The Alberta Oil Sands region is a large area of land in Western Canada that contains vast quantities of oil sands among other natural resources. The area is also home to a complex surface water and groundwater system, but the interaction between them and the associated water-based resources has not yet been fully understood. To analyse this interaction, a study has been conducted to understand and quantify groundwater recharge, using a variety of methods, including the use of stable isotopes of water (2-H and 18-O) to identify and separate baseflows, and to determine the natural range of variability in baseflow. A comparison of isotope-based hydrograph separation methods with recursive digital filtering methods (the BFLOW model) was also conducted and showed that BFLOW overestimates baseflow contributions, as it considers all low frequency contributions including those originating from glacier melt, lake outflows, and wetlands. The findings of this research provide valuable insights into the surface-groundwater interaction pathways and are the first step in generating a spatially and temporally distributed recharge boundary condition for hydrogeological modelling. By better understanding the role of surface water in subsurface recharge and the associated potential vulnerabilities of the hydrological and hydrogeological systems to anthropogenic changes within the oil sands region, this study will enable informed decision making for the sustainable management of water-based resources.