Irrigation in California. 279 



irrigation is also practiced or is being introduced, and these are 

 on a par with the districts of San Diego county, in the matter of 

 rank as irrigation regions. East of the Sierra Nevada, and at 

 their base, lies the Owen's river country, an area suitable for 

 irrigation, where irrigation is necessary and where it is being 

 introduced. Upon the great Mojave desert and the Colorado 

 desert, there is at present no irrigation. The water supply is 

 very scanty. This is an irrigation region of the future, but it is 

 not regarded by Californians as a practicable one at present. 



With this general idea of the State, we will now look at the 

 rainfall and water supply. The State contains 157,440 square 

 miles of territory, of which 17,747 di-ain into the ocean north of 

 the Golden Gate, 21,665 drain into the ocean south of the Golden 

 Gate, 55,942 drain into the interior basins, and 62,086 drain out 

 at the Golden Gate. Of this territory which drains out by the 

 Golden Gate, 26,187 square miles comprise the Sacramento valley, 

 31,895 square miles the San Joaquin valley, and 4,004 the country 

 draining directly to the bays, making the 62,086 given above as 

 the whole area. 



The necessity for irrigation in California, and the relative 

 necessity in different parts of the State, are shown by the distri- 

 bution of rainfall. The San Joaquin valley has an average of 

 less than 10 inches of rainfall, the Sacramento has an average of 

 between 10 and 20 inches. The great deserts of the Mojave and 

 Colorado have an average of less than 10 inches, and in certain 

 localities only 3 to 6 inches. The Salinas valley, a small portion 

 of the coast above Los Angeles, and a portion of the interior 

 valley of the south, have also an average of less than 10 inches. 



So, we may say, that the great irrigation regions of California 

 have average amounts of rainfall varying from about 6 up to 20, 

 but generally less than 10 inches. This rain is distributed in four 

 or five months of each year, with some slight showers in one or 

 two months other than these ; the remainder of the year being 

 absolutely dry, with no rainfall whatever. Hence, you will see 

 at once, the necessity for the artificial application of water in 

 California. In the older countries of Europe, where irrigation 

 has been practiced for centuries, for instance, in Spain, where 

 water is used more extensively than in California, the annual 

 mean rainfall ranges between 10 and 25 inches. In the irriga- 

 tion regions of France, the mean rainfall ranges from 10 to 40 

 inches ; in the irrigation regions of Italy, the rainfall is between 



