The Port au Persil River (French: "Rivière du Port au Persil") is a tributary of the northwest shore of the St. Lawrence River, flowing into the city of Saint-Siméon in the Charlevoix-Est Regional County Municipality, in the Capitale-Nationale administrative region, Quebec, Canada.

The upper part of the valley of this watercourse is served by Route 138 along the northwest shore of the St. Lawrence River.

Nevertheless, safe ice circulation is generally from late December to mid-March.

The main hydrographic slopes near the "Salmon Port River" are: The Port-au-Persil River rises from a mountain stream (elevation: 281 m (922 ft)) in a forest area southeast of "lac des Rats Musqués" (lake of the Musk Rats).

From its source, the course of the Port aux Persil river descends by traveling 9.4 km (5.8 mi) according to the following segments: The term "Port au Persil" is used in Quebec toponymy in the area of Saint-Siméon to designate: the harbor, the hamlet, the bay, the road, the lake, the river and a street.