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Show Public Water Supply The majority of the people in the Central Valley obtain their water from wells. The quality is high except for a slight hardness, which is increasing slowly. Thirty-seven communities, including Sac- ramento, obtain their water either directly from the stream channels or from artificial reservoirs. Water quality is very high in the mountain streams but becomes progressively poorer toward the delta areas. Sacramento River water is so polluted by the time it reaches Sacramento that full treatment, in- cluding aeration, chemical coagulation, filtration, and chlorination, is necessary to make the water suitable for domestic use. In the delta area surface water is so heavily polluted that it is unsatisfactory for water supply purposes without special treatment. In addition to valley water supply demands, much of the water supply for the 2.5 million people of the San Francisco Bay area is obtained from the Tuolumne and Mokelumne Rivers of the San Joa- quin drainage. Aqueducts 150 and 250 miles long serve the East Bay cities and San Francisco. The supplies are presently almost completely utilized. The Bureau of Reclamation estimated in 1945 that only about 5 percent of the total available natural water supply of the valley will be needed for municipal and industrial use-1 million acre- feet. Exports to the San Francisco Bay region will be 450,000 acre-feet annually and use in the Central Valley itself will be 550,000 acre-feet annually. Present estimates indicate that the bay area require- ments will be substantially greater than these 1945 data. Increasing pollution of the streams, and conflicts in the use of the catchment watersheds, endanger domestic and industrial water supplies. Two projects authorized or under construction have pul>lic water supply as a major feature. The Contra Costa Canal unit of the Central Valley Project carries water from the delta for domestic, industrial^ and irrigation use along the south shore of Suisun. Bay from Antioch to Martinez. Munici- pal and industrial demands have taken the greater part of this supply, and are expected to predominate in the future. Additional demands upon the Contra Costa Canal are for the industrial requirements of Rich- mond and other communities. This situation now is under s tudy by the Bureau of Reclamation. Also under study is the use of Central Valley water in the Santa Clara area where quantity and quality, sur- face and underground, have been deteriorating. The authorized Solano Project will provide supple- mental water for the municipal supply of cities in Solano County, principally Vallejo, and also will furnish a water supply for military installations in the area. The Folsom Project, now under con- struction, also is expected to supply water for munic- ipal and industrial purposes. Flood Protection The Present Situation Extensive flooding of the lower parts of the Sacra- mento and San Joaquin Valleys is a natural occur- rence. As settlement spread over the Central Valley, damages from floods steadily increased, with a concomitant demand for flood protection. By 1917 a comprehensive flood control plan for the Sacramento River had been adopted. With no flood protection it is estimated by the Corps of Engineers that damages would average 25 million dollars annually. Flood protection works already constructed are estimated to prevent 10 mil- lion dollars' worth of flood damage annually. Major flood damage (15 million dollars annually) still occurs. The principal works of the Sacramento Valley flood control project are levees and channel im- provements along the Sacramento River; along the lower reaches of the American, Bear, Yuba, and Feather Rivers, Cache and Putah Creeks, Willow Slough, and many of the minor tributaries above Colusa; the Moulton, Colusa, Tisdale, Fremont, and Sacramento overflow weirs; and the Sutter and Yolo bypasses. With the exception of some en- largement and extension of the Sacramento River levees and construction of levees on minor tribu- taries, the project works have been completed and have operated to provide flood protection for many years. When operated in conjunction with the existing and proposed storage units (including Shasta Reser- voir) the flood control program will provide a high degree of protection to about 800,000 acres of fer- tile agricultural lands and to the major cities, in- cluding Sacramento, Marysville-Yuba City, and Colusa, as well as many smaller communities, and to transportation facilities. Fewer measures have been undertaken to provide flood protection for the San Joaquin Valley. Four flood control reservoirs have been completed in the 100 |
