Influence of Physiographic Region on Pathogen Concentrations Between Stream Types

Predicting public health risk associated with exposure to and recreational use of surface waters is often challenging due to substantial variability in concentrations of pathogenic bacteria, even among seemingly similar streams. In this study, we document significant differences in the surface water concentrations of the common bacteria indicators Escherichia coli and fecal coliform between two major stream types—blackwater and redwater streams (p < 0.001). We propose and present evidence that these findings result from natural biogeochemical variation between physiographic regions (p < 0.001). These findings suggest that physiographic stream type may influence the degree of exposure to waterborne pathogens and risk of waterborne disease. Future research is needed to assess whether the inclusion of stream type in risk assessments can improve public health modeling and mapping.