fish And Game to track the Brown Trout Redds over time to get a better idea of how they change year to year.
For more information on this program, see the Idaho Press Article
BVFF Members Klaus Kissman and Troy Pearse counting redds in the North Channel of the Boise River.
The Lower Boise River runs from Lucky Peak dam to the Snake River and the upper section (from the Dam down to Star) has a good population of naturally reproducing rainbow and brown trout. Lucky Peak is a tailwater dam, which helps keep the waters cool in the summer, but three common issues below a dam in an urban area that can limit wild trout reproduction are: 1) Lack of spawning size gravels; 2) Loss of side channels; and 3) Lack of Large Woody Debris.
GRAVEL AUGMENTATION
The Boise River has lost much of its spawning size gravels which limits where wild brown and rainbow trout can spawn. Two winters ago, Boise Valley Fly Fishers (BVFF) worked with Idaho Fish and Game (IDFG) and Boise River Flood Control District #10 (FCD 10) Boise Flood to improve trout spawning and rearing habitat on a side channel of the Lower Boise River in Garden City. We worked with IDFG to identify areas that had suitable depth and flow for rainbow and brown trout spawning and added a total of 12 cubic yards of gravel to three areas in the side channel. We timed adding the gravel when BFlood10 was in the area doing their annual winter stream maintenance work and they donated time and machinery to move the gravel into the side channel where our volunteers raked it into place. For more details on the gravel augmentation, see these articles by the Idaho Statesman and BREN.
LARGE WOODY DEBRIS
Woody debris provides refuge for trout fry and is critical to the survival of young trout. However, flood control practices in urban areas like Boise remove fallen trees to reduce flood risk. We have been fortunate to be able to work with FCD 10 and they agreed to reposition and retain some fallen trees in this side channel as an experiment to improve trout habitat. We appreciate FCD 10’s extra efforts to improve woody debris when possible.
SIDE CHANNELS
Side channels are the best place for trout spawning and rearing. They have reduced flows that are conducive to trout spawning and tend to have the right depth and structure for trout to make their redds. Side channels with year-round flow are the most valuable because they provide opportunities for Brown Trout to spawn in November and they give young trout fry shelter to survive their first winter. BVFF’s side channel has flow year-round, although the entry sometimes gets clogged with rocks and logs placed there by the public to cross, which reduces inflows and blocks fish passage. Please help us keep side channels flowing and do not block them off.
SPAWNING
Because of the extended drought, the BVFF side channel has had lower than average flows, but we have seen rainbow trout redds in the spring and brown trout redds in the fall in the areas where we added gravel. A recent review of the gravel we placed in the stream two winters ago shows that the gravel at the head of the channel is making its way down the side channel from higher flows during spring runoff and mother nature is using it to make a new spawning area, which brown trout used this fall to spawn. The gravel at the top of the side channel is getting thin and we are working on refreshing it this winter or next winter.
FRY SURVEY
This Fall we were able to accompany IDFG on their annual Lower Boise River trout fry survey and see firsthand how the habitat improvements were working.
I am very pleased to report that we found dozens and dozens of brown and rainbow trout fry in the side channel!
Most of the trout fry were located in the large woody debris, which underscores the importance of woody debris. IDFG Fish Biologist Tim D'Amico, who led the fry survey, was very impressed with the number of trout fry in our side channel and commented that it was one of the most productive spots they had sampled that year.
RECIPE FOR SUCCESS
A side channel that flows year-round, plus spawning size gravel and woody debris is winning trout habitat combination to improve the trout population. BVFF has adopted this side channel and we plan to continue to work on habitat improvements as well as do regular river cleanups in the area. We are talking with IDFG about the potential to restore year-round flow to other side channels that have become dry over the winter—something that would continue to improve the wild trout populations in the Lower Boise River.
Another critical factor for success is the partnerships between BVFF, IDFG and FCD 10, working together to improve and protect trout habitat on the Lower Boise River. And we couldn’t do it without the support of our members and volunteers.
We are raising money to do additional gravel augmentations. Please buy a "Greenback" from the BVFF store to help support our efforts to increase trout spawning in the Boise River.
HABITAT SIGNS
BVFF added a trout habitat sign to the side channel to help educate people about the importance of side channels and the lifecycle of brown and rainbow trout. Since then we have added similar trout habitat signs at the Diane Moore Nature center as well as the first anti-litter sign on the Lower Boise River!
THANKS
Our thanks to all of our project partners and volunteers that made this project happen.
I just got back from swinging a fly for steelhead on the Clearwater river. In my 30 years of fishing for steelhead, the last few years have been the toughest I have experienced. Since retiring from HP I have been able to log way more hours chasing steelhead but have only caught a small number of fish compared to just 10 years ago when I fished a fraction of the hours.
I had beautiful Fall days on the Clearwater: The sun was bright and the Clearwater river was low and clear. But there were not many fish to be found, and everyone I talked with had the same experience. I expect the rain this week will pull some fish into the river and fishing will (hopefully) improve. I did manage to swing one up on a small pink Klamath Intruder--a 35" hen that was holding in some boulders at the base of a riffle. What a thrill to connect with something that WILD! (Sorry, no Fish Photo. I held her in the water for a brief moment to revive, thanked her, and sent her back on her way.)
Talking with Rick Williams yesterday, he had a similar experience swinging a fly on the Salmon River near Riggins. He reported that he had nary a bump or swirl...and that it felt like he was fishing an empty river.
While swinging I had plenty of time to think about the plight of the steelhead (and salmon). The speaker for BVFF's last club meeting was fisheries expert Dr. Rick Williams, who painted a grim picture of the future of anadromous fish in Idaho unless big changes occur soon to the river and management. The BIG take-away messages I got from his talk were:
BOTTOM LINE: If we want to save Salmon and Steelhead for future generations, then we must return the Lower Snake River to a free-flowing river and get Idaho smolts safely to the ocean. Time is not on our side in this issue. Please share this message and support Congressman Simpson's plan.
My thanks to Link Jackson for his "Grant Me Freedom" artwork.
In October 2022, volunteers from the Boise Valley Fly Fishers (BVFF) built an Angler Access to the Boise River at the Diane Moore Nature Center . The set of landscape timber steps replace a steep, erosive social-trail that had developed at the site and give anglers a safe way to access this section of the Lower Boise River.
The project design team was led by retired landscape designer Randy Lancaster along with Greg Kaltenecker from the Intermountain Bird Observatory, local water enthusiast Steve Steubner, and Klaus Kissman and Troy Pearse from BVFF. We had an awesome set of volunteers who worked hard for two days to get the landscape timber stairs built. You can't ask for better volunteers than these guys! My thanks to Klaus Kissman, Troy Pearse, Brian Martin, George Butts, Kent Christensen, Mike Stahl, Joe DeSousa, Tim Opp, Jack Truschel, Scott Lenz, Jay Pryor, and Tim DeMarco.
You can see some video of the project construction on our YouTube channel, and more photos were uploaded to our Facebook Group Page (note, you do not have to have a Facebook account to see these).
DAY1-PHOTOS
DAY2-PHOTOS
The project was a collaborative effort between BVFF and the Intermountain Bird Observatory, which has been championing development of the Diane Moore Nature center under the direction of Greg Kaltenecker who is the Diane and Winston Moore Family Endowed Director. Funding for the project was provided by a grant from the Idaho Fish and Wildlife Foundation and BVFF. BVFF is excited to be working at the Diane Moore Nature Center and is thrilled with their work to restore a historic side channel which adds important spawning habitat and rearing habitat for wild trout in the Boise River.
BVFF collaborated with the IBO and Idaho Fish and Game on trout habitat signs that were installed in August along the restored side channel. One of the habitat signs explains the trout's lifecycle and encourages catch and release fishing in this area which is primarily wild trout. We were lucky to get an awesome piece of artwork designed by local artist Link Jackson for the second sign which describes the importance of "woody debris" to the survival of young trout. BVFF is proud to have also helped design and install the first anti-litter signs on the Lower Boise river and we hope to see more of them at other access points.
Trout and wildlife need clean habitat. Please pack out all trash. Keep it Wild! #FillTheNet and #LeaveItBetter
Flows on the Owyhee have dropped for the year, and you can see the dramatic shift in water temperatures as they changed from running water through the power turbines to the bottom outlet works. Water temps were ranging from 50 - 55 degrees daily and have dropped down to 49 - 50 degrees. The reservoir is at critically low levels but thankfully we made it through the season without the power turbines pulling in warmer water from the "epilimnion" warmer surface layer.
BVFF has been working with ODFW, BofR and the Owyhee Irrigation District on a plan to switch outflows to the lower "outlet works" if needed. For more details about that, see our Conservation News Article
The cooler water temps will get the BWO hatches going, especially as we get cooler and cloudy weather. The cooler water will also trigger browns to start spawning, so if you go over to fish the Owyhee, please remember to avoid brown trout spawning areas. For more information on how to identify brown trout redds, see our Conservation News Article.
October is here, and it is one of my favorite months to fish. Hatches are picking up with Fall Caddis and Blue Winged Olives, and the trout have the feedbag on preparing for winter. But with October comes the brown trout spawning season. The exact timing of spawning depends on water and weather conditions but generally brown trout on the Owyhee start to spawn in October with activity peaking in November and tapering off into December. And on the Boise River in town, browns typically don’t start spawning until the first week of November.
Brown trout like to spawn in gravel that is ½” to 1.5” in diameter, in water that is 1’ to 3’ deep and has some mild current. The tail-out of a run is one of their favorite places, especially if it has gravel. Gravel tail-outs are also an easy place for anglers to cross the river, so it is important to keep your eye out for redds to avoid wading through them.
Redds can be identified by the gravel being rubbed clean as fish build their nest. Redds tend to be circular to oblong shaped and are about the size of a hula-hoop. If there is a large gravel deposit, then you will often find multiple redds built next to each other. Here is a photo of a group of redds at the end of a small side channel on the Boise River. Note the size of the gravel and how it has been rubbed clean. There is also a single redd built along the far bank.
Side channels and bank edges are another common area to find brown trout redds so look before you step into the river. Here are some photos of brown trout redds on the Boise River from last year, and a short REDD-U-Cational Video that shows some brown trout redds in a tail-out.
When you see brown trout working their redds, it is best to leave them to their task as we all want them to succeed and make more brown trout! That doesn’t mean you shouldn’t go fishing. It is perfectly ethical to fish other sections of the river where brown trout are not spawning. There are plenty of rainbow trout that are snacking on the stray egg patterns and fishing in the deeper run below can be quite good. Last year the a pink salmon colored “Eggstacy” fly was my top egg pattern on the Boise River. I was amazed at how well the eggstacy material worked. Tim Camtasia has a nice video on how to tie it.
So get out and enjoy some fall fishing, but remember to watch where you wade. Brown trout redds are vulnerable for several months while the eggs are incubating--in our area that is typically into the month of March. Over time it gets harder to identify the redds as they silt-in from river algae and deposits, so it is best to avoid walking through gravel areas during the winter, especially on the Owyhee where there is so little spawning habitat. In 2019 BVFF worked with ODFW to put signs at vulnerable spawning locations to alert anglers. Watch for those signs, and tredd carefully.
Between 2015 and 2020 there was a concerning drop in the brown trout population on the Owyhee River in Oregon, particularly in the lower reaches between the tunnel and the concrete bridge 10 miles downstream. Several years ago the Oregon Department of Fish and Wildlife (ODFW) started looking into the causes to try and protect this precious fishery. The leading suspects were 1) Anglers wading through brown trout spawning redds; 2) Predation of brown trout fry; and 3) Excessive warm water temperatures.
To help address the first issue, BVFF worked with ODFW in 2019 and installed Redd Protection Signs at major spawning sites. To help reduce the chance of brown trout eating their own fry, ODFW increased stocking of rainbow trout fry in the river, which is why there has been a sudden increase in the number of rainbow trout being caught.
ODFW’s first review of water temperatures showed that the river stayed plenty cool for trout during the summer, all the way down to Snively Springs. But further analysis of historical water temperatures at the Bureau of Reclamation stream gauge (about a mile below the dam) showed that during the extended drought years 2013 – 2015, Owyhee Reservoir levels dropped to the point that the power turbines started pulling in some warmer surface water which caused increased water temperatures to be released from the dam. We estimate that water temperatures released from the dam in August of 2014 and 2015 were 60 – 65 degrees compared to the normal summertime 50 degrees. This puts water temperatures in the lower reaches of the river into the upper 70s to low 80s, which is in the lethal temperature range for brown trout.
Over the last two years, BVFF and ODFW have been researching the water temperature issue. We found that the Federal Energy Regulatory Commission (FERC) license for power generation at the Owyhee Dam requires that outflows be managed to ensure water temperatures needed for trout in the river below. Using this information, ODFW has been able to successfully negotiate with the Owyhee irrigation district to change dam operations to pull from deeper in the reservoir when needed. Luckily with our super-wet spring the Owyhee reservoir levels were higher than anticipated so it has not been a problem this year, but we are very happy to have this agreement in place and are thankful to ODFW for their work to help alleviate another warm water event and protect the brown trout on the Owyhee River.
The brown trout population on the Owyhee river continues to recover, although the lower river is recovering slower than the upper river, partially because of having less spawning habitat. Our club’s gravel augmentation project this Fall will give brown trout new places to spawn and hopefully will increase the population of brown trout on the lower half of the river.
Special thanks go to Kirk Handley and Dave Banks at ODFW for their ongoing efforts on the Owyhee river. My personal thanks go to BVFF member Forrest Goodrum for his help digging through the FERC dam licensing documents and to Ryan Hedricks from the Bureau of Reclamation for his help understanding the Owyhee dam operation and being a liaison between the different groups.
