Precipitation, Pathogens, and Turbidity Trends in the Little River, Tennessee

Abstract

The Little River is on the state of Tennessee's Year 2004 list of impaired waters, and has existing total maximum daily loads for sediment and E. coli bacteria. In this study, we investigate how precipitation, discharge, sediment, and pathogens are related in the Little River. Our goals are to: (1) determine the degree of correlation between precipitation, turbidity, stream discharge, and pathogen (total coliform and E. coli) concentrations; (2) identify and describe seasonal patterns that may exist for both pathogens and turbidity: and (3) develop a simple statistical model that predicts pathogen concentration from rainfall, stream discharge, and turbidity measurements. Spearman's correlation results show that discharge is most highly correlated to seven-day antecedent precipitation, and that turbidity and pathogen concentration are most highly correlated with the previous day's precipitation. In addition, total coliform concentrations are significantly (p = 0.01) higher in summer than in other seasons, but we were unable to show significant seasonal differences in E. coli concentrations. We propose a simple regression model (R ² = 0.57) for E. coli using readily available and easily measurable parameters such as precipitation, discharge, and turbidity.

Keywords:

• Tennessee
• stream discharge
• water quality
• model