Lac Saint-Jean is within Rio Tinto Alcan’s (RTA’s) hydropower system and the shoreline is experiencing erosion problems caused by high water levels combined with wind waves generated by significant storms. For RTA to prepare for the next water level management agreement, Lasalle|NHC compiled historical data series and updated past studies. A suite of numerical models was developed based on the MIKE platform (MIKE 21 and LITPACK) to simulate hydrodynamic currents, wind-generated waves, and morphological changes induced by sediment transport due to the combined action of waves and currents. The models provided RTA with comprehensive tools to understand the process causing shoreline erosion and allowed assessment of the effectiveness of existing and proposed structural and water level management interventions, considering the impact of climate change.