1906 



FORESTRY AND IRRIGATION 



249 



$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 exces- 

 sive costs the three western dams ap- 

 pear remarkable. The Roosevelt clam, 

 for example, contains 350.000 cubic 

 yards of masonry erected at a cost of 

 $3,850,000. The' capacity of the reser- 

 voir is 61,000,000,000 cubic feet, or 

 fifteen times that of the New Croton, 

 and about seven and one-half times 

 that of the Wachusett. The cost of 

 this dam per million cubic feet storage 

 is only $63.16. Even more remark- 

 able appears the Pathfinder dam. It 

 contains 53,000 cubic yards of mason- 

 ry, 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 stor- 

 age is therefore only $22.95 as against 

 $1,900 for the New Croton. and $238 

 for the Wachusett. Similar figures 

 for the Shoshone dam, the highest in 

 the world, are : Cubic yards of mas- 

 onry, 69,000; cost, $1,000,000; capa- 

 city of reservoir, 20,000,000 cubic feet, 



or a cost per million cubic feet storage 

 of $50.35- 



These extremely low costs have sel- 

 dom been equalled in the history of 

 reservoir construction, and are due 

 largely to the excellent natural facili- 

 ties which are found in the rugged 

 western country. From this fact it 

 must not be inferred that these west- 

 ern structures are simple engineering 

 works. On the contrary, owing to 

 their isolated location, their inaccessi- 

 bility by rail and often by wagon, and 

 the erratic and torrential character of 

 the streams, they involve problems 

 which tax the skill and ingenuity of 

 their builders to the utmost. 



It is most fortunate that these res- 

 ervoirs 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 capa- 

 city. 



The Croton dam, if it had been con- 

 structed in Salt River Valley in Ari- 

 zona for irrigation, would only supply 

 23,000 acres, and irrigators would 

 have to pay $330 an acre for stored 

 water, as against $20, the estimaed 

 cost from the Roosevelt dam. 



