Water-level fluctuations of lakes in Florida ( FGS: Map series 62 )
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF90000313/00001
 Material Information
Title: Water-level fluctuations of lakes in Florida ( FGS: Map series 62 )
Series Title: ( FGS: Map series 62 )
Physical Description: 1 map : col. ; 41 x 51 cm.
Language: English
Creator: Hughes, G. H ( Gilbert H )
Geological Survey (U.S.)
Florida -- Bureau of Geology
Publisher: The Bureau
Place of Publication: Tallahassee
Publication Date: 1974
Subjects / Keywords: Lakes -- Maps -- Florida   ( lcsh )
Maps -- Florida   ( lcsh )
Lakes -- 1:2,000,000 -- Florida -- 1974   ( local )
Lakes -- 1:2,000,000 -- Florida -- 1974   ( local )
1:200,000 -- Florida -- 1974   ( local )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
single map   ( marcgt )
Maps   ( lcsh )
Statement of Responsibility: by G. H. Hughes ; prepared by United States Geological Survey in cooperation with the Bureau of Geology, Florida Department of Natural Resources.
Bibliography: Bibliography.
General Note: Includes text, 2 insets, 4 graphs, and diagr. of elements affecting lake-level fluctuations.
Funding: Map series. (Florida. Bureau of Geology) ;
 Record Information
Source Institution: University of Florida
Holding Location: George A. Smathers Libraries, University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: aleph - 001820167
oclc - 07691703
notis - AJP4154
lccn - 80695115 /MAPS
System ID: UF90000313:00001

Full Text




published by BUREAU OF GEOLOGY


I I -T I I I I I I


by G.H. Hughes

Prepared by
in cooperation with the


The fresh-water lakes of Florida are of importance not only because
they constitute sources of water supply but also because they provide
countless and diverse opportunities for camping, fishing, boating,
swimming, and other types of outdoor recreation.
Unfortunately, the various recreational uses of lakes are not entirely The
compatible and, also, they may conflict with other established lake intense
uses. Furthermore, intensive use of lakes for any purple of lakes for y pu se generally surface
leads to deterioration. Thus, protection of public and private interests control
alike requires some degree of control and management of the water with t
quality and level of lakes, contris
Wise and effective management of lakes in turn requires knowledge materi
of lake hydrology. The purpose of this report is to promote the under one or
standing of lake hydrology, particularly as it pertains to the nature and Fac
causes of lake-level fluctuations. The chemical and biological condition lake s
of lakes is closely related to the hydrology of lakes, but for the sake of transpi
brevity is not discussed. from t
The fresh-water lakes of Florida are plentiful and generally well Transp
distributed within the State. A recent tabulation (Florida Board of driving
Conservation, 1969) lists 7,712 fresh-water lakes in Florida, including differ
all lakes named on topographic maps of the U.S. Geological Survey and species
unnamed lakes having surface areas of 10 acres or more. Most of the from a
lakes cover less than 100 acres, about half of these less than 20 acres; Disc
930 lakes have surface areas greater than 100 acres and 115 have with ti
surface areas greater than 1,000 acres. The largest, Lake Okeechobee, with it
covers 436,000 acres. Although about 35 percent of the lakes are in 4 some i
counties-Osceola, Orange, Lake, and Polk-12 counties each have more altitude
than 200 lakes and only 15 counties have less than 30 lakes. The as tha
number of lakes listed for each county of Florida is shown on the State restrict
map. Leak
The U.S. Geological Survey has recorded lake-level fluctuations at in leave
some of the important lakes in Florida for many years, in cooperation with tl
with State, local, and other Federal governmental agencies. As of 1972 Water s
lake-level records were being collected at 160 lakes. Included in this The
total are'both meandered and non-meandered lakes. A meandered lake conditi
is one whose approximate shoreline was established by a series of levels
survey lines in the original land survey of Florida. All navigable lakes Rainfal
were supposed to be included in the survey but only about 200 of the as prev
many lakes considered navigable were surveyed. Responsibility for same w
managing the bottom lands of the meandered lakes rests with the the ws
Trustees of the Internal Improvement Trust Fund. Through a substar
cooperative agreement between that agency and the U.S. Geological example
Survey, lake-level records as of 1972 were being obtained at 72 lake le,
- meandered lakes including most of the large ones. confine
Records for some lakes in central Florida begin in the late 20's and above 1
early 30's; for example, that for Lake Kissimmee begins in 1929 and for the dif
Lake Okeechobee in 1931. Records spanning 20 years or more are a confi
available for several lakes throughout the State. Continuous water- level potent
recorders are operated at some of the lakes; daily, weekly, or less periods
frequent observations are made at others. Over the years lake- level portray
records have been discontinued at about 100 lakes. Bay La
lake let
Between significant wet and dry spells, the range of fluctuation in lake an
level varies greatly among lakes: as small as 2 feet for some lakes, more lake.
than 30 feet for others. About 80 percent fluctuate 5 feet or more as confine
indicated in figure 1. side of
Levels of lakes connected by a throughgoing stream tend to fluctuate may ga
together but the range of fluctuation may differ significantly. Since while l<
1935 the fluctuation in level of a group of large lakes on the Oklawaha
River has ranged from 4 feet at Lake Griffin to 6 feet at Lake Eustis. WHY
Since 1942 the maximum fluctuation in level of lakes on the main stem
of the Kissimmee River has ranged from 9.2 feet at Lake Cypress to The
12.4 feet at Lake Kissimmee. Several other lakes connected to the runoff,
Kissimmee River by lateral streams or canals fluctuate in levels less than or they
5 feet The difference in the magnitude of lake-level fluctuations is causes l
marked in a chain of lakes on a small creek in Clay County where since Give
1957 the fluctuation. in level has ranged from only 2 feet at Sand Hill differed
Lake to 10.2 feet at Brooklyn Lake. variabil
Levels of lakes in the same general area often fluctuate together, even Much c
though they are not connected by a throughgoing stream, but again the depress
range of fluctuation may differ significantly. Pebble Lake and Kingsley greatly
Lake in Clay County are only about 10 miles apart in what appears to many s
be similar terrane. Yet since 1945 the range of fluctuation in level of evenly
Pebble Lake is about 10 times greater than the range for Kingsley Lake, rainfall
as indicated in figure 2. generate
An understanding of lake-level fluctuations, and of why they may variation
differ in magnitude so greatly for nearby lakes, is best obtained from natural
consideration of the hydrologic system of a lake. The elements of such parts o:
- a system are portrayed by the diagram in figure 3 for two types of lakes air tern
that are common in Florida. the avi
The hydrologic system of a lake involves rainfall, evaporation, radiatic
runoff, and the interchange of water between the lake and one or more Thus, t
aquifers. In Florida two types of aquifer generally are involved: an same ft
unconfined aquifer and a confined aquifer. The confined aquifer is lakes b
recharged by downward leakage from the unconfined aquifer and from the san
lakes and streams, and directly from rainfall in instances where part of
the aquifer is exposed at the land surface. A confining bed of relatively
impermeable material maintains the water of the confined aquifer
under pressure generated by the level of water in areas where the
aquifer is recharged. The water of the confined aquifer is discharged in
areas where the confining bed is breached or fractured and where the
static head of water in the confined aquifer is above land surface. The
static head of water in an aquifer is represented by the potentiometric
surface, which is defined by the levels to which water will rise in tightly
cased wells penetrating the aquifer. The water table is the
potentiometric surface of an unconfined aquifer.
The distinguishing features of the two types of lakes shown in figure
3 are as follows: Lake A represents a landlocked lake in an area where
recharge of the confined aquifer occurs. The level of lake A is above the
potentiometric surface of the confined aquifer. Thus, given the required
opening in the confining beds, water moves downward from lake A into
the confined aquifer. On the other hand, lake B represents a lake with a
surface outlet in an area where discharge from the confined aquifer
occurs. The level of lake B is below the potentiometric surface of the
confined aquifer. Thus, given the required opening in the confining bed,
water moves upward into lake B from the confined aquifer.
Lake-level fluctuations are the net effect of factors that cause the
lake level to rise and factors that cause the lake level to decline. Factors
that cause the lake level to rise are lated to rainfall, the source of
water for all fresh-water lakes in Florida. Part of the lake water comes
directly from rainfall on the lake and part comes from surface- and
ground-water inflow derived from rainfall on the drainage basin of the Figure
lake. The extent of the lake-evel rise varies with the size of the lake and fluctu
the magnitude of the inflow.

ity of rain
r, and wi
outing land
the differ
buting aqu
als along fr
r more aquif
etors that ca
surface, too
nation by
the lake, di
and leakan
s more grad
e evaporat
ally folio'
imation var
% energy ft
nces. If the
t in the win
water surf
charge of wa
he height o
the size and
instances m
e of the ba
t of the i
ted by the c
kage of wal
Is of water
he hydraul
may leak fr
on. In real
are contain
ll is the son
Piously stat
way that la
water in th
itially beto
le, figure 4
vel remains
ed aquifer
the lake lev
ference bet
ined aquife
metric su
s to above
yed by the
ike the wa
vel when t
the lake le
iometric su
,d ground-w
At large la
id aquifer
the lake a
ain water f
losing water


elements th
for examp
may vary I
lake-level fi
n similar la
nces in the
ity of rain
of the rain
sons. The
over a dis
uch storms
on the lak
ed by the
area; but
erences in
ins in evap
f Florida. I
perature, a
ailable ene
on, and ev
the decline i
or lakes in
because the
me degree.

3.-Diagrammatic section showing elements that affect lake-level
nations of lakes A and B.

1966 1967
Figure 4.-Seasonal fluctuation of level of Lake Sherwood
(blue), water-table aquifer (red), and potentiometric surface
of confined aquifer (black).

Figure 5-Seasonal fl

S s o N D J F A MJ j This public document was promulgated at a total
1967 1968 cost of $425.00 or a per copy cost of $.29 for the

uctuation in levels of Bay Lake, Orange purpose of disseminating geologic data.

County, Florida, and potentiometric surface of confined
aquifer (Floridan) underlying Bay Lake, January 1967 to
August 1968.

0 10 20 30 40 s0

--A 1

-- a


3 3 .
WALTON 0 *"*
Y 58 i 2 J \

BAY 3 LEON [ 55 1Y
S4 9 1 1 1

i of surface-water inflow varies with the quantity and -AKULLA 3 / COLUMBIA
fall, with the size and slope of the contributing land LIBERTY4 TAYLOR 0 _
ath the permeability of the materials beneath the I
d surface. The magnitude of ground-water inflow varies I ~-
ee in e levels of water in thelake and water in the LAFAYETTE > \
lifer, and with the hydraulic conductivity of the UL UNION
he path of flow. Ground water may enter the lake from 2 ',L: ST. JOHNS
ifers. L A 0 .
cause the lake level to decline are evaporation from the -
anspiration by aquatic plants growing in the lake,
peripheral vegetation that draws part or all its water I L
discharge of water through or over the rim of the lake GILCHRIST AACHUA THAM
ge of water through the lake bottom. The decline in DIXIE 101 1 I1A 263 0 -
dual and generally longer lasting than the rise in level. 76 A
ion occurs continuously but it varies diurnally and
wing a cyclic pattern et by solar raditionind movement may differ greatly hence, evaporation from small lakes n
ties similarly because Solar radiation is the source of May iffer appreciably. For example, evaporation from a s..alllake in a LEV Y 0 '
or both processes; however, plants do impose some large, flat, and open area would be about the same as evaporation from 101
e plants die or become dormant, as occurs with some a large lake in the same general area. However, if the small lake is 1 101 *
enter, transpiration ceases while in Florida evaporation shielded from wind because it sits low in a sinkhole depression or is
sace continuesS surrounded by tall and dense vegetation, evaporation from it might be- \
after through or over the rim of the lake basin varies markedly less than from the large lake. MARION
f the lake level above the spill level of the outlet and One of the chief causes of differences in the magnitude of lake- level MARI284 VOL
A shape of the outlet. Discharge through the outlet in fluctuations is the variability in permeability of materials beneath the 84
Say be restricted by a control structure. Where the land surface. In combination with the slope of the land surface, the
banks of the downstream receiving channel is the same permeability of materials determines the extent to which rainfall runs
ake rim, discharge of water from the lake can be off the land surface or percolates down to the water table. Other things 0 Y. 7 ---- ,1
capacity of the receiving channel. being equal, a lake that receives water primarily from surface-water
ter through the lake bottom varies with the difference inflow will have a greater range of fluctuation than one that receives I -
r in the lake and water in the receiving aquifer, and water primarily from ground-water inflow. The permeability of CI
ic conductivity of materials along the path of flow. materials beneath the land surface also determines the extent to which -2 36
om the lake to one or more aquifers, water can leak downward from the lake. In general, the rate of leakage 0 84
in figure 3 essentially represents a steady-state varies directly with the permeability of the materials, and the range of 6 SUMTER
lity such a condition never occurs because the water lake-level fluctuations increases with increasing leakage. N N D 253 s -
ually changing and they change at different rates. Another factor that contributes greatly to differences in the HERNANDO
urce of water for the aquifers as well as for the lakes, magnitude of lake-level fluctuations is the relation between the lake 2R GE
ed. Hence, ground-water levels fluctuate in much the level and the potentiometric surface of the confined aquifer. Lakes in / /
ke levels fluctuate. The hydraulic gradients between recharge areas generally fluctuate more widely than do takes in ----
e lake and water in the different aquifers vary discharge areas. In hilly terrane, the relation between the lake level and /
ween wet and dry sp and and even may reverse. For the potentiometric surface can vary greatly over a relatively short 296
shows that at Lake Sherwood in Orange County the distance. PA s
Above the potentiometric surface of the underlying Although the size of a drainage basin is an important factor in ----
but that the water table near the lake is sometimes determining how much water a lake receives, size alone does not cause
'el and sometimes below the lake level In areas where differences in the magnitude of lake level fluctuations of different o -
tween the lake level and the potentiometric surface of lakes. Given uniform rainfall over similarly shaped lakes and drainage O CEOLA
r is small relative to their ranges of fluctuation, the basins in the same hydrologic and geologic setting, areas of lakes would as S @O
surface may rise from below the lake level during dry adjust in proportion to drainage areas and the magnitude of lake-level HILL ORO... 1 ....
the lake level during wet periods. This condition is fluctuations would be the same for all lakes regardless of size of the 20.. n"
graphs in figure 5 for Bay Lake in Orange County. At drainage basins. The same conclusion would apply to the size of natural 234 POLK
ter table near the lake generally is slightly above the surface outlets because, under the assumed conditions, the flow into
he potentiometric surface of the confined aquifer is and out of the lakes would be proportional to the size of the drainage
level and is slightly below the lake level when the basins; hence, the size of the surface outlets would adjust by erosion to INDIAN RIVER
Surface is below the lake level. The relation between the outflow from the lakes.N RIER
water levels is not always the same on all sides of the On the other hand, if the size of the natural surface outlet of a lake is
makes the potentiometric surface of an underlying increased or decreased, the range of lake-level fluctuations will decrease I I I I I I
may be simultaneously above the lake level on one or increase accordingly. For example, if the surface outlets decreased o MANATEE HARDEE HLNDS
md below the lake level on the other side. A lake also in size, the maximum attainable lake level will be higher than before. PERCETAGE OF LatKES r v C wrv-ea u A F OaLucT 3
rom the unconfined aquifer on one side of the lake The minimum lake level attainable is also higher than before, but the LEVEL EQUALS OR EXCEEDS A IVEN NIUDE OKEECHOEE
to the same aquifer on the other side. increase will be less than for the maximum level because of Fige 1. Cumulative frequency distribution of maximum I
compensating factors. If the aquifers that contribute water to and fluctuation in level of Florida lakes based on records ._ ST. LUCIE
EVEL FLUCTUATIONS DIFFER IN MAGNITUDE receive water from a lake are presumed to be extensive relative to the spanning 0lyears or morefor 110 lakes. SARASOT -
lake, as they usually are, an independent change in the lake level will 15 1
hat affect lake-level fluctuations-rainfall, evaporation, not affect the level of water in the aquifers except locally. If the lake 190
ple-may occur uniformly over large areas of Florida, level is raised as a result of a change in the lake outlet, therefore, the > KINGSLEY LAKE DESOTO
locally. It is the spatial variability of the elements that hydraulic gradient between the lake and the contributing aquifer is (SURFACE OUTLET) MARTIN
uctuations to differ in magnitude. decreased, and the hydraulic gradient between the lake and the 180 -
ike basins in the same hydrologic and geologic setting, receiving aquifer is increased. Ground-water inflow to the lake is --- ---. Lake r
e magnitude of lake-level fluctuations owing to the thereby decreased and ground-water outflow from the lake is thereby o) O
fall are generally short term rather than long term. increased. Depending on the relative importance of ground-water inflow Okec bee
all in Florida comes from thunderstorms and tropical and outflow in the hydrologic system of the lake, the minimum lake CHARLOTTE GLADES
quantity of rainfall from any one storm may differ level attained at the end of a drought may or may not be appreciably
stance of a few miles but the total rainfall from the higher than would have resulted naturally had the lake outlet not been PEBBLE LAKE L_
that occur over a number of months or years is about changed., 120 (LANDLOCKED) U
d. Thus, over the short term the rise in level due to For any change in the hydrologic system of a lake, a reaction must e
e-and, also, due to surface- and ground-water inflow take place somewhere in the system. Because of the relations and inter- m H
rainfall-may differ substantially for lakes in the same relations that exist between rainfall, runoff, lake levels, and ground- 110 LEE E\ BEACH
over the long term the net effect of rainfall is about water levels, the hydrologic system of a lake must be adequately I-
defined before effects of changes can be fully evaluated. U

the magnitude of lake-level fluctuations due to S E /E \ E N/ 1--
oration generally are small The energy available for SELECTED REFERENCES 100
on of water is about uniformly distributed over large U.S. Geological Survey,
ndchumidity-and, hence, determine the proportion-such as wind spof Water Resources Data for Florida: Part 1, VoL 3, Surface /
nd humidity-and, hence, determine the proportion of water rcords-lakes 1961-1970.- 90 7
rgy that is dissipated by processes of conduction, Florida Board of Conservation, \
aporation, are also nearly uniform over large areas. Florida Board of Conservation,
in lake levels due to evaporation tends to be about the 1969 Florida lakes. Part 3, Gazetteer: 145 p. 80 COLLIER
the same general area. This is especially true for large 8J 1940 1950 1960 1970 29
ir surfaces are exposed to wind movement to about F t- o -
For small lakes, however, the degree of exposure to Figure 2.-Contrasting hydrographs of two lakes in Clay
County, Florida. ~Y_ \

I l llno l

Swfindi Avi, 75 9 as 1 Non-meandered lake; stage reco$'obtained
S-. o,,e E F Meandered lake; stage record obtained
Ni--- ro,0o Meandered lake; stage record not obtained

1065 33 Number near county name indicates number
of lakes in county as listed by Florida Board
of Conservation Gazetteer (1969)


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