The Saint-Roch River is a tributary of the Big Black River (Maine), flowing in:
Quebec (Canada) in the administrative region of Chaudière-Appalaches, in L'Islet Regional County Municipality, in the municipalities of Sainte-Perpétue, Chaudière-Appalaches, Quebec, Saint-Omer, Quebec, Saint-Pamphile, Quebec;
Maine (United States) in the Aroostook County, Township T15 R15 Wels.
Especially in forested area, the river flows in a valley encircled by Notre Dame Mountains which are parts of Appalachian Mountains. Its course is situated between the Rochu River (or Little Saint Roch River) (West side) and the Gagnon River (West side).
The upper part of the "Saint-Roch River" begins in Notre Dame Mountains, in the municipality of Sainte-Perpétue, Chaudière-Appalaches, Quebec, in the L'Islet Regional County Municipality.
This source is located at:
15.0 kilometres (9.3 mi) northwest of the border between Quebec and Maine;
9.8 kilometres (6.1 mi) north-east from the village of Sainte-Perpétue, Chaudière-Appalaches, Quebec;
35.3 kilometres (21.9 mi) northwest from the confluence of the Saint-Roch River;
35.0 kilometres (21.7 mi) to the southeast from the village of Saint-Jean-Port-Joli.
St. Roch river flows 44.0 kilometres (27.3 mi) according to the following segments:
Upper river course (segment of 27.6 kilometres (17.1 mi) in Quebec)
From the source in the mountains, the Saint-Roch river flows:
8.1 kilometres (5.0 mi) to the South in Sainte-Perpétue, Chaudière-Appalaches, Quebec, cutting the path of rank Taché East, to the boundary of the municipality of Saint-Omer;
1.6 kilometres (0.99 mi) to the South in Saint-Omer, to the boundary of the municipality of Sainte-Perpétue, Chaudière-Appalaches, Quebec;
150 metres (490 ft) to the South in Sainte-Perpétue, Chaudière-Appalaches, Quebec, to the confluence of the Saint-Roch North River (from the West);
0.8 kilometres (0.50 mi) to the southeast, to the boundary of the municipality of Saint-Pamphile, Quebec;
2.8 kilometres (1.7 mi) (or 1.5 kilometres (0.93 mi) in direct line), winding towards the southeast, to the bridge of the Little North rank;
2.1 kilometres (1.3 mi) (or 1.5 kilometres (0.93 mi) in direct line), winding towards the southeast, to the bridge of the rank of Pelletier;
7.3 kilometres (4.5 mi) (or 3.1 kilometres (1.9 mi) direct line), winding towards the southeast and straddling the boundary between Saint-Omer, Quebec and Saint-Pamphile, Quebec, to the bridge of the rank of Gagnon;
2.3 kilometres (1.4 mi) (or 1.4 kilometres (0.87 mi) in direct line), winding towards the southeast, to the bridge of the 6th rank;
1.6 kilometres (0.99 mi) to the southeast, to the confluence of the Gagnon River (from the southwest);
0.8 kilometres (0.50 mi) to the South-East, to the border between Quebec and Maine.
Lower course of the river (segment of 16.4 kilometres (10.2 mi) in Maine designated Shields Branch)
From the border between Quebec and Maine, the river "Shields Branch" runs on:
2.0 kilometres (1.2 mi) to the southeast in the Maine, to the Little Saint Roch River (from the Northeast). Note: This river has its source in Quebec where it is designated Brochu River;
9.3 kilometres (5.8 mi) (or 4.7 kilometres (2.9 mi) in direct line) to the southeast, winding end segment to the highway bridge;
5.1 kilometres (3.2 mi) (or 2.3 kilometres (1.4 mi) in direct line) to the southeast, winding up to the confluence of the river.
The "Saint-Roch River" empties into a river curve on the North shore of the Big Black River, in Township T14 R15 Wels, the Aroostook County. This confluence is located:
8.5 kilometres (5.3 mi) southeast of the border between Canada and US;
13.7 kilometres (8.5 mi) west of the confluence of the Big Black River;
11.6 kilometres (7.2 mi) southeast of the village center of Saint-Pamphile, Quebec, in Quebec.
