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Middle Creek and Fish Creek. These creeks drain in a northeasterly <br />direction towards Trout Creek, which flows north to the Yampa. Foidel <br />Creek was an intermittent stream which drained the Eckman Park area <br />northeasterly into Middle Creek. It has been transformed into a <br />perennial, effluent-dominated stream by mine inflow discharges from the <br />Foidel Creek underground mine. Peak discharges of all the Yampa's <br />tributaries are a consequence of snowmelt and incident precipitation <br />during the period from April to June. <br />Fish Creek has an average base flow of approximately 3 cfs, which is <br />derived from ground water contribution. Boettcher (1972) estimated that <br />roughly twenty-five percent of the total streamflow in Fish Creek comes <br />from ground water discharge. Peak discharge in Fish Creek, near the <br />proposed permit area, occurs during the period from March through June, <br />when the combination of snowmelt, incident precipitation and ground water <br />contribution result in discharge rates in excess of 25 cfs. The lack of <br />ground water discharges into Foidel Creek was evidenced by the no flow <br />periods in the stream during the summer and fall. As mentioned earlier, <br />Foidel is now a perennial stream with its base flow regime influenced by <br />mine discharges. Peak flows occur in response to snowmelt runoff, from <br />March through June, and high intensity rainfall events. <br />The Yampa and its tributaries are all calcium sulfate dominated waters. <br />Several have equal components of calcium and magnesium. Surface water <br />quality in the Upper Trout Creek drainage is affected at the baseline <br />level by farming, road drainage, and previous mining, Concentrations of <br />major and trace constituents vary greatly with the rates of flow and <br />evaporation, and the locality of sampling. Common elements observed <br />are: calcium, bicarbonate, sulfate, nitrate-nitrogen, total iron, and <br />total manganese. In general, surface water upstream from current mining <br />activities is alkaline, moderately saline and high in calcium carbonate <br />hardness. <br />Sulfate concentrations appear to increase both as flow increases in small <br />drainages and immediately downstream from disturbed area drainages. <br />Sulfate concentrations exceed the recommended drinking water standard of <br />250 mg/1 upstream of mining-related disturbance on Foidel Creek, and <br />standards are regularly exceeded downstream on Middle Creek and on Fish <br />Creek. (TABLE 5). Levels of sulfate on lower Trout Creek and along the <br />Yampa River are below the standard. Sulfates in the 1000-1500 mg/1 range <br />frequently have laxative effects, but concentrations as low as 200-500 <br />mg/1 may effect some individuals (USEPA, 1476). As waters from Foidel <br />and Fish Creek are used predominately for irrigation, future uses are <br />unlikely to be limited by elevated sulfate levels. <br />Total suspended solids levels increase with increased flow in all <br />drainages (TABLE 7). Average concentrations in the Yampa and its <br />tributaries all substantially exceed the NPDES discharge standard for <br />coal mines of 35 mg/1 average with 70 mg/1 once during a thirty day <br />period. TSS levels only meet that standard during low flows. The mines <br />will have no deleterious impact on TSS levels as all drainage from <br />disturbed areas must pass through sedimentation ponds and discharge must <br />meet the existing NPDES stream standard. <br />-38- <br />