170 



DIVISION OF WATER KESOURCES 



PLATE XI 



WATER SUPPLY 



of 



SANTA ANA RIVER 



above 



PRADO GAGING STATION 



1932 



In order to show more clearly the disposition of all the rising- 

 water above Prado, Table 5 was prepared. This table shows the esti- 

 mated water supply above the Prado gaging station for two seasons, 

 1930-31 and 1931-32. The natural losses were computed, based on the 

 evaporation pan record collected at Prado, except for three months, 

 October, 1930, and February and May. 1932. During these months 

 the record at Prado was incomplete. For the month of October, 1930, 

 the record collected by the Bureau of Agricultural Engineering at 

 Santa Ana was used. The record collected by the same bureau at 

 Pomona was used for the months of February and May, 1932. 



During the season of 1930-31 there was very little storm run-off 

 due to rainfall, consequently the main source of the water passing the 

 Prado gaging station was from the ground water inflow. Table 5 shows 

 that of the 74,900 acre-feet of inflow into the area above Prado for this 

 season, 17,500 acre-feet, or 23.4 per cent, were consumed by the natural 

 losses in this area. 



If the water of the Santa Ana River is more A^aluable at any one 

 period of the year than another, it is during the summer irrigation 

 season. During this period the entire flow of the river is diverted by 

 the Santa Ana Valley Irrigation and Anaheim Union water companies. 

 To augment this supply additional water is pumped along the canal 

 systems in Orange County. An inspection of Table 5 shows that for 

 the months of ]\Iay to September, 18,090 acre-feet entered the valley 

 or flood channel of the Santa Ana River between Riverside Narrows 

 and Prado during the season of 1930-31. Of these 18,090 acre-feet, 

 10,180 acre-feet were consumed by natural losses. This represents a 

 loss of 56 per cent. For the same period during 1931-32, 18,280 acre- 

 feet entered the flood channel of the river. During this season 9790 

 acre-feet were consumed by natural losses, or a loss of 54 per cent. 



