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Flow in the West Lateral irrigation ditch is exclusively controlled by the Colorado Co-operative <br />Company. The ditch is "turned on" usually in mid-April, and continues to operate up until about <br />mid-October, depending on the length of each year's growing season. During the remainder of <br />each year, the ditch is turned on temporarily to provide water for filling cisterns and stock ponds. <br />Water delivered via this lateral and the rest of the surrounding ditch system provides a water <br />source for irrigation, drinking water and livestock use, and is the dominant seasonal influence of <br />the hydrologic regime in the vicinity of the New Horizon Mine. <br />Most reaches along the West Lateral lose irrigation flow to diversions, evapotranspiration and, of <br />course, seepage. The reaches that showed a loss in flow had water being withdrawn along each <br />reach through diversions on the day the study was performed, as well as significant lengths of <br />heavily vegetated bank sides. Seepage of irrigation water occurs along the entire reach of the <br />West Lateral, probably occurring at higher rates and volumes along the "ridge-top" reach where <br />the ditch was excavated through the shallow soils into the highly fractured sandstone. <br />The two reaches where the ditch featured gains in flow are portions of the general "ridge-top" <br />segment of the West Lateral. The ditch channel bottom in this reach is largely fractured and <br />weathered sandstone, and likely results in relatively large amounts of seepage. This seepage, in <br />combination with localized intensive "flooding-type" irrigation, travels laterally through the <br />shallow soils and fractured sandstone eventually flowing back into the West Lateral slightly <br />downstream. The combination of fractured, weathered sandstone channel bottoms in the ditch <br />and localized "flood-type" irrigation along these two gaining reaches likely resulted in the <br />measured gains in flow. <br />Flows in Calamity Draw, which is roughly parallel to the southern boundary of Mine 2, generally <br />reflect local irrigation practices. Water from the West Lateral Ditch's return irrigation flow is its <br />primary source. Very little supplemental flow is derived from precipitation and snowmelt <br />runoff. In 1987, measured flow rates in Calamity Draw varied from 0.605 cfs in April to 13.4 cfs <br />in July. Flow in Calamity Draw varied from 1.04 to 2.06 cfs during the non-irrigation period. <br />Shallow ground water alluvial sources provide a large portion of this low flow period's water. <br />This ground water flow is related to local irrigation practices but is consolidated into a more <br />uniform and regular flow by the permeability of these near surface alluvial deposits. Sediment <br />Pond 007 for the New Horizon Mine 2 mining site will contribute water to the Calamity Draw <br />system. The drainage system at the Mine 2 site has been designed to provide adequate capacity <br />and storage times' to completely control a 10-year 24-hour precipitation event. This system will <br />collect all runoff from the mine site and should actually lower present total suspended solids <br />(TSS) contribution from this area over the life of the mine. Increased TDS levels in this water <br />from mining disturbances are expected, but are projected to be within acceptable discharge levels <br />and will be mitigated by dilution. Regular monitoring of these flow rates and water quality will <br />give adequate control of this current water source to protect water quality in Calamity Draw. <br />The discharges from the mine enter Calamity Draw at a point about 2.5 miles above the <br />confluence of Calamity Draw and the San Miguel River. <br />The above-mentioned parks consist of recent undifferentiated aeolian silts and sands overlaying <br />the Dakota and Burro Canyon Formations. The perennial flow nature of both Tuttle and <br />Calamity Draws is largely due to the local irrigation practices. Over the years this more or less <br />11