WATER LOSSES FROM WET AREAS 109 



Also, the seasonal rainfall prior to the two growing seasons 

 differed. The rainfall for the year ju-ior to the 1931 season was 15.31 

 inches at San Bernardino and 2S.98 inches at Alpine. For the year 

 prior to the 1932 season it was 21.96 inches at San Bernardino and 

 55.83 inches at Alpine. The increase in rainfall varies from over 40 

 per cent during the second year at San Bernardino to over 90 per cent 

 at Alpine. The Coldwater Canyon watershed lies between the two, but 

 closer to Alpine and the average rainfall over the watershed was per- 

 haps 70 per cent greater in the 1931-32 rainy season than it was in 

 1930-31. 



As a result of the greater rainfall in the 1931-32 season, the 

 stream flow was sustained at a much greater volume in 1932 than in 

 1931. The flow during the spring months was beyond the capacity of 

 the flumes installed and it was not deemed advisable to make the large 

 additional outlay necessary to measure the larger flows accurately. 

 For this reason and also because of possible complications resulting 

 from side inflow, records were not started in 1932 until June 24. 

 Inflow from the east branch Avas measured from June 24 to July 9 at 

 the branch control, which was on bedrock, but no more water passed 

 the control after that date. A survey of the main canyon at that 

 time showed no surface indications of springs between the middle and 

 lower controls. 



However, during the period from July 26 to August 19, 1932, 

 there is evidence that there was some underground inflow between the 

 middle and lower controls. That this was the ease during a part of this 

 period is shown by the greater daily maximum discharges at the lower 

 control than at the middle control for some of the dates for the period, 

 as shown in Table 36. 



To evaluate this underground inflow during the period between 

 July 26 and August 19, 1932, the differences in daily maximum dis- 

 charges at the controls in question were compared with the maximum 

 temperature recorded at San Bernardino on the preceding day, using 

 all values during 1932 except the period in question. This showed that 

 the amount of water charged to side inflow increased slowly and uni- 

 formly until about August 11, after which it dropped off quite rapidly. 

 The daily loss between the middle and lower controls Avas corrected 

 accordingly from July 26 to August 19. On nine days during this 

 period, the side inflow was sufficient to make the daily maximum dis- 

 charges slightly higher at the lower control than at the middle control. 

 However, the measured flow at the lower control was never at any 

 time as great as the flow at the upper control. 



In. 1931 the lowest dail}^ maximum discharge at the lower control 

 was 0.210 second-foot on August 26, and the absolute minimum flow 

 was 0.002 second-foot during several days in August. In the following 

 year the lowest daily maximum discharge at the same control was but 

 0.320 second-foot on September 8, and the absolute minimum flow was 

 but 0.013 on the same date. On October 17, 1931, the last date on 

 which measurements were taken in that season, the daily maximum 

 discharge at the lower control was 0.380 second-foot with a daily mini- 

 mum discharge of 0.258 second-foot, while on the same date a year 

 later the daily maximum discharge had recovered to 0.487 second-foot 

 with a daily minimum discharge of 0.379 second-foot. 



