Effect of Human Recreation on Escherichia Coli Levels in the Chattahoochee River in Helen, GA
Dalman, Nancy Eufemia
Pschandl, Carolyn M.
Van Cleave, Renee M.
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The economy of Helen, GA relies heavily on tourism and recreation in the Chattahoochee River. Tubing the river is a particularly popular activity, with several thousand people in the water each week from June - September. Sampling during the summer of 2003 by the Georgia Mountains Regional Development Center (GMRDC) reported high levels of the fecal indicator bacterium Escherichia coli in the Chattahoochee River near Helen. The present study focused on determining whether sediment disturbance by humans increases bacterial load in the water column, thus amplifying exposure risk for people engaging in recreational activities. Sediment acts as a reservoir for E. coli and disturbance of sediment may lead to sudden and significant increases in E. coli concentrations. In this study, water samples were collected once or twice per week from June through September, in the morning (before the tubing period began) and evening (after tubing ended) of the same day. Samples were collected at control sites upstream of the tubing region and at experimental sites spanning the stretch of river through Helen where the majority of tubing activity occurs. Samples were prepared for total coliform and E. coli quantification using the Colilert® Quanti-tray® 2000 system (IDEXX) and incubated for 24 hours at 35.5°C. Mean E. coli levels at control sites were 47.5 MPN/100 ml for AM sampling and 38.8 MPN/100 ml for PM sampling. E. coli levels at test sites were 230.2 MPN/100 ml for AM sampling and 259.9 MPN/100 ml for PM sampling, with over half of the test site readings being greater than the USEPA proposed standard of 235 MPN/100ml. E. coli levels were significantly greater at test sites compared to control sites. However, E. coli levels did not differ significantly between morning and evening collections, suggesting that human activity in the water had little impact on the levels of E. coli either through addition of bacteria directly to the water column or through the disruption of sediment bacteria stores.