SPECIAL FARM TOPICS 301 



wasted as for water used, has been found not only to reduce the total 

 amount consumed but also to benefit greatly the land irrigated. It 

 also increases the areas possible to irrigate, benefiting both the indi- 

 vidual irrigators and the public. Under practically all systems the 

 charge amounts to one dollar per cubic foot per second for twenty- 

 four hours. (Ex. S. Bui. 229.) 



Duty of Water. By duty of water is meant the area or acreage 

 of land which may be irrigated with a given quantity of water, as 

 a cubic foot per second or miner's inch. Generally the duty of water 

 is not high, that is, the area of land irrigated by a cubic foot per sec- 

 ond is small. However, while this is and must always be a variable 

 quantity, owing to variations in soils, conditions of use, different 

 character of crops and other causes, the principal and most apparent 

 reason for the low duty is the almost total lack of effort for economy 

 in its use. The almost universal lack of knowledge among farmers 

 of the measurement of water, and consequently of any effort to deter- 

 mine the quantity used, confuses and renders impracticable the deter- 

 mination of its duty. Ordinarily the duty of water is 100 and 200 

 acres per each "second foot," though it sometimes falls as low as 50 

 acres, and if water be very scarce or hard to secure it may reach as 

 high as 500 acres per second foot. (Univ. of Nev. Bui. 52: Tex. 

 Bui. 43.) 



Losses in Transmission. Under present practice a very large 

 part of the water diverted from streams for irrigation is lost by seep- 

 age from ditches, by evaporation from ditches and from the wet sur- 

 faces of irrigated fields, by percolation beyond the reach of plant 

 roots, and by wasteful practice. 



The limiting of the area irrigated is not the only bad result of 

 losses and excessive use. The water wasted has swamped large areas 

 once fertile, or brought up so much alkali as to injure or destroy vege- 

 tation, requiring drainage or the abandonment of the land. 



A further disadvantage is the increased cost of irrigation due 

 to building works large enough to divert and transport large quanti- 

 ties of water which not only serve no useful purpose but do positive 

 harm. 



A general statement of the total amount of loss of water must 

 be made and accepted with reservation. It would appear that in the 

 the main canals from 15 per cent to 40 per cent is lost, and in the 

 laterals as much more. It would thus appear that not much over 

 one-half, certainly not over two-thirds of the water taken from the 

 stream, reaches the fields. In the most favorable aspect, the loss is 

 great, and is relatively greatest when the loss can be least afforded, 

 viz. : when the water is low and the ditches are running with reduced 

 heads. 



It is evident that these losses can be prevented by carrying the 

 water in pipes, and very nearly stopped by lining canals with cement 

 concrete or cement plaster, and as the magnitude of the losses is bet- 

 ter appreciated and the value of water grows an increasing part of the 

 water supply for irrigation will be carried in this way. But at pres- 

 ent these means are too expensive for most places and most crops. 



