The relationship of land use practices to surface water quality in the Upper Oconee Watershed of Georgia

On a watershed scale, geospatial information can be used to-identify water resources that are least buffered from contamination. Implementing conserva tion practices at these locations may accelerate the process of increasing a watershed's ability to support its designated uses. The Upper Oconee Wate rshed of Georgia contains land areas devoted to poultry, dairy, and beef pr oduction. Within these historically agricultural lands, urbanization is pro ceeding rapidly around existing cities. Agricultural production practices a re concentrated in the watershed with poultry in the headwaters area and da iry near a major lake (Lake Oconee). The objective of this research was to relate data sets representing surface water quality at selected sites throu ghout the watershed to the predominant land use in that portion of the wate rshed. The location of 550 poultry operations in the headwaters of the Uppe r Oconee Watershed, away from the city of Athens GA, has minimized conflict s between agricultural and urban interests. Phosphorus, nitrogen, and fecal coliform bacteria were high near the poultry production area, but were red uced within the watershed prior to reaching the intake for the municipal wa ter supply. Athens had a large impact on surface water quality and approxim ately doubled the amount of phosphorus and nitrogen in the Oconee River. Th e Oconee River contributed approximately 70% of the water flowing to Lake O conee. The residents of Lake Oconee have noted the 30 dairies located west of the lake impacting two relatively minor creeks flowing to the lake. Thes e two creeks make up approximately 2.5% of the flow to the lake, but the pr oximity of the dairies:to the lake makes losses of phosphorus, nitrogen, an d fecal bacteria apparent in water samples. Fecal coliform numbers were ele vated in some creeks with little agricultural or urban development. To test alternative microbial assays, surface water from a grazed watershed was co mpared to water from a wooded watershed. Assays for enterococci and E. coli may provide a better test: for fecal contamination and allow differentiati on between natural areas and areas impacted by grazing animals. Analysis of the Upper Oconee Watershed identified agricultural impacts and areas that should be priorities for natural resource management to reduce agricultural nonpoint sourer pollution. Focusing conservation efforts at these location s may prevent agricultural-urban conflict. However, the data also indicate that municipal sources of nutrients and fecal bacteria must be reduced to m ake significant progress in the watershed. (C) 2000 Elsevier Science B.V. A ll rights reserved.