Hydrology of Polk County, Florida

By Rick M. Spechler and Sharon E. Kroening

Prepared in cooperation with the

Polk County Board of County Commissioners

South Florida Water Management District

Southwest Florida Water Management District

St. Johns River Water Management District 

Scientific Investigations Report 2006-5320

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Spechler, R.M., and Kroening, S.E., 2007, Hydrology of Polk County, Florida: U.S. Geological Survey 

Scientific Investigations Report 2006-5320, 114 p.
Contents

Abstract...........................................................................................................................................................1

Introduction ....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Previous Investigations........................................................................................................................3

Acknowledgments................................................................................................................................3

Site-Numbering System.......................................................................................................................3

Description of Study Area ............................................................................................................................4

Population, Industry, and Land Use ...................................................................................................5

Physiography.........................................................................................................................................6

Climate....................................................................................................................................................8

Ground-Water Use..............................................................................................................................10

Chapter 1—Ground-Water Resources of Polk County................................................................13

Data Collection.............................................................................................................................................13

Geologic Framework ...................................................................................................................................13

Stratigraphy .........................................................................................................................................13

Karst Features .....................................................................................................................................18

Ground-Water Resources ..........................................................................................................................18

Surficial Aquifer System....................................................................................................................19

Intermediate Confining Unit and Intermediate Aquifer System..................................................26

Floridan Aquifer System.....................................................................................................................33

Upper Floridan Aquifer..............................................................................................................33

Middle Semiconfining Unit and Middle Confining Unit .......................................................35

Lower Floridan Aquifer .............................................................................................................37

Sub-Floridan Confining Unit .....................................................................................................38

Ground-Water Flow System.....................................................................................................38

Recharge and Discharge.................................................................................................38

Potentiometric Surface....................................................................................................38

Long-Term Trends in Ground-Water Levels....................................................................................42

Head Relations ....................................................................................................................................46

Water Budget ......................................................................................................................................50

Ground-Water Quality .................................................................................................................................51

Surficial Aquifer System....................................................................................................................52

Intermediate Aquifer System............................................................................................................57

Floridan Aquifer System.....................................................................................................................58

Vertical Distribution of Chloride and Sulfate Concentrations ............................................62

Chapter 2—Streamflow and Lake-Level Characteristics in Polk County............................67

Purpose and Scope .....................................................................................................................................67

Methods.........................................................................................................................................................67

Streamflow and Lake-Level Characteristics...........................................................................................67

Streamflow Characteristics ..............................................................................................................68

Peace River Basin .....................................................................................................................70

Kissimmee River Basin .............................................................................................................74

Alafia, Hillsborough, Ocklawaha, and Withlacoochee River Basins ................................77

iii
Low-Flow and Flood-Frequency Statistics .....................................................................................77

Lake Characteristics...........................................................................................................................77

Regulation of Lake Levels.........................................................................................................81

Temporal Trends in Lake Levels ..............................................................................................84

Factors Controlling Lake Levels ..............................................................................................85

Summary........................................................................................................................................................88

Selected References...................................................................................................................................91

Appendix 1. Well and spring data-collection sites.........................................................................99-105

Appendix 2. Chemical and physical data for water from the surficial aquifer system, 

intermediate aquifer system, and the Upper Floridan aquifer wells in Polk and 

parts of adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties....107-112

Appendix 3. Lake and stream data-collection sites.....................................................................113-114

Figures

1. Map showing location of study area in central Florida..........................................................4

2. Graph showing historical population for Polk County............................................................5

3-4. Maps showing generalized:

3. Land use in Polk County, 1995 ..........................................................................................6

4. Physiography of Polk County............................................................................................7

5-6. Graphs showing:

5. Annual rainfall at Lakeland, Mountain Lake, and Avon Park, Florida, 

1931-2003..............................................................................................................................9

6. Monthly evapotranspiration at the Disney Wilderness Preserve in eastern 

Polk County, August 2000 to December 2005...............................................................10

7. Diagram showing total ground-water use, by category, for 2000 ......................................11

8. Piechart showing historical total ground-water use in Polk County, 1965-2002..............11

9-10. Maps showing location of:

9. Wells with periodic or continuous water-level data ..................................................14

10. Wells and spring where water-quality data were collected from 1998-2003.........15

11. Lithologic chart showing relation of stratigraphic and hydrogeologic units ...................16

12. Geologic map of Polk County....................................................................................................17

13. Aerial photograph showing sinkhole-formed lakes near Winter Haven, Florida ............19

14. Map showing location of sinkholes and depressions in Polk County ...............................20

15. Photograph showing loss of water from the Peace River through underlying 

conduit during low-flow period, May 2004 .............................................................................21

16. Map showing location of hydrogeologic sections................................................................22

17-18. Diagrams showing generalized hydrogeologic sections:

17. A-A’ and B-B’.....................................................................................................................23

18. C-C’ and D-D’.....................................................................................................................24

19. Map showing generalized thickness of the surficial aquifer system ................................25

20. Graphs showing water levels at selected wells tapping the surficial aquifer system.....26

iv
21-25. Maps showing:

21. Transmissivity of the surficial and intermediate aquifer systems............................27

22. Generalized altitude of the top of the intermediate confining unit and the 

intermediate aquifer system...........................................................................................28

23. Generalized thickness of the intermediate confining unit and the 

intermediate aquifer system...........................................................................................29

24. Water levels of the intermediate aquifer system (Zone 2), September 2003 .........30

25. Water levels of the intermediate aquifer system (Zone 2), May 2004 .....................31

26. Graphs showing water levels at selected wells tapping the intermediate

aquifer system ............................................................................................................................32

27-31. Maps showing:

27. Altitude of the top of the Floridan aquifer system.......................................................34

28. Transmissivity of the Upper Floridan aquifer...............................................................36

29. Altitude of the top of the middle confining unit...........................................................37

30. Potentiometric surface of the Upper Floridan aquifer, September 2003.................39

31. Potentiometric surface of the Upper Floridan aquifer, May 2004 ............................40

32. Graphs showing water levels in selected wells tapping the Upper Floridan aquifer.......41

33-34. Maps showing:

33. Predevelopment potentiometric surface of the Upper Floridan aquifer.................42

34. Change in the potentiometric surface of the Upper Floridan aquifer from 

predevelopment to average 2000-2004 conditions .....................................................43

35-37. Graphs showing:

35. Discharge at Kissengen Spring, 1898-1960..................................................................43

36. Long-term water levels in observation wells tapping the surficial aquifer 

system and the Upper Floridan aquifer.........................................................................45

37. Water levels in selected wells open to the surficial aquifer system, the 

intermediate aquifer system, and the Upper Floridan aquifer..................................47

38. Map showing head differences between the surficial aquifer system and the 

Upper Floridan aquifer, May 2004 ............................................................................................48

39. Graphs showing water levels during drilling of monitoring wells......................................49

40. Diagram showing water budget for Polk County, Florida, 1994-2003.................................50

41. Trilinear diagram for water from wells tapping the surficial aquifer system ...................52

42-45. Maps showing generalized distribution of:

42. Specific conductance in water from the surficial aquifer system...........................53

43. Chloride concentrations in water from the surficial aquifer system.......................54

44. Sulfate concentrations in water from the surficial aquifer system.........................55

45. Nitrate concentrations in water from the surficial aquifer system .........................56

46. Trilinear diagram for water from wells tapping the intermediate aquifer system...........57

47. Map showing generalized distribution of selected constituents in water from 

the intermediate aquifer system ..............................................................................................58

48. Trilinear diagram for water from wells tapping the Upper Floridan aquifer.....................59

49-53. Maps showing generalized distribution of:

49. Specific conductance in water from the Upper Floridan aquifer ............................60

50. Chloride concentrations in water from the Upper Floridan aquifer.........................61

51. Sulfate concentrations in water from the Upper Floridan aquifer...........................62

52. Hardness concentrations in water from the Upper Floridan aquifer ......................63

53. Nitrate concentrations in water from the Upper Floridan aquifer...........................64
54. Graphs showing chloride and sulfate concentrations in water samples obtained 

during drilling of monitoring wells ...........................................................................................65

55-57. Maps showing:

55. Estimated altitude of water in the Floridan aquifer system having chloride 

concentrations greater than 250 milligrams per liter.................................................66

56. Location of lakes and streams analyzed in this report ..............................................68

57. Major surface-water drainage basins, tributaries, and lakes..................................69

58. Flow-duration hydrographs for Peace River at Bartow, water years 1979-2003 .............70

59. Graph showing flow-duration curves for selected stream sites in Polk County, 

water years 1979-2003 ...............................................................................................................71

60. Graph showing flow-duration curves for Kissimmee River at S-65, water years 

1930-1969 and water years 1979-2003......................................................................................75

61. Flow-duration hydrographs for Kissimmee River at S-65 (site 74), water years 

1930-1969 and 1979-2003............................................................................................................76

62. Map showing location of Lake Hamilton and Winter Haven Chain of Lakes....................82

63-65. Graphs showing:

63. Generalized seasonal variations in lake levels in Lake Deeson, 1954-2003 ...........83

64. Seasonal variations in lake levels in Saddle Blanket Lake during a period of 

below normal rainfall........................................................................................................83

65. Seasonal variations in lake levels and the minimum daily air temperatures 

at a lake (Swim Lake) affected by ground-water pumpage......................................84

66-67. Maps showing temporal trends in lake levels in:

66. Polk County, 1960-2003 ....................................................................................................86

67. Polk County, 1990-2003 ....................................................................................................87

Tables

1. Results of trend analysis for long-term observation wells and for rainfall stations...............44

2. Mean annual flow and runoff for selected streams in Polk County, water years 

1991-2003.............................................................................................................................................69

3. Temporal trends in streamflow over 20-year periods for Peace River at Bartow..................72

4. Temporal trends in streamflow over 30-year periods for Peace River at Bartow..................72

5. Temporal trends in streamflow over 40-, 50-, and 60-year periods for Peace River 

at Bartow ............................................................................................................................................73

6. Low-flow frequency statistics for Catfish Creek near Lake Wales...........................................78

7. Low-flow frequency statistics for Fox Branch near Socrum .....................................................78

8. Low-flow frequency statistics for Green Swamp Run near Eva................................................78

9. Low-flow frequency statistics for Bowlegs Creek near Fort Meade........................................79

10. Low-flow frequency statistics for Livingston Creek near Frostproof .......................................79

11. Low-flow frequency statistics for Peace Creek Drainage Canal near Wahneta ...................79

12. Low-flow frequency statistics for Tiger Creek near Babson Park............................................80

13. Low-flow frequency statistics for Peace River at Bartow .........................................................80

14. Low-flow frequency statistics for Peace River at Fort Meade..................................................80

15. Flood-flow frequency statistics for selected sites in Polk County............................................81

16. Temporal trends in mean annual water levels for selected lakes in Polk County, 

1960-2003.............................................................................................................................................85

vi
Conversion Factors, Vertical Datum, Abbreviations, 

and Acronyms

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day (m/d)

Transmissivity*

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

Leakance

foot per day per foot [(ft/d)/ft] 1 meter per day per meter

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F – 32) / 1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). 

Altitude, as used in this report, refers to distance above the vertical datum.

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of 

aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot squared per day (ft2/d), 

is used for convenience.

vii
Acronyms and Additional Abbreviations

AMO Atlantic Multidecadal Oscillation

CaCO3 calcium carbonate

ET evapotranspiration

FGS Florida Geological Survey

LOWESS locally weighted scatterplot

μg/L micrograms per liter

μS/cm microsiemens per centimeter at 25 °C

mg/L milligrams per liter

NOAA National Oceanic and Atmospheric Administration

NWIS National Water Data Information System

NO3

- nitrate

NO2

- nitrite

N nitrogen

PDO Pacific Decadal Oscillation

ROMP Regional Observation and Monitoring-Well Program

SJRWMD St. Johns River Water Management District

SFWMD South Florida Water Management District

SWUCA Southern Water Use Caution Area

SWFWMD Southwest Florida Water Management District

QS spring discharge

QO subsurface outflow

QR surface-water runoff

USGS U.S. Geological Survey

viii
aquifer system. The Floridan aquifer system, a thick sequence 

of permeable limestone and dolostone, consists of the Upper 

Floridan aquifer, a middle semiconfining unit, a middle 

confining unit, and the Lower Floridan aquifer. The Upper 

Floridan aquifer provides most of the water required to meet 

demand in Polk County.

Data from about 300 geophysical and geologic logs were 

used to construct hydrogeologic maps showing the tops and 

thicknesses of the aquifers and confining units within Polk 

County. Thickness of the surficial aquifer system ranges from 

several feet thick or less in the extreme northwestern part of 

the county and along parts of the Peace River south of Bartow 

to more than 200 feet along the southern part of the Lake 

Wales Ridge in eastern Polk County. Thickness of the intermediate aquifer system/intermediate confining unit is highly variable throughout the county because of past erosional processes 

and sinkhole formation. Thickness of the unit ranges from less 

than 25 feet in the extreme northwestern part of the county to 

more than 300 feet in southwestern Polk County. The altitude 

of the top of the Upper Floridan aquifer in the county ranges 

from about 50 feet above National Geodetic Vertical Datum 

of 1929 (NGVD 29) in the northwestern part to more than 

250 feet below NGVD 29 in the southern part.

Water levels in the Upper Floridan aquifer fluctuate 

seasonally, increasing during the wet season (June through 

September) and decreasing during the rest of the year. Water 

levels in the Upper Floridan aquifer also can change from year 

to year, depending on such factors as pumpage and climatic 

variations. In the southwestern part of the county, fluctuations 

in water use related to phosphate mining have had a major 

impact on ground-water levels. Hydrographs of selected 

wells in southwestern Polk County show a general decline 

in water levels that ended in the mid-1970s. This water-level 

decline coincides with an increase in water use associated with 

Abstract

Local water managers usually rely on information 

produced at the State and regional scale to make waterresource management decisions. Current assessments of 

hydrologic and water-quality conditions in Polk County, 

Florida, commonly end at the boundaries of two water 

management districts (South Florida Water Management 

District and the Southwest Florida Water Management 

District), which makes it difficult for managers to determine 

conditions throughout the county. The last comprehensive 

water-resources assessment of Polk County was published 

almost 40 years ago. To address the need for current countywide information, the U.S. Geological Survey began a 31⁄2-

year study in 2002 to update information about hydrologic and 

water-quality conditions in Polk County and identify changes 

that have occurred.

Ground-water use in Polk County has decreased substantially since 1965. In 1965, total ground-water withdrawals in 

the county were about 350 million gallons per day. In 2002, 

withdrawals totaled about 285 million gallons per day, of 

which nearly 95 percent was from the Floridan aquifer system. 

Water-conservation practices mainly related to the phosphatemining industry as well as the decrease in the number of mines 

in operation in Polk County have reduced total water use by 

about 65 million gallons per day since 1965.

Polk County is underlain by three principal hydrogeologic units. The uppermost water-bearing unit is the surficial 

aquifer system, which is unconfined and composed primarily 

of clastic deposits. The surficial aquifer system is underlain 

by the intermediate confining unit, which grades into the 

intermediate aquifer system and consists of up to two waterbearing zones composed of interbedded clastic and carbonate 

rocks. The lowermost hydrogeologic unit is the Floridan 

Hydrology of Polk County, Florida

By Rick M. Spechler and Sharon E. Kroening
 Hydrology of Polk County, Florida

phosphate mining. A substantial increase in water levels that 

began in the mid-1970s coincides with a period of decreasing 

water use in the county.

Despite reductions in water use since 1970, however, 

over the long term, the increase in pumping in and near Polk 

County has resulted in a decline of the potentiometric surface 

of the Upper Floridan aquifer across much of the county since 

predevelopment times. Based on the difference between the 

estimated predevelopment potentiometric-surface map and 

water levels in wells measured in May and September and 

averaged from 2000 to 2004, water-level declines range from 

zero in the northwestern part of the county to as much as 

40 feet in the southwestern part.

Water samples collected from 130 wells were used to 

characterize ground-water quality in Polk County. Samples 

from 53 wells and 1 spring in Polk and adjacent counties were 

collected for this project by the U.S. Geological Survey and 

analyzed for common inorganic constituents and nutrients. 

Concentrations of total dissolved solids, sulfate, and chloride 

in water samples from the surficial and intermediate aquifer 

systems generally were below State and Federal drinkingwater standards. Nitrate concentrations, however, were as high 

as 26 milligrams per liter (mg/L) in samples from the surficial 

aquifer system along the Lake Wales Ridge. The application of 

fertilizers related to citrus farming is a likely source of nitrate 

to the ground water in this area.

Inorganic constituent concentrations in water from the 

Floridan aquifer system generally were below State and 

Federal drinking-water standards. Water from the Upper 

Floridan aquifer in most of Polk County is hard (hardness 

ranging from 70 to 290 mg/L), and has a dissolved-solids 

concentration of less than 500 mg/L. Chloride concentrations 

in water from the Upper Floridan aquifer range from 4.2 to 

61 mg/L, and sulfate concentrations range from about 0.2 

to 44 mg/L. In contrast to results from the surficial aquifer 

system, nitrate concentrations in the Upper Floridan aquifer 

generally were low (less than 0.02 mg/L) and exceeded 

1.0 mg/L in only three wells.

Temporal trends in streamflow in the Peace River were 

updated in this study using data through 2003. The analyses 

also were expanded by analyzing trends over a wide range of 

the hydrologic regime and over several multidecadal periods. 

Results indicate that annual minimum to 70th percentile 

streamflows in the Upper Peace River began to decline in the 

1950s, and this decline has persisted to 2003. Results also 

showed a statistically significant decrease in annual minimum 

streamflows in the Peace River at Bartow from 1974-1993. 

This decrease may be due to elimination of wastewater 

discharges to the stream during the mid-1980s.

Temporal trends in lake levels were analyzed to describe 

long-term trends (1960-2003) and trends of a shorter duration 

(1990-2003). About 90 percent of the lakes had no change in 

water levels from 1990-2003. Five of the lakes had an increasing trend in water levels. The increase in water levels likely is 

not due to increased rainfall. Annual totals at nearby rainfall 

stations had no significant trends during this period.

Introduction

Increasing demands are being made on the water 

resources of Polk County, Florida, as a result of rapidly 

increasing population and a strong agricultural industry. 

Changes in ground-water levels or water quality that may have 

resulted from the redistribution of pumping stresses, however, 

have not been documented on a countywide basis. The last 

comprehensive hydrogeologic investigation of Polk County 

was completed in 1966. The U.S. Geological Survey (USGS) 

and other State and local agencies continue to collect information on the surface-water and ground-water resources of Polk 

County. Current assessments of hydrologic and water-quality 

conditions conducted by these agencies commonly end at 

the water management district boundaries, which makes it 

difficult for water-resource managers to determine hydrologic 

and water-quality conditions throughout the county. Three of 

Florida’s water management districts (St. Johns River, South 

Florida, and Southwest Florida Water Management Districts) 

have had jurisdiction over parts of the county. An analysis 

of long-term and current hydrologic data will enable waterresource managers to better evaluate changes in hydrologic 

conditions. Updated information can be used to redefine baseline conditions against which future changes can be quantified. 

To address the need for current countywide information, the 

USGS, in cooperation with Polk County, the South Florida 

Water Management District (SFWMD), the St. Johns River 

Water Management District (SJRWMD), and the Southwest 

Florida Water Management District (SWFWMD) conducted a 

31⁄2-year study from 2002 to 2006 to evaluate the hydrogeology and ground-water quality of Polk County and to provide 

an updated evaluation of surface water including streamflow 

and lake-level trends and characteristics. The results of the 

study are summarized in this report.

Purpose and Scope

This report presents the results of a study to describe and 

update information on the hydrogeology of the surficial, intermediate, and Floridan aquifer systems in Polk County, Florida, 

characterize water-quality conditions in the three aquifers, and 

assess long-term trends in the ground-water and surface-water 

resources. Chapter 1 of the report describes: (1) the lithology, 

depth, thickness, and extent of the surficial aquifer system, 

intermediate aquifer system, intermediate confining unit, and 

the Floridan aquifer system in Polk County; (2) water levels 

and water-level changes in the aquifer systems; and (3) the 

water-quality characteristics of the surficial, intermediate and 

Floridan aquifer systems. Chapter 2 describes trends in lake 

stage and streamflow by updating flow and lake stage data and 

duration curves.

Information presented in the report was compiled 

from data collected during this investigation by the USGS, 

SWFWMD, SFWMD, and SJRWMD. Additional information also was obtained from published reports by the USGS, 
SFWMD, Florida Geological Survey (FGS), and private 

consultants, and from unpublished data by the USGS and 

FGS. New data collected during this investigation included 

water-quality samples, ground-water level measurements, and 

lithologic logs.

Previous Investigations

Numerous reports have described the hydrology, geology, 

and ground-water resources of Polk County. Discussions of 

Florida geology with reference to Polk County are included in 

reports by Cooke (1945) and Stringfield (1966). Miller (1986) 

describes the hydrogeologic framework of the Floridan aquifer 

system.

The first comprehensive investigation on the hydrogeology and ground-water resources of Polk County was done by 

Stewart (1966). A number of studies have described the hydrogeology of selected areas within Polk County. Shaw and Trost 

(1984) evaluated the regional hydrogeology of the Kissimmee 

River Basin. Duerr and others (1988) and Knochenmus (2006) 

described the hydrogeologic framework of the intermediate 

aquifer system in west-central Florida. O’Reilly and others 

(2002) described the hydrogeology and water quality of the 

Lower Floridan aquifer in east-central Florida, which included 

part of Polk County. Pride and others (1966), Grubb (1978), 

and Grubb and Rutledge (1979) described the hydrology of 

the Green Swamp area. Robertson (1971; 1973) discussed the 

hydrology of the Lakeland Ridge. The hydrogeology of the 

Lake Wales Ridge was described in several reports, including Barcelo and others (1990) and Yobbi (1996). Hutchinson 

(1978) described the surficial and intermediate aquifer systems 

of the upper Peace River and eastern Alafia River Basins. 

Kaufman (1967) and Robertson and Mills (1974) described the 

effects of ground-water pumping in the Peace and Alafia River 

Basins. Basso (2003) discussed the surface-water/groundwater relation in the Upper Peace River Basin. Lewelling 

and others (1998) assessed the hydraulic connection between 

ground water and the Peace River.

Several reports evaluated the ground-water quality in 

Polk County. Swancar and Hutchinson (1995) discussed the 

chemical and isotopic composition and potential for contamination of water in the Upper Floridan aquifer in west-central 

Florida. Stewart (1966) presented a general reconnaissance of 

ground-water quality in Polk County. Barr (1992) evaluated 

the potential for ground-water contamination of the surficial, 

intermediate, and Floridan aquifer systems in Polk County. 

Miller and Sutcliffe (1982), Rutledge (1987), and Lewelling 

and Wylie (1993) described the quality of water in the surficial 

aquifer system in parts of the phosphate region of southwestern Polk County. Moore and others (1986) summarized 

information from the ambient ground-water quality monitoring 

program for the SWFWMD. Nitrate in shallow ground water 

in the vicinity of the Lake Wales Ridge was evaluated by 

Tihansky and Sacks (1997). Pesticides and nitrate concentrations in the surficial aquifer system underlying citrus areas in 

the northern part of the Lake Wales Ridge were evaluated in 

a land-use comparison study (German, 1996). Agricultural 

chemicals in the surficial aquifer system in the Lake Wales 

Ridge were investigated by Choquette and others (2005).

Several investigators have employed continuous highresolution seismic-reflection techniques in Polk County lakes 

and rivers to describe geologic structure at depth—including 

Evans and others (1994), Tihansky and others (1996), and 

Lewelling and others (1998).

Ground-water flow modeling studies that include all or 

part of the study area are presented by Grubb and Rutledge 

(1979), Wilson and Gerhart (1982), Ryder (1982; 1985), 

Tibbals (1990), Barcelo and Basso (1993), Yobbi (1996), and 

Sepúlveda (2002).

Several hydrologic assessments have focused on lakes 

that lie within Polk County. The hydrology and limnology of 

Crooked Lake were described by Bradbury and others (1978). 

Sacks and others (1998) estimated ground-water exchange 

with lakes in the ridge areas of Polk and Highlands Counties 

by using water-budget and chemical mass-balance approaches. 

Swancar and others (2000) estimated ground-water exchange 

at Lake Starr.

Acknowledgments

The authors gratefully acknowledge the assistance given 

by many organizations and individuals during the study and 

especially appreciate the cooperation received from Chris Sweazy, 

Emily Hopkins Richardson, and Cynthia Gefvert of the South 

Florida Water Management District; Jeff Spence of the Polk 

County Board of County Commissioners; Margit Crowell, 

Eric DeHaven, and Joseph Haber of the Southwest Florida 

Water Management District; and Nolan Col of the St. Johns 

River Water Management District. Appreciation also is 

expressed to the residents and private companies in the area 

who permitted access to their properties and allowed the 

sampling of water and measuring of water levels in their wells.

Site-Numbering System

The USGS assigns a unique site identification number 

to each inventoried well and surface-water site. A 15-digit 

number based on latitude and longitude is used to identify 

wells in the USGS National Water Data Information System 

(NWIS). The first six digits denote the degrees, minutes, and 

seconds of latitude; the next seven digits denote degrees, 

minutes, and seconds of longitude; and the last two digits 

denote a sequential number for a site within a one-second 

grid. For example, well 280253081235801 is the first well 

inventoried at latitude 28 ̊02’53” N, longitude 081 ̊23’58” W. 

The latitude and longitude stored in NWIS, however, should 

be used rather than those defined by the 15-digit site number 

because the initial measurements may be inaccurate or successive measurements more accurate. Surface-water sites that are 

Introduction 
 Hydrology of Polk County, Florida

part of the long-term data-collection network are assigned an 

eight-digit downstream order number, such as 02294650 for 

the Peace River at Bartow, which designates the major river 

basin (02) and the order in which the tributary joins the main 

stream. Surface-water sites that are not part of the long-term 

network usually are given a 15-digit number.

Description of Study Area

Polk County, located in the central part of the Florida 

peninsula, is Florida’s fourth largest county (fig. 1). It is 

bordered on the north by Lake and Sumter Counties, on 

the east by Osceola County, on the south by Hardee and 

Highlands Counties, and on the west by Hillsborough and 

Pasco Counties. Polk County is approximately 40 miles 

wide and 50 miles long and has a surface area of about 1,823 

square miles (mi2), of which 187 mi2 are water (Purdum and 

others, 1988). Land-surface elevations range from about 50 

to 305 feet (ft) above NGVD 29 (Stewart, 1966); however, 

most of the land lies between 75 and 250 ft above NGVD 29 

(Heath, 1961; Southwest Florida Water Management District, 

1988). The lowest elevations are found in the eastern part 

of the county, and the highest elevations are found on the 

Lake Wales Ridge in the vicinity of the city of Lake Wales 

and Babson Park (Stewart, 1966). The western part of Polk 

County is included within the SWFWMD, and the eastern 

part is included within the SFWMD (fig. 1). A small area 

in the northern part of the county that corresponded to the 

Ocklawaha River basin was once part of the SJRWMD, but 

in 2003 boundary lines were redrawn and this area is now 

under the jurisdiction of the SWFWMD. All of Polk County 

that falls under the jurisdiction of the SWFWMD is part of 

the Southern Water Use Caution Area (SWUCA), which 

GREEN

SWAMP

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Withlacooche Ri e

e

v r

Peace v Ri er

Kissim

me ver e Ri

Saddle

Creek

Saddle

Creek

Lake

Hatchineha

Lake

Pierce

Lake

Marion

POLK COUNTY

LAKE

COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

SJRWMD

SWFWMD

SFWMD

SWFWMD

SFWMD

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

STUDY AREA

Lakeland

Polk City

Davenport

Dundee

Lake Wales

Bartow

Bradley

Junction

Fort Meade Frostproof

Winter

Haven

Auburndale

Lake

Alfred

Eagle

Lake

Highland

Park

Hillcrest

Heights

Lake

Hamilton

Haines

City

Mulberry

Mountain

Lake

Avon Park

Lake Louisa

State Park

Babson

Park

17

I-4

17

98

17

27

27

98

92

98

60

60

60

60

630

Kissengen

Spring

Disney

Wilderness

Preserve

Figure 1. Location of study area in central Florida.
includes all or part of eight counties in southwestern Florida. 

This water-use caution area was designated in 1992, when it 

was recognized that increasing ground-water withdrawals (in 

response to increasing growth) resulted in declines in aquifer 

heads causing saltwater intrusion in coastal areas, lowered lake 

levels in the upland areas, and reduced baseflow in some river 

reaches.

Population, Industry, and Land Use

Since the 1960s, there has been a rapid increase in 

population and this trend is expected to continue. From 1960 

to 2004, the population of Polk County increased from about 

195,000 to 528,000 (fig. 2). The population of Polk County 

is projected to reach about 676,000 by 2020. In 2004, the 

county was the 10th largest in terms of population in the State 

(Office of Economic and Demographic Research, 2005). Polk 

County has 17 municipalities (fig. 1). The largest in population is Lakeland and the second largest is Winter Haven. 

Other municipalities include Auburndale, Bartow, Davenport, 

Dundee, Eagle Lake, Fort Meade, Frostproof, Haines City, 

Highland Park, Hillcrest Heights, Lake Alfred, Lake Hamilton, 

Lake Wales, Mulberry, and Polk City.

Polk County is one of the leading counties in industrial 

development in the State, having about 450 manufacturing 

companies and 3,114 farms in 2002 (U.S. Department of 

Agriculture, 2005). It ranks first in phosphate production (Polk 

County Department of Economic Development, 2005) and 

second in cattle production (U.S. Department of Agriculture, 

2005). The county also ranks first in the State in citrus production for 2003-2004, producing nearly 14 percent of Florida’s 

citrus (U.S. Department of Agriculture, 2005).

Agriculture, wetlands, urban land, forests, and mining 

were the major land-use categories in the county in 1995 

(fig. 3). Agricultural land use composed about 40 percent of 

the county, in which citrus is the primary agricultural product. 

Agricultural lands are scattered throughout the county, but 

are concentrated along the ridges. Wetlands composed about 

30 percent of the county and generally are found in the 

Green Swamp area of northern Polk County and east of the 

Lake Wales Ridge. Urban land composed about 12 percent 

of the county, and is mostly concentrated around the cities 

of Lakeland, Bartow, Auburndale, Winter Haven, and Lake 

Wales. Forest covered about 6 percent of the county, primarily 

in the eastern one-third of the county. Mining areas composed 

about 4 percent of the county, and are found primarily in the 

southwestern part. Phosphate and, to a lesser degree, sand 

mining are the primary types of mining operations.

A comparison of the extent of urban land use between 

1977 and 1995 indicates that the amount of urban area 

increased from about 10 to 12 percent. Most of the increase in 

urbanization occurred in an east-west band across the central 

part of the county, which included the cities of Lakeland, 

Auburndale, Winter Haven, and Lake Wales. The eastern part 

of the county (east of the Lake Wales Ridge) has had relatively 

little increase in urbanization.

1960 1970 1980 1990 2000 2010 2020

YEAR

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

POPULATION

Figure 2. Historical population for Polk County (from the Office of Economic and Demographic Research, 2005).

Description of Study Area 
 Hydrology of Polk County, Florida

Physiography

Polk County is divided into 10 physiographic provinces 

(White, 1970): the Polk Upland, Lake Upland, Winter Haven 

Ridge, Lake Henry Ridge, Lakeland Ridge, Lake Wales Ridge, 

Bombing Range Ridge, Osceola Plain, Western Valley, and Intra 

Ridge Valley (fig. 4). In general, these physiographic provinces are four basic types: uplands, ridges, valleys, and plains.

Much of the western part of Polk County lies in the Polk 

and Lake Uplands. These uplands are characterized by moderate relief, shallow lakes, and moderate water-table depths. 

The Polk Upland is a broad sandy area that ranges in altitude 

from about 65 ft above NGVD 29 along parts of the Peace 

River to about 150 ft above NGVD 29. In the northern part 

of the county, the Polk Upland merges with the Lake Upland. 

The boundary between the Polk and Lake Uplands is inferred 

because there is not a distinct topographic break between the 

two uplands (White, 1970). The part of the Lake Upland that 

is in Polk County ranges in altitude from 100 to 135 ft above 

NGVD 29. In much of the Lake Upland lies the Green Swamp. 

The Green Swamp is a composite of many swamps that are 

distributed fairly uniformly over the area. Interspersed among 

the swamps are low ridges, hills, and flatlands. In the extreme 

northwestern part of the county lies the Western Valley physiographic province. The Western Valley is a low, irregular valley 

produced by the erosion of soluble sediments (Campbell, 

1986). Elevations of the Western Valley that lie within Polk 

County range from 75 to about 120 ft above NGVD 29.

Figure 3. Generalized land use in Polk County, 1995.
Three north-northwest to south-southeast trending ridges 

rise from the surface of the Polk Upland. These ridges have the 

highest land-surface elevations in the county and are characterized by closed basin lakes and sinkholes, deep water tables, 

and subsurface drainage. Surface drainage features generally 

are absent. The easternmost ridge within the Polk Upland (the 

Winter Haven Ridge) consists mostly of small ridge remnants, 

reaching altitudes of about 200 ft above NGVD 29. The 

southern extension of the Winter Haven Ridge is referred to as 

the Lake Henry Ridge. Maximum altitudes along this ridge are 

230 ft above NGVD 29. The westernmost ridge, the Lakeland 

Ridge, begins about 10 miles north of Lakeland and extends to 

the south of Bartow, reaching altitudes of about 270 ft above 

NGVD 29.

The most prominent ridge in Polk County is the Lake 

Wales Ridge (fig. 4). The Lake Wales Ridge, located east of 

the Winter Haven Ridge, borders the eastern edge of the Polk 

Upland and extends southward from Lake County, through 

Polk County and into Highlands County. The Lake Wales 

Ridge is the highest and longest of the ridges, with maximum 

altitudes of 305 ft above NGVD 29. This long, narrow, sandy 

ridge contains numerous sinkhole lakes and depressions, many 

of which do not have any surface-water outlets. In the southern 

part of the county, the Lake Wales Ridge is divided into two 

secondary ridges by the Intra Ridge Valley. This valley was 

formed by the dissolution of the underlying limestone and 

contains numerous karst features.

LAKE UPLAND WESTERN

VALLEY

WINTER

HAVEN

RIDGE

LAKE

WALES

RIDGE

POLK UPLAND

LAKELAND

RIDGE

BOMBING

RANGE RIDGE

OSCEOLA

LAKE

PLAIN

HENRY

RIDGE

INTRA RIDGE

VALLEY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

Figure 4. Generalized physiography of Polk County (from White, 1970).

Description of Study Area 
 Hydrology of Polk County, Florida

The Osceola Plain is a broad marine terrace that lies east 

of the Lake Wales Ridge. It is characterized by large lakes, 

little relief, and altitudes that range from about 50 to 75 ft 

above NGVD 29. Water levels in the surficial aquifer system 

are at, or only a few feet below, land surface in much of the 

plain. In southeastern Polk County, the Bombing Range Ridge 

rises above the level of the Osceola Plain. Reaching altitudes 

of about 135 ft above NGVD 29 in Polk County, this ridge is 

probably the result of a former marine sand bar (White, 1970).

Climate

The climate of Polk County is classified as humid 

subtropical and is characterized by hot, wet summers and 

mild, relatively dry winters. The mean annual temperature 

at Lakeland is 73  ̊F, and the mean monthly temperature 

ranges from a low of about 61  ̊F in January to 83  ̊F in 

August. Temperatures commonly exceed 90  ̊F from June to 

September, and may fall below freezing for a few days in the 

winter months.

Rainfall is unevenly distributed throughout the year. 

About 55 percent of the annual rainfall total is derived from 

thunderstorms that occur frequently during the months of 

June through September. During the summer, thunderstorms 

can produce heavy but localized rainfall, resulting in several 

inches of precipitation falling in one location and little or none 

falling a few miles away. During the summer months and early 

fall, occasional tropical storms and hurricanes also can bring 

heavy precipitation into the area. During the winter, rainfall 

is associated with frontal system activity, which is usually 

of a longer duration and areally more uniform than summer 

convectional precipitation. April and November typically are 

the driest months.

The National Oceanic and Atmospheric Administration 

(NOAA) records indicate that long-term average annual rainfall totals are similar throughout the county. Rainfall data for a 

73-year period from 1931 to 2003 at the Lakeland, Mountain 

Lake, and Avon Park (Highlands County) stations are shown 

in figure 5. The mean annual rainfall was about 51 inches (in.) 

at the Lakeland and Mountain Lake stations and about 53 in. at 

the Avon Park station.

Drought conditions prevailed throughout much of Florida 

during 2000. The lowest annual rainfall totals recorded 

at the Avon Park and Mountain Lake stations occurred in 

2000: 26.10 and 29.53 in., respectively. At the Lakeland 

site, however, the lowest annual rainfall total was 35.83 in. 

measured in 1961. Annual rainfall totals of more than 74 in. 

were measured at both the Avon Park and Mountain Lake 

stations in 1953, and an annual rainfall total of 70.24 in. was 

measured at Lakeland in 1959.

A considerable amount of variation in annual rainfall 

occurs from year to year, sometimes making it difficult to 

determine whether annual rainfall totals changed substantially 

over time. Patterns are apparent at some of the rainfall stations 

(fig. 5). From 1931 to 1960, the average annual rainfall 

was 53.9 and 55.3 in. at Mountain Lake and Avon Park, 

respectively. At Lakeland, the average rainfall was 51.3 in. 

during this period. In contrast, average annual rainfall from 

1961 to 2003 was lower, 48.5 and 50.9 in. at Mountain Lake 

and Avon Park, respectively. At Lakeland, however, the average annual rainfall during this period was not much different 

at 50.1 in.

Several investigators (Barcelo and others, 1990; Flannery 

and Barcelo, 1998; Basso and Schultz, 2003) reported lower 

rainfall amounts in the county from 1960-2000 compared 

to earlier decades. These multidecadal variations in rainfall 

may result from alternating cycles of warmer and cooler 

sea-surface temperatures in the North Atlantic and Pacific 

Oceans. Sea-surface temperatures in the North Atlantic Ocean 

vary by about 0.4 °C, which is referred to as the Atlantic 

Multidecadal Oscillation (AMO) (Enfield and others, 2001). 

These variations in temperature likely are caused by natural 

internal variations in the strength of the ocean thermohaline 

circulations and the associated meridional heat transport. 

Warm phases of the AMO have occurred from 1930-1960 and 

1995-2004, and cool phases have occurred from 1905-1925 

and 1970-1990 (McCabe and others, 2004). Enfield and others 

(2001) have shown the AMO has a strong influence on rainfall 

in the conterminous United States. Warm phases of the AMO 

are correlated with dry conditions in most of the conterminous 

United States; however, in Florida it is generally correlated 

with wet conditions. Sea-surface temperatures in a large 

part of the northern Pacific Ocean also vary on multidecadal 

cycles, which is referred to as the Pacific Decadal Oscillation 

(PDO) (Mantau and others, 1997). These variations also may 

affect rainfall in Florida. When sea-surface temperatures along 

the coast of North America are unusually warm, there is a 

strong tendency for temperatures in the central Pacific Ocean 

to be anomalously cool. This is referred to as a cool phase of 

the PDO. Cool phases of the PDO generally are associated 

with below-average precipitation from March through October 

in the southern United States and have occurred from 1890-

1924 and 1947-76 (Mantau and others, 1997).

McCabe and others (2004) decomposed the drought 

frequency in the Nation into the primary factors affecting 

variability; most of the variability was attributed to the AMO, 

PDO, and a factor related to increasing North American 

temperatures. The effect that both AMO and PDO conditions 

have on droughts in the Nation was analyzed by McCabe 

and others (2004). Under cool AMO conditions and the 

combination of warm AMO and cool PDO conditions, there 

is a tendency for above-normal drought frequency in most 

of Florida. McCabe and Wolock (2002) reported a change in 

precipitation across the eastern Unites States around 1970 that 

may be related to a shift in climatic conditions.
5 YEAR

MOVING

AVERAGE

5 YEAR MOVING AVERAGE

5 YEAR MOVING

AVERAGE

LAKELAND

MOUNTAIN LAKE

AVON PARK

0

10

20

30

40

50

60

70

80

1930 1940 1950 1960 1970 1980 1990 2000

YEAR

RAINFALL, IN INCHES

0

0

10

20

30

40

50

60

70

80

10

20

30

40

50

60

70

80

90

Average rainfall = 50.7 inches

Minimum rainfall = 29.53 inches

Maximum rainfall = 74.91 inches

Average rainfall = 50.9 inches

Minimum rainfall = 35.83 inches

Maximum rainfall = 70.24 inches

Average rainfall = 52.7 inches

Minimum rainfall = 26.10 inches

Maximum rainfall = 80.80 inches

Figure 5. Annual 

rainfall at Lakeland, 

Mountain Lake, and 

Avon Park, Florida, 

1931-2003.

Description of Study Area 
10 Hydrology of Polk County, Florida

Most of the rainfall returns to the atmosphere by 

evapotranspiration, which is defined as the evaporation of 

water from soil and water surfaces and transpiration of plants. 

About 60 percent of the annual evapotranspiration occurs 

from May to October (Southwest Florida Water Management 

District, 1988). Locally, evapotranspiration varies with the 

evaporative demand of the atmosphere and the availability 

of water. The upper limit of evapotranspiration is approximately equal to the rate at which water can evaporate from a 

free-water surface under natural conditions (Tibbals, 1990). 

Evapotranspiration rates are highest in the lakes, swamps, and 

marshes, where water is near or above land surface much of 

the time. Lake evaporation rates measured at Lake Starr in 

Polk County for a 2-year period (August 1996 to July 1998) 

were 57.08 and 55.88 inches per year (in/yr), respectively 

(Swancar and others, 2000).

During 2001-2005, annual evapotranspiration rates 

ranged from 34.0 to 40.2 in/yr (D.M. Sumner, U.S. Geological 

Survey, written commun., 2006) at a Bahia grass/palmetto 

site in eastern Polk County where the water table is shallow 

(fig. 6). The lowest rates of evapotranspiration in Polk County 

occur along the ridges where the surficial sediments are 

permeable and the depth to the water table is greater. Tibbals 

(1990) estimated the relation of evapotranspiration to watertable depth and determined that the minimum rate of evapotranspiration in east-central Florida occurred where the water 

table was greater than 13 ft below land surface. In a study 

along the Lake Wales Ridge in Orange County, Sumner (1996) 

determined an annual evapotranspiration rate of about 27 in. at 

a site with a deep water table. This rate is probably close to a 

minimum evapotranspiration value for central Florida.

Ground-Water Use

The Upper Floridan aquifer is the principal source of 

water supply in Polk County. The aquifer supplies nearly all 

the ground water used for commercial-industrial self-supplied, 

public-supply, domestic self-supplied, agricultural irrigation 

uses, and recreational irrigation. In 2000, about 4 percent 

of the total amount of ground-water withdrawn was from 

the surficial or intermediate aquifer systems in Polk County 

(Marella, 2004). At present (2005), no water is withdrawn 

from the Lower Floridan aquifer in Polk County. Groundwater withdrawals vary from season to season and from year 

to year, primarily as a function of the amount and distribution 

of rainfall. Of the total water withdrawn in 2000, 48 percent 

was used for agricultural irrigation, 23 percent for public 

supply, 21 percent for commercial/industrial self-supplies, 

4 percent for domestic self-supplied, 3 percent for recreational 

irrigation, and 1 percent for thermoelectric power generation 

(fig. 7).

Ground-water use has decreased substantially in Polk 

County since 1965. In 1965, total ground-water withdrawals in 

Polk County were about 350 million gallons per day (Mgal/d) 

(fig. 8). In 2002, withdrawals totaled about 285 Mgal/d. The 

large declines in water use are the result of water-conservation 

practices related to the mining and processing of phosphate 

ore, as well as the decrease in the number of mines operating 

in Polk County. Water use from the commercial/industrial 

self-supplied category, which includes mining, decreased 

from 270 Mgal/d in 1965 to 56 Mgal/d in 2002. Some of this 

decline in water use, however, was partially offset by increases 

in water use for public supply and agriculture. From 1965 to 

2002, water use for public supply increased from 26 to about 

74 Mgal/d. During the same period, agricultural water use 

increased from 52 to 127 Mgal/d.

0

1

2

3

4

5

6

7

2000 2001 2002 2003 2004 2005

ANNUAL

TOTAL FOR 2001 = 34.0 INCHES

ANNUAL FOR 2002 = INCHES

TOTAL 39.7

ANNUAL FOR 2003 = 40

INCHES

TOTAL .2

ANNUAL FOR 2004 = 38

INCHES

TOTAL .0

ANNUAL FOR 2005 = 40

INCHES

TOTAL .2

YEAR

MONTHLY EVAPOTRANSPIRATION,

IN INCHES

Figure 6. Monthly evapotranspiration at the Disney Wilderness Preserve in eastern Polk County, 

August 2000 to December 2005 (D.M. Sumner, U.S. Geological Survey, written commun., 2006).
PUBLIC SUPPLY

23%

DOMESTIC

(self-supplied)

4%

COMMERCIAL /

INDUSTRIAL

21

(self-supplied)

%

AGRICULTURE

(self-supplied)

48%

THERMOELECTRIC

1%

RECREATIONAL IRRIGATION

3%

POLK COUNTY

331 million gallons per day

0

50

100

150

200

250

300

350

400

450

1960 1970 1980 1990 2000 2010

GROUND-WATER, IN MILLION GALLONS PER DAY

YEAR

TOTAL

GROUND-WATER

USE

PUBLIC SUPPLY

COMMERCIAL/ INDUSTRIAL DOMESTIC SELF-SUPPLIED

SELF-SUPPLIED

AGRICULTURE

SELF-SUPPLIED THERMOELECTRIC

RECREATIONAL IRRIGATION

TOTAL GROUND WATER

Figure 7. Total ground-water use, by category, for 2000 (from Marella, 2004).

Figure 8. Historical total ground-water use in Polk County, 1965-2002 (from Marella, 2004; and Southwest 

Florida Water Management District, 2004a, 2004b).

Description of Study Area 11
12  Hydrology of Polk County, Florida
shallow-water marine origin and are composed of limestone, 

dolostone, evaporite, clay, and sand that range in age from 

Late Cretaceous to Holocene. The major stratigraphic units 

of interest in Polk County, from oldest to youngest, are: the 

Cedar Keys Formation of late Paleocene age, the Oldsmar 

Formation of early Eocene age, the Avon Park Formation 

of middle Eocene age, the Ocala Limestone of late Eocene 

age, the Suwannee Limestone of early Oligocene age, the 

Hawthorn Group of late Oligocene to Miocene age, and the 

undifferentiated surficial deposits of Pliocene to Holocene 

ages (fig. 11). Most geologic units cropping out within Polk 

County (fig. 12) are composed of unconsolidated siliciclastic 

sediments. The exceptions, however, are in the extreme northwestern part of the county and along the Peace River, where 

some of the sediments are composed of carbonates.

There are some differences in the geologic nomenclature 

used in earlier water-resource assessments of Polk County 

(Stewart, 1966; Pride and others, 1966) and those used in 

this report (fig. 11). Miller (1986) determined that the Avon 

Park Limestone and the Lake City Limestone could not be 

distinguished from each other on the basis of either lithology or 

fauna; therefore, all of the lithologic units within the Lake City 

Limestone were reclassified as Avon Park Limestone. Miller 

(1986) also recognized that the Avon Park Limestone contained 

a considerable amount of dolostone and should be called a 

formation (Avon Park Formation), rather than a limestone. The 

Ocala Group is now referred to as the Ocala Limestone, and the 

unit previously referred to as the Hawthorn Formation is now 

recognized as the Hawthorn Group (Scott, 1988). Similarly, 

the Tampa Member of the Arcadia Formation was formerly 

referred to as the Tampa Limestone or Tampa Formation.

Stratigraphy

The basal Tertiary unit within the study area is the Cedar 

Keys Formation of late Paleocene age (fig. 11). The Cedar 

Keys Formation generally has extremely low permeability, 

and thus, functions as the sub-Floridan confining unit at the 

base of the Floridan aquifer system. Conformably overlying the Cedar Keys Formation is the Oldsmar Limestone of 

Eocene age. It is composed mostly of limestone and dolostone 

that in places contains inclusions of gypsum and anhydrite. 

These evaporites were deposited in shallow, restricted marine 

basins on emergent areas of the Florida Platform during lower 

sea-level stands. The Avon Park Formation, a thick sequence 

of marine limestone and dolostone, overlies the Oldsmar 

Formation and is characterized by alternating layers of soft 

to well-indurated, fossiliferous, tan to light-brown limestone 

Data Collection

The hydrology of Polk County was described by using 

existing data and new geologic, water-level, and water-quality 

data. Data were obtained from published reports and from 

Federal, State, and County agencies. A network of monitoring 

wells was established for the collection of water levels and 

ground-water samples from the surficial, intermediate, and 

Floridan aquifer systems. Data-collection sites were inventoried based on a review of existing wells and available waterlevel and water-quality data in the study area. The locations 

of wells and springs used for the collection of water-level and 

water-quality data are shown in figures 9 and 10, respectively. 

Well construction information is presented in appendix 1.

Geologic and geophysical information from more than 

300 wells was used to construct hydrogeologic maps and 

cross sections of the surficial aquifer system, the intermediate 

aquifer system/intermediate confining unit, and the Floridan 

aquifer system in Polk County. This information was obtained 

from the files of the USGS, FGS, SWFWMD, SFWMD, and 

from published reports. The data that were analyzed include 

borehole geophysical logs and lithologic descriptions of well 

cuttings by geologists and drillers.

Three surficial aquifer system monitor wells were 

constructed in areas where data were not available. These 

wells were installed near existing wells that tap the Upper 

Floridan aquifer to provide a comparison of water levels and 

water quality between the two aquifers. Split-spoon samples 

were collected every 5 ft and were used to provide additional 

data on surficial aquifer system lithology. The altitude of the 

measuring points of monitoring wells was determined by 

instrument leveling.

Water samples collected by the USGS and State agencies from 130 wells between 1998 and 2003 were used to 

characterize ground-water quality in Polk County (fig. 10). 

Water-quality samples from 53 wells and 1 spring in Polk and 

adjacent counties were collected specifically for this project 

by the USGS and analyzed for common inorganic constituents 

and nutrients, mostly in 2003. Sampled wells include public 

supply, domestic, irrigation, and dedicated monitoring wells.

Geologic Framework

The study area is underlain by a thick sequence of 

sedimentary rocks that has a minimum thickness of about 

5,300 ft, as shown by a deep oil test well at Mulberry (Davis 

and Associates, 1981). These sediments are predominantly of 

 CHAPTER 1—Ground-Water Resources of Polk County

 13
14  Hydrology of Polk County, Florida

and brown, crystalline dolostone. The Avon Park Formation 

typically is highly fractured and cavernous. Inclusions of 

gypsum and anhydrite nodules also occur within the lower part 

of the Avon Park Formation (Navoy, 1986). The formation is 

distinguished from overlying formations by the abundance of 

cone-shaped foraminifera of the genus Dictyoconus. The top 

of the Avon Park Formation ranges from about 0 ft NGVD 29 

in northeastern Polk County to about 700 ft below NGVD 29 

in the extreme southwestern part of the county (Arthur and 

others, 2007).

An erosional unconformity separates the Avon Park 

Formation from the overlying Ocala Limestone of late Eocene 

age (Stewart, 1966). The Ocala Limestone can contain two 

distinct lithologic units. The lower unit consists of a white-tocream to dark-brown, granular, fossiliferous, well-indurated, 

dense, limestone and dolostone. The upper unit is described 

as a white-to-cream or tan, fossiliferous, generally poorly 

indurated, pure limestone. The Ocala Limestone is recognized 

by the disc-shaped foraminifera of the genus Lepidocyclina. 

The top of the Ocala Limestone ranges from about 75 ft above 

NGVD 29 in the extreme northwestern part of the county to 

about 450 ft below NGVD 29 in the extreme southwestern 

part of the county (Arthur and others, 2007). In the extreme 

northwestern part of the county, the Ocala Limestone is at or 

near land surface (Stewart, 1966).

Overlying the Ocala Limestone is the Suwannee Limestone 

of early Oligocene age. The Suwannee Limestone has undergone extensive erosion and is absent in much of the northern 

and extreme eastern part of the county (Arthur and others, 

2007). The limestone is white, cream, or tan, fossil­iferous, 

Figure 9. Location of wells with periodic or continuous water-level data (well numbers and information in appendix 1).

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

.

9 8 7 6

5

4

2 1

99 97

96 95

91 92

89

84 88 83

82

81 80

78

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76

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62 60 59 58 57

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10

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114

113

112

111

110

108 107 103 101

100

206

102 106

105

47 53

66

65

267

196

214

52

St. Cloud well

238

237

236

99

EXPLANATION

WELL LOCATION

AND NUMBER

Lakeland

Bartow

Winter

Haven

Mountain

Lake

Avon Park
poorly to well-indurated and variably recrystallized. The 

limestone can be interbedded with calcilutite (calcareous mud, 

greater than 50 percent silt or clay-size carbonate particles) 

and calcarenite (calcareous sand, greater than 50 percent 

sand-size carbonate particles) units. The top of the Suwannee 

Limestone ranges from about 75 ft above to about 250 ft 

below NGVD 29 (Arthur and others, 2007). The Suwannee 

Limestone generally is distinguished from the overlying 

Hawthorn Group by the lack of phosphatic sand.

Unconformably overlying the Suwannee Limestone 

is the Hawthorn Group of late Oligocene to Miocene age. 

Although originally believed to be Miocene in age, more 

recently the Hawthorn Group has been interpreted to include 

late Oligocene-aged sediments as well (Scott and others, 

2001). Scott (1988) reclassified the sediments of the Hawthorn 

to group status because of its areally extensive and mapable 

lithologic units. In southern peninsula Florida, the Hawthorn 

Group includes, in ascending order, the Arcadia and Peace 

River Formations. The Arcadia Formation may contain up 

to two named members, in ascending order, the Nocatee and 

Tampa Members. Where both of these members cannot be 

identified, the section is referred to as the Arcadia Formation 

(Scott, 1988). The Arcadia Formation is composed of limestone and dolostone containing varying amounts of quartz 

sand, clay, and phosphate grains. Thin beds of quartz sand and 

clay are scattered throughout the section and generally are 

calcareous or dolomitic and phosphatic (Scott, 1988). The top 

of the Arcadia Formation ranges from about 100 ft above to 

more than 100 ft below NGVD 29 (Scott, 1988). The unit is 

absent in the northern part of the study area.

Figure 10. Location of wells and spring where water-quality data were collected from 1998-2003 (well numbers and 

information in appendix 1).

Geologic Framework 15

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

St. Cloud well

6

3

5 9

7

4

2

93 90

88 87

85 83

76 73 66

59

53

42 48 44

34

29

28 25

21 20

11

98

69

54

39

37

23

19

92

15

79

89

86

77

72 68 61 51

43 40 36 35

31 27

24

22

264

261

255

243

235 230

218

201

183

174

171 166

165 162 160

155

148 141 147

140 135

125 112 109

190

172

159

130

111

101

156

263

256

253 252

251

244 242

234 229

224 223

222 221 219

214 207 204 202 198 195

192 188 187 184

178

175 168 164

158

157

153

149 142

134

132 121 126

120 116 113

110 104

103

94

65

117

9

EXPLANATION

WELL LOCATION AND NUMBER

SPRING LOCATION AND NUMBER 201
16  Hydrology of Polk County, Florida

SERIES STRATIGRAPHIC UNIT GEOLOGY

AND LITHOLOGY HYDROGEOLOGIC UNIT

Holocene and

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Undifferentiated

surficial deposits

Sand

Surficial aquifer

system

Sand, clay

Hawthorn

Group

Peace River

Formation

Arcadia

Formation

Phosphate,

clay, sand,

limestone,

and

dolostone

Intermediate aquifer system or

Intermediate confining unit

Tampa

Member

Nocatee

Member

Suwannee Limestone

Ocala Limestone

Avon Park Formation

Oldsmar Formation

Cedar Keys Formation

Limestone

and dolostone

Upper Floridan aquifer

Middle

confining unit

Lower

Floridan aquifer

Sub-Floridan

confining unit

Limestone and

Floridan aquifer system

dolostone with some

intervals containing

inclusions of gypsum

and anhydrite

Limestone and

dolostone with beds

of gypsum and

anhydrite

Bone Valley

Member

Middle semiconfining unit

Cypresshead

Formation

Confining unit

Confining unit

Confining unit

Zone 2

Zone 3

Upper permeable

zone

Semi-confining unit

Lower permeable

zone

Figure 11. Relation of stratigraphic and hydrogeologic units (modified from Barr, 1992; Tihansky and others, 1996; O’Reilly and 

others, 2002; Sepúlveda, 2002; and Basso and Hood, 2005).
The lowermost sediments of the Arcadia Formation form 

the Nocatee Member. The Nocatee Member consists of a 

complexly interbedded sequence of variably phosphatic quartz 

sands, clays, and carbonates (Scott, 1988). Previously, this unit 

was called the “sand and clay unit” of the Tampa Limestone 

by Wilson (1977). In Polk County, the top of the Nocatee 

Member ranges from about 0 to more than 200 ft below 

NGVD 29 (Arthur and others, 2007). The unit is absent in all 

but the southwestern part of the county.

The Tampa Member of the Arcadia Formation consists 

predominantly of limestone and subordinate dolostone, sand, 

and clay. Phosphate concentrations are low, generally less than 

3 percent (Scott, 1988). The top of the unit ranges from about 

50 ft above to 150 ft below NGVD 29 and is present only in 

southwestern Polk County (Arthur and others, 2007).

Unconformably overlying the Arcadia Formation is 

the Peace River Formation. The Peace River Formation is 

composed of interbedded quartz sand, clay, and carbonates, 

with variable amounts of phosphate. Siliciclastics, however, 

are the predominant lithology, comprising more than twothirds of the formation (Scott, 1988). The Peace River 

Formation is present throughout most of Polk County. The top 

of the unit generally ranges from about 125 ft above to 125 ft 

below NGVD 29 (Arthur and others, 2007).

The unit formerly called the Bone Valley Formation was 

reclassified by Scott (1988) to member status within the Peace 

River Formation. The Bone Valley Member is a clastic unit 

consisting of pebble or gravel-sized phosphate fragments and 

sand-sized phosphate grains in a matrix of quartz sand and 

clay (Scott, 1988). The presence of phosphate gravels in the 

To

Ts

TQuc

TQuc

TQuc Thpb Thpb

Thpb

Thpb

Qu

Qu

Qu

Qu

Qu

Qu

Tc

Tc

Tc

Tc

Tc

Tc Tc

Tc

Tc

Tc

Tc

Thpb

TQd

TQd

Qh

Qh

Qh

TQuc

TQd

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

EXPLANATION HOLOCENE

PLEISTOCENE / HOLOCENE

PLIOCENE / PLEISTOCENE

PLIOCENE

MIOCENE / OLIGOCENE

OLIGOCENE

EOCENE

28°15′

28°00′

27°45′

Qh Holocene sediments

Qu Undifferentiated sediments

TQd Dunes

TQuc Reworked Cypresshead

Formation

Tc Cypresshead Formation

Thpb Hawthorn Group,

Peace River Formation,

Bone Valley Member

Ts Suwanee Limestone

To Ocala Limestone

Figure 12. Geologic map of Polk County (from Scott and others, 2001).

Geologic Framework 17
18  Hydrology of Polk County, Florida

Bone Valley Member is the most important lithologic factor 

in the differentiation of this member from the remainder of 

the Peace River Formation. The unit extends over much of the 

southwestern part of Polk County, where it attains a maximum 

thickness of about 50 ft (Scott, 1988). Because of its thickness 

and high concentration of phosphate, the Bone Valley Member 

has been extensively mined in Polk County. The top of the unit 

ranges from more than 120 ft to about 60 ft above NGVD 29 

(Arthur and others, 2007).

Overlying the Hawthorn Group are the undifferentiated 

clastic (surficial) deposits of Pliocene to Holocene age, which 

includes the Cypresshead Formation. The undifferentiated 

surficial deposits consist primarily of sands, clayey sands, 

and clay. These deposits are present throughout most of Polk 

County, except in the extreme northwestern part of the county 

and along parts of the upper Peace River, where at a few locations, limestone is exposed at land surface. The quartz sands, 

which make up the upper part of the unit, are fine-to-coarse 

grained and reach their maximum thickness under the Lake 

Wales Ridge.

Karst Features

The soluble limestones and dolostones that underlie 

Polk County have been sculptured by dissolution and 

weathering processes to form what is known as karst terrain. 

Characteristic features of karst terrains that are directly related 

to carbonate dissolution and ground-water flow include sinkholes, springs, caves, disappearing streams, internally drained 

basins, and subsurface drainage networks. Water percolating 

through the upper soil zone combines with carbon dioxide, 

forming a slightly acidic solution. This water passes through 

insoluble sediments until it reaches the underlying carbonates. 

These carbonate rocks may be fractured, jointed, and have 

many voids and cavities that provide conduits for water flow. 

The voids or fractures can range in size from small vugs to 

large caverns. Acidic water passing through these openings 

slowly dissolves the carbonate rocks, and, over a long period 

of time, results in the formation of enlarged conduits and cavities. As the solution caverns become larger, in some instances, 

the roofs may not be able to support the overlying sediment. 

Collapse of the cavity roofs is evident today as sinkholes and 

sinkhole depressions.

Sinkholes most commonly develop in areas where 

ground-water recharge rates are rapid and where the overlying 

siliciclastic sediments are relatively thin or very permeable. 

Although sinkholes in all stages of development are common 

throughout Polk County, most occur along the ridges and 

range from small depressions to large lakes (fig. 13). These 

sinkholes, which often are filled with permeable surficial 

sands, provide more direct avenues for water from the surficial 

aquifer system to recharge the underlying Upper Floridan 

aquifer. The locations of sinkholes and depressions in Polk 

County are shown in figure 14. The features presented, which 

range from about 10 ft to several hundred feet in diameter, 

were delineated from USGS topographic maps. Also included 

may be some man-made features, which can be indistinguishable from the natural features on the topographic maps. Many 

of the natural lakes, ponds, and topographic depressions in 

the county were formed by sinkholes. Larger lakes often were 

formed by the coalescence of several sinkholes. Continuous 

high-resolution seismic-reflection surveys of lakes on the 

Lake Wales Ridge indicate that many of these lakes likely 

were formed by subsidence activity (Lee and others, 1991; 

Sacks and others, 1992; Evans and others, 1994; Tihansky and 

others, 1996).

The existence of karstic features along the upper Peace 

River and adjacent floodplains between Bartow and Fort 

Meade (fig. 1) provide a direct hydraulic connection between 

the river and aquifers at some locations (Lewelling and others, 

1998). The Peace River in this area is characterized by shallow, sometimes exposed carbonate units, with karst features 

that vary in type and size and include sinkholes, subsidence 

depressions, dissolution pipes, and enlarged fractures. Patton 

(1981) and Patton and Klein (1989) mapped more than 90 

sinkholes in the upper Peace River floodplain. Along this 

stretch of the river, the water level in the river often is higher 

than water levels in the underlying aquifers. The downward 

head gradient allows the Peace River to lose water to the 

ground-water system through sinkholes and conduits (fig. 15).

Ground-Water Resources

The hydrogeologic system in the study area consists of 

a series of clastic deposits underlain by a thick sequence of 

carbonate rocks. The stratigraphic units underlying the county 

form a layered sequence of aquifers and confining units. 

Each aquifer system has unique hydraulic characteristics that 

determine its potential for water supply.

The uppermost water-bearing unit is the surficial aquifer 

system. This aquifer system is underlain by and separated 

from the Floridan aquifer system by the intermediate confining 

unit or the intermediate aquifer system, both of which restrict 

the movement of water between the overlying and underlying 

aquifers. The lowermost hydrogeologic unit underlying the 

county is the Floridan aquifer system (fig. 11). The Floridan 

aquifer system has two major water-bearing zones (Upper 

Floridan aquifer and Lower Floridan aquifer), which are separated by a less-permeable middle semiconfining unit and/or a 

middle confining unit. Underlying the Floridan aquifer system 

are low-permeability limestone and dolostone that contain 

considerable gypsum and anhydrite, and define the base 

of the Floridan aquifer system. Generalized hydrogeologic 

sections (locations shown in fig. 16), based on geophysical and 

geologic logs, are shown in figures 17 and 18. The sections 

show the relative positions of the surficial, intermediate, and 

Floridan aquifer systems. Stratigraphic units, general lithology, and corresponding hydrogeologic units underlying Polk 

County are given in figure 11.
Surficial Aquifer System

The surficial aquifer system is unconfined and consists 

of unconsolidated clastic deposits that range in age from 

Pliocene to Holocene. The unit is composed primarily of 

fine- to medium-grained quartz sand near land surface that 

grades with depth to silty and clayey sands. The lithology and 

texture of the sediments within the surficial aquifer system can 

vary considerably both vertically and laterally. The base of the 

surficial aquifer system is defined by the first persistent beds 

of Miocene or Pliocene age sediments containing a substantial 

increase in clay or silt.

Thickness of the surficial aquifer system in Polk County 

is variable. A generalized contour map of the thickness of the 

surficial aquifer system is shown in figure 19. The thicknesses 

shown in figures 17 to 19 represent the thickness of both 

saturated and unsaturated undifferentiated sediments. In much 

of the western one-third of the county, thicknesses generally are less than 50 ft. In the Green Swamp area where the 

Upper Floridan aquifer is near land surface, deposits from the 

surficial aquifer system may be only a few feet thick or less. 

Along parts of the Peace River south of Bartow, the surficial 

aquifer system exists as thin sand units within the streambed 

and exposed cut banks that may be several feet or less in 

0 1 MILE

0 1 KILOMETER

.5

.5

Figure 13. Sinkhole-formed lakes near Winter Haven, Florida (source: Land Voyage 15-meter satellite).

Ground-Water Resources 19
20 Hydrology of Polk County, Florida

thickness (Lewelling and others, 1998). The surficial aquifer 

system generally thickens toward the east, especially along the 

southern part of the Lake Wales Ridge where the thickness can 

exceed 200 ft.

The surficial aquifer system is recharged primarily by 

the infiltration of rainfall. Much of the rain that falls in the 

study area, however, drains into streams or lakes or is lost 

to evapotranspiration. The remaining rainfall percolates into 

the unsaturated surficial deposits and recharges the surficial 

aquifer system. In extreme eastern Polk County, the surficial 

aquifer system also is recharged by the upward leakage of 

water from the Upper Floridan aquifer where heads in the 

underlying Upper Floridan aquifer are higher than in the surficial aquifer system. Other sources of recharge include the land 

application of wastewater and reclaimed water, septic-tank 

effluent, irrigation of agricultural land or residential areas, 

and lateral ground-water inflow from adjacent areas. Water 

is discharged from the surficial aquifer system by evapotranspiration; by seepage into lakes, wetlands, and streams; 

by downward leakage to the Floridan aquifer system in areas 

where the potentiometric surface of the Upper Floridan aquifer 

is below the water table; and by pumpage.

Even though most water in the surficial aquifer system 

flows vertically to recharge the Upper Floridan aquifer, there 

is also a lateral component of flow. The lateral direction in 

which the water flows in the surficial aquifer generally is 

governed by the topography. Water in the surficial aquifer 

system usually flows laterally from areas of higher altitude 

and discharges into lakes, streams, and wetlands in areas of 

lower altitude. The altitude of the water table varies from one 

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

EXPLANATION

SINKHOLE OR DEPRESSION

FEATURE -- Features were

delineated from 1:24,000

U.S. Geological Survey

topographic maps

LAKE

STREAM

Figure 14. Location of sinkholes and depressions in Polk County.
physiographic region to another. In low, flat, poorly drained 

areas, such as in the Green Swamp area in northern Polk 

County, the water table generally is at or near land surface 

throughout most of the year. The stage of the streams and 

lakes also represents the altitude of the water table. In areas of 

relatively high land-surface altitude, the water table generally 

is a subdued reflection of land-surface topography, but can be 

as much as 100 ft below land surface in some areas along the 

Lake Wales Ridge (Yobbi, 1996). In addition to the influence 

of topography, the slope of the water table varies depending 

on the hydrologic conditions, such as antecedent rainfall and 

evapotranspiration rates (Knochenmus, 1976). During wet 

periods when rainfall exceeds evapotranspiration, the slope of 

the water table steepens as the storage of water in the surficial 

aquifer system increases. During dry periods, the slope flattens 

as water drains from storage or is lost to evapotranspiration.

The altitude of the water table in the surficial aquifer 

system fluctuates in response to seasonal changes in precipitation and evapotranspiration. Water levels also may fluctuate in 

response to pumpage and may be affected by the manipulation 

of streamflows. Hydrographs for selected wells completed in 

the surficial aquifer system (fig. 20) show that water levels 

generally are highest in September or October, which is at or 

near the end of the wet season. Water levels gradually decrease 

to their lowest levels in April or May, which is the end of the 

dry season.

Although the range of water-level fluctuation in wells 

from the surficial aquifer system varies over the county, 

seasonal fluctuations of water levels average about 1 to 5 ft. 

The magnitude of seasonal water-table highs and lows are 

controlled mostly by local variations in rainfall. Rainfall 

events can cause sharp rises in water level in the surficial 

aquifer system, whereas lack of rainfall causes a gradual 

decline. Extended periods of drought also can affect water 

levels. Water levels in some wells from the surficial aquifer 

system declined to record or near-record lows in 2000 and 

2001, when annual rainfall averaged about 21 and 27 in. 

below normal at the Mountain Lake and Avon Park stations, 

respectively. For the same amount of rainfall, however, the 

magnitude of water-level fluctuations may differ spatially 

depending on variations in permeability and porosity of the 

sediments, and on the depth to the water table. For example, 

Figure 15. Loss of water from the Peace River through underlying conduit 

during low-flow period, May 2004.

Ground-Water Resources  21
22  Hydrology of Polk County, Florida

in areas where the unsaturated zone is relatively thin, water 

levels respond quickly to rainfall, generally peaking within 

1 or 2 days following the event. In areas where the unsaturated 

zone is thick, water levels in the surficial aquifer system wells 

can take weeks before responding to rainfall (O’Reilly, 1998; 

Swancar and others, 2000; Knowles and others, 2002).

Hydraulic properties of the surficial aquifer system vary 

considerably across the county and are dependent largely upon 

aquifer thickness, grain-size distribution, sorting, packing, 

and cementation of the sediments within the aquifer. These 

properties are reflected in values of transmissivity, storage 

coefficient, hydraulic conductivity, and specific capacity 

that indicate the ability of an aquifer to yield water to wells. 

Few data are available on the hydraulic characteristics of the 

surficial aquifer system in Polk County. Horizontal hydraulic 

conductivity values determined for the surficial aquifer system 

from six wells in Polk County ranged from 0.3 to 55 feet per 

day (ft/d) (Southwest Florida Water Management District, 

2000). Field horizontal hydraulic conductivity determined 

from slug tests performed on 30 surficial aquifer system 

monitoring wells in adjacent Lake County and the Ocala 

National Forest ranged from 0.2 to 35 ft/d (Knowles and other, 

2002). Adamski and German (2004) reported field horizontal 

hydraulic conductivity values that ranged from 0.05 to 30 ft/d, 

which were determined from slug tests performed on 21 

surficial aquifer system wells in adjacent Orange County. 

Additional hydraulic conductivity values reported in wells in 

adjacent southeastern Hillsborough and northwestern Hardee 

Counties ranged from 18 to 102 ft/d. CH2MHill (1989) 

reported horizontal hydraulic conductivity of the surficial 

Figure 16. Location of hydrogeologic sections.

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY

PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

Disney

Wilderness

Preserve

A

A ′

B

B ′

C

C ′

D

D ′

W-662

ROMP 87

ROMP 76

PK 7427

PK 7434

PK 7435

W-12269

W-6182

ROMP 60

ROMP 59

W-1801 W-9276

ROMP 57

ROMP 57X

W-11179

W-9132

PK 7618

815-157-2

W-6863

W-3852

Romp 40

W-5471

(POF-1)

W-10248

ROMP 44

ROMP 55

W-2842

A A ′

WELL NAME

LINE OF HYDROGEOLOGIC

SECTION

EXPLANATION

ROMP 55
WEST EAST

A A’

B B’

600

500

400

300

200

100

100

200

300

0

VERTICAL SCALE GREATLY EXAGERRATED 0 10 MILES

0 10

5

5 15 KILOMETERS

FEET

WEST EAST

600

500

400

300

200

100

100

200

300

0

FEET

600

500

400

300

200

100

100

200

300

0

FEET

600

500

400

300

200

100

100

200

300

0

FEET

ROMP 60

Section C - C’

ROMP 59

W-1801

W-9276

W-9132

W-11179

ROMP 57

Section D - D’

ROMP 57x

W-662

ROMP 87Section C - C’

ROMP 76

PK7427

PK7434

PK-7435

W-12269Section D - D’

W-6182

Disney Wilderness Preserve

INTERM EDIATE

CONFINING UNIT

AQUIFER SYSTEM INTERM EDIATE

AQUIF ER

SYS TEM

SURFICIAL

UNIT

FLORIDAN

AQUIFER

SYSTEM

FLORIDAN

AQUIFER

SYSTEM

INTERMEDIATE CONFINING

Figure 17. Generalized hydrogeologic sections A-A’ and B-B’ (section lines shown in fig. 16).

Ground-Water Resources  23
24  Hydrology of Polk County, Florida

600

500

400

300

200

100

0

100

200

300

NORTH SOUTH

C C’

FEET

NORTH SOUTH

D D’

VERTICAL SCALE GREATLY EXAGERRATED 0 10 MILES

0 10

5

5 15 KILOMETERS

600

500

400

300

200

100

0

100

200

300

FEET

600

500

400

300

200

100

0

100

200

300

FEET

600

500

400

300

200

100

0

100

200

300

FEET

SURFICIAL

AQUIFER

SYSTEM

PK7618

815-157-2

ROMP 87

Section A - A’

W-6863

ROMP 60

B’ Section B -

W-3852

ROMP 40

W-5471

W-12269

Section A - A’

W-10248

ROMP 57

B B’ Section -

ROMP 44

ROMP 55

W-2842

INTERMEDIATE

AQUIFER

INTERMEDIATE SYSTEM

CONFINING

UNIT

AQUIFER

INT E RM EDIAT E A Q U I F E R S Y S T E M

SURFICIAL SYSTEM

I N T E R M E D I A T E

C O N F I N I N G

U N I T

FLORIDAN

AQUIFER

SYSTEM

FLORIDAN

AQUIFER

SYSTEM

Figure 18. Generalized hydrogeologic sections C-C’ and D-D’ (section lines shown in fig. 16).
aquifer system ranging from 25 to 160 ft/d, based on slug tests 

conducted in the Lake Wales Ridge in extreme southwestern 

Orange County. Transmissivity estimates from surficial aquifer 

system wells ranged from 8 to 2,400 feet squared per day 

(ft2/d) in Polk County to 535 to 5,300 ft2/d in nearby wells in 

southeastern Hillsborough and northwestern Hardee Counties 

(fig. 21). Barr (1992) determined an average specific yield of 

0.25 for the surficial aquifer system in Polk County.

The surficial aquifer system is not widely used as a 

source of water supply because, relative to the underlying 

aquifers, its permeability is low, resulting in low yields. 

In addition, water from the surficial aquifer system often 

contains high concentrations of dissolved iron or can contain 

substantially higher concentrations of nutrients, pesticides, 

or bacteria than water from underlying aquifers. According 

to Marella (2004), less than 1 percent of the total ground 

water used in Polk County comes from the surficial aquifer 

system. Lawn irrigation and domestic supply are the main 

uses of water from this aquifer. Well yields depend on 

the thickness and permeability of the aquifer system and 

generally range from 10 to 50 gallons per minute (gal/min) 

(Barr, 1992).

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

100

100

100

150

150

200

150

100

25

25

25

25

50

50

50

25

25

25

5

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

Lakeland

Polk City

Davenport

Bartow Lake Wales

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

LINE OF EQUAL THICKNESS -- Shows thickness

of the surficial aquifer system.

Dashed where approximate. Contour intervals

are variable

WELL CONTROL POINT

100

Figure 19. Generalized thickness of the surficial aquifer system.

Ground-Water Resources  25
26  Hydrology of Polk County, Florida

Intermediate Confining Unit and Intermediate 

Aquifer System

The surficial aquifer system underlies the intermediate 

confining unit or intermediate aquifer system of late Oligocene 

to Pliocene age. These deposits have varying degrees of 

permeability, consisting of permeable sands or carbonates, or 

relatively impermeable layers of clay, sandy clay, or clayey 

carbonates.

The intermediate confining unit is present throughout 

much of northern and eastern Polk County (fig. 22). The 

intermediate confining unit serves as a confining layer (except 

where breached by sinkholes) that restricts the vertical movement of water between the surficial aquifer system and the 

underlying Upper Floridan aquifer. The unit consists mostly of 

interbedded clay, silt, phosphate, and sand, but includes some 

limestone and dolostone of the Hawthorn Group. In many 

areas, the intermediate confining unit also can include lowpermeability clay and silt layers of early Pliocene age.

Data from geologic and geophysical logs and from 

published reports were used to construct generalized maps of 

the top and thickness of the intermediate confining unit and 

intermediate aquifer system (figs. 22 and 23, respectively). 

The top of the intermediate confining unit (defined as the 

first persistent clays of Pliocene or Miocene age) ranges from 

about 100 ft above NGVD 29 in the northwestern part of the 

county to more than 50 ft below NGVD 29 in the southeastern 

part of the county. Thickness of the intermediate confining 

unit generally ranges from less than 25 ft in the northern 

part of the county to more than 200 ft in the southeastern 

part of the county. The unit is locally thin or absent in the 

extreme northwestern part of Polk County. Thickness of the 

unit is variable throughout Polk County due to past erosional 

processes and sinkhole formation.

The intermediate aquifer system is present in southwestern Polk County, where the intermediate confining unit grades 

into more permeable sediments of the Peace River and Arcadia 

Formations. These deposits are a source of water supply and 

have sufficient permeability to warrant being referred to as 

1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005

YEAR

WATER LEVEL, IN FEET ABOVE NGVD 29

77

78

79

80

81

82

83

84

112

114

116

118

120

122

124

126

128

76

ROMP CL-2 SITE

WELL NUMBER: 34

TOTAL DEPTH: 22 feet

ROMP 58 SITE

WELL NUMBER: 118

TOTAL DEPTH: 60 feet

Figure 20. Water levels at selected wells tapping the surficial aquifer system (well locations 

shown in fig. 9).
an aquifer system. The intermediate aquifer system includes 

all water-bearing and confining units between the base of 

the surficial aquifer system to the top of the Floridan aquifer 

system. Generally, the intermediate aquifer system includes an 

upper confining unit of clayey sand, clay, shell, and marl, and 

a lower confining unit of sandy clay and clayey sand (Yobbi, 

1996). These confining units are highly variable both spatially 

and vertically. Lying between these confining units in Polk 

County are one or two water-producing zones, which also 

are separated by another confining unit. The water-producing 

zones are composed primarily of clastic sediments interbedded with carbonate rocks (Yobbi, 1996; Basso, 2003). As a 

whole, however, the entire system, including the water-bearing 

units, restricts vertical movement of ground water between 

the overlying surficial aquifer system and underlying Upper 

Floridan aquifer.

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

___ 16

3

20 ___

3

___8

--

950

___

--

775

___

--

2,200

____

3 ___ 535

-- 668

___

--

____ 2,400

--

5,300

____

--

1,900

____

-- ___ 760

--

1,800

____

--

___ 265

--

___ 670

27

___ 740

21

640

___

33 ___ 390

75

270

___

46

160

___

33

160

___

97

2,600

____

32

1,400

____

40

3,800

____

--

170

___

135

8,800

____

38

5,000

____

101

13,300

_____

89

4,600

_____

150

___ 280

--

EXPLANATION

TRANSMISSIVITY OF THE SURFICIAL

AQUIFER SYSTEM -- Top number is transmissivity,

in feet squared per day. Bottom number is open

hole interval of well, in feet; -- data not available

TRANSMISSIVITY OF ZONE 2 OF THE

INTERMEDIATE AQUIFER SYSTEM --

Top number is transmissivity, in feet

squared per day. Bottom number is

open hole interval of well, in feet

20 ___

3

160

___

33

TRANSMISSIVITY OF ZONE 3 OF THE

INTERMEDIATE AQUIFER SYSTEM --

Top number is transmissivity, in feet squared

per day. Bottom number is open hole interval

of well, in feet

33

TRANSMISSIVITY OF THE INTERMEDIATE

AQUIFER SYSTEM, ZONE UNKNOWN --

Top number is transmissivity, in feet squared per day.

Bottom number is open hole interval of well, in feet;

-- data not available

___ 640 --

3,800 ___

Lakeland

Polk City

Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Figure 21. Transmissivity of the surficial and intermediate aquifer systems (from Pride and others, 1966; Hutchinson, 1978; 

and Southwest Florida Water Management District, 2000).

Ground-Water Resources  27
28  Hydrology of Polk County, Florida

Basso (2003) determined that the transitional boundary 

where these sediments change from a confining unit to an 

aquifer system (with associated confining units) begins in 

western Polk County, extending north to Auburndale, then 

south to the western side of the Lake Wales Ridge (fig. 22). 

The lateral extent and water-bearing potential of the various 

zones within the intermediate aquifer system can be highly 

variable because the water-bearing zones can be thin in places 

and contain a mixture of shell, sand, and carbonate beds that 

are interbedded within a clay matrix. This heterogeneous 

sequence often results in low overall permeability of the waterbearing zones and complicates mapping the lateral extent 

of each zone (Basso and Hood, 2005). The line defining the 

extent of the aquifer is approximate, however, and only defines 

the area where the aquifer is most productive. Minor waterbearing units of lower transmissivity may exist outside of the 

boundary, but these are not shown.

The top of the intermediate aquifer system ranges 

from about 100 ft above to more than 100 ft below NGVD 

29 (fig. 22). Thickness of the intermediate aquifer system 

generally ranges from nearly zero, where the permeable zones 

pinch out in central Polk County, to more than 300 ft in the 

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

100

100

100

50

50

100

100

-50

-100

0

0

0

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

Lakeland

Polk City Davenport

Lake

Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

STRUCTURE CONTOUR -- Shows altitude of

the top of the intermediate aquifer system and the

intermediate confining unit. Datum is NGVD 29.

Hachures indicate depression.

Contour interval 50 feet

WELL CONTROL POINT

100

APPROXIMATE

EXTENT OF

INTERMEDIATE

AQUIFER SYSTEM

?

?

?

Figure 22. Generalized altitude of the top of the intermediate confining unit and intermediate aquifer system.
southwestern part of the county (fig. 23). The intermediate 

aquifer system is absent in the northern and eastern part of 

the county, where less-permeable sediments (intermediate 

confining unit) overlie the Floridan aquifer system.

Previous investigators (Barr, 1992; Torres and others, 

2001; Basso, 2003) describe three water-bearing zones within 

the intermediate aquifer system in southwestern Florida, 

which were designated in descending order as PZ1, PZ2, and 

PZ3. Differentiation of these zones was based predominantly 

on visual inspection of rock cores, and was corroborated by 

water-level and water-quality changes and specific-capacity 

data collected during test drilling. Knochenmus (2006), 

however, renamed these vertically stratified permeable units 

in the intermediate aquifer system (in descending order) as 

Zone 1, Zone 2, and Zone 3. This report uses the nomenclature 

of Knochenmus (2006).

In Polk County, only two water-bearing zones are 

present in the intermediate aquifer system—Zones 2 and 3 

(fig. 11). Investigations of these zones indicated that they are 

limited in vertical extent and are present at variable depths 

(Knochenmus, 2006). The uppermost hydrogeologic zone 

(Zone 2) is the most extensive aquifer within the intermediate 

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

200

50

25

50

50

100

100

200

200

300

25

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

Lakeland

Polk

City Davenport

Bartow Lake Wales

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

LINE OF EQUAL THICKNESS -- Shows thickness

of the intermediate aquifer system and the

intermediate confining unit. Dashed where

approximate. Contour interval variable

WELL CONTROL POINT

100

APPROXIMATE

EXTENT OF

INTERMEDIATE

AQUIFER SYSTEM

?

?

?

Figure 23. Generalized thickness of the intermediate confining unit and the intermediate aquifer system.

Ground-Water Resources  29
30 Hydrology of Polk County, Florida

aquifer system in Polk County, occurring throughout much of 

the southwestern part of the county. This water-bearing zone 

is composed primarily of dolostone and limestone units within 

the Peace River Formation and the upper parts of the Arcadia 

Formation (Torres and others, 2001; Basso, 2003; Basso and 

Hood, 2005). Based on limited data, thickness of Zone 2 in 

Polk County ranges from about 24 to 104 ft (Basso and Hood, 

2005). The lowermost water-bearing zone (Zone 3) is found 

only in the extreme south-central part of Polk County. Zone 

3 consists of limestone and dolostone with varying amounts 

of interbedded siliciclastics within the Tampa or Nocatee 

Members of the Arcadia Formation (Torres and others, 2001; 

Basso, 2003; Basso and Hood, 2005).

Recharge to the intermediate aquifer system/intermediate 

confining unit primarily occurs as downward leakage from 

the overlying surficial aquifer system, and more directly, 

through sinkholes, mines, or quarries that breach the confining 

units. Discharge from the intermediate aquifer system occurs 

as pumpage; upward leakage to the surficial aquifer system, 

rivers, and streams; and downward leakage to the Upper 

Floridan aquifer.

Ground-water flow in the intermediate aquifer system 

in Polk County is not well understood. Little is known about 

the continuity of flow zones within the intermediate aquifer 

system. In Polk County, and in much of southwestern Florida, 

the lateral continuity of Zone 2, and to a lesser degree Zone 3, 

is highly variable because the producing zones are thin, can be 

poorly productive, and contain considerable clay.

Water levels for Zone 2 of the intermediate aquifer 

system are shown in figures 24 and 25. Because Zone 2 is 

made up of localized, discontinuous lenses of permeable 

materials that are not laterally connected, potentiometric 

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

99

93

95

91

99 93

94 72

91

84

81 88 80

77

83 88

69

100

107

116

125 122

129

EXPLANATION

WELL -- Number is altitude of water

level in feet above NGVD 29

93

APPROXIMATE

EXTENT OF

INTERMEDIATE

AQUIFER SYSTEM

?

?

?

Lakeland

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Figure 24. Water levels of the intermediate aquifer system (Zone 2), September 2003.
surface contours were not constructed. The construction of 

potentiometric maps implies a regional flow system, and in 

southern Polk County, this likely does not occur.

The water-level map of Zone 2 of the intermediate 

aquifer system for September 2003 (fig. 24) represents 

conditions near the end of the wet season, when withdrawals 

from the Upper Floridan aquifer for agricultural irrigation and 

public supply are near minimum, and water levels generally 

are at their highest. Water in the intermediate aquifer system 

is under confined conditions in most areas where the aquifer 

system occurs. Water levels ranged from about 129 ft above 

NGVD 29 in the southwestern part of the county to less than 

70 ft above NGVD 29 along the Peace River near the Polk 

County-Hardee County line. The May 2004 water-level map 

(fig. 25) represents conditions when ground-water withdrawals 

are at their greatest and water levels are near seasonal lows. 

Water levels ranged from 126 ft above NGVD 29 to about 

62 ft above NGVD 29. Comparison of the September and May 

maps shows a change in water levels that ranges from about 

2 to 14 ft from one season to another. Both maps show that the 

highest water levels occur in the south-central and southwestern parts of the county. The lowest water levels occur in the 

extreme western part of the county and along the southern part 

of the Peace River. A hydrograph for a well open to Zone 2 is 

shown in figure 26.

Water-level maps were not constructed for hydrologic 

unit Zone 3 because of the lack of wells drilled into this zone. 

Because the aquifer is present in only a small part of southern 

Polk County, few wells are available for measurement. A 

hydrograph for a well open to Zone 3 is shown in figure 26.

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

62

70

62

116

68

69

79

86

81

90

79

94

126

122

60

88

97 114

99

95

74

76

73

73

Lakeland

Bartow Lake Wales

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

90 WELL -- Number is altitude of water

level in feet above NGVD 29

APPROXIMATE

EXTENT OF

INTERMEDIATE

AQUIFER SYSTEM

?

?

?

Figure 25. Water levels of the intermediate aquifer system (Zone 2), May 2004.

Ground-Water Resources  31
32  Hydrology of Polk County, Florida

Data on the hydraulic properties of the intermediate 

aquifer system in Polk County are limited and values vary 

considerably because of the variable nature of the lithology 

(Basso, 2003). Transmissivity is variable over short distances, 

which is indicative of lithologic heterogeneity within the 

aquifer system (Yobbi, 1996). Transmissivity estimates for the 

permeable zones of the intermediate aquifer system in Polk 

County, derived from aquifer tests, ranged from 160 to 13,330 

ft2/d (fig. 21). Model-derived transmissivity values for the 

intermediate aquifer system in Polk County ranged from about 

100 to 5,000 ft2/d (Sepúlveda, 2002). Reported transmissivity 

values ranged from 1 to 8,800 ft2/d at 43 sites (Zone 2) and 

from 20 to about 43,000 ft2/d at 36 sites (Zone 3) in southwestern Florida (Knochenmus, 2006).

The intermediate aquifer system is a minor source of 

water supply west of the Lake Wales Ridge and south of 

Lakeland, where it is thicker and more permeable than in other 

areas of the county. Marella (2004) reported that in 2000 about 

11.6 Mgal/d, or about 3 percent of the total ground water used 

in Polk County, was withdrawn from the intermediate aquifer 

system for domestic, industrial, and irrigation uses.

The confining units that occur within the intermediate 

aquifer system have low hydraulic conductivity values and 

restrict the vertical movement of water. Depending on the 

hydraulic gradients, however, these confining units may 

transmit water or allow water to leak from one water-bearing 

unit to another. Leakage between the intermediate aquifer 

system and adjacent aquifers may be upward or downward. 

30

40

50

60

70

80

90

WATER LEVEL, IN FEET ABOVE NGVD 29

1975 1980 1985 1990 1995 2000 2005

YEAR

70

75

80

85

90

95

100

65

60

ZONE 3

ROMP 45 SITE

WELL NUMBER: 39

TOTAL DEPTH: 192 feet

ROMP 59 SITE

WELL NUMBER: 100

TOTAL DEPTH: 142 feet ZONE 2

Figure 26. Water levels at selected wells tapping the intermediate aquifer system (well locations shown in fig. 9).
Field hydraulic data for the confining units are limited, and 

estimates of the hydraulic properties are mainly available 

from regional flow-model simulations. The leakance of the 

intermediate aquifer system is highly variable across the study 

area and depends on the vertical hydraulic conductivity and 

thickness of the confining unit. Leakance values calibrated 

in a regional flow model for the upper confining unit of the 

intermediate aquifer system ranged from 1x10-5 per day (d-1) 

to 3x10-4 d-1, and from 7x10-6 d-1 to more than 1x10-4 d-1 for 

the lower confining unit (Ryder, 1985). In another model, 

simulated leakance of the upper confining unit of the intermediate aquifer system ranged from 1x10-6 d-1 to 6x10-4 d-1

and from 1x10-6 d-1 to 1x10-3 d-1 for the lower confining unit 

(Sepúlveda, 2002). Calibrated leakance for the upper confining 

unit along the Lake Wales Ridge in Polk County ranged from 

1x10-5 d-1 to 1x10-3 d-1 and from 1x10-5 d-1 to 5x10-4 d-1 for 

the lower confining unit (Yobbi, 1996). Model-derived leakance for the entire intermediate confining unit in Polk County 

ranged from about 1x10-5 d-1 to 3x10-4 d-1 (Tibbals, 1990). 

Leakance values are highest along the ridges and the northern 

part of the county where the confining beds are relatively thin, 

permeable, or breached by karst features. The lowest values 

occur in the southern part of the county where karst features 

are less numerous and confining units are relatively thick or 

have lower permeability.

Floridan Aquifer System

The Floridan aquifer system, which is the principal 

source of ground water in Polk County, underlies all of 

Florida and parts of Alabama, Georgia, and South Carolina. 

The Floridan aquifer system, as defined by Miller (1986), is a 

vertically continuous sequence of carbonate rocks of generally high permeability that are mostly of Tertiary age. The 

rocks are hydraulically connected in varying degrees, and 

their permeability generally is one order to several orders of 

magnitude greater than that of the units bounding the system 

above and below. The top of the Floridan aquifer system 

usually coincides with the top of the Suwannee Limestone, 

which is present throughout Polk County except in the 

northern and extreme eastern parts of the county. Where the 

Suwannee Limestone is absent, the top of the aquifer is the 

Ocala Limestone. The base of the system is defined by the 

first occurrence of relatively impermeable, persistent beds of 

gypsum or anhydrite found in the upper part of the Paleoceneage Cedar Keys Formation. Thickness of the Floridan aquifer 

system ranges from about 2,400 to 3,100 ft in Polk County 

(Miller, 1986). The aquifer system includes the following stratigraphic units in descending order: the Suwannee 

Limestone, the Ocala Limestone, the Avon Park Formation, 

the Oldsmar Formation, and the upper part of the Cedar Keys 

Formation (fig. 11).

The Floridan aquifer system is divided into two aquifers 

of relatively high permeability—the Upper Floridan and 

Lower Floridan aquifers (fig. 11). In Polk County, the Upper 

Floridan aquifer contains freshwater, and the Lower Floridan 

aquifer contains more mineralized water. These aquifers are 

separated by less-permeable units called the middle semiconfining and middle confining units, both of which restrict the 

vertical movement of water.

Upper Floridan Aquifer

The geologic units that compose the Upper Floridan 

aquifer include the Suwannee Limestone, the Ocala 

Limestone, and the upper part of the Avon Park Formation 

(fig. 11). A generalized structure contour map of the altitude 

of the top of the Upper Floridan aquifer (top of the Floridan 

aquifer system) is shown in figure 27. The altitude of the 

top of the Upper Floridan aquifer is highest in the northwestern part of the county, where it is more than 50 ft above 

NGVD 29. In a few areas of the Green Swamp in extreme 

northwestern Polk County, the aquifer is at or within a few 

feet of land surface (Pride and others, 1966; Stewart, 1966). 

The top of the aquifer dips toward the south, to more than 

250 ft below NGVD 29 in both the extreme southeastern and 

southwestern parts of the county. The surface of the Upper 

Floridan aquifer is the remnant of an ancient karst plain, and 

generally exhibits considerable irregularity throughout the 

county. Sinkhole-type depressions on the surface of the aquifer 

are common. Thickness of the Upper Floridan aquifer ranges 

from about 300 ft in eastern Polk County to more than 1,200 ft 

in the southwestern part of the county (Ryder, 1985; Miller, 

1986; Basso, 2003). The base of the aquifer is considered to 

be the first occurrence of vertically persistent intergranular 

evaporites in the Avon Park Formation.

Permeability of the Upper Floridan aquifer is not uniform 

with depth. Reports describing well drilling and testing 

indicate the presence of two important water-bearing zones 

separated by a less-permeable zone. In the northern and 

eastern parts of Polk County, where the Suwannee Limestone 

has been removed by erosion, the lower part of the Ocala 

Limestone generally is the uppermost permeable zone of the 

Upper Floridan aquifer. Permeable intervals in this area are 

more dolomitic; may be granular in texture; contain solution features such as caverns, cavities, and pipes; and yield 

moderate amounts of water to wells (Pride and other, 1966; 

Stewart, 1966). In much of the county where the Suwannee 

Limestone is present, the uppermost permeable zone of the 

Upper Floridan aquifer generally coincides with the Suwannee 

Limestone (Stewart, 1966; Basso, 2003). The permeability of 

the Suwannee Limestone appears to be primarily intergranular, with some minor contribution due from moldic porosity 

(Basso, 2003). In parts of the county, the Suwannee Limestone 

may contain solution cavities and conduits due to the thinning 

of the overlying confining unit (Basso, 2003). Wells drilled 

into the Suwannee Limestone generally yield more water than 

those wells drilled into the Ocala Limestone; therefore, many 

domestic and small irrigation wells tap this zone for water 

supply.

Ground-Water Resources  33
34  Hydrology of Polk County, Florida

Underlying the Suwannee Limestone is a semiconfining 

unit that generally corresponds stratigraphically to all or parts 

(mostly the upper part) of the Ocala Limestone, but in some 

areas, also may include the extreme upper part of the Avon 

Park Formation (Basso, 2003). The unit is composed of a soft, 

chalky, fine-grained foraminiferal calcilutite and calcarenitic 

limestone (Basso, 2003).

The lowermost permeable zone of the Upper Floridan 

aquifer occurs in the hard, fractured dolostone within the Avon 

Park Formation, and is the major source of water in the Upper 

Floridan aquifer. Yields from large diameter wells completed 

into this zone can range from 2,000 to 3,000 gal/min (Basso, 

2003). The permeability of the upper Avon Park Formation 

is due primarily to fractures and interconnecting solution 

cavities. The top of the lowermost permeable zone generally is marked by an increase in formation resistivity due to 

the increasing presence of dolostone, and by an increase in 

the occurrence of fractures and solution cavities within the 

carbonates, as indicated by caliper logs (O’Reilly and others, 

2002; Basso, 2003).

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

50

50

0

0

0

-50

-50

-50

-100

-150

-200

-200

-250

0

-150

-100 -100

-150

-250

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

Lakeland

Polk

City Davenport

Lake

Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

STRUCTURE CONTOUR -- Shows altitude

of the top of the Floridan aquifer system.

Datum is NGVD29. Contour interval is 50 feet

WELL CONTROL POINT

50

Figure 27. Altitude of the top of the Floridan aquifer system (modified from Shaw and Trost, 1984; Schiner, 1993; 

Knowles and others, 2002; Arthur and others, 2007).
Spechler and Halford (2001) also showed that two 

water-bearing zones exist in the Upper Floridan aquifer in 

east-central Florida. Flow logs from wells indicate that two 

distinct zones of different permeabilities (referred to in their 

report as Zones A and B) exist in the Upper Floridan aquifer. 

Zone A, which corresponds to about the upper two-thirds of 

the aquifer, generally coincides with the Ocala Limestone. The 

Suwannee Limestone is not present in most of east-central 

Florida. Zone B is equivalent to about the lower one-third of 

the Upper Floridan aquifer and generally coincides with the 

upper part of the Avon Park Formation. The upper part of 

the Avon Park Formation in east-central Florida, like in Polk 

County, generally consists of hard, dense dolostone with abundant fractures and other secondary porosity features and is a 

major source of water in the Upper Floridan aquifer. Hydraulic 

conductivities in Zone B range from 3 to more than 10 times 

greater than the hydraulic conductivities in Zone A (Spechler 

and Halford, 2001).

Transmissivity estimates for the Upper Floridan aquifer 

vary widely across Polk County. Variations from one aquifer 

test to another can be attributed to differences in open-hole 

intervals and well depths, and to the heterogeneous and anisotropic nature of the carbonate aquifer system. Variations in the 

hydraulic characteristics of the rock strata within the Floridan 

aquifer system are complex and are closely related to the 

geologic framework of the system. The porosity and permeability of the rock strata result from a combination of: (1) the 

original texture of the rock; (2) processes that have acted on 

the rock, such as dolomization and recrystalization; (3) joints, 

fractures, and other structural deformities; and (4) mineral 

dissolution and precipitation (Schiner, 1993). Water moves 

through porous limestone and dolostone, and the movement is 

enhanced by fractures and solution features.

Transmissivity estimates for the Upper Floridan aquifer in 

Polk County, as determined from aquifer and specific capacity 

tests, range from about 1,200 to 179,000 ft2/d (fig. 28). Modelderived transmissivity values range from 10,000 to 500,000 

ft2/d (Sepúlveda, 2002). Model-derived transmissivity values 

determined by Yobbi (1996) in the vicinity of the Lake Wales 

Ridge in Polk County range from 12,000 to 130,000 ft2/d. 

Even though these ranges of values are similar, model-derived 

transmissivity values generally are higher than those obtained 

from aquifer tests. This is due to the highly heterogeneous and 

anisotropic nature of the cavernous limestone and dolostone 

and because the wells used in aquifer tests generally tap less 

than the full thickness of the Upper Floridan aquifer (Yobbi, 

1996).

Transmissivity values generally are lowest in the 

northeastern part of the county and highest in the central and 

southwestern part of the county. According to Pride and others 

(1966) and Yobbi (1996), the lower transmissivity values in 

the northern part of the county and in some areas along the 

Lake Wales Ridge can be attributed to the infilling of fractures 

and cavities in the carbonate units of the Upper Floridan 

aquifer by siliciclastic materials.

Middle Semiconfining Unit and Middle 

Confining Unit

In much of Polk County, the Upper and Lower Floridan 

aquifers are separated by the middle semiconfining unit and 

a middle confining unit. The middle semiconfining unit is 

a sequence of softer, relatively less-permeable limestone 

and dolomitic limestone of variable thickness. This unit is 

considered semiconfining because it has lower porosity and 

lacks abundant secondary solution features. The middle 

semiconfining unit (equivalent to the middle confining unit I 

as mapped by Miller, 1986) generally is present in the middle 

one-third of the Avon Park Formation. It is present in the 

eastern part of the county and is believed to extend into much 

of the western part (Miller, 1986). Although individual zones 

can yield moderate amounts of water, flowmeter logs of wells 

located to the northeast in Orange County indicate that this 

unit is considerably less transmissive than either the Upper 

or Lower Floridan aquifers (O’Reilly and others, 2002). Data 

points for estimating the extent and thickness of the middle 

semiconfining unit are nearly non-existent in Polk County. 

Thickness of this unit in extreme northeastern Polk County 

was estimated to be less than 400 ft, based on data collected 

in adjacent Osceola and Orange Counties (O’Reilly and 

others, 2002). Thickness of the unit was estimated to be 507 ft 

at the Polk City test well (well 217) (O’Reilly and others, 

2002) and about 360 ft at the Regional Observation and 

Monitoring-Well Program (ROMP) well (ROMP 74X, well 

203) (Gates, 2003). O’Reilly and others (2002) observed from 

geophysical logs in east-central Florida that the top of the 

unit generally is recognized by a sharp decrease in formation 

resistivity compared to the overlying fractured dolostone, and 

by a sharp decrease in flow as observed on flowmeter logs. 

Caliper logs also show an enlarged borehole when penetrating 

this zone, indicating that the rock is soft and contains few 

fractures or cavities.

In west-central Florida, including all of Polk County, 

there is a separate and distinct second confining unit underlying the middle semiconfining unit. The unit, called the middle 

confining unit (middle confining unit II of Miller, 1986), is 

composed primarily of anhydritic and gypsiferous dolostone 

and dolomitic limestone. This unit generally corresponds to 

the lower part of the Avon Park Formation and is considerably less permeable than the overlying middle semiconfining 

unit. It forms an essentially non-leaky confining bed that 

separates freshwater in the Upper Floridan aquifer from the 

more mineralized water in the underlying rocks. The top 

of the middle confining unit, generally defined as the first 

occurrence of evaporites, ranges from less than 900 ft below 

NGVD 29 in parts of northern Polk County to more than 

1,300 ft below NGVD 29 in the southern part of the county 

(fig. 29).

Ground-Water Resources  35
36  Hydrology of Polk County, Florida

The thickness of the middle confining unit ranges from 

about 100 to 200 ft in much of southern Polk County to as much 

as 762 ft at Polk City in northern Polk County (Miller, 1986; 

O’Reilly and others, 2002). The anomalously thick area occurring in northern Polk County is thought to have been caused by 

incomplete dissolution of evaporites where the deep flow system 

is very sluggish (Miller, 1986). Areas where the evaporites 

are thinner represent areas where more vigorously circulating 

waters have dissolved much of the unit’s interstitial evaporitic 

material, thereby increasing porosity and permeability.

Little information is available on the hydraulic properties of the middle confining unit in Polk County. Hydraulic 

testing of the carbonate rocks containing evaporites in the 

intergranular pore spaces indicates that they are extremely 

low in permeability (Wolansky and others, 1979). Horizontal 

hydraulic conductivities from cores taken at different depths 

within the middle confining unit at the Polk City test well 

generally ranged from about 0.000024 to 0.90 ft/d (Navoy, 

1986). Two samples taken from this interval, however, had 

hydraulic conductivities of 6.6 and 19.0 ft/d, indicating that 

isolated zones of higher hydraulic conductivity exist within 

this confining unit. Horizontal hydraulic conductivity values 

range from 0.002 to 0.04 ft/d, based on packer tests conducted 

on this zone in Hillsborough, Manatee, and Sarasota Counties 

(Basso, 2003). No hydraulic data are available for the middle 

semiconfining unit in Polk County.

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

Lakeland

Polk City

Davenport

Lake Wales Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

EXPLANATION

TRANSMISSIVITY FROM AQUIFER

OR SPECIFIC CAPACITY TEST --

Top number is transmissivity, in feet

squared per day. Bottom number is

open hole interval of well, in feet;

-- data not available

281,000

_______

740

4,300

_____

92

4,900

_____

89

3,500 _____

215

6,000

_____

201 21,000

_____

-- 16,000

_____ -- 3,900

_____

154

4,900

_____

165

4,100

_____

264

6,000

_____

264

96,000

_____ --

13,000

_____

126 92,000

_____

463

10,300

_____

205

70,000

_____

445

96,000

_____

906

99,000

_____

452

66,000

_____

307

16,000

______

233

27,000

_____

622

51,000

______

263

179,000

_____

658

100,000

______

462 107,000

_______

561

152,000

______

660

126,000

______

600

116,000

______

474

150,000

_______

686

281,000

_______

740

1,200 -1,400

_________

170

8,900 ______

740

5,600 ______

708

50,000

______

990 468,000

_______

717

104,000

_____ --

Figure 28. Transmissivity of the Upper Floridan aquifer (from Pride and others, 1966; Shaw and Trost, 1984; Szell, 1993; 

and Southwest Florida Water Management District, 2000).
Lower Floridan Aquifer

The Lower Floridan aquifer is present throughout Polk 

County and underlies the middle confining unit. Because the 

water within the Lower Floridan aquifer is thought to be very 

mineralized throughout much of the county, and sufficient 

amounts of water can be obtained from the Upper Floridan 

aquifer, few wells have been drilled into the Lower Floridan 

aquifer. Consequently, little is known of the hydrologic properties or the chemical quality of water of the Lower Floridan 

aquifer within Polk County.

The Lower Floridan aquifer generally is present within 

the lower part of the Avon Park Formation, the Oldsmar 

Formation, and the upper part of the Cedar Keys Formation 

(fig. 11). In east-central Florida, the Lower Floridan aquifer 

is highly productive and is composed of alternating beds of 

limestone and fractured dolostone (O’Reilly and others, 2002). 

Permeability within this zone mostly is related to secondary 

porosity developed along bedding planes, joints, and fractures. 

In much of Polk County, the Lower Floridan is composed 

of alternating beds of limestone and dolostone containing 

intergranular evaporites and generally is not as productive. 

Figure 29. Altitude of the top of the middle confining unit (modified from Wolansky and others, 1979; Miller, 1986; 

O’Reilly and others, 2002; and Basso, 2003).

Ground-Water Resources  37

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE COUNTY

-800

-900

-900

-1,000

-900

-1,000

-1,100

-1,200

-1,100

-1,300

-1,200

-1,300

-1,000

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

-738

-749

-787

-821

-822

-886

-903

-906

-913

-954

-972

-991

-1,041

-1,055

-1,170

-1,005

-738

EXPLANATION

STRUCTURE CONTOUR -- Shows altitude

of the top of the middle confining unit.

Dashed where approximate. Datum is

NGVD29. Contour interval is 100 feet

WELL CONTROL POINT AND VALUE

-900
38  Hydrology of Polk County, Florida

Altitudes of the top of the Lower Floridan aquifer are 

estimated to range from 1,000 ft to more than 1,600 ft below 

NGVD 29 (Miller, 1986). At well 203 (ROMP 74X), located 

in Davenport, a permeable unit delineated as part of the Lower 

Floridan aquifer was encountered at 1,165 ft below NGVD 29 

(Gates, 2003). The permeable zone consists of hard, fractured 

dolostone without the presence of gypsum. At Polk City, a 

test well penetrated the Lower Floridan aquifer at a depth of 

1,648 ft below NGVD 29 (O’Reilly and others, 2002). In a test 

well completed in 2005 in Lake County near the four corner 

region of northeastern Polk County, CH2MHILL (2005) 

determined that the top of the Lower Floridan aquifer was at 

about 1,030 ft below NGVD 29. Thickness of the aquifer was 

estimated to range from about 1,100 to 1,800 ft across the 

study area (Miller, 1986).

In east-central Florida, the top of the Lower Floridan aquifer generally is marked on geophysical logs by an increase in 

formational resistivity due to the increased presence of dolostone (O’Reilly and others, 2002). A noticeable increase in flow 

to a well due to the presence of fractures and solution cavities 

also commonly marks the contact between the Lower Floridan 

aquifer and overlying unit (O’Reilly and others, 2002).

Few data are available to describe the hydraulic properties 

of the Lower Floridan aquifer in Polk County. In southwestern 

Orange County, where the transmissivity of the aquifer has 

been enhanced by secondary porosity features, transmissivity 

estimates exceeding 500,000 ft2/d were reported from several 

aquifer tests (Lichtler and others, 1968; Szell, 1993). In 

west-central Florida, the unit is of relatively low permeability 

because of the presence of intergranular gypsum.

Sub-Floridan Confining Unit

Underlying the Lower Floridan aquifer are lowpermeability dolostone and limestone containing abundant 

evaporite minerals that form the sub-Floridan confining unit. 

The top of this unit is defined as the uppermost stratigraphic 

occurrence of persistent evaporite deposits in the upper part of 

the Cedar Keys Formation (Miller, 1986). These beds of very 

low permeability serve as the hydraulic base of the Floridan 

aquifer system and range in altitude from about 2,200 ft below 

NGVD 29 in northern Polk County to about 3,400 ft below 

NGVD 29 in southwestern Polk County (O’Reilly and others, 

2002; Sepúlveda, 2002). Test drilling, however, indicates that, 

based on hydraulic properties, the sub-Floridan confining 

unit may be considerably shallower than mapped by Miller 

(1986). At a site in south-central Orange County, a gypsiferous 

dolostone was first encountered at 2,150 ft below NGVD 29 

and substantial amounts at 2,240 ft below NGVD 29 (McGurk 

and Sego, 1999). Packer tests completed in the test hole indicated the presence of low-permeability rocks below a depth of 

1,990 ft (McGurk and Sego, 1999). Another test well drilled 

in south-central Orange County found gypsiferous dolostone at about 2,160 ft below NGVD 29 (Boyle Engineering 

Corporation, 1995). Decreasing permeability, however, was 

reported in the dolostone and limestone below a depth of 

1,960 ft below NGVD 29.

Ground-Water Flow System

The recharge and discharge areas of Polk County and 

ground-water flow patterns in the Upper Floridan aquifer 

(based on potentiometric surface maps) are discussed herein.

Recharge and Discharge

Recharge areas of the Upper Floridan aquifer cover much 

of Polk County. These areas include well-drained and poorly 

drained soils, swamps, closed-basin lakes, and sinkholes. The 

Upper Floridan aquifer is recharged by the downward movement of water through the surficial aquifer system and intermediate confining unit or intermediate aquifer system. The 

rate of recharge varies with the vertical hydraulic conductivity, 

the thickness of the surficial aquifer system and underlying 

units, and the magnitude of the downward head gradient.

Estimated rates of recharge from the surficial aquifer 

system to the Upper Floridan aquifer range from 0 to greater 

than 10 in/yr in Polk County (Stewart, 1980; Ryder, 1985; 

Tibbals, 1990; Yobbi, 1996). Highest rates of recharge occur 

on the Lake Wales Ridge with somewhat lower rates along 

adjacent ridges. These karst ridge areas are characterized 

by deep water tables, an intermediate confining unit that 

is relatively thin or permeable, and a downward hydraulic 

gradient. These areas also include numerous closed basins 

where the intermediate confining unit has been breached 

by sinkholes and the infiltration rate of ground water to the 

underlying Upper Florida aquifer is high. Very low to moderate recharge rates occur in areas where the underlying confining unit is thicker or less permeable, such as in southwestern 

Polk County. Very low to moderate recharge rates also occur 

in areas where the confining unit may be thin or absent, but 

where the water table and the potentiometric surface of the 

Floridan aquifer are similar, such as in the Green Swamp area.

Areas of discharge from the Upper Floridan aquifer occur 

where the altitude of the potentiometric surface is normally 

above the water table in the surficial aquifer system. In some 

areas, the Upper Floridan aquifer potentiometric surface is 

above land surface. Areas of discharge occur primarily east of 

the Lake Wales Ridge and along parts of the Kissimmee River 

(fig. 30). Estimated discharge by diffuse upward leakage from 

the Upper Floridan to the surficial aquifer system ranges from 

about 0.5 to 6 in/yr (Tibbals, 1990).

Potentiometric Surface

The potentiometric surface maps used to evaluate 

ground-water flow patterns in the Upper Florida aquifer were 

constructed from water-level data from a network of wells 

distributed across Polk County. The potentiometric surface 

of the Upper Floridan aquifer represents the altitude to which 

water levels will rise in tightly cased wells. The surface is 

mapped by measuring the altitude of water levels in a network 

of wells and is represented on maps by contours that connect 

points of equal water-level altitudes. Potentiometric surface 
maps of the Upper Floridan aquifer in northern and central 

Florida are published semiannually by the USGS in cooperation with the SFWMD, SWFWMD, SJRWMD, and other 

local agencies. The configuration of the potentiometric surface 

of the Upper Floridan aquifer for September 2003 is shown 

in figure 30. The September 2003 potentiometric surface 

represents conditions near the end of the wet season, when 

withdrawals from the aquifer for agricultural irrigation and 

public supply are near minimum, and water levels generally 

are at their highest. Ground water in the Upper Floridan 

aquifer moves downgradient from potentiometric highs toward 

potentiometric lows, in directions perpendicular to the lines 

of equal head. The potentiometric surface ranges from about 

130 ft above NGVD 29 in northern Polk County to about 44 

ft above NGVD 29 in the extreme southeastern part of the 

county along the Kissimmee River.

During May 2004, which represented conditions when 

ground-water withdrawals are greatest and water levels are 

near seasonal lows, the potentiometric surface ranged from 

127 ft above NGVD 29 to about 30 ft above NGVD 29 

(fig. 31). Comparison of the September and May maps shows 

little change in the configuration of the surface from one 

seasonal extreme to another, even though the potentiometric 

surface is considerably lower during the dry season. The 

potentiometric surface was about 1.5 to 17 ft lower in May 

2004 as compared to September 2003. The decline in the 

potentiometric surface was greatest in the southwestern part 

of the county and least in the northern and extreme eastern 

part of the county. Comparison of the maps also shows that 

the potentiometric contours are shifted slightly to the west 

in September relative to May because of recharge from the 

summer rains and the associated reduction of pumping.

Kissim

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POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

91

91

65 93

73

99 94

92

82 89 70

84 59

82 71 60

80 81

83

96

96

85 81 48

46

71

90

44 80 89

84

87

78 79

46 75

88

111 117

111

105

128

128 104

128

130

129

122 100 100 124

116

101

119

102

101

100

105

105

100

80

77

90

126

104

EXPLANATION

104 WELL -- Number is altitude of water

level in feet above NGVD 29

POTENTIOMETRIC

CONTOUR -- Shows altitude at

which water level would have

stood in tightly cased wells.

Contour interval is 10 feet.

100

DISCHARGE AREA

80

70

90

100

110

120

130

80

70

60

60

50

100

90

60

Figure 30. Potentiometric surface of the Upper Floridan aquifer, September 2003 (from Kinnaman and Knowles, 2004a).

Ground-Water Resources  39
40 Hydrology of Polk County, Florida

The potentiometric surface of the Upper Floridan aquifer 

is constantly fluctuating, mainly in response to seasonal 

variations in rainfall and ground-water withdrawals. Seasonal 

and year-to-year fluctuations of water levels in two wells open 

to the Upper Floridan aquifer in Polk County are shown in 

figure 32. Hydrographs show that the water levels generally 

are at or near their minimums during May and then begin 

to rise rapidly through September or October in response 

to summer rains and the cessation of irrigation pumpage. 

The range of water-level fluctuations in the Upper Floridan 

aquifer varies to some extent with geographical location. 

Fluctuations are greatest where the aquifer is well confined 

and is heavily pumped for irrigation, or near areas of major 

industrial pumping, such as in southwestern Polk County 

(well 4). In areas where withdrawals from the Upper Floridan 

aquifer are less and the overlying confining beds are thin or 

leaky, such as in the Green Swamp area, seasonal variations 

in water levels generally range from about 1 to 5 ft (well 263). 

Variations in water levels generally are similar to those in the 

surficial aquifer system, but usually are of greater magnitude. 

Fluctuations that more closely mimic those in the water table 

generally indicate a better hydraulic connection between the 

surficial and Upper Floridan aquifers.

Prior to large withdrawals from the Upper Floridan 

aquifer, the level of the potentiometric surface was mainly 

controlled by the hydraulic characteristics of the aquifer and 

the overlying confining units, the topography and altitude of 

the recharge areas, and by natural recharge and discharge. 

Predevelopment hydrologic conditions are considered to be 

conditions that existed prior to man’s influence on the system. 

Kissim

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POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

58 88

102

115

88

70

93 94

84 92

80 67

76

92

69 54

58

92

97

64 97

66 75

90 84

79

65

44 60

75

40

64 74

76

74

61 63

42 30 69

102

126

125 102

125

127 127

118 119

111

112

100

108

109

87

60

124 121

76

72

89

93

97

89

EXPLANATION

POTENTIOMETRIC

CONTOUR -- Shows altitude at

which water level would have stood

in tightly cased wells.

Contour interval is 10 feet.

100

104 WELL -- Number is altitude of water

level in feet above NGVD 29

120

100

110

100

100

90

90

90

80

80

70

70

60

60

50

40

50

Figure 31. Potentiometric surface of the Upper Floridan aquifer, May 2004 (from Kinnaman and Knowles, 2004b).
Johnston and others (1980) estimated the predevelopment 

potentiometric surface of the Upper Floridan aquifer in the 

southeastern United States. A map showing the average 

potentiometric surface of the Upper Floridan aquifer prior to 

development in Polk County is shown in figure 33. Altitude of 

the potentiometric surface ranged from more than 130 ft above 

NGVD 29 in the north-central part of the county to less than 

60 ft above NGVD 29 along the Kissimmee River.

Since predevelopment times, the increase in ground-water 

withdrawals in Polk and adjacent counties resulted in a decline 

of the potentiometric surface of the Upper Floridan aquifer 

across much of the county (fig. 34). The approximate decline 

in the potentiometric surface of the Upper Floridan aquifer 

was based on the difference between the estimated predevelopment potentiometric-surface map and water levels in wells 

measured in May and September, and averaged from 2000 to 

2004. Even though in many locations throughout Polk County 

water levels have risen or remained constant over the past 

20-40 years, water levels, for the most part, are still considerably lower than during predevelopment times. For example, 

in southwestern Polk County where substantial rises in water 

levels have been observed, present water levels range from 

about 15 ft to as much as 40 ft below predevelopment times. 

In the eastern and west-central parts of the county, water levels 

have declined from about 0 to 15 ft. In a few areas that were 

not impacted much by pumping, such as in northwestern Polk 

County and along the Kissimmee River, little or no change in 

the potentiometric surface has occurred.

Associated with the long-term decline in the potentiometric surface of the Upper Floridan aquifer has been the 

cessation of flow from Kissengen Spring and other minor 

springs in southern Polk County (fig. 35). Kissengen Spring, 

located along the Peace River in south-central Polk County 

(fig. 1), was the first known major spring to cease flowing in 

Florida due to ground-water withdrawals from wells (Rosenau 

and others, 1977). The two initial discharge measurements 

made of the spring in 1898 and 1917 were 31 cubic feet 

per second (ft3/s) and 21 ft3/s, respectively (Peek, 1951). 

A record high discharge measurement of 44 ft3/s was made 

in 1933. Discharge from the spring declined progressively 

from 1933 until it ceased flowing in February 1950. Sporadic 

spring discharges were measured in 1955, 1959, and 1960. 

A discharge of 0.3 ft3/s was measured in April 1960, and the 

spring has not flowed since that time.

Vertical ground-water head gradients along the Peace 

River have reversed as a result of the long-term reduction in 

ground-water levels. Areas of the upper Peace River basin 

exhibited artesian flow conditions prior to the regional 

102

104

106

108

110

112

114

116

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

-10

0

10

20

30

40

50

60

70

WATER LEVEL, IN FEET ABOVE OR BELOW NGVD 29

YEAR

EVA SITE

WELL NUMBER: 263

TOTAL DEPTH: 192 feet

ROMP 40 SITE

WELL NUMBER: 4

TOTAL DEPTH: 1,140 feet

Figure 32. Water levels in selected wells tapping the Upper Floridan aquifer (well locations shown in fig. 9).

Ground-Water Resources  41
42  Hydrology of Polk County, Florida

lowering of the Upper Florida aquifer potentiometric surface 

in the area (Stewart, 1966). At the headwaters of the Peace 

River, flowing wells were reported by Stewart (1966) in 1948 

near Saddle Creek. Stewart (1966) also reported ground-water 

discharge from limestone outcrops of the Hawthorn Group 

from a quarry in this same area. The most upstream parts of 

the Peace River in Polk County are presently a ground-water 

recharge area. During the dry season, ground-water levels 

in both the intermediate aquifer system and Upper Floridan 

aquifer are below the river stage from upstream of Bartow to 

downstream from Fort Meade (Lewelling and others, 1998). 

During the wetter periods, heads in the intermediate aquifer 

system can be higher than the river stage for short periods.

In the future, water levels in the Floridan aquifer system 

in southwestern Polk County may continue to rise because of 

the continuing decrease in water use by the phosphate industry 

as active mining moves farther south. The potential rise in 

water levels, however, may be offset by increases in water use 

for residential and possibly agricultural developments.

Long-Term Trends in Ground-Water Levels

As a result of an increasing population and strong 

agricultural industry, ground-water withdrawals for public 

supply and agricultural purposes in Polk County have 

increased considerably since 1965. In contrast, withdrawals 

for phosphate mining have declined almost 80 percent as 

the industry implemented water-conservation practices and 

as production decreased in the 1980s. Long-term changes in 

ground-water levels have resulted from this redistribution of 

pumping stresses.

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

EXPLANATION

POTENTIOMETRIC

CONTOUR -- Shows altitude at

which water level would have stood

in tightly cased wells. Datum is

NGVD 29. Contour interval is 10 feet

100

130

120

110

100

90

80

70

60

60

90

80

70

Figure 33. Predevelopment potentiometric surface of the Upper Floridan aquifer (from Johnston and others, 1980).
> 0 to 15 FEET

> 15 to 40 FEET

NO CHANGE

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

Figure 34. Change in the potentiometric surface of the Upper Floridan aquifer from predevelopment to average 

2000-2004 conditions.

Figure 35. Discharge at Kissengen Spring, 1898-1960.

Ground-Water Resources  43

KISSENGEN SPRING

02294758 (2750320814839)

0

10

20

30

40

50

1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 2005

DISCHARGE,

IN CUBIC FEET PER SECOND

December 21, 1898

(31 ft3/s) February 25, 1917

(21 ft3/s)

October 11, 1933

(44 ft3/s)

April 4, 1960

(0.3 ft3/s)

Last observed

discharge
44  Hydrology of Polk County, Florida

Long-term water level-data from observation wells 

tapping the surficial, intermediate, and Floridan aquifer 

systems were analyzed statistically for significant trends 

(table 1) using the nonparametric Kendall’s tau (Helsel and 

Hirsch, 1992). A 0.05 significance level was used as the 

criterion for statistical significance. The test is a ranked-base 

procedure that examines whether data values tend to increase 

or decrease with time. No assumption of normality is required 

and the test is resistant to the influence of extremes, but there 

can be no serial correlation for the resulting probability values 

to be correct (Helsel and Hirsch, 1992). Hydrologic data tend 

to be serially correlated on measurement scales of less than 

1 year, whereas annual data typically do not have a serial 

correlation problem. Therefore, trend analysis was conducted 

using annual sets of data. Locally weighted scatterplot 

(LOWESS) smoothing, a robust smoothing technique (Helsel 

and Hirsch, 1992), also provided information on significant 

trends in ground-water levels.

For the surficial aquifer system, the test was conducted 

at three monitoring wells with water-level data that began in 

the mid-1960s and three that began in the mid-1970s. Results 

of the Kendall’s tau trend analysis show that for the period 

of record analyzed, two of the six wells showed significant 

declines in water levels and two wells showed a significant rise 

in water levels (table 1, p-values less than 0.05). The remaining two wells had no significant trends (p-values greater than 

0.05). Although the Kendall’s tau showed significant trends 

for the entire period of record at some wells, these long-term 

trends may not be continuous and may vary somewhat over 

time. The use of LOWESS for trend analysis for the period 

of record shows these short-term rises and declines in water 

levels (fig. 36). For example, at well 189, which was one of 

the wells where the Kendall’s tau trend indicated a decline in 

water levels for the period of record (fig. 36), the LOWESS 

line indicates that the decline was not constant over the 

period of record. The water levels in the well increased from 

Table 1. Results of trend analysis for long-term observation wells and for rainfall stations.

[Locations of wells and rainfall stations shown in figure 9. SAS, surficial aquifer system; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer]

Well 

number

USGS site 

identification

number

Station name County Aquifer

Bottom 

of casing 

(feet)

Depth of 

well 

(feet)

Period of 

record 

analyzed

p-value Kendall’s 

tau

264 282245081492602 Eva SAS Lake SAS 18 23 1963-2004 0.0450 -0.2160

243 281532081345002 Loughman shallow Polk SAS 29 32 1964-2004 .3512 -.1024

145 275815081444201 Lake McLeod shallow Polk SAS 24 26 1965-2004 .0000 .5539

208 281008081441802 Lake Alfred SAS Polk SAS 6 9 1973-2003 .1261 .1957

189 280719081543301 Combee Road SAS near Lakeland Polk SAS 8 9 1974-2004 .0381 -.2645

17 274225081315201 USGS shallow well P-48 Polk SAS 59 62 1977-2004 .0108 .3439

39 274547081470901 Romp 45 Htrn Polk IAS 110 192 1976-2004 .0190 .3104

101 275314081514203 Romp 59 Upper Htrn Polk IAS 50 60 1977-2004 .0022 .4127

27 274440081314801 Coley UFA Polk UFA 208 319 1949-2004 .0000 -.5364

103 275326081585801 ROMP 60 UFA Polk UFA 237 710 1955-2004 .2553 -.1118

207 281008081441801 Lake Alfred 6” UFA PO0006 Polk UFA 102 425 1959-2004 .9396 .0087

242 281532081345001 Loughman UFA (POF-1) Polk UFA 85 247 1960-2004 .0001 -.4146

144 275802082044701 Fletcher Lett UFA Hillsborough UFA 100 530 1963-2004 .8369 -.0232

158 280229081325201 Lake Hatchinea Rd 8” UFA 

 (POF-4)

Polk UFA 146 453 1963-2004 .0829 -.1870

210 281037082071801 J.O. Alston 2” UFA Pasco UFA 47 55 1964-2003 .2172 -.1390

263 282245081492601 Eva UFA (L-0057) Lake UFA 100 192 1964-2004 .1888 -.1439

63 274846081262001 USGS Well at Lake Weohyakapka

 (POF-0008)

Polk IAS/

UFA

149 197 1969-2004 .1957 -.1524

150 275959081552501 Sanlon Ranch 24” UFA Polk UFA 293 1220 1970-2004 .0002 .4387

184 280531081431601 Lake Alfred 12” UFA Polk UFA 282 555 1971-2004 .0012 .3977

58 274815081130301 River Ranch UFA (POF-5) Polk UFA 185 300 1974-2004 .7597 .0409

Avon Park rainfall station Highlands 1931-2003 .5548 -.0476

Lakeland rainfall station Polk 1931-2003 .3104 .0814

Mountain Lake rainfall station Polk 1931-2003 .2776 -.0871

Winter Haven rainfall station Polk 1949-2003 .1274 .1421
Figure 36. Long-term water levels in observation wells tapping the surficial aquifer system and the Upper Floridan aquifer (well locations 

shown in fig. 9).

Ground-Water Resources  45

YEAR

80

82

84

86

88

90

92

100

90

80

70

60

114

112

110

108

104

106

118

122

126

130

134

139

125

127

129

131

133

135

137

110

60

70

80

90

100

WATER LEVEL, IN FEET ABOVE NGVD 29

30

50

70

90

40

60

80

1945 1955 1965 1975 1985 1995 2005

20

138

134

132

130

128

1945 1955 1965 1975 1985 1995 2005

136

WATER LEVEL, IN FEET ABOVE NGVD 29

LOWESS CURVE

LOWESS CURVE

LOWESS CURVE

LOWESS

CURVE

LOWESS

CURVE

LOWESS

CURVE

LOWESS CURVE

LOWESS

CURVE

J.O. ALSTON SITE

WELL

Upper Floridan aquifer

p = .2172

NUMBER: 210

TOTAL DEPTH: 55 feet

AQUIFER:

COLEY SITE

WELL NUMBER: 27

TOTAL DEPTH: 319 feet

AQUIFER: Upper Floridan aquifer

p = 5.51 x 10-9

EVA SITE

WELL

Upper Floridan aquifer

p = .1888

NUMBER: 263

TOTAL DEPTH: 192 feet

AQUIFER:

LAKE ALFRED SITE

WELL

Upper Floridan aquifer

p = .9396

NUMBER: 207

TOTAL DEPTH: 425 feet

AQUIFER:

SANLON RANCH SITE

WELL

Floridan aquifer

p = .0002

NUMBER: 150

TOTAL DEPTH: 1,220 feet

AQUIFER: Upper

LAKE ALFRED SITE

WELL

p = .1261

NUMBER: 208

TOTAL DEPTH: 9 feet

AQUIFER: Surficial aquifer system

ROMP 60 SITE

WELL

Floridan aquifer

p = .2553

NUMBER: 103

TOTAL DEPTH: 710 feet

AQUIFER: Upper

COMBEE ROAD SITE

WELL NUMBER: 189

TOTAL DEPTH: 9 feet

AQUIFER: Surficial aquifer system

p = .0381
46  Hydrology of Polk County, Florida

the beginning of the record until the early 1980s, and then 

declined to 2004. The LOWESS lines for some of the other 

surficial aquifer wells also indicate periods of declining or 

rising water levels. These oscillations probably are the result 

of the cyclic variations in rainfall over time.

Long-term water-level data from 14 observation wells 

tapping the intermediate aquifer system and the Upper 

Floridan aquifer also were statistically analyzed for trends 

(table 1). The period of record used for data analysis ranged 

from 31 to 56 years. Two of the intermediate aquifer monitoring wells analyzed had water levels that began in the 1970s. 

Three of the Upper Floridan aquifer monitoring wells had 

water-level data that began prior to 1960. Six of the wells had 

water-level data that began in the 1960s, and three monitoring 

wells had water-level data that began in the 1970s.

Eight wells (of 14) had no significant trends in waterlevel (p-values greater than 0.05). Two intermediate aquifer 

wells and two Upper Floridan aquifer wells showed significant 

increases in water levels in (p-values less than 0.05). Two 

Upper Floridan aquifer wells had significant declines in water 

levels (p-values less than 0.05).

As previously mentioned, the long-term trends identified 

in these wells may not be continuous throughout the period 

of record. For example, at well 103, there was no significant 

trend in water levels for the period of record; however, water 

levels clearly declined from the beginning of record until 

the early 1970s, and then began to rise (fig. 36). Water-level 

trends in southwestern Polk County, similar to those at 

well 103 (ROMP 60), illustrate that industrial pumpage has 

had a major impact on ground-water levels in the county. 

Water-level declines prior to the mid-1970s coincide with an 

increase in water use associated with phosphate mining in 

Polk and Hillsborough Counties that had been occurring for 

several decades. Mining in Polk County, for the most part, had 

been concentrated south of Lakeland and west of the Peace 

River. At the peak of phosphate production in the mid-1970s, 

ground-water pumpage for phosphate mining was estimated 

to be about 270 Mgal/d. The rise in water levels that began in 

the mid-1970s at some well locations (and several years later 

at others) coincides with a period when ground-water use 

associated with the phosphate industry declined. In addition 

to a decrease in ground-water pumpage, an increase in rainfall 

during part of the period at some of the rainfall stations (fig. 5) 

also may be responsible for some of the increase in water 

level.

Changes in the distribution of pumpage also could 

account for some of the variation in water-level trends. At well 

27 (located in southeastern Polk County), which had a significant water-level decline for the period of record, water levels 

declined until the early 1980s (fig. 36). Water levels then 

stabilized and rose slowly for the next 20 years. The waterlevel declines observed until the early 1980s were partially the 

result of water use associated with the phosphate industry as 

well as water use associated with agricultural irrigation along 

the Lake Wales Ridge. The water-level stabilization that began 

in this well in the 1980s is somewhat muted compared to 

other wells like well 103 (ROMP 60) in southern Polk County 

that rose more in response to the reduced mining water use. 

Possibly, the recovery in water levels was offset by an increase 

in agricultural water use as the citrus industry grew along the 

Lake Wales Ridge.

Head Relations

Water levels within the aquifer systems in Polk County 

vary with depth. Heads decrease with depth in recharge areas 

and increase with depth in discharge areas. The magnitude 

of head differences between the surficial, intermediate, and 

Floridan aquifer systems is directly related to the character 

of the confining units separating the aquifers. In areas not 

affected by pumpage, greater head differences between the 

aquifers generally are found where the confining unit is 

thicker and less permeable. In contrast, small head differences between hydrogeologic units indicate a better hydraulic 

connection.

Water-level data show a wide variation in the magnitude 

of head differences between the surficial, intermediate, and 

Floridan aquifer systems (fig. 37). Hydrographs at wells 

242 and 243 in northern Polk County show a small (0 to 

4 ft) head difference between wells in the surficial aquifer 

system and wells in the Upper Floridan aquifer. Water-level 

trends in the surficial aquifer system also generally mimic 

the trends observed in the Upper Floridan aquifer at this site. 

This similarity in trends indicates that leaky, fairly permeable 

or thin confining beds at this location allow relatively good 

connection between the aquifers. Small head differences and 

similar trends are also observed at Romp 45 between wells in 

Zone 3 of the intermediate aquifer system (well 39) and wells 

tapping the Upper Floridan aquifer (well 40). Hydrographs at 

wells 4 and 6 (ROMP 40) and wells 72 and 73 (ROMP 44) in 

southern Polk County show large head differences between 

the surficial and Upper Floridan aquifers. At ROMP 40, water 

levels are about 75 to 135 ft higher in the surficial aquifer 

system than in the underlying Upper Floridan aquifer. Little 

similarity in trends is observed between the water levels of 

the two aquifers, indicating that the confining beds between 

aquifers are thicker and relatively impermeable.

Head differences between the surficial aquifer system and 

the Upper Floridan aquifer in May 2004 varied considerably 

at 27 well pairs in Polk and adjacent counties (fig. 38). The 

magnitude of the downward head gradient between the two 

aquifers increases toward the southwest, mostly as the result 

of increased ground-water withdrawals for industrial use and 

tighter confinement between the two aquifers. In southwestern 

Polk County, water levels in the surficial aquifer system 

ranged from about 18 to 104 ft higher than water levels in the 

Upper Floridan. Ground-water withdrawals are high along the 

Lake Wales Ridge, but the head difference is smaller due to 

the fact that some drawdown is attenuated by vertical leakage 

from above. In northern Polk County, surficial aquifer system 

heads generally were about 0 to 8 ft higher than heads in 
30

40

50

60

70

80

90

100

110

120

-20

0

20

40

60

80

100

120

140

160

60

70

80

90

100

110

120

130

140

WATER LEVEL, IN FEET ABOVE OR BELOW NGVD 29

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

80

85

90

95

100

WELL NUMBER 73

SURFICIAL AQUIFER SYSTEM

ROMP 44 SITE

WELL NUMBER 72

UPPER FLORIDAN AQUIFER

WELL NUMBER 6

SURFICIAL AQUIFER SYSTEM

ROMP 40 SITE

WELL NUMBER 5

INTERMEDIATE AQUIFER SYSTEM

WELL NUMBER 4

UPPER FLORIDAN AQUIFER

WELL NUMBER 42

SURFICIAL AQUIFER SYSTEM

ROMP 45 SITE

WELL NUMBER 39

INTERMEDIATE AQUIFER SYSTEM

WELL NUMBER 40

UPPER FLORIDAN AQUIFER

WELL NUMBER 243

SURFICIAL AQUIFER SYSTEM

LOUGHMAN SITE

WELL NUMBER 242

UPPER FLORIDAN AQUIFER

Figure 37. Water levels in selected wells open to the surficial aquifer system, the intermediate aquifer system, and the Upper 

Floridan aquifer (well locations shown in fig. 9).

Ground-Water Resources  47
48  Hydrology of Polk County, Florida

the Upper Floridan aquifer. The head gradient is reversed in 

the extreme eastern part of the county, where the underlying 

Upper Floridan aquifer has a higher head than the surficial 

aquifer system. In this area, water levels in the Upper Floridan 

aquifer ranged from about 0 to 16 ft higher than water levels in 

the surficial aquifer system.

Little data are available on water-level variations with 

depth in the Floridan aquifer system in Polk County. To investigate the potential of obtaining potable water supplies from 

the Lower Floridan aquifer, however, several test wells were 

drilled in Polk and adjacent Lake and Osceola Counties. The 

variations in water levels with depth during the construction of 

three test wells (drilled to depths ranging from 1,560 to 2,400 ft) 

are shown in figure 39.

During drilling of the Lake Louisa State Park well (well 

267), water levels measured in the drill stem decreased about 

32 ft over the interval from 435 to 2,366 ft below land surface 

(fig. 39). At ROMP 74X (well 203), water levels measured 

in the drill stem decreased about 41 ft over the interval from 

461 to 1,556 ft. During the drilling of the Polk City core 

hole (well 217), water levels decreased about 9 ft over the 

interval from 512 to 1,996 ft. Substantial declines in water 

levels occurred from 1,200 to 1,300 ft below land surface 

at Lake Louisa State Park and from 1,226 to 1,286 ft below 

land surface at Romp 74X. The head changes appear to mark 

the base of the middle confining unit (the top of the Lower 

Floridan aquifer) and indicate good hydraulic separation 

between the Upper and Lower Floridan aquifers.

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Lakeland

Polk City Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

2.0

3.3

1.6

3.3

5.9

3.9

8.3

6.1

0.4

0.6 1.4

41.1

2.63

-4.3

28.3

18.1

19.2

41.3

36.0

44.0

2.49

-7.6

-0.1

104.1

-13.2

-16E

5.9

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

EXPLANATION

WATER LEVEL DIFFERENCE --

Point is location of well cluster.

umber is measured water-level

difference (surficial aquifer

system minus UpperFloridan

aquifer, in feet). E denotes

estimated value.

N

Note: negative numbers indicate an

upward head gradient and positive

numbers indicate a downward head

gradient.

2.0

DISCHARGE AREA

Figure 38. Head differences between the surficial aquifer system and the Upper Floridan aquifer, May 2004 (well numbers 

shown in fig. 9).
2,400

2,200

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

ROMP 74X

Well number: 203

WATER LEVEL, IN FEET ABOVE(-) AND

BELOW(+) LAND SURFACE

-10 0 10 20 30 40 50

Land surface altitude = 85 ft

WELL DEPTH, IN FEET BELOW LAND SURFACE

0 5 10 15 20 25 30 35 2,400

2,200

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

WELL DEPTH, IN FEET BELOW LAND SURFACE

POLK CITY CORE HOLE

Well number: 217

ADJUSTED WATER LEVELS,

IN FEET BELOW LAND SURFACE

Land surface altitude = 137 ft

WATER LEVEL,

IN FEET BELOW LAND SURFACE

LAKE LOUISA STATE PARK L-0729

Well number: 267

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

2,400

2,200

0 10 20 30 40 50 60

WELL DEPTH, IN FEET BELOW LAND SURFACE

EXPLANATION

ANNULUS

DRILL STEM

EXPLANATION

PACKER TEST

DRILL STEM

EXPLANATION DRILL STEM

Top of Lower

Floridan aquifer

Top of sub-Floridan

confining unit

DRILLING TERMINATED: 1/27/00

Well backplugged to 1,410 feet

Top of middle

confining unit

Top of middle

semiconfining unit

Land surface altitude = 120 ft

DRILLING STARTED:

11/3/99 Top of Upper

Floridan aquifer

Top of Upper Floridan aquifer

Top of Lower

Floridan aquifer

Top of middle

confining unit

Top of middle

semiconfining unit

Top of Upper Floridan aquifer

Top of Lower

Floridan aquifer

Top of middle

confining unit

Top of middle

semiconfining unit

DRILLING STARTED:

12/16/2002

DRILLING TERMINATED:

11/18/1980

DRILL STEM

DRILLING TERMINATED:

6/4/2003

DRILLING STARTED: 12/3/1979

Water levels converted

to below land surface

using altitude of 137 ft.

Figure 39. Water levels during drilling of monitoring 

wells (modified from Navoy, 1986; O’Reilly and others, 

2002; and Gates, 2003). (Well numbers refer to fig. 9.)

Ground-Water Resources  49
50 Hydrology of Polk County, Florida

At the Polk City well, a slight rise in water levels seems 

to occur to a depth of 1,300 ft (fig. 39). According to Navoy 

(1986), the rise is probably due to an inaccurate adjustment 

made to head measurements in the deeper part of the aquifer, 

rather than to an actual increase in water levels with depth. 

During the drilling of the well which took about 11 months, 

prevailing dry conditions caused a regional lowering of the 

potentiometric surface. To determine the true head-depth relation, an adjustment was made by Navoy (1986) to filter out the 

effects of the regional potentiometric surface decline. Navoy 

(1986) concluded that the most reasonable interpretation of 

the data is that the water levels remained at a rather constant 

level as depth increased, until a marked decline of about 16 ft 

occurred at the 1,800- to 1,900-ft interval.

Water levels at two well sites (fig. 39, wells 203 and 267) 

were not adjusted for changes with time. Additionally, waterlevel data in all wells presented in figure 39 were not adjusted 

for density differences between freshwater and mineralized 

water in various zones within the wells.

Water Budget

A water budget evaluates the quantities of water that 

enter and leave an area during a given time period, and 

equates their net sum to the change in the quantity of water 

stored in the area during that period. A generalized steadystate water budget for Polk County was made by using 

measured or estimated values for rainfall, lateral subsurface 

outflow, runoff and surface-water discharge, spring discharge, 

and evapotranspiration. Assuming there is no change in storage, inputs are balanced by outputs. An average estimate of 

evapotranspiration was calculated as the residual of the water 

budget. A generalized water budget can be described by the 

following equation:

ET = P- Q0 - QR - QS, (1)

where

ET is evapotranspiration, in inches per year;

P is precipitation, in inches per year;

Q0 is net lateral subsurface outflow, in inches per year;

QR is runoff (sum of overland runoff and ground-water 

seepage to streams), in inches per year; and

QS is spring discharge, in inches per year.

A generalized water budget was computed for Polk 

County over a 10-year period from 1994 to 2003 (fig. 40). 

A water budget averaged over a 10-year period is more 

representative of long-term conditions than a 1-year water 

budget. Additionally, when long-term average annual values 

P PRECIPITATION

ET EVAPOTRANSPIRATION

Q

R SURFACE-WATER RUNOFF

SPRING DISCHARGE

Q O NET LATERAL SUBSURFACE OUTFLOW

All values are in inches per year.

Q

S

SUB-FLORIDAN CONFINING UNIT

INTERMEDIATE

CONFINING UNIT

SURFICIAL

AQUIFER SYSTEM

FLORIDAN AQUIFER SYSTEM

P = 54.7 ET = 41.6

QS = 0 QR = 11

QO = 2.1

INTERMEDIATE

AQUIFER SYSTEM OR

Figure 40. Water budget for Polk County, Florida, 1994-2003.
of the various water-budget items are used, it is more valid 

to assume that the change in storage is negligible and can be 

disregarded without significant error. It was also assumed that 

all ground water pumped out was returned to the system as 

wastewater or irrigation return flow and that no substantial 

amount of ground water was piped into or out of the county.

The major input to the system is precipitation, which 

averaged about 54.7 in/yr from 1994 to 2003 at five NOAA 

stations (Avon Park, Bartow, Lakeland, Mountain Lake, and 

Winter Haven). Ten-year rainfall averages varied across the 

area during this period, ranging from about 49.6 in/yr at 

Mountain Lake to nearly 57.4 in/yr at Winter Haven.

Net lateral subsurface outflow (Q0) from Polk County 

was determined by using a USGS modular ground-water flow 

model (Nicasio Sepúlveda, U.S. Geological Survey, written 

commun., 2005). Net lateral outflow was determined for the 

surficial aquifer system (0.03 in/yr), the intermediate aquifer 

system (0.02 in/yr), the Upper Floridan aquifer (1.35 in/yr), 

and the Lower Floridan aquifer (0.70 in/yr). Net lateral 

subsurface outflow from all aquifers was about 2.1 in/yr.

Water leaving the county as surface-water runoff (QR) 

averaged about 11 in/yr from 1994 to 2003, based on the 

analysis of streamflow records at nine USGS gaging sites 

in basins that lie entirely or partially within Polk County. 

These gaged surface-water sites include the: Kissimmee 

River at S-65; Peace River at Fort Meade; Peace River at 

Zolfo Springs; North Prong Alafia River near Keysville; 

South Prong Alafia River near Lithia; Hillsborough River 

near Crystal Springs; Withlacoochee River near Cumpressco; 

Green Swamp Run near Eva; and Blackwater Creek near 

Knights. Runoff at sites not located in the vicinity of the Polk 

County line was estimated using drainage area proration. 

Runoff was not prorated from the Withlachoochee River and 

Green Swamp Run, because the former site is located near the 

Polk County line and the drainage basin is not well defined 

for the latter site. It was assumed in the water budget that onehalf of the runoff from the Kissimmee River Basin was from 

Polk County and the other half from Osceola County.

Spring discharge (QS) was estimated to be 0 in/yr. Due 

to the lowering of the potentiometric surface of the Upper 

Floridan aquifer, Kissengen Spring (the largest spring in Polk 

County) ceased flowing in the early 1960s.

Evapotranspiration is the largest output component in the 

water budget and is the most difficult to measure. Few accurate estimates of evapotranspiration were available; therefore, 

a value of 41.6 in. was determined by solving equation 1 for 

evapotranspiration. This back-calculated value of evapotranspiration is a reasonable estimate for Polk County and falls 

within the range of evapotranspiration values determined for 

the area—27 in/yr reported for a well-drained, deep watertable site along the Lake Wales Ridge in southwestern Orange 

County (Sumner, 1996) and about 56.5 in/yr reported at Lake 

Starr in east-central Polk County (Swancar and others, 2000).

Ground-Water Quality

The chemical and physical characteristics of water in 

aquifers are affected by the initial chemical composition of 

water entering the aquifer, the mineralogy and solubility of 

rocks with which it comes in contact, and the residence time 

of water in contact with the aquifer matrix. Atmospheric 

precipitation also can contribute to mineralization of water. 

The nature and extent of interconnection of sinkholes, rivers, 

and lakes, as well as anthropogenic sources, can affect the 

chemical composition of ground water.

The chemical characteristics of water can determine its 

suitability for various uses. The Florida Department of State 

(1989) established primary regulations and secondary standards for drinking water distributed by public water-supply 

systems. The primary drinking-water regulations establish 

mandatory limits and apply to the physical and chemical 

characteristics of water that may affect the health of the 

consumer. The secondary drinking-water standards establish 

recommended limits on certain chemical constituents that 

pertain to the aesthetic qualities of drinking water—which are 

not enforceable and are intended as guidelines. Concentrations 

of nitrate greater than 10 milligrams per liter (mg/L) as 

nitrogen exceed the national and State primary drinking-water 

regulations (U.S. Environmental Protection Agency, 2000). 

Secondary drinking-water standards set maximum limits of 

500 mg/L for dissolved-solids concentration, 250 mg/L for 

chloride and sulfate concentrations, 1.4 mg/L for fluoride 

concentration, and 0.3 mg/L for iron concentration. The 

principal chemical constituents in ground water that affect 

potability are chloride, sulfate, nitrate, and the amount of 

dissolved ions in the water (specific conductance). Hardness, 

due primarily to calcium and magnesium ions, may also be 

important for public and domestic water use.

Water-chemistry data collected by the USGS and State 

agencies were compiled for this study (fig. 10 and app. 2). 

Water samples from 53 wells and 1 spring were collected 

and analyzed by the USGS for major chemical constituents 

in 2002-2003. Samples were collected from 9 wells and 

1 spring tapping the surficial aquifer system, 5 wells tapping 

the intermediate aquifer system, and 39 wells tapping the 

Upper Floridan aquifer. Additionally, water-quality data 

(primarily field measurements and concentrations of major 

ions and nutrients) collected by the SFWMD, SWFWMD, and 

SJRWMD were compiled for the 1998-2003 period to further 

evaluate ground-water quality conditions. These data included 

37 samples from the surficial aquifer system, 10 samples from 

the intermediate aquifer system/intermediate confining unit, 

and 29 samples from the Upper Floridan aquifer.

Water samples collected by the USGS for this study 

were obtained from monitoring, public supply, and privately 

owned wells. Purging methods varied depending upon the type 

of well. For monitoring wells, water samples were collected 

using a centrifugal or submersible electric pump. These wells 

were sampled after at least three casing volumes of water 

Ground-Water Quality  51
52  Hydrology of Polk County, Florida

were pumped and temperature, specific conductance, and pH 

had stabilized. Public supply and privately owned wells have 

pumps installed that are used routinely. These wells were 

sampled after field parameters stabilized. A water sample for 

the spring was collected at the spring vent. Field measurements were made at this site by inserting the instrument probes 

directly into the spring orifice.

Specific conductance, temperature, pH, and dissolved 

oxygen were determined in the field. Water samples were 

collected for laboratory analysis of major ions, selected trace 

metals, alkalinity, total organic carbon, and nutrients. Nutrients 

included nitrite as nitrogen (nitrite), nitrite plus nitrate as nitrogen (nitrate), ammonia as nitrogen (ammonia), ammonia plus 

organic nitrogen as nitrogen, phosphorus, and orthophosphate 

as phosphorus (hereafter referred to as phosphate) (app. 2). 

Nitrogen (N) occurs as anions in water as nitrite (NO2

-

) or 

nitrate (NO3

-

). Both species are mobile and NO3

-

 is stable 

over a wide range of conditions (Hem, 1985). The NO2

-

 ion is 

unstable in aerated water and generally is present in negligible 

concentrations compared to NO3

-

. In this report, the combined 

concentration of nitrite plus nitrate reported by the laboratory 

is referred to as nitrate. Water samples were processed at the 

time of collection using standard USGS procedures (U.S. 

Geological Survey, 1998). Samples collected to determine 

major ion, trace-element, and nutrient analyses were filtered 

through a 0.45-micron pore-size disposable encapsulated filter. 

Samples for major cation and trace-element analyses were 

acidified with 2 milliliters of 7.7N nitric acid to adjust the 

sample pH to less than 2. All water samples were analyzed by 

USGS laboratories in Ocala, Florida, and Denver, Colorado.

Surficial Aquifer System

Major factors that control the quality of water in the 

surficial aquifer system are: (1) the quality and quantity of 

rainfall that infiltrates the aquifer system, and (2) the aquifer 

system properties, such as permeability and sediment type 

(Schiner, 1993). The concentrations of inorganic constituents 

in water from the surficial aquifer are related to the quality of 

the recharge water. Recharge water that moves through the soil 

zone or sediments may be chemically altered through mineral 

dissolution, mineral precipitation, cation or anion exchange, 

oxidation-reduction reactions, and sorption of organic molecules (Crandall and Berndt, 1996).

The concentrations of most chemical constituents in 

ground water from the surficial aquifer are somewhat variable 

(app. 2). The surficial aquifer system is primarily composed of 

insoluble quartz sand, which generally results in ground water 

with low mineral content and hardness. Water type is variable 

from location to location, but generally is a mixed water type, 

meaning that no one or two cations or anions were dominant 

in the ground water (fig. 41).

SULFATE PLUS CHLORIDE

PERCENT OF MILLIEQUIVALENTS PER LITER

MAGNESIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

CALCIUM PLUS MAGNESIUM

SULFATE

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

CALCIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

80

60

40

20

0

10

100

0

80

60

40

20

0

0

20

40

60

80

100

20

40

60

80

100

0

CARBONATE PLUS BICARBONATE

80

60

40

20

0

100 0

20

40

60

80

100

100

80

60

40

20

0

20

40

60

80

100

100

100

80

60

40

20

0

SODIUM PLUS POTASSIUM

0

20

40

60

80

100

Figure 41. Trilinear diagram for 

water from wells tapping the 

surficial aquifer system.
The areal variability of specific conductance, chloride, 

sulfate, and nitrate in water from the surficial aquifer system 

is shown in figures 42-45. Although 47 surficial aquifer wells 

were sampled from 1998 to 2003, the distribution is somewhat 

skewed because nearly two dozen wells were sampled along 

the Lake Wales Ridge. Many of the surficial aquifer wells 

incorporated into the water-quality network were drilled for 

a pesticide and nutrient monitoring network along the Lake 

Wales Ridge (Choquette and Sepúlveda, 2000).

Specific conductance, the ability of water to conduct 

an electrical current, is related to the presence of charged 

ionic species in water, thus providing an indication of the 

ion concentration of water. In the sampled wells, specific 

conductance ranged from 32 to 572 microsiemens per 

centimeter (μS/cm) (fig. 42 and app. 2). Specific conductance 

in the surficial aquifer system is variable over the county. 

Water having specific conductance of less than 200 μS/cm 

generally occurred in parts of northeastern and southwestern 

Polk County. Values ranging from 200 to 350 μS/cm occurred 

in a wide diagonal band beginning in the northwestern part 

of the county and extending to the southeastern part. Specific 

conductance values exceeding 350 μS/cm generally occurred 

along the Lake Wales Ridge area in the southern part of the 

county and along the Kissimmee River in the extreme southeastern part of the county.

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Lakeland

Polk City Davenport

Lake Wales Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

90

32

41

95

52

54 77

243

515

102

117

221

278

287

114 290

489 202 341

412

269 301

432

107

400

110 367

213

398

272 107 193

374 126

430 453

224 362

315 523 500

347 568

572

496 210

330

EXPLANATION

< 200 200 - 350 > 350

400 WELL -- Number indicates

specific conductance

SPECIFIC CONDUCTANCE IN

MICROSIEMENS PER CENTIMETER AT

25 DEGREES CELSIUS

SPRING -- Number indicates

specific conductance

278

Figure 42. Generalized distribution of specific conductance in water from the surficial aquifer system.

Ground-Water Quality  53
54  Hydrology of Polk County, Florida

Chloride concentrations in water from the surficial 

aquifer system ranged from 2.0 to 45 mg/L (fig. 43 and 

app. 2). Over most of the county, concentrations were less than 

25 mg/L. Lowest concentrations (less than 10 mg/L) were in 

the southwestern part, and in parts of northern and southeastern Polk County. Highest chloride concentrations (exceeding 

25 mg/L) occurred primarily along the areas that generally 

coincide with the southern part of the Lake Wales Ridge. 

Chloride is a major constituent of dissolved solids in ground 

water in coastal Florida. Chloride concentration often is used 

as an indicator of the extent of saltwater intrusion or amount 

of remnant seawater in an aquifer. In Polk County, the source 

of chloride in ground water from the surficial aquifer system 

is likely from agricultural activities, septic tank effluent, and 

small amounts contributed by rainfall.

Sulfate concentrations in water sampled from the 

surficial aquifer system ranged from 0.25 to 99 mg/L (fig. 44 

and app. 2). Sulfate concentrations were generally less than 

10 mg/L throughout much of the eastern and some of the 

northwestern and southwestern parts of Polk County. Sulfate 

concentrations ranging from 10 to 30 mg/L occurred in much 

of west-central Polk County. Sulfate concentrations greater 

than 30 mg/L were mostly along the Lake Wales Ridge. 

In Polk County, sulfate in the surficial aquifer system is likely 

derived from inorganic sulfates found in fertilizers or from 

organic sulfides that undergo oxidation in the soil or in organic 

waste treatment (Hem, 1985).

Figure 43. Generalized distribution of chloride concentrations in water from the surficial aquifer system.

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Lakeland

Polk City

Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

15

21

33

10 16

24 13

12

22

26 15

11 26

20 18

33

27 14

15

29 30

23 25 31 14 28

45

25

34 13

8.6

8.1

8.3

4.2 3.6

7.1

3.5

7.3

2.7 3.9

5.7 6.4

4.3

2.0 8.4

2.3

EXPLANATION

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 10 10 - 25 >

_ 25

22 WELL -- Number indicates

chloride concentration

SPRING -- Number indicates

chloride concentration

33
Nitrate concentrations in water from the surficial aquifer 

system ranged from less than 0.004 to 26 mg/L (fig. 45 and 

app. 2). Lowest concentrations were generally east and west of 

the Lake Wales Ridge. Highest concentration generally were 

along the Lake Wales Ridge. Fourteen wells along the Lake 

Wales Ridge had nitrate concentrations of 10 mg/L or greater. 

Additionally, a small spring discharging from a hill in northwestern Polk County had a nitrate concentration of 17 mg/L.

Nitrate concentrations are an important limiting factor 

for domestic water use. Excessive concentrations of nitrate 

in drinking water may cause methemoglobinemia in small 

children (Hem, 1985). The presence of elevated nitrate levels 

in surficial aquifer water could be an indication of contamination from fertilizers, animal waste associated with livestock 

management, and/or septic tank leachate. Along the Lake 

Wales Ridge, citrus groves are ubiquitous and fertilization is 

common practice. Tihansky and Sacks (1997) determined that 

water samples collected from wells in citrus land-use areas in 

Polk and Highlands Counties had the highest nitrate concentrations, ranging from 4.9 to 57 mg/L. Fertilizers also can 

contain additional chloride and sulfate, which could account 

for the increases in chloride and sulfate concentrations found 

Lakeland

Polk City Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

12

61

31

15

13 49

18

21 74

33

47 40

18

64

50

23 42

47 58

23

48 12

19

55 54

43

53 77 99 15

64

86

28

4.1

1.9

1.4

5.8

7.5

1.1

1.9

3.4

1.9

0.51

0.40

0.73

0.25

EXPLANATION

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 10 10 - 30 > 30

40 WELL -- Number indicates

sulfate concentration

SPRING -- Number indicates

sulfate concentration

0.40

Figure 44. Generalized distribution of sulfate concentrations in water from the surficial aquifer system.

Ground-Water Quality  55
56  Hydrology of Polk County, Florida

along the Lake Wales Ridge, as well the increases in specific 

conductance. Nitrates are readily transported in water and are 

stable over a considerable range of conditions (Hem, 1985). 

In east-central Florida, concentrations of nitrates in ground 

water underlying pristine areas were generally low, indicating 

that natural sources of nitrate do not contribute substantially to 

concentrations in ground water (Adamski and German, 2004). 

Water samples collected from the surficial aquifer system 

beneath undeveloped land in Polk and Highlands Counties 

also had low nitrate concentrations of less than 0.002 mg/L 

(Tihansky and Sacks, 1997).

Concentrations of iron in water from the surficial aquifer 

system ranged from less than 2.0 to 11,300 micrograms per 

liter (μg/L) (app. 2). Although most water samples yielded 

concentrations below 300 μg/L (the secondary drinking-water 

standard), concentrations greater than 300 μg/L were found 

in some places throughout the county. Iron in ground water is 

derived from the dissolution of rocks and soils in the aquifer. 

Concentrations exceeding 300 μg/L may stain laundry and 

plumbing fixtures. Large quantities of iron cause an unpleasant 

taste and favor growth of iron bacteria. Repeated use of such 

water for lawn irrigation can cause staining of sidewalks and 

buildings.

Lakeland

Polk City Davenport

Lake Wales Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

17

13

22 10 14

26

16

20

23

18

16

22 19

16

24

26

4.6

1.8

3.4

6.3

2.8 5.7

6.2

9.4

<0.02

<0.02

<0.02

0.06

<0.02

0.22 0.03

0.32

0.38

<0.02

0.48

0.007

0.006

0.006

0.076

0.008

0.014 0.006

0.041

<0.004

EXPLANATION

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 1.0 1.0 - 10 > 10

16 WELL -- Number indicates

nitrate concentration

SPRING -- Number indicates

nitrate concentration

17

Figure 45. Generalized distribution of nitrate concentrations in water from the surficial aquifer system.
Intermediate Aquifer System

Concentrations of major ions and nutrients in ground 

water of the intermediate aquifer system are somewhat variable because of the variability in the lithology of the sediments 

composing the intermediate aquifer system, and mixtures with 

water from the underlying Upper Floridan aquifer and overlying surficial aquifer system. Differences in composition result 

from the abundance of quartz sand, limestone, dolostone, clay, 

and phosphorite.

Water samples were collected from water-bearing zones 

from 15 wells tapping the intermediate aquifer system in Polk 

and adjacent counties. Seven wells tapped Zone 2 and one well 

tapped Zone 3. The water-bearing zones for seven wells were 

not determined because geologic or hydrologic information 

was not available for those sites.

The results of chemical analyses of water from the 

intermediate aquifer system in Polk and adjacent counties 

are given in appendix 2. In general, water quality of the 

intermediate aquifer system in Polk County is within the 

Florida Department of Environmental Protection primary and 

secondary drinking-water standards. Water type, as identified by a trilinear diagram, is of a calcium bicarbonate type 

(fig. 46). Specific conductance, chloride, sulfate, and nitrate 

concentrations of water from the intermediate aquifer system 

are shown in figure 47. Specific conductance ranged from 

257 to 601 μS/cm. Chloride concentrations in water ranged 

from 4.1 to 51 mg/L, and sulfate concentrations ranged from 

less than 0.2 to 17 mg/L. Nitrate concentrations ranged from 

less than 0.02 to 9.7 mg/L.

SULFATE PLUS CHLORIDE

PERCENT OF MILLIEQUIVALENTS PER LITER

MAGNESIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

CALCIUM PLUS MAGNESIUM

SULFATE

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

CALCIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

80

60

40

20

0

10

100

0

80

60

40

20

0

0

20

40

60

80

100

20

40

60

80

100

0

CARBONATE PLUS BICARBONATE

80

60

40

20

0

100 0

20

40

60

80

100

100

80

60

40

20

0

20

40

60

80

100

100

100

80

60

40

20

0

SODIUM PLUS POTASSIUM

0

20

40

60

80

100

Figure 46. Trilinear diagram for water from wells tapping the intermediate aquifer system.

Ground-Water Quality  57
58  Hydrology of Polk County, Florida

Floridan Aquifer System

The Upper Floridan aquifer is the major source of potable 

water to Polk County residents. The aquifer is composed of 

limestone and dolostone, which generally results in ground 

water that typically is hard. The quality of water in the Upper 

Floridan aquifer in Polk County generally meets Florida 

Department of Environmental Protection primary and secondary drinking-water standards. Water type, as identified by a 

trilinear diagram, is a calcium bicarbonate type (fig. 48).

Maps of specific conductance, chloride, sulfate, hardness, 

and nitrate in water from the Upper Floridan aquifer were 

constructed to delineate areas of different water quality (figs. 

49-53). Because all water samples were collected at the wellhead, they represent a composite from the various producing 

zones penetrated by the open borehole. Major constituent 

concentrations in water from the Floridan aquifer system vary 

areally and with depth.

The extent of mineralization of water in the Upper 

Floridan aquifer is indicated by specific conductance. The 

areal distribution of specific conductance values from the 

Upper Floridan aquifer is shown in figure 49. Specific 

conductance ranged from 104 to 577 μS/cm. The lowest 

specific conductance (less than 250 μS/cm) generally occurred 

in eastern Polk County. In much of the western two-thirds of 

the county, specific conductance ranged from about 250 to 

Lakeland

Davenport

Lake

Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort

Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

6.1

310

6.9

<0.02

9.6

434

0.62

NA

10

418

6.7

NA

4.4

347

<0.20

<0.02

14

506

5.1

NA

13

585

<0.20

<0.02

10

401

8.6

NA

36

495

4.8

<0.02

51

601

1.2

NA 17

327

9.9

0.04

9.8

257

1.7

0.01

7.3

311

0.68

0.06

4.1

285

2.5

NA

14

443

17

<0.02

15

354

1.1

9.7

Specific

conductance

Chloride

Sulfate

NO3

EXPLANATION

CHEMICAL ANALYSES

Chloride, sulfate, and nitrate

concentrations in milligrams per liter.

Specific conductance in

microsiemens per centimeter at

25 degrees celisius.

“NA” denotes no data

WELL (ZONE 2)

WELL (ZONE 3)

WELL (ZONE UNKNOWN)

Figure 47. Generalized distribution of selected constituents in water from the intermediate aquifer system.
500 μS/cm. Highest specific conductance values were in the 

Green Swamp area of northwestern Polk County and in parts 

of the discharge areas near the Kissimmee River.

Another indicator of mineralization is total dissolvedsolids concentration. The U.S. Environmental Protection 

Agency (2000) established a secondary drinking water regulation of 500 mg/L for dissolved-solids concentrations. Because 

water from many of the wells sampled in the past was not 

analyzed for dissolved-solids concentration, these values in 

ground water from the Upper Floridan aquifer were estimated 

from values of specific conductance. For the range of specific 

conductance values found in Polk County, multiplying specific 

conductance by 0.55 to 0.65 gives a reasonable approximation 

of the dissolved-solids concentration. Thus, specific conductance values shown in figure 49 (as well as existing dissolvedsolids concentrations) indicate that water in the entire county 

is below the 500-mg/L recommended limit for dissolved solids 

(U.S. Environmental Protection Agency, 2000).

The distribution of chloride concentrations in the Upper 

Floridan aquifer is shown in figure 50. Concentrations are 

below the 250-mg/L recommended limit for drinking water 

throughout the entire county. Chloride concentrations in water 

from the Upper Floridan aquifer ranged from 4.2 to 61 mg/L 

(app. 2). The lowest concentrations, generally less than 

10 mg/L, occurred in much of eastern and west-central Polk 

County. Chloride concentrations exceeding 25 mg/L occur 

at only three sites—one in the southwestern and two in the 

southeastern parts of the county.

The somewhat higher chloride concentrations (greater 

than 50 mg/L) that occur in the Upper Floridan aquifer along 

the Kissimmee River in the extreme southeastern part of the 

county are probably a mixture of freshwater and relict seawater that entered the aquifer system during a higher stand of sea 

level in the geologic past. The mineralized water, which has 

not been completely flushed from the Upper Floridan aquifer, 

extends east into southern Osceola County (Schiner, 1993).

SULFATE PLUS CHLORIDE

PERCENT OF MILLIEQUIVALENTS PER LITER

MAGNESIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

CALCIUM PLUS MAGNESIUM

SULFATE

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

CALCIUM

PERCENT OF MILLIEQUIVALENTS PER LITER

80

60

40

20

0

10

100

0

80

60

40

20

0

0

20

40

60

80

100

20

40

60

80

100

0

CARBONATE PLUS BICARBONATE

80

60

40

20

0

100 0

20

40

60

80

100

100

80

60

40

20

0

20

40

60

80

100

100

100

80

60

40

20

0

SODIUM PLUS POTASSIUM

0

20

40

60

80

100

Figure 48. Trilinear diagram for water from wells tapping the Upper Floridan aquifer.

Ground-Water Quality  59
60 Hydrology of Polk County, Florida

The distribution of sulfate concentrations in the Upper 

Floridan aquifer is shown in figure 51. Sulfate concentrations 

ranged from less than 0.20 to 44 mg/L. Sulfate concentrations 

of less than 10 mg/L occurred in nearly all of the county. 

Sulfate concentrations exceeding 30 mg/L were primarily in a 

small area in southwestern and southeastern Polk County.

Hardness concentrations in water sampled from the 

Upper Floridan aquifer ranged from 70 to 290 mg/L (fig. 52). 

Concentrations of less than 120 mg/L occurred primarily in eastern Polk County. Concentrations ranging from 120 to 180 mg/L 

were in much of the western two-thirds of the county. Highest 

concentrations (greater than 180 mg/L) were in the northwestern 

part and in a small area in south-central Polk County.

Hardness is principally due to calcium and magnesium 

ions, and can be an important water-quality criterion for public 

supply and domestic water use. Hard water may have detrimental effects, such as causing excessive soap consumption 

and the formation of encrustations or boiler scale. Hardness 

is expressed as milligrams per liter of calcium carbonate 

(CaCO3). A classification by Hem (1985) considers water 

soft if its hardness concentration lies between 0 and 60 mg/L, 

moderately hard between 61 and 120 mg/L, hard between 

121 and 180 mg/L, and very hard for concentrations greater 

than 180 mg/L of CaCO3. Hardness of water from the Upper 

Floridan aquifer in Polk County, therefore, ranges from 

moderately hard to very hard.

Lakeland

Polk City

Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

306

605

810 361 498

566 279

309

244 528 432 502

318

177 299

258

198 253 310 384 239

514 366

274

264

430

267

185

304

177

306 240

367

363

178

163 257

379

572 321

413

400

365 298 332

104 160 335

448 199 302

572

210 174 350

335

368

418

376 264

351

384 376

577

489 356 154

179

EXPLANATION

< 250 250 - 500 > 500

SPECIFIC CONDUCTANCE IN

MICROSIEMENS PER CENTIMETER AT

25 DEGREES CELSIUS

240 WELL -- Number indicates

specific conductance

Figure 49. Generalized distribution of specific conductance in water from the Upper Floridan aquifer.
Nitrate concentrations in water from the Upper Floridan 

aquifer range from less than 0.02 to 7.8 mg/L (fig. 53). Most 

of the water samples collected throughout Polk County had 

nitrate concentrations less than 0.02 mg/L, and only at three 

locations did concentrations exceed 1.0 mg/L. Nitrate may 

enter the Upper Floridan aquifer through breaches in the 

intermediate confining unit caused by sinkholes or where 

the intermediate confining unit is thin or absent. Where 

such features do not exist, nitrate concentrations typically 

decrease with depth below land surface due to denitrification, 

a process in which nitrate is reduced into gaseous nitrogen. 

In general, denitrification occurs when oxygen is depleted, 

and bacteria turn to nitrate in order to respire organic matter. 

Four conditions must be present for denitrification to occur: 

(1) nitrate must be present, (2) anaerobic conditions must 

be present in the aquifer, (3) a sufficient source of reduced 

organic carbon must be present, and (4) the bacteria capable 

of reducing nitrate must be present. Some evidence supporting the occurrence of denitrification is seen by comparing 

nitrate concentration in water of the surficial aquifer system 

to that in the Upper Floridan aquifer. At four locations where 

a comparison could be made (wells 31 and 34, 40 and 42, 

93 and 94, 234 and 235), nitrate concentrations observed in 

Upper Floridan aquifer waters were substantially lower than 

in the surficial aquifer system. For example, nitrate concentrations were 9.4 mg/L at well 34 (surficial aquifer system) and 

Lakeland

Polk City Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

16

61

22

14

15 11

11

18

15 16

10

10

12

14

19

10

10

18 15

19 12

11

58 16

17

11 13

11

13

12

61

51 11

7.1

7.3

6.3

7.2 4.2

8.8

8.4

6.0 5.5

7.0 8.0

5.6

7.7

6.9

4.8

7.2 7.1

7.1

5.7

4.9 9.3 5.7

7.9

4.7 9.2 5.4

7.2

5.8

5.7 7.8

7.8

4.5

7.5

6.8

EXPLANATION

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 10 10 - 25 > 25

16 WELL -- Number indicates

chloride concentration

Figure 50. Generalized distribution of chloride concentrations in water from the Upper Floridan aquifer.

Ground-Water Quality  61
62  Hydrology of Polk County, Florida

0.01 mg/L at well 31 (Upper Floridan aquifer). Lower nitrate 

concentrations in the Upper Floridan aquifer compared to the 

surficial aquifer system, however, do not necessarily indicate 

that denitrification has occurred. Lower nitrate concentrations in the Upper Floridan aquifer may have resulted from 

dilution of high nitrate water with low nitrate water present 

in the Upper Floridan aquifer, or high concentrations found 

in the surficial aquifer water may not have reached the Upper 

Floridan aquifer.

Vertical Distribution of Chloride and Sulfate 

Concentrations

Little data are available on the quality of water underlying the Upper Floridan aquifer in Polk County. Several 

monitoring wells have been drilled into the Lower Floridan 

aquifer in northern Polk and adjacent counties to acquire information about variations in water quality within the Floridan 

aquifer system. Chloride and sulfate concentrations in water 

samples collected during the drilling of three monitoring wells 

are shown in figure 54. Water samples were collected through 

the drill stem as the wells were drilled. Differences in trends 

in chloride and sulfate profiles are indicators of differences 

Lakeland

Polk City

Davenport

Lake Wales Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

12

11

21

19 23

19

21

33

26

21

42

12

36

44

13

18

43

40

15

41 41

5.0

2.5

8.0 3.3 1.9 1.0

1.2 7.8

6.0

4.6

3.1

4.3

1.4

5.6

4.1 1.3

9.7

6.3

2.2 4.3

1.7

3.4

6.0

6.5

< 0.20

< 0.20 < 0.20

0.20

< 0.20

0.25

< 0.40

0.20

3.2

0.40

< 0.20

0.20

0.20

0.28

< 0.20 0.64

< 0.20 0.19

0.31

< 0.20

< 0.20 < 0.20

EXPLANATION

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 10 10 - 30 > 30

21 WELL -- Number indicates

sulfate concentration

Figure 51. Generalized distribution of sulfate concentrations in water from the Upper Floridan aquifer.
in mixing of recharge water, relict seawater, and sulfate-rich 

water. In general, chloride and sulfate concentrations increased 

with depth, and water in the Lower Floridan aquifer was more 

mineralized than in the Upper Floridan aquifer.

The data shown in figure 54 assume that these water 

samples originate from the formation at or near the drill bit. 

Under certain conditions, when using the reverse air-rotary 

method, a change in water quality with depth may not be 

detected, or may be detected at a somewhat greater depth 

where the change in water quality occurs. This condition 

results if the permeability of the rock being drilled is low so 

that little of the return flow originates from the formation at 

or near the drill bit. Rather, most of the flow comes from a 

permeable zone higher in the hole.

The limited water-quality data show that, at least in 

northern Polk County, ground water having chloride concentrations less than 25 mg/L extends to considerable depths 

in the Floridan aquifer system. At ROMP 74X (well 203), 

chloride concentration was less than 25 mg/L to a depth of 

1,486 ft below land surface. At the Polk City test well (well 

217), chloride concentration was less than 11 mg/L to a depth 

of about 1,895 ft. At the St. Cloud well (located in northwestern Osceola County), chloride concentration remained 

below 25 mg/L from about 500 ft to a depth of 1,180 ft. 

At the interval between 1,180 to 1,220 ft, chloride concentration increased sharply from 25 to 240 mg/L. The increase 

in chloride concentration occurred near the contact between 

the middle confining unit and the Lower Floridan aquifer. 

Lakeland

Polk City

Davenport

Bartow Lake Wales

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

93

85

76 81

74

84

82

70

320 150

380 170

150

280

150

100 120 150 190

250 120 160

110

150

110

180

290

190

130 150

230

160 220

140

170 170

127

230

170

EXPLANATION

HARDNESS CONCENTRATION,

IN MILLIGRAMS PER LITER

< 120 120 - 180 > 180

160 WELL -- Number indicates

hardness concentration

Figure 52. Generalized distribution of hardness concentrations in water from the Upper Floridan aquifer.

Ground-Water Quality  63
64  Hydrology of Polk County, Florida

In the interval between 1,220 to 1,480 ft, chloride concentrations increased gradually with depth and ranged from 240 

to 660 mg/L. At the interval between 2,020 to 2,140 ft, 

chloride concentrations increased sharply again from 740 to 

3,600 mg/L (O’Reilly and others 2002).

Vertical changes in sulfate concentrations coincide well 

with the different hydrogeologic units. Sulfate concentrations in the Upper Floridan aquifer and much of the middle 

semiconfining unit at the three monitoring wells (fig. 54) 

were generally less than 100 mg/L, but increased substantially when the middle confining unit was penetrated. For 

example, during the drilling of ROMP 74X (well 203), an 

increase in sulfate concentration from 66 to 314 mg/L was 

observed between 1,051 and 1,071 ft below land surface 

(Gates, 2003). This increase marked the approximate contact 

where evaporites were first found, which is also considered to 

be the top of the middle confining unit. Sulfate concentrations 

remained constant throughout the middle confining unit but 

increased to 2,210 mg/L after the Lower Floridan aquifer was 

penetrated. During the drilling of the St. Cloud well, sulfate 

concentrations increased from 72 to 420 mg/L in the interval 

between 760 to 800 ft (O’Reilly and others, 2002). The top of 

the middle confining unit is estimated at 800 ft. Between 1,180 

and 1,220 ft below land surface, a moderate decrease in sulfate 

concentration was observed, along with a sharp increase in 

chloride concentration. This change in water quality corresponds with a change in head difference and apparently marks 

the base of the middle confining unit (the top of the Lower 

Lakeland

Polk City

Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY

PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

. . .

. . . . . . . . . . .

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

. .

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

2.0 7.8

2.6

< 0.02 < 0.02

< 0.02

< 0.02

< 0.02 < 0.02

< 0.02

< 0.02

< 0.02

< 0.02 < 0.02

0.54 0.41

< 0.02

< 0.02 < 0.02

< 0.02

< 0.02

< 0.02

< 0.02

0.29

< 0.02

< 0.02 0.01

< 0.02 < 0.02

< 0.02

< 0.02

< 0.02 < 0.02

0.01

< 0.02

< 0.02 < 0.02

0.008

< 0.020

0.008 < 0.02

0.007

0.004

0.005

0.007

< 0.004

< 0.004

< 0.004

< 0.004

EXPLANATION

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

< 0.25 0.25 - 1.0 >1.0 - 10

2.6 WELL -- Number indicates

nitrate concentration

Figure 53. Generalized distribution of nitrate concentrations in water from the Upper Floridan aquifer.
1 10 100 1,000 10,000

CONCENTRATION, IN MILLIGRAMS PER LITER

DEPTH, IN FEET BELOW LAND SURFACE

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

0

0.1 1 10 100 10,000

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

0

1 10 100 1,000 10,000

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

0

CONCENTRATION, IN MILLIGRAMS PER LITER

1,000

DEPTH, IN FEET BELOW LAND SURFACE

SULFATE

SULFATE

SULFATE

CHLORIDE

CHLORIDE

CHLORIDE

Top of Lower

Floridan aquifer

Top of middle

confining unit

Top of middle

semiconfining unit

Top of Upper Floridan aquifer

Top of Upper Floridan aquifer

Top of middle

semiconfining unit

Top of middle

confining unit

Top of Lower

Floridan aquifer

Top of Upper Floridan aquifer

Top of Lower

Floridan aquifer

Top of middle

confining unit

Top of middle

semiconfining unit

ROMP 74X

Well number: 203

ST. CLOUD WELL

Osceola County

Land surface altitude = 85 ft

POLK CITY CORE HOLE

Well number: 217

Land surface altitude = 137 ft

Figure 54. Chloride and sulfate concentrations 

in water samples obtained during drilling of 

monitoring wells (well number refers to fig. 9) 

(from Navoy, 1986; O’Reilly and others, 2002; 

and Gates, 2003, 2005).

Ground-Water Quality  65
66  Hydrology of Polk County, Florida

Floridan aquifer) (O’Reilly and others, 2002). At the Polk City 

test well, sulfate concentration increased from 1.4 mg/L at 

856 ft to about 560 mg/L at 1,065 ft below land surface.

A generalized map of the altitude of water with chloride 

concentrations greater than 250 mg/L is shown in figure 55. 

The map, taken from a larger map covering the 19 counties of 

the SJRWMD, was based primarily on water-quality samples 

collected from monitoring and test wells, and on surfaceand borehole-geophysical data (McGurk and others, 2003). 

The altitude of the top of the 250-mg/L isochlor is variable 

throughout Polk County, and the estimated position of the top 

of the 250-mg/L isochlor surface is less than 1,200 ft below 

NGVD 29 in the extreme southeastern part of the county. 

The thickest section where chloride concentrations are less 

than 250 mg/L is along the Lake Wales Ridge. In this area, 

the altitude of the top of the 250-mg/L isochlor is estimated to 

be about 2,400 ft below NGVD 29. In the western half of the 

county, the isochlor surface appears to rise gradually. Because 

few deep wells were drilled in western Polk County, little is 

known about the vertical distribution of chloride concentrations in the Floridan aquifer system. Thus, the estimated 

altitudes of the 250-mg/L isochlor were not drawn in parts of 

western Polk County. Figure 55, however, may not accurately 

portray the thickness of the freshwater zone in the county. 

The limited data indicate that beneath the top of the middle 

confining unit, dissolved-solids concentrations could be too 

high (due primarily to the high concentrations of sulfate) to 

consider the ground water in this part of the aquifer as fresh.

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

EXPLANATION

-2,200 ESTIMATED ALTITUDE OF WATER

HAVING CHLORIDE CONCENTRATION GREATER THAN 250

MILLIGRAMS PER LITER --

Contours interval 200 feet.

Datum is NGVD 29

-2,200

-2,000

-2,400

-1,800

-1,600

-1,400

-1,200

-1,600

-1,800

-2,000

-2,200

-2,400

-2,200

-2,000

-1,800-1,600

Figure 55. Estimated altitude of water in the Florida aquifer system having chloride concentrations greater than 

250 milligrams per liter (from McGurk and others, 2003).
Low-flow frequency statistics were determined by fitting 

time series of annual minimum streamflows over 1, 2, 3, 7, 10, 

30, 60, 90, 183, and 365 consecutive-day periods, commonly 

referred to as N-day annual minimum low-flow values, to a 

log Pearson Type III distribution (Riggs, 1972). In this study, 

N-day annual minimum flows were computed using a climatic 

year beginning on October 1 to ensure that all low-flow data 

related to a particular drought are contained in the same 

climatic year because the lowest streamflows in Polk County 

typically occur from April through June. Flood-frequency 

statistics were determined using the method described by the 

U.S. Interagency Advisory Committee on Water Data (1982).

The accuracy of low-flow and flood-frequency statistics 

is dependent upon the period of record used in the analysis, the 

variability and skewness of the data, and the recurrence interval. Standard error was calculated according to Kite (1977) 

for selected low-flow and flood-frequency statistics. This 

procedure assumes the error in the estimation of frequency 

statistics is a function of the uncertainty in estimating the 

mean, standard deviation, and skewness of the data.

Streamflow and Lake-Level 

Characteristics

Polk County contains the headwaters of five river 

basins—the Alafia, Hillsborough, Peace, Ocklawaha, and 

Withlacoochee Rivers. The county also contains numerous 

lakes and part of the Kissimmee River Basin (fig. 57). Surfacewater drainage from the county primarily occurs through the 

Peace and Kissimmee Rivers. Many changes to surface-water 

drainage patterns have occurred since the late 1800s. For 

flood-control purposes, the Kissimmee River downstream 

from Lake Kissimmee was channelized and many other lake 

outlets were modified (Barcelo and others, 1990), either by 

constructing structures to regulate lake levels or constructing 

canals to connect previously unconnected lakes.

Streamflow and lake level characteristics and trends were 

assessed in this study because the changes in the ground-water 

resources that have occurred in Polk County also have been 

expressed in the surface-water resources. Prior to human 

development, the Peace River was considered to be a gaining 

stream, which continuously received inflow from the groundwater system (Southwest Florida Water Management District, 

2002). The river now (2005) loses water to the ground-water 

system in parts of Polk County because the hydraulic gradient 

in the vicinity of the river has been reversed because of the 

lowering of the potentiometric surface of the Upper Floridan 

Purpose and Scope

This chapter describes the streams and lakes of Polk 

County, emphasizing trends in streamflow and lake levels. 

No information on water quality is presented. Substantial 

changes in the county that may affect streamflows and lake 

levels are described. Streamflow and lake locations summarized in this study are shown in figure 56 and appendix 3. 

Temporal trends in streamflows were updated using data 

through the year 2003. Streamflow duration curves and lowand flood-flow frequency statistics also were updated through 

2003. Seasonal fluctuations and temporal trends in lake levels 

are presented using data from 1960-2003. The factors that 

control lake levels in the county are summarized based upon 

the existing literature. Temporal trends in streamflow and 

flow-frequency statistics were determined using USGS data. 

Lake-level trends were determined using data collected by the 

SFWMD, SWFWMD, and USGS.

Methods

Several statistical methods were used in this study. 

Temporal trends in streamflow and lake levels were determined 

using Kendall’s tau (Helsel and Hirsch, 1992). Strong linear 

correlations correspond to tau levels of 0.7 and greater (Helsel 

and Hirsch, 1992). The criterion for statistical significance 

used was the 0.05 significance level. The annual minimum, 

maximum, 10th, 30th, 50th, 70th, and 90th percentiles of 

streamflow were tested for trends to gain information about 

how different parts of the streamflow regime have changed over 

time. Temporal trends in streamflow also were analyzed over 

15 multidecadal periods, ranging from 20 to 60 years, to gain 

insight into the short-term temporal trends and the persistence 

of any temporal trends over time. Long-term temporal trends in 

lake levels in Polk County were updated during this study using 

data from 1960-2003. Temporal trends also were determined 

for 1990-2003, using a larger set of lakes, to quantify recent 

trends that may have occurred.

Kendall’s tau and the resulting p-values were corrected 

for ties in the time series according to Helsel and Hirsch 

(1992). A large number of ties (values with the same sign and 

magnitude) can cause misleading results when calculating and 

interpreting Kendall’s tau. The variance of the test statistic is 

used to calculate the p-values associated with Kendall’s tau. 

As the number of ties in the time series increases, the variance 

of the test statistic decreases, which results in a more significant value of Kendall’s tau.

 CHAPTER 2—Streamflow and Lake-Level Characteristics in Polk County

  67
68  Hydrology of Polk County, Florida

aquifer system (Lewelling and others, 1998). Several investigators (Geraghty and Miller, Inc., 1980; Barcelo and others, 

1990) also reported declining water levels over time in several 

of the lakes in Polk County, most notably in Crooked Lake, 

Lake Clinch, and Lake Buffum. Other lakes, such as Reedy 

Lake, have had no substantial declines in lake levels (Barcelo 

and others, 1990) despite being in the immediate vicinity of 

lakes that do.

Streamflow Characteristics

Mean annual runoff for individual basins in the county 

ranges from 6.6 to 16.1 in. (table 2). Runoff was calculated by 

dividing the mean annual streamflow by the basin area and is 

given in inches of water over the entire basin area. Streamflow 

generally has a seasonal distribution, which is similar to the 

Peace River at Bartow (fig. 58). Streamflow generally is greatest in September and October, which is near the end of the wet 

season. The lowest streamflow usually occurs in May or June.

Several investigators (Enfield and others, 2001; McCabe 

and Wolock, 2002; Basso and Schultz, 2003; Kelly, 2004) have 

related streamflow conditions in Florida and elsewhere in the 

United States to shifts in climatic conditions or multidecadal 

cycles in precipitation. Enfield and others (2001) reported 

Mississippi River outflow varied by 10 percent between warm 

and cool AMO phases, and the estimated unregulated inflow to 

Lake Okeechobee varied by 40 percent. Kelly (2004) reported 

significantly higher streamflows in west-central Florida during 

1940-1969 compared to 1970-1999, which roughly coincides 

with the warm and cool phases of the AMO.

POLK COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

B a s e m o d ifie d fro m U .S . G e o lo g ic a l S u rv e y d ig ita l d a ta , 1 :1 0 0 ,0 0 0 , 1 9 8 5 U n iv e rs a l Tra n sv e rs e Me rc a to r p ro je c tio n , z o n e 1 7 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

82°00′ 45′ 30′ 81°15′

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Wi o thlac och

r

ee Rive

P e a c e R iver

K

m issim

ee River

2 6

5 7

9

8

1

39

42

24

47

58

36

16

21

20

54

22

51

34

53

44

56

40

13

50

15

49

38

26

37

45 55

43

59

57

29

60

46

41

48

10

4

3

30

23

18

32

19

28

14

31

33

17

52

11

27

12

35

25

MULBERRY BARTOW

FROSTPROOF

FORT MEADE

BRADLEY JUNCTION

DAVENPORT

HAINES

CITY

DUNDEE

LAKE WALES

POLK CITY

65

72

74

73

75

71

70

69

68

67

66

63

61

64

62

76

EXPLANATION

38 LAKE SITE AND NUMBER

72 STREAM SITE AND NUMBER

Figure 56. Location of lakes and streams analyzed in this report (site names in appendix 3).
Table 2. Mean annual flow and runoff for selected streams in Polk County, water years 1991-2003.

[Locations of site numbers shown in figure 56]

Site 

number Location name Drainage basin

Drainage area, 

in square miles

Mean annual flow, 

in cubic feet per 

second

Mean annual runoff, 

in inches

76 Withlacoochee River near Cumpressco Withlacoochee 280 144 7.0

65 Green Swamp Run near Eva Withlacoochee 43 29.1 9.2

72 Catfish Creek near Lake Wales Kissimmee 58.9 35.5 8.2

73 Tiger Creek near Babson Park Kissimmee 52.8 37.9 9.8

74 Kissimmee River at S-65, near Lake Wales Kissimmee 1,607 1,274 10.8

75 Livingston Creek near Frostproof Kissimmee 120 58 6.6

66 Fox Branch near Socrum Hillsborough 9.5 11.3 16.1

67 Saddle Creek near Structure P-11 near Bartow Peace 135 83.1 8.4

68 Peace River at Bartow Peace 390 215 7.5

69 Peace Creek Drainage Canal near Wahneta Peace 162 97 8.1

70 Peace River at Fort Meade Peace 480 259 7.3

71 Bowlegs Creek near Fort Meade Peace 47.2 29.1 8.4

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Withlacooche Ri e

e

v r

Peace River

Lake

Hatchineha

Tiger Creek

Lake

Arbuckle

Livingston Creek

Reedy Lake

Lake Clinch

Lake

Buffum

Catfish

Creek

Lake

Pierce

Lake

Marion

Peace Creek

Drainage Canal

Fox

Branch

Saddle

Creek Structure

P-11

S-65A

Green Swamp Run

Bowlegs Creek

Saddle

Creek

Tiger

Lake

Lake Lucerne

Saddle Blanket Lakes

Swim

Lake

K issi m m e e R iv e r

Lake

Kissimmee

S-65

S-65

KISSIMMEE

RIVER BASIN

PEACE RIVER

BASIN

ALAFIA

RIVER

BASIN

WITHLACOOCHEE

RIVER BASIN

HILLSBOROUGH

RIVER 

BASIN

OCKLAWAHA

RIVER BASI

N

POLK

COUNTY

LAKE COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY

PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

82°00′ 45′ 30′ 81°15′

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985

Universal Transverse Mercator projection, zone 17 0 10 MILES

0 10

5

5 15 KILOMETERS

28°15′

28°00′

27°45′

Lakeland

Bartow

Fort

Meade

Frostproof

Cumpressco

Lake

Wales

EXPLANATION

CONTROL STRUCTURE--Location

and number.

Figure 57. Major surface-water drainage basins, tributaries, and lakes.

Streamflow and Lake Level Characteristics  69
70 Hydrology of Polk County, Florida

Peace River Basin

The confluence of Saddle Creek and the Peace Creek 

Drainage Canal form the headwaters of the Peace River (fig. 

57). Saddle Creek originates from lakes north of the city of 

Lakeland, and is regulated by structure P-11, which is near the 

outlet of Lake Hancock. As its name implies, the Peace Creek 

Drainage Canal is not a natural stream. Peace Creek was 

dredged in the 1930s and in places was channelized to drain 

the land, forming the Peace Creek Drainage Canal (Southwest 

Florida Water Management District, 2002).

The natural hydrography of the part of the Peace 

River Basin north of Fort Meade was altered by the surface 

mining of phosphate ore (T. King, Florida Fish and Wildlife 

Conservation Commission, written commun., 1995; University 

of South Florida, 2003; Basso, 2003). Reclamation of surfacemined land prior to July 1, 1975, was voluntary (Florida 

Institute of Phosphate Research, 2006a), and the post-mining 

topography was generally characterized by mine pit lakes, 

clay settling areas, sand tailings, and tracts of homogenized 

overburden (University of South Florida, 2003). Since 1975, 

the State of Florida required reclamation of all surface-mined 

areas (Florida Statutes, chapter 378), which generally consists 

of reshaping the land to resemble the premining topography 

and hydrography and replanting the landscape (Florida 

Institute of Phosphate Research, 2006b). Clay settling areas 

are former mine pits where fine particles of waste sand, clay, 

and phosphate from the beneficiation process are allowed 

to settle and consolidate. Beneficiation refers to the process 

used to separate the sand and clay from the phosphate rock. 

The waste products from phosphate mining typically consist 

of a slurry of about 3- to 5-percent solids. This slurry takes 

years to settle and eventually consolidates into a relatively 

impermeable layer. Lewelling and Wylie (1993) determined 

the hydraulic conductivity of materials redeposited in areas 

reclaimed with waste clay ranged from 0.01 to 1.2 ft/d, which 

is lower compared to values in areas reclaimed using other 

methods.

Surface-water drainage to the Peace River within Polk 

County is limited. Most of the surface-water drainage to the 

river between Bartow and Fort Meade is water released from 

five phosphate-mine outfalls and reclaimed stream channels 

(Lewelling and others, 1998; Basso, 2003). Bowlegs Creek 

is the largest tributary to the Peace River within Polk County 

(fig. 57), and provides a minor amount of flow to the river. 

The mean annual streamflow in Bowlegs Creek near Fort 

Meade (site 71) was 29.1 ft3/s, compared to 215 ft3/s in the 

Peace River at Bartow (site 68), based on data from water 

years 1991-2003 (table 2). The water year is the 12-month 

period from October 1 through September 30. The water year 

is designated by the calendar year in which it ends. Thus, the 

year ending September 30, 2002, is called the 2002 water year.

Flow-duration curves constructed from data collected at 

the Bartow and Fort Meade stream gages illustrate the loss 

of water from the Peace River to the ground-water system 

during low-flow conditions along this reach (fig. 59). During 

low-flow conditions, streamflow per square mile at Bartow 

is greater compared to the downstream Fort Meade site. 

Furthermore, the entire flow of the river has been observed 

disappearing into karstic features in the streambed during dry 

Figure 58. Flow-duration hydrographs for Peace River at Bartow, water years 1979-2003.

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

STREAMFLOW, IN CUBIC FEET PER SECOND

10

100

PEACE RIVER AT BARTOW

(SITE 68)

1,000

75th PERCENTILE

MEDIAN

25th PERCENTILE

Statistics were based on data from

water years 1979-2003
periods (Hammett, 1990; Barr, 1992; Lewelling and others, 

1998). Seepage runs have been conducted along the Peace 

River during low- and high-flow conditions to quantify the 

amount of water lost to the ground-water system. Seepage runs 

consist of a series of streamflow measurements along a stream 

reach during stable flow conditions to quantify streamflow 

gains and losses. Between Bartow and Fort Meade, the Peace 

River lost 16 to 30 ft3/s of water during low-flow conditions 

(Lewelling and others, 1998; R. Basso, Southwest Florida 

Water Management District, written commun., 2006). Some 

water also may be lost to the ground-water system during 

high-flow conditions. Lewelling and others (1998) reported 

a loss of 118 ft3/s during high-flow conditions, although this 

loss of water may be an artifact of the measurement technique, 

which had an estimated error of 5 to 8 percent.

Previous studies reported statistically significant declining streamflows in the Peace River at Bartow from 1940-2002 

(Hammett, 1990; Flannery and Barcelo, 1998; Lewelling and 

others, 1998; Southwest Florida Water Management District, 

2002). This decrease has been attributed to rainfall deficits, 

which have occurred since about 1960, and the lowering 

of the potentiometric surface of the Upper Floridan aquifer 

in the area (fig. 34). Previous analyses of the data from the 

Bartow and Fort Meade stream gages have indicated that most 

of these decreases occurred prior to 1965. Most investigators have reported no significant trends in annual mean or 

mean monthly streamflows from 1965-2000 (Flannery and 

Barcelo, 1998; Lewelling and others, 1998). These stationary trends were attributed to improved water-conservation 

practices implemented by the phosphate-mining industry. One 

study (Southwest Florida Water Management District, 2002) 

reported a significant reduction in low streamflows (10th 

percentile) at the Peace River at Bartow from 1970-1990. 

This decrease was attributed to reductions in point-source 

discharges to the river during the 1980s.

Temporal trend analyses conducted over several multidecadal periods in this report indicate annual minimum to 70th 

percentile streamflows have declined in the upper part of the 

Peace River. The analyses also indicate these declines began in 

the 1950s and have persisted to 2003. An analysis of the data 

over a series of 20-year periods showed that annual minimum 

and 10th percentile streamflows from the Peace River at 

Bartow significantly increased from water years 1944-1963 

(table 3), which is consistent with the trend analyses reported 

by the Southwest Florida Water Management District (2002). 

Annual minimum to 70th percentile streamflows at the Bartow 

site, however, significantly decreased from 1954-1973. 

These decreases persisted when data over 30-, 40-, 50-, and 

60-year periods were analyzed (tables 4 and 5). In contrast to 

the results from other studies that reported stabilized annual 

PERCENT OF TIME EQUALED OR EXCEEDED

0.1

1

10

STREAMFLOW PER UNIT AREA,

IN CUBIC FEET PER SECOND PER SQUARE MILE

1 2 5 10 25 50 75 90 95 98 99

FOX BRANCH NEAR SOCRUM (SITE 66)

KISSIMMEE RIVER AT S-65 (SITE 74)

SADDLE CREEK (SITE 67)

PEACE RIVER AT BARTOW (SITE 68)

PEACE RIVER AT FORT MEADE (SITE 70)

GREEN SWAMP RUN NEAR EVA (SITE 65)

CATFISH CREEK NEAR LAKE WALES (SITE 72)

WITHLACOOCHEE RIVER NEAR CUMPRESSCO (SITE 76)

Figure 59. Flow-duration curves for selected stream sites in Polk County, water years 1979-2003.

Streamflow and Lake Level Characteristics  71
72  Hydrology of Polk County, Florida

Table 3. Temporal trends in streamflow over 20-year periods for Peace River at Bartow.

[Top value, Kendall’s tau; bottom value, p-value; values significant at the 0.05 significance level are 

shown in bold]

Flow statistic

Period analyzed

1944-1963 1954-1973 1964-1983 1974-1993 1984-2003

Annual minimum flow 0.5579

.0006

-0.5158

.0016

-0.1579

.3457

-0.3789

.0211

-0.2368

.1522

Annual 10th percentile .5474

.0008

-.4947

.0026

-.3158

.0556

-.2684

.1046

-.1579

.3462

Annual 30th percentile .3105

.0597

-.4474

.0064

-.2842

.0852

-.2105

.2048

-.0316

.8710

Annual 50th percentile .2316

.1630

-.3632

.0273

-.2000

.2300

-.1263

.4556

.0789

.6495

Annual 70th percentile .0316

.8711

-.3263

.0478

-.0211

.09225

-.1474

.3810

.1368

.4173

Annual 90th percentile -.0632

.7211

-.2526

.1273

.0000

1.0000

.0316

.8711

.1368

.4173

Annual maximum flow -.1000

.5590

-.2211

.1834

.0211

.9225

-.0158

.9482

.3263

.0478

Table 4. Temporal trends in streamflow over 30-year periods for Peace River at 

Bartow. 

[Top value, Kendall’s tau; bottom value, p-value; values significant at the 0.05 significance 

level are shown in bold]

Flow statistic

Period analyzed

1944-1973 1954-1983 1964-1993 1974-2003

Annual minimum flow -0.0115

.9431

-0.4989

.0001

-0.4598

.0004

-0.3724

.0040

Annual 10th percentile .0161

.9147

-.5310

.0000

-.4920

.0001

-.2598

.0455

Annual 30th percentile -.1609

.2181

-.4712

.0003

-.4207

.0012

-.1172

.3719

Annual 50th percentile -.1471

.2609

-.3862

.0029

-.3241

.0125

.0069

.9715

Annual 70th percentile -.2368

.0688

-.2368

.0688

-.2230

.0868

.0253

.8584

Annual 90th percentile -.2920

.0246

-.1494

.2535

-.0943

.4754

.0805

.5441

Annual maximum flow -.3126

.0160

-.0989

.4537

-.1149

.3819

.2046

.1163
mean and mean monthly streamflows from the 1970s to the 

1990s, there were significant decreases in the annual minimum 

streamflows at the Bartow (tau = -0.3789, p = 0.0211) and Fort 

Meade (tau = -0.2709, p = 0.0407) sites from 1974-1993 and 

1975-1993, respectively.

Annual 90th percentile and maximum streamflows in the 

Peace River at Bartow significantly decreased from 1944-1993. 

Significant decreases in 90th percentile and annual maximum 

streamflows were determined using Kendall’s tau from 1944-

1973, 1944-1983, and 1944-1993 (tables 4 and 5).

Several factors have been attributed to the reduced 

streamflow in the Peace River within Polk County, including the increased pumpage of ground water, lower rainfall 

amounts from about 1960-2000, which may be associated with 

the cool phase of the AMO, and elimination of point-source 

discharges. The increased pumpage of ground water in the 

Peace River Basin over time and the corresponding effect on 

Upper Floridan aquifer levels was discussed previously in this 

report. Reducing Upper Floridan aquifer levels may increase 

the potential for leakage from the surficial and intermediate 

aquifer systems to the Upper Floridan aquifer, thus reducing 

the amount of water available to contribute baseflow to the 

Peace River. Declines in streamflow from about 1940-2000 

also have been attributed by several investigators to deficient 

rainfall associated with the cool phase of the AMO in Florida 

(Enfield and others, 2001; Basso and Schultz, 2003; Kelly, 

2004). Nationally, step changes in streamflow around 1970 

were documented and attributed to changes in precipitation 

(McCabe and Wolock, 2002). Multidecadal variations in rainfall may be especially important to understand the variations 

in high streamflows in the Peace River (R. Basso, Southwest 

Florida Water Management District, written commun., 2006). 

Annual 90th percentile and maximum streamflow in the 

Peace River at Bartow were determined in this study to be 

significantly greater from 1940-1960 compared to 1970-90 

(p = 0.0001 and p = 0.0023, respectively), which is consistent 

with the phases of the AMO. Decreases in annual minimum streamflows at the Bartow and Fort Meade sites from 

1974-1993 likely resulted from the elimination or reduction 

of point-source discharges to the river. A number of pointsource discharges to the Peace River or its tributaries were 

reduced or eliminated around 1995 (Southwest Florida Water 

Management District, 2002).

In contrast to the streamflow declines that have been 

documented in the Peace River, there were significant 

increases in the 90th percentile to maximum annual streamflows at the Fort Meade site from 1975-2003. There was a 

significant increase in annual maximum streamflows at the 

Fort Meade site from 1975-2003 (tau = 0.2808, p = 0.0340) 

and 1984-2003 (tau = 0.3789, p = 0.0212). There also was a 

significant increase in annual maximum streamflows at the 

Bartow site from 1984-2003 (table 3).

The effect of reducing pumpage in the Peace River Basin 

on restoring the potential for upward flow from the Upper 

Floridan aquifer and springflow from Kissengen Spring was 

evaluated by Basso (2003) using a ground-water flow model 

calibrated to 1989 conditions and a graphical analysis. The 

study concluded that ground-water withdrawals would need to 

be reduced by 60 to 80 percent for the Upper Floridan aquifer 

to contribute baseflow to the section of the Peace River from 

Bartow to Fort Meade and to return flow to Kissengen Spring.

There were no significant temporal trends in streamflows in Saddle Creek, and there were insufficient data from 

the Bowlegs Creek and the Peace Creek Drainage Canal 

Table 5. Temporal trends in streamflow over 40-, 50-, and 60-year periods for Peace River at Bartow.

[Top value, Kendall’s tau; bottom value, p-value; values significant at the 0.05 significance level are shown in bold]

Flow statistic

40-year period 50-year period 60-year period

1944-1983 1954-1993 1964-2003 1944-1993 1954-2003 1944-2003

Annual minimum flow -0.2205

.0461

-0.6244

.0000

-0.4705

.0000

-0.4237

.0000

-0.6155

.0000

-0.4876

.0000

Annual 10th percentile -.2308

.0370

-.6167

.0000

-.4410

.0001

-.4147

.0000

-.5755

.0000

-.4497

.0000

Annual 30th percentile -.3359

.0023

-.5487

.0000

-.2897

.0087

-.4661

.0000

-.4416

.0000

-.4181

.0000

Annual 50th percentile -.2949

.0076

-.4551

.0000

-.1808

.1028

-.4073

.0000

-.3355

.0006

-.3362

.0002

Annual 70th percentile -.2641

.0169

-.3538

.0014

-.0718

.5216

-.3829

.0001

-.2229

.0229

-.2791

.0017

Annual 90th percentile -.2590

.0192

-.2051

.0640

-.2590

.0192

-.3061

.0018

-.1135

.2483

-.2192

.0136

Annual maximum flow -.2551

.0210

-.1756

.1130

.1102

.3219

-.2996

.0022

.0008

1.000

-.1475

.0972

Streamflow and Lake Level Characteristics  73
74  Hydrology of Polk County, Florida

tributaries to quantify temporal trends. The lack of temporal 

trends in Saddle Creek was in contrast with other investigations that reported a significant decline in streamflow 

(T. King, Florida Fish and Wildlife Conservation Commission, 

written commun., 1994; University of South Florida, 2003). 

These declines were partly attributed to changes in basin 

hydrography, which occurred after the area was surface 

mined. Approximately 70 percent of the northern part of the 

Saddle Creek Basin was surface mined prior to 1960 and left 

unreclaimed by the original owners of the mine (T. King, 

Florida Fish and Wildlife Conservation Commission, written 

commun., 1994; BCI, 2000). This resulted in surface runoff 

being diverted into canals or impounded in mine pit lakes or 

clay settling areas. Lewelling and Wylie (1993) compared the 

hydrologic characteristics of small unimpacted basins in the 

vicinity of southwestern Polk County to those with substantial 

amounts of reclaimed mined land. There was no sustained 

baseflow to streams in basins where the mined lands were 

backfilled with clay. The declining streamflows noted in the 

previous studies likely resulted from more water being stored 

in these features. The lack of temporal trends in Saddle Creek 

determined in this report likely resulted from the period of 

record of the analyzed data. Data were analyzed in this report 

from 1963-2003, which is subsequent to the hydrography 

changes that likely affected streamflows in Saddle Creek.

Kissimmee River Basin

The Kissimmee River Basin includes about 700 mi2 of 

the eastern part of Polk County and is the largest watershed 

providing water to Lake Okeechobee. Water-resource managers typically subdivide the Kissimmee River Basin into the 

upper and lower basins. The southern boundary of the Upper 

Kissimmee River Basin generally corresponds to State Road 

60 (U.S. Army Corps of Engineers, 1996). Polk County 

contains parts of both the Upper and Lower Kissimmee 

River Basins (fig. 57). The Upper Kissimmee River Basin 

generally does not contain a well-defined stream channel 

for the Kissimmee River (which begins at the outlet of Lake 

Kissimmee) and is characterized by many lakes connected 

by a series of canals. The Lower Kissimmee River Basin 

is characterized by the channelized Kissimmee River and 

tributary streams.

Most of the Kissimmee River Basin is regulated for 

flood-control purposes as part of the comprehensive Central 

and South Florida Flood Control Project. Nine water-control 

structures constructed between 1964 and 1970, located on 

streams, lakes, and canals upstream of Polk County in Osceola 

and Orange Counties, currently (2005) are operated to lower 

water levels from January through May to provide storage 

for wet-season precipitation (U.S. Army Corps of Engineers, 

1996). The entire Kissimmee River was channelized from 

1962 to 1971, resulting in a reduction in the total length of the 

river from 103 to 56 miles (U.S. Army Corps of Engineers, 

1991). The channelized Kissimmee River is often referred to 

as Canal 38 or C-38 (U.S. Army Corps of Engineers, 1996). 

The channelized river is about 30 ft deep (U.S. Army Corps 

of Engineers, 1991). Six water-control structures and locks 

originally were located on C-38 to step the canal down in 6-ft 

increments, which segmented the canal into five navigation 

pools. Two of these water-control structures (S-65 and S-65A) 

are located on the border of Polk County. These structures 

historically were managed to maintain a constant water level 

in the navigation pools (U.S. Army Corps of Engineers, 1991).

The streams draining the large lakes in eastern Polk 

County provide minor amounts of streamflow to the 

Kissimmee River. Three of these streams are instrumented 

by the USGS to continuously measure streamflow—Catfish 

Creek (site 72), Tiger Creek (site 73), and Livingston Creek 

(site 75) (figs. 56 and 57). Streamflow has been monitored on 

Catfish Creek since 1947, and has been monitored on Tiger 

and Livingston Creeks since 1991. The average streamflow 

in the Kissimmee River at S-65 is 1,274 ft3/s based on data 

from water years 1991-2003 (table 2). The average streamflow 

in Catfish Creek, Livingston Creek, and Tiger Creek for the 

same period is 35.5, 58, and 38 ft3/s, respectively. Streamflow 

per square mile in Catfish Creek is less variable (resulting in 

a flatter slope on the flow-duration curve) compared to other 

streams in Polk County (fig. 59) due to the large amount of 

storage available in Lake Pierce.

Prior to regulation, the Kissimmee River was described as 

resembling a large lake during major flood events (U.S. Army 

Corps of Engineers, 1991). Lakes in the upper part of the basin 

formerly contributed inflow to the Kissimmee River most 

of the time; flow in the river generally was greater than 100 

ft3/s about 95 percent of the time (fig. 60). Streamflows had a 

seasonal variation similar to the other streams in the county. 

Prior to regulation, the highest median streamflows generally 

occurred in September and October and the lowest occurred in 

June and July (fig. 61). Over one-half of the time, 94 percent 

(about 42,000 acres) of the floodplain of the Kissimmee 

River historically was inundated with water (Koebel, 1995). 

Overbank flow generally occurred in the upper part of the 

river when streamflows exceeded 1,400 ft3/s (Koebel, 1995). 

Hydroperiods generally were longest near the river channel 

and the part of the basin within Polk County (Toth and others, 

1995). Water in the lakes in the Upper Kissimmee Basin also 

would overflow the banks for about 3 to 5 months during the 

wet season and inundate the surrounding wetland areas (U.S. 

Army Corps of Engineers, 1996). During wet years, inundation of the wetlands surrounding the lakes could last as long as 

10 months (U.S. Army Corps of Engineers, 1996).

The hydrologic characteristics of much of the Kissimmee 

River were altered due to regulation of lake levels and channelization in the basin. The regulation schedule implemented 

in the Upper Kissimmee River lakes results in frequent periods 

of no discharge to C-38 (Obeysekera and Loftin, 1990). The 

median streamflow in the Kissimmee River at S-65 was near 

zero about one-half of the time, primarily during the months 

of June-July and October-December based on data from water 

years 1979-2003 (figs. 60 and 61). The seasonal variation in 

streamflows has changed dramatically as well. Streamflows 
generally were greatest from January-May and in August 

compared to other times of the year based on data from water 

years 1979-2003 (fig. 61). Streamflow also was greater during 

high-flow events from water years 1979-2003 compared to 

water years 1930-1969 due to less storage in the basin (fig. 

60). Many of the original river meanders are now stagnant and 

have filled in with vegetation and sediment (U.S. Army Corps 

of Engineers, 1991). The only original river meanders with 

flowing water receive tributary inflow (U.S. Army Corps of 

Engineers, 1991).

Regulation of the Kissimmee River Basin has resulted in 

adverse ecological impacts to the watershed. The floodplain of 

the river historically was dominated by wetlands. Forty-four 

percent of these wetlands were drained and replaced with 

improved and unimproved pasture (Toth and others, 1995). 

The lack of flow to most of the remaining meanders in the 

Kissimmee River has drastically changed habitat conditions 

and has allowed aquatic macrophytes (plants) to encroach 

upon the center of these channels (Toth and others, 1995). 

Water-level fluctuations in the wetlands that existed prior 

to channelization have been largely eliminated, which has 

resulted in less diverse wetland plant communities (Koebel, 

1995; Toth and others, 1995). Water fowl usage of the 

Kissimmee River floodplain decreased 92 percent by the 

1970s (Perrin and others, 1982), and waterfowl were replaced 

with species generally associated with upland, terrestrial 

habitats (Koebel, 1995). Dissolved-oxygen concentrations 

in C-38 and the remnant river channels were lower than the 

5-mg/L criterion recommended for the protection of aquatic 

life. Concentrations typically range from 2 to 3 mg/L near the 

surface of the channel and less than 1 mg/L at depths greater 

than 3 to 6 ft (Toth and others, 1995). Low dissolved-oxygen 

conditions have resulted in sport fish, such as largemouth bass, 

being replaced with species tolerant of poorer water-quality 

conditions, such as gar and bowfin (Koebel, 1995).

The flood-control project in the Kissimmee River Basin 

currently (2005) is being modified by the State of Florida 

and the Federal Government to restore the ecosystem by: 

(1) re-establishing the historical hydrologic conditions; 

(2) recreating the historic river/floodplain connectivity; 

(3) recreating the historical mosaic of wetland plant communities; and (4) restoring the historical biological diversity 

(South Florida Water Management District, 2005b). Restoring 

the ecosystem of the Lower Kissimmee River Basin is to be 

PERCENT OF TIME EQUALED OR EXCEEDED

10

STREAMFLOW, IN CUBIC FEET PER SECOND

1 2 5 10 25 50 75 90 95 98 99

100

1,000

10,000

WATER YEARS 1930-1969

WATER YEARS 1979-2003

Figure 60. Flow-duration curves for Kissimmee River at S-65, water years 1930-1969 and water years 1979-2003.

Streamflow and Lake Level Characteristics  75
76  Hydrology of Polk County, Florida

75th PERCENTILE

MEDIAN

25th PERCENTILE

WATER YEARS 1979 - 2003

MEDIAN

25th PERCENTILE

75th PERCENTILE

WATER YEARS 1930 - 1969

OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. 0

1,000

2,000

3,000

4,000

STREAMFLOW, IN CUBIC FEET PER SECOND

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Figure 61. Flow-duration hydrographs for Kissimmee River at S-65 (site 74), water years 1930-1969 and 

1979-2003.
accomplished through two major projects: (1) the Headwaters 

Revitalization project in the upper basin and (2) the Modified 

Level II Backfilling plan in the lower basin (Koebel, 1995). 

The Headwaters Revitalization project will modify the regulation schedules for the headwaters lakes to provide greater and 

more natural fluctuations of water levels in the lakes. The S-65 

structure was modified in 2001 to provide a higher discharge 

capacity (Koebel, 1995; South Florida Water Management 

District, 2005a). The Modified Level II Backfilling plan 

includes the backfilling of 22 miles of canal, removal of 

two water-control structures, and the recarving of 9 miles 

of former river channel (South Florida Water Management 

District, 2005b). The project area for most of the Modified 

Level II Backfilling plan is located downstream from Polk 

County.

Alafia, Hillsborough, Ocklawaha, and 

Withlacoochee River Basins

The Alafia, Hillsborough, Ocklawaha, and Withlacoochee 

River Basins make up about 600 mi2 of Polk County (fig. 57). 

The Alafia and Hillsborough River Basins are characterized 

by land that is flat and relatively high; the Ocklawaha River 

Basin is characterized by high, sandy ground (Heath, 1961). 

Drainage from this basin is to the north through poorly defined 

stream channels (Heath, 1961). Within Polk County, the 

Withlacoochee River Basin is characterized by innumerable 

low hammocks and shallow cypress ponds (Heath, 1961).

The only streams gaged in these basins in or in near Polk 

County are the Withlacoochee River and two streams in the 

Ocklawaha and Hillsborough Rivers—Green Swamp Run and 

Fox Branch, respectively. No streams within the Alafia Basin 

are gaged in or near the county. The Withlacoochee River is 

the largest of these streams, with a mean annual streamflow 

of 144 ft3/s (table 2). The Fox Branch and Green Swamp 

Run sites periodically have no flow. Fox Branch has no flow 

less than 5 percent of the time (fig. 59). In contrast, Green 

Swamp Run near Eva has no flow more than one-half of the 

time. Flow-duration curves for the Withlacoochee River near 

Cumpressco and Green Swamp Run flatten out during high 

streamflows because of storage of water in wetlands.

Low-Flow and Flood-Frequency Statistics

Low-flow frequency statistics may aid in determining requirements for: (1) the amount of water that may be 

withdrawn from a stream, or (2) disposal of treated wastes 

to streams. Low-flow frequency statistics are presented in 

tables 6 through 14, and flood-flow frequency statistics are 

presented in table 15. Low-flow and flood-flow frequency 

statistics were not computed for the Kissimmee River at 

S-65 due to the regulated nature of this stream. There were 

insufficient non-zero data from Green Swamp Run near Eva 

to compute low-flow frequency statistics for 1-, 2-, 3-, 7-, 

10-, 30-, 60-, and 90-day annual minimum flows. The Peace 

River at Bartow, Peace River at Fort Meade, and Catfish Creek 

near Lake Wales sites had significant temporal trends in the 

low-flow data over the entire period of record. Frequency 

analysis assumes the data were homogeneous and were not 

affected by temporal trends associated with either watershed 

or climatic changes. For this reason, data from water years 

1985-2003 were analyzed to determine low-flow frequency 

statistics for the Bartow and Fort Meade sites. The period of 

record from 1965-2003 was analyzed to determine low-flow 

frequency statistics at the Catfish Creek site. Flood-flow 

frequency estimates at the Peace River at Bartow, Peace River 

at Fort Meade, and Fox Branch sites were similar to estimates 

reported by Hammett and DelCharco (2005) who analyzed 

data through 2001. Flood-flow frequencies listed in this report 

and those reported by Hammett and DelCharco (2005) generally were within the standard error of the estimates.

Lake Characteristics

Polk County ranks fourth in the State of Florida in the 

number of lakes per county (Gant, 1993). There are about 

900 lakes or open-water features with a surface area greater 

than 10 acres (fig. 56). Ninety-four percent of the lakes or 

open-water features in the county are located within the 

Alafia, Kissimmee, and Peace River Basins. Lakes located 

on the ridge areas are thought to occupy depressions formed 

by sinkholes (Sinclair and others, 1985; Barcelo and others, 

1990; Yobbi, 1996), and generally lack surface-water inflows 

or outflows. The large lakes located in eastern Polk County, 

such as Lake Marion and Lake Pierce (fig. 62), originally 

were deeper parts of a vast wetland that occupied the area 

prior to human development (U.S. Army Corps of Engineers, 

1996). Water from most of these large lakes, with the exception of Lake Arbuckle, flows to Lake Kissimmee by streams 

and canals. Water from Lake Arbuckle flows southward 

and eventually discharges into Lake Istokpoga in Highlands 

County (not shown). The numerous small open-water features 

in southwestern Polk County are not natural lakes but are 

former mine pits and bermed clay-settling areas formed 

during phosphate-mining operations (Southwest Florida Water 

Management District, 2003). A few of the named lakes within 

the vicinity of Lakeland (fig. 62) originated from phosphatemining activities, including Lake Bentley, Lake Crago, and 

Lake John (City of Lakeland, 2001). Most of these lakes were 

created in the 1950s and 1960s.

Most of the lakes in Polk County exchange water with the 

ground-water system. Direct runoff from the land surface into 

these lakes, with the exception of stormwater runoff in urban 

areas, is considered to be minimal because of the high permeability of the sandy soils in the area. Lakes can be classified 

as seepage and drainage lakes. Seepage lakes have no surfacewater inflow or outflow, and primarily lose water through 

the ground-water system or evaporation. Drainage lakes 

primarily lose water through a surface-water outlet. Seepage 

lakes receive ground-water inflow from the surficial aquifer 

Streamflow and Lake Level Characteristics  77
78  Hydrology of Polk County, Florida

Table 6. Low-flow frequency statistics for Catfish Creek near Lake Wales.

[Site 72, figure 56. Period of record analyzed was water years 1965-2003. SEx,y, standard error of the x-day annual minimum flow 

with a y-year recurrence interval. Accuracy, SE7,2=2.1 ft3/s, SE7,10=0.4 ft3/s, SE30,2=2.5 ft3/s, SE30,10=0.7 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 8.8 8.8 8.8 9.1 11 11 13 16 23 34

5 2.2 2.3 2.4 2.6 2.7 3.7 5.6 7.9 13 22

10 .7 .8 .9 1.0 .9 1.8 3.2 4.8 9.4 17

20 .2 .2 .3 .4 .3 .9 1.9 3.1 6.9 14

50 0 0 0 0 .1 .4 1.0 1.7 4.7 10

Table 7. Low-flow frequency statistics for Fox Branch near Socrum.

[Site 66, figure 56. Period of record analyzed was water years 1966-2003. SEx,y, standard error of the x-day annual minimum flow 

with a y-year recurrence interval. Accuracy, SE30,2=0.1 ft3/s, SE30,10=0.03 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 0.3 0.3 0.3 0.4 0.4 0.8 1.2 1.7 3.3 8.3

5 0 0 0 .01 .04 .3 .5 .8 1.9 5.5

10 0 0 0 0 0 .1 .3 .5 1.4 4.5

20 0 0 0 0 0 0 .2 .4 1.1 3.7

50 0 0 0 0 0 0 0 .2 .8 3.1

Table 8. Low-flow frequency statistics for Green Swamp Run near Eva.

[Site 65, figure 56. Period of record analyzed was water years 1979-2003. SEx,y, standard error of the x-day annual minimum flow 

with a y-year recurrence interval. Accuracy, SE365,2=1.9 ft3/s, SE365,10=0.3 ft3/s. NC, not computed]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 NC NC NC NC NC NC NC NC 0.2 5.4

5 NC NC NC NC NC NC NC NC 0 1.3

10 NC NC NC NC NC NC NC NC 0 .6

20 NC NC NC NC NC NC NC NC 0 .3

50 NC NC NC NC NC NC NC NC 0 .1
Table 9. Low-flow frequency statistics for Bowlegs Creek near Fort Meade. 

[Site 71, figure 56. Period of record analyzed was water years 1965-68, 1992-2003. SEx,y, standard error of the x-day annual 

minimum flow with a y-year recurrence interval. Accuracy, SE7,2=0.2 ft3/s, SE7,10=0.1 ft3/s, SE30,2=0.3 ft3/s, SE30,10=0.2 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 1.2 1.2 1.3 1.3 1.4 1.7 2.2 3.3 6.7 12

5 .7 .7 .7 .8 .8 1.0 1.3 1.8 3.2 14

10 .5 .5 .5 .6 .6 .7 1.0 1.3 2.2 18

20 .4 .4 .4 .4 .5 .6 .8 1.0 1.6 26

50 .3 .3 .3 .3 .3 .4 .6 .8 1.1 10

Table 10. Low-flow frequency statistics for Livingston Creek near Frostproof.

[Site 75, figure 56. Period of record analyzed was water years 1992-2003. SEx,y, standard error of the x-day annual minimum 

flow with a y-year recurrence interval. Accuracy, SE7,2=1.6 ft3/s, SE7,10=0.9 ft3/s, SE30,2=2.2 ft3/s, SE30,10=1.3 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 8.7 8.8 8.9 9.4 9.9 12 16 18 27 48

5 5.9 5.9 6.0 6.2 6.4 7.6 9.6 11 16 33

10 4.9 4.9 4.9 5.1 5.2 6.0 7.4 8.9 12 28

20 4.2 4.3 4.3 4.3 4.4 4.9 5.9 7.3 10 24

50 3.6 3.7 3.7 3.7 3.7 3.9 4.6 5.9 8.0 21

Table 11. Low-flow frequency statistics for Peace Creek Drainage Canal near Wahneta.

[Site 69, figure 56. Period of record analyzed was water years 1992-2003. SEx,y, standard error of the x-day annual minimum 

flow with a y-year recurrence interval. Accuracy, SE7,2=1.6 ft3/s, SE7,10=0.5 ft3/s, SE30,2=2.0 ft3/s, SE30,10=0.8 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 3.3 3.4 3.7 4.1 4.5 5.9 7.9 12 25 77

5 1.1 1.1 1.3 1.5 1.7 2.3 3.6 5.0 9.8 46

10 .5 .5 .7 .8 .9 1.3 2.3 3.2 6.1 36

20 .2 .3 .4 .4 .5 .8 1.7 2.3 4.2 29

50 .1 .1 .2 .2 .2 .4 1.1 1.6 2.8 24

Streamflow and Lake Level Characteristics  79
80 Hydrology of Polk County, Florida

Table 12. Low-flow frequency statistics for Tiger Creek near Babson Park.

[Site 73, figure 56. Period of record analyzed was water years 1992-2003. SEx,y, standard error of the x-day annual minimum flow 

with a y-year recurrence interval. Accuracy, SE7,2=1.5 ft3/s, SE7,10=1.3 ft3/s, SE30,2=1.8 ft3/s, SE30,10=1.6 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 11 11 11 12 13 15 18 21 27 38

5 7.8 7.8 8.0 8.5 8.8 11 13 15 20 31

10 6.4 6.4 6.6 6.9 7.2 9.0 11 13 17 28

20 5.3 5.4 5.5 5.9 6.1 7.7 9.7 11 15 25

50 4.3 4.4 4.5 4.8 5.0 6.4 8.1 9.3 13 22

Table 13. Low-flow frequency statistics for Peace River at Bartow.

[Period of record analyzed: water years 1984-2003. SEx,y, standard error of the x-day annual minimum flow with a y-year 

recurrence interval. Accuracy, SE30,2=4.5 ft3/s, SE30,10=0.8 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 3.6 3.7 3.8 5.5 6.2 7.5 11 14 31 108

5 1.8 1.8 1.9 .7 .8 2.1 3.7 5.3 12 60

10 .0 0 0 0 0 .7 1.8 3.1 7.6 46

20 0 0 0 0 0 0 1.0 2.0 5.2 37

50 0 0 0 0 0 0 .4 1.2 3.4 29

Table 14. Low-flow frequency statistics for Peace River at Fort Meade.

[Period of record analyzed: water years 1985-2003. SEx,y, standard error of the x-day annual minimum flow with a y-year 

recurrence interval. Accuracy, SE7,2=1.4 ft3/s, SE7,10=0.2 ft3/s, SE30,2=3.7 ft3/s, SE30,10=0.7 ft3/s]

Recurrence 

interval 

(in years)

Annual minimum low flow, in cubic feet per second, 

for the indicated number of consecutive days

1 2 3 7 10 30 60 90 183 365

(annual mean)

2 2.2 2.4 2.5 3.2 3.7 7.5 14 21 41 132

5 .5 .6 .6 .8 .9 1.9 4.3 6.3 13 76

10 .2 .2 .2 .3 .4 .8 2.0 3.1 7.0 59

20 .1 .1 .1 .1 .2 .3 1.0 1.6 4.0 48

50 .04 .04 .04 .1 .1 .1 .4 .7 2.1 39
system (Sacks and others, 1998; Lee and Swancar, 1997); 

most of the inflow occurs near the shoreline (Lee, 2000). Most 

seepage lakes can be further classified as flow-through lakes, 

where ground water flows in along part of the lake perimeter, 

and lake water leaks to the ground water laterally along the 

remainder of the lake perimeter. The percentage of the lake 

perimeter that exhibits ground-water inflow or outflow varies 

between lakes and by season (Sacks and others, 1998). The 

direction of lateral ground-water outflow from lakes does 

not necessarily parallel the basin topography. For example, 

lateral ground-water outflow from Lake Starr (site 42, fig. 56, 

app. 3) occurred in topographically higher parts of the lake 

basin, which was attributed to preferential flow toward karstic 

features (Swancar and others, 2000). In the deeper parts of the 

lake bottom, water typically flows vertically to recharge the 

Upper Floridan aquifer.

Transient water-table mounding was observed near 

the shoreline of seepage lakes in Polk County and also may 

affect lake levels. Lee and others (1991) and Swancar and 

others (2000) observed transient water-table mounds near 

Lake Lucerne and Lake Starr. Transient water-table mounding generally was short in duration, and generally lasted less 

than 1 day at Lake Starr (Swancar and others, 2000). Lee 

(1996) used a ground-water flow model combined with an 

independent water budget to document the effects of transient 

ground-water mounds on ground-water inflow to Lake Barco, 

a seepage lake in a ridge setting in Putnam County—located 

about 80 miles north of Polk County. Transient water-table 

mounds sometimes reversed ground-water flow directions 

on outflow sides of lakes, resulting in greater ground-water 

inflow and less lateral ground-water outflow. The generation 

of net ground-water inflow (defined as ground-water inflow 

minus ground-water outflow) to the lake that originated 

from transient water-table mounding was usually the result 

of a single large rainfall event, rather than a succession of 

small events.

The ground-water catchment areas for seepage lakes in 

Polk County are probably substantially smaller than the topographic drainage basins (Sacks and others, 1998; Lee, 2002). 

For example, Swancar and Lee (2003) simulated a catchment 

area for Lake Starr that was only 16 percent of the topographic 

drainage. At Lake Barco, the simulated catchment area was 

determined to be 2.4 hectares compared to the topographic 

basin of 81 hectares (Lee, 1996).

Regulation of Lake Levels

Water levels of some lakes in Polk County are controlled 

by flood-control structures or are influenced by other lakes 

connected to them. Forty-two of the 262 named lakes (16 

percent) in Polk County inventoried by Gant (2001) were 

reported to have a control structure on the outlet. There are 

two large chains of lakes connected by canals in the vicinity of 

Winter Haven—the Lake Hamilton and Winter Haven Chain 

of Lakes (fig. 62). The Lake Hamilton Chain of Lakes consists 

of seven interconnected lakes—Lake Haines, Lake Rochelle, 

Lake Conine, Lake Smart, Lake Fannie, Lake Henry, and Lake 

Hamilton. Four control structures regulate the flow of water 

between lakes in this system—P-5 (located on Lake Henry), 

P-6 (located on Lake Smart), P-7 (located on Lake Fannie), 

and P-8 (located on Lake Hamilton) (Southwest Florida Water 

Management District, 2002). The Winter Haven Chain of 

Lakes consists of 13 interconnected lakes—Lake Mariana, 

Lake Jessie, Lake Idylwild, Lake Hartridge, Lake Cannon, 

Lake Mirror, Lake Deer, Lake Howard, Lake May, Lake 

Shipp, Lake Eloise, Lake Winterset, and Lake Lulu. An outlet 

structure on Lake Lulu regulates the water levels in the lakes. 

Lakes Hartridge and Conine are connected by a canal. Locks 

in the canal permit the flow of water from Lake Hartridge 

to Conine during high water levels (U.S. Environmental 

Protection Agency, 2005). These lakes historically were not 

Table 15. Flood-flow frequency statistics for selected sites in Polk County.

[Locations of site numbers shown in figure 56. Units are cubic feet per second]

Site 

number Site

Recurrence interval, in years

2 5 10 25 50

72 Catfish Creek near Lake Wales 77 ± 5 112 ± 8 136 ± 11 168 ± 17 193 ± 26

66 Fox Branch near Socrum 256 ± 42 568 ± 101 862 ± 182 1 ,349 ± 363 1,803 ± 620

65 Green Swamp Run near Eva 52 ± 12 102 ± 23 142 ± 36 197 ± 61 242 ± 97

73 Tiger Creek near Babson Park 126 ± 10 157 ± 13 175 ± 16 195 ± 22 209 ± 30

75 Livingston Creek near Frostproof 244 ± 36 374 ± 63 471 ± 97 606 ± 161 716 ± 246

69 Peace Creek Drainage Canal near Wahneta 385 ± 66 658 ± 104 846 ± 145 1,083 ± 227 1,256 ± 345

68 Peace River at Bartow 913 ± 83 1,608 ± 159 2,168 ± 255 2,989 ± 447 3,683 ± 701

70 Peace River at Fort Meade 857 ± 96 1,375 ± 166 1,759 ± 249 2,286 ± 408 2,706 ± 614

71 Bowlegs Creek near Fort Meade 378 ± 46 557 ± 69 676 ± 96 827 ± 145 939 ± 209

Streamflow and Lake Level Characteristics  81
82  Hydrology of Polk County, Florida

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Withlacooche Ri e

e

v r

Peace v Ri er

Kissim

me ver e Ri

Saddle

Creek

Saddle

Creek

Lake

Hatchineha

Lake

Pierce

Lake

Marion

Lake Crago

Lake John

Lake Bentley

POLK COUNTY

LAKE

COUNTY

SUMTER

COUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

SJRWMD

SWFWMD

SFWMD

SWFWMD

SFWMD

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Base modified from

U.S. Geological Survey

digital data, 1:100,000, 1985

Universal Transverse

Mercator projection, zone 17

0 10 MILES

0 10

5

5 15 KILOMETERS

Lakeland

Polk City

Davenport

Dundee

Lake Wales

Bartow

Bradley

Junction

Fort Meade Frostproof

Winter

Haven

Auburndale

Lake

Alfred

Eagle

Lake

Highland

Park

Hillcrest

Heights

Lake

Hamilton

Haines

City

Mulberry

Mountain

Lake

Avon Park

Lake Louisa

State Park

Kissengen

Spring

HAINES CITY

WINTER HA DUNDEE VEN

Lake

Haines Lake

Henry

Lake

Hamilton

Lake

Mariana Lake

Rochelle

Lake

Cannon Lake

Howard

Lake

Lulu Lake

Eloise Lake

Winterset

Lake

Hartridge

Lake

Conine Lake

Smart

Lake

Fannie Lake

Jessie

Lake

Shipp

Lake

Mirror

Lake

Idylwild

Lake

Deer

Lake May

Figure 62. Location of Lake Hamilton and Winter Haven Chain of Lakes.
connected and occupied individual basins before construction of the canals. Within the Kissimmee River Basin, Lakes 

Hatchineha and Kissimmee have been regulated to maintain 

their stages between 48.5 and 54.0 ft NGVD 29, and Tiger 

Lake has been regulated to maintain the stage between 49.0 

and 52.5 ft NGVD 29 (U.S. Army Corps of Engineers, 1996). 

Lake levels in these three lakes historically were lowered 

from January through May to provide storage for wet-season 

precipitation (U.S. Army Corps of Engineers, 1996).

Lake levels vary seasonally in response to rainfall, 

evaporation, surface-water inflow and outflow, ground-water 

inflow and outflow, and ground-water pumpage. Water 

levels in most lakes in Polk County have seasonal variations 

similar to those in Lake Deeson (site 1, figs. 56 and 63). 

In Lake Deeson, lake levels generally were lowest from May 

through July and highest in September and October. Seasonal 

variations in lake levels, however, have deviated from this 

general pattern in any given year due to variations in rainfall 

or pumpage. For example, Sacks and others (1998) reported 

a steady decline in water levels in Saddle Blanket Lake 

(from January through December 1996) due to below normal 

rainfall during this period (fig. 64). Decreases in lake levels 

25TH PERCENTILE

MEDIAN

75TH PERCENTILE

123

124

125

126

127

128

LAKE LEVEL, IN FEET ABOVE NGVD 29

J F M A M J J A S O N D

Figure 63. Generalized seasonal 

variations in Lake Deeson, 1954-2003.

Figure 64. Seasonal variations in lake levels in Saddle 

Blanket Lake during a period 

of below normal rainfall.

Streamflow and Lake Level Characteristics  83

1996

SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. 115

116

117

118

119

120

LAKE LEVEL, IN FEET ABOVE NGVD29

JAN.

1995 1997
84  Hydrology of Polk County, Florida

measured in December 1995 during cold periods at Swim 

Lake (fig. 65), a 5-acre lake located within a citrus area on 

the Lake Wales Ridge, were attributed to increased pumpage 

from the Upper Floridan aquifer to protect citrus crops from 

frost damage (Sacks and others, 1998). Increased pumpage 

from the Upper Floridan aquifer results in an increased head 

difference between the lake and the aquifer, which induces 

more downward ground-water outflow from the lake.

Physical alteration of lakes in the county resulted in 

attenuated lake-level fluctuations in some lakes. Lake-level 

fluctuations were reduced in some lakes in the Kissimmee 

River Basin due to regulation by structure S-65. The lakes 

that compose the Winter Haven Chain of Lakes historically 

differed in surface-water elevations over a range of several 

feet; with the construction of the interconnecting canals in the 

1920s, however, these lakes now fluctuate at approximately 

the same elevation as Lake Lulu (Southwest Florida Water 

Management District, 2002). Reduced or eliminated waterlevel fluctuations were suggested by some investigators as 

a major cause of undesirable changes in lake and wetland 

communities in the Kissimmee River Basin (Perrin and 

others, 1982) because of accelerated accumulation of bottom 

sediments, declines in dissolved oxygen, nutrient enrichment, 

vegetation changes in the littoral zone, and the reduction of 

fish and wildlife populations.

Temporal Trends in Lake Levels

Temporal trends of lake levels in Polk County were 

examined to: (1) update previously published information on 

long-term temporal trends, and (2) quantify recent trends that 

may have occurred. Trends were computed for all lakes having 

sufficient data. Long-term temporal trends from generally the 

1960-2003 period were computed for 14 lakes (sites 1, 9, 27, 

MINIMUM

AIR TEMPERATURE

BELOW FREEZING

AIR

TEMPERATURES

LAKE LEVEL

1996

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

20

30

40

50

60

70

80

JUNE

95.0

95.5

96.0

96.5

97.0

97.5

98.0

98.5

LAKE LEVEL, IN FEET ABOVE NGVD29

MINIMUM DAILY AIR TEMPERATURE, IN DEGREES FARENHEIT

1995

Figure 65. Seasonal variations in lake levels and the minimum daily air temperatures at a lake (Swim Lake) affected by 

ground-water pumpage.
35, 37, 43-44, 56, 58-59, 61-64; fig. 56). These were the only 

lakes with sufficient data to compute temporal trends during 

this period. Temporal trends were computed for the 1960-2003 

period to facilitate comparisons of trends among the lakes. 

Recent trends were quantified for 71 lakes during the 1990-

2003 period. Three of the lakes (Scott Lake, Lake Hamilton, 

and Lake Hancock, sites 9, 61, and 63, respectively) had 

data only from 1960-2002. These sites were included in the 

analyses because there were few lakes that had data extending 

back to 1960.

Lake levels during 1960-2003 declined in 5 of the 14 

lakes (table 16, fig. 66). Most of these lakes are located along 

the Lake Wales Ridge. One-half of the 14 lakes had no trend 

in lake levels during this period; water levels in most of these 

lakes are regulated by a control structure or by a connection to 

another lake. Two of the lakes, Lake Mariana and Scott Lake 

(sites 27 and 9, fig. 56, app. 3), had increases in lake levels. It 

is unknown whether increasing water levels in Lake Mariana 

are related to changes in the regulation of the control structure 

on the lake’s outlet or some other factor. The increasing 

trend in Scott Lake seems to be related to the fact that low 

water levels were reported in the late 1960s and early 1970s, 

although the cause of the low levels is unknown. Decreases 

in water levels at selected lakes along the Lake Wales Ridge 

have been reported by other investigators (Geraghy and Miller, 

1980; Barcelo and others, 1990) and were attributed to belownormal rainfall and ground-water pumpage.

Temporal trend analyses using data from 1990-2003 

show that almost 90 percent of the lakes had no significant 

change in water levels (fig. 67). Five of the lakes (Blue Lake, 

Crooked Lake, Lake Buffum, Lake Clinch, and Little Crooked 

Lake), located in the vicinity of Frostproof, had an increasing 

trend in water levels during this period. Most of these lakes 

were identified as having long-term declines in water levels, 

which indicate that a reversal in lake-level trends may be 

occurring. Possible reasons for the increase in water levels 

include a reduction in ground-water pumpage in the area or 

increased rainfall during 1990-2003. The increase in water 

levels likely is not due to increased rainfall. Annual totals at 

the Avon Park, Lakeland, and Mountain Lake rainfall stations 

maintained by NOAA and the West Frostproof station maintained by the SWFWMD had no significant trends during this 

period (tau = 0.3407, p = 0.1005; tau = 0.3077, p = 0.1388; 

tau = 0.1429, p = 0.5112; and tau = 0.2747, p = 0.1889; 

respectively).

Factors Controlling Lake Levels

Reported declines in lake levels have resulted in several 

investigations of the factors that control lake levels in 

Polk County and in other parts of Florida (Lee and others, 

1991; Lee and Swancar, 1997; Sacks and others, 1998; 

Lee, 2000; Swancar and others, 2000; Lee, 2002; Metz and 

Table 16. Temporal trends in mean annual water levels for selected lakes in 

Polk County, 1960-2003. 

[Locations of site numbers shown in figure 56. Bolded values indicate a statistically 

significant trend]

Site 

number Lake name Period of record analyzed

Kendall’s

 tau p-value

58 Lake Clinch 1960-2003 -0.2812 0.0071

44 Lake Parker 1960-2003 .1501 .1509

56 Crooked Lake 1960-2003 -.4017 .0001

61 Lake Hamilton 1960-2002 .0122 .9084

9 Scott Lake 1960-2002 .2918 .0052

64 Mountain Lake 1960-1986, 1989-1999,

2000-2003

-.5282 .0000

63 Lake Hancock 1960-2002 .0808 .4449

37 Lake Howard 1960-2003 .1067 .3070

27 Lake Mariana 1960-2003 .9784 .0003

1 Lake Deeson 1960, 1965-2003 .1667 .1299

35 Lake Otis 1960-2003 -.0761 .4665

59 Reedy Lake 1960-2003 .0878 .4187

62 Lake Marion 1960-1993, 1998, 

2001-2003

-.2319 .0404

43 Lake Wales 1960-2003 -.2902 .0075

Streamflow and Lake Level Characteristics  85
86  Hydrology of Polk County, Florida

Sacks, 2002; Sacks, 2002). Water budgets were developed 

for eight lakes in Polk County to determine the relative 

importance of precipitation, evaporation, and ground-water 

inflow and outflow on lake stage (Lee and others, 1991; Lee 

and Swancar, 1997; Sacks and others, 1998; and Swancar 

and others, 2000). Ground-water inflow was quantified 

at about 40 seepage lakes on the Winter Haven and Lake 

Wales Ridges (Sacks and others, 1998; Sacks, 2002). Three 

modeling studies (Lee and Swancar, 1997; Lee, 2002; and 

Swancar and Lee, 2003) examined the relative importance of 

the factors controlling ground-water exchange with lakes.

Rainfall and evaporation generally accounted for more 

than one-half of either the total annual inflow or outflow in most 

of the studied lakes. Ground-water inflow and outflow, however, 

generally were not negligible components of the annual water 

budget. Ground-water inflow accounted for 47 percent, on 

average, of the total annual inflow in 32 lakes studied by Sacks 

(2002). Ground-water outflow accounted for 39 percent, on 

average, of the total outflow from Lake Lucerne (Lee and 

Swancar, 1997) and the seven lakes studied by Sacks (2002).

Ground-water inflow varied substantially among lakes 

and also seasonally in Polk County. Sacks (2002) reported that 

ground-water inflow to lakes located in Polk County ranged 

from 7 percent of the annual total inflows to Grassy Lake 

(site 23, fig. 56, app. 3) to 83 percent in Lake Josephine. Most 

of the lakes studied in Polk County were rated as receiving 

POLK COUNTY

LAKE COUNTY

SUMTERCOUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

B a s e m o d ifie d fro m U .S . G e o lo g ic a l S u rv e y d ig ita l d a ta , 1 :1 0 0 ,0 0 0 , 1 9 8 5 U n iv e rs a l Tra n sv e rs e Me rc a to r p ro je c tio n , z o n e 1 7 0 10 MILES

0 10

5

5 15 KILOMETERS

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

Lakeland

Polk City

Davenport

Lake Wales

Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Withla c oo c he R i e

e

v r

Pe ac e v R i e r

EXPLANATION

INCREASING TREND

DECREASING TREND

NO TREND

Figure 66. Temporal trends in lake levels in Polk County, Florida, 1960-2003.
medium to high amounts of ground-water inflow compared 

to other regions of west-central Florida (Sacks, 2002). Sacks 

and others (1998) and Swancar and others (2000) reported that 

net ground-water inflow varied seasonally in seepage lakes. 

The lakes generally had positive net ground-water flow during 

months with higher rainfall (typically June-September), and 

negative net ground-water flow during drier months.

Several factors affect ground-water exchange with 

lakes. Lateral ground-water inflow and outflow to the lake is 

affected by the head gradients between the surficial aquifer 

system and the lake. Additional ground-water inflow into 

a lake may be induced by temporary increases in the head 

gradient due to water-table mounding or artificially lowering the lake level by pumpage. Ground-water inflow to a 

lake also may be affected by the amount of recharge to the 

surficial aquifer system. The potential for a lake to receive 

ground-water inflow also may be affected by the depth of a 

lake. A deeper lake potentially receives more ground-water 

inflow compared to a shallower lake because the deeper lake 

intercepts a larger portion of the surficial aquifer system. 

More lateral ground-water inflow, however, may be received 

by a smaller lake relative to its surface area, compared to a 

large lake, because the smaller lake has a larger ratio of lake 

perimeter to surface area.

POLK COUNTY

LAKE COUNTY

SUMTERCOUNTY

HILLSBOROUGH COUNTY PASCO COUNTY

HARDEE COUNTY HIGHLANDS COUNTY

MANATEE

COUNTY

OSCEOLA

COUNTY

ORANGE

COUNTY

Lake

Weohyakapka

Lake

Rosalie

Crooked

Lake

Lake

Hancock

Wi o thlac och

r

ee Rive

Pe a c e R iver

B a s e m o d ifie d fro m U .S . G e o lo g ic a l S u rv e y d ig ita l d a ta , 1 :1 0 0 ,0 0 0 , 1 9 8 5 U n iv e rs a l Tra n sv e rs e Me rc a to r p ro je c tio n , z o n e 1 7 0 10 MILES

0 10

5

5 15 KILOMETERS

82°00′ 45′ 30′ 81°15′

28°15′

28°00′

27°45′

EXPLANATION

INCREASING TREND

DECREASING TREND

NO TREND

PRECIPITATION GAGE

Lakeland

Polk City

Davenport

Lake Wales Bartow

Winter

Haven

Mulberry

Avon Park

Fort Meade

Kissim

me ver e Ri

Figure 67. Temporal trends in lake levels in Polk County, Florida, 1990-2003.

Streamflow and Lake Level Characteristics  87
88  Hydrology of Polk County, Florida

Summary

The hydrogeology, ground-water quality, and streamflow 

and lake level trends and characteristics of Polk County, Florida, 

were evaluated during a 31⁄2-year study from 2002 to 2006. 

The study area encompasses about 1,823 square miles in 

central Florida. Rapid increases in population have occurred 

in Polk County since the 1960s and this trend is expected to 

continue. From 1960 to 2004, the population increased from 

about 195,000 to 528,000, making it the tenth largest county 

in terms of population in the State. The population in Polk 

County is projected to reach about 676,000 by 2020.

Ground-water use has decreased substantially since 

1965. In 1965, total ground-water withdrawals in Polk County 

were about 350 million gallons per day. In 2002, withdrawals 

totaled about 285 million gallons per day, of which nearly 

95 percent was from the Floridan aquifer system. Waterconservation practices related to the phosphate-mining industry 

have helped reduce total water use by about 65 million gallons 

per day since 1965. Of the total ground-water use in 2000, 

48 percent was for agricultural irrigation, 23 percent for public 

supply, 21 percent for commercial/industrial self-supplied, 

4 percent for domestic self-supplied, 3 percent for recreation, 

and 1 percent for thermoelectric power generation.

Three principal water-bearing units underlie Polk County. 

The uppermost water-bearing unit is the surficial aquifer 

system. The surficial aquifer system is underlain by the intermediate confining unit or by the intermediate aquifer system. The 

lowermost hydrogeologic unit is the Floridan aquifer system.

The surficial aquifer system is unconfined and consists 

of unconsolidated clastic deposits that range in age from 

Pliocene to Holocene. The unit is composed primarily of 

fine- to medium-grained quartz sand near the land surface 

that grades with depth to silty and clayey sands. The lithology and texture of the sediments within the surficial aquifer 

system can vary considerably both vertically and laterally. 

Thickness of the surficial aquifer system is highly variable, 

ranging from several feet or less in extreme northwestern 

Polk County and along parts of the Peace River south of 

Bartow, to more than 200 feet along the southern part of the 

Lake Wales Ridge in eastern Polk County. The water table 

in the surficial aquifer system fluctuates about 1 to 5 feet 

seasonally. The hydraulic properties of the surficial aquifer 

system vary considerably across the county and are dependent 

largely upon aquifer thickness, grain-size distribution, sorting, 

packing, and cementation of the sediments within the aquifer. 

Transmissivity estimates from surficial aquifer wells ranged 

from 8 to 2,400 foot squared per day. Ground water in the 

surficial aquifer system is recharged primarily by the infiltration of rainfall. The surficial aquifer provides small amounts 

of water for lawn irrigation and domestic use.

The intermediate confining unit is present throughout 

much of the northern and eastern parts of Polk County. The 

intermediate confining unit serves as a confining layer (except 

where breached by sinkholes) that restricts the vertical movement of water between the surficial aquifer system and the 

underlying Upper Floridan aquifer. The unit consists mostly 

of interbedded clay, silt, phosphate, and sand, but includes 

some limestone and dolostone of the Hawthorn Group. In 

many areas, the intermediate confining unit also can include 

low-permeability clay and silt layers of early Pliocene age. 

Thickness of the intermediate confining unit generally ranges 

from less than 25 feet in northern Polk County to more than 

200 feet in southeastern Polk County. The unit is locally thin 

or absent in extreme northwestern Polk County.

The intermediate aquifer system is present in southwestern Polk County, where the intermediate confining unit grades 

into more permeable sediments of the Peace River and Arcadia 

Formations. These deposits are a source of water supply and 

have sufficient permeability to warrant being referred to as 

an aquifer system. The intermediate aquifer system includes 

all water-bearing and confining units between the base of 

the surficial aquifer system to the top of the Floridan aquifer 

system. As a whole, however, the entire system, including the 

water-bearing units, restricts vertical movement of ground 

water between the overlying surficial aquifer system and 

underlying Upper Floridan aquifer. Thickness of the intermediate aquifer system generally ranges from nearly zero, where 

the permeable zones pinch out in central Polk County, to more 

than 300 feet in southwestern Polk County.

In Polk County, two water-bearing zones are present in 

the intermediate aquifer system. Investigations of these zones 

indicated that they are limited in vertical extent and are present 

at variable depths. The uppermost hydrogeologic zone (Zone 2) 

is the most extensive aquifer within the intermediate aquifer 

system in Polk County, and is present throughout much of the 

southwestern part of the county. The lowermost water-bearing zone (Zone 3) is found only in the extreme south-central 

part of Polk County. Data on the hydraulic properties of the 

intermediate aquifer system in Polk County are limited, and 

values vary considerably because of the variable nature of the 

lithology. Transmissivity estimates for the permeable zones of 

the intermediate aquifer system in Polk County ranged from 

160 to 13,330 feet squared per day. The intermediate aquifer 

system is a minor source of water supply. About 3 percent of 

the total ground water used in Polk County is withdrawn from 

the intermediate aquifer system for domestic, industrial, and 

irrigation uses.

The Floridan aquifer system is subdivided into two 

aquifers, the Upper Floridan aquifer and Lower Floridan 

aquifer. In Polk County, the Upper Floridan aquifer contains 

freshwater and the Lower Floridan aquifer contains more 

mineralized water. These aquifers are separated by a lesspermeable middle semiconfining unit and middle confining 

unit, both of which restrict the vertical movement of water. 

The Upper Floridan aquifer can be further subdivided into 

two separate zones of different permeabilities. The Upper 

Floridan aquifer system consists primarily of limestone and 

dolostone of Eocene to Oligocene age. The altitude of the top 

of the Upper Floridan aquifer ranges from about 50 feet above 

NGVD 29 in the northwestern part of the county to more 
than 250 feet below NGVD 29 in the southern part. In a few 

areas in extreme northwestern Polk County, the aquifer is at 

or within a few feet of land surface. Transmissivity estimates 

for the Upper Floridan aquifer in the Polk County area range 

from about 3,500 to 468,000 feet squared per day. The Upper 

Floridan aquifer provides most of the water-supply demands in 

Polk County.

The potentiometric surface of the Upper Floridan aquifer 

system fluctuates, mainly in response to seasonal variations 

in rainfall and ground-water withdrawals. In September 2003, 

the altitude of the potentiometric surface of the Upper Floridan 

aquifer ranged from about 44 to 130 feet above NGVD 29. 

Potentiometric surface altitudes in May 2004 were about 1.5 to 

17 feet lower than those measured in September 2003.

Water levels in the Upper Floridan aquifer also can 

change from year to year, depending on such factors as pumpage and climatic variations. Long-term trends of water levels 

in the southwestern part of the county show that fluctuations 

in water use related to phosphate mining have had a major 

impact on water levels in the area. Hydrographs of selected 

wells in southwestern Polk County show a general decline 

in water levels that ended in the mid-1970s. This water-level 

decline coincided with an increase in water use associated 

with phosphate mining. A significant rise in water levels 

that began in the mid-1970s coincided with a period when 

pumping associated with the phosphate industry declined. 

In addition to a decrease in pumping, an increase in rainfall 

during this same period also may be responsible for some of 

the increase in water levels.

Since predevelopment times, the increase in pumping 

in and near the study area has resulted in a decline of the 

potentiometric surface of the Upper Floridan aquifer across 

much of the county. The approximate decline in the potentiometric surface of the Upper Floridan aquifer is based on the 

difference between the estimated predevelopment potentiometric surface map and the water levels of wells measured in 

May and September and averaged from 2000 to 2004. In the 

southwestern part of the county, where large withdrawals for 

industrial use have occurred, declines in water levels ranged 

from about 15 to as much as 40 feet. In the eastern and 

west-central parts of the county, water levels have declined 

from greater than 0 to 15 feet. In the northwestern part of the 

county, an area that has not been impacted by pumping, little 

or no change in water levels has occurred.

Ground-water quality was assessed by sampling 

53 wells and one spring and by compiling data collected 

from 76 additional wells by State and other Federal agencies. Inorganic constituents were the focus of water-quality 

analysis. Concentrations of dissolved solids, sulfate, and 

chloride in water samples from the surficial and intermediate aquifer systems generally were below State and Federal 

drinking-water standards. Nitrate concentrations, however, 

were elevated (as high as 26 milligrams per liter (mg/L)) in 

the surficial aquifer system along the Lake Wales Ridge. The 

application of fertilizers related to citrus farming is a likely 

source of nitrate to the ground water in this area.

Water in the Upper Floridan aquifer is typically a calcium 

bicarbonate water type, resulting from the dissolution of 

the carbonate rock. Inorganic constituent concentrations in 

water from the Floridan aquifer system generally were below 

State and Federal drinking-water standards. Water from the 

Upper Floridan aquifer in most of the county is hard and has a 

dissolved-solids concentration of less than 500 mg/L. Chloride 

concentrations in water from the Upper Floridan aquifer range 

from 4.2 to 61 mg/L, and sulfate concentrations range from 

about 0.2 to 44 mg/L. In contrast to results from the surficial 

aquifer system, nitrate concentrations in the Upper Floridan 

aquifer generally were low and exceeded 1.0 mg/L in only 

three wells. Lower nitrate concentrations in the Upper Floridan 

aquifer suggest that denitrification may be occurring as ground 

water moves downward, but also may be due to dilution.

Chloride concentrations less than 250 mg/L extend to 

considerable depths in the Floridan aquifer system. The thickest section where chloride concentrations are less than 250 

mg/L is along the Lake Wales Ridge. The altitude of the top 

of the 250-mg/L isochlor surface in this area is estimated to 

be about 2,400 feet below NGVD 29. The estimated position 

of the 250-mg/L isochlor surface is less than 1,200 feet below 

NGVD 29 in the extreme southeastern part of the county. 

The depth of the chloride isochlor surface, however, may not 

accurately portray the thickness of the freshwater zone. The 

limited data available indicate that within and beneath the 

middle confining unit, dissolved-solids concentrations may 

be high not because of chloride, but because of high sulfate 

concentrations.

Low-flow and flood-flow frequency statistics were 

updated in this study based on data collected by the USGS 

through 2003. A shorter period of record was used to compute 

frequency statistics for the Peace River at Bartow, Peace River 

at Fort Meade, and Catfish Creek near Lake Wales due to 

temporal trends in the streamflow data. Frequency statistics at 

these sites were computed to represent 2003 conditions.

The Kissimmee River within Polk County has been 

regulated for flood-control purposes as part of the Central and 

South Florida Flood Control Project. The entire stream was 

channelized from 1962 to 1971. These changes have resulted 

in alteration of the hydrologic characteristics of the stream. 

The seasonal variation in streamflows has changed substantially. Based on data from water years 1979-2003, the greatest 

streamflows for the Kissimmee River generally occurred from 

January through May and in August. In contrast, streamflows 

generally are greatest in September and October and least 

in May and June in all other streams in the county. Further 

changes in the hydrology of the Kissimmee River in Polk 

County may occur in the future because the flood-control 

project in the Kissimmee Basin is being modified by the State 

of Florida and the Federal Government, in part to re-establish 

the historic hydrologic conditions in the basin.

The declines measured in the potentiometric surface of 

the Upper Floridan aquifer also have been expressed in some 

of the surface-water resources of the county as well. The 

section of the Peace River within the county formerly was a 

Summary  89
90 Hydrology of Polk County, Florida

gaining stream, which received springflow from Kissengen 

Spring and ground-water inflow from the Floridan aquifer 

system. This part of the Peace River is now classified as a 

losing stream. Kissengen Spring has not flowed since 1960, 

and the Floridan aquifer system no longer contributes groundwater inflow to the river. Several studies also have been 

published documenting long-term declines in streamflow in 

the Peace River and in the water levels of selected lakes.

Temporal trends in streamflow in the Peace River were 

updated in this study using data through 2003. The analyses 

also were expanded by analyzing trends over a wider range 

of the hydrologic regime and over 15 multidecadal periods. 

The results indicated that annual minimum to 70th percentile 

streamflows in the Upper Peace River began to decline in the 

1950s, and that this decline in streamflows has persisted to 

2003. Results also showed a statistically significant decrease 

in annual minimum streamflows in the Peace River at Bartow 

from 1974 to 1993. This decrease may be due to elimination 

of wastewater discharges to the river during the mid-1980s.

The lakes in Polk County exchange water with the 

ground-water system. Direct runoff from the land surface, 

with the exception of stormwater runoff in urban areas, is 

considered to be minimal because of the high permeability 

of the sandy soils in the area. Most of the seepage lakes are 

classified as flow-through lakes, where ground-water inflows 

along part of the lake perimeter and outflows laterally along 

the remainder. The percentage of the lake perimeter receiving 

ground-water inflow varies among lakes and from season to 

season.

Water levels in lakes in the county vary seasonally. Water 

levels generally are lowest in May and greatest in September 

and October. There may, however, be deviations from this 

general pattern due to variations in rainfall or pumpage. 

Transient water-table mounding also has been observed near 

the shoreline of seepage lakes in the county and may affect 

lake levels. Observed water-table mounding generally was 

short in duration. At Lake Starr, water-table mounds generally 

lasted less than 1 day.

Temporal trends in lake levels were analyzed to describe 

long-term trends (1960-2003) and trends that occurred from 

1990-2003. About 90 percent of the lakes had no change in 

water levels from 1990-2003. Five of the lakes had an increasing trend in water levels. The increase in water levels likely is 

not due to increased rainfall. Annual totals at nearby rainfall 

stations had no significant trends during this period.
Selected References

Adamski, J.C., and German, E.R., 2004, Hydrology and 

quality of ground water in Orange County, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

03-4257, 113 p.

Aucott, W.R., 1988, Areal variation in recharge to and 

discharge from the Floridan aquifer system in Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

88-4057, 1 sheet.

Anderson, Warren, and Simonds, E.P., 1983, Hydrology of 

Hamilton Lake and vicinity, Polk County, Central Florida: 

U.S. Geological Survey Open-File Report 82-630, 1 sheet.

Arthur, J., Fischler, C., Kromhout, C., Clayton, J., Kelley, M., 

Lee, R., Li, L., O’Sullivan, M., Green, R., and Werner C., 

2007, Hydrogeologic framework of the Southwest Florida 

Water Management District: Tallahassee, Florida Geological 

Survey Bulletin 68.

BCI, 2000, Reclamation and mitigation of the Upper 

Peace River watershed at the Tenoroc Fish Management 

Area—Task 1, restoration approach and identification 

of work elements: Prepared for the Florida Department 

of Environmental Protection, the U.S. Army Corps of 

Engineers, and the Southwest Florida Water Management 

District, 95 p.

Barcelo, Mark, and Basso, Ron, 1993, Computer model 

of ground-water flow in the Eastern Tampa Bay Water 

Use Caution Area: Brooksville, Southwest Florida Water 

Management District, 102 p.

Barcelo, M.D., Slonena, D.L., Camp, S.C., and Watson, 

J.D., 1990, Ridge II: A hydrogeologic investigation of the 

Lake Wales Ridge: Brooksville, Southwest Florida Water 

Management District Technical Report, 130 p.

Barr, G.L., 1992, Ground-water contamination potential and 

quality in Polk County, Florida: U.S. Geological Survey 

Water-Resources Investigations Report 92-4086, 92 p.

Basso, Ron, 2003, Predicted change in hydrologic conditions 

along the Upper Peace River Basin due to a reduction in 

ground-water withdrawals: Brooksville, Southwest Florida 

Water Management District, 53 p.

Basso, Ron, and Hood, Jill, 2005, Assessment of minimum 

levels for the intermediate aquifer system in the Southwest 

Florida Water Management District: Brooksville, Southwest 

Florida Water Management District, 217 p.

Basso, Ron, and Schultz, Richard, 2003, Long-term variation 

in rainfall and its effect on Peace River flow in west-central 

Florida: Brooksville, Southwest Florida Water Management 

District, 33 p.

Blanchard, R.A., Seidenfeld, A.V., and McCulloch, D.S., 

2004, Potentiometric surface of the Upper Floridan aquifer, 

west-central Florida, September 2003: U.S. Geological 

Survey Open-File Report 2004-1314, 1 sheet.

Blanchard, R.A., Seidenfeld, A.V., and McCulloch, D.S., 

2004, Potentiometric surface of the Upper Floridan aquifer, 

west-central Florida, May 2004: U.S. Geological Survey 

Open-File Report 2004-1399, 1 sheet.

Boyle Engineering Corporation, 1995, Hydrogeologic 

report—Orange County southern regional wellfield: 

Consultant’s report prepared for Orange County Public 

Utilities Commission, Orange County, Florida, Report 

OR-003-305-01.

Bradbury, K.R., Bartos, L.F., and Richters, D.F., 1978, 

Hydrology and limnology of Crooked Lake near Babson 

Park, Florida: Brooksville, Southwest Florida Water 

Management District Environmental Section Technical 

Report 1978-1, 47 p.

Bush, P.W., and Johnston, R.H., 1988, Ground-water 

hydraulics, regional flow, and ground-water development 

of the Floridan aquifer system in Florida and in parts of 

Georgia, South Carolina, and Alabama: U.S. Geological 

Survey Professional Paper 1403-C, 80 p.

Campbell, K.M., 1986, Geology of Polk County, Florida: 

Tallahassee, Florida Geological Survey Open-File Report 

13, 18 p.

Carr, W.J., and Alverson, D.C., 1959, Stratigraphy of middle 

Tertiary rocks in parts of west-central Florida: U.S. 

Geological Survey Bulletin 1092, 111 p.

CH2MHILL, 1989, Wastewater management program for 

the 1,000-acre site: Consultant’s report prepared for Reedy 

Creek Improvement District, Lake Buena Vista, Florida.

CH2MHILL, 2005, Construction and testing of well F at the 

Southlake Utilities water treatment facility site: Consultant’s 

report prepared for Southlake Utilities, Lake County, 

Florida.

Charlotte Harbor National Estuary Program, 2000, 

Committing to the future—A comprehensive conservation 

and management plan for the greater Charlotte Harbor 

watershed, v. 1: Charlotte Harbor National Estuary 

Program, North Fort Myers, Florida, 272 p.

Choquette, A.F, and Sepúlveda, A.A., 2000, Design of a 

shallow ground-water network to monitor agricultural 

chemicals, Lake Wales Ridge, Central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

00-4134, 35 p.

Choquette, A.F, Turner, R.D., Haber, J.D., Lucas, P.A., 

and Daiker, D.H., 2005, Temporal variability of agricultural chemicals in ground water and implications for 

water-quality sampling, in Proceedings of the Annual 

Tennessee Water Resources Symposium, April 2005, 

Burns, Tennessee: American Water Resources Association, 

p. 2B6-2B14.

City of Lakeland, 2001, City of Lakeland lakes water quality 

report, 1988-2000: Public Works Department, Florida, 

37 p.

Selected References  91
92  Hydrology of Polk County, Florida

Cooke, W.C., 1945, Geology of Florida: Tallahassee, Florida 

Geological Survey Bulletin 29, 339 p.

Crandall, C.A., and Berndt, M.P., 1996, Water quality of 

surficial aquifers in the Georgia-Florida Coastal Plain: 

U.S. Geological Survey Water-Resources Investigations 

Report 95-4269, 28 p.

Davis and Associates, 1981, Application and technical report 

for disposal well no. 2: Consultant’s report prepared for the 

Kaiser Aluminum and Chemical Corporation, Mulberry 

Plant, Polk County, Florida, 32 p.

Dietrich, T.S., 1978, The urbanization of Florida’s population: 

An historical perspective of county growth 1830-1970: 

Gainesville, University of Florida, Bureau of Economic and 

Business Research.

Duerr, A.D., and Enos, G.M., 1991, Hydrogeology of the 

intermediate aquifer system and Upper Floridan aquifer, 

Hardee and DeSoto Counties, Florida: U.S. Geological 

Survey Water-Resources Investigations Report 90-4104, 

46 p.

Duerr, A.D., Hunn, J.D., Lewelling, B.R., and Trommer, J.T., 

1988, Geohydrology and 1985 water withdrawals of the 

aquifer systems in southwest Florida with emphasis on 

the intermediate aquifer system: U.S. Geological Survey 

Water-Resources Investigations Report 87-4259, 115 p.

Enfield, D.B., Mestas-Nunez, A.M., and Trimble, P.J., 2001, 

The Atlantic multidecadal oscillation and its relation to 

rainfall and river flows in the continental U.S.: Geophysical 

Research Letters, v. 28, no. 10, p. 2077-2080.

Evans, M.W., Snyder, S.W., and Hine, A.C., 1994, Highresolution seismic expression of karst evolution within 

the Upper Floridan aquifer system, Crooked Lake, Polk 

County, Florida: Journal of Sedimentary Research, v. B64, 

p. 232-244.

Flannery, M.S., and Barcelo, M., 1998, Spatial and temporal 

patterns of streamflow trends in the Upper Charlotte Harbor 

watershed, in Proceedings of the Charlotte Harbor Public 

Conference and Technical Symposium: Charlotte Harbor 

National Estuary Program, Florida, Technical Report 98-02.

Florida Department of State, 1989, Rules of the Department of 

Environmental Regulation, public drinking water systems: 

Tallahassee, in Florida Administrative Code, chap. 17-550.

Florida Institute of Phosphate Research, 2006a, History of 

phosphate land reclamation in Florida [accessed 9/5/2006] 

http://www.fipr.state.fl.us/research-area-reclamation.

htm#History

Florida Institute of Phosphate Research, 2006b, 

Reclamation— Strategies and stages [accessed 9/5/2006] 

http://www1.fipr.state.fl.us/PhosphatePrimer/0/

764E773481EAD02A85256F790058D446

Gant, R.D., 1993, Directory of lakes within the Southwest 

Florida Water Management District—Lake levels program: 

Brooksville, Southwest Florida Water Management District, 

58 p.

Gant, R.D., 2001, Directory of lakes within the Southwest 

Florida Water Management District: Brooksville, Southwest 

Florida Water Management District, 61 p.

Gates, M.T., 2003, Hydrogeology of the ROMP 74x 

Davenport monitor well site, Polk County, Florida, phase 

1 core drilling and testing: Brooksville, Southwest Florida 

Water Management District, 58 p.

Gates, M.T., 2005, ROMP 74x Davenport, Polk County, 

Florida: Brooksville, Southwest Florida Water Management 

District, 28 p.

Geraghty and Miller, Inc., 1980, Highlands Ridge hydrologic 

investigation: Consultant’s report prepared for the Peace 

River Basin Board, Brooksville, Southwest Florida Water 

Management District, 142 p.

German, E.R., 1996, Analysis of nonpoint-source groundwater contamination in relation to land use: Assessment 

of nonpoint-source contamination in central Florida: U.S. 

Geological Survey Water-Supply Paper 2381-F, 60 p.

Grubb, H.F., 1978, Potential for downward leakage to the 

Floridan aquifer, Green Swamp area, central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

77-71, 1 sheet.

Grubb, H.F., Chappelear, J.W., and Miller, J.A., 1978, 

Lithologic and borehole geophysical data, Green Swamp 

area, Florida: U.S. Geological Survey Open-File Report 

78-574, 270 p.

Grubb, H.F., and Rutledge, A.T., 1979, Long-term water 

supply potential, Green Swamp area, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

78-99, 76 p.

Grubbs, J.W., 1995, Evaluations of ground-water flow and 

hydrologic budget for Lake Five-O, a seepage lake in northwestern Florida: U.S. Geological Survey Water-Resources 

Investigations Report 94-4145, 42 p.

Hammett, K.M., 1990, Land use, water use, streamflow characteristics, and water-quality characteristics of the Charlotte 

Harbor inflow area, Florida: U.S. Geological Survey WaterSupply Paper 2359-A, 64 p.

Hammett, K.M., and DelCharco, M.J., 2005, Estimating the 

magnitude and frequency of floods for streams in westcentral Florida, 2001: U.S. Geological Survey Scientific 

Investigations Report 2005-5080, 15 p.

Heath, R.C., 1961, Surface-water resources of Polk County, 

Florida: Tallahassee, Florida Geological Survey Information 

Circular 25, 123 p.
Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods 

in water resources: Techniques of Water-Resources Investigations of the United States Geological Survey, book 4, 

Hydrologic Analysis and Interpretation, chap. A3, 510 p.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological Survey 

Water-Supply Paper 2254, 263 p.

Hickey, J.J., 1990, An assessment of the flow of variablesalinity ground water in the middle confining unit of 

the Floridan aquifer system, west-central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

89-4142, 13 p.

Hutchinson, C.B., 1978, Appraisal of shallow ground-water 

resources and management alternatives in the upper Peace 

and eastern Alafia River basins, Florida: U.S. Geological 

Survey Water-Resources Investigations Report 77-124, 57 p.

Irwin, G.A., and Hutchinson, C.B., 1976, Reconnaissance 

water sampling for radium-226 in central and northern 

Florida, December 1974-March 1976: U.S. Geological 

Survey Water-Resources Investigations Report 76-103, 16 p.

Jackson, T.E., 2000, Report on the Kissengen Spring site 

near Bartow, Florida, and the potential for restoration of 

the spring flow: Brooksville, Southwest Florida Water 

Management District Technical Memorandum, 9 p.

Johnston, R.H., Krause, R.E., Meyer, F.W., Ryder, P.D., 

Tibbals, C.H., and Hunn, J.D., 1980, Estimated potentiometric surface for the Tertiary limestone aquifer system, 

southeastern United States, prior to development: U.S. 

Geological Survey Open-File Report 80-406, 1 sheet.

Kaufman, M.I., 1967, Hydrologic effects of ground-water 

pumpage in the Peace and Alafia River basins, Florida, 

1934-1965: Tallahassee, Florida Geologic Survey Report of 

Investigations 49, 32 p.

Kelly, Martin, 2004, Florida river flow patterns and the 

Atlantic multidecadal oscillation: Brooksville, Southwest 

Florida Water Management District, Ecologic Evaluation 

Section, 80 p.

Kinnaman, S.L., and Knowles, Leel, Jr., 2004a, Potentiometric 

surface of the Upper Floridan aquifer in the St. Johns River 

Water Management District and vicinity, Florida, September 

2003: U.S. Geological Survey Open-File Report 2004-1288, 

1 sheet.

Kinnaman, S.L., and Knowles, Leel, Jr., 2004b, Potentiometric 

surface of the Upper Floridan aquifer in the St. Johns River 

Water Management District and vicinity, Florida, May 

2004: U.S. Geological Survey Open-File Report 2004-1377, 

1 sheet.

Kite, G.W, 1977, Frequency and risk analyses in hydrology: 

Water Resources Publication, Fort Collins, Colorado, 224 p.

Knochenmus, D.D., 1976, Hydrology of Lake County: U.S. 

Geological Survey Water-Resources Investigations Report 

76-72, 99 p.

Knochenmus, L.A., 2006, Regional evaluation of the hydrogeologic framework, hydraulic properties, and chemical 

characteristics of the intermediate aquifer system underlying southern west-central Florida: U.S. Geological Survey 

Scientific Investigations Report 2006-5013, 52 p.

Knowles, Leel, Jr., O’Reilly, A.M., and Adamski, J.C., 2002, 

Hydrogeology and simulated effects of ground-water 

withdrawals from the Floridan aquifer system in Lake 

County and in the Ocala National Forest and vicinity, northcentral Florida: U.S. Geological Survey Water-Resources 

Investigations Report 02-4207, 140 p.

Koebel, J.W., Jr., 1995, A historical prospective on the 

Kissimmee River restoration project: Restoration Ecology, 

v. 3, p. 149-159.

LaMoreaux, P. E., and Associates, 1975a, Water resources 

evaluation for W.R. Grace and Company’s Hookers Prairie 

tract, Polk County, Florida.

LaMoreaux, P. E., and Associates, 1975b, Four corners mine, 

Hillsborough and Manatee Counties, Florida, application 

for development approval.

Leach, S.D., 1977, Estimated water-use inventory in Florida, 

1975: U.S. Geological Survey Open-File Report 77-577, 

57 p.

Lee, T.M., 1996, Hydrogeologic controls on the ground-water 

interactions with an acidic lake in karst terrain, Lake Barco, 

Florida: Water Resources Research, v. 32, no. 4, p. 831-844.

Lee, T.M., 2000, Effects of near-shore recharge on groundwater interactions with a lake in mantled karst terrain: Water 

Resources Research, v. 36, p. 2167-2182.

Lee, T.M., 2002, Factors affecting ground-water exchange and 

catchment size for Florida lakes in mantled karst terrain: 

U.S. Geological Survey Water-Resources Investigations 

Report 02-4033, 54 p.

Lee, T.M., Adams, D.B., Tihansky, A.B., and Swancar, Amy, 

1991, Methods, instrumentation, and preliminary evaluation of data for the hydrologic budget assessment of Lake 

Lucerne, Polk County, Florida: U.S. Geological Survey 

Water-Resources Investigations Report 90-4111, 42 p.

Lee, T.M., and Swancar, Amy, 1997, Influence of evaporation, 

ground water, and uncertainty in the hydrologic budget of 

Lake Lucerne, a seepage lake in Polk County, Florida: U.S. 

Geological Survey Water-Supply Paper 2439, 61 p.

Lewelling, B.R., 1987, Potentiometric surface of the intermediate aquifer system, west-central Florida, May 1987: U.S. 

Geological Survey Open-File Report 87-705, 1 sheet.

Lewelling, B.R., Tihansky, A.B., and Kindinger, J.L., 1998, 

Assessment of the hydraulic connection between ground 

water and the Peace River, west-central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

97-4211, 96 p.

Selected References  93
94  Hydrology of Polk County, Florida

Lewelling, B.R., and Wylie, R.W., 1993, Hydrology and water 

quality of unmined and reclaimed basins in phosphatemining areas, west-central Florida: U.S. Geological Survey 

Water-Resources Investigations Report 93-4002, 93 p.

Lichtler, W.F., Anderson, Warren, and Joyner, B.F., 1968, 

Water resources of Orange County, Florida: Tallahassee, 

Florida Geological Survey Report of Investigations 50, 150 p.

Long, H.W., Jr., and Orne, D.P., 1990, Regional study of land 

use planning and reclamation: Central Florida Planning 

Council, p. 77.

Mantau, N.J., Hare, S.R., Zhang, Yuan, Wallace, J.M., and 

Francis, R.C., 1997, A Pacific interdecadal climate oscillation with impacts on salmon production: Bulletin of the 

American Meteorological Society, v. 78, p. 1069-1079.

Marella, R.L., 1988, Water withdrawals, use, and trends in 

Florida, 1985: U.S. Geological Survey Water-Resources 

Investigations Report 88-4103, 43 p.

Marella, R.L., 2004, Water withdrawals, use, discharge, and 

trends in Florida, 2000: U.S. Geological Survey Scientific 

Investigations Report 2004-5151, 136 p.

McCabe, G.J., Palecki, M.A., and Betancourt, J.L., 2004, 

Pacific and Atlantic Ocean influences on multidecadal 

drought frequency in the United States: Proceedings of the 

National Academy of Sciences, USA, v. 101, p. 4136-4141.

McCabe, G.J., and Wolock, D.M., 2002, A step increase in 

streamflow in the conterminous United States: Geophysical 

Research Letters, v. 29, no. 24, p. 2185-2188.

McGurk, B., and Sego, J., 1999, Hydrologic data from a 

Lower Floridan test well, central Orange County, Florida: 

Palatka, St. Johns River Water Management District 

Technical Publication SJ99-SP8, 133 p.

McGurk, Brian, Burger, Patrick, and Toth, David, 2003, 

Three-dimensional mapping of salinity zones within 

the Floridan aquifer system in the St. Johns River Water 

Management District and adjoining areas, northeast Florida: 

National Ground Water Association National Ground 

Water Expo, Association of Ground Water Scientists and 

Engineers Symposium, Technical Interactive Presentation, 

Orlando, Florida, December 2003.

Menke, C.G., Meredith, E.W., and Wetterhall, W.S., 1961, 

Water resources of Hillsborough County, Florida: 

Tallahassee, Florida Geological Survey Report of 

Investigations 25, 101 p.

Menke, C.G., Meredith, E.W., and Wetterhall, W.S., 1964, 

Water-resources records of Hillsborough County, Florida: 

Tallahassee, Florida Geological Survey Information Circular 

44, 95 p.

Metz, P.A., 1995, Hydrogeology and simulated effects of 

ground-water withdrawals for citrus irrigation, Hardee and 

DeSoto Counties, Florida: U.S. Geological Survey WaterResources Investigations Report 93-4158, 83 p.

Metz, P.A., and Brendle, D.L., 1996, Potential for waterquality degradation of interconnected aquifers in westcentral Florida: U.S. Geological Survey Water-Resources 

Investigations Report 96-4030, 54 p.

Metz, P.A., and Sacks, L.A., 2002, Comparison of the 

hydrogeology and water quality of a ground-water 

augmented lake with two non-augmented lakes in northwest 

Hillsborough County, Florida: U.S. Geological Survey 

Water-Resources Investigations Report 02-4032, 74 p.

Miller, J.A., 1986, Hydrogeologic framework of the Floridan 

aquifer system in Florida and in parts of Georgia, 

South Carolina, and Alabama: U.S. Geological Survey 

Professional Paper 1403-B, 91 p., 33 plates.

Miller, R.L., and Sutcliffe, Horace, Jr., 1982, Water-quality 

and hydrogeologic data for three phosphate industry wastedisposal sites in central Florida, 1979-80: U.S. Geological 

Survey Water-Resources Investigations Report 81-84, 77 p.

Miller, R.L., and Sutcliffe, Horace, Jr., 1984, Effects of three 

phosphate industrial sites on ground-water quality in central 

Florida, 1974 to 1980: U.S. Geological Survey WaterResources Investigations Report 83-4256, 184 p.

Mills, L.R., and Laughlin, C.P., 1976, Potentiometric surface 

of Floridan aquifer, Southwest Florida Water Management 

District, May 1975: U.S. Geological Survey Open-File 

Report FL 76002, 1 sheet.

Mills, L.R., Laughlin, C.P., and Parsons, D.C., 1976, 

Potentiometric surface of Floridan aquifer, Southwest 

Florida Water Management District, September 1975: U.S. 

Geological Survey Open-File Report FL 76003, 1 sheet.

Moore, D.L., Martin, D.W., Walker, S.T., Rauch, J.T., and 

Jones, G.W., 1986, Initial sampling results of an ambient 

background ground-water quality monitor network in the 

Southwest Florida Water Management District: Brooksville, 

Southwest Florida Water Management District, 393 p.

National Oceanic and Atmospheric Administration, 1965-75, 

Climatological data, Florida: v. 68-79.

Navoy, A.S., 1986, Hydrogeologic data from a 2,000-foot deep 

core hole at Polk City, Green Swamp area, central Florida: 

U.S. Geological Survey Water-Resources Investigations 

Report 84-4257, 89 p.

Obeysekera, J., and Loftin, M.K., 1990, Hydrology of the 

Kissimmee River basin, influence of man-made and natural 

changes, in Loftin, M.K., Toth, L.A., and Obeysekera, J., 

eds., Proceedings of the Kissimmee River Restoration 

Symposium, October 1988, Orlando, Florida: West 

Palm Beach, South Florida Water Management District, 

p. 211-222.

Office of Economic and Demographic Research, 2005, Total 

county population: April 1, 1970-2030: Tallahassee, The 

Florida Legislature, Excel file [accessed 8/2005] http:www.

state.fl.us/population.htm
O’Reilly, A.M., 1998, Hydrogeology and simulation of the 

effects of reclaimed-water application in west Orange and 

southeast Lake Counties, Florida: U.S. Geological Survey 

Water-Resources Investigations Report 97-4199, 91 p.

O’Reilly, A.M., Spechler, R.M., and McGurk, B.E., 2002, 

Hydrogeology and water-quality characteristics of the 

Lower Floridan aquifer in east-central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

02-4193, 60 p.

Parizek, R.R., 1976, On the nature and significance of fracture 

traces and lineaments in carbonate and other terranes, in 

Karst Hydrology and Water Resources: Proceedings of the 

U.S.-Yugoslavia Symposium, Dubrovnik, Croatia, June 2-7, 

1974, v. 1, p. 47-108.

Patton, T.H., 1981, Geologic investigations of the ordinary 

high water line along the upper Peace River, Polk County, 

Florida: Patton and Associates, Inc., prepared for Beckham, 

McAliley, and Proenza, P.A., 141 p.

Patton, T.H., and Klein, Jean-Georges, 1989, Sinkhole 

formation and its effect on Peace River hydrology, in

Beck, B.F., ed., Engineering and environmental impacts 

of sinkholes and karst: Proceedings of the third multidisciplinary conference on sinkholes, St. Petersburg Beach, 

Florida, October 2-4, 1989: Rotterdam, Balkema Publishers, 

p. 25-31.

Peek, H.M., 1951, Cessation of flow of Kissengen Spring 

in Polk County, Florida: Tallahassee, Florida Geological 

Survey Report of Investigations 7, p. 73-82.

Perrin, L.S., Allen, M.J., Rowse, L.A., MontaIbano, F., III, 

Foote, K.J., and Olinde, M.W., 1982, A report on fish and 

wildlife studies in the Kissimmee River Basin and recommendations for restoration: Okeechobee, Florida Game and 

Fresh Water Fish Commission, Office of Environmental 

Services, 260 p.

Polk County Department of Economic Development, 2005, 

Demographics [accessed 8/2005] http://www.cfdc.org

Pride, R.W., Meyer, F.W., and Cherry, R.N., 1966, Hydrology 

of Green Swamp area in central Florida: Tallahassee, Florida 

Geological Survey Report of Investigations 42, 137 p.

Purdum, E.D., Krafft, P.A., and Fernald, E.A., 1988, Florida 

county atlas and municipal fact book: Tallahassee, Florida 

State University, Institute of Science and Public Affairs, 45 p.

Riggs, H.C., 1972, Frequency curves: U.S. Geological Survey 

Techniques of Water-Resources Investigations, chap. A2, 

book 4, 15 p.

Robertson, A.F., 1971, A preliminary evaluation of hydrologic 

conditions of the Lakeland Ridge area of Polk County, 

Florida: U.S. Geological Survey Open-File Report FL-71007, 

37 p.

Robertson, A.F., 1973, Hydrologic conditions in the Lakeland 

Ridge area of Polk County, Florida: Tallahassee, Florida 

Geological Survey Report of Investigations 64, 54 p.

Robertson, A.F., and Mills, L.R., 1974, Ground-water withdrawals in the upper Peace and upper Alafia River basins, 

Florida: Tallahassee, Florida Geological Survey Map Series 

67, 1 sheet.

Rosenau, J.C., Faulkner, G.L., Hendry, C.W., Jr., and Hull, 

R.W., 1977, Springs of Florida (2d ed.): Tallahassee, Florida 

Geological Survey Bulletin 31, 461 p.

Rutledge, A.T., 1987, Effects of land use on ground-water 

quality in central Florida—Preliminary results: U.S. 

Geological Survey Water-Resources Investigations Report 

86-4163, 49 p.

Ryder, P.D., 1982, Digital model of predevelopment flow in 

the Tertiary limestone (Floridan) aquifer system in westcentral Florida: U.S. Geological Survey Water-Resources 

Investigations Report 81-54, 61 p.

Ryder, P.D., 1985, Hydrology of the Floridan aquifer system in 

west-central Florida: U.S. Geological Survey Professional 

Paper 1403-F, 63 p.

Sacks, L.A., 2002, Estimating ground-water inflow to lakes 

in central Florida using the isotope mass-balance approach: 

U.S. Geological Survey Water-Resources Investigations 

Report 02-4192, 59 p.

Sacks, L.A., Lee, T.M., and Tihansky, A.B., 1992, 

Hydrogeologic setting and preliminary data analysis for 

the hydrologic-budget assessment of Lake Barco, an acid 

seepage lake in Putnam County, Florida: U.S. Geological 

Survey Water Resources Investigations Report 91-4180, 28 p.

Sacks, L.A., Swancar, Amy, and Lee, T.M., 1998, Estimated 

ground-water exchange with lakes using water-budget 

and chemical mass-balance approaches for ten lakes in 

ridge areas of Polk and Highlands Counties, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

98-4133, 52 p.

Sacks, L.A., and Tihansky, A.B., 1996, Geochemical and 

isotopic composition of ground water, with emphasis 

on sources of sulfate, in the Upper Floridan aquifer and 

intermediate aquifer system in southwest Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

96-4146, 54 p.

Schiner, G.R., 1993, Geohydrology of Osceola County, 

Florida: U.S. Geological Survey Water-Resources 

Investigations Report 92-4076, 68 p.

Scott, T.M., 1988, The lithostratigraphy of the Hawthorn 

Group (Miocene) of Florida: Tallahassee, Florida 

Geological Survey Bulletin 59, 148 p.

Selected References  95
96  Hydrology of Polk County, Florida

Scott, T.M., Campbell, K.M., Rupert, F.R., Arthur, J.D., 

Missimer, T.M., Lloyd, J.M., Yon, J.W., and Duncan, J.G., 

2001, Geologic map of Florida: Tallahassee, Florida 

Geological Survey Map Series 146, 1 sheet.

Sepúlveda, Nicasio, 2002, Simulation of ground-water flow 

in the Intermediate and Floridan aquifer systems in peninsular Florida: U.S. Geological Survey Water-Resources 

Investigations Report 02-4009, 130 p.

Shaw, J.E., and Trost, S.M., 1984, Hydrogeology of the 

Kissimmee planning area: West Palm Beach, South Florida 

Water Management District Technical Publication 84-1, 235 p.

Sinclair, W.C., and Reichenbaugh, R.C., 1981, Hydrology of 

the Winter Haven Chain of Lakes, Polk County, Florida: 

U.S. Geological Survey Open-File Report 81-212, 1 plate.

Sinclair, W.C., Stewart, J.W., Knutilla, R.L., Gilboy, A.E., 

and Miller, R.L., 1985, Types, features, and occurrence 

of sinkholes in the karst of west-central Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

85-4126, 81 p.

Snyder, S.W., Evans, M.W., Hine, A.C., and Compton, J.S., 

1989, Seismic expression of solution collapse features from 

the Florida platform, in Beck, B.F., ed., Engineering and 

environmental impacts of sinkholes and karst: Proceedings 

of the Third Multidisciplinary Conference on Sinkholes, 

St. Petersburg Beach, Florida: Orlando, Florida Sinkhole 

Research Institute, p. 281-298.

South Florida Water Management District, 2005a, Headwaters 

projects [accessed 8/1/2005] http://www.sfwmd.gov/org/erf/

krr/construct/headwaters/s65_mods.html

South Florida Water Management District, 2005b, Kissimmee 

River restoration [accessed 8/1/2005] http:// www.sfwmd.

gov/org/erd/krr/pubs/3_krrpub.html

Southwest Florida Water Management District, 1988, Groundwater resources availability inventory, Polk County, Florida: 

Brooksville, 220 p.

Southwest Florida Water Management District, 2000, 

Aquifer characteristics within the Southwest Florida Water 

Management District: Brooksville, 123 p.

Southwest Florida Water Management District, 2002, Upper 

Peace River—An analysis of minimum flows and levels: 

Brooksville, 244 p.

Southwest Florida Water Management District, 2003, Florida 

forever work plan—Annual update: Brooksville, 84 p.

Southwest Florida Water Management District, 2004a, 

2002 estimated water use in the Southwest Florida Water 

Management District: Brooksville, 178 p.

Southwest Florida Water Management District, 2004b, 

Estimated water use, 1998 to 2002, in the Southwest Florida 

Water Management District: Brooksville, 5 p.

Spechler, R.M., and Halford, K.J., 2001, Hydrogeology, water 

quality, and simulated effects of ground-water withdrawals 

from the Floridan aquifer system, Seminole County and 

vicinity, Florida: U.S. Geological Survey Water-Resources 

Investigations Report 01-4182, 116 p.

Sprinkle, C.L., 1989, Geochemistry of the Floridan aquifer 

system in Florida and in parts of Georgia, South Carolina, 

and Alabama: U.S. Geological Survey Professional Paper 

1403-I, 105 p.

Stewart, H.G., Jr., 1963, Records of wells and other waterresources data in Polk County, Florida: Tallahassee, Florida 

Geological Survey Information Circular 38, 144 p.

Stewart, H.G., Jr., 1966, Ground-water resources of Polk 

County, Florida: Tallahassee, Florida Geological Survey 

Report of Investigations 44, 170 p.

Stewart, J.W., 1980, Areas of natural recharge to the Floridan 

aquifer in Florida: Tallahassee, Florida Bureau of Geology 

Map Series 98, 1 sheet.

Stringfield, V.T., 1936, Artesian water in the Florida 

Peninsula: U.S. Geological Survey Water-Supply Paper 

773-C, p. 115-195.

Stringfield, V.T., 1966, Artesian water in Tertiary limestone 

in the southeastern States: U.S. Geological Survey 

Professional Paper 517, 226 p.

Sumner, D.M., 1996, Evapotranspiration from successional vegetation in a deforested area of the Lake Wales 

Ridge, Florida: U.S. Geological Survey Water-Resources 

Investigations Report 96-4244, 37 p.

Swancar, Amy, and Hutchinson, C.B., 1995, Chemical and 

isotopic composition and potential for contamination of 

water in the Upper Floridan aquifer, west-central Florida, 

1986-89: U.S. Geological Survey Water-Supply Paper 2409, 

68 p.

Swancar, Amy, and Lee, T.M., 2003, Effects of recharge, 

Upper Floridan aquifer heads, and time scale on simulated 

ground-water exchange with Lake Starr, a seepage lake in 

central Florida: U.S. Geological Survey Water-Resources 

Investigations Report 02-4295, 53 p.

Swancar, Amy, Lee, T.M., and O’Hare, T.M., 2000, 

Hydrogeologic setting, water budget, and preliminary 

analysis of ground-water exchange at Lake Starr, a seepage 

lake in Polk County, Florida: U.S. Geological Survey WaterResources Investigations Report 00-4030, 66 p.

Szell, G.P., 1993, Aquifer characteristics in the St. Johns River 

Water Management District: Palatka, St. Johns River Water 

Management District Technical Publication SJ 93-1, 495 p.

Tibbals, C.H., 1990, Hydrology of the Floridan aquifer system 

in east-central Florida: U.S. Geological Survey Professional 

Paper 1403-E, 98 p.

Tibbals, C.H., and Grubb, H.F., 1982, Aquifer test results, 

Green Swamp area, Florida: U.S. Geological Survey WaterResources Investigations Report 82-35, 29 p.
Tihansky, A.B., Arthur, J.D., and DeWitt, D.W., 1996, Sublake 

geologic structure from high-resolution seismic-reflection 

data from four sinkhole lakes in the Lake Wales Ridge, 

central Florida: U.S. Geological Survey Open-File Report 

96-224, 72 p.

Tihansky, A.B., and Sacks, L.A., 1997, Evaluation of nitrate 

sources using nitrogen-isotope techniques in shallow 

ground water within selected lake basins in the Central 

Lakes District, Polk and Highlands Counties, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

97-4207, 28 p.

Torres, A.E., Sacks, L.A., Yobbi, D.K., Knochenmus, L.A., 

and Katz, B.G., 2001, Hydrogeologic framework and 

geochemistry of the intermediate aquifer system in parts of 

Charlotte, De Soto, and Sarasota Counties, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

01-4015, 74 p.

Toth, L.A., Arrington, D.A., Brady, M.A., and Muszick, D.A., 

1995, Conceptual evaluation of factors potentially affecting 

restoration of habitat structure within the channelized 

Kissimmee River Ecosystem: Restoration Ecology, v. 3, 

p. 160-180.

U.S. Army Corps of Engineers, 1991, Central and southern 

Florida project environmental restoration of the Kissimmee 

River, Florida—Final integrated feasibility report and environmental impact statement: U.S. Army Corps of Engineers, 

Jacksonville District, 699 p.

U.S. Army Corps of Engineers, 1992, Central and southern 

Florida project environmental restoration of the Kissimmee 

River, Florida—Final integrated feasibility report and 

environmental impact statement: U.S. Government House 

Document 102-286, 716 p.

U.S. Army Corps of Engineers, 1996, Central and southern 

Florida project Kissimmee River headwaters revitalization 

project—Integrated project modification report and supplement to the final environmental impact statement: U.S. 

Army Corps of Engineers, Jacksonville District, 888 p.

U.S. Department of Agriculture, 2005, National agricultural 

statistics service [accessed 8/05] http://www.nass.usda.

gov/fl

U.S. Environmental Protection Agency, 2000, Drinking water 

standards and health advisories: Washington D.C., Office of 

Water, Publication EPA 822-B-00-001, 12 p.

U.S. Environmental Protection Agency, 2005, Proposed 

TMDL report—Nutrient TMDL for Winter Haven Chain of 

Lakes: Atlanta, Ga., 47 p.

U.S. Environmental Protection Agency, 2006, TMDL report—

Dissolved oxygen and nutrient TMDLs for Lake Hancock 

and Lower Saddle Creek: Atlanta, Ga., 110 p.

U.S. Geological Survey, 1998, National field manual for the 

collection of water quality data: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chaps. A1-A9, 2 v., variously paged. Also available at 

http://pubs.water.usgs.gov/twri9A

U.S. Interagency Advisory Committee on Water Data, 1982, 

Guidelines for determining flood flow frequency, Bulletin 

17-B of the Hydrology Subcommittee: Reston, Virginia, 

U.S. Geological Survey, Office of Data Coordination, 183 p.

University of Florida, 1985, Florida statistical abstract: 

Gainesville, Bureau of Economic and Business Research, 

722 p.

University of South Florida, 2003, Hydrologic investigation of 

the phosphate-mined upper Saddle Creek watershed, WestCentral Florida: Tampa, 166 p.

White, W.A., 1970, The geomorphology of the Florida 

Peninsula: Tallahassee, Florida Bureau of Geology 

Bulletin 51, 164 p.

Wilson, W.E., 1977, Hydrologic data for a subsurface wasteinjection site at Mulberry, Florida, 1972-76: U.S. Geological 

Survey Open-File Report 77-511, 24 p.

Wilson, W.E., and Gerhart, J.M., 1982, Simulated effects of 

ground-water development on the potentiometric surface of 

the Floridan aquifer, west-central Florida: U.S. Geological 

Survey Professional Paper 1217, 83 p.

Wolansky, R.M., Barr, G.L., and Spechler, R.M., 1979, 

Generalized configuration of the bottom of the Floridan 

aquifer, Southwest Florida Water Management District: 

U.S. Geological Survey Water-Resources Investigations 

Open-File Report 79-1490, 1 sheet.

Wolansky, R.M., and Corral, M.A., 1985, Aquifer tests in 

west-central Florida, 1952-76: U.S. Geological Survey 

Water-Resources Investigations Report 84-4044, 127 p.

Wood, W.W., 1976, Guidelines for collection and field analysis 

of ground-water supplies for selected unstable constituents: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 1, chap. D2, 24 p.

Yobbi, D.K., 1996, Analysis and simulation of groundwater flow in Lake Wales Ridge and adjacent areas of 

central Florida: U.S. Geological Survey Water-Resources 

Investigations Report 94-4254, 82 p.

Selected References  97
98  Hydrology of Polk County, Florida
Appendix 1. Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]

Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

1 273603081270501 Dressler Dairy UFA – 350 wl Highlands SWF, USGS

2 273615081284901 ROMP 43XX UFA UFA 409 1,363 wl, qw Highlands SWF, USGS

3 273615081284902 ROMP 43XX SAS SAS 32 83 qw Highlands SWF, USGS

4 273851082031501 ROMP 40-1 UFA UFA 408 1,140 wl, qw Polk SWF, USGS

5 273851082031502 ROMP 40 Htrn IAS 76 180 wl, qw Polk SWF, USGS

6 273851082031503 ROMP 40 shallow SAS 38 43 wl, qw Polk SWF, USGS

7 273903081185201 Avon Park Prison #1 (POF-9) UFA – 1,035 wl, qw Polk USGS

8 273913081331801 Wegvar Htrn well IAS 170 240 wl Polk USGS

9 273929081080601 S-65A, POF-20 UFA 260 1,000 wl, qw Polk SF, USGS

10 273929081080602 S-65A, OSS-74 SAS 45 90 wl Polk SF

11 273929081080603 S-65A, OSS-75 SAS 17 32 qw Polk SF, USGS

12 274009081452202 Mobil UF-5 Htrn IAS – 217 wl Polk USGS

13 274134081401801 Lastinger Rd Htrn IAS 94 135 wl Polk USGS

14 274151081513201 Gardinier UFA UFA 410 908 wl Polk USGS, SWF

15 274155081573201 Ft. Green Springs Rd. IAS/UFA 280 302 wl, qw Polk USGS, SWF

16 274218082035701 Barber Htrn IAS 11 191 wl Hillsborough USGS

17 274225081315201 USGS shallow well P-48 SAS 59 62 wl Polk SWF, USGS

18 274238081415801 Mobil UFA-1 UFA 221 243 wl Polk SWF, USGS

19 274259082032801 C.L. Harlow IAS 165 290 qw Hillsborough SWF, USGS

20 274347081305201 Turkey Hill Road surf SAS 54 64 qw Polk SWF, USGS

21 274402081353401 P-10 Frostproof fire twr SAS 20 42 wl, qw Polk SWF, USGS

22 274427082083701 ROMP 48 Tpa/Suw UFA 215 541 wl, qw Hillsborough SWF, USGS

23 274427082083702 ROMP 48 Htrn IAS 46 61 wl, qw Hillsborough SWF, USGS

24 274427082083703 ROMP 48 Avon Park UFA 780 815 wl, qw Hillsborough SWF, USGS

25 274427082083704 ROMP 48 WT SAS 10 14 wl, qw Hillsborough SWF, USGS

26 274432081493401 Barnette Htrn IAS – 229 wl Polk USGS

27 274440081314801 Coley UFA UFA 208 319 wl, qw Polk SWF, USGS

28 274434081575201 CR 630 surficial SAS 18 38 qw Polk SWF, USGS

29 KREFFS, site E SAS 10 15 qw Polk SF

30 Ridge Wrap CLP-9 SAS 25 35 wl Polk SWF 

31 274522081303901 ROMP CL-2 UFA UFA 412 442 wl, qw Polk SWF, USGS

32 274522081303902 ROMP CL-2 Htrn IAS 330 346 wl Polk SWF, USGS

33 274522081303903 ROMP CL-2 deep SAS SAS 200 220 wl, qw Polk SWF, USGS

34 274522081303904 ROMP CL-2 SAS SAS 17 22 wl, qw Polk SWF, USGS

35 274532081320601 City of Frostproof, plant 2, well 4 UFA 207 1,082 qw Polk USGS

36 274545081342501 ROMP CL-3 UFA UFA 228 440 wl, qw Polk SWF, USGS

37 274545081342502 ROMP CL-3 Htrn IAS 140 197 wl, qw Polk SWF, USGS

38 274545081342503 ROMP CL-3 surficial SAS 20 49 wl Polk SWF, USGS

39 274547081470901 ROMP 45 Htrn IAS 110 192 wl, qw Polk SWF, USGS

40 274547081470902 ROMP 45 Suwannee UFA 330 440 wl, qw Polk SWF, USGS

Appendix 1  99
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

41 274547081470903 ROMP 45 Avon Park UFA 680 757 wl, qw Polk SWF, USGS

42 274547081470904 ROMP 45 shallow SAS 38 58 wl, qw Polk SWF, USGS

43 274552081115201 River Ranch replacement UFA – – wl, qw Polk USGS

44 274605081301001 Wardlaw Road SAS SAS 19 37 wl, qw Polk SWF

45 KRFFFS, site F SAS 10 15 wl Polk SF

46 KRFFFM, site F SAS 15 30 wl Polk SF

47 274730081333801 ROMP 55 UFA UFA 212 1,200 wl Polk SWF, USGS

48 274730081333802 ROMP 55 surficial SAS 23 73 qw Polk SWF, USGS

49 Ridge Wrap VC-4 SAS 85 105 wl Polk SWF

50 274746081202201 Indian Lake Estates golf course UFA – 800 wl Polk USGS

51 274749081582501 Polk Co. (Bradley Junction #2) UFA 300 550 qw Polk USGS

52 274807081115501 S-65 (OSF-52) UFA UFA 172 850 wl Osceola USGS, SF

53 274806081311401 North Lake Patrick Road SAS 35 55 wl, qw Polk SWF

54 274810081480601 T. Winkler IAS 112 320 qw Polk USGS

55 S-65, OSS-73 SAS 12 15 wl Osceola SF

56 S-65, OSS-72 SAS 105 120 wl Osceola SF

57 274812081190301 P49 SAS 14 17 wl Polk USGS

58 274815081130301 River Ranch UFA (POF-5) UFA 185 300 wl Polk USGS

59 274820081324501 West Cody Villa Rd. SAS 130 150 wl, qw Polk SWF

60 Ridge Wrap CLP-7 SAS 180 200 wl Polk SWF

61 274840081195001 Indian Lakes Utilities UFA 295 976 qw Polk USGS

62 274841081480901 Homeland #9 UFA UFA – 746 wl Polk USGS

63 274846081262001 USGS Well at Lake Weohyakapka 

 (POF-0008)

IAS 149 197 wl Polk USGS

64 274847081414501 Cloninger Htrn UFA – – wl Polk USGS

65 274848081302201 Murray Road UFA UFA 245 263 wl, qw Polk SWF

66 274848081302202 Murray Road SAS SAS 10 21 wl, qw Polk SWF

67 274851081262001 Lake Weohyakapka SAS SAS 5 20 wl Polk SF

68 274907081124801 Grape Hammock RV Park UFA – 465 qw Polk USGS

69 274908081480901 Homeland DEP #4 IAS 56 202 wl, qw Polk SWF, USGS

70 274910081452201 Lake Garfield Nursery UFA UFA 317 817 wl Polk USGS, SWF

71 274925082084301 WCRWSA SCHM-6 UFA UFA 231 910 wl Hillsborough USGS,SWF

72 274926081355301 ROMP 44 UFA UFA 235 402 wl, qw Polk SWF, USGS

73 274926081355302 ROMP 44 surficial SAS 25 75 wl, qw Polk SWF, USGS

74 Ridge Wrap CLP-5 SAS 48 58 wl Polk SWF

75 275009081540901 Pebbledale Rd. well UFA 288 303 wl, qw Polk SWF, USGS

76 275009081540902 Pebbledale shallow SAS 56 58 wl, qw Polk SWF, USGS

77 275023081321501 ROMP CL-1 UFA UFA 220 315 wl, qw Polk SWF, USGS

78 275023081321602 ROMP CL-1 SAS SAS 29 49 wl Polk SWF

79 275028081394301 Orange Acres Ranch UFA 80 850 qw Polk USGS

80 275031081342100 Ridge Wrap CLP-1 SAS 60 70 wl Polk SWF

100 Hydrology of Polk County, Florida

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

81 Ridge Wrap CLP-3 SAS 30 60 wl Polk SWF

82 275040081493001 Homeland Flrd Well 8 IAS 68 227 wl Polk USGS

83 275040081335801 Muncie Rd. surficial SAS 70 90 wl, qw Polk SWF

84 275059081562201 Commercial Carrier Htrn IAC 92 167 wl Polk USGS

85 275101082025501 USGS surficial SAS 12 17 qw Polk SWF, USGS

86 275115081522101 City of Bartow, Chamber Drive UFA 252 740 qw Polk USGS

87 275128081314201 Golfview Road SAS 45 65 qw Polk SWF

88 275135081252601 East Lake Wales Utility SAS (PO0027) SAS 12 22 wl, qw Polk USGS

89 275137081252501 East Lake Wales Utility UFA (POF-19) UFA – 837 wl, qw Polk USGS

90 275158081275601 Glenn St. Mary Rd. SAS SAS 25 35 qw Polk SWF

91 275146082084301 WCRWSA SCHM-4 UFA UFA 222 915 wl Hillsborough USGS

92 275152082035801 Edison Junction WCRWSA 8 IAS 65 211 wl, qw Hillsborough SWF, USGS

93 275154081314001 Polk Co. LF #203 D-1 (ROMP 14) SAS 68 78 qw Polk SWF, USGS

94 275154081314002 Polk Co. LF #203 AW-1 (ROMP 14) UFA 155 245 qw Polk SWF, USGS

95 275158082085101 WCRWSA Grassy Gulch UFA UFA 220 900 wl Hillsborough SWF, USGS

96 275235082033601 WCRWSA SCHM-4 UFA UFA 209 900 wl Hillsborough SWF, USGS

97 275235082033603 WCRWSA SCHM-4 NRSD SAS – 17 wl Hillsborough USGS

98 275259082032501 W.E. Bugg IAS 55 300 qw Hillsborough SWF, USGS

99 275314081514201 ROMP 59 UFA UFA 200 1,050 wl Polk SWF, USGS

100 275314081514202 ROMP 59 Htrn IAS 122 142 wl Polk SWF, USGS

101 275314081514203 ROMP 59 Upper Htrn IAS 50 60 wl, qw Polk SWF, USGS

102 275323082080601 WCRWSA SCHM-11 UFA UFA 220 918 wl Hillsborough USGS

103 275326081585801 ROMP 60 UFA UFA 237 710 wl, qw Polk SWF, USGS

104 275327081341001 City of Lake Wales, Grove Ave. UFA 745 1,063 qw Polk USGS

105 275348081335701 ROMP 57X UFA UFA 274 315 wl Polk SWF, USGS

106 275348081335702 ROMP 57X Htrn IAS 192 210 wl Polk SWF, USGS

107 275348081335703 ROMP 57X surficial SAS 114 135 wl Polk SWF, USGS

108 275403081391301 St. Joe, SR60 – – 1,500 wl Polk USGS

109 275406081285501 Mammoth Grove Road surficial SAS 11 21 qw Polk SWF, USGS

110 275411081372001 ROMP 57 UFA UFA 160 634 wl, qw Polk SWF, USGS

111 275411081372002 ROMP 57 Htrn IAS 95 140 wl, qw Polk SWF, USGS

112 275411081372003 ROMP 57-3 SAS SAS 15 40 wl, qw Polk SWF, USGS

113 275429082093901 ROMP 61 UFA UFA 360 1,000 wl, qw Hillsborough SWF, USGS

114 275433081460501 Thompson Htrn IAS 68 101 wl Polk USGS

115 275440081493701 Central Fla. Truss Htrn IAS 47 60 wl Polk USGS

116 275448081431601 Polk County, Lake Garfield UFA 130 410 qw Polk USGS

117 275507081353701 ROMP 58 UFA UFA 155 330 wl, qw Polk SWF, USGS

118 275507081353702 ROMP 58 surficial SAS 45 60 wl Polk SWF, USGS

119 Ridge Wrap VC-7 SAS 67 87 wl Polk SWF

120 275524081485601 City of Bartow #4 UFA 183 750 qw Polk USGS

Appendix 1 101

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

121 275536081490901 City of Bartow #2 UFA 180 750 qw Polk USGS

122 275538082031901 Knox UFA UFA 240 300 wl Polk SWF, USGS

123 275547082044801 WCRWSA SCHM-3 UFA UFA 218 880 wl Hillsborough SWF, USGS

124 275547082044802 WCRWSA SCHM-3 IAS 65 90 wl Hillsborough USGS

125 275600081331501 Mountain Lake Corp. SAS SAS 40 60 qw Polk SWF

126 275600081331502 Mountain Lake Corp. UFA 162 260 qw Polk SWF

127 275609081132001 Joe Overstreet 4” UFA UFA – 401 wl Osceola USGS

128 275613082094401 WCRWSA SCHM-2 UFA UFA 115 910 wl Hillsborough USGS

129 275615082022001 Warren Htrn IAS 89 127 wl Polk USGS

130 275545081362701 Tower Wood Htrn IAS 118 150 wl, qw Polk USGS

131 275622081252301 Lake Rosalie (POF-0015) UFA – 575 wl Polk USGS

132 275624081252201 Harbor Camp Ground, Lake Rosalie #2 UFA 365 575 qw Polk USGS

133 275628081541201 Tillery Rd UFA UFA 231 542 wl Polk USGS

134 275634081211801 Kissimmee St Pk (POF-0013) UFA 226 560 wl, qw Polk USGS

135 275634081211901 Kissimmee St Pk SAS (PO0028) SAS 18 28 wl, qw Polk USGS

136 275723081465701 Cumberland Farms UFA UFA 200 300 wl Polk USGS

137 275728081570001 ROMP 60X UFA UFA 212 806 wl Polk SWF, USGS

138 275732081352402 Lake Starr 1PNS-25 SAS SAS 22 25 wl Polk USGS

139 275732081352406 Lake Starr 1PNS-125 UFA UFA 122 125 wl Polk USGS

140 275745081333501 St. Helena Rd. SAS SAS 50 70 wl, qw Polk SWF

141 275759082085401 ROMP DV-2 SAS SAS 15 35 qw Hillsborough SWF, USGS

142 275759082085402 ROMP DV-2 UFA UFA 108 130 wl, qw Hillsborough SWF, USGS

143 275800081523001 Central St. Htrn IAS 77 100 wl Polk USGS

144 275802082044701 Fletcher Lett UFA UFA 100 530 wl Hillsborough USGS

145 275815081444201 Lake Mcleod shallow SAS 24 26 wl Polk USGS

146 275857081352201 P-8 Tindel Camp Rd SAS 90 110 wl Polk SWF

147 275903081342801 Lake Mable Loop Rd south SAS 59 79 wl, qw Polk SWF

148 275918081430601 P-3 Lake Eloise Terrace SAS 41 61 wl, qw Polk SWF

149 275941081413001 Cypress Gdns # 5 PRO UFA 143 737 qw Polk SWF

150 275959081552501 Sanlon Ranch 24” UFA UFA 293 1,220 wl Polk SWF, USGS

151 280045081504001 Polk Co. Landfill Htrn IAS 90 120 wl Polk USGS

152 280053081572301 Orleans St. UFA UFA 219 773 wl Polk SWF, USGS

153 280103081493301 Polk County, Donald Lane UFA 81 610 qw Polk USGS

154 280113081435301 ROMP 73 UFA UFA 161 389 wl Polk SWF, USGS

155 280115081352001 Swann Rd. surficial SAS 77 97 wl, qw Polk SWF

156 280115081352002 Swann Rd. UFA 178 200 wl, qw Polk SWF

157 280153081274101 Lake Hatchineha near Haines City (POF-6) UFA 178 411 wl, qw Polk USGS

158 280229081325201 Lake Hatchinea Rd. 8” UFA (POF-4) UFA 146 453 wl, qw Polk USGS

159 280247082015301 D.J. Trusses Co. Htrn ICU 80 140 wl, qw Polk USGS

160 280252081365001 Watertank Rd. west SAS 125 145 wl, qw Polk SWF

102  Hydrology of Polk County, Florida

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

161 280253081235801 Disney Preserve mid-Htrn 122 ft ICU 108 122 wl Polk SF

162 280253081235802 Disney Preserve SAS 36 ft SAS 26 36 wl, qw Polk USGS, SF

163 280253081235803 Disney Preserve SAS 10 ft SAS 5 10 wl Polk SF

164 280253081235804 Disney Preserve UFA 460 ft UFA 200 460 wl, qw Polk USGS, SF

165 280255081354201 Watertank Road SAS 69 89 wl, qw Polk SWF

166 280301081423701 P-2 11th St. NE SAS 66 86 wl, qw Polk SWF

167 280338081572901 North Fla. Ave. UFA UFA 203 865 wl Polk SWF, USGS

168 280318081593201 Lakeland 10th St. PRO UFA 273 790 qw Polk SWF

169 280350082104401 Fisher UFA #60 UFA – – wl Hillsborough SWF, USGS

170 280408082080801 McIntosh Ellap UFA UFA 99 155 wl Hillsborough SWF, USGS

171 280413081353801 Polk Co. LF #204 B-3 SAS 49 59 qw Polk SWF

172 280415081590301 Lakeland Util. MW # 1 ICU 98 127 qw Polk SWF

173 280413082061401 M. Quagliani UFA UFA 80 216 wl Hillsborough SWF, USGS

174 280416081572001 ROMP 70 surficial SAS 22 35 qw Polk SWF

175 280416081572002 ROMP 70 Floridan UFA 185 645 qw Polk SWF

176 280420081570101 Lakeland Stadium UFA UFA 660 920 wl Polk SWF, USGS

177 280438082075301 Griffin UFA UFA 127 469 wl Hillsborough SWF, USGS

178 280443081391701 City of Winter Haven Ridge Vo-Tech School UFA 182 445 qw Polk USGS

179 280455082021501 J.B. Sergeant UFA UFA – 144 wl Polk SWF, USGS

180 280503081552801 Fish Lake deep UFA 82 311 wl Polk USGS

181 280510082043801 T-2 UFA UFA 130 585 wl Hillsborough SWF, USGS

182 280520081575201 Cresent Dr. UFA UFA 224 827 wl Polk SWF, USGS

183 280530081362301 Ridge Wrap P-6 SAS 85 105 wl, qw Polk SWF

184 280531081431601 Lake Alfred 12” UFA UFA 282 555 wl, qw Polk SWF, USGS

185 280556081532601 Tennorock Road UFA 45 72 wl Polk USGS

186 280558081314801 Kimbell (POF-14) UFA 149 396 wl Polk USGS

187 280622082061701 ROMP 86.5 Cone Ranch UFA UFA 128 177 qw Hillsborough USGS

188 280635081372301 City of Haines #3 UFA 170 570 qw Polk USGS

189 280719081543301 Combee Road SAS SAS 8 9 wl Polk SWF, USGS

190 280715081543501 Combee Road DP ICU 31 55 wl, qw Polk SWF, USGS

191 280708082074801 T-1 UFA UFA 140 579 wl Hillsborough SWF, USGS

192 280732081585301 Polk County (Palmore well) UFA 150 562 qw Polk USGS

193 280740082105201 Black Water Creek UFA UFA 94 154 wl Hillsborough SWF, USGS

194 PO0024 Lake Lowery UC SAS – 7 wl Polk SJR

195 280807081571401 Polk Co., Lake Gibsonia High School UFA 145 618 qw Polk USGS

196 280834082062901 Blackwater Creek transect well 4 ICU 6.4 8.9 wl Hillsborough USGS

197 Ridge Wrap P-5 SAS 95 115 wl Polk SWF

198 280837082063101 Blackwater Creek transect deep UFA 43 91 wl, qw Hillsborough USGS

199 280849082053701 T-3 UFA UFA 144 700 wl Hillsborough SWF, USGS

200 Ridge Wrap P-1 SAS 55 75 wl Polk SWF

Appendix 1 103

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

201 280906082004001 Socrum Spring SAS – – qw Polk USGS

202 280916082005501 Costine UFA 101 139 qw Polk USGS

203 ROMP 74x Davenport test well – 1,560 wl Polk SWF

204 280905081270101 Reedy Creek overlook (OSF-11) UFA 134 398 wl, qw Osceola USGS

205 280957082072001 LS-01 UFA UFA 40 65 wl Hillsborough

206 281007081511001 Zimmerman UFA 67 118 wl Polk SWF

207 281008081441801 PO0006 Lake Alfred 6” UFA UFA 102 425 wl, qw Polk SWF, USGS

208 281008081441802 Lake Alfred SAS SAS 6 9 wl Polk SWF, USGS

209 281031082071801 Alston Track deep UFA 59 98 wl Pasco SWF, USGS

210 281037082071801 J.O. Alston 2” UFA UFA 47 55 wl Pasco SWF, USGS

211 Alston Tract SAS SAS 1 9 wl Polk SWF

212 Alston Tract SAS SAS 1 9 wl Polk SWF

213 281052082052601 Alston deep UFA UFA 50 112 wl Polk USGS

214 281057081495002 ROMP 76 6” UFA, Polk City UFA 264 315 wl, qw Polk SWF, USGS

215 281058081495002 USGS 1.75” drill pipe at Polk City UFA 840 908 wl Polk USGS

216 281058081495003 USGS 4” annular monitor UFA 590 908 wl Polk USGS

217 281058081495004 USGS core hole 2 at Polk City MCU, LFA 1,000 1,996 wl, qw Polk USGS

218 281058081495005 ROMP 76 SAS (PO0026) SAS 25 35 wl, qw Polk SWF

219 281202081391701 PO-0001 Thornhill UFA UFA 108 151 wl, qw Polk SJR

220 281202081391702 PO0002 Thornhill SAS SAS 10 15 wl Polk SJR

221 281226081341901 Three Worlds RV Park UFA 118 310 qw Polk USGS

222 281312082011601 ROMP 87 UFA UFA 300 380 wl, qw Polk SWF, USGS

223 281312082011602 ROMP 87 shallow UFA UFA 28 38 wl, qw Polk SWF, USGS

224 281317081491301 Fussell Road UFA UFA 78 217 wl, qw Polk USGS

225 281317081491302 Fussell Road SAS SAS 19 27 wl Polk USGS

226 281322082084501 Chancey Rd. UFA UFA 50 87 wl Pasco SWF, USGS

227 281429081290501 Mercantile Ln. (OSF-254) UFA – – wl Osceola USGS, SF

228 Ridge Wrap P-4 SAS 90 110 wl Polk SWF

229 281440081431701 Spread Eagle Ranch deep UFA 80 285 wl, qw Polk SWF, USGS

230 281440081431702 Spread Eagle Ranch shallow SAS 15 20 wl, qw Polk SWF, USGS

231 281443082055501 Howard Blvd. UFA UFA 134 172 wl Polk SWF, USGS

232 Howard Street SAS SAS 4 24 wl Polk/

Hillsborough

SWF

233 281504082104801 ROMP 86 UFA UFA 425 434 wl Pasco SWF, USGS

234 281511081393101 USGS deep observation on US 27 (POF-2) UFA 358 453 wl, qw Polk SWF, USGS

235 281511081393102 USGS shallow observation on US 27 SAS 89 92 qw Polk SWF, USGS

236 Intercession City IC-SAS SAS 15 20 wl, qw Osceola SF

237 Intercession City IC-HCU ICU 45 55 wl, qw Osceola SF

238 Intercession City OSF-100 UFA 110 280 wl, qw Osceola SF

239 Intercession City OSF-99 UFA 355 675 wl Osceola SF

240 Intercession City OSF-98 – 1,220 1,490 wl Osceola SF

104  Hydrology of Polk County, Florida

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
Well 

number

USGS site 

identification 

number

Station name Aquifer Bottom of 

casing (feet)

Depth of 

well 

(feet)

Primary 

data 

type

County Source of 

data

241 Intercession City OSF-97 – 2,000 2,130 wl Osceola SF

242 281532081345001 Loughman UFA (POF-1) UFA 85 247 wl, qw Polk SWF, USGS

243 281532081345002 Loughman shallow SAS 29 32 wl, qw Polk SWF, USGS

244 281532082065001 54-East UFA UFA 45 98 wl, qw Pasco USGS

245 281532081493001 USGS shallow well W5470 UFA 78 231 wl Polk USGS

246 281536081324801 FPC 6" UFA UFA 63 261 wl Osceola USGS

247 281631081564501 Spears UFA 90 290 wl Polk USGS

248 281835081552201 Green Swamp Check Station UFA – – wl Polk USGS

249 281836081430401 Green Bay Ranch Cabin deep UFA – – wl Polk USGS

250 281836081430402 Green Bay Ranch Cabin shallow SAS 30 35 wl Polk USGS

251 281837081544101 ROMP 88 Avon Park UFA 195 385 wl, qw Polk SWF, USGS

252 281917081514801 Van Fleet Trail UFA – – qw Polk USGS

253 281951082012001 Green Swamp L11MD UFA – 49 wl, qw Sumter USGS

254 281951082012002 Green Swamp L11MM – – 18 wl Sumter USGS

255 281951082012003 Green Swamp SAS L11MS SAS – 9 wl, qw Sumter USGS

256 282125082021901 Green Swamp check station UFA – 20 qw Sumter USGS

257 282127082022501 ROMP 89 Cumpressco Ranch UFA 20 142 wl Sumter SWF, USGS

258 282152082011201 Green Swamp L-11K deep UFA 0 36 wl Sumter SWF

259 282152082011202 Green Swamp L-11K shallow SAS 0 17 wl Sumter SWF

260 282202081384601 OR0064 Lake Oliver UFA UFA 103 318 wl Orange USGS, SJR

261 282202081384602 Lake Oliver SAS replacement SAS – 38 wl, qw Orange USGS, SJR

262 282241081443901 L-0051 Sand Mine UFA UFA 85 115 wl Lake USGS, SJR

263 282245081492601 Eva UFA (L-0057) UFA 100 192 wl, qw Lake SWF, USGS

264 282245081492602 Eva SAS SAS 18 23 wl, qw Lake SWF, USGS

265 282318081544003 L-0555 Green Swamp test UFA 64 190 wl Lake USGS, SJR

266 282331081370801 USGS well Hartzog Rd. UFA 92 117 wl Orange USGS

267 Lake Louisa test well L-0729 – – 2,400 wl, qw Lake SJR

Appendix 1 105

Appendix 1. (Continued) Well and spring data-collection sites.

[–, no data. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan aquifer. Abbreviations for data type: qw, water-quality sample; wl, ground-water level. 

Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District, SJR, St. Johns River 

Water Management District; USGS, U.S. Geological Survey. Well locations shown in figures 9 and 10]
106  Hydrology of Polk County, Florida
Appendix 2. Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of adjacent 

Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]

Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

2 273615 812849 SWF UFA 7/2/2003 26.1 179 – 8.3 – 11 – 22 7.4 1.4 6.4 <30 7.5 0.11 6.5 73

3 273616 812848 SWF SAS 7/2/2003 330 – – – 3.0 .48 64 3.9 1.9 1.0 <3.0 2.3 <.1 28 145

4 273851 820315 SWF UFA 3/12/2002 26.4 356 217 7.8 – 17 – 40 14 1.2 7.9 100 11 – 41 131

5 273851 820315 SWF IAS 4/29/2003 25.1 601 – 7.4 – 47 – 52 23 1.7 50 <30 51 1.3 1.2 264

6 273852 820315 SWF SAS 12/1/1998 24.9 210 – 6.0 – 18 .041 19 6.9 .83 5.9 11,300 13 .60 .25 88

7 273911 812108 USGS UFA 7/15/2003 25.7 154 104 8.2 70 11 <.02 17 6.1 .50 3.0 5.0 4.5 .10 6.0 65

9 273929 810806 USGS UFA 8/5/2003 24.6 489 285 7.5 170 26 <.02 35 19 1.9 29 <2.0 51 .50 41 123

11 273929 810806 USGS SAS 8/5/2003 24.0 496 292 7.3 180 28 <.02 63 5.4 1.3 32 293 34 .50 1.9 201

15 274155 815732 USGS IAS/

UFA

8/6/2003 25.2 577 351 7.3 230 43 <.02 46 27 1.8 30 92 61 2.3 15 182

19 274259 820328 SWF IAS 3/16/2000 24.5 327 180 7.4 – – .04 33 17 .52 6.5 – 17 .47 9.9 134

20 274348 813053 SWF SAS 7/15/2003 26.8 572 – 4.3 – 8.1 26 38 19 25 5.7 55 25 .05 86 <1.0

21 274403 813534 SWF SAS 5/13/1999 24.4 347 – 5.0 – 14 .006 14 15 28 7.1 202 45 <.10 64 12

22 274427 820833 SWF UFA 6/25/2003 25.8 384 – 7.7 – 21 – 46 17 1.8 12 <30 13 .48 43 133

23 274427 820833 SWF IAS 6/25/2003 28.3 285 – 7.4 – 16 – 31 15 1.6 9.5 520 4.1 .64 2.5 137

24 274427 820833 SWF UFA 6/25/2003 27.0 376 – 7.7 – 20 – 44 17 1.7 11 <30 12 .44 40 133

25 274427 820833 SWF SAS 11/30/1998 27.2 54 – 5.0 – 3.5 .014 2.1 1.1 .07 4.8 16 8.4 .12 3.4 3.1

27 274440 813148 SWF UFA 4/24/2003 25.8 351 – 7.7 – 20 – 40 14 1.9 7.6 <30 11 .29 18 147

28 274440 815801 SWF SAS 11/11/1998 77 – – – 4.5 .38 15 1.6 .09 1.5 <20 2.0 .33 15 25

29 274456 811051 SF SAS 10/24/2000 25.2 568 – 6.8 – – – 100* 55* 1.6* 4.7* 72 4.3* – .73* 270*

31 274522 813039 SWF UFA 2/10/2000 26.4 264 – 8.1 127 23 .01 23 17 2.2 8.0 <25 8.2 – 13 106

34 274522 813039 SWF SAS 2/10/2000 24.6 500 – 6.3 197 2.8 9.4 45 21 23 7.3 <25 28 – 99 52

35 274532 813206 USGS UFA 7/17/2003 25.7 376 272 7.2 170 22 <.02 46 14 2.4 8.1 20 13 .20 44 128

36 274545 813425 SWF UFA 5/19/1999 24.7 418 – 7.4 – 23 .007 52 13 11 12 5.8 7.8 .22 .31 194

37 274545 813425 SWF IAS 4/25/2003 24.3 434 – 7.3 – 28 – 61 15 3.5 8.5 106 9.6 .16 .62 236

39 274547 814709 USGS IAS 8/6/2003 24.4 310 199 7.3 150 39 <.02 34 16 .90 7.5 <7.0 6.1 .80 6.9 151

Appendix 2  107
Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

40 274547 814709 USGS UFA 8/6/2003 27.2 368 229 7.6 170 18 <.02 43 15 1.6 7.9 <2.0 11 .40 36 140

42 274551 814710 USGS SAS 8/6/2003 26.7 315 181 7.6 140 20 6.2 30 15 .50 6.6 <2.0 14 .30 1.9 113

43 274552 811152 USGS UFA 9/9/2003 25.0 335 204 7.7 140 28 <.02 25 16 1.3 12 8.0 17 .60 12 135

44 274610 813008 SWF SAS 7/15/2003 25.2 523 – 4.2 – 6.5 24 30 16 22 8.2 74 31 .04 77 <1.0

48 274730 813337 SWF SAS 2/16/2000 24.9 224 – 5.0 57 9.8 .32 11 7.1 .82 17 1,110 23 – 53 –

51 274749 815825 USGS UFA 7/16/2003 25.1 350 223 7.3 160 16 <.02 44 13 .70 6.3 31 7.8 .30 42 122

53 274809 813113 SWF SAS 7/15/2003 26.2 362 – 4.7 – 11 16 24 13 13 6.4 55 25 .06 43 <1.0

54 274810 814806 USGS IAS 8/12/2003 24.5 495 295 7.0 170 35 <.02 37 18 .90 38 3.0 36 1.0 4.8 193

59 274825 813249 SWF SAS 7/14/2003 27.4 430 – 4.1 – 8.2 22 28 15 17 4.4 57 30 .09 54 <1.0

61 274840 811950 USGS UFA 7/17/2003 25.6 174 106 8.0 82 12 <.02 19 7.4 .80 3.9 6.0 5.7 .20 3.4 78

65 274851 813023 SWF UFA 4/24/2003 25.3 210 – 8.7 – 6.1 – 24 3.8 2.3 8.4 <30 16 .05 21 42

66 274851 813023 SWF SAS 7/7/2003 25.7 453 – 4.3 – 6.9 19 24 12 23 6.9 130 29 .13 55 <1.0

68 274907 811248 USGS UFA 9/9/2003 24.1 572 345 7.3 220 27 <.02 55 19 1.4 29 10 58 .90 26 173

69 274910 814804 SWF IAS 4/28/2003 22.8 401 – 7.3 – 33 – 46 24 1.0 9.1 <30 10 .53 8.6 210

72 274926 813553 SWF UFA 5/17/1999 24.0 302 – 7.6 – 28 .005 34 14 2.4 7.2 4.2 5.8 .60 1.7 142

73 274928 813553 SWF SAS 5/17/1999 25.2 52 – 5.0 – 3.6 .008 .85 .66 2.6 3.7 94 6.4 <.10 1.1 11

76 275011 815415 SWF SAS 11/9/1998 25.1 374 – 7.0 – 43 .076 38 19 1.1 7.5 601 5.7 .83 19 163

77 275023 813215 SWF UFA 2/16/2000 24.3 199 – 8.4 84 – .01 19 9.2 1.4 11 <25 11 – .19 –

79 275028 813943 USGS UFA 9/9/2003 24.9 448 289 6.8 230 46 <.02 54 24 3.4 6.9 55 7.2 .30 <.20 250

83 275049 813343 SWF SAS 7/7/2003 28.6 126 – 5.6 – 6.8 .03 5.0 7.0 2.8 3.5 1,900 15 .03 12 19

85 275102 820254 SWF SAS 11/4/1998 25.0 193 – 4.9 – 3.8 5.7 22 4.3 .28 3.5 9.0 3.9 .59 48 3.0

86 275115 815221 USGS UFA 9/16/2003 24.1 335 208 7.6 150 17 – 39 12 1.1 10 197 9.2 .50 33 123

87 275129 813141 SWF SAS 7/14/2003 27.0 107 – 5.6 – 6.2 2.8 10 2.9 4.2 1.1 47 2.7 .06 23 7.2

88 275135 812526 USGS SAS 11/18/2003 26.5 272 155 7.1 100 12 .22 22 11 1.7 17 13 14 .50 7.5 111

89 275137 812525 USGS UFA 7/15/2003 25.8 160 111 8.1 74 9.6 <.02 18 6.4 .60 3.2 18 5.4 .10 4.3 70

108  Hydrology of Polk County, Florida

Appendix 2. (Continued) Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of 

adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]
Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

90 275140 812755 SWF SAS 7/8/2003 27.3 398 – 4.1 – 6.7 16 19 12 23 4.5 75 27 .19 58 <1.0

92 275152 820358 SWF IAS 1/14/1999 23.8 257 – 7.4 – 25 .01 25 12 .70 6.2 796 9.8 .20 1.7 112

93 275155 813139 SWF SAS 9/14/1999 25.2 213 – 4.6 – 12 6.3 11 9.2 8.8 3.0 24 7.3 .32 47 11

94 275155 813139 SWF UFA 9/14/1999 24.8 104 – 8.8 – 8.5 2.6 12 3.0 .70 2.9 20 4.7 <.10 2.2 30

98 275259 820325 SWF IAS 4/3/2000 24.2 311 – 7.5 – – .061 46 6.6 .45 7.6 – 7.3 .61 .68 144

101 275314 815142 SWF IAS 4/25/2003 24.9 506 – 7.2 – 30 – 47 28 .61 15 465 14 .48 5.1 254

103 275326 815858 SWF UFA 4/29/2003 26.4 332 – 7.6 – 19 – 44 12 .96 7.0 <30 7.9 .33 .64 168

104 275327 813410 USGS UFA 7/17/2003 25.9 298 193 7.4 130 11 .29 39 8.7 2.1 6.4 <2.0 12 .10 21 109

109 275405 812855 SWF SAS 4/3/2002 25.2 367 – 5.4 – 3.9 18 38 7.5 7.6 8.2 25 33 .01 42 6.0

110 275411 813720 SWF UFA 4/24/2003 24.5 365 – 6.8 – 22 – 44 12 3.9 10 413 19 .28 6.3 158

111 275411 813720 SWF IAS 4/24/2003 25.4 418 – 7.2 – 30 – 61 13 4.3 7.2 612 10 .23 6.7 214

112 275413 813721 SWF SAS 5/27/1999 26.0 110 – 5.2 – 4.0 .006 10 1.7 1.9 5.3 238 3.5 .10 23 11

113 275429 820939 SWF UFA 4/4/2000 25.9 400 182 7.6 – – <.004 45 15 .94 – – 15 .12 9.7 177

116 275448 814316 USGS UFA 7/16/2003 24.4 413 245 7.2 190 28 <.02 50 16 3.5 9.6 379 18 .40 <.20 188

117 275511 813538 SWF UFA 4/28/2003 24.9 321 – 7.5 – 33 – 39 14 3.3 7.7 94 5.7 .16 .14 198

120 275524 814856 USGS UFA 8/13/2003 23.8 572 324 6.8 290 20 – 71 28 .90 10 541 10 .40 19 279

121 275536 814909 USGS UFA 8/13/2003 26.4 379 232 7.3 180 17 <.02 50 13 1.0 7.3 19 9.3 .30 23 159

125 275600 813315 SWF SAS 7/10/2003 28.0 400 – 4.6 – 6.8 23 32 6.9 21 3.3 56 18 .13 50 <1.0

126 275600 813315 SWF UFA 4/24/2003 25.4 257 – 8.1 – 11 – 31 7.2 3.4 5.2 <30 10 .07 19 66

130 275621 813639 USGS IAS 8/5/2003 23.6 347 207 7.0 170 31 <.02 50 11 3.8 4.3 1,030 4.4 .40 <.20 228

132 275624 812522 USGS UFA 7/17/2003 24.6 163 106 8.0 76 11 <.02 15 8.1 1.0 3.6 7.0 4.9 .10 1.3 77

134 275634 812118 USGS UFA 7/15/2003 24.0 178 106 7.5 81 12 <.02 19 7.6 1.1 3.5 22 5.7 .30 4.1 78

135 275634 812119 USGS SAS 11/19/2003 23.6 107 60 5.0 13 7.1 <.02 2.9 1.3 .20 11 3,580 20 .10 5.8 5.7

140 275743 813343 SWF SAS 7/10/2003 432 – 5.7 – 9.5 20 34 16 16 6.1 69 26 .03 64 5.1

141 275800 820853 SWF SAS 1/12/1999 26.0 95 – 4.8 – 5.1 .06 3.4 2.3 1.6 5.1 546 11 .20 18 1.0

Appendix 2  109

Appendix 2. (Continued) Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of 

adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]
Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

142 275759 820854 SWF UFA 3/21/2000 25.1 363 207 7.6 – – .004 42 16 1.8 5.2 – 7.1 .60 .28 182

147 275901 813443 SWF SAS 7/10/2003 27.0 301 – 4.2 – 7.4 16 19 9.6 11 5.5 54 15 .11 40 <1.0

148 275918 814306 SWF SAS 5/25/1999 25.6 269 – 4.3 – 6.8 3.4 14 9.3 7.2 8.2 15 26 <.10 47 11

149 275927 814124 SWF UFA 5/24/1999 25.5 367 – 7.6 – 11 <.004 55 8.0 1.4 13 29 19 <.10 5.6 152

153 280103 814933 USGS UFA 7/16/2003 25.4 240 136 7.5 110 15 <.02 32 7.8 1.1 5.5 4.0 7.1 .20 1.4 114

155 280121 813513 SWF SAS 7/8/2003 28.3 412 – 4.6 – 8.9 26 32 11 19 5.1 56 22 .11 33 <1.0

156 280121 813514 SWF UFA 4/24/2003 25.4 306 – 8.6 – 14 – 31 8.9 1.4 5.7 <30 14 .03 4.3 20

157 280153 812741 USGS UFA 9/16/2003 26.7 177 – – – – – – – – – – 12 – 21 –

158 280229 813252 USGS UFA 8/5/2003 24.0 304 175 7.3 150 15 <.02 42 10 1.0 4.7 358 7.2 <.10 .20 149

159 280237 820149 USGS ICU 7/16/2003 23.6 443 294 7.2 210 38 <.02 63 13 .60 9.5 335 14 .50 17 193

160 280253 813650 SWF SAS 7/9/2003 341 – 4.8 – 8.8 14 23 12 13 3.2 53 12 .19 74 <1.0

162 280253 812358 USGS SAS 8/7/2003 23.8 41 30 4.4 4.0 4.7 <.02 .25 .78 <.10 4.1 652 7.1 <.10 1.4 2.0

164 280253 812358 USGS UFA 8/7/2003 24.1 185 115 7.8 85 11 <.02 26 4.8 .70 3.2 12 4.8 .10 11 75

165 280253 813527 SWF SAS 7/9/2003 26.7 202 – 5.1 – 12 10 14 6.1 4.4 2.9 46 13 .04 21 1.0

166 280301 814237 SWF SAS 5/24/1999 25.9 489 – 4.1 – 8.7 22 23 22 11 13 45 24 .10 18 45

168 280345 815933 SWF UFA 3/21/2000 26.7 267 – 7.8 – – <.004 35 8.4 .52 4.2 – 6.9 .29 3.1 126

171 280412 813543 SWF SAS 9/1/1999 25.3 290 – 4.2 – 7.2 13 22 9.5 8.1 5.5 15 16 <.10 49 1.0

172 280412 815853 SWF ICU 3/21/2000 25.5 354 – 7.6 – – 9.7 33 18 .34 6.2 190 15 .32 1.1 114

174 280417 815720 SWF SAS 11/11/1998 25.8 114 – 5.5 – 7.9 .006 7.9 1.1 .36 11 2,230 10 .15 13 21

175 280417 815720 SWF UFA 11/11/1998 27.3 430 – 7.4 – 16 .007 65 11 1.1 5.5 450 7.7 .28 .20 225

178 280443 813917 USGS UFA 9/15/2003 26.4 264 152 7.4 110 14 .41 34 7.2 1.2 6.6 4.0 10 .20 4.6 113

183 280530 813623 SWF SAS 4/7/1999 287 – 7.2 – – – – – – – – – – – –

184 280532 814323 SWF UFA 5/20/1999 25.9 274 – 7.7 – 15 .54 35 10 1.9 7.0 52 10 .13 6.0 115

187 280622 820617 USGS UFA 5/24/2002 23.4 514 294 7.5 250 15 – 93 4.3 .40 8.0 1,710 15 .20 <.20 246

188 280635 813723 USGS UFA 9/8/2003 25.6 366 209 7.3 160 13 <.02 51 7.6 1.3 11 10 16 .10 7.8 158

110 Hydrology of Polk County, Florida

Appendix 2. (Continued) Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of 

adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]
Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

190 280707 815430 USGS ICU 8/6/2003 23.8 585 356 6.3 300 23 <.02 62 36 .30 13 10,800 13 .20 <.20 307

192 280732 815853 USGS UFA 7/15/2003 24.0 239 145 7.8 120 15 <.02 33 8.6 .50 3.8 4.0 5.6 .30 1.2 117

195 280807 815714 USGS UFA 7/15/2003 25.5 384 216 7.7 190 12 <.02 63 7.6 .70 4.8 15 8.0 .20 1.0 188

198 280838 820630 USGS UFA 9/24/2002 23.3 310 175 7.9 150 16 – 48 6.6 .80 5.4 8.0 7.0 .20 1.9 151

201 280906 820040 USGS SAS 9/8/2003 25.3 278 171 4.6 89 7.2 17 11 15 .60 9.0 8.0 33 .40 .40 3.0

202 280916 820055 USGS UFA 9/8/2003 24.0 253 176 6.4 100 14 7.8 31 5.6 .60 7.5 10 18 .20 3.3 64

204 280955 812651 USGS UFA 8/14/2003 22.5 198 115 7.8 93 9.9 <.02 28 5.6 .60 3.4 8.0 5.5 .10 8.0 85

207 281008 814418 USGS UFA 8/14/2003 24.2 258 177 7.5 120 17 <.02 42 4.2 1.5 4.4 252 6.0 .20 .40 125

214 281057 814950 SWF UFA 5/25/1999 24.1 299 – 7.7 – 13 2.0 40 9.8 1.2 5.8 6.3 11 .21 12 119

218 281058 814950 SJR SAS 11/17/2003 24.8 221 166 5.7 – 4.2 – 12 5.2 2.2 20 165 21 .10 15 20

219 281204 813916 SJR UFA 12/14/2001 22.0 177 116 8.0 – – – 25* 6.0* .51* 4.6* – 6.8* .12 3.2* 83

221 281226 813419 USGS UFA 9/8/2003 24.0 318 181 7.1 150 11 – 52 4.8 .60 5.2 134 8.4 <.10 .20 154

222 281312 820125 SWF UFA 3/15/2000 24.7 432 – 7.3 – – <.02 73 6.0 .77 7.7 – 8.8 <.10 <.20 215

223 281313 820124 SWF UFA 5/5/1999 23.6 502 – 7.0 – 19 .017 91 3.9 .35 8.6 1,420 15 .25 <.20 235

224 281317 814913 USGS UFA 8/12/2003 23.7 528 304 6.8 280 14 <.02 108 2.8 1.9 6.4 83 11 <.10 <.40 267

229 281441 814316 SWF UFA 5/3/1999 23.9 244 – 7.3 – 11 <.004 45 1.3 1.6 3.1 74 4.2 <.10 .25 117

230 281441 814316 SWF SAS 5/3/1999 23.9 32 – 4.9 – 2.8 <.004 .23 .42 .24 2.2 8,310 3.6 <.10 .51 8.9

234 281509 813929 USGS UFA 8/7/2003 25.3 309 173 7.4 150 13 <.02 55 3.1 .70 4.4 64 7.2 <.10 2.5 148

235 281509 813929 USGS SAS 8/7/2003 25.5 117 79 4.9 31 6.1 1.8 6.7 3.5 7.2 1.9 13 4.2 <.10 31 3.0

242 281532 813450 SWF UFA 5/12/1999 24.5 279 – 7.4 – 11 .008 51 2.7 .80 4.0 120 6.3 <.10 <.20 136

243 281532 813450 SWF SAS 5/12/1999 24.5 102 – 5.7 – 7.7 .007 10 1.2 1.1 4.3 9,950 8.3 <.10 1.9 –

244 281532 820650 USGS UFA 9/19/2002 22.4 566 327 7.2 – 12 <.020 108 1.5 .20 6.8 4,260 14 <.10 <.20 275

251 281837 815441 SWF UFA 5/5/1999 23.7 498 – 7.2 – 17 .008 77 7.4 1.1 17 59 22 .18 .20 228

252 281917 815148 USGS UFA 11/19/2003 23.3 361 205 7.2 170 15 <.02 56 7.4 .80 6.6 330 7.3 .10 <.20 180

253 281951 820120 USGS UFA 8/13/2003 23.0 810 541 6.3 380 16 <.02 131 13 .20 34 7,200 61 .40 <.20 354

Appendix 2  111

Appendix 2. (Continued) Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of 

adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]
Well 

No. Latitude Longitude Data source Aquifer Date

Temperature,

 ̊C

Specific 

conductance, 

field, 

μS/cm

Total 

dissolved 

solids, 

mg/L

pH

Hardness 

total, 

mg/L as 

CaCO3

Silica, 

mg/L

Nitrate, 

mg/L

Calcium, 

mg/L

Magnesium, 

mg/L

Potassium, 

mg/L

Sodium, 

mg/L

Iron, 

μg/L

Chloride, 

mg/L

Fluoride, 

mg/L

Sulfate, 

mg/L

Alkalinity, 

mg/L as 

CaCO3

255 281951 820120 USGS SAS 8/13/2003 25.1 515 352 6.3 210 9.7 <.02 58 15 .20 30 10,000 15 .60 4.1 258

256 282125 820219 USGS UFA 8/8/2003 22.0 605 350 6.7 320 12 <.02 123 2.4 <.10 9.7 921 16 .10 5.0 294

261 282202 813846 USGS SAS 3/6/2001 23.9 243 163 5.0 69 5.7 4.6 13 8.9 14 1.9 405 8.1 <.10 61 7.0

263 282245 814926 USGS UFA 8/12/2003 23.3 306 176 7.2 150 14 <.02 55 2.2 1.6 4.3 307 7.1 <.10 <.20 148

264 282245 814926 USGS SAS 8/12/2003 22.7 90 50 5.3 18 3.5 <.02 5.1 1.2 2.3 6.6 969 8.6 <.10 12 12

Appendix 2. (Continued) Chemical and physical data for water from the surficial aquifer system, intermediate aquifer system, and Upper Floridan aquifer wells in Polk and parts of 

adjacent Highlands, Hillsborough, Lake, Orange, and Osceola Counties.

[Abbreviations for source of data: SF, South Florida Water Management District; SWF, Southwest Florida Water Management District; SJR, St. Johns River Water Management District; USGS, U.S. Geological 

Survey. Abbreviations for aquifer: SAS, surficial aquifer system; ICU, intermediate confining unit; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; MCU, middle confining unit; LFA, Lower Floridan 

aquifer. Samples analyzed by the USGS are dissolved; sample with an asterisk (*) is total concentration. In ground water, dissolved and total constituents are comparable if particulate matter is negligible.  ̊C, degrees 

Celsius; μS/cm, microsiemens per centimeter at 25  ̊C; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not analyzed; <, less than. Well locations shown in figure 10]

112  Hydrology of Polk County, Florida
Appendix 3. Lake and stream data-collection sites.

[Site number in figure 56]

Site number Site name Latitude Longitude

1 Lake Deeson 28o06’38” 81o55’50”

2 Lake Bonny 28o03’01” 81o58’29”

3 Lake Wire 28o02’51” 81o57’34”

4 Lake Morton 28o02’16” 81o57’09”

5 Lake Hunter 28o02’01” 81o57’59”

6 Lake Parker 28o03’00” 81o55’21”

7 Lake Bonny 28o02’16” 81o55’44”

8 Lake John 28o00’16” 81o56’24”

9 Scott Lake 27o57’45” 81o56’03”

10 Lake Helene 28o10’26” 81o48’20”

11 Lake Agnes 28o10’07” 81o49’05”

12 Clearwater Lake 28o10’13” 81o49’59”

13 Mud Lake 28o10’11” 81o50’37”

14 Little Lake Agnes 28o09’41” 81o48’27”

15 Lake Tennessee 28o08’38” 81o48’56”

16 Lake Mattie 28o08’11” 81o47’02”

17 Lake Juliana 28o07’52” 81o47’44”

18 Lake Van 28o06’26” 81o46’45”

19 Lake Arietta 28o05’44” 81o47’42”

20 Lake Whistler 28o05’29” 81o48’34”

21 Lake Myrtle 28o05’16” 81o49’40”

22 Lake Ariana 28o05’04” 81o48’37”

23 Grassy Lake 28o07’04” 81o44’34”

24 Lake Swoope 28o06’11” 81o43’30”

25 Lake Alfred 28o05’42” 81o44’05”

26 Lake Pansy 28o04’06” 81o44’39”

27 Lake Mariana 28o04’11” 81o45’19”

28 Blue Lake 28o02’43” 81o46’24”

29 Lake Buckeye 28o02’31” 81o42’19”

30 Lake Maude 28o02’11” 81o43’14”

31 Lake Silver 28o01’16” 81o43’44”

32 Lake Martha 28o01’36” 81o43’19”

33 Lake Elbe 28o01’41” 81o42’44”

34 Lake Mariam 28o00’51” 81o42’04”

35 Lake Otis 28o01’01” 81o42’51”

36 Deer Lake 28o01’38” 81o45’34”

37 Lake Howard 28o01’03” 81o44’57”

38 Lake Annie 27o59’06” 81o36’39”

39 Lake Ruby 27o58’28” 81o39’29”

40 Lake Bess 27o58’04” 81o39’20”

Appendix 3  113
Site number Site name Latitude Longitude

41 Lake McLeod 27o58’29” 81o45’09”

42 Lake Starr 27o57’23” 81o35’32”

43 Lake Wales 27o54’14” 81o34’43”

44 Lake Parker 27o54’34” 81o38’14”

45 Lake Garfield 27o53’49” 81o43’37”

46 Lake Walker 27o51’16” 81o43’11”

47 Lake Buffum 27o48’31” 81o40’00”

48 Lake Henry 27o46’50” 81o43’08”

49 Blue Lake 27o51’23” 81o34’55”

50 Blue Lake 27o51’01” 81o34’26”

51 Big Gum Lake 27o55’45” 81o29’32”

52 Little Gum Lake 27o55’19” 81o28’55”

53 Cypress Lake 27o54’55” 81o28’48”

54 Thomas Lake 27o54’19” 81o28’30”

55 Saddlebag Lake 27o53’53” 81o27’52”

56 Crooked Lake 27o48’29” 81o33’18”

57 Little Crooked Lake 27o45’46” 81o34’21”

58 Lake Clinch 27o45’16” 81o32’24”

59 Reedy Lake 27o44’32” 81o29’57”

60 Lake Hickory 27o42’01” 81o32’09”

61 Lake Hamilton 28o2’1” 81o38’39”

62 Lake Marion 25o5’57” 81o31’57”

63 Lake Hancock 27o57’49” 81o51’28”

64 Mountain Lake 27o56’9” 81o35’27”

65 Green Swamp Run near Eva 28o18’39” 81o41’08”

66 Fox Branch near Socrum 28o10’55” 82o00’45”

67 Saddle Creek near Structure P-11 

 near Bartow

27o56’17” 81o51’05”

68 Peace River at Bartow 27o54’07” 81o49’03”

69 Peace Creek Drainage Canal near 

 Wahneta

27o55’28” 81o43’37”

70 Peace River at Fort Meade 27o45’04” 81o46’56”

71 Bowlegs Creek near Fort Meade 27o41’59” 81o41’44”

72 Catfish Creek near Lake Wales 27o57’40” 81o29’48”

73 Tiger Creek near Babson Park 27o48’40” 81o26’38”

74 Kissimmee River at S-65 near 

 Lake Wales

27o48’14” 81o11’53”

75 Livingston Creek near Frostproof 27o42’30” 81o26’48”

76 Withlacoochee River near 

 Compressco

28o18’42” 82o03’22”

114  Hydrology of Polk County, Florida

Appendix 3. (Continued) Lake and stream data-collection sites.

[Site number in figure 56]