Screening-level ecological risk assessment of stormwater quality in Banff National Park, Alberta, Canada

Mountain protected areas are highly vulnerable to land use changes and tourism pressures, which can present as degraded water quality from urban stormwater contamination. Using a standardized framework, we conducted a screening-level ecological risk assessment (SLERA) of stormwater quality in the main townsite of Banff National Park, Alberta, Canada. The town of Banff is home to approximately 8,300 residents but experiences large-scale anthropogenic pressure from more than four million annual visitors. End-of-pipe grab samples were collected from four outfalls and two upstream sites representing background conditions, during 21 rainfall and snowmelt events. Samples were assessed using a water quality index (WQI), which rated stormwater effluent from three outfalls as ‘poor’ and one outfall as ‘marginal’, while background sites rated ‘good’ and ‘excellent’. The outfalls exhibited similar contaminant profiles, with frequent WQI exceedances for cadmium, copper, lead, zinc, total phosphorous, total suspended solids and turbidity. Chloride exceedances were observed exclusively in snowmelt and approached concentrations typical of large municipalities. Embedding a WQI within a SLERA framework provides a novel and transferable approach for preliminary risk identification where data and monitoring capacity are limited, particularly in small, cold climate municipalities.