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.. 0014 <br /> C. Nutrients <br /> Nutrients such as nitrogen and phosphorus are important to plant and animal <br /> life, but higher concentrations of these nutrients can often threaten surface and <br /> ground water supplies. Usually, increased levels of nutrients are the result of <br /> human activity — the use of fertilizer or manure, septic systems, or combustion of <br /> fossil fuels. Nutrients in ground water usually take the form of nitrate, nitrite and <br /> ammonia. In particular, a drinking water standard for nitrate (10 mg/L) is set to <br /> protect against high levels, which are dangerous and can pose health risks of <br /> anemia and other conditions for small children and the infirm. <br /> High concentrations of nutrients in County ground water may reflect excessive <br /> human activity as mentioned above, or poor well construction. Of the 51 wells <br /> studied in the County, 82% of the samples contained nitrate. While there were <br /> widespread findings of nitrate, most were of low concentration. The median <br /> value of all wells sampled was 0.49 mg/L, although one well had a high reading <br /> of 7.2 mg/L. All other wells sampled were below 3 mg/L. Ammonia and <br /> orthophosphate were only detected at low concentrations. <br /> D. Total Dissolved Solids <br /> Dissolved solids measures the mass of solutes in a water sample after <br /> evaporation. Higher or lower than average dissolved solids are indications of the <br /> potential for scaling or clogging of plumbing from precipitate minerals. Dissolved <br /> solids are generally lower in the Piedmont's crystalline rocks than in other <br /> regions of the state and nation, and the median dissolved solids concentration in <br /> the County from the analysis is 125 mg/L. This level is typical of the Piedmont <br /> area of the southeastern U.S. <br /> E. Metals and Trace Elements <br /> Metals and trace elements were detected infrequently in the County's well <br /> sampling. No trace elements exceeded the U.S. EPA's MCL's (maximum <br /> contaminant levels), although some metals were found at levels worthy of note. <br /> Zinc, manganese, iron and copper were the most frequently detected metals. <br /> In three samples, the level of iron exceeded the level of N.C. drinking water <br /> standards. Manganese exceeded drinking water standards in 12 of the 51 wells <br /> sampled — and in three cases both iron and manganese were exceeded. As has <br /> been known for years, iron and manganese are sometimes a primary concern <br /> with ground water supplies in the County, and cause significant water quality <br /> nuisances in both the County and state. In excessive amounts, iron and <br /> manganese can stain teeth, plumbing fixtures, skin or laundered products, and <br /> also may cause odor or taste concerns. <br /> Lead was detected in 8 of the 51 samples, .although at levels below State and <br /> Federal MCL. The levels were, however, greater than the zero-level goal that has <br /> 7 <br />