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<br />r>~ <br />~ <br />.i~.. <br /> <br />.~.;..:1'.'. <br />~,,< <br />< <br /> <br /> <br />m.'.>.... <br />lo'. <br />(;~ <br /> <br />"1 <br />~) <br />tL; <br /> <br />,q <br />~:A <br />::-- ~:i <br /> <br />"" <br />; .~~ <br />F:} <br />d <br /> <br />f~ <br />('./>~,1 <br />~4 <br /> <br />.r{~ <br />ta <br /> <br />;;",'.0} <br /> <br />tJ <br /> <br />Pl <br />h~j <br /> <br />'}j <br /> <br />~~1 <br /> <br />CHAPTER II <br /> <br />PIAN FORMULATIOO <br /> <br />Hydrosalinity <br /> <br />Data collected by the SCS indicates that the total average annual salt <br />load of Oak Creek is approximately 4,800 tons per year. However, this data <br />also produced a total average annual salt load for Tongue Creek of 35,600 tons <br />per year which is only 78 percent of the 45,500 tons per year value calculated <br />by Reclamation using a base flow separation technique. <br /> <br />Therefore, the total average annual salt load value developed by the SCS <br />was adjusted proportionately to 6,100 tons per year to provide continuity in <br />the investigation. using the adjusted value results in an average Oak Creek <br />salt load of approximately 7.3 tons per acre-foot. Assuming an inflow TOS <br />concentration of 0.1 tons per acre-foot results in a net salt loading effect <br />of 7.2 tons per acre-foot. <br /> <br />Cost Effectiveness Analysis <br /> <br />A cost effectiveness analysis was conducted to determine if any of the <br />Oak Creek irrigation delivery systems presented cost effective salinity <br />control opportunities through implementation of a lining program. Cost <br />estimates were prepared for the Sandburg, Oak Creek No.1, Mountain View Mesa, <br />and Hoosier Ditches utilizing procedures similar to those described in the <br />Tongue Creek area. using the estimated annual cost of lining the individual <br />systems and a range of seepage rates (0.1 to 0.9 feet per day), corresponding <br />salt loading rates which would produce a cost effectiveness value of $lOO per <br />ton were calculated. A curve, representing the combination of seepage and <br />salt loading rates required to support a lining program with an annual cost <br />effectiveness of $100 per ton was developed. <br /> <br />Assuming that the maximum possible salt loading rate from ditch seepage <br />is equal to 7.2 tons per acre-foot, the corresponding seepage rate from the <br />curve is approximately 0.4 feet per day. Based on interviews with water users <br />and field observations, this value exceeds the seepage rates that could <br />reasonably be expected to occur in the Oak Creek drainage. <br /> <br />f.~ <br />~: Additionally, the future development of Delta's water rights in the area <br />,;j are not defined. Currently the city operates the irrigated lands under <br />short-term lease agreements with the water users; therefore, long-term <br />P irrigation of these lands is questionable. Based on the marginal cost <br />tf} effectiveness and uncertain future of land use practices, the Oak Creek <br />drainage was eliminated from further investigation. <br /> <br />(; <br />'::. ' <br />lo':.' <br /> <br />Special study area--canal and lateral lining/Winter water replacement <br /> <br />Area Description <br /> <br />The Special study Area (SSA) is located in the southeastern corner of <br />Delta County, and the drainages are tributary to the North Fork of the <br />Gunnison River. The drainage basins in the SSA include Alum Gulch, <br />Cottonwood Creek, and an unnamed gulch lying between them. The total drainage <br />area is approximately 22,000 acres which includes 6,600 acres of irrigated <br /> <br />10 <br /> <br />00r1936 <br />