Caupichigau Lake is a freshwater body of the southern part of Eeyou Istchee James Bay (municipality), in the administrative region of Nord-du-Québec, in the province of Quebec, in Canada.

The hydrographic slope of Lake Caupichigau is accessible through the road 113 which link Lebel-sur-Quevillon to Chibougamau.

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

The mouth of Lake Caupichigau is located at the bottom of a bay on the north-west side, at: The main hydrographic slopes near Lake Caupichigau are: The main hydrographic slopes near Lake Caupichigau are: This hydronym is indicated on the sheet of the topographic series Mistassini, in 1945.

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