Effects of tropical depressions Ivan and Jeanne on water quality of the Upper Oconee River basin: results from a watershed group monitoring program
Ruhlman, Melanie B.
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We measured storm water quality at 10 long-term monitoring sites in the Middle and North Oconee River basins near peak flow during Tropical Depressions (TD) Ivan and Jeanne and compared our results to the Upper Oconee Watershed Network low flow dataset. Maximum turbidity levels for the North Oconee River were 5-10 times lower than those in the Middle Oconee River (474 - 834 NTUs) during both storms. We found the lowest turbidity levels in small streams with vegetated buffers and an urban stream. Most of the fine particulate material transported in the 10 streams at low flow and peak flow during TD Jeanne was in the form of inorganic sediment. An estimated 4,039 kg of sediment moved downstream every minute in the Middle Oconee River just prior to peak flow during TD Ivan, while sediment in the North Oconee River was transported downstream at a rate of 88 kg/min. Fecal coliform bacteria concentrations were also greater during peak storm flow (<500 - 11,800 CFU/100 mL), while nitrate, pH, and conductivity values did not differ greatly from low flow conditions. Our results demonstrate the negative effects of high flows on sediment transport and fecal coliform concentrations in the upper Oconee River basin, particularly in the Middle Oconee River watershed.