The Pipmuacan Reservoir, known in French as Réservoir Pipmuacan, is an artificial lake situated on the border between the Saguenay–Lac-Saint-Jean and Côte-Nord regions of Quebec, Canada, approximately 130 kilometers north of Chicoutimi. This reservoir is crucial in regulating water flow for downstream hydroelectric stations on the Betsiamites River and, through Lake Pamouscachiou, the Shipshaw River. It spans a total surface area of 978 square kilometers, with 802 square kilometers being pure water.
Geographically, the reservoir is irregular, featuring numerous deep bays and a western section dotted with islands. A significant, rounded peninsula marks its center. Its primary tributaries include the Betsiamites, Sylvestre, Hirondelles, and Pipmuacan Rivers. The name “Pipmuacan” originates from the former Lake Pipmuacan, submerged during the reservoir’s creation. The name is derived from the Innu language, potentially meaning “arrow,” and commemorates a historical conflict between the Innu and Iroquois.
The Pipmuacan Reservoir supports a variety of sport fish, including northern pike, lake trout, brook trout, and lake whitefish. Local outfitters offer fishing excursions and lodging options for visitors.
The history of Pipmuacan Reservoir dates back to October 1953, when Hydro-Québec initiated construction on the Bersimis-1 dam and power plant. This involved building two main dams: one 674 meters long and 74 meters high between two mountains around Lake Cassé and another 315 meters long to control water release into the Desroches River. The construction was completed by 1956, with a spillway cut through a mountain between the two dams to manage water overflow.
In 2002, Hydro-Québec diverted part of the Portneuf River northwards into the Pipmuacan Reservoir to enhance the capacity of the Bersimis power stations. Further optimization efforts, such as the partial diversion of the Sault aux Cochons River, are currently being studied.