Upper Abernethy Tributary Restoration - Implementation

This project is within the upper Abernethy creek basin along an unnamed tributary flowing into reach 3 of the main channel. An Upper Abernethy Creek Rapid Bio-assessment conducted in 2019 and the 2021 Strategic Restoration Action Plan for Native Fish in the Abernethy Creek Watershed identify the need to improve habitat complexity, reduce fine sediments, improve pool habitat, reduce stream temperature and provide future supplies of large wood. The Upper Abernethy Tributary Restoration project will improve instream and riparian conditions through placement of multiple log jams with key pieces, secondary logs, and slash. This will improve structure within the stream channel, trapping sediment and providing habitat complexity. Invasive blackberry will also be removed in the riparian area, followed by riparian planting. Project partners include NOAA Fisheries through an Infrastructure and Investment Jobs Act grant provided to Johnson Creek Watershed Council, the Clackamas Partnership, and the private landowner.

The design and installation of large wood structures will provide an immediate benefit to salmonid populations, while existing riparian trees mature to the size necessary to function as “key” large wood pieces. Placement of large wood pieces will increase complex cover in pool areas, help retain gravels for spawning, and increase the presence of complex habitat features that provide variability in velocity, cover, and depth and drive geomorphic channel processes. These functions are anticipated to increase critical rearing, holding, and spawning habitat for salmon, steelhead and Pacific lamprey. Construction of habitat function and structural elements will also promote bank stabilization and reduce sedimentation rates, resulting in improved spawning habitat quality. Through the replanting of native species and the removal of invasive plants, the future large wood cycle will be restored. As these species mature, they will provide stream shade, resulting in improved water quality. They will also provide immediate and future habitat for native wildlife and small interstitial spaces for juvenile salmonids when floodplains are inundated.