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Water in Orange County
LEAFLET NO. 8
Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
DIVISION OF GEOLOGY
FLORIDA BOARD OF CONSERVATION
BOARD OF COUNTY COMMISSIONERS OF ORANGE COU
WATER IN ORANGE COUNTY, FLORIDA
3.F. Joyner, W.F. Lichtler, and Warren Anderson
What is the source of Orange County's
water? Where is it stored? How much is avail-
able? How good is it? How is it used? What are
present and future water problems? What can be
done to protect sources of good water? These
are some of the questions often asked about
water. Some of these questions are easy to ans-
wer; others are difficult.
WHAT IS THE SOURCE OF
ORANGE COUNTY'S WATER?
The source of all fresh water in Orange
County is rain--either on the county or on adja-
cent higher land areas. The average annual
rainfall in Orange County is 52 inches, an
average of 2,500 mgd (million gallons per day).
Normally more than half this rainfall occurs
during the 4-month rainy season from June
Water in nature constantly moves in what is
known as the hydrologic cycle. It falls from the
atmosphere as precipitation, evaporates from
the land, vegetation, and surface-water bodies,
moves over and through the ground to the lakes,
rivers, and ocean and again evaporates.
Figure 1. Rain--Source of Orange County's water.
Of the 52 inches of rain that fall on Orange
County in an average year, about 35 inches, oi
1,750 mgd, returns to the atmosphere by eva
portion from lakes, streams, and the land, anm
by transpiration from vegetation--an orange tre(
of average size transpires about 35 gallons ol
water per day. About 17 inches of rain, or 750
mgd, are left to recharge the ground-water reser
voirs and help maintain flow in streams in thE
In addition to the rainfall on Orange County,
an average of about 180 mgd flows into th(
county from Lake and Osceola counties, both i
JAN tFEB MAR APRl MAY JUNE JULY AUG SEPT OCT NOV DEC
Figure 2. Average monthly rainfall at Orlando.
streams and through the ground. About 30 mgd
is consumed by various water users within
Orange County, leaving about 900 mgd that
flows from Orange County into Seminole, Bre-
vard, and Lake counties in streams and through
WHERE IS ORANGE COUNTY'S
Orange County has enormous quantities of
water stored on the surface and in the ground.
The total amount varies somewhat from the
rainy season to the dry season and from years
of above-average rainfall and years of below-
average rainfall. However, the amount of varia-
tion is small because most of the water is
0 5 10 20 30 MILES
Figure 3. Cross section of Orange and Brovard
counties illustrating hydrologic cycle.
Stream channels in Orange County are not
deeply incised and the amount of water stored
in channels is insignificant in most streams.
Seepage of ground water to the stream channels
temporarily sustains streamflow during dry
weather, but all streams go dry or recede to
very low flow during extended droughts except
for the St. Johns River and the spring-fed Wekiva
The amount of water stored in lakes varies
considerably because lakes are subject to high
evaporation losses (about 4 feet per year),
seepage losses, and low rates of recharge
during dry weather. Levels of some lakes fluc-
tuate as little as 2 feet; others more than 20
feet. Water stored in the upper foot of the 55,000
acres of lake surface in Orange County is 18
billion gallons, enough to provide nearly 50
million gallons of water per day for a year.
The water stored in the lakes and streams
in Orange County is generally soft, and low in
mineral content, but it often is highly colored
because of dissolved organic matter.
The quantity of water stored in the ground
in Orange County is estimated at many trillion
gallons. Porous rocks which are capable o
yielding water to wells and springs are called
aquifers. The uppermost ground-water reservoir
in Orange County is the nonartesian or water-
table aquifer which is composed primarily of
quartz sand. This aquifer extends from the
water table to a depth of about 30 to 40 feet
below the land surface. The water-table aquifer
will yield small to moderate quantities of water
(5 to 20 gallons per minute) to small diameter
sand-point wells. Larger yields can be obtained
from larger diameter (over 2-inch) wells with
screens. In most parts of the county, the water
table is near the land surface and suction-type
pumps are adequate to lift the water to the
surface. However, in some areas of western
Orange County the water table is more than 10
to 15 feet below the surface and submersible
or deep-well jet pumps must be used.
Water from the water-table aquifer is gene-
rally very soft, low in mineral content, and
slightly corrosive. In some areas the water is
high in iron and/or color and may cause staining
of fixtures and surfaces wetted by sprinklers.
Shallow wells may be subject to contamination
from septic-tank effluent or other pollutants
unless the wells are located a sufficient dis-
tance from possible sources of contamination.
In areas where the aquifer is composed of
clean, coarse sand, and where wells are safe
from pollution, the water-table aquifer is a good
source of water for domestic use.
The Hawthorn Formation lies between the
water-table aquifer and the underlying Floridan
aquifer. Most of the Hawthorn Formation is
relatively impermeable clayey sand and confines
water in the underlying artesian Floridan aqui-
fer. However, in some areas, particularly east
and south of Orlando, porous layers of shell,
.sand, or gravel within the Hawthorn Formation
will yield moderate to large supplies of water.
The water levels in wells that penetrate these
zones are usually intermediate between the
water table and the water level of the Floridan
aquifer. Water in the Hawthorn Formation is
usually hard, low in color and iron, and pro-
200'- WATER ARTESIAN WELL SAND
TA ..CHARGE AREA DISCHARGE
APOPKA LAND WATER TABLE AREA
P .. .LAND L FLOWING
100' 0 R, ARTESIAN WELL A LIMESTONE
SEA RACE SAND ,AA A A
oo' AWORMATIO MARL
0 5 10 20 30 MILES
Figure 4. Block diagram of Orange County.
tected from pollution by surrounding, relatively
The principal water-storage reservoir in
Orange County is the Floridan aquifer which
underlies all of Florida and parts of Georgia,
South Carolina, and Alabama. In Orange County
this ground-water reservoir is more than 1,300
feet thick and is composed, generally, of lime-
stone and dolomitic limestone. The depth to
the top of the aquifer ranges from about 50
foot blow the land surface in parts of western
Orange County to about 350 feet in the south-
eastern part of the county. Solution channels
and pore spaces in the limestone range in dia-
meter from a fraction of an inch to more than
200 foot. Yields of 4,000 gpm (gallons per
minute) or more can usually be obtained from
large diameter (20 inches or more) wells drilled
into the Floridan aquifer.
The water in the Floridan aquifer is arto-
sian, which means it will rise above the top of
the aquifer in a penetrating well. The imaginary
surface that coincides with the water level in
a well in an artesian aquifer is called the pio-
zomotric surface. The piezometric surface
ranges from more than 100 feet below the land
surface (non-flowing areas) in high areas in the
western part of Orange County, to more than 15
DEPTH TO TOP OF FLORIDAN
AQUIFER, FEET BELOW LAND SURFACE
I 0 to 100
100 to 200
 200 to 300
I MORE THAN 300
Figure 5. Depth to top of Floridan aquifer.
0 10 M
DFPTH TO PIEZOMETRIC SURFACE,
FEET BELOW LAND SURFACE N
MORE THAN 80
60 to 80
S40 to 60
0 2 0 to 40
O to 20
i ARTESIAN FLOW AREA
0 5 tr .A
Figurt, 6. I'iezometric surface of tho Floridan aquif.
feet above the land surface (flowing areas,
the St. Johns River valley in the extreme
tern part of the county.
The piezometric surface is highest in
southwestern part of the county and sic
downward to the northeast and east. Grr
water moves down gradient in a direction gt
rally at right angles to the piozomotric cont
Sr f 1 ANI I%,I 0
,-) K) ,. r .
Figure 7. Altitude of piozomotric surface at avorag(
The mineral content of the water in the
,ridan aquifer is lowest in the western part
the county and increases toward the east.
t of the increase is due to solution of the
stone as the water moves slowly eastward
ard the sea, however, most of the increase
ably is caused by residual saline water that
red the aquifer when the sea last, covered
PARTS PER MILLION
I LESS THAN 150
F 150 300
i MORE THAN 2000
0 5 10 MILES
i .. I . ILE
lro 8. Dissolved solids in water from the Floridan
Except for the salt water in the eastern
of the county and highly colored water in
s of the water-table aquifer, ground water is
able for domestic, irrigational, and most
mistrial purposes. The principal dissolved
stituents in water in Orange County are:
Ia, calcium, magnesium, sodium, chloride,
rate, and bicarbonate.
S HOW IS WATER USED?
Use of water in Orange County is increasing
at a rapid rate. In 1965 the total use was about
100 mgd exclusive of water used for electric
power generation. About 30 mgd of the water
used was consumed--evaporated or incorporated
in a product. All water for municipal, industrial,
and domestic supplies and about half the water
Figure 9. Water use in Orange County.
used for irrigation in Orange County came from
ground-water sources--primarily the Floridad
aquifer. Total ground-water pumpage was appro
ximately 80 mgd. This amount included 11 mgc
that the City of Cocoa and vicinity including
Cape Kennedy, NASA, and Patrick Air Forc(
Base drew from ground-water reservoirs ii
eastern Orange County. The water in the Flor
idan aquifer underlying Brevard County is gen
erally too highly mineralized for most uses
Lakes and ponds in Orange County provide
water for irrigation, but the largest uses 0
surface water are for recreation and cooling fo
Photo U S. Soil Conservotion Service
Figure 10. Citrus grove irrigation in Orange County.
electric power generation. The 1,100 lakes and
ponds in the county constitute a valuable re-
source. Many are used for boating, swimming.
fishing, skiing, and other recreational activities.
They also moderate the surrounding air temper-
ature and attract a great number of tourists to
Orange County. Lakes have played a large
part in establishing Orlando's reputation as one
of the 10 most beautiful cities in the country.
Photo Orlando Area Chamber of Commerce
Figure 11. Water for recreation.
Streams in Orange County are used for
fishing, boating, and swimming; however,- most
of the streams go dry during droughts.
WHAT ARE THE WATER PROBLEMS?
In 1960 many homes were flooded by high
lake levels. In 1962 the docks of some lake-
front homes were left high and dry by low lake
levels. These extremes illustrate one of the
major surface-water problems in Orange County--
too much water during wet periods and not
enough during dry periods.
Photo U S Soil Conservotion Service
Figure 12. Flooding in 1960.
More than 300 drainage wells have been
drilled in Orange County since 1906 to drain
excess surface water and to dispose of waste.
Prior to 1950, raw sewage and citrus pulp were
put into the Floridan aquifer. Such practices
have been outlawed, but the quality of the water
entering drainage wells is not easily controlled
or regulated. Some parts of the Floridan aquifer
are still subject to pollution. Some streams and
lakes receive treatment plant effluent and other
contaminants. The continued increase in need
or water calls for increased attention to area-
vide water planning and conservation.
WHAT ABOUT THE FUTURE?
At present (1968) there is more than enough
vater entering the ground-water reservoirs in
)range County to meet all demands and to still
maintain flow in the springs and flow of ground
vater into Seminole, Brevard, and Lake coun-
;ies. If recharge to the Floridan aquifer is sig-
lificantly reduced by urbanization and by diver-
sion of water to the sea, and if water use in the
region continues to increase, increasing atten-
tion will need to be given to conservation and
water developmental measures to satisfy the
demand for fresh water.
A tremendous amount of water is stored
underground, but long-term withdrawal of more
water than enters the aquifer promotes problems.
Excessive withdrawal lowers water levels and
invites intrusion of salt water from the ocean or
from greater depths in the aquifer. Pollution of
the water also impairs its usefulness. Lowering
of artesian levels tends to promote formation of
WHAT CAN BE DONE?
Accurate information, sound planning, and
farsighted land-use management are the keys to
most of the water-management problems of
Much of the flood damage to homes and
other property can be avoided by recognizing
that lake levels naturally rise and fall in re-
sponse to variations in rainfall. If the flood
plains of lakes are kept in their natural state or
are developed in- such a manner that the develop-
ments will not be greatly harmed by high water,
damage can be minimized and water can be
saved from wet periods for use during droughts.
To do this, it is necessary to know the expected
high-water stage of the lakes and to develop
only land safe from flooding. Removal of deve-
lopment in most settled areas is probably not!
practical, but in some cases the best interests
of the county may be served by removing homes
that are subject to flooding.
Surplus surface water can be a blessing in
disguise if managed properly. Research can
probably devise an economically feasible plan
whereby surplus surface waters can be collect-
ed, treated if necessary, and then stored under-
ground for later use. Drainage wells, which
now are a hazard because of pollution, could
thus be converted into recharge wells, whicl
would preserve and enhance the water resources
of the region.
The pollution problem increases as popu.
lation density increases. However, modern me-
thods of sewage can usually purify water t(
the stage where it safely can be put underground
or into streams and lakes. In the long run, treat-
ment of waste water before it enters streams
and lakes may be less expensive than trying
to solve the problems created by pollution of
The need for water in the distant future
cannot be definitely foreseen. However, the
population will undoubtedly continue to increase
and it is safe to assume water needs will also
continue to increase until much of the available
water is used. Annual rainfall in Orange County
varies considerably--extremes are 40 inches in
1943 to 69 inches in 1960--whereas evapotrans-
piration losses remain relatively constant. One
year of above average rainfall provides many
times the volume of recharge to the water reser-
voirs than does a year of below average rainfall.
As below average years of rainfall occur mor<
than twice as frequently as above average years
(48 below and 27 above in the past 75 years of
record), the importance of the years of floods
The rolling highlands of western Orange
County absorb almost all the rainfall that does
not evaporate. Preservation of this region in its
natural state or improving its recharge capacity
is important. This can be done by guiding
uture urban and industrial expansion to the
pastern areas of the county and preserving the
western highlands for agricultural use. This
permits recharge and at the same time yields
high rate of return through agri-business.
Surface drainage is sluggish in the eastern
art of the county because of the flat terrain,
nd downward movement of water is slow be-
;ause of the relatively impermeable sub-strata.
Vater control must be provided before this area
man be developed. If excess surface water is
collected treated, and allowed to recharge
;he Floridan aquifer through wells, water sup-
)lies will increase, the danger of salt-water
intrusion will decrease, and development of the
irea will be aided. Collection, treatment, and
storage of all excess surface water in the county
nay not now be feasible, but such a goal is
EMERGENCY WATER SUPPLIES?
Citizens of Orange County need not be
overly concerned with contamination of the
ground-water supply by radioactive fallout
except those whose wells are subject to con-
tamination by drainage wells. The water stored
underground is protected from immediate con-
tamination, whereas the water above ground
in streams and lakes would be immediately
exposed to radioactive fallout. The artesian
aquifer is at least 50 feet below land surface
and would probably not be contaminated. Water
taken directly from an uncontaminated artesian
well would be safe to drink during or after radio-
HOW WAS THE WATER
The measurement of Orange County's water
resources involves many complex operations.
The services of experienced geologists, engi-
neers, and chemists were necessary to measure
and study the many variables in water quantity,
quality, and movement.
In order to obtain information on Orange
County's underground water, many existing
wells were studied and tested and where neces-
sary test wells were drilled. Drill cuttings were
examined and water samples were analyzed for
their chemical content. Water levels were mea-
sured to determine seasonal and long-term
changes and pumping tests were conducted
to obtain a knowledge of the ability of the aqui-
fers to transmit and store water. The amount
of water stored in the aquifers was estimated
using geologic and well and pumping-test infor-
The quantity and quality of surface water
changes more rapidly and frequently than the
quantity and quality of ground water. Continuous
records or many measurements of the physical
and chemical characteristics of streams and
lakes are necessary in order to obtain extremes,
frequencies, and averages.
The stage (water level) of some streams in
the county was measured continuously; and,
for some streams and lakes, periodic stage
measurements were made. Several stream dis-
charge measurements were made at each gaging
site and a stage-discharge relation was defined.
By using a continuous record of stage and the
stage-discharge relation, a continuous discharge
Many water samples from streams and lakes
were analyzed for dissolved chemical consti-
tuents in order to define the ranges, trends, and
averages in water quality.
WHERE CAN MORE INFORMATION
Additional information on the water re-
sources of Orange County is contained in the
followingg reports of the Florida Geological
survey prepared by the U.S. Geological Survey
In cooperation with Orange County and the
divisionn of Geology, Florida Board of Conserva-
Ground Water conditions in Orlando and vicinity,
Florida: Fla. Geological Survey Report of Inv. No.
5, by A.G. Unklesbay.
Interim Report on the Water Resources of Orange
County, Florida: Fla. Geological Survey Inf. Circ.
No. 41, by W.F. Lichtler, Warren Anderson, and
B.F. Joyner, 1964.
Water Resources of Orange County, Florida:
Fla. Geological Survey Report of Inv. No. 50, by
W.F. Lichtler, Warren Anderson, and B.F. Joyner,
SControl of Lake Levels in .Orange County,
Florida: Fla. Geological Survey Inf. Circ. No. 47,
by Warren Anderson, W.F. Lichtler, and B.F. Joyner,
Availability of Ground Water in Orange County,
Florida: Fla. Geological Survey Map Series No.
21, by W.F. Lichtler and B.F. Joyner, 1966.
Availability and quality of surface water in
Orange County, Florida: Fla. Geological Survey
Map Series No. 24, by Warren Anderson and Boyd
F. Joyner, 1966.
Water Resources records of Orange County,
Florida: Fla. Geological Survey Inf. Circ. No. --
by W.F. Lichtler, Warren Anderson, and B.F. Joyner,
Surface and quality of water records of Florida:
prepared annually by the U.S. Geological Survey.
FLRD GEOLOSk ( IC SUfRiW
[year of publication as printed] Florida Geological Survey [source text]
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