METHOD OF IRRIGATION 



197 



construction of permanent ditches is the first big thing in 

 irrigation agriculture. Great waste has occurred and is 

 occurring because of carelessness in this matter. 



The ditches, once decided upon, should be built in a 

 permanent fashion, so that they will not need to be 



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Fia. 35. Plan of field-ditch irrigation. 



repaired greatly from year to year. In the older and more 

 prosperous irrigated sections, ditches are often made of 

 concrete and are consequently practically indestructible. 

 The best illustration of this kind of ditch is found in Cali- 

 fornia, notably in the Riverside district, where the orange 

 groves require that water be made to do its highest duty. 



