1905 



FORESTRY AND IRRIGATION 



383 



The minimum summer flow in the 

 Southern California streams, and it is 

 this minimum which controls irrigated 

 acreage, is in" round numbers 250 

 second feet. With high economy this 

 would be sufficient to irrigate 80,000 

 or 90,000 acres. Actually, 225,000 

 acres are under irrigation. This re- 

 sult has been accomplished by the utili- 

 zation of underground waters. These 

 subterranean sources now furnish sup- 

 plies for twice as much acreage as the 

 surface waters. They have certain 

 definite advantages over the surface 

 supplies, in that their quantity is com- 

 paratively uniform throughout the 

 year ; while surface streams are lowest 

 when the demand for water is great- 

 est. 



These waters which have become so 

 important in Southern California, dur- 

 ing the last decade especially are the 

 object of especial investigations now 

 under way. Their distribution has 

 been pretty well determined by the de- 

 velopments already carried out, but 

 their quantity and the limits of safe use 

 are not known. A series of observa- 

 tions is now being made whose object 

 is to determine whether these limits 

 have been reached in any particular 

 community. These measurements 

 have been conducted for nearly a year 

 and preliminary deductions may soon 

 be reached from them. Meanwhile, 

 reports are being issued in which the 

 results of studies of underground con- 

 ditions are given, artesian outlines and 

 changes in artesian areas are mapped, 

 depths to ground waters are shown, 

 the results of determinations of 

 alkalinity are given, and lists of wells, 

 with their costs and yields, are tabu- 

 lated. All of these accompany texts in 

 which the sources of the ground 

 waters are discussed and their quanti- 

 tative dependence upon rainfall on the 

 one hand and development on the 

 other, are brought out. It is hoped 

 that where a tendency exists to de- 

 velop underground waters beyond the 

 limits of safety, that tendency may be 

 checked by a clear statement of the 

 conditions. 



In certain portions of the desert 

 areas of Eastern and Southern Cali- 

 fornia, underground waters are known 

 to occur in some quantity. One of the 

 most important of these areas is that 

 centering about Indio, Coachella and 

 Walters, in the northwestern end of 

 the Colorado desert. Fifty years ago, 

 when this desert, 287 feet below sea- 

 level at its lowest point, was one of 

 the most dreaded spots in the arid 

 west, Prof. W. P. Blake predicted that 

 artesian waters would be found be- 

 neath its surface. In 1888 the South- 

 ern Pacific Company secured a small 

 artesian flow at Indio, and the pre- 

 diction made 35 years before was ful- 

 filled. Since 1900, when a method for 

 sinking deep wells rapidly and cheaply 

 was applied, developments in this 

 desert valley have been rapid. Its 

 unique climatic conditions, which 

 favor prolific growth and the early 

 maturity of many crops when water 

 can be applied to the soil, have given it 

 especial agricultural advantages which 

 are being utilized by its pioneer set- 

 tlers. 



Its growth depends entirely upon 

 the underground waters which are se- 

 cured from about 350 wells. The ma- 

 jority of these are artesian, and with 

 the waters which they yield 4,000 

 acres have already been brought under 

 cultivation. Cantiloupes, watermelons, 

 sweet potatoes, early table grapes and 

 hay and grain crops are successfully 

 grown, and the finer qualities of dates, 

 and citrus fruits are being tried. The 

 ground waters in this region, upon 

 which its agricultural existence and 

 continued growth depend, have been 

 carefully studied by the Survey and a 

 report upon them is now in course of 

 preparation. 



Down through the center of Cali- 

 fornia stretches the great Valley of the 

 Sacramento and San Joaquin Rivers. 

 It is 400 miles long and from 10 to' 50 

 in width, an empire in itself. From 

 south to north and from cast to west 

 it presents a wide range in humidity 

 from a rainfall of 8 inches annually to 

 one of 40 inches. The variety of prob- 



