It generally flows north-west in the municipalities of Saint-Louis (MRC Les Maskoutains) and Sainte-Victoire (MRC Pierre-De Saurel), in the administrative region of Montérégie, on the South Shore of St. Lawrence River, in Quebec, Canada.

[1] The Lemoine River has its source in an agricultural zone at the confluence of the "Décharge des Huit" stream in the municipality of Saint-Louis.

This source is located near Chemin du Rang Prescott (north side).

From its source, the course of the Lemoine river descends on 9.0 kilometres (5.6 mi) almost entirely in agricultural zone, with a drop of 9 metres (30 ft), according to the following segments: The mouth of the Lemoine river corresponds to the confluence of the Benoit stream and is the source of the rivière Pot au Beurre.

The toponym "rivière Lemoine" was made official on January 21, 1975, in the place name bank of the Commission de toponymie du Québec.