WATER RESOURCES OF ORANGE COUNTY 55
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Drainage area: 1418 sq. mi.
Average flow: 1379 cfs
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LW-FLOW FREQUENCY
Figure 22. Low-flow frequencies for St. Johns River near Christmas.
is overlain by a thin aquiclude (impervious formation) through which there is considerable leakage. In addition, there are many wells heavily pumped for irrigation, and the excess water flows through drainage ditches to the St. Johns River. Many artesian wells flow wild along the banks of the river. Consequently, during extended droughts the mineral content of the water in the St. Johns River above the Wekiva River approaches that of the highly mineralized artesian water.
The water in the St. Johns River was very highly mineralized during the drought in the spring and early summer of 1962. Figure 23 shows a chloride profile of the river from headwaters to Green Cove Springs from May 29 to October 24, 1962. This extended reach of the river is shown for comparative purposes. Figure 23