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<br />SUMMARY <br /> <br />The Regional Director's proposed feasibility report for the McElmo <br />Creek Unit of the Colorado River Water Quality Improvement Program is <br />scheduled for completion in 1983. Until then, this status report will <br />inform concerned interests of the costs and the salt reductions asso- <br />ciated with the alternatives currently being considered. <br /> <br />The McElmo Creek Unit investigation in southwestern Colorado was <br />authorized by Public Laws 93-320 and 96-375 to determine the most cost- <br />effectiv~/ way to reduce the 115,000 tons of salt entering the San Juan <br />River annually from the McElmo Creek drainage. The San Juan River, in <br />turn, flows into the Colorado River. As a result of salt loading in the <br />McElmo Creek drainage, salinity increases at Imperial Dam by about 12 <br />milligrams per liter (mg/L). <br /> <br />Most of the Montezuma Valley Irrigation Company (MVI) facilities <br />were constructed before 1900, and much of the system was cut directly <br />into the saline soils and rock. Conveyance system seepage from the <br />unlined canals picks up salts from these soils and discharges it into <br />McElmo Creek and, eventually, the Colorado River. The Soil Conservation <br />Service (SCS), an agency of the Department of Agriculture (USDA), is <br />conducting an on-farm program for salinity reduction, while the Bureau of <br />Reclamation is involved in the off-farm salinity control efforts. <br /> <br />Following initiation of the study in December 1976, a public involve- <br />ment program aided in developing and evaluating a number of alternatives. <br />From these potential alternatives, candidate plans were selected for future <br />study. <br /> <br />The preferred plan consists of combining the Rocky Ford Ditch into the <br />Highline Ditch and concrete-lining 34 miles of high and moderate seepage <br />canals in the remainder of the MVI system. Two other alternatives consist <br />of concrete-lining 39 miles of high and moderate seepage canals in the MVI <br />system or placing portions of the system in pipe. Cost effectiveness of <br />these plans has been based on a 50-year analysis since it is estimated <br />that the canal lining will have a 50-year life. The current (fiscal year <br />1981) planning interest rate of 7.375 percent was used in the analysis. <br /> <br />The preferred plan would have a total construction cost of $34,100,000 <br />and a reduction in the salinity level at Imperial Dam of 6.1 mg/L at a <br /> <br />1/ Cost effectiveness as it is used in this report is the cost per <br />mg/L ;eduction in salt concentration at Imperial Dam. The Bureau of <br />Reclamation is attempting through its salinity studies to determine which <br />of the units of the Colorado River Water Quality Improvement Program <br />(CRWQIP) have the greatest potential for salt concentration removal for the <br />least amount of money expended. <br /> <br />[('11.18 <br />. .:1... <br />