Evidence for the Accumulation and Steady-State Persistence of E. coli in Subtropical Drainage Basin Sediments

While the presence of fecal indicator bacteria such as Escherichia coli in urban stormwater has been widely documented, their occurrence and persistence in sediments are not as well understood. Recent investigations suggest that E. coli can accumulate in drainage basin sediments and act as a fecal bacterial reservoir within a watershed. We investigate the prevalence of E. coli populations in a tidal creek stormwater catchment and examine their interaction with overlying stormwater under wet and dry weather conditions. Two rain events are sampled more intensively with samples collected prior to, during, and after rainfall to profile bacteria in each matrix throughout a storm. Results of profile sampling and estimates of sediment resuspension provide evidence for E. coli accumulation during dry conditions and entrainment in overlying waters during storm conditions. Profile results suggest the occurrence of steady-state E. coli populations in drainage basin sediments.