Economic Significance of Water Supply

Attachment No. 2, Lower Colorado River Basin Project, Economic Significance of Water Supply for Homes, Industry, Agriculture, page 9WATER SUPPLY AND DEMAND IN THE COLORADO RIVER BASIN The Colorado River Basin is one of the most extensive basins in the United States and the dryest. The waters available in the river system have been highly developed for agriculture, municipal and industrial uses, both within the basin itself and by extensive transbasin diversion projects that do now, or in the immediate future will, carry Colorado River water into six different river basins or drainage areas of the United States. The waters of the Colorado River system were divided between the upper basin and the lower basin by compact in 1922. The point of division between the upper and lower basins was established at Lee Ferry on the Colorado River 1 mile downstream from the mouth of the Paria River. The waters of the Gila River, a lower basin tributary, are now fully used. The Supreme Court decree of 1964 settled the relative entitlements of Arizona, California, and Nevada for use of water from the mainstream of the Colorado River. The proposed project will enable Arizona to put to use additional waters of the Colorado River within its entitlement as confirmed by the Supreme Court decree. The participating projects of the upper basin are moving forward and increasing their use of water. The municipal and industrial potential of the area, especially mineral production, could drastically change the estimate of the future water requirement and its timetable of use. The need of the upper basin for more water than is now available could come as early as 20 or 30 years from now. Southern California is close to the limits of its present water supplies. The California Water Project, now under construction, will take care of its needs for perhaps another 25 years. However, sometime in the 1990's an additional supply will have to be found to meet the demands of the increasing population and industrial expansion. Arizona now has a more severe and a more immediate water supply problem than the other two areas. The tributary flows within Arizona are essentially developed and used. The balance of the water to meet the historical demand has come from an overdraft of the available groundwater reserves. The construction of facilities to bring Colorado River water into the primary water using section of the State can only partially offset this overdraft but will provide time to develop plans for the next increment of water supply to satisfy the growing demand. It is economically infeasible for agriculture to expand without additional water sources. However, a major long-term objective is to arrest the groundwater overdraft and sustain agriculture at its present level. The Lower Colorado River Basin Project, with the Central Arizona Unit proposed for early construction, will help alleviate the present critical situation and enable Arizona to survive until a means can be developed to secure additional water to satisfy the Region's long-range needs.Epson Perfection 4870 Photo, 400 dpi, 8 bit, 1,656,019 byte