West Fork Deadwood Creek Floodplain Reconnection Project TA

The West Fork Deadwood Creek Floodplain Reconnection Technical Assistance project investigated baseline site conditions and bridge replacement options for a narrow-span bridge that crosses West Fork Deadwood Creek within the floodplain reconnection project area. The replacement off the current bridge spanning West Fork Deadwood Creek at the road-stream crossing with a longer spanning bridge will allow for full restoration site development at the floodplain reconnection project site and not be impinged upon by the current infrastructure which constricts the stream into a single channel that is highly disconnected from its adjacent floodplain. The longer spanning bridge will open up the potential for increased flow path diversity, increased habitat complexity and promote natural habitat forming processes that are beneficial to rearing coho salmon as well as a suite of other native aquatic organisms. The work supported by this grant advanced the site analysis and subsequent bridge design, and with match funding from the USFS, a Final Design for the bridge replacement was achieved during this effort. Specific tasks accomplished include 1) topographic site survey 2) hydrologic and hydraulic analysis (performed by USFS using match funding sources) 3) geotechnical analysis 4) Alternatives Analysis and Advancement to Final Design. The advancement of the designs was a collaboration between the SWC, USFS, Lane County Public Works and a hired private Consultant (Cole Smith Engineering).

The purpose of this project is to restore habitat complexity that will contribute to support of historic levels of salmonid productivity in West Fork Deadwood Creek. Current conditions include a lack of habitat complexity (side channels, alcoves, floodplain connectivity, etc.), lack of floodplain interaction, and reduced channel complexity. By re-grading the floodplain, aggrading the existing channel and placing large wood, hydrologic connectivity across the valley floor floodplain will be restored and channel complexity improved. Invasive species will be removed/controlled, and the project area will be replanted with a diverse mixture of native species in a manner that mimics the natural succession of species observed in similar native ecosystems. Many of these plant species are already present in the area, and are representative of the plant communities found nearby. Diverse native vegetation can shade streams, filter excess nutrients, provide future large wood recruitment, and supply food for macroinvertebrates. This improves habitat, water quality, and nutritional supplies for salmon and steelhead.