174 1HE IRRIGATION AGE. 



America, judging by the relics, I desire to call attention to the diffi- 

 culties we have to contend against which may or may not exist in 

 other places. 



One of our greatest is the small amount of fall in the Salt and 

 Gila rivers after they leave the mountains, probably ranging from 

 three to seven feet per mile. As the valleys lay twelve or fifteen feet 

 above the river the canal must be started up stream from five to fif- 

 teen miles, with a fall of from 18 inches to two feet per mile, to get it 

 on the land. The bed of the river is sediment, sand and gravel for an 

 unknown depth, and a mason dam is, therefore, out of the question, 

 while brush and rock or lumber dams can only be used to raise the 

 water a few feet. 



The Arizona timber dam, shown in this number of the AGE, is the 

 highest dam in use on the Salt or Gila rivers, on a sandy foundation. 

 It had a section taken out during the flood of 1891, but it has held all 

 right since that. The Woolfy dam, on the Gila river, which was built 

 of lumber similar to the Arizona and with a sandy foundation, at- 

 tempted to raise the water 18 feet, but the height was too great and 

 the apron on the lower side was not long enough to carry the overflow 

 a sufficient distance from the dam and it soon settled, a portion of it 

 being carried away, leaving a canal, probably fifty miles long, large 

 enough to canal boats, but without any water, and it is still unused. 

 This canal covers one of the finest valleys in the world; the depth of 

 the soil has never been found. It is traversed by railroad, with a num- 

 ber of towns and shipping stations. Without water this land is a des- 

 ert; with water it would furnish six mowings of alfalfa, or keep two 

 to three head of cattle per acre on pasture the year round. Had this 

 dam held it would have supported a hundred thousand head of cattle 

 and a large population. 



With a little government aid, or even by the combining of private 

 capital, it can be made a success yet. The present dam is located at a 

 bend of the river where it narrows down to less than half its usual 

 width, as it passes between two mountains of solid rock and, had there 

 been a rock bottom, a better location could not have been asked for. 

 A low dam would probably have held. By running the canal up stream 

 several miles the bed of the river can be tapped, securing a large por- 

 tion of the invisible underflow, which would probably more than 

 double the amount of water in the summer where a dam is used to 

 raise it. 



Up to the present time all of the ancient and modern canals de- 

 pended on diverting the surface water from the stream by a dam; the 

 lower a dam the less it took to keep it in repair, no attempt being 

 made to secure the underflow, which is very strong and will probably 

 averaga two miles wide. A well ten feet, eight feet square, sunk 



