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o F <br /> o G2 <br /> o H <br /> o I <br /> o L <br /> o M <br /> o Q and Q rider <br /> o R and R rider. <br /> Surface Water Hydrology <br /> Drainages within and adjacent to the permit area(on the north facing slope) drain south to north in a <br /> dendritic pattern as illustrated in Map 1 above. Drainages flow primarily in response to snowmelt <br /> and/or heavy rains, eventually discharging to the Yampa River. Drainages in the southern portion of <br /> the permit area drain southward to the Williams Fork River. Natural surface waters are of a calcium- <br /> magnesium-sulfate type, with total dissolved solids content commonly greater than 1000 mg/1 in the <br /> smaller streams, and less than 1000 mg/1 in the largest streams. Total dissolved solids <br /> concentrations commonly peak during periods of low stream flows; during high flows, waters are <br /> diluted, resulting in low concentrations. <br /> Ground Water Hydrology <br /> Within the general area of the Trapper Mine, ground water exists in both bedrock and alluvial <br /> aquifers. Significant bedrock aquifers are the Trout Creek, Middle, Twentymile, and White <br /> sandstones. The Middle, Twentymile and White sandstones lie within the Williams Fork Formation; <br /> the Trout Creek sandstone is the uppermost member of the underlying Iles Formation. The major <br /> alluvial aquifers in the area are associated with the Yampa and Williams Fork Rivers. Many of the <br /> coal seams, discontinuous sandstones, siltstones and some of the smaller alluvial bodies in the area of <br /> the mine are also water bearing. These,however, characteristically contain insufficient quantities of <br /> water to be considered significant aquifers. Of the bedrock aquifers, the Twentymile sandstone <br /> produces the best quality ground water, a bicarbonate-type possessing a relatively low total dissolved <br /> solid content of less than 600 mg/l. Ground water in the White sandstone contains total dissolved <br /> solids generally greater than 600 mg/1 due to high levels of sulfate and bicarbonate. Ground water in <br /> the coal-seam aquifers and interbedded sandstones and siltstones is commonly of poor quality with <br /> total dissolved solids greater than 1000 mg/1 due to high levels of bicarbonate and sodium. <br /> Regional Climate <br /> The region has a highland continental climate characterized by low precipitation, large fluctuations in <br /> diurnal temperatures, low humidity, moderate wind speeds, and high levels of insolation (exposure to <br /> sunlight). The Craig area is in the rain/snow shadow of mountain ranges to the west and south and <br /> consequently has a high number of dry, clear days. <br /> Local Climate <br /> The climate of the Craig, Colorado area is characteristic of semi-arid steppe regions. Average annual <br /> precipitation for the town of Craig, six miles north of Trapper,is 13. 5 inches, of which over one <br /> third is snowfall (averaging 66.5 inches/year). Trapper Miine's average annual precipitation is 16.7 <br /> inches. Mean annual temperature in Craig is 43°F, with recorded extremes of-45°F and 100°F. <br /> Winds predominate from the west, but are locally modified by topographic features. The growing <br /> 7 <br />