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THE IRRIGATION AGE. 



THE DUTY OF WATER IN CALIFORNIA. 



BY FBANK ADAMS. 

 Office of Experiment Stations, U. S. Department oi Agriculture. 



. There is no single question of irrigation of more 

 fundamental importance than the amount of water nec- 

 essary to most successfully and most economically raise 

 crops. This is true whether irrigation be viewed from 

 the standpoint of the court which settles water rights, 

 the engineer who constructs canals, the superintendent 

 who divides and distributes water, or the farmer who 

 uses it. Nevertheless, although accurate studies to de- 

 termine the duty of water have been carried on to a 



little for the same crop in a locality where conditions 

 are different. In other words, the duty of water must 

 be studied locally rather than generally, and California 

 is so large a State, and has such widely varying condi- 

 tions of soil, rainfall, plant adaptability, water supply, 

 and, what is most perplexing of all, has so many farmers, 

 with such varying ideas regarding how much water 

 plants need that with all resources that seem to be 

 available, years of study and careful practice will be 

 required before we can be said to know the duty of 

 water in California. 



To begin with, there is not even a general agree- 

 ment as to what the term "duty of water" means, or how 

 it should be expressed. The term "duty" used in con- 



A CALIFORNIA IRRIGATION CANAL IN THE FOOTHILLS 

 With a high duty of water running in the canal should irrigate 30,000 acres. 



considerable extent in all of the Western States for a 

 number of years, the data available for California, at 

 least, are comparatively meager. This is unfortunate, 

 because not only is the United States Government un- 

 dertaking irrigation in a large way, but hundreds of 

 individuals, co-operative companies and private corpo- 

 rations are now planning, constructing, or operating ir- 

 rigation systems, and some 35,000 farmers are already 

 irrigating, in most cases with too much water, approxi- 

 mately 2,000,000 acres of orchards, vineyards and field 

 crops. 



It is in no way surprising that, in spite of the ef- 

 forts that have already been made, so little is known 

 about the duty of water in California, because what 

 might be a sufficient quantity of water for a given 

 crop in one localitv might be either too much or too 



nection with water would seem to indicate what service 

 it should perform, yet the term is taken to mean the 

 service it 'does perform. Probably the misnomer will 

 not be eliminated until the service water should perform 

 in irrigation and the service it does perform are one 

 a result so far attained in few, if any. localities in Cali- 

 fornia. While the inaccuracy of the term is perhaps of 

 little consequence, the wide variation in the way it is 

 expressed is of consequence, because it leads to misun- 

 derstanding. At present 'the duty of water is expressed 

 in the area of land a given unit of running water will 

 irrigate, the, size of stream necessary to water a given 

 area, or the total depth of water applied to the surface 

 of land during the season. 1 f either of the first two 

 expressions are used, no definite idea is conveyed unless 

 the length of time the stream of water is flowing be 



