688 SOILS: PROPERTIES AND MANAGEMENT 



extended rapidly in the western United States. It has 

 approximately doubled each ten years since 1879. 



Irrigation is employed somewhat generally throughout 

 the region west of the 100th meridian, which runs through 

 central Nebraska. With the exception of limited areas 

 the annual rainfall is less than 25 inches, and over large 

 areas it is less than 15 inches. 



The methods of securing water and applying it to the 

 land have grown up gradually out of the experience of 

 the people in many communities and under many condi- 

 tions. Cooperative effort of some sort is essential to 

 provide water for irrigation, and this has led to the use 

 of several types of organizations for the purpose. Nat- 

 urally, the states concerned have taken a part in the 

 matter by passing laws and providing funds to promote 

 irrigation practices. Finally, the aid of the Federal 

 Government was enlisted. The enterprises for the pro- 

 vision of water for irrigation may be divided into seven 

 groups, 1 chiefly according to their legal status : (1) com- 

 mercial enterprises selling water for profit; (2) partner- 

 ships among individual farmers without formal organiza- 

 tion; (3) cooperative enterprises, made up of water 

 users; (4) irrigation districts which are public corpora- 

 tions ; (5) Carey Act 2 enterprises, by Federal enact- 

 ment authorized August 18, 1894, and made up of 

 grants to the arid and semiarid states, these states 

 being held responsible for the irrigation of these grants ; 

 (6) United States Indian Service enterprises, to provide 

 for the construction of irrigation works in Indian reser- 

 vations; and (7) the United States Reclamation Serv- 



1 Thirteenth U. S. Census, Chapter 14, p. 421. 1910. 



2 Stover, A. P. Irrigation under the Carey Act. U. S. D. A., 

 Office Exp. Sta., Ann. Kept. pp. 451-488. 1910. 



