The Gouin Reservoir is a man-made lake, fully within the boundaries of the City of La Tuque, Quebec, Canada. It is not one contiguous body of water, but the collective name for a series of connected lakes separated by innumerable bays, peninsulas, and islands with highly irregular shapes. It has therefore a relative long shoreline of over 5,600 km (3,500 mi) compared to its surface area of 1,570 km2 (610 sq mi). It is the source of the Saint-Maurice River.

La Tuque is a city located in north-central Quebec, Canada, on the Saint-Maurice River, between Trois-Rivières and Chambord. The population was 11,129 at the 2021 Canadian census, most of which live within the urban area. At over 28,000 km2 (11,000 sq mi), it is the largest city in Canada by area.