Water quality of the French Broad River, North Carolina — An analysis of data collected at Marshall, 1958-1977
An investigation of water quality in the French Broad River in North Carolina has resulted in the definition of variations in water quality, a determination of the degree to which the quality of water in the river has been affected by man 's activities, and an analysis of trends in the changing chemical quality of the river. The investigation centered on data collected during 1958-77 at the U.S. Geological Survey 's station at Marshall, N.C. The quality of water in the French Broad River at Marshall is suitable for most uses. None of the major dissolved constituents and nutrients, nor defined properties such as hardness, alkalinity and color, exceed suggested limits for drinking waters. Chromium, lead, selenium, and zinc are the only trace metals to occasionally exceed drinking water standards. Dissolved oxygen levels are high year round, remaining near or above the saturation level even at higher summer temperatures. Results of tests for biological oxygen demand and chemical oxygen demand characterize the French Broad at Marshall as a clean river. However, 58% of samples analyzed for fecal coliform bacteria during 1974-77 exceeded recommended limits for bathing waters. In 1958, an estimated 64% of the dissolved solids load in the river at Marshall was due to pollution. By 1966, 74% of the dissolved load could be attributed to pollution. Loads of dissolved solids, sodium, sulfate, and calcium showed the most dramatic increases, coinciding with general increases in population and industrial employment. New wastewater treatment facilities and improved industrial technology have apparently combined to curb pollution and reverse the earlier trend. In 1977 water quality had returned at least to levels of 1958.