Analysis of Fecal Bacteria and Pathogen Levels in Storm-Water Runoff from Suburban Watersheds.

Analysis of fecal bacteria and pathogen levels in storm-water runoff from suburban watersheds Robert A. Sowah, Mussie Y. Habteselassie, David E. Radcliffe Runoff from suburban watersheds can carry fecal bacteria originating from diverse sources. The concentrations of fecal bacteria and pathogens can vary temporally and can be influenced by the duration and intensity of storm events. Identifying the dynamics of fecal bacteria and pathogen concentration in real-time during a storm event can support attempts to reduce the risk of human exposure to fecal pathogens in our waterways. In this study, we monitored in real-time, the concentrations of fecal bacteria and pathogen in four gaged watersheds in metropolitan Atlanta. Four headwater streams in the study area were fitted with ISCO automated samplers that were set to collect stream water samples during storms. Storm samples were then analysed for fecal indicator bacteria (E. Coli and enterococci), host-associated Bacteroidales markers (human, ruminant and dog) and human pathogens (shiga toxin producing E. Coli [STEC] and human adenovirus) over a three year period. Statistical evaluation of bacteria concentrations in storm-runoff shows that ruminant animals were the dominant source of fecal bacteria in the watersheds. The waterborne pathogens STEC and human adenovirus were frequently dectected in storm-water runoff and was moderately correlated with fecal bacteria concentrations. This study shows that suburban watersheds with little agricultural land use could contribute significantly to pathogen loads stemming from septic systems and/or leaky sewer pipes.