The St. Louis River, the largest U.S. tributary to Lake Superior, drains 3,634 square miles, entering the southwestern corner of the
lake between Duluth, MN and Superior, WI. The river flows 179 miles through three distinct areas; coarse soils, glacial
till and outwash deposits at its headwaters; a deep narrow gorge at Jay Cooke State Park; and red clay deposits at its
lower reaches. As the river approaches Duluth and Superior it takes on the characteristics of a 12,000 acre (4856 hectare)
freshwater estuary. While the upper part of the estuary has some wilderness-like qualities, the lower portion is decidedly urban.
The lower St. Louis River is one of 42 Areas of Concern (AOC) in the Lake Superior basin. An AOC is a site that has serious environmental pollution
problems that require remedial action and the development of a Remedial Action Plan (RAP) to outline ways to restore
the area. See EPA GLNPO for more information on the Great Lakes AOCs. The
Minnesota Pollution Control Agency has a web page that discusses contaminated sediments within the
St Louis River. St. Louis Estuary restoration efforts are updated here.
A large publicly owned wastewater treatment plant (Western Lake Superior Sanitary District, WLSSD) discharges into the river,
and the river carries a heavy load of suspended sediments from non-point sources. The river also has a number of sites known to contain contaminated sediments.
See our Reports page for more details.
The lower St Louis provides good fish habitat and is an excellent warm water fishery. However, the recent invasion of exotic fish (Eurasian
ruffe and round goby) may threaten native fish populations (see MN Sea Grant exotic species ).
Beginning in 2011, a major project began entitled "Implementation Framework for Delisting the St. Louis River AOC. Funded by EPA's Great Lakes Restoration Initiative, the MPCA, MnDNR, and WiDNR are leading an effort to develop Beneficial Use Imapirment (BUI) Blueprints for cleaning up the SLR AOC. These Blueprints will complement a flurry of current GLRI-funded remediation activities to guide the complete restoration of degraded portions of the system.