The course of the Muskrat river "crosses the territory of the municipality of Adstock, in the Les Appalaches Regional County Municipality, in the administrative region of Chaudière-Appalaches, on the South Shore of the St. Lawrence River, in Quebec, Canada.

From Bolduc Lake, the Muskrat River flows on 5.3 kilometres (3.3 mi) towards the southwest in a forest environment, collecting water from the Poulin and Rodrigue rivers and passing east of the village of Saint-Daniel, up to its mouth.

[1] The mouth of the Muskrat river flows into a marsh area (on the east side) at the bottom of the "Baie aux Rats Musqués" which is an extension of the northeast shore of Grand lac Saint François.

Formerly, this river was also designated according to the French appellation: rivière aux Rats Musqués.

The toponym "Rivière Muskrat" was officially registered on August 4, 1969, at the Commission de toponymie du Québec.