| Tortue River South-West | |
| Pushpin Map: | Quebec |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Quebec |
| Subdivision Type3: | Region |
| Subdivision Name3: | Chaudière-Appalaches |
| Subdivision Type4: | MRC |
| Subdivision Name4: | L'Islet Regional County Municipality, Montmagny Regional County Municipality |
| Source1: | Agricultural stream |
| Source1 Location: | L'Islet |
| Mouth: | Tortue River |
| Mouth Location: | L'Islet |
| Basin Size: | NaNkm (-2,147,483,648miles) |
| Tributaries Left: | (upstream) |
| Tributaries Right: | (upstream) Rivière du Petit Moulin |
The Tortue River South-West River (in French: rivière Tortue Sud-Ouest) is a tributary of the west bank of the Tortue River, which flows on the south shore of the St. Lawrence River, east of the village of L'Islet-sur-Mer.[1]
The Southwest Tortue River toponym is derived from the name of the main river, the Tortue River. The use of animal names is frequent in French Canadian toponymy to designate watercourses. The term turtle usually refers to slow current due to the low drop.
The toponym Rivière Tortue Sud-Ouest was made official on December 5, 1968 at the Commission de toponymie du Québec.[2]