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and an average TDS discharge of 101 tons persquare mile. Specific conductance ranges between <br />318 and 730 umhos, and the mean Sodium Adsorption Ratio {SAR) is about 0.7. Based on these <br />values, waters of the San Miguel at Naturita are classified as C2-S1, which categorizes the San <br />Miguel River as being good for irrigation use. As of 1957, approximately 15,000 acres underlain by <br />Dakota sandstonewere actively irrigated between Placerville and Naturita, Colorado (lorns, et a1. <br />1965a). Using historic streamflow information, lorns et a1. (1965a) estimated a water budget for <br />the San Miguel River in thisvicinity, and concluded thattheTDS contribution to the San Miguel River <br />fromirrigationisabout2.8tons/yearperacreofirrigatedland. As of 1957, waters of the San Miguel <br />River (except at the mouth during lowflows) were suitable fordomestic use, while during low flow, <br />high levels of sulfate would render the water unsuitable. <br />SITE SPECIFIC SURFACE WATER INFORMATION <br />Drainage Sasin Geomorphology <br />Map 2.04.7-1 delineates the areas named Firstand Second Park. The New Horizon 1 is located on <br />the gently sloped uplandjust north ofTuttle Draw, in the southern portion ofthe Second Park. The <br />revised New Horizon 2 mining area includes the mildly sloping upland area between Tuttle Draw (to <br />the north) and Calamity draw (to the south). The area is located approximately in the middle of the <br />First Park. Both the First and Second Parks are relatively flat (gently sloping) areas formed by <br />regional uplift of sedimentary rocks that have been subsequently dissected by both Tuttle and <br />Calamity Draws. Both Parks consistprimarilyofrecentdepositsofundifferentiatedeoliansiltsand <br />sands that overlay the Dakota and Burro Canyon Formations. With the completion ofthe Colorado <br />Cooperative Company's Main Irrigation Ditch in about 1910, these deposits have been intensively <br />reworked by cultivation using irrigation water to form a broad rolling valley across the First and <br />Second Parks. <br />The revised New Horizon 2 permit area is located in the water sheds of both Tuttle Draw and <br />Calamity Draw. The revised New Horizon 2 permit area to the south and east of the West Lateral <br />irrigation ditch drains into Calamity Draw and consists of 396 acres. The area north and west of the <br />West Lateral irrigation ditch drains into Tuttle Draw and consists of 412 acres. The drainage area <br />of Calamity Draw to its confluence with the San Miguel River is about 7.0 square miles. The <br />drainage basin of Tuttle Draw is about 16 square miles. With the exception of the lower portion of <br />the Calamity Draw basin (nearthe mouth), the watershed is largely comprised of irrigated pasture <br />• (REVISED6/28/01) 2.04.7-22 <br />