Trace organic compounds in rivers, streams, and wastewater in southeastern Alberta, Canada

Abstract

We selected 14 anthropogenic organic compounds representing major classes of potential contaminants for analysis to determine their occurrence in the South Saskatchewan River and its tributaries near irrigated farmland and the only urban center in southeast Alberta, Canada. Agriculture and urban runoff and discharges seem to have little impact on the quality of surface water based on samples taken above and below Medicine Hat/Redcliff in the South Saskatchewan River and local tributaries. Samples of river water, tributary water, and raw and treated wastewater taken over a period of 3 years allowed an estimation of the impact of trace organic compounds from urban and agricultural activities on water quality. Of the 14 compounds investigated, 10 were detected in concentrations above the detection limit in at least one surface water sample and 9 at concentrations above the detection limit in sewage samples. The wastewater treatment plant removed indicator compounds to varying degrees, and the volume of treated effluent discharge was <1% of the river, even during the lowest flow conditions, thereby minimizing potential impact. Discharge in the river and tributaries varied by an order of magnitude over the period of study, including 2 major flood events in the South Saskatchewan River. Potential health or environmental effects were difficult to evaluate from a regulatory perspective because few guidelines are available for reference.