174 CLASSIFICATION OF THE PUBLIC LANDS, 



COMPILATION OF RESULTS AND REVISION OF WITHDRAWALS. 



When results of field investigation are available, much the same 

 procedure is followed in the office in revising withdrawals as in 

 making the preliminary withdrawals. The problem at this stage 

 becomes one of limiting the withdrawals to the least possible area. 

 •Careful scrutiny of plans and profiles of the streams makes it pos- 

 sible to determine the power value of each smallest legal subdivision, 

 and withdrawn areas containing no sites that are or may be valuable 

 for the development of power are restored to the public domain. If 

 the stream is of relatively fl^t gradient, where power development 

 must be restricted to the low-head type and the construction will 

 consist of power houses in conjunction with dams developing the 

 available head, it is possible in many cases to locate definitely the 

 favorable dam sites and divide the stream into successive units of 

 probable development, from which no very great departure in con- 

 struction is likely. On such streams the power-site reserves can be 

 defined with a high degree of accuracy, and the use of each tract, 

 whether for dam site, power-house site, flowage, or other purpose, 

 can be forecast with considerable assurance. A minimum area of 

 land is retained in power-site reserves on such streams. If the 

 stream has a relatively steep gradient, however, where the natural 

 development for power will consist of a low diversion dam and a 

 long conduit leading to a power house perhaps several miles below 

 and developing a high effective head, there can be a wide range of 

 selection for the units of a comprehensive power project. On such 

 a stream no specially favorable dam site is necessary, and relative 

 expense of construction is generally the factor determining a choice 

 among several different locations for the conduit. A definite use for 

 any particular tract can seldom be assigned with development of this 

 type, and the power-site reserve must be maintained so as to include 

 all possible conduit locations if it is to be effective. A final revision 

 of withdrawals along such a stream must be made as the power sites 

 are developed. Even in such cases, however, restorations are fre- 

 quently possible as soon as field examinations are made. 



Eestorations are recommended by the Survey and recorded in the 

 Survey files in much the same way as withdrawals. The usual form 

 of power-site restoration is as follows : 



Department of the Interior, 



United States Geological Survey, 



Washington, 'November 12, 1912. 

 The honorable the Secrexart of the Interior. 



Sir: Investigation of lands included in power-site reserve No. 117, Snake 

 River, Idaho, indicates that the portion of the lands included therein described 

 In the following order of restoration is not valuable for the conservation of 



