Title: Safe and Adequate - And You Drink It
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Title: Safe and Adequate - And You Drink It
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Language: English
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Spatial Coverage: North America -- United States of America -- Florida
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Abstract: Richard Hamann's Collection - Safe and Adequate - And You Drink It
General Note: Box 12, Folder 1 ( Materials and Reports on Florida's Water Resources - 1945 - 1957 ), Item 20
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Safe and Adequate---and You Drink It

by
ROBERT 0. VERNON*


S Florida has had a rash of too much unfavorable
k publicity on its water supply. Over the past few years
several articles have appeared in magazines having
S nationwide circulation. One of these was entitled
S "Foul-and You Drink It." These articles attempted
to prove that our public water supplies were not fit
S to drink and that the state was facing an acute shortage
S of water. Much editorial comment followed the pub-
lication of these articles, both pro and con, and ap-
parently much was said by people who didn't have all
the facts.
To anyone familiar with the ground-water resources
of Florida and of the nation, these articles were mon-
strous misstatements of facts. It was obvious that the
authors, in their remarks on Florida, were writing
about subjects of which they had little knowledge and
their statements undoubtedly alarmed some of our
citizens unduly. The Florida Geological Survey, in
cooperation with the U. S. Geological Survey, has
gathered and published a great quantity of data on
the water resources of Florida and adjacent states
which are available from its offices.
S Florida stands at the top in the nation in resources
in water, being blessed by an abundant rainfall. There
are adequate supplies for both additional industry and
agriculture. The water is sweet, pure and potable,
requiring as a rule no treatment except for normal
health precautions. It is true that in a few areas
some trouble is experienced in obtaining water be-
cause of low formation yield and that some areas along
the coast have not spaced wells wisely and have with-
drawn water from the aquifer too rapidly, allowing
salt water from the ocean to contaminate the well
fields. Some of our rocks contain entrapped salt water
which may be flushed out in wells and in addition the
levels of ground water in wells have been decreased in
some areas because of overdevelopment. A wise and
controlled usage is strongly recommended for these
areas, but elsewhere there is an abundance of water.
Our wealth of water is obtained entirely from a
rainfall that averages about 53 inches annually over
the state. This rainfall is the income upon which the
state has to live. If more water is used than falls on
Florida, a draft must be made on our savings account,
the water stored in the lakes and underground forma-
tions, and when this is exhausted, the state is bank-
rupt.

*Assistant Director, Florida Geological Survey


The state, except for a portion of the panhandle
and the northern peninsula, does not depend for its
water supply upon any rain that falls on other states.
Certainly, none of our water comes from West Vir-
ginia and other northern states as has been reported.
The peninsula, south of Marion County, must depend
entirely upon the rain that falls upon the peninsula.
The responsibility of how we use the water, whether
wisely or unwisely, rests directly upon the citizens of
the state.

Subsurface water
All of the natural waters contained in the voids and
interstices of the rocks below the land surface are
called subsurface waters, regardless of their origin.
This includes soil moisture, water in the capillary
voids, water moving from the land surface to the top
of the ground water level that marks the top of
saturation of all the voids in the rocks; and this water
as it moves laterally and vertically to the ground sur-
face as seepages and springs.
One classification of subsurface water is shown in
Figure I. The zone of aeration and the zone of satura-
tion are the two large physical divisions of subsurface
water, the separation being made at the water table


Figure 1.-Classification of subsurface water.









below which all of the permeable interstices are filled
with water and above which the interstices contain
both water and air. The zone of aeration is separable
into three sub-zones; the belt of soil water, the inter-
mediate vadose belt and the capillary fringe belt.
The belt of soil water is the upper zone from which
water is discharged into the atmosphere by plant
transpiration and by evaporation. Most subsurface
water passes through this zone into the intermediate
vadose belt beyond recall by the roots of plants, on its
way down to the zone of saturation. There are large
quantities of water in dead storage in the vadose zone,
either sinking slowly downward drawn by gravity to
the underlying zone of saturation or drawn by molecu-
lar attraction into the capillary fringe. The thickness
of this belt may be several feet in fine-grained clastics
and the zone can be identified in wells because the
walls are noticeably wet through the belt, but no
water is delivered into the well until the water table
is penetrated.
That portion of the subsurface water named the
zone of saturation on Figure 1, where all the pores of
the rock are filled by water, is also called ground water
and the upper surface of saturation is called the water
table. The belt of saturation may exist as a ground
water, held by an impervious layer perched in the
zone of aeration, with a second water table below it;
in which case it is a perched water table (see Figure 1).
This belt more commonly is a uniform zone of satura-
tion filling all of the interstices of the rock from the
base of porosity, deep within the earth, upwards to
the water table. The surface of the water table con-
forms rather generally with the configuration of the
earth surface, and generally the water table intersects


APPROXIMATE TOP OF

THE FLORIDAN AQUIFER


THE TOP OF THE FIRST POROUS
LIMESTONE AS PENETRATED
IN WELLS
1E AREAS IN WHICH THE AQUICLUDE IS ABSENT AND
THE AQUIFER LIES RELATIVELY NEAR THE
GROUND SURFACE


Figure 2.-The configuration of the top of the Floridan aquifer
with the limits of the aquiclude shaded.


the water levels in streams, ponds and lakes. Where
the water table is free to rise and fall with rainfall
and is not confined, it is said to be under water-table
conditions.
In some cases the ground water may fill interstices
in rock that lies below a relatively impervious forma-
tion, called an aquiclude, being trapped below this
(see Figure 1). The water table may be higher in some
parts of such an aquifer than in others, in which case
the water is under pressure and is said to be artesian.
A knowledge of the depth to the water table is
important since it determines the depth of wells, the
setting of pumps and when measurements of the ele-
vations of the water table are referred to sea level and
plotted on a map, they provide a reliable method
of determining the direction of flow, areas of recharge,
areas of discharge, and they assist in the solutions of
ground water problems. Ground water is the inter-
mediate course of rainfall traveling through the earth
to its eventual destination-the sea, and the zone of
saturation forms a series of huge reservoirs that con-
tribute water to natural surface drainages and which
can be tapped by wells.
In Florida about 93 per cent of the ground water
used in agriculture, industry, municipal and domestic
supplies is derived from artesian waters. Therefore,
much of the remainder of this discussion will be on
artesian waters.

The Floridan Aquifer
The state is blessed by having one of the most
permeable and prolific artesian aquifers in the world,
from which most of Florida's water supply is derived.
The Floridan aquifer, the name applied to this large
artesian reservoir, includes limestones of Cretaceous
to Miocene ages that are subsurface formations be-
neath the southern portions of South Carolina, Georgia
and Alabama, and all of Florida except for the west-
ernmost panhandle. The formations yielding these
copious supplies of potable and high-quality ground
water, underlie these states to depths of several thou-
sand feet. At some places the formations making up
the aquifer are exposed (see Figure 2) but generally
the top of the aquifer lies several hundred feet beneath
the ground surface.
The approximate shape of the top of the aquifer
is reproduced by Figure 2, representing the altitude of
the top of the porous limestone section, as penetrated
by wells. This is a very irregular surface that crosses
geologic formations and time markers and is erosional,
being deeply pitted by erosional hills, valleys and sinks
such as those in Polk County and by structural troughs
and highs such as the deep depression in Osceola


I -


































OLIGOCENE E 0 C E
CRETAC

Figure 3.-Greatly fore-shortened cross section
County. Much of this surface is covered by sandstones,
sands, dense limestone and clays which make up the
impervious cover, called an aquiclude, beneath which
the artesian water is held. Recharge occurs where the
aquifer is exposed and also through this cover by
means of sinkholes that breach the cover. Principal
recharge areas are present in Polk, Pasco and Clay
counties.
Along the Ocala uplift, striking northwest-south-
east in the western part of peninsular Florida, and in
Jackson and adjacent counties of panhandle Florida,
the formations making up the aquifer are exposed.
A sharp escarpment marking the limits of the aqui-
clude around the Ocala uplift and in panhandle
Florida is shown in Figure 2.
The formations composing the Floridan aquifer
are known to extend to more than 5,000 ft. in some
parts of Florida and cavities in the limestone have
been recorded at depths greater than 8,000 ft., but
there they are filled by salt water. The aquifer is
composed principally of a large porous mass of lime-
stones, with horizontal permeability much greater
than of the vertical. For simplicity, let us visualize that
Sin this porosity there has been developed over geo-
logic time a large bubble of fresh water and, along the
coasts and in the southern Peninsula, heavily mineral-
ized water under artesian pressure. This bubble of
artesian water is floating upon salty water, in part
more saline than sea water, and the shape of the


N E OUGOCENE MIOCENE PLIO-PLEISTOCENe
EOUS

n through Florida extending down the peninsula.
bubble is bi-convex, the altitude of the top surface
governing the altitude of the bottom surface. In
general, the depth at any point on the land surface to
the fresh water-salt water contact is approximately
40 times the artesian pressure measured at that point
expressed in feet above sea level.

Cross Section Through Florida
Figure 3 is a very generalized north-south cross
section through the state. The principal artesian
aquifer is made up of the limestone formations of
Cretaceous, Eocene, Oligocene, and low Miocene ages.
Over most of the peninsula the artesian aquifer is
confined by impervious members of the Hawthorn
formation, but along the section in Marion County,
it is exposed (see Figures 2 and 3). The aquiclude,
composed of dense sediments of the Hawthorn forma-
tion of Miocene age, not only confines the water in
flowing areas, but also prevents or retards recharge.
However, in Polk County, and also in other areas to
the north, sinkholes formed by the collapse of solution
channels in the limestone have displaced the Haw-
thorn, creating channels through which recharge may
occur. The recharge has built up the piezometric
surface to the north and south. Water, therefore,
moves down the slope of the piezometric surface across
formation boundaries to supply the copious flow of
springs and discharge to wells.








One noteworthy result of the relationship of dis-
charge to recharge in the artesian system is the dif-
ference in artesian pressure at different depths. In
an area of recharge, water levels are generally higher
in the upper limestone formations than in the lower
ones. In discharge areas, the converse is true. That
is why in Levy County, an area of discharge, deeper
wells will flow, whereas shallower ones will not.

The Piezometric Surface
The shape of the mass of artesian water can be
partially illustrated by Figure 4. This map is a
piezometric surface made up of lines that connect
points of equal artesian pressure as measured in wells
that penetrate the Floridan aquifer. It is constructed
by measuring the water levels or pressures and con-
verting these to heights above sea level and locating
the position of the well accurately upon a map of


Florida. Smooth lines running through points of equal
pressure complete the map. A map of the elevations
on the water table or of the artesian pressures such as
Figure 4 is fundamental to determining the basic water
facts of any area.
The map of the piezometric surface of artesian
water in Florida is not the same as the water table,
which is, as previously noted, the upper surface of
the zone of saturation. The piezometric surface exists
only in scattered wells that penetrate the artesian
aquifer and in the imagination of those who work
with it. Although largely imaginary, it has a very
material significance. It represents the height to which
water will rise in wells that penetrate the artesian lime-
stone formations in Florida.
Some questions, such as what is the practical sig-
nificance of the piezometric surface? or what does it
tell us that a study of the geology does not? may have


PIEZOMETRIC SURFACE OF


FLORIDA WITH AREAS OF


PROBABLE FLOW SHADED


AMsI MMI


Figure 4.-The piezometric surface of the artesian aquifer with areas of flow shaded.

38









occurred to you. Just such questions have been raised
by geologists who were of the opinion that a thorough
study of the geology along with a few water-level
measurements would indicate the areas of recharge,
discharge and direction of flow. These questions may
be answered rather adequately by the experience in
Florida.
Prior to about 1934 or 1935, it was understood
that the artesian water in Florida conformed with the
ordinary text book concepts. In other words, it was
generally understood that the artesian formations were
recharged principally where they crop out in Marion
County, and that the water flowed down the dip.
About 1934, an investigation of the artesian water
waH begun. That investigation, like the ones today,
wa' a cooperative enterprise of the Florida Geological
Sure\ and the iJ. S. Geological Survey. Mr. V. T.
Stringheld, of the U. S. Geological Survey, was as-
signed to the investigation and he began immediately
to map the piezometric surface. Working with him
\as a man by the name of Westendick. Stringfield
began measuring water levels and artesian pressures
along the east coast while Westendick worked in cen-
tral Florida. It wasn't long before Westendick began to
report water levels in Polk County that were higher
than those in Marion County, where the recharge was
supposed to occur. This was most surprising. Water
ob\ iousl\ could not be flowing up a hydraulic gradient
and. furthermore, it did not seem likely that there
could be recharge in Polk County, inasmuch as the
artesian limestones were covered with several hundred
feet oL impervious clays of the Hawthorn formation.
So stringield began looking for an explanation. One
man -uggested that the high levels in Polk County
occulied as a result of water entering the formations
in the highlands of Georgia and flowing through
formations deeply buried at Marion County, but this
didn't seem to be likely or possible.
The solution came when Stringfield discovered a
log ot a % ell which had been drilled in a dry sinkhole
near Da\enport. The log showed that from the sur-
face ot the ground down to the limestone, nothing
but petrmeable sand was penetrated. The solution was
then readily apparent. Recharge to the formations
was occurring through the thousands of sinkholes that
occur in the highlands of Polk County. When the map
was completed, it revealed the presence of other re-
charge areas in Florida; one in Pasco County, one at
the southwest corner of Clay County, and a small one
in Putnam and Volusia counties. It revealed also that
the area around Marion County, instead of being a
recharge area, was essentially one of discharge. The
springs ot the area have lowered the artesian pressure
here, creating a saddle in the piezometric surface. The


springs are fed by recharge in the two recharge areas
directly north and south of Marion County.
The piezometric map is an aid in determining the
direction of flow of the artesian water through the
aquifer which acts as an effective conduit over all of
Florida. In those areas, such as the center of penin-
sula Florida, where the contours are high, it can be
assumed that water is entering the aquifer and is flow-
ing down gradient from that area to areas where the
contours are low. Heavy discharge is occurring along
the valleys, saddles and low places in the piezometric
map. Most of the large artesian springs of Florida
are located in the saddle that crosses the peninsula
just north of the high recharge area. Please note the
large valley made in the piezometric surface that ex-
tends up the valley of the Suwannee River. All along
this river numerous artesian springs are discharging
water into the valley.
The U. S. Geological Survey has computed that the
minimum flow of the Suwannee River increases from
621.8 million gallons per day at Ellaville to 1,788.5
million gallons per day upstream from Wannee. Along
this course of the river the only surface stream that
feeds the Suwannee is the Santa Fe with a minimum
discharge of 429.5 million gallons per day. Since it
is known that the Santa Fe is almost entirely spring
fed it can be assumed that the increase in discharge
down the Suwannee River is a result of discharge of
water from the artesian aquifer from thousands of
springs along the Suwannee and Santa Fe river valleys.
Entering the aquifer at recharge areas, the water
may pass beneath the impervious beds of the aquiclude
which confines the water under hydraulic head as it
moves down gradient in the aquifer. In areas where
the ground surface is lower than the piezometric sur-
face, the water will have sufficient head to flow from
wells that puncture the confining beds and penetrate
the aquifer. Flowing wells can be obtained over
about one-third of the state as shown in Figure 4.

Springs
Florida has seventeen first magnitude springs (a
flow of 64.6 million gallons per day or larger)-more
than any other state or foreign country. At least 100
named springs are known, most of which are fed by
artesian water. It is interesting to consider for a mom-
ment what about these springs might interest various
professions; the water works supervisor for example.
The mean flow of Rainbow Springs over the last
fifteen years has been about 700 cu. ft. per second.
That amounts to about 450 million gallons of water
daily. The City of Miami'uses about one-tenth of that
amount, and the spring could more than supply all
the industries and municipalities in Florida. It would









just about supply drinking water for all the people of
the world.
A geologist might be more interested in another fea-
ture of the spring-its function as an excavator. We
are all familiar with the role played by the solution of
limestone in the development of Florida geology. We
are inclined to view the solution process as an ex-
tremely slow one, as, of course, it is. However, the
quantities of limestone carried away by solution in
our larger springs is apt to be surprising. For example,
140 tons of limestone is removed by the water from
Rainbow Springs in each 24-hour period. Three times
this much-450 tons a day-is carried away by Silver
Springs, not because the flow is much greater, but
because the water is harder. Stated differently, 450
tons of limestone would fill a room 30 ft. long, 20 ft.
wide, and 10 ft. high and over a period of ten years
the limestone would cover a square mile of area to a
depth of one foot.

Quality of Water
Deep wells drilled for oil have generally penetrated
very salty water over most of the state. This water is
commonly much saltier than sea water and from these
scattered records, it has been inferred that the entire
state is underlain by these heavily mineralized waters
and that the fresh artesian water is floating upon the
salty water.
During the geologic past, sea water has covered
Florida many times and under the pressure of the
raised water level salt water has permeated the lime-
stones underlying the state. Some hydrologists believe
that much of the artesian aquifer (see Figure 5) is
salty because of these invasions of sea water and that
this salt water is now being flushed out of the aquifer
by high hydraulic pressures of fresh water built up in
recharge areas of the artesian system. Presumably with
time all of these entrapped salt waters will be flushed
out and the entire aquifer will contain fresh water.
Commonly the ground water closely adjacent to
the water table is soft and may contain some iron, but
where the aquifer is limestone, the water is harder, but
never as hard as artesian water.
Artesian water varies greatly in total hardness and
in chemical content. In recharge areas it may be as
little as 100 parts per million, but increases in pro-
portion to the distance away from the recharge. Hard-
ness of the water is caused primarily by magnesium and
calcium bicarbonate, dissolved from the dolomites and
limestones of the aquifer. Rain water is soft and filled
with natural acids and as it enters the limestone aquifer
and travels through it, more and more of the rock is
dissolved and upon discharge the water may contain


several hundred parts per million dissolved solids.
Where heavily mineralized waters are present in
areas along the eastern Atlantic Coast and the Southern
Peninsula of Florida, well supplies are developed in
shallow aquifers under water table conditions. The
Southern Peninsula ground surface is composed of
very permeable limestones of Pleistocene and Miocene
ages and the water supply is believed to be adequate
for the large cities of the area. However, the eastern
Atlantic area must depend on very shallow aquifers of
limited distribution and an expansion of the present
water supply must be sought in adjacent inland areas
where surface of artesian waters can be utilized.

Consumption of Ground Water
The average daily use of ground water in Florida is
estimated to exceed 625 million gallons per day with
about 40 per cent used for industry, 32 per cent for
public water supplies, 20 per cent for agriculture and
8 per cent for domestic supplies.
To the "doom peddlers," the heavy draft of 625
million gallons of water per day from our ground water
would seem to be excessive. These people do not
consider the very large capacities of the state's elaborate
and extensive artesian aquifer. There should be no
alarm over these necessary uses, especially when the
natural drainages from the aquifer in the form of
fresh water springs, of which Florida has a great num-
ber, exceeds three and one-half billion gallons of
water per day. This is about seven times the total yield
of ground water from wells for all uses in the state.
About the only use made of this water is for recreation.
For most of the state which obtains its water from
the ground, there are four conservation problems.


AREA OF HIGHLY
MINERALIZED ARTESIAN
WATER


Figure 5.-Areas of Florida having heavily mineralized waters in
the Floridan aquifer.









First, many wells are allowed to flow freely or the
casing is so rotted as to be ineffective, and the water
is put to no beneficial use. Senate Bill No. 57 (Florida
Statutes 370.052 and 370.054) would help in com-
bating this problem in that it required that all flowing
wells be equipped with a valve, but, unfortunately,
no funds were appropriated for enforcing or ad-
ministering the law. Such funds should be made avail-
able since the loss of water from flowing wells is large
and has undoubtedly contributed in some areas to salt-
water pollution and to lowered water levels. Secondly,
large withdrawals of water from wells along the coastal
areas has resulted in the invasion of well fields by salt
water. Miami, Panama City, Tampa and St. Peters-
burg have all had to relocate their fields for this cause.
Thirdly, some areas, particularly Orlando, formerly
disposed of their sewage into the same limestone from
which they took their water, resulting in pollution
of the water supply and the development of large sup-
plies of underground sewage gas. This practice is
now forbidden by a State Sanitary Code, but sufficient
sewage and citrus wastes have been drained into some
of the limestone areas so that the decomposition is
producing enough gas to allow its use in homes. Sev-
eral homes in Orlando obtain their entire supply from
their individual wells. Further, a developing use of
water in air conditioning is taking a large draft of
water. This water should be circulated out of the
ground through the air conditioner and back into the
Ground or tremendous withdrawals will result.
Finally, when our forefathers came to America they
found a virgin land and settled it. They immediately
began to erect legal boundaries-township, county,
state-and to establish legal controls of commodities.
The fundamental of all conservation is that the natural
laws of water pay no heed to political boundaries, and
conservation practiced within one state or county
cannot solve water problems. The effort must be a
coordinated program, probably achieved through nat-
ional and state legislation.


In summary:
1. The larger part of Florida has abundant, pure,
sweet water.
2. In those few areas having trouble, some control
over wells should be established:
a. Wildly flowing wells should be equipped with
valves and abandoned wells should be
plugged where no longer needed.
b. Spacing should be scientifically determined
by pumping tests.
c. Water should be reused where possible.
d. The people in the area should be educated to
their responsibility.
Conservation, as practiced in the state, bears a
striking resemblance to the newcomer to Tallahassee
who visited several churches seeking one to attend
regularly. Finally, the visitor came to a little church
and entered as the congregation was reading respon-
sively:
We have left undone those things which ought to
have been done.
"We have done those things which should have
been left undone."
He was heard to mutter as he sat down on a pew,
"My crowd at last!"

Acknowledgements
The Florida Geological Survey has cooperated with
the U. S. Geological Survey for many years in water
resource studies. From this association a bibliography
of several hundred papers has been prepared and
published. Much of the information given in this
paper is a summary and condensation of the results of
these cooperative studies. The writer has drawn freely
from the discussions, notes, papers and published works
of members of the U. S. Geological Survey, particularly
from those of H. H. Cooper, Jr., and V. T. Stringfield.


I IIII __~ ___-- __- -- .




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