Sumas River Sediment Load

Science Center Objects

The Issue: A large, clay-rich active landslide on the western flank of Sumas Mountain in Whatcom County, Washington, is a significant source of sediment to Swift Creek and the salmon-bearing Sumas River. The landslide contains naturally occurring serpentinite that weathers to chrysotile asbestos and elevated levels of metals. The asbestos load in water as well as deposits along the banks and flood plain of Swift Creek and the Sumas River present human health concerns.

How the USGS will help: The USGS will evaluate sediment load, downstream transport, and spatial extent of sediment being deposited along Swift Creek and the Sumas River. The USGS will characterize input of sediment into the Sumas River from Swift Creek, monitor and quantify the sediment flux down the Sumas River, evaluate the potential for distribution of asbestos, and analyze the geomorphology and hydrology of the Sumas River watershed to assess concentration and transport potential of asbestos downstream to the Canadian border.

Assessment of Transport and Deposition of Asbestos-Rich Sediment along Swift Creek and the Sumas River, Whatcom County, Washington

Sumas River Sediment Load

Sumas River Sediment Load

(Public domain.)

Problem - A large (0.55 km2) active landslide on the western flank of Sumas Mountain in Whatcom County, Washington, is a significant source of sediment to Swift Creek and the salmon-bearing Sumas River. The clay-rich landslide contains naturally occurring asbestos and elevated levels of metals. The asbestos load in water as well as deposits along the banks and floodplain of Swift Creek and the Sumas River present significant human health concerns. Engineering controls and/or remediation are being considered to address the problem. In the past, Swift Creek was regularly dredged to minimize overbank flooding, but high costs and health concerns associated with handling the asbestos-laden dredge spoils have curtailed such work, resulting in a channel network with diminished flood-carrying capacity, high potential for overbank flooding of hazardous water and sediment, and possible impacts to the salmon-bearing aquatic ecosystem.

Objectives - The objectives of this study are to evaluate sediment load, downstream transport, and spatial extent of sediment deposition along Swift Creek and the Sumas River. The USGS will characterize input of sediment into Swift Creek, deploy sediment-monitoring instrumentation to quantify the current state of fluvial sediment flux, evaluate distribution potential of asbestos load, and analyze the geomorphology and hydrology of the Sumas River watershed to assess concentration and distribution of asbestos downstream to the Canadian border.

Swift Creek at Oat Cole Road in Whatcom County, WA

Swift Creek at Oat Cole Road in Whatcom County, WA

(Public domain.)

Relevance and Benefits - The study will monitor transport of potentially hazardous asbestos-rich sediment within the Sumas River system. The study is consistent with the USGS strategic science direction "A National hazards, risk, and resilience assessment program" ,"Climate variability and change", and "Understanding Ecosystems and Predicting Ecosystem Change: Ensuring the Nation's Economic and Environmental Future".

Approach - Analysis of the geomorphology of the Swift Creek/Sumas River system will rely on published literature, existing published and unpublished data, newly collected data, communication and coordination with professional colleagues, and the application of geomorphic principles of the downstream movement of sediment pulses in river networks.