About the St. Louis River
The St. Louis River, with a watershed of 3,963 square miles, is the largest U.S. tributary to Lake Superior. Its headwaters is Seven Beavers Lake near Hoyt Lakes, Minnesota from which the river flows southwesterly for 179 miles before taking on the characteristics of a 12,000-acre freshwater estuary near Lake Superior. Below Jay Cooke State Park, the river turns to the northeast, and flows between Duluth, Minnesota, and Superior Wisconsin. The SLRA focuses primarily on the lower 39 miles of the St. Louis River, below Cloquet, Minnesota.
The St. Louis River was designated as an Area of Concern (AOC) (view map)-one of 43 on the Great Lakes- because of pollution problems remaining from past industrial practices. Unlike many other AOCs on the Great Lakes, the St. Louis River also has a lot of high quality habitat for plants and animals.
The St. Louis River AOC includes the Nemadji River, which has a watershed of 433 square miles. It begins near Moose Lake, Minnesota, and flows northeast to Superior, Wisconsin, where it enters Superior Bay one-half mile from the Superior entry to Lake Superior. About one-third of the Nemadji River watershed consists of red clay. Often this suspended clay created a visible plume of cloudy, red water extending out into Lake Superior.