Epidemiological studies have shown direct relationship between acute gastrointestinal illness (AGI) and fecal indicator bacteria (FIB), Escherichia coli in freshwater and Enterococci in marine water. On the other hand, there is no consensus method for selection of the appropriate FIB for brackish water beaches, leaving the selection to the state level environmental protection agencies. In Georgia, Enterococci have been used as FIB for all beaches regardless of whether it is freshwater or marine environment.

Kings Ferry Beach, a popular site for recreational activities, is located along the Ogeechee River and in Georgia. Department of Natural Resources has issued a permanent advisory at this beach due to persistently high numbers of Enterococci. In this study, we tested the freshwater indicator (E. coli) against Enterococci to determine whether E. coli would be an alternative FIB in these tidal waters considering that they show more freshwater characteristics than a marine environment. Fourteen sampling points around Kings Ferry Beach were tested monthly for bacterial contamination. E. coli and Enterococci were enumerated using USEPA methods 1603 and 1600 respectively. In situ environmental data including salinity were also collected. Statistical analysis was performed using IBM SPSS version 21.

The first four months of data showed that the salinity of the river ranged from 0.038 to 7.56 psu, showing freshwater/brackish water characteristics. Among 59 samples tested, 5% exceeded the USEPA criteria for E. coli (300 CFU/100mL). On the other hand, 50% of these samples exceeded the USEPA Enterococci criteria (60 CFU/100mL). Therefore, our results showed that using Enterococci as indicator for pollution in brackish water systems provides a more conservative approach for better prevention of potential health outcomes upon exposure to these waters.