WATER RESOURCES OF ORANGE COUNTY 57
TABLE 9. CHEMICAL ANALYSES OF ST. JOHNS RIVER WATER, JUNE 7, 1962.
Analysis State Highway State Highway State Highway
(ppm) 520 50 16
Chloride 900 1,150 2,050 Sodium 454 606 1,270 Sulfate 150 248 315 Calcium 136 160 196 Magnesium 56 77 79 Hardness 570 716 814
As indicated by figure 23, the quality of the water in the headwaters improves early with increased flow, but remains poor downstream until the highly mineralized water stored in the lakes is flushed out. The chloride concentrations in the water on October 24, 1962 indicate that most of the highly mineralized water was flushed from the river.
Figure 24 shows a cumulative frequency curve of specific conductance of the water-the percent of time the specific
400
200 -W
U
w
60
20
S40---U05 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 995 999 99.99
PERCENT OF TIME SPECIFIC CONDUCTANCE WAS EQUALED OR EXCEEDED
Figure 24. Cumulative frequency curve for specific conductance of the
St. Johns River near Cocoa, October 1953 September 1963.