Linking Septic System Pollution Potential to Water Quality: A Baseflow Sampling Approach

Abstract

Reliable wastewater sanitation infrastructure is essential for protecting public health and the environment. Decentralized wastewater treatment systems such as septic systems are susceptible to failure and may be a nonpoint source of pollution in groundwater and surface water. Researchers have used geospatial modeling to identify areas at risk of septic system failure. However, these studies rarely incorporate ground-truth sampling to validate modeling efforts. Here, an innovative sampling approach was used to collect surficial groundwater samples from streambeds in coastal Mississippi and Alabama. Classification and regression trees were used to evaluate the effectiveness of a pollution potential model in predicting concentrations of wastewater tracers identified in these samples. Results support pollution potential modeling as an effective predictor of a human-specific wastewater tracer, though individual septic system points performed better when used in the alternate model scenario. This study identified wastewater tracers throughout the study area and has implications for future sampling approaches and environmental risk assessment.