124 



measurement. From May to September natural losses of the river- 

 bottom vegetation were 55 per cent of all the water entering the 

 channel of the Santa Ana River in a length of l6 miles. Troxell 

 (33) estimates natural losses, combining transpiration and evapo- 

 ration, as equal to approximately 50 inches in depth annually. 



As a measure of evaporation and transpiration losses, 

 Table 38 has been compiled to show the effect of natural losses 

 on stream flow, total monthly loss in acre-feet, and monthly con- 

 sumptive use of water in acre-inches per acre. 



TABLE 38 



ESTIM/ITED NATURAL LOSSES BETWEEN RIVERSIDE NARROWS AND 



PRADO GAGING STATION, SANTA ANA RIVER, CALIF. , 



1930-31 AND 1931-32 (33) 



1930-31 



1931-32 



Month 



Mean 

 daily 



Second- 

 feet 



Monthly Per acre 



Acre- 

 feet 



Acre- 

 inches 



Mean 

 daily 



Second- 

 feet 



Monthly Per acre 



Acre- 

 feet 



Acre 



inches 



Year 



24.0 



17459 



51.84 



22.4 



16325 



48.49 



The results obtained agree in general with tank measure- 

 ments conducted by the Division of Irrigation 20 miles away near 

 Santa Ana, a general summary of which is given in Table 13. Here 

 saltgrass growing with water near the surface used 36 to 42 in- 

 ches annually. Tules and cattails represented an adjusted loss 

 of 73 inches, willows used 45 inches, and wire rush 84 inches. 



