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

The route 400 connects the Gouin Dam to the village of Parent, Quebec, also serves 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).

A strait of 4.5 kilometres (2.8 mi) passing west of this island joins Marmette Bay South.

The water level of Chapman Lake is dependent on the Gouin Dam established in 1948.

The toponym "lac Chapman" was formalized on December 18, 1986, by the Commission de toponymie du Québec.