The St. Louis River is a river in the U.S. states of Minnesota and Wisconsin that flows into Lake Superior. The largest U.S. river to flow into the lake, it is 179 miles (288 kilometers) in length and starts near Hoyt Lakes, Minnesota. The river's watershed is 3,634 square miles (9,410 km2) in area. Near the Twin Ports of Duluth, Minnesota and Superior, Wisconsin, the river becomes a freshwater estuary.
According to Warren Upham, he records the Ojibwe name of the river being Gichigami-ziibi (Great-lake River). He also records:
The river was probably so named by Pierre Gaultier de Varennes, sieur de La Vérendrye (1685–1749), who was a very active explorer, in the years 1731 and onward, of the vast country from Pigeon River and Rainy Lake to the Saskatchewan and Missouri Rivers, establishing trading posts and missions. The king of France in 1749, shortly before the death of La Vérendrye, conferred on him the cross of St. Louis as a recognition of the importance of his discoveries, and thence the name of the St. Louis River appears to have come. On Jean-Baptiste-Louis Franquelin's map (1688) and Philippe Buache's map (1754), it is called the Rivière du Fond du Lac, and the map by Gilles Robert de Vaugondy (1755) and Jonathan Carver's map (1778) are the earliest to give the present name.
In the mid 20th century, the St. Louis River became one of the most heavily polluted waterways in the state. Holling Clancy Holling, in his 1942 book Paddle to the Sea, illustrated the polluted state of the St. Louis River. By 1975, the river became an Environmental Protection Agency Area of Concern. The Western Lake Superior Sanitary District (WLSSD) was established in 1971 to address serious pollution problems in the lower St. Louis River Basin. WLSSD's regional wastewater treatment plant began operating in 1978. Within 2 years, fish populations rebounded and anglers began returning to the river. Through the 1980s and 1990s, additional cleanups took place, and the river is now significantly less polluted.
The river offers a wide variety of fishing opportunities including excellent Walleye, Northern Pike, Largemouth Bass, and Channel Catfish. Other species of rough fish can be caught here. Attempts to introduce Sturgeon into the river are currently taking place and if caught, are to be immediately returned. The River is also frequented by those travelling the Minnesota DNR St. Louis River Water Trail, which features campsites and excellent angling opportunities.