Lac Castelnau is a Lake located in Baie-Comeau; Manicouagan, Quebec and has an elevation of 145 meters.

• Latitude: 49° 16' 20'' North   (decimal: 49.2722688)
• Longitude: 68° 12' 51'' West   (decimal: -68.2141943)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Elevation: 145 meters
• Location: Baie-Comeau; Manicouagan
• Atlas of Canada Locator Map: Lac Castelnau
• GPS Coordinate Locator Map: Lac Castelnau Lat/Long