The Swift Creek Asbestos site is located in Whatcom County, approximately 12 miles northeast of Bellingham, Washington. Extreme sedimentation with naturally occurring asbestos occurs in Swift Creek as a result of historic landslide activity in the upper watershed. The excessive deposition of sediment reduces the Swift Creek channel capacity, making the stream channel prone to flooding, and therefore requiring regular dredging to protect adjacent properties.
Historically, there have been many landslides in the Swift Creek drainage area to the east of the site. The excessive sediment in Swift Creek is caused by the large, complex landslide in the upper watershed of Sumas Mountain that reactivated in the 1940s. The reactivation of an ancient landslide occurred at least 73 years ago by erosion of ancient slide debris by Swift Creek. The land area affected by the landslide encompasses approximately 225 acres in the steep terrain of the upper watershed of Sumas Mountain, extending from an elevation of approximately 1,000 feet up to an elevation of approximately 2,200 feet above mean sea level. Sediment deposition occurs in the lower gradient region of the watershed.
The exposed slide material contains elevated levels of naturally occurring asbestos, nickel, manganese, cobalt, chromium, and magnesium. These substances are present in amounts toxic enough to prevent vegetation from growing on the slide material, and Swift Creek has no resident fish. The movement of sediment downstream in Swift Creek contributes to water quality problems in the Sumas River. The EPA Region 10 Site Assessment program became aware of the potential asbestos contamination in the dredged material in 2005. Together with the U.S. Army Corps of Engineers, who issues the dredging permit, EPA has expressed concern about this material being taken from the site by persons without personal protection and concerns about exposures to this material wherever it comes to be located if it is not covered, as has been done in the past.
Approximately 150,000 cubic yards of material move into the creek system annually. To prevent flooding, the Swift Creek channel has been maintained by annual dredging, initially by the Corps of Engineers, then for many years by the County. The dredged material was stockpiled on the banks of Swift Creek predominantly between Oat Coles and Goodwin Roads. In past years, stockpiled dredge material was removed from the banks of Swift Creek by the public, likely including local business and residents for a variety of uses. The practice of removing dredged material from the banks of Swift Creek for public uses was later disallowed by the Army Corps of Engineers (2004) due to human health concerns about naturally occurring asbestos in Swift Creek sediments. Additional dredge material was added to the stockpile in 2005 and now piles of this material remain along the banks of the creek. Without dredging the channel is becoming choked with sediment, and the stream channel will likely begin shifting to alternate paths, compounding the flooding hazards.
In early 2006, Whatcom County requested assistance from the EPA in determining the asbestos concentration in the dredged materials. In May 2006, EPA Region 10 performed an integrated assessment (IA) which included sample collection at locations along the approximately one-mile length of the dredged material piles. The average asbestos concentration for the composite dredged material samples collected during the IA was approximately 1.6%.