Real-Time Quantitative PCR Measurements of Fecal Indicator Bacteria and Human-Associated Source Tracking Markers in a Texas River following Hurricane Harvey

Hurricane Harvey has caused unprecedented devastation to huge parts of southeastern Texas, particularly damaging the wastewater infrastructure resulting in release of sewage contamination into environmental waters. The purpose of this study was to conduct a preliminary assessment of fecal indicator bacteria (Escherichia coli and enterococci) and human-associated fecal genetic markers (human-associated Bacteroidales), measured using qPCR assays, across a Texas river impacted by Hurricane Harvey. Water samples were collected along the Guadalupe River during September-December 2017. The most heavily flooded sites showed the highest abundance of fecal indicator bacteria and human-associated Bacteroidales markers, indicating that a large number of sewage overflows and stormwater runoff occurred during Harvey flooding. These findings suggest that high levels of human fecal contamination were introduced into waterways draining into the Gulf of Mexico and impaired surface water quality. The human-associated Bacteroidales markers exhibited a low to slightly strong correlation with conventional fecal indicators, suggesting the variable occurrence of different markers and uncertainty of enterococci and E. coli for detection of human fecal pollution. In general, results of this initial microbiological contaminant assessment will serve as baseline information for follow-on studies to monitor existing and emerging public health risks to residents of Texas and potential long-term environmental impacts on the water resources in the impacted regions.