Hydrologic and Microbial Risk Characterization of an Arctic Wetland Treatment Area

Abstract

This study focused on the hydrologic characterization and microbial risk associated with a passive wastewater treatment wetland in Qamani’tuaq (Baker Lake), Nunavut. Site-specific field data was utilized in conjunction with hydrologic-contaminant modelling to simulate E. coli concentrations throughout the system. The results were applied to a quantitative microbial risk assessment (QMRA), along with information obtained through community consultation, to characterize the potential microbial health risk for multiple exposure pathways and hydrologic scenarios. Several water quality parameters exceeded treatment criteria specified in the Hamlet’s water license, while short hydraulic retention times were the primary reason for ineffective treatment performance during spring freshet. Simulated E. coli concentrations throughout the system indicated that dilution from external watershed contributions was playing a large role in reducing bacteria concentrations, as opposed to biological degradation or treatment. Overall, the assessment predicted risk levels greater than the recommended health target (10-4) for four common exposure pathways.