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~. \ i j l I .; I ~. I ~ t ., .." r':'C" ~ ,.....; , . OPERATION A:-:D M.AINTENANCE 41 Agricultl.l-ral lI~((ter investigal:ions Field and greenhouse studies concerning the effects of treated and untreated Colorado River water on the growth of agricultural and ornamental plants have been continued_ The tolerance of camel- lia. hyacinth. and tuli)l'to soil salinity was investigated using sand culture techniques_ The camellia test work is not completed, but the hyacinth and tulip showed a marked tolerance to saline con- ditions. In the irrigation experiment conducted in cooperation with the University of California on a 13.5-acre section of the District orange groves at La Verne. the trees have been irrigated since 1942 with natural and softened Colorado River water and local well water. Yields have been good for all three sections of the grove_ During the past season a slIlall difference was observed for the crop of Wash- ington navel oranges irrigated with softened Colorado River water, but no difference was noted for the Valencia orange yield_ With the introduction of Colorado River water into San Diego County, numerous inquiries arose regarding the probable effects of the natural water on agricultural and ornamental plants in that area_ The accumulated experience gained from District investiga- tions and field observations over a period of six years enabled the staff to answer these questions with assurance. The educational pro- gram to assist both commercial and amateur growers with horticul- tural problems was continued by lectures in San Diego County and personal interviews in other District areas_ Some 250 soil and leaf samples were collected and analyzed in order to interpret the results of experiments. QuaWy of Cohn'ado Rivl'r 1Voter An average analysis of Colorado River water as received at and delivered from the softening and filtration plant during the fiscal year 1947-48 is given in table 6_ The quality of natural water by months is gi,'en in table 7 and the quality of the softened water by months in table 8. Due to the increased hardness of the softened water released du,'ing the periods of peak flow through the soften- ing plant. the average hardness of the finished water for the year was 138 parts per million. which is slightly higher than the desired 125 parts per million. In table 9 are given data on the operation of the zeolite softeners. The further decrease in the quantity of salt required pel' part of hardness removed is the result of the use in softener operation of a greater proportion of the beds containing new zeoli te.