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Collection of runoff water and the use of ta;lwater reuse pits increases efficiencies by reducing system losses. Sprinkler irrigation systems are the most efficient method for controlling water until it is released. After release, wind velocity, evaporation, travel speed (on continuous movement systems), and crop , residue on the fiel d will greatly affect overall system efficiency. Application rates can be adjusted to soil intake rates. With the proper application rate little runoff should result. It is important to recognize the upper limits of irrigation effi- ciencies for the particular farm in question. Soil intake rates vary fran one location to another within an individual field. Al so, water availability, economics, labor practices, and energy limitations have a definite effect on onfarm efficiencies. H;stor;cal Onfarm Efficiency Onfarm efficiencies vary greatly within the basin and from field to field within an individual farm. Onfarm efficiency for the Kansas- Bostw; ck I rr; gat; on 0; stri ct in Area I II ranges from 39 to 83 percent with an average of 61 percent (Bureau of Reclamation, 1974). The average onfarm efficiency, for the Frenchman Valley and H&RW Irrigation Oistr;cts in Area I for the 1967-1972 irrigation season, was 55 percent (Bureau of Reclamation, 1977). Onfann efficiency in Area II at the McCook study area on the Meeker-Driftwood Canal for the 1965-1969 period averaged 46 percent (Bureau of Reclamation, 1970). The Soil Conservation Service estimated 1975 onfarm efficiencies for Areas I and II to range from 50 to 58 percent. Area III onfarm efficiencies range from 50 to 63 percent (SCS, 1976). The onfann efficiencies for the study areas are all within the range suggested by the SCS. The present onfann efficiency fi gures used in thi s report for each of the three study a reas are: A rea I Area II Area I II 55 percent 55 percent 55 percent Attainable Efficiency Fran 1965-1969, the Bureau of Reclamation conducted a Water Use Study 6 mi 1 es southeast of McCook, Nebraska, near the Meeker-Dri ftwood Canal. The study was to detennine water use under current i,rrigation practices, and to identify sources of waste and water loss. From the study, it was determined that the fann operator can increase irrigation efficiency by knowing when to irrigate and the amount of irrigation water to be applied. Management practices that could be used to increase efficiency utilizing the existing irrigation systems with only small amounts of additional labor include: 1. Installation of resi stance blocks or tensiometers for deter- mination of soil moisture depletions. 15