The Rivière du Sault au Mouton flows south, on the north shore of the St. Lawrence River, in the unorganized territory of Lac-au-Brochet and the municipality of Longue-Rive, in the La Haute-Côte-Nord Regional County Municipality in the administrative region of Côte-Nord, in the province of Quebec, in Canada.

The lower part of the hydrographic slope of the "Sault au Mouton river" is served by the route 138 which crosses it near its mouth.

From this last lake, a secondary forest road goes up the valley to serve the east of Lac de la Petite Montagne.

The main neighboring hydrographic slopes of the Sault au Mouton river are: The "Sault au Mouton river" takes its source at the mouth of the "Grand-Mère lake" (length: 0.6 km (0.37 mi); altitude: 494 m (1,621 ft)) in forest zone, in the unorganized territory of Lac-au-Brochet.

[1] From the mouth of "Lac de la Grand-Mère", the course of the "Sault au Mouton river" flows mainly in the forest area over 60.2 km (37.4 mi) according to the following segments: Upper course of the Sault au Mouton river (30.7 km (19.1 mi) segment) Lower course of the Sault au Mouton river (segment of 29.5 km (18.3 mi)) The Sault au Mouton river flows over a sandstone (at low tide) up to 2.5 km (1.6 mi) on the west bank of the Saint Lawrence River in the sector Sault-au-Mouton of the municipality of Longue-Rive in the bay of Mille-Vaches which is part of the "Hauts-Fonds de Mille-Vaches".