AZ vs. CA:12 California Exhibits, Vol. XII; Nos. 1350-1383; 1400-1446; 1501-1518; 1601-1603; 1701-1703

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[pp. 227-29] "How Water Is Consumed in Irrigation "In the processes of irrigation, water is diverted from the stream and applied to the land. A portion of that water is dissipated into the air by the evaporation from soil, pools, and plant surfaces. A second portion runs off the surface-waste water. A third portion goes into the ground; some is held in the soil by capillarity; some percolates beyond the root zone, and reappears in the stream; some goes deeper to replenish deep ground storage. A fourth portion is withdrawn from the root zone by plants and transpired in the processes of plant growth, of which a portion remains fixed in the tissues of the plant. "Of the waste and percolating water, some may collect in low areas, inducing luxuriant growths of weeds and acquatic plants; some evaporates from the standing waters in such areas. If the percolating water raises the water table permanently or seasonally into the root zone of native vegetation that vegetation transpires in increased quanta-ties and becomes more rank. The flora may even change to water-loving species. "Consumptive Use is a technical term used to designate the water lost annually from an area by plant usage and by evaporation from soil, plant, and water surfaces. As applied to a whole valley it is found by determining the total inflow, I; the precipitation on the valley floor, P; the outflow, including return water, R; and the change in ground storage, AG. The consumptive use, K, then becomes K=I+P+AG-R