Site History
Thomson Reservoir is located north of Thomson, MN on the St. Louis River in Carlton County. The 330-acre reservoir is a hydroelectric and water level control dam operated by Minnesota Power. Investigations have found elevated concentrations of dioxins and furans widely distributed throughout the reservoir sediments. The sediment remediation project will improve the aquatic environment by addressing 225,000 cubic yards of contaminated sediment across 69.5 acres.
Location
Schedule
The sediment remediation project is being conducted by the U.S. Environmental Protection Agency, the Minnesota Pollution Control Agency and PotlatchDeltic through a Great Lakes Legacy Act voluntary partnership. This project will use the modern technology of applying 1-2 inches of activated carbon pellets over contaminated sediment to improve the aquatic environment. The activated carbon rapidly binds to the contaminants in the sediment. Applying carbon prevents contaminants from accumulating in bottom dwelling organisms and moving up the food chain. It is anticipated for in-water construction work to begin Summer 2024.
Remediation Process
Sediment to be remediated: 69.5 acres (225,000 cubic yards)
Contaminants: Dioxins/Furans
Method: Enhanced Monitored Natural Recovery with Thin-Layer Amended Cover or Broadcast Amendment
When: 2024-2025
Partners: U. S. Environmental Protection Agency, Minnesota Pollution Control Agency, and PotlatchDeltic
Cost: ~$36 million
Contaminants: Dioxins/Furans
Method: Enhanced Monitored Natural Recovery with Thin-Layer Amended Cover or Broadcast Amendment
When: 2024-2025
Partners: U. S. Environmental Protection Agency, Minnesota Pollution Control Agency, and PotlatchDeltic
Cost: ~$36 million
Short-term Disruptions
Public water access will remain open. Parking may be limited. The public is reminded to observe posted signs and exercise caution around the work area including construction equipment in the water.
Community Involvement
An informational public meeting with question-and-answer session was held September 21, 2023 at the Fond du Lac Tribal & Community College. An information packet has also been distributed.
Contact U.S. EPA project manager, Meaghan Kern, or MPCA project manager, Steve Schoff, to ask questions about the project. |
More Information
Documents and Resources
Great Lakes Areas of Concern: Six Strategies to Support Community Revitalization (PDF, 8p, 987KB) 2024
Sheboygan’s Revitalization: The Sheboygan River Area of Concern (video, 4:24), 2022
Thomson Reservoir Remediation Method Poster (PDF, 1p, 1.4) September 2023
Thomson Reservoir Remedial Footprint Poster (PDF, 1p, 3.1MB) September 2023
Thomson Reservoir Sediment Project Fact Sheet (PDF, 2p, 5.0MB) September 2023
Environmental Assessment Worksheet (PDF, 13p, 433KB) August 2023
Decision Summary for Thomson Reservoir (PDF, 12p, 270KB) November 2020
Focused Feasibility Study for Thomson Reservoir (PDF, 1207p, 41.4MB) June 2020
Stakeholders
U. S. Environmental Protection Agency
Minnesota Pollution Control Agency
PotlatchDeltic
Minnesota Power
St. Louis River Alliance
Minnesota Department of Natural Resources
Fond du Lac Band of Lake Superior Chippewa
U.S. Army Corps of Engineers
University of Minnesota Recreational Sports Outdoor Program
Great Lakes Areas of Concern: Six Strategies to Support Community Revitalization (PDF, 8p, 987KB) 2024
Sheboygan’s Revitalization: The Sheboygan River Area of Concern (video, 4:24), 2022
Thomson Reservoir Remediation Method Poster (PDF, 1p, 1.4) September 2023
Thomson Reservoir Remedial Footprint Poster (PDF, 1p, 3.1MB) September 2023
Thomson Reservoir Sediment Project Fact Sheet (PDF, 2p, 5.0MB) September 2023
Environmental Assessment Worksheet (PDF, 13p, 433KB) August 2023
Decision Summary for Thomson Reservoir (PDF, 12p, 270KB) November 2020
Focused Feasibility Study for Thomson Reservoir (PDF, 1207p, 41.4MB) June 2020
Stakeholders
U. S. Environmental Protection Agency
Minnesota Pollution Control Agency
PotlatchDeltic
Minnesota Power
St. Louis River Alliance
Minnesota Department of Natural Resources
Fond du Lac Band of Lake Superior Chippewa
U.S. Army Corps of Engineers
University of Minnesota Recreational Sports Outdoor Program