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. the Division of Irrigation Engineering and Water Conservation and the Imperial Irrigation District, range from 69.5 inches hi 1952 to 75.2 inche s in 1948, with a mean of 71. 8 inche s. .. Estimates have been made of water consumption rates for most irrigated areas of the Colorado River Basin. These should be corre- lated and summarized in one report, with the few measurements available. Land use surveys to determine acreage of crops and native vegetation should be completed so that total consumptive use can be computed for each sub-basin. In order to comply with provisions Of the Colorado River Basin compacts between states, more research studies should be conducted, and measurements made of consumptive use of water by lysimeters, soil moistUre depletion and inflow-outflow methods. Evaporation stations should be established at proposedreser- voir sites. Since the w.ater supply in the Basin is limited, research is needed to improve irrigation practices and determine the most economical irrigation requirements. Studies should include measurements of irriga- tion efficiencies, quality of water, drainage and return waters from irrigation. * * * * * * * * * It ELIMINA TING WASTE IN mRIGA TION Frank J. Veihmeyer, Professor of Irrigation, U. of Calif. . Much can be done by individual water users to conserve water used in irrigation. The efficiency of irrigation, which is the difference between the amount of water applied t.o the land and that held in the soil within reach of plant roots, is surprisingly low in much of the West, in many areas not as high as 60%. The other forty percent or more is lost by evaporation, runoff at lower ends of fields, or percolation below the roots. Much of this waste can be eliminated by proper preparation of the land and by regulating lengths of run and widths of check to conform with sizes of stream available and with slopes and infiltration capacities of soil. . Spme loss is inevitable. Evaporation takes place each time water is applied, so long as the soil surface and plants are wet. This loss may amount to I inch of water for each application. Conveyance losses can be redu~ed by lining ditches and installing concrete pipe system.. Where topography, soil and crops are suitable, water may be conserved by sprinkle;r irrigation. However, sprinkling is not the answer to all water waste problems. In fact, most sprinkler systems are underdesigned for deep.-rooted crops, so that irrigations are required more frequently than in other surface methods, and the loss is accumulated. " Most trouble in irrigated agriculture is too much water rather than too little,. Excessive use of water is illustrated by a recent report of one of the best irrigation districts in California, which states that over 100,000 acre-feet were pumped for drainage. This district has ample water and -15-