FARM DRAINAGE AND IRRIGATION 



769 



The removal of one-quarter inch of rainfall in 24 hours will generally 

 provide adequate drainage. On this basis the area in acres drained by 

 given sizes of tile and grades are as follows : 



To double the fall for steeper grades than those given in the above table 

 will increase the carrying capacity of the tile one-quarter to one-third. 



IRRIGATION 



Water, wisely used, has converted many desert acres into fruitful 

 fields and orchards. This has made possible thriving settlements in many 

 parts of the arid West, and encouraged the development of industries 

 other than agriculture, especially the mining of useful metals. 



Water Rights. — In regions of limited water supply, laws for the con- 

 trol of water become essential. These laws should be understood and 

 obeyed by all users of water. It is a principle that rather definite shares 

 in the water supply of a region shall be apportioned to specific areas of 

 land. When the water supply is insufficient for all available land, priority 

 of appropriation receives first consideration. A new settler is prohibited 

 by law from sharing in the water supply at the expense of early settlers. 

 In many irrigation districts, the extravagant use of water has prevailed. 

 A more economical use on the part of the older settlers would produce 

 equally as good crops. In fact, the extravagant use of water is more 

 often injurious than otherwise. 



Co-operation. — This is a necessary feature in most irrigation dis- 

 tricts, because the water supply must serve the entire community, and in 

 order to do so most advantageously, co-operative action is called for in 

 its use^and conservation. Co-operation means that the farmers on an 

 irrigation ditch must take turns in using the water. The larger the volume 

 of water the shorter the time each may use it and the greater number 

 of farmers can be supplied. The apportionment of the water should 

 correspond to the acreage of crops to be irrigated by each farmer. This 

 rotation of the allotment of water to the farmers on a ditch is advan- 

 tageous from two standpoints. First, it gives each farmer sufficient water 

 to cover his land in a very short time, thus economizing on the time spent 



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