SOIL WATER 89 



The early irrigation enterprises were very wasteful 

 of water, but more care is now coming to be exercised. 

 There are three sources of serious loss of water: losses 

 at seasons of the year when the water in the streams can- 

 not all be used, seepage from canals, and over-irrigation. 

 These losses may be decreased by building reservoirs, 

 and by using more care in constructing canals, and in 

 applying water. 



91. Storage Reservoirs. During a part of the year, the 

 rivers carry enough water to irrigate much more land than 

 can be supplied through the summer months. The flow 

 of the Nile in September is thirty-five times that of June. 

 To hold back a part of this water, the English built the 

 Assuan reservoir, which extends up the Nile for a hundred 

 miles. 



Forests in the mountains serve to hold back the water 

 and so distribute it through the season. But reservoirs 

 are also necessary. In India, 9,500,000 acres are irrigated 

 from reservoirs, an area equal to about five times the 

 area of improved farm land in New Jersey. 



The United States Government is now building large 

 reservoirs for storing irrigation water. The projects now 

 approved provide for the irrigation of 1,909,000 acres, 

 located in fourteen states. The total cost is estimated 

 to be $34,270,000, or about $18 per acre. The land thus 

 reclaimed is sold to settlers, so that it more than pays 

 the cost of the reservoirs and canals. The money can be 

 used over again for irrigation of more land. After all 

 the present reservoirs are completed, we shall have only 

 one-fifth as large an area irrigated from them as is thus 

 irrigated in India. 



