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Show ment and utilization of the basin's limited water resources. Although full advantage seemingly has not been taken of this concept in the early stages of development, more recent developments and planning give full consideration to the possibilities for several-purpose structures and reservoirs. Not all sites are suitable for economical multiple- purpose use, and since additional developments are required for full basin development, single-purpose sites also must be considered in planning improve- ment. However, they must fit the requirements of highest social benefits, as well as being compatible with existing legal restrictions on water use. 12. Potential New Techniques of Water Supply The Problem Potential new techniques for developing water supply, and potential problems associated with their development. The Situation The Colorado River Basin is one of the most arid sections in the continental United States. With many unique natural attributes this extensive basin awaits that time when sufficient water is made available to utilize this vast area to its ultimate. An indication of the great needs are shown in the lower basin. There the present assured water sup- plies amount to 8.5 million acre-feet a year. A survey of lands which might be capable of irriga- tion if water were available indicates potential future demands in the basin of about 31.2 million acre-feet a year. In addition a large but undetermined amount can be used for industrial and domestic purposes. There are six possible methods of increasing water supply to meet these needs: (1) increasing effec- tiveness of consumptive use; (2) a more complete development of the river; (3) diversion of water from other river basins; (4) conversion of sea water; (5) creation of additional rainfall; and (6) use of reclaimed waste waters. As yet the river basin is far from its ultimate de- velopment. There will be need in the future for the use of all water from this river on arid lands. This is possible; it awaits only the decision and funds to make it an actuality. Even if all of the potential system is developed there will continue to be a deficiency of water. Therefore, supplemental sources of water supply need study if this basin is to attain its potential. One possibility within the basin itself is increasing runoff. Present runoff can be augmented by re- ducing water losses. Treatment of the dense mountain forest can result in decreasing snow evaporation and getting more snow melt water into the ground. Large amounts of water also can be saved for stream flow by a reduction in the con- sumptive use by nonuseful plants. Tamarisk, juniper, mesquite, and various range weeds all con- sume water that could profitably be used by more valuable plants. It is doubtful if adjoining river basins are in better position than the Colorado River to satisfy needs other than their own. Plans for five of the six adjoining basins include importation of Colorado River water. The present needs of these basins are so great that large and several small out-of- basin diversion projects have been built. Others have been proposed to use Colorado River water to satisfy demands of larger populations in adjoining basins. Far distant water sources, such as the Columbia and other Pacific coastal streams, with their ex- cesses of fresh water, are potential sources of water supply. The need or demand in the Colorado Basin is sufficient to warrant preliminary study of these sources. The sea has been classed as the "last water hole." It offers an unlimited source of water if salts can be removed and the treated water lifted to the de- sired points of application. Vast amounts of energy will be required. Among the potential sources of undeveloped power are atomic energy and solar energy. With new energy sources, the possibility of using sea water may become an actuality. In the lower basin, with its preponderance of clear days, the po- tentialities of solar energy are pronounced. There are three general methods of treating sea water for removal of salts: mechanical, chemical, and electrical. Research is being conducted on each of these methods and a bill was introduced in the Eighty-first Congress to increase funds for it. If salts can be successfully removed from sea water, there is also the possibility that similar salts can be removed from the Colorado River water. The salinity of the river as it picks up deleterious salts from eroding soils and washes the salt from irrigated lands so reduces the quality of the water as to decrease its value for irrigation. Methods of purifying the river water would greatly increase its usefulness. 443 |