NONPOINT AND POINT-SOURCE DISCHARGES INFLUENCE NUTRIENT CONCENTRATIONS IN NORTHEASTERN GEORGIA

By Lisa K. Ham

ABSTRACT

Nonpoint and point-source discharges increase nutrient concentrations in the Altamaha and Ogeechee River basins. The Altamaha River, draining 14,200 mi2, has two major tributaries---the Ocmulgee River, draining 5,260 mi2 and the Oconee River, draining 5,320 mi2. Higher nutrient concentrations were found in the Ocmulgee River than in the Oconee River; point-source discharges on the Ocmulgee River are four times greater than on the Oconee River. Throughout both tributaries, increases in ammonia concentrations correspond to wastewater discharges found upstream and increases in total-phosphorus concentrations correspond to phosphorus inputs from nonpoint sources. Along the Ogeechee River point-source discharges are minimal, but nitrate and total-phosphorus concentrations increase due to nonpoint sources. The major tributary of the Ogeechee River, draining 4,410 mi2, is the Canoochee River, draining 1,420 mi2. In the Canoochee River, nonpoint and point-source discharges result in increases in nutrient concentrations. Throughout the Altamaha and Ogeechee River basin, sediment uptake of total phosphorus appears to be resulting in decreases in total-phosphorus concentrations.

Trend analysis for sites within the Altamaha and Ogeechee River basins resulted in four increasing nitrate trends, three increasing ammonia trends, and three increasing total phosphorus trends. At these sites, median nutrient concentrations were below U.S. Environmental Protection Agency guidelines.


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