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STANDARD VIEW MARC VIEW
UNITED STATES DEPARTMENT OF THE INTERIOR
MAP SERIES NO. 69 _GEOLOGICAL SURVEY
MAP SERIES NO. 69
FLORIDA DEPARTMENT OF NATURAL RESOURCES
published by BUREAU OF GEOLOGY
HYDROLOGY OF THE
OKLAWAHA LAKES AREA OF FLORIDA
by P.RW. Bush
UNITED STATES GEOLOGICAL SURVEY
in cooperation with
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
Lakes Apopka, Carlton. Beauclaid. Dora. Etis, Harris, Little Harris,
Griffin,and Yakle are part of a chain of lakes that lis the most prominent
feature of the upper Oklawaha River drainage basin in central Flod1da.
For convenience, this chain of lake is called the Okldwaha lakes in this
report, and the lakes in conjunction with their environs, the Oklawaha
lakes aues. The main use of the lakes is recreation, but the desirability
of most of the lakes for recreation has decreased in recent years.
Certain land-se practices have caused the lake water quality to
deteriorate to the point that swimming, boating, and fishing are better
elsewhere. To date, much hydrologic data have been collected in the
Oklawaha lakes area. This report, prepared by the U.S. Geological
Survey in cooperation with the Southwest Florida Water Management
District, summaries hydrologic knowledge in the area. It provides
hydrologic information for the public, and a bases for future hydrologic
studies pertaining to specific problems, such as water-quality
DESCRIPTION OF THE AREA
Limestone of the Florldan Aquifer underlies the Oklawalh River
drainage bsin. Twenty-five to 200 feet (8 to 61 meters) of sand, clayey
and, and clay covers the limestone and constitutes the water- table
aquifer in the atea of the basin that contains the chain of lakes. (See fig.
1.) The undulating topography, dotted with hundreds of lakes, is
largely the result of subsidence of the land surface caused by
differential solution by water of the underlying limestone and
subsequent collapse of the surficial deposits.
Landforms of generally north-south orientation characterize the
Oklawaha lakes area (Puri and Vernon, 1964). Relief is generally
greatest (75-210 feet, 23-94 meters) in the ridge areas. Lowest altitudes
occur in the valleys where relief (55-165 feet, 17-50 meters) is also least
in the area. In addition to these physiographic differences, there are
also geologic and hydrologic differences among the ridges, valleys, and
The lithology of the water-table aquifer of the ridges and uplands is
one of generalized type, and that of the water-table aquifer of the
valleys is of a second generalized type (Knochenmus, written
communication, 1973). The first type consists of three subunits. The
upper-beginning at land surface-is a thin mantle of fine sand (0-15
feet, 0-5 meters). The middle sbunit is a thicker stratum of fine clayey
sand. The lowermost subunit conists of interbedded and intermixed
sand and clay and overlies the Floridan Aquifer. The permeability of
the water- table aquifer decreases with increasing depth, so that the
lowermost subunit acts as a confining layer and restricts the movement
of water from one aquifer to the other.
The second generalized type, characteristic of the water-table aquifer
in the valleys, is one heterogeneous unit made up of medium sand and
interbedded day layers. Enough clay probably exists in this unit near
the top of the Floridan Aquifer to restrict the hydraulic connection
Categorization of the geohydrologic differences among landforms in
the Oklawaha lakes area stems mainly from what happens to the
estimated annual 49.9 inches (1,270 millimeters) of rainfall (30-year
average of annual rainfall from National Oceanic and Atmospheric
Administration stations at Eustis, Leesburg, and Clermont). The part of
this rainfall that ends up in surface streams, percolates to the Floridan
Aquifer, evaporates, or is transpired varies with the type of landform.
On the Lake Wales Ridge, runoff is low. High sand hills and a water
table far below land surface readily allow most of the rainfall to seep
into the ground. The confining layer under the Lake Wales Ridge is very
thin or missing, so that the water-table aquifer is in hydraulic
connection with the Floridan Aquifer. Consequently, recharge to the
Floridan Aquifer is high. Knochenmus (written communication, 1973)
estimates annual runoff on the Lake Wales Ridge to be 0-4 inches
(0100 millimeters), and annual recharge to be 12-16 inches (300-400
millimeters). The remaining 30+ inches (760+ millimeters) of rainfall is
evapottanspired. Citrus trees, which cover most of the non-swamp and
non-urban land in the Oklawaha lakes area, transpire about 30 inches
(760 millimeter) of water annually (Lichtler, 1972, p. 25). About 48
inches (1,220 millimeters) per year is evaporated from lakes (Kohler
and others, 1959).
According to Knochenrmus (written communication, 1973), the
Sumter and Lake Uplands in the Oklawaha lakes area are moderately
good recharge areas(8-12 inches, 200-300 millimeters annually). Runoff
estimated to be 0-4 inches (0-100 millimeters) from the Lake Upland.
Recharge through the Mount Dora Ridge is hindered by a relatively
thick confining layer, but still averages 4-8 inches (100-200 millimeters)
annually. Runoff from the Mount Dora Ridge is estimated to be 4-8
The Central Valley and the Lake Harris Cross Valley are different
from the ridge and upland areas. In much of the valley area, the water
table is within a few feet of land surface; thus, the potential for
evapotranspiration is greater than elsewhere in the Oklawaha lakes area.
The potentiometric surface (surface defined by the levels to which
water will rise in wells cased into an aquifer) of the Floridan Aquifer is
also dose to or even above the land surface in much of the valley area.
When the water table and the potentiometric surface of the Floridan
aquifer nearly coincide, little vertical gradient exists between aquifers.
Consequently, movement of water between the two aquifers is low.
Knochernmus (written communication, 1973) estimates annual recharge
to the Floridan aquifer in the valley area to be 0-4 inches (0-100
The stated geologic and hydrologic differences among landforms are
necessarily generalized to represent average conditions over the
Oklawaha lakes area. Certain areas of the Central Valley are relatively
high and vertical gradients are probably sufficient to allow rcharg. On
the Lake Wales Ridge along the south edge of Lake Harris, the
potentiometric surface of the Floridan aquifer is as high as or higher
than the water table, so no recharge can occur there.
FLOW, STAGE CHARACTERISTICS, AND
REGULATION OF THE OKLAWAHA LAKES SYSTEM
Of the nine lakes in the hydrologic system discussed in this report.
Lake Apopka has the largest surface area; however, it is also the
shallowest. Lake Harris and Little Lake Harris combined contain the
largest volume of water. Figurem 2 is a diagram of the direction and
average measured or estimated rate of flow in the channels connecting
the lakes, and the volume of water stored in the lakes at the indicated
Lake levels are usually lowest in the spring, when rainfall is low, and
highest in late summer and early fanl, when rainfall is high. Above-
averageor below-average rainfall over a period of months can
noticeably affect lake levels. For example, figure 3 shows that during
the drought period of 1954-56, lake levels declined almost continuously
toward record lows. Again in 1961-62, deficient rainfall over an
extended period resulted in very low lake levels. Above-average rainfall
in 1953, and in 1959-60, produced unusually high lake levels. Ove0 the
periods of record, the largest range in lake level fluctuation has been
about 6 feet (2 meters) in Lakes Eustis and Harris, and the smallest,
about 4 feet (1.3 meter), in Lakes Griffin and Yale.
Lake Griffin has been regulated to some extent for more than 30
years by a control in the Oklawaha River at Moss Bluff, about 8 miles
(13 kilometers) downstream from the lake. The other Oklawaha lakes
have been regulated for somewhat shorter periods. A timber control
was placed in Apopka-Beaudair Canal in 1950, and the present lock
and dam, about halfway between Lake Apopka and Lake Beauclakir (fig.
1) was opened in 1956. Also in 1956, the present lock and dam in
Hainem s Creek at Lisbon was opened. Haines COrek was straightened and
aged about the same time. A non-adjustable control in Yale-Griffin
Canal for many years was replaced recently by a 30-inch (760
millimeter) culvert about 0.3 mlrae (0.5 kilometer) from Lake Yale. The
level of Lakes Dora, Beauclair, and Carlton seems to more closely
match the level of lakes Eustis and Harris after Dora Canal was entarged
about 1958. Apopka-Beaudlair Canal was also deepened in 1958.
Flow- and stage-duration curves show how the natural regimen of
discharge through Haines Creek and Apopka-Beamulair Canal and
fluctuations in the levels of lakes in the chain have been altered by
regulation. The flow-duation curves of Apopka-Beauclair Canal and
Haines Creek for the unregulated periods (figs. 4 and 5) have fairly flat
slopes because the large volume of storage in the upstream lakes tends
to equalize flow. The slopes of the curves representing the regulated
periods are steeper because regulation has caused considerably more
variation in extremes of flow. More water was released during wet
periods, and less water released during dry periods, than would have
flowed from the lakes underpre-regulation channel conditions.
Comparison of the stege-duration curves for Lake Apopka and Lake
Eustis for the regulated and unaegulated periods (figs. 6 and 7) does not
reveal the seemingly drastic changes in the flow tegimen of
Apopka-Beauclair Canal and Haines Creek. The shape of the curves for
the regulated periods is similar to that for the unrgulated periods.
Increasing the range of discharge variation in the two channels did not
noticeably reduce the range of fluctuation of Lake Apopka and Lake
Eustis, and also Lakes Hardris, Little Harris, Dora, Beauair, and Caton
for the periods of record compared. But it is likely that lake stages
hglher than those recorded during the 195940 wet period would have
occurred if channel improvements had not been made. Similarly, the
drought of 1961-62 would probably have caused lower lake levels than
the that 9 c00eed f dishadge bed not been controlled.
LAKE BOTTOM CONFIGURATION AND COMPOSfTION
The most prominent features of the lake bottoms are the relatively
deep trenches in Lakes Harris, Eustis, Griffin, Yale, and Apopka. The
trenches occur to some degree in each of the larsgr lakes along the
south or01 west hore parallel to the widest expanse of water.
The physical characteristics of bottom deposits in all the Oklawaha
lakes are similar: spot samples of bottom materials throughout the lake
system were almost always unconsolidated jeUy-like muck. However, in
the trenches of Lakes Harris, Eustis, Griffin, and Yale, most spot
samples were fine to coarse sand rather than muck. The bottom
deposits of Lake Apopka were sampled extensively by Schneider and
Little (1969). They report soft, unconsolidated muck over 90 percent
of the lake bottom, consisting of approximately 99 percent water at the
surface, and about 90 percent water at a depth of I meter.
Unconsolidated deposits of muck are at least 40 feet (12 meters ) thick
in some areas of the lake. Where water depths permitted in Lakes
Griffin, Harris. Little Harris, and Eustis, a 14- foot (4.3-mater) rod was
pushed into the muck. Penetration ranged from less than foot (0.3
meter) to more than 7 feet (2 meters).
One explanation for the existence of trenches along the south or
west shores of the largro lakes is that wind-generated currents have
prevented the deposition of sediment in these areas. Winds blowing
across the surface of a body of water create a surface current, which
results in the piing-up of the surface water toward the leeward shore.
The pressure thus exerted on the water immediately underneath the
piled-up water induces a flow there in a direction opposite to that of
the surface current (Ruttner. 1969, p. 50; Reid, 1961, p. 112). In
general, prevailing winds over Florida, other than the southern
peninsula, are from the north in winter (Bradley, 1972).
To show inflow-outflow relations, a water-budget study was made of
lakes Carlton, Beauclair, Dora, Harris, Little Harris, and Eustis taken as
a hydrologic unit. These lakes were chosen for a water budget because
streamflow into and out of the six-lake system is gaged. (See fig. 1.)
The January 11970December 1971 time period was selected because the
discharge record for the Palatlakaha River at structure M-1 begins in
January 1970. The water budget is shown graphically in figure 8.
Storage in the lakes was 28,800 ace-feet (35.6 cubic hectometers) less
on December 31, 1971, than on January 1, 1970. This change in
storage accounts for the difference between total input and total
output. Gaged inflow and known spring discharges, 48 percent of the
total input over the 2-year period, consists of water entering through
Apopka-Beauclair Canal, through structure M-1 on the Palatlakaha
River, and from Bugg, Blue, and Holiday Springs. The input from the
springs was estimated on the basis of discharge measurements.
Estimated rainfall on the 49 square miles (127 square kilometers) of
water surface anea, 35 percent of the total input over the 2-year period,
is the average of rainfall at Clermont, Eustis, and Leesburg. Gaged
outflow, 66 percent of the total output, is the volume of water released
through Haines Creek over the 2 years. Estimated evaporation, 34
percent of the total output, is pan evaporation at the National Oceamc
and Atmospheric Administration Lisbon station for 1970-71 adjusted
for lakes by the factor 0.81 (Kohler, 1954). Algebraically combining
inputs and outputs and the change in storage leaves a residual input of
17 percent derived from ungad runoff, subsurface flow from the
water-table aquifer, and the net exchange of water between the lakes
and the Floridan Aquifer.
The weighted difference between the altitude of the potentiometric
surface of the Floridan Aquifer and the levels of the six lakes shows the
potentiometric surface to hate been 1.92 feet (0.585 meter) higher, on
the average, than the lake levels in May 1971; at this time the
potentiometric surface was at or near its lowest level relative to the lake
surfacesduring the 2-year period. (See fig. 9.) Thus, if the permeability
of the deposits between the lakes and the Floridan Aquifer, exclusive of
the vents at the springs, is uniform, the net exchange of water between
the lakes and the Floridan Aquifer must have been into the lakes. If the
lower limit on net exchange of water is assumed to be zero, then the
entire 17 percent residual was unsgagd runoff and subsurface flow from
the water-table aquifer, fixing the upper limit of these factors at 5.86
inches (149 millimeters) per year. From an analysis based on estimates
of water-table aquifer permeability, average gradient toward the lakes,
and area of subsurface flow to the takes, engaged runoff to the lakes is
appreciably greater than subsurface flow from the water-table aquifer.
Knochenmuos (written ommunication, 1973) suggests that runoff and
s0 surfacee flow from the water-table aquifer in the ungaged are. a0e at
least 2 inches (51 millimeters) per year. If these factors were a
minimum of 2 inches (51 millimeters) per year, or 6 percent of the
total input, then the contribution from the Floridan Aquifer was a
maximum of 11 percent of the total input. On the hypotheses that the
net exchange of water between the lakes and the Floridan Aquifer
cannot be to the aquifer and that engaged runoff and subsurface flow
from the water-table aquifer were at least 2 inches, (51 millimeters) the
most that can be deduced is that runoff and subsurface flow accounts
for 6 to 17 percent of the total input, and that seepage from the
Floridan Aquifer to the lakes accounts for 0 to 11 percent of the total
A water budget for Lake Apopka, to the extent possible with
available data, has been calculated by Anderson (1971). A potential for
seepage from the Floridan Aquifer to the lake exists. The flow from
Apopka (Gourd Neck) Springs min the southwest part of Lake Apopka
was measured to be 28 cubic feet per second (18 million gallons per
day, 0.79 cubic meter per second) in May 1971. It is estimated that
flow from the spring is equivalent to about 30 percent of the average
net outflow from the lake.
The Florida Game and Fresh Water Fish Commission studied 104
Florida lakes and ranked them according to the degree of
eutrophication of each (East Central Florida Regional Planning Council,
1972). Lakes Apopka, Carlton, Beauclair, and Dora ate among the 10
most eutrophic of the 104 lakes studied. Lakes Eustis, Griffin, Harris,
and Yale are ranked 94, 89, 75, and 72 respectively; the higher the
ranuk the greater the degree of eutrophication. Eutrophication of a lake
is the natural process of enrichment with nutrients. The Oklawaha
chain of takes is a prime example of "cultural eutrophication"-that is,
eutrophication greatly accelerated by certain activities of man.
The main cause of cultural eutrophication in the Oklawaha lakes is
muck farming of the reclaimed marsh and wedtands along the north
shore of Lake Apopka (P.R. Edwards, former Director, Lake County
Pollution Control Department, oral communication, 1973). To
maintain optimum water levels while growing crops, water is pumped
from the farm to Lake Apopka and to Apopka-Beauchais Canal when
water is in excess, and allowed to flow by gravity from the lake to the
farms when water is deficient. Water from the farms is rich in nutrients
dissolved from the highly organic muck and from fertilizers. Since Lake
Apopka and Apopka-Beauclair Canal are at the head of the chain of
lakes, nutrient- rich water flows to the down-stream lakes. Smaller
muck farms are adjacent to Lakes Haurs and Griffin.
Other sources of the nutrients that enter the lakes are sewage
treatment plants and industrial plants, primarily citrus processing
plants. Sewage treatment plants for years have discharged waste to
Lakes Yale, Dora, Eustis, Griffin, and Apopka. Sewage waste from
private treatment facilities has also been discharged to the takes. Citrus
promising plants have discharged waste water to Lakes Yale, Griffin,
Harris, and Apopka.
Both the Lake and Orange County Pollution Control Departments
now prohibit the discharge of any type of waste to surface waters.
Several municipal, private, and industrial sources have been granted
temporary permits to continue discharging waste to the lakes until
facilities for other methods of disposal can be completed. The muck
farms also continue to discharge ntrient-laden water to the lakes, but
only under temporary permits. Agricultural interests are developing
plans to control the discharge of waste into surface waters.
No single characteristic can satisfactorily define the trophic state of a
lake. Several physical, chemical, and biological criteria are usually used
to indicate the degree of eutrophication. Eutrophic lakes have high
utrient concentrations of nitrogen and phosphorus, high chlorophyll
levels, high production of plankton and lare plants, low water
transparency, high algal populations distributed among few species, and
are usually shallow (Brazonik and others, 1969). Based on analyses of
water samples by the Lake and Orange County Pollution Control
Departments, the Environmental Engineering Department of the
University of Florida, and the US. Geological Survey, these
characteristics generally describe the Oklawaha chain of lakes. Probably
the worst lakes in terms of water quality ae Carlton, Beauclair, and
Dora, followed closely by Lake Apopka. The quality of Lakes Eustis
and Griffin is somewhat better. Lakes Harris and Little Harris contain
water of considerably better quality than that in Lakes Carlton,
Beauclair, Dora, and Apopka. Lake Yale is the best in the chain because
of relative lack of nutrient sources. The quality of Lakes Eustis and
Griff is better than that of the lakes upstream of Dora Canal because
water of relatively good quality from Lake Harris dilutes the wainer of
poorer quality from Lake Dora. Lakes Harris and Little Harris contain
water of better quality than those upstream of Dora Canal because their
main source of water, the Palatiakaha River, is relatively free of
The process of entrophication is irreversible because the life
processes going on in a lake are such that nutrients are not lost from the
system but re largely recycled. The excessive quantities of algae (angal
blooms) that result from abundant nutrients die, sink to the lake
bottoms, and decompose. As the alpae decompose, they release some of
the nutrients back to the water to be used for continued growth of
algae. Decomposition, which requires oxygen, and the oxygen demands
of the living algae, can reduce dissolved oxygen levels to near zero so
that fish die. The dead fish sink to the bottom where they decay and
contribute more organic matter to the lake bottom. The soft,
unconsolidated bottom deposits of the Oklawaha lakes result from a
gradual build-up of decayed orgnic matter. Loose bottom conditions
make spawning difficult for those gamefish that require a firm bottom
upon which to lay eggs, and also retard the growth of rooted aquatic
plants, which provide shelter for the fish, take up nutrients, and
produce oxygen. Once a lake is overly enriched with nutrients, the
damage cannot be overcome in a short time by eliminating the source
of nutrients. Restoration requires drastic and costly measures.
1971 Hydrologic considerations in dining Lake Apopka-a
preliminary analysoI 1970: U.S. Geol. Suvey open- file
1972 Climates of the states, climate of Florida: National
Oceanic and Atmospheric Administration, Climatography
of the United Statea no. 60-8.
Brezonik, P.0, Morgan, W.., Shannon, E.E., and Putnam, H.).
1969 Eutrophication factors in north central Florida lakes:
Water Resources Research Center, Univ. Florida, Pub. 5,
Bul. series 134.
East Central Florida Regional Planning Council,
1972 Water quality report: Update of water quality section,
First Annual Report of Oklawaha Comprehensive River
Basin Study, 1971.
1954 Lake and pan evaporation in waterlorss investigations:
Lake Hefner studies, technical report, US. Geol. Survey
Prof. Paper 269.
Kohler, MA., Nordenson., FJ. and Baker, D.R,
1959 Evaporation maps for the United States: Technical Paper
No. 37. U.S. Weather Bureau.
1972 Appraisal of the water resources in the East Central
Florida region: Florida Dept. Nat. Resources, Bureau of
Geology Rept. Inv. 61.
Puri, H.S. and Vernon, R.O.
1964 Summary of the geology of Florida and a guidebook to
the classic exposures: Florida Geol. Survey, Spec. Pub. 5
1961 Ecology of inland waters and estuaries New York,
1969 Fundamentals of irmnology: Toronto, Univ. of Toronto
Schneider, R.E. and Little, J.A.
1969 Characterization of bottom sediments and selected
nitrogen and phosphorus sources in Lake Apopka,
Florida: Federal Water Pollution Control Administration.
OUT OF LAE GRIFFIN
382 FT fts(A M1
1959-71 EST AVG
YALE-GRIFFIN LK YALE
-7 EST A 2 c METERS) s
IT/S' 7 BILLION GALLONS|
( \ 2 MILLION
y -\ /a?'^ \C..1 METERS)
,T 8 FEET HAI/NES CREEK
1 79METERS) 32 FTft906M%
208 BILLION GALLONS M A97VG
(787 MIuLLION /
DEAD RIVER AT 620 FEET (189 ETERS)
TO FT.(- .. u
r9-71 EST AVG 260 aLL- GALLONS
6 -54 wI (N o i e u954 MINLLION
S 7 M CUBIC METERS)
S DORA CANAL
s125 IT .- M.)
/ \ \^ ^-^^ 959-71 EST AWG
SLAKES HARRIS LT E HARRIS LAKE 0
AT 620F6 FEET 18 9 METERS) AT 620 FEET M
-4 BILLION BILLION GALLONS(.Es
(247 cue s o7 MILLION CUBIC METERS)L ALLOS
\ \17MLINCUBIC METERS)A FULI
at 62 0 FEET (18 9 TERS >
13 MILLION GALLONS
APOPKA-BEAUCLAIR 14 MILLION CUBIC METERS)
10 FT (SOS M.)v
:NTO L-AKE ARRIS -- ~^
14 F-T (323 M )
1959-71 EST AG/\
\ LAKE APORKA
AT .65 FEET (23 METERS)
S547 BILLION GALLONS
(207 MILLION CUBIC METERS)
P.A1 F FE
LAKE -.RR Fi
o I KILouETER
AVERAGE ALTTUDE, 1959-71 26 FEET 191 METERS)
SURFACE AREA ( HRIADLTLHARRIS AND LTTLE HRS 17.650 ACRES,.
MEAN DEPTH BELOW ALTITUDE 620 FEET (189 METERS) 114
FEET ( 348 METERS I
Figure 2. Volumes and flows in the Oklawaha lakes system.
FLORIDA DEPARTMENT OF NATURAL RESOURCES
BUREAU OF GEOLOGY
This public document was promulgated at a total
cost of $498.00 or a per coy cost of S 33 for [te
purpose of disseminating hydrologic datl.
E ALT -Q-TOS"
m I MILE
AVERAGE ALTITUDE, 1959-71 626 FEET ( 191 METERS)
SURFACE AREA 7806 ACRES, 12.2 SQUARE MILES ( 3160 HECTARES)
MEAN DEPTH BELOW ALTITUDE 620 FEET ( 18.9 METERS ) 1 102
FEET (3 SI METERS)
3I I 3 I 0 I I I I I I 6 6 6 5 7
35 37 39 40 41 42 43 44 45 46 47 48 49 50 S 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 1972
Figure 3. Month-end water levels, rainfall departure from 30-year averages from National Oceanic and Atmospheric
Administration stations at Eustis, Lesbur& and Clermont.
1963 64 65 66 67 68 69 70 71 72 1973
Figrme 9. Perolc wat0 level in Floridl Aqudft wen 844-146.
0 ( MILE
O I KILOMETER
AVERAGE ALTITUDE, 1959-71 665 FEET (20.3 METERS )
SURFACE AREA 30,630 ACRES, 479 SQUARE MILES ( 12,400 HECTARES )
MEAN DEPTH BELOW ALTITUDE 66.5 FEET (203 METERS ). 5.5
FEET (I 7 METERS )
o 3 I 43-49 I I
(CURVE ESTIATD FRO C-oARELATN9
0 10 W W 40 W W 70 W W W
Fige 4. Flow-duration curves for
ApopkaBeauclair Canal for unegulated
peiod 1943-49, related pid
Figme &8 Water budget for Lakes Carton, Beoauelair, Dora, Eu Hart and Litle Hartd,
taken as a unit, for the period 1/1/70-12/31/71.
0,5000 005570 0088000080\/ MAP CiZTIg') U
r( 7 5
ta6- AP kpX\- aTwkaa
5. .-.-.-.-.-.-.-.- -.-.
AVERAGE ALTITUDE, 19i-7: 62,8 FEET (19.1 METERS)
SURFACE AREA 382 ACRES. 6O SHARE MILES (154 HE CTARES)
MEAN DEPTH BELOW ALTITUDE 6 0 FEET (19 METRS) 10.4
FEET ( 317 METERS)
Fsgom 58 Flow-dnm80n su
0fm HlWm Coek feemaompegoltd
Figure 7. Stp-duation curves for Lme
Eastid for unoseulatd period 1943-55,
regulated perWod 1957-70.
I r r
- r r F r-
--vPD EOOI UrY fI-bai-b"r