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News release

June 6, 2023


Stephen Mikkelson, 218-316-3887,

MPCA releases assessment of Thomson Reservoir project in St. Louis River Area of Concern

Person fishes from rocky shore of Thompson Reservoir

Project proposes remediation of 220,000 cubic yards of contaminated sediment using activated carbon

The Minnesota Pollution Control Agency (MPCA) today released its environmental assessment worksheet (EAW) for the proposed Thomson Reservoir sediment remediation project. This is the last of eight projects for the MPCA’s remediation team and U.S. Environmental Protection Agency (EPA) in the St. Louis River Area of Concern (AOC).

The Thomson Reservoir site is located just upstream of the Thomson Hydroelectric Station on the St. Louis River in Carlton, Minn. The sediment is contaminated with dioxins/furans from industrial discharges in the reservoir prior to modern environmental regulations. The project will use a pelletized powdered activated-carbon amendment in about 69 acres of the 330-acre reservoir to remediate the contamination. This effort will reduce the availability of contaminants in riverbed sediments for macroinvertebrates that live there, which in turn reduces levels of dioxins/furans up the food chain.

The project also includes an expansion of the Kayak Center parking lot for recreational paddlers, which will keep the reservoir accessible to outdoor enthusiasts during construction.

The estimated project cost is $40 million. It will be funded thought a Great Lakes Legacy Act partnership with the MPCA, the EPA, and a voluntary private party.

The agency is requesting public comments on the worksheet, which describes the project’s potential effects on the environment, including its impact on nearby land uses, geography, habitat, and historic sites. The EAW also details air and vehicle emissions, dust, traffic, noise, and odors that the project might produce and describes the potential for temporary indirect impacts to sensitive ecological areas from noise and construction equipment.
The public can review the draft EAW and submit public comments by visiting or by mail by July 6, to:

Minnesota Pollution Control Agency
c/o Pam Foster
525 S. Lake Avenue, Ste. 400A
Duluth, MN 55802

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