The main neighboring watersheds of the Rouge River are: • north side:
Maskinongé River; • west side:
Petite rivière Saumon,
Petite-Nation River,
Maskinongé River,
Nominingue River; • east side:
Kingham River,
Calumet River,
Beaven River,
Diable River,
Macaza River,
Lenoir River; • south side:
Ottawa River. The Rouge river has its source at Lac de la Fougère, located at the northern end of the township of Dupont, in the unorganized territory of
Lac-Matawin at about of altitude. From Fougère Lake, the Rouge River flows south, crossing Red Lake formed by the widening of the river. The river winds along the entire length of the western limit of the
Rouge-Matawin Wildlife Reserve that it separates from the
Zec de la Maison-de-Pierre. When leaving the wildlife reserve, it has already lost more than in altitude. The landscape also changes from a rocky plateau to a sandy plain and crosses its first village,
L'Ascension, then
Labelle and
La Conception. About twenty kilometers downstream, it meets the
Nominingue River and then changes its course in a south-southeast direction. At the end of a route, the Red River flows on the north shore of the
Ottawa River between the village of
Calumet and the municipality of
Pointe-au-Chêne, in the territory of the
Argenteuil Regional County Municipality. In the last long segment, the river has several falls and rapids, including the First, Second and Third Nigger-Eddy Rapids. Among its main tributaries, the Rouge River receives water from: • east side: the
Lenoir River,
Macaza River and the
rivière du Diable rivers, passing to
Saint-Jovite; • west side: the
Maskinongé River and the
Nominingue River. The Red River watershed covers . The course of the river is generally peaceful (except the last segment of ) with many U and S meanders. ==2019 floods==