- Altitude: 366 m above sea level
- Surface Area: 1,950 sq km
- Mean Depth: 85 m
- Maximum Depth: 350 m
- Volume: 142 cu. km
- Shoreline Length: 1322 km
- Drainage Basin: 29, 241 sq km
The Manicouagan Reservoir is located north of the St. Lawrence River in Quebec. The reservoir was created by damming the arched Manicouagan and Mouchalagan Lakes with their associated rivers. The circular shape of the reservoir and the surrounding landscape's characteristics are a consequence of a meteoritic impact. A large island, ile Rene-Levasseur, fills the middle of the reservoir. The Mouchalagane, Seignelay, and Themines rivers as well as the Petite Riviere Manicouagan and Hart Jaune River are the major inlets to this body of water. The Manicouagan River drains the reservoir. The water is oligotrophic, slightly acidic and very clear. This reservoir is monomictic and the thermocline develops during the summer at an average depth of 8 meters. Mercury has been detected in whitefish, the main commercial fish species from the lake. This, however, is normal for reservoirs located in this region. The enhanced siltation that occurred when the reservoir was first dammed in the late 1960's has settled and the water quality is generally considered to be pristine.
Manicouagan Reservoir is situated on the Precambrian rock of the Canadian Shield. Aquatic environments occupy the low areas between the numerous rocky hills and account for 20 to 50% of the region's surface area. Consequently, most of Hydro-Quebec's reservoirs are found in this region and the Manicouagan Reservoir is the most substantial water body of the Manicouagan hydroelectric complex. Boreal forest surrounds the reservoir and the main activities within the drainage basin are hunting of moose, caribou and lynx. Baie-Comeau is the closest city, located 217 km away on the north shore of the St. Lawrence River.