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Long term water-quality trends in North Carolina Rivers

Conference Proceedings
By Douglas A. Harned

Abstract

Interpretation of water quality data collected by the U.S. Geological Survey for the French Broad, Neuse, and Yadkin-Pee Dee Rivers in North Carolina has provided 2O-year trends in concentrations of major dissolved constituents, and also estimates of the degree of pollution caused by man for each river. The amount of dissolved inorganic pollution in each river was determined by subtracting estimates of natural loads of dissolved constituents, determined from base-line stations, from measured total loads, Presently, man-made pollutants make up approximately 60 percent of the dissolved material transported by the French Broad River, 50 percent by the Neuse River, and 50 percent by the Yadkin-Pee Dee River. Two data-transformation methods enable trends to be identified in some dissolved constituent concentrations. Both methods permit the concentrations to be calculated as if they were determined at a constant discharge over the period of record. Although little change has occurred since 1956 for most constituents, identifiable changes in certain constituents, such as increases in potassium and sulfate, indicate that the water quality of the Neuse and Yadkin Pee-Dee Rivers has deteriorated. Increases in sulfate are probably due to increased inputs of sulfur compounds from air pollution. Water-quality improvement in the French Broad River is due to reductions of point-source pollution.

Harned, D.A., 1980, Long term water-quality trends in North Carolina Rivers: [abs] Sixteenth American Water Resources Association Conf., Minneapolis Minnesota, October 12-16.