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acceptance of such an alternative is unlikely, Preliminary study of this proposal showed costs to exceed benefits and further evaluations were not made. Two alternative plans were evaluated. The first plan, Alternative 1, minimizes structural works. The second plan, Alternative 2, includes improving off-farm conveyance systems and onfarm systems, maximizes irrigation efficiency and salt load reduction. This latter plan is the designated environmental quality plan and provides the greatest reduction in salt loading. Net economic benefits are largely derived from reduced salinity, This results in the "Environmental Quality Plan" yielding the highest net benefits; therefore, Alternative 2 is also identified as the "Economic Development Plan," The alternatives are evaluated for a 25- year project life at seven and three-eights (7-3/8) percent interest after a ten year installation period. The major practice in both alternative plans is improved onfarm irri- gation water management. Off-farm conveyance system improvement needs and proposed solutions were identified by the SCS and Clark County Con- servation District in August 1978 and are used in this study. The alternatives consider fish and wildlife resources. Assessment of fish, wildlife and recreation resources are located in the environmental appendices, The impact on the visual resource and its quality was also considered. Unlined irrigation ditches presently provide some wildlife habitat. Changes in irrigation management will result in minimal habitat disturbance, " ,,_., , Other nonreturn flow and concentrated return flow uses of water from irrigated lands were examined. Water not used for irrigation could be used to develop additional wildlife habitat. However, water not used for irrigation is subject to the applicable state water law prior to utilization for additional wildlife habitat, '<i; The proposed onfarm irrigation water management program would not result in land modification below plow depth and, therefore, will not affect cultural resources beyond present agricultural activity. Future Without Salinity Pro~ram (t The future without program for salinity control is based on pro- jected (35-year) changes without implementation of a salinity control program, Projected land use changes from agricultural to urban uses is 160 acres. Some 32 acres are estimated for building lots and the remainder for use as small pastures, lawns and gardens. Irrigated land considered for this alternative is 3,495 acres distributed as follows: 72 percent alfalfa, 26 percent pasture, and 2 percent small grain, No changes in production levels or in onfarm irri- ation systems would result from ongoing conservation programs, It is assumed the ongoing program will be adequate to replace and maintain irrigation systems at their present level, 41 (' {J GI ., ,'~ 0 -' '-" "-, \.'