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The permit area lies structurally between the parallel, south-southeast trending Sage Creek and <br /> Fish Creek anticlines. The axis of the Sage Creek Anticline is situated about one to two miles <br /> west of the western edge of the Yoast permit area. The axis of the Fish Creek Anticline <br /> originates near Scotchman's Gulch and extends south-southeasterly dividing the northern first <br /> five-year mine block from the neck portion of the permit area. <br /> The rock units in the permit area dip predominantly 15 to 20 percent to the north in the north <br /> mine block, to the northwest in the neck area, and to the west in the south mine block. More <br /> extreme dips of 25 to 35 percent occur locally in the northwest and northeast parts of the north <br /> mine block. The rock units are apparently unaffected by any significant faulting within the permit <br /> area. <br /> Surface Water <br /> The Yoast Mine drains to Sage Creek on the west side and to Grassy Creek on the east side. <br /> Sage Creek and Grassy Creek are perennial tributaries to the Yampa River. Annand Draw and <br /> Scotchman's Gulch are intermittent drainages which drain from the northern side of the permit <br /> area into Grassy Creek. The Yampa River then flows to the Green River and eventually to the <br /> Colorado River. <br /> Sage Creek <br /> Sage Creek is a perennial stream to the west of the permit area. Flows upstream from the permit <br /> area range from an average 0.7 cubic feet per second (cfs) in the spring to near 0 in late summer <br /> and fall. Approximately two miles downstream from the permit area, average flows of 1.5, 0.09, <br /> and 0.04 cfs were observed during baseline data collection in the spring, summer, and fall <br /> respectively. <br /> Water quality in Sage Creek varies from upstream to downstream. Baseline data indicate a <br /> predominantly CaMgHCO3 water type upstream from the permit area. Total dissolved solids <br /> (TDS) typically ranged from 296 to 510 mg/1 at high and low flows, respectively. A <br /> CaMgSO4HCO3 water type predominated downstream from the permit area, and TDS typically <br /> ranged from 526 to 695 mg/1 at high and low flows, respectively. <br /> Most of the flow in Sage Creek is diverted out of the stream for irrigation purposes prior <br /> to reaching the site where downstream baseline data was collected. Sage Creek water is <br /> also utilized for livestock watering. <br /> Grassy Creek <br /> Grassy Creek is a perennial stream to the east of the permit area. Flow in Grassy Creek upstream <br /> from the permit area was perennial during baseline data collection. Mean flow rates in the <br /> spring, summer, and fall were 0.91, 0.10, and 0.06 cfs respectively. A CaMgSO4HCO3 water <br /> type predominated upstream from the permit area. TDS ranges from 680 to 853 mg/1 at high and <br /> low flows, respectively. <br /> Permit Area <br /> Intermittent flows from the northern side of the permit area drain through Annand Draw into <br /> Scotchman's Gulch and then into Grassy Creek. Spring flows in Annand Draw are <br /> predominantly from the melting of snowpack. Late spring to early summer flows are a <br /> combination of bank storage, runoff from precipitation events over saturated or frozen ground, or <br /> 6 <br />