IRRIGATION 125 



land are now irrigated from reservoirs. In Ceylon, the 

 Padival Dam is 1 1 miles in length, and 200 feet wide at the 

 base, 30 feet wide at the crest, and 70 feet high in places. 

 This dam is said to have cost $6,327,100. It is further 

 stated that there are 5000 reservoirs in use in Ceylon. There 

 are many reservoirs in use in the United States, some of which 

 have been built by private parties, and others by the 

 government. One of the largest of these is the Roosevelt Dam 

 on the Salt River in Arizona. This dam, completed in 

 February, 1910, has a capacity of 1,824,000 acre feet of water. 



Pumping Water for Irrigation. In many places a supply 

 of irrigation water can not be obtained without the aid of 

 pumps. Usually water secured by this method is very 

 expensive, much more so than the water obtained from 

 canals and reservoirs by gravity. There are, however, 

 certain advantages in pumping the water for irrigation pur- 

 poses. Generally the water supply is under perfect control, 

 which is not always the case with a canal or reservoir. Again, 

 there can be no controversies over water rights or friction 

 with other irrigators who want to use the supply at the same 

 time. 



Underground water is the only source of supply in certain 

 localities. In some places in the West the soil is so open that 

 large streams disappear and flow away underneath the sur- 

 face. When this water can be pumped it forms a valuable 

 supply of irrigation water. In Egypt much of the water is 

 elevated by hand labor either from canals or from the river 

 Nile. In California alone, over 200,000 acres are irrigated by 

 water which is pumped, and some 400,000 acres are so irri- 

 gated in Texas and Louisiana. There has been a marked 

 development in pumps during the past few decades. The 

 power used includes animal power, steam engines, gas and 

 gasoline engines, and electric power. 



