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<br />24
<br />
<br />DEPLETION OF SURFACE WATER SUPPLIE.S
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<br />vided to serve the increased population. In one case, it was stated
<br />that these requirements would be equivalent to the average flow of
<br />Colorado River at Rifle, from which the erroneous conclusion was drawn
<br />that industrial development of the area would be throttled if any more
<br />water were diverted from the river for other purposes. The writer of
<br />this statement was actually referring to diversion requirements which
<br />.could be satisfied from storage reservoirs and no allowance was made
<br />for the very large proportion of the water diverted which would return
<br />to the stream system for satisfaction of Colorado's obligations to
<br />deliver water at Lee Ferry in common with the other upper basin
<br />States.
<br />Future depletions caused by industrial and domestic uses of water
<br />{lan best be determined from experience in major industrial centers in
<br />the West where the quantity of water produced for use is measured
<br />accurately and the quantity returned through sewerage systems is
<br />likewise known. .
<br />, In the 12-month period ending June 30, 1950, the total quantity of
<br />water produced for use in Los Angeles and the contiguous cities of
<br />Glendale, Burbank, Beverly Hills, and Santa Monica was 444,900
<br />acre-feet. The outflow through the sewage-disposal plant which
<br />serves these 5 cities was 218,460 acre-feet in the same year, leaving
<br />226,440 acre-feet unaccounted for by measured return flow. The
<br />population of these cities, according to the 1950 census, was 2,245,264.
<br />The water unaccounted for was thus 1 acre-foot per year for each 10
<br />persons. The actual consumption of water was even less than that
<br />indicated because the San Fernando Valley portion of the city of
<br />Los Angeles, with a population of about 500,000, is largely'uDsewered,
<br />ahd the return from domestic uses in this area allgments the ground-
<br />water supplies from which a considerable part of the total water
<br />production is obtained.
<br />; Recently, a sewerage system was completed to serve the cities of
<br />Alameda, Albany, Berkeley, Emeryville, Oakland, and Piedmont in
<br />the San Francisco Bay area. During the months of June and July
<br />1953, a total of 156,400 acre-feet of water was delivered by East Bay
<br />Municipal Utility District to consumers in these cities, and during
<br />the same months 111,700 acre-feet were discharged through the sewet
<br />system. The quantity of water unaccounted for was thus 44,700
<br />a~re-feet, which was 29 percent of the total production. . The gross
<br />annual requirements in the east bay area, including all industrial
<br />uses, are in the order of 1 acre-foot of water for each 5 persons, so that
<br />the unit consumption must be about 1 acre-foot of water per year for
<br />each 15 persons.
<br />Comparable consumptive uses of water were found to be character-
<br />istic of the area served by Denver. Records furnished by that city
<br />for the 5 years from 1946 to 1950, inclusive, showed an average
<br />diversion for municipal purposes of 107,000 acre-feet pel' year and
<br />returns through the sanitary sewers which averaged 68,000 acre-feet
<br />per year. This leaves 39,000 acre-feet per year as the apparent con"
<br />sl1mption of water. The average population during the 5 years was
<br />.about 460,000 persons,so that the rate of depletion was only 0.085
<br />acre-foot per year pel' capita, equivalent to about 12 persons pel' acre-
<br />foot of water per year.
<br />The east shore of Sll.n Francisco Bay is highly industrialized and so
<br />is I,os Angeles and the contiguous cities of Glendale and Bu:rbank.
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