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flows westerly passing just north of the town of Nucla and then flows northwestward passing <br />north of the New Horizon Mine 1. Diversion ditches distribute water to mainly agricultural users <br />in the area. Since the completion of the irrigation system for this area in about 1910, these areas <br />have been intensively reworked for irrigated agriculture. Additional uses include domestic, <br />municipal and stock pond consumption. <br />The New Horizon Mine 2 permit block is located just west of the town of Nucla in the mildly <br />sloping upland area between Tuttle Draw and Calamity Draw, approximately in the middle of <br />First Park. Especially in the Mine 2 mining area, the surface water system is characterized by a <br />"disjointed" tributary drainage system almost completely controlled by return flow ditches of the <br />local irrigation network. <br />West Lateral Irrigation Ditch - The West Lateral irrigation ditch is part of the Colorado <br />Co-operative Company's main ditch system that originates on the San Miguel River just <br />upstream of Cottonwood Canyon (about 12 miles upstream of Naturita). Construction of the <br />main ditch commenced in 1896, and water began flowing to the First Park area via the ditch in <br />the spring of 1904 (Mercer, 1967). The main ditch, as well as the main laterals, is basically an <br />unlined open channel excavated in shallow soils and sandstone. Where the ditch crosses <br />drainages, pipes and aqueducts have been constructed to carry the flow. The main ditch has an <br />average gravity run of four feet per mile from the San Miguel River to the First Park area <br />(Mercer, 1967). For a more historical discussion on the Colorado Co-operative Company's <br />development of the regional ditch system, the reader should refer to Section 2.04.3, Site <br />Description and Land Use Information. <br />The West Lateral splits off the main ditch near the northern boundary of the Nucla Townsite. <br />The West Lateral follows a ridge-top course westward from Nucla through the New Horizon <br />Mine 2 area to the main north-south county road (2700 Road), then winds south and southwest <br />until the conveyed irrigation water is used by the various shareholders located along the ditch's <br />course. A total of 18 diversions have been identified on this lateral; many consist of wooden <br />"splitter boxes" that divert a consistent proportion of the irrigation water from the lateral to fields <br />via small ditches and channels. Some diversions simply consist of pipes and hoses that also <br />route irrigation water to fields which are slightly lower in elevation. <br />The West Lateral irrigation ditch is an unlined open channel. Where the ditch courses along the <br />ridge top separating Tuttle Draw to the north and the Calamity Draw Valley to the south, the <br />ditch has been excavated through shallow soils into the highly fractured and weathered <br />sandstone. Over time, the ditch channel bottom has been subsequently scoured and eroded, <br />resulting in significant reaches of exposed and fractured sandstone. Further down the ditch <br />course, the ditch channel is constructed through deeper soils, and features a sandy channel <br />bottom. In most reaches, vegetation grows so heavily on the banks that the Colorado <br />Co-operative Company performs routine cutting and cleaning to ensure the integrity of the ditch <br />channel. Occasionally, where the ditch courses through the deeper soils, the ditch bottom is <br />periodically cleaned out (dredged). The overall gradient of the West Lateral irrigation ditch is <br />approximately .014 ft/ft. <br />10