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median pH level for County ground water was 6.93, very close to neutral. There <br /> was a wide range of values, with a high of 8.3 at a well northeast of <br /> Hillsborough, and a low of 4.72 in Bingham Township. <br /> Conductance measures the ability of water to conduct electricity, which is of <br /> significance because ionized particles in ground water may be indicative of total <br /> dissolved solids in the water. The median value in the County is 180 <br /> microsiemens per centimeter. A considerable range of conductance exists in the <br /> County, with values ranging from a high of523 and a low of 26. Although the <br /> range is broad , most values were typical for ground water in the Piedmont. <br /> Dissolved oxygen is a product of precipitation and ground water recharge. <br /> Increased dissolved oxygen can indicate loss of precipitates, while low levels of <br /> dissolved oxygen are associated with high levels of iron, manganese, sulfate and <br /> dissolved organic matter. The median value for County ground water was 2.5 <br /> milligrams per liter . (mg/L), with highest variance again found in felsic <br /> metavolcanic rocks. The range of findings for dissolved oxygen runs from 9.4 <br /> mg/L to 0.03 mg/L. Again, these measurements are within the expected range of <br /> ground water quality for the Piedmont. <br /> Alkalinity measures the capacity to neutralize acid in the water, usually produced <br /> by carbon dioxide and bicarbonate, The median alkalinity found in Orange is 103 <br /> mg/L of calcium carbonate, with a high of 194 and a low of 24. <br /> B. Major Ions <br /> Major ions dissolved from soil and bedrock into ground water also help describe <br /> the chemical makeup of the water — whether cations (ions with a positive <br /> electrical charge) or anions (negative electrical charge). Common cations are <br /> calcium, magnesium, sodium and potassium. Common anions include <br /> bicarbonate, sulfate, chloride, fluoride and nitrate. <br /> Calcium and magnesium, as previously noted, are among the chemicals that <br /> cause many problems in ground water, including hardness of water — which can <br /> potentially cause scale in pipes and precipitates in hot water heaters. In certain <br /> areas of the County, high levels of these chemicals pose nuisance problems for <br /> many citizens. Generally-speaking, however, the incidence of these ions in the <br /> County's ground water is not out of line with expected levels in the Piedmont <br /> region. The median concentration of calcium in samples was 23 mg/L, and the <br /> median for magnesium was 4.4 mg/L. Other ions analyzed include sodium, <br /> potassium, bicarbonate, sulfate chloride and flouride. No unusual levels of these <br /> compounds were found in the sample. <br /> 6 <br />