The
Assomption River (in French
Rivière l'Assomption, named after the
Assumption of Mary) is the most important waterway in the
Lanaudière region of
Quebec,
Canada, is over long, and has a
drainage basin of . Its source is the
Mont Tremblant massif. Seven significant rivers flow into the Assomption (de la Boule, Versailles, Noire, la Chaloupe, Ouareau, Saint-Esprit, and Achigan) before it flows into the
Rivière des Prairies at
Repentigny, Quebec.