Rock Creek Confluence Stream Restoration Design-Build, Clackamas River

RockCreekHENDERSON design-build professionals worked with Clackamas County’s Water Environment Services (WES) group in the assessment, permit preparation, design, and construction of improvements to approximately 1,600 feet of Rock Creek at its confluence with the Clackamas River. Preservation and enhancement of this site will provide a refuge for sensitive species as the watershed continues to develop with higher density urban and suburban land uses. Within the project reach, Rock Creek should have a complex instream morphology that provides a variety of instream habitat features like riffles, pools, side channels, and bars. Rock Creek should also have a low to moderate entrenchment, with high floodplain connectivity and moderate width to depth ratios. In addition, to preserve and enhance the functions of stream habitat, the project site should contain a variety of riparian and upland plant communities, composed of native species and free of invasive and noxious weeds. Measurable goals developed by HENDERSON  for the site’s restoration include increased amount of LWD; increased frequency, depth and quality of pools; improved stream resiliency to flood events; reduced landslides triggered by stormwater discharges; increased riparian habitat diversity and stream cover; decreased cover of non-native invasive plant species; and reduced erosion in the riparian zone.

HENDERSON prepared design for in-stream and riparian elements to enhance the habitat within the reach, including installation of large woody debris, increased stream habitat complexity for salmonid resting and rearing habitat, floodplain reconnection, and replacement of invasive vegetation with dense native shrub and canopy plantings. HENDERSON supported WES in the permitting of this project and constructed the final design.


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