The project site is located at lower Johnson Creek, a small tributary to Carpenter Creek south of Mount Vernon. The project was identified as a way to improve habitat quantity and quality for native salmonids and trout while simultaneously reducing risk of flooding for neighboring properties. The project focused on restoring natural processes of alluvial fan migration to the site, and is intended to improve drainage, reduce flood risk, improve sediment transport, and restore coho salmon and steelhead habitat at the alluvial fan that has been created where sediments have been deposited at a transition from a relatively high gradient, narrow drainage to low-gradient, unconfined floodplain.
Lower Johnson Creek was confined by berms that pinned the creek into a fixed location along the toe of the hill slope. The berms forced reoccurring sediment deposition within low gradient sections of Johnson Creek and downstream in sections of Carpenter Creek, which is also confined by berms. Over the years in this configuration, the Johnson Creek stream channel had become perched at a higher elevation than the surrounding landscape, thereby increasing the risk of channel avulsion into the neighboring fields, home, and infrastructure. Feasibility work identified low lying topography in the project area that could accommodate a restored stream channel with capacity for peak flows and sediment transport processes.
The project was implemented in Summer 2010. Work entailed excavating a new stream channel through the lower elevation floodplain, elevating the private roadway at the end of East Johnson Road, installing a new bridge at the road crossing, rerouting Johnson Creek into the restored stream channel, and filling a portion of the perched abandoned channel. After the project was implemented, the site was enrolled into a Conservation Reserve Enhancement Program (CREP) and planted with native vegetation.
This project was constructed in 2010. Site monitoring and stewardship is ongoing.
Primary Project Contact
Eric Mickelson –Restoration Ecologist