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period in this portion of Routt County. A minimum flow of zero and maximum flow <br />of 8 cfs has occurred during the period of record. TDS concentrations have <br />increased over the past nine years, from a 1987 average of 600, to a 1996 average of <br />787. <br />Outflow from the Wadge Impoundment (NPDES 002) which, along with the <br />Northwest Impoundment (NPDES OCJ), is located downstream of site SW-S2-1, is <br />governed by three sources; snowmelt runoff, rainfall runoff and spoils aquifer <br />inflow. During the period June through September for the period of record, a peak <br />flow of 11 cfs has been recorded, minimum flow was zero, and mean daily flow was <br />0.3 cfs. An increase in TDS concentration has been observed during the past 9 <br />years, from an average of 2332 mg/I in 1987 to an average of 2951 mg/1 in 1996. <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/I <br />were characteristic before 1983, prior to discharges from atruck-wash facility <br />(which contributes flow to the Northwest Impoundment) using Wadge Impoundment <br />water as a source. Subsequently, as the Northwest Impoundment discharges have <br />increased, TDS has increased to an average of 2943 mg/1 in the effluent in 1996. <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. The <br />June through September mean flow for the period of record is 1.3 cfs, with <br />minimum of 0.002 cfs and maximum of 10 cfs. A mean concentration of TDS <br />2138 mg/I has been observed at this kite between 1987 and 1996. <br />Fish Creek Drainage Basin <br />Cow Camp Creek <br />Since 1982, surface water flow and quality on Cow Camp Creek have been <br />monitored at site SW-S2-6, 1/4 mile downstream of Pond 004, and at the outfall of <br />Pond 004. Flow rates measured at the 004 outfall and at SW-S2-6 are directly <br />related. In 1983 the yearly average flow was 0.154 cfs and in 1996 was .609 cfs. <br />Prior [o mining disturbance in the Cow Camp Creek drainage, the creek was <br />ephemeral. Pit disturbance in the drainage has resulted in perennial flow at <br />SW-S2-6, with a year round average of .235 cfs. <br />Total dissolved solids in Cow Camp Creek have escalated as mining in the drainage <br />area has progressed. TDS has increased from an average of 600 mg/1 in 1982 to an <br />26 <br />