FLORIDA GEOLOGICAL SURVEY


few feet of sand to the water table. Ground water then moves laterally
and discharges into Pensacola Bay or Santa Rosa Sound. The water in
the upper part of the sand-and-gravel aquifer is under nonartesian con-
ditions, and the water level rises rapidly after intense rainfall and de-
clines slowly during prolonged periods without rain. The hydrograph of
well 021-709-8 shows the response of the water level to rainfall. Pump-
ing from nearby wells also had an influence on the water level in this
well. Wells owned by the Santa Rosa Island Authority were pumped at
rates of about 60,000 gpd during the winter and about 120,000 gpd dur-
ing the summer from 1951 to 1956. After 1956, when the pumping from
these wells ceased and rainfall was above average, the water level rose
gradually to a record high in 1959. From the high water level in late
1959 to mid 1962, the water level declined about 6 feet.
 The hydrograph of water levels in well 021-709-8 and the monthly
rainfall at Pensacola for 1959 shows the rapid rise of the water level that
resulted from intense rainfall. The water level changed only slightly
until heavy rains in September caused a rise of 2.5 feet. Additional heavy
rains in October caused rises totaling about 4 feet. A total of almost 30
inches of rain fell in Pensacola in September and October 1959. These
rises brought the water table near or above the land surface in some areas
around Gulf Breeze, causing some damage and considerable incon-
venience.
 The 1954 hydrograph in figure 38 illustrates a decline of the water
level during a year of low rainfall. In 1954, Pensacola had the lowest
rainfall of record, 28.68 inches. The water level at Gulf Breeze declined
6.2 feet during this year. The water level declined 5.7 feet from January
to September and remained less than 2 feet above sea level until the
end of the year. The ground-water table received very little recharge
from rainfall in 1954. Most of the rain was lost through evapotranspira-
ion.

 TEMPERATURE OF GROUND WATER
 The temperature of the earth's crust increases with depth at the rate
 of about 10F. for each 50 to 100 feet. The temperature of ground water
 generally increases with depth at approximately the same rate.
 Ground-water temperatures in Escambia and Santa Rosa counties
 from the sand-and-gravel aquifer 50 to 250 feet deep usually range from
 66' to 730F. These temperatures reflect the average annual air tempera-
 ture (680) at Pensacola and the geothermal gradient.
 The temperature of water from the upper limestone of the Floridan