The James Bay Project refers to the construction of a series of hydroelectric power stations on the La Grande River in northwestern Quebec, Canada by state-owned utility Hydro-Québec, and the diversion of neighbouring rivers into the La Grande watershed. It is located between James Bay to the west and Labrador to the east, and its waters flow from the Laurentian Plateau of the Canadian Shield. The project covers an area the size of New York State and is one of the largest hydroelectric systems in the world. It has cost upwards of US$20 billion to build and has an installed generating capacity of 15,244 megawatts, at the cost of 7,000 square miles of Cree hunting lands. If fully expanded to include all of the original planned dams, as well as the additional James Bay II projects, the system would generate a total of 27,000 MW, making it the largest hydroelectric system in the world. It has been built since 1974 by James Bay Energy (SDBJ) for Hydro-Québec.

La Grande River is a river in northwestern Quebec, Canada, rising in the highlands of the north-central part of the province and flowing roughly 900 km (560 mi) west to its drainage at James Bay. It is the second-longest river in the province, surpassed only by the Saint Lawrence River.