STORAGE RESERVOIRS. 113 



with practically insuperable obstacles. Nature had not provided suitable localities, 

 and an exhaustive study of the whole basin gave only the following meager results : 



" Lake Geneva could be so dammed at the outlet as entirely to cut off its dis- 

 charge at the time of flood. 



"The Arve and its tributaries, being mostly torrential streams, afford very few 

 good reservoir sites. In fact only one was deemed worthy of consideration, and its 

 capacity was only 706,000,000 cubic feet. This would be of no use to the upper Rhone, 

 which flowed between high banks not subject to overflow, and by the time it reached 

 Lyons its effect would be wholly inappreciable. The reservoir would cost $400,000, 

 besides the destruction of valuable bottom lands. This project was therefore not 

 considered practicable. 



"The next site in passing down stream is what is known as the Lac du Bourget, 

 situated to the east of the river and forming a kind of natural reservoir in times of 

 flood. It was proposed to carry this natural action still farther by damming the 

 Rhone. Its natural storage capacity is 3,350,000,000 cubic feet, and this could be 

 increased to 5,824,000,000 cubic feet. It was calculated that this storage would diminish 

 the flow of the Rhone at the moment of flood by 35,000 cubic feet per second, and would 

 diminish the height of the flood at Lyons by 2.3 feet. The cost of this work would be 

 about $4,000,000. 



"No further reservoir sites of importance were found above the junction of the 

 Ain. In this valley there are several feasible sites, whose aggregate capacity would 

 be nearly 2,000,000,000 cubic feet. The cost would be about $1,400,000. The esti- 

 mated effect at Lyons on a flood like that of 1856 would be to reduce the height of the 

 flood by about i foot. 



" No reservoirs were recommended for the Saone, because none that could be found 

 would have any appreciable effect as compared with the vast natural reservoir formed 

 by the lower part of the valley already alluded to, and would have almost no influence 

 on the discharge of the main stream at Lyons. 



"Below Lyons the immediate valley of the main stream offers no opportunities 

 for large reservoirs. 



"The first large tributary on this section of the river, the Isere, was carefully studied, 

 but no situations were found which were considered favorable. The alluvial and 

 unsatisfactory nature of the foundation for dams, the necessity of condemning valuable 

 bottom lands, the small aggregate result possible of attainment under the most favor- 

 able circumstances, rendered the project wholly unadvisable. 



"The valley of the Ardeche likewise contains no feasible reservoir sites. 



" On none of the other tributaries were suitable sites found until the Durance was 

 reached. The valley of this stream, which is one of the largest affluents of the Rhone, 

 offers several good sites, and it was found practicable to store 11,366,600,000 cubic 

 feet of water at a cost of about $6,600,000. The result, however, was altogether insig- 

 nificant. The Durance enters the Rhone far down the valley of that stream, where its 



