The Eastmain-1 development is component of the La Grande complex as part of the James Bay Hydropower Project. The power stations are located on the west bank along a North-South axis.
During Construction, the 3 turbine-alternator groups of the Eastmain-1 power station had a combined power output of 480 megawatts, with annual production reaching 2.7 terawatts/hour. The normal drop height was of 63m, with an estimated water flowrate of 840 m3/s.
The adjacent Eastmain-1-A power station is fed by additional water flows from a partial diversion of the Rupert River, and was opened in November 2009 as part of the same Project. It is located 700 metres to the East of its sister power station, which whom it shares several characteristics.