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lG~8 2 METROPOLITAN WATER DISTHICT rapid development and wasteful use. Furthermore, the surface streams which formerly fed the subterranean iakes were utilized simultaneously with the development of subsurface supplies, with the result that the withdrawals from the underground reservoirs soon began to exceed the replenishment. This caused little concern at first because of the vast extent of the underground storage. It was natural that these water reserves should be overdrawn to build up a community which would later be able to go far afield for new supplies. This is just what has happened. Water reserves have been visibly diminishing for many years. The water being taken each year from local streams and under- ground basins is considerably in excess, over large areas, of the av- erage annual replacement from rainfall. Artesian welis have given wa)' to pumped wells and the latter in many cases have required deepening. Several basins have been nearly emptied and others have been drawn down to great depths. Many wells are now from 500 to 1,000 feet deep, involving hea,,)' cost for drilling, equipping, and operating. Along the coast, salt water is fiowing back into the emptied gravels, destroying valuable fresh water supplies. Obvious- iy this depletion of reserves cannot continue indefinitely withollt resulting in serious damage and great loss of property values at the next drought period to be experienced. Water f,'om outside sources Evidence of depletion of underground waters in many coastal basin areas is steadily accumulating, despite the fact that the City of Los Angeles has been importing an important supplemental sup- ply through its Owens River aqueduct since 1913. This supply has been of incalculable value to Los Angeles and indirectly to the basin as a whole, but it is entirely inadequate to supply the future needs of the basin. It is derived normaliy from surface sources on the east slopes of the Sierra Nevada mountains, and is reasonably de- pendable but not entirely unfailing. At times it must be supple- mented by pumping from the Owens Valiey gravels.. With the re- cent completion of the Mono Basin project, bringing that water into the Owens River drainage area, the dependability of the Los Angeles supply is measurably increased but it still will be subject to serious reduction during a protracted dry cycie common to both watershed areas. Repetition in this coastal basin, nnder its present- day population and industrial conditions, of the dry cycle which prevailed from 1893 to 1900, with an average rainfali of 9.82 inches per year, would cause great damage. ~ I ~ .1 I , I 1 ~ I I .I I