The main watersheds adjacent to the Bras de Jacob Ouest are: • north side:
Bras de Jacob, Desgagné lake, Côté lake, William lake brook,
rivière du Moulin,
Chicoutimi River,
Saguenay River; • east side:
rivière du Moulin,
Bras Henriette,
la Petite Décharge,
Rivière à Mars; • south side:
Cyriac River, Lac aux Rats Musqués; • west side:
Simoncouche River,
Simoncouche Lake, Des Îlets lake, Dépôt lake,
Cyriac River,
Chicoutimi River. The Bras de Jacob Ouest rises at the mouth of Lac Graveline (length: ; altitude: ) in a forest area in the
Laurentides Wildlife Reserve. This source is located at: • north-east of
route 175; • northwest of a curve in the course of the
Cyriac River; • east of Lac des Îlets; • south-east of the confluence of the
Simoncouche River and
Kenogami Lake; • south-east of the village of
Laterrière; • south-west of the confluence of Bras de Jacob Ouest and
Bras de Jacob; • south-east of the Portage-des-Roches dam, erected at the head of the
Chicoutimi River. The Bras de Jacob Ouest spills onto the south bank of the
Bras de Jacob. This confluence is located at: • east of
route 175; • south-east of the confluence of the
Simoncouche River and
Kenogami Lake; • south-west of the village of
Laterrière; • south-west of the confluence of Jacob's arm and
rivière du Moulin; • south-east of the Portage-des-Roches dam, erected at the head of the
Chicoutimi River; • south of the confluence of the
rivière du Moulin and the
Saguenay River in the
Chicoutimi sector of the city of
Saguenay. From the mouth of Bras de Jacob Ouest, the current successively take the courses of
Bras de Jacob on towards the east, the course of the
rivière du Moulin on towards the north, then the course of the
Saguenay River on towards the east until at
Tadoussac where it merges with the
Saint Lawrence Estuary. == Toponymy ==