CLASSIFICATION IN EELATION TO WATER KESOUECES. 171 



portance for departmental action. The determination of the proper 

 course is difficult, for the question of feasibility must be partly an- 

 swered with regard to future conditions. All the factors discussed 

 in the beginning of this section, such as domestic water supply, irri- 

 gation, and transportation, must be borne in mind, and it is impera- 

 tive that the engineer remember the fact that Government control of 

 a small amount of land may be quite as effectual in the ultimate 

 control of the development at the power site as if every element of 

 that site were in public ownership. A small tract of land, even a 

 fractional subdivision, located within a storage-reservoir site or 

 along a diversion right of way has been sufficient to determine the 

 control of the development. Having reached a decision on all the 

 points above discussed, the engineer makes appropriate report. 



Detailed surveys arfe not attempted in reconnaissance work. Ap- 

 proximate cross sections are taken at possible dam sites and, after 

 the most feasible height of the dam is determined, a rough estimate 

 of the area that would be submerged is made by means of the hand 

 level. Where no profile of the stream channel is available, the fall 

 over a short distance is determined with an aneroid barometer. This 

 instrument, however, must be used with caution, especially during 

 changeable weather. Photographs of all the critical points are 

 taken. The possible dam sites suitable for storage or for diversion 

 having been located and the type of development roughly determined, 

 it is then necessary to consider the run-off. If the problem is one of 

 storage, it will be sufficient to know the approximate mean annual 

 run-off; the height of the storage dam can then be so fixed that the 

 capacity of the reservoir may, as nearly as practicable, be sufficient 

 to afford complete control. Of course, as a rule, sufficient storage 

 capacity is not available, yet on the other hand there are situations 

 in which the dam might be raised to a height that would give greater 

 storage capacity than is necessary. In case no storage is to be pro- 

 vided, the mean daily flow of the stream must, if possible, be deter- 

 mined in order that the primary power capacity of the site may be 

 appraised. If the available site is located in a canyon, it becomes 

 necessary to determine within reasonable limits whether the maxi- 

 mum fall may be secured by a low diversion dam and conduits or 

 whether it would be more economical to obtain the necessary height 

 by the construction of a high dam. 



Much of the land along the streams of the West has passed into 

 private ownership, and where good facilities exist for the develop- 

 ment of water power or the diversion of water for irrigation private 

 interests may have established rights to the use of the water. An- 

 other complication on many streams consists in the location of rail- 

 road rights of way. Thus the problem of land classification may be 



