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Show PART IV PUTURE DEMAND As the demand for water increases, the value of water will also in- crease and changes will be necessary in handling the available water. Many of the smaller irrigation companies, especially those which have duplicating and overlapping facilities, will need to be consolidated. This will lessen the total number of diversions in relation to the amount of land irrigated. Consolidation will also help to increase the overall irrigation system efficiencies. The development of new land and water supplies will require additional diversions; however, the number of di- versions will be proportionally less than compared with the amount of ir- rigated land under existing systems and facilities. Return flows Potentially irrigable lands are scattered throughout the subregions, much the same as presently irrigated areas. Since most water originates at higher elevations., return flows from irrigation systems in the upper areas will be reused by lower outlying areas. This process of using re- turn flows will generally be repeated many times before the water is even- tually consumed or returns to the stream below any possible use in the region. Crop consumptive use Many factors influence the amount of water consumed by irrigated crops. Included are climate, type of crop, plant growth characteristics, and water management. More detailed information on these factors is pre- sented in Part II of this appendix. For estimation purposes, the pro- jected rates of consumptive use by crops will remain essentially the same as those tabulated under present status (refer to Table 8, Part II). The most significant change will result from improved water management in those areas where an adequate water supply will be provided for the short supply lands. Adequacy of supply The supply of water in the region is adequate to meet the projected irrigation water requirements. This includes a full water supply for 587.k- million acres of new land and supplemental water for i-21,100 acres of presently irrigated land with varying degrees of short water supply. Even though the region's water supply is physically adequate to meet the irri- gation needs, many other constraints such as land ownership, political boundaries, water rights and compacts, water exports from the region, and the rapidly growing requirements for municipal and industrial supply and for outdoor recreation, including fish and wildlife, will need to be re- solved before projected development becomes a reality. Depletions Present on-site water depletions by irrigated land, related inciden- tal use, and irrigation reservoir evaporation amount to about 2.128 72 |