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<br />- ~'Ol) <br />"J '- <br /> <br />44 <br /> <br />METROPOLITAN W,~TER DISTRICT <br /> <br />examination. From points in the distribution system 687 samples <br />were taken for chemical analysis and 5,383 were collected for sani. I <br />tary control. The observation and control of plankton growths in <br />the various District reservoirs required the microscopical examina- I <br />tion of 1,411 samples. The practice of spot treatment with copper .. <br />sulfate to control scattered growths in the reservoirs was continued, <br />and no general treatments were required, <br />The results of bacteriological examination of Colorado River <br />water are given in table 10. From natural Colorado River water <br />the completed positive tubes in per cent of total 10 ml. tubes planted <br />were slightly less than for the preceding fiscal year. No positive <br />completed tests were obtained from the 1,825 tubes planted from <br />softened water samples, Only 24 confirmed positives were obtained <br />from the distribution system, representing less than 1/10 of one <br />per cent of the 26,915 tubes planted. <br /> <br />TABLE 6 <br /> <br />ANALYSIS OF COLORADO RIVER WATER <br /> <br />A\,t"rage for Year Ending June 30, 1949 <br /> <br /> (:OLOIIAI)O RI\'EIl W ATIo:R <br />COI'STlTlJE:>\T SYMBOL NAl'lIR"L SOFn:NlIl <br />Silica ....siO: 8.., prlll 12.2 ppm <br />Iroll ... F'~ Tc. T" <br />Cakium .......Ca 81 ,12 <br />;\lagnt'~illm :'lolg 30 n 1 <br />Sodium lInri p()la~~illm . ..NaS K 107 20;1 <br />Carhonate ..CO., 2 n I <br />Biearb(lnal~ . ....HCO" I~O 109 <br />Sulfate . ........sn, ,114 316 <br />Ch!orille CI 85 % <br />Nitrat~ NO, 0,2 .. 0,2 <br />Rurnn R 0,1 0,1 l <br />rllluride ...... F 0.;1 0.., <br />Total (li~~"I\'{'.d .~olid:-, 701 740 1 <br />Hardne5~ as CaCOJ <br />Total. 3:].1 IT] <br />Carbnnale 119 III <br />NnllcurhollaLt' 21.') 22 <br />free ('urh'.1l dioxide... I() 0 <br />Hydrogen i')11 l't'lIeentralioll.. ..vII 8..1 8,8 <br />Electrical conduCliviLy ,EC,IO" 1100 1180 <br />