43 



four sets appears in the following tabulation, which, represents 



the 3 years 1929-30 to 1931-32: 



Average depth to water table Vater used 



Inches Inches 



12 42.76 



24 1/35.31 



36 i/23.79 



48 13.37 



Saltgrass is an indicator of ground water, but this inves- 

 tigation has demonstrated that its consumptive use is not exces- 

 sive when compared with water requirements of many other plants. 

 As the depth to water increases consumptive use decreases. Thus, 

 at a depth of 1 foot the quantity of water used in 1 year equalled 

 42.76 inches; at 2 feet, 35.31 inches; and at 4 feet, 13.37 inches. 

 The depth-use ratio plots almost as a straight line. 



In most saltgrass areas in the Santa Ana basin the depth to 

 water table exceeds 4 feet and the average seasonal draft on the 

 ground water is not excessive. Monthly and seasonal data on use 

 of water by saltgrass in the Santa Ana River basin are given in 

 Table 3. 



Wire rush . --Wire rush ( June us balticus ) was transplanted 

 into a tank in which the water level was held at a depth of 2 feet. 

 With a plentiful water supply close to the roots, growth became 

 dense and the demand for water increased in the second year to a 

 total of 13.75 inches for the month of July. For the 12-month 

 period ending November 30, 1931, the annual consumptive use of 

 water by wire rush was 93.58 inches. Wire rush thus used more 

 than 2.5 times the saltgrass requirement. Monthly use of water 

 by wire rush is shown in Table 4. 



Willow . --Investigation of the consumptive use of water by 

 red willow was begun at the Santa Ana station in 1930 and contin- 

 ued for two seasons. During much of the second year, however, 

 the willow was in poor condition and early in the season became 

 partly defoliated. For this period consumptive use data are 



17 For 11 months only; May omitted. 



