Lac Sir-John is a Lake located in Lachute; Argenteuil, Quebec and has an elevation of 201 meters.

• Latitude: 45° 43' 28'' North   (decimal: 45.7244444)
• Longitude: 74° 17' 18'' West   (decimal: -74.2883333)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Elevation: 201 meters
• Location: Lachute; Argenteuil
• Atlas of Canada Locator Map: Lac Sir-John
• GPS Coordinate Locator Map: Lac Sir-John Lat/Long