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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />3688 <br /> <br />LOWER GUNNISON BASIN UNIT - COLORADO <br /> <br />The Lower' Gunnison Basin Unit--Stage I study area pertains <br />only to the Uncompahgre Valley in the vicinity of the towns and <br />counties of Montrose and Delta in west-central Colorado. The <br />area begins approximately 9 milcs above Montrose on the Uncom- <br />pahgre River and continues downstream (north) on either side <br />until the confluence with the Gunnison River. It is approxi-- <br />mately 14 miles wide at the lower end of the valley and is almost <br />equally divided by the river. The elevation of the irrigated <br />lands range from 6,400 feet above Montrose to 4,900 feet near <br />Delta. The Stage II study area, centered around Hotchkiss, is <br />not currently under study. <br /> <br />The lands involved in the Stage I study are centered on the <br />distribution system of the Uncompahgre Project. The entire pro- <br />ject has approximately 550 miles of canals and laterals with about <br />254 miles lying on the east side of the Uncompahgre River. The <br />system is maintained and operated by the Uncompahgre Valley Water <br />Users Association. <br /> <br />The annual salt loading from the study area is estimted at <br />360,000 tons. The salt load is derived from both on-farm and off- <br />farm sources and results in an increase of about 37 mg/L of total <br />dissolved solids at Imperial Dam. The major contributions are <br />from the seepage and leaching effect of unlined canals and irri- <br />gation return flow. <br /> <br />The current salinity control plan calls for lining all of <br />the canals and laterals on the east side of the river. This would <br />involve lining about 59 miles of canals, 195 miles of laterals <br />and the replacement of more than 2,000 structures. This program <br />would reduce the annual salt load by 140,500 tons and correspondingly <br />reduce the salinity concentration at Imperial Dam by 15.2 mg/L. <br />The estimated cost (July, 1981, prices) per mg/L of salinity reduc- <br />tion at Imperial Dam is $722,000. <br /> <br />The Regional Director's proposed feasibility report and draft <br />environmental impact statement was released in October, 1981. <br />Once the final environmental impact statement is completed/":the <br />Secretary of the Interior could forward his report to Congress for <br />authorization in 1984. Based on this schedule an~ the required <br />subsequent advance planning studies, the construction of these <br />facilities could begin in 1987. It is expected to be built in <br />stages and that it will take 9 years to complete. <br /> <br />(updated 11/20/81) <br /> <br />DS:cs <br /> <br />-21- <br /> <br />-, <br />