372 



THE IREIGATION AGE. 



cause the water had to be raised from depths ranging 

 from 22 to 140 feet, at an average cost of $4.38 per 

 acre-foot. 



The most complete data regarding the duty of water 

 in California relate to the Gage Canal system at Kiver- 

 side. Records have been kept for the Office of Experi- 

 ment Stations on this system for six years, beginning 

 in 1898. The depth of water used has been exceedingly 

 uniform, ranging from 2.62 feet to 2.93 feet and averag- 

 ing 2.74 feet, all of the figures including the light rain- 

 fall of the Riverside district. These figures should be 

 applicable to nearly all of the region devoted to citrus 

 fruits south of the Tehachapi. There the orange and 

 lemon orchards are irrigated every month in the year, 

 although in winter the irrigation requirements fall off 

 because of rainfall, as well as because of decreased evap- 

 oration from the soil and decreased transpiration from 

 the trees. Other records are available for Southern Cali- 

 fornia, although not exclusively for citrus fruits. The 

 best available data for the region around San Diego, 



at the average rate of 5.42 acre-feet per acre, which in- 

 eluded a light rainfall, but made no allowance for seep- 

 age losses. Coming north, most of the data available do 

 not show any widely different use. Measurements, some- 

 what incomplete, under five ditches on Tule River, show 

 an average depth of water used, including rainfall and 

 allowing for seepage losses, of 2.75 feet. Under four 

 important ditches in Santa Clara Valley the total depth 

 received by the land in 1904 was 3.09 feet. On the 

 other hand, 3,250 acres in Modesto and Turlock district* 

 received in 1904 an average depth of 7.69 feet. It 

 should be added, however, that the land in Modesto and 

 Turlock districts was newly irrigated, and that the irri- 

 gators were mostly getting their first experience in the 

 use of water. 



Ten years ago it was not at all uncommon for engi- 

 neers to plan and construct canals on the theory that a)J 

 necessary precaution would be observed if the canals 

 were made large enough to carry water at the rate of 

 one-acre foot of water, i. e., a depth of one foot for each 



A MEASURING WEIR. 

 Measuring the duty of water with stationary weir at source ol supply. 



tern, shows that the average depth to which water is 

 used, including rainfall, is approximately 2.50 feet. 

 The records kept by the California Development Com- 

 particularly for the district under the Sweetwater sys- 

 pany for the Imperial settlements show that in 1904 a 

 total of 280,000 acre-feet of wafer was delivered to the 

 canals of the various mutual water companies. The 

 area irrigated was not far from 85,000 acres, so that 

 with rainfall, and not allowing anything for seepage or 

 other losses, the average depth of water used was 3.59 

 feet. In Imperial water district No. 1, 166,800 acre-feet 

 of water was supposed to have been used on 61,000 acres, 

 making an average depth, including rainfall, but not 

 allowing for seepage, of 3.03 feet. In both cases the 

 seepage and other losses must have been considerable, so 

 that the real duty of water was undoubtedly above what 

 the figures indicate. At Yuma, not far from the Im- 

 perial settlements, data kindly placed at the disposal of 

 the Office of Experiment Stations by Mr. J. B. Lippin- 

 cott, of the Reclamation Service, show that in 1904 

 water was run for 4,650 acres planted- to mixed crops 



acre to be irrigated. While the data now available 

 hardly give more than a suggestion of the real duty of 

 water, they are sufficient to show that unless extraor- 

 dinary favorable conditions prevail, canals should be 

 planned on the theory that at least four acre-feet of 

 water will have to be diverted for each acre of land to 

 lie irrigated. Yet this is only roughly true, because of 

 the difference in practice and crops and requirements. 

 Measurements made on one well irrigated farm in San 

 Joaquin Valley in 1904 showed that a single irrigation 

 of alfalfa was satisfactorily accomplished with a depth of 

 .54 foot, yet Mr. W. L. Dixon, of the Kern County Canal 

 and Water Company at Bakersfield, is authority for the 

 statement that under the Kern County system it is not 

 at all uncommon, but quite usual, for a depth of 2 feet 

 of water to be applied to alfalfa at one time. The dif- 

 ference in the use in these two cases is not a difference 

 in requirements, but a difference in practice. Where 

 the smaller quantity was used, the irrigator was careful 

 and the checks in which the water was applied were 

 practically level and not over one acre in area. Where 



