| St. Mary River | |
| River | |
| Country | Canada |
|---|---|
| Province | British Columbia |
| Source | Purcell Wilderness Conservancy |
| - location | Purcell Mountains |
| - coordinates | 49°55′N 116°34′W / 49.917°N 116.567°W |
| Mouth | Kootenay River |
| - location | Fort Steele |
| - coordinates | 49°37′N 115°39′W / 49.617°N 115.650°WCoordinates: 49°37′N 115°39′W / 49.617°N 115.650°W |
The St. Mary River (sometimes represented as the St. Mary's River) is a river in the East Kootenay region of British Columbia. It rises in the Purcell Mountains and flows in a generally southeasterly direction to its confluence with the Kootenay River at Fort Steele, British Columbia.