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• EASTERN MINING DISTRICT <br />Site 8 is located approximately 2.5 miles downstream of the former U.S.G.S. Station 09243800. Flow was <br />monitored under the previous permit, and is currently being monitored only when water quality samples are <br />collected. <br />Foidel Creek at Mouth (former U.S.G.S. Station 09243900) is located 0.85 miles upstream of the confluence of <br />Foidel Creek with Middle Creek. The station has been operating since 1975 with a period of record from October <br />1975 through September 1981 and June 1982 through 1992. Table l OB shows a summary of flows from 1976 to <br />present. the mean annual flow for this station ranged from 0.07 cfs in water year 1977 to 4.39 cfs in water yeaz <br />1981. <br />Middle Creek <br />SVeam flow is monitored on Middle Creek by former U.S.G.S. Station 09243700 and is located 1.25 miles <br />upstream of the confluence with Foidel Creek. The period of record for the Middle Creek station is from October <br />1975 through September 1981 and April 1982 through the current year. Mean annual flow ranged from 0.5 cfs in <br />1977 to 7.22 cfs in 1980. <br />Surface Water Ouality <br />Farming and irrigation, road drainage, and previous mining affect baseline surface water quality above and below <br />the mine. Concentrations of major and trace constituents vary greatly with the rates of flow, evaporation, and the <br />location of sampling. A complete description of the baseline water quality prior to mining is found in Section 2.04 <br />• of the previous permit. <br />Results of the analyses for surface water quality samples taken during April and May of 1993 for Upper Foidel <br />Creek neaz Oak Creek (Station No. 14) are found in Table lOD, Water Quality Foidel Creek Near Oak Creek, <br />Station No. 14. Additional results of analyses for Upper Foidel Creek near Oak Creek, Foidel Creek at Site 8, and <br />Middle Creek at former U.S.G.S. Station 09243700 for 1992 are found in Tables 10E, IOF, and l OG, respectively. <br />Fluctuations in some surface water quality parameters are directly related to variations in flow rates. As stream <br />flows increase, concentrations of suspended constituents, such as total suspended solids or total iron, increase. <br />Increases in stream flow tend to decrease the concentrations of dissolved constituents because of dilution. <br />Water quality in Upper Foidel Creek, as measured in 1993, is shown on Table IOD. Total dissolved solids ranged <br />from 226 mg/i in April 1993 to 606 mg/I in May 1993. Fieid pH ranged from 8.2 units in April 1993 to 8.6 units in <br />May 1993. concenVations of total recoverable iron ranged from 0.33 mg/1 in April 1993 to 1.21 mg/1 in May <br />1993. Total recoverable manganese concenVations ranged from 0.01 mg/1 to less than 0.01 mg/1 from April 1993 <br />to May 1993, respectively. Total recoverable zinc concenVations ranged from below detection limit to 0.02 mg/1 <br />during April 1993. Other metals analyzed were consistently below detection limit. <br />Water quality at Site 8 is of magnesium-calcium sulfate type. Total dissolved solids ranged from 1,890 mg/I in <br />April 1992 to 3,856 mg/I in September 1992. Field pH ranged from 8.3 units in April and June 1992 to 8.5 units in <br />August 1992. Concentrations of total recoverable iron ranged from 0.4 mg/1 in August 1992 to 8.0 mg/1 in <br />September 1992. Total recoverable manganese concentrations ranged from 0.1 mg/I in April 1992 to 2.3 mg/1 in <br />June 1992. Total recoverable zinc concentrations ranged from below detection limit in June 1992 to 0.2 mg/I in <br />• August and September 1992. Other metals analyzed were consistently below detection limit. <br />PR 03-06 2.04-37 05/07/03 <br />