Applying a community-based monitoring framework to enteric bacteria monitoring and microbial source tracking

Abstract

Using microbial source tracking (MST) to find possible causes of fecal contamination in freshwater systems via quantitative polymerase chain reaction (qPCR) is a robust field with ever increasing application. Rural lakes have been less studied using this technique but there is high potential for impact in these communities where fecal contamination has rarely been investigated. Using a community-based monitoring approach, we supported five lake associations in the northern region of the lower peninsula of Michigan as they sought to understand fecal contamination levels in both a freshwater stream system and five freshwater lakes. Working together to formulate questions, we aimed to gain understanding about the dynamics between septic systems, stormwater runoff and enteric bacteria levels, including using MST for human fecal contamination. We found a high prevalence of human fecal contamination in three study lakes with a high density of septic systems and one stream system, which was partially due to rain events. We also found a positive trend between high usage of septic systems and appearance of enteric bacteria in corresponding well water samples. This information adds to previous knowledge about the correlation between human MST markers and density and abundance of septic systems and could help make wastewater management decisions for these areas and the state of Michigan in the future.