Lake Opataca is a body of water in the Broadback River watershed in the Eeyou Istchee James Bay (municipality) area in the Nord-du-Québec, in the province of Quebec, in Canada.

The surface of Opataca Lake is usually frozen from early November to mid-May, however, safe ice circulation is generally mid-November to mid-April.

Lake Opataca is surrounded by mountains with dozens of peaks exceeding 400 metres (1,300 ft).

Presumably of Cree origin, this toponym could mean "it is a pass, a narrow passage, on the water, between two elevations of ground".

[2] The toponym "Lake Opataca" was formalized on December 5, 1968, by the Commission de toponymie du Québec, when it was created.