Geologic Evaluation of the Strawberry Creek Restoration Project

Elk grazing near Strawberry Creek in Redwood National Park
Elk grazing near Strawberry Creek in Redwood National Park
Summary: 

PWA evaluated existing geologic conditions and potential stream channel response to proposed channel realignment and restoration activities in middle Strawberry Creek.

Client: 
Pacific Coast Fish, Wildlife and Wetlands Restoration Association (PCFWWRA) and National Park Service
Location: 
Humboldt County, California
Project Lead (s): 
Tom Leroy

Strawberry Creek historically flowed from its upland watershed, across an active alluvial fan, and down through an expansive wetland system into the lower portions of Redwood Creek. Currently the system is significantly modified from its natural configuration in part because of a levee system constructed in the lower portions of Redwood Creek after the devastating 1964-1965 floods. The overall goals of this restoration project entail improving fish passage and coho rearing habitat in Strawberry Creek, while working within the constraints imposed by the land use objectives of Redwood National Park (RNP) and adjacent landowners. The restoration plan for lower Strawberry Creek was designed to occur in several phases. Phase 1 was implemented by Pacific Coast Fish, Wildlife and Wetlands Restoration Association (PCFWWRA) with funding from the U.S. Fish and Wildlife Service and consisted of invasive reed canary grass removal along a 3,270 ft reach of lower Strawberry Creek, followed by repeated aggressive planting of 5 acres of native riparian vegetation, and construction of 4,000 ft of livestock exclusion fencing.
Phase 2 of the restoration project will be conducted upstream of the phase 1 project, with funding provided by the California Department of Fish and Game, to develop final engineering plans and specifications for channel realignment and restoration. All proposed enhancement activities and design options are planned to be implemented entirely within the boundaries of RNP. Phase 2 project components include:
1)    Restoring approximately 3 acres of wetland;
2)    Conducting channel realignment and restoration to facilitate stable, self-sustaining geomorphic processes;
3)    Replacing stream crossing culverts to improve fish passage and conveyance of water, sediment, and debris;
4)    Removing invasive species and reestablishing riparian areas in the restored wetland and along the restored stream channels.

PWA’s role in this project involved evaluating existing geologic conditions and potential channel response to channel restoration activities associated with phase 2 of this project, which consisted of review and analysis of geologic site conditions, review of historic aerial photography, characterization of alluvial fan processes and channel stability, sampling and analysis of subsurface wetland stratigraphy, and identification of geologic constraints and potential mitigations to the proposed channel restoration project.

Services Rendered : 
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