CHAPTER VI. 

 CANAL CONSTRUCTION. 



WATER is king, and the most important adjunc5l 

 _^« to the greater requirements of irrigation is a 

 ^^1 good canal system. The gravity supply of 

 water is by all odds the best that can be 

 employed, and the farmer who has a good ditch in per- 

 fect working order may consider that he has a fortune 

 lying at his threshold. In laying out a system of 

 ditches for a farm, use care and time. Think it over 

 well, and it may be economy to employ a hydraulic 

 engineer to run levels and determine grades. No large 

 canal system should be undertaken without consulting 

 an expert engineer. Each farm to a certain extent 

 requires a ditch system adapted to its peculiar topog- 

 raphy, soil, and crops. See to it that the water can 

 get off the land as well as on it. Remember at all times 

 that drainage is quite as necessary to successful irriga- 

 tion as the water-supply itself. The matter of grade 

 for a ditch is one which depends so much upon circum- 

 stances as almost to preclude rules. It is safe, how- 

 ever, to make the grades as light as possible to avoid 

 ' ' silting up " or settling. Cutting may be called per- 

 petual motion, for if once begun it seems never to stop. 

 The ditch gradually gets lower and lower until the 

 water cannot be got out of it at all, and it must either 

 be abandoned or have falls built in it to keep the flow 



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