ENVIRONMENTAL ASSESSMENT OF THE CHATTAHOOCHEE RIVER IN WEST GEORGIA: RELATIONSHIPS BETWEEN FLOW AND SEDIMENT AND BACTERIA

The Chattahoochee River has the smallest drainage basin of any river providing a majority of the water to a metropolitan area in the US, yet it supplies more than 70% of the drinking water to the metro-Atlanta area. In addition to continued development and construction, 200 municipalities and businesses discharge >250 million gallons of sewage and pollutants into the river daily, landing the Chattahoochee on the Most Endangered Rivers list 7 times since 1986, according to American Rivers. We examined the correlation between flow, rain, turbidity, total suspended solids (TSS), fecal coliform bacteria, and E. coli bacteria to determine the effect storm events have on water quality and to show the relationship between turbidity and indicator bacteria levels.

Our sample site is located in Carroll County, Georgia, ~40 miles downstream of Atlanta. Turbidity samples were collected 5 days a week (min=2.8 NTU, med=8.85 NTU, max=190 NTU), while other parameters were collected 2-3 times per week, including TSS (min=1.2mg/L, med=8.80 mg/L, max=280.0 mg/L), fecal coliform (min=9 colonies/100 ml, med=110 col/100 ml, max=4900 col/100 ml), and E. coli (min=20 colonies/100 ml, med=80 col/100 ml, max=4000 col/100 ml). E. coli measurements have only been collected recently and more data is necessary to better understand its relationship with turbidity. Correlation between turbidity and other parameters varies from r2=0.85 with TSS, to r2=0.68 with stream flow, and to r2=0.30 with fecal coliform. Thus, turbidity may possibly be used as a proxy to roughly determine TSS, stream flow, and fecal coliform bacteria levels. During storm events, turbidity measurements were collected 2-3 times daily and compared with discharge measurements obtained from the United States Geological Survey. One particular storm event shows a correlation between turbidity and stream flow of r2=0.85. This shows how closely storms and the effects of increased stream flow are related to water quality. This research also focuses on an attempt to determine the sediment load carried by the Chattahoochee River to West Point Lake, a reservoir located downstream of our study site. Using historical sediment and flow data collected by the USGS at monitoring stations along the river, plus sediment data collected in this study, a rough estimate of sediment load was calculated.