Lac O'Brien is a Lake located in Alleyn-et-Cawood; Pontiac, Quebec and has an elevation of 196 meters.

• Latitude: 45° 53' 11'' North   (decimal: 45.8863889)
• Longitude: 76° 14' 48'' West   (decimal: -76.2466667)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Elevation: 196 meters
• Location: Alleyn-et-Cawood; Pontiac
• Atlas of Canada Locator Map: Lac O'Brien
• GPS Coordinate Locator Map: Lac O'Brien Lat/Long