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f"J ' C, c, ., J( I.J J. - 3 - for subsurface drainage works in sreas requiring such drainage. Practice 4. The Soil Conservation Service reports 9~ of the irrigators using some form of recovery system. It may be that not all fields of the reported 9% have reuse systems. The systems may be a ~anually operated type or the very recent innovation, the auto- matic irrigation and reusa system. Practice 4 permits use of the maximum non-erosive stream, reduces labor and applies water to the soil efficiently. The automatic system involves extra capital out- lay, but may ultimately result in more profitable use of the irri- gators time for other production enterprises. In effect, practice 4 trades capital for labor while reducing irrigation runoff to zero. I'fuen the economics of a particular form do not justify such a system, community or neighborhood cooperative systems of water re- covery could be considered. It appears that recovery systems for irrigation water runoff and in particular reuse syste~s offer the possibility of substan- tial water savings. Considering past experience and without im- posed controls, (limitatio~s of runoff or other measures) it is pro- bable that it will take 7-10 years before one-half of the present acreage will be serviced by recovery or reuse systems. B. Runoff Losses - sprinkler irrigation Sprinkler systems are estimated to number about 500 in the Big Blue Basin and 125 in the Little Elue Basin. No record of the acre- age by sprinkler system is available. However, many sprinkler sys- tems are used in conjunction with surface systems. If 40 acres is arbitrarily assigned per sprinkler systeM there would be 25,000 acres irrigated by this method. Sprinkler irrigation runoff should be below the 5~ level if they are properly designed and orerated. Design in the Big Bln~ Basin is ge~erally adequate with a few designs erring on the side of high application rates. Survey data on runoff are not available and probably would be i~accurate if available, because of var~ation in soil, slope and crop conditions at various times of the year. Observation indicates a generally satisfactory situation. There is a need for more education concerning correct water application rates for sprinkler operation. Educational programs should be dir- ected at users and also retailers of equipment. C. Evaporation Losses ~vaporation losses are incurred through spraying of water, transporting by lined or unlined ditches and from soil and water surfaces. Evaporation ~ay vary frOM 5 to 25% of the applied water depending on the method of irrigation. air temperatures, wind, the length of application period, crop canopy and humidity. Irrigation by pipe systems are a means of reducing evaporation from free water surfaces. A large number of pipe conveyance syste/'~3 are in evidence in the Plue River Basln. It is anticir~ted that tr,Q use of closed conduit systems to t~e point of field usa will in- crease with an increasing trend toward underground piping systems and the use of gated pipe. Acceptance of gated pipe systems remai~;