OCR Text |
Show inadequate to meet long-range needs. If large scale modification becomes operational, it could reduce, but not replace, the need for importation. Importation of surface water from areas of surplus could be one alternative for meeting the water supply deficiency of the Region, as well as that of the remainder of the Pacific Southwest area. Both pri- vate and public entities have made various proposals for studies of long-distance water transfers from areas of surplus, such as Canada and the Pacific Northwest. However, legislative constraints and the guide- lines for framework studies preclude consideration of this alternative at this time. More specifically, the Secretary of the Interior is pro- hibited under Title II of the Colorado River Basin Project Act of September 30, 1968, for a period of 10 years from the date of the Act, from undertaking studies of any plan for the importation of water into the Colorado River Basin from any natural river drainage basin lying outside the States of Arizona, California, Colorado, New Mexico, and those portions of Nevada, Utah, and Wyoming that are outside the natural drainage basin of the Colorado River. The desalting of sea water remains as the one available source for large scale water importation which may be considered in the Type I studies and for which general cost information is available. Therefore, desalting was considered the source of additional water for the Region and the basis for estimating the general magnitude of costs presented herein. A major factor in considering importation on a regional basis is that the water needs of the entire Pacific Southwest area should be coordinated into a comprehensive plan of which the Lower Colorado Region's augmentation needs would be an integral part. Exploration should also be made of the possibilities of exchanging desalted water for Colorado River water presently being conveyed to the coastal areas of southern California, thereby releasing Colorado River water for use within the basin. This would offer only limited augmentation as the quantities to be diverted after CAP is operational would not exceed 550,000 acre-feet. Future studies should be directed also toward the siting of major desalting facilities. For the purpose of the Type I studies, the following assumptions were made: (l) that desalting facilities would be located along the southern California coast; (2) that desalted water would be conveyed to Lake Mead: (3) that the 1906 to 1965 period of record defines the quantity of Colorado River water available; (k) that the initial importation to relieve the basin states of the Mexican Water Treaty burden would be a national obligation and would be implemented near the end of the 1981 to 2000 time frame; and (5) that augmentation water would include sufficient quantities so that ground-water over- draft would be greatly reduced by 2020. 97 |