156 



THE IRRIGATION AGE. 



high during the season. In 1915, with the larger 

 equipment in place, the flooding was resumed in 

 March and continued throughout April, covering 

 about the same ground as before and for about the 

 same period. The water used in flooding was not 

 measured. 



The pump discharge for each week during the 

 seasons of 1915 and 1916 is shown in the follow- 

 ing table : 



Fig. 8 Sodium salts in surface foot. Percentage of decrease and 

 amount and percentage remaining after one and two years' drainage. 



1915 



Week ending Gals. 



Mar. 27.... 5,480,000 



April 3.... 6,790,000 



" 10.... 8,780,000 



" 17.... 10,240,000 



" 24. ... 9,500,000* 



1 .... 9,500,000* 



8.... 9,700,000 



15.... 7,620,000 



22.... 8,290.000 



29. ... 7,810,000 



5.... 8,330,000 



12.... 7,350,000 



19. ... 6,220,000 



26.... 5,360,000 



3.... 4,710,000 



10.... 4,870,000 



17.... 6.300.000 



24.... 5,390,000 



31 4,440,000 



7.... 3.500.000 



14.... 2,630,000 



21.... 1,630,000 

 28. ... 420,000 

 4.... 850,000 



May 



June 



July 



Aug. 



Sept. 



Total 145,710,000 



operation 3,921 hours out of a total of 4,056 hours, 

 or 96.6 per cent of the time between April 10 and 

 September 25, discharging 159,966,000 gallons, or 

 1.51 cubic feet per second. 



In 1915 the maximum weekly discharge oc- 

 curred during the week of April 17, when 10,240,000 

 gallons were pumped during 160 hours, or an equiva- 

 lent of 2.38 cubic feet per second. During 1916 the 

 maximum discharge occurred during the week end- 

 ing April 30, when there were 9,900- 

 000 gallons pumped during 165 hours, 

 or 2.23 cubic feet per second. 



The increased discharge in 1916 

 is due to the pumping season being 

 lengthened by a late irrigation, in 

 order to facilitate preparing the land 

 for the 1917 crop. 



Figures 6 and 7 show the depth 

 to water from March to September 

 inclusive for 1914, 1915 and 1916. 

 These observations were made by 

 weekly reading on test wells located 

 midway between laterals and 450 feet 

 from the main drain. Numbers 1 to 

 4 are located east of the main line and 

 numbers 5 to 8 west of the main line. 

 (See Fig. 2.) 



The irregularities in the curves show the effect 

 of flooding in the vicinity of the test well. The 

 effect of the irrigation which the grain received in 

 April, 1916, is shown quite plainly in all of the 

 wells by the rise in the water table. 



Estimated. 



tPump not running. 



1915 discharge equals 447.7 acre 



1916 discharge equals 500.1 acre 



Total ....162,984,000 



feet, or 8.79 acre-feet over 160 acres, 

 feet, or 3.12 acre-feet over 160 acres. 



During 1915 the pump was in actual operation 

 3,534 hours out of the total of 3,648 hours, or 96.8 

 per cent of the time between March 22 and August 

 20. discharging 144,440,000 gallons, or 1.52 cubic feet 

 per second. During 1916 the pump was in actual 



Fig. 9 Distribution of sodium salts through a six-foot soil column in 



1915. 



