The Rivière à l'Ours is a tributary of Ashuapmushuan River, flowing successively in the unorganized territory of Lac-Ashuapmushuan, in the municipalities of Saint-Félicien and Saint-Prime, in the Le Domaine-du-Roy Regional County Municipality, in the administrative region of Saguenay–Lac-Saint-Jean, in the province of Quebec, in Canada.

The surface of the Bear River is usually frozen from the beginning of December to the end of March, except the rapids areas; however, safe traffic on the ice is generally from mid-December to mid-March.

The mouth of Lac à l'Ours is located at: From the mouth of Lac à l'Ours, the Rivière à l'Ours flows over 55 km (34 mi) with a drop of 315 m (1,033 ft), especially in forest areas (part upper), then agricultural in the lower part, according to the following segments: The Bear River flows on the southwest bank of the Ashuapmushuan River, just downstream from a peninsula attached to the south bank and stretching to the north.

This confluence is located at: From the mouth of the Bear River, the current descends the course of the Ashuapmushuan River towards the southeast on 7.3 km (4.5 mi), then crosses Lake Saint-Jean east on 41.1 km (25.5 mi) (i.e. its full length), take the course of the Saguenay River via the Petite Décharge on 172.3 km (107.1 mi) east to Tadoussac where it merges with the Estuary of Saint Lawrence.

[2] The toponym "rivière à l'Ours" was formalized on December 5, 1968, at the Place Names Bank of the Commission de toponymie du Québec.