Physical, Chemical, and Microbial Quality of Floodwaters in Houston Following Hurricane Harvey

Hurricane Harvey brought more than 50 in. of rainfall to some areas of the Greater Houston Metro area (GHMA) starting on August 25, 2017; the Hurricane was also associated with damage to environmental infrastructure such as wastewater facilities, superfund sites, and leaks and spills from industrial and municipal facilities. This study collected post-Harvey water quality data in multiple streams for several weeks after the Hurricane. In addition to measuring impact, the study compared the observed concentrations of several physical, chemical, and microbial constituents and water properties to their historical counterparts in an effort to understand the water quality impacts of Harvey on the natural water systems within the GHMA. Unusual water quality findings such as low pH were observed that likely had acute and chronic effects on ecosystems including the loss of oyster populations in Galveston Bay. In-stream microbial concentrations, using E. coli as the indicator, were within historical norms typically reported for the GHMA. The observed levels of measured dissolved metals post Harvey, while relatively low, when multiplied by the significant volume of water discharged from bayous to Galveston Bay, meant the delivery of a substantial load of trace metals to the estuary. Specifically, the load in the particulate phase would be expected to accumulate and gradually repartition to the dissolved phase for a long period of time. Total metal concentrations, when elevated relative to their historical counterparts, could be associated with the presence of industrial activities. Overall, anthropogenic activities including the presence of hydraulic flood control structures, local runoff from industrialized areas, and active superfund sites were recognized as key factors affecting short-term acute water quality impacts. Watersheds with very little human alterations experienced minimal water quality changes and had relatively rapid recoveries post-Harvey.