Lac Monsieur is a Lake located in Notre-Dame-du-Rosaire; Montmagny, Quebec.

• Latitude: 46° 53' 26'' North   (decimal: 46.8906000)
• Longitude: 70° 25' 52'' West   (decimal: -70.4310999)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Notre-Dame-du-Rosaire; Montmagny
• GPS Coordinate Locator Map: Lac Monsieur Lat/Long