Laserfiche WebLink
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 miles east of the 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 ground <br />water recharge, causing ground water mounding in the shallow ground water aquifer system. The <br />effects of mounding near the New Horizon Mine are apparent from monitor well water levels and <br />hydrographs (see Attachment 2.05.6(3) -1, formerly Peabody Appendix 7 -2). Perennial flow occurs <br />in Tuttle Draw as a result of ground water discharge and return flow from the irrigation of the upland <br />area. Site inspections confirm that water used for irrigation is obtained from the San Miguel River <br />and no flood irrigation water is obtained from Tuttle Draw or Calamity Draw. The West Lateral Ditch <br />crosses the proposed New Horizon 2 mining area. <br />In regard to the agricultural water quality standards, the San Miguel River water delivered by the <br />irrigation ditches is more suitable for irrigation purposes than the waters in Tuttle or Calamity Draw. <br />The agricultural suitability (National Academy of Sciences, 1972) of surface water in Calamity and <br />Tuttle Draws falls within the category of water that can only be used for salt tolerant plants on <br />permeable soils with careful management practices (TDS from 2,000 to 5,000 mg /1). Using the <br />same classification system, water supplied by the West Lateral irrigation ditch (San Miguel River) <br />(TDS 500 mg /I or lower) will have no detrimental effects on plants. Waters of Tuttle and Calamity <br />Draws have commonly exceeded the manganese and PH agricultural standards. <br />Revised September 2014 JR -64) 2.05.6(3) -15 <br />