To monitor pollution of marine beaches in Georgia, enterococci have been used as indicators of fecal contamination. For the 1986 Recreational Water Quality Criteria (RWQC), the beach action value (BAV) was 104 colony forming units (CFU)/100 ml; the new RWQC, instituted in 2012, is 70 CFU/mL, a 32.6% decrease. When the beach action value is reached, authorities are to issue a beach advisory for protection of swimmer health. The present study investigated changes in compliance with the 2012 RWQC at five high-use beaches in Georgia.
[Photo: Dr. Asli Aslan]
In the summer of 2015, samples of water were collected from five beaches at Tybee Island. Enterococci concentrations were enumerated by USEPA-approved methods. Samples exceeding the 1986 and 2012 RWQC beach action values were compared with times that advisories were posted at these beaches.
At these beaches, advisories were posted four times during the summer. Since, in 2015, the previous RWQC was in use, these decisions were based on the guideline value of 104 colony-forming units (CFU)/100 ml. When the new beach action value (70 CFU/100 ml) was applied, retrospectively, for samples collected at these sites, researchers found that the number of advisories would have been doubled if this value had been in place at that time.
One other issue that is often overlooked in water quality monitoring is the day of the sampling that is most representative for human exposure. In this study, researchers showed only short term advisories were in agreement with routine week-day monitoring results. When the advisories were longer than 3 days, the weekend concentrations of bacteria were not always in agreement with the weekday results.
Staring from January 2016, Georgia has adopted new water quality criteria to monitor beaches. Decreasing the beach action value to 70 CFU/100 ml strengthens beach monitoring programs because it allows for better prevention from waterborne diseases, thus protecting the health of swimmers.
“New recreational water quality criteria and their impact on beach advisories in Coastal Georgia,” was published in The Journal of the Georgia Public Health Association.
Dr. Asli Aslan, Assistant Professor of Environmental Health Services at the Jiann-Ping Hsu College of Public Health at Georgia Southern University was the lead author and recent alum, Dr. Sara Benevente was the co-author of this study.