NEHA December 2022 Journal of Environmental Health

12 Volume 85 • Number 5 A D VANC EME N T O F T H E SCIENCE (Table 1). We found little evidence of chronic human contamination at any site, although human markers were detected sporadically below the lower limit for quantification but still above the limit of detection (Supplemental Table 2). The ruminant marker was also detected infrequently at the Lower Farm River and Sasco Brook, while there was no detection at Goodwives River (Supplemental Table 1). The sporadic detection of markers at these sites does little to explain the sources of contamination, as the detection of these markers did not correspond to elevated counts of E. coli (Figure 3). Markers associated with contamination by poultry, dogs, and cattle feces were not detected in any of the samples (Supplemental Table 2). Discussion The aim of this project was to develop a microbial source tracking program in coastal Connecticut and establish a scientific method for assessing the sources of fecal contamination that can lead to water body impairment. This study, however, did not detect significant human, domesticated animal, or wildlife contributions to the elevated bacteria levels in the three targeted watersheds. Our results suggest that the tested sources might not contribute to the observed elevated bacteria levels. This information is valuable considering the potential threat to public health that the discovery of human markers would have represented. Not finding a definitive answer on the contamination source, however, prevents the development of actionbased remediation recommendations. While genetic markers associated with human, poultry, dog, ruminant, and cattle feces were successfully implemented, the markers for avian (including seagull) contamination failed quality assurance procedures. At the time of this study, alternative markers for avian contamination had not yet been tested for use in studies of this type. A more consistent and reliable marker for geese is needed as well as additional markers to enable the detection of other potential sources of bacterial contamination such as rodents or other wildlife. The U.S. Environmental Protection Agency, CT DEEP, and other agencies recognize that indicator bacteria are not the basis of a human health risk but rather a proxy for other more serious disease-causing organRelationship Between E. coli Levels and GenBac3 Counts in the Three Targeted Watersheds Note. The results demonstrate a weak correlation betweenE. coli levels and GenBac3 counts for any of the sampling sites. 1.0 1.5 2.0 2.5 1.0 3.0 4.0 2.0 2.5 3.0 3.5 4.0 2.0 2.5 3.0 2.0 2.0 2.5 3.0 3.5 2.5 3.0 2.0 1.5 A. Lower Farm River, Branford B. Goodwives River, Darien C. Sasco Brook, Westport Log10 GenBac3 (Markers/100 ml) Log10 GenBac3 (Markers/100 ml) Log10 GenBac3 (Markers/100 ml) Log10 E. coli (CFU/100 ml) Log10 E. coli (CFU/100 ml) Log10 E. coli (CFU/100 ml) FIGURE 2