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Surface water Hydrology There are two (2) major northwestern Colorado rivers which intersect the permit area. These are the Yampa and Williams Fork Rivers. The Yampa River runs from north to south through the permit area, while the Williams Fork River runs from south to north and joins the Yampa River north of the mine facilities area. The northern portion of the permit area is dominated by the Big Bottom alluvium, while the southern and eastern portions of the permit area are dominated by the Williams Fork Mountains and the river beds of the Yampa and Williams Fork Rivers. Both rivers depend primarily on snowmelt for their flow. Ground water discharge contributes to the base flow in the late summer months. Both the Yampa and Williams Fork Rivers have deeply incised valleys at their confluence due to down-cutting in the resistant sequence of sandstones in this area. The broad valley floors of Big and Round Bottoms resulted from the erosion of the less resistant rock strata of the Lewis Shale. 't'hree alluvial valley floors are formed in synclines within the permit and adjacent area. These are the alluvium associated with the Williams Fork and Yampa Rivers. The Williams Fork alluvium averages 800 to 1,000 feet wide within the permit area. The Yampa River alluvium is up to 9,000 feet wide with an average width of 5,000 feet in the permit area. Ground Water Hydrelogy There are five bedrock aquifers within the permit and adjacent areas of Beagle Mines. These aquifers are the Tow Creek and Trout Creek Sandstones of the Iles Formation, the Middle Sandstone, the Twentymile Sandstone and the White Sandstone of the Williams Fork Formation. The alluvium of the Williams Fork and Yampa Rivers contain ground water. The alluvia are generally recharged laterally by adjacent rock aquifers, by direct infiltration of precipitation, by irrigation waters, or by surface water flow. The alluvial ground waters discharge into the rivers, producing baseflowe. Climate The climate of the region is classified as highland continente~l. It is characterized by low precipitation, large fluctuations in diurzial temperatures, low humidity, moderate wind, and high levels of insulation. 77xe local climate of the Craig, Colorado, area is characteristic of the semi-arid [steppe regions. The average annual precipitation for the area is 14.0 inches, of which over one-third is snowfall (averaging 66.5 inches/year). The mean annual ter~erature is 43°F, with recorded extremes of -45°F and 100°F. Winds are predomi~xantly from the west, but are locally modified by topographic features. The growing season for the Craig area averages 77 days. Soils Three soil orders are found within the proposed permit area; Aridisols, Mollisols and Bntisols. Topographic features have played a significant role in the develop- ment of these soil bodies. Generally speaking, the Aridisols and thinner Mollisols are found in the fairly steep areas on the eastern portion of the pro- posed permit area, and the thicker Mollisols and Entisols are along the bottom areas of the Williams Fork drainage. However, overall the soils encountered are relatively deep (except for outcrop areas) and fairly well drained. &ffective rooting depth varies from 20-60 inches, with the most productive soils found in the bottomland areas. Soil reaction is neutral to slightly alkaline, with the exception of small scattered sodic substrata. These small isolated areas probably formed in place from weathered sodic shales.