Areas of standing timber, 15 to which larger streams can be taken, 7 which smaller streams can serve, 7 Arid Region, Boundaries of the, 1, 3 Extent of the, 5 Increase in water supply in the, 89, 91 Land system needed for the, 25 Mining industries of the, 88 Physical characteristics of the, 1 Precipitation of the, 48 Rainfall of the, 5 Arizona and New Mexico, Seasonal precipitation in, 56 Arkansas, Land grants to, 174, 179 _Artemisia_, 110 Ashley Fork, Irrigable lands of, 161 Atchison, Topeka and Santa Fé Railroad Company, Land grants to the, 178 Atlantic and Pacific Railroad Company, Land grants to the, 179 Atlantic coast, Flow of the rivers of the, 76 Rainfall on the, 69 Barfoot, Mr. J. L., 59 Barton, Mr., 113 Basin, Colorado. (_See_ Colorado Basin.) Great Salt Lake. (_See_ Great Salt Lake District.) Range System, 94 Sevier Lake. (_See_ Sevier Lake District.) Uinta-White. (_See_ Uinta-White Basin.) Bear River, 117 City, 78 drainage basin, Agricultural resources of the, 119 Area of the, 119 Mean flow of the, 72 Beaver dams, Effect of cutting, 74 _Betula occidentalis_, 103 Bill to authorize the organization of irrigation districts, 30 pasturage districts, 33 Black Rock bench, 61 pillar, 59, 60 Bonneville Lake, 96 Book Cliffs, Orographic structure of the, 98 _Bouteloua oligostachya_, 108 _Bromus_, 109 Brown Cliffs, 98 Brown’s Park, Irrigable lands of, 162 Burlington and Missouri Railroad Company, Land grants to the, 178 Canals, Land grants in aid of, 166 Cañon Lands, Amount of irrigable land in the, 106 Coal lands of the, 106 Description of the, 105 of Utah, 94 _Carex Jamesii_, 109 Carrington Island, 62 Castle Valley, 105 Central Pacific Railroad Company, Land grants to the, 177 _Cercocarpus parvifolius_, 110 _Celtis occidentalis_, 103 Circle Valley, Amount of irrigable land in the, 137 Climate of the Colorado Basin, 151 Coal lands, 45 Disposal of the, 44 of the Cañon Lands, 106 of the Rocky Mountain Region, 19 Colony system, 28 Colorado Basin, Climate of the, 151 Elevation of the, 151 Irrigable lands of the, 150 Mean annual precipitation in the, 79 Orographic structure of the, 95 Source of the water supply of the, 152 Table of irrigable lands of the, 164 drainage area, 94 River, Principal tributaries of the, in Utah, 150 Conditions affecting the distribution of rainfall, 90 Coöperative labor necessary to the development of irrigation, 11 Critical period, 85, 138, 154 season, 116 Dakota, Precipitation of, 51 Denver Pacific Railroad Company, Land grants to the, 179 Desert drainage area, 94 Orographic structure of the, 95 Des Moines River, Land grant in aid of the improvement of the, 171 Distribution of rain throughout the year, 50