Saint Louis River Area of Concern - Sediment Assessment

The Minnesota Pollution Control Agency (MPCA) is currently working with the United States Environmental Protection Agency and private consultants as part of the Great Lakes Area of Concern (AOC) program to identify and remediate bed sediments contaminated with polychlorinated dibenzo-p-dioxins/dibenzofurans (dioxins) in reservoirs in the St. Louis River watershed of the Lake Superior Basin. Two reservoirs in the St. Louis River watershed where dioxins in bed sediments are a concern are Thomson and Scanlon Reservoirs near Cloquet, Minnesota. A history of industrial-waste-water discharges associated mainly with the municipal discharges, building materials manufacturing, and paper manufacturing has resulted in the accumulation of dioxins in the reservoir bed sediments. Knowledge of the bed-sediment characteristics, such as its composition and thicknesses, is needed to develop an effective remediation plan for the reservoir bed sediments. To address this issue, the U. S. Geological Survey (USGS) and MPCA are undertaking a cooperative project to characterize the bed-sediment lithology, in particular sediment compositions and thicknesses, in Thomson and Scanlon Reservoir. Results from the project will be used by MPCA to design an effective remediation plan for the in-situ treatment of the dioxin-bearing sediments in the reservoirs.