Lake Manicouagan as seen from earth orbit. Image courtesy NASA.

Manicouagan Reservoir (also Lake Manicouagan) is a annular lake in northern Quebec, Canada, the remnant of an impact crater made approximately 212 million years ago, towards the end of the Triassic period. Recent research has shown that the impact melt within the crater has an age of 214±1 Ma. As this is 12±2 Ma before the end of the Triassic, it implies that it was not the cause of the major extinction event which marks the Triassic-Jurassic boundary.

The crater was created by the impact of a 5 km diameter asteroid which excavated a crater originally about 100 km wide although sediments and erosion have since reduced its diameter to about 72 km.

The lake was created by flooding from the massive Manicouagan or Manic (Manic 1, Manic 2...) series of hydroelectric projects undertaken by Hydro-Quebec, the provincial electrical utility, during the 1960s. The complex of dams is also called the Manic-Outardes project because the rivers involved are the Manicouagan and the Outardes.

The Manicouagan lake acts as a giant hydraulic battery for Hydro-Quebec. In the peak period of the winter colds the lake surface is usually lower since the turbines are run all the time at peak load, to meet the massive electrical heating needs of the province. The surface of the lake also knows record low levels in the extreme periods of heat in New England during the summer, since in that period Hydro-Quebec sells electrical energy to the joint New England grid and individual utilities in the United States.