Impacts on water quality in the upper Elbow River

摘要

Recent work has found evidence of deterioration in water quality in the Elbow River upstream from Calgary, Alberta, Canada. We sampled this basin to describe spatial and temporal trends and factors that could be contributing to this deterioration. Sources near Calgary generally contributed most of the total phosphorus (TP) entering the river, and most total suspended solids (TSS) during low to average flows. During high flows, a large influx of TSS occurred further upstream. Sources of TP could include runoff from residential developments and agriculture, and groundwater, while re-suspension of bed material, erosion, and storm sewers may contribute TSS. Increasing trends in dissolved phosphorus (TDP) and ammonia suggest that sources in this reach are also contributing dissolved nutrients. Appreciable loading of nitrate + nitrite also occurred near Calgary, with a significant increasing trend in nitrate + nitrite occurring at every Elbow River site and several tributaries. Fecal coliforms have increased significantly over time at a downstream site. Runoff from residential developments, agriculture, or contributions from groundwater could account for this trend. In the 2003 bacterial source tracking study, DNA markers from ruminant animals were found in samples from most locations sampled in this basin, even at some headwaters sites, but no human markers were found.