The Red River takes its source at the mouth of Couture Lake (length: ; altitude: ), taking the shape of a mushroom and located in the north-eastern part of Chertsey. The mouth of this lake is located west of the center of the village of
Sainte-Béatrix, at north of the center of village of
Rawdon, at east of the Ouareau river. From the mouth of Couture Lake, the Rouge River flows over , with a drop of , according to the following segments:
Upper course of Rouge River (segment of ) • towards the south-east, up to the limit of Saint-Alphonse-Rodriguez; • north in Saint-Alphonse-Rodriguez, to the outlet of Lac Gareau (coming from the north); • towards the northeast, to the northern end of Lac Gareau; • towards the south, successively crossing Lac Joly, Lac de la Fromantière (length: ; altitude: ) and Lake Dontigny (length: ; altitude: ), to the dam to the south of the latter; • south to the outlet of Morgan Lake (coming from the west); • towards the south-east, along the limit between Saint-Alphonse-Rodriguez and Chertsey, to the outlet of lac Marchand (coming from the east); • south into Chertsey, to the forest road bridge; • southward, to the north shore of Rawdon lake; • towards the south, crossing Rawdon lake (length: ; altitude: ) over its full length, up to at the dam at its mouth. Note: Rawdon lake follows the shape of the letter L, the foot of which is oriented towards the east; this lake is located in the village of Rawdon;
Intermediate course of the Rouge River (segment of ) From the mouth of Rawdon Lake, the Rouge River flows over: • east passing north of the village, forming a hook south, then a large S, to the
route 348 (Kildare Road); • (or in a direct line) to the east, first forming a loop to the north, then two loops to the south, collecting the discharge (coming from the southwest) of Lake Joe which is located in the middle of a campground, and meandering until crossing the Nadeau road, until the confluence of the Blanche river (coming from the northwest ); • (or in a direct line) eastward, crossing Lane Road, 5th Rang Road/Wilfrid Road and chemin du 4th Rang, and winding up to the limit of Saint-Ambroise-de-Kildare; • (or in a direct line) towards the south-east, winding up to the limit of Chertsey; • (or in a direct line) south-east in Chertsey, winding up to the
route 346 (rue Héroux-Rang Double); • (or in a direct line) towards the southeast, collecting the waters of Le Grand Ruisseau (Red River) (coming from the north) and meandering to the edge of Crabtree; • (or in a direct line) south-east in Crabtree, crossing the chemin Saint-Jacques and the
route 158 at the end of the segment and winding up to the confluence of the river. The Red River empties on the north bank of the Ouareau river which descends towards the southeast to the north bank of the
L'Assomption River. This confluence is located at: • northwest of the
St. Lawrence River; • north of the Crabtree bridge spanning the Ouareau river; • southeast of downtown
Joliette. ==Toponymy==