I06 IRRIGATION FARMING. 



in some cases be advisable, where the expense is not 

 too great, to raise the dam higher and thus increase 

 the velocity of the water' used in sluicing out the silt. 

 This will increase the efficiency of that means of 

 cleansing the reservoir. 



The removal of the accumulated debris by the 

 ordinary methods of excavation is clearly out of the 

 question. No community in the world can afford to 

 pay for an acre- foot of storage capacity for the purpose 

 of irrigation any sum approaching the cost of an acre- 

 foot of excavation by ordinary methods. A plan is 

 suggested, however, which might be applied, and when 

 properly adapted to the topography and hydrography 

 of the locality would be effe(5live at reasonable expense: 

 A small water supply is to be obtained at considerable 

 head over the reservoir site, either by diverting the 

 stream at a distance above the reservoir or by storing 

 waters in a small reservoir on the stream or some of its 

 tributaries and carrying them in pipes or flumes above 

 the upper edge of the reservoir to the vicinity of the 

 dam. At points along the side of the reservoir which 

 are topographically favorable, preferably upon ridges 

 jutting out into the lake, hydraulic giants are to be 

 provided to adl under the head of water furnished by 

 the pipe-line. Large sluiceways are to be provided near 

 the dam, and at such times as the reservoir happens to be 

 empty these sluiceways are to be opened to their full 

 capacity and the deposited material hydraulicked out, 

 as in hydraulic mining. The material, being mostly 

 fine and freshly deposited, would wash easily and rap- 

 idly and be carried by the stream out of the reservoir 

 through the sluice-gates. This water need not be 



