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delivered to water-deficient areas en route. Frenchman Dam has been completed. Construction of Oroville, San Luis and Antelope Valley Dams has begun. The initial construction contract has been awarded for the California Aqueduct. The year 1972 has been set as the date for the first delivery of water to southern California. While an aqueduct achieves direct water transfer, another variation could be through the concept of water exchanges, whereby waters of one source are replaced with equivalent waters from another. This type of system can be extended to new water sources as the need arises. Future Water Supply-Demand Relationships The estimates of future main-stem Colorado River water supplies available to the Pacific Southwest region were based on the most critical drawdown period of Colorado River flows of record (1930-1963), combined with a liberal estimate of future Upper Basin depletions. It is estimated that present water requirements will increase from about 14.5 million acre-feet per year to about 17.0 million acre-feet per year by 1975, as shown on table 13. As indicated on table 16, it is estimated that the water supplies presently available to the Pacific Southwest may be increased from about 13.2 million acre-feet per year to about 16.0 million acre-feet per year by 1975. This anticipated increase in supply would result through completion of the filling of the upstream reservoirs of the Colorado River Storage Project, storage releases from Lake Mead, by the availability of import water into the southern California basin through the California Aqueduct and the Los Angeles Aqueduct, and by the salvage of water along the Colorado River between Davis Dam and the Mexican border. Although not shown on table 16, reduction of wastes to the sea through reclamation and water salvage programs, by lining conveyance and distribution systems, will increase these supplies. These added supplies will be to the benefit of users in local areas. On the basis of population projections and no increase in irrigated acreage, it is estimated that by accomplishment of present programs of the State of California and the city of Los Angeles for importing water from northern California to southern California, and through the proposed water salvage programs on the Colorado River, the estimated shortage would be about 1.1 million acre-feet per year by 1975. This imbalance would increase progressively in future years to almost 3.7 million acre-feet by the year 2000 as a result of the increasing water demands of the growing population and the decreasing water supply in the Colorado River resulting from progressively increasing depletions by the Upper Basin States. The estimated quantities of water available at and below Hoover Dam to the year 2000 are shown in table 16A. IV-10Epson Perfection 4870 Photo, 400 dpi, 8 bit, 14,082,048 byte