The mountain headwaters of the South Saskatchewan River Basin are among the province’s most climate-vulnerable waters. Supplying over 90% of annual stream flow compared to lowland reaches, projected shifts in climate and hydrologic regimes raise concerns regarding future water security, quality, and aquatic community health. Mountain headwater streams are substantially groundwater dependent and provide a year-round ability to moderate climate driven hydrologic variability; however, the extent of this buffering capacity remains poorly understood. The Elbow River is a small (average flow ~12 m3/s), unregulated eastern slopes river that supplies ~40% of 1.3M people in the Calgary region. The Elbow River is estimated to be >60% groundwater, providing critical refugia for several threatened cold-water salmonid species. Topography and climate influence spatial and temporal variability of stream temperature regimes, particularly air temperature, precipitation, melt events, and groundwater. Substantial interannual variability in snowpack, spring rain, and snowmelt provides a window into their influence on stream temperature. Understanding how stream temperature responds to a shifting climate is critical for future resource management and aquatic ecological integrity. This research utilizes an interdisciplinary approach to investigate how climate induced hydrologic variability influences stream temperature along an elevational and spatial gradient of the Upper Elbow River. Continuous stream temperature and stage monitoring are complemented by geochemical and isotopic analyses of stream water to investigate provenance, seasonal separation, and groundwater contributions. Additionally, benthic macroinvertebrates are evaluated to act as a proxy for ecological expression in response to interannual variability in hydrologic dynamics and the moderating influence of groundwater.