The influence of storm-water sewer overflows on stream water quality and source tracking of fecal contamination

Abstract

This study was performed to find the influence of storm-water sewer overflows on stream water quality and to track nonpoint fecal pollutant sources. Based on the analysis of BOD5, CODcr, TN, TP, coliform bacteria and heavy metals from storm-water sewer overflows into the Ansan stream in Korea, during both dry and wet weather, it was found that the storm-water sewer overflows adversely affected stream water quality. Cd concentrations, especially, exceeded the standard of water quality needed for the health of human beings; also, a number of coliform bacteria were also found. TN concentrations in the upper stream were higher than those of other storm-water overflow points, and fecal bacteria concentrations mid- and downstream were higher than those of the upper stream. Antibiotic Resistance Analysis (ARA) was conducted to find more fundamental pollutant sources. ARA statistically confirmed livestock as a major source of the coliform bacteria in the upper stream, verifying that the major sources of pollution are fertilizers and livestock farming. ARA also showed that human beings were statistically confirmed as a major source of coliform bacteria in the mid- and downstream sections, which implies that a breach in the sewer line mid- and downstream could be present. Therefore, ARA was confirmed to be an effective non-point source-tracking tool in streams, with high reliability and efficiency.