Lac Rachelle-Castonguay is a Lake located in Lac-au-Brochet; La Haute-Côte-Nord, Quebec.

• Latitude: 49° 35' 49'' North   (decimal: 49.5969935)
• Longitude: 69° 42' 11'' West   (decimal: -69.7031672)
• 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 Rachelle-Castonguay
• GPS Coordinate Locator Map: Lac Rachelle-Castonguay Lat/Long