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Identification of Factors Affecting Fecal Pollution in Beaver Lake Reservoir

Gibson, Kristen E., Lee, Jung Ae, Jackson, Jay M., Smith, Lauren N., Almeida, Giselle
Journal of environmental quality 2017 v.46 no.5 pp. 1048-1056
Escherichia coli, base flow, cattle, host specificity, lakes, most probable number technique, odds ratio, pollution, poultry, public health, quantitative polymerase chain reaction, rain, risk, rivers, spring, streams, water quality, watersheds, United States
Standard methods for the evaluation of recreational water quality rely on generic bacterial indicators such as Escherichia coli. However, E. coli does not provide enough information to determine fecal source or public health risk. The stsudy objective was to determine factors influencing the presence of E. coli and host-specific markers (HSM) from upstream to downstream in Beaver Lake Reservoir (BLR). From February 2014 to September 2015, 420 base flow and rain event samples were collected from seven sites—two sites from streams (White River [WR] and War Eagle Creek) draining into BLR and five sites from within BLR. Each sample was analyzed for E. coli and by quantitative polymerase chain reaction for HSM related to human, bovine, and poultry. The data indicate that overall levels of E. coli were significantly greater in the WR and significantly lower at the most downstream sampling location in BLR. Escherichia coli is more likely present during spring (adjusted odds ratio [aOR] = 1.86), at the WR sampling site (aOR = 3.39), or during a rain event (aOR = 2.73). Moreover, the HSM HumM2 is more likely present (aOR = 1.99) when E. coli is present. These same factors were associated with E. coli concentrations >126 most probable number 100 mL⁻¹ (aOR = 2.76–12.48), except the poultry marker CL was more likely associated (aOR = 3.81) than HumM2. This study revealed that both seasonal and locational factors are important variables for fecal pollution in BLR. Moreover, these same factors may apply to fecal pollution in manmade reservoirs within similar types of watersheds across the United States, as well as internationally.