Lake Ouescapis is a freshwater body of the Broadback River watershed in the Municipality of Eeyou Istchee Baie-James (municipality), in the Administrative Region of Nord-du-Québec, in Quebec, in Canada.

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

Surrounding areas near the lake include mountain peaks, the highest on the east side reaching 358 metres (1,175 ft) and another at 358 metres (1,175 ft) on the west side of the lake.

The mouth of lake Ouescapis is located at: The Lake Ouescapis flows on the northeast side by a discharge flowing over 10.6 kilometres (6.6 mi) the South-East by forming small serpentines to the north shore of Lake Poncheville (length: 37.1 kilometres (23.1 mi); altitude: 269 metres (883 ft)).

From there, the current crosses on 46.7 kilometres (29.0 mi) up to the Broadback River, according to following segments: The toponym lake Ouescapis was formalized on December 5, 1968 at the Commission de toponymie du Québec, at the creation of this commission.