THE EFFECT RAINFALL HAS ON THE WATER QUALITY OF THE LITTLE TALLAPOOSA RIVER AND A HEAVILY IMPACTED TRIBUTARY

The Little Tallapoosa River watershed is located in the Piedmont province of west Georgia. The Little Tallapoosa River forms the northern boundary of the campus of the State University of West Georgia. The watershed is forested and contains pastures, hayfields, areas of residential development, and small urban centers. The watershed is in the late stage of youthful erosion with weathered slopes. Thunderstorms along with 50 inches of annual precipitation lead to runoff with large amounts of sediments. Continual development of residential areas, clear cutting of trees, runoff from agricultural land, and road construction pose a continued threat to the watershed. There are three principal sites monitored on campus which include Central Campus Branch, the Little Tallapoosa River, and a free flowing artesian well. Central Campus Branch is a tributary of the Little Tallapoosa River that drains the central part of the campus and is affected by runoff from parking lots, streets, buildings, fertilized activity fields and lawns. Field measurements during 2004 were taken before and after rain events. The sampling was done at 12-hour intervals. The parameters tested in the field include pH, specific conductivity, turbidity, dissolved oxygen, and air and water temperatures. Dissolved oxygen and turbidity increase after rainfall events while specific conductivity and pH decline. A large rain event of 1.71 inches produced a 20-fold decrease in specific conductivity for Central Campus Branch and a turbidity of 880 NTU. The lowest recorded Central Campus Branch turbidity value of 0.60 NTU occurred during a dry period. The highest recorded turbidity value on the Little Tallapoosa River was 80 NTU, which was recorded 96 hours after a 0.56 inch rainfall event. The lowest recorded turbidity value of 6.8 NTU occurred during a dry period. Flooding prevented sampling the river after major rainfall events. Twelve-hour sampling intervals during and after rain events provides more comprehensive data. With no construction and grass established fields in central campus watershed another source of sediment is required to account for turbidity ~900 NTU. Erosion of bank sediment in the headwaters during intense channel flow coupled with overland flow are possible sources of sediment.