Irrigation Enterprise in America. 831 



on a barge anchored in the river, whence the water is pumped into a 

 reservoir and is distributed by gravity to the land. Government coal 

 of a quality too poor to ship was to irrigate 30,000 acres of previously 

 waste land. This project has not, however, proved very successful. 



" In Western Colorado is the Uncompahgre Valley, with a broad 

 alluvial plain traversed by a small stream. Some miles away in a 

 parallel valley is the larger Gunnison River flowing in a canyon. 

 One A'allej^ had land without water, and the other water without land. 

 The engineeis drove a tunnel six miles long through a mountain 

 range and brought the water of the Gunnison to the valley of the 

 TTncompahgre, and it is irrigating 140,000 acres. 



" In the Yuma project in California-Arizona, the main canal 

 has to be on the California side of the river, where there is less land 

 to irrigate t'nan on the Arizona side. An enormous inverted siphon 

 passing under the river has been constructed, and the surplus water 

 is carried to the east side, where it is distributed. 



" In the construction of dams for the reservoirs, a wide range of 

 problems was presented. In several of the projects dams were built 

 across deep and relatively narrow mountain gorges where the dam 

 had to be very high but could be firmly anchored at the bottom and 

 sides in solid rock. The famous Roosevelt dam in Arizona is solid 

 masonry 280 feet high, 235 feet long on the bottom, and 1125 feet 

 long on top. So great is the pressure of the impounded water that 

 the dam is 180 feet thick at the base. A roadway on top is wide 

 enough for three automobiles to travel abreast. 



"The Arrowrock dam in Idaho is 349 feet high, and the Sun 

 River dam in Montana is 329 feet high; the Elephant Butte dam, 

 in iS'ew Mexico, 318 feet ; and the Shoshone dam, in Wyoming, 328 

 feet. Other dams have been built in broad, open valleys, where 

 great length and thickness but small height were requisite. The 

 Hondo dam. in Xew Mexico, is only 25 feet high, but has a crest 

 length of over 3 miles. The Xelson Reservoir dam, in Montana, is 

 39 feet high and 4 miles long. 



" Xo two undertakings were alike. The ingenuity and resource- 

 fulness of the engineers were tested anew with every project. No 

 case illustrates this better than the Salt River project in Arizona. 

 The topography of the region led to the adoption of a dam site 

 60-70 miles from the land which was to be irrigated. The nearest 

 town of any size was TO miles away, and the nearest railway 40 miles. 

 The site selected for the dam was in almost inaccessible mountains. 

 From the railroad to this site a road had to be constructed, miles 

 of it cut into the precipitous face of the mountains. This road alone 

 cost a half-million dollars. The expense of getting timber and 

 cement to this remote region, involving a wagon haul of 40 miles, 

 would have been prohibitive. Moreover, labourers could not be 

 induced to go there to work. Yet the building of the dam required 

 a vast quantity of materials, a great number of workmen, and a 

 large amount of mechanical power.. The engineers decided to develop 

 hydro-electric power at the dam site, and they built a power canal 

 15 miles long, costing a million and a half dollars, installed a power 

 plant, and produced their power on the spot. They erected a cement 

 mil], quarried the rock for making the cement, and manufactured 



