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) Alternative 2 Alternative 2 would improve canals and/or replace with pipeline systems, and improve onfarm irrigation systems. Minimum deep percola- tion and increased irrigation efficiency would result. This alternative includes water management improvements of Alter- native 1 plus changing of set width& Maximum efficiency and minimum deep percolation are attained within many of the constraints of the pre- sent onfarm irrigation systems including: field dimensions (length and width), direction of flow, slope, irrigation head delivered to the farm, and crops grown. Urbanization, land use and precentages of crops grown are not assumed to differ from changes occurring without a salinity con- trol program. Changing field set widths would optimize unit stream flow for fields irrigated by the border method, About one-third of the existing borders would need reconstructIon. Reorganization and land leveling of fields would be compatible with recommended modification of the delivery systems, These water management measures will reduce seasonal gross application, and deep percolation below those of Alternative 1 and will be more effec- tive in salt load reduction. The irrigation efficiencies will vary, but. are expected to average 62 percent. Data for Alternative 2 is summarized in Table 8. The water required for leaching (leaching fraction) for the level of irrigation water management assumed in this alternative was calculated using the present salinity of the irrigation water, and considering potential yield reductions. The leaching requirement is satisfied by the deep percolation amount shown in Table 8. Leaching requirement yield reduction is offset by yield increases associated with higher irrigation efficiency, However, the net increase in crop production is not as great as that of Alternative 1, Incidental erosion (and sediment) control proposed in Alternative 1 is increased in Alternative 2, Accelerated assistance for wildlife wet- land habitat and wildlife upland habitat management proposed for Alter- native 1 is also applicable to Alternative 2. Riparian habitat enhanced by nondiverted surface flow (9,100 acre-feet) exceeds that of. Alternatve 1, Impacts on fish and other wildlife are addressed in Appendix A. Lining of unlined portions of the delivery system canals and lining of, or replacement of canals and onfarm ditches with pipeline, will reduce seepage. Riparian habitat lost due to lining or replacement of ditches with pipelines would be offset by improvement of upland habitat, Improvement of the water delivery canal system and improvement of onfarm systems and management are considered complementary components of this alternative and benefits are not separable. 45 0003~~