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Show PART VIII TECHNOLOGICAL ADVANCEMENTS known; the problem is to produce large quantities of fresh water at a cost that is competitive with that for water obtained from conventional sources. Recent investigations have indicated that in large plants (50 million gallons daily or more) the water cost would be around 30 cents per thousand gallons. That cost is competitive in some areas for domestic and industrial use but it is far beyond the economics of a supply for irrigation operations, where prices generally range from 5 to 10 cents per thousand gallons. Future cost reductions depend upon improving existing processes and design, finding better and cheaper materials for construction, obtaining further economies by building larger plants, and selling by-products in the form of heat, energy, and chemicals. The Bureau of Reclamation recently completed a report exploring the potential of augmenting the Colorado River by desalting sea water to establish the expected feasibility of such a plan. Plans were analyzed for dual-purpose plants located on the coast of southern California and the Gulf of California and relied upon projected techniques for combined nuclear-desalting and thermal-electric plants. The base plan called for staged plants with an annual capacity of 2 million acre-feet by year 2010. The Upper Colorado Region could benefit from coastal desalination plants by water exchanges in the river system. Evaporation Suppression Controversy exists concerning the ultimate benefits to be derived from evaporation-reduction operations. Work done by the Bureau of Reclamation and others during the past several years indicates that it may be feasible to increase the usable water supply by evaporation- reduction techniques under favorable conditions. However, technical problems exist and work continues on improving the methods for applying, maintaining, and evaluating the effectiveness of evaporation retardents on water surfaces. Various chemicals and compounds have been utilized in the form of solid chunks, flakes, finely-divided powders, molten sprays, solutions, and emulsions to form monomolecular films on water surfaces to retard evaporation. Each form has been found to have its advantages and its disadvantages, and none has proved to be a panacea for solving the myriad problems encountered in field applications, particularly that of maintaining a film on the water surface in the presence of wind or wave s. 32 |