46                    FLORIDA GEOLOGICAL SURVEY


       1961 j                        1962                    D     1963
         DEC JAN FED MAR   PR      JIJ JL AUG  SE"   OCT NOV DEC  JAN



  4500:




  4000



  3500

z
2
._ 300                         Vis volume of fresh water thot has flowed Into Joke
      .since spillway overflow began

.                              V- vokme of the lake at spillway elevation
2500


z
  .2(00 '



U 1500




   1000



   500



      I       --  : t.        "      I              =                .
         1  2  3  4  5  6  7  8  .9 10 II  12 13 14 15 16 17 18 19 20 21 v,/V0

 Figure 27. Graph showing the relation of chloride in water in Deer Point Lake to fresh water inflow.


 Florida. That is: (1) rainfall is the source of all the water even though some falls outside the basin and moves into the basin underground;
 (2) the surface materials are highly porous, unconsolidated sands;
 (3) it is underlain by the artesian Floridan aquifer; and (4) water leaves the basin by streanflow, evaporation, transpiration, underground flow to the ocean and other basins, and by consumptive use.
     There are four physiographic divisions within the basin that affect the surface drainage and the water storage, both above and