Dolbeau-Mistassini is a town in northern Quebec, Canada, at the confluence of the Mistassibi River, Riviere aux Rats and the Mistassini River, on Lac Saint-Jean. Dolbeau-Mistassini is in the Maria-Chapdelaine Regional County Municipality and is the commercial hub of Lac-St-Jean with big stores and shopping centres.

Lac Saint-Jean is a large, relatively shallow lake in south-central Quebec, Canada, in the Laurentian Highlands. It is situated 206 km (128 mi) north of the Saint Lawrence River, into which it drains via the Saguenay River. It covers an area of 1,053 km2 (407 sq mi), and is 63.1 m (207 ft) at its deepest point. Its name in the Innu language is Piekuakamu.