WATER RESOURCES OF ORANGE COUNTY 127
prevent the formation of deep cones of influence and retard the upward movement of salty water.
Because the salt water in the aquifer in Orange County is apparently residual rather than direct encroachment from the ocean, there is a finite amount present and it is gradually being removed by natural flow in the aquifer. The quality of the water should improve naturally as the salty water is discharged and replaced by fresh water from the recharge area. However, considering the great thickness and areal extent of the aquifer, the amount of salty water in storage, and the slow rate of movement of the water, thousands of years may have to elapse before any freshening is noticed. The freshening process possibly could be speeded by putting a line of wells along the St. Johns River that were cased deep into the lower salty zone. If these wells were allowed to flow or were pumped, they would rmove some of the salty water and increase the flow of fresh water from the recharge area. However, the cost of such an operation would be high, the disposal of the salty water would be a problem, and the rate and amount of improvement are unknown. A comprehensive analysis of the economics and hydrologic practicality of such a project would have to be made.
The question, "will pumping in the eastern part of the county increase the danger of salt-water intrusion in the Orlando area?", is of interest to the residents of the Orlando area. Pumping in the eastern part of Orange County might cause an increase in the salt content of the water in the vicinity of the pumped wells and possibly even cause some salt-water intrusion in areas east of the well field, but it is unlikely to adversely affect the quality of ground water in areas to the west of the well field. The natural gradient of the piezometric surface in Orange County is toward the east (fig. 47) and salt water in the eastern part of the county would have to flow up gradient to reach the Orlando area. Pumping in the eastern part of the county increases the natural gradient and further decreases the possibility of salt water reaching Orlando. An exception to this would be if water levels throughout Orange County were lowered to the extent that salt water that might be at depth in the aquifer could move upward in response to the Ghyben-Herzberg principal (See page 124). However, if this should happen, the wells in the eastern part of the county would probably become too salty for use long before the Orlando area was affected.