Combining targeted sampling and bacterial source tracking (bst) during calm and stormy conditions

In April 2004, high numbers of fecal enterococci triggered a beach advisory on Sea Island, GA. Targeted sampling, which finds fecal contamination much like the children’s game of “hot” and “cold,” was combined with three bacterial source tracking (BST) methods: Enterococcus speciation, the presence or absence of a human virulence factor in Enterococcus faecium, and fluorometry. During calm (i.e non-runoff) conditions, the likely contamination sources were wildlife feces and leaking sewer lines located on a creek of St. Simons Island, GA. Fluorometry quickly identified malfunctioning sewer lines. A test for human virulence factor was positive. During stormflow (i.e. runoff) conditions, the likely contamination sources were wildlife feces and effluent from two pipes. A test for human virulence factor was negative. Because the percentage of Ent. faecalis from the pipes was high (>30%), fecal contamination from wild birds was likely. This is the first report of targeted sampling during stormy conditions, and the first time fluorometry has been combined with targeted sampling.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources Facult