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I I I w ...... ...... <::> Additionally, ontarm ImprOVements ~ill include concrete ditches with headgates and ports or notches, or pipelines and gated pipes with control valves that accommodate semiautomatic timing devices to shut off the flo~ of water at the prescribed lime. I Installation of semiautomatic liming devices for salinIty control, although encouraged by SCS, is optional, available to those who may want them, hut not required for all ....ho choose to participate in lhf> program. The third solution considered the effect of combining anfarm water management with lining of the onfarm ditches. undt.'r this third solution l""O levels of implementation ~ere examined. The minimum level a;sumes implementing baSIC improvements in existing irrigatIon systems and practices Suited to manual labor. The maximum level asswnes reorganization of existing systems, including making needed Improvements in a sufficient reach of the off-farm ""ater delivery system to assure proper operation of the onfarrn system, The maximum level also includes the option for designing the onfarrn improvements to accommodate the use of semiautomated timing devices to achieve a higher degree of precision in controlling the time of each irrigation set and to reduce the manual labor needed for irrigatJon. Cost f'stimates for concrete ditch lining sholo'n for each alternative plan include df'sign and construnion features needed to Io'ith- stand fre~zing action resulting from carrying ~inter water for livestock. Plan formulatIon included evaluation of the 26 ~atersheds for levels of improve- ment and t~~es of benefits to be derived. Alternative plans Werf' formulated under each level of improvement by ~rouping watersheds to emphasize two planning objectives: I. Maximize net benefits - onfarm and downstream. 2. Maximize salt load reduction. Alternatives ""ere formulated by <ldding treatment unti I net benefits approached Zero for each levf'l of treatment. Results of forrnul.Jting these alternative plans are sho~n in Tabl~ IV-I. The next step ~as to rank the alternative plans by increaSing order of total cost and to compare total cost ~ith salt load reduction, Off-Farm Lateral Iml'rO\,'ements. This liSDA study extended the concept of onfarm ditch lining to include improving the off-farm laterals that arf' outside of the Uncompahgre Project Area under study by the Bureau of ReclamatIon. Improvement of these off-LHm laterals 1,,:as considered in t....o parts. It is necessary that onfarm improvements include improving a sufficient length of the distribution laterals to assure proper operation of the onfarm system improvements. It ...'as estimated that 80 percent of the smdll laterals should be included as an integral part of the onfaem system improvements at the maximum level. The remaining 20 percent of the small laterals and all of thf' medium sized laterals are included in this discussion of off-farm laterals. Improvement of large canals in Delta County was not cost effectIve based on prelimlndry analysis of salt reduction benefits, hut is schedulf'd for further study by the Bureau of Reclamation under their planning for additional development of ~ater resources in the area. 1\'-)