1997-11-13_REVISION - M1977493 (50)

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Iron (dissolved [d]) was higher than the chronic water quality standard of 0.3 mg/L (also the secondary drinking water standard) in the first three sampling events, however, by Sampling Event 4 (June 6, 1997), iron (d) concentrations ranged from 0.08 to 0.09 mg/L which are well below the chronic water quality standard of 0.3 mg/L. Iron (d) concentrations have remained below the chronic water quality and secondary drinking water standard for the past six sampling events. ),Manganese The chronic water quality standard for manganese (tr) is 1.0 mg/L. Manganese (tr) was higher than water quality standards for the first three sampling events. Concentrations of manganese (tr) for the first two sampling events ranged from 7.1 to 9.02 mg/L. Although manganese (tr) concentrations still exceeded the chronic water quality criteria for Sampling Event 3, concentrations were significantly lower and ranged from 1.45 to 1.98 mg/L. By Sampling Event 4, manganese (tr) concentrations were below the chronic water quality standard of 1.0 mg/L. Manganese (tr) has remained below the water quality standard for the six sampling events since Sampling Event 4 and results from the most recent sampling event (July 25, 1997) showed concentrations ranging from 0.005 to 0.017 mg/L which are well below the chronic water quality standard. The chronic water quality standard for manganese (d) is 0.05 mg/L (also the secondary drinking water standard). Manganese (d) was higher than the chronic water quality standard for the first • six sampling events. By Sampling Event 7 (June 26, 1997), manganese (d) concentrations met the chronic water quality standard of 0.05 mg/L. For all sampling events following Sampling Event 7, manganese (d) concentrations have remained below chronic water quality and secondary drinking water standards and have continued to decrease with concentrations ranging from 0.005 to 0.016 mg/L for the most recent sampling event(July 25, 1997). Nitrogen (ammonia) The chronic water quality standard for ammonia is based on pH and temperature. The water quality standard for each sampling event was calculated based on the mean pH and temperature for that sampling event. Nitrogen was higher than water quality standards in Sampling Events 1 and 3 only. pH 9� The acute and chronic water quality standards for pH are a range o 6.9 to 9.0 standard units. pH measurements were taken in the field and laboratory. The first three sampling events indicated acidic water with pH values ranging from 4.2 (field measurement) to 7.0. pH values ranged from 7.12 to 8.8 for the following seven sampling events which are within the acceptable range. DAPROJECTS\6102-001\SWSUMIDOC[9-Sep-97] 3