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spoils aquifer inflow, During the period June through September for the <br />period of record, a peak flow of 10 cfs has been recorded, minimum flow was <br />zero, and mean daily flow was 0.3 cfs. A fairly constant TDS concentration of <br />2500 mg/1 has been observed during the past 5 years (1981 through 1986). <br />A second pond which discharges to Grassy Creek is the Northwest Impoundment <br />(NPDES 003). The June through September mean flow is approximately 0.07 cfs, <br />with maximum of 2 cfs and minimum of zero. TDS concentrations of 900 mg/1 <br />were characteristic before 1983, prior to discharges from a truck-wash <br />facility (which contributes flow to the Northwest Impoundment) using Wadge <br />Impoundment water as a source. Subsequently, as the Northwest Impoundment <br />discharges have increased, TDS has increased to 1900 mg/1 in the effluent. <br />At the surface water monitoring station on Grassy Creek below Seneca II Mine <br />(SW-S2-2), the quantity and quality of water exiting the mine is monitored. <br />The June through September mean flow far the period of record is 1.3 cfs, with <br />minimum of 0.002 cfs and maximum of 10 cfs. A mean concentration of 1600 mg/1 <br />has been observed at this site during the past 5 years (1981-1986). <br />Fish Creek Drainage Basin <br />Surface water flow and quality have been monitored on Cow Camp Creek at site <br />SW-S2-6, located near the permit area boundary, since about 1982. This <br />station is located a short distance downstream of Pond 004 in the southeast <br />part of the permit area. Flow rates measured at the 004 pond outfall and at <br />SW-52-6 are historically similar. A June through September mean flow of 0.12 <br />cfs is characteristic, with a minimum of zero and maximum of 2 cfs being <br />measured at the outlet of Pond 004 during the period of record (1982-1986). <br />Prior to mining disturbance in the Cow Camp Creek drainage the creek was <br />ephemeral. Subsequent to disturbance in this drainage, flow has been <br />perennial, with a base flow of about 0.12 cfs. During the monitoring period <br />(1982-1986), TDS has increased from about 600 mg/1 in 1982 to 1900 mg/1 in <br />1986. Concentrations of sulfate, calcium and magnesium have increased in <br />similar proportion, while sodium and bicarbonate concentrations have decreased. <br />Limited data have been collected to date in the Bond Creek drainage. However, <br />actual surface mining activities have not begun in this drainage at present. <br />Monitoring data obtained during 1986 showed a minimum flow of 0.014 cfs and <br />maximum of 0.85 cfs. Prior to mining, no flow during August and September is <br />anticipated at surface station SW-S2-9, located on Bond Creek near the permit <br />area boundary. Initial TDS data indicate a base level of 340 mg/1. Water in <br />the undisturbed drainage can be characterized as a calcium bicarbonate type. <br />A surface water monitoring station located on Fish Creek above the Seneca II <br />Mine inflow (via Cow Camp Creek) indicates a June through September mean flow <br />of 10 cfs during the period 1979-1986. A mean TDS concentration for this <br />period at this station is 530 mg/1. <br />tonitoring of Fish Creek below the confluence with Cow Camp Creek during this <br />same period does not show any identifiable change in the flow or quality of <br />Fish Creek due to discharge from Cow Camp Creek. <br />_1 g_ <br />