Spatial and temporal characterization of Escherichia Coli, suspended particulate matter, physiochemical and land use practice relationships in a contemporary mixed-land use watershed

Understanding land use practice and physiochemical influences on Escherichia (E.) coli concentrations is necessary to improve water quality management and human health. Additionally, elucidating the usefulness of suspended particulate matter as a proxy for fecal contamination may aid in quantifying microbial water quality in cases where direct testing is not feasible. Weekly stream water samples and physiochemical data were collected from 22 stream gauging sites with varying land use practices in a representative contemporary mixed-land use Appalachian watershed of the eastern USA. Over the period of one annual year, E. coli colony forming units (CFU per 100mL) were compared to suspended particulate matter (SPM) concentrations (mg/L), physicochemical parameters and land use practices. Study results highlight the legacy impacts of historic mining (acid mine drainage) on E. coli concentrations, as 77% of sample sites displayed significant correlation (p < 0.05) between pH and E. coli concentrations. Agricultural land use showed statistically significant relationships (p = 0.00) between annual E. coli and SPM concentration data. Additionally, sub-catchments comprising mixed development land cover of approximately 25%-30% showed negative correlations (p<0.05) between to E. coli and chloride concentrations. The study is the first to incorporate a high spatial and temporal resolution sampling over a full annual year, thereby enabling greatly needed validation of previous studies and advancing understanding of factors influencing fecal contamination in receiving waters.