Fig 1.
A map of Town Creek Estuary in Beaufort, NC, with the sampling sites denoted with a black star icon.
Lift stations and nearby sewer infrastructure are denoted by a red circle icon; stormwater outfalls are denoted by a yellow square icon; marsh is denoted by a green triangle icon; septic systems are denoted by a blue circle icon; and areas downstream from possible major sources of contamination are denoted by a purple trapezoid icon.
Table 1.
Sampling site locations in Town Creek Estuary and associated potential sources of contamination.
Table 2.
Average environmental conditions observed on each sampling date.
Table 3.
Primers and probes for the HF183 assay [32].
Fig 2.
Correlation plot of Spearman rank correlations between environmental, water quality, and molecular parameters.
Significant (p < 0.05) correlations are shown on the upper portion of the plot as red dots (negative correlations) or blue dots (positive correlations) with the correlation strength represented by the shade of the dot. The size of the dot indicates the significance level with larger dots representing a higher probability that the identified correlation is real. The lower portion of the plot shows the spearman rank correlation values. TC = total coliforms, EC = Escherichia coli, ENT = Enterococcus.
Table 4.
Mean values of vitrified clay (VC) pipe and pipes aged over 50 years in a 400-meter radius of each site; mean concentrations of Escherichia coli (EC), Enterococcus (ENT), HF183, and distance to the nearest stormwater pipe within a 400-meter radius of each site.
Ranks were assigned using two models, equal weighting of each parameter or variable weighting with a higher weight assigned to parameters of measured fecal contamination. A rank of 1 indicates the highest potential source location of fecal contamination and priority for infrastructure review and repair to 10 with the lowest potential source risk. Bold values indicate equivalent ranks using both models.
Fig 3.
Correlation plot of Spearman rank correlations between molecular and infrastructure parameters.
Significant (p < 0.05) correlations are shown on the upper plot as red dots (negative correlations) or blue dots (positive correlations) with the correlation strength represented by the shade of the dot. The size of the dot indicates the significance level with larger dots representing a higher probability that the identified correlation is real. The lower portion of the plot shows the spearman rank correlation values. TC = total coliforms, EC = Escherichia coli, ENT = Enterococcus, VC = vitrified clay, PVC = polyvinyl chloride, DIP = ductile iron pipe, CIPP = cured in place pipe, Age > 50 = percentage of pipe at each site greater than 50 years of age, Age <50 = percentage of pipe at each site less than 50 years of age.
Fig 4.
(A) Mean concentrations of Escherichia coli (EC) (MPN/100 mL), (B) Enterococcus spp. (ENT) (MPN/100 mL), (C) human host-specific marker HF183 (copies/100 mL), (D) percent of pipe aged over 50 years (Over50), (E) percentage of pipes constructed using vitrified clay (VC), and (F) the inverse of the nearest distance (m) to stormwater outflow pipes at each site presented as a stacked bar graph of the sum total at each site.