River in Québec, Canada, draining Lac St Jean, and flowing 765 km/475 mi southeast to the St Lawrence estuary at Tadoussac, 190 km/120 mi northeast of Québec. The upper reaches of the river thread through hilly country above Chicoutimi; hydroelectricity is generated along this stretch, providing power for numerous pulp and paper mills, and a huge aluminium smelting plant. From Ha Ha Bay, the waters widen and are navigable to large ships, but are confined by gaunt cliffs, often 500 m/1,640 ft high.
Hay, oats, and potatoes are grown in the area, crops which are well suited to the cool, short summers. Most farmers are also employed as lumberjacks, trappers, or guides; lumber mills are sited at Bolbeau, Kenogami, Jouquiere, Chicoutimi, and Port Alfred. At Arvida, the Aluminium Company of Canada (Alcan) has a large plant making use of locally-generated hydroelectricity to smelt imported ores. The finished product is transported by the St Lawrence–Great Lakes waterway to the rest of Canada. Arvida is now the largest centre for the manufacture of aluminium in North America. Roberval, on Lac St John, is a market and transportation centre, and salmon thrive in the shallow waters of the lake. Ha Ha Bay is a popular summer resort.
The Jesuit missionary, Father Dequen, was the first European to follow the Saguenay to Lake St John in 1647; Tadoussac, a French-Canadian village at its junction with the St Lawrence, has been the centre of the Jesuit and Franciscan missions since the 17th century.