The Lake Brochu is a vast expanse of freshwater in the south-eastern part of the Gouin Reservoir, in the territory of the town of La Tuque, in the administrative region of Mauricie, in the province of Quebec, in Canada.

The route 400, connecting the Gouin Dam to the village of Parent, Quebec, serves the southern portion of Brochu Lake, as well as the river valleys Jean-Pierre and Leblanc; this road also serves the Peninsula which stretches north in the Gouin Reservoir on 30.1 kilometres (18.7 mi).

Some secondary forest roads are in use nearby for forestry and recreational tourism activities.

Aliéniste, Brochu acts at the beginning of the twentieth century as general director of the asylum of Beauport, establishment named afterwards "Hospital Saint-Michel-Archangel", then designated "Hospital Center Robert-Giffard" (French: Centre hospitalier Robert-Giffard) which is named today Institut universitaire en santé mentale de Québec (French).

[2] The toponym "Lac Brochu" was formalized on December 18, 1986, by the Commission de toponymie du Québec.