Excessive sedimentation in Swift Creek is caused by a large, complex landslide on Sumas Mountain. Approximately 150,000 cubic yards of material move into the creek annually. The sediment contains elevated levels of naturally occuring asbestos, nickel, manganese,cobalt, chromium and magnesium. These chemicals are present in amounts toxic enough to prevent fish from living in Swift Creek and plants from growing in the slide and sediment material.
To prevent flooding, Swift Creek has been dredged annually. The dredged material was placed on the banks of Swift Creek by Whatcom county. The dredge material has been removed by local residents and businesses for use as landscaping and fill material.
In 2005, USEPA became aware of the potential asbestos contamination in the dredge material and prevented any more dredge material from being moved from the site. In early 2006, Whatcom County asked USEPA for help in determining possible solutions to the accumulation of dredge material along Swift Creek between Oat Coles Road and Goodwin Road, south of South Pass Road.
In May 2006, On-Scene-Coordinator Kathy Parker and START contractors sampled the dredge material. The results of the sampling confirmed the presence of elevated levels of metals and chrysotile asbestos content greater than 1%.
In August 2006, USEPA performed activity-based sampling at the site to determine if asbestos fibers were likely to get into the breathing zone for people handling the dredge material without personal protection. The results indicate that significant amounts of fibers of the harmful size, shape and type do enter the breathing zone of adults.
There currently is no firm plan for managing the site. During the fall of 2006, heavy rain events deposited large quantities of sediment in the creek bed bringing the level of the creek above the level of the surrounding land. The dredge material currently forms a berm that holds the creek in the bed. Further deposit of sediment may result in the creek leaving the current creek bed in an unpredictable location.
