356 IRRIGATION INVESTIGATIONS IN CALIFORNIA. 



The entire volume of water which has reached the dam in the thirteen years 

 since it was built would cover 180,070 acres 1 foot deep, and if spread over the water- 

 shed would cover it a little less than 18 inches deep, or an average of 1.36 inches in 

 depth per annum. During the first eight years of storage the run off was abundant 

 and even excessive, the total volume amounting to 171,608 acre-feet, of which 43.5 

 per cent was in one year, 1895. The succeeding five years to date have produced 

 but 8,462 acre-feet of run off in all, or only 35 per cent of the capacity of the reservoir. 

 The average of the thirteen j-ears, if it could have been evenlj' distributed, would 

 have given a J^early volume of 1.3,851 acre-feet, equivalent to a constant stream of 

 20.39 cubic feet per second. The water supply being so unevenly divided among the 

 seasons, there has resulted a ver\' great waste, which has amounted to approximatelv 

 80,000 acre-feet in all, or 43 per cent of the whole. Of this amount the greater portion 

 was lost during the great flood of January, 1895, when nearly three reservoirfuls of 

 water poured over the dam in a few daj's. This loss is entirely distinct from the 

 constant unavoidable loss due to evaporation. The waste or loss over the crest of 

 the dam may be classified as avoidable, because it is due solely to the lack of' reser- 

 voirs of sufficient capacit}'. Had there been in existence, at the time of the flood of 

 1895, three additional reservoirs of equal capacity to that back of the Sweetwater 

 Dam not a drop of water need have wasted into the sea during that flood, and the last 

 three j'ears since 1897 would have been j'ears of plentj' instead of seasons of drought 

 and shortage. Two, and possibly three, such auxiliary sites exist on the sti'eam 

 and might be made available. One lesson to be drawn, therefore, from the extreme 

 fluctuations of this stream, if it can be regarded as a type for southern California, is 

 that all possible reservoir sites upon it need to be utilized and a great excess of res- 

 ervoir capacity provided if its waters are all to be utilized and the industries which 

 spring up under established irrigation systems are to be properly safeguarded. 



THE DUTY OF THE STREAM. 



One of the most interesting problems in connection with the utilization of every 

 stream is the determination of the probable maximum duty to be expected from that 

 stream when its waters shall have been conserved to the fullest extent practicable. 

 The solution of this problem should be the work of the United States Government, 

 for it is one of national importance, and too large for any lesser organization to 

 attempt. If it be determined within reasonable limits of accuracy, in advance of the 

 construction of storage works, much ill-advised investment of capital can be saved, 

 and the development of the water supply may be made with a greater certainty as to 

 the results to be achieved. A stream which may have been generally regarded as a 

 reliable supply for irrigating 50,000 acres, for example, might prove, on thorough 

 investigation, to be good for only 10,000 acres. If the discovery of its real dutj- is 

 made before the distributing system is built over an extravagantly large area, and 

 before water is pledged to more lands than can possibly be supplied, much complication 

 will be avoided and much waste of monej' prevented. For lack of this sort of 

 information, which it is the function of the Government to gather and tabulate for 

 general use, many ill-advised schemes have been projected throughout the United 

 States, and more are being projected every year, which would be condemned, wholly 



