| Rivière des Perdrix | |
| 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: | Montmagny Regional County Municipality |
| Source1: | Mountain and forest streams |
| Source1 Location: | Cap-Saint-Ignace |
| Mouth: | Estuary of Saint Lawrence |
| Mouth Location: | Notre-Dame-du-Rosaire |
| Progression: | rivière des Perdrix, Bras Saint-Nicolas, Rivière du Sud (Montmagny), St. Lawrence River |
| Tributaries Left: | (upstream) |
| Tributaries Right: | (upstream) |
The Inconnue River (in French: rivière Inconnue) flows in the municipalities of Cap-Saint-Ignace and Notre-Dame-du-Rosaire, in the Montmagny Regional County Municipality, in the administrative region of Chaudière-Appalaches, in Quebec, in Canada.
The "Inconnue River" is a tributary of the east bank of the rivière des Perdrix, which flows towards the south bank of the Bras Saint-Nicolas; from there, the current flows to the southeast shore of the rivière du Sud (Montmagny); the latter flows north-east to the south shore of the St. Lawrence River.
The main neighboring watersheds of the Inconnue River are:
The Inconnue River has its source on the north slope of the Notre Dame Mountains, in the township of Bourdages, in the municipality of Cap-Saint-Ignace. Several branches of mountain and forest streams feed the head of the Inconnue River.
From its source, the Inconnue River flows through mountainous and forested areas over, divided into the following segments:
The Inconnue River flows on the east bank of the Perdrix River (Bras Saint-Nicolas) in a small valley north of the Érables mountain. This confluence is located from the south shore of the St. Lawrence River, north of the village of Notre-Dame-du-Rosaire and at southeast of the Montmagny highway bridge.[1]
The toponym Rivière Inconnue was formalized on December 5, 1968, at the Commission de toponymie du Québec.[2]