UN ED SEMES 



LAMATION 



Government Irrigation Work During the Month. 



Another 

 Opening 

 Shoshone 



Another one of the 

 splendid undertakings 

 of the United States 

 Reclamation Service is completed to 

 the extent of the opening of a portion 

 of the land to settlement, namely, 

 about 50,000 acres. This is the Sho- 

 shone project in northern Wyoming. 

 The general location of the project is 

 seventy-five miles east of the Yellow- 

 stone National Park. The total area 

 to be irrigated is 250,000 acres. 



The Shoshone project is notable for 

 the size of its dam, constructed in a 

 narrow pass between towering walls 

 of rock. This dam encloses an im- 

 pounding reservoir whose use is to 

 store the water and let it out into the 

 channel of the river as needed. 



Further down the stream are two 

 diversion dams. One of these, at the 

 village of Corbett, turns the water 

 aside into a tunnel running -parallel 

 with the river three and a half miles. 

 This is necessary in order to obtain 

 the water at a sufficient height to de- 

 liver it into the Garland Canal, which 

 then carries the water to 50,000 acres 

 of irrigable land lying north of the 

 Shoshone River between Balston and 

 Garland. This land is unusually level 

 and well surfaced for irrigation. 



200 feet long on top, and 310 feet 

 high. The reservoir formed will flood 

 6,600 acres to an average depth of 69 

 feet. The walls of the canyon are 

 solid granite; it was therefore be- 

 lieved at first glance that no trouble 

 would be experienced in finding a 

 foundation for the mammoth struc- 

 ture. The diamond drill, however, re- 

 vealed an entirely different state of 

 affairs. It pierced boulders many feet 

 in thickness, but these rested on beds 

 of gravel. At the point finally se- 

 lected for the dam site bed rock was 

 encountered 88 feet below the river 

 bed. 



A Tunnel 

 Spillway 



The Canyon 

 Reservoir 



The impounding dam. 

 in the narrowest por- 

 tion of the canyon above 

 the irrigated tract, will outstrip in 

 height every other structure of this 

 kind. It will have the form of a nar- 

 row wedge, 85 feet across the bottom. 



On account of the steep 

 canyon walls it was nec- 

 essary, in order to pro- 

 vide for a spillway by which the ex- 

 cessive floods might pass the dam, to 

 dig a tunnel from the surface of the 

 proposed reservoir around the dam, 

 through the solid granite of the moun- 

 tain, to discharge into the canyon sev- 

 eral hundred feet below the dam. This 

 tunnel will have a capacity of about 

 25,000 cubic feet per second, or suffi- 

 cient to carry the largest floods of the 

 stream. 



To reach the dam site it was neces- 

 sary to construct a road through an 

 almost inaccessible gorge. On this 

 road there are several tunnels through 

 rock cliffs, and for several miles the 

 road is in rock cuts. Incidentally this 

 road is a scenic route of great beauty, 

 and constitutes a new approach to the 

 Yellowstone National Park. 



