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Relationships and trends of E. Coli, human-associated bacteroides, and pathogens in the Proctor Creek watershed (GWRC 2017)
Citation:
Snyder, B., M. Molina, AND O. Georgacopoulos. Relationships and trends of E. Coli, human-associated bacteroides, and pathogens in the Proctor Creek watershed (GWRC 2017). In Proceedings, Georgia Water Resources Conference, Athens, GA, April 19 - 20, 2017. Georgia Institute of Technology, Atlanta, GA, 1-7, (2017).
Impact/Purpose:
Fecal indicator bacteria (FIB) such as E. coli are used as an indicator for fecal contamination in freshwater ecosystems. These organisms are ideal fecal indicators as they live in the gastrointestinal tract of warm blooded animals. The results presented here indicate that the Proctor Creek watershed is highly impacted by human-associated Bacteroides. Major and consistent sources of human fecal contamination are common throughout the watershed, particularly in the upper reaches of the watershed. The tributary site at Greensferry was a constant source of HF183MGB that was impacting downstream mainstem locations. This suggests that illicit sewage connections or failing infrastructure are present in the headwaters of the watershed.
Description:
Urban surface waters can be impacted by anthropogenic sources such as impervious surfaces, sani-tary and storm sewers, and failing infrastructure. Fecal indicator bacteria (FIB) and microbial source tracking (MST) markers are common gauges of stream water qual-ity, however, little is known about their relationship with public health. In this study, we measured culturable and molecular concentrations of E. coli, a human-associated Bacteroides marker (HF183MGB), and selected water-borne pathogens and toxins (Salmonella sp. and Shiga-toxin (Stx2)) in surface water throughout a highly urban-ized watershed near downtown Atlanta, GA to determine if any relationships exist between these parameters. The Proctor Creek watershed, a tributary to the Chattahoochee River, consistently fails fecal coliform standards and is therefore, listed on the Environmental Protection Agen-cy’s (EPA) 303(d) impaired waters list. Water grab sam-ples were taken at 12 locations throughout the watershed every two weeks for one year. Culturable E. coli concen-trations varied greatly throughout the watershed (24 to 101,330 MPN/100 mL). The human associated marker was widespread throughout the watershed and correlated highly with molecular E. coli (R2 = 0.63). Salmonella was present at all mainstem and half of the tributary sites, whereas Stx-2 was widespread throughout the entire wa-tershed but was most frequently found at headwater loca-tions where storm water inlets and outfalls were more prevalent. Based on their high correlation, E. coli could be a useful parameter in predicting human-associated Bacteroides in this watershed. Our results also indicate that major and consistent human sources of fecal contam-ination are present throughout the watershed suggesting that sanitary sewer leaks could be widespread across the region.
