2 5 8 



THE IRRIGATION AGE. 



THE HEADGATES. 



The headgates of the canal are located on the 

 south bank of the river. They are forty feet wide, 

 ending in masonry abutments on each side. These 

 abutments are ten feet higher than the bottom of the 

 canal, and are connected by a masonry wall whose 

 top is level with the bottom of the canal, and whose 

 bottom extends eight feet below the canal. 



This wall forms the sill of the headgates, which 

 are eight in number, each five feet wide, and formed 

 of a single plate of steel, strengthened with angle 

 irons. The posts upon which the gates slide are each 

 made of two sections of railroad iron, riveted togeth- 

 er base to base, and set in the masonry footwall. 



THE CANAL. 



The canal supplied by these headgates is thirty feet 

 wide on the bottom, forty-eight feet at the water line, 

 and carries six feet of water. Its grade is thirteen 

 inches to the mile, and its capacity is 26,000 miner's 

 inches. The banks are nine feet high above the bot- 

 tom of the canal, and are fourteen feet wide on top. 



The portion of the canal between the headgates 

 and the Snake river, 2)^ miles long, is called the 

 " main canal." There are two waste gates on this 

 section, one near the dam and one at the lower end 

 of the main canal. Each of these gates is capable of 

 discharging the whole flow of the canal, the first into 

 the Bruneau and the last into the Snake river. They 

 are of a somewhat novel design, and may be de- 

 scribed as follows : A section of the lower bank of 

 the canal is omitted, and replaced by two masonry 

 "U" shaped abutments twenty feet apart. The 

 top of the canal bank is made continuous by a bridge 

 twenty feet long, resting upon the tops of the 

 abutments. The abutments are connected by a ma- 

 sonry wall, whose top is level with the bottom of the 

 canal. The space between the abutments and above 

 this wall is the waste way. The waste way is regu- 

 lated by a single gate, twenty feet long and six feet 

 high. It is made in the shape of a segment of a 

 cylinder, and turns upon the axis of the cylinder. 

 The axis is horizontal, and the weight of the gate is 



so counterbalanced that it is easily managed by one 

 man working a rack and pinion gearing. The top of 

 the gate is always placed at the same level as the 

 surface of the water required in the canal, and forms 

 a regulating weir. It is opened to a position of full 

 discharge by lowering the gate till its top is level 

 with the bottom of the canal. 



The drainage of the country above the canal is 

 passed under it through masonry arch culverts. The 

 largest of these culverts is 126 feet long, and has a 

 four-foot span. The lateral or distributing ditches 

 are supplied by masonry culverts from the main 

 canal. The main canal, as above described, is now 

 completed, with all its accessories of waste gates, 

 lateral gates, culverts and wagon bridges. 



What is known as the "main branch canal " is an 

 extension of the main canal down the south bank of 

 Snake river. This canal is fifteen miles long, and is 

 the same in all respects as the main canal, except 

 that its width has been reduced from thirty feet in 

 the main canal to sixteen feet in the extension. The 

 surplus water of the main canal above the capacity 

 of the extension will be used for the supply of a 

 branch canal on the north bank of the Snake river, 

 and for water power to pump water to a higher level 

 for the supply of lands above the main canals. 



The capacity of the canals is greater than would be 

 needed for irrigation alone, but the conditions in the 

 valley under the canal are somewhat unusual. 



Every acre of the irrigable land is underlaid by 

 gold-bearing gravel, covered by a few feet of soil, 

 and the canals are designed to supply water for these 

 mines as well as for irrigation purposes. 



About four thousand acres of promising placer 

 lands have been located directly under the canals 

 now in process of construction. As above stated, the 

 dam, the headworks, and the main canal are now 

 completed. The extension of the main canal cover- 

 ing the mining ground is well along toward comple- 

 tion, all the more difficult portionshaving been finished 

 already, and it is expected that the coming summer 

 will see the waters of the Bruneau spread upon the 

 valley of the Snake. ' 



DAM ON BRUNEAU RIVER IN IDAHO. 



