Title: Letter: Water Crop Theory
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 Material Information
Title: Letter: Water Crop Theory
Physical Description: Book
Language: English
 Subjects
Spatial Coverage: North America -- United States of America -- Florida
 Notes
Abstract: Letter: Water Crop Theory, To: Rod Cherry From: David Pyne, Enlcosed article, 8/30/1973
General Note: Box 10, Folder 12 ( SF Water Rights-Water Crop - 1973, 1976-77 ), Item 39
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00002275
Volume ID: VID00001
Source Institution: Levin College of Law, 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
I rI^.^ 0- -0 *



"3 BLACK, CROW & EIDSErSS, Is C.
C k CONSULTING ENGINEERS
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sOCA RATON. rLOIOA/NAOtLS. rLonIOA/SAN JOSC.COSTA siCA P. 0 041647 s 4c- g-* l
WILMINoTON, OCLAWARE CAsLE AooRCSS. BCEGNVFLA HOUSTON. TCXAS TWX *SC *8S21-9
August 30, 1973




Mr. Rod Cherry p* V3/-
Southwiest Florida Water Management District
Post Office Box 457 : J. J 0
Brooksville, Florida 33512 ;CA -Gi *4 ~40 ***. A"t%.cc

Re: Water Crop Theory 44.(t4V64 Al I '/34
/74-6. a^-..s. a5^0-9a --7W ^
Dear Rod: ./
We believe that last Tuesday's meeting between the District's
hydrologic staff and our own, was most worthwhile. In general it
appears that we are in agreement on the hydrologic aspects of the
water crop theory, although some differences remain concerning the
utilization of this tool for regulating consumptive withdrawal from
wells or well fields. We are optimistic that we can work together to
improve the tools available for well field regulation, utilizing the
water crop theory as a guide.

In order to establish a baseline for further discussions the
following comments represent our understanding of the conclusions
reached at the Tuesday meeting.

Water Crop Theory

1. A. water budget analysis for the Middle Gulf area indicates that
a consumptive withdrawal of 860, 000 gpd/square mile uniformly over
the whole area is theoretically available. This should only be considered
as a guide since precipitation, hydrologic, geologic and other variations
over the area may suggest greater or lesser withdrawals at specific
-, sites. It is unlikely that such variations by themselves would justify
changing the above uniform estimate by +50%.

2. An increase in the water crop due to reduced evapotranspiration
losses, if adopted as a management objective, would probably not
increase the water crop substantially. Theoretically a reduction in ET


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Mr. Rod Cherry
Water Crop Theory
Page two


loss by 25% (about 10 inches of rainfall) would increase the water crop
to about 1, 500, 000 gpd/sm. Actually this would be difficult to achieve.
One million od/sm is perhaps a more realistic upper liit, on a .. y
uniformrnwithrawa basis. '

3.. Maintenance of minimum streamflow-duration relationships,
if adopted as a management objective, would reduce the water crop in
direct proportion to the degree of constraint .imposed by the objectives.

4. We are in agreement on the hydrological aspects of the water
crop derivation, and have a mutual understanding of the precision of ,
the results.

Regulation of Consumptive Withdrawal

5. The District's hydrologic staff proposes that the District utilizes
the water crop theory for regulation of consumptive withdrawal, with the
.proviso that whenever the water user can show to the satisfaction of the
Governing Board and staff that- withdrawal in excess of the water crop
is causing no adverse effect upon the utilization of surrounding property,
or that any such adverse effect is to be compensated by the water user,
then such excess withdrawal may be permitted.

6. No resolution has yet been determined as to how much water
can be withdrawn from a single well along a right-of-way, with essentially
no surrounding well field property. Withdrawal wwould-probably be tA.
based upon existing consumptive use within the adjacent square miles.

7. Regulation of withdrawal based upon the water crop theory does
not provide a well-defined mechanism for determining who withdraws
water in a given area in a competitive situation. Water resources
maIageent will increasingly require allocation decis s based upon
prioritis and current law, which provides for reasonabe beneficial
use consistent with the public interest. This is a tough problem that
must be faced, and one that may best be resolved after the establishment /
of a water-supply authority.

8. We understand that the District hydrological staff concur with
our belief that the localized dewatering of the sands around a well or
well field is an ecological, not a hydrological, consideration, and that


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Mr. Rod Cherry
Water Crop Theory
Page three


such localized dewatering, with appropriate compensation as per Item 5
if necessary, should be permissible."

9. Black, Crow and Eidsness, Inc. concurs with the three-phase
Approach to regulation of withdrawals, namely:

1. Estimate yield
2. Refine estimate with pumping test data
3. Regulate according to performance --

We also concur with the four Actors propped for consideration n
estimating yields, namely thbvater crop, salt water intrusion, sink
hole development and economic distress. The last item should be
pertinent within the cone of depression defined by a decline of three
feet in the potentiometric surface, although, in our opinion, it does not
necessarily follow that economic distress occurs automatically at any 0c1
point within this area. Each claim should be evaluated separately.

These nine points represent what we believe to have been the
key points discussed in the meeting. In addition we wish to offer the
following comments.

Regulation according to Paragraph Five is an acceptable starting
point, however it allows very wide flexibility in the degree to which the
Governing Board may permit or restrict withdrawals. The Board-
should be provided as soon as possible with a more clearly defined set
of regulation criteria, such that the value judgement component in the ,4,*r t"
regulation decision can be reduced to a reasonable level. Such criterialw.
would also permit water users to estimate in advance the allowable .
withdrawal in a given area. The only tool for such an estimate at the .
present time is the water crop theory, which we believe will generally.
indicate withdrawals less than those "necessary for economic and /.
efficient utilization, for a purpose and in a manner which is both '
reasonable and consistent with the public interest. (Water Resources
Act of 1972). We will be happy to work with you in the development
of such criteria, particularly if they could be developed in time for
presentation at the October Board meeting.

A second point for your consideration is our concern that the
District should adopt a regulation and allocation police tlat is not








Mr. Rod Cherry
Water Crop Theory
Page four


related to land ownership. The Water Resources Act of 1972 provides
or "reasonable beneficial use ... consistent with the pblic interest. "
As the demand for water increases, the belief that water belongs to
the overlying landowner is being heard more frequently, particularly
within Pasco County. We believe that support of that interpretation
of the law may ease water management decisions at the expense of the
public interest. We encourage the District to adopt a more progressive
interpretation of the law, by which water is allocated according o
a formua hashed upon priorities and needs, with provision for compensate
to landowners sustaining adverse effects oth' than "loss of water
.Jj rigs. Such a rogressiv uld, in our opinion, be
facilitated by the creation of a water supply authority, and would
constitute a sound basis for regional water resources management.

We are most encouraged by the progress that has been made \
within the past few months toward the goal of effective, regional water
resources management. Our meeting last Tuesday represents another
S milestone along that path. Although there will undoubtedly be further
successes and setbacks, we wish to assure you of our firm commitment .
to this goal and our intent to actively support all measures consistent
with progress in that direction. We look forward to working closely
with you and your staff in the achievement of this goal.

.j .* ,- Very truly yours,

S_ BLACK, CROW AND EIDSNESS, INC.





RDGP/mfl

cc: Mr. J. I.. Garcia-Bengochea
Mr. Jack Suddath -- .



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only necessary to estimate width on bais of
tributary drainage area, flow regimen, and general
knowledge of the geographic setting of the streams
under consideration.
Evaporation rates used are shown in figure 11.
Meyers' study indicates that lakes, reservoirs, and
ponds cover only -53,000 acres of the approximately
8,170,000 acres in the Delaware River basin. This
area amounts to about 0.6 percent of the area of the
basin from which an average of 135,000 acre-feet of
water evaporates annually. Swamps cover about
94,000 acres in the basin, which is. approximately 1.2
percent of the area; the average'annual evaporation
from these swamps is 251,000 acre-feet. Perennial
stream have a total surface area in the basin of about
41,000 acres, or 0.5 percent. From the surface of these
streams the computed annual average evaporation is
107,000 acre-feet. The total area of fresh-water surface
in the basin is about 188,000 acres, or 2.3 percent
and the average annual evaporation is 493,000 acre-
feet, or about 3.2 percent of the water loss. The total
fresh-water area in New Jersey east of the basin is
about 217,000 acres, or 7 percent of the total land area,
and the average annual evaporation is 618,000 acre-feet.
The parts of these losses that occur during the growing
season can be estimated from figure 11 if consideration
ia given to the extent of deep-water bodies and to heat
storage.
The quantity of water lost by evaporation from ex-
posed-water surfaces in the Delaware River basin is less
than 2 percent of the total precipitation in the basiu and
lIes than 4 percent of the total runoff. Losses by evap-
oration from water surfaces alone are relatively insig-
nificant in comparison to the total of the water resources
of the basin. Nevertheless, the loss from individualres-
ervoirs may be a serious problem to the users.
Results of this study are summarized in greater detail
in table 2, pages 26-30.
TBANsPmRATION
Transpiration is the method by which moisture from
living cells of plants and animals is returned to the
atmosphere. However, transpiration by animals
(vapor discharge by perspiration and respiration) is
such a small fraction of the total that it is usually
neglected in water budgets, and only plant transpira-
tion is usually considered.
In a sense each plant is a water pump. Actuated by
the sun's energy, plants withdraw water from the ground
through their roots and discharge the excess water
chiefly through their leaves. Consequently, trans-
piration occurs during the daylight hours. Transpira-
tion also fluctuates seasonally; it is lowest in the winter
when plants are dormant or dead and highest during
the growing season when plant activity is at its greatest.


Direct measurement of transpiration over large areas
is not possible; indeed, measurement of transpiration
even on small controlled plots is difficult. Moreover,
evaporation from land and water surfaces and trans-
piration from the associated plant assemblages are not
easily separated; therefore, in the study of vapor dis-
charge from land areas it is usually evapotranspiration
rather than transpiration that is measured.
In some field studies the evapotranspiration lois from
shallow aquifers can be estimated from an analysis of
continuous water-level records of wells tapping these
aquifers, and in some places, especially in the drylands,
the effects of evapotranspiration on streamfiow can
be determined by analysis of meteorological and
hydrologic data. In the Delaware River basin it
has not been possible to make such estimates.
saurso AND THa WATa o0noP
"Runoff," the third term in the simplified water
budget mentioned oa page 14, is discussed in consider-
able detail on pages 103-121. From such simple budg-
et it is commonly inferred that average annual runoff
represents the potentially usable yearly water supply,
or the theoretical annual water crop. Certainly, R
is the only potentially manageable part of the water
cycle, and it is frote this that all man's water needs
must be met.
The term "watie crop" is commonly used for either
total stream discharge or water yield, which includes
net ground-water outflow. Such a concept, however,
is oversimplified for it does not take into account the
fact that part of the discharge (R) may not be recovera-
ble for use and that part of the natural evapotranspira-
tion may be recoverable. Nevertheless, the water
crop is most useful as an aid in estimating the safe
water development of a basin.
The term "water crop" is here defined as the water
from streams and aquifers that annually may be used
by man, provided that long-term withdrawals do not
exceed long-term replenishment. Floodwaters that are
not stored for future use are wasted and therefore are
not a recoverable part of the water crop. In addition
to natural limitations, man places his own limitations on
the water that can be used. Usually a large part of
the water withdrawn returns to streams or aquifers after
use and may be withdrawn again. Water diverted to
another basin does not return to the basin of its origin
and is therefore equivalent to water used consump-
tively, at least so far as the basin of origin is concerned.
The quantity of water available for withdrawal de-
pends on many variable and partly interrelated factors
among which are: (1) weather and climate; (2) physical,
characteristics of the drainage basins involved; and


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(3) economic, legal, and political aspects of water
development. Important among the factors under (3)
are the requirements for nonwithdrawal uses, such as
hydroelectric power development, dilution of wastes,
prevention of salt-water encroachment, navigation,
maintenance of fish and wildlife, and recreational uses.
The latter requirements are usually met by low or
normal streamflow. Withdrawals may be made down-
stream from places of nonwithdrawal use, but usually
some water is discharged to the ocean (or leaves the
particular region) to meet some requirement for mainte-
nance of flow; such water is not a withdrawable part
of the water crop.
The magnitude of the water crop varies from year to
year and from place to place. The variations due to
weather can be averaged over a period of years to
obtain the perennial water crop. As man's needs
increase, however, the development of ground-water
supplies and surface-storage facilities results in an
increase in the average quantity available for consump-
tive use.
For example, the water crop might be considered to
be the water available from natural (unregulated)
stramflow. The low flows of streams would then
impose limitations on the withdrawal of water and
might evdn be insufficient to meet requirements of
nonwithdrawal uses. Provision of facilities for storing
water during periods of high streamflow make it possible
to augment low flows at points downstream and to
withdraw a larger part of the total streamflow. If
sufficient storage is available for regulation complete
enough for uniform streamflow, and if no water is
required for nonwithdrawal use, the water crop is equal
to the runoff. Complete regulation, however, is seldom
possible or practical in humid regions; also advantage,
may be taken of the natural storage capacity in aquifers
by withdrawing ground water. Extensive ground-
water development may result in lowered water tables,
decreased evapotranspiration from ground water, de-
creased ground-water outflow, and increased space in
which flood waters may be stored. Thus, a part of the
natural water loss might be salvaged and become a part
of the water crop.
With the economic conditions that are likely to pre-
vail in the foreseeable future, the attainable perennial
water crop in the Delaware River basin probably is
considerably less than the runoff, which averages about
4.7 tgy. Even though the harvestable water crop
could be increased by water recovered from the natural
water loss, there probably always will be a great deal of
storm runoff that cannot be stored because of physical
or economic reasons. Additionally, demands for non-
withdrawal uses must be satisfied; for example, unless
a salt-water barrier of some kind is constructed to pre-


vent ocean water from moving ever farther up the
Delaware River, increasingly larger amounts of fresh
water will be required to flush the salt water seaward as
time goes on. This procedure will diminish the recover-
able water crop to the extent that fresh water is
"wasted" to the sea in the flushing action.
The runoff (which is the principal budget item
involved in the water crop) is conveniently divided
into two major parts: (1) direct runoff, which reaches
stream channels by overland flow quickly after rain or
anowmelt or by lateral percolation through surface and
subsurface layers of litter and shallow soil; and (2) base
runoff (or base flow), which reaches stream channels
after considerable delay usually as ground-water
discharge or as release from natural surface storage (in
swamps, lakes, and stream channels). The direct
runoff is the principal contributor to storm and flood
flows, and the base runoff maintains the fair-weather
flow of streams.
PACTOBR AFFCTWNO T H QUANTITY AND DITlRIBmTION
or TBR WAT=B CnOP
The three principal groups of factors that influence
the water crop were mentioned on pages 14 and 21 and are
used. as the basis of the following discussion:
1. Weather and climate: Climate is one of the most
important factors influencing the magnitude of
the water crop and its variability in place; weather
is the principal factor causing variability of the
water crop in time. The most important ele-
ments of weather, precipitation and temperature,
are discussed elsewhere in this report.
Snow, one of the forms of precipitation, deserves
some special comment. The principal hydrologic
effect of snow is temporary storage of water during
cold weather and the release of the stored water
with the advent of warm weather. Storage in
snow is of great importance in parts of the western
United States where the snow accumulation on
the high mountains provides delayed runoff
for use in the spring and summer. Snow is much
less important to the Delaware River region,
because the differences in elevation and climate
are less extreme and because snowmelt runoff
usually occurs in winter and early spring when
runoff from rainfall is sufficient to meet most de-
mands. The effect on the regimen of streams in
the northern part of the Delaware River basin is
significant, however. Snow may also have several
minor effects. For example, insulation of the
ground from sudden changes in air temperature
may prevent the ground from freezing and allow
infiltration to continue; or the cover of snow on
frozen ground may prevent the ground from thaw-


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WATER RESOURCES OF THE DELAWARE RIVER BASIN


ing and may increase direct runoff from snowmelt
or rain. The snow cover may absorb considerable
quantities of rain. If rain saturates the snow and
continues to fall, large quantities of snowmelt, in
addition to the rainfall, may be released in a flash
flood.
2. Physical characteristics of the drainage basin: The
storage capacity of a basin is determined by its
physical characteristics, including the works of
man. Temporary storage of water within a drain-
age basin generally has a stabilizing influence on
streamflow and thus on the water crop. Storage
is the most important of all the factors subject to
human control and development; it is discussed in
following sections on surface storage and ground-
Swater storage.
The ability of the soil to absorb precipitation
and transmit it to the aquifers is a closely related
factor of great importance, which is discussed in
the section on infiltration capacity. The prin-
cipal effects of land use or vegetational cover on
the water crop are reflected in the infiltration
capacity.
Topography also has important effects, some of
which are related to storage. Areas of consider-
able relief commonly contain suitable sites for
construction of artificial surface-storage facilities,
but practically none are suitable for providing
storage for all storm runoff from major floods.
These areas are also deficient in natural storage
capacity, both on the surface and underground.
Areas of low relief in the basin have few suitable
sites for any but very small surface reservoirs,
but these areas commonly have large ground-
water storage capacities. Steep land slopes favor
direct runoff, and flat slopes allow more time for
infiltration.
The topography has a controlling influence on
land use and thus affects the water crop indirectly.
For example, steep slopes may be suitable only for
forest, and level lands near a stream may be
suitable for agricultural, urban, or industrial
development.
3. Economic, legal, and political aspects of water de-
velopment: Detailed analysis of specific projects
is beyond the scope of this study, but the limita-
tions imposed by these projects are important in
any evaluation of the water crop. For example,
economic limitations probably would prevent the
storage of all the water that it is physically possible
to store. Legal and political considerations might
impose additional restrictions. All the human
factors are subject to change, and the overall
limitations imposed will probably decrease as the


need for water increases, but at any particular place
the limitations may increase appreciably. As
water becomes more difficult to obtain, users will
pay higher prices, and laws may be altered to meet
new conditions.
The requirements for nonwithdrawal use also
are dependent upon human factors, subject to
change both in time and place. In drylands
regions higher priority uses often take nearly all
the available supply. In the Delaware River
basin, however, an increase in nonwithdrawal
uses is more likely to occur than a decrease because
of the increasing needs for: (1) dilution of wastes;
(2) control of salt-water encroachment; and (3)
maintenance of navigation facilities.
srACX rTOSAs
The natural surface-storage capacity of a basin
includes the capacity of its lakes, ponds, swamps, and
stream channels. During periods of storm runoff the
inflow to these water bodies usually exceeds the outflow,
consequently the water levels rise. The outflow rate
is partly determined by the stage, or elevation of the
water surface. When the inflow rate drops below the
outflow rate, the stage begins to fall and the release of
stored water sustains flow at downstream points. Thus,
stirface-water storage and ground-water storage to-
gether provide the fair-weather flow of streams, and
increase the harvestable water crop by making more of
the streamflow available for withdrawal.
Natural storage may be supplemented by artificial
reservoirs with either controlled or uncontrolled outlets.
When outlets are uncontrolled, the effects of-the storage
are similar to those of natural storage except that
outflow rates are partly determined by design of the
outlet structure. Such storage reduces flood peaks,
unless the reservoir is full at the time of peak runoff,
but has no effect on low flows occurring long after storm
runoff has ceased.
Controlled storage may be classified as flood-control
storage or as conservation storage. Flood-control
storage is utilized to reduce flood peaks and thus to
diminish damage at downstream points; but, because
storage space must be emptied soon after each flood,
flood-control storage has no effect on most low flows.
Conservation storage is utilized to store excess runoff
for later use during periods of low runoff. Storage.
for hydroelectric power is intermediate between theme
two types. Its purpose is to supply power when
needed, regardless of streamflow conditions. In prac-
tice its effects are usually closer to those of conservation
storage than to those of flood-eontrol storage.
In the Delaware River basin the best storage sites are
upstream from the Fall Line. In the Coastal Plain,
surface-water storage sites are scarce, even for small


reservoirs. H
locally scanty
aquicludes, st
been construe
flowing tribul
Jersey. Somi
remain and a
,'feasible.
The useful
reservoirs is
data for the
Neither, for
expected life
the one propc
these large n
hundred years
probably less
Surface-wa
closely related
level in swam
water table;
become groum
reservoir in pI
water table f
storage of Mw
There is a
River basin 1
rugged parts 4
by storm runm
They are use
trials, and tl
and cominsl
havd little.
Evaporation 1
dry weather,
great, the tot
In the low
soils and sqi
the ponds a
and the effee
For example,
report:
In August 11
near Seed, NJ
feet ong, was
course of the B
feet from the p
is about 30 per
ground water
within a few uh
it can be appr
water body m
ground water.
considered adv
precipitation, I


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particular place
preciably. As
Ain, users will
ltered to meet

-wal use also
r, subject to
In drylands
ake nearly all
aware River
ionwithdrawal
rease because
ion of wastes;
nent; and (3)


y of a basin
, swamps, and
irm runoff the
da the outflow,
a outflow rate
ovation of the
rops below the
I the release of
points. Thus,
ar storage to-
i streams, and
making more of

id by artificial
trolled outlets.
i of the storage
re except that
design of the
a flood peaks,
Af peak runoff,
ng after storm

s flood-control
Flood-control
is and thus to
I; but, because
ter each flood,
most low flows.
a excess runoff
inoff. Storage
between these
power when
ons. In prac-
>f conservation
ragse.
storage sites are
Coastal Plain,
ven for small


reservoirs. However, in places where ground water is
locally scanty and where the area is underlain by thick
Saquicludes, small serviceable surface reservoirs have
been constructed, especially in some of the westward-
flowing tributaries of the Delaware River in New
Jersey. Some sites for such small reservoirs still
remain and may eventually be utilized if economically
feasible.
The useful life that may be expected of these small
reservoirs is unknown because the sediment-transport
data for the small streams involved does not exist.
Neither, for that matter, can we be certain of the
expected life of large reservoirs, such as Pepacton or
the one proposed at Tocks Island. The useful life of
these large reservoirs probably will be about several
hundred years; that of small reservoirs will be much less,
probably less than a hundred years.
Surface-water storage and ground-water storage are
closely related in some places. For example, the water
level in swamps rises and falls with the connecting
water table; leakage from reservoirs and ponds may
become ground water; raising the level of water in a
reservoir in permeable materials may cause a rise of the
water table for considerable distances and increase the
storage of water in the aquifers.
There is a widespread movement in the Delaware
River basin to construct farm ponds. In the more
rugged parts of the region these ponds are filled mostly
by storm runoff in small wet-weather drainage courses.
They are usually built on relatively impermeable ma-
terials, and the pond water is therefore insulated from,
and commonly above, the water table. Such ponds
have little or no effect on ground-water storage.
Evaporation takes a heavy toll from such ponds during
dry weather, but because the area of these ponds is not
great, the total effect on the basin's water crop is small.
In the lower lands of the basin, especially where the
soils and aquifers are thicker and more permeable,
the ponds commonly connect with the water table,
and the effects of ponds on ground water are greater.
For example, Barksdale and Remson (1956, p. 524)
report:
In August 1953 the floodgates were opened in a small dam
near Seely, NJ. The level of the pond, which is about 2,000
feet long, was lowered more than 4 feet. As a result, in the
course of the next several weeks the water level in a well 500
feet from the pond fell 1.5 feet. The specific yield of the aquifer
is about 30 percent, so that obviously several million gallons of
ground water was being drained from the aquifer in the area
within a few hundred yards on either side of the pond. Thus,
it can be appreciated that the impounding of this small surface-
water body resulted in the storage of a substantial amount of
ground water. In many and perhaps most areas this would be
considered advantageous; in others, particularly areas of heavy
precipitation, it might be better to allow the drainage of this soil


so that the storage space would be available to reduce overland
flow and erosion. Whee the aquifer material have large specify
yields, the judicious placement of small dams can result in sub-
stantial increases in local ground-water storage. On the other
hand, in areas where the speeifie yield is low, relatively little
water could be stored in the ground around such a pond.
ols-.WAIrs aoaresa
Aquifers serve dually as natural reservoirs and
conduits, and they have a pronounced effect on the
time distribution and magnitude of the water crop.
As in a surface reservoir, the quantity of water stored
underground fluctuates in response to changing rates of
inflow and outflow, although with considerable lag.
The amount in storage increases during and after
periods of precipitation, or water added to the soil in
excess of field capacity percolates downward to the
zone of saturation; in contrast, storage decreases
during and after periods of drought. Recharge from
equivalent amounts of precipitation is much less during
the growing season than during the winter, because
during the growing season more of the water is lost by
evapotranspiration from the soil and vegetation and
less water infiltra*e4 to the water table. At the same
time the discharge from the ground-water reservoir
continues; hence, the amount of water in storage
decreases. Limits within which the quantity of water
stored underground fluctuates naturally are determined
chiefly by the volume of pore space in the reservoir
that can accept and transmit water and by the eleva-
tions of the discharge outlets.
The chief effect of ground-water storage on the water
crop is to maintain streamflow during dry periods and
to distribute the flow more evenly in time. In the
Delaware River basin this regulatory effect is of great
importance; it is estimated that about half the average
annual runoff is derived from ground-water discharge,
but marked variations in this proportion occur within
the basin.
When a ground-water supply is developed, the
ground-water storage has even more effect on the water
crop than it has under natural conditions. When
water is pumped from aquifers, more storage space is
provided to accept recharge from precipitation, which
otherwise might have run off directly. Pumping lowers
the water table and reduces: (1) natural evapotrans-
piration; (2) underground outflow; and (3) ground-
water discharge to streams or other surface-water
bodies. The draft on storage is offset by additional
recharge that is induced where the normal water-table
slope toward a surface-water body is reversed.
Ground water can be withdrawn from storage at
rates temporarily exceeding the rate of natural recharge
(temporary overdraft), and the aquifers can be replen-
ished either naturally or artificially. When with-


1 __







_ ?-- ;:- ------cl~--


WATEM RMEOURCZS OF THE DELAWARX RXIEN DA5w


drawals exceed recharge mining of ground water occurs.
In such instances mining the aquifer depletes the supply.
In several parts of the United States, including parts
of New Jersey, aquifers have been recharged artificially
with excess local streamflow or with imported supplies
(Barksdale and DeBuchananne, 1946, p. 726-737).
By use of these processes during the development of
ground-water supplies, recharge and discharge of the
aquifers are increased, and the fluctuations in ground-
water storage may be greater than those under natural
conditions. Except for the decrease in natural loss by
evapotranspiration and ground-water outflow, the
potential water crop in the basin is not thereby in-
creased; however, more of it is made available for use
locally.
The part of the annual water crop that is available
locally from ground water varies greatly, depending
chiefly on the storage and transmissibility characterie-
tics of the aquifers. Thus, Jle ground water is availa-
ble in an area underlain by impermeable rocks or clay
than in an area underlain by thick permeable sand.
In the Delaware River basin ground water is most
abundant in the Coastal Plain; in the Appalachian
Highlands, where ground water is not so abundant, it
occurs in greatest quantities in the deeper valleys- that
are underlain by coarse glacial deposits or limestone.
- Ground-water supplies tend to differ from surface-
water supplies in physical, chemical, and biological
character, and ground-water supplies therefore may be
more desirable than surface supplies for some purposes,
For example, at Louisville, Ky., a plentiful supply of
water is available from the Ohio River, but many
industries prefer ground water for cooling in summer
because of its lower temperature, greater clarity, and
more uniform chemical characteristics. Accordingly,
withdrawals from the aquifer in summer greatly exceed
the natural recharge, and in winter cold river water
is used to recharge the aquifer. Thus, aquifer storage
is utilized to provide cold water when surface supplies
are too warm.

The characteristics of the rocks and soils above the
zone of saturation determine the rate at which water
can be absorbed and transmitted to the underlying
aquifers. Consequently, the rocks and soil largely
determine the proportions of direct runoff and ground-
water recharge. Permeable well-drained soils absorb
water readily and continue to do so as long as storage
space is available in the aquifer. Most soils absorb
water more readily when nearly dry than when wet.
A permeable soil over an impermeable subsoil quickly
becomes saturated and infiltration decreases to the
rate at which the subsoil transmits water downward.
The infiltration capacity of a soil may be changed by:


(1) freezing, which makes the surface less permeable;
(2) alternate freezing and thawing, which loosens the soil;
and (3) changes in vegetational cover and methods of
cultivation, which affect soil structure, organic matter,
and plant and animal life in the soil. Furthermore,
urbanization results in elimination of infiltration from
large areas
A virgin soil tends to be much more permeable than
the same soil under cultivation or grazing. 'The effects
of cultivation on infiltration capacity are illustrated by
experience at Seabrook, NJ., where almost one billion
gallons of cannery waste is disposed of annually by
irrigation from large sprinkler nozzles in a wooded area
of approximately 260 acres. I1 describing the experi-
ence at Seabrook, Thornthwaite (1951) states:
Any land that had been tilled would become saturated and
soupy to plow depth after 2 inches of water had been applied.
At the same time, adjacent pine-oak woodland which had not
been plowed took 50 inches at th e e .3 inches per hour
without becoming saturated. This area received more than 150
inches in 10 days with still no sign of being satsied.
The infiltration rates observed at Seabrook could be
maintained only where soils and subsoils are deep,
permeable, and well drained.
Land use and management may affect the infiltration
capacity to extents that vary in time and in place,
depending upon local conditions. The effects of various
types of land use and various methods of cultivation
have been studied extensively by small-plot experiments,
but evaluation of the effects in large complex area, such
as the Delaware River basin, is difficult.
FAMCTORU AWrrnC o TM QUA14eY Or THm WATM COsto
A satisfactory water supply must be adequate in
quality and quantity. Water passing through the
atmosphere and over or through the soil and rocks
acquires suspended and dissolved impurities. Some of
these impurities may be of no consequence for a
particular use, but may seriously impair the water for
other uses. For example, water containing a small
concentration of dissolved iron may be suitable for
drinking but not satisfactory for the manufacture of
plastics or rayon. Dissolved oxygen enhances the
palatability of drinking water, is essential to the exist-
ence of some forms of aquatic life, and plays a part in the
self-purification of natural waters. Dissolved oxygen
also makes water corrosive to metal pipes, and for such
uses as boiler-feed water its concentration should be
below a certain level Natural water is never chemically
pure although much is biologically pure. We shall,
therefore, consider the sources of the impuritie and their
effect on the uses of the water.
zurnea n saseo now T= &=00003
Rainwater and snowmelt are the purest of natural
waters. In some areas, rain falling on the rooftops is


collected in cistem
further treatmeat.
contains oxygen, i
from the atmoseph
are found in great
than in the air. I
other gases an&
acid, and sulfuric
and soot. Theas
in the rainwater
are common ner
nary salt is com
purities, howev,
small quantities

Rain that falL4
to dissolve ree
mated that, in te
130 tons of miner
annually and can
concentration O
depend upon ma
water and rook i
ground water i
which runs quk
When the grout
rainfall, little n
S to the stream i
accompanied by
to streams. Il
less mineraliud
flow is largely d
Water mayc
erals, as it dor
oxygen or earb
materials. Thi
hydrolysiss," tl
the action e
Whether the a
donation, thes
solution ions of
iron, manganm
and colloidal
Through hydh
sium, sodium,
are then epl*
By this prom
soluble day m
becomes mea
minerals, wl
River bain,.
than by neut
Dry air em
by volume, i


_I-------- -- -^*"'-


ll- t h k, t u 1L1 Ai[ i lll AI 1.11I


`t




-u,; k L(lI


. les permeable;
ch loosens the soil;
i and methods of
s, organic matter,
i. Furthermore,
r infiltration from

w permeable than
sing. The effects
are illustrated by
almost one billion
I of annually bJ
in a wooded area
ibing the experi-
) states:
ime saturated and
r had been applied.
and which had not
83 Inceha per hour
lived more than 150
attaed.
abrook could be
bsoils are deep,

t the infiltration
e and in place,
ffeets of various
a of cultivation
lot experiments,
nplex area, such

Om wATra CROP
)e adequate in
g through the
soil and rocks
cities. Some of
squence for a
r the water for
mining a small
M suitable for
manufacture of
enhances the
dl to the exist-
Ps a part in the
solved oxygen
r, and for such
ion should be
er chemically
e. We shall,
ities and their


st of natural
>e rooftops is


TB WATr


collected in cisterns and serves for domestic use without
further treatment. Even this relatively pure water
contains oxygen, nitrogen, and carbon dioxide dissolved
from the atmosphere, but oxygen and carbon dioxide
are found in greater proportions in the dissolved gases
than in the air. The rain washes from the atmosphere
other gases and such substances as ammonia, nitric
acid, and sulfuric acid, as well as fine particles of dust
and soot. The nature and proportion of the impurities
in the rainwater are variable: mineral acids, for example,
are common near cities or industrial centers, and ordi-
nary salt is common near the seacoast. Mineral im-
purities, however, are present in rainwater in extremely
small quantities.
rPUUr DrIren nr o 00aomM s aD sosU
Rain that falls on the earth's crust begins immediately
to dissolve rock and soil. Clarke (1924, p. 116) esti-
mated that, in the region draining to the North Atlantic,
130 tons of minerals per square mile of land is dissolved
annually and carried off to the ocean. The nature and
concentration of the dissolved matter in the water
depend upon many conditions. Long contact between
water and rock material favors solution, consequently,
ground water is usually more mineralized than water
which runs quickly over the surface to the streams.
When the ground is frozen, or saturated by previous
rainfall, little rain penetrates the ground and runoff
to the streams is increased. In the early spring, rain
accompanied by snowmelt results in heavy discharge
to streams. In either situation, the stream waters are
less mineralized than in periods of low flow when stream-
flow is largely derived from ground water.
Water may react chemically directly. with rock min-
erals, as it does with feldspars, or serve- as a solvent of
oxygen or carbon dioxide, which also react with earth
materials. The direct action of water is referred to as
hydrolysiss," the action of oxygen as "oxidation," and
the action of carbon dioxide as "carbonation."
Whether the action be hydrolysis, oxidation, or car-
bonation, the water leaches out and carries away in
solution ions of sodium, potassium, calcium, magnesium,
iron, manganese, chloride, sulfate, nitrate, bicarbonate,
and colloidal or soluble silica, iron, and aluminum.
Through hydrolysis the feldspars give up their potas-
sium, sodium, and calcium to the water. These ions
are then replaced by hydrogen ions from the water.
By this process the feldspars are converted to less
soluble clay minerals, and as a result the solvent water
becomes more alkaline and more mineralized. Silica
minerals, which are very abundant in the Delaware
River basin, are attacked more by acid ground water
than by neutral or alkaline water.
Dry air contains about 0.03 percent carbon dioxide
by volume, but rainwater may contain as much as


ia SUML 85

3 percent dissolved carbon dioxide (Rankama and
Sahama, 1950, p. 312). Aerobic bacteria in the soil
oxidize organic material to carbon dioxide which further
enriches the soil water in carbon dioxide. Dissolved
carbon dioxide forms carbonic acid which is very
effective in dissolving such carbonate rocks as limestone
or dolomite.
The concentration and proportions of dissolved mate-
rials depend chiefly upon the mineral constituents of
the aquifer from which the water came. Compared to
water from other sedimentary rocks, water flowing over
or through limestone or dolomite will be rich in calcium
and magnesium. On the other hand, water flowing
from an acidic, igneous, rock terrane, such as an area
underlain by granite, gneiss, or schist is low in dissolved
solids but relatively high in silica, sodium, and
potassium.
KVmRa nPAUZ. D An A 0eaTvoWU WAsI
Natural water contains some impurities, and use of
the water for domestic, industrial, or agricultural pur-
poses usually adds more. Whether these additional
impurities impair the usefulness of the water depends
upon their nature, their concentration in the water, and
what use is to be made of the water.
The quality of water may be impaired by some uses
even when no impurities are added. For example, far
more water is used for cooling than for all other indus-
trial purposes. The discharge of waste cooling water
to a stream raises the stream temperature, especially
where the stream water is reused several times, and it
may become too-warm for further use as a coolant.
Fish and other aquatic life are affected by a rise in
temperature because (1) warm water contains less
dissolved oxygen than cooler water, and (2) fish are
more active at the higher temperature and therefore
consume more oxygen. Thus, an increase in water
temperature may asphyxiate the fish by depleting the
oxygen.
Some organic wastes, such as those in sewage, are
oxidized by the dissolved oxygen in stream waters with
the aid of certain kinds of bacteria. This natural
purification process, too, proceeds faster at higher
temperatures. Faster reaction may be an advantage
if there is sufficient dissolved oxygen to consume all the
organic waste material. However, the waste putrefies
if the dissolved oxygen is not sufficient to oxidize it,
for in the absence of oxygen the waste is destroyed by
reactions producing gases of objectionable odor, such
as hydrogen sulfide. Thus, information on the con-
centration of dissolved oxygen is useful in evaluating
water quality; so also is the biochemical oxygen de-
mand, which is a measure of the oxygen required for
the destruction of organic matter by aerobic biochemi-


j





IiI


WATER RESOURCES OF THE DELAWARE RIVER BASIN


cal action. If the dissolved oxygen is sufficient to
satisfy the biochemical oxygen demand, the oxidizable
wastes probably will be removed by natural purification
in the stream.
Dissolved minerals, such as common salt (sodium
chloride), do not disappear in this fashion. They may,
however, be flushed away or be sufficiently diluted that
they are not deleterious. The sewage of the city of
Philadelphia adds about 100 tons of sodium chloride
daily to that already in the Delaware River. With a
fresh water flow of 12,000 cfs (cubic feet per second),
for example, the 100 tons per day of sodium chloride
constitutes only 3 to 4 ppm in the river water. This
concentration is not objectionable and is insignificant
compared to the amount of salt introduced from the
ocean.
Industrial wastes are of many kinds. Wastes from
breweries, dairies, and slaughter houses, for example,
contain organic material which, like sewage waste, is
subject to oxidation. Some contain toxic substances,
such as the phenols from coke plants, the arsenic from
weed-killers or insecticides, and the cyanides from elec-
troplating processes. Others include mineral acids
from chemical manufacturing or salt brines from petro-
leum wells. Some wastes do not dissolve in the water.
Oils and greases float or become emulsified; solid parti-
cles, such as paper fibers, sewage solids, or sediment
may make the water turbid by remaining suspended;
or may foul stream beds or reservoir bottoms by settling
out there.
Radioactive substances from nuclear reactors and
radioisotopes used in medical therapy or in industrial
processes are potential contaminants of aquifers and
streams. Although their disposal is restricted by
various regulations, it is always possible that-through
accident, ignorance, carelessness, or sabotage-radio-
active materials may reach ground- and surface-water
bodies. The rate at which these materials give off
radioactive radiation can neither be retarded "nor
accelerated. If ingested, some may become concen-
trated in lethal quantities in particular tissues of the
body. Radioactive materials are also harmful to some
industrial processes, such as the manufacture or
processing of photographic film.
Drainage from farmlands is sometimes rich in am-
monia, nitrates, and phosphates, which stimulate the
growth of algae. Algae are beneficial in that they
produce oxygen and consume carbon dioxide and some
are a food supply for fish and other aquatic life; but
where algal growth is excessive the algae or their prod-
ucts can poison farm animals and impart undesirable
taste and odor to domestic water. Algae are undesira-
ble in cooling water and in water used for laundry,
photography, and the manufacture of paper and rayon.


When the streamflow is large compared to the volume
of waste discharge, dilution may be sufficient to reduce
the concentration of impurities to an unobjectionable
level. The disposal of wastes by dilution, however,
is not as simple as it may seem. Suppose an industry
wishes to discard 500 gpd of a waste containing 20 ppm
of cyanide by dumping it into a small stream having
an average flow of 1 mgd (millions gallons per day),
or 1.55 cfs. If the waste is uniformly mixed with the
total daily flow of the stream, the resulting cyanide
concentration in the stream will be only 0.01 ppm.
But in dry seasons the stream discharge will be less
than 1 mgd, and the resulting concentration of cyanide
will be greater. If the batch of waste is all dumped
within a half-hour period, the concentration of cyanide
in the stream may be 0.5 ppm, which would be fatal to
most fish. Again, the waste may not mix thoroughly
with the stream water, and some of the water may con-
tain more than 0.5 ppm of the waste. The waste may
concentrate on one side of the stream or, if denser than
the stream water, on the bottom. Mixing is also
affected by wind, river alinement, roughness of the
channel, and tidal action.
Most polluted water can be made suitable for use by
treAtment, but the process may be too costly. For ex-
ample, several treatment methods are known for the
conversion of sea water to fresh water, but as yet none
of these methods produce fresh water at a cost low
enough to compete in the Delaware River basin with
naturally fresh water for irrigation, domestic, or
industrial use.
Most wastes are introduced into the streams in areas
of heavy population and industrial concentration, as
the Allentown-Bethlehem area on the Lehigh River,
the Easton, Trenton, and the Philadelphia metropolitan
areas on the Delaware River, and on the Schuylkill
River at and below Reading. Other important sources
of pollution are in the headwaters areas of the Schuylki
and Lehigh Rivers.

The anthracite coal mines of the Schuylklld and
Lehigh River basins have a pronounced effect on the
quality of the water in these streams and on some of
their tributaries. Associated with the coal are sales
containing pyrite, a sulfide of iron. When the coal is
mined, the shales are exposed to attack by air and
running water. As water saturated with air flows
across these shales or through the pyrite-bearing refuse
in or near.the mines, iron and sulfur are dissolved in
the water. The ferrous iron oxidizes to ferric iron and
the sulfur to sulfate ion and free sulfuric acid.
The resulting dilute sulfuric acid readily dissolves
additional rock materials so that in addition to the
hydrogen, ferrous, and sulfate ions, these mine waters


often contain
sium, alumi
hydrolysis e
the pH of i
or 4. The
mine is rated
,- from differ
length of ac
minerals as
position of
mine drain
there is litt
composition
water gene
wastes from
tion in Sept
streamnlow
former perk
The Scht
cuts throng
and finally
month uplaM
from Berne
year period,
(1) the we
area, 3.5 til
gion as in t
nearly as n
percent of 1
the Schuyll








For man
River m~W
purities ris
ganese cai
paint, na
problems i
rayon, pla
magnesium
their effi
Mineral s
injurious U
Acid ma
natural pu
shown by I
River. 1
promote i


x~--~-----~nr.rr.*^-r~-pc---~-rrr~i-~













GROUND WA'ZR-ITS AVAULBJoTT AND A" CRARAMR


red to the volume
dicient to reduce
Sunobjectionable
iution, however,
pose an industry
staining 20 ppm
11 stream having
llons per day),
r mird with the
multing cyanide
only 0.01 ppm.
rge will be less
tion of cyanide
is all dumped
tion of cyanide
ud be fatal to
mix thoroughly
water may con-
The waste may
if denser than
is also
sea of the

for use by
tly. For ex-
wn for the
as yet none
t a cost low
basin with
domestic, or


sams in areas
entration, as
high River,
metropolitan
is Schuylkill
rtant sources
he Schuylkill


huylkill and
effect on the
on some of
I are shales
the coal is
by air and
Sair flows
ring refuse
solved in
e iron and
id.
Dissolves
ion to the
ine waters


often contain high concentrations of calcium, magne-
sium, aluminum, and manganese as well. Owing to
hydrolysis of salts of iron, manganese, and aluminum,
the pH of acid mine drainage usually is low, about 3
or 4. The composition of water from any particular
mine is rather uniform, but the composition of water
from different mines varies because of differences in
length of contact of water with air and acid-forming
minerals and because of the different mineral com-
position of the rock. In the streams, however, the
mine drainage is diluted by overland runoff. Although
there is little seasonal change in the concentration or
composition of drainage from a given mine, the stream
water generally has lowest concentrations of acid
wastes from December to June and greatest concentra-'
tion in September and October, because the volume of
streamfow available for dilution is greatest in the
former period and least in the latter.
The Schuylkill River rises in the coal regions, then
cuts through shale and sandstone, limestone, diabase,
and finally through the crystalline rocks of the Pied-
mont upland. The coal-mining region is upstream
from Berne, Pa. The following data, based on the 4-
year period October 1947 to September 1951, show that:
(1) the. water dissolves, per square mile of drainage
area, 3.5 times as much material in the coal-mining re-
gion as in the rest of the drainage basin; and (2) that
nearly as much material is dissolved above Berne (19
percent of total drainage area) as in the remainder of
the Schuylkill River basin.

DnmbM Dw Di


LI It) Z in
I**% t aw P--.-- --..- --- m a-I. ____.
T-----------------------.. -.... im ,m, a

For many industrial uses, water of the Schvylkill
River must be treated because of the dissolved im-
purities resulting from mine drainage. Iron and man-
ganese cause stains or discoloration on white porcelain,
paint, enamel, and laundry; they create additional
problems in the manufacture or processing of paper,
rayon, plastics, textiles, and leather. Calcium and
magnesium form scale in steam boilers which reduces
their efficiency and increases maintenance costs.
Mineral acids corrode metal and concrete and are
injurious to fish.and other forms of aquatic life.
Acid mine drainage may have a pronounced effect on
natural purification processes in a stream, as has been
shown by Chubb and Merkel (1946) for the Schuylkill
River. Domestic sewage contains the organisms that
promote its decay. When the sewage is diluted with


stream water containing dissolved oxygen, these orgs-
nisms aid the oxidation of organic matter. If, however,.
the stream water is acid (as it is in the upper Schuylkill
River), the sewage remains practically unchanged in
the stream. The dissolved-oxygen concentration in-
ereases in this reach of the stream, for little is consumed
by the sewage. At or near Reading, tributaries
draining a limestone region add their waters to the
stream; these waters are alkaline enough to neutralize
the water of the main stream. The inactive organisms
then function again, the sewage is oxidized; and the
dissolved-oxygen concentration decreases. If the dis-
solved oxygen is insufficient to oxidize the sewage when
the acid stream is neutralized, nuisance conditions can
be created, for in the absence of oxygen the sewage
.which accumulated in the acid reach of the stream is
putresed.

Sediment in streams is due to erosion and to municipal
and industrial wastes. If a drainage basin is covered
with protective vegetation, comparatively little erosion
occurs; but if the ground is bare and exposed to rain-
drop impact and rapid runoff, soil erosion and stream
loads are greater. Although industrial or municipal
wastes may contribute sediment to the streams, most
of these are treated before discharge; simple treatments
are used to remove the settleable solids. Sediment may
be sand, clay, silt, vegetation, or material of mining or
other industrial origin. Perhaps the greatest sediment
problems in the basin have been those associated with
coal mining. At one time coal-cleaning operations and
the erosion of cuim piles were the source of sediment
discharged principally into the Schuylkill River. Now
coal washeries have settling ponds to remove the culm
before the wash water is discharged to the streams, old
deposits have bean dredged from the Schuylkill River,
and desilting basins have been provided to remove
sediment that reaches the river.
Sediment interferes with natural purification in
streams by reducing the penetration of sunlight and by
its adverse effect on aquatic growth. Sediment in
suspension clogs the gills of many fish and mollusks.
Worms, protozoa, algae, insects, and crustacea may be
injured or destroyed. During settling, inorganic sed-
iment carries organic matter with it. The decay of the
organic matter requires oxygen, and the sediment
hinders access of oxygen to the organic matter.
The load that a stream can carry in suspension or
move along its bed as bedload is largely a function of
stream velocity. The. faster a stream flows, other
factors being equal, the more sediment the stream can
transport. Stream velocity is not constant, either in
place or time, and sediment load constantly changes.
When velocity drops below the point at which a stream


i1 ; i Ii


37


rWI


(4\


t




,A ta, I A 1lll L i 4 111 I i


(r


WATER RESOURCES OF THE DELAWARE RIVER BABIN


can carry fine gravel insuspension, itstill maycarrysand.
silt, and clay particles. Given a lesser velocity, the
sand may be dropped and only silt and clay still remain
in suspension. Where streams enter reservoirs and
velocity becomes negligible, only the very finest
sediment remains in suspension, and even this, given
enough time in quiet water, settles out.
Organic sediments may be deposited in a streambed
or carried downstream in suspension, deppdiUng largely
upon the stream velocity. In either situation, such
sediments are slowly decomposed by bacterial action
with the aid of dissolved oxygen. In a turbulent
stream the oxygen consumed is replaced through aera-
tion, unless the organic matter is oxidized too rapidly.
Where an organic pollutant is released to a stream
upgradient from a reservoir, two possibilities must be
considered: (1) All the organic pollutant will be de-
posited in the streambed -or be oxidized before it
reaches the reservoir; or (2) some or all of the oxidizable
matter will reach the reservoir.
In the first possibility, all the oxidation occurs in the
turbulent stream above the reservoir, and the oxygen
in the reservoir water is not depleted. In the second
possibility, all or some of the organic material is trapped
in the reservoir and undergoes decomposition there,
resulting in depletion of the oxygen in the reservoir
water. In the reservoir, as well as in the stream, the
oxygen consumed is replaced to some extent through
aeration. However, owing to depth and lack of
turbulence, aeration occurs at a slower rate in the
reservoir than in the stream. When no more dissolved
oxygen is left, anaerobic decomposition may begin
and produce odors. In a situation of this kind, a
regulated release of water to the reservoir for the
purpose of maintaining a specified minimum flow
through it could be highly undesirable. At sufficiently
low discharge rates, the organic solds would be oxidized
before they reach the reservoir, but at the higher
discharge rates provided by the regulated releases,
they might be carried into the reservoir, there to
undergo either oxidation or anaerobic decomposition.
Sediment is deposited in navigation channels in
many places, and dredging becomes necessary. Sedi-
ment must be removed from water to be used in the
manufacture of such products as ice, bottled beverages,
food, paper, and rayon. Some suspended solids are
abrasive and erode turbine blades in hydroelectric
plants. Often the most expensive part of the purifica-
tion of domestic water is the removal of sediment.
se wam nm asanswI sarway
Below Trenton the Delaware River is tidal. Salt
water from the ocean mixes with the fresh water of the
river as far upstream as Philadelphia. In addition,
large quantities of sanitary and industrial wastes are


discharged into this reach of the river. The salinity
ranges from that of the river water-at Trenton (40-
120 ppm of dissolved solids) to that of ocean water
(35,000 ppm). The salinity at intermediate points
varies under the effects of changes in sea level, in fresh-
water discharge, wind, and other factors, that is, the
usable supply of water at some places in this.urban and
industrial area varies greatly because of variations in
water quality. The varying chemical quality of water
in the tidal reach of the Delaware River is discussed
on pages 149-166.
GROUND WATE--ITS AVABIABLITY AND CHARACTER
GENERAL GROUOD-WATBR HTDROLOGY OF TI
BABUs
SUo80U OF GROUND WAT r
All ground water in the Delaware River basin is
derived from precipitation. When the capacity of
the soil to retain water against gravity (the field
capacity of the soil) is exceeded, the excess water
percolates to the zone of saturation to become ground
water. Throughout most of their courses the streams
of the Delaware River basin act as drains rather than
as sources of ground water. Seepage from streams
contributes a significant amount of recharge to ground
water only where pumping of wells reverses the natural
direction of ground-water movement toward the
streams. Under these circumstances, substantial
quantities of recharge may be induced from the streams.
OOCCURRRWC AMD MOVKMJT
Ground water is water occurring in saturated open-
ings in earth materials; it provides water to wells,
springs, and the fair-weather flow of streams. A bed
or zone of such materials capable of yielding collectible
quantities of water to wells or springs is called an aqui-
fer. Aquifers have two principal functions: (1) storage
of water; and (2) transmittal of water.
Storage is perhaps the primary function of aquifers
in which the water exists under unconfined, or water-
table, conditions. The water table is the top of the
zone of saturation, below the capillary fringe, where
pressures are atmospheric. Water-table conditions are
most common in shallow permeable materials such as
the coarse-grained deposits in large areas in the Coastal
Plain and the thick mantle of weathered rock in many
parts of the Piedmont physiographic province. Such
aquifers are naturally recharged directly from precipita-
tion on their intake areas.
On the other hand, aquifers that contain water under
confined, or artesian, conditions serve principally as
conduits to transmit water from intake (recharge) areas
to discharge areas, although they may store immense
quantities of water. Artesian aquifer ae enclosed by


P*
I


beds or zoa
(aquicludes)
little water
The heights i
treating an art
The best ex
in the basin
layers of da;
Aquifers is
to store, tra
nificant hydi
storage, pen
which is the
so important
such as clay,
of a material
storage cap.
Cofwfcie i
volume of wi
an aquifer pI
component c
that surface.
is due to eld
than to drai
very small, a
table quite
the coeffile
to 0.30.
Storagesi
aquifer are
and dischba
storage are r
or piezometr
released fro
represented
table, or pie
of the aquif
having an as
decline in v
a decline in
over the am
In an art
of 0.0001, a
represents s
water. In a
trial actual
the coeffcid
specific yiew
material isd
is derived p
water itself
aquifer and I
aquifer, how
the water l


U-.
I





$- ---mq.W


i .II ________


Highlights of Water Management in the

Southwest Florida Water Management District


by Garald G. Parker, C.P.G.


Reprinted from the May-June 1973, Volume 11, Number 3 issue of Ground Water


b.


L i *


i-






0


0


Highlights of Water Management in the

Southwest Florida Water Management District


by Garald U. Parker, C.P.G.a



ABSTRACT
The District, comprising 15 counties and nearly
10,000 square miles in central western Florida centering on
the Tampa-St. Petersburg metropolitan area, is one of the
nation's most rapidly growing areas. Water-budget analyses-
compared with expected water demands for water by the
burgeoning population indicate thatby about 1985, if the
present population growth rates and water-use demands
persist, we will be using as much water as nature supplies us
with on the long-term average annual basis, for once-only
uses. After that, to supply the water needed, we will either
"mine" water on a District-wide scale or bring about other
remedies. Among these are, without attempting to list
them in order of priorities:
1. Reuse water again and again.by cleaning it up and
recharging the aquifers with both high-grade sewage effluent
either by land-spreading or by injection through recharge
wells into the aquifers.
2. Engage in desalination of the almost limitless
quantities of brackish ground water, especially in the coastal
areas where salt-water encroachment is occurring on a large
scale.
3. Induce aquifer recharge by creating storage space
in the aquifers in areas that are currently full to overflowing.
In such areas precipitation is now largely rejected as re-
charge and ground-water seepage is lost to evapotrans-
piration.
4. Effect economies of water use by both industry
and agriculture-by far the largest users of water in our
District-by regulation of amounts that may be used for
irrigation and for various other industrial and agricultural
processes.
5. Divert flood waters from direct runoff to the
oceans to temporary flood detention areas from which
water can be drawn off to aquifer recharge facilities.
6. By permit processes regulate the amounts of water
that can be withdrawn for any purpose from either ground-
or surface-water sources in the District thus preventing
overdraft and resultant lowered water levels and, in some
areas additional salt-water encroachment.
7. Eliminate waste of water, particularly the existing
large losses from thousands of existing wild-flowing artesian
wells.


aChief Ilydrologist and Senior Scientist, Southwest
Florida Water Management District, Brooksville, Florida
33512.
Discussion open until October 1, 1973.


8. Develop new, large well fields upgradient from the
large coastal springs that now are discharging along our
Gulf Coast, a total of about 900 mgd, none of which is now
used for water supply.
9. Space new well fields for regional water-supply
purposes widely over the District and arrange for organiza-
tion of regional water-distribution and use systems.
10. As soon as feasible engage in rainmaking to
augment nature's normal precipitation.
Under nature's irrigation supply-demand pattern and
man's previously unmanaged and all-too-often wasteful
usage growing beyond all previous expectations, the water
supply and the flood-and-drought situation have become
impossible to live with. But with proper management of our
water and land resources the tide can be changed, and it
will be possible to live comfortably within our available
resources. It will cost us more but the increased cost is the
price we must pay to live in an area where demands on the
water resources are rapidly outgrowing nature's provisions.

The Southwest Florida Water Management
District comprises an area of nearly 10,000 square
miles and 15 counties situated in central-western
Florida (Figure 1). In fact, the District is almost as
large as the State of Maryland and is larger than any
of the following States: Connecticut, Delaware,
New Hampshire, New Jersey, Massachusetts, Rhode
Island or Vermont.
"Big" government is loathed in Florida just as
it is generally elsewhere in the United States, and it
took a nearly catastrophic set of weather circum-
stances in 1959 and 1960 to convince citizens of
this region that local government is too small, too
weak and generally too provincial in outlook to
prevent or alleviate such destructive floods as those
that plagued this region in March 1959, and again in
March and September 1960.
As a matter of fact, this region has experienced
alternating flood and drought throughout both
geologic and recorded history. But as long as the
population was sparse and the demands for water
supply were inconsequential, the people could
tolerate the vagaries of nature. For example, the
great flood of September 1933 might have been
even more disastrous than those of 1959 and 1960,


_


,4^. _.4-- --4w- iti--.- .--. L -


.--l--~iPI- i-r^)--l^.i--~ --~----i-s
in-




Il ii Jl JIU1P~,ik


Fig. 1. Index map showing the location of the Southwest
Florida Water Management District.


but in 1933 the population was small and homes
( and business establishments generally were not
built in flood prone areas. Today the population is
large, expanding rapidly, and much of it is develop-
ing in hazardous, flood prone areas. The counties of
Florida have the authority to enact flood plain
zoning regulations but, with rare exceptions, have
failed to do so.
Historically, this area has experienced numer-
ous droughts of 1 or 1- to 2-years' duration but
people had always been able "to make out" because
their small needs for water could be met by nearby
sources. Now we are experiencing, generally over
the entire District, a drought of unprecedented
proportions with 10 years of subnormal precipita-
Stion out of the last 12, and with an accumulated
rainfall deficiency of about 100 inches or more
(Figure 2). With a long-term average annual pre-
cipitation for the District of about 55 inches, the
deficiency is almost that of 2 years of expected
rainfall. Such conditions of extreme drought and
flood, complicated by an exploding population
with a vast thirst for water, have created water-
supply and flood protection problems of such large
magnitudes that local governments-village, city
( and county-cannot successfully combat them.
Accordingly "Big Government" in the form of
Sa regional flood control agency was demanded by
local citizens in 1960. The State Legislature re-


~6~[2.~,7c-15 ~ A'


Sa a a .a r a . .
VrAR
|an OC*,nmMlu,,a~Tft : T ft Oi- TW p tc UWiAITRf
,b 1 .%. .- ,I V'10 s t
V V i 16i- 4tr ,qq jii
i!";"' i' % '1 1 2
Fig. -2 G:fh f d4pat ur# of r*ainf for Tampa Florida.
Fig. 2. Graph Of departur* of rainfall for Tampa, Florida.


sponded by enacting Chapter 61-691, Florida
Statutes, which established the Southwest Florida
Water Management District. The Act became law
on July 1, 1961. Its Section 1 states:
"For the purpose defined in Chapter 378, Florida
Statutes, and to facilitate the creation and initial operation
of a district under said Chapter, Southwest Florida Water
Management District is hereby created a public corporation
for carrying out and effectuating the provisions of said
Chapter. Other than as herein provided, Southwest Florida
Water Management District shall operate under and be
governed by the provisions of Chapter 378, Florida Statutes,
as amended from time to time."
Chapter 378, Florida Statutes, is known as the
Flood Control Act. It prescribes rules and regula-
tions governing the establishment of flood control
and water management districts. Among other
things this Act provides for cooperation with
agencies of the federal government to effect flood
control management (378.01) and establishes a
water resources development account (378.03) in
the general revenue fund of the State which is to
provide financial assistance to districts established
under its authority, including the funds as grants-
in-aid to purchase lands required for such purposes
as water storage areas, canal or reservoir sites and
bridges.
The members of the Board of Governors, as


Departwu From Normal Roanfall For Tompa, Fla.
M4 On US WAIICR *VIuU MC9RO
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_1








provided in Chapter 61-691, were appointed by the
Governor and met for their organizational meeting
on August 28, 1961, at the Capitol in Tallahassee,
Florida. By March 6, 1962, the entire District was
organized into .11 River Basins (Figure 3), each C
with its own Basin Board operating at the grass- .
roots level to levy taxes, build and operate flood
control and other water management structures
within limits of their river basin boundaries, and to
be responsible for carrying out the provisions of ..
Chapter 61-691 within their respective boundaries. '
Each Basin Board, however, is responsible for its -.1
actions to the 9-member Board of Governors of the .w L
District.
In the meantime, members of the Florida
delegation to the U.S. Congress were busy arranging
through the Committees on Public Works in both
the House and the Senate for aid of the U.S.
government under the provisions of both the River ,
and Harbor and Flood Control Acts. This resulted
in the establishment of the Four River Basins,
Florida, Project as described in House Document
No. 585, 87th Congress, 2nd Session, 1962 (Figure
4).
Fig. 3. Map of Southwe
Under this authority and with funds provided rict showing the 11
by the U.S. Congress, the State of Florida's water District.
resources development account and local ad valo-
S rem taxes, the U.S. Army Corps of Engineers and
the Southwest Florida Water Management District '
began work on the Four River Basins' Project on "
October 23, 1962. S "
The District staff at that time consisted of .
only 3 persons, but additional personnel were added ,,* i
as work progressed on the flood control aspects of t., .*.
the Four River Basins' Project. Early in the Project -'-
emphasis was placed on starting construction of the L-
Tampa Bypass Canal with its system of channels '.
and water control structures designed to route
damaging floods around the periphery of Tampa 1 s
instead of through it; on developing the outdoor f
recreation plan to allow and provide for citizen use -A
of flood control properties and other works of the
District such as reservoirs and flood detention areas .w N % "
for such activities as hunting, fishing and camping;
beginning work on the Lake Tarpon project to Z
prevent flooding and to seal off salt water from 4 'ril
access to the lake, thus allowing it eventually to
become a fresh-water lake; to acquire lands within -
the 850 square miles of the Green Swamp for flood / .
detention purposes and, hopefully, either for direct
aquifer recharge or for later downstream release as Fig 4 Map of Southwe
water supplies to the rapidly growing coastal urban trict showing works of
areas; to improve navigation and water conservation the U.S. Army Corps
on the Withlacoochce River by construction at the Florida Water Managem


'I
st Florida Water Management Dis-
river basins which comprise the


st Florida Water Management Dis-
the Four River Basins' Project of
of Engineers and the Southwest
ent District.







Wysong Locks and Dam of the inflatable "Fabri-
dam"; on the purchase of a huge flood detention
area in the lower Hillsborough River to serve also
-as a site for a big, new well field to serve the
Increasing needs of the City of Tampa; on the
replacement of an antiquated and worn-out dam on
the Oklawaha at Moss Bluff with a bigger, new
locks and dam;on the construction of the Masaryk-
town Bypass Canal to prevent a recurrence of some
of the worst flooding experienced in the District
during the 1960 floods; on the construction of the
: Jumper Creek Flood Detention Area and the Tsala
Apopka Outfall Canal on the Withlacoochee River
in Citrus County; and on numerous other projects
such as the Big Cypress Creek Flood Detention
Area including a regional well field.\
Works such as these, including the building
and occupancy of a new headquarters office and
service center on a beautiful oak and pine forested
site 7 miles south of Brooksvillc (Figure 1) occupied
the chief attention of the staff until early 1969.
At that time, owing to growing pressure on
the District's Governing Board to regulate the drill-
'ing of wells and the uncontrolled development of
ground water, the decision was made to establish a
Ground-Water Hydrology Division for these pur-
poses. This was done in March 1969, but was
Quickly reoriented to a Hydrologic Division when
.'it became understood by the administrative and
executive officers of the District that ground water
and surface water in this District are only different
sides of the same hydrologic coin and must be.
managed as a single resource.
Upon the activation of the new Hydrologic
Division, the nucleus was available for the estab-
lishment, under Chapter 373.142, Florida Statutes,
of a Water Regulatory District. This was accom-
plished in July 1969, with the new organization
having the same Board of Governors and the same
District boundaries as the original District. The
staff wrote the draft of a proposed regulatory law
and on October 1, 1969, Chapter 357R-I, Florida
Administrative Code, "Orders of the Southwest
SFlorida Water Management District (Regulatory)"
became effective. Chapter 357R-1 defined the rules
and regulations for the development, use, control,
and conservation of water and related land re-
sources, with particular reference to ground-water
resources in the District. Its several sections pro-
vided for: (1) Purposes and definitions; (2) Regis-
tration of well drillers; (3) Construction of wells;
S (4) Inventory of wells and water uses; (5) Civil
action for damages; and (6) Penal provisions.
Under these regulations the registration of all


well drillers and engineering laboratories drilling
holes of 2 inches in diameter or larger was begun
on January. 1, 1970; all drillers of good repute and
adequate experience were "grandfathered" in dur-
ing this first year but any not registered by January
1, 1971, were required to take both a written test
in the office and a demonstration test of drilling
skills using their own rigs "on the job."
In the office, IBM card systems were set up
for data control, filing, retrieving and processing.
Before many months had passed the staff was
processing an average of nearly 1,000 well permits
and well completion reports each month and to
date have registered 297 well drilling contractors
and 1,107 drillers. A total of 22,939 well drilling
permits have been processed from January 1, 1970
to December 1, 1972.
Owing to unforeseen weaknesses and incom-
plete coverage of our initial rules and regulations
(357R-1), revisions were made and adopted as
Chapter 16CC, Florida Administrative Code, effec-
tive February 3, 1972. Later, on July 1, 1972, the
Hydrologic Division was given broader functions
and entitled the Water Resources Division; simul-
taneously the biologists of the Environmental
Team, previously a unit loosely attached to the
Office of the Executive Director, were made the
nucleus of our newly established Environmental
Department. This rearrangement allows for better
use of personnel, equipment and facilities, and the
organization as needed from time to time of ad hoc
teams of hydrologists, geologists, biologists and
engineers to attack practically any problem of
environmental, water resources, or engineering con-
cern. Currently, a Planning Division is being estab-
lished. Other Divisions, whose titles suggest their
areas of responsibility are: Administrative, Legal
and Office of the Senior Scientist-Chief Hydrol-
ogist, Engineering, Environmental, Field Opera-
tions, Finance and Accounting, Real Estate, Tech-
nical Services and Water Resources.
Although the Four River Basins' Project is still
the largest in terms of money and manpower ex-
pended on District programs, the problems relating
to water supply have taken over the major emphasis
of our present planning. Scarcely a day passes-if
ever-that water or water-related problems some-
where in the District do not make newspaper, TV
and radio headlines. Or saying it another way,
water and water-related problems are always in the
news and by far the most of these relate to water
supply.
In order to find solutions to these water prob-
lems and to manage water adequately, it is neces-


_ _







sary that we understand the nature and occurrence
of our water resources. Basic to this understanding
is the determination of how much of what kind of
water is where and how it varies in quantity and
quality, both in space and in time. To gain this
essential knowledge we rely heavily upon a compre-
hensive, cooperative arrangement with the U.S.
Geological Survey to develop both the systematic
and special basic data needed for management
purposes. This is supplemented by generalized
geologic and hydrologic studies df Florida by the
Florida Department of Natural Resources in co-
operation with the U.S. Geological Survey and the
Southwest Florida Water Management District. The
information supplied as a result of these coopera-
tive agreements covers such areas as: (1) flows and
stages of streams; (2) flows and stages of ground
water; (3) study and description of both the
chemical and biologic quality of ground and surface
waters; (4) investigation and description of lakes,
aquifers and aquicludes; (5) preparation of water
table and potentiometric maps for various places at
different times of the year; (6) evaluation and
description of the water resources of areas of
particular interest, such as for example, the Green
Swamp, the Gulf Coastal zone of salt-water en-
croachment, the "world's biggest orange grove," an
area of 62 square miles in DeSoto County, and the
phosphate-mining district in the upper Peace and
Alafia River basins; and (7) others such as one or
more contiguous counties not previously studied in
detail. Topical cooperative studies include such
subjects as: (1) deep well disposal of waste waters;
(2) the effects of spray irrigation disposal of sewage
effluent; (3) the artificial recharge of aquifers;
(4) salt-water encroachment; (5) the development
of aquifer and river basin digital models; (6) ground-
water-surface-water relationships; and (7) forecast-
ing the formation of sinkholes. This is far from
being a complete list of areas and topics of study
but is fairly representative of the scope of our
cooperative program with the U.S. Geological Sur-
vey. This cooperative arrangement, covering fiscal
years 1963 through 1972, has amounted to a total
of $4,220,300 of which the District has contributed
one half and the Survey the other half. The pro-
gram has steadily grown from its inception and is
now funded (1973 FY) at $607,000 (both sides
included), but it is still inadequate to cover our
needs of data for water management purposes.
To supplement the U.S. Geological Survey
cooperative program, special studies are contracted
with consulting firms of engineers, hydrologists and
environmentalist; and basic to all our field studies


is a program of mapping the District, piece by piece
as funds become available, by photogrammctric
methods. Most mapping is done on a scale of 1 inch
equals 200 feet and with 1-foot contour intervals.
This mapping is done by contract with firms
specializing in photogrammetry.
In addition to the work done and data
assembled by the U.S. Geological Survey, the
consultants and the photogrammetric firms, the
District staff of 24 water resources professionals
and 9 subprofessionals gathers a vast amount of
field information both personally and from the
well completion reports required by law to be
completed and sent in by the well drillers operating
within the District. Such data are filed, stored and
later retrieved as needed by use of IBM computer
facilities supplemented with standard filing and
storage systems. Special studies of all available
data are combined to make management decisions
on all levels ranging from the regulation of pump-
ing regimes and quantities of water pumped from
existing wells and well fields to the granting or
denial of a permit for a new well, the plugging and
abandonment of an old one, the taking of water
from any surface-water source, or the dredging,
filling or building of structures in canals or streams
of the District. Likewise, decisions are made re-
garding whether or not a proposed new well field
may be developed and if so-how, where, and when.
Conditions of its drilling, completion and subse-
quent operation are carefully regulated to avoid
overdevelopment of the resource or damage either
to the environment or to existing water-supply
developments.
Additionally, operations of existing well fields
and all other large sources of withdrawal are being
strictly monitored and controlled. This has already
led to orders for the reduction of pumping from
existing well fields of the City of St. Petersburg, of
the County of Pinellas, and specific wells of the
phosphate industry. Orders for reduction of exist-
ing large scale. pumping related to excessive or
inefficient use of industrial and agricultural waters
are now being finalized. Currently our knowledge
of water use and withdrawals largely depends upon
unverified reports from the operators. The new
orders will require the metering of all water from
large capacity wells or other sources, and quarterly
reporting by the operators of their withdrawals and
final disposition of the withdrawn waters. Thus, for
the first time in any large area of Florida, total
measured withdrawals and total consumptive uses
will be .known. Such information is essential for
proper management and eventual allocation of


-I


__








water resources for whatever uses man needs to
make of them.
C Environmental assessment of proposed land
developments, drainage proposals, eutrophication
control schemes for lakes and reservoirs, and many
other similar or related studies are a regular part of
our activities. The staffers making these studies and
management decisions, some of which are in the
form of recommendations for action either to the
District Governing Board or any of th'e 11 District
Basin Boards, consist (as of 12-1-72) of 3 biologists,
11 engineers, 3 geologists, 4 hydrologists, 3 hydro-
geologists, and 9 hydrotechnicians.
The staff also engages in a wide variety of
"people-service" functions. These include such
matters as:
1. Preparation and publication of The Hydro-
scope, the monthly journal printed to keep the
public informed not only of current important
happenings affecting the water resources of the
District but enlightening our nonprofessional read-
ers on interesting or current technical matters (Vol.
1, No. 1 was issued in January 1970). Recent topics
have included articles on salt-water encroachment,
how to interpret and utilize potcntiomctric maps,
S the meaning and value of hydrographs, the nature
of our water-supply problems and how to use the
water budget approach to determine the adequacy
of our water resources for future population
growth, the size and location of new well fields,
and many others.
2. Participation in meetings of learned and
scientific societies, engineering and professional
associations, public forums, seminars and the giving
of talks or speeches before Boards of County Com-
missioners, City Councils, scholastic groups ranging
from university level to the elementary school, and
active membership in citizen-sponsored a c t i o n
groups seeking such objectives as new and improved
water treatment and/or sewage treatment plants, or
the end to a drainage scheme or one of land
Development that could be damaging to the water
resources or to the environment.
3. Planning for the acquisition of new flood
water detention areas and/or new well fields that
would be integral parts of a regional water-supply
system for selected parts of our urbanizing areas
and their conjunctive use for citizen enjoyment,
Including camping, fishing, hunting, bird-lore,
school "Outdoor Classrooms," nature trails, canoe-
ing courses, and others.
Now at this point, it may be well to describe


the nature of some of the water-supply problems
we are working on and some of the solutions to
these problems that are either proposed or have
been determined.
The number one problem relates to how much
water is available for water-supply purposes and
how much water can be withdrawn from what
sources for consumptive use. Currently we can only
derive "ball-park"- values, because, with the" kinds
of basic data available to work with, this is the
best that can be done at the present time.
To quantify the water-supply situation we
make use of the water budget method. However,
we must use the results we obtain with caution,
recognizing that they are only "ball-park" values
because all the factors we plug into our equations
are themselves only approximations. Precipitation,
for example, is measured at widely scattered
stations over the District and most of the records
are short, in the order of 10 years or less; few
exceed 50 years. Thus, precipitation values are not
nearly as good as needed. The long-term average
rainfall over the District appears to be about 55
inches per year.
Runoff, the discharge measured in surface
streams, is perhaps even less well defined than
precipitation. Runoff records are shorter, few
exceeding 40 years; and, to avoid tidal conditions
in the estuarial sections of our coastal streams,
gaging stations are generally several miles or more
inland from the stream mouths. Thus the runoff
increment in the stretch between the gaging station
and the stream mouth is unmeasured and must be
estimated. Total, long-term average runoff the
District over, is apparently about 15 inches per
year.
Ground-water discharge into the lower, tidal
portions of the streams and into the Gulf of Mexico
via shore zone seeps and submarine springs cannot
be measured directly so must be determined in-
directly. Likewise, storage and flow of ground
water in the aquifers cannot be measured directly
as is streamflow; therefore, such information must
..be derived indirectly from study of pumping test
data that give us approximate values of the co-
efficients of transmissibility, storage, and leakance,
and from potentiometric and water table maps that
provide us with gradients and lengths of flow sec-
tions through the saturated thickness of the
aquifers.
Adding to our quantification problem is the
fact that there is no direct way of measuring evapo-
transpiratioj losses. Generally, evapotranspiration
(Et) values are derived as a residual by subtracting






runoff (R) from precipitation\ all in inches of
water. This is more reliable the longer the period of
record and should be at least a year long. By
starting and stopping each water budget period at
the same time of.year the annual cycle of wet and
dry periods will be complete, and no accounting
may therefore have to be made of changes in
storage in ground- or surface-water bodies, or in the
soil moisture above the water table. If significant
changes in storage have occurred, these then must
be plugged into the right-hand side of the equation.
Runoff is essentially the measure of the total
potential water crop, but it is only a potential, not
an actual measure of what can be taken for con-
sumptive use. Some water must be left to maintain
the flow in the streams and to prevent lakes,
swamps and marshes from drying out. For once-
only use, as is the common current practice here in
the Southwest Florida Water Management District,
it appears that we'd be lucky indeed if we could
capture and use more than '/3 R. How much would
this be, and how many people would it supply with
the amount of water they will need?
First, let's calculate the yield possible to ob-
tain from the 15 inches of R. One inch of R from
one square mile for one year is approximately 17.4
million gallons. '/3 X 15" 5", the expected water
crop, and 5" X 17.4 mgy/mi2 = 87 mil. gal/mi2/yr.
From 10,000 sq. mi. the "ball-park" value of the
water crop would be 870 billion gallons, or 0.87
tgy (trillion gallons per year).
Current District water use data are still in the
process of being computed and in the absence of
actual values, we shall estimate that the usage is
about 1,000 gpcd (gallons per capital per day). This
compares with U.S. Geological Survey figures for
the 1970 national use at 1,800 gpcd. Our rate of
use here is lower than the national use inasmuch as
we have fewer heavy industries and smaller agricul-
tural uses in the District than in the industrial East
and the irrigated West. Nonetheless, our huge
phosphate and citrus industries are very large users
of water and run the gpcd figures up from around
175-250 gpcd for our larger cities, and 100 gpcd
for village uses, to this higher estimated District-
Swide value.
The population of the District is now about
1.75 million people and it is generally forecast by
demographers that this will double by about 1985.
Given 1.75 million persons and 1,000 gpcd once-
only usages, our current water demand is about
365,000 gpcy (gallons per capital per year). This
totals 638.75 bgy (billion gallons per year) or 0.64
tgy (rounded).


With an cl ated available average annual
water crop of 0.87 tgy and a water use of 0.64
tgy, we currently have a surplus of 0.23 tgy, or
enough water for a population increase of about
630,000 persons. Thus, on the basis of these
estimations, we will be using all of the available
water crop before 1985 and water mining will
begin on a large, increased scale unless ways are
found either to augment the water crop or decrease
usage, or both.
So we have cause for concern, but not for
alarm. Even if before 1985 we use all the annual
water crop, we will not be running out of fresh
water. The great Floridan Aquifer (our huge "water
barrel") underlies the State everywhere and here
ranges in thickness from about a thousand feet to
more than 2000 feet. Totally, under the nearly
10,000 square miles of the District, the Floridan
Aquifer stores far more fresh water than is stored
in all of the Great Lakes combined.
-However, there is a limit to the amount that
we may "mine" from this great aquifer, for much
of its fresh water is in dead storage, a dead storage
imposed by the Ghyben-tlcrzberg principle of salt
water-fresh water relationships. The Floridan pen-
insula is surrounded by ocean water and every-
where, at some depth, it is underlain by salt water
some of which is more than 3 times as salty as the-
ocean.
So, except for relatively short periods of time,
we dare not draw the regional water level down to
or below sea level. Thus we can only safely use
that part of this huge lens of fresh water that is
above sea level and this is a comparatively small
part of the total volume in storage. If we were to
manage our ground-water withdrawals so poorly as
to deplete the top storage (the part above sea level),
the bottom storage (the part below sea level) will
slowly shrink in direct proportion to top-storage
depletion and as a consequence salt water would
move both inland from the Gulf and upward from
below. Once this happens it would be practically
impossible to get the salt water pushed back out.
However, even salt-water encroachment is not
all bad, for it furnishes us with an abundant supply
of brackish water that can be sweetened for water-
supply purposes. Recent breakthroughs in the
reverse osmosis (RO) method have apparently made
this method competitive with development and
transport of fresh-water supplies via pipelines from
distant well fields. The newest, and probably the
most efficient desalination plant in the U.S., is thli
500,000 gpd RO plant at Rotunda West on Char-
lotte County's Placida Peninsula, about 20 miles




I L ~ L~i


west of Punta Gorda. This new plant was installed
in 1972 at-a cost of $385,000, including pumps,
wells and treatment plant. Rotunda plans to expand
this plant to 2 mgd in the near future. Cost of
treating brackish water from wells at the site and
reducing the 7,000 ppm chloride in the untreated
well water to less than. 250 ppm with only one
pass through the exchange medium is expected to
be about 50 cents per thousand gallons. Rotunda's
- engineers calculate that such water can be profit-
" ably delivered to their consumers at 85 cents per
thousand gallons. The salty waste water produced
is piped to the nearby Gulf of Mexico where it is
swept away by the tides to mingle harmlessly with
the vast salty waters of the Gulf. \
In summary, water management controls are
needed to prevent this region and our District from
becoming hydrologically bankrupt. It appears that
by about 1985 we will be using all of the average
annual water crop and, as a consequence, unless
action is taken in time to forestall it, we will be
mining water on an increasing scale. Water is
already being mined on a large scale in the phos-
phate field of the upper Peace River basin where
the potentiomctric surface of the artesian writer in
the Floridan Aquifer has dropped 20 to 60 feet
over an area in excess of 1,000 square miles during
the last 20 years. Some of the preventative and
conservation measures we may employ include:


A. Reduce R (runoff) losses to the Atlantic Ocean
and the Gulf of Mexico.
1. Establish and utilize additional flood reten-
tion reservoirs.
2. Create recharge facilities in association with
such reservoirs to hurry flood waters into
aquifer storage.
3. Establish salt-water control dams on tidal
canals and- streams and place these dams as
near the shoreline as feasible. Hold a fresh-
water head behind each dam at least 2'/ feet.
above mean sea level and higher if possible.
These water control structures will not only
prevent bleeding off of fresh water, but will
prevent salt-water encroachment both in the
dammed-off section of the canals and streams
and also in the aquifer at depths directly
related to the height to which the fresh-water
head can be held above msl (mean sea level).
This is in accordance with the Ghyben-
Herzberg principle which states that, for each
foot of fresh-water head above msl, the under-
lying salt water is depressed about 40 feet.


B. Reduce Et evapotranspirationn) losses.
1. Evapotranspiration loss reductions can best
be accomplished by lowering the water table
in swampy and marshy places below the reach
of water wasting plants. Choices of areas and
plants that must be preserved and protected
against greatly lowered water levels will have
to be made in order to decide what areas can
be utilized and what ones cannot. Some areas
must be saved from lowering the water level
in order to preserve natural forest and swamp
environments for esthetic purposes as well as
for wildlife sanctuaries and human enjoyment.


C. Reduce waste of water.
1. Increase charges for water, particularly for
the large users, who now, for the most part,
pay for their water at a rate which declines as
the water used increases. Possibly water sever-
ance taxes should be utilized for large, non-
public users, so as to obtain the joint benefits
'of augmenting District income (needed to pay
for increased costs of water supply and man-
aemient) and causing water users to be con-
cerned with wasting. The more costly the
water; the less the users are likely to waste it.
2. Require reuse of water for those municipal,
commercial, industrial and agricultural efflu-
ents that are practicably reusable. Once
through the mill and then discharge to the
ocean is a wasteful luxury that no longer can
be tolerated.
3. Many irrigators now put far too much water
on their crops. Irrigators should be educated
to use only as much water as is actually
required. Some advantageous economies could
be effected by using, whenever possible, high-
grade sewage effluent, including its load of
nutrients (N, P and C) instead of pumping
additional raw water from wells. Use of such
enriched water would save the farmer, or
rancher or golf course irrigator from having to
apply artificial fertilizers and thus save him
money while at the same time reducing nutri-
ent runoff to the streams. A gallon of such
water used in this manner saves an additional
gallon from being pumped from the aquifer
thus extending our water crop.
4. Numerous abandoned artesian wells are now .
flowing to waste, depleting the aquifers and
causing salt-water encroachment in the coastal
areas and lowered water levels inland. Each of
these wells should be plugged securely from







bottom to top to effectively stop this senseless
waste of water.

D. Augment present supplies.
1. Reuse of. water (C-2 and C-3 above) is a
means of augmenting current supplies.
2. Preventing salt-water encroachment is an aug-
mentation of existing supplies.
3. Recycling cleaned-up sewage wastes is one of
otir biggest sources of "new" water. Most
municipal sewage is 99% reusable water. Being
run through "tertiary" (extended secondary)
treatment to reduce impurities of all kinds and
result in a product that is at least as good as
water naturally available in the aquifers and
streams of the area, would make such water
available for human reuse after being artifi-
cially recharged to our aquifers or mixed with
streamflow. Just one reuse of a year's water
crop would allow the water crop to go twice
.as far. Or, saying it another way, it would
serve twice as many people. This can be done,
but at a cost. It is a cost that, eventually, we
must pay. The question isn't if we should do
it, the question is only when and how shall we
do it?
4. Capture as much flood flow as we can and
inject it into the only available large storage
reservoir-the Floridan Aquifer. This can be
accomplished best by developing flood de-
tention reservoirs with discharge works lead-
ing to those parts of the District where large
drawdowns of water level have created billions
or trillions of gallons of available storage
volume. Some such large storage capacity
exists in the areas of pumping influence that
surround every large well field in the District,
but the largest potential storage is in the areas
of large drawdown around the phosphate and
citrus production areas, mostly in Polk, eastern
Hillsborough and eastern Manatee Counties
where, over more than a thousand square
miles, water -levels in the Floridan Aquifer
have declined 20 to 60 feet or more in the
last 20 years.
5. Locate and operate regional well fields and
recharge facilities so as to manage withdrawals
and replacements (recharge) scientifically. Well
fields should be hooked up into regional
systems much as the electrical industry has
done their generator plants and power distri-
bution systems.
6. In areas where water is now being "mined,"
that is pumped out at a rate faster than nature


-I--CLL--WL-LUIIUrr.-iillu


replaces it, allow no more large-scale water
devclopmcnts and work to eliminate waste
and extravagant uses of water supplies in such
areas. f
7. In the shore zone region which has been
invaded by salt-water encroachment and in
some inland areas containing brackish ground
water, immense supplies of brackish water are
available, particularly in the upper parts of the
Floridan Aquifer of southern Florida. This
water ranges from nearly as salty as the ocean
to only slightly more salty than normal ground
water. Much of it a mile or so inland is only
mildly saline (1,000 to 7,000 mg/l) and can
be economically reclaimed for use. This will
be more costly than use of fresh water (if it
were locally available), but is comparable to
the cost of developing and transporting fresh
water from distant well fields. Some day we
will do this on a large scale, and it may not
be far off, particularly if the coastal counties
cannot import the fresh water they will need
to obtain from outside their county bound-
aries. We must remember that the coastal
counties are at the downstream end of nature's
pipeline; the upstream end is in those inland
counties mostly to the cast, and is included
within the boundaries of the Southwest Flor-
ida Water Management District.
8. Import water from distances up to several
hundred miles, such as from the aquifer up-
gradient from Weekiwachec Springs, Chassa-
howitzka Springs, Homosassa Springs, Crystal
River Springs and others, or even farther,
from such large north Florida streams as the
Suwannee or Apalachicola. But this will be
costly, probably much more costly than any
other means previously mentioned. Nonethe-
less, it has been done elsewhere in places
such as Boston, New York, Los Angeles, San
Francisco and Denver; it could also be done
here. Hydrologic and engineering studies will
have to be made by the District to evaluate
just how much these alternatives will cost.
Then, with such knowledge, the taxpayers
will be in a position to make the necessary
choices.

E. Mine the aquifers. The Floridan Aquifer and its
overlying shallow system of water table and low
pressure artesian zones contain far more water in
storage than all the Great Lakes combined. In
the District, for example, the upper 1,000 feet
or more is generally filled with fresh water inland






from the 25-foot contour on the C-,ntiomctric
surface. However, salt water underlies this aqui-
fer system everywhere and bounds it on the
C west all along the shore. If the aquifer is over-
pumped, salt-water -encroachment slowly but
eventually follows. Tampa and St. Petersburg,
to name only 2 large users, lost their original
coastal zone well fields to salt-water encroach-
Sment in the 1920's; now other coastal cities,
Such as New Port Richey, are undergoing the
Same loss. Additionally, thousands of private
wells in the shore zone that extends generally
inland from the Gulf of Mexico to about the
10-foot contour on the potentiometric surface
either have been ruined by salt-water encroach-
ment or are in imminent danger of the same
fate. And this is extremely serious because this


zone includes mos[ our rapidly urbanizing
area where the largest amounts of water will be
needed to supply its burgeoning population.
Great care must be taken that the aquifer not
be mined of its fresh water with resultant salt-
water encroachment. Detailed research is cur-
rently underway to develop better knowledge of
the aquifer's hydrologic characteristics so that
realistic, effective management decisions can be
reached.

Right now we have considerable generalized
and some specific information and hydrologic
understandings that will serve to guide us until
better and more detailed data are available: We can
make do, then, for awhile. But, we can't afford to
dally. The situation is upon us now.


I U I Ad




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