CLASSIFICATION IN HELATION TO WATEE BESOUEOES. 185 



neer rests largely on his general knowledge of related conditions and 

 on the experience that has been gained by the people in the region. 

 The transportation facilities and the market are subject to change 

 and should usually be considered merely to determine whether pres- 

 ent or future development is desirable. Transportation facilities 

 will, under ordinary conditions, be provided in response to produc- 

 tion, and market is a feature which, in the long run and under the 

 present conditions of rapid growth and consumption in this country, 

 will ultimately offer few difficulties. 



CHABAOTEB OF IBBIGATIOIT W^OKES. 



Having reached a favorable determination as to water supply, duty 

 of water, and the economic f eattires above set forth, the engineer must 

 then investigate the character of irrigation works that are adapted 

 to the phj'sical conditions of the area. The character of such works 

 depends entirely on the physical problems to be met. It may be 

 necessary to construct storage reservoirs in order to utilize the high- 

 est possible proportion of the available water. On the other hand, 

 the source of supply may be a very large stre-am, having a capacity 

 -sufficient to furnish all the water required for practicable irriga- 

 tion in the entire region, and the studies are then confined to the 

 determination of suitable diversion sites and canal routes reaching 

 from the headworks to the lands to be irrigated. As in the case of 

 reconnaissance power surveys, no final locations are determined by 

 the engineer, it being considered preferable to leave such matters 

 of detail to those who may in the future develop the project. The 

 location of the headworks and of reservoirs and the routes, lengths, 

 and capacities of canals can be determined approximately by field 

 investigation of the type herein described, and while the results may 

 be inaccurate for purposes of final location and development, they 

 are sufficient to afford information suitable for departmental action. 

 The public lands located in reservoir sites or along the courses of 

 prospective conduits are carefully considered by the engineer with 

 respect to their relation to the ultimate problem under consideration. 



METHODS OF CLASSIFICATION. 

 PBOOBDUEE UNDER THE CAB.EY ACT 



In the administration of the Carey Act and its amendments classi- 

 fication of lands with respect to irrigability is a necessary incident, 

 for under the conditions of this act the land granted must be non- 

 mineral, desert, and irrigable. The first step in the present pro- 

 cedure is the withdrawal of lands under the act of March 15, 1910 

 (36 Stat, 237), at the solicitation of the State in which the lands are 



