50 IRRIGATION FARMING. 



be. Illustrations of such conditions are found in 

 many places along the valleys of the Arkansas, the Rio 

 Grande, and other western streams, particularly those 

 which rise at great elevations and have a strong velocity 

 throughout their upper courses and a low velocity 

 farther down stream. 



The Surface Supply. — We are safe in claiming 

 four distinc5tive sources of water-supply, which may 

 in turn be divided into two classes. These are the 

 streams, natural lakes and reservoirs, underflow or 

 phreatic waters, and the deep subterranean or artesian 

 bksins. Of these the most pradlicable and available are 

 the living waters of the natural streams. In the older 

 irrigated states, where the legislators have framed laws 

 for the appropriation of running waters, the control 

 thereof is usually placed with an executive officer, 

 generally called the State Engineer, who virtually has 

 under his charge and supervision the control of the 

 running waters. He gauges the streams, keeps a 

 record of their flow, and doles out the canal rights in 

 accordance with the statutes. First come, first served 

 is the rule, and ditch charters which are granted by 

 him are issued in consecutive numerical order, until 

 the full carrying capacity of the stream is allotted, 

 when further issuance of charters ceases. 



In the most successful irrigating watercourses taken 

 from the perennial streams, the headworks are almost 

 invarialy located well up on the river, to command 

 sufficient level in order, if possible, to tap the. stream 

 where the water is clear and not laden with silt. By 

 thus locating the intake it is usually possible, owing to 

 the greater slope of the country, to reach the high 



