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Show CONSUMPTIVE USE OF WATEK IN IRRIGATION 1365 and reported by Ullrich (22). The average annual inflow of the river at Sevier, including the inflow of tributaries from Sevier to Gunnison, for this 7-year period was 295 000 acre-ft., and the average outflow was 211000 acre-ft., thus leaving 85 000 acre-ft. which was applied to 65 000 acres giving a consumptive use of 1.3 ft. The crop-year rainfall is approximately 0.3 ft. As the mean annual rainfall is only 0.7 ft., the draft by the crops on moisture stored in the soil from winter rains and from ground-water is probably not to exceed 0.3 ft., the quantity previously assumed in connection with the net-duty work. On this basis, therefore, the consumptive use, U, for the Sevier Valley, as herein denned, is 1.9 ft. This value of the consumptive use is much less than farm consumptive use as determined by the Utah Experiment Station for standard crops on a typical soil. If one-half the irrigated lands of the valley were in alfalfa and one-fourth in sugar-beets and potatoes, respectively, then farm consumptive use, accord ing to the values presented heretofore, would be 3.0 acre-ft. per acre. For crops thus distributed and 'for yields equal to those of the experimental farm it would mean either that farm percolation Df = 1.1 acre-ft. per acre, since Uf = U -\- Df (provided no water entered the valley through underground sources that could not be measured), or that 71500 acre-ft. percolated into the valley if Df = 0. In all probability the truth lies somewhere between these two extremes, meaning that some unmeasured water entered the valley and that some water was lost by deep percolation from the experimental plots, the sum of the two for the entire valley being approximately 71 500 acre-ft., provided the experimental farm yields were not much greater than those of the valley as a whole. Cache la Poudre Valley, Colorado.-The Cache la Poudre Valley, in Northern Colorado, is one of the foremost irrigated valleys of that State. Irrigation practice there is diversified, well-balanced as to crop rotation, and economic as to use of water. The need for water has raised water values and forced economy of use in irrigation. A 2-year investigation of irrigation in that area furnishes some valuable information on consumptive use. According to Hemphill the average consumptive use of river water, during the 2-year period of 1916-17, was 1.25 acre-ft. per acre over an area of 220 000 acres net. Adding 0.92 acre-ft. crop-season rainfall which is 80% of the 1.14 acre-ft. mean annual rainfall, gives a valley consumptive use of about 2.17 acre-ft. per acre. Data are not available concerning draft on soil moisture. Truckee River, Nevada.-In connection with duty-of-water studies on the Truckee Kiver, in Nevada, Harding (3) estimated the valley consumptive use by subtracting the valley outflow at Vista from the inflow at the California-Nevada line. He made estimates also based on direct measurement of drains and found fair agreement for seasonal consumptive use between the two methods. In making monthly comparisons by the two methods the results are less consistent. The gross area of cropped land considered was 27 000 acres, approximately three-fourths of which is cultivated land and the remainder largely wild hay land. The cultivated land produced mostly alfalfa, |