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Quantitative Microbial Source Tracking and Coliphage Monitoring in Small Stream Tributaries (Banklick Watershed Council)
Citation:
McMinn, B., A. Korajkic, J. Kelleher, A. Diedrich, A. Pemberton, J. Willis, M. Sivaganesan, B. Shireman, A. Doyle, AND O. Shanks. Quantitative Microbial Source Tracking and Coliphage Monitoring in Small Stream Tributaries (Banklick Watershed Council). Banklick Watershed Council, Fort Wright, KY, June 05, 2024.
Impact/Purpose:
The Banklick Creek in northern Kentucky is a 303.d listed impaired waterway. Sanitation District No. 1 (SD1) is interested in identifying sources of pollution within the Banklick Creek watershed to improve water quality within the Banklick Creek. Unfortunately, SD1 has been unable to identify sources of fecal contamination entering the Banklick Creek which makes targeted remediation difficult. To assist SD1 in identifying sources of fecal contamination entering Banklick Creek, our team devised experimentation to identify sources of fecal contamination in three tributary catchments having different land use characteristics. By applying both culture-based and molecular source tracking markers, we identified key sources of fecal contamination in each catchment. This information can now be used by SD1 to implement targeted remediation to improve water quality within the Banklick Creek watershed.
Description:
Stream tributaries can be impacted by a myriad of fecal pollution sources that contribute to water quality impairment in receiving waters. Strategic water quality monitoring of tributaries can enhance the ability to identify fecal pollution sources to better protect human health. Water quality is assessed using fecal indicator bacteria (FIB); however, FIB cannot differentiate sources of fecal contamination nor the presence of disease-causing viruses. For this study, three stream tributary catchments within the Banklick Creek watershed (Fort Wright, Kentucky U.S.A.) were selected for water quality testing based on geographic information system (GIS) land use information, with careful attention to factors that could influence the source and amount of fecal contamination present in each catchment. To identify sources of contamination, host-associated genetic targets HF183/BacR287 (human), Rum2Bac (ruminant), GFD (avian), and DG3 (canine) were analyzed with FIB (E. coli and enterococci), viral indicators (somatic and F+ coliphage), six general water quality parameters, and local rainfall data. Based on an E. coli single sample maximum (235 CFU/100 mL), 70.7% (29 of 41) of samples indicated impairment. Somatic coliphage significantly correlated with FIB paired measurements (P ≤ 0.0002, R2 ≥ 0.551), but F+ coliphage was not prevalent enough for statistical comparison (detected in 37% of samples). The ruminant host-associated genetic marker was detected most frequently (46.3%) followed by human (43.9%) and avian (41.5%), and dog (7.3%). A Bayesian censored data analysis approach was applied to investigate potential quantitative links between host-associated genetic marker occurrence with that of rainfall and fecal indicator levels. Findings indicate that bacterial and viral indicator occurrence varies depending on the presence of human or non-human fecal pollution sources. In addition, results confirm that human and non-human sources both contribute to poor water quality in Banklick Creek watershed and emphasize the important role of rainfall in tributary systems.