| Eastmain | |
| Map: | Eastmain map.png |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Quebec |
| Subdivision Type3: | Region |
| Subdivision Name3: | Jamésie |
| Length: | 756km (470miles)[1] |
| Discharge1 Avg: | 930m3/s |
| Source1: | Lac Bréhat |
| Source1 Location: | Baie-James, Nord-du-Québec, Québec, Canada |
| Source1 Coordinates: | 52.525°N -70.8667°W |
| Source1 Elevation: | 554m (1,818feet) |
| Mouth: | James Bay |
| Mouth Location: | Eastmain, Nord-du-Québec, Quebec, Canada |
| Mouth Coordinates: | 52.2417°N -78.5667°W |
| Mouth Elevation: | 0m (00feet) |
| Basin Size: | 46400km2 |
The Eastmain River, formerly written East Main, is a river in west central Quebec. It rises in central Quebec and flows 800km (500miles) west to James Bay, draining an area of 46400km2. The First Nations Cree village of Eastmain is located beside the mouth.
Eastmain is a compounding of the river's former name East Main,[2] which was taken from the former Hudson's Bay Company outpost at its mouth. This post controlled company trading operations in the East Main District on the eastern side of James Bay.
Since the late 1980s, most of the waters of the Eastmain River have been diverted and flow northwards through the Opinaca Reservoir, with a surface area of about, and into the Robert-Bourassa Reservoir of Hydro-Québec's La Grande Complex. The remainder of the Eastmain River contains only about 10 percent of the volume of its former flow, and is now subject to freeze-up in winter (see photo). These changes have affected the Cree and Inuit peoples who live along the Eastmain River and James Bay coast, making it more difficult for them to travel in winter and reducing their access to fish in the river.
In 2005, a further hydroelectric project on the upper Eastmain River was under construction. The project was part of the original hydroelectric project provided for by the James Bay and Northern Quebec Agreement of 1975. The Eastmain Reservoir will eventually have a surface area of about, and the Eastmain-1 power plant will generate a maximum of 900 MW.
The mouth of the Eastmain was a centre of the Hudson's Bay Company fur trade. Charles Bayly reached it from Rupert House in the 1670s. After Rupert House was destroyed in 1686, the area was visited by a ship from York Factory. In 1723 to 1724, Joseph Myatt of the Hudson's Bay Company built a post.[3]