Illabot Creek Alluvial Fan Restoration – Phase 2

The goal of this project was to restore natural processes and improve habitat conditions on the alluvial fan of Illabot Creek by addressing impacts from the dikes and roadway. The first phase of the project was completed in 2013 with SRF Board funds (project #11-1542), and included removing approximately 1,150 linear feet of dike, installing log jams, and constructing pilot channels downstream of the Rockport-Cascade Road. The funding request described here is for the second phase of the project which included completing final designs, constructing two new 100-foot span bridges on Rockport-Cascade Road, removing an additional 850 linear feet of dike, installing log jams, and actively reconnecting Illabot Creek with historic channels on the floodplain and alluvial fan. Rock weirs and log flood fences were installed to control grade and maintain flows into the new channels.

The existing bridge was left in place. Following project completion any one of the three bridges are able convey all or a portion of the flow from Illabot Creek. Flow through the constructed pilot channels and the two new bridges initially occurred during the large rainfall event in fall 2018, and the channels have been consistently engaged during all but the warmest/dryest days of the year. Natural processes of erosion, deposition, and channel development have already begun to occur within the channels. These processes are expected increasing spawning and rearing habitat for Chinook salmon, steelhead trout, and other species.

To reconnect Illabot Creek to two historic alluvial fan channels, thus increasing the overall habitat length and acreage available to juvenile and adult Chinook and steelhead.