IRRIGATION AND DRAINAGE 



all kinds of crops. This amount of water, if none were lost, would 

 cover each acre to a depth of 1.9 feet. In other words, the duty 

 of water is a trifle less than 2 acre-feet per acre. 



In 1908 the depth of water used on a 2i|-acre apple orchard 

 at Wenatchee, Washington, was measured and found to be 

 23 inches. The trees were seven years old and produced heavily. 

 This orchard was watered five times, the first time on May 13 

 and the last on September 23. In San Diego County, California, 

 1 miner's inch (-^ of a cubic foot per second) irrigates from 6 to 

 7 acres near the coast, where the air is cool and evaporation low, 

 but twenty miles or more inland the same amount of water is 

 needed for about 4 acres. 



On the sandy loam orchards of Orange County, California, it 

 has been demonstrated that 2 acre-inches every sixty days is 

 insufficient to keep bearing trees in good condition. The rain- 

 fall of this locality averages less than 12 inches per annum, but 

 about 95 per cent of the total falls between November and May, 

 inclusive. 



The most reliable, and in many ways the most valuable, records 

 pertaining to duty of water for orchards have been obtained by the 

 water companies of Riverside County, California. Here more or 

 less irrigation water is used every month of the year. 



WATER USED UNDER THE RIVERSIDE WATER COMPANY'S 

 SYSTEM (1901-1908) 



Average Depth pek 

 Acre in Feet 



Average Rainfall 

 in Feet 



Total Water applied 

 in Feet 



December . 

 January . . 

 February . 

 March . . 

 April . . . 

 May . . . 

 June . . . 

 July . . . 

 August . . 

 September 

 October . . 

 November . 

 Total . 



: 59 



123 

 .046 

 .078 

 177 

 291 

 274 

 -7- 

 269 

 243 

 189 

 169 

 29 



0.109 

 .170 

 .190 

 .316 

 .068 

 .023 

 .003 



.015 

 ■043 

 •073 

 [.01 



.268 



•293 

 .236 

 •394 

 .245 



•3M 



.277 

 .274 

 .269 

 .258 

 .232 

 •242 

 •30 



