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overlain by varying thicknesses of undifferentiated eolian silts and sands. These deposits have <br />subsequently been reworked by water, forming rolling upland valleys that are dissected by both <br />Tuttle and Calamity Draws. Since completion of the Colorado Cooperative Company's main <br />irrigation ditch around 1910, the unconsolidated deposits have been further reworked by man to <br />form broad rolling valleys across the First and Second Park, making the area more conducive for <br />irrigation and agriculture. <br />The New Horizon 2 mining area is located entirely within the Calamity Draw watershed (7.0 square <br />miles) which is less than half the size of the Tuttle Draw watershed. Calamity Draw is also an <br />upland drainage area that is tributary to the San Miguel River. The middle and upper portion of this <br />watershed (the First Park) has been intensively irrigated and cultivated since about 1910. <br />Presently, the watershed is comprised of irrigated pasture, rangeland, and the town site of Nucla. <br />Agricultural and irrigation practices have resulted in a disjointed tributary drainage pattern which <br />is almost completely controlled by the return ditches of the irrigation network. Most of the <br />tributaries, especially in the mid and upper portion of Calamity Draw, are intermittent with flow being <br />controlled by the timing and application of irrigation water. Calamity Draw, in the vicinity of the New <br />Horizon 2 mining area, is a perennial, meandering stream with a narrow incised (up to three feet) <br />channel. The banks are stable as a result of vegetation encroachment. <br />Calamity Draw has the same valley bottom widths and geomorphic features as Tuttle Draw, but is <br />less steep and confining. The perennial flows of both draws are due to irrigation return water and <br />the limited baseflow is maintained by overburden ground water discharge. The overburden aquifer <br />is recharged from the upland irrigation system. <br />Irrigation <br />The area in the vicinity of New Horizon 2 has (since about 1910) had an extensive man -made <br />irrigation system. The water used for flood irrigation is diverted from the San Miguel River <br />approximately 15 mileseast ofthe New Horizon Mine by the Colorado Cooperative Ditch Company. <br />The irrigation ditches transect basins and commonly run along the basin divides (see Map 2.04.7 - <br />1A for the exact location of the irrigation ditches). The main irrigation ditches have a network of <br />feeder ditches running from them for irrigating outlying fields. These ditches are a source of <br />ground water recharge, causing ground water mounding in the shallow ground water aquifer <br />system. The effects of mounding near the New Horizon Mine are apparent from monitor well water <br />levels and hydrographs (see Attachment 2.05.6(3) -1, formerly Peabody Appendix 7 -2). Perennial <br />flow occurs in Tuttle Draw as a result of ground water discharge and return flow from the irrigation <br />of the upland area. Site inspections confirm that water used for irrigation is obtained from the San <br />Miguel River and no flood irrigation water is obtained from Tuttle Draw or Calamity Draw. The <br />Revised August 2010 (PR06) 2.05.6(3) -14 <br />