ᐄᔑᔥᑲᐧᐱᔨᐤ ᓰᐲ ᐋᓯᒌᔅᒡ ᑳ ᒥᔪᐱᒥᔮᔨᒡ Erosion and shoreline stability

Navigation safety and shoreline stability are important for land users, as they directly affect travel and the use of La Grande Rivière. Bank, shore and channel conditions can be affected by changes in water levels and flow.

To better understand the current situation and possible impacts, a survey was carried out in summer 2025 with Eeyou land users. Observations were made on selected segments downstream of La Grande-1, Robert-Bourassa (La Grande-2), La Grande-3 and La Grande-4 generating stations, extending to the river mouth. Simulation studies were also conducted to examine possible changes in water levels and flow that could result from the potential La Grande capacity upgrades. All observations and data collected are currently being analyzed to identify and assess impacts on riverbanks, shorelines and delta dynamics.

Eeyou participation played a key role in the 2025 field studies on erosion along the Chisasibi (river), also known as the Grande Rivière. Eeyou land users joined the research team to share knowledge and observations. They provided insights on riverbank changes downstream of La Grande-3 during a flyover, contributed photos and details about a major 2003 landslide in the La Grande 1 reservoir area, and helped survey the estuary and a comparison area on the south bank.

Since the La Grande development, their observations highlighted increased erosion, loss of traditional use areas and risks to culturally significant sites, despite some shoreline protection efforts. For the Eeyou, the Chisasibi (river) was traditionally and is still a major travel route and a cultural landmark. Erosion currently occurring due to the operation of the La Grande complex not only alters the landscape but also creates navigation hazards and threatens important community, cultural and heritage sites.

Find out more in the Fact Sheet.