Microbial Contamination of Surface Water and Groundwater in Flood-Impacted Rural Communities in South Texas Following Hurricane Hanna

Abstract

Hurricane Hanna brought unprecedented rainfall and flooding to Texas in 2020. Our study evaluated microbial contamination in surface water (SW) and groundwater (GW) across rural communities in Rio Grande Valley (RGV) and Baffin Bay using both culture-based and qPCR methods. Sampling began immediately after the landfall of Hurricane Hanna (August 2020) and until the end of the summer monsoon (August 2021). High concentrations of culturable Escherichia coli and total coliforms were detected during summer monsoon for both surface and GW. E. coli and enterococci were present in all SW samples in RGV. Enterococci was detected in all SW samples collected from BB; however, E. coli was detected in 81% of samples. Like SW, concentration of E. coli and enterococci markers in GW samples were high in RGV. The human-associated fecal marker (HF183) was detected in both SW and GW but mainly in RGV during the dry period. HF183 exhibited a low to moderate correlation with conventional fecal indicators, suggesting the uncertainty of enterococci and E. coli for detection of human fecal pollution. In general, the outcomes of this study serve as foundational data for subsequent investigations aimed at overseeing both established and evolving public health concerns for Texas residents.