Title: Letter from William F. Guyton to SWFWMD
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00051377/00001
 Material Information
Title: Letter from William F. Guyton to SWFWMD
Alternate Title: Letter from William F. Guyton to SWFWMD reporting on the evidence at the hearing of Dec. 1, 1968, to determine the need for a water regulatory district in the area of Pinellas-Anclote, Northwest Hillsborough, Hillsborough, Pithlachascootee, and Green Swam
Physical Description: Book
Language: English
Spatial Coverage: North America -- United States of America -- Florida
General Note: Box 3, Folder 2 ( SWFWMD (R) HISTORY - LAWS, RULES FIRST ORDERS - B3F2 ), Item 66
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: UF00051377
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text


JOSEPH K.LONGACRE March 26, 1966
a ter -

Governing Board
Southwest Florida Water Management District 7 1966
Brooksville, Florida

Gentlemen: 0o 0/f

This letter will constitute my report to you on the evidence presented
at the hearing of December 1, 1965, to determine the need for a water
regulatory district in the area of the Pinellas-Anclote, Northwest Hills-
borough, Hillsborough, Pithlachascootee, and Green Swamp Basins. In
accordance with your instructions, I attended the hearing and listened to
the verbal testimony. I also have studied the transcript of the testimony
and the exhibits which were introduced.

Most of the verbal testimony at the hearing dealt only with the
northwest Hillsborough County northeast Pinellas County locality, but
some of it covered a wider area and a number of the U. S. Geological
Survey reports which were introduced as exhibits are concerned with other
parts of the area included in the hearing.

The following is a summary of the principal hydrologic conclusions
presented at the hearing with respect to various existing and possible
problems. This summary represents my interpretation of the statements
and evidence presented but does not include my opinions with respect to
these matters, which will be presented later in this letter.


Depletion /

Taking the word "depletion" in the context of exhaustion or use
exceeding yield, the record shows no depletion up to this time of the water
resources anywhere in the area covered by the hearing. The record c\vs
that there is no shortage of water in the area now nor is one likely to dc\elop
in the near future. The record does show, however, that at some time in
the more distant future water demands will develop to such an extent that
local shortages may occur.


Salt-Water Encroachment

The U. S. Geological Survey reports show that serious salt-water
encroachment has occurred in much of Pinellas County and in the vicinity
of Tampa. It was generally agreed at the hearing that there is no evidence
of present salt-water encroachment in the northwest Hillsborough County -
northeast Pinellas County locality. There seemed to be no disagreement,
however, that there could be salt-water encroachment in this locality at
some future time as a result of greatly increased pumping, although no one
has presumed to state at what pumping rate this might occur. The U. S.
Geological Survey reports state that the only way to prevent salt-water
encroachment along the west side of the area covered by the hearing is to
limit the amount of pumping but they do not say to what rates. It is generally
agreed that adequate information is not available to make this determination.

Drawdown of Piezometric Surface Caused by Pumping

It is generally agreed that the drawdown of the piezometric surface
(and artesian water levels in wells) is the natural result of pumping from
the artesian aquifer. The testimony also is in agreement that the cone of
depression resulting from pumping at a given point is widespread and
extends over many square miles. It also is agreed, however, that these
drawdowns are of moderate amount and do not make it impossible to obtain
water from the artesian aquifer but simply make it necessary to pump the
water from a somewhat greater depth and possibly in some cases to have
deeper wells.

Lowering of Lake Levels

Mr. Andrews concluded that the levels of some of the lakes in the
vicinity of the St. Petersburg Lutz Field, and particularly Round Lake, are
affected by pumping from artesian wells; and a number of affidavits were
presented by persons claiming that their lake levels had declined concurrent-
ly with the increase in pumping by St. Petersburg. U. S. Geological Survey
reports indicate that some lakes in the area covered by the hearing are con-
nected to varying degrees with the artesian aquifer. Mr. Brashears showed&
that lake levels in the vicinity of the Cosme Well Field appear to be regulated
chiefly by the amount and rate of rainfall in the area rather than by change
in pumpage from the artesian aquifer. He did not make such a direct and
positive statement with respect to the lakes in the vicinity of the Lutz Field,
nor did he say that there is no connection between any of the lakes and the
artesian aquifer. Dr. Garcia-Bengochea did not testify concerning this


Increased Iron Content in Water from Wells

Mr. Andrews pointed out that the iron content in the water from a
number of wells in the Lutz area has increased since the beginning of pump-
ing at the Lutz Field. There are a number of affidavits from land owners in
this regard. Mr. Andrews did not claim that the iron is a direct result of
increased pumping, but he stated that it might be. There is no other evidence
in the record on this matter.

Sink Holes

The question of increased incidence of sink holes in the vicinity of
new well fields was handled in the same manner as the iron problem. Affi-
davits were presented by landowners in the vicinity of the Lutz Field that a
number of sink holes had occurred concurrently with the increase in pumping
in the Lutz locality, and Mr. Andrews discussed this as a possible problem
resulting from heavy pumping. The matter is not covered in any other
manner in the record.

Lowering of Water Table in Shallow Aquifer

Two landowners gave affidavits that they have had to irrigate their
citrus groves more since municipal well fields were installed in their
localities. This would infer a lowering of the water table in the shallow
aquifer as a result of the pumping from the well fields. Testimony pre-
sented by Mr. Brashears and the U. S. Geological Survey indicate no
measurable influence on the water table in the shallow aquifer in the Cosme
locality and the Lutz locality as a result of.pumping from the artesian
aquifer. The U. S. Geological Survey reports, however, infer that there
is a small connection in the general area between the water in the shallow
aquifer and that in the artesian aquifer and that thus there should be some
leakage from the shallow aquifer into the artesian aquifer when the piezo-
metric surface is drawn down.


In summary, the evidence indicates the following.

1i. No present danger of exhaustion of water resources in the
area and none likely in the near future. Possible demand
for more water than available in some localities in the
more distant future.

v--- - -~~~"I -_


2. Serious salt-water encroachment in the past in much of
Pinellas County and in the Tampa locality. No major salt-
water encroachment elsewhere in the area covered by the
hearing. No evidence yet of any salt-water encroachment
in northwest Hillsborough County northeast Pinellas County
locality, and none expected in the near future. Possibly
will be some new salt-water encroachment in the area in
the future as pumping rates continue to grow, but informa-
tion concerning pumping rates that could be sustained without
salt-water encroachment not available.

3. Small to moderate, widespread drawdowns of piezometric
surface (and artesian water levels in wells) are created by
pumping from artesian aquifer.

4. There probably is some relation between some lake levels
and the piezometric surface, but number of lakes affected
by changes in piezometric surface and magnitudes of effects

5. The iron content of water from some wells has increased and
some new sink holes have developed in the vicinity of the
Lutz Field. It is suspected that this is the result of the
decline of piezometric surface caused principally by pumping
from the field, but no direct evidence is available to prove this.

6. No directly measurable changes have been shown in the water
table in the shallow aquifer as a result of changes in the
piezometric surface. Instead, all tests have shown other-
wise. However, it is believed that there is a small degree
of connection between the water in the shallow aquifer and
the water in the artesian aquifer.

The above represents the best summary I can make of the evidence
as I understand it. I have attempted to keep it unclouded by my own opinions
and independent review of the water resources in the area. The following
sections' of this letter, however, present my own opinions with respect to
these matter s.



Depletion and Salt-Water Encroachment

I see no immediate problem with respect to depletion or salt-water
encroachment in the northwest Hillsborough County northeast Pinellas
County locality. There appears to be considerably more water available
than is now being used. Perhaps someday a problem of salt-water encroach-
ment may occur in this locality but probably not until the pumping rates
become considerably larger than at present. It will be a relatively long
and costly process to develop complete enough information on the ground-
water resources to determine how much ground water can be pumped in
any locality and in the area as a whole without salt-water encroachment.

Drawdown of Piezometric Surface

The pumping of every well in the area which draws from the artesian
aquifer causes some drawdown of the piezometric surface. In each locality
of similar hydrology, the amount of the drawdown caused by each well is
roughly proportional to the rate of pumping, and the spread of each cone of
depression is roughly the same regardless of the pumping rate. Each cone
of depression covers a widespread area of many square miles. Thus, there
is some drawdown from municipal wells, some from domestic wells, some
from irrigation wells, and some from industrial wells. The total measured
drawdown at any point is the cumulative effect of all. The only way to avoid
additional drawdown of the piezometric surface would be to prohibit any
increase in pumping from the aquifer. I do not believe that any reasonable
spacing of wells or limitation on pumpage per unit area would be a satis-
factory solution because of the widespread nature of each cone of depression.
It would smooth out the drawdown in some very small localities, but the
overall drawdown effects would be about the same for the same total pumpage.
The only way to eliminate the drawdown which has already occurred would be
to go back to a state of nature and cease all pumping.

Lowering of Lake Levels

While many and perhaps most lakes are relatively unaffected by
changes in the piezometric surface, I believe that many other lakes are
affected by such changes, the amounts of lake lowering ranging from a very
small and almost imperceptible amount up to the total amount of lowering
of the piezometric surface. Because of the tightness of the bottoms of most
of the lakes, however, the percentage of the affected lakes which will have


proportionately large declines of levels in relation to the declines of the
piezometric surface probably is small. I know of no way to prevent such
lowering of lake levels, because it will be the natural result of the lower-
ing of the piezometric surface; and I know of no way to prevent this without
prohibiting increases in pumping.

Iron Problems

I believe that the iron content of the water from some of the shallow
domestic wells has increased as a result of the decline in the piezometric
surface. I do not know the exact mechanism causing this change, but the
evidence appears too extensive to say that the changes have not occurred.
On the other hand, the solution to this problem may be relatively simple,
involving only casing and cementing the wells to a slightly deeper level in
the artesian aquifer or perhaps only setting the pumps deeper,in existing
wells. Also, the removal of iron from water normally is a relatively
simple treatment process.

Sink Holes

I do not doubt that the development of some sink holes has been
triggered by the decline in the piezometric surface. As the piezometric
surface is lowered, the supporting effect of the water on the overlying rock
is decreased and the limestone must carry a greater proportion of the weight,
which permits collapse at points already weak from previous solution. This
should be only a hastening of an occurrence which would in time have hap-
pened anyway, however; and after the initial effects are felt, sink holes
should not continue to occur at an accelerated rate.

Lowering of Water Table in Shallow Aquifer

As in the case of the lowering of the artesian water levels and of
some lake levels, I see no way to avoid some lowering of the water table
in the shallow aquifer. It should be noted, however, that not only does
pumping from the artesian aquifer cause this, but also that drainage ditches
and flood control measures affect the shallow water table, lake levels, and *
piezometric surface and would have to be prohibited if an original state of
nature were to be maintained.

Hydrologic Boundaries

There is apparently no complete barrier to the flow of ground water
from any part of the Southwest Florida Water Management District to any


adjacent part. Thus, there is no firm requirement to use ground-water
flowlines as the boundaries of a hydrologic unit -- even if they were known
with certainty, which they are not -- because these flowlines are subject
to changes resulting from changes in ground-water use and physical changes
in the recharge areas. Therefore, if hydrologic units are to be selected
which are smaller than the entire Southwest Florida Water Management
District, I believe theyahould be selected on the basis of surface-water
drainage areas and present and anticipated water use and water management
problems. Thus, next to the District boundaries, the use of basin boundaries
probably would be the most reasonable alternative, I would not consider it
necessary to include the Green Swamp Basin in any hydrologic unit selected
simply because of previous reports that this is the area in which most of the
recharge originates. In the first place, the Green Swamp is not necessarily
the area of greatest recharge; and in the second place, any development of
ground water in the Green Swamp Basin would not necessarily affect water
levels in an adjacent basin any more than would development of ground water
from an adjoining basin to the north or south.

Possible Regulations

From a hydrologic standpoint, the only regulations which I believe
would be practical at this time would be those dealing with the filing of well
records and with well construction standards. The primary well construc-
tion standards which might be justified would be those designed to prevent
salt-water contamination caused by improper casing and plugging procedures,
to prevent surface pollution, and to eliminate safety hazards. As stated
above, because of the widespread nature of the cones of depression, I see
no practical way to prevent the decline of the piezometric surface and
artesian water levels by well spacing or restriction of the amount of pumpage
per unit area. Also, because of lack of knowledge concerning the amount of
pumping that should be permitted, it would seem unreasonable at this time
to limit the total amount of pumping in an area on account of a fear of salt-
water encroachment.

Preponderance of Evidence

From a hydrologic standpoint, I see no clear-cut preponderance of
evidence to indicate whether a water regulatory district should be established.
There seems to be no great need for a water regulatory district now from the
standpoint of exhaustion or destruction of water resources, but it is true that
some minor economic problems are being created as a result of the use of
the water resources. Also, in part of the area covered by the hearing,
particularly Pinellas County, a serious water resource problem of salt-water


encroachment has occurred in the past and there is a possibility that similar
problems will develop in the future in other parts of the area as the use of
water increases. Sufficient information is not available at this time for
selecting regulations to safeguard the water resources in this respect, how-
ever, without the possibility and even the likelihood of unduly restricting

Sincerely yours,

William F. Guyton



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