Holcomb Creek Large Wood Enhancement #1

The project location is on Holcomb Creek 0.2 miles upstream from its confluence with Abernethy Creek. Stream inventories conducted in 2017 and 2019 indicated a lack or large wood and associated complex habitat throughout the Abernethy Creek watershed, including Holcomb Creek. The low level of large wood in the system is the result of past timber practices that reduced the level of conifer trees in riparian areas as well as potential direct removal of wood from the system. Restoration activities for this project include placing large wood, invasive species removal, and native species planting. The project will also use logs to exclude cattle in place of fencing due to risk of fence damage from flowing waters. Project Partners include members of the Clackamas Partnership and the Clackamas Soil & Water Conservation District.

Lower Columbia River coho and winter steelhead are negatively impacted by loss of habitat, impaired water quality and lack of access to historic spawning areas. This project will restore habitat elements believed to be most limiting to salmon and steelhead as identified in local and regional assessments referenced above and below in this application.

The 2017 stream habitat inventory (Cascade Environmental Group) found there are relatively low quantities of instream large wood pieces, particularly large logs (key large wood pieces). Replacing large wood along Holcomb Creek will provide salmon and steelhead complex overhanging cover and recruit gravels for improved substrate complexity. Upland downed wood is also important for amphibians and other terrestrial species that require escape cover and areas for hibernation. Significantly increasing the density of large wood on the site would greatly enhance biological conditions for fish and wildlife.

Lack of riparian vegetation: Removal of invasive plants and reestablishment of native trees and shrubs will increase instream shading, replenish the large wood cycle, and reestablish more naturally moderated channel migration
rates. Each of these will benefit salmon and steelhead by improving the quality and future sustainability of available habitat.