The hydrographic slopes adjacent to the Toussaint River are:

• north side: Surprise Lake (Roy River), Caopatina Lake, Des Vents Lake (Opawica River), Opawica River;
• east side: Kakospictikweak River, Kanatakompeak Bay, Gouin Reservoir, McSweeney Lake, Magnan Lake, Wapous River;
• south side: Kamitcikamak Lake, Gouin Reservoir, Du Mâle Lake (Gouin Reservoir), Nemio River, Bureau Lake;
• west side: De la Rencontre Creek, Du Mâle Lake (Gouin Reservoir), Plamondon Creek (Gouin Reservoir), Pascagama River, Saint-Cyr Lake (Saint-Cyr River South), Macho River.

The Toussaint River originates at the mouth of Coutras Lake (length: 1.1 kilometres (0.68 mi), altitude: 480 metres (1,570 ft)) located in the canton of Chambalon. The mouth of this head lake is located at:

• 41.6 kilometres (25.8 mi) north of the mouth of the Toussaint River (confluence with a bay of Gouin Reservoir);
• 47.7 kilometres (29.6 mi) north of the village center of Obedjiwan, Quebec (located on a peninsula on the north shore of Gouin Reservoir);
• 97.7 kilometres (60.7 mi) northwest of the dam at the mouth of the Gouin Reservoir (confluence with the Saint-Maurice River);
• 152.5 kilometres (94.8 mi) north-east of the village center of Wemotaci, Quebec;
• 212.8 kilometres (132.2 mi) northwest of downtown La Tuque.^[2]

From the mouth of Coudras Lake, the course of the Toussaint River flows over 56.0 kilometres (34.8 mi) according to the following segments:

Upper course of Toussaint River (segment of 28.6 kilometres (17.8 mi))

• 2.3 kilometres (1.4 mi) north-east, crossing a small unidentified lake (altitude: 468 metres (1,535 ft)) on 0.5 kilometres (0.31 mi), up to its mouth;
• 6.6 kilometres (4.1 mi) south-east across Lingen Lake at 2.1 kilometres (1.3 mi) (length: 2.9 kilometres (1.8 mi); altitude: 433 metres (1,421 ft) to the mouth of Lake Lingen. Note: This lake straddles the canton of Chambalon and Balete;
• 6.9 kilometres (4.3 mi) south-east in Balete Township crossing over Balete Lake at 4.2 kilometres (2.6 mi) (length: 5.4 kilometres (3.4 mi); 428 metres (1,404 ft)), to the northern limit of the town of La Tuque;
• 0.7 kilometres (0.43 mi) southeasterly across a 2.6 kilometres (1.6 mi) a lake formed by the widening of the river to its mouth;
• 6.2 kilometres (3.9 mi) to the southwest by collecting Augusta Creek (coming from the north) at the beginning of the segment and crossing a lake formed by the widening of the river to the eastern limit of the township of Marceau;
• 5.6 kilometres (3.5 mi) southwesterly in the township of Marceau, to the northern limit of the township of Perrier;

Lower course of Toussaint River (segment of 27.4 kilometres (17.0 mi))

• 6.0 kilometres (3.7 mi) in Perrier Township including crossing Perrier Lake (length: 4.6 kilometres (2.9 mi); altitude: 413 metres (1,355 ft)) over the full length, to its mouth;
• 13.5 kilometres (8.4 mi) south, getting from Ouest the water from Lake Kamatcimiskowok and forming a hook on 2.2 kilometres (1.4 mi) to the east, then crossing two lakes, to the northern limit of the township of Toussaint;
• 5.9 kilometres (3.7 mi) southerly in the township of Toussaint across Lake Gaudet (length:3.6 kilometres (2.2 mi); altitude: 405 metres (1,329 ft)) on its full length to its mouth. Note: The pass Kaopitciwok is located at the northern part of Lake Gaudet which receives the water from the outlet (from North-East) of lake Aciminik;
• 2.0 kilometres (1.2 mi) towards the South cutting forested road R2046, until the confluence of the Toussaint River with the Kamitcikamak Lake which constitutes an extension on the North shore of the Gouin Reservoir.^[3]

The confluence of the "Toussaint River" with the Kamitcikamak Lake is located at:

• 69.9 kilometres (43.4 mi) northwest of Gouin Dam;
• 6.2 kilometres (3.9 mi) north-east of the village center of Obedjiwan, Quebec;
• 116.5 kilometres (72.4 mi) northwest of the village center of Wemotaci, Quebec;
• 208.1 kilometres (129.3 mi) north-west of downtown La Tuque;
• 308.1 kilometres (191.4 mi) northwest of the mouth of the Saint-Maurice River (confluence with the St. Lawrence River at Trois-Rivières).

The Toussaint River flows into the bottom of a bay of Kamitcikamak Lake which extends over 4.1 kilometres (2.5 mi) on the north shore of Gouin Reservoir; this lake is barred on the east side by a peninsula stretching southward on 8.0 kilometres (5.0 mi), from the north shore of the Gouin Reservoir. From the mouth of this lake, the current flows south-easterly on 96.1 kilometres (59.7 mi) skirting the village of Obedjiwan, Quebec and crossing the Gouin Reservoir including Kikendatch Bay] to the Gouin Dam. From there, the current flows along the Saint-Maurice River to Trois-Rivières, where it flows into the St. Lawrence River.

• Saint-Maurice River
• Gouin Reservoir, a body of water
• Obedjiwan, Quebec, a village
• Eeyou Istchee James Bay (municipality)
• La Tuque, a city
• List of rivers of Quebec