The Lac Henri-Mercier is a freshwater body whose discharge spills into the rivière Jacques-Cartier Nord-Ouest, in the unorganized territory of Lac-Jacques-Cartier, in the La Côte-de-Beaupré Regional County Municipality, in the administrative region of Capitale-Nationale, in province of Quebec, in Canada.

[1] Forestry is the main economic activity in the sector; recreational tourism, second.

The main watersheds near Lake Henri-Mercier are: Enclosed between the mountains, the Petit lac Jacques-Cartier has a length of 6.3 kilometres (3.9 mi), a width of 0.7 kilometres (0.43 mi) and an altitude of 662 metres (2,172 ft).

Located at the bottom of a small bay to the northeast, the mouth of this lake has a dam.

Subsequently, the toponym "lac Henri-Mercier" was formalized on December 5, 1968, by the Commission de toponymie du Québec.