| Seine River | |
| Pushpin Map: | Canada Manitoba |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Manitoba |
| Source1: | Marchand, Manitoba area |
| Source1 Coordinates: | 49.4167°N -96.4603°W |
| Source1 Elevation: | 302m (991feet) |
| Mouth: | Red River of the North |
| Mouth Location: | Saint Boniface, Winnipeg, Manitoba |
| Mouth Coordinates: | 49.9°N -97.11°W |
| Mouth Elevation: | 226m (741feet) |
| Basin Size: | 2509sqkm[1] |
The Seine River (French: Rivière Seine) is a tributary of the Red River of the North that runs through southeastern Manitoba, Canada. It is one of the four rivers of the city of Winnipeg.
Its name comes from the Aboriginal word Tchimâhâgânisipi from Tchimâhâgân (meaning draw net or seine net) and sipi (river). The river rises in the Sandilands Provincial Forest near Steinbach and passes by or through the communities of Marchand, La Broquerie, Ste. Anne, and Lorette before reaching the Red River Floodway near the Winnipeg city limits.[2] At this point the river's channel is diverted under the Floodway into what is known as the "Seine River Siphon", which allows a flow of up to 4.5m3/s; any additional flow is diverted onto the Floodway. During a wet spring, the river often overflows its banks, sometimes flooding nearby houses. During a dry summer, the river is often reduced to a trickle.
Within the city, the Seine travels a tortuously meandering course, reaching the Red River at St. Boniface just north of The Forks. The lower section of its course in the city marks the east–west boundary between the southern section of St. Boniface and the suburb of St. Vital.It is a typical meandering river with a single main channel embanked within a flat, shallow valley. The river's banks are heavily treed, but pollution has been an issue in the city of Winnipeg.