Reservoir vital signs monitoring, 1992: Bacteriological conditions in the Tennessee Valley. Fourth annual report.

摘要

Twenty-eight designated swimming beaches, four informal swimming areas, two canoe launching or landing sites, and two additional sites on a canoeing stream were sampled at least ten times each during 30-day sampling periods in the summer of 1992. One designated swimming beach, one informal swimming area, and two canoe launching or landing sites exceeded the recommended criterion of geometric mean concentrations of fecal coliform bacteria of 200/100 mL. In addition to these four sites, five designated swimming beaches and one informal swimming area exceeded the US Environmental Protection Agency (EPA) recommended criterion by having more than 10 percent of the fecal coliform samples with concentrations greater than 400/100 mL. Rainfall was an important factor for these six sites and the four sites that did not meet the geometric mean criterion. Some sampling sites are affected by rainfall more than others. When bacteria concentrations increase after rainfall, it indicates that site is vulnerable to contamination from nonpoint sources of pollution. Recreational use of these sites following rainfall is discouraged. If samples collected within 24 hours of rainfall (one-half inch or more) are excluded, all-but one of the ten sites have better bacteriological water quality, and two meet both the geometric mean and maximum concentration criteria. Five canoe access locations on the Bear Creek floatway, plus one site upstream and another downstream of the floatway were sampled eight times each during 1992. All seven sites met recreation criteria.