Groundwater - surface water interaction and water quality in the lower Elbow River, Alberta

Abstract

Current river water quality monitoring programs typically fail to consider surface and groundwater interaction when studying non point source(s) (NPS) effects. This study investigates water quality degradation in the Elbow River in the context of surface and groundwater interaction. Although the groundwater flow directions in the adjacent alluvial aquifer can vary seasonally by more then 40", they are predominantly sub-parallel to the Elbow River. Septic effluent from Bragg Creek Hamlet is thought to migrate in the groundwater as far as 5 to 12 km before discharging to the river. An estimated chloride mass flux of 53 kg day-1 in the alluvial aquifer just downgradient of Bragg Creek is based on piezometer testing and groundwater sampling. This is about 10% of the chloride mass flux increase observed in the river within the study area. This suggests another, more substantial, source of chloride mass loading to the river. Geologic sources, cattle grazing on the alluvial aquifer, road salting, golf course fertilizer use, and wildlife are potential candidates.