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THE IRRIGATION AGE. 



storage height, the New Croton is the lowest. The 

 order is then as follows: Shoshone, 240 feet; Roose- 

 velt, 230 feet; Pathfinder, 200 feet; Wachusett, 185 

 feet, and the New Croton, 157 feet. In other words, 

 about 50 per cent of the masonry in the New Croton 

 dam is below ground and is serviceable for foundation 

 purposes only. 



It is interesting to note the comparative reservoir 

 capacities. While the New Croton dam is the largest 

 in the world from the standpoint of its amount of 

 masonry, the storage capacity of the reservoir formed 

 by it is by far the lowest of any of those above men- 

 tioned. In fact, from a standpoint of storage economy, 

 the New Croton reservoir is one of the poorest that 

 has been constructed in recent years. The dam con- 

 tains 833,000 cubic yards of masonry and was erected 



storage is therefore only $22.95, as against $1,900 for 

 the New Croton, and $238 for the Wachusett. Sim- 

 ilar figures for the Shoshone dam, the highest in the 

 world, are: Cubic yards of masonry, 69,000; cost, 

 $1,000,000 ; capacity of reservoir, 20,000,000 cubic feet, 

 or a cost per million cubic feet storage of $50.35. 



These extremely low costs have seldom been 

 equaled in the history of reservoir construction, and are 

 due largely to the excellent natural facilities which are 

 found in the rugged western country. From this fact 

 it must not be inferred that these western structures are 

 simple engineering works. On the contrary, owing 

 to their isolated location, their inaccessibility by rail 

 and often by wagon, and the erratic and torrential char- 

 acter, of the streams, they involve problems which tax 

 the skill and ingenuity of their builders to the utmost. 



Road Leading to Pe 



at a cost of $7,600,000. The capacity of the reservoir 

 formed by it is 4,000,000,000 cubic feet, or a cost of '- 

 $1,900 per million cubic feet storage. Similar figures 

 for the Wachusett dam show that it contains 280,000 

 cubic yards of masonry, and was erected at a cost of 

 about $2,000,000. Its storage capacity is 8,400,000,000 

 cubic feet, or a cost of $238 per million cubic feet 

 storage. In contrast to these excessive costs the three 

 western dams appear remarkable. The Roosevelt dam, 

 for example, contains 350,000 cubic yards of masonry, 

 erected at a cost of $3,850,000. The capacity of the 

 reservoir is 61,000,000,000 cubic feet, or fifteen times 

 that of the New Croton, and about seven and a half 

 times that of the Wachusett. The cost of this dam per 

 million cubic feet storage is only $63.16. Even more 

 remarkable appears the Pathfinder dam. It contains 

 53,000 cubic yards of masonry, erected at a cost of 

 $1,000,000. The capacity of the reservoir is 43,560,- 

 000,000 cubic feet, or more than ten times that of the 

 Croton. The cost of the dam per million cubic feet 



n Falls Idaho. 



It is most fortunate that these reservoirs provide 

 enormous storage at relatively low cost, otherwise their 

 construction would not be feasible, as the irrigated land 

 could not bear the expense of the costly structures of 

 the East with their limited storage capacity. 



The Croton dam, if it had been constructed in 

 Salt River Valley, in Arizona, for irrigation, would 

 only supply 23,000 acres, and irrigators would have to 

 pay $330 an acre for stored water, as against $20, the 

 estimated cost from the Roosevelt dam. 



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