Side channels, smaller spawning-size gravel and woody cover are all important for a healthy wild trout population. And while gravel augmentations may be “sexy”, unless there is safe refuge for the trout fry that hatch, then not many are going to make it to adulthood (something biologists call “recruitment”). 

WOOD

Idaho Fish and Game (IDF&G) has told me they think a lack of woody cover is something that is keeping the Boise River from reaching its full potential. BVFF has been working to improve woody cover by partnering with the Boise Flood District and looking for opportunities to keep some wood in the river for fish. This January they worked out the permitting logistics and retained/repurposed a tree instead of removing it. We are excited about the potential this type of change can make and appreciate all of the flood district's efforts to make it happen. See this BVFF conservation blog for more details.

This March, right before the flows came up, we were able to work with the flood district to retain a second tree that fell late in the season.  BVFF volunteers met with flood district manager Mark Zirschky to trim the tree back and secure it. Later this year the flood district will go through the additional permitting process to formally repurpose the tree and we will work with master arborist Zeke Willard and Idaho Tree Preservation Company to retain it.  If all goes well we might be able to identify another tree or two to add to that list this fall.

SIDE CHANNELS

This latest tree is in one of the side channels behind the old Les Bois racetrack at Expo Idaho where BVFF has been working with the flood district, IDF&G and the City of Boise to restore winter flows. The City of Boise is working with HDR on engineering for the Les Bois side channels and we are excited about the potential for these side channels to flow year-round again! It is a slow process but Dorene MacCoy, Boise Water Quality Coordinator, told me recently that it was still moving forward and they hope to review plans with stakeholders soon. For more information about this project, see this BVFF Conservation Blog article.

A couple of years ago, BVFF did a snorkel fry survey in the newly restored side channel at the Diane Moore Nature Center and we were amazed at how many trout fry we saw and estimated there were 2,500 in the 0.4 mile long side channel. Talking with IDF&G, they agreed it was an impressive number of fry and said that the excellent woody cover there was likely a major contributing factor.

In early March, BVFF volunteered at the Diane Moore Nature Center to secure some downed trees in the side channel to help prevent bank erosion and provide additional woody cover for trout.  It would be fun to do another snorkel fry survey this summer to see how the side channel is doing.  

GRAVEL

In 2019 and 2023 BVFF did gravel augmentations in a side channel of the Boise River (you can read more about that project here). High water has shifted that gravel down the side channel where trout have been using it for spawning. Unfortunately we didn't see any brown trout redds last fall, likey because of reduced inflows to the side channel, which is a good reminder that in addition to gravel you need to have adequate water depth and flows for trout to spawn.  BVFF's gravel augmentation on the Owyhee river is planned for this fall, after flows drop at the end of Irrigation Season. You can read more about that project here and here.

THANKS

BVFF is grateful to IDF&G, the Boise Flood District, Idaho Tree Preservation Company, the City of Boise and the Diane Moore Nature Center for their efforts to improve woody cover and restore side channels on the Boise River. We are lucky to have such great partnerships with these people and organizations. My thanks to them and to all of the volunteers who continue to help with these projects, including everyone who volunteers for our yearly Fly Fishing Expo which provides the funds we use for these projects.