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SUMMARY (Continued) N ~ Alternatives ~ ~) two viable alternatives (A and B) plus a no-action alternative for Stage Two development were considered. Alternatives A and B met the crite~ia of four tests (completeness, effectiveness, efficiency, and accep~ability) used to identify viable plans that would meet the goals of th~ salinity control program and Bureau of Reclamation and Department of the Interior guidelines. From these alternatives, alternative B was selectied as the recommended plan of development. , , ~ ~uring the planning process, a number of other salinity reduction conce~ts and altern~tives were studied but were dropped from further "on- sider~tion because they failed to pass one or more of the tests. These alterriatives included the concept of reducing salinity by combining exist~ng canal systems into fewer and more efficient facilities, the concent of installing barrier cutoff walls along canal embankments, and thea4.dition of nine canal lining increments to alternatives' A and B.. OptiOr!s for combining systems were dropped from c'Onsideration because of concetlns of the water users about potential administrativeaIld water right /problems and potential problems related to additional government invol~ement. The concept of installing barrier cutoff walls was dropped becau~e the technique was unproven and its effectiveness in reducing canal ,seepage was questionable. The additional increments to alterna- 0 tives !A and B ,were dropped because of their relatively poor cost ,effec- , tiveness. Recommended plan (alternative B) ~he recommended plan would entail membrane lining three reaches of the Government Highline Canal and replacing existing open earth laterals with buried pipe laterals. 'Ilhe canal improvements would consist of membrane lining approxi- matel~ 38 miles of the 47-mile section of the Government Highline Canal from p!alisade to the canal's terminus, 6 miles northwest 'Of Mack.lJBe- cause lof its small capacity, the last mile of the canal would be placed in pi~e. One segment of the canal was recently concrete lined under Stage jOne. A mile-long siphon under East Salt Creek would not be re- place~. The membrane lining would be 20-mil polyvinyl chloride, cov~red with 14 to 19 inches of earth and gravel for all canal capacities. Major iexisting structures along the canal, including siphons, flumes, and bGidges, would be subjected to a structural and hydraulic evaluation and w$uld be replaced if necessary. All turnout structures would' be replaqed, and several new wasteway and centerline check structures would 1 , 'I .~ r , l t )jThe first 6 miles of the canal from the Grand Valley Diversion Dam to; Palisade were excluded because ,the canal traverses the Mesa Verde Forma~on, a much less saline formation than the Mancos Formation; be- cause Jof the large capacity of the canal, it would be too expensive to line. :~ '; t~ I i S-2 ',;