| Rivière de Grand-Saint-Louis | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Quebec |
| Subdivision Type3: | Region |
| Subdivision Name3: | Centre-du-Québec |
| Subdivision Type4: | MRC |
| Subdivision Name4: | Bécancour Regional County Municipality |
| Length: | 12.9km (08miles) |
| Discharge1 Avg: | NaNm3/s |
| Source1: | Forest streams |
| Source1 Location: | Bécancour |
| Source1 Coordinates: | 46.2375°N -72.3077°W |
| Source1 Elevation: | 78 |
| Mouth Location: | Bécancour |
| Mouth Coordinates: | 46.3247°N -72.3283°W |
| Mouth Elevation: | 18m (59feet) |
| Progression: | Gentilly South-West River, Gentilly River and St. Lawrence River |
| Basin Size: | NaNkm2 |
| Tributaries Left: | (from the mouth) Le Ruisseau |
| Tributaries Right: | (from the mouth) Poulet brook, Coumier brook |
The Rivière de Grand-Saint-Louis is a tributary of the Gentilly South-West River whose current flows successively into the Gentilly River and on the south bank of the St. Lawrence River.
The Grand-Saint-Louis river flows in the territory of the town of Bécancour, in the Bécancour Regional County Municipality, in the administrative region of Centre-du-Québec, in the province of Quebec, in Canada.
The main hydrographic slopes neighboring the "Grand-Saint-Louis river" are:
The "Grand-Saint-Louis river" originates in an agricultural area on the border of Saint-Sylvère and Bécancour. This area is located near the Route des Peupliers, north of the Bécancour River and west of the village of Bécancour. In this head area (east of the Bécancour River, four roads are designated by tree names: poplars, cherry trees, beech trees, elms and spruce trees.
From the intermunicipal limit between Saint-Sylvère and Bécancour, the course of the river flows in forest and agricultural area, over 12.9 km, with a drop of, according to the following segments:
The Grand-Saint-Louis river flows on the west bank of the Gentilly South-West River. This confluence is located 1.0 km southwest of the route 261, 215 m northwest of the route des épinettes, 1.7 km west from the Gentilly River and 4.3 km east of the Bécancour River.
The term "Saint-Louis" constitutes a family name of French origin.
The toponym "Rivière de Grand-Saint-Louis" was formalized on August 18, 1978 at the Commission de toponymie du Québec.[2]