FLORIDA GEOLOGICAL SURVEY


and northeastern boundaries. Water levels declined about 5 feet in
discharge areas (Hillsborough and Kissimmee River basins)
because the ground-water discharge is relatively uniform regardless
of seasonal variations in rainfall. Water levels declined less than 5
feet in the interior of the Green Swamp because there was little
local pumpage and the rainfall during the dry period was about
enough to balance the outflow; therefore, the aquifer remained
relatively full.
 The area surrounding the Green Swamp is more populated and
developed and increased pumping during the dry period (1962)
caused a greater decline in piezometric levels than would have
occurred under natural conditions. If there had been no appreciable
increase in pumping, the map could be used to detect areal changes
in the hydraulic characteristics of the aquifer, particularly changes
in permeability.
 The northernmost extent of an area of heavy pumping for
mining, industrial, municipal, and irrigational supplies is in the
vicinity of Lakeland where the water levels declined about 20 feet.
The drawdown is confined to the southern boundary of Green
Swamp, suggesting that the area of the sinkhole-riddled ridges
around southern Green Swamp is a recharge area. Water levels
declined between 10 and 20 feet on the western side of Green
Swamp in the vicinity of Dade City. This is considered to be an
area of high permeability and good recharge. Water levels declined
about 10 feet in the northeastern area which is also considered to
be an area of high permeability and good recharge.
 The general conclusion is that increase in discharge (natural
or pumping) does not appreciably increase the lateral movement
of ground water from the interior of Green Swamp but does affect
the border areas.

 HYDRAULICS OF THE FLORIDAN AQUIFER

 Coefficients of horizontal and vertical permeability were
determined for selected core samples of the limestones that
comprise the Floridan aquifer. The samples were obtained from
well 805-154-8, located just north of Lake Parker. The laboratory
determinations are presented in table 9. The permeability values
ranged from 0.0001 to 19 gpd/ft2. The specific yields ranged from
0.2 to 23.2 percent. However, the specific yield determined in the
laboratory represents that of the rock sample and not of the aquifer
as confined.