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Ground-water samples were collected from 1995 through 1999 from 60 wells (30 domestic wells and 30 monitoring wells adjacent to burley tobacco fields) and 35 springs in the Valley and Ridge Physiographic Province within the Upper Tennessee River Basin as part of the U.S. Geological Survey National Water-Quality Assessment Program. These samples were analyzed for nutrients, fecal indicator bacteria, pesticides, and volatile organic compounds.
Concentrations of nitrate were less than 3 milligrams per liter in 97 percent of water samples collected from the wells and springs. None of the water samples collected from domestic wells or springs exceeded the public-supply drinking water standard of 10 milligrams per liter (mg/L). Five water samples collected from monitoring wells adjacent to burley tobacco fields had concentrations that exceeded 10 mg/L with a maximum concentration of 32.5 mg/L. Despite elevated levels of nitrate in monitoring wells, extensive nitrate contamination of the ground water is unlikely to occur as a result of tobacco production because tobacco fields are limited in size (generally less than 2 acres).
Fecal indicator bacteria, such as total coliform and E. coli (Escherichia coli), were frequently detected in domestic wells and springs. The presence of any of the indicator bacteria is considered unacceptable for State public-supply drinking-water standards. Total coliform was detected in 100 percent of the springs and 37 percent of the domestic wells. E. coli was detected in 97 percent of the springs and 30 percent of the domestic wells. About half of the 35 springs sampled are used for domestic drinking-water supply while other springs near roadsides are frequently used for drinking-water purposes.
Pesticides were detected in water samples collected from 69 percent of the springs, 43 percent of the domestic wells, and 40 percent of the monitoring wells adjacent to burley tobacco fields. Concentrations of pesticides generally were low [less than 0.05 micrograms per liter (µg/L)] and were less than applicable drinking-water standards; however, 13 of the 18 pesticides detected have no established drinking-water standards. The most frequently detected herbicides were atrazine, deethylatrazine (a degradation product of atrazine), and prometon. The only insecticides detected were dieldrin and p,p'-DDE, a degradation product of DDT. The maximum concentration of pesticides detected was 17.3 µg/L of tebuthiuron.
Volatile organic compounds were detected in 86 percent of the springs, 67 percent of the domestic wells, and 90 percent of the monitoring wells. Concentrations of volatile organic compounds generally were low (less than 0.5 µg/L). None of the volatile organic compounds detected exceeded drinking-water standards, but 20 of the 44 compounds were chloroform, styrene, and toluene. The maximum volatile organic compound concentration detected was 9.51 µg/L of MTBE.
Friday, 13-Apr-01 14:34:11 CST
This abstract can be cited as follows:
Johnson, G.C., 2001, Ground-water quality in the Valley and Ridge Physiographic Province in the upper Tennessee River Basin, 1995-99 [abs.], in Tennessee Water Resources Symposium, 11th, Burns, Tenn., 2001, Proceedings: Tennessee Section of the American Water Resources Association, p. 1A-8.
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