PRJNA505497
Patterns of fecal contamination in urban street water delivered to an coastal embayment
Stormwater from the urban environment has been identified as an important source of pollution to coastal waterways. While the types of pollutants (e.g., metals, organics) can be quite diverse, there is an increasing appreciation of urban stormwater as a source of fecal microbes relevant to coastal water quality monitoring. In this study, street water samples from Queens, New York were found to consistently contain high levels of enterococci, a group of fecal indicator bacteria (FIB), via cultivation-based approaches. These concentrations were orders of magnitude above the EPA recommended Beach Action Value and significantly higher than the concentration observed in receiving waterways, demonstrating stormwater as a potentially significant source of indicators relevant to waterway management and monitoring programs. The fecal indicators were also found to persist in a viable form on the street surface during periods of extended dry weather. 16S rRNA gene sequencing of bacterial isolates confirmed the identity of the cultivated FIB to be Enterococcus spp. The presence of taxa from the genus Enterococcus was also confirmed in both street water and Combined Sewer Overflow (CSO) samples by high-throughput amplicon DNA sequencing. CSO samples were found to have significantly greater representation of taxa that have been associated with human fecal contamination than street water samples. The percent sequence representation of Enterococcus and broader groups of fecal taxa were correlated in CSO samples but not in street water samples, and also suggested an overrepresentation of FIB relative to other fecal taxa in street water samples. The results of this study confirm that fecal indicators are abundant in urban stormwater but appear to be decoupled from broader fecal taxa creating complexity in the interpretation of FIB monitoring data influenced by stormwater versus sanitary sewer waste.