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6. Support studies necessary for the satisfactory and orderly continuation of the above studies, including mapping, geology, water supply, regional economic, and others. Water Interchange Projects--Water interchange projects should be considered as a possible means of solving a portion of the long-range water supply needs of the Pacific Southwest. These interchanges may include conveyance of streamflows, frequently or occasionally surplus to the areas where they occur, to other areas for use either directly or through surface-or ground-water storage regulation. Possible desirable water interchanges in connection with the development of desalting plants also should be considered. For example, desalted water might be delivered from the nearby Gulf of California to Imperial Dam for dilution and distribution to existing projects. On an interchange basis, an equal quantity of water then could be diverted from upstream reservoirs and imported to areas of need. Tributary Projects--Throughout the five-State Lower Colorado River Basin area, there are potential tributary projects which heretofore have been undefined. With the increasing population, these tributary locations are beginning to feel the pressure of population growth, and the increasing demands for additional water. Planning studies are proposed to identify the water sources needed to satisfy existing and future demands. These tributary projects are located in the Virgin River Basin in Utah and Nevada, the Little Colorado, Gila River, and smaller basins draining directly to the Colorado River in Arizona and New Mexico, and the Inland Basin area of southern California. Future Desalting Projects--Sources of supply for meeting the increasing future water demands of the Pacific Southwest area must include full consideration of desalting saline and brackish waters available in the area. In addition to ocean water along the coast of California and in the Gulf of California, saline water is also present in the Salton Sea. Saline water will also be present in increasing quantities in other areas with the deterioration in quality of return flow water. Technological advances in the field of desalting offer promise of lower costs in the future through the use of both nuclear and conventional fuels. Continuing study of these possibilities is essential in formulating future plans for the Pacific Southwest Water Plan. Water Reclamation and Quality Control Projects--Future studies will be required to determine the feasibility of desalting nonreusable municipal and industrial wastes, and other brackish return flows from the Las Vegas, Nevada, area. At present, these wastes are allowed to discharge into Lake Mead, and in their present magnitude and quality do not constitute a serious overall deterioration of the quality of VI-14Epson Perfection 4870 Photo, 400 dpi, 8 bit