Swift Creek Sediment Management Action Plan Implementation

Swift Creek drains a 2.7 square mile watershed located in northern Whatcom County, Washington. Swift Creek flows from steep headwater terrain on Sumas Mountain across an alluvial fan, down through agricultural areas and ultimately discharges to the Sumas River. A large (68 million cubic yard), active landslide dominates the upper watershed. The complex landslide represents an abnormally large sediment supply: in recent years an average of 30,000 cubic yards of bedload per year has deposited in the lower creek channel. In addition to landslide related- risks, outbreak floods, and sediment management concerns, environmental and human health issues arise from the mineralogy of the Swift Creek landslide. Landslide sediments contain natural chrysotile asbestos. Whatcom County and the Whatcom County Flood Control Zone District have been preparing to address chronic problems in Swift Creek for years. With funding now allocated, and more funding expected, Whatcom County is implementing projects that can solve these problems. The next step is to advance repository development and design of instream priority actions identified in the Swift Creek Sediment Management Plan (SCSMAP).

Herrera is leading a team of regional experts, including several who have been involved in Swift Creek for years. Herrera’s experience with all aspects of science, planning, engineering, and permitting associated with stream restoration and managing contaminated soil and sediment, combined with experience in reclaiming mine sites throughout the northwestern United States allows us to fully understand the issues in Swift Creek. Initial work has included developing a prioritization protocol for implementing sediment management and reclamation projects, as well as planning level cost estimates. Based on available funding, property availability, proof of concept and feasibility, and costbenefit analysis results, the Herrera Team will refine and develop the SCSMAP projects. Additionally, Herrera will support the Supplemental Environmental Impact Statement (SEIS) and develop preliminary design analysis for the proposed actions which will likely include repository site(s) located on the Swift Creek alluvial fan east of Goodwin Road.