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38 WATER RESOURCES OF CALIFORNIA. of California’s arable lands. Appendix “ C,” ‘ ‘ Utilization of the Water Resources of California,” presents a general preliminary plan for obtaining the maximum use from the state’s waters and the control of floods. Appendix “ D ,” ‘ ‘ Relation of Settlement to Irrigation Development,” discusses colonization problems of irrigation projects. All this information, basic for a full conception of the potential value of the state’s water resources, its greatest possession, is briefly sum­marized in the chapters of this report. A general preliminary plan for achieving the greatest service from these waters, is presented as requested by the legislative enactment pro­viding for these investigations. This plan outlines a scheme of coor­dinated development whereby a maximum accomplishment may ulti­mately be obtained whose physical works for storing water would cost but slightly more than half as much as similar attainment under an uncoordinated plan. The canals for transporting this water to the regions of use are, many of them, very long and obtain water from several sources, pass through numerous communities, and could be made possible only through organization of large sections of the state. With­out such canals much of the state’s waters will go unused. Only then, through united endeavors, almost statewide in extent, can the maximum service be obtained from the state’s waters. The reservoirs involved in the maximum development o f the state’s waters are some 260 in number. These and twice as many more were examined by field parties in these investigations, and a selection made of a third of all the possible sites reported on-. Time did not allow, neither did the preliminary investigation warrant, a detailed examina­tion of dam sites. Before it is finally known that the selected sites are feasible, borings and exploration trenches must be made. The canals outlined on the map of the comprehensive plan, largely pass through territory of which adequate maps do not exist. Many surveys must be made before it may be ascertained that these canals are feasible and that they are in the most economical location. It is therefore recom­mended to your honorable body that funds be appropriated to pursue the study of the comprehensive 'plan in greasier detail tham has been possible for this report. It is also desired to call to your attention the value of records of the waters flowing in California streams. Because of the sporadic way in which the waters pass down the stream channels, reliable estimates of future expectancies can only be made from uninterrupted records of many years’ duration. The inventory of the state’s waters presented in this report has been based on an estimated fifty-year mean flow. This was accomplished by expanding records of measured run-off through comparison with precipitation records and, on many streams, the entire estimate of run-off was obtained by comparison. It is urgent that provision be made for the continuance of stream gaging records at least as extensive as in the past, and some increase be made in appro­priations for this work if possible. The construction of all the great hydraulic works on which the future wealth of this state depends, must be designed in accord with these records of stream flow. It is important that they be continuous and on all the streams. Lastly, the desirability of stimulating the rate of'ru ral settlement in California has been pointed out in this report. This subject is placed before you as one worthy of your attention. WATER RESOURCES OF CALIFORNIA. 19 CH APTER II. CALIFORNIA. California, second in area, but first among the states of the Union in value of natural resources, lies between the Great Basin of the North American continent and the Pacific Ocean. Confined on the north by Oregon and on the south by Mexico, it constitutes three-fifths of the western boundary of the United States. The six hundred and fifty miles of its meridional length extends to over nine hundred miles of seashore as the coast line pursues a diagonal and more tortuous course in delineating the headlands and coastal indentations of the Pacific littoral. Within the two hundred miles of California’s average width, there are 23,000,000 acres of agricultural lands disposed in parcels of various sizes and separated by mountains that occupy much of the intervening space. These agricultural areas are the flat and rolling lands of the state that have soils, disposed in appreciable areas of regular surface conformation, suitable for the production of harvestable crops. The grains, fruits, berries, grapes, vegetables and other farm produce for which California is famed, are grown on these lands. They are located on the valley floors, in the foothills and on the plateaus of the state. Included in the agricultural areas, are lands at present deficient in natural moisture, but more or less conveniently situated for the ultimate acquisition of an accessory water supply. Slightly over one-half of these agricultural areas were farmed in 1920. The non-agricultural regions of California, the mountains, are, for the most part, precipitous, rocky or soilless. Occupying three-fifths the area of the state, these upland regions are spacious collectors of precipitation that fill the stream channels with water, without which much of the state’s arable lands could never reveal their powers of production because of deficient soil-moisture. Although they are mostly non-tillable, nevertheless the mountainous regions have supplied the alluvial earth through glacial action, weathering or erosion, that their streams have conveyed to lower levels and deposited there to be­come the fertile, productive soils of the agricultural areas. California’s mountains are so disposed that their greater part is comprised within two ranges. These diverge in their southerly course at Mount Shasta within forty miles of the Oregon line, and leave be­tween their bases, the long flat valley that averages a quarter the breadth of the state and half its length. Girdling this valley in their southward course, these two mountain chains proceed in long sweeping curves to a convergence at Tehachapi Pass, three-quarters the way down the state from the north boundary. The encircling line of crests of these two ranges enclose within a rock wall, two-thirds of California’s agricultural lands. This wall is cleft to valley-floor level in but one