Lac du Grand Couac is a Lake located in Lac-au-Brochet; La Haute-Côte-Nord, Quebec.

• Latitude: 49° 40' 34'' North   (decimal: 49.6761627)
• Longitude: 69° 42' 39'' West   (decimal: -69.7109508)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Lac-au-Brochet; La Haute-Côte-Nord
• Atlas of Canada Locator Map: Lac du Grand Couac
• GPS Coordinate Locator Map: Lac du Grand Couac Lat/Long