The north end of the lake is 0.3 km south-west of the boundary of Sainte-Thècle.

The waters of Lake Fontaine pour the northwest at the end of a long bay in a small discharge of 0.5 km to the lake Nicolas that crosses North Mékinac River, which runs in the Lejeune Township of Sainte-Thècle to the south-west.

The northern part of the lake Fontaine resembles to the shape of the head of a dog schnauzer looking towards the southeast.

The "Watchtower fire path" passes near the lake (south side), this path leads to the ancient tower fender at the top of a mountain in southern of Archange Lake (Mékinac).

The "chemin of lake Fontaine" from the intersection of Route 159 at the north end of Lake Roberge (Grandes-Piles), and moves towards the northeast to cross the path "Joseph-St-Amant" that penetrates deep into the Lejeune Township of Sainte-Thècle.