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UNITED STATES DEPARTMENT OF THE INTERIOR
MA FR1 N-6
FLORIDA DEPARTMENT OF NATURAL RESOURCES
published by BUREAU OF GEOLOGY
GROUND-WATER WITHDRAWALS IN THE UPPER PEACE AND
UPPER ALAFIA RIVER BASINS, FLORIDA
by A.F. Robertson and L.R. Mills
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
An investigation of ground-water withdrawals in the upper Peace
River and upper Alafia River basins was begun in July 1970 as part of a
cooperative agreement with the Southwest Florida Water Management
District. The investigation was prompted by the need to quantitatively
evaluate the cause of the large declines in artesian water levels in the
area which have occurred in recent years. Information gathered as part
of the investigation an presented herewith provide a base for decisions
as to the means to alleviate the situation.
Many direct measurements of pumpage were made during the course
of this investigation. Extrapolations that were necessary were based on
data obtained by direct measurements made during 1970 and 1971.
Numerical values in the text of this report are given in English units.
Water-quality data are reported in metric units only, and other tabular
data and contour values on maps are in English units only. The
following table will aid the reader in converting English units to metric
Multiply English units
square miles (mi2)
million gallons per day (mgd)
gallons per minute (gpm)
B To get metric units
25.4 millimeters (mm)
.3048 meters (m)
2.590 square kilometers (km2)
3.785x10"3 cubic meters (m3)
1233 cubic meters (m3)
1.233x10"3 cubic hectometers (hm3)
cubic decimeters per
.04381 cubic meters per second
.06309 liters per second (Is)
.9072 Tonne (t)
The cooperation of the many grove owners, industrial plant
managers, and municipal water superintendents, who permitted
discharge measurments of their wells and provided information that
made this study possible, is gratefully acknowledged.
The assistance of personnel from many governmental agencies and
other organizations was also useful to this study and a special thanks is
given. These include: County Extension Service, Polk County; Florida
Citrus Experiment Station; Florida Crop and Livestock Reporting
Service; Florida Department of Agriculture, Division of Fruit and
Vegetable Inspection; Florida Phosphate Council and the Southwest
Florida Water Management District. The investigation was made by the
U.S. Geological Survey under the general supervision of C.S. Conover,
district chief for Florida, and under the immediate supervision of J.S.
Rosenshein, chief of the Tampa subdistrict.
DESCRIPTION OF THE AREA
The upper Peace and upper Alafia River basins, as referred to in this
report, are the drainage areas upstream from the U.S. Geological Survey
gaging station on the Peace River at Zolfo Springs, and the station on
the Alafia River at Lithia (fig. 1). The two basins encompass about
1,160 square miles. Flatlands, generally less than 150 feet above mean
sea level, lie between three ridges. The ridges, which trend northwest
reach a maximum elevation of 350 feet. The sandy soils in the area,
especially along the ridges, are well drained and extensively cultivated
One of the most productive phosphate-ore deposits m the world is in
the area of investigation. This ore has been mined extensively (fig. 1)
and is the basis for many industries.
Fourteen cities and towns lie in or adjacent to the basins. The largest
city is Lakeland, which had a population of about 41,500 in 1970.
Three others-Bartow, Plant City and Winter Haven-each had
populations greater than 10,000.
Hundreds of wells in the area are used for a variety of water needs.
However, most of the water is pumped for municipal, irrigation, and
industrial use. The principal source of water is the Floridan aquifer.
This aquifer, which underlies the entire area is highly productive.
Individual wells produce as much as 8,000 gpm (gallons per minute).
The aquifer consists of several thousand feet of limestone and dolomite
overlain by 50 to 100 feet of sand and clay beds. Few wells are deeper
than 1,500 feet and most are about 800 feet deep.
METHODS USED TO DETERMINE
Ground-water withdrawal was determined as follows: (1) reading
meters at most municipal wells; (2) measuring discharge of many
industrial and irrigation wells; (3) determining the relation between
electrical-power consumption and pumpage from pilot wells for
extrapolation of pumpage to wells where only power consumption was
known; and (4) determining the relation between pumpage and tons of
phosphate production, boxes of citrus production, and acres of citrus
irrigated at pilot areas for extrapolation of pumpage to the total area of
Eight of the 14 cities and towns, representing 90 percent of the
water withdrawn for municipal use, had some method of metering their
total water use. The figures given for municipal water-use are
considered to be the most accurate of the three water-use categories
Pump discharges for many industrial and irrigation wells measured by
direct methods were used as a basis for estimating discharges of other
wells by indirect methods. One indirect method involved determining
the relation between discharge rate and power consumption. Records of
power consumption were used to determine the amount of water
withdrawn by pumps driven by electric motors. Owners or plant
managers provided estimates of the total operating time (during
1970-71) of pumps that were not equipped with electric meters.
Another indirect method involved the determination of the quantity
of water used per ton of phosphate mined, per box of citrus processed
and per acre of citrus grove irrigated. These figures, determined at pilot
areas, were used with phosphate and citrus production data and with
citrus acreage data to estimate total industrial water use and total
irrigation water use during 1970-71. This indirect method also was used
to determine annual water use from 1935 to 1970. The figures that
were used were: (1) 2,800 gallons per ton of phosphate mined; (2) 120
gallons per box of citrus processed for concentrate; and (3) 432,000
gallons per year per acre of citrus irrigated. Past investigations also
provided some data (Stewart, 1966; Kaufman, 1967; Pride, 1970; and
Annual ground-water withdrawal from the Floridan Aquifer in the
upper Peace and upper Alafia River basins was slightly more than 120
billion gallons in 1970 and 1971. In 1971, 11.6 billion gallons were
used by municipalities, 76 billion gallons by industries, and 33 billion
gallons by citrus irrigators. The general locations of centers of pumpage
in 1971 are shown on figure 2.
The highest annual water use was 143 billion gallons and occurred in
1968. The decrease in water use between 1968 and 1971 is mainly the
result of decreased withdrawals by industry.
Fourteen municipalities in, or immediately adjacent to, the area used
11.6 billion gallons of water, or about 10 percent of the total pumpage
in the area during 1971. Lakeland, the largest city in the area, used the
most, almost half of the municipal demand. Municipal water use has
increased steadily since 1935 (fig. 3). The increase has been dramatic
for some cities. For instance Lakeland's water use has more than tripled
since 1951 (table 1). Although some municipalities supply water to
industries in the cities, most of the increase in municipal pumpage is
due to increase in population. The population in the area of
investigation was not determined directly, but was determined
indirectly by assuming that the population of Polk County since 1935
(fig. 4) is representative of the growth of the area.
Water use by cities is influenced by rainfall. On the average the
greatest use is during the drier months of April, May, and June when
almost one-third of the annual withdrawals occur (fig. 5) and rainfall is
low (fig. 6).
In 1971, the 76 billion gallons of ground water used by industry
represented 63 percent of the total water used that year in the area of
investigation. Industries include phosphate mining and processing,
citrus processing and packing, ice manufacturing, concrete batch plants,
and laundries. The phosphate and citrus industries are by far the largest
industrial water users.
The increased ground-water withdrawals by industry since 1935 (fig. 3)
reflects the increase of industrial output. For example, the production of
both phosphate and citrus (fig. 4) has grown markedly. However, this
growth has not been steady. Water-use for citrus processing dropped
considerably for several years after 1962 when a severe freeze destroyed
many trees and cut production. Water withdrawals by the phosphate
industry have decreased since 1968 because of increased use of
recirculated water in mining operations.
Industrial withdrawals vary during the year (fig. 5). Withdrawals for
citrus processing were determined monthly and vary considerably due
to the seasonal nature of the citrus crop. Withdrawals for phosphate
mining and processing also vary considerably because of the use of
recirculated water from holding ponds that is replenished by rainfall
during part of the year. These variations are apparent because the area
of greatest water-level recovery in 1971 occurred in the area of
phosphate mining, (fig. 2). However, the data available for withdrawals
by the phosphate industry was only sufficient to determine total annual
withdrawals. Therefore, for the purpose of showing the relative
magnitudes of all water-use categories, pumpage by the phosphate
industry was assumed to be constant.
Water use for irrigation of citrus is the second largest water
requirement in the area onan an nual basis. During 1971, irrigation
pumpage was 33 billion gallons, about 27 percent of the total quantity
of groundwater withdrawn that year. Estimates of the amount of water
used for irrigation from 1935 to 1971 (fig. 3) were based on the total
citrus acreage during those years and adjusted on the basis of annual
precipitation (fig. 7). The percentage of citrus acreage irrigated was
assumed to have increased linearly from 10 percent in 1935 to 75
percent m 1971.
Because irrigation is supplemental to rainfall, withdrawals are high
during dry periods and low or zero during wet periods. Monthly
irrigation during 1970-71 (fig. 5) varied inversely with monthly
precipitation (fig. 6).
The water used to irrigate 14 citrus groves that represent about 20
percent of the total irrigated acreage was monitored in 1970 and 1971.
The water use per acre was determined, and that value was used to
estimate total irrigation pumpage.
EFFECTS OF GROUND-WATER WITHDRAWALS ON
Levels of the potentiometnric surface of the Floridan Aquifer
fluctuate mainly in response to withdrawals from the aquifer. Levels
have declined since about 1948 as ground-water withdrawals increased
(figs. 3 and 8). Levels declined more than 40 feet between 1949 and
1969 in the central part of the area (Stewart and others, 1971).
Between June 1969 and May 1971 water levels declined by as much as
20 feet in part of the area (Robertson, 1973, p. 22).
Seasonal water-level fluctuations are caused by seasonal pumpage
variations (figs. 5 and 9). Levels are generally lowest during the spring
when pumpage is greatest and rainfall is least and highest during the
fall. These seasonal water-level fluctuations are greatest, slightly more
than 20 feet, near the central and southern parts of the area of
investigation (fig. 2).
In 1971, 120 billion gallons of groundwater was withdrawn from the
Floridan Aquifer m the upper Peace and upper Alafia River basins.
Withdrawals increased from 22 billion gallons in 1935 to 143 billion
gallons in 1968. Industries associated with phosphate mining and
production and with citrus processing used about 76 billion gallons in
1971. Withdrawals for irrigation were 33 billion gallons and for
municipal supplies were 11.6 billion gallons in 1971.
The decrease in total water withdrawals since 1968 is caused mainly
by the decrease in industrial withdrawals. Phosphate mining operations,
using more recirculated water from holding ponds, have reduced their
withdrawals from the aquifer for make-up water.
Increased annual withdrawals have resulted in declines of water levels
in the Floridan Aquifer of more than 40 feet since 1949. Seasonal
variations in ground-water withdrawals are reflected in seasonal
water-level fluctuations of as much as 20 feet over the central and
southern parts of the area of investigation.
Healy, H. G.,
1972 Public water supplies of selected municipalities in Florida, 1970:
Florida Bur. Geology, Inf. Cire. 81.
Kaufman, M. I.,
1967 Hydrologic effects of ground-water pumpage in the Peace and
Alafia River basins, Florida, 1934 -65: Florida Div. Geology,
Rept. Inv. 49.
Pride, R. W.,
1970 Estimated water use in Florida, 1965: Florida Bur. Geology,
Map Ser. 36.
Pride, R. W.
1973 Estimated use of water in Florida, 1970: Florida Bur. Geology.
Inf. Cir. 83.
Robertson, A. F.,
1973 Hydrologic conditions in the Lakeland Ridge area of Polk
County, Florida: Florida Bur. Geology, Rept. Inv. 64.
Stewart, H. G., Jr.,
1966 Ground-water resources of Polk County: Florida Div. Geology.
Rept. Inv. 44.
Stewart, J. W.,
1071 (Mills, L. R., Knochenmus, D. D., and Faulkner, G. L.) Poten-
tiometric surface and areas of artesian flow, May 1969, and
change of peotentiometric surface 1964 to 1969, Floridan Aqui-
fer, Southwest Florida Water Management District: U. S. Geol.
Survey, Hydrol. Inv., Atlas HA-440.
S^ '/ \ ^ SUPPLY ^ --_-
Figure 3. Estimated annual ground-water pumpage for public supply, industry and irrigation,
Figure 4. Citrus acreage, phosphate production, citrus production, and Polk County population, 1935-71.
0 5 10 MILES
0 5 10 KILOMETERS
Generalized Area of Phosphate Mining
Generalized Area of Citrus Cultivation
9o Observation Well and Number
A Stream Gaging Station
-- Drainage Basin Boundary
-20- Potentiometric Contour-Shows Elevation of the
Potentiometric Surface of the Floridan Aquifer in
May, 1971. Contour Interval 10 Feet. Datum is Mean
Figure 1. Potentiometric surface of the Floridan Aquifer m May 1971 and areas of phosphate mining and citrus cultivation.
Center of Industrial Pumpage
Center of Irrigation Pumpage
Center of Municipal Pumpage
9s Observation Well and Number
U_ 10 MILES
0o 5 10 KILOMETERS
A Stream Gaging Station
-..- Drainage Basin Boundary
-20- Line of Equal Water-Level Rise in
the Floridan Aquifer from May to
Sept, 1971. Interval 5 feet.
Area of Circle Indicates Annual Ground -
Water Withdrawals, in Billion Gallons
0.3 0.3-1 1-3 3-6 6-10 10-15 15-25
Figure2. Centers of pumpage and risein levelofthepotentiometric surface of theFloridan Aquifer from Mayto September, 1971.
Figure 6. Rainfall in the upper Peace and upper Alafia River basins, 1970-71. Data
from the National Oceanic and Atmospheric Administration
Environmental Data Service.
Table 1. Pumpage in the Upper Peace and Upper Alafia
River Basins, 1951, 1961, 1971.
Pumpage, billion gallons
1951 1961 1971
1.715 3.904 5.442
.700 1.231 1.773
.290 .600 .926
.295 .702 .899
.310 .599 .709
.225 .451 .438
.295 .840 1.195
3.830 8.585 11.648
32.5 54.1 76.0
9.2 28.9 32.7
45.5 91.6 120.3
Figure 5. Monthly ground-water pumpage for public supply, industry, and irrigation,
Figure 7. Rainfall in the upper Peace and upper alafia River basins, 1935-71. Data from the National Oceanic
and Atmospheric Administration Environmental Data Service.
SB .. .._____________________________________ _-
60" 1 '
sO WELL 10 so
60 i i i
Figure 8. Range of water-level fluctuations in selected wells which penetrate the Floridan Aquifer, 1948-71. The
highest and lowest water levels during the year are shown where data are available. Numbered wells are
shown on figures 1 and 2.
> o -
21 F M A M i J A S OIN D J F M A M J J A S O N D
o nIJP'F 'aMIA 'M J'AIS'sTo'N nDIj' F'*T-MA 'M
Figure 9. Range of water-level fluctuations in selected wells
Aquifer, 1970-71. The highest and lowest water lev
where data are available from recorder charts. We)
Numbered wells are shown on figures 1 and 2.
FLORIDA GEOLOGIC SURVEY MAP SERIES
DEPARTMENT OF NATURAL RESOURCES
BUREAU OF GEOLOGY
This public document was promulgated at a total cost
of $625.00 or a per copy cost of $.42 for the purpose
of disseminating hydrologic data.
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