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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 domestic 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.
About one-half of the habitable area of the county of Los Angeles, or metropolitan area, is now within the boundaries of incorporated cities. It may conservatively be assumed thåt the next 25 to 30 years will see the absorption of the entire area within municipal boundaries with an increase in population to a total of 3,270,000. This will increase the need of water from a present use of 466,000 acre-feet to an estimated requirement of 1,359,000 acre-feet per annum for domestic purposes. For the other four counties it is assumed that the urban population will increase at the rate established from 1910 to 1925 and which is considerably less than the rate from 1915 to 1925, or that of the past five years. The total population would thus increase from about 400,000 in 1925 to about 750,000 in 1950, which estimate is considered as conservative, and the urban population from about 216,000 in 1920 to 600,000 in 1950. The use of water over the entire valley of Southern California is estimated for 1950 at 2,013,000 acre-feet, which is 916,950 acre-feet less than the available supply. The deficit is equivalent to 1,150 second-feet constant flow, required for domestic purposes.
The valley of southern California is surrounded on three sides by deserts, whose water supply, if there be any, is entirely inadequate to take care of even a fraction of their irrigable lands.
The interests of southern California require steps to be taken at once to obtain from the Colorado River 1,500 second-feet of water for domestic purposes only. This, and this alone, will prevent serious shrinkage in the use of land in this area for agricultural purposes.
The acquisition of this amount of water for domestic purposes, on the other hand, does not contemplate any material increase in the present irrigable area. Unless such a supply is secured, or, looking into the future, definitely provided for, southern California must look to a further adjustment in the economic balance between the utilization of land for agricultural and for urban and suburban uses. This spells loss of protection of wealth and a shrinkage of population.
Îhe CHAIRMAX. Thank you, Mr. Sonderegger.
TABLE No. 1,--Valley of southern California--Population records
1900, United States Census.
936, 438 1, 425,000 1, 900, 000 2,750,000 3, 260,000 3,650,000
27, 929 56, 706 73, 401 85, 000 95,000 116, 000 135, 000 155,000
17,897 34, 696 50, 297 65, 000 74, 000 92, 000 110,000 128, 000
19, 696 34, 436 61, 375 100,000 122, 000 166, 000 210,000 254, 000
35, 090 61, 665 112, 248 150,000 180,000 240, 000 300,000 360, 000
691, 634 1, 133, 759 1.825, 000 2, 371, 000 3, 363, 000 4,015, 000 4,547,000
San Bernardino and Riverside Counties :
241,000) 170,000 89.000
Total water supply
1, 097, 000
TABLE No. 1.--Seasonal use of water, in acre-feet, 19.25
Los Angeles County:
Domestic, city of Los Angeles, 1,000,000, at 112 gallons per
40, 320 300,000
1 Report by board of engineers to city of Los Angeles, August, 1924.
San Bernardino County :
Domestic, urban, 50,000 inhabitants, at 120 gallons per capita ---
6, 720 140,000
Riverside County :
Domestic, urban, 40,000 inhabitants, at 120 gallons per capita---
acres, Coachella Valley, and 35,000 acres, Palo Verde project-
Orange county :
Domestic, urban, 60,000 inhabitants, at 120 gallons per capita--
8, 070 168,000
San Diego County:
Domestic, urban, 140,000 inhabitants, at 120 gallons per capita -
18, 820 62,500
962, 250 1,097, 000
134, 750 TABLE No. 7.--Acre-feet water requirements in 1950 Los Angeles County (metropolitan area):
Estimated population within present city limits of Los Angeles. 2, 180, 000 Entire metropolitan area
3, 270, 000
Domestic use for that portion of the metropolitan area where the
Acre-feet 386, 000 150, 000 823, 000
Total, Los Angeles County---
1, 359, 000
Domestic needs (number of inhabitants, at 130 gallons per day) :
100, 000) Riverside County-
80,000 Orange County
160, 000 San Diego County
580, 000 Industrial development (estimated at 100 second-feet) Irrigation needs :
San Bernardino County (110,000 population, at 1.40 acre-feet,
* Los Angeles city report.