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 Front Cover
 Florida State Board of Conserv...
 Transmittal letter
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 Ground water
 References
 Topography
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FGS






STATE OF FLORIDA
STATE BOARD OF CONSERVATION



FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director






REPORT OF INVESTIGATIONS NO. 25


WATER RESOURCES
COUNTY,


OF HILLSBOROUGH
FLORIDA


By
C. G. Menke, E. W. Meredith, and W. S. Wetterhall

U. S. Geological Survey









Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY,
HILLSBOROUGH COUNTY
and the
CITY OF TAMPA


TALLAHASSEE, FLORIDA
1961




--fucu V




AGRI-
FLORIDA STATE BOARD hiuLTt

OF LIBRAfY

CONSERVATION


FARRIS BRYANT
Governor


TOM ADAMS
Secretary of State




J. EDWIN LARSON
Treasurer



THOMAS D. BAILEY
Superintendent of Public Instruction


RICHARD ERVIN
Attorney General




RAY E. GREEN
Comptroller



DOYLE CONNER
Commissioner of Agriculture


ROBERT O. VERNON
State Geologist and Administrator
Oil and Gas Division






LETTER OF TRANSMITTAL


Jlorida ceoloqical Survey

Ciallakassee

July 6, 1961

Honorable Farris Bryant, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Bryant:

The principal responsibility for preparing water resource data
in Florida rests with the Florida Geological Survey. To the extent
that the development of these data merges with the interests
of the Nation, the U. S. Geological Survey likewise has responsi-
bilities in Florida. The Florida Geological Survey was given funds
to undertake a study in Hillsborough County and this department
has merged its interests with those of the County Commissioners
of Hillsborough County, of the city of Tampa, and of the U. S.
Geological Survey, and we are pleased to publish, as Report of
Investigations No. 25, a comprehensive study of the water resources
of Hillsborough County, which was prepared by C. G. Menke, E.
W. Meredith, and W. S. Wetterhall, of the U. S. Geological Survey.
The details on the water resources have been combined with
general knowledge on the geology and hydrology developed by
the Florida Geological Survey over a period of years and will be
helpful in the future development of the culture of this county.

Respectfully yours,
Robert O. Vernon, Director





















































Completed manuscript received
April 14, 1961
Published by the Florida Geological Survey
E. 0. Painter Printing Company
DeLand, Florida

iv








PREFACE


This report was prepared by the U. S. Geological Survey, Water
Resources Division, under the direction of J. W. Geurin, district
-hemist, Branch of Quality of Water; A. 0. Patterson, district
engineer, Branch of Surface Water, and M. I. Rorabaugh, district
engineer, Branch of Ground Water. Preparation costs were borne
by the U. S. Geological Survey, the Florida Geological Survey, Hills-
borough County, and the city of Tampa. The cost of publication
was borne by the Florida Geological Survey. Funds for the collec-
tion of data were supplied by the U. S. Geological Survey, the
Florida Geological Survey, the Florida State Road Department,
Trustees of the Internal Improvement Fund, Hillsborough County,
and the city of Tampa.





CONTENTS

Pag,
Preface ..... v
Abstract _____
Introduction _____------..----------- ----_------------________ 3
Purpose and scope 3_____ --___ __ _--_3
Acknowledgments ------.______--------- .-------- ..-_---. 4
Previous and present studies ----..-.-- .-------. --- ------------ 4
Sources of additional information ----.---- ------. ---------- --- 7
Methods of investigation --------------_-- 8
Description of area ..__..----------_ ------- ------- 9
' Hydrology of Hillsborough County --------..-------------- --- 12
Rainfall .___- ..--.-..........-...- -._-...____ ~_. ------__ -. -- 12
Evapotranspiration __.-------.---. --.---------- -__---______-- 12
Surface flow _..-- ---_-._--------___-- 14
Underground flow -------------------------------------------_____ 15
Geology _-.....----.---- -. ---- .---------- ___16
Water problems ------------- ------..- --------..-____________._. 17
Surface water -----.------------------.---------------- -- ------------ 19
Use ---- ----- -----------.--------------.---------------------.. ----- 21
Anclote River basin -----------------------------_---.----------- 21
Anclote River -- ----------_21
Brooker Creek basin ------..--------.------------- --. 21
Brooker Creek ---------------- --- --- 21
Keystone Lake __-__.--------...........----- ----. 22
Church and Echo lakes --.. ..-.- __-_ 22
Rocky Creek basin -_--------- -----------------------24
Rocky Creek .----------------------------------------- 24
Brushy Creek ---. .....-------------- ------.----.-------- ---..--. 24
Sweetwater Creek basin --------- ---- ---------25
Sweetwater Creek -___-------------------.__ -- ---- 25
Lake Magdalene -_--------------------26
Bay Lake __-- -------------.- -- ------------ --26
Lake Ellen -----______.__...............------------2___ 26
Carroll Lake __.------------------------------ --- 28
Hillsborough River basin _____------------------_---_-- 28
Hillsborough River _--------------- --_--__--___. 28
Blackwater Creek --------- ----------------36
Flint Creek .-_-_- -----.---------- -- ---- 36
Lake Thonotosassa .....-___~_------.____._______ ---.....---_-- 38
Baker Creek _--------.-------------_----.. 38
Pemberton Creek --- .------_----------- ___- -._-_. 38
Cypress Creek 40
Keene Lake 40
Hanna Lake ____ -___-__ _--_-___-40
Lake Stemper __-_____________41
Sulphur Springs ________________ 41
Blue Sink ___ __ ___44
Drainage Ditch _____44

vi





Lake Hobbs ...--...----....----..----.------.------.----...-------.._ ---- 44
Cooper Lake. --------------------_---- ----------44
Hutchins Lake --------. ---- ------ ___ ----_ 45
Platt Lake _-------- ----- ------------------ 45
Palm River basin ~__----___ ._-- ---45
Palm River------. -- ------------ ----45
Sixmile Creek -- -------_ -------46
,/Alafia River basin _--.. _.. ----.---------- ---------------- 49
Alafia River --_-----.--- _- --------- ------------49
North Prong Alafia River -.--.-- --------------_______. 57
South Prong Alafia River ------ ------- --------------59
Turkey Creek -------- ------- ---------559
Fishhawk Creek ----- -------------------------- 59
Other Streams _---.------ _____.- ---59
Lithia Springs ----------------------------------59
Buckhorn Spring -------_-----------------_---------_--- 60
Bullfrog Creek basin ------------_-------------------60
Bullfrog Creek ------ -- -----------60
Little Bullfrog Creek --- --------------------------62
Little Manatee River basin -----.-- ---_-- ---------62
Little Manatee River- ----- ---------------62
Howard Prairie Branch ---------------------_ ----- 69
Pierce Branch --------.---- ---------69
Carlton Branch ----- --- -------------------------69
South Fork Little Manatee River ------ ------------ -----70
Other streams ...------------------------.-----... ----------. ---------------- 70
Peace River basin __ ------------ ___----- 70
Ground Water --- ------.. ---------------- ---.-- --- 70
Water-table aquifer _-------------- ------- -------- 71
Shallow artesian aquifer ----- ----------------_ --_ 71
Principal artesian aquifer ---- ---_-----_-- __ -72
Recharge to underground formations ------ -- --------_--76
Discharge from underground formations ---- ---__________. 77
Water level ------ ----------- ------ -- ---- 82
Use ---------- ___ --------. -.. 886
Drainage wells -. -------- ------------------ -- --- 8-87
Well exploration studies -- --------------- 88
Quantitative studies -_----- -- ---------------- ---89
Quality ____.____-------. ------__ ---_-- 95
References -------_ .----- ---- ---- ---- ------ ------- ----------- -- 97
Appendix -----.-____... --....----------..- --- .--__- 99
Topographic map coverage of Hillsborough County ------ ------ 99
Location of inventoried wells ------ ----- Facing 100
Topography of Hillsborough County .----.------------- --- 100
Explanation of well numbering system -- -------_ -- 101






ILLUSTRATIONS


Figure Page

1 Periods of record for observation wells, 1956-58 __ 4
2 Periods of record at streamflow gaging stations --------__ -- 5
3 Periods of record at lake stage stations ____ 6
4 Location of Hillsborough County, Florida ___ 10
5 Mean, maximum, and minimum monthly rainfall at Tampa, Florida,
1840-1958. ___________________ 13
6 Geologic cross sections through Hillsborough County, Florida Facing 18
7 Surface-water features, location of gaging stations, and water
sampling sites --___-___-- ---- --- 20
8 Stage of Church and Echo lakes, 1957-59---- -- -- 23
9 Stage-duration curves of some lakes in Hillsborough County 27
10 Flow-duration curve of Hillsborough River near Zephyrhills-- 29
11 Mineral content and water temperature in Hillsborough River at
Hillsborough River State Park ---- .-_-. .----- .--- 30
12 Percent of days specific conductance was equal to or less than a
given value, Hillsborough River at Hillsborough River State Park 31
13 Color in relation to rainfall and flow of the Hillsborough River at
Hillsborough River State Park (September 1956 to October 1957)--. 32
14 Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (September 1956 to
October 1957) -_ ____ ___ -_-.- -.._ ..__~_ -._ 33
15 Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (October 1957 to
October 1958) ------_ -----------___ ---- 34
16 Dissolved materials in relation to flow, Hillsborough River at Hills-
borough River State Park (September 1956 to September 1957) _- 34
17 Chemical character of dissolved materials of Hillsborough River
at Tampa (September 1956 to August 1957) ... _-- .. -----. 35
18 Chemical character of dissolved materials of Hillsborough River
at Tampa (October 1957 to October 1958) ___- 36
19 Mineral content in relation to flow, Flint Creek near Thonotosassa 37
20 Stage of Lake Thonotosassa_____ -_------- 39
21 Relationship of chloride, sulfate, and specific conductance to stage
in Sulphur Springs (800-227-B) 42
22 Dissolved materials of Sulphur Springs in relation to flow and to
stage 43
23 Profiles of streams in the Palm River basin -__- __ 46
24 Dissolved materials in relation to flow, Sixmile Creek at Tampa
(September 1956 to September 1958) --- _48
25 Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (September 1956 to August 1957) 49
26 Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (October 1957 to September 1958) ______ __ 50


viii







27 Profiles of streams in the Alafia River basin 51
28 Flow-duration curve of Alafia River at Lithia _52
29 Mineral content and water temperature in Alafia River at Lithia
(October 1957 to September 1958) 53
30 Percent of days specific conductance was equal to or less than a
given value, Alafia River at Lithia ___ ____ ___ 54
31 Percent of days sulfate concentration was equal to or less than a
given value, Alafia River at Lithia __________................_ 55
32 Percent of days phosphate concentration was equal to or less than
a given value, Alafia River at Lithia ..... _____ ___~_ 55
33 Percent of days fluoride concentration was equal to or less than a
given value, Alafia River at Lithia ___________ 56
34 Percent of days pH was equal to or less than a given value, Alafia
River at Lithia ___..-____ ... _..._-----------_ ------ ----------- 56
35 Chemical character of dissolved materials carried by the Alafia
River at Lithia (September 1956 to October 1957) __57
36 Chemical character of dissolved materials carried by the Alafia
River at Lithia (October 1957 to September 1958) ----- ------- 58
37 Profiles of streams in the Bullfrog Creek basin --__....-----_..... 61
38 Profiles of streams in the Little Manatee River basin ___ 63
39 Flow-duration curve of Little Manatee River near Wimauma .--_--- 64
40 Mineral content and water temperature in Little Manatee River
near Wimauma (October 1956 to September 1957) ____ 65
41 Percent of days specific conductance was equal to or less than a
given value, Little Manatee River near Wimauma -------____ 65
42 Color in relation to rainfall and flow of Little Manatee River near
Wimauma (October 1956 to September 1957) __ 66
43 Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1956 to September 1957) 67
44 Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1957 to October 1958) 68
45 Water levels in selected wells and the precipitation at Tampa and
St. Leo weather stations _____ 77
46 a, b, c, d. Water levels in selected wells ___ 78-81
47 Locations of springs and areas in which water levels in the principal
artesian aquifer were above land surface in September and October
1958 82
48 Piezometric surface in the principal artesian aquifer (September-
October 1958) -----________ 83
49 Piezometric surface in northwestern Hillsborough County (No-
vember 21-23, 1957) _____ 84
50 Well exploration data ------- ----- __ -88
51 Tampa well-field site ___ 91
52 Drawdown in the vicinity of a well after pumping 60 days or more
at 1,000 gpm ________ _94








Table Page
1 Monthly mean evaporation from lakes in Hillsborough County 14
2 Summary of geologic formations from bottom of Oldsmar lime-
stone to the ground surface-- __-____---- Facing 16
3 Information on selected springs in Hillsborough County .-_Facing 82
4 Well construction and test data, Tampa well-field site ..-..---- Facing 92
5 Elevation above mean sea level of formational tops penetrated
by test wells .-__ ------__ _-.------.----.--------._ 92
6 Adjusted values of T, S, and P'/m' for pumping test at the site of
the city of Tampa well field -------- ---------- 93







WATER RESOURCES OF HILLSBOROUGH COUNTY,
FLORIDA
By
C. G. Menke, E. W. Meredith, and W. S. Wetterhall
U. S. Geological Survey

ABSTRACT

Hillsborough County is near the west coast of central Florida
and is comprised of 1,040 square miles of land. The population
was about 400,000 in 1960.
This report is an evaluation of the basic hydrology of the
county and of some of the major factors that affect the available
fresh water supply.
An average of 1,400 mgd (million gallons per day) of fresh
water is potentially available in the county-1,000 mgd of surface
water and 400 mgd of ground water. This is enough to supply
1,250,000 people using 1,100 gpd (gallons per day) per capital, if
all the flood waters could be stored for use.
The fresh water supply is comprised of about 2,500 mgd of
rainfall on the county, of 300 mgd surface-water inflow, and of
100 mgd ground-water inflow to the county. About 1,500 mgd is
returned to the atmosphere by evapotranspiration.
Three rivers, the Hillsborough, Alafia, and Little Manatee
rivers, have an average combined flow of 508 mgd and drain about
70 percent of the county. The average flow of the Hillsborough
River is 173 mgd, of which about 23 mgd is used by the city of
Tampa for its municipal supply. The average flow of the Alafia
River is 220 mgd and of the Little Manatee River is 115 mgd. The
observed minimum flow of the Hillsborough River was 31 mgd,
of the Alafia River was 4.3 mgd, and of the Little Manatee River
was 0.8 mgd. The flow of the Alafia River is used to dispose of
industrial wastes, and the flow of the Little Manatee River is
wasted to the sea.
Water may be obtained from three aquifers. The nonartesian
aquifer, composed of surface sands, yields up to 200 gpm (gallons
per minute) per well. The shallow artesian aquifer, composed of
limestone and sand beds in the Hawthorn formation of Miocene
age, yields up to 500 gpm, and the principle artesian aquifer, com-
posed of limestones of Tertiary age lying below the Hawthorn
formation, yields up to several thousands gpm per well.






FLORIDA GEOLOGICAL SURVEY


The coefficient of transmissibility of the principal artesian
aquifer ranges from about 75,000 to 220,000 gallons per day per
foot, and the coefficient of storage from 0.00005 to 0.002 gallons
per square foot per foot. The coefficient of leakance, in gallons per
day per square foot under a unit gradient divided by the thickness
in feet of the confining beds above and below the aquifer, is 0.002
at the site of the Tampa well field 6 miles west of Plant City.
Most of the 67 mgd of ground water used in the county is
derived from the principal artesian aquifer. Movement in the
aquifer is primarily through the zones of high permeability that
are associated with joints and faults. Locally, these zones behave
as aquifers when they are pumped or recharged at high rates. The
aquifer is recharged through sinkholes and through the sands and
clays that overlie it, and large amounts of water are discharged
from the aquifer to streams in the northern half of the county
and to the bay.
The water level in the nonartesian aquifer is generally within a
few feet of the land surface. Water levels in the shallow artesian
aquifer are erratic really. The piezometric surface of the principal
artesian aquifer is higher than 100 feet in the northeastern part
of the county and generally slopes toward Tampa Bay. Troughs in
the piezometric surface extend inland, indicating that water is
discharged from the aquifer into the Hillsborough and Alafia
rivers.
Dissolved materials of surface waters was generally less than
250 ppm (parts per million) in the county. Notable exceptions
are the Alafia River, with an average dissolved-materials concen-
tration of 292 ppm and a maximum of 658 ppm, and Sulphur
Springs with an average of 500 ppm and a maximum of more than
1,000 ppm. Most of the streams have dissolved materials of less
than 100 ppm but contain colored organic materials leached from
vegetation.
Water in shallow aquifers appears to have less than 100 ppm
dissolved materials in most of the county and may contain organic
color in quantities ordinarily less than those found in streams.
Ground water found between depths of 100 and 200 feet generally
had less than 500 ppm of dissolved materials except in the coastal
areas.
Where the piezometric surface is more than 30 feet above sea
level, ground-water supplies containing less than 500 ppm of dis-
solved materials may be obtained at a depth below sea level not
exceeding 40 times the elevation of the piezometric surface above
sea level. Where the elevation of the piezometric surface is less






REPORT OF INVESTIGATIONS NO. 25


than 30 feet, the concentration of dissolved materials varies
erratically with both depth and location from about 170 to more
than 11,000 ppm. In the Ruskin area, the concentration and char-
acter of dissolved materials changes with the lowering of water
levels.
Variations of rainfall, streamflow, ground-water levels, and
concentrations of dissolved material are given in the report.



INTRODUCTION

PURPOSE AND SCOPE

The purpose of this report is to provide basic information
necessary for optimum development of the water resources of
Hillsborough County and to aid in the solution of some local water
problems.
Quantitative and qualitative aspects of both surface and ground
water are presented in this report. Surface-water interpretations
are based on stage, discharge, and quality data collected in ten
stream basins in the county. Rates of runoff per unit area were
used in estimating flow into the county and into Tampa Bay.
Miscellaneous measurements of stage, discharge, and quality of
water in several lakes, springs, and minor streams supplement
the more intensive data collected at regular gaging sites. Ground-
water information was derived from studies of the geologic forma-
tions, well construction, water level, and pumping-test data.
The several aquifers and the geologic formations comprising
them are described. The water-bearing and water-yielding proper-
ties and the chemical quality of the water from each aquifer are
noted. The fluctuations of water levels in wells are shown, as is
the configuration of the piezometric surface. Hydraulic properties
of the aquifers as determined by analysis of pumping-test data
are given, and a profile of the cone of drawdown near a pumping
well at the proposed site of Tampa's well field is shown and
discussed.
Most of the ground-water and quality-of-water information is
restricted to the period 1956 through 1958 and consequently does
not reflect the wide range of hydrologic conditions known to have
existed in the county.
Both surface-water and ground-water information was used to
estimate a water budget for the county.






FLORIDA GEOLOGICAL SURVEY


ACKNOWLEDGMENTS

The collection of data for this report was substantially aided
by the many citizens and firms who furnished data or services and
who allowed the authors access to wells, streams, and lakes. A
special debt of gratitude is acknowledged to the following well
drillers who contributed data from their files and from their intimate
knowledge of the area: Ben Lovelace and Company, May Artesian
Well Drilling Company, F. A. May and Sons, Morrill Well and
Pump Company, and Mr. Phillip Morrill, retired driller.
Mr. Lyle Dickman furnished data from which use of water for
truck crops was computed.


PREVIOUS AND PRESENT STUDIES

The first documented study of water in Hillsborough County
was made by Matson and Sanford and published in 1913. The


PERIOD OF RECORD
1956 1957 1958
J F(MAMMJ J JASOND J FM|AM J J AS ON)D J|FM AM J J7AS ON D











-
-





I



No record


.


Figure 1. Periods of record for observation wells, 1956-58.


WELL
NUMBER
742-219-1
744-225-39
747-220-1
751-203-1
751 -207-1
752-207-1
752-220-1
756-215-1
756-227-1
757-212-1
757-212-2
757-212-3
757-221-1
758-207-1
759- 229-2
801- 213-22
801- 227-1
801- 227-3
802- 217-1
802-225-2
802- 238-1
803-238-2
804- 207-1
804- 225-1
804-235-1
805-237-1
807-230-3
808-234-2
808-237-5
809-227-1
809-239-1
810-212-1





REPORT OF INVESTIGATIONS NO. 25


report gives information on the source, quality, and development
of ground water, along with lithologic logs and tables of wells and
springs.
A continuing observation well program, to observe ground-water
levels throughout the State, was begun in 1930 and included one
well in Hillsborough County. The water levels in this well and in
two additional wells that were in operation at the beginning of this
project are shown in figure 45. The periods of record for obser-
vation wells are shown in figure 1.
Between 1933 and 1938 streamflow measurement stations were
established on the Alafia, Hillsborough, and Little Manatee rivers.
By 1958, 17 gaging stations were in operation in the county (fig. 2).
The Florida State Board of Health conducted an intensive
chemical and biological study of the Peace and Alafia rivers and
reported the results of the study, along with recommendations, in
two volumes and several supplements (Florida State Board of
Health, 1955).


Figure 2. Periods of record at streamflow gaging stations.





FLORIDA GEOLOGICAL SURVEY


Lake stage observations of 11 lakes were started in 1946
(fig. 3.)
Peek (1959) has described the geology and ground water of
the Ruskin area in southwestern Hillsborough County.
The present study was begun about mid-1956. This report
presents the results of concurrent countywide studies of the fol-
lowing:
(1) Streamflow
(2) Springflow
(3) Lake stage
(4) Geology
(5) Ground water
(6) Chemical quality of streams, lakes, and water
in underground formations


Lake


Bay Lake near Sulphur Springs, Fla.
Lake Carroll near Sulphur Springs, Fla.
Church Lake near Citrus Park, Fla.
Cooper Lake near Lutz. Fla.
-r-o Lake near Citrus Park, Fla.
Lake Ellen near Sulp-ur Springs." Fla.
Ranna lake n-ar lutz. Fla.
Lake H .hhs nar lutz. Fla.
Rutrhl-q la ke near Lutz. Fla.
Keene Lake near Lutz, Fla.
Kenstrne Lake near Odessa. Fla.
Lake Naodalene near Lutz. Fla..
Platt Lake near Lut., Fla.
Lake Steeper near Lutz, Fla.
Lake Thonotoaassa near Tannotneassa, Fla.


Iv // //// // 7
.I I I I I 7-


(^//////////
OiO0?o^^

N!^^^


2^^^^^^^


I I I I


Figure 3. Periods of record at lake stage stations.


"~'"'"'"'






REPORT OF INVESTIGATIONS No. 25


SOURCES OF ADDITIONAL INFORMATION

U. S. Geological Survey and U. S. Weather Bureau publications
may be purchased from the Superintendent of Documents, U. S.
Government Printing Office, Washington 25, D. C. Publications of
the Geological Survey, May 1958, lists all publications of the U. S.
Geological Survey through May 1958. A revised edition is printed
every 5 years and these are supplemented each year. It includes
a list of Water-Supply Papers published as a numbered series.
U. S. Geological Survey Water-Supply Papers containing data
related to streams and wells in Hillsborough County are listed
below:

Year Number Year Number
1913 319 1945 1032
1928 596G 1946 1052, 1072
1933 742 1947 1082, 1097
1934 757 1948 1112, 1127
1935 782 1949 1142, 1157
1936 773C, 802 1950 1172, 1166
1937 822 1951 1192, 1204
1938 852 1952 1222, 1234
1939 872 1953 1266, 1274
1940 892 1954 1322, 1334
1941 922 1955 1384, 1405
1942 952 1956 1434, 1450
1943 972 1957 1504, 1520
1944 1002 1958 1554, 1571

The Water-Supply Papers through No. 1032 are out of print
but are available through certain public and college libraries.
A list of publications of the Florida Geological Survey may be
obtained from the Florida Geological Survey. Reference files of
these publications have been placed in more than 200 high school,
college, university, public, state and federal agency libraries in
Florida. Many early reports are out of print and are available only
through the reference libraries.
District offices of the U. S. Geological Survey are sources of
most current unpublished basic data. Locations and addresses of
district offices in Florida are as follows:

Branch of Surface Water
Mr. A. O. Patterson, District Engineer
244 Federal Bldg. Ocala, Florida
Branch of Quality of Water
Mr. K. A. MacKichen, District Engineer
244 Federal Bldg., Ocala, Florida
Branch of Ground Water
Mr. M. I. Rorabaugh, District Engineer
P. O. Box 110, Tallahassee, Florida






FLORIDA GEOLOGICAL SURVEY


State governmental offices are likewise a source of more current
unpublished information. Mailing addresses:
Florida Geological Survey
Dr. Robert O. Vernon, Director
P. O. Box 631
Tallahassee, Florida
Florida Department of Water Resources
Mr. John W. Wakefield, Director
The Capitol
Tallahassee, Florida
Florida State Board of Health
Mr. David B. Lee, Director Bureau of Sanitary
Engineering
P. O. Box 210
Jacksonville 1, Florida
Topographic map coverage of Hillsborough County is shown
in the appendix. Copies of topographic maps may be purchased
from the Map Information Office, U. S. Geological Survey, Wash-
ington 25, D. C. When ordering, include the title of the topographic
sheet desired, along with latitude and longitude of the lower right-
hand corner.

METHODS OF INVESTIGATION

The selection of sites at which measurements were made or
samples were taken was based primarily on the following factors:
(1) existing data, (2) accessibility of the site (for periodic
measurements or sampling), and (3) simplicity of establishing
relationships between stage, streamflow, and quality.
Records of stage were obtained either by continuous water-
level recorders or by measuring directly with a tape or staff gage.
Both surface-water and ground-water elevations are referenced
to mean sea level, datum of 1929. Streamflow was determined
by current meter measurements.
Water samples were collected and analyzed by standard methods
as detailed in "Methods of Collection and Analysis of Water
Samples," (Rainwater and Thatcher, 1960). Streams were sampled
where measured, if practical. Ground-water samples were col-
lected preferably from wells for which depth, depth of casing,
well log, and elevations of the well and of the water were known.
The results of the analysis of these samples were used to estimate
water quality at other locations.
Dissolved materials, mineral content, and organic materials, as
used in this report, are defined as follows: The term dissolved
materials is the residue on evaporation at 1800 C. The concentra-
tion of dissolved materials includes both organic materials and






REPORT OF INVESTIGATIONS NO. 25


mineral content whenever both types of substances are present.
Mineral content is the concentration of dissolved inorganic earth
materials. The term organic materials is an estimate of the
concentration of dissolved organic materials. The concentration
is calculated by substracting the amount of mineral content from
the amount of dissolved materials. The organic materials are
leached from vegetation and characteristically color natural waters.
Whenever organic materials are essentially absent, the dissolved
materials and mineral content become synonymous.
Data used in the evaluation of ground-water resources were
obtained by direct observation, from the records and memory of
well drillers and owners, and from the files of both the Florida
Geological Survey and the U. S. Geological Survey.
Wells were inventoried in the county to determine the location,
depth of well, depth and diameter of casing, owner, year drilled,
and other miscellaneous physical information. The elevation of
the water surface in the wells was determined with maximum error
of 2 feet. These data were used in mapping the piezometric
surface of the county.
Pump tests were made to determine water-transmitting and
water storing capacities of the principal artesian aquifer and leak-
age of the confining beds.
A current meter was used to determine internal velocity
of water in wells to permit comparison of the permeabilities of
the water-yielding zones of the aquifer.
A drawdown test and the tracing of the progress of dye through
the aquifer were helpful in understanding the hydrology.
Well cuttings were examined to determine the elevation of
formational tops, referred to mean sea level. The geologic sections
were prepared from these data.

DESCRIPTION OF AREA

Hillsborough County is located in the western part of peninsular
Florida about midway down the west coast (fig. 4). The northern
boundary of the county is located near latitude 28010' north, the
eastern boundary near longitude 8204' west. It is bordered on
the western side by Pinellas County, on the northern side by Pasco
County, on the eastern side by Polk County, and on the southern
side by Manatee County.
The county is square except for indentations in the southwestern
part made by Tampa Bay. The bay gives the county an extensive
protected coastline and makes excellent seaport facilities possible.






FLORIDA GEOLOGICAL SURVEY


Figure 4. Location of Hillsborough County, Florida.






REPORT OF INVESTIGATIONS No. 25


'he land area is 1,040 square miles and ranges in elevation from
ea level at the bay to more than 160 feet above sea level at the
Iillsborough-Polk county line southeast of Keysville. There
re many lakes in the northwestern part of the county.
There are three main surface drainage basins in the county:
he Hillsborough, Alafia, and Little Manatee river systems. The
hree main rivers rise near the eastern boundary line of the
countyy and drain toward the bay area.
Numerous springs occur in the northern half of the county.
Hillsborough County is one of the major metropolitan areas in
?lorida and the economy is based on manufacturing, agriculture,
-ecreational activities, and allied trades (Bureau of the Census,
L956). The county occupies less than 2 percent of the land in the
State, yet in 1954 it had about 10 percent of the manufacturing
businessess in the State. During 1954 these businesses employed
early 19,000 people and paid more than $57 million in wages. In
1958 about 98,000 acres of land was used for agricultural purposes,
38,000 for citrus farming, 25,000 for vegetable farming, and
35,000 for pasture (oral communication: Mr. Jean Beam, Hills-
borough County Agricultural Agent).
In 1954 the retail sales in the county totaled more than $320
million. More than 15,000 people employed in this business received
nearly $33 million in wages. About 8,000 people employed in
wholesale trade received more than $28 million in wages. Businesses
providing services employed about 5,000 people who received more
than $12 million in wages.
During the decade 1940-50, Hillsborough County registered a
growth in population of 38.7 percent for a total population of
249,894 in 1950. In the succeeding decade, the county registered
a population growth of 59 percent for a population of 397,788 in
1960. This gave the county a population density of 380 people per
square mile. More than 75 percent of these people live in urban
areas. The greatest concentration of the people is in the city of
Tampa.
Mean monthly temperatures range from about 600 F. to 82 F.
Temperature extremes range from below freezing to about 100
degrees. From 310 to 365 days per year free of killing frost can be
expected in the county.
The area has been affected by 29 hurricanes of varying
intensities since 1900 (Corps of Engineers, 1956). The important
hydrologic effect of these tropical disturbances is the very heavy
rainfall associated with the storms.






FLORIDA GEOLOGICAL SURVEY


HYDROLOGY OF HILLSBOROUGH COUNTY

In the hydrologic cycle, water that falls on the earth evaporates,
runs off the land to the sea, and infiltrates the ground. The water
entering the ground emerges on the surface in lakes, streams,
springs, and the sea or is returned to the atmosphere by evapo-
transpiration. The quantity of water following any of these paths
is dependent mainly on the weather, topography, and geology.
Water dissolves some of those materials with which it is in
contact. The amount of minerals that may be dissolved in the
water depends mainly on the rate of solution, the time of contact,
and the solubility of the materials contacted. Solubility limits
the amount of any materials in solution regardless of time of
contact or rate of solution. Ultimately the mineralized water
finds its way to the sea. Long continued addition of minerals in
this manner has given rise to the highly mineralized water that we
know as sea water.
The divisions of surface water and ground water have been
used for the presentation of the bulk of the material that makes
up this report.

RAINFALL

The average annual rainfall in Hillsborough County is 50.24
inches. This is equivalent to about 21/ bgd (billion gallons
per day). Only a part of this water is available for use.
Rainfall varies with time, but averages based upon 30 or more
years of record remain nearly the same. Mean, maximum, and
minimum monthly rainfall is shown in figure 5, to illustrate the
variation.

EVAPOTRANSPIRATION

The amount of evaporation and transpiration from the land
and water surfaces of Hillsborough County has been estimated
to be 1/ bgd. This is equivalent to a sheet of water 30 inches
thick over the area of Hillsborough County each year. The
figure of 11/ bdg is derived by difference between i flow plus
precipitation and outflow plus water use. --
About 50 inches of water per year evaporates from lakes in
Hillsborough County.-Recordsof evaporation have been collected
since 1952 from a Class A pan located at Bay Lake. An average
of about 61 inches of water evaporates from the pan per year. In







REPORT OF INVESTIGATIONS No. 25


25 -

24

23

22

21

20

19


17

w
0 15
Z
- 14

Z 13

12
z
I0 I



i 9
0
S8
..
CL 7

6

5

4

3

2


0


Figure 5. Mean, maximum, and minimum monthly rainfall at Tampa,
Florida, 1840-1958.


!


RAINFALL IN TAMPA
(/1840-195)






MAXIMUM

.......................................





















MEAN




MINIMUM
/ijiiii~ii~~~ji~~ijiiiil






FLORIDA GEOLOGICAL SURVEY


December, an average of 2.8 inches evaporates. The average rate
increases to 7.5 inches in May and gradually decreases to 5.2 inches
in September.
Evaporation from the shallow pan is generally greater than
that from a lake. Monthly coefficients have been computed from
records collected from 1940-56 at Lake Okeechobee, Florida (table
1). They range from 0.69 for February to 0.91 for July and
August. The computed evaporation from lakes in Hillsborough
County is shown in table 1.
SURFACE FLOW
The streams in Hillsborough County generally flow towards
Tampa Bay. In the northwestern part, Rocky Creek and Sweet-
water Creek flow southward and empty into Old Tampa Bay. In
the northeastern part, the Hillsborough River and Palm River
flow southwestward and into Hillsborough Bay. In the southern
half of the county, the Alafia River and the Little Manatee River
flow westward and into Tampa Bay. Old Tampa Bay and Hills-
borough Bay flow southward into Tampa Bay which, in turn,

TABLE 1. Monthly Mean Evaporation from Lakes in Hillsborough County

Evaporation (inches)
Class A
Month Pan' Pan Coefficient2 Lakes

January 3.17 0.77 2.44
February 3.73 .69 2.57
March 5.23 .73 3.82
April 6.35 .84 5.33
May 7.53 .82 6.17
June 7.10 .85 6.04
July 6.18 .91 5.62
August 5.66 .91 5.15
September 5.24 .85 4.45
October 4.45 .76 3.38
November 3.44 .71 2.44
December 2.77 .83 2.30

Total 49.71

'Monthly mean of record for 1952-58 from U. S. Weather Bureau
evaporation station at Bay Lake near Sulphur Springs, Florida.
!Computed evaporation data for Lake Okeechobee, Florida, Kohler, M.
A., 1954.)






REPORT OF INVESTIGATIONS No. 25


empties into the Gulf of Mexico. The average streamflow into
the bays is slightly more than a billion gallons a day. About 6
percent flows into Old Tampa Bay, 77 percent flows into
Hillsborough Bay, and 17 percent flows directly into Tampa Bay.
Hillsborough County is the source of about two-thirds of this water.
The remaining one-third comes from parts of Hernando, Lake,
Sumter, Pinellas, Pasco, Polk, and Manatee counties.
Runoff is generally high in the southern part of the county,
moderate in the northeastern part, and low in the northwestern
part. Yearly mean values range from 12 inches in the northwest
to 17 inches in the south. An exception is the Palm River basin.
Although this basin is in the central part of the county, its runoff
is high (24 inches). The yearly average runoff for the county is
15.6 inches.

UNDERGROUND FLOW

Generally, the piezometric surface in Hillsborough County
slopes towards Tampa Bay, indicating the general direction of
underground flow. In the northwestern part of the county, ground-
water flow is southward to Old Tampa Bay; in the northeastern
part, the flow is southwestward to Hillsborough Bay; and in the
southern half it is westward to Tampa Bay.
About 100 mgd flows through the ground into Hillsborough
County. This value was derived using the formula Q=TIL, where
Q is the ground-water flow in gallons per day, T is the transmissi-
bility rate in gallons per day per foot, I is the piezometric slope
in feet per foot, and L is the length in feet of the contour crossed.
The values used in the computation were 2.7 x 101 gpd per foot
for the transmissibility rate, 9 x 10-" for the average piezometric
slope, and 3.85 x 10" feet for the length of contour at the county
line.
Springs in Hillsborough County discharge water in quantities
about equal to the ground-water flow into the county. Sulphur,
Eureka, Buckhorn, and Lithia springs discharge 77 mgd, and
other known springs discharge about 20 mgd.
Water probably seeps into the ground at a rate of more than
450 million gallons a day. About 50 mgd of this water emerges in
the bays adjoining Hillsborough County. Another 67 mgd is
pumped from the ground for industrial, farm, public and private
water supplies. The remainder emerges in streams of the county
and flows to the bays. The figure of 450 mgd excludes the ground
water returned to the atmosphere by transpiration.






FLORIDA GEOLOGiCAL SURVEY


GEOLOGY

Hillsborough County is underlain by sedimentary rocks ranging
in thickness from about 8,000 feet in the northeast to about 13,000
feet in the southwest (Applin, 1951). These sediments, which rest
on crystalline rocks, consist of sandstone, anhydrite, and dolomite
of Mesozoic age overlain by limestone, dolomite, clay, and sand of
Cenozoic age.
Only the upper 1,000 feet of the Cenozoic section is used as a
source of water in the county. Only two water wells over 1,000
feet deep were inventoried during the investigation.
The depth of a well is controlled by economy and by depth to
salt water. For economical reasons, a well is finished at the
shallowest depth at which a given yield at a given drawdown is
obtainable. The depth of a well, for most purposes, must also be
limited by the depth to salt water. In the northeastern part of the
county, the depth to salt water is probably more than 4,000 feet
below the surface. The maximum depth of a fresh-water well in
that area would be about 4,000 feet. At this depth the entire
Cenozoic section would have been penetrated.
Table 2 summarizes the geologic formations and their properties
from the bottom of the Oldsmar limestone of Eocene age to the
recently deposited sands and clays at the surface. This section is
believed to include all of the formations that are economically
exploitable as a source of water in the county.
The rocks of Cenozoic age in the county were laid down in
essentially horizontal position. During deposition of sediments,
the land was tilted downward to the southwest. This resulted in
thickening of the beds in that direction. The forces resulting from
differential compaction, along with regional forces associated with
the Ocala uplift and the peninsular arch, warped the beds down-
ward to the southwest. The stresses were relieved by faulting. The
present attitude of the beds is the result of these structural changes.
The available data indicate the existence of many faults, some with
about 200 feet of vertical displacement. Additional data are
necessary to place and limit these faults.
Because the beds thicken and dip to the southwest, wells .of
similar bottom elevation will penetrate older formations in the
northeast than in the southwest. Most of the -deep wells in the
southwestern part of the county produce water principally from
the Tampa and Suwannee limestones, whereas those in the central-
east and northeast parts of the county commonly produce from
the Avon Park limestone.























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TABLE 2. Summary of Geologic Formations from Bottom of Oldsmar Limestone to the Ground Surface


Formation


Undifferentiated


Hawthorn formation


Tampa limestone


Suwannee limestone


Thickness


0-150






0-250


80-400


Character of material


Sand, clay, and marl.


Clay, sand, and limestone. Lime-
stone, near bottom of formation,
is white to gray, soft, sandy, and
porous.

White, cream, and gray, hard
to soft, sandy limestone. Many
molds of pelecypods and gastro-
pods.

White, yellow, and light brown,
soft to hard, dense, fine-grained
limestone with chert lenses to
25 feet thick.


Water supply


Sand yields up to 200 gpm in
some areas and generally 5 to
10 gpm to driven wells less than
40 feet deep. Clay and marl do
not yield usable quantities of
water to wells.


Limestone member yields up to
200 gpm.


Yields up to 1,000 gpm. Supplies
most domestic and commercial
wells in county.


Crystal River formation Yellow-gray and brown soft, al- Rarely used for water supply
(Puri, 1957) most pure limestone. Mostly because of low transmissibility.
Williston formation 90-300 foraminiferal coquinas in pasty
(Puri, 1957) limestone matrix.
Inglis limestone

Soft, chalky, cream to brown Principal source of supply for
Avon Park limestone 200+ limestone containing beds of wells yielding more than 500
foraminiferal coquina and zones gpm. Yield exceeds 5,000 gpm
of brown to dark brown, hard, in some wells.
Lake City limestone 500 crystalline dolomitic limestone.
Locally contains some gypsum.

Fragmental dolomitic limestone Not used for water supplies but
Oldsmar limestone 900 with lenses of chert, thin shale is potential source of fresh water
beds, and some gypsum. in north-central and northeast-
ern part of county.


Cedar Keys limestone


Not
known


Not known


Not used.
known.


Potential use not


Aquifer


Water
table
aquifer


Shallow
artesian
aquifer


Principal
artesian


Water level


Water level generally less than
10 feet. Water table follows
topography in a subdued
manner.


Piezometric surface not de-
fined. Water level is generally
higher than that of nearby
wells in principal artesian
aquifer.


Piezometric surface shown in
figures 48 and 49.


'The Ocala group used here accords to the terminology of the Florida Geological Survey.


Series


Pleistocene
Recent


and


Pliocene


Miocene


Oligocene


Eocene


Paleocene


-------------- I I------------I I I f


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REPORT OF INVESTIGATIONS NO. 25


Geologic cross sections through Hillsborough County are shown
in figure 6.

WATER PROBLEMS

Hillsborough County is now in a period of accelerated popula-
tion and economic growth. Large quantities of water will be
needed for municipal and industrial uses.
The need for land also is increasing with the growing
population. Areas having poor drainage and the flood plain of
streams are being used to fill the need. As more people occupy
and use this type of land, pressure will be placed upon govern-
mental agencies to have drainage and flood-control works
performed.
The per capital use of water in the county is estimated to equal
the national average of 1,100 gallons per day. In 1955, the per
capital use of water in Florida was 900 gallons per day. The county
has many industries which make its per capital use greater than
the average for the State.
It will be necessary to reclaim and re-use water or to import
water when the population of Hillsborough County exceeds the
number of persons that may be supported by the available water.
An average of about 1,400 mgd is potentially available. This is
enough water to supply 1,250,000 persons if all of the flood waters
could be stored for use. At present 400 mgd of this water enters
the county from adjoining counties.
Surface-water problems in Hillsborough County are caused by
the distribution of water. Three relative conditions occur-low
water, medium water, and floods. When flood conditions exist, the
problem becomes one of eliminating excess water that might cause
damage and inconvenience. During medium and low water
periods, the problems may become one of finding suitable water
sufficient to satisfy the needs.
The flooding of the community of Bloomingdale Acres in March
1959 illustrates the problems encountered when flood plains are
used for residential purposes. Bloomingdale Acres was built on
the north bank of the Alafia River during 1957 and 1958. In March
1959, the stage in the river rose to 26.9 feet above the mean sea level
and a large portion of Bloomingdale Acres was flooded. In the
past, similar stages have recurred every 4 to 5 years.
The question of whether a piece of property is subject to
flooding may be determined from lake and stream stage data and
topographic maps.





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FLORIDA GEOLOGICAL SURVEY


Ground-water problems are related to distribution and occur -
rence with respect to quality. Desired quality limits the quantity of
water available for a given use. The elevation of the piezometric
surface and the geology of the area are the principal factors con-
trolling the quality of ground water.
Salt content is the major quality problem in the county. There
are two potential sources of salt water, (1) Tampa Bay and (2)
connate waters. Sea water can enter the aquifer when the water
level in the aquifer is lowered sufficiently. This condition exists
near Gibsonton. Heavy industrial pumping in that area has lowered
the piezometric surface to below sea level in the vicinity of the
channel cut in the bay. This condition also exists along the shore
of the bay west of the Interbay peninsula where the piezometric
surface is near sea level because of natural discharge.
Zonation in an aquifer allows a salty zone to exist in the upper
part of the aquifer near a surface source of salt water at the same
time that lower zones contain fresh water.
In the remainder of the county, as well as in some of the tidal
areas, salt water in wells is derived from a body of salty connate
water that has not been flushed from the aquifer since the area
emerged from the sea. This water underlies the entire county at
depth. In general, the salt water interface occurs at a depth below
sea level of 40 times the elevation of the piezometric surface
above sea level. The 40-to-1 relationship is based on specific
gravities of 1 for fresh water and 1.025 for salt water and assumes
a sharp interface in a static system. Actually the fluctuation of
the piezometric surface, movement of ground water, ocean tides,
and circulation of the salt water in convection-like currents, cause
the interface to be gradational between fresh and salt water, with
a thickness of more than 100 feet in places.
Salt content generally will increase with depth, but the increase
is not uniform. In some areas, the bulk of the aquifer may contain
salty water, but certain zones through which large amounts of
water are moving may be relatively fresh. In other areas, the bulk
of the aquifer may contain fresh water, but a cavity may contain
very salty water. Areas near one of the many faults that may act
as conduits for the upward movement of the connate water are
potentially salty. Thus, with the development of the ground-water
resource and the resultant lowering of the piezometric surface,
the contaminated areas will become more numerous, and the
existing areas of contamination will become more pronounced.
Prevention of problems from this source may require recharge







REPORT OF INVESTIGATIONS NO. 25


of the aquifer by surface water to raise the piezometric surface in
the affected areas.
Future development of ground-water supplies for municipal
or other large users will be controlled by the elevation of the
piezometric surface and by geological conditions that affect quality
of water.
The decline of water levels caused by extensive development of
ground-water supplies may make the placing of well fields
unfeasible in the area where the elevation of the piezometric
surface is less than 50 feet above sea level.
The flanks of the piezometric highs centered in Pasco and
Polk counties present nearly ideal sites for development of future
water supplies. The area of the reentrant (indicated by upstream
bending of the contour lines) in the piezometric surface that fol-
lows the Hillsborough River from near Tampa to the northeastern
part of the county is not favorable for location of well fields. Any
pumpage from wells in that area would only deplete the surface-
water supply presently used by the city of Tampa as a source of
water and would cause rapid contamination of the river and wells
by salt water.
The Industrial Park area in northeast Tampa is unsuitable for
large-scale ground-water development because of existing quality
of water problems. Increased pumping would further contaminate
the aquifer with the salty water that locally makes ground water
in the area unsuitable for most purposes.
When a well is allowed to flow, it diminishes the usable volume
of water that may be withdrawn from the aquifer. At present,
wells flowing to waste are important only in the vicinity of Ruskin,
where quality of water is directly related to local heavy withdrawal,
and in the vicinity of Tampa, where salt water already has spoiled
the water in part of the aquifer as a source of fresh water.
Development of the ground-water resource to its full potential
will necessitate control of waste flow from wells and may warrant
the plugging of springs where feasible.

SURFACE WATER

Eighty-four percent of the water drained from the 1,040 square
miles of land surface in Hillsborough County is carried by 10
streams. The remainder is drained from the land adjacent to
Tampa Bay by numerous small streams, canals, ditches, and
sewers. Some characteristics are discussed for the following
stream basins:







FLORIDA GEOLOGICAL SURVEY


Anclote River basin
Brooker Creek basin
Rocky Creek basin
Sweetwater Creek basin
Hillsborough River basin
Palm River basin
Alafia River basin
Bullfrog Creek basin
Little Manatee River basin
Peace River basin
A map showing the area in Hillsborough County
the streams of these 10 basins is shown in figure 7.











0N \'\\^ X' -


a,


drained by


HILLSBOROUGH COUNTY
FLORIDA


A


Figure 7. Surface-water features, location of gaging stations, and
water sampling sites.







REPORT OF INVESTIGATIONS NO. 25


USE

The majority of surface water uses in Hillsborough County are
nonconsumptive. Most of this water is used in some way for
recreational purposes. Some is used for cooling, washing, shipping,
etc. Water flowing in Pemberton Creek and in the Alafia River is
used to dilute and carry waste materials.
No estimate is made of the quantity of surface water consumed
in the county. The amount of water pumped for irrigation of citrus
groves and truck crops is not known.. The known uses include 3
mgd for industrial processes and 23 mgd for municipal supply.

ANCLOTE RIVER BASIN
ANCLOTE RIVER

The Anclote River drains 113 square miles of land in Pinellas,
Pasco, and Hillsborough counties. However, only about 3 square
miles of the land is in Hillsborough County, along the northern
boundary and is 40 to 60 feet above mean sea level. Water
draining from this area moves northwestward to the Anclote River
through Pasco and Pinellas counties. Osceola Lake, Lake Artillery,
and Lake Hiawatha lie in the Hillsborough County portion of the
river basin. Lake Hiawatha is the largest of these lakes. It has a
surface area of 100 acres, of which 80 percent is in Hillsborough
County and the remainder in Pasco County.

BROKER CREEK BASIN
BROKER CREEK

Brooker Creek drains approximately 42 square miles of land
in Hillsborough, Pasco, and Pinellas counties, of which 28 square
miles is in northwestern Hillsborough County. The remainder
(14 square miles) is in Pasco and Pinellas counties. The creek
heads in the marshy area 2 miles east of the town of Lake Fern
and 4 miles southeast of Odessa. It flows generally in a south-
southwestward direction to Keystone Lake, then northward to
Island Ford Lake, and then southwestward toward Lake Tarpon in
Pinellas County, crossing the county line half a mile south of State
Highway 582. The land is about 60 feet above sea level in the
northeastern part of the basin and 20 feet above sea level at the
county line. There are numerous lakes in the upper part of the
basin. The land in this area is used mainly for growing citrus.






FLORIDA GEOLOGICAL SURVEY


The average discharge (1946-55) of the creek at the outlet of
Keystone Lake was 4.8 mgd (0.48 mgd per sq. mi.). The highest
recorded daily flow of 116 mgd occurred in August 1949. Several
times during the period of record, there was no flow in the creek.
In 1949, there was no flow for 159 consecutive days, and, in 1951,
there was no flow for 94 consecutive days.
During the 8-year period, 1950-58, the flow of Brooker Creek
2 miles upstream from Lake Tarpon averaged 14.5 mgd (0.48 mgd
per sq. mi.), the same rate of runoff per unit area as at the
outlet of Keystone Lake.

KEYSTONE LAKE
Keystone Lake, with a surface area of 580 acres at a stage of
41 feet above mean sea level, is the largest of the two dozen
named lakes and numerous unnamed lakes within the area drained
by Brooker Creek. It is an integral part of the Brooker Creek
channel. During the period, April 1946 to December 1959, the
maximum and minimum stages of the lake were 43.20 (August
1949) and 38.60 feet (June 1949), respectively, in relation to
mean sea level. Stages in this lake closely follow the seasonal
rainfall pattern. The annual variation in stage on the lake is
less than 5 feet. A stoplog dam was constructed at the lake
outlet in October 1955.

CHURCH AND ECHO LAKES
Church and Echo lakes, located 2 miles northwest of Citrus
Park, have a surface area of 70 and 25 acres, respectively, when
the stage is 33 feet above mean sea level. The stage did not drop
below the bottom of the channel connecting the two lakes during
the period of this investigation. Therefore, the two lakes react as
one.
Church and Echo lakes are reported by local residents to be
used as a source of water for the irrigation of surrounding groves.
It would take a pump with a capacity of 360 gpm, running con-
tinuously at full capacity for a period of 30 days, to lower the
stage of these lakes half a foot.
During the 2 years of the stage investigation, Church and Echo
lakes have ranged from 33.92 to 37.28 feet above mean sea level
(fig. 8). When the stage is more than 35 feet above mean sea
level, Church, Echo, Thorpe, and Williams lakes become inter-
connected. This complex of lakes was formerly called Lake
Sullivan. j:
































1957 1958


Figure 8. Stage of Chuich and Echo lakes, 1957-59.






FLORIDA GEOLOGICAL SURVEY


ROCKY CREEK BASIN
ROCKY CREEK

Rocky Creek drains 42 square miles of land in Hillsborough
County and 3 square miles in Pasco County. The creek proper
begins at Turkey Ford Lake and flows southwestward through
Rock Lake, Lake Josephine, Pretty Lake, and Lake Armistead,
then southward into Old Tampa Bay. Land elevations are as high
as 60 feet in the upper part of the creek basin and at sea level near
the mouth. There are numerous lakes in the northern two-thirds
of the basin but very few in the southern part.
The lake area in the northeastern part of the basin contributes
water to Rocky Creek through ill-defined channels leading to Tur-
key Ford Lake. The only measurement of flow from this area was
made at Vernon Road on September 27, 1947. The flow at the
bridge crossing was 40.0 cfs (cubic feet per second). On this same
day the mean daily flow of Brooker Creek at the outlet of Keystone
Lake was 60.0 cfs, 8 times the 9-year average flow for 1946-55.
In 1953, a timber dam was constructed on Rocky Creek about a
100 feet upstream from the east-west tracks of the Seaboard
Air Line Railroad, 4 miles above the mouth. Stage below the dam
fluctuates with the tides of Old Tampa Bay, and, when flow is
sufficient to just submerge the control, tidal fluctuations are
discernible as far as 5 miles above the creek's mouth.
During the 5-year period, 1953-57, the average flow of Rocky
Creek at the control was 20 mgd (0.57 mgd per sq. mi.). Flows
ranged from a minimum of 0.3 mgd (May and June 1955) to a
maximum of 450 mgd (September 1953). The flow fell below 1.5
mgd in 1953, 1955, 1956, and 1957. The longest period, 96 con-
secutive days, was in 1955.
The estimated average flow of Rocky Creek at the mouth is
24 mgd.
The concentration of material dissolved in Rocky Creek on
January 29, 1959, was estimated to be about 50 ppm. About 30
ppm of this total was mineral content and the remaining 20 ppm
was organic material. These estimates are based upon measure-
ments of specific conductance and a color intensity of 110 platinum-
cobalt scale units.

BUSHY CREEK

Bushy Creek, the largest tributary to Rocky Creek, drains 11
square miles of land west of Sulphur Springs. The creek begins ai






REPORT OF INVESTIGATIONS NO. 25


Starvation Lake and flows southwestward, joining Rocky Creek a
quarter of a mile south of Gunn Highway. Its largest tributary
jeads in Lake Le Clare and flows southward joining Brushy Creek
about 11/2 miles above its confluence with Rocky Creek.
The concentration of material dissolved in Brushy Creek on
January 29, 1959, was estimated to be 70 ppm. About 35 ppm
of this total was mineral content and the remaining 35 ppm was
organic material. These estimates are based on measurements of
specific conductance and a color intensity of 130 platinum-cobalt
scale units.

SWEETWATER CREEK BASIN
SWEETWATER CREEK

Sweetwater Creek drains 25 square miles of land in Hills-
borough County. It begins at Lake Magdalene, flows westward to
Bay Lake, then southward to Lake Ellen, and finally, south-
southwestward to Tampa Bay. Stoplog dams are used to regulate
flow into and out of these lakes. The land drained by the creek
ranges in elevation from 55 feet at the northern divide to sea level
at the mouth. This creek basin is now becoming urbanized,
especially around the lakes, with citrus groves and farms being
replaced by housing developments.
During the 7-year period, 1952-58, the average discharge of
Sweetwater Creek was 3.0 mgd at the Gunn Highway. This is
equivalent to only 0.47 mgd per square mile of area drained. Other
local watersheds having little surface storage yield about 0.6 mgd
per square mile. The low yield from Sweetwater Creek watershed
above the Gunn Highway is attributed to the detention of water
in the lakes, which results in an increase in the evaporation and
seepage losses. There was no flow in Sweetwater Creek many
times during the period 1951-58. During the 18-month period
November 1955 to April 1957, the maximum flow was 1.5 mgd and
the average flow was less than 0.1 mgd.
The estimated average flow of Sweetwater Creek at its mouth
is 14 mgd.
During periods of high water, the Hillsborough River basin
is interconnected with the Sweetwater Creek basin between Platt
Lake and Lake Magdalene.
One of the larger tributaries to Sweetwater Creek heads in
White Trout Lake, flows southwestward and joins the creek 1.2
miles north of Hillsborough Avenue (State Highway 580) and 2.3
miles east of Dale Mabry Highway (State Highway 597). It





FLORIDA GEOLOGICAL SURVEY


drains about 4 square miles of land lying west of Tampa and has;
an estimated average flow of 3 mgd.
On January 29, 1959, the concentration of dissolved material
in the South Branch of Sweetwater Creek was estimated to be 110
ppm and in Sweetwater Creek just below South Branch it was
estimated to be 80 ppm. About 55 ppm and 45 ppm, respectively,
of this was mineral content, and the remainder was organic
material. These estimates are based on measurements of specific
conductance and respective color intensities of 220 and 110
platinum-cobalt scale units.

LAKE MAGDALENE

Lake Magdalene, the largest lake in the Sweetwater Creek
basin, has a surface area of 230 acres when the stage is 47 feet
above mean sea level. During the past 12 years, 1947-58, the stage
has fluctuated between 44.5 and 50.8 feet above mean sea level.
Ninety percent of the time the stage was greater than 46.4 feet;
50 percent of the time it was greater than 48.6; and 10 percent of
the time it was greater than 49.5 feet.
Stage-duration curves for Lake Magdalene, Bay Lake, Lake
Ellen, and Carroll Lake are shown in figure 9. The curves for Lake
Magdalene, Bay Lake, and Lake Ellen are plotted on the same grid
with Hobbs Lake, Cooper Lake, and Platt Lake. All of these lakes
are part of the same drainage course during periods when some of
the flow of the drainage ditch of the Hillsborough River basin is
diverted into the Sweetwater Creek basin.

BAY LAKE

Bay Lake, 3.5 miles northwest of Sulphur Springs and 4.4 miles
east of Citrus Park, has a surface area of 38 acres when the stage
is 45 feet above mean sea level. During the past 12 years, 1947-58,
the stage fluctuated between 43.0 and 46.7 feet. Ninety percent
of the time the stage was greater than 43.9 feet; 50 percent of
the time it was greater than 45.1 feet; and 10 percent of the time
it was greater than 45.6 feet (fig. 9).

LAKE ELLEN
Lake Ellen, located 3.8 miles northwest of Sulphur Springs, haE
a surface area of 50 acres when the stage is 39 feet above mear
sea level. During the 10-year period, September 1946 to Augusi
1956, the stage fluctuated between 37.6 feet and 41.8 feet. Ninety












65













St
W

S61,
00


x "





S55
w




D 53
0 5
-J



51



S48







41
WJ 4
C)







47









3 4
40

3

38

37

3t


100 o0 10 TO S0 80 40 30 20 O0 0

PERCENT OF TIME

Figure 9. Stage-duration curves of some lakes in Hillsborough County.


REPORT OF INVESTIGATIONS No. 25


100 90 80 70 o0 50 40 3 0 3 0 0




65


KEENE LAKE (1949-551
63

62
HANNA LAKE (1947-51
61






" `4--ii--





100 90 00 70 O0 50 40 30 0 0

PERCENT OF TIME






FLORIDA GEOLOGICAL SURVEY


percent of the time the stage was greater than 38.9 feet; 5C
percent of the time it was greater than 39.9 feet; and 10 percent
of the time it was greater than 40.6 feet (fig. 9).

CARROLL LAKE

Carroll Lake, located 2.8 miles northwest of Sulphur Springs
in the Sweetwater Creek drainage basin, covers 186 acres when
the stage is 34 feet above mean sea level. During periods of high
stage, water from the lake flows southwestward through a swampy
area and into Sweetwater Creek above Gunn Highway. Lake
stages fluctuated between 32.2 feet and 40.1 feet above mean sea
level during the past 13 years (1947-58). Ninety percent of the
time the stage was greater than 33.9 feet; 50 percent of the time
it was greater than 35.9 feet; and 10 percent of the time it was
greater than 37.4 feet (fig. 9).

HILLSBOROUGH RIVER BASIN
HILLSBOROUGH RIVER

The Hillsborough River drains 690 square miles of land in
Hernando, Pasco, Polk, and Hillsborough counties. During periods
of high water, the Withlacoochee River, which drains parts of
Lake and Sumter counties, overflows into the Hillsborough River
basin near Richland. The river rises in the Green Swamp area of
central peninsular Florida and flows southwestward to Hillsborough
Bay at Tampa.
About 320 square miles of land in Hillsborough County is
drained by the Hillsborough River. Land elevations range from
sea level at the mouth of the river to more than 140 feet at a point
east of Plant City. There are many lakes and springs in the basin.
The greatest concentration of lakes is along the western basin
divide, north of Tampa, and the largest lake, Lake Thonotosassa,
is located between Plant City and Temple Terrace. Citrus groves,
cattle ranches, and truck farms are located in the rural parts of
the river basin. Plant City, Temple Terrace, and part of Tampa
are in the basin.
The flow of the Hillsborough River is gaged at Hillsborough
River State Park where the river drains approximately 220 square
miles. During the 19-year period, 1940-58, the average discharge
of the river there was 173 mgd (0.79 mgd per sq. mi.). The lowest
flow recorded during this period was 31 mgd (June 1945). Flow
in the river is sustained by the discharge of Crystal Springs, which







REPORT OF INVESTIGATIONS NO. 25


empties into the Hillsborough River in Pasco County just above
the Hillsborough-Pasco county line. About 90 percent of the time
the flow is 71 cfs or 46 mgd or more; 50 percent of the time it is
120 cfs or 78 mgd or more; and 10 percent of the time it is 600
cfs or 388 mgd or more (fig. 10). Usually the monthly flow is
highest in late summer or early fall, and the lowest in the fall or
spring seasons.
The total dissolved materials in the river water at Hillsborough
River State Park averaged (time weighted) about 150 ppm from
September 1956 to August 1958 and ranged from 50 to 218 ppm.
The total dissolved materials generally ranged from 52 to 90
percent calcium-plus-magnesium as calcium carbonate, 1 to 31
percent colored organic matter, and 4 to 17 percent sulfate. The
remaining dissolved materials were smaller amounts of various
other minerals. Mineral content for the 1957 water year ranged
from 56 to 201 ppm, as indicated by figure 11.
a
a
W
WlO,10.000

1.1


ouuu I
HILLSBOROUGH RIVER
NEAR ZEPHYRHILLS, FLA.
(1940 TO 1958)

1,000
I,ooo ____ __ _____ ____

500





100___

50




I0 --- ----- --- --- -- --- -- --- --
0 10 20 30 40 50 60 70 80 90 100
PERCENT OF DAYS
Figure 10. Flow-duration curve of Hillsborough River near Zephyrhills.


.1 I I I






FLORIDA GEOLOGICAL SURVEY


--I I I II,
I:K -__-;- ^- -- p -







200 +




OCT NOV. DE. JAN FEB. MAR. APR. MAY JUNE JULY AUG. SEPT.
1956 1957
Figure 11. Mineral content and water temperature in Hillsborough River at
Hillsborough River State Park.

About half the time, the mineral content was 127 ppm or less
during the period September 1956 to September 1957. This value
is based upon specific conductance. Figure 12 shows the percent of
days the specific conductance was equal to or less than a given
value for the period of record stated above.
Figure 12, in combination with the formula given below, can
be used to estimate the mineral content of the Hillsborough River
near Tampa for any desired percentage of time:
Mineral content in ppm= (0.59) x (specific conductance). The
factor, 0.59, is the average of the ratios of mineral content to
specific conductance for composite samples during the period
September 1956 to August 1958.
Dissolved solids and water temperatures of the Hillsborough
River vary with the seasons. Water temperatures ranged from
630 F. in January to 900 F. during August the period 1956 tc
August 1958. The effect of rainfall upon streamflow is usually
accompanied by changes in both the amount and character of dis-
solved materials. Changes in the values for color, for instance,
are shown in figure 13.
For the period September 1956 to October 1957 the streamflow







REPORT OF INVESTIGATIONS NO. 25


1



0
6



S2
_2


330

33 0




270


230

210-I-
170-- -- I-- ----I--- --- --- -- -r^- -- --
__ I---- __- I I Iii


190





170 --i --Sptembar 1956 to
S---- Sptmbar 1957

90_- -- _______
70


0.01 05 I .2 .1 I 2 5 10 20 30 40 50 60 70 80 90 5 03 92 St. 9S. 9 99.9
PERCENT OF DAYS

Figure 12. Percent of days specific conductance was equal to or less than
a given value, Hillsborough River at Hillsborough River State Park.

tended to increase in direct proportion to rainfall, whereas
calcium plus alkalinity as carbonate was nearly always present in
amounts greater than most of the other dissolved materials. A
trend of the chemical character of dissolved materials is indicated
in figure 14. Figure 15 shows a similar trend for the period from
October 1957 to October 1958.
The average concentration of dissolved materials (150 ppm)
appears when streamflow is about 129 mgd, or about 200 cfs
(fig. 16). The figure also shows the range of dissolved materials
for the period in relation to flow.
During the 6-year period, 1934-39, the average flow of the
Hillsborough River at Fowler Avenue was 350 mgd. It ranged
between 30 and 7,600 mgd. At this point, the river drains about
525 square miles of land.
During the 20-year period 1939-58, the average flow of the
Hillsborough River above the Tampa waterworks dam was 380
mgd (0.58 mgd per sq. mi.). The discharge over the dam has
never fallen below 31 mgd. This low rate occurred on June 11-17,
1945. In 1957 the average amount of water withdrawn from the
river by the Tampa water department was 23 mgd. Even during






32 FLORIDA GEOLOGICAL SURVEY


*~.~"7
RAINFALL DURING TIME INTERVAL MONTHLY DEPARTURE FROM
SSHOW AT BOTTOM OF GRAPH NORMAL RAINFALL 6

PLANT CITY STATION SIT P \ I
4











HURINroOMP OtIte PEO t o 19
St 1 \

S, \i / -

ZO \ / -. I
1000i m w 3

S 00 1 2
S -OO-- "








r 956 19 i f
oour to fll d flo the Hisborough River at



Hillsborough River State Park (September 1956 to October 1957).

the 1945 period of extreme low flow, the water spilled over the
dam (wasted to the sea) amount to 135 percent of the 1957 average
withdrawal The greatest flow, 3,800 mgd, was observed at the
40th Street bridge on September 7, 1933, prior to the failure of
the Tampa power dam.
During the flood of September 1933, the Hillsborough River
crested at 26.3 feet above mean sea level at the 40th Street bridge
and at 15.2 feet at Nebraska Avenue. Flow of the magnitude
that caused this extreme in stage recurs at a frequency of about
once every 80 years. The frequency given is based on composite
frequency curves.
At the mouth the average flow of the Hillsborough River
probably exceeds 450 mgd.
The chemical character of dissolved materials in Hillsborough
River water at the Tampa waterworks dam is shown in figures 17
and 18. ,







REPORT OF INVESTIGATIONS No. 25


: 1AL"LJTY AS MAITBRGN IC
CARBONATE 01 MTERIALS
SI--Io01"sB. S DILIC.
MAGNESIUM CHLORIDE
T:i] CALCIU SULFATE

n i 1 L-i-L.I. ..l
CO 0 0
4 O c I z -4
1957


50


1956


Figure 14. Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (September 1956 to
October 1957).

During the period of the record from October 1956 to February
1957 and June to July 1957, rainfall on the county as indicated
by the Plant City station was below normal. Most of the remaining
record, September 1956, March to May 1957, and August to
September 1957, was during a period of above normal rainfall.
The time period used is not representative of a complete range in
rainfall but is considered representative of the range of departure
from normal rainfall.
Color intensity of the Hillsborough River water exceeds the
maximum amount recommended for municipal supplies most of
the time and requires treatment for its removal. This is most
commonly accomplished by adding alum to the water, which causes
the color to "floc" or separate from the solution in solid form. It
then can be allowed to settle out, or it can be filtered. The amount


0
n










FLORIDA GEOLOGICAL SURVEY


2CC -

1tC -

I6C -

140

It





I0 -
Bo -




40 L

20


SSILICA
FLUORIDE. NITRATE

K CHLORIDE
SULFATE

CARBONATE

POTASSIUM
SMAONESIUM

| CALCIUM


z I. -
0


Figure 15. Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (October 1957 to October 1958).


Figure 16. Dissolved materials in relation to flow, Hillsborough River at
Hillsborough River State Park (September 1956 to September 1957).







REPORT OF INVESTIGATIONS NO. 25 35


260 -
SIUCA
240 cF LI
220 SLATE
D ALKALINITY AS
200 CARBONATE
I POTASSUIPUM
180 D MACGNESUM
2 60 -


A 160 -









>0 W X 0X (
i IA l l. 1 -

1956 1957
Figure 17. Chemical character of dissolved materials of Hillsborough River
at Tampa (September 1956 to August 1957).

of iron present in the river is very likely greater than that shown
by analysis, because iron precipitates out of solution during storage
of samples. Iron is removed by aeration and is removed usually
during the process of removing color. No other concentration of
dissolved material was observed to exceed the maximum amount
recommended by the U. S. Public Health Service.
Biological suitability, which is determined by the State Board
of Health, is not included as a part of this report.
Water from the Hillsborough River apparently would be suit-
able for agricultural purposes. The objections noted above for
municipal supplies do not affect the suitability of the water for
agricultural purposes. Boron content is unknown.
Industrial uses vary widely, and water quality requirements
vary almost as widely. Generally, the lesser the amount of
dissolved matter in water, the more suitable the water is for
industrial uses. The main exceptions to this rule are uses in which
the water is not actually used in the process; for example, as
cooling water in which practically the only considerations are
temperature, corrosive properties, and quantity of water available








FLORIDA GEOLOGICAL SURVEY


Me -


280 -

260

240t-

220 L



too L

160



120
t80 r





60

40

20

0


Figure 18. Chemical character of dissolved materials of Hillsborough River
at Tampa (October 1957 to October 1958).


to meet the industrial needs. Water supplies that contain the lower
dissolved solids concentrations are attractive to industries from an
economic standpoint.

BLACKWATER CREEK

Blackwater Creek, one of the major tributaries of the Hills-
borough River, flows into the river about a mile above the
Hillsborough River State Park. During the 7-year period, 1952-58,
the runoff from the 120 square miles of land in the Blackwater
Creek watershed averaged 63 mgd (0.52 mgd per sq. mi.). The
minimum flow was 0.45 mgd in May 1952. At the same time about
3 mgd was being withdrawn from the creek for irrigation purposes.
On only three occasions has flow dropped below 1.5 mgd; the
longest of these lasted 6 days.


FLINT CREEK

Flint Creek drains 71 square miles of land in Hillsborougl
County. The creek proper begins at Lake Thonotosassa and flow,


IL J I_ ... -I-


n (Y
N
= 4'
4 z


O SLICA

SULFITE
ALKALINITY AS
CARBONATE
- SODIUM a
S POTASSIUM
M AGNESIUM

il CALCUM


ON
re
u P
LL 4








REPORT OF INVESTIGATIONS No. 25 37


eastward for half a mile, then northward for a mile, and then
westward for 11/ miles to the river. During the 2-year period,
October 1956 to December 1958, the average flow of Flint Creek
at the outlet of Lake Thonotosassa was 42 mgd (0.70 mgd per
sq. mi.). Zero flow was recorded during 18 days in June 1958.
At the mouth the average flow of Flint Creek probably exceeds
50 mgd.
The average mineral content of the stream was about 74 ppm,
estimated from the discharge-mineral content relationship shown
in figure 19. The observed mineral content ranged from 46 to
92 ppm, and color intensity from 55 to 90 platinum-cobalt scale

zoo
200 -



180



160



140
NOVEMBER 1956
TO
OCTOBER 1957
U. 120



1 00

CALCIUM, MINEpAL
i MAGNESIUM, CONTENT
-j
B 0 AND
ALKALINITY
\ ,AS CARBONATE

so
60__



40 ____








0 ------ --- ------------------ ----------------- ----
0 10 20 30 40 s0 60 70 80 90 100 110
MINERAL CONTENT IN PARTS PER MILLION

Figure 19. Mineral content in relation to flow, Flint Creek near Thonotosassa.






FLORIDA GEOLOGICAL SURVEY


units. Calcium plus magnesium carbonate ranged from 34 to 45
percent of the mineral content.
The estimates are based on four chemical analysis of creek
water during November, December 1956, and May, October 1957,
and on streamflow measurements ranging from 3.9 to 119 mgd or
6.0 to 184 cfs.
LAKE THONTOSASSA
Lake Thonotosassa, with a surface area of about 830 acres,
is the largest lake in Hillsborough County. Stages of the lake
were recorded during the same period (1956-58) that data were
collected on Pemberton and Flint creeks. During this period the
elevation ranged from 34.85 feet to 36.52 feet above mean sea level,
less than 2 feet (fig. 20). The range in stage would have been ip
the order of 6 feet for the same period had not the timber dam
at the lake outlet been in place. This dam helps maintain a
relatively constant stage during periods of low inflow, yet it has
very little effect on stage when high inflow and high outflow exist.
During the period of no flow for Flint Creek in June 1958, the
flow of Pemberton Creek ranged from 1.2 to 5.0 mgd. The record
of this period indicates that the combined seepage and evaporation
losses from Lake Thonotosassa exceeded 4 mgd. Considering the
flow contributed to the lake by Baker Creek, it does not seem
unreasonable to surmise that the losses often exceed 6 mgd.

BAKER CREEK
Baker Creek is the largest tributary to Lake Thonotosassa.
It heads in the Lake Weeks and Lake Hooker area, 12 miles east
of Tampa, and flows northward through improved channels to Lake
Thonotosassa.

PEMBERTON CREEK
Pemberton Creek drains water from the land lying east of
Plant City. From the headwaters, it flows westward to Baker
Creek. The confluence is about a mile above the mouth of Baker
Creek. During the 2-year period, September 1956 to December
1958, the flow of Pemberton Creek was studied at a point 1.8
miles above its mouth. Here the creek drains approximately 24
square miles of land, and the average flow was 17 mgd (0.71
mgd per sq. mi.), The minimum flow was 0.8 mgd (October 1958).
The outflow of the Plant City sewage plant contributes substan-
tially to the flow of the creek during periods of prolonged drought.


















SCTLAKE THONOTOSASSA



















SEPT T NO DE JN FE MAR PR MAY JUNE JULY AUG SEPT OT NOV DEC JAN FE MAR APR MA JUNE JULY AU SEPT OT NOV DEC
SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC


Figure 20. Stage of Lake Thonotosassa.


42


- 40




36
38









32


30






FLORIDA GEOLOGICAL SURVEY


CYPRESS CREEK
Cypress Creek is another of the major tributaries of the
Hillsborough River. It rises in Big Cypress Swamp, 12 miles
north of Tampa. It then flows south-southeastward and joins the
Hillsborough River about 2 miles north of Temple Terrace. During
the period May 1956 to March 1959, the flow of Cypress Creek was
measured periodically at the Skipper Avenue bridge, 5 miles north-
northeast of Sulphur Springs. No flow existed when visits to the
creek were made between May 1956 and March 1957, November
and December 1957, and in June 1958. A large quantity of the
rainwater falling on the land drained through Cypress Creek
goes into storage in the lakes and swamps of the watershed. Some
of the water enters the ground and probably emerges again in
the spring lying in the lower part of the Hillsborough River basin,
or in one of the bays near Tampa.

KEENE LAKE
Keene Lake, with a surface area of about 30 acres, lies west of
Cypress Creek near Lutz. During the 7-year period, 1949-55, the
stage of the lake ranged between 60.90 feet (June 1955) and 63.30
feet above mean sea level (September and October 1953). Ninety
percent of the time the stage was 61.6 feet or more; 50 percent of
the time it was 62.7 feet or more; and 10 per cent of the time it was
62.9 feet or more (fig. 9). The range in stage of the lake is
minimized by the concrete control in the outlet channel at Sunset
Lane. Water discharged from the lake flows southward to Hanna
Lake.
HANNA LAKE

Hanna Lake lies west of Cypress Creek near Lutz. It has a
surface area of about 30 acres. During the 9-year period, 1947-55,
the stage of the lake ranged between 57.72 feet (June 1949) and
62.90 feet above mean sea level (August 1953). Ninety percent
of the time the stage was 59.7 feet or more; 50 percent of the
time it was 61.4 feet or more; and 10 percent of the time it was
61.7 feet or more (fig. 9). Water discharged from the lake flows
south-southeastward to Cypress Creek.
During the period, May 1946 to September 1951 the average
discharge was 1.7 mgd. Frequently, no water was discharged
from the lake. The maximum discharge was 30 mgd in Sep-
tember 1947. Some water from the lake is diverted westward
to Lake Stemper.






REPORT OF INVESTIGATIONS NO. 25


LAKE STEMPER

Lake Stemper lies west of Cypress Creek near Lutz. It has a
surface area of about 130 acres. During the 12 years, 1947-58, the
stage of the lake ranged between 58.68 feet (July 1949) and 61.98
feet above mean sea level (September 1953). Ninety percent of
the time the stage was 59.8 feet or more; 50 percent of the time
it was 61.2 feet or more; and 10 percent of the time it was 61.5
feet or more (fig. 9). Water discharged from the lake flows
southeastward to Cypress Creek.

SULPHUR SPRINGS

Sulphur Springs flows from a circular pool about 50 feet in
diameter over a control structure into an L-shaped run about 500
feet long and into the Hillsborough River. about ll/ miles below
the Tampa waterworks dam. During the period 1917-59,
measurements of discharge from the springs were made at
irregular intervals. The discharge ranged from 8.34 to 71.1 mgd,
and the average of all the measurements is 37 mgd. About one-
third of this water entered the ground in the Blue Sink area.
The time-weighted average concentration of the dissolved
materials in Sulphur Springs water was 660 ppm from September
1956 to October 1958. This average concentration was calculated
from 25 measurements taken at about 6-week intervals during the
period of record and includes measurements made during the
period of stage regulation. The mineral content ranged from 196
to 1,100 ppm.
The average and range in concentration includes concentrations
observed when the pool level was lowered for the test described
later in the Ground Water section. Excluding measurements made
during the period of stage regulation, the average concentration
of dissolved materials was about 540 ppm and the range in
concentration was about 196 to 634 ppm. Concentration of organic
materials usually was low; therefore, mineral content and con-
2entration of dissolved materials were nearly equal.
The concentration of dissolved materials fluctuates with the
3tage and discharge of the springs. This is indicated by figures
21 and 22. The wide range in concentration observed, and the
aven greater range that is indicated as being possible, suggests
hydraulic connection with aquifers lying at depths greater than
any aquifers that have been penetrated so far by wells in this
area.


















d
w -J


i -




10
10
,700 21600
U

S600 s 140'd







_oo 0 so
1 u



00 ,oo 0 -
S a. I,


1957


l'igure 21. Relationship of chloride, sulfate and specific conductance to stage
in Sulphur Springs (800-227-B).




















ELEVATION OP WATER SURFACE IN RELATION
TO DISSOLVED MATERIALS
-,


TREND OF DISSOLVED MATERIALS IN RELATION TO FLOW

I


0
%o o


,-, 0 0
0



0


I I I I I


200 300 400 O50 600 700
DISSOLVED MATERIALS IN PPM


0


- 0


-


I i i i I I I


B00 900 1000 1100


Figure 22. Dissolved materials of Sulphur Springs in relation to flow and
to stage.


60
100







4o 0

O M


I I I I I I I I I I I I


I I






FLORIDA GEOLOGICAL SURVEY


The particular significance of this interpretation is with respect
to consideration of Sulphur Springs for use as a water supply. If
natural conditions are allowed to prevail, the water quality of
Sulphur Springs probably would fluctuate near the range observed.
If the stage of the spring is lowered to increase the yield from
Sulphur Springs, water quality can be expected to deteriorate
rapidly, and it is likely that the springs would yield water of
unsuitable quality.
BLUE SINK
The Blue Sink area drains approximately 26 square miles of
land in Hillsborough and Pasco counties. It is located in the
northern section of the city of Tampa west of Florida Avenue and
south of Fowler Avenue. The sink area is perforated with sink-
holes and has no surface drainage. Large quantities of surface
water flow into the sinks from a drainage ditch carrying water
from land lying north of Sulphur Springs. The average flow into
these sinks probably exceeds 9 mgd.
DRAINAGE DITCH
A drainage ditch carries water from an area of many lakes
situated north of Sulphur Springs to the Blue Sink area. During
the period, July 1946 to September 1956, the discharge of the
drainage ditch at Bearss Avenue was 4.4 mgd (0.37 mgd per sq.
mi.). The longest of the many periods of no flow lasted 7 months-
March to September 1956. In 1947, the discharge was as high as
69 mgd.
LAKE HOBBS
Lake Hobbs, which is located about half a mile northwest of
Lutz, has a surface area of approximately 65 acres. During the
12-year period, 1947-58, the stage of the lake ranged between
63.36 feet (May 1956) and 68.10 feet above mean sea level (Sep-
tember 1953). Ninety percent of the time the stage was 64.2
feet or more; 50 percent of the time it was 65.9 feet or more;
and 10 percent of the time it was 67.0 or more above mean sea
level (fig. 9). Water discharged from the lake flows southward
through a ditch to Cooper Lake.

COOPER LAKE
Cooper Lake is half a mile south of Lake Hobbs. It has a
surface area of about 85 acres. During the 10-year period, Sep-
tember 1946 to August 1956, the stage of the lake ranged between






REPORT OF INVESTIGATIONS No. 25


58.78 feet (June 1949) and 62.54 feet above mean sea level (Sep-
;ember 1947). Ninety percent of the time the stage was 60.1
feet or more; 50 percent of the time it was 61.1 feet or more; and
10 percent of the time it was 61.7 feet or more above mean sea
level (fig. 9). Water discharged from the lake flows southward
through several lakes into Hutchins Lake.

HUTCHINS LAKE

Hutchins Lake lies 2 miles southwest of Lutz. It has a surface
area of about 20 acres. During the period, April 1946 to Septem-
ber 1952, the range in stage was greater than 2.7 feet. The
average discharge from the lake was 0.97 mgd (0.36 mgd per sq.
mi.). There was no discharge from the lake many times during
the period. The maximum discharge was 18 mgd in August 1947.

PLATT LAKE

Platt Lake is about 5 miles north of Sulphur Springs. It has
a surface area of about 65 acres when the stage is 49 feet above
mean sea level. Water from the lake flows through ditches to the
Blue Sink area., During the 10-year period, September 1946
to August 1956, the stage of the lake ranged between 46.92 feet
(June 1949) and 51.38 feet above mean sea level (September
1950). Ninty percent of the time it was 47.6 feet or more; 50
percent of the time it was 48.9 feet or more; and 10 percent of
the time it was 50 feet or more above mean sea level (fig 9).

PALM RIVER BASIN
PALM RIVER

Palm River drains 40 square miles of land in Hillsborough
County. It flows southwestward and empties into McKay Bay at
Tampa. The river proper is a continuation of Sixmile Creek and
is only about 2 miles in length. Land elevation in the basin ranges
from 135 feet on Kennedy Hill, northeast of Tampa, to sea level
at the river's mouth. Due south of Temple Terrace, there is a
valley in the ridge dividing the Hillsborough and Palm River
basins, through which water flowed into the Palm River basin
during the 1933 flood. Stage of the river fluctuates with the tide
in McKay Bay. The average net flow at the river's mouth probably
exceeds 45 mgd.






FLORIDA GEOLOGICAL SURVEY


SIXMILE CREEK

Sixmile Creek, the largest tributary to Palm River, rises in
a low flat prairie and flows 7 miles in a southerly direction to join
Palm River. In the upper reaches, the channel has been improved.
During periods of heavy rainfall, the creek overflows its banks
and inundates the prairie. In the upper portion of the basin the
gradient of the channel is 2.9 feet per mile (0.05 percent). Below
U. S. Highway 92, the gradient increases sharply to 8.8 feet.per
mile (0.17 percent) (fig. 23).
Much of the dry-season flow of Sixmile Creek comes from
springs in the upper reaches.
A study of the flow characteristics of Sixmile Creek was started
in 1956. During the 3 years of study, flow of the creek at the
State Highway 574 crossing (Broadway Avenue) did not fall
below 9 mgd.
Two tributaries join Sixmile Creek above State Highway 574
and give the stream pattern a fan-like appearance. The western-
most tributary drains an area of fairly flat, swampy land north of
Orient Park. It rises at Bellows Lake and flows southeastward
to join Sixmile Creek between Buffalo Avenue and State Highway
574. The channel is shallow and has an average slope of 16 feet
per mile (0.3 percent). The easternmost tributary drains an area


40

-J
au



o
0


SNote: Data token from
DISTANCE ABOVES.G.S. Topographic
6 Mops. zO


w

4 5 6 7 8 9
DISTANCE ABOVE MOUTH (MILES)


Figure 23. Profiles of streams in the Palm River basin.






REPORT OF INVESTIGATIONS NO. 25


of pasture and grove land. It heads in the boggy areas around
Mango Lake and flows westward to enter Sixmile Creek about
one-tenth of a mile below the Buffalo Avenue crossing. The channel
is shallow. It has a gradient of 8.1 feet per mile (0.15 percent).
On April 25, 1958, the flow of tributaries to Sixmile Creek was
measured to determine how much each contributed to the base
flow of Sixmile Creek. Also, the quantity of ground-water pickup
between measuring sites was determined. Six measurements of
flow were made above the regular gaging station on Sixmile Creek
and one was made at the station. These measurements are listed
as follows:
Location of Discharge
Stream Tributary to: Measuring Site (cfs)
(Western branch) Sixmile Creek % mile west of U. S. 2.0
Hwy. 301 at Buffalo Ave.
Sixmile Creek Palm River At the U. S. Hwy. 92 40.1
bridge
Sixmile Creek At U. S. Hwy. 301, % mile 0
south of U. S. Hwy. 92
(Eastern branch) Sixmile Creek At Faulkenburg Rd., mile 1.9
north of State Hwy. 574
(Eastern branch) At Buffalo Ave., 2 0.1
miles west of Mango
(Eastern branch) At State Hwy. 574, mile 0.1
east of U. S. Hwy. 301
Sixmile Creek Palm River At State Hwy. 574 51.0
(Broadway)
Sixmile Creek above U. S. Highway 92 contributes most of the
water (79 percent) found in the creek at State Highway 574
during periods of base flow. The western tributary to Sixmile
Creek carries 4 percent at Buffalo Avenue and the eastern branch
contributes another 4 percent at Faulkenburg Road. There is
six miles of stream channel between the three measuring points
mentioned above and the gaging station at State Highway 574.
A total of 6.8 cfs of flow was picked up by this reach of channel
for an average ground-water inflow of 0.7 mgd per mile of channel.
The dissolved materials in Sixmile Creek averaged (time
weighted) 228 ppm and ranged from 112 to 342 ppm from
September 1956 to September 1958. Figures are based on 17
water samples taken at about 6-week intervals during the period
.of measurement. Calcium plus magnesium carbonate ranged
from 47 to 64 percent of the mineral content; sulfate was about 22
to 35 percent. Color intensity ranged from 5 to 180 platinum-
cobalt scale units.






FLORIDA GEOLOGICAL SURVEY


The relation of dissolved materials to flow of the stream is
shown in figure 24.
Changes in streamflow usually are accompanied by changes in
both the amount and character of dissolved materials. Changes in
the amount and character of dissolved materials are indicated in
figures 25 and 26.

Springs: There are many springs in the headwaters of Sixmile
Creek. Only the springs known as Eureka Springs have been
measured. These springs are located 0.7 mile north of U. S. High-
way 92 and 0.8 mile east of U. S. Highway 301. The flow was 2.5
mgd on May 1, 1946, and 0.7 mgd on May 1, 1956.
The mineral content of Eureka Springs water was 213 ppm, as
shown by combined samples taken on May 1, 1956, and on July
31, 1958. There was no significant difference in the mineral content



220


6SO


40 1-


t0 0 -


o I I I I I i I I I I .I I It
100 120 140 160 180 200 22.0 240 260 280 300 320 340 360 380
DISSOLVED MATERIALS IN PPM

Figure 24. Dissolved materials in relation to flow, Sixmile Creek at Tampa
(September 1956 to September 1958).


o80-


200

180







REPORT OF INVESTIGATIONS No. 25


-, 40
-)
J <1


1957


Figure 25. Chemical character of dissolved materials carried
at Tampa (September 1956 to August 1957).


by Sixmile Creek


on these 2 days. Calcium plus magnesium carbonate was about
68 percent and sulfate was about 20 percent of the mineral
content.
Color intensity was 20 on May 1, 1956, and 4 on July 31, 1958
(platinum-cobalt scale units).

ALAFIA RIVER BASIN

ALAFIA RIVER

The Alafia River drains 410 square miles of land in Polk and
Hillsborough counties. Two hundred and forty-five square miles
of this land is in Hillsborough County. The river begins at the
confluence of the North, and South Prongs, about 4 miles east of
the town of Lithia, flows westward, and empties into Tampa Bay
near Riverview (fig. 7). Land elevations in the basin range from
sea level near the mouth to 250 feet above mean sea level in the


S1956
L956







FLORIDA GEOLOGICAL SURVEY


o z S
1957


1958


Figure 26. Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (October 1957 to September 1958).



eastern part. There are few natural lakes in the basin; however,
open-pit phosphate mining operations have created many artificial
ones. Soils in the basin are sandy, and the land is used principally
for raising cattle and citrus. The population density is low.
Throughout most of its length the Alafia River flows through
a shallow, wooded valley and in a well defined channel. Several
large tributaries, many small ones, and many springs flow into it.
The lower reach of the river rises and falls with tides in Tampa
Bay and, when the flow of the river is low, tidal fluctuations are
discernible as far as 10 miles upstream from the mouth. Channel
gradients are shown in figure 27.
At Lithia, the average flow of the Alafia River is about 220
mgd. The maximum flow was about 12 bgd on September 7, 1933,
and the minimum was about 41/. mgd on June 6, 1945. Fifty
percent of the time the flow is 160 cfs or 103 mgd or more (fig.
28). Usually, the average monthly flow is highest in September and
lowest in May.


440o-
400-

a 320

280 L

SZOO
200L


SILICA
FLUOROE, NITRATE
A PHOSPHATE
s CHLORIDE
SULFATE
A LKALINITY" AS
CARBONATE

POTASGNESIUM
El CEALCII.R






REPORT OF INVESTIGATIONS NO. 25


15 20 25
110

100
90 90
80 80

70 70
AG w
60 60 '

50

S40
0 oNote Data taken from
S U. S. G.S. Topographic 302
I/

1 0 --O p-. __Maps._




0 -- 10
0
15 20 25 30 35 40 45
DISTANCE ABOVE MOUTH (MILES)
Figure 27. Profiles of streams in the Alafia River basin.

On September 7, 1933, the stage of the Alafia River at Lithia
was 35.5 feet above mean sea level. Flow of the magnitude that
caused this extreme in stage recurs at a frequency of about once
every 80 years. The frequency given is based on composite fre-
quency curves.
At the mouth, the average flow of the Alafia River probably
exceeds 300 mgd.
The average concentration of dissolved materials (time
weighted) in the Alafia River at Lithia was 292 ppm from October
1957 to September 1958. Dissolved materials ranged from 116 to
658 ppm during the same period. Dissolved, materials were about
87 to 100 percent mineral content. Constituents reach high
concentrations and vary considerably; for instance, sulfate con-
centration ranged from 33 to 222 ppm; phosphate, from 9 to 170
ppm; calcium, from 18 to 117 ppm; and silica, from 15 to 77 ppm;
alkalinity as carbonate was essentially absent. Color intensity
ranged from about 15 to 150 (platinum-cobalt scale units).
Industrial waste, materials discharged into the stream mask







FLORIDA GEOLOGICAL SURVEY


10,000 -_ z


S5ip





S1


S5





1


0 10 20 30 40 50 60 70 80
PERCENT OF DAYS
Figure 28. Flow-duration curve of Alafia River at Lithia.


90 100


the presence of naturally occurring concentrations of dissolved
materials. The preceding estimates of dissolved materials in Alafia
River water near Lithia are not representative of upstream
locations on the Alafia River or its tributaries.
High but variable concentrations of wastes at different locations
upstream from Lithia were indicated by specific conductance, by
color intensity, and by fluoride content of water samples taken
from the Alafia River near Lithia; the South Prong Alafia River
2.5 miles east of Pinecrest; the Alafia River 2.5 miles southeast
of Bloomingdale; the North Prong Alafia River 0.5 mile north of


oo
ALAFIA RIVER
AT LITHIA, FLA.
(1934 TO 1958)


00


00

00





50
2oo 30 40- -0-6- -- --0









10


I







REPORT OF INVESTIGATIONS NO. 25


Keysville; and Fishhawk Creek 1 mile east of Boyette. These
samples were collected during the period January 27-29, 1959.
(See separate data report.)
Mineral content of the Alafia River at Lithia for the period
October 1957 to September 1958 is indicated in figure 29. About
50 percent of the time the specific conductance was equal to or
less than 340 micromhos. The mineral content, in parts per million,
was about 77 percent of the specific conductance in micromhos;
therefore, half the time the mineral content from October 1957
to September 1958 was equal to or less than 262 ppm. Figure 30
shows the percent of days that the specific conductance was equal
to or less than a given value for the 1-year period ending September
1958.
Figure 30 can be used to estimate the mineral content for any
desired percentage of time during the period of record according
to the following relationship:


90 -
90
so ---- -- -- -- -- ---7 ^*^ /'A ^-


50 0-

40
60 I


600

550
500








50VJ M



100

50 OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT


Figure 29. Mineral content and water temperature in Alafia River at Lithia
(October 1957 to September 1958).


o






54 FLORIDA GEOLOGICAL SURVEY





i i I /_-

A
g o o -. .- f. .-


3400 I^-- ^-
a 0 0
400

300 October 1956 to
September 1957


0.01 .05 I 5 I 2 5 o 1 0 30 40 50 070 o0 90 95 g 99 99.5 99.9 99.9
PERCENT OF DAYS

Figure 30. Percent of days specific conductance was equal to or less than a
given value, Alafia River at Lithia.

Mineral content in ppm= (0.77) x (specific conductance).
The factor, 0.77, is the average of the ratios of mineral content to
specific conductance for composite samples during the period of
record.
Figures 31, 32, 33, and 34 show the percent of days that sulfate,
phosphate, fluoride, and pH values, respectively, were equal to or
less than a given value.
The chemical character of the dissolved materials is shown in
figures 35 and 36. The water temperatures in the stream varied
from 450F. in February to 850F. in June (fig. 29).
According to U. S. Public Health standards, the water quality
of the Alafia River was unsuitable for municipal uses during the
period October 1, 1957 to September 30, 1958. Color intensity
exceeded that desired most of the time. Fluoride concentrations
exceeded the recommended maximum all the time, with concentra-
tions in the stream reaching 17 ppm. Phosphate concentrations
were observed up to 170 ppm. Fluoride, phosphate, and other
materials enter the stream at various locations as industrial waste
products. Water from the Alafia River would be difficult to treat
economically for municipal use.
Biological suitability for use as municipal supplies is not
included as a part of this report.
Regular use of Alafia River water for stock watering would








REPORT OF INVESTIGATIONS No. 25


0.01 .05 .1


.2 .5 1 2


5 to 20 30 40 50 40 70 80 90 95 98 99 9
PERCENT OF DAYS


Figure 31. Percent of days sulfate concentration was equal to or less than
a given value, Alafia River at Lithia.






lt0 -- -- -- ---- --- --- -- -- ----^ --




2 13---------------------------------------^----
too -----------------------
10


150
150


130
120


1 0


90
so
So_ _ __ ____





0 50- --

tOcob1r 195 to


1(01 --- 1 -- -- -- L-- --- I I- I- --I -- -- -I- -- -- -- -- --
0.01 .05 .1 .2 .5 I 2 5 10 20 30 40 0o 60 70 80 90 95 98 99 99.5 9.9 99.99
PERCENT OF DAYS

Figure 32. Percent of days phosphate concentration was equal to or less than
a given value, Alafia River at Lithia.


flo
o190 V- -00


170


150


30 -------------- --
9O------1- --- --/-~- -


110


90


TO
October 1957 to
September 1959



30__-------


--







FLORIDA GEOLOGICAL SURVEY


.5 2 3 10t 20 3 0 40 SO 60 70
PERCENT OF DAYS


80 90 95 9S 99 99.5 99.9 9.99


Figure 33. Percent of days fluoride concentration was equal to or less than
a given value, Alafia River at Lithia.


result in mottled teeth and other pathological changes in the

animals because of the fluoride content (California State Water

Pollution Control Board, 1952, p. 256). Continued use would result

in increasing economic loss to livestock producers along the river.

Extensive use of Alafia River waters for irrigation could result


9.8 1 1 1 1 1 1 1 1 1 --







..4 -- __
9.3
S,.4 -- -0



&. _-- _I
if6.r /-,



S9--------------------- -



5o September 19 to


I 991 99.5 99.9 99.9s


Figure 34. Percent of days pH was equal to or less than a given value, Alafia i
River at Lithia.


2
o
s






.J
3

a
Ui
&


j

Z
bi


October 1957 to
I I I







J ----
0 -- --- -- -- -- -- -- -- --- -- ---


0.0 .05 .1 .2


0.01 .05 .1 2 .5 I 3 10 20 30 40 50 10 70 10 90 95
PERCENT OF DAYS







REPORT OF INVESTIGATIONS NO. 25


Q sucA
FL.UORIDr. MTBAME
8 PHOSPHATE

50 SULFATE
550 ALALIiTYAS
500 PD T.
450 MAGNESIUM
a 450 Lxl
CALCIUM
5 400
350
r 300

250

200







0 z 0 o
1956 1957


Figure 35. Chemical' character of dissolved materials carried by the Alafia
River at Lithia (September 1956 to October 1957).


in contamination of ground-water supplies hydraulically connected
downgradient from the irrigated land. Shallow ground water is
used for domestic supplies within the basin and would be vulnerable
to contamination by fluoride and phosphate.
The Alafia River water was the least suitable of all river water
in Hillsborough County for most uses because of the range in
concentration of the dissolved materials.


NORTH PRONG ALAFIA RIVER


The North Prong Alafia River drains about 175 square miles
of land southeast of Plant City. Fifty square miles of the basin
area is in Hillsborough County, and the remainder lies in Polk
County. Stream channels in the area run mostly through wide
marshy or swampy areas and are not well defined. There are
several springs in the basin.
The average flow of the North Prong is about 110 mgd.









FLORIDA GEOLOGICAL SURVEY


E SILICA

F rHOSPHtATE

F NIT.LTE


JLFATE
SALKLINITY -S
CANDCNATE
L S"IM a

POTASSIUM
SA -NESIUM

-I CALCIUM


I i


!75

F- MJ
->EO"


25


PER MILIO
PER MILLION


n
n n N
O (D
W 4 W
D LL


19ST 1958


Figure 36. Chemical character of dissolved materials carried by the Alafia

River at Lithia (October 1957 to September 1958).


t I


P
OR r?
Z -I
5 ~






REPORT OF INVESTIGATIONS NO. 25


SOUTH PRONG ALAFIA RIVER

The South Prong Alafia River drains about 120 square miles
of land, 70 square miles of which is in Hillsborough County. The
South Prong begins near Hookers Prairie (Polk County), flows
westward for 20 miles, northward for 14 miles, and joins the North
Prong. Average flow at the junction is probably 100 mgd.

TURKEY CREEK

Turkey Creek drains 40 square miles of land in the area south-
east of Plant City. It flows into the Alafia River 2 miles upstream
from Lithia Springs. There are numerous phosphate pits in the
basin. Average flow is about 25 mgd.

FISHHAWK CREEK

Fishhawk Creek drains avout 30 square miles of land lying
south of Lithia Springs. It flows northward and into the Alafia
River 2 miles south of the town of Riverview. Average flow is
,about 20 mgd.

OTHER STREAMS

Bell Creek drains 15 square miles lying south of the Alafia
River. It flows northward and enters the Alafia River about 5
miles downstream from Lithia Springs and 9 miles upstream from
the mouth. Its average flow is about 7 mgd. Rice Creek, draining
an area of about 5 square miles south of the river, flows in 5
miles upstream from the mouth. Average flow is probably more
than 2 mgd.
Numerous lesser tributaries flow into the Alafia River through-
out its course. The combined area that they drain is approximately
25 square miles and on the average they contribute about 20 mgd
to the river.

LITHIA SPRINGS

Two springs, located on the south bank of the Alafia River
bout 19 miles upstream from the mouth and about 2 miles down-
stream from Turkey Creek, are known collectively as Lithia
springs. One of the springs forms a pool about 50 feet across. It
is connected to the river by a run about 200 feet long. The other
spring forms a pool 100 feet across. It is connected to the river






FLORIDA GEOLOGICAL SURVEY


by a run about 600 feet long. The average combined flow of the
springs probably exceeds 30 mgd. The flow of the springs was
measured 17 times between 1934 and 1938. The highest combined
flow measured was 46.7 mgd; the lowest, 25.9 mgd.
On the basis of five samples collected from Lithia Springs
during the period from November 1957 to June 1958, the dissolved
materials averaged about 268 ppm. The dissolved materials in the
water from each spring opening are similar in both quantity and
chemical character. Nearly 100 percent of the dissolved materials
is mineral content. Calcium plus magnesium plus alkalinity as
carbonate was about 51 percent, and sulfate was about 30 percent
of the mineral matter. Color intensity was low, being in the range
from zero to five platinum-cobalt scale units. These quantities
compare very favorably with the dissolved materials and the
chemical character of Lithia Springs on July 19, 1923, and again
on April 30, 1946.

BUCKHORN SPRING

Buckhorn Spring flows into Buckhorn Creek which in turn
flows into the Alafia River about 8 miles above the mouth. The
spring is 3 miles northeast of Riverview and half a mile north
of the Alafia River. It forms a pool about 30 feet across and
empties directly into Buckhorn Creek. Its average flow is
approximately 8 mgd. The U. S. Phosphoric Products Company
pumps from the spring to supply a plant at Gibsonton.
Mineral content on April 26, 1956, was 310 ppm. Calcium plus
magnesium plus alkalinity as carbonate was 44 percent, and
sulfate was 22 percent of the mineral content. Color intensity
was 20 platinum-cobalt scale units.


BULLFROG CREEK BASIN
BULLFROG CREEK

Bullfrog Creek drains 40 square miles of land in southern
Hillsborough County. Headwaters of the creek are just north of
Wimauma. From there the flow is westward, then northward, then
westward and into Hillsborough Bay about a mile south of the
Alafia River. The stream drains an area of sandy land dotted
with ponds and sinkholes. The largest tributary is Little Bullfrog
Creek. Land elevations in the basin range from sea level at the
bay to 140 feet above sea level on ridges in the upper reaches.






REPORT OF INVESTIGATIONS No. 25 61

Bullfrog Creek has a fairly well defined channel. The channel
gradient is fairly steep (13 feet per mile) in the upper part and
is moderate in the central part (5 feet per mile). In the lower
part the gradient is nearly flat (1 foot per mile). Channel
gradients are shown in figure 37.
The average flow of the creek at Big Bend Road (drainage
area: 29 sq. mi.) is about 18 mgd. However, wide variations in
flow occur. From October 1956 to October 1958, the highest flow
was 1.4 bgd. Several times during the 2-year period the flow
ceased. During June 1957, there was zero flow for 12 consecutive
days. More than 20 percent of the time the flow was less than 1
mgd.
At the mouth of Bullfrog Creek, water flows in and out because
of fluctuations in the level of the bay; however, the net flow is into
the bay. The average net flow at this point probably exceeds 30
mgd.
The dissolved materials in Bullfrog Creek near Wimauma
averaged 36 ppm and ranged from about 25 to 49 ppm, from
September 1956 to September 1958. The values are based on 16
water samples taken at about 6-week intervals during the period.
Color intensity ranged from about 65 to 200 platinum-cobalt scale
units and was often a large percentage of the dissolved materials.


12 13 14 15
100

90 90

so --/ so- 8

70 ------ 70

60 s60

g 50 50 m

? 40 40 W

3030
12 13 14 15 16 Z
20
Note: Data token from
SU. S. G.S. Topographic
709 0
t O-- M o p |. IJ

6 7 B 9 10 II
DISTANCE ABOVE MOUTH (MILES)

Figure 37. Profiles of streams in the Bullfrog Creek basin.






FLORIDA GEOLOGICAL SURVEY


The remainder of the dissolved materials was mineral content with
chloride, sodium, bicarbonate, silica, calcium, and sulfate in small
amounts; chloride was present in greatest quantity most of the
time, followed closely by most of the other minerals.
Large changes in streamflow are accompanied by irregular
changes of small magnitude in the dissolved materials. The water
contacts only the insoluble sand deposits, which overlie the im-
permeable Hawthorn formation and does not contact soluble
materials. The wide range in color indicates contact with vegetable
matter on the surface or at shallow depths.

LITTLE BULLFROG CREEK

Little Bullfrog Creek, which drains about 9 square miles of
land south of Riverview, flows into Bullfrog Creek a mile south
of Big Bend Road. It has a well defined channel with a gradient
of about 11 feet per mile. At the mouth, the estimated average
flow is 7 mgd.

LITTLE MANATEE RIVER BASIN
LITTLE MANATEE RIVER

The Little Manatee River, about 40 miles long, heads in a
swampy area east of Fort Lonesome, in southeastern Hillsborough
County, flows westward, and empties into Tampa Bay near the
town of Ruskin. The stream drains 150 square miles of land in
southern Hillsborough County and 75 square miles of land in
northern Manatee County. At its source the channel is about 100
feet above sea level and has a fairly steep gradient, particularly in
its upper reaches. (fig. 38). In general, the channel is well defined
and has steep, sandy banks. Tributaries to the Little Manatee
River enter from both sides at fairly regular intervals. In the
lower reach of the river the stage rises and falls with the tide in
Tampa Bay and when flow is low, tidal fluctuations are discernible
as much as 15 miles upstream from the mouth.
Lake Wimauma is the largest of the several lakes in the river
basin. It has a surface area of about 130 acres.
For the 19-year period from 1940 to 1958, the average discharge
of the Little Manatee River at U. S. Highway 301 was 115 mgd.
Flow ranged from a minimum of 0.8 mgd in June 1945 to a maxi-
mum of 6,110 mgd in June 1945. About 90 percent of the time the
flow was 12 cfs or 8 mgd or more. Fifty percent of the time flow
was 48 cfs or 31 mgd or more, and 10 percent of the time it was






REPORT OF INVESTIGATIONS NO. 25 63



120
ZII

110oo
I / 100

90


w
"C U0 70 0
S 5 / >

70 0







o Note: Daota-laoken from
,, 20 U.S.G.S. Topographic
jS I 30 Mops.
000












15 20 25

DISTANCE ABOVE MOUTH (MILES)
Figure 38. Profiles of streams in the Little Manatee River basin.



480 cfs or 310 mgd or more (fig. 39). Usually the average monthly


averaged 57 ppm (time-weighted) from October 1956 to September
1957 and ranged from 36 to 88 ppm. These materials were about
I to 49 percent organic materials. The remainder of the dissolved
material was mineral content with sodium chloride, bicarbonate,
i ilica, calcium, and sulfate in small amounts, each predominating at
Different times. Mineral content for the same period ranged from
:0 to 55 ppm as indicated by figure 40.
About 50 percent of the time, the specific conductance was equal
io or less than 63 micromhos. The mineral content was about 62
percent t of the specific conductance; therefore, half the time the
minerall content from October 1956 to September 1957 was equal






FLORIDA GEOLOGICAL SURVEY


500





100

50





10

S
-..7-

t--- I --- -
IO \=^ -- ------ =






t -- -- -- -- -- -- -- -- -- --


0 10 20 30 40 50 60 70
PERCENT OF DAYS


80 90 100


Figure 39. Flow-duration curve of Little Manatee River near Wimauma.


to or less than 40 ppm. Figure 41 shows the percent of days the
specific conductance was equal to or less than a given value for the
period stated.
Figure 41 can be used to estimate the mineral content for any
desired percentage of days according to the following relationship:
Mineral content in ppm= (0.62) x (specific conductance). The
factor, 0.62, is the average of the ratios of mineral content to
specific conductance for composite samples collected during the
period of record.


b.


bJ
o
x
X

r 1,000
0


LITTLE MANATEE RIVER
NEAR WIMAUMA, FLA.
(1939 TO 1958)


00I 0 1 1 1
1 F --i i-





SPECIFIC CONUUUTANCE IN MICROMHOS AT 25* C.


CD




Is,

C'

D.4




(BD

09


















' s


N


0



ch
Np











so
II

CD

1p






cl
OCD


-tB
rt-^d


oa

^5!



CD'

CD


N
(P


MINERAL CONTENT PPM
0 o .8 0


OCT



NOV


DEC


JAN


0




0t
I-
z:

0

0:
oi

z~
Pn






66 FLORIDA GEOLOGICAL SURVEY

The color intensity during the low rainfall period from Novem-
ber 1956 to January 1957 was stable at about 75 units. During
the early part of the rainy season, February to April, much of the
soluble organic material was leached from the vegetation and the
color intensity increased (fig. 42). Greater flow during the latter
part of the rainy season resulted in less color intensity.
The effect of rainfall upon streamflow is usually accompanied
by changes in both the amount and character of dissolved materials.
Chemical character of dissolved materials is exhibited in figures
43 and 44.


:I'



I

I

i- I




COLOR x II X

l i- "XX Xo o x W XXII
i l gl m p X X lX X ,Ii Xl X i iiXi


Figure 42. Color in relation to rainfall and flow of Little Manatee River
near Wimauma (October 1956 to September 1957).


! iao
S100
1000
900
Soo
?o00
600


400
3CC
200






REPORT OF INVESTIGATIONS No. 25


0 0 -
o W a u N E n .
1956 2q57
Figure 43. Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1956 to September 1957).

Water temperatures in the stream varied from 510 F. in No-
vember to 870 F. in June and July.
During the period October through December 1957, a relatively
sharp increase in mineral content, from 24 to 181 ppm, occurred.
Simultaneously color intensity decreased from 140 to 27 (platinum-
cobalt scale units) and calcium plus magnesium plus alkalinity as
carbonate increased from about 6 to 132:ppm. The sulfate increased
from 2 to 20 ppm. These changes resulted from a combination of
below-normal rainfall and heavy pumping of ground water for
irrigation in the headwaters of the basin. Part of the water used







FLORIDA GEOLOGICAL SURVEY


40


ia




30 [
120

It
too




4r



30
60

30
0

i0 i-
o0*^*


^Sg


*LUORIE., NITRATE:
PHOSPHATE
SSLICA

RD CHLORIDE
S0 SULFTE
A- SALINITY AS
CARBONATE
-- SODIUM a
POTASSIUM
M MAGNESIUM
lJ[ CALCU.M


1957


Figure 44. Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1957 to October 1958).


for irrigation infiltrates the soil and probably reaches the water
table. It moves through the sand deposits and discharges into the
streams of the basin.
The chemical character and concentration of dissolved materials
in Little Manatee River may be explained largely by the interaction
of rainfall upon the surface sand deposits. The sand deposits rest
upon the relatively impermeable Hawthorn formation. The rain
quickly permeates the sand. Downward and upward movement
through the underlying Hawthorn formation is much slower.
Therefore, rainwater tends to move over the ground or down-
gradient within the sands. The sands are only slightly soluble, and
the length of time in contact is relatively short, thus limiting the
mineral content. The range in color intensity indicates contact
with vegetable matter on the ground surface or at shallow depths.
The Little Manatee River water is suitable for municipal use
with respect to dissolved materials except for color intensity. Most
of the time, color intensity exceeds the recommended amount. Iron


I 1 I I I I I .... ....


1958






REPORT OF INVESTIGATIONS NO. 25


concentrations probably are greater than those indicated. Bac-
teriological suitability is not included as a part of this report.
Water from the Little Manatee River apparently is suitable
for agricultural uses; this assumption is qualified to the extent
that the boron content of the water is not known.
Little Manatee River water is more suitable for industrial uses
than that from other major streams in the county. The dissolved
material concentrations in this stream are relatively low compared
to the other major streams in the county, except for color.
At the mouth, the average flow of the Little Manatee River
probably exceeds 180 mgd.
The Little Manatee River above its confluence with Howard
Prairie Branch drains 35 square miles of land of the eastern part
of the river basin. About 31 square miles of this land is in Hills-
borough County, and the remaining 4 square miles is in Manatee
County. Alderman Creek brings water collected from Manatee
County into Hillsborough County. This creek joins the Little
Manatee River 34 miles above the mouth. The average flow of
the river above Howard Prairie Branch is probably 30 mgd.

HOWARD PRAIRIE BRANCH

Howard Prairie Branch drains an area of about 13 square miles
in Hillsborough County and 5 square miles in Manatee County.
Water collected in Manatee County is channeled northward into
Hillsborough County. Three lakes form part of the Howard Prairie
Branch channel. The largest and easternmost lake is about 60 acres
in area at a stage of 73 feet above mean sea level. At its confluence
with the Little Manatee River, 29 miles upstream from Tampa Bay,
Howard Prairie Branch contributed an average of 14 mgd to the
river.
PIERCE BRANCH

Pierce Branch drains 10 square miles of land in Hillsborough
County. This stream flows southward and enters the Little Manatee
River at a point about 27 miles above the mouth. The average
flow of Pierce Branch is probably 8 mgd.

CARLTON BRANCH

Carlton Branch drains 10 square miles of land in Hillsborough
County. This stream, like Pierce Branch, flows southward. It
enters the Little Manatee River about 26 miles above the river's
mouth. The average flow of Carlton Branch is about 8 mgd.






FLORIDA GEOLOGICAL SURVEY


SOUTH FORK LITTLE MANATEE RIVER

The largest tributary to the Little Manatee River is South Fork
Little Manatee River. It drains approximately 40 square miles of
land in Manatee and 1 square mile in Hillsborough County. The
stream flows northwestward into Hillsborough County, flowing
at an average rate of 30 mgd. The South Fork Little Manatee
River flows into the Little Manatee River about 21 miles above
the river's mouth and 2 miles above the point where the Little
Manatee River flows across the Hillsborough-Manatee county
line into Manatee County.

OTHER STREAMS

Numerous other streams drain the remaining 110 square miles
of land not covered in the discussion of tributaries to the Little
Manatee River. These streams contribute on the average about
90 mgd to the river or about one-half the flow at the mouth.

PEACE RIVER BASIN

The Peace River drains about 4 square miles of land in the
southeastern corner of Hillsborough County. The river flows
southward to Charlotte Harbor and the Gulf of Mexico. The area
in Hillsborough County contributing water to the Peace River is
mainly swampland that lies 130 to 145 feet above the sea.

GROUND WATER

Part of the rain that falls on the earth moves downward
through the ground to the zone of saturation to become ground
water. The ground water then moves laterally along the hydraulic
gradient to discharge points such as springs, wells, or the sea. The
materials through which the water moves in usable quantities is
known as an aquifer. Where water in the aquifer is at atmospheric
pressure and is free to rise, the water occurs under nonartesian
conditions and the water surface is referred to as the water table.
Where relatively impermeable beds restrict the vertical movement
of water in a completely saturated aquifer, the water occurs under
artesian conditions, and the surface described by the elevations to
which water will rise in wells tapping the aquifer is referred to as
the piezometric surface. Artesian conditions exist when the water
is under greater than atmospheric pressure or when the water






REPORT OF INVESTIGATIONS NO. 25


will rise above the top of the aquifer where tapped. Where the
piezometric surface is lower than the water table, the water may
move downward from the monartesian aquifer into the artesian
aquifer. Where the water table is lower than the piezometic sur-
face, water may move upward from the artesian aquifer into the
nonartesian aquifer or to flowing wells and springs. Ground
water in Hillsborough County occurs under both artesian and
nonartesian conditions.

WATER-TABLE AQUIFER

The undifferentiated surface sands and clays generally contain
water under water-table conditions in Hillsborough County, but
artesian conditions may occur locally. The water in the aquifer is
derived from local rainfall, and the water table is only a few feet
below the ground surface.
Wells deriving water from the sand are constructed by driving
a screened well point into the saturated zone or, on the high
"prairies," by sinking a pipe to the top of a layer of hardpan and
chiselling a hole through the handpan into the underlying sand.
The well is then pumped until the water is clear. Drive-point wells
are generally less than 20 feet deep and yield about 5 gpm.
The wells developed below the hardpan are usually from 8 to
16 feet deep and may yield more than 200 gpm where the hardpan
is sufficiently thick and strong to allow development of large cavities
under it.
Generally water is not available in desirable quality or quantity
from the water-table aquifer, and it is not a very important source
of supply in the county.

SHALLOW ARTESIAN AQUIFER

Wells developed in the sand and limestone beds of the Hawthorn
formation in the southern half of the county yield up to about
500 gpm of water of relatively poor quality. The advantages
of developing wells in this aquifer are that shallower wells and
less expensive pumps are required if only small to moderate yields
of water are needed. The saving effected could offset the advan-
tage of having better quality water from the deeper aquifers. The
aquifer in the Hawthorn formation, though important in Polk
County, is of minor importance throughout the small area of
Hillsborough County in which it occurs.






FLORIDA GEOLOGICAL SURVEY


PRINCIPAL ARTESIAN AQUIFER

The principal artesian aquifer includes the units described by
Stringfield (1936, p. 124-128) and the Floridian aquifer of Parker
(1955, p. 188-189). Parker (op. cit.) includes the Lake City lime-
stone, Tampa limestone and, where hydrologically connected, the
Hawthorn formation in the Floridan aquifer.
The physical limits of the aquifer should be set at hydrologic
boundaries. In Hillsborough County, there is no evidence of a
hydrologic boundary at the base of the Lake City limestone. In
addition, rotary drilling in the county has resulted in loss of mud
circulation throughout the older Tertiary formations (i.e., Oldsmar
and Cedar Keys limestones) and possibly the upper part of the
Lawson limestone of Cretaceous age. Loss of circulation indicates
the presence of cavities that, in all probability, are the result of
solution by ground water. Therefore, the entire Tertiary system
from the base of the Hawthorn formation to the top of the Gulf
series (as used by the Florida Geological Survey) of Cretaceous
age is included in the principal artesian aquifer of this report. The
general occurrence of cavities in the Eocene rocks and the inferred
presence of similar cavities in the Oldsmar and Cedar Keys lime-
stones indicate ground-water movement to at least that depth.
Limestone, more or less dolomitized, is the dominant lithologic
component of the aquifer. Zones of high permeability are
distributed erratically through the aquifer. These zones have not
been traced over great distances. It is known from examination
of caves in other areas that most horizontal water courses in
limestone end in vertical openings that intersect other horizontal
cavities at different levels. Similar conditions are assumed to be
responsible for the hydrologic continuity observed in the principal
artesian aquifer in Hillsborough County.
The hydraulic systems just described are limited in vertical
extent by layers of rocks of low permeability. The rocks of the
upper part of the Ocala group tend to restrict this system. The
Tampa and Suwannee limestones, which are a hydrologic unit,
comprise the aquifer above the Ocala. The few available data
indicate that the formations underlying the Ocala group to the
greatest depth commonly penetrated by water wells tend to form
another gross hydrologic unit. The two systems are connected
hydraulically by solution openings along structural planes that
probably are faults. The vertical permeability of these openings
is sufficient to allow approximate equilibrium to obtain between






REPORT OF INVESTIGATIONS NO. 25


the two systems when the time of interchange of water is great
and the amount of water interchanged is small. Where either
system is stressed by a local discharge through a large spring or
well, the vertical movement of water is relatively small and the
two systems behave as separate aquifers. Thus, throughout most
of the county the total limestone section is essentially a hydrologic
unit, but wherever either system is stressed by large volumes of
discharge the Tampa and Suwannee limestones act as an aquifer,
separate from the limestones below the Ocala group.
Several thousand gallons per minute can be pumped from
any of the several zones in the aquifer. The specific capacity
of the well depends on the size and continuity of the cavities pene-
trated by the well.
Sulphur Springs (801-227-B) flows an average of about 37
mgd. Based on chemical analyses of water from the spring as
compared with water from well 801-227-3, about 90 percent of
the water, or 33 mgd, is of good chemical quality derived from
the Tampa and Suwannee limestones. The remaining 4 mgd
consists of highly mineralized water from below the Ocala group.
The proportions of minerals in the spring water are different from
those in sea water, indicating that the concentration and chemical
character of the water do not reflect salt-water intrusion from
Tampa Bay. Instead, the water probably is diluted connate water.
The connate water.is derived from older rocks that have not been
flushed by fresh water as have the more recent rocks near the
surface. Concentrations of chloride of more than 69,000 ppm
(Black and Brown, 1953) are known to occur in the older rocks
in Florida. These rocks are rich in gypsum and anhydrite from
which sulfate could be dissolved, giving rise to the type of water
occurring in well 801-227-3.
The movement of water in the Tampa and Suwannee limestones
was traced by introducing 8 pounds of sodium fluorescein into a
sinkhole about 1,000 feet northwest of Blue Sink. During the test,
the dye followed a sharply angular and narrow course correspond-
ing to the trends of regional structures. The dye moved one-
half mile southwest, then 11/2 miles southeast from Blue Sink (803-
227-A), then southwestward to 801-226-A, and to Sulphur Springs.
A number of randomly located points in the area were monitored
but did not show any dye. Though the test was not made under
ideal conditions, the results seem to be quite clearly indicative
of structural control of ground-water movement in the area. The
inferred upward movement of connate water along fault planes
and the observed path of the dye are interpreted as evidence that






FLORIDA GEOLOGICAL SURVEY


some of the fault zones have a higher vertical permeability than
the nonfractured rocks.
Water movement in limestones of the principal artesian aquifer
is essentially restricted to solution zones that have developed along
joints, faults, and bedding planes. The more permeable fractures
are the avenues of movement of greater quantities of water than
the less permeable smaller fractures. As the solution-enlarged
fractures coalesced and extended to a point of discharge such as
a spring, the pressure in the larger cavities was reduced and water
moved from smaller fractures into the solution-enlarged cavities.
This process resulted in virtual conduits through which water
moved at relatively high velocities. As the velocity of the water
in the conduit increased, the water reacted less with the limestone
in the recharge area and thus was capable of dissolving more lime-
stone closer to the discharge area and further enlarging the
existing conduits. Eventually this destructive process led to over-
stressing and collapse of the limestone skeleton. After the
supporting limestone had collapsed in a large enough area, the
weak clays and sands fell into the cavity and resulted in the
formation of a depression in the land surface called a sinkhole.
The water, blocked by a plug of overburden, began development of
a cavity system to bypass the plug. Relaxation of lateral stress
in the vicinity of the original sinkhole resulted in redistribution
of stress in the area and probably aided the expansion of joints
and, consequently, the re-routing of water through the area.
The process above, repeated many times over the years, produced
the many sinkholes present today.
Thus, the existence of sinkholes in an area is indicative of a
substantially cavernous condition and infers high permeability of
the limestone. Where the sinkholes occur in a line or have coalesced
to form a linear depression, the directional trends of the joint
systems or faults which control the solution activity can be
established. In Hillsborough County, these trends are at compass
bearings of about N. 40 E., N. 40 W., N. 13 E., and N. 70 E.
Sulphur Springs derives the greater part of its water from the
Suwannee and Tampa limestones. The apparent decline of water
level in the Suwannee and in the Tampa is about 15 feet at the
spring. Water level in the Avon Park limestone is lowered about
5 feet by discharge from the spring. Distribution of springs and
linearity of surface features in the area suggest the existence of
a fault along the course of the Hillborough River and another
trending northwest through the area. It is probable that the bulk
of the water from the Avon Park and lower limestones is moving






REPORT OF INVESTIGATIONS No. 25


along the fracture zone of a fault. This indicates that the Ocala
group is acting as a confining bed in a localized area about the
spring. The Suwannee and Tampa limestones should be considered
as a separate aquifer in this area.
A similar condition probably exists to the north and northeast
of Boiling Spring (755-204-A). Several instances of higher water
levels with depth, lowering of water levels in one well following
drilling of another well nearby, and water levels that are incon-
sistent with regional trends were reported in that area. The
reports were fairly consistent and are believed to be qualitatively
correct. The hydrology of the area adjacent to Boiling Spring is
complicated by the presence of a fairly well developed aquifer in
the Hawthorn formation and will require further study to
determine the exact conditions.
The confining beds overlying the principal artesian aquifer are
composed of clays of the Hawthorn formation and other undif-
ferentiated formations. The thickness of the confining beds ranges
from a few feet in the north-central part of the county to about
300 feet in the southeastern part. Numerous sand-filled sinkholes
breach the confining beds in the northern half of the county. These
,sinkholes act as recharge wells and probably contribute a major
part of the recharge to the aquifer in this area. Sinkholes become
progressively fewer toward the discharge areas and, except for
some quite ancient, -obscure, and completely filled sinkholes, have
not been found in discharge areas. Though some water moves into
Hillsborough County from Pasco and Polk counties, the greater
part of the water in the aquifer is introduced either by percolation
through the confining beds or through sinkholes that may or may
not be sand filled. Natural discharge is through springs either
on the land surface or in rivers and lakes or Tampa Bay. Water
discharges westward into the Gulf of Mexico from a small area
in the northwestern part of the county.
The quantity of water that may be obtained from wells in this
area is practically limited only by the desired quality of the water.
Throughout the county, yield is generally controlled by size and
depth of wells. However, salt water occurs at depth and quality
of water becomes an important consideration in deciding how
deep a well should be drilled. Consequently, the usable part of
the aquifer may be only a small part of the total aquifer. The
effective bottom elevation of the usable part of the aquifer is at
a depth below sea level of about 40 times the elevation of the
piezometric surface above sea level. The highest measured point
on the piezometric surface in the county is about 100 feet above





76 FLORIDA GEOLOGICAL SURVEY

mean sea level in a well about 3 miles northeast of Plant City
(803-204-1). Assuming an effective head of 85 feet, a maximum
bottom elevation of 3,400 feet below sea level is computed for wells
that will yield fresh water under those conditions. As the
piezometric surface approaches sea level, the thickness of the usable
part of the acquifer approaches zero and fresh water cannot be
obtained.

RECHARGE TO UNDERGROUND FORMATIONS

Recharge of the water-table aquifer occurs whenever rain falls
on the land surface. The water-table aquifer in Hillsborough
County consists of sand of about 30 percent perosity. The water
table rises approximately 3 inches for each inch of rainfall that
reaches it. The water table generally is only a few feet below
land surface even in dry periods, and areas that are not well
drained are likely to become saturated and to have water standing
on the surface after a heavy rain. The fluctuation in water levels,
though rapid, is only a few feet in magnitude.
Recharge of the artesian aquifers is more complex. It occurs
both by percolation through the so-called confining beds and by
surface water and discharge from other aquifers entering through
exposures of the aquifer in sinkholes. The water will flow into and
through all sediments. The rate of flow is determined in part by
the porosity and the hydraulic gradient. Observed water-level
fluctuations in the principal aquifer (fig. 45) are quite rapid and
of large magnitude, indicating that part of the recharge enters the
aquifers in a short time at a high rate. The most probable places
where high rates of recharge occur are the numerous sinkholes
and points where the aquifer is near the surface. The latter places
are not sufficiently numerous to be of areal importance. Thus,
sinkholes are the apparent avenue of rapid recharge of the aquifer.
An example of this type of recharge may be seen in the system of
sinkholes between Linebaugh and Fowler avenues west of Florida
Avenue in Tampa. The introduction of large quantities of water
into the aquifer from a drainage ditch through these sinkholes
causes an almost immediate and large rise in water level, in a well
near Nebraska Avenue at Temple Terrace Highway (801-227-1).
This well is hydraulically connected with cavities in the Tampa
and Suwannee limestones. See figure 46b.
Interpretation of the hydrographs of the group of three wells
(757-212-1, 2, 3) supports this hypothesis. The water level in Well
2, reflecting water-table conditions, rises several feet in response





REPORT OF INVESTIGATIONS NO. 25


L O 0 1n Ch
q 0


I I,~ II I IJ .. I~ T11,1 1MAWETH.Ej S.T-t'.1II

E E
z 20


Figure 45. Water levels in selected wells and the precipitation at Tampa and
St. Leo weather stations.

to a heavy rain. The water level in Well 1, in the principal aquifer,
rises proportionally as and almost simultaneously with the level in
Well 2. The water in Well 3, reflecting the level in the shallow
artesian aquifer, rises with a lag of several days and in a subdued
manner. This is interpreted as being indicative of recharge of the
principal artesian aquifer by water that has not passed through
a permeable phase of the discontinuous shallow artesian aquifer.
The best explanation of this involves the presence of a vertical
solution opening through which the water could move into the
principal artesian aquifer from the nonartesian aquifer.

DISCHARGE FROM UNDERGROUND FORMATIONS

When an aquifer is saturated, the long-term volume of discharge
must equal the long-term volume of recharge. Variations in the
volume of water in storage are important only for short periods of
time and do not change the long-term recharge-discharge relation-
ships appreciably.
Ground water is discharged through both springs and wells


r'Fi~lMi~li;Lmc
10 A I i







FLORIDA GEOLOGICAL SURVEY



S 747-220-1

30-v
-30 -


-40
751-ZC3-1





-14
T2- 207




-46
-48 J-- -' ---- -1- -- -
48
52-207-1

L -


44 -


7 220 -







I I I / I )


TD<~


-IC


--12

-ia
-14


j -'3
-'


756-215-1 -i


I I


71 56-227-i I I j t
7r --


-is

-41


-43

-45


-47


-49


J A S OIN D J F MA, M J J A S OND J F M A M J A S 0 N D
1956 1957 ___ 1958


Figure 46a. Water levels in selected wells.


'' '''' "' ''


' '


/







REPORT OF INVESTIGATIONS No. 25


757-212-2

-/ I -

-10 -






-16
-10
757-221-1

-12 1 1 1


3
801- 213-22

-5-

-7 J _


I iii l i I~ I I II 1 I~ I l I IV I


801-227-3


I I i \


- 802-238-1I


804-207-1





I I I I -- I I I I II I I
J - - --/


-n
z -9
J -18
0
-20

w -22
(r -1
w -1


z -15

S-7
i -17


0

+2

0

-n


-16


J AIS N D J FIMIAIMIJ J AS 0o N D J F M AIMI JJ |AIS I D
1956 1957 t 1958

Figure 46b. Water levels in selected wells.


_i41


IC


-i i I i I I i I I I IUI 1 I~I I ii I i i i


801-227-1
1 1 1 1


I


r
3
a
W
9
II


I Ii


I I III II I I I I





FLORIDA GEOLOGICAL SURVEY


__ 1 1 1 t r I I -i
-to- i



-142 ----- -i _

-[ o-' '___ l. -__ILI i I IL!__ ____ L ____ i / i
-zo
804-235-1
10





16 _



_-6 8 05-237-~ j J

2 ---I
80 -237-i
6- -







0-L-L_- 1 I i\ / ~ 11
809-239-1
23



S-27

810-237-1




809-239-1





-13 -- _-
-15



-7



J IAISIO DJ F A J AMJJASIO ND J F M A M J J AS N D
1956 1957 1958

Figure 46c. Water levels in selected wells.






REPORT OF INVESTIGATIONS NO. 25


809-227-1 I
-8
-10


757-212-3
c -27

" -29 I

1 -
-3

I -76
802-217-1





-82




802-225-26 9 I

-23




Figure 46d. Water levels in selected wells.




though, in general, more water is discharged through springs.
Data were collected from several hundred springs and wells
during this investigation. Information for most of the large and
a few of the smaller springs is listed in table 3. The locations of
these springs as well as many smaller springs for which no
information was collected are shown in figure 47.
Spring flow varies with head in the aquifer and decreases when
water levels decline. Low rainfall during the winter, use of
irrigation wells from November through May, and increased use
of water during the tourist season from January through April
cause water levels to decline. Therefore, spring flow is decreased
during the dry season.






FLORIDA GEOLOGICAL SURVEY


Bow od f .m U. S GeologDc
Siwey aograp*c wAdvonges
Figure 47. Locations of springs and areas in which water levels in the
principal artesian aquifer were above land surface in September and October
1958.

WATER LEVEL

The amount of water in the ground at any time depends on the
balance between recharge and discharge, on the transmissibility of
the aquifer, and on the ability of the aquifer to expand and contract
in response to changes in pressure. The water level is an indication
of the amount of water in an aquifer, and changes in the amount
of water in storage are reflected in changes of water levels in
wells that penetrate the aquifer. A rise in water level indicates
an increase in water pressure, which causes expansion of the
aquifer and compression of the water and an increase in the









TABLE 3. Information on Selected Springs in Hillsborough County

Estimated Approximate
Spring name Spring Owner Location discharge elevation Use Remarks
number (gpm) (ft.)


Lithia
Little Lithia
Messer
Buckhorn

Boiling
Palma Ceia
Craft Mineral
Deshong

Oak

Magbee

Eureka
Do.





Lowry

North Park
Jackson
10th Street Sink


Purity
Sulphur
Richardson
Trinity



Blue Sink


751-213-A
751-213-B
752-217-A
753-218-A

755-204-A
755-229-A
757-222-A
757-222-B

757-225-A

757-227-A

800-220-A
800-220-B
800-221-A
800-221-B

800-226-A
800-226-B
800-227-A

800-227-B
800-234-A
801-226-A

801-226-B
801-227-A
801-227-B
801-227-C
802-226-A



802-227-A


804-218-A -----.
805-219-A William Fink


808-205-A


SE% sec. 17, T. 30 S., R. 21 E.
SE% sec. 17, T. 30 S., R. 21 E.
SW% sec. 14, T. 30 S., R. 20 E.


County of Hillsborough
do.
-- .--------
U. S. Phosphoric Products
Corp.

City of Tampa
Mrs. H. E. Herrington
do.

Oak Park Drive-in Theatre

City of Tampa

------------------------
..-.... ...- ------- -



City of Tampa
Mrs. H. L. McGlammery
City of Tampa



Mrs. Cecil Fink

City of Tampa
Purity Springs Water Co.
City of Tampa
Hedrick Estate


SW A
SW1A
SW1A


SEA NE% sec. 9, T. 30 S., R. 20 E.
SW% NWIA sec. 25, T. 29 S., R. 22 E.
NE%1 NE 1 sec. 34, T. 29 S., R. 18 E.
SW% SW%A sec. 13, T. 29 S., R. 19 E.
SW% SW4a sec. 13, T. 29 S., R. 19 E.

NE1/ NW% sec. 17, T. 29 S., R. 19 E.

SE1 NW% sec. 13, T. 29 S., R. 18 E.

SE% NWYA sec. 31, T. 28 S., R. 20 E.
SE% NW% sec. 31, T. 28 S., R. 20 E.
SE 1A NWI sec. 30, T. 28S., R. 20 E.
SE% NWIA sec. 30, T. 28 S., R. 20 E.

NEA SWA sec. 30, T. 28 S., R. 19 E.
SW'A SE1A sec. 30, T. 28 S., R. 19 E.
NW1A SWA sec. 25, T. 28 S., R. 19 E.

NW% NW1 sec. 36, T. 28 S., R. 18 E.
SE%1 NW% sec. 35, T. 28 S., R. 17 E.
SW% SWA sec. 19, T. 28 S., R. 19 E.

NWA SW% sec. 30, T. 28 S., R. 19 E.
NE% NW% sec. 25, T. 28 S., R. 18 E.
SE1A NE% sec. 25, T. 28 S., R. 18 E.
SWA NE1A sec. 25, T. 28 S., R. 18 E.
SW% SW% sec. 18, T. 28 S., R. 19 E.



SE% NW1A sec. 13, T. 28 S., R. 18 E.


SE% NW% sec. 4, T. 28 S., R. 20 E.
SE1 SE1' sec. 29, T. 27 S., R. 20 E.

SE'/ NEA sec. 15, T. 27 S., R. 22 E.


20,000
2,000
500

5,000
2,000
50
150
20

100

300

2,000
200
1,000
1,000

15
100
30

50
5
0

15
500
60,000
210


30+5
;305


Recreation
do.
None

Industrial
None
None
None
None

None

None

None
None
None
None

None
None
None

None
None
None

None
Public supply
Recreation
Public supply








None


A complex of 6 openings.
Water formerly bottled and sold.
Formerly supplied slaughter
house.
Spring is buried, discharge via
conduit.
High color, formerly public sup-
ply for Tampa.

200 ft. SW of 800-220-A.

0. 15 mi. N. of 800-221-A Spring
is in bottom of ditch.


Very strong H2S odor, sulfur de-
posits on curb.
Formerly supplied laundry.

Dike prevents flow except at high
stage.




Spring flowed from orifice into
pool-then out orifice on other
side of pool; ceased flow 7-10-58
following earthquake.
Spring flows from orifice into pool
-then out orifice on other side of
pool.


Spring is
corner.
On south
Creek, 50


150 feet. NW of sec.

bank of Blackwater
ft. west of canal.


5
25
7

5
5
13

5
7
7
5


20
300









REPORT OF INVESTIGATIONS NO. 25


U/1.:1( 5.4,%S DS'1...OF C14E INIERIOR
GtOL(4GICA1 SUiRVEY


FLORIDA GEOLOGICAL SURVEY
R 0 VnonR. OlClor


47;-. 60 40

"I/ /'"




























Bsos to pk li U S Geoaocol Iy'rc';y y >WS .Wclet eho'l

Figure 48. Piezometric surface in the principal artesian aquifer (September-
October 1958).









amount of water in storage. Conversely, when the water level
declines the aquifer contracts and the water expands, thus decreas-
ing the amount of water in storage.
The configuration of the piezometric surface in Hillsborough
County during September and October 1958 is shown in figure 48
by contour lines. This surface represents the water levels that
may be expected in wells tapping the principal artesian aquifer
throughout the county. The hydraulic gradient and direction of
movement of water also may be determined from the map. Water










always moves down the hydraulic gradient or normal to a contour
line from any point.
ing the amount of water in storage.



































4 40 30, .28










I Uppi numi i 11 ubo m




*h I Lino, m lu m ri t 1 1 i ra ll I C feet .ine t r m > l

Figure 49. Piezometric surface in northwestern Hillsborough County (No-
vember 21-28, 1957).





REPORT OF INVESTIGATIONS NO. 25 85

The degree of uniformity of spacing of the contours is an
indication of the uniformity of the geology and of recharge and
discharge. Closer spacing of the contours or piezometric highs
indicates low transmissibility, local recharge, or both. Conversely,
wide spacing and re-entrants or lows in the surface indicate high
transmissibility, local discharge, or both. The shape of the piezo-
metric surface changes with rates of recharge and discharge.
The piezometric surface shown in figure 49 is based on meas-
urements made during September and October of 1958. Normally,
annual highwater levels occur inthese months. In 1958, however,
water levels were very high during the winter months, reflecting
unusually high rainfall, and were somewhat lower in the fall.
The piezometric surface generally slopes toward Tampa Bay
from two piezometric highs, one in Polk County, and the other
in Pasco County. Between the two highs is a re-entrant that
Generally follows the Hillsborough River. This re-entrant tends
to become less pronounced down the gradient and probably is caused
by discharge from the many springs in the river valley where the
aquifer is near or at the surface. If underground drainage were
largely responsible for the feature, the contours would be more
distorted in the lower reaches of the drainage area than in the
upper reaches.
A similar feature in the vicinity of the Alafia River also
reflects the low pressure in the aquifer resulting from discharge
by springs. On the flank of the re-entrant along the Hillsborough
River is a cone of depression surrounding Sulphur Springs and
many nearby springs. The contours shown depict the water level
in the Avon Park limestone in the immediate vicinity of Sulphur
Springs. Water levels in wells in the Tampa and Suwannee lime-
stones are considerably more depressed in the area than those in
wells in the Avon Park limestone because of higher discharge
through the extensive cavity system that has been developed in
the upper formations and of the retarding effect of the less
permeable limestones of the Ocala group.
The shape of the piezometric surface in the northwestern part
of the county is shown in detail in the vicinity of the St. Peters-
burg well field (fig. 49). The sharp re-entrant in the piezometric
surface near the well field may reflect drawdown caused by with-
drawal of water from the area but that drawdown may be
superimposed on a re-entrant in the surface similar to the some-
what less pronounced re-entrant to the southwest. The piezometric
ridge between these two re-entrants may be the result of recharge
from the lakes, but its continuity into the discharge area to the






FLORIDA GEOLOGICAL SURVEY


southeast indicates that it probably is controlled by a major pre-
Mesozoic fault shown by Vernon (1951, fig. 11). Recharge probably
is a factor in the determination of the shape of the surface. The
existence of an impermeable zone along the fault may be responsible
for the steep gradient on the south side of the pumping field. Ad-
ditional data are necessary for a more definite resolution.

USE

Ground-water pumpage in Hillsborough County is estimated to
average 67 million gallons a day. More water is used during the
winter than during the summer because of the increase in irriga-
tion in the usually dry winter and because of the influx of tourists
and the consequent increase in domestic and commercial use. Public
water systems for part of Tampa, for St. Petersburg in Pinellas
County, for Plant City, Temple Terrace, and numerous subdivisions
near Tampa derive their supplies from wells. More than 99 percent
of the water pumped is used for domestic, commercial, and public
building supply. About 0.3 mgd is pumped from wells at former
Drew Field to supplement the surface-water supply of the city of
Tampa. Purity Springs Water Company pumped 1.0 mgd, Hendrick
Estates (commercial) pumped 0.02 mgd, and Florence Villa sub-
division pumped 0.05 mgd. Figures from the city of Tampa indicated
the presence of 1,500 to 1,600 wells in the city. The figures
included 149 commercial wells and 1 industrial well. Individual
wells supply an estimated 4 mgd to rural residents who are not
furnished water by the public water systems.
Industrial cooling and processing water uses are estimated to
be 24 mgd. Cooling water is frequently salty in the area of
industrial development near Tampa Bay. The total pumpage from
wells in this area was estimated to be 60 percent fresh water and
40 percent salty bay and connate water, based on chemical quality.
The bay water enters the aquifer through exposures in the channel
cuts in the bay. It flows toward the wells where the water level
is lower than sea level.
Irrigation of truck crops and citrus groves by ground water
probably exceeds 15 mgd. The exact pumpage and flow from
irrigation wells is almost impossible to determine directly. The
above figure is based on use of 1.4 million gallons of water per acre
per year for truck crops and an average of 100,000 gallons per
acre per year for the estimated 10 percent of the citrus groves
that are irrigated with ground water in the county.






REPORT OF INVESTIGATIONS NO. 25


DRAINAGE WELLS

Drainage wells offer a low cost means of controlling flooding
in ponded areas where conditions are favorable for their use. The
principal problems involved are effectiveness, pollution of water
in the aquifer, and possible property damage from high water
levels. To be effective, the well must remove water from an area
at such a rate that the storage capacity of the pond will not be
exceeded during the heaviest, most prolonged rain that is expected
for the area. The required capacity of drainage wells is inversely
related to pond storage. Rate of runoff into a pond is usually quite
large as compared with the capacity of most wells; therefore,
several wells may be required to drain even a small area.
The drainage capacity of a well is about equal to the specific
capacity of the well. The specific capacity is the rate at which
water can be pumped from a well with a given drawdown. A well
that yields 100 gpm per foot of drawdown will yield about 300 gpm
with 3 feet of drawdown and will accept 300 gpm of drainage water
with a rise in water level of about 3 feet. The stage of the pond
or lake and the piezometric surface fluctuate approximately
simultaneously, but the pond level fluctuates more quickly and with
greater magnitude. This relatively high piezometric surface may
not prevent satisfactory use of drainage wells to remove excess
pond water if the specific capacity of the well is large. The water
level in the pond must be above the piezometric surface in order for
water to flow into the well.
Surface waters may contain bacteria and organic and inorganic
materials that are undesirable or dangerous in drinking water.
If this water is permitted to enter the aquifer through a drainage
well, it may move very quickly to a well that is being used as a
source of drinking water. Knowledge of the detailed hydrology
of the area is necessary for evaluation of the effect.of such drainage
on other supplies. However, because the expense of such studies
may be prohibitive, a general rule-of-thumb procedure is commonly
used. If the well is cased to a salt-water bearing zone, the risk of
pollution is slight. Such procedure is not generally practical
because the top of the salt-water zone may be at a depth of several
thousand feet in the eastern part of the county. If water of a
given quality is drained into a zone of the aquifer that is not used
for purposes that are affected by that quality, then the drainage
water may be harmless. In areas where salt water is at shallow
depths, such recharge may be desirable in that it will eventually
push the fresh-salt contact to greater depth.






FLORIDA GEOLOGICAL SURVEY


In some areas, as near Sulphur Springs, an artificially induced
rise in water levels that are already high may result in considerable
damage to some properties. In the natural condition, Sulphur
Springs drew down the water levels in the surrounding area so
that several former spring basins no longer flowed. When the water
level in the spring was raised by construction of a concrete wall,
several of these former springs resumed flow. They were diverted
to the river through drains, or they were filled or diked to prevent
flow. Several of these former springs, both evident and buried
under fill, might flow if substantial drainage is disposed of
through wells in the area.

WELL EXPLORATION STUDIES

The results of surveys of velocity, temperature, and chemical
quality in three wells are shown in figure 50.
The velocity of the water, concentrations of chloride and sulfate,
and the specific conductance are shown for various depths in well
802-225-2. The well is in the industrial park about 3 miles north-
east of Sulphur Springs. When the well is pumped at 200 gpm,
the principal producing zones appear to be a cavity at about 660
feet and a permeable zone from 440 to 540 feet.


Figure 50. Well exploration data.






REPORT OF INVESTIGATIONS No. 25


Velocity and temperature of water are shown for various
depths in well 801-227-3, about 1 mile north of Sulphur Springs.
Essentially all of the water pumped (about 150 gpm) came
from a cavity at the bottom of the well. The temperature of this
water was about 850 F. The normal temperature. of ground water
in the upper zones of the aquifer is about 750 F.
Waters in the principal producing zones, as well as the several
minor producing zones, vary in both concentrations and propor-
tions of dissolved materials. Some of the zones contain very
highly mineralized water. Thus the zone immediately below the
casing yields but a small percentage of the water pumped but
the concentration of sulfate increases by 1,000 ppm in that zone.
The lower temperature in the upper 65 feet probably is caused by
the flow of cooler water around the casing in the upper zones.
Well 752-207-1, about 1 mile southwest of Keysville, derived
most of its flow from a cavity at the bottom of the well. The
temperature remained almost constant with depth.

QUANTITATIVE STUDIES

The ability of an aquifer to transmit and store water is ex-
pressed in terms of coefficients that are derived from pump test
data.
The coefficient of transmissibility (T) is defined by Theis
(1938, p. 894) as the number of gallons of water at the prevailing
water temperature that will move in 1 day through a vertical
strip of the aquifer 1 foot wide normal to a unit hydraulic
gradient. The coefficient of storage (S) is the volume of water
released or taken into storage per unit surface area of the aquifer
per unit change in head normal to the aquifer surface.
In the conventional units of the U. S. Geological Survey, T is
in gallons per day per foot and S is in gallons per square foot per
foot.
An index of the leakage between aquifers is the coefficient of
leakance (P'/m'). It is expressed in units of gallons per day per
square foot, under a unit gradient divided by the thickness of the
confining bed or beds, in feet.
Theis (Wenzel, 1942) developed a method of determining T
and S from time-drawdown data in observation wells in the vicinity
of a pumped well. Theis assumed that the confining beds are
impermeable. In natural systems, this condition does not obtain,
and the Theis equation permits only an approximation of the true
values, depending on the amount of leakage through the confining






FLORIDA GEOLOGICAL SURVEY


beds. Hantush (1956) developed a solution introducing corrections
for this leakance-an equation which allows the coefficient of leak-
ance to be determined as well as the coefficients of transmissibility
and storage. The method of determining coefficients from the
Hantush equation is similar to that described by Theis (Wenzel,
1942). The field data consist of measurements of quantity of
water pumped, distance between pumped well and observation well,
and water levels in all wells with times of measurements. The
data are reduced to logarithmic graphs with time (t) in days since
pumping began divided by the square of the distance (r) from
pumped well to observation well (t/r2) as the abscissa, and draw-
down (s) in feet as the ordinate. Each water-level measurement is
made at an approximate time so that the points on the graph
allow construction of a smooth curve. The resulting curve is then
compared with a family of leaky aquifer type curves developed
by H. H. Cooper, Jr., of the U. S. Geological Survey. This family of
curves is based upon the equation for nonsteady flow in an infinite
leaky aquifer developed by Hantush and Jacob (1955, p. 95-100)
and described by Hantush (1956, p. 702-714). The values of a
chosen match point, when substituted in the proper equation, give
values for the three coefficients, T, S, and P'm'.
Pumping tests in three areas in Hillsborough County have been
conducted by the U. S. Geological Survey to determine these
coefficients.
In 1942, test pumping at Hookers Point in Tampa was conducted
as part of a study to determine the feasibility of construction
of "wet" ship construction -basins to about 17 feet below mean
low water. Only one of the many wells penetrated the Tampa
limestone. Data from this well yielded a T of 75,000. Data from
wells penetrating only a thin bed of limestone at about 32 feet
below mean sea level indicated values for T ranging from 7,000
to 16,000 and values for S ranging from 0.00014 to 0.00077. The
erratic results reflect the extremely variable nature of the for-
mations tested.
In 1955 a test was made about half a mile east of Sun City. The
flowing well (740-227-6) and the observation well (740-227-7)
used for this test penetrate essentially the entire thickness of
the Tampa and Suwannee limestones. The values for T and S, as
determined by Peek (1959, p. 54) are 114,600 and 0.0006, re-
spectively.
In 1957, the city of Tampa initiated the testing of a potential
well field site 6 miles west of Plant City. The tests were conducted
jointly by the U. S. Geological Survey and the consultants for







REPORT OF INVESTIGATIONS NO. 25


801-


801-213-




pe_


S801-214-2
--5>-


801-213-10 l



z


Figure 51. Tampa well-field site.


the city of Tampa, Robert and Company, Associates, of Atlanta,
Georgia. The plan of the test site (fig. 51) shows the location of
the 10 wells used in the tests and a number of selected off-site wells.
The well construction data and test data are shown in table 4.
Several of the wells were deepened after each test to allow testing
of deeper zones of the aquifer.
The following table shows the elevation above sea level of the
tops of formations penetrated by test wells:
Wells 801-213-11 and 15, only 25 feet apart, penetrated the top


0 400 800 1. 200 feet


II


-I


_ I I I


802-213-3 1
SSTAFFORD RD.


S802-213-2








213-6 801-213-7,8::


801-213-23 801-213-21
801-213-1-9,:
-12 801-213-17. 802111 8-213-16
801-213-13 1 8




SE corner sec 20
T 28 S R 21 E.I :SPARKMAN LRD.
801-213-9






FLORIDA GEOLOGICAL SURVEY


TABLE 5. Elevation Above Sea Level of Formational Tops Penetrated
by Test Wells

Elevation of top of
Tampa Suwannee Ocala I Avon Park
Well limestone limestone group limestone

801-213-11 +12 11 -296
802-213-4 +17 85 -321 -418
-13 6 76 -
-15 +20 20 -183
-16 +i22 31
-19 none 12 -152
-20 + 9 31 -218
-21 3 -115
-22 +25 35 -211 -412
-23 +12



of the Ocala group at -321 and -183 feet, respectively, a difference
of 138 feet. Well 801-213-23 bottomed in the Tampa limestone at
-186 feet and 801-213-17 had not entered rock at -240 feet. The
sand in this well (801-213-17) probably fills a vertical solution
opening. Aerial photographs, in color, of the well field show a
number of circular areas similar to that surrounding 801-213-17
within the limits of the test site. It is believed that these areas
should be avoided in future drilling for water.
The geologic anomalies indicated in table 5 are the result of
collapse following weakening of the rock in places by solution of
limestone. The occurrence of solution features in such abundance
may well be associated with faulting. The top of the Avon Park
limestone is about the same elevation in the two wells on the site
that penetrate it but more data are necessary if faulting is to be
defined in the area.
Data from four of the six pumping tests were analyzed to ob-
tain values for T, S, and P'/m'. Maximum, minimum, and "best
fit" values were computed for each of the coefficients. These were
used to obtain adjusted values.
For the first test, well 801-213-15 was pumped at 811
gpm for 400 minutes. Data from observation wells 801-
213-11, -15, -19, and -20 were analyzed. Best values for the
coefficients were determined to be T=-35,000, S=0.00005, and
1P m'.=0.03. The section tested was from the top of the limestone
to a depth of about 250 feet. Well 801-213-11 was 560 feet deep

























































i






1/


:i
i'






I

i

i









TABLE 4. Well Construction and Test Data, Tampa Well-Field Site

USGS No. 802-213-4 801-213-13 801-213-11 801-213-16 801-213-20 801-213-19 801-213-23 801-213-21 801-213-15 801-213-22
Tampa No. 1 2 3 4 5 6 7 8 A B
Test Depth Csg.' Depth Csg. Depth Csg. Depth Csg. Depth Csg. Depth Csg. Depth Csg. Depth Csg. Depth Csg. Depth Csg.

1 210 78 269 64 560 74 250 50 250 39 125 78 227 67.6
2 210 78 269 64 560 74 250 50 400 39 225 78 413 67.6
3 450 208 345 64 560 74 250 50 400 39 400 78 256 78 256 92 413 67.6 420 72
4 450 208 345 64 560 74 250 50 400 39 400 78 256 78 256 92 413 67.6 420 72
5 450 208 379 64 750 74 250 50 400 39 400 78 256 78 256 92 413 67.6 800 72
6 450 208 379 64 750 74 250 50 400 39 400 78 256 78 256 92 413 67.6 800 72


Time (1957


Pumped well


Test No.


Start


End


Duration of q-2
test (mins.) (gpm)


USGS No. 801-213-15
Tampa No. A
801-213-15
A
801-213-22
B
801-213-22


801-213-15
A
801-213-22
B
801-213-22
B


1 9:00 a.m. 4-3

2 9:00 a.m. 4-12

3 10:03 a.m. 5-6

4 8:01 a.m. 5-10



5 3:15 p.m. 7-22

6 1:10 p.m. 7-26


3:40 p.m. 4-3

6:00 p.m. 4-12

6:01 p.m. 5-7

8:08 a.m. 5-11



3:20 p.m. 7-23

4:10 p.m. 7-30


400


540 2,200


1,920

1,440



1,440

7380


1,520

1,400

2,820

1,500

3,800


'Csg-Depth of casing
2q-Pumping rate









REPORT OF INVESTIGATIONS NO. 25


but the water level did not differ materially from the other wells
in response to pumping. An excellent hydraulic connection between
801-213-11 and 801-213-15 was noted during drilling.
After the first test, wells 801-213-15, -19, and -20 were deepened.
Test 2 consisted of pumping 801-213-15 for 540 minutes at 2,200
gpm. Data from wells 801-213-11, -19, and -20 were analyzed. The
values for the coefficients were found to be T=100,000, S=0.003,
and P'/m'=0.02. The section tested was from the top of limestone
to a depth of about 410 feet.
After the second test, wells 801-213-21, -22, and -23 were
drilled and 801-213-13 and -19 were deepened. Well 802-213-4
was deepened and subcased to 208 feet.
For test 3, well 801-213-22 was pumped for 1,920 minutes at
1,520 gpm. Data from observation wells 801-213-11, -19, 20, -23,
and 802-213-4 were analyzed. Best values of the coefficients were
T=50,000, S=-0.0007, and P'/m' =0.001. The section tested was
essentially the same as for the second test. Two short tests were
then run, but the data were not analyzed.
Wells 801-213-11, -13, and -22 were then deepened and the last
test was run, with 801-213-22 pumping 3,800 gpm for 7,380
minutes. Data from wells 801-213-11, -15, -16, -19, -20, -21, and
-23 were analyzed. Best values of the coefficients were determined
to be T=220,000, S=0.002, and P'/m' was 0.002. The section
tested was from the top of limestone to a depth of about 800 feet.
Continuous rain throughout most of the test did not appear to
affect the data.
Adjusted values of the coefficients for each test are summarized
in table 6.
The order of magnitude of the values of T in table 6 increases
with depth as does the specific capacity of the wells. This indicates
that the aquifer is layered. The principal water-bearing zones
are separated by zones of lower permeability. The coefficient of

TABLE 6. Adjusted Values of T, S, and P'/m' for Pumping Test at the Site of
the City of Tampa Well Field.

Open
Pumped Deuth hole
Test T S P'. m' well (ft.) (ft.)
1 35,000 .00005 0.03 801-213-15 227 159
2 100,000 .0003 .02 801-213-15 413 345
3 50,000 .0007 .001 801-213-22 420 348
6 220,000 .002 .002 801-213-22 800 728







FLORIDA GEOLOGICAL SURVEY


leakance (P'/m') computed for the test in which the pumped and
observed wells were deep is much lower than that for the test
using relatively shallow wells. This indicates that a smaller per-
centage of the pumped water was derived from leakage in the
deeper test. It is possible that the coefficient of leakance reflects
leakage into the upper part of the section with resultant distortion
of the observed rate of decline of water levels in the wells that
penetrate the entire section. If a well were cased to about 350 feet,
lessening direct lowering of head in the upper zones of the aquifer,
the area immediately adjacent to the well field might not be de-
watered as much as if the wells were cased only to the first sub-
stantial rock.
Figure 52 is a semilog plot of the profile of the cone of draw-
down around a pumped well at the site of the city of Tampa well
field. Scale units are given for a pumping rate of 1,000 gpm. The
value of "S" for any pumping rate is computed by multiplying the
value for "S" (drawdown in feet) at 1,000 gpm by the ratio of
the new pumping rate to 1,000 gpm. The shape of the cone of
drawdown will remain constant for a given rate of pumping after
equilibrium has obtained, but will be shifted horizontally to a











3
o



1,000
(r)
Distance,in feet from pumped well


Figure 52. Drawdown in vicinity of a well after pumping 60 days
or more at 1,000 gpm.






REPORT OF INVESTIGATIONS No. 25


distance from the pumped well such that the drawdown will be
proportional to the pumpage rate as the drawndown on the curve
is to 1,000 gpm. If the sands and clays above the aquifer are
dewatered, the water level will decline, following the type curve
computed by Theis. The transmissibility will remain essentially
constant but the storage coefficient will approximate 0.2.
The drawdown was greater than calculated in the early part
of each test. This indicates that water is not being released from
storage immediately when water levels are lowered. The large
amount of sand in the limestone formations yields water slowly
in comparison to the cavities in the limestone through which the
water is transmitted to the well. Because the storage coefficient
is larger and transmissibility smaller for the cavity fill than for
the limestone, the cavity fill will yield water at a slower rate and
for a longer time than the cavity proper. This slow yielding of
water may distort the observed data to such an extent that only a
long period of testing will allow accurate determination of the
aquifer constants.

QUALITY

With the exception of the Ruskin area, certain areas in and
near Tampa, and coastal areas, the water in underground forma-
tions generally contains less than 500 ppm dissolved materials.
The dissolved materials in water from shallow zones of the aquifer
generally range from 50 to 500 ppm with a nonuniform tendency
toward increasing concentrations of dissolved materials with in-
creasing depth. This is partially indicated by analysis of water
from test well 801-213-15 near Plant City. (See separate data
report.)
The average dissolved materials in most ground waters in
Hillsborough County, calculated from 78 samples analyzed, was
about 240 ppm. Water has been obtained from a depth of 1,489 feet
3 miles east of Wimauma that contained less dissolved materials
than this average.
Dissolved materials in ground water indicate that the Gyben-
Herzberg principle is reasonably applicable and may be used in the
development of ground water in areas having artesian pressures
great enough to cause water to rise in wells to an elevation of 30
feet, or more, above sea level. As the maximum safe depth, as
computed from the Gyben-Herzberg principle, is approached, there
is increasing danger that the water will contain higher concentra-
tions of dissolved materials. Greater rates of pumping will result






FLORIDA GEOLOGICAL SURVEY


in higher concentrations of dissolved materials. It is expected that
the concentrations of dissolved materials will increase sharply at
about the calculated safe depth.
The dissolved materials in water in the underground formations,
with the exception of the above mentioned areas, are mainly
calcium, magnesium, and bicarbonate. Together, these constituents
average about 76 percent of the dissolved materials but may be as
much as 98 percent. Small amounts of sulfate, chloride, and sodium
are present.
In the Ruskin area during wet periods, when the area is not
irrigated, concentration of the dissolved materials is about 500
ppm. Concentrations of sulfate and alkalinity as carbonate are
about equal. During dry periods when the area is extensively irri-
gated, the concentrations of dissolved materials in the water
increase to 1,840 ppm or more. During this same period, the
chemical character of the dissolved materials changes with in-
creased pumping. The concentrations of sulfate and calcium (and
magnesium by a lesser amount) increase and the alkalinity as
carbonate decreases by a nearly proportionate amount. The
materials average about 43 percent sulfate and may be as much
as 50 percent. Because of the increase in calcium and sulfate, the
noncarbonate hardness often nearly equals the carbonate hardness
at higher concentrations of dissolved materials. In the Ruskin
area during periods of heavier pumping for irrigation, sulfate
concentration has been as high as 821 ppm; at the same time
chloride and sodium content has increased less rapidly to 270 and
105 ppm, respectively. These are only the maximum concentrations
observed and do not necessarily represent maximum concentrations
that could occur.
The concentrations and chemical character of the dissolved ma-
terials in the water vary widely in certain areas in the vicinity
of Tampa and near the coast (except in the Ruskin area). There-
fore average would be meaningless. The concentrations of dissolved
materials vary nonuniformly with location and depth. Concentra-
tions ranged from about 170 ppm to about 11,000 ppm, and the
depths of wells ranged from about 145 to more than 2,000 feet. The
higher concentrations of dissolved materials range from 14 to 50
percent chloride, 6 to 30 percent calcium plus magnesium plus
alkalinity (as carbonate), 6 to 26 percent sodium, and 6 to 47
percent sulfate.
Seasonal variations in water levels cause the concentrations of
dissolved materials to fluctuate in zones of aquifers that are
affected by salt-water intrusion. The position of the fresh-salt






REPORT OF INVESTIGATIONS No. 25


water interface is dependent on the elevation of the piezometric
surface, and rise and fall of water levels cause a rise and fall of
the interface between fresh water and salt water. Large fluctua-
tions in water level cause the zone of diffusion at the interface to
be wide. Water from wells penetrating the upper part of the zone
of diffusion may have only slightly higher concentrations on initial
development but would increase in concentration rapidly during
heavy pumping. Drilling of wells to depths that approach the
interface should be avoided.
Except for some locations in the vicinity of Tampa and the
coast, including the Ruskin area that is already heavily pumped,
most ground waters would be suitable for municipal use. Sodium,
chloride, and sulfate probably will exceed the maximum concen-
tration recommended by the U. S. Public Health Service after
heavy pumping of these areas. The upward movement of water con-
taining highly concentrated dissolved materials probably will be
indicated by more rapidly increasing concentrations of calcium and
sulfate than of the other dissolved materials. Further pumping
probably will result in increasing concentrations of sodium and
chloride. If the concentrations of dissolved materials are observed
periodically, the optimum development of the water resource may
be attained and acceptable quality of water maintained. The
availability of water having the desired quality is one of the first
considerations for industrial use. Supplies containing low concen-
trations of dissolved materials cannot be developed in the vicinity
of Tampa, along the coast, or in the Ruskin area.



REFERENCES

Applin, Paul L.
1951 Preliminary report on buried pre-Mesozoic rocks in Florida and
adjacent states: U. S. Geol. Survey Circ. 91.
Black, A. P.
1953 (and Brown, Eugene, Pearce, J. M.) Salt water intrusion in
Florida-1953: State Board of Conservation. Water Survey and
Research Paper No. 9.
Brown, Eugene (see Black, A. P.)
Corps of Engineers, U. S. Army
1956 Hurricanes affecting the Florida coast: Jacksonville District
Appraisal Rept.
Ferguson, G. E. (see Parker, G. G.)






FLORIDA GEOLOGICAL SURVEY


Florida State Board of Health
1950-53 Peace and Alafia rivers, stream sanitation studies: v. 1, the
Alafia River; v. 2, the Peace River; and supp. 2 to v. 1 and 2,
A biological survey of the Peace River, Florida; Addendum No.
1 and 2 to fluoride; Summary of Peace and Alafia rivers, Aug.
15, 1955, to May 15, 1956: Jacksonville, Florida.
Hantush, M. C.
1955 (and Jacob, C. E.) Nonsteady radial flow in an infinite leaky
aquifer: Am. Geophys. Union Trans., v. 36, no. 1, p. 95-100.
1956 Analysis of data from pumping tests in leaky aquifers: Am.
Geophys. Union Trans., v. 37, p. 702-714.
Jacob, C. E. (see Hantush, M. C.)
Kohler, M. A.
1954 Water-loss investigation, Lake Hefner studies, technical report:
U. S. Geol. Survey Prof. Paper 269.

Love, S. K. (see Parker, G. G.)

Matson, G. C.
1913 (and Sanford, Samuel) Geology and ground waters of Florida:
U. S. Survey Water-Supply Paper 319.
Parker, G. G.
1955 (and Ferguson, G. E., Love, S. K., and others) Water resources
of southeastern Florida: U. S. Geol. Survey Water-Supply Paper
1255.


Pearce, J. M. (see Black, A. P.)


Peek, H. M.
1959


Puri, H. S.
1957


The artesian water of the Ruskin area of Hillsborough County,
Florida: Florida Geol. Survey Rept. Inv. No. 21.


Stratigraphy and zonation of the Ocala group: Florida Geol.
Survey Bull. 38.


Rainwater, F. H.
1960 (and Thatcher, L. L.) Methods of collection and analyses of
water samples: U. S. Geol. Survey Water-Supply Paper 1454.

Sanford, Samuel (see Matson, G. C.)

Stringfield, V. T.
1936 Artesian water in the Florida peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C.

Thatcher, L. L. (see Rainwater, F. H.)
Theis, C. V.
1938 Ground water in south-central Tennessee: U. S. Geol. Survey
Water-Supply Paper 677.






REPORT OF INVESTIGATIONS NO. 25


U. S. Bureau of the Census
1956 County and city data book: U. S. Government Printing Office,
Washington D. C., p. 42-46.

Vernon, R. O.
1951 Geology of Citrus and Levy counties, Florida: Florida Geol.
Survey Bull. 33.

Wenzel, L. K.
1942 Methods of determining permeability of water-bearing materials,
with special reference to discharging-well methods: U. S. Geol.
Survey Water-Supply Paper 887.


APPENDIX


HILLSBOROUGH COUNTY
FLORIDA'


-, 2*5 o


Zt*T? 30"


7r 30 00o

Figure 53. Topographic map coverage of Hillsborough County.







FLORIDA GEOLOGICAL SURVEY


ULNITJ S OTT PE'R'W -F THE INTERIOR
LZEOI 3MC1 c;IIPF


FLORIDA GEOLOGICAL SURVEY
An M[km-r


3m :oM l ;eosca CONTOUR INTERVAL 20 FEET
S, Woo.OW orn TLrnMpTh C*mWOu AT 0 IMET


Figure 55. Topography of Hillsborough County.


100


I_______ __ ____~____











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UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY


FLORIDA GEOLOGICAL SURVEY
R.O.Vernon. Director.


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Well inventory by W. S. Wetterholl


Base compiled from U.S"'Geological
Survey topographicc quudrongles.


Figure 54. Location of inventoried wells.


! RI7


EXPLANATION

Well and well number
Well and well number


_ __ I __


'A:


- -_ II--- ---


, .


-- -







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_____CI__ ___YUI^_







REPORT OF INVESTIGATIONS No. 25 101
















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Figure 56. Explanation of well numbering system.




Water resources of Hillsborough County, Fla. ( FGS: Report of investigations 25 )
CITATION SEARCH THUMBNAILS DOWNLOADS PDF VIEWER PAGE IMAGE ZOOMABLE
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 Material Information
Title: Water resources of Hillsborough County, Fla. ( FGS: Report of investigations 25 )
Series Title: ( FGS: Report of investigations 25 )
Physical Description: 101 p. : illus. ;
Language: English
Creator: Menke, C. G
Florida -- Division of Geology
Publisher: s.n.
Place of Publication: Tallahassee
Publication Date: 1961
 Subjects
Subjects / Keywords: Groundwater -- Florida -- Hillsborough County   ( lcsh )
Water-supply -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by C. G. Menke, E. W. Meredith and W. S. Wetterhall. Prep. by the U.S. Geol. Survey in co-op, with Florida Geol. Survey and the City of Tampa.
Bibliography: Bibliography
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Table of Contents
    Front Cover
        Page i
    Florida State Board of Conservation
        Page ii
    Transmittal letter
        Page iii
        Page iv
    Preface
        Page v
    Contents
        Page vi
        Page vii
        Page viii
        Page ix
        Page x
    Abstract
        Page 1
        Page 2
        Page 3
    Introduction
        Page 4
        Page 3
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Hydrology
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        61a
        Page 17
    Water problems
        17a
        Page 18
        Page 19
        Page 17
    Surface water
        Page 20
        Page 21
        Page 19
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
    Ground water
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 84
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
        92a
        Page 93
        Page 94
        Page 95
        Page 96
        Page 97
        Page 70
    References
        Page 98
        Page 99
        Page 97
    Topography
        Page 100
    Well location
        Page 102
    Explanation of well numbering system
        Page 101
        Copyright
            Copyright
Full Text



STATE OF FLORIDA
STATE BOARD OF CONSERVATION



FLORIDA GEOLOGICAL SURVEY
Robert 0. Vernon, Director






REPORT OF INVESTIGATIONS NO. 25


WATER RESOURCES
COUNTY,


OF HILLSBOROUGH
FLORIDA


By
C. G. Menke, E. W. Meredith, and W. S. Wetterhall

U. S. Geological Survey









Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY,
HILLSBOROUGH COUNTY
and the
CITY OF TAMPA


TALLAHASSEE, FLORIDA
1961









AGRi-
FLORIDA STATE BOARD houti

OF LIBRAfY

CONSERVATION


FARRIS BRYANT
Governor


TOM ADAMS
Secretary of State



J. EDWIN LARSON
Treasurer



THOMAS D. BAILEY
Superintendent of Public Instruction


RICHARD ERVIN
Attorney General



RAY E. GREEN
Comptroller



DOYLE CONNER
Commissioner of Agriculture


ROBERT O. VERNON
State Geologist and Administrator
Oil and Gas Division






LETTER OF TRANSMITTAL


Jlorida ceoloqical Survey
Callakassee

July 6, 1961

Honorable Farris Bryant, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Bryant:

The principal responsibility for preparing water resource data
in Florida rests with the Florida Geological Survey. To the extent
that the development of these data merges with the interests
of the Nation, the U. S. Geological Survey likewise has responsi-
bilities in Florida. The Florida Geological Survey was given funds
to undertake a study in Hillsborough County and this department
has merged its interests with those of the County Commissioners
of Hillsborough County, of the city of Tampa, and of the U. S.
Geological Survey, and we are pleased to publish, as Report of
Investigations No. 25, a comprehensive study of the water resources
of Hillsborough County, which was prepared by C. G. Menke, E.
W. Meredith, and W. S. Wetterhall, of the U. S. Geological Survey.
The details on the water resources have been combined with
general knowledge on the geology and hydrology developed by
the Florida Geological Survey over a period of years and will be
helpful in the future development of the culture of this county.

Respectfully yours,
Robert 0. Vernon, Director




















































Completed manuscript received
April 14, 1961
Published by the Florida Geological Survey
E. 0. Painter Printing Company
DeLand, Florida

iv








PREFACE


This report was prepared by the U. S. Geological Survey, Water
Resources Division, under the direction of J. W. Geurin, district
-hemist, Branch of Quality of Water; A. 0. Patterson, district
engineer, Branch of Surface Water, and M. I. Rorabaugh, district
engineer, Branch of Ground Water. Preparation costs were borne
by the U. S. Geological Survey, the Florida Geological Survey, Hills-
borough County, and the city of Tampa. The cost of publication
was borne by the Florida Geological Survey. Funds for the collec-
tion of data were supplied by the U. S. Geological Survey, the
Florida Geological Survey, the Florida State Road Department,
Trustees of the Internal Improvement Fund, Hillsborough County,
and the city of Tampa.





CONTENTS

Pag,
Preface .... v
Abstract __-___-
Introduction .____----------------------...........- ---. 3
Purpose and scope 3
Acknowledgments ---------------.-.. 4
Previous and present studies --.-.- --.---.------------ -- 4
Sources of additional information ----. ----------. ------------- 7
Methods of investigation---------- 8
Description of area ------ --- 9
' Hydrology of Hillsborough County --..--..----------- --.-- --- --- 12
Rainfall .-. ..--. ..-.- .- -12
Evapotranspiration __....-----------.... ----------- --__---______12
Surface flow ------------_--------.14
Underground flow ------ ------------ 15
Geology --------------.---------- 16
Water problems ------------- -----... .-------..-__. ._____ ______-_17
Surface water--- ---------------------- --19
Use ---------------------------------- 21
Anclote River basin -----------------------------_---.------ ----- 21
Anclote River ----------- _21
Brooker Creek basin ----------------------------- --____--21
Brooker Creek ------- --- 21
Keystone Lake --------- ---- 22
Church and Echo lakes --.22
Rocky Creek basin ------------------------24
Rocky Creek ---- -- --------------------- 24
Brushy Creek -.---------------.----------24
Sweetwater Creek basin --------- ---- --------- 25
Sweetwater Creek ---____-------------- _-------------25
Lake Magdalene ---------------------26
Bay Lake -...---------. -----------26
Lake Ellen ------- ---------------26
Carroll Lake ---------------------------- -- 28
Hillsborough River basin .-- ------ ---- -- -- 28
Hillsborough River ------- -.---------- 28
Blackwater Creek ------ ------------------- 36
Flint Creek -...--.- ---- -.----------- 36
Lake Thonotosassa ----------- .----. .....------ 38
Baker Creek -------------------- 38
Pemberton Creek -----------------..------- 38
Cypress Creek 40
Keene Lake _40
Hanna Lake ___ --- --- 40
Lake Stemper 41
Sulphur Springs ___- --41
Blue Sink 44
Drainage Ditch 44





Lake Hobbs .....-- ....----.---- -.-.------- -------44
Cooper Lake ------------- ---- ----------------44
Hutchins Lake ------------- ----------- --------45
Platt Lake -------------------45
Palm River basin 45
Palm River ------ ------------ -----------45
Sixmile Creek -------------------46
/Alafia River basin- _--._.. .------------------------------- 49
Alafia River -------.---- ---------- ------------49
North Prong Alafia River ---.--- ------------------. .-- 57
South Prong Alafia River ---------- ---------- ------- 59
Turkey Creek --- -----------------------59
Fishhawk Creek -------------------------- ------ 59
Other Streams _---.------ _____- ---59
Lithia Springs ------ --------------------------- 59
Buckhorn Spring ---------_.. .--- --__ ----------------__ ----_____ 60
Bullfrog Creek basin --------------------------60
Bullfrog Creek ------------------------60
Little Bullfrog Creek -- ---------------------- ---- 62
Little Manatee River basin ---------- ---- ---------62
Little Manatee River- ---------------------62
Howard Prairie Branch -------------------- 69
Pierce Branch ------------- ----------69
Carlton Branch ----- ------------------------------------69
South Fork Little Manatee River ---------------70
Other streams ..------ ----- --------- ------------------ 70
Peace River basin ---------------- --- -- 70
Ground Water --------.------------------ .- 70
Water-table aquifer ------------------------- ----- 71
Shallow artesian aquifer -------------------- ------- 71
Principal artesian aquifer --------- -------- 72
Recharge to underground formations ---- ---- ------- 76
Discharge from underground formations --- ---------- 77
Water level -------------- .------- ---- 82
Use ---------.-------- -.- 86
Drainage wells -._--.---- ----.- -- ---- 87
Well exploration studies ------------------- 88
Quantitative studies -------- -------------- 89
Quality ------------- --.-- ---------- -- 95
References --- ------- -----------. 97
Appendix -------------------------.--- --.-- 99
Topographic map coverage of Hillsborough County ------- 99
Location of inventoried wells ------- ------- Facing 100
Topography of Hillsborough County --- ----- -----100
Explanation of well numbering system ---- -------- ---- 101








vii






ILLUSTRATIONS


Figure Page

1 Periods of record for observation wells, 1956-58 4
2 Periods of record at streamflow gaging stations -------- -- 5
3 Periods of record at lake stage stations 6
4 Location of Hillsborough County, Florida 10
5 Mean, maximum, and minimum monthly rainfall at Tampa, Florida,
1840-1958. ____--- --_ ___---- 13
6 Geologic cross sections through Hillsborough County, Florida Facing 18
7 Surface-water features, location of gaging stations, and water
sampling sites --.-- --- --- 20
8 Stage of Church and Echo lakes, 1957-59 --- ------ 23
9 Stage-duration curves of some lakes in Hillsborough County 27
10 Flow-duration curve of Hillsborough River near Zephyrhills -- 29
11 Mineral content and water temperature in Hillsborough River at
Hillsborough River State Park --- --.-. --- 30
12 Percent of days specific conductance was equal to or less than a
given value, Hillsborough River at Hillsborough River State Park 31
13 Color in relation to rainfall and flow of the Hillsborough River at
Hillsborough River State Park (September 1956 to October 1957)-- 32
14 Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (September 1956 to
October 1957) --_-----__- -.._... ._. 33
15 Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (October 1957 to
October 1958) _---_ -__-_---.-__ 34
16 Dissolved materials in relation to flow, Hillsborough River at Hills-
borough River State Park (September 1956 to September 1957) 34
17 Chemical character of dissolved materials of Hillsborough River
at Tampa (September 1956 to August 1957) _------ -- ---- 35
18 Chemical character of dissolved materials of Hillsborough River
at Tampa (October 1957 to October 1958) 36
19 Mineral content in relation to flow, Flint Creek near Thonotosassa 37
20 Stage of Lake Thonotosassa ---.-- 39
21 Relationship of chloride, sulfate, and specific conductance to stage
in Sulphur Springs (800-227-B) 42
22 Dissolved materials of Sulphur Springs in relation to flow and to
stage 43
23 Profiles of streams in the Palm River basin 46
24 Dissolved materials in relation to flow, Sixmile Creek at Tampa
(September 1956 to September 1958) .48
25 Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (September 1956 to August 1957) 49
26 Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (October 1957 to September 1958) _- ...__ 50


viii







27 Profiles of streams in the Alafia River basin 51
28 Flow-duration curve of Alafia River at Lithia 52
29 Mineral content and water temperature in Alafia River at Lithia
(October 1957 to September 1958) 53
30 Percent of days specific conductance was equal to or less than a
given value, Alafia River at Lithia 54
31 Percent of days sulfate concentration was equal to or less than a
given value, Alafia River at Lithia --...... .......... ..... 55
32 Percent of days phosphate concentration was equal to or less than
a given value, Alafia River at Lithia ................ 55
33 Percent of days fluoride concentration was equal to or less than a
given value, Alafia River at Lithia -- 56
34 Percent of days pH was equal to or less than a given value, Alafia
River at Lithia .. .....-----------------------..... ..---------------.....................--- 56
35 Chemical character of dissolved materials carried by the Alafia
River at Lithia (September 1956 to October 1957) 57
36 Chemical character of dissolved materials carried by the Alafia
River at Lithia (October 1957 to September 1958) --- ------ 58
37 Profiles of streams in the Bullfrog Creek basin ----------- ..... 61
38 Profiles of streams in the Little Manatee River basin 63
39 Flow-duration curve of Little Manatee River near Wimauma -.-- 64
40 Mineral content and water temperature in Little Manatee River
near Wimauma (October 1956 to September 1957) 65
41 Percent of days specific conductance was equal to or less than a
given value, Little Manatee River near Wimauma ---------__ 65
42 Color in relation to rainfall and flow of Little Manatee River near
Wimauma (October 1956 to September 1957) 66
43 Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1956 to September 1957) 67
44 Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1957 to October 1958) 68
45 Water levels in selected wells and the precipitation at Tampa and
St. Leo weather stations ___ 77
46 a, b, c, d. Water levels in selected wells 78-81
47 Locations of springs and areas in which water levels in the principal
artesian aquifer were above land surface in September and October
1958 -82
48 Piezometric surface in the principal artesian aquifer (September-
October 1958) ------- -- 83
49 Piezometric surface in northwestern Hillsborough County (No-
vember 21-23, 1957) 84
50 Well exploration data -------------- 88
51 Tampa well-field site __- 91
52 Drawdown in the vicinity of a well after pumping 60 days or more
at 1,000 gpm 94








Table Page
1 Monthly mean evaporation from lakes in Hillsborough County 14
2 Summary of geologic formations from bottom of Oldsmar lime-
stone to the ground surface __- Facing 16
3 Information on selected springs in Hillsborough County -.Facing 82
4 Well construction and test data, Tampa well-field site ..-..-----...Facing 92
5 Elevation above mean sea level of formational tops penetrated
by test wells .- -- --.......---------.--.------- 92
6 Adjusted values of T, S, and P'/m' for pumping test at the site of
the city of Tampa well field --------------- ---------- 93







WATER RESOURCES OF HILLSBOROUGH COUNTY,
FLORIDA
By
C. G. Menke, E. W. Meredith, and W. S. Wetterhall
U. S. Geological Survey

ABSTRACT

Hillsborough County is near the west coast of central Florida
and is comprised of 1,040 square miles of land. The population
was about 400,000 in 1960.
This report is an evaluation of the basic hydrology of the
county and of some of the major factors that affect the available
fresh water supply.
An average of 1,400 mgd (million gallons per day) of fresh
water is potentially available in the county-1,000 mgd of surface
water and 400 mgd of ground water. This is enough to supply
1,250,000 people using 1,100 gpd (gallons per day) per capital, if
all the flood waters could be stored for use.
The fresh water supply is comprised of about 2,500 mgd of
rainfall on the county, of 300 mgd surface-water inflow, and of
100 mgd ground-water inflow to the county. About 1,500 mgd is
returned to the atmosphere by evapotranspiration.
Three rivers, the Hillsborough, Alafia, and Little Manatee
rivers, have an average combined flow of 508 mgd and drain about
70 percent of the county. The average flow of the Hillsborough
River is 173 mgd, of which about 23 mgd is used by the city of
Tampa for its municipal supply. The average flow of the Alafia
River is 220 mgd and of the Little Manatee River is 115 mgd. The
observed minimum flow of the Hillsborough River was 31 mgd,
of the Alafia River was 4.3 mgd, and of the Little Manatee River
was 0.8 mgd. The flow of the Alafia River is used to dispose of
industrial wastes, and the flow of the Little Manatee River is
wasted to the sea.
Water may be obtained from three aquifers. The nonartesian
aquifer, composed of surface sands, yields up to 200 gpm (gallons
per minute) per well. The shallow artesian aquifer, composed of
limestone and sand beds in the Hawthorn formation of Miocene
age, yields up to 500 gpm, and the principle artesian aquifer, com-
posed of limestones of Tertiary age lying below the Hawthorn
formation, yields up to several thousands gpm per well.






FLORIDA GEOLOGICAL SURVEY


The coefficient of transmissibility of the principal artesian
aquifer ranges from about 75,000 to 220,000 gallons per day per
foot, and the coefficient of storage from 0.00005 to 0.002 gallons
per square foot per foot. The coefficient of leakance, in gallons per
day per square foot under a unit gradient divided by the thickness
in feet of the confining beds above and below the aquifer, is 0.002
at the site of the Tampa well field 6 miles west of Plant City.
Most of the 67 mgd of ground water used in the county is
derived from the principal artesian aquifer. Movement in the
aquifer is primarily through the zones of high permeability that
are associated with joints and faults. Locally, these zones behave
as aquifers when they are pumped or recharged at high rates. The
aquifer is recharged through sinkholes and through the sands and
clays that overlie it, and large amounts of water are discharged
from the aquifer to streams in the northern half of the county
and to the bay.
The water level in the nonartesian aquifer is generally within a
few feet of the land surface. Water levels in the shallow artesian
aquifer are erratic really. The piezometric surface of the principal
artesian aquifer is higher than 100 feet in the northeastern part
of the county and generally slopes toward Tampa Bay. Troughs in
the piezometric surface extend inland, indicating that water is
discharged from the aquifer into the Hillsborough and Alafia
rivers.
Dissolved materials of surface waters was generally less than
250 ppm (parts per million) in the county. Notable exceptions
are the Alafia River, with an average dissolved-materials concen-
tration of 292 ppm and a maximum of 658 ppm, and Sulphur
Springs with an average of 500 ppm and a maximum of more than
1,000 ppm. Most of the streams have dissolved materials of less
than 100 ppm but contain colored organic materials leached from
vegetation.
Water in shallow aquifers appears to have less than 100 ppm
dissolved materials in most of the county and may contain organic
color in quantities ordinarily less than those found in streams.
Ground water found between depths of 100 and 200 feet generally
had less than 500 ppm of dissolved materials except in the coastal
areas.
Where the piezometric surface is more than 30 feet above sea
level, ground-water supplies containing less than 500 ppm of dis-
solved materials may be obtained at a depth below sea level not
exceeding 40 times the elevation of the piezometric surface above
sea level. Where the elevation of the piezometric surface is less






REPORT OF INVESTIGATIONS NO. 25


than 30 feet, the concentration of dissolved materials varies
erratically with both depth and location from about 170 to more
than 11,000 ppm. In the Ruskin area, the concentration and char-
acter of dissolved materials changes with the lowering of water
levels.
Variations of rainfall, streamflow, ground-water levels, and
concentrations of dissolved material are given in the report.



INTRODUCTION

PURPOSE AND SCOPE

The purpose of this report is to provide basic information
necessary for optimum development of the water resources of
Hillsborough County and to aid in the solution of some local water
problems.
Quantitative and qualitative aspects of both surface and ground
water are presented in this report. Surface-water interpretations
are based on stage, discharge, and quality data collected in ten
stream basins in the county. Rates of runoff per unit area were
used in estimating flow into the county and into Tampa Bay.
Miscellaneous measurements of stage, discharge, and quality of
water in several lakes, springs, and minor streams supplement
the more intensive data collected at regular gaging sites. Ground-
water information was derived from studies of the geologic forma-
tions, well construction, water level, and pumping-test data.
The several aquifers and the geologic formations comprising
them are described. The water-bearing and water-yielding proper-
ties and the chemical quality of the water from each aquifer are
noted. The fluctuations of water levels in wells are shown, as is
the configuration of the piezometric surface. Hydraulic properties
of the aquifers as determined by analysis of pumping-test data
are given, and a profile of the cone of drawdown near a pumping
well at the proposed site of Tampa's well field is shown and
discussed.
Most of the ground-water and quality-of-water information is
restricted to the period 1956 through 1958 and consequently does
not reflect the wide range of hydrologic conditions known to have
existed in the county.
Both surface-water and ground-water information was used to
estimate a water budget for the county.






FLORIDA GEOLOGICAL SURVEY


ACKNOWLEDGMENTS

The collection of data for this report was substantially aided
by the many citizens and firms who furnished data or services and
who allowed the authors access to wells, streams, and lakes. A
special debt of gratitude is acknowledged to the following well
drillers who contributed data from their files and from their intimate
knowledge of the area: Ben Lovelace and Company, May Artesian
Well Drilling Company, F. A. May and Sons, Morrill Well and
Pump Company, and Mr. Phillip Morrill, retired driller.
Mr. Lyle Dickman furnished data from which use of water for
truck crops was computed.


PREVIOUS AND PRESENT STUDIES

The first documented study of water in Hillsborough County
was made by Matson and Sanford and published in 1913. The


PERIOD OF RECORD
1956 1957 1958
J F(MAMMJ J JASOND J FM|AM J J AS ON)D J|FM AM J J7AS ON D






















No record


.


Figure 1. Periods of record for observation wells, 1956-58.


WELL
NUMBER
742-219-1
744-225-39
747-220-1
751-203-1
751 -207-1
752-207-1
752-220-1
756-215-1
756-227-I
757- 212-1
757- 212-2
757-212-3
757- 221-1
758-207-1
759- 229-2
801- 213-22
801- 227-1
801- 227-3
802- 217-1
802- 225-2
802- 238-1
803- 238-2
804- 207-1
804- 225-1
804- 235-1
805- 237-1
807-230-3
808-234-2
808 -237-5
809-227-1
809-239-1
810-212-1






REPORT OF INVESTIGATIONS NO. 25


than 30 feet, the concentration of dissolved materials varies
erratically with both depth and location from about 170 to more
than 11,000 ppm. In the Ruskin area, the concentration and char-
acter of dissolved materials changes with the lowering of water
levels.
Variations of rainfall, streamflow, ground-water levels, and
concentrations of dissolved material are given in the report.



INTRODUCTION

PURPOSE AND SCOPE

The purpose of this report is to provide basic information
necessary for optimum development of the water resources of
Hillsborough County and to aid in the solution of some local water
problems.
Quantitative and qualitative aspects of both surface and ground
water are presented in this report. Surface-water interpretations
are based on stage, discharge, and quality data collected in ten
stream basins in the county. Rates of runoff per unit area were
used in estimating flow into the county and into Tampa Bay.
Miscellaneous measurements of stage, discharge, and quality of
water in several lakes, springs, and minor streams supplement
the more intensive data collected at regular gaging sites. Ground-
water information was derived from studies of the geologic forma-
tions, well construction, water level, and pumping-test data.
The several aquifers and the geologic formations comprising
them are described. The water-bearing and water-yielding proper-
ties and the chemical quality of the water from each aquifer are
noted. The fluctuations of water levels in wells are shown, as is
the configuration of the piezometric surface. Hydraulic properties
of the aquifers as determined by analysis of pumping-test data
are given, and a profile of the cone of drawdown near a pumping
well at the proposed site of Tampa's well field is shown and
discussed.
Most of the ground-water and quality-of-water information is
restricted to the period 1956 through 1958 and consequently does
not reflect the wide range of hydrologic conditions known to have
existed in the county.
Both surface-water and ground-water information was used to
estimate a water budget for the county.





REPORT OF INVESTIGATIONS NO. 25


report gives information on the source, quality, and development
of ground water, along with lithologic logs and tables of wells and
springs.
A continuing observation well program, to observe ground-water
levels throughout the State, was begun in 1930 and included one
well in Hillsborough County. The water levels in this well and in
two additional wells that were in operation at the beginning of this
project are shown in figure 45. The periods of record for obser-
vation wells are shown in figure 1.
Between 1933 and 1938 streamflow measurement stations were
established on the Alafia, Hillsborough, and Little Manatee rivers.
By 1958, 17 gaging stations were in operation in the county (fig. 2).
The Florida State Board of Health conducted an intensive
chemical and biological study of the Peace and Alafia rivers and
reported the results of the study, along with recommendations, in
two volumes and several supplements (Florida State Board of
Health, 1955).


Figure 2. Periods of record at streamflow gaging stations.





FLORIDA GEOLOGICAL SURVEY


Lake stage observations of 11 lakes were started in 1946
(fig. 3.)
Peek (1959) has described the geology and ground water of
the Ruskin area in southwestern Hillsborough County.
The present study was begun about mid-1956. This report
presents the results of concurrent countywide studies of the fol-
lowing:
(1) Streamflow
(2) Springflow
(3) Lake stage
(4) Geology
(5) Ground water
(6) Chemical quality of streams, lakes, and water
in underground formations


Bay Lake near Sulphur Springs, Fla.
Lake Carroll near Sulphur Springs, Fla.
Church Lake near Citrus Park, Fla.
Cooper Lake near Lutz. Fla.
-R-o Lake near Citrus Park, Fla.
.Lake Ellen near Sulpi-ur Springs." Fla.
Ranna lake na-r Lutz. Fla.
Lake R .hhs nar lutz. Fla.
Rutrhl-q lake near Lutz. Fla.
Keene Lake near Lutz, Fla.
Kestrone Lake near Odessa. Fla.
Lake Naodalene near Lutz. Fla..
Platt Lake near Lutr, Fla.
Lake Steuper near Lutz, Fla.
Lake Thonotosassa near Tannotnmassa, Fla.


Iv // //// // 7
.I I I I I 7-


(^//////////
OiO0?o^^

N!^^^


2^^^^^^^


I I I I


Figure 3. Periods of record at lake stage stations.


"~'"'"'"'






REPORT OF INVESTIGATIONS No. 25


SOURCES OF ADDITIONAL INFORMATION

U. S. Geological Survey and U. S. Weather Bureau publications
may be purchased from the Superintendent of Documents, U. S.
Government Printing Office, Washington 25, D. C. Publications of
the Geological Survey, May 1958, lists all publications of the U. S.
Geological Survey through May 1958. A revised edition is printed
every 5 years and these are supplemented each year. It includes
a list of Water-Supply Papers published as a numbered series.
U. S. Geological Survey Water-Supply Papers containing data
related to streams and wells in Hillsborough County are listed
below:

Year Number Year Number
1913 319 1945 1032
1928 596G 1946 1052, 1072
1933 742 1947 1082, 1097
1934 757 1948 1112, 1127
1935 782 1949 1142, 1157
1936 773C, 802 1950 1172, 1166
1937 822 1951 1192, 1204
1938 852 1952 1222, 1234
1939 872 1953 1266, 1274
1940 892 1954 1322, 1334
1941 922 1955 1384, 1405
1942 952 1956 1434, 1450
1943 972 1957 1504, 1520
1944 1002 1958 1554, 1571

The Water-Supply Papers through No. 1032 are out of print
but are available through certain public and college libraries.
A list of publications of the Florida Geological Survey may be
obtained from the Florida Geological Survey. Reference files of
these publications have been placed in more than 200 high school,
college, university, public, state and federal agency libraries in
Florida. Many early reports are out of print and are available only
through the reference libraries.
District offices of the U. S. Geological Survey are sources of
most current unpublished basic data. Locations and addresses of
district offices in Florida are as follows:

Branch of Surface Water
Mr. A. 0. Patterson, District Engineer
244 Federal Bldg. Ocala, Florida
Branch of Quality of Water
Mr. K. A. MacKichen, District Engineer
244 Federal Bldg., Ocala, Florida
Branch of Ground Water
Mr. M. I. Rorabaugh, District Engineer
P. 0. Box 110, Tallahassee, Florida






FLORIDA GEOLOGICAL SURVEY


State governmental offices are likewise a source of more current
unpublished information. Mailing addresses:
Florida Geological Survey
Dr. Robert 0. Vernon, Director
P. O. Box 631
Tallahassee, Florida
Florida Department of Water Resources
Mr. John W. Wakefield, Director
The Capitol
Tallahassee, Florida
Florida State Board of Health
Mr. David B. Lee, Director Bureau of Sanitary
Engineering
P. 0. Box 210
Jacksonville 1, Florida
Topographic map coverage of Hillsborough County is shown
in the appendix. Copies of topographic maps may be purchased
from the Map Information Office, U. S. Geological Survey, Wash-
ington 25, D. C. When ordering, include the title of the topographic
sheet desired, along with latitude and longitude of the lower right-
hand corner.

METHODS OF INVESTIGATION

The selection of sites at which measurements were made or
samples were taken was based primarily on the following factors:
(1) existing data, (2) accessibility of the site (for periodic
measurements or sampling), and (3) simplicity of establishing
relationships between stage, streamflow, and quality.
Records of stage were obtained either by continuous water-
level recorders or by measuring directly with a tape or staff gage.
Both surface-water and ground-water elevations are referenced
to mean sea level, datum of 1929. Streamflow was determined
by current meter measurements.
Water samples were collected and analyzed by standard methods
as detailed in "Methods of Collection and Analysis of Water
Samples," (Rainwater and Thatcher, 1960). Streams were sampled
where measured, if practical. Ground-water samples were col-
lected preferably from wells for which depth, depth of casing,
well log, and elevations of the well and of the water were known.
The results of the analysis of these samples were used to estimate
water quality at other locations.
Dissolved materials, mineral content, and organic materials, as
used in this report, are defined as follows: The term dissolved
materials is the residue on evaporation at 1800 C. The concentra-
tion of dissolved materials includes both organic materials and






REPORT OF INVESTIGATIONS NO. 25


mineral content whenever both types of substances are present.
Mineral content is the concentration of dissolved inorganic earth
materials. The term organic materials is an estimate of the
concentration of dissolved organic materials. The concentration
is calculated by substracting the amount of mineral content from
the amount of dissolved materials. The organic materials are
leached from vegetation and characteristically color natural waters.
Whenever organic materials are essentially absent, the dissolved
materials and mineral content become synonymous.
Data used in the evaluation of ground-water resources were
obtained by direct observation, from the records and memory of
well drillers and owners, and from the files of both the Florida
Geological Survey and the U. S. Geological Survey.
Wells were inventoried in the county to determine the location,
depth of well, depth and diameter of casing, owner, year drilled,
and other miscellaneous physical information. The elevation of
the water surface in the wells was determined with maximum error
of 2 feet. These data were used in mapping the piezometric
surface of the county.
Pump tests were made to determine water-transmitting and
water storing capacities of the principal artesian aquifer and leak-
age of the confining beds.
A current meter was used to determine internal velocity
of water in wells to permit comparison of the permeabilities of
the water-yielding zones of the aquifer.
A drawdown test and the tracing of the progress of dye through
the aquifer were helpful in understanding the hydrology.
Well cuttings were examined to determine the elevation of
formational tops, referred to mean sea level. The geologic sections
were prepared from these data.

DESCRIPTION OF AREA

Hillsborough County is located in the western part of peninsular
Florida about midway down the west coast (fig. 4). The northern
boundary of the county is located near latitude 28010' north, the
eastern boundary near longitude 8204' west. It is bordered on
the western side by Pinellas County, on the northern side by Pasco
County, on the eastern side by Polk County, and on the southern
side by Manatee County.
The county is square except for indentations in the southwestern
part made by Tampa Bay. The bay gives the county an extensive
protected coastline and makes excellent seaport facilities possible.






FLORIDA GEOLOGICAL SURVEY


Figure 4. Location of Hillsborough County, Florida.






REPORT OF INVESTIGATIONS No. 25


I'he land area is 1,040 square miles and ranges in elevation from
sea level at the bay to more than 160 feet above sea level at the
Hillsborough-Polk county line southeast of Keysville. There
are many lakes in the northwestern part of the county.
There are three main surface drainage basins in the county:
the Hillsborough, Alafia, and Little Manatee river systems. The
three main rivers rise near the eastern boundary line of the
county and drain toward the bay area.
Numerous springs occur in the northern half of the county.
Hillsborough County is one of the major metropolitan areas in
Florida and the economy is based on manufacturing, agriculture,
recreational activities, and allied trades (Bureau of the Census,
1956). The county occupies less than 2 percent of the land in the
State, yet in 1954 it had about 10 percent of the manufacturing
businesses in the State. During 1954 these businesses employed
nearly 19,000 people and paid more than $57 million in wages. In
1958 about 98,000 acres of land was used for agricultural purposes,
38,000 for citrus farming, 25,000 for vegetable farming, and
35,000 for pasture (oral communication: Mr. Jean Beam, Hills-
borough County Agricultural Agent).
In 1954 the retail sales in the county totaled more than $320
million. More than 15,000 people employed in this business received
nearly $33 million in wages. About 8,000 people employed in
wholesale trade received more than $28 million in wages. Businesses
providing services employed about 5,000 people who received more
than $12 million in wages.
During the decade 1940-50, Hillsborough County registered a
growth in population of 38.7 percent for a total population of
249,894 in 1950. In the succeeding decade, the county registered
a population growth of 59 percent for a population of 397,788 in
1960. This gave the county a population density of 380 people per
square mile. More than 75 percent of these people live in urban
areas. The greatest concentration of the people is in the city of
Tampa.
Mean monthly temperatures range from about 600 F. to 82 F.
Temperature extremes range from below freezing to about 100
degrees. From 310 to 365 days per year free of killing frost can be
expected in the county.
The area has been affected by 29 hurricanes of varying
intensities since 1900 (Corps of Engineers, 1956). The important
hydrologic effect of these tropical disturbances is the very heavy
rainfall associated with the storms.






FLORIDA GEOLOGICAL SURVEY


HYDROLOGY OF HILLSBOROUGH COUNTY

In the hydrologic cycle, water that falls on the earth evaporates,
runs off the land to the sea, and infiltrates the ground. The water
entering the ground emerges on the surface in lakes, streams,
springs, and the sea or is returned to the atmosphere by evapo-
transpiration. The quantity of water following any of these paths
is dependent mainly on the weather, topography, and geology.
Water dissolves some of those materials with which it is in
contact. The amount of minerals that may be dissolved in the
water depends mainly on the rate of solution, the time of contact,
and the solubility of the materials contacted. Solubility limits
the amount of any materials in solution regardless of time of
contact or rate of solution. Ultimately the mineralized water
finds its way to the sea. Long continued addition of minerals in
this manner has given rise to the highly mineralized water that we
know as sea water.
The divisions of surface water and ground water have been
used for the presentation of the bulk of the material that makes
up this report.

RAINFALL

The average annual rainfall in Hillsborough County is 50.24
inches. This is equivalent to about 21 bgd (billion gallons
per day). Only a part of this water is available for use.
Rainfall varies with time, but averages based upon 30 or more
years of record remain nearly the same. Mean, maximum, and
minimum monthly rainfall is shown in figure 5, to illustrate the
variation.

EVAPOTRANSPIRATION

The amount of evaporation and transpiration from the land
and water surfaces of Hillsborough County has been estimated
to be 11/ bgd. This is equivalent to a sheet of water 30 inches
thick over the area of Hillsborough County each year. The
figure of 11/f bdg is derived by difference between i flow plus
precipitation and outflow plus water use. --
About 50 inches of water per year evaporates from lakes in
Hillsborough County.-Recordsof evaporation have been collected
since 1952 from a Class A pan located at Bay Lake. An average
of about 61 inches of water evaporates from the pan per year. In






REPORT OF INVESTIGATIONS No. 25


25 -

24

23

22

21

20

19


17








12
0II
O 16
w






o 9s
0





S8
CL7
15
14

Z 13
12
z

S10








I
0
wLJ8



6

5

4

3

2


0


Figure 5. Mean, maximum, and minimum monthly rainfall at Tampa,
Florida, 1840-1958.


!


RAINFALL IN TAMPA
(1840-1958)






MAXIMUM























MEAN




MINIMUM






J IF -M IA M J J A S 0 N D






FLORIDA GEOLOGICAL SURVEY


December, an average of 2.8 inches evaporates. The average rate
increases to 7.5 inches in May and gradually decreases to 5.2 inches
in September.
Evaporation from the shallow pan is generally greater than
that from a lake. Monthly coefficients have been computed from
records collected from 1940-56 at Lake Okeechobee, Florida (table
1). They range from 0.69 for February to 0.91 for July and
August. The computed evaporation from lakes in Hillsborough
County is shown in table 1.
SURFACE FLOW
The streams in Hillsborough County generally flow towards
Tampa Bay. In the northwestern part, Rocky Creek and Sweet-
water Creek flow southward and empty into Old Tampa Bay. In
the northeastern part, the Hillsborough River and Palm River
flow southwestward and into Hillsborough Bay. In the southern
half of the county, the Alafia River and the Little Manatee River
flow westward and into Tampa Bay. Old Tampa Bay and Hills-
borough Bay flow southward into Tampa Bay which, in turn,

TABLE 1. Monthly Mean Evaporation from Lakes in Hillsborough County

Evaporation (inches)
Class A
Month Pan' Pan Coefficient2 Lakes

January 3.17 0.77 2.44
February 3.73 .69 2.57
March 5.23 .73 3.82
April 6.35 .84 5.33
May 7.53 .82 6.17
June 7.10 .85 6.04
July 6.18 .91 5.62
August 5.66 .91 5.15
September 5.24 .85 4.45
October 4.45 .76 3.38
November 3.44 .71 2.44
December 2.77 .83 2.30

Total 49.71

'Monthly mean of record for 1952-58 from U. S. Weather Bureau
evaporation station at Bay Lake near Sulphur Springs, Florida.
!Computed evaporation data for Lake Okeechobee, Florida, Kohler, M.
A., 1954.)






REPORT OF INVESTIGATIONS No. 25


empties into the Gulf of Mexico. The average streamflow into
the bays is slightly more than a billion gallons a day. About 6
percent flows into Old Tampa Bay, 77 percent flows into
Hillsborough Bay, and 17 percent flows directly into Tampa Bay.
Hillsborough County is the source of about two-thirds of this water.
The remaining one-third comes from parts of Hernando, Lake,
Sumter, Pinellas, Pasco, Polk, and Manatee counties.
Runoff is generally high in the southern part of the county,
moderate in the northeastern part, and low in the northwestern
part. Yearly mean values range from 12 inches in the northwest
to 17 inches in the south. An exception is the Palm River basin.
Although this basin is in the central part of the county, its runoff
is high (24 inches). The yearly average runoff for the county is
15.6 inches.

UNDERGROUND FLOW

Generally, the piezometric surface in Hillsborough County
slopes towards Tampa Bay, indicating the general direction of
underground flow. In the northwestern part of the county, ground-
water flow is southward to Old Tampa Bay; in the northeastern
part, the flow is southwestward to Hillsborough Bay; and in the
southern half it is westward to Tampa Bay.
About 100 mgd flows through the ground into Hillsborough
County. This value was derived using the formula Q-TIL, where
Q is the ground-water flow in gallons per day, T is the transmissi-
bility rate in gallons per day per foot, I is the piezometric slope
in feet per foot, and L is the length in feet of the contour crossed.
The values used in the computation were 2.7 x 101 gpd per foot
for the transmissibility rate, 9 x 10-" for the average piezometric
slope, and 3.85 x 10" feet for the length of contour at the county
line.
Springs in Hillsborough County discharge water in quantities
about equal to the ground-water flow into the county. Sulphur,
Eureka, Buckhorn, and Lithia springs discharge 77 mgd, and
other known springs discharge about 20 mgd.
Water probably seeps into the ground at a rate of more than
450 million gallons a day. About 50 mgd of this water emerges in
the bays adjoining Hillsborough County. Another 67 mgd is
pumped from the ground for industrial, farm, public and private
water supplies. The remainder emerges in streams of the county
and flows to the bays. The figure of 450 mgd excludes the ground
water returned to the atmosphere by transpiration.






16 FLORIDA GEOLOGICAL SURVEY

GEOLOGY

Hillsborough County is underlain by sedimentary rocks ranging
in thickness from about 8,000 feet in the northeast to about 13,000
feet in the southwest (Applin, 1951). These sediments, which rest
on crystalline rocks, consist of sandstone, anhydrite, and dolomite
of Mesozoic age overlain by limestone, dolomite, clay, and sand of
Cenozoic age.
Only the upper 1,000 feet of the Cenozoic section is used as a
source of water in the county. Only two water wells over 1,000
feet deep were inventoried during the investigation.
The depth of a well is controlled by economy and by depth to
salt water. For economical reasons, a well is finished at the
shallowest depth at which a given yield at a given drawdown is
obtainable. The depth of a well, for most purposes, must also be
limited by the depth to salt water. In the northeastern part of the
county, the depth to salt water is probably more than 4,000 feet
below the surface. The maximum depth of a fresh-water well in
that area would be about 4,000 feet. At this depth the entire
Cenozoic section would have been penetrated.
Table 2 summarizes the geologic formations and their properties
from the bottom of the Oldsmar limestone of Eocene age to the
recently deposited sands and clays at the surface. This section is
believed to include all of the formations that are economically
exploitable as a source of water in the county.
The rocks of Cenozoic age in the county were laid down in
essentially horizontal position. During deposition of sediments,
the land was tilted downward to the southwest. This resulted in
thickening of the beds in that direction. The forces resulting from
differential compaction, along with regional forces associated with
the Ocala uplift and the peninsular arch, warped the beds down-
ward to the southwest. The stresses were relieved by faulting. The
present attitude of the beds is the result of these structural changes.
The available data indicate the existence of many faults, some with
about 200 feet of vertical displacement. Additional data are
necessary to place and limit these faults.
Because the beds thicken and dip to the southwest, wells .-of
similar bottom elevation will penetrate older formations in the
northeast than in the southwest. Most of the deep wells in the
southwestern part of the county produce water principally from
the Tampa and Suwannee limestones, whereas those in the central-
east and northeast parts of the county commonly produce from
the Avon Park limestone.








TABLE 2. Summary of Geologic Formations from Bottom of Oldsmar Limestone to the Ground Surface


Formation


Undifferentiated


Hawthorn formation


Tampa limestone


Suwannee limestone


Thickness


0-150






0-250


80-400


Character of material


Sand, clay, and marl.


Clay, sand, and limestone. Lime-
stone, near bottom of formation,
is white to gray, soft, sandy, and
porous.

White, cream, and gray, hard
to soft, sandy limestone. Many
molds of pelecypods and gastro-
pods.

White, yellow, and light brown,
soft to hard, dense, fine-grained
limestone with chert lenses to
25 feet thick.


Water supply


Sand yields up to 200 gpm in
some areas and generally 5 to
10 gpm to driven wells less than
40 feet deep. Clay and marl do
not yield usable quantities of
water to wells.


Limestone member yields up to
200 gpm.


Yields up to 1,000 gpm. Supplies
most domestic and commercial
wells in county.


Crystal River formation Yellow-gray and brown soft, al- Rarely used for water supply
(Puri, 1957) most pure limestone. Mostly because of low transmissibility.
Williston formation 90-300 foraminiferal coquinas in pasty
(Puri, 1957) limestone matrix.
Inglis limestone

Soft, chalky, cream to brown Principal source of supply for
Avon Park limestone 200+ limestone containing beds of wells yielding more than 500
foraminiferal coquina and zones gpm. Yield exceeds 5,000 gpm
of brown to dark brown, hard, in some wells.
Lake City limestone 500 crystalline dolomitic limestone.
Locally contains some gypsum.

Fragmental dolomitic limestone Not used for water supplies but
Oldsmar limestone 900 with lenses of chert, thin shale is potential source of fresh water
beds, and some gypsum. in north-central and northeast-
ern part of county.


Cedar Keys limestone


Not
known


Not known


Not used.
known.


Potential use not


Aquifer


Water
table
aquifer


Shallow
artesian
aquifer


Principal
artesian


Water level


Water level generally less than
10 feet. Water table follows
topography in a subdued
manner.


Piezometric surface not de-
fined. Water level is generally
higher than that of nearby
wells in principal artesian
aquifer.


Piezometric surface shown in
figures 48 and 49.


'The Ocala group used here accords to the terminology of the Florida Geological Survey.


Series


Pleistocene
Recent


and


Pliocene


Miocene


Oligocene


Eocene


Paleocene


----------- I I---------I II


I I I-


I ------


----I -----






REPORT OF INVESTIGATIONS NO. 25


Geologic cross sections through Hillsborough County are shown
in figure 6.

WATER PROBLEMS

Hillsborough County is now in a period of accelerated popula-
tion and economic growth. Large quantities of water will be
needed for municipal and industrial uses.
The need for land also is increasing with the growing
population. Areas having poor drainage and the flood plain of
streams are being used to fill the need. As more people occupy
and use this type of land, pressure will be placed upon govern-
mental agencies to have drainage and flood-control works
performed.
The per capital use of water in the county is estimated to equal
the national average of 1,100 gallons per day. In 1955, the per
capital use of water in Florida was 900 gallons per day. The county
has many industries which make its per capital use greater than
the average for the State.
It will be necessary to reclaim and re-use water or to import
water when the population of Hillsborough County exceeds the
number of persons that may be supported by the available water.
An average of about 1,400 mgd is potentially available. This is
enough water to supply 1,250,000 persons if all of the flood waters
could be stored for use. At present 400 mgd of this water enters
the county from adjoining counties.
Surface-water problems in Hillsborough County are caused by
the distribution of water. Three relative conditions occur-low
water, medium water, and floods. When flood conditions exist, the
problem becomes one of eliminating excess water that might cause
damage and inconvenience. During medium and low water
periods, the problems may become one of finding suitable water
sufficient to satisfy the needs.
The flooding of the community of Bloomingdale Acres in March
1959 illustrates the problems encountered when flood plains are
used for residential purposes. Bloomingdale Acres was built on
the north bank of the Alafia River during 1957 and 1958. In March
1959, the stage in the river rose to 26.9 feet above the mean sea level
and a large portion of Bloomingdale Acres was flooded. In the
past, similar stages have recurred every 4 to 5 years.
The question of whether a piece of property is subject to
flooding may be determined from lake and stream stage data and
topographic maps.




-ELEVATION, IN


FEET REFERRED TO MEAN SEA


8 0 0


o .0


88 88


r-0 -r
0


C D
0CD C
OLCD

-n o
o0~


.5
0 0


8b.-24-3-
Pret' y lake

' -Brushy Creek

S 804-229-1

S80 2 5Ec-les

m 801-227-3

H L Z= 802-225-2


C-> -4802-223-1
Hillsborough River

c -u >

R**, =1 ...802-217-1


E- E= --,^ 801o-213-22


-'

; l [ 1" 800-2--
moa --vL- -roz800-207-1-


(AM 1i -L
) o a o o o
S0 0 0 0

807-230-3
Lake
I H i Cooper Lake
E 809-227-1
.808-226-1
L

z- r- Trout Creek
Scloy Gully


E 807-218-1
I- t _- -

S L o Z Hillsborough River
808-214-2

- 0 _




rn(
--_ 805-213-1




804-207-1
-0 O\

- 1- -U Hillsborough Co.
LO Polk Co.




1 = 0 V 805-157-15


LEVEL
L E V E
*^ O fU
Q0 0


S746-228-2

S- Little Manatee
S- River



746-224-10



7 I- n Alafia River
..... -751-225-2




-n- 755-221-1

Palm River
-758-222-1
: LakeLee
I.U...H59 222-2

S-800-224-1
.. Hillsborough

: 802-225-2



-;'H -
S'I 8,08-226-1


o 0 o o o o o
i I I I I I I I I


S --- 746-209-1
::--,-,-- 748-208-1
r > -rI Chilo Br

- 52-207-1
!---u= -- -= y = -=:= n .j' 752*) 07co n -1_


UI)
o- C.

ID
~.0


o =r
00

tbo


144.





I o C E



nT


S1 I I I .. 75-208-1

0 'I~Turkey Cr



,o C,-800-207-1



M il:I :: 1804-207-1


0 0


,I


If







FLORIDA GEOLOGICAL SURVEY


Ground-water problems are related to distribution and occur -
rence with respect to quality. Desired quality limits the quantity of
water available for a given use. The elevation of the piezometric
surface and the geology of the area are the principal factors con-
trolling the quality of ground water.
Salt content is the major quality problem in the county. There
are two potential sources of salt water, (1) Tampa Bay and (2)
connate waters. Sea water can enter the aquifer when the water
level in the aquifer is lowered sufficiently. This condition exists
near Gibsonton. Heavy industrial pumping in that area has lowered
the piezometric surface to below sea level in the vicinity of the
channel cut in the bay. This condition also exists along the shore
of the bay west of the Interbay peninsula where the piezometric
surface is near sea level because of natural discharge.
Zonation in an aquifer allows a salty zone to exist in the upper
part of the aquifer near a surface source of salt water at the same
time that lower zones contain fresh water.
In the remainder of the county, as well as in some of the tidal
areas, salt water in wells is derived from a body of salty connate
water that has not been flushed from the aquifer since the area
emerged from the sea. This water underlies the entire county at
depth. In general, the salt water interface occurs at a depth below
sea level of 40 times the elevation of the piezometric surface
above sea level. The 40-to-1 relationship is based on specific
gravities of 1 for fresh water and 1.025 for salt water and assumes
a sharp interface in a static system. Actually the fluctuation of
the piezometric surface, movement of ground water, ocean tides,
and circulation of the salt water in convection-like currents, cause
the interface to be gradational between fresh and salt water, with
a thickness of more than 100 feet in places.
Salt content generally will increase with depth, but the increase
is not uniform. In some areas, the bulk of the aquifer may contain
salty water, but certain zones through which large amounts of
water are moving may be relatively fresh. In other areas, the bulk
of the aquifer may contain fresh water, but a cavity may contain
very salty water. Areas near one of the many faults that may act
as conduits for the upward movement of the connate water are
potentially salty. Thus, with the development of the ground-water
resource and the resultant lowering of the piezometric surface,
the contaminated areas will become more numerous, and the
existing areas of contamination will become more pronounced.
Prevention of problems from this source may require recharge







REPORT OF INVESTIGATIONS NO. 25


of the aquifer by surface water to raise the piezometric surface in
the affected areas.
Future development of ground-water supplies for municipal
or other large users will be controlled by the elevation of the
piezometric surface and by geological conditions that affect quality
of water.
The decline of water levels caused by extensive development of
ground-water supplies may make the placing of well fields
unfeasible in the area where the elevation of the piezometric
surface is less than 50 feet above sea level.
The flanks of the piezometric highs centered in Pasco and
Polk counties present nearly ideal sites for development of future
water supplies. The area of the reentrant (indicated by upstream
bending of the contour lines) in the piezometric surface that fol-
lows the Hillsborough River from near Tampa to the northeastern
part of the county is not favorable for location of well fields. Any
pumpage from wells in that area would only deplete the surface-
water supply presently used by the city of Tampa as a source of
water and would cause rapid contamination of the river and wells
by salt water.
The Industrial Park area in northeast Tampa is unsuitable for
large-scale ground-water development because of existing quality
of water problems. Increased pumping would further contaminate
the aquifer with the salty water that locally makes ground water
in the area unsuitable for most purposes.
When a well is allowed to flow, it diminishes the usable volume
of water that may be withdrawn from the aquifer. At present,
wells flowing to waste are important only in the vicinity of Ruskin,
where quality of water is directly related to local heavy withdrawal,
and in the vicinity of Tampa, where salt water already has spoiled
the water in part of the aquifer as a source of fresh water.
Development of the ground-water resource to its full potential
will necessitate control of waste flow from wells and may warrant
the plugging of springs where feasible.

SURFACE WATER

Eighty-four percent of the water drained from the 1,040 square
miles of land surface in Hillsborough County is carried by 10
streams. The remainder is drained from the land adjacent to
Tampa Bay by numerous small streams, canals, ditches, and
sewers. Some characteristics are discussed for the following
stream basins:






REPORT OF INVESTIGATIONS NO. 25


Geologic cross sections through Hillsborough County are shown
in figure 6.

WATER PROBLEMS

Hillsborough County is now in a period of accelerated popula-
tion and economic growth. Large quantities of water will be
needed for municipal and industrial uses.
The need for land also is increasing with the growing
population. Areas having poor drainage and the flood plain of
streams are being used to fill the need. As more people occupy
and use this type of land, pressure will be placed upon govern-
mental agencies to have drainage and flood-control works
performed.
The per capital use of water in the county is estimated to equal
the national average of 1,100 gallons per day. In 1955, the per
capital use of water in Florida was 900 gallons per day. The county
has many industries which make its per capital use greater than
the average for the State.
It will be necessary to reclaim and re-use water or to import
water when the population of Hillsborough County exceeds the
number of persons that may be supported by the available water.
An average of about 1,400 mgd is potentially available. This is
enough water to supply 1,250,000 persons if all of the flood waters
could be stored for use. At present 400 mgd of this water enters
the county from adjoining counties.
Surface-water problems in Hillsborough County are caused by
the distribution of water. Three relative conditions occur-low
water, medium water, and floods. When flood conditions exist, the
problem becomes one of eliminating excess water that might cause
damage and inconvenience. During medium and low water
periods, the problems may become one of finding suitable water
sufficient to satisfy the needs.
The flooding of the community of Bloomingdale Acres in March
1959 illustrates the problems encountered when flood plains are
used for residential purposes. Bloomingdale Acres was built on
the north bank of the Alafia River during 1957 and 1958. In March
1959, the stage in the river rose to 26.9 feet above the mean sea level
and a large portion of Bloomingdale Acres was flooded. In the
past, similar stages have recurred every 4 to 5 years.
The question of whether a piece of property is subject to
flooding may be determined from lake and stream stage data and
topographic maps.






FLORIDA GEOLOGICAL SURVEY


Anclote River basin
Brooker Creek basin
Rocky Creek basin
Sweetwater Creek basin
Hillsborough River basin
Palm River basin
Alafia River basin
Bullfrog Creek basin
Little Manatee River basin
Peace River basin
A map showing the area in Hillsborough County
the streams of these 10 basins is shown in figure 7.









0a


drained by


HILLSBOROUGH COUNTY
FLORIDA
S\.


A


Figure 7. Surface-water features, location of gaging stations, and
water sampling sites.







REPORT OF INVESTIGATIONS NO. 25


USE

The majority of surface water uses in Hillsborough County are
nonconsumptive. Most of this water is used in some way for
recreational purposes. Some is used for cooling, washing, shipping,
etc. Water flowing in Pemberton Creek and in the Alafia River is
used to dilute and carry waste materials.
No estimate is made of the quantity of surface water consumed
in the county. The amount of water pumped for irrigation of citrus
groves and truck crops is not known.. The known uses include 3
mgd for industrial processes and 23 mgd for municipal supply.

ANCLOTE RIVER BASIN
ANCLOTE RIVER

The Anclote River drains 113 square miles of land in Pinellas,
Pasco, and Hillsborough counties. However, only about 3 square
miles of the land is in Hillsborough County, along the northern
boundary and is 40 to 60 feet above mean sea level. Water
draining from this area moves northwestward to the Anclote River
through Pasco and Pinellas counties. Osceola Lake, Lake Artillery,
and Lake Hiawatha lie in the Hillsborough County portion of the
river basin. Lake Hiawatha is the largest of these lakes. It has a
surface area of 100 acres, of which 80 percent is in Hillsborough
County and the remainder in Pasco County.

BROKER CREEK BASIN
BROKER CREEK

Brooker Creek drains approximately 42 square miles of land
in Hillsborough, Pasco, and Pinellas counties, of which 28 square
miles is in northwestern Hillsborough County. The remainder
(14 square miles) is in Pasco and Pinellas counties. The creek
heads in the marshy area 2 miles east of the town of Lake Fern
and 4 miles southeast of Odessa. It flows generally in a south-
southwestward direction to Keystone Lake, then northward to
Island Ford Lake, and then southwestward toward Lake Tarpon in
Pinellas County, crossing the county line half a mile south of State
Highway 582. The land is about 60 feet above sea level in the
northeastern part of the basin and 20 feet above sea level at the
county line. There are numerous lakes in the upper part of the
basin. The land in this area is used mainly for growing citrus.







REPORT OF INVESTIGATIONS NO. 25


of the aquifer by surface water to raise the piezometric surface in
the affected areas.
Future development of ground-water supplies for municipal
or other large users will be controlled by the elevation of the
piezometric surface and by geological conditions that affect quality
of water.
The decline of water levels caused by extensive development of
ground-water supplies may make the placing of well fields
unfeasible in the area where the elevation of the piezometric
surface is less than 50 feet above sea level.
The flanks of the piezometric highs centered in Pasco and
Polk counties present nearly ideal sites for development of future
water supplies. The area of the reentrant (indicated by upstream
bending of the contour lines) in the piezometric surface that fol-
lows the Hillsborough River from near Tampa to the northeastern
part of the county is not favorable for location of well fields. Any
pumpage from wells in that area would only deplete the surface-
water supply presently used by the city of Tampa as a source of
water and would cause rapid contamination of the river and wells
by salt water.
The Industrial Park area in northeast Tampa is unsuitable for
large-scale ground-water development because of existing quality
of water problems. Increased pumping would further contaminate
the aquifer with the salty water that locally makes ground water
in the area unsuitable for most purposes.
When a well is allowed to flow, it diminishes the usable volume
of water that may be withdrawn from the aquifer. At present,
wells flowing to waste are important only in the vicinity of Ruskin,
where quality of water is directly related to local heavy withdrawal,
and in the vicinity of Tampa, where salt water already has spoiled
the water in part of the aquifer as a source of fresh water.
Development of the ground-water resource to its full potential
will necessitate control of waste flow from wells and may warrant
the plugging of springs where feasible.

SURFACE WATER

Eighty-four percent of the water drained from the 1,040 square
miles of land surface in Hillsborough County is carried by 10
streams. The remainder is drained from the land adjacent to
Tampa Bay by numerous small streams, canals, ditches, and
sewers. Some characteristics are discussed for the following
stream basins:






FLORIDA GEOLOGICAL SURVEY


The average discharge (1946-55) of the creek at the outlet of
Keystone Lake was 4.8 mgd (0.48 mgd per sq. mi.). The highest
recorded daily flow of 116 mgd occurred in August 1949. Several
times during the period of record, there was no flow in the creek.
In 1949, there was no flow for 159 consecutive days, and, in 1951,
there was no flow for 94 consecutive days.
During the 8-year period, 1950-58, the flow of Brooker Creek
2 miles upstream from Lake Tarpon averaged 14.5 mgd (0.48 mgd
per sq. mi.), the same rate of runoff per unit area as at the
outlet of Keystone Lake.

KEYSTONE LAKE
Keystone Lake, with a surface area of 580 acres at a stage of
41 feet above mean sea level, is the largest of the two dozen
named lakes and numerous unnamed lakes within the area drained
by Brooker Creek. It is an integral part of the Brooker Creek
channel. During the period, April 1946 to December 1959, the
maximum and minimum stages of the lake were 43.20 (August
1949) and 38.60 feet (June 1949), respectively, in relation to
mean sea level. Stages in this lake closely follow the seasonal
rainfall pattern. The annual variation in stage on the lake is
less than 5 feet. A stoplog dam was constructed at the lake
outlet in October 1955.

CHURCH AND ECHO LAKES
Church and Echo lakes, located 2 miles northwest of Citrus
Park, have a surface area of 70 and 25 acres, respectively, when
the stage is 33 feet above mean sea level. The stage did not drop
below the bottom of the channel connecting the two lakes during
the period of this investigation. Therefore, the two lakes react as
one.
Church and Echo lakes are reported by local residents to be
used as a source of water for the irrigation of surrounding groves.
It would take a pump with a capacity of 360 gpm, running con-
tinuously at full capacity for a period of 30 days, to lower the
stage of these lakes half a foot.
During the 2 years of the stage investigation, Church and Echo
lakes have ranged from 33.92 to 37.28 feet above mean sea level
(fig. 8). When the stage is more than 35 feet above mean sea
level, Church, Echo, Thorpe, and Williams lakes become inter-
connected. This complex of lakes was formerly called Lake
Sullivan. I
































1957 1958


Figure 8. Stage of Chuich and Echo lakes, 1957-59.






FLORIDA GEOLOGICAL SURVEY


ROCKY CREEK BASIN
ROCKY CREEK

Rocky Creek drains 42 square miles of land in Hillsborough
County and 3 square miles in Pasco County. The creek proper
begins at Turkey Ford Lake and flows southwestward through
Rock Lake, Lake Josephine, Pretty Lake, and Lake Armistead,
then southward into Old Tampa Bay. Land elevations are as high
as 60 feet in the upper part of the creek basin and at sea level near
the mouth. There are numerous lakes in the northern two-thirds
of the basin but very few in the southern part.
The lake area in the northeastern part of the basin contributes
water to Rocky Creek through ill-defined channels leading to Tur-
key Ford Lake. The only measurement of flow from this area was
made at Vernon Road on September 27, 1947. The flow at the
bridge crossing was 40.0 cfs (cubic feet per second). On this same
day the mean daily flow of Brooker Creek at the outlet of Keystone
Lake was 60.0 cfs, 8 times the 9-year average flow for 1946-55.
In 1953, a timber dam was constructed on Rocky Creek about a
100 feet upstream from the east-west tracks of the Seaboard
Air Line Railroad, 4 miles above the mouth. Stage below the dam
fluctuates with the tides of Old Tampa Bay, and, when flow is
sufficient to just submerge the control, tidal fluctuations are
discernible as far as 5 miles above the creek's mouth.
During the 5-year period, 1953-57, the average flow of Rocky
Creek at the control was 20 mgd (0.57 mgd per sq. mi.). Flows
ranged from a minimum of 0.3 mgd (May and June 1955) to a
maximum of 450 mgd (September 1953). The flow fell below 1.5
mgd in 1953, 1955, 1956, and 1957. The longest period, 96 con-
secutive days, was in 1955.
The estimated average flow of Rocky Creek at the mouth is
24 mgd.
The concentration of material dissolved in Rocky Creek on
January 29, 1959, was estimated to be about 50 ppm. About 30
ppm of this total was mineral content and the remaining 20 ppm
was organic material. These estimates are based upon measure-
ments of specific conductance and a color intensity of 110 platinum-
cobalt scale units.

BUSHY CREEK

Bushy Creek, the largest tributary to Rocky Creek, drains 11
square miles of land west of Sulphur Springs. The creek begins ai






REPORT OF INVESTIGATIONS NO. 25


Starvation Lake and flows southwestward, joining Rocky Creek a
quarter of a mile south of Gunn Highway. Its largest tributary
ieads in Lake Le Clare and flows southward joining Brushy Creek
about 11/2 miles above its confluence with Rocky Creek.
The concentration of material dissolved in Brushy Creek on
January 29, 1959, was estimated to be 70 ppm. About 35 ppm
of this total was mineral content and the remaining 35 ppm was
organic material. These estimates are based on measurements of
specific conductance and a color intensity of 130 platinum-cobalt
scale units.

SWEETWATER CREEK BASIN
SWEETWATER CREEK

Sweetwater Creek drains 25 square miles of land in Hills-
borough County. It begins at Lake Magdalene, flows westward to
Bay Lake, then southward to Lake Ellen, and finally, south-
southwestward to Tampa Bay. Stoplog dams are used to regulate
flow into and out of these lakes. The land drained by the creek
ranges in elevation from 55 feet at the northern divide to sea level
at the mouth. This creek basin is now becoming urbanized,
especially around the lakes, with citrus groves and farms being
replaced by housing developments.
During the 7-year period, 1952-58, the average discharge of
Sweetwater Creek was 3.0 mgd at the Gunn Highway. This is
equivalent to only 0.47 mgd per square mile of area drained. Other
local watersheds having little surface storage yield about 0.6 mgd
per square mile. The low yield from Sweetwater Creek watershed
above the Gunn Highway is attributed to the detention of water
in the lakes, which results in an increase in the evaporation and
seepage losses. There was no flow in Sweetwater Creek many
times during the period 1951-58. During the 18-month period
November 1955 to April 1957, the maximum flow was 1.5 mgd and
the average flow was less than 0.1 mgd.
The estimated average flow of Sweetwater Creek at its mouth
is 14 mgd.
During periods of high water, the Hillsborough River basin
is interconnected with the Sweetwater Creek basin between Platt
Lake and Lake Magdalene.
One of the larger tributaries to Sweetwater Creek heads in
White Trout Lake, flows southwestward and joins the creek 1.2
miles north of Hillsborough Avenue (State Highway 580) and 2.3
miles east of Dale Mabry Highway (State Highway 597). It






FLORIDA GEOLOGICAL SURVEY


drains about 4 square miles of land lying west of Tampa and has;
an estimated average flow of 3 mgd.
On January 29, 1959, the concentration of dissolved material
in the South Branch of Sweetwater Creek was estimated to be 110
ppm and in Sweetwater Creek just below South Branch it was
estimated to be 80 ppm. About 55 ppm and 45 ppm, respectively,
of this was mineral content, and the remainder was organic
material. These estimates are based on measurements of specific
conductance and respective color intensities of 220 and 110
platinum-cobalt scale units.

LAKE MAGDALENE

Lake Magdalene, the largest lake in the Sweetwater Creek I
basin, has a surface area of 230 acres when the stage is 47 feet
above mean sea level. During the past 12 years, 1947-58, the stage
has fluctuated between 44.5 and 50.8 feet above mean sea level.
Ninety percent of the time the stage was greater than 46.4 feet;
50 percent of the time it was greater than 48.6; and 10 percent of
the time it was greater than 49.5 feet.
Stage-duration curves for Lake Magdalene, Bay Lake, Lake
Ellen, and Carroll Lake are shown in figure 9. The curves for Lake
Magdalene, Bay Lake, and Lake Ellen are plotted on the same grid
with Hobbs Lake, Cooper Lake, and Platt Lake. All of these lakes
are part of the same drainage course during periods when some of
the flow of the drainage ditch of the Hillsborough River basin is
diverted into the Sweetwater Creek basin.

BAY LAKE

Bay Lake, 3.5 miles northwest of Sulphur Springs and 4.4 miles
east of Citrus Park, has a surface area of 38 acres when the stage
is 45 feet above mean sea level. During the past 12 years, 1947-58,
the stage fluctuated between 43.0 and 46.7 feet. Ninety percent
of the time the stage was greater than 43.9 feet; 50 percent of
the time it was greater than 45.1 feet; and 10 percent of the time
it was greater than 45.6 feet (fig. 9).

LAKE ELLEN
Lake Ellen, located 3.8 miles northwest of Sulphur Springs, hall
a surface area of 50 acres when the stage is 39 feet above mear
sea level. During the 10-year period, September 1946 to August
1956, the stage fluctuated between 37.6 feet and 41.8 feet. Ninet'













$6

68

6T



65






W 6


0
x 60




0 59
so



56

Q 54




0 52

w
51



S50













43

48
47















3,

34

37


100 o0 s0 To S0 80 40 o3 20 10 0

PERCENT OF TIME

Figure 9. Stage-duration curves of some lakes in Hillsborough County.


REPORT OF INVESTIGATIONS No. 25


100 90 80 70 0 50 40 30 20 10 0




65

64I
KEENE LAKE 1949-5 IME1


















100 90 10 70 PE SO 40 30 20 10 0

PERCENT OF TIME






FLORIDA GEOLOGICAL SURVEY


percent of the time the stage was greater than 38.9 feet; 5C
percent of the time it was greater than 39.9 feet; and 10 percent
of the time it was greater than 40.6 feet (fig. 9).

CARROLL LAKE

Carroll Lake, located 2.8 miles northwest of Sulphur Springs
in the Sweetwater Creek drainage basin, covers 186 acres when
the stage is 34 feet above mean sea level. During periods of high
stage, water from the lake flows southwestward through a swampy
area and into Sweetwater Creek above Gunn Highway. Lake
stages fluctuated between 32.2 feet and 40.1 feet above mean sea
level during the past 13 years (1947-58). Ninety percent of the
time the stage was greater than 33.9 feet; 50 percent of the time
it was greater than 35.9 feet; and 10 percent of the time it was
greater than 37.4 feet (fig. 9).

HILLSBOROUGH RIVER BASIN
HILLSBOROUGH RIVER

The Hillsborough River drains 690 square miles of land in
Hernando, Pasco, Polk, and Hillsborough counties. During periods
of high water, the Withlacoochee River, which drains parts of
Lake and Sumter counties, overflows into the Hillsborough River
basin near Richland. The river rises in the Green Swamp area of
central peninsular Florida and flows southwestward to Hillsborough
Bay at Tampa.
About 320 square miles of land in Hillsborough County is
drained by the Hillsborough River. Land elevations range from
sea level at the mouth of the river to more than 140 feet at a point
east of Plant City. There are many lakes and springs in the basin.
The greatest concentration of lakes is along the western basin
divide, north of Tampa, and the largest lake, Lake Thonotosassa,
is located between Plant City and Temple Terrace. Citrus groves,
cattle ranches, and truck farms are located in the rural parts of
the river basin. Plant City, Temple Terrace, and part of Tampa
are in the basin.
The flow of the Hillsborough River is gaged at Hillsborough
River State Park where the river drains approximately 220 square
miles. During the 19-year period, 1940-58, the average discharge
of the river there was 173 mgd (0.79 mgd per sq. mi.). The lowest
flow recorded during this period was 31 mgd (June 1945). Flow
in the river is sustained by the discharge of Crystal Springs, which







REPORT OF INVESTIGATIONS NO. 25 29

empties into the Hillsborough River in Pasco County just above
the Hillsborough-Pasco county line. About 90 percent of the time
the flow is 71 cfs or 46 mgd or more; 50 percent of the time it is
120 cfs or 78 mgd or more; and 10 percent of the time it is 600
cfs or 388 mgd or more (fig. 10). Usually the monthly flow is
highest in late summer or early fall, and the lowest in the fall or
spring seasons.
The total dissolved materials in the river water at Hillsborough
River State Park averaged (time weighted) about 150 ppm from
September 1956 to August 1958 and ranged from 50 to 218 ppm.
The total dissolved materials generally ranged from 52 to 90
percent calcium-plus-magnesium as calcium carbonate, 1 to 31
percent colored organic matter, and 4 to 17 percent sulfate. The
remaining dissolved materials were smaller amounts of various
other minerals. Mineral content for the 1957 water year ranged
from 56 to 201 ppm, as indicated by figure 11.

a

w. 1-a 1-
uO c _____________


,uuu II
HILLSBOROUGH RIVER
NEAR ZEPHYRHILLS, FLA.
(1940 TO 1958)

1,000

500 _





100-
10 --- --- ---k_ ___ __ ___ __ ___ __


10 20 30 40 50 60 70
PERCENT OF DAYS


80 90 100


Figure 10. Flow-duration curve of Hillsborough River near Zephyrhills.


1I






FLORIDA GEOLOGICAL SURVEY


--I I I II,
I:K -__-;- ^- -- p -






200



7 -1------ -


OCT NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT.
1956 1957
Figure 11. Mineral content and water temperature in Hillsborough River at
Hillsborough River State Park.

About half the time, the mineral content was 127 ppm or less
during the period September 1956 to September 1957. This value
is based upon specific conductance. Figure 12 shows the percent of
days the specific conductance was equal to or less than a given
value for the period of record stated above.
Figure 12, in combination with the formula given below, can
be used to estimate the mineral content of the Hillsborough River
near Tampa for any desired percentage of time:
Mineral content in ppm= (0.59) x (specific conductance). The
factor, 0.59, is the average of the ratios of mineral content to
specific conductance for composite samples during the period
September 1956 to August 1958.
Dissolved solids and water temperatures of the Hillsborough
River vary with the seasons. Water temperatures ranged from
630 F. in January to 900 F. during August the period 1956 tc
August 1958. The effect of rainfall upon streamflow is usually
accompanied by changes in both the amount and character of dis-
solved materials. Changes in the values for color, for instance,
are shown in figure 13.
For the period September 1956 to October 1957 the streamflow










320
330
310




190







U ISO
1
S30

20





130

190

70


0.01 05 I .2 .5 I 2 5 10 20 30 40 50 60 70 80 90 95 03 99 t.5 93 9 99.99
PERCENT OF DAYS

Figure 12. Percent of days specific conductance was equal to or less than
a given value, Hillsborough River at Hillsborough River State Park.

tended to increase in direct proportion to rainfall, whereas
calcium plus alkalinity as carbonate was nearly always present in
amounts greater than most of the other dissolved materials. A
trend of the chemical character of dissolved materials is indicated
in figure 14. Figure 15 shows a similar trend for the period from
October 1957 to October 1958.
The average concentration of dissolved materials (150 ppm)
appears when streamflow is about 129 mgd, or about 200 cfs
(fig. 16). The figure also shows the range of dissolved materials
for the period in relation to flow.
During the 6-year period, 1934-39, the average flow of the
Hillsborough River at Fowler Avenue was 350 mgd. It ranged
between 30 and 7,600 mgd. At this point, the river drains about
525 square miles of land.
During the 20-year period 1939-58, the average flow of the
Hillsborough River above the Tampa waterworks dam was 380
mgd (0.58 mgd per sq. mi.). The discharge over the dam has
never fallen below 31 mgd. This low rate occurred on June 11-17,
1945. In 1957 the average amount of water withdrawn from the
river by the Tampa water department was 23 mgd. Even during


REPORT OF INVESTIGATIONS NO. 25 31





















September 19516 to
September 1957


__ II1i III[I_______.1_____ e







32 FLORIDA GEOLOGICAL SURVEY


*~.~"7







1100 '
1000r /

AVERAGE STREAMFLOW (TIME WEIGHTED)
800 DURING COMPOSITE PERIOD


I i I / .. .-. .
I Goo L J










1956 1957
Figure 13. Color in relation to rainfall and flow of the Hisborough River at


00withdrawa The greatest flow, 3,800 mgd, was observed at the

00th Street bridge on September 7, 1933, prior to the failure of
















crested at 26.3 feet above mean sea level at the 40th Street bridge
o- L -















and at 15.2 feet at Nebraska Avenue. Flow of the magnitude
that caused this extreme in stage recurs at a frequency of a bout
once every 80 years. The frequency given is based on composite
1956 1957

Figure 13. Color in relation to rainfall and flow of the Hillsborough River at
Hillsborough River State Park (September 1956 to October 1957).

the 1945 period of extreme low flow, the water spilled over the
dam (wasted to the sea) amount to 135 percent of the 1957 average
withdrawal. The greatest flow, 3,800 mgd, was observed at the
40th Street bridge on September 7, 1933, prior to the failure of
the Tampa power dam.
During the flood of September 1933, the Hillsborough River
crested at 26.3 feet above mean sea level at the 40th Street bridge
and at 15.2 feet at Nebraska Avenue. Flow of the magnitude
that caused this extreme in stage recurs at a frequency of about
once every 80 years. The frequency given is based on composite
frequency curves.
At the mouth the average flow of the Hillsborough River
probably exceeds 450 mgd.
The chemical character of dissolved materials in Hillsborough
River water at the Tampa waterworks dam is shown in figures 17
and 18- ..







REPORT OF INVESTIGATIONS No. 25


0 0 -
> 0 z 0O


ALKALINTY AS 0 O ANIC
IuII CARBONATE MATERIALS
| I__ 8 P _A-M SILICA
. M WAGESIUM CHLORIDE
j7j CALCIUM SULFATE

J iL1--juLA L-i-i-L I ---l
I oi LwL, j
0 0 -
IX < -i
1957


Figure 14. Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (September 1956 to
October 1957).

During the period of the record from October 1956 to February
1957 and June to July 1957, rainfall on the county as indicated
by the Plant City station was below normal. Most of the remaining
record, September 1956, March to May 1957, and August to
September 1957, was during a period of above normal rainfall.
The time period used is not representative of a complete range in
rainfall but is considered representative of the range of departure
from normal rainfall.
Color intensity of the Hillsborough River water exceeds the
maximum amount recommended for municipal supplies most of
the time and requires treatment for its removal. This is most
commonly accomplished by adding alum to the water, which causes
the color to "floc" or separate from the solution in solid form. It
then can be allowed to settle out, or it can be filtered. The amount


0










FLORIDA GEOLOGICAL SURVEY


2CQ --



IBC -

3, -


I C





I0 -

40 L


SSLICA
FLUORIDE. NITRATE
5 PHOSPHATE
CHLORIDE
SULFATE
]ALKALINITY AS
CARBONATE
SODIUM a
POTASSIUM
MAGNESCIM
CALCIUMI


z I .-
-a < < 0


Figure 15. Chemical character of dissolved materials carried by Hillsborough
River water at Hillsborough River State Park (October 1957 to October 1958).


Figure 16. Dissolved materials in relation to flow, Hillsborough River at
Hillsborough River State Park (September 1956 to September 1957).







REPORT OF INVESTIGATIONS NO. 25


I80 -


160
140 -

120 -
100 -




,- :.
80 ii g 1




60l
40
40




Li z
1956


] SIUCA


A LKALINITY AS
CARBONATE
F] SODIUM s
POTASSIU1
MAGNESiUM





O-




I 0




i i 1 1 I


Figure 17. Chemical character of dissolved materials of Hillsborough River
at Tampa (September 1956 to August 1957).

of iron present in the river is very likely greater than that shown
by analysis, because iron precipitates out of solution during storage
of samples. Iron is removed by aeration and is removed usually
during the process of removing color. No other concentration of
dissolved material was observed to exceed the maximum amount
recommended by the U. S. Public Health Service.
Biological suitability, which is determined by the State Board
of Health, is not included as a part of this report.
Water from the Hillsborough River apparently would be suit-
able for agricultural purposes. The objections noted above for
municipal supplies do not affect the suitability of the water for
agricultural purposes. Boron content is unknown.
Industrial uses vary widely, and water quality requirements
vary almost as widely. Generally, the lesser the amount of
dissolved matter in water, the more suitable the water is for
industrial uses. The main exceptions to this rule are uses in which
the water is not actually used in the process; for example, as
cooling water in which practically the only considerations are
temperature, corrosive properties, and quantity of water available








FLORIDA GEOLOGICAL SURVEY


.0


260


220

200

too L

160

140 -






60

40

20
0


SILICA
> CHLOHIDE

ALKALINITY AS
SsuLFATE

CARBONATE
- SODIUM a
POTASSUIM
- UACNESIJM
CALCIUM


Figure 18. Chemical character of dissolved materials of Hillsborough River
at Tampa (October 1957 to October 1958).

to meet the industrial needs. Water supplies that contain the lower
dissolved solids concentrations are attractive to industries from an
economic standpoint.

BLACKWATER CREEK

Blackwater Creek, one of the major tributaries of the Hills-
borough River, flows into the river about a mile above the
Hillsborough River State Park. During the 7-year period, 1952-58,
the runoff from the 120 square miles of land in the Blackwater
Creek watershed averaged 63 mgd (0.52 mgd per sq. mi.). The
minimum flow was 0.45 mgd in May 1952. At the same time about
3 mgd was being withdrawn from the creek for irrigation purposes.
On only three occasions has flow dropped below 1.5 mgd; the
longest of these lasted 6 days.

FLINT CREEK

Flint Creek drains 71 square miles of land in Hillsborough
County. The creek proper begins at Lake Thonotosassa and flovwk


1 Y L_ Y I







REPORT OF INVESTIGATIONS No. 25


2,stward for half a mile, then northward for a mile, and then
westward for 11/2 miles to the river. During the 2-year period,
October 1956 to December 1958, the average flow of Flint Creek
at the outlet of Lake Thonotosassa was 42 mgd (0.70 mgd per
sq. mi.). Zero flow was recorded during 18 days in June 1958.
At the mouth the average flow of Flint Creek probably exceeds
50 mgd.
The average mineral content of the stream was about 74 ppm,
estimated from the discharge-mineral content relationship shown
in figure 19. The observed mineral content ranged from 46 to
92 ppm, and color intensity from 55 to 90 platinum-cobalt scale


0 10 20 30 40
MINERAL CONTENT


0S 60 70 80 90
IN PARTS PER MILLION


Figure 19. Mineral content in relation to flow, Flint Creek near Thonotosassa.


20O



ISO



160



140



LU. 120



100


NOVEMBER 1956
TO
OCTOBER 1957


___-- T -__




CALCIUM, MINEpIAL
MAGNESIUM, CONTENT
-- --- AND
ALKALINITY
IAS CARBONATE



~- -- -






FLORIDA GEOLOGICAL SURVEY


units. Calcium plus magnesium carbonate ranged from 34 to 45
percent of the mineral content.
The estimates are based on four chemical analysis of creek
water during November, December 1956, and May, October 1957,
and on streamflow measurements ranging from 3.9 to 119 mgd or
6.0 to 184 cfs.
LAKE THONTOSASSA
Lake Thonotosassa, with a surface area of about 830 acres,
is the largest lake in Hillsborough County. Stages of the lake
were recorded during the same period (1956-58) that data were
collected on Pemberton and Flint creeks. During this period the
elevation ranged from 34.85 feet to 36.52 feet above mean sea level,
less than 2 feet (fig. 20). The range in stage would have been ip
the order of 6 feet for the same period had not the timber dam
at the lake outlet been in place. This dam helps maintain a
relatively constant stage during periods of low inflow, yet it has
very little effect on stage when high inflow and high outflow exist.
During the period of no flow for Flint Creek in June 1958, the
flow of Pemberton Creek ranged from 1.2 to 5.0 mgd. The record
of this period indicates that the combined seepage and evaporation
losses from Lake Thonotosassa exceeded 4 mgd. Considering the
flow contributed to the lake by Baker Creek, it does not seem
unreasonable to surmise that the losses often exceed 6 mgd.

BAKER CREEK
Baker Creek is the largest tributary to Lake Thonotosassa.
It heads in the Lake Weeks and Lake Hooker area, 12 miles east
of Tampa, and flows northward through improved channels to Lake
Thonotosassa.

PEMBERTON CREEK
Pemberton Creek drains water from the land lying east of
Plant City. From the headwaters, it flows westward to Baker
Creek. The confluence is about a mile above the mouth of Baker
Creek. During the 2-year period, September 1956 to December
1958, the flow of Pemberton Creek was studied at a point 1.8
miles above its mouth. Here the creek drains approximately 24
square miles of land, and the average flow was 17 mgd (0.71
mgd per sq. mi.), The minimum flow was 0.8 mgd (October 1958).
The outflow of the Plant City sewage plant contributes substan-
tially to the flow of the creek during periods of prolonged drought.



























I {
LAKE THNNOTOSASSA















SEPT -JAN AUG SEPT OCT NOV DEC JAN FE MAR APR MA JUNE JULY AUG SEPT OCT NOV DEC--

SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC


Figure 20. Stage of Lake Thonotosassa.


42


- 40


36








32


30






FLORIDA GEOLOGICAL SURVEY


CYPRESS CREEK
Cypress Creek is another of the major tributaries of the
Hillsborough River. It rises in Big Cypress Swamp, 12 miles
north of Tampa. It then flows south-southeastward and joins the
Hillsborough River about 2 miles north of Temple Terrace. During
the period May 1956 to March 1959, the flow of Cypress Creek was
measured periodically at the Skipper Avenue bridge, 5 miles north-
northeast of Sulphur Springs. No flow existed when visits to the
creek were made between May 1956 and March 1957, November
and December 1957, and in June 1958. A large quantity of the
rainwater falling on the land drained through Cypress Creek
goes into storage in the lakes and swamps of the watershed. Some
of the water enters the ground and probably emerges again in
the spring lying in the lower part of the Hillsborough River basin,
or in one of the bays near Tampa.

KEENE LAKE
Keene Lake, with a surface area of about 30 acres, lies west of
Cypress Creek near Lutz. During the 7-year period, 1949-55, the
stage of the lake ranged between 60.90 feet (June 1955) and 63.30
feet above mean sea level (September and October 1953). Ninety
percent of the time the stage was 61.6 feet or more; 50 percent of
the time it was 62.7 feet or more; and 10 per cent of the time it was
62.9 feet or more (fig. 9). The range in stage of the lake is
minimized by the concrete control in the outlet channel at Sunset
Lane. Water discharged from the lake flows southward to Hanna
Lake.
HANNA LAKE

Hanna Lake lies west of Cypress Creek near Lutz. It has a
surface area of about 30 acres. During the 9-year period, 1947-55,
the stage of the lake ranged between 57.72 feet (June 1949) and
62.90 feet above mean sea level (August 1953). Ninety percent
of the time the stage was 59.7 feet or more; 50 percent of the
time it was 61.4 feet or more; and 10 percent of the time it was
61.7 feet or more (fig. 9). Water discharged from the lake flows
south-southeastward to Cypress Creek.
During the period, May 1946 to September 1951 the average
discharge was 1.7 mgd. Frequently, no water was discharged
from the lake. The maximum discharge was 30 mgd in Sep-
tember 1947. Some water from the lake is diverted westward
to Lake Stemper.






REPORT OF INVESTIGATIONS NO. 25


LAKE STEMPER

Lake Stemper lies west of Cypress Creek near Lutz. It has a
surface area of about 130 acres. During the 12 years, 1947-58, the
stage of the lake ranged between 58.68 feet (July 1949) and 61.98
feet above mean sea level (September 1953). Ninety percent of
the time the stage was 59.8 feet or more; 50 percent of the time
it was 61.2 feet or more; and 10 percent of the time it was 61.5
feet or more (fig. 9). Water discharged from the lake flows
southeastward to Cypress Creek.

SULPHUR SPRINGS

Sulphur Springs flows from a circular pool about 50 feet in
diameter over a control structure into an L-shaped run about 500
feet long and into the Hillsborough River. about 11/ miles below
the Tampa waterworks dam. During the period 1917-59,
measurements of discharge from the springs were made at
irregular intervals. The discharge ranged from 8.34 to 71.1 mgd,
and the average of all the measurements is 37 mgd. About one-
third of this water entered the ground in the Blue Sink area.
The time-weighted average concentration of the dissolved
materials in Sulphur Springs water was 660 ppm from September
1956 to October 1958. This average concentration was calculated
from 25 measurements taken at about 6-week intervals during the
period of record and includes measurements made during the
period of stage regulation. The mineral content ranged from 196
to 1,100 ppm.
The average and range in concentration includes concentrations
observed when the pool level was lowered for the test described
later in the Ground Water section. Excluding measurements made
during the period of stage regulation, the average concentration
of dissolved materials was about 540 ppm and the range in
concentration was about 196 to 634 ppm. Concentration of organic
materials usually was low; therefore, mineral content and con-
2entration of dissolved materials were nearly equal.
The concentration of dissolved materials fluctuates with the
3tage and discharge of the springs. This is indicated by figures
21 and 22. The wide range in concentration observed, and the
aven greater range that is indicated as being possible, suggests
hydraulic connection with aquifers lying at depths greater than
any aquifers that have been penetrated so far by wells in this
area.

















d





Io -
2-





,700 O160

2 600 5 1406
600 1240'

S ,. ,

S z400 zoo 00

g 300 so|




5100 40


1957


l'igure 21. Relationship of chloride, sulfate and specific conductance to stage
in Sulphur Springs (800-227-B).




















ELEVATION OP WATER SURFACE IN RELATION
TO DISSOLVED MATERIALS


TREND OF DISSOLVED MATERIALS IN ELATION TO FLOW

0 .


o o
, 0 0
0



0


I I I


200 300 400 B50 600 700
DISSOLVED MATERIALS IN PPM


0
0


- 0


-


I i i i I I I


B00 900 1000 1100


Figure 22. Dissolved materials of Sulphur Springs in relation to flow and
to stage.


00



o -
20
40 0


O


I I I I I I I I I I I I


I I






FLORIDA GEOLOGICAL SURVEY


The particular significance of this interpretation is with respect
to consideration of Sulphur Springs for use as a water supply. If
natural conditions are allowed to prevail, the water quality of
Sulphur Springs probably would fluctuate near the range observed.
If the stage of the spring is lowered to increase the yield from
Sulphur Springs, water quality can be expected to deteriorate
rapidly, and it is likely that the springs would yield water of
unsuitable quality.
BLUE SINK
The Blue Sink area drains approximately 26 square miles of
land in Hillsborough and Pasco counties. It is located in the
northern section of the city of Tampa west of Florida Avenue and
south of Fowler Avenue. The sink area is perforated with sink-
holes and has no surface drainage. Large quantities of surface
water flow into the sinks from a drainage ditch carrying water
from land lying north of Sulphur Springs. The average flow into
these sinks probably exceeds 9 mgd.
DRAINAGE DITCH
A drainage ditch carries water from an area of many lakes
situated north of Sulphur Springs to the Blue Sink area. During
the period, July 1946 to September 1956, the discharge of the
drainage ditch at Bearss Avenue was 4.4 mgd (0.37 mgd per sq.
mi.). The longest of the many periods of no flow lasted 7 months-
March to September 1956. In 1947, the discharge was as high as
69 mgd.
LAKE HOBBS
Lake Hobbs, which is located about half a mile northwest of
Lutz, has a surface area of approximately 65 acres. During the
12-year period, 1947-58, the stage of the lake ranged between
63.36 feet (May 1956) and 68.10 feet above mean sea level (Sep-
tember 1953). Ninety percent of the time the stage was 64.2
feet or more; 50 percent of the time it was 65.9 feet or more;
and 10 percent of the time it was 67.0 or more above mean sea
level (fig. 9). Water discharged from the lake flows southward
through a ditch to Cooper Lake.

COOPER LAKE
Cooper Lake is half a mile south of Lake Hobbs. It has a
surface area of about 85 acres. During the 10-year period, Sep-
tember 1946 to August 1956, the stage of the lake ranged between






REPORT OF INVESTIGATIONS No. 25


58.78 feet (June 1949) and 62.54 feet above mean sea level (Sep-
tember 1947). Ninety percent of the time the stage was 60.1
feet or more; 50 percent of the time it was 61.1 feet or more; and
10 percent of the time it was 61.7 feet or more above mean sea
level (fig. 9). Water discharged from the lake flows southward
through several lakes into Hutchins Lake.

HUTCHINS LAKE

Hutchins Lake lies 2 miles southwest of Lutz. It has a surface
area of about 20 acres. During the period, April 1946 to Septem-
ber 1952, the range in stage was greater than 2.7 feet. The
average discharge from the lake was 0.97 mgd (0.36 mgd per sq.
mi.). There was no discharge from the lake many times during
the period. The maximum discharge was 18 mgd in August 1947.

PLATT LAKE

Platt Lake is about 5 miles north of Sulphur Springs. It has
a surface area of about 65 acres when the stage is 49 feet above
mean sea level. Water from the lake flows through ditches to the
Blue Sink area., During the 10-year period, September 1946
to August 1956, the stage of the lake ranged between 46.92 feet
(June 1949) and 51.38 feet above mean sea level (September
1950). Ninty percent of the time it was 47.6 feet or more; 50
percent of the time it was 48.9 feet or more; and 10 percent of
the time it was 50 feet or more above mean sea level (fig 9).

PALM RIVER BASIN
PALM RIVER

Palm River drains 40 square miles of land in Hillsborough
County. It flows southwestward and empties into McKay Bay at
Tampa. The river proper is a continuation of Sixmile Creek and
is only about 2 miles in length. Land elevation in the basin ranges
from 135 feet on Kennedy Hill, northeast of Tampa, to sea level
at the river's mouth. Due south of Temple Terrace, there is a
valley in the ridge dividing the Hillsborough and Palm River
basins, through which water flowed into the Palm River basin
during the 1933 flood. Stage of the river fluctuates with the tide
in McKay Bay. The average net flow at the river's mouth probably
exceeds 45 mgd.






FLORIDA GEOLOGICAL SURVEY


SIXMILE CREEK

Sixmile Creek, the largest tributary to Palm River, rises in
a low flat prairie and flows 7 miles in a southerly direction to join
Palm River. In the upper reaches, the channel has been improved.
During periods of heavy rainfall, the creek overflows its banks
and inundates the prairie. In the upper portion of the basin the
gradient of the channel is 2.9 feet per mile (0.05 percent). Below
U. S. Highway 92, the gradient increases sharply to 8.8 feet.per
mile (0.17 percent) (fig. 23).
Much of the dry-season flow of Sixmile Creek comes from
springs in the upper reaches.
A study of the flow characteristics of Sixmile Creek was started
in 1956. During the 3 years of study, flow of the creek at the
State Highway 574 crossing (Broadway Avenue) did not fall
below 9 mgd.
Two tributaries join Sixmile Creek above State Highway 574
and give the stream pattern a fan-like appearance. The western-
most tributary drains an area of fairly flat, swampy land north of
Orient Park. It rises at Bellows Lake and flows southeastward
to join Sixmile Creek between Buffalo Avenue and State Highway
574. The channel is shallow and has an average slope of 16 feet
per mile (0.3 percent). The easternmost tributary drains an area


40

-J
30 2





Note: Data taken from
611 Si1)WLE OU.S.G.S. Topographic
604 Mops. z
o
I o 4
_J

0O
4 5 6 7 8 9
DISTANCE ABOVE MOUTH (MILES)


Figure 23. Profiles of streams in the Palm River basin.






REPORT OF INVESTIGATIONS NO. 25


of pasture and grove land. It heads in the boggy areas around
Mango Lake and flows westward to enter Sixmile Creek about
one-tenth of a mile below the Buffalo Avenue crossing. The channel
is shallow. It has a gradient of 8.1 feet per mile (0.15 percent).
On April 25, 1958, the flow of tributaries to Sixmile Creek was
measured to determine how much each contributed to the base
flow of Sixmile Creek. Also, the quantity of ground-water pickup
between measuring sites was determined. Six measurements of
flow were made above the regular gaging station on Sixmile Creek
and one was made at the station. These measurements are listed
as follows:


Stream
(Western branch)

Sixmile Creek


(Eastern branch)


Tributary to:
Sixmile Creek

Palm River

Sixmile Creek

Sixmile Creek

(Eastern branch)

(Eastern branch)


Sixmile Creek Palm River

Sixmile Creek above U. S. High'
water (79 percent) found in the
during periods of base flow. The


Location of
Measuring Site


Discharge
(cfs)


% mile west of U. S.
Hwy. 301 at Buffalo Ave.
At the U. S. Hwy. 92
bridge
At U. S. Hwy. 301, mile
south of U. S. Hwy. 92
At Faulkenburg Rd., % mile
north of State Hwy. 574
At Buffalo Ave., 2
miles west of Mango
At State Hwy. 574, % mile
east of U. S. Hwy. 301
At State Hwy. 574
(Broadway)


40.1

0


0.1

0.1

51.0


way 92 contributes most of the
creek at State Highway 574
western tributary to Sixmile


Creek carries 4 percent at Buffalo Avenue and the eastern branch
contributes another 4 percent at Faulkenburg Road. There is
six miles of stream channel between the three measuring points
mentioned above and the gaging station at State Highway 574.
A total of 6.8 cfs of flow was picked up by this reach of channel
for an average ground-water inflow of 0.7 mgd per mile of channel.
The dissolved materials in Sixmile Creek averaged (time
weighted) 228 ppm and ranged from 112 to 342 ppm from
September 1956 to September 1958. Figures are based on 17
water samples taken at about 6-week intervals during the period
.of measurement. Calcium plus magnesium carbonate ranged
from 47 to 64 percent of the mineral content; sulfate was about 22
to 35 percent. Color intensity ranged from 5 to 180 platinum-
cobalt scale units.






FLORIDA GEOLOGICAL SURVEY


The relation of dissolved materials to flow of the stream is
shown in figure 24.
Changes in streamflow usually are accompanied by changes in
both the amount and character of dissolved materials. Changes in
the amount and character of dissolved materials are indicated in
figures 25 and 26.

Springs: There are many springs in the headwaters of Sixmile
Creek. Only the springs known as Eureka Springs have been
measured. These springs are located 0.7 mile north of U. S. High-
way 92 and 0.8 mile east of U. S. Highway 301. The flow was 2.5
mgd on May 1, 1946, and 0.7 mgd on May 1, 1956.
The mineral content of Eureka Springs water was 213 ppm, as
shown by combined samples taken on May 1, 1956, and on July
31, 1958. There was no significant difference in the mineral content



220


6SO


40 1-


t0 0 -


100 120 140 160 180 200 22.0 240 260 280 300 320 340 360 380
DISSOLVED MATERIALS IN PPM

Figure 24. Dissolved materials in relation to flow, Sixmile :Creek at Tampa
(September 1956 to September 1958).


o80-


200 -

180







REPORT OF INVESTIGATIONS No. 25


2 N j
n 01 0 N D N N
6. 05 1 .5 2 4
-N ,9,6 I9-
u 1 L96 1957


Figure 25. Chemical character of dissolved materials carried
at Tampa (September 1956 to August 1957).


by Sixmile Creek


on these 2 days. Calcium plus magnesium carbonate was about
68 percent and sulfate was about 20 percent of the mineral
content.
Color intensity was 20 on May 1, 1956, and 4 on July 31, 1958
(platinum-cobalt scale units).

ALAFIA RIVER BASIN

ALAFIA RIVER

The Alafia River drains 410 square miles of land in Polk and
Hillsborough counties. Two hundred and forty-five square miles
of this land is in Hillsborough County. The river begins at the
confluence of the North, and South Prongs, about 4 miles east of
the town of Lithia, flows westward, and empties into Tampa Bay
near Riverview (fig. 7). Land elevations in the basin range from
sea level near the mouth to 250 feet above mean sea level in the


3GO

2 320

280

S240







FLORIDA GEOLOGICAL SURVEY


S N N AS,
0 4 ~
o z S
1957


1958


Figure 26. Chemical character of dissolved materials carried by Sixmile Creek
at Tampa (October 1957 to September 1958).



eastern part. There are few natural lakes in the basin; however,
open-pit phosphate mining operations have created many artificial
ones. Soils in the basin are sandy, and the land is used principally
for raising cattle and citrus. The population density is low.
Throughout most of its length the Alafia River flows through
a shallow, wooded valley and in a well defined channel. Several
large tributaries, many small ones, and many springs flow into it.
The lower reach of the river rises and falls with tides in Tampa
Bay and, when the flow of the river is low, tidal fluctuations are
discernible as far as 10 miles upstream from the mouth. Channel
gradients are shown in figure 27.
At Lithia, the average flow of the Alafia River is about 220
mgd. The maximum flow was about 12 bgd on September 7, 1933,
and the minimum was about 41/ mgd on June 6, 1945. Fifty
percent of the time the flow is 160 cfs or 103 mgd or more (fig.
28). Usually, the average monthly flow is highest in September and
lowest in May.


440o-

400-


a 320

280 L
- 240


SILICA
FLUOROE, NITRATE
A PHOSPHATE
s CHLORIDE
SULFATE
A LKALINITY" AS
CARBONATE
P SODIUM
POTASSIUM

El CALCIIJ.R






REPORT OF INVESTIGATIONS NO. 25


15 20 25
110

100
90 90


70 70
60 -OI 60

50
40


SU. S. G.S. Topographic 0
I/

1 0 --O p-. __Maps._


90 o -
0 -- 10

0
15 20 25 30 35 40 45
DISTANCE ABOVE MOUTH (MILES)
Figure 27. Profiles of streams in the Alafia River basin.

On September 7, 1933, the stage of the Alafia River at Lithia
was 35.5 feet above mean sea level. Flow of the magnitude that
caused this extreme in stage recurs at a frequency of about once
every 80 years. The frequency given is based on composite fre-
quency curves.
At the mouth, the average flow of the Alafia River probably
exceeds 300 mgd.
The average concentration of dissolved materials (time
weighted) in the Alafia River at Lithia was 292 ppm from October
1957 to September 1958. Dissolved materials ranged from 116 to
658 ppm during the same period. Dissolved, materials were about
87 to 100 percent mineral content. Constituents reach high
concentrations and vary considerably; for instance, sulfate con-
centration ranged from 33 to 222 ppm; phosphate, from 9 to 170
ppm; calcium, from 18 to 117 ppm; and silica, from 15 to 77 ppm;
alkalinity as carbonate was essentially absent. Color intensity
ranged from about 15 to 150 (platinum-cobalt scale units).
Industrial waste, materials discharged into the stream mask







FLORIDA GEOLOGICAL SURVEY


10,000


1 5p



S5.

J





1
I
E

)
J
>
C

>



13


0 10 20 30 40 50 60 70 80
PERCENT OF DAYS
Figure 28. Flow-duration curve of Alafia River at Lithia.


90 100


the presence of naturally occurring concentrations of dissolved
materials. The preceding estimates of dissolved materials in Alafia
River water near Lithia are not representative of upstream
locations on the Alafia River or its tributaries.
High but variable concentrations of wastes at different locations
upstream from Lithia were indicated by specific conductance, by
color intensity, and by fluoride content of water samples taken
from the Alafia River near Lithia; the South Prong Alafia River
2.5 miles east of Pinecrest; the Alafia River 2.5 miles southeast
of Bloomingdale; the North Prong Alafia River 0.5 mile north of


oo
ALAFIA RIVER
AT LITHIA, FLA.
(1934 TO 1958)


0 0

0

00 -






50
2oo 30 40- -0-6- -- --0



5,^=: : := = =


I







REPORT OF INVESTIGATIONS NO. 25


Keysville; and Fishhawk Creek 1 mile east of Boyette. These
samples were collected during the period January 27-29, 1959.
(See separate data report.)
Mineral content of the Alafia River at Lithia for the period
October 1957 to September 1958 is indicated in figure 29. About
50 percent of the time the specific conductance was equal to or
less than 340 micromhos. The mineral content, in parts per million,
was about 77 percent of the specific conductance in micromhos;
therefore, half the time the mineral content from October 1957
to September 1958 was equal to or less than 262 ppm. Figure 30
shows the percent of days that the specific conductance was equal
to or less than a given value for the 1-year period ending September
1958.
Figure 30 can be used to estimate the mineral content for any
desired percentage of time during the period of record according
to the following relationship:


90 --





'0
so -- -- -- -- -- -- -- -7 ^*^ /'A ^ -



50 0-



550 O ---V ~ JM A AJ U
500




350


250
20 01-- 1 4 fIIA'IA J V' 11 1 A

50
100

50 OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT


Figure 29. Mineral content and water temperature in Alafia River at Lithia
(.October 1957 to September 1958).


CL

:
z
0
0c






54 FLORIDA GEOLOGICAL SURVEY







300 October 19 to





September 1957
700 VI

too-- F-


3400 I^-- ^-






0.01 .05 2 .5 2 5 10 0 3040 506070 80 s g5 go9999.5 99.9 99.99
PERCENT OF DAYS
Figure 30. Percent of days specific conductance was equal to or less than a
given value, Alafia River at Lithia.

Mineral content in ppm= (0.77) x (specific conductance).
The factor, 0.77, is the average of the ratios of mineral content to
specific conductance for composite samples during the period of
record.
Figures 31, 32, 33, and 34 show the percent of days that sulfate,
phosphate, fluoride, and pH values, respectively, were equal to or
less than a given value.
The chemical character of the dissolved materials is shown in
figures 35 and 36. The water temperatures in the stream varied
from 450F. in February to 850F. in June (fig. 29).
According to U. S. Public Health standards, the water quality
of the Alafia River was unsuitable for municipal uses during the
period October 1, 1957 to September 30, 1958. Color intensity
exceeded that desired most of the time. Fluoride concentrations
exceeded the recommended maximum all the time, with concentra-
tions in the stream reaching 17 ppm. Phosphate concentrations
were observed up to 170 ppm. Fluoride, phosphate, and other
materials enter the stream at various locations as industrial waste
products. Water from the Alafia River would be difficult to treat
economically for municipal use.
Biological suitability for use as municipal supplies is not
included as a part of this report.
Regular use of Alafia River water for stock watering would







REPORT OF INVESTIGATIONS No. 25


0.01 .05 .1


.2 .5 1


5 to 20 30 40 50 40 70 80 90 95 98 99 9
PERCENT OF DAYS


Figure 31. Percent of days sulfate concentration was equal to or less than
a given value, Alafia River at Lithia.





lt0 -- -- ---------- -- -- -- ----^ --



2 13---------------------------------------^----

too 1------ -------------------
90





1 50----------












001 .05 -.2 .5 -0 203040-6070 90 95 999. 9 99.99
OItober 1957 to





PERCENT OF DAYS

Figure 32. Percent of days phosphate concentration was equal to or less than
a given value, Alafia River at Lithia.


190 V_ -00







30 ------ ------- ---
9O------1- --- --/-~- -








October 1957 to
SSeptember 1959
o ___ ---__ --- ---- --------------- ___


--







FLORIDA GEOLOGICAL SURVEY


.5 1 2 3 to 20 30 40 50 60 70
PERCENT OF DAYS


80 90 95 s9 99 99.5 99.9 9.99


Figure 33. Percent of days fluoride concentration was equal to or less than
a given value, Alafia River at Lithia.

result in mottled teeth and other pathological changes in the
animals because of the fluoride content (California State Water
Pollution Control Board, 1952, p. 256). Continued use would result
in increasing economic loss to livestock producers along the river.
Extensive use of Alafia River waters for irrigation could result


9.8 1 1 1 1 1 1 1 1 1 --

.9 .--


6.4 -0 ,- 0
; ,. --- ;- -- -- -- - -- - ---




c.t t o
f ._t--_____ ------- -
S *a ---- - --~ --- ---

.? I O io
s- September 1957
5.a A I I I I


91 99 99.5 99.9 99.9s


Figure 34. Percent of days pH was equal to or less than a given value, Alafia i
River at Lithia.


2









9J


25-

to- -0 - - ----
-~-T









:^ L 4OctbTr 1957 to
SS-pLLmb 1958


0.01 .05 .2


0.01 .05 .1 2 .5 1 3 10 20 30 40 50 60 70 10 90 95
PERCENT OF DAYS







REPORT OF INVESTIGATIONS NO. 25


Q sucA
FL.UORIDr. MTBAME
8 PHOSPHATE
600 CHLORIDE
55 SULFATE
550 ALALIiTYAS
500 P T.u
450 MAGNESIUM
CALCIUM
S400

350
S300

250

200








W z 0 o
1956 1957


Figure 35. Chemical' character of dissolved materials carried by the Alafia
River at Lithia (September 1956 to October 1957).


in contamination of ground-water supplies hydraulically connected
downgradient from the irrigated land. Shallow ground water is
used for domestic supplies within the basin and would be vulnerable
to contamination by fluoride and phosphate.
The Alafia River water was the least suitable of all river water
in Hillsborough County for most uses because of the range in
concentration of the dissolved materials.


NORTH PRONG ALAFIA RIVER


The North Prong Alafia River drains about 175 square miles
of land southeast of Plant City. Fifty square miles of the basin
area is in Hillsborough County, and the remainder lies in Polk
County. Stream channels in the area run mostly through wide
marshy or swampy areas and are not well defined. There are
several springs in the basin.
The average flow of the North Prong is about 110 mgd.








FLORIDA GEOLOGICAL SURVEY


E SILICA
F rOSPHtATE
SFLUOTDE
F IT.ATE


JLFATE
SALK"ALINITY -S
.CANDUCNATE
-SL"IM a
POTASSIUM
CAL-NESIUM

CALCIU.


I i


2,5


0
PER MILLION


U


19MT 1958

Figure 36. Chemical character of dissolved materials carried by the Alafia
River at Lithia (October 1957 to September 1958).


t I






REPORT OF INVESTIGATIONS NO. 25


SOUTH PRONG ALAFIA RIVER

The South Prong Alafia River drains about 120 square miles
of land, 70 square miles of which is in Hillsborough County. The
South Prong begins near Hookers Prairie (Polk County), flows
westward for 20 miles, northward for 14 miles, and joins the North
Prong. Average flow at the junction is probably 100 mgd.

TURKEY CREEK

Turkey Creek drains 40 square miles of land in the area south-
east of Plant City. It flows into the Alafia River 2 miles upstream
from Lithia Springs. There are numerous phosphate pits in the
basin. Average flow is about 25 mgd.

FISHHAWK CREEK

Fishhawk Creek drains avout 30 square miles of land lying
south of Lithia Springs. It flows northward and into the Alafia
River 2 miles south of the town of Riverview. Average flow is
,about 20 mgd.

OTHER STREAMS

Bell Creek drains 15 square miles lying south of the Alafia
River. It flows northward and enters the Alafia River about 5
miles downstream from Lithia Springs and 9 miles upstream from
the mouth. Its average flow is about 7 mgd. Rice Creek, draining
an area of about 5 square miles south of the river, flows in 5
miles upstream from the mouth. Average flow is probably more
than 2 mgd.
Numerous lesser tributaries flow into the Alafia River through-
out its course. The combined area that they drain is approximately
25 square miles and on the average they contribute about 20 mgd
to the river.

LITHIA SPRINGS

Two springs, located on the south bank of the Alafia River
bout 19 miles upstream from the mouth and about 2 miles down-
stream from Turkey Creek, are known collectively as Lithia
springs. One of the springs forms a pool about 50 feet across. It
is connected to the river by a run about 200 feet long. The other
spring forms a pool 100 feet across. It is connected to the river






FLORIDA GEOLOGICAL SURVEY


by a run about 600 feet long. The average combined flow of the
springs probably exceeds 30 mgd. The flow of the springs was
measured 17 times between 1934 and 1938. The highest combined
flow measured was 46.7 mgd; the lowest, 25.9 mgd.
On the basis of five samples collected from Lithia Springs
during the period from November 1957 to June 1958, the dissolved
materials averaged about 268 ppm. The dissolved materials in the
water from each spring opening are similar in both quantity and
chemical character. Nearly 100 percent of the dissolved materials
is mineral content. Calcium plus magnesium plus alkalinity as
carbonate was about 51 percent, and sulfate was about 30 percent
of the mineral matter. Color intensity was low, being in the range
from zero to five platinum-cobalt scale units. These quantities
compare very favorably with the dissolved materials and the
chemical character of Lithia Springs on July 19, 1923, and again
on April 30, 1946.

BUCKHORN SPRING

Buckhorn Spring flows into Buckhorn Creek which in turn
flows into the Alafia River about 8 miles above the mouth. The
spring is 3 miles northeast of Riverview and half a mile north
of the Alafia River. It forms a pool about 30 feet across and
empties directly into Buckhorn Creek. Its average flow is
approximately 8 mgd. The U. S. Phosphoric Products Company
pumps from the spring to supply a plant at Gibsonton.
Mineral content on April 26, 1956, was 310 ppm. Calcium plus
magnesium plus alkalinity as carbonate was 44 percent, and
sulfate was 22 percent of the mineral content. Color intensity
was 20 platinum-cobalt scale units.


BULLFROG CREEK BASIN
BULLFROG CREEK

Bullfrog Creek drains 40 square miles of land in southern
Hillsborough County. Headwaters of the creek are just north of
Wimauma. From there the flow is westward, then northward, then
westward and into Hillsborough Bay about a mile south of the
Alafia River. The stream drains an area of sandy land dotted
with ponds and sinkholes. The largest tributary is Little Bullfrog
Creek. Land elevations in the basin range from sea level at the
bay to 140 feet above sea level on ridges in the upper reaches.






REPORT OF INVESTIGATIONS No. 25 61

Bullfrog Creek has a fairly well defined channel. The channel
gradient is fairly steep (13 feet per mile) in the upper part and
is moderate in the central part (5 feet per mile). In the lower
part the gradient is nearly flat (1 foot per mile). Channel
gradients are shown in figure 37.
The average flow of the creek at Big Bend Road (drainage
area: 29 sq. mi.) is about 18 mgd. However, wide variations in
flow occur. From October 1956 to October 1958, the highest flow
was 1.4 bgd. Several times during the 2-year period the flow
ceased. During June 1957, there was zero flow for 12 consecutive
days. More than 20 percent of the time the flow was less than 1
mgd.
At the mouth of Bullfrog Creek, water flows in and out because
of fluctuations in the level of the bay; however, the net flow is into
the bay. The average net flow at this point probably exceeds 30
mgd.
The dissolved materials in Bullfrog Creek near Wimauma
averaged 36 ppm and ranged from about 25 to 49 ppm, from
September 1956 to September 1958. The values are based on 16
water samples taken at about 6-week intervals during the period.
Color intensity ranged from about 65 to 200 platinum-cobalt scale
units and was often a large percentage of the dissolved materials.


12 13 14 15
100
90 90

80 80
7010-------u 70 "

60 60
6-7 B 17 IsO
S 50 50
? 40 40 W

12 13 14 15 16 Z
20
Note: Data token from
to U.S. G.S. Topographic .

6 7 8 9 10o II1
DISTANCE ABOVE MOUTH (MILES)
Figure 37. Profiles of streams in the Bullfrog Creek basin.






FLORIDA GEOLOGICAL SURVEY


The remainder of the dissolved materials was mineral content with
chloride, sodium, bicarbonate, silica, calcium, and sulfate in small
amounts; chloride was present in greatest quantity most of the
time, followed closely by most of the other minerals.
Large changes in streamflow are accompanied by irregular
changes of small magnitude in the dissolved materials. The water
contacts only the insoluble sand deposits, which overlie the im-
permeable Hawthorn formation and does not contact soluble
materials. The wide range in color indicates contact with vegetable
matter on the surface or at shallow depths.

LITTLE BULLFROG CREEK

Little Bullfrog Creek, which drains about 9 square miles of
land south of Riverview, flows into Bullfrog Creek a mile south
of Big Bend Road. It has a well defined channel with a gradient
of about 11 feet per mile. At the mouth, the estimated average
flow is 7 mgd.

LITTLE MANATEE RIVER BASIN
LITTLE MANATEE RIVER

The Little Manatee River, about 40 miles long, heads in a
swampy area east of Fort Lonesome, in southeastern Hillsborough
County, flows westward, and empties into Tampa Bay near the
town of Ruskin. The stream drains 150 square miles of land in
southern Hillsborough County and 75 square miles of land in
northern Manatee County. At its source the channel is about 100
feet above sea level and has a fairly steep gradient, particularly in
its upper reaches. (fig. 38). In general, the channel is well defined
and has steep, sandy banks. Tributaries to the Little Manatee
River enter from both sides at fairly regular intervals. In the
lower reach of the river the stage rises and falls with the tide in
Tampa Bay and when flow is low, tidal fluctuations are discernible
as much as 15 miles upstream from the mouth.
Lake Wimauma is the largest of the several lakes in the river
basin. It has a surface area of about 130 acres.
For the 19-year period from 1940 to 1958, the average discharge
of the Little Manatee River at U. S. Highway 301 was 115 mgd.
Flow ranged from a minimum of 0.8 mgd in June 1945 to a maxi-
mum of 6,110 mgd in June 1945. About 90 percent of the time the
flow was 12 cfs or 8 mgd or more. Fifty percent of the time flow
was 48 cfs or 31 mgd or more, and 10 percent of the time it was






REPORT OF INVESTIGATIONS No. 25 63



120
ZII
110oo
I / 100

90



70 O
I0 40 .

SI60

S5 050
0C z

Dc N 35 |
4 3 Uull t
oNote:. Daotoa- ken from
-- 20 U.S.G.S. Topographic




15 20 25
DISTANCE ABOVE MOUTH (MILES)
Figure 38. Profiles of streams in the Little Manatee River basin.



480 cfs or 310 mgd or more (fig. 39). Usually the average monthly
flow is lowest in the spring and highest in the summer.
The dissolved materials carried by the Little Manatee River
averaged 57 ppm (time-weighted) from October 1956 to September
1957 and ranged from 36 to 88 ppm. These materials were about
I to 49 percent organic materials. The remainder of the dissolved
material was mineral content with sodium chloride, bicarbonate,
Silica, calcium, and sulfate in small amounts, each predominating at
S'different times. Mineral content for the same period ranged from
:0 to 55 ppm as indicated by figure 40.
About 50 percent of the time, the specific conductance was equal
io or less than 63 micromhos. The mineral content was about 62
percentt of the specific conductance; therefore, half the time the
mineral content from October 1956 to September 1957 was equal






FLORIDA GEOLOGICAL SURVEY


500





10 -0--- -

50





-..7-

t--- ---- -
IO \=^ -- ------ =






t -- -- -- -- -- -- -- -- -- --


0 10 20 30 40 50 60 70
PERCENT OF DAYS


80 90 100


Figure 39. Flow-duration curve of Little Manatee River near Wimauma.


to or less than 40 ppm. Figure 41 shows the percent of days the
specific conductance was equal to or less than a given value for the
period stated.
Figure 41 can be used to estimate the mineral content for any
desired percentage of days according to the following relationship:
Mineral content in ppm= (0.62) x (specific conductance). The
factor, 0.62, is the average of the ratios of mineral content to
specific conductance for composite samples collected during the
period of record.


b.I


bJ

x

tr 1,000
0


LITTLE MANATEE RIVER
NEAR WIMAUMA, FLA.
(1939 TO 1958)


%00I 1 1 1





SPECIFIC CONUUUTANCE IN MICROMHOS AT 25* C.


C+
-4C
1C.







(CD
C0~
hCD








Pp
C
g'l








c+









N
. D


0 (9

p0D
p^


N


0








ch
Ip


C1





OCD


N


B-A
soa






(D
CD'

CD
N-B


MINERAL CONTENT PPM


OCT


NOV


DEC

JAN


0

0

I-f
z



0

0
~i2
z
P






66 FLORIDA GEOLOGICAL SURVEY

The color intensity during the low rainfall period from Novem-
ber 1956 to January 1957 was stable at about 75 units. During
the early part of the rainy season, February to April, much of the
soluble organic material was leached from the vegetation and the
color intensity increased (fig. 42). Greater flow during the latter
part of the rainy season resulted in less color intensity.
The effect of rainfall upon streamflow is usually accompanied
by changes in both the amount and character of dissolved materials.
Chemical character of dissolved materials is exhibited in figures
43 and 44.


1200
I 100
1000
900
0oo
?00o


600
400
3CC
200
100O

0


0 0 0 0 .
Q o 0 I IL
0 X 0 0 4 a < 4 Id
1956 1957

Figure 42. Color in relation to rainfall and flow of Little Manatee River
near Wimauma (October 1956 to September 1957).


T i

C-O '


/- l

SI I I I
op \ /
SCOLO IX x X x X x X






REPORT OF INVESTIGATIONS No. 25


0 0 -
o 2 0 U. W N N N N 1
1956 2q57
Figure 43. Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1956 to September 1957).

Water temperatures in the stream varied from 510 F. in No-
vember to 870 F. in June and July.
During the period October through December 1957, a relatively
sharp increase in mineral content, from 24 to 181 ppm, occurred.
Simultaneously color intensity decreased from 140 to 27 (platinum-
cobalt scale units) and calcium plus magnesium plus alkalinity as
carbonate increased from about 6 to 132:ppm. The sulfate increased
from 2 to 20 ppm. These changes resulted from a combination of
below-normal rainfall and heavy pumping of ground water for
irrigation in the headwaters of the basin. Part of the water used







FLORIDA GEOLOGICAL SURVEY


40
30
120

Ito


90 -


70
6o -

30
40-
30


*LUORIE., NITRATE:
HSPHATE
SSLICA
RD CHLORIDE
S0 SULFATE
A LKALINITY AS
CARBONATE
-- SODIUM a
POTASSIUM
M MAGNESIUM
C CALC.IM


1957


Figure 44. Chemical character of dissolved materials carried by the Little
Manatee River near Wimauma (October 1957 to October 1958).


for irrigation infiltrates the soil and probably reaches the water
table. It moves through the sand deposits and discharges into the
streams of the basin.
The chemical character and concentration of dissolved materials
in Little Manatee River may be explained largely by the interaction
of rainfall upon the surface sand deposits. The sand deposits rest
upon the relatively impermeable Hawthorn formation. The rain
quickly permeates the sand. Downward and upward movement
through the underlying Hawthorn formation is much slower.
Therefore, rainwater tends to move over the ground or down-
gradient within the sands. The sands are only slightly soluble, and
the length of time in contact is relatively short, thus limiting the
mineral content. The range in color intensity indicates contact
with vegetable matter on the ground surface or at shallow depths.
The Little Manatee River water is suitable for municipal use
with respect to dissolved materials except for color intensity. Most
of the time, color intensity exceeds the recommended amount. Iron


I, I I II ... ....i


1958






REPORT OF INVESTIGATIONS NO. 25


concentrations probably are greater than those indicated. Bac-
teriological suitability is not included as a part of this report.
Water from the Little Manatee River apparently is suitable
for agricultural uses; this assumption is qualified to the extent
that the boron content of the water is not known.
Little Manatee River water is more suitable for industrial uses
than that from other major streams in the county. The dissolved
material concentrations in this stream are relatively low compared
to the other major streams in the county, except for color.
At the mouth, the average flow of the Little Manatee River
probably exceeds 180 mgd.
The Little Manatee River above its confluence with Howard
Prairie Branch drains 35 square miles of land of the eastern part
of the river basin. About 31 square miles of this land is in Hills-
borough County, and the remaining 4 square miles is in Manatee
County. Alderman Creek brings water collected from Manatee
County into Hillsborough County. This creek joins the Little
Manatee River 34 miles above the mouth. The average flow of
the river above Howard Prairie Branch is probably 30 mgd.

HOWARD PRAIRIE BRANCH

Howard Prairie Branch drains an area of about 13 square miles
in Hillsborough County and 5 square miles in Manatee County.
Water collected in Manatee County is channeled northward into
Hillsborough County. Three lakes form part of the Howard Prairie
Branch channel. The largest and easternmost lake is about 60 acres
in area at a stage of 73 feet above mean sea level. At its confluence
with the Little Manatee River, 29 miles upstream from Tampa Bay,
Howard Prairie Branch contributed an average of 14 mgd to the
river.
PIERCE BRANCH

Pierce Branch drains 10 square miles of land in Hillsborough
County. This stream flows southward and enters the Little Manatee
River at a point about 27 miles above the mouth. The average
flow of Pierce Branch is probably 8 mgd.

CARLTON BRANCH

Carlton Branch drains 10 square miles of land in Hillsborough
County. This stream, like Pierce Branch, flows southward. It
enters the Little Manatee River about 26 miles above the river's
mouth. The average flow of Carlton Branch is about 8 mgd.






FLORIDA GEOLOGICAL SURVEY


SOUTH FORK LITTLE MANATEE RIVER

The largest tributary to the Little Manatee River is South Fork
Little Manatee River. It drains approximately 40 square miles of
land in Manatee and 1 square mile in Hillsborough County. The
stream flows northwestward into Hillsborough County, flowing
at an average rate of 30 mgd. The South Fork Little Manatee
River flows into the Little Manatee River about 21 miles above
the river's mouth and 2 miles above the point where the Little
Manatee River flows across the Hillsborough-Manatee county
line into Manatee County.

OTHER STREAMS

Numerous other streams drain the remaining 110 square miles
of land not covered in the discussion of tributaries to the Little
Manatee River. These streams contribute on the average about
90 mgd to the river or about one-half the flow at the mouth.

PEACE RIVER BASIN

The Peace River drains about 4 square miles of land in the
southeastern corner of Hillsborough County. The river flows
southward to Charlotte Harbor and the Gulf of Mexico. The area
in Hillsborough County contributing water to the Peace River is
mainly swampland that lies 130 to 145 feet above the sea.

GROUND WATER

Part of the rain that falls on the earth moves downward
through the ground to the zone of saturation to become ground
water. The ground water then moves laterally along the hydraulic
gradient to discharge points such as springs, wells, or the sea. The
materials through which the water moves in usable quantities is
known as an aquifer. Where water in the aquifer is at atmospheric
pressure and is free to rise, the water occurs under nonartesian
conditions and the water surface is referred to as the water table.
Where relatively impermeable beds restrict the vertical movement
of water in a completely saturated aquifer, the water occurs under
artesian conditions, and the surface described by the elevations to
which water will rise in wells tapping the aquifer is referred to as
the piezometric surface. Artesian conditions exist when the water
is under greater than atmospheric pressure or when the water






REPORT OF INVESTIGATIONS NO. 25


will rise above the top of the aquifer where tapped. Where the
piezometric surface is lower than the water table, the water may
move downward from the monartesian aquifer into the artesian
aquifer. Where the water table is lower than the piezometic sur-
face, water may move upward from the artesian aquifer into the
nonartesian aquifer or to flowing wells and springs. Ground
water in Hillsborough County occurs under both artesian and
nonartesian conditions.

WATER-TABLE AQUIFER

The undifferentiated surface sands and clays generally contain
water under water-table conditions in Hillsborough County, but
artesian conditions may occur locally. The water in the aquifer is
derived from local rainfall, and the water table is only a few feet
below the ground surface.
Wells deriving water from the sand are constructed by driving
a screened well point into the saturated zone or, on the high
"prairies," by sinking a pipe to the top of a layer of hardpan and
chiselling a hole through the handpan into the underlying sand.
The well is then pumped until the water is clear. Drive-point wells
are generally less than 20 feet deep and yield about 5 gpm.
The wells developed below the hardpan are usually from 8 to
16 feet deep and may yield more than 200 gpm where the hardpan
is sufficiently thick and strong to allow development of large cavities
under it.
Generally water is not available in desirable quality or quantity
from the water-table aquifer, and it is not a very important source
of supply in the county.

SHALLOW ARTESIAN AQUIFER

Wells developed in the sand and limestone beds of the Hawthorn
formation in the southern half of the county yield up to about
500 gpm of water of relatively poor quality. The advantages
of developing wells in this aquifer are that shallower wells and
less expensive pumps are required if only small to moderate yields
of water are needed. The saving effected could offset the advan-
tage of having better quality water from the deeper aquifers. The
aquifer in the Hawthorn formation, though important in Polk
County, is of minor importance throughout the small area of
Hillsborough County in which it occurs.






FLORIDA GEOLOGICAL SURVEY


PRINCIPAL ARTESIAN AQUIFER

The principal artesian aquifer includes the units described by
Stringfield (1936, p. 124-128) and the Floridian aquifer of Parker
(1955, p. 188-189). Parker (op. cit.) includes the Lake City lime-
stone, Tampa limestone and, where hydrologically connected, the
Hawthorn formation in the Floridan aquifer.
The physical limits of the aquifer should be set at hydrologic
boundaries. In Hillsborough County, there is no evidence of a
hydrologic boundary at the base of the Lake City limestone. In
addition, rotary drilling in the county has resulted in loss of mud
circulation throughout the older Tertiary formations (i.e., Oldsmar
and Cedar Keys limestones) and possibly the upper part of the
Lawson limestone of Cretaceous age. Loss of circulation indicates
the presence of cavities that, in all probability, are the result of
solution by ground water. Therefore, the entire Tertiary system
from the base of the Hawthorn formation to the top of the Gulf
series (as used by the Florida Geological Survey) of Cretaceous
age is included in the principal artesian aquifer of this report. The
general occurrence of cavities in the Eocene rocks and the inferred
presence of similar cavities in the Oldsmar and Cedar Keys lime-
stones indicate ground-water movement to at least that depth.
Limestone, more or less dolomitized, is the dominant lithologic
component of the aquifer. Zones of high permeability are
distributed erratically through the aquifer. These zones have not
been traced over great distances. It is known from examination
of caves in other areas that most horizontal water courses in
limestone end in vertical openings that intersect other horizontal
cavities at different levels. Similar conditions are assumed to be
responsible for the hydrologic continuity observed in the principal
artesian aquifer in Hillsborough County.
The hydraulic systems just described are limited in vertical
extent by layers of rocks of low permeability. The rocks of the
upper part of the Ocala group tend to restrict this system. The
Tampa and Suwannee limestones, which are a hydrologic unit,
comprise the aquifer above the Ocala. The few available data
indicate that the formations underlying the Ocala group to the
greatest depth commonly penetrated by water wells tend to form
another gross hydrologic unit. The two systems are connected
hydraulically by solution openings along structural planes that
probably are faults. The vertical permeability of these openings
is sufficient to allow approximate equilibrium to obtain between






REPORT OF INVESTIGATIONS NO. 25


the two systems when the time of interchange of water is great
and the amount of water interchanged is small. Where either
system is stressed by a local discharge through a large spring or
well, the vertical movement of water is relatively small and the
two systems behave as separate aquifers. Thus, throughout most
of the county the total limestone section is essentially a hydrologic
unit, but wherever either system is stressed by large volumes of
discharge the Tampa and Suwannee limestones act as an aquifer,
separate from the limestones below the Ocala group.
Several thousand gallons per minute can be pumped from
any of the several zones in the aquifer. The specific capacity
of the well depends on the size and continuity of the cavities pene-
trated by the well.
Sulphur Springs (801-227-B) flows an average of about 37
mgd. Based on chemical analyses of water from the spring as
compared with water from well 801-227-3, about 90 percent of
the water, or 33 mgd, is of good chemical quality derived from
the Tampa and Suwannee limestones. The remaining 4 mgd
consists of highly mineralized water from below the Ocala group.
The proportions of minerals in the spring water are different from
those in sea water, indicating that the concentration and chemical
character of the water do not reflect salt-water intrusion from
Tampa Bay. Instead, the water probably is diluted connate water.
The connate water-is derived from older rocks that have not been
flushed by fresh water as have the more recent rocks near the
surface. Concentrations of chloride of more than 69,000 ppm
(Black and Brown, 1953) are known to occur in the older rocks
in Florida. These rocks are rich in gypsum and anhydrite from
which sulfate could be dissolved, giving rise to the type of water
occurring in well 801-227-3.
The movement of water in the Tampa and Suwannee limestones
was traced by introducing 8 pounds of sodium fluorescein into a
sinkhole about 1,000 feet northwest of Blue Sink. During the test,
the dye followed a sharply angular and narrow course correspond-
ing to the trends of regional structures. The dye moved one-
half mile southwest, then 11/2 miles southeast from Blue Sink (803-
227-A), then southwestward to 801-226-A, and to Sulphur Springs.
A number of randomly located points in the area were monitored
but did not show any dye. Though the test was not made under
ideal conditions, the results seem to be quite clearly indicative
of structural control of ground-water movement in the area. The
inferred upward movement of connate water along fault planes
and the observed path of the dye are interpreted as evidence that






FLORIDA GEOLOGICAL SURVEY


some of the fault zones have a higher vertical permeability than
the nonfractured rocks.
Water movement in limestones of the principal artesian aquifer
is essentially restricted to solution zones that have developed along
joints, faults, and bedding planes. The more permeable fractures
are the avenues of movement of greater quantities of water than
the less permeable smaller fractures. As the solution-enlarged
fractures coalesced and extended to a point of discharge such as
a spring, the pressure in the larger cavities was reduced and water
moved from smaller fractures into the solution-enlarged cavities.
This process resulted in virtual conduits through which water
moved at relatively high velocities. As the velocity of the water
in the conduit increased, the water reacted less with the limestone
in the recharge area and thus was capable of dissolving more lime-
stone closer to the discharge area and further enlarging the
existing conduits. Eventually this destructive process led to over-
stressing and collapse of the limestone skeleton. After the
supporting limestone had collapsed in a large enough area, the
weak clays and sands fell into the cavity and resulted in the
formation of a depression in the land surface called a sinkhole.
The water, blocked by a plug of overburden, began development of
a cavity system to bypass the plug. Relaxation of lateral stress
in the vicinity of the original sinkhole resulted in redistribution
of stress in the area and probably aided the expansion of joints
and, consequently, the re-routing of water through the area.
The process above, repeated many times over the years, produced
the many sinkholes present today.
Thus, the existence of sinkholes in an area is indicative of a
substantially cavernous condition and infers high permeability of
the limestone. Where the sinkholes occur in a line or have coalesced
to form a linear depression, the directional trends of the joint
systems or faults which control the solution activity can be
established. In Hillsborough County, these trends are at compass
bearings of about N. 40 E., N. 40 W., N. 13 E., and N. 70 E.
Sulphur Springs derives the greater part of its water from the
Suwannee and Tampa limestones. The apparent decline of water
level in the Suwannee and in the Tampa is about 15 feet at the
spring. Water level in the Avon Park limestone is lowered about
5 feet by discharge from the spring. Distribution of springs and
linearity of surface features in the area suggest the existence of
a fault along the course of the Hillsborough River and another
trending northwest through the area. It is probable that the bulk
of the water from the Avon Park and lower limestones is moving






REPORT OF INVESTIGATIONS No. 25


along the fracture zone of a fault. This indicates that the Ocala
group is acting as a confining bed in a localized area about the
spring. The Suwannee and Tampa limestones should be considered
as a separate aquifer in this area.
A similar condition probably exists to the north and northeast
of Boiling Spring (755-204-A). Several instances of higher water
levels with depth, lowering of water levels in one well following
drilling of another well nearby, and water levels that are incon-
sistent with regional trends were reported in that area. The
reports were fairly consistent and are believed to be qualitatively
correct. The hydrology of the area adjacent to Boiling Spring is
complicated by the presence of a fairly well developed aquifer in
the Hawthorn formation and will require further study to
determine the exact conditions.
The confining beds overlying the principal artesian aquifer are
composed of clays of the Hawthorn formation and other undif-
ferentiated formations. The thickness of the confining beds ranges
from a few feet in the north-central part of the county to about
300 feet in the southeastern part. Numerous sand-filled sinkholes
breach the confining beds in the northern half of the county. These
,sinkholes act as recharge wells and probably contribute a major
part of the recharge to the aquifer in this area. Sinkholes become
progressively fewer toward the discharge areas and, except for
some quite ancient, -obscure, and completely filled sinkholes, have
not been found in discharge areas. Though some water moves into
Hillsborough County from Pasco and Polk counties, the greater
part of the water in the aquifer is introduced either by percolation
through the confining beds or through sinkholes that may or may
not be sand filled. Natural discharge is through springs either
on the land surface or in rivers and lakes or Tampa Bay. Water
discharges westward into the Gulf of Mexico from a small area
in the northwestern part of the county.
The quantity of water that may be obtained from wells in this
area is practically limited only by the desired quality of the water.
Throughout the county, yield is generally controlled by size and
depth of wells. However, salt water occurs at depth and quality
of water becomes an important consideration in deciding how
deep a well should be drilled. Consequently, the usable part of
the aquifer may be only a small part of the total aquifer. The
effective bottom elevation of the usable part of the aquifer is at
a depth below sea level of about 40 times the elevation of the
piezometric surface above sea level. The highest measured point
on the piezometric surface in the county is about 100 feet above





76 FLORIDA GEOLOGICAL SURVEY

mean sea level in a well about 3 miles northeast of Plant City
(803-204-1). Assuming an effective head of 85 feet, a maximum
bottom elevation of 3,400 feet below sea level is computed for wells
that will yield fresh water under those conditions. As the
piezometric surface approaches sea level, the thickness of the usable
part of the acquifer approaches zero and fresh water cannot be
obtained.

RECHARGE TO UNDERGROUND FORMATIONS

Recharge of the water-table aquifer occurs whenever rain falls
on the land surface. The water-table aquifer in Hillsborough
County consists of sand of about 30 percent perosity. The water
table rises approximately 3 inches for each inch of rainfall that
reaches it. The water table generally is only a few feet below
land surface even in dry periods, and areas that are not well
drained are likely to become saturated and to have water standing
on the surface after a heavy rain. The fluctuation in water levels,
though rapid, is only a few feet in magnitude.
Recharge of the artesian aquifers is more complex. It occurs
both by percolation through the so-called confining beds and by
surface water and discharge from other aquifers entering through
exposures of the aquifer in sinkholes. The water will flow into and
through all sediments. The rate of flow is determined in part by
the porosity and the hydraulic gradient. Observed water-level
fluctuations in the principal aquifer (fig. 45) are quite rapid and
of large magnitude, indicating that part of the recharge enters the
aquifers in a short time at a high rate. The most probable places
where high rates of recharge occur are the numerous sinkholes
and points where the aquifer is near the surface. The latter places
are not sufficiently numerous to be of areal importance. Thus,
sinkholes are the apparent avenue of rapid recharge of the aquifer.
An example of this type of recharge may be seen in the system of
sinkholes between Linebaugh and Fowler avenues west of Florida
Avenue in Tampa. The introduction of large quantities of water
into the aquifer from a drainage ditch through these sinkholes
causes an almost immediate and large rise in water level, in a well
near Nebraska Avenue at Temple Terrace Highway (801-227-1).
This well is hydraulically connected with cavities in the Tampa
and Suwannee limestones. See figure 46b.
Interpretation of the hydrographs of the group of three wells
(757-212-1, 2, 3) supports this hypothesis. The water level in Well
2, reflecting water-table conditions, rises several feet in response





REPORT OF INVESTIGATIONS NO. 25


0 n 0 Tn Ch
H) 10 10 1nq


o I I TMPA WETrHEi STA 'ON


S I II LEO WE THE ST ON
z 20


Figure 45. Water levels in selected wells and the precipitation at Tampa and
St. Leo weather stations.

to a heavy rain. The water level in Well 1, in the principal aquifer,
rises proportionally as and almost simultaneously with the level in
Well 2. The water in Well 3, reflecting the level in the shallow
artesian aquifer, rises with a lag of several days and in a subdued
manner. This is interpreted as being indicative of recharge of the
principal artesian aquifer by water that has not passed through
a permeable phase of the discontinuous shallow artesian aquifer.
The best explanation of this involves the presence of a vertical
solution opening through which the water could move into the
principal artesian aquifer from the nonartesian aquifer.

DISCHARGE FROM UNDERGROUND FORMATIONS

When an aquifer is saturated, the long-term volume of discharge
must equal the long-term volume of recharge. Variations in the
volume of water in storage are important only for short periods of
time and do not change the long-term recharge-discharge relation-
ships appreciably.
Ground water is discharged through both springs and wells


lfi 11.1 -a',' ItL LI* 1j &






FLORIDA GEOLOGICAL SURVEY


747-220-1

- 3 0 ---


-40
512c3-1 I





-14



752-207-I
L- -


44


7 220 -


TD<~


-IC

-12

-14
Z


j -'3

-'5


756-215-I




;j~iHThtVhThitWWIWizizLi


- I ,


- 56-227-, I I j tL
7r --


-is

-41

-43

-45

-47

-49


oJ A IS JON D J F MANM J JA S OND J F M AM J L ASS o N D
1956 1957 1__958

Figure 46a. Water levels in selected wells.


'' '''' "' ''


' '






REPORT OF INVESTIGATIONS NO. 25


757-212-2









-16 -
-10
757-221-1


3
801- 213-22



-7 5


I iiil i I~I I I 1 iI1 I~ IVl i i I


801-227-3

I I i \


- 802-238-1I


I I I I i i I I I I I i i i i I
03- 238-1


3
z -9



-j 18
.20

S22


1-


z -15

U' -17


0

+2

0

-n


-16


J' AIS 0N D J F IM AM| J A S 0 N D J F|M A|M J |As | O[N D
1956 1957 1958

Figure 46b. Water levels in selected wells.


_i41


IC


mmmrru~-rrc~mm


801-227-1
1 1 1 1


I


r


I Ii


I I I I





FLORIDA GEOLOGICAL SURVEY


__ 1 i. jrI __
-to i--


-14 --- ---- ._-^-- ____

14
10


0- 25 I | I I i/-I1 I








s oa-234-1 I
-23 -


25


. I


S 809-239-1 j 1

-13

t15


810-212-1
-7
o-9


JIAISI 0 D J AFIMAAMj ASI0 N J FM MAM J J ASON D
1956 1957 1958
Figure 46c. Water levels in selected wells.





REPORT OF INVESTIGATIONS NO. 25


809-227-1 1 1




757-212-3

" -29 I I

-33 I If



-76
W -7I _




-82 -



802-225-2
S2\ ii


JASONDIJFMAMMJJASONDJFMAMJ AS ND
1956 1957 I 1958

Figure 46d. Water levels in selected wells.



though, in general, more water is discharged through springs.
Data were collected from several hundred springs and wells
during this investigation. Information for most of the large and
a few of the smaller springs is listed in table 3. The locations of
these springs as well as many smaller springs for which no
information was collected are shown in figure 47.
Spring flow varies with head in the aquifer and decreases when
water levels decline. Low rainfall during the winter, use of
irrigation wells from November through May, and increased use
of water during the tourist season from January through April
cause water levels to decline. Therefore, spring flow is decreased
during the dry season.






FLORIDA GEOLOGICAL SURVEY


Bow fo m U. S GeogIcal
Siwey aograp*c wAdvonges
Figure 47. Locations of springs and areas in which water levels in the
principal artesian aquifer were above land surface in September and October
1958.

WATER LEVEL

The amount of water in the ground at any time depends on the
balance between recharge and discharge, on the transmissibility of
the aquifer, and on the ability of the aquifer to expand and contract
in response to changes in pressure. The water level is an indication
of the amount of water in an aquifer, and changes in the amount
of water in storage are reflected in changes of water levels in
wells that penetrate the aquifer. A rise in water level indicates
an increase in water pressure, which causes expansion of the
aquifer and compression of the water and an increase in the






TABLE 3. Information on Selected Springs in Hillsborough County

Estimated Approximate
Spring name Spring Owner Location discharge elevation Use Remarks
number (gpm) (ft.)


Lithia
Little Lithia
Messer
Buckhorn

Boiling
Palma Ceia
Craft Mineral
Deshong

Oak

Magbee

Eureka
Do.





Lowry

North Park
Jackson
10th Street Sink


Purity
Sulphur
Richardson
Trinity



Blue Sink


751-213-A
751-213-B
752-217-A
753-218-A

755-204-A
755-229-A
757-222-A
757-222-B

757-225-A

757-227-A

800-220-A
800-220-B
800-221-A
800-221-B

800-226-A
800-226-B
800-227-A

800-227-B
800-234-A
801-226-A

801-226-B
801-227-A
801-227-B
801-227-C
802-226-A



802-227-A


804-218-A -----.
805-219-A William Fink


808-205-A


SE% sec. 17, T. 30 S., R. 21 E.
SE% sec. 17, T. 30 S., R. 21 E.
SW% sec. 14, T. 30 S., R. 20 E.


County of Hillsborough
do.
-- .--------
U. S. Phosphoric Products
Corp.

City of Tampa
Mrs. H. E. Herrington
do.

Oak Park Drive-in Theatre

City of Tampa

------------------------
..-.... ...- ------- -



City of Tampa
Mrs. H. L. McGlammery
City of Tampa



Mrs. Cecil Fink

City of Tampa
Purity Springs Water Co.
City of Tampa
Hedrick Estate


SW A
SW1A
SW1A


SEA NE%, sec. 9, T. 30 S., R. 20 E.
SW% NWIA sec. 25, T. 29 S., R. 22 E.
NE%1 NE 14 sec. 34, T. 29 S., R. 18 E.
SW%A SW%A sec. 13, T. 29 S., R. 19 E.
SW1/ SW%4 sec. 13, T. 29 S., R. 19 E.

NE1/ NW%1 sec. 17, T. 29 S., R. 19 E.

SE%1 NW% sec. 13, T. 29 S., R. 18 E.

SE1% NWYA sec. 31, T. 28 S., R. 20 E.
SE% NW%, sec. 31, T. 28 S., R. 20 E.
SE 1A NWIA sec. 30, T. 28S., R. 20 E.
SE% NWIA sec. 30, T. 28 S., R. 20 E.

NEA SWA sec. 30, T. 28 S., R. 19 E.
SW'A SE1A sec. 30, T. 28 S., R. 19 E.
NW1A SWA sec. 25, T. 28 S., R. 19 E.

NWA NW1A sec. 36, T. 28 S., R. 18 E.
SE%1 NW% sec. 35, T. 28 S., R. 17 E.
SW% SWA sec. 19, T. 28 S., R. 19 E.

NWA SW% sec. 30, T. 28 S., R. 19 E.
NE% NW% sec. 25, T. 28 S., R. 18 E.
SE1A NE% sec. 25, T. 28 S., R. 18 E.
SWA NE1A sec. 25, T. 28 S., R. 18 E.
SW% SW% sec. 18, T. 28 S., R. 19 E.



SE%4 NW1A see. 13, T. 28 S., R. 18 E.


SE% NW% sec. 4, T. 28 S., R. 20 E.
SE1A SE'A sec. 29, T. 27 S., R. 20 E.

SE'A NEA sec. 15, T. 27 S., R. 22 E.


20,000
2,000
500

5,000
2,000
50
150
20

100

300

2,000
200
1,000
1,000

15
100
30

50
5
0

15
500
60,000
210


30+5
,305


Recreation
do.
None

Industrial
None
None
None
None

None

None

None
None
None
None

None
None
None

None
None
None

None
Public supply
Recreation
Public supply








None


A complex of 6 openings.
Water formerly bottled and sold.
Formerly supplied slaughter
house.
Spring is buried, discharge via
conduit.
High color, formerly public sup-
ply for Tampa.

200 ft. SW of 800-220-A.

0. 15 mi. N. of 800-221-A Spring
is in bottom of ditch.


Very strong H2S odor, sulfur de-
posits on curb.
Formerly supplied laundry.

Dike prevents flow except at high
stage.




Spring flowed from orifice into
pool-then out orifice on other
side of pool; ceased flow 7-10-58
following earthquake.
Spring flows from orifice into pool
-then out orifice on other side of
pool.


Spring is
corner.
On south
Creek, 50


150 feet. NW of sec.

bank of Blackwater
ft. west of canal.


5
25
7

5
5
13

5
7
7
5


20
300






REPORT OF INVESTIGATIONS NO. 25


U/1.:1( 5.4,%S DS'1...OF C14E INIERIOR
GtOL(GICA1 SUiRVEY


FLORIDA GEOLOGICAL SURVEY
R 0 Vtnono. ,eCIi,


00










I 2 ,--.. I-. ., .....
N,1 J., 4 ,..
























Bsos to pka li U S Geoaocol Iy'rc';y y >WS .Wclet eho'l

Figure 48. Piezometric surface in the principal artesian aquifer (September-
October 1958).

amount of water in storage. Conversely, when the water level
declines the aquifer contracts and the water expands, thus decreas-
ing the amount of water in storage.
The configuration of the piezometric surface in Hillsborough
County during September and October 1958 is shown in figure 48
by contour lines. This surface represents the water levels that
may be expected in wells tapping the principal artesian aquifer
throughout the county. The hydraulic gradient and direction of
movement of water also may be determined from the map. Water
always moves down the hydraulic gradient or normal to a contour
line from any point.
amun ofwtri trge ovrey0 he h ae ee
declines~ ~ ~ ~~~ ~~~~~ Ihlqiekonrcsadte ae xad, hsdces




























I -

















45-- 0 0 82428
3 '^ 0 ,, M' .06 ,








It Upp e nuIM i 1 l .11 LuIPP# nei M oume Ill at number
Contour m 0 1 llo Ti bo mea n t Ia Fllell i nt n imr lnw l, Awmlrmi
PMble Spiply Will otheod wN> gommIfflmlf. defemlId Eby iglfotImIIoI o ) lllOli d(limlirmld ,rm i e f m O IAh'c mlopl.)
Figure 49. Piezometric surface in northwestern Hillsborough County (No-
vember 21-28, 1957).