The study looked at using micropollutants to track wastewater in treatment plants and groundwater. Nine micropollutants were found to be good indicators of treated wastewater. These indicators were classified as stable, labile, or uncertain based on how well they were removed in the treatment plants. By comparing labile to stable indicators, the researchers could see how well different treatment ponds were working and detect seasonal changes in efficiency. They also found evidence of untreated wastewater reaching groundwater, even when treated wastewater was being reused.