Sediment Assessment of Hotspot Areas in the Duluth/Superior Harbor

The St. Louis River and the Duluth/Superior Harbor consist of a variety of habitat types, ranging in character from relatively pristine streams and wetlands to an industrialized harbor containing two Superfund sites. Many current and former dischargers have contributed to the contamination of sediments within this Area of Concern (AOC). Currently, there are only a few permitted point source discharges to the waters of the AOC. These include (in Minnesota): the Western Lake Superior Sanitary District (WLSSD), which collects and treats both municipal and industrial wastes for the entire region of the AOC from Cloquet to Duluth. In Wisconsin, current major NPDES dischargers to the waters of the AOC include the Superior Municipal Wastewater Treatment Plant (WWTP), Murphy Oil-Superior Refinery, and Superior Fiber Products (whose wastewater is transported to WLSSD for treatment). The geological setting, anthropological history, and recent environmental knowledge about the AOC are documented in the Stage I Remedial Action Plan (RAP) document [Minnesota Pollution Control Agency (MPCA)/Wisconsin Department of Natural Resources (WDNR), 1992]. During the past five years, the MPCA and its collaborators have been actively involved in delineating the extent of sediment contamination in the St. Louis River AOC.
Date Issued
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United States Environmental Protection Agency (Washington, D.C.)
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United States Environmental Protection Agency
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Public Domain