2010-12-08_PERMIT FILE - C1981008A (9)

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West Lateral Ditch crosses the proposed New Horizon 2 mining area. In regard to the agricultural water quality standards, the San Miguel River water delivered by the irrigation ditches is more suitable for irrigation purposes than the waters in Tuttle or Calamity Draw. The agricultural suitability (National Academy of Sciences, 1972) of surface water in Calamity and Tuttle Draws falls within the category of water that can only be used for salt tolerant plants on permeable soils with careful management practices (TDS from 2,000 to 5,000 mg /1). Using the same classification system, water supplied by the West Lateral irrigation ditch (San Miguel River) (TDS 500 mg /l or lower) will have no detrimental effects on plants. Waters of Tuttle and Calamity Draws have commonly exceeded the manganese and PH agricultural standards. Since the early part of this century, it has been a regional practice to obtain water for irrigation from the San Miguel River. Because of the incised nature of the stream channel, it is difficult to flood irrigate from either Tuttle or Calamity Draw. From field reconnaissance investigations, it has also been determined that water pumpage from these draws for irrigation purposes is occurring infrequently. Subirrioation A small amount of subirrigation does occur along the Tuttle and Calamity Draw stream channels. Much of the alluvial ground water along these draws is a result of seepage from the irrigation ditches. In many areas where the subirrigation occurs, the vegetation and soil quickly dry up when the ditch is turned off from October to April. The subirrigation along Tuttle or Calamity Draw is not considered extensive enough to support agricultural development. Conclusion The CDRMS concluded in its Decision and Findings of Compliance Document (1983) that no alluvial valley floors exist in either the New Horizon permit area or the potentially affected area (Tuttle Draw) associated with the New Horizon Mine. WFC concludes, based on the following criteria, that no alluvial valley floors exist along the potentially affected area of Calamity Draw associated with the New Horizon 2 mining area. Water availability, quality, the limited extent of the unconsolidated streamlaid deposits and subirrggated areas, and the incised nature of Calamity Draw make it infeasible and impractical to construct a flood irrigation system employing gravity drainage. This conclusion is substantiated by the results of an EPA alluvial valley floor study (EPA 1977) which addresses most coal mining areas of the west and the fact that flood irrigation is not being practiced along Calamity Draw. Revised August 2010 (PR06) 2.05.6(3) -15