1999-10-15_GENERAL DOCUMENTS - C1994082

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The proposed permit area lies structurally between the parallel, south-southeast trending Sage Creek and Fish Creek anticlines. The axis of the Sage Creek Anticline is situated about one to two miles west of the western edge of the Yeast permit area. The axis of the Fish Creek Anticline originates near Scotchman's Draw and extends south-southeasterly dividing the northern first five-year mine block from the neck portion of the permit area. The rock units in the proposed permit area dip predominantly 15 to 20 percent to the north in the north mine block, to the northwest in the neck area, and to the west in the south mine block. More extreme dips of 25 to 35 percent occur locally in the northwest and northeast parts of the north mine block. The rock units are apparently unaffected by any significant faulting within the permit area. Surface Water The Yoast Mine drains to Sage Creek on the west side, and to Grassy Creek on the east side. Sage Creek and Grassy Creek are perennial tributaries to the Yampa River. Armand Draw and Scotchmans Gulch are intermittent drainages which drain from the northern side of the proposed permit area into Grassy Creek. The Yampa River then flows to the Green River and eventually the Colorado River. Refer to Figure 3 for more detail. Sage Creek Sage Creek is a perennial stream to the west of the proposed permit area. Flows upstream from the proposed permit area range from an average 0.7 cubic feet per second (cfs) in the spring to near 0 in late summer and fall. Approximately two miles downstream from the permit area, average flows of 1.5, 0.09, and 0.04 cfs were observed during baseline data collection in the spring, summer, and fall respectively. Water quality in Sage Creek varies from upstream to downstream. Upstream from the permit area, a CaMgHCC03 water type predominates. Total dissolved solids (TDS) typically range from 296 to 510 mg/l at high and low flows, respectively. Downstream from the permit area, a CaMgSO4HCO3 water type predominates, and TDS typically ranges from 526 to 695 mg/l at high and low flows, respectively. Most of the flow in Sage Creek is diverted out of the stream for irrigation purposes prior to reaching the site where downstream baseline data was collected. Sage Creek water is also used for livestock watering. Grassy Creek Grassy Creek is a perrenial stream to the east of the permit area. Flow in Grassy Creek upstream from the permit area was perennial during baseline data collection. Mean flow rates in the spring, summer and fall were 0.91, 0.10, and 0.06 cfs respectively. A CaMgSO4HCO3 water type predominates upstream from the permit area. TDS ranges from 680 to 853 mg/l at high and low flows, respectively. Yoast Mine 10 October 19, 1999