358 • IRRIGATION INVESTIGATIONS IN CALIFORNIA. 



Assuming an average consumption of 50 gallons per capita in supplying domestic 

 demand, and estimating the population as 2,500 inhabitants, the volume thus repre- 

 sented would be equivalent to 1,600 acre-feet in twelve years. This quantitj' being 

 deducted from 76, -454, and the remainder divided by 12, the quotient is 6,230 acre- 

 feet as the average volume of water applied to the lands annually during the twelve 

 years. The area irrigated in 1896 reached a maximum of 4,580 acres. If a mean 

 area of 4,000 acres be assumed as having been irrigated, the mean depth of water 

 applied, hj the above computation, would be 1.56 feet. This is, of course, a very 

 rough approximation of the probable consumption during the period in question. 

 It is closely corroboi^ated by numerous meter measurements of the volume applied 

 to certain known areas, so that the actual use may be fairly closely stated to have 

 been 1.5 feet in depth per annum. 



There has been a growing conviction, however, that the orchards would have 

 thrived equally well, and perhaps better, with a more moderate application of water. 

 The experience gained in the care of bearing orchards since the great drought com- 

 pelled the company to seek and develop an independent source of supply have shown 

 that the trees will live and bear with an extremelj' small allowance of water. The 

 history of the use of water in 1899 is extremeh' interesting. At the beginning of 

 the irrigation season the reservoir contained barely 40,000,000 gallons of water. By 

 the sinking of numerous wells in the upper part of the reservoir valley and in the 

 valley below the dam, and bj- the establishment of elaborate pumping plants, the 

 company developed and pumped 457,000,000 gallons, of which the3- estimated 

 140,000,000 gallons were used in supplying domestic service and for mechanical 

 purposes, leaving 317,000,000 gallons as the amount of pumped water used in irri- 

 gating 3,800 acres of orchard, chie% citrus fruits. This, added to the 40,000,000 

 gallons in the reservoir, gave a total volume of supply of 1,096 acre-feet. Thus the 

 average depth of water applied was but 0.288 feet, or 3.375 inches. The irrigation 

 was supplemented bj" thorough cultivation, and the orchards, when thus cared for, 

 were quite thrifty and bore heavily. In fact, the lemon crop was never so heavv as 

 the one following the drought of 1899. The water used was but 18.5 per cent of the 

 average amount previously applied. Still it can not be argued from this experience 

 that such extreme economj- could be practiced as a regular thing. It appears to be 

 the general opinion now among the irrigators that thej^ have heretofore used more 

 water than necessary, and that the allotment of 1 acre-foot per annum (326,000 gallons 

 per acre, or 12 inches in depth) is ample for their orchards and all other crops, except 

 alfalfa, which requires rather more. This being accepted as a reasonable allowance, 

 the maximum possible duty of Sweetwater River in irrigation, based on the measured 

 run off of thirteen years, may be deduced as follows, assuming that ample storage 

 capacity be provided: The average annual run off is 13,492 acre-feet, of which the loss 

 by evaporation from the surface of reservoirs may be 25 per cent. This would leave 

 10,119 acre-feet as the average volume available for actual irrigation, which would 

 irrigate 10,119 acres. 



Jn short had there been more reservoirs on the Siveetwater, having a combined 

 storage capacity of 75,000 acre-feet (instead of 18,000 before the flow of 1895 and 

 22,500 since the following year), the stream flow since 1887 would have amply irri- 

 gated about 10,000 acres of land chiefly in orchard without the panicky conditions 



