GREAT LAKES MUD
  • Home
  • Pollution
    • Dioxins
    • Heavy Metals
    • NAPL
    • Oil and Grease
    • PAHs
    • PCBs
    • TBT
    • TPH
  • Partnership
    • Great Lakes Legacy Act
    • Cost-Sharing
  • Cleanup Process
    • Project Stages
    • Dredging
    • Dry Excavation
    • Caps and Covers
    • Habitat Restoration
  • Community Revitalization
    • Ashtabula
    • Buffalo
    • Duluth
    • Muskegon
    • Sheboygan
  • Waterbody
    • Indiana >
      • East Branch - Grand Calumet River AOC
      • East Branch Phase II - Grand Calumet River AOC
      • East Chicago Waterways - Grand Calumet River AOC
      • Indiana Harbor Canal TSCA - Grand Calumet River AOC
      • Lake George Canal Middle & East - Grand Calumet River AOC
      • Roxana Marsh - Grand Calumet River AOC
      • Stateline - Grand Calumet River AOC
      • West Branch - Grand Calumet River AOC
    • Michigan >
      • Black Lagoon - Detroit River AOC
      • Centennial Park - Detroit River AOC
      • Division Street Outfall - Muskegon Lake AOC
      • Former MGP Site - St. Marys River AOC
      • Lower Rouge River Old Channel - Rouge River AOC
      • River Raisin - River Raisin AOC
      • Riverwalk - Detroit River AOC
      • Ruddiman Creek - Muskegon Lake AOC
      • Ryerson Creek Outfall - Muskegon Lake AOC
      • Tannery Bay - St. Marys River AOC
      • Torch Lake - Torch Lake AOC
      • Upper Trenton Channel - Detroit River AOC
      • Zephyr Site - Muskegon Lake AOC
    • Minnesota >
      • Azcon/DSPA Slip - St. Louis River AOC
      • Minnesota Slip - St. Louis River AOC
      • Munger Landing - St. Louis River AOC
      • Scanlon Reservoir - St. Louis River AOC
      • Slip 3 and Slip C - St. Louis River AOC
      • SLR Interlake/Duluth Tar - St. Louis River AOC
      • Spirit Lake Site - St. Louis River AOC
      • Thomson Reservoir - St. Louis River AOC
    • New York >
      • Buffalo River - Buffalo River AOC
    • Ohio >
      • Ashtabula River - Ashtabula River AOC
      • Cuyahoga River Old Channel - Cuyahoga River AOC
      • Gorge Dam - Cuyahoga River AOC
      • Jack's Marine North Slip - Ashtabula River AOC
      • Ottawa River - Maumee AOC
      • Otter Creek - Maumee AOC
    • Wisconsin >
      • Greater Milwaukee Estuary - Milwaukee Estuary AOC
      • Hog Island Inlet - St. Louis River AOC
      • Howards Bay - St. Louis River AOC
      • Kinnickinnic River - Milwaukee Estuary AOC
      • Lincoln Park - Milwaukee Estuary AOC
      • Sheboygan River - Sheboygan River AOC
      • Tyco - Menominee River AOC
    • More coming soon...
  • Education
    • Grade School Curriculum
    • High School Curriculum
    • More Resources >
      • Indiana
      • Michigan
      • Minnesota
      • Ohio
      • Wisconsin
  • Contact

 Thomson Reservoir

St. Louis River Area of Concern

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

The Thomson Reservoir project site is located in Carlton County north of Thomson, MN. It is within the St. Louis River Area of Concern.


Picture
Picture

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


Picture
The 69.5-acre Thomson Reservoir remedial footprint.
Picture
The remediation method for Thomson Reservoir.

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.
Picture

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



IISG and GLR logos
Picture
Picture
Picture

Contact Us

Great Lakes Mud c/o Illinois-Indiana Sea Grant
Purdue University
195 Marsteller Street
West Lafayette, IN 47907-2033

​Email: [email protected]
© 2025 Illinois-Indiana Sea Grant, All Rights Reserved.
Illinois-Indiana Sea Grant strives to ensure equal access and an
​inclusive environment.
  • Home
  • Pollution
    • Dioxins
    • Heavy Metals
    • NAPL
    • Oil and Grease
    • PAHs
    • PCBs
    • TBT
    • TPH
  • Partnership
    • Great Lakes Legacy Act
    • Cost-Sharing
  • Cleanup Process
    • Project Stages
    • Dredging
    • Dry Excavation
    • Caps and Covers
    • Habitat Restoration
  • Community Revitalization
    • Ashtabula
    • Buffalo
    • Duluth
    • Muskegon
    • Sheboygan
  • Waterbody
    • Indiana >
      • East Branch - Grand Calumet River AOC
      • East Branch Phase II - Grand Calumet River AOC
      • East Chicago Waterways - Grand Calumet River AOC
      • Indiana Harbor Canal TSCA - Grand Calumet River AOC
      • Lake George Canal Middle & East - Grand Calumet River AOC
      • Roxana Marsh - Grand Calumet River AOC
      • Stateline - Grand Calumet River AOC
      • West Branch - Grand Calumet River AOC
    • Michigan >
      • Black Lagoon - Detroit River AOC
      • Centennial Park - Detroit River AOC
      • Division Street Outfall - Muskegon Lake AOC
      • Former MGP Site - St. Marys River AOC
      • Lower Rouge River Old Channel - Rouge River AOC
      • River Raisin - River Raisin AOC
      • Riverwalk - Detroit River AOC
      • Ruddiman Creek - Muskegon Lake AOC
      • Ryerson Creek Outfall - Muskegon Lake AOC
      • Tannery Bay - St. Marys River AOC
      • Torch Lake - Torch Lake AOC
      • Upper Trenton Channel - Detroit River AOC
      • Zephyr Site - Muskegon Lake AOC
    • Minnesota >
      • Azcon/DSPA Slip - St. Louis River AOC
      • Minnesota Slip - St. Louis River AOC
      • Munger Landing - St. Louis River AOC
      • Scanlon Reservoir - St. Louis River AOC
      • Slip 3 and Slip C - St. Louis River AOC
      • SLR Interlake/Duluth Tar - St. Louis River AOC
      • Spirit Lake Site - St. Louis River AOC
      • Thomson Reservoir - St. Louis River AOC
    • New York >
      • Buffalo River - Buffalo River AOC
    • Ohio >
      • Ashtabula River - Ashtabula River AOC
      • Cuyahoga River Old Channel - Cuyahoga River AOC
      • Gorge Dam - Cuyahoga River AOC
      • Jack's Marine North Slip - Ashtabula River AOC
      • Ottawa River - Maumee AOC
      • Otter Creek - Maumee AOC
    • Wisconsin >
      • Greater Milwaukee Estuary - Milwaukee Estuary AOC
      • Hog Island Inlet - St. Louis River AOC
      • Howards Bay - St. Louis River AOC
      • Kinnickinnic River - Milwaukee Estuary AOC
      • Lincoln Park - Milwaukee Estuary AOC
      • Sheboygan River - Sheboygan River AOC
      • Tyco - Menominee River AOC
    • More coming soon...
  • Education
    • Grade School Curriculum
    • High School Curriculum
    • More Resources >
      • Indiana
      • Michigan
      • Minnesota
      • Ohio
      • Wisconsin
  • Contact