6 CONTENTS. 



Page. 



Classiflcation in relation to water resources 159 



Genei;al principles of water utilization 159. 



Classification of water-power sites 161 



Preliminary withdrawals - 161 



Methods of field examination 167 



Diversity of conditions 167 



Reconnaissance examination 168 



Detailed field investigations 172 



Compilation of results and revision of withdrawals 174 



Adverse claims 175 



Nonpower classiflcation 176 



Additional requirements to make power classification effective 177 



Classification of lands as regards lrrigabillty_ 178 



Field methods 178 



General considerations 178 



Available water supply 181 



Present utilization of water for irrigation 182 



Duty of water 183 



Character of lands to be irrigated 184 



Character of irrigation works 185 



Methods of classification 185 



Procedure under the Carey Act 185 



Irrigation reservoir sites 187 



Procedure under the enlarged-homestead acts 187 



Classification as regards domestic use 190 



General principles 190 



Farm water supply 190 



Range water supply ^ 191 



Municipal water supply 192 



Index 193 



ILLUSTRATIONS. 



Page. 

 FiGUEE 1. Township map showing classification and valuation of coal 



lands 63 



2. Diagram showing split or broken coal beds and their value 



for classification ^ 71 



3. Diagi-am showing depth limits of coals of different B. t. u. 



and of different thicknesses under 6 feet 76 



4. Rates paid in the United States for mining coal of specified 



thicknesses, and curve showing average relation between 

 mining rate and thickness 85 



5. Sketch map showing lines along which a coal bed is of equal 



thickness (isopachous lines), drawn for use In the valuation 



of coal land gg 



6. Reduced copy of diagram used by the United States Geological 



Survey in computing tonnage and value of coal per acre 92 



7. Diagram showing depth to which phosphate deposits are classi- 



fied under the regulations 131 



8. Typical township card from survey records illustrating acUon 



taken by the United States Geological Survey on power sites. 166 



