California-Department-of-Fish-and-Wildli

French Creek Instream and Off Channel Habitat Enhancement Design Project –

Phase II

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The project’s overarching objective is to restore stream habitat essential to salmonid production. Specifically, the goals are aimed to improve instream and floodplain habitat both in the immediate short term and in the long term for Coho Salmon in French Creek, a highly productive spawning and rearing tributary of the Scott River. Furthermore, the project aims to create both over summering and overwintering habitat for Coho Salmon by increasing the frequency of inundation of the extensive anabranching channels in the adjacent floodplain to provide access to off-channel/side-channel habitats.

The short-term objective of the project is to increase and improve the quality and quantity of pool habitats within the project reach, with the long-term objective to move this reach from its current Stage 3-4 semi-stable degraded status towards Stage 6-8 with improved ecological services, outlined in Cluer, B., & Thorne, C. 2014, A Stream Evolution Model Integrating Habitat and Ecosystem Benefits paper. This will effectively increase stream complexity, floodplain activation, simultaneously improving pool frequency and depth.

Conceptual stream evolution model illustrating pathways of degradation and recovery of streams (Cluer and Thorne, 2014).

Large wood serves as a food resource for microbes, fungi, and macroinvertebrates, and contributes to habitat formation, aquatic food webs, and biogeochemical processes. Wood also contributes to the natural spatial and temporal dynamics of channel processes and is essential to sustain healthy streams. Furthermore, large wood that is within the active stream channel provides velocity refuges for fish during peak winter flows, decreases average water velocities, and sorts critical spawning gravel.

Final deliverables are to produce 100% site design that incorporates the goals and objectives of this project by creating instream structures, off channel features, and other habitat improvements in order to provide overwintering and summer rearing Coho Salmon habitat, improve floodplain connectivity, aggrade incised sections of the stream channel, and reduce pressure on eroding stream banks. In doing so, the project seeks to increase stream length, habitat complexity, and improve all riparian vegetation function and vitality.

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