IRRIGATION 



3065 



IRRIGATION 



less than 1,000,000 were in the undertakings of 

 the national government. About 3,000,000 acres 

 are included in its projects, completed or under 

 way in 1916, but as settlement on them is slow, 

 little further construction is planned. 



Though the number of acres watered by 

 works of the national government is small com- 

 pared with the total for private undertakings, 

 most of the dams and reservoirs built by the 

 reclamation service have been too large for 

 construction by individual enterprise. The 

 Roosevelt dam, shown in an illustration in the 



AN IRRIGATION DITCH 



article ARIZONA, is the best known. Arrowrock 

 dam, in Idaho, finished in 1915, is the highest 

 in the world. The largest irrigation reservoir 

 ever built is at Elephant Butte dam on the 

 upper Rio Grande; it will store more than 100 

 billion cubic feet of water, enough to cover the 

 state of New York to the depth of an inch. 

 The largest of the government systems in re- 

 gard to the area affected is at Boise, Idaho, 

 where 255,000 acres can be irrigated. 



Progress in Canada. Though only a very 

 small portion of Canada has as little rainfall 

 as the desert regions of the United States, there 



is a large area in the west where it has be*en 

 found wise to irrigate the land. Most of the 

 irrigation systems are small and all have been 

 built by individuals or companies. The 

 Dominion government grants licenses to those 

 who wish to divert water from rivers, and in 

 one case has assisted with a loan of money, but 

 it does not erect irrigation works. 



The largest irrigation system on the Ameri- 

 can continent has been constructed in Alberta 

 by the Canadian Pacific Railway. The water 

 of the Bow River is diverted from a reservoir 

 near Bassano to 440,000 acres of land. The dam 

 which forms the reservoir is over 7,000 feet 

 long and contains more material than any 

 other in the world except the Assuan dam in 

 Egypt. A picture of the spillway of the dam 

 will be found in the panel which heads the 

 article ALBERTA, and more information about 

 Canadian irrigation is given in the articles 

 ALBERTA, BRITISH COLUMBIA and SASKATCHE- 

 WAN. 



In Other Countries. India leads all the 

 world in irrigation. Fifty million acres of its 

 land are artificially watered, half of them by 

 government works, which in some years return 

 nine per cent on the capital invested. One 

 canal, the Chenab, serves nearly 2,000.000 

 acres, and its annual revenue is nearly twenty- 

 five per cent of its cost. Others are operated 

 at a loss, but the government finds it cheaper 

 to build them than to supply food to the popu- 

 lation in times of famine which would other- 

 wise' occur. The struggle of the British govern- 

 ment against famine is one of the heroic things 

 the natives have most heartily appreciated. 



In Egypt the natives have carried water 

 from the Nile in jars, or raised it with an 

 Archimedean screw or diverted it to the land 

 with simple dams and canals for forty cen- 

 turies or more. The British have constructed 

 works which irrigate 15,000,000 acres, among 

 which is the great Assuan dam, the largest in 

 the world. 



The valleys of the Tigris and Euphrates 

 were once well irrigated, and attempts are 



Before Irrigation 



