Overview
At the Deer Creek conservation site, adding large woody debris (LWD) in the stream and associated channels will increase the quality of fish habitat. The salmon life cycle requires gravel beds for spawning, as well as deep pools for juvenile salmon to use for resting. To help U.S. Forest Service personnel determine stream morphology changes following the addition of LWD, our team monitored the existing pool and riffle morphology of side channels of Deer Creek. After the project is implemented, we expect an increase in the wetted length of sides channel during normal spring stream flow.
Monitoring of LWD allows the restoration to be evaluated for its success in restoring stream morphology and salmon habitat. The 2016 Stream team monitored the floodplains along Deer Creek, with the goal of increasing the abundance of spawning nests of rainbow and cutthroat trout by 25% within the five year protocol. The addition of large woody debris into the established side channels and off-chutes of Deer Creek are designed to re-connect these channels to the entire adjacent floodplain, hopefully reactivating many ground water fed channels and standing pools found in our floodplain surveys.
Pool and Riffle Morphology Monitoring
Our team conducted morphological monitoring of side channels of Deer Creek using a modified version of the U.S. Forest Service Level II Stream Inventory Survey. Firstly, we determined whether a subsection of a particular would be categorized as a pool or as a riffle.
For each pool and riffle, we recorded length of subsection, maximum water depth, average width of wetted area, water temperature, and stream substrate composition (e.g. percent sand, gravel, cobble, boulder, or bedrock).
Large Woody Debris Monitoring
Our team also counted the number of LWD structures existing with each stream subsection. If LWD leaned over the channel but did not interact with the wetted channel or alter stream flow, it was not be tallied as LWD, rather recorded as potential LWD in the comments section. We tallied the number of pieces according to each of the three size classes: Small (diameter 12-24 inches and length > 25 feet), Medium (diameter 24-36 inches and length >50 feet), and Large (diameter > 36 inches and length >50 feet).