| Trois Milles River | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Quebec |
| Subdivision Type3: | Region |
| Subdivision Name3: | Côte-Nord |
| Subdivision Type4: | Regional County Municipality |
| Subdivision Name4: | Minganie Regional County Municipality |
| Length: | 8.5km (05.3miles) |
| Source1: | Lake Princeton |
| Source1 Location: | L'Île-d'Anticosti |
| Source1 Coordinates: | 49.8713°N -64.1935°W |
| Source1 Elevation: | 68m (223feet) |
| Mouth: | Gulf of Saint Lawrence |
| Mouth Location: | L'Île-d'Anticosti |
| Mouth Coordinates: | 49.8228°N -64.3339°W |
| Mouth Elevation: | 1m (03feet) |
| Progression: | Lac Saint-Georges, Gamache River, Gamache Bay, Gulf of Saint Lawrence. |
| Tributaries Left: | (upstream) |
| Tributaries Right: | (upstream) |
The rivière Trois Milles (English: Three Mile River) is a tributary of Lake Saint-Georges (which is crossed by the Gamache River), flowing in the municipality of L'Île-d'Anticosti, in the Minganie Regional County Municipality, in the administrative region of Côte-Nord, in province of Quebec, in Canada.
The main forest road on Anticosti Island that starts from Port-Menier goes up this valley and cuts the river just south of Princeton Lake.
Airport operations are the main economic activity in this valley.
The Trois Milles River has its source at Princeton Lake (length: ; altitude:) located in the western part of Anticosti Island. Princeton Lake is fed by a stream (coming from the north). The mouth of this lake is located at the end of the bay on the south shore, at:
From its source, the Trois Milles river flows south-west between the Gamache river (located on the west side); and the rivière aux Canards (located on the east side).
From the mouth of Princeton Lake, the course of the Trois Milles River descends on, with a drop of, according to the following segments:
This confluence is located at east of the Pointe aux Pointe-Ouest point of Anticosti Island, at southeast of the shore north of the island and north of Gamache Bay. The Trois Milles River empties onto the northeast shore of Lac Saint-Georges, which in turn empties into Gamache Bay which is connected to the Gulf of St. Lawrence.[1]
This toponymic designation is based on the fact that the road leading to the airport crosses this watercourse three miles from the center of the village of Port-Menier.
The toponym "Rivière Trois Milles" was made official on September 12, 1974, at the "Banque des noms de lieux" de la Commission de toponymie du Québec.[2]