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• pipes and hoses that also route irrigation water to slightly lower elevation fields. <br />The West Lateral irrigation ditch is an unlined open channel. Where the ditch courses on the <br />ridge-top separating Tuttle Draw to the north and the Calamity Draw Valley to the south, the ditch <br />has been excavated through shallowsoils into the highlyfractured and weathered sandstone. Over <br />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, <br />vegetation grows so heavily on the banksides that the Colorado Co-operative Company performs <br />routine cutting and cleaning to ensure the integrity of the ditch channel. Occasionally, where the <br />ditch courses through the deepersoils, the ditch bottom is periodically cleaned out (dredged). The <br />overall gradient of the West Lateral irrigation ditch is approximately .014 fUft. <br />Flow. 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 ofeach year's growing season. During the remainderofeach <br />• year, the ditch is temporarily turned on to providewaterforfilling 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 waterand livestock use, and is the dominate seasonal influence of the hydrologic <br />regime in the vicinity of the New Horizon Mine. <br />As a part of baseline studies initiated in and near the New Horizon 2 mining area, three surface <br />water monitoring sites were established along the West Lateral forobtaining flow and waterquality <br />baseline information. These siteswere SW-N104, SW-N105 and SW-N106 and were located on <br />the West Lateral at points upstream, midway and downstream of the New Horizon 2 mining area <br />(see Map 2.04.7-1). Flow and water quality data were collected at these sites since July of 1986, <br />and are presented as Stream Gaging Report and Water Quality Reports presented in Peabody <br />Appendices 7-5 and 7-9, respectively. Monitoring of the site SW-N106 has been discontinued. <br />However, New Horizon Mine continues to monitor SW-N104 and SW-N105. <br />Surface water Site SW-N104 is located on the West Lateral, in the city limits of Nucla. <br />Instantaneous discharge measurements were made at SW-N 104 in the diversion spiitte box, and <br />continuous flow monitoring were conducted at this site via a stilling well and a digital water level <br />(Revised 6/28/01) 2.04.7-29 <br />