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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 <br />Formation; the Trout Creek sandstone is the uppermost member of the underlying Iles Formation. <br />The major alluvial aquifers in the area are associated with the Yampa and Williams Fork Rivers. <br />Many of the coal seams, discontinuous sandstones, siltstones and some of the smaller alluvial <br />bodies in the area of the mine are also water bearing. These, however, characteristically contain <br />insufficient quantities of water to be considered significant aquifers. Of the bedrock aquifers, the <br />Twentymile sandstone produces the best quality ground water, a bicarbonate -type possessing a <br />relatively low total dissolved solid content of less than 600 mg/1. Ground water in the White <br />sandstones contains total dissolved solids generally greater than 600 mg/1 due to high levels of <br />sulfate and bicarbonate. Ground water in the coal -seam aquifers and interbedded sandstones and <br />siltstones is commonly of poor quality with total dissolved solids greater than 1000 mg/l due to <br />high levels of bicarbonate and sodium. <br />Regional Climate <br />The region has a highland continental climate characterized by low precipitation, large <br />fluctuations in diurnal temperatures, low humidity, moderate wind speeds, and high levels of <br />insolation (exposure to sunlight). The Craig area is in the rain/snow shadow of mountain ranges <br />to the west and south and 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 <br />annual precipitation for the town of Craig, six miles north of Trapper, is 13.5 inches, of which <br />over one third is snowfall (averaging 66.5 inches/year). Trapper Mine's average annual <br />precipitation is 16.7 inches. Mean annual temperature in Craig is 43'F, with recorded extremes <br />of -45'F and 100'F. Winds predominate from the west, but are locally modified by topographic <br />features. The growing season for the area in the vicinity of Craig averages 77 frost -free days. <br />Soil Types, Characteristics and Distribution <br />Three soil orders are found in the permit area: <br />1. Aridisols <br />2. Entisols <br />3. Mollisols. <br />Characteristic of fairly steep, semi -arid regions of northwestern Colorado, they represent soils <br />grading from recently developed soil bodies with minimum horizon development (Entisols) to <br />older soils comprising well defined diagnostic horizons (Mollisols). Overall, the soils found in the <br />permit area are relatively deep and well drained exhibiting effective rooting depth ranges from <br />two to sixty inches. The deepest soils yielding the greatest rooting depths occur in valleys and on <br />the leeward sides of ridges. Soil reaction is slightly acid to moderately alkaline over the permit <br />area with the exception of inclusions of small scattered areas with saline substrata. These small <br />areas have probably formed in place from weathered sodic shale. <br />Page 9 <br />Trapper RN7 Prepared by: R. Reilley <br />Nov 2017 <br />