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Farming development in southern California depends solely upon the artificial application of water as distinct from rainfall. Since 75 per cent of our water supply is derived from underground sources, its development is expansive. Irrigation practice is the most economical in the world; there are practically no earth ditches, all water being conveyed in lined conduits or pipes. The cost of irrigation water ranges from $5 to $50 per acre foot and is particularly high in the choice frostless foothill sections.
High land values and expensive irrigation have forced the farmers to specialized agriculture and the selection of crops which bring a high price, such as citrous fruits, walnuts, fancy deciduous fruits for table use and canning, beans, beets, winter vegetable, and a multitude of semitropical fruits and crops which require special climatic conditions and intense cultivation.
Put in another way, economic conditions concerning the utilization of land in this area forced such extreme specialization, that the crops produced are not competitive with products of the soil from the rest of the United States. The United States census for 1919 shows a total irrigated area in the five counties of 572,000 acres and a crop value of $155,000,000, or a gross return of $270 per acre. The citrus crop of 1925 is estimated to bring about $60,000,000. We are a large market for staple food crops. We buy potatoes from Idaho, wheat from the North and East, corn from Iowa, apples and pears from Oregon, steers for fattening are brought from Arizona, New Mexico, Nevada, Utah, and Texas to the Imperial Valley.
The farming population of this prosperous country is in a class of its own; of the urban and suburban type that live well and maintain their connection with the metropolis by a system of first-class roads and up-to-date transportation facilities by rail, bus, and private auto, telephone, and radio. In the year 1924, there were 541,000 automobiles registered in Los Angeles County; one automobile for every 2.64 people. The growth of our back country began between 1900 and 1910, during which time Imperial and Coachell Valleys experienced a large influx of settlers. The Yuma Project was initiated about 1905 and was completed about 1908, while Palo Verde Valley was opened up about 1910.
The land under crop and the value of agricultural products raised in these tributary valleys is about as follows:
The contributory mining country of Arizona, Nevada, and Utah has an annual output of mineral products going into millions. Industrial development has kept pace with land settlement. We have to-day 5,500 manufacturing establishments of all kinds within the metropolitan area, employing 170,000 people. The United States
census shows the following value of manufactured products: 1899, $15,134,000; 1909, $68,586,000; 1919, $618,772,520; 1924 (C. of C.), $1,200,000,000. In 1923 the weekly pay roll was $6,234,377. The tonnage entered and cleared at Los Angeles Harbor was as follows: 1890, 158,766 tons; 1900, 253,855 tons; 1910, 1,709,294 tons; 1920, 4,210,176 tons; 1924, 22,214,137 tons. These are the fundamental factors and conditions which have brought about the rapid and steady growth of southern California.
Continued growth is conditioned upon the further development of the back country by the utilization of the irrigation supply and potential power of the Colorado River and further industrial and commercial development in the valley of southern California itself.
The possible additional irrigable area along the Colorado River is given in Senate Document 142, Sixty-seventh Congress, second session, as follows:
Total additional possible irrigable area: 978,000 acres.
An abundance of cheap power will induce the development of the great now dormant mineral wealth of Arizona, Utah, and Nevada, while industrial development in the valley of southern California has only just begun.
The water supply of the coastal belt of southern California is characterized by extreme irregularity. Practically all the rainfall occurs between December and April. It is irregular from day to day, from month to month, and from year to year. Records of seasonal rainfall date as far back as 1850. It has now been fairly well etsablished that there are cycles of wet and dry periods, periods of 10 to 12 years in which the average rainfall and stream flow are below normal followed by periods of the same duration in which they rise above normal. The difference in wetness and the resulting water crop is very marked. For Los Angeles and vicinity the
average water crop of a wet period is about three and one-half times that of a dry period, while in the eastern portion the proportion is about 21,2 to 1. The San Gabriel River in its driest year of record had a seasonal run-off of 10,000 acre-feet and in the wettest year a maximum of over 400,000 acre-feet. The average seasonal rainfall on the valley floor is about 16 inches, while for the mountains it averages about 3 feet. We are now in a dry period which began in 1916. The rainfall for the last three years has been about 50 per cent of the normal.
With these extreme fluctuations it is not practicable to utilize the average water supply of a cycle and it requires enormous storage to regulate the water supply so as to make at least a portion available during the latter years of a dry period of long duration. Surface storage reservoirs of such capacity are not available.
However, the coastal belt of southern California is naturally equipped with underground basins of colossal dimensions and capacity. They are "sunken basins" filled with materials brought down by the streams--sand, gravel, and clay, and capable of absorbing large volumes of water. In the natural order of things these basins are the recipient of portions of the stream flow as it traverses the valley and of seepage from the rainfall on the porous valley floors. It is this underground supply that has made possible the development of southern California ; in fact, it forms the very foundation of its prosperity; 75 per cent of the developed water supply is from underground sources. The largest of these underground basins underlies the coastal plain, which extends from Los Angeles about 20 miles south to Long Beach and southeasterly for about 40 miles to Santa Ana and Newport Beach. Similarly, the San Fernando Valley, San Gabriel Valley, and San Bernardino Valley have underlying deep basins suitable for storage in which water remains potable for an indefinite time and can be stored for long periods.
In order, therefore, to regulate the erratic water supply it is necessary to store the same in these underground basins, in which manner it is possible to utilize as much as 75 per cent of the supply. There are still unavoidable losses, such as evaporation and the escape of water underground into the Pacific Ocean. In years past there has been considerable flood waste amounting from 10 to 30 per cent of the water supply. Steps have been taken to salvage portions of this waste. Two years ago Los Angeles County voted à bond issue of $35,000,000 for conservation and flood control. This was eight years after the last capital flood which occurred in 1914. This bond issue was voted purely on the strength of the conservation feature. Two-thirds of the voters had never seen a heavy rain in this county, as they came subsequent to 1914. But they were much impressed with the effect of the dry years and the necessity of conserving the water supply.
The counties of Riverside, San Bernardino, and Orange, which are watered by the Santa Ana River, many years ago formed the conservation association for the conservation of flood water and lately have appointed a board of engineers to report on ways and means to effect the complete recovery of all flood waste. It is in
evitable that this will involve the expenditure of many millions of dollars.
The city of San Diego has already invested $16,000,000 in the construction of surface storage reservoirs on its principal rivers and is impounding about 140,000 acre-feet.
Despite all efforts of regulating the erratic water supply, it is the water crop of the dry periods which remains the controlling factor. About 21 years ago, at the end of the driest period of record, the city of Los Angeles found itself confronted by a water shortage, and as a result undertook the importation of a supplementary supply from Owens Valley. The city then had a population of 170,000 people, who burdened themselves with a bond issue of $25,000,000. It is this water supply that has made possible the phenomenal expansion of the city during the past 15 years, and which has carried us over the present dry periods. The present supply of the city of Los Angeles is 390,000 acre-feet and for the metropolitan area 594,000 acre-feet per annum. The available local supply of the entire coastal belt after the flood waste has been conserved will amount for a dry period to about 800,000 acre-feet per annum. Including the Los Angeles aqueduct, the supply is 1.100,000 acrefeet per annum. See attached Table No. 3.
The computations here presented are based principally upon the measurements of stream flow and ground-water fluctuations, which have been carried on by the United States Geological Survey since 1897. The water supply thus determined represents the safe yield that may be relied upon during a dry period.
On Table No. 4 we have indicated the present use in the various counties. From a comparison with Table No. 3, it is apparent that the supply has practically been exhausted in all counties except Los Angeles, where there is a surplus of 130,000 acre-feet available from the Los Angeles aqueduct.
This result is also borne out by a study of the water levels of the great underground basins. While these reservoirs are of a capacity capable of tiding over a series of dry years, nevertheless it is the recharge that constitutes the measure of the water supply and not the size of the reservoir.
Water levels have dropped in all basins, and in many at an alarming rate. The high-water mark of 1916 at the end of the last wet period was in the coastal plain considerably below the level which existed at the end of the preceding wet period. The Neff well at Anaheim, in Orange County, in the area replenished by the Santa Ina River, has dropped an average of 21/2 feet per year in the past 28 years. The Bouton well of the city of Long Beach is located in the coastal plain immediately north of the city. It is within the lower reaches of the San Gabriel and Los Angeles Rivers. The underground water, when the well was originally put down in the late nineties, was under sufficient pressure to rise 60 feet above the ground surface. Last summer the water level was 50 feet below the surface, a total drop of 110 feet. The artesian area of this coastal plain has shrunk from an original of 104,500 acres to 32,136 acres in 1923 and is still receding.
In certain parts of Riverside County water levels have receded to such depths as to make the cost of water prohibitive, and thousands of acres of land formerly irrigated have been abandoned and returned to a state of nature.
With the local water supply exhausted, a permanent increase in the irrigated crop is not possible. A recurrence of a wet period and an abundant visible stream flow will undoubtedly induce new development, which, however, can not be carried through a dry period. The prediction is made, that by 1950 the irrigated area will not have increased over 10 per cent of the present. One of the most serious features of the present water situation is the encroachment of the domestie needs on the agricultural supply. If carried on this would automatically stop the growth of any community, dependent as it is, upon its neighborhood agricultural development. The habitable but at present dry area in the valley, suitable for industrial as well as residential purposes, is very large and estimated at approximately 415,000 acres.
The use of water over large areas of irrigated land varies at present from 1.25 acre-feet per acre to about 2.25 acre-feet. With additional lands brought under irrigation, the available supply will fall short, which may induce less use at the expense of more intense tillage of soil. Such benefits, however, will be offset by greater use when the farming units become smaller. In San Fernando Valley the average duty of water over some 60,000 acres is 1.60 acre-feet, while for small poultry ranches it is 2.45 acre-feet. In the interior counties the use over large areas is in excess of 2 acre-feet. The duty of water allowed in our computations is the ideal duty fixed by the State Department of Engineering of California and is higher than the present use. For net duty we have made an allowance for 25 per cent of return water. The values herein used are therefore conservative.
The domestic use of the city of Los Angeles varies widely in different portions of the city, from as low as 45 gallons per capita per day to 496 gallons per capita per day and averages 112 gallons. Other cities have a larger rate of use and some increase must be anticipated for Los Angeles in the future. For our computation we have assumed a future use of 130 gallons per capita per day for those areas where the density of population is at least 14 persons per acre.
The effect of industrial use is estimated to increase the use of water 2.5 acre-feet per acre as more and different kinds of industries are established. The past 10 years have witnessed a persistent invasion of habitable hills by home seekers. The increased cost of water is here offset by a lower use brought about by the steep slopes.
An exhaustive study and estimate of the future requirements of the metropolitan area of Los Angeles by a board of engineers in August, 1924, has been made public in a report. The trend of growth of the city of Los Angeles was found to correspond closely to that of Chicago for the same population, which is more rapid than New York and about twice the rate of Philadelphia. By 1950 the city is estimated to have a population of 2,180,000.