Professor St-Hilaire is interested in the spatial and temporal variability of abiotic variables in rivers and in the information content of measurement station networks. His work includes modelling of the thermal regime and sediment dynamics of rivers. He also conducts statistical analyses of environmental flows in relation to climate change. His main research areas are: Axis 1: Hydrological and thermal modelling in rivers; Axis 2: Environmental flows and modelling of aquatic habitats; Axis 3: Hydrology and water quality of peatlands.