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time, the ditch channel-bottom has been subsequently scoured and eroded. resulting in significant <br /> reaches of exposed and fractured sandstone. Further down the ditch course, the ditch channel is <br /> constructed through deeper soils, and features a sandy channel bottom. In most reaches, vegetation <br /> grows so heavily on the banksides that the Colorado Co-operative Company performs routine cutting <br /> and cleaning to ensure the integrity of the ditch channel. Occasionally, where the ditch courses <br /> through the deeper soils. the ditch bottom is periodically cleaned out (dredged). The overall gradient <br /> of the West Lateral irrigation ditch is approximately .014 ftlft. <br /> 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 each <br /> year, the ditch is temporarily turned on to provide water for tilling cisterns and stock ponds. Water <br /> delivered via this lateral and the rest of the surrounding ditch system provides a water source for <br /> irrigation, drinking water and livestock use, and is the dominant seasonal influence of the hydrologic <br /> 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 The reaches that showed a loss in flow had water being withdrawn along each reach <br /> through diversions on the day the study was performed, as well as significant lengths of heavily <br /> vegetated bank sides. Seepage of irrigation water occurs along the entire reach of the West Lateral, <br /> probably occurring at higher rates and volumes along the "ridge-top" reach where the ditch was <br /> 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 shallow <br /> soils and fractured sandstone eventually flowing back into the West Lateral slightly downstream. <br /> The combination of fractured, weathered sandstone channel bottoms in the ditch and localized <br /> "flood-type" irrigation along these two gaining reaches likely resulted in the measured gains in flow. <br /> Flows in Calamity Draw generally reflect local irrigation practices. Water from the West Lateral <br /> Ditch's return irrigation flow is its primary source. Very little supplemental flow is derived from <br /> precipitation and snowmelt runoff. In 1487, measured flow rates in Calamity Draw varied from <br /> 0.605 cfs in April to 13.4 cfs in July. Flow in Calamity Draw varied from 1,04 to 2.06 cfs during <br /> the non-irrigation period. Shallow ground water alluvial sources provide a large portion of this low <br /> flow period's water. This ground water flow is related to local irrigation practices but is consolidated <br /> into a more uniform and regular flow by the permeability of these near surface alluvial deposits. <br /> Sediment Pond 007 for the New Horizon Mine 2 mining site will contribute water to the Calamity <br /> Draw system. The drainage system at the New Horizon 2 site has been designed to provide adequate <br /> capacity and storage times to completely control a 10-year 24-hour precipitation event. This system <br /> wit[ 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 from <br /> 6 <br />