Rivers in the mountains in western Canada have binary characters defined by snowmelt and storm runoff during the high-flow period of May-August, and groundwater contribution during the low-flow period that occupies the remaining seven to eight months of a year. This groundwater contribution is critically important as it sustains groundwater-dependent ecosystems by providing zones of thermal refugia for aquatic species, while sustaining low flows for other downstream water supply needs including hydropower generation and municipal water supply. Groundwater processes in alpine and subalpine environments are not well understood, but recent studies in the Canadian Rockies, Andes, and elsewhere have demonstrated the importance of alpine aquifers in regulating stream flow and providing buffering mechanisms against climate change. In the north, the presence of permafrost further complicates the groundwater system and how groundwater exchanges with surface water. The goals of this research are to 1) identify unique aquifer systems which represent common conditions 2) quantify hydrogeological response to glacial melt, snowmelt, and rainfall inputs 3) characterize effects of stream-groundwater exchange processes distribution and extent of thermal refugia 4) incorporate understanding of these processes into models and 5) develop tools to estimate groundwater contribution and its sensitivity to climate change and land-use practices