U.S. Department of the Interior

U.S. Geological Survey

Series Name 0000

Secondary Identification

This Is the Cover for a Standard Report That Is Not an 

Individually Published Chapter of a Larger Volume

Prepared in cooperation with

Highlands County,

South Florida Water Management District,

Southwest Florida Water Management District

Hydrogeology and

Groundwater Quality of

Highlands County, Florida

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5097

©

©

2010 Google - Imagery,

2010 DigitalGlobe,

Florida Department of Environmental Protection,

GeoEye,

U.S. Geological Survey
Clockwise from top:

• Rosemary scrub—photograph by Reed Bowman

• Caladiums—photograph by Rick Spechler

• Lake Istokpoga—photograph by Rick Spechler

• Areal photo of lakes and sinkholes—

 ©2010 Google - Imagery, ©2010 DigitalGlobe

 Florida Department of Environmental Protection, 

 GeoEye, U.S. Geological Survey

Cover2.indd 1 7/8/2010 1:31:09 PM
Hydrogeology and Groundwater Quality of 

Highlands County, Florida

By Rick M. Spechler

Prepared in cooperation with

Highlands County

South Florida Water Management District

Southwest Florida Water Management District

Scientific Investigations Report 2010–5097

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Spechler, R.M., 2010, Hydrogeology and Groundwater Quality of Highlands County, Florida: U.S. Geological Survey 

Scientific Investigations Report 2010-5097, 84 p.
iii

Acknowledgments

The author gratefully acknowledges the assistance given by many organizations and individuals 

during the study and especially appreciates the cooperation received from Steve Krupa, 

Chris Sweazy, Emily Hopkins Richardson, Anne Dodd, and Cynthia Gefvert of the South 

Florida Water Management District; Tamera McBride, Jerry Mallams, Ron Basso, Margit 

Crowell, and Carol Smith of the Southwest Florida Water Management District; Jim Polatty 

and Clell Ford of Highlands County; and Hilary Swain of Archbold Biological Station. Special 

thanks is also given to Torsten Rothman of the Highlands County Natural Resources Advisory 

Commission, who provided field assistance and owner contact information for several wells 

that were later sampled for this study. Finally, appreciation is expressed to the ranchers, grove 

operators, and other land owners who permitted access to their properties and allowed the 

sampling of water from their wells.
iv
v

Contents

Acknowledgments........................................................................................................................................iii

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

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

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

Previous Studies ...................................................................................................................................3

Description of Study Area ............................................................................................................................3

Population, Industry, and Land Use ...................................................................................................3

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

Surface-Water Features......................................................................................................................8

Climate, Rainfall, and Evapotranspiration.........................................................................................8

Water Use ............................................................................................................................................12

Methods of Data Evaluation and Collection............................................................................................13

Well Records and Site Identification...............................................................................................13

Geologic and Geophysical-Log Data Collection............................................................................14

Water-Level Data Collection.............................................................................................................14

Water-Quality Data Collection and Analysis..................................................................................15

Quality-Assurance Samples .............................................................................................................16

Geologic Framework ...................................................................................................................................16

Stratigraphy .........................................................................................................................................18

Sinkholes..............................................................................................................................................19

 Hydrogeology...............................................................................................................................................20

Surficial Aquifer..................................................................................................................................21

Intermediate Aquifer System/Intermediate Confining Unit .........................................................27

Floridan Aquifer System.....................................................................................................................31

Upper Floridan Aquifer..............................................................................................................31

Middle Confining Units..............................................................................................................34

Lower Floridan Aquifer and Sub-Floridan Confining Unit ...................................................34

Groundwater System and Characteristics .....................................................................................35

Potentiometric Surface of the Upper Floridan Aquifer........................................................35

Groundwater Withdrawals, Recharge, and Discharge.......................................................35

Long-Term Trends in Groundwater Levels.............................................................................37

Water-Level Comparisons........................................................................................................40

Water-Budget Components......................................................................................................40

Assessment of Groundwater Quality........................................................................................................43

Surficial Aquifer..................................................................................................................................46

Major Ions and Physical Characteristics ..............................................................................46

Nutrients......................................................................................................................................48

Intermediate Aquifer System............................................................................................................51

Upper Floridan Aquifer.......................................................................................................................52

Major Ions and Physical Characteristics ..............................................................................53

Nitrate Concentration ...............................................................................................................59

Vertical Distribution of Chloride and Sulfate Concentrations ....................................................59

Summary and Conclusions.........................................................................................................................62

Selected References...................................................................................................................................64
vi

Appendix 1. Inventory of wells used in this study .......................................................................... 72–76

Appendix 2. Summary of major inorganic constituents and physical characteristics in 

 the surficial aquifer and intermediate and Floridan aquifer systems in 

 Highlands County and parts of adjacent counties ................................................... 77–80

Appendix 3. Summary of selected trace metals and nutrients in the surficial aquifer 

 and intermediate and Floridan aquifer systems in Highlands County and 

 parts of adjacent counties ........................................................................................... 81–84

Figures

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

2. Map showing topography of Highlands County...........................................................................5

3. Graph showing historical and projected population growth for Highlands County ..............5

4–6. Maps showing: 

4. Generalized land use in Highlands County, 2004................................................................6

5. Generalized physiography of Highlands County.................................................................7

6. Major surface-water drainage basins, streams, canals, and lakes in 

 Highlands County......................................................................................................................9

7–9. Graphs showing: 

7. Annual rainfall at Archbold Biological Station and Avon Park, Florida.......................10

8. Average monthly potential evapotranspiration for Highlands County, 

 1996-2007..................................................................................................................................11

9. Historical groundwater use in Highlands County, 1965-2005........................................12

10. Pie chart showing total groundwater use, by category, for 2005 ...........................................13

11. Map showing location of wells used for data collection.........................................................14

12. Chart showing relation of stratigraphic and hydrogeologic units..........................................16

13. Geologic map of Highlands County..............................................................................................17

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

15. Map showing location of hydrogeologic sections ....................................................................21

16. Diagram showing generalized hydrogeologic sections A-A’ and B-B’.................................22

17. Diagram showing generalized hydrogeologic section C-C’.....................................................23

18. Map showing generalized thickness of the surficial aquifer ..................................................24

19. Map showing transmissivity of the surficial aquifer and intermediate aquifer system......25

20. Diagrams showing water levels in selected wells completed in the surficial aquifer........26

21. Map showing generalized altitude of the top of the intermediate aquifer system/

 intermediate confining unit...........................................................................................................28

22. Map showing generalized thickness of the intermediate aquifer system/

 intermediate confining unit...........................................................................................................29

23. Diagrams showing water levels in selected wells completed in the intermediate 

 aquifer system.................................................................................................................................30

24–27. Maps showing:

24. Altitude of the top of the Floridan aquifer system.......................................................... 32

25. Transmissivity of the Upper Floridan aquifer................................................................... 33

26. Potentiometric surface of the Upper Floridan aquifer, May 2007 ............................... 36

27. Potentiometric surface of the Upper Floridan aquifer, September 2007 ................... 37

28. Diagrams showing water levels in selected wells completed in the Upper 

 Floridan aquifer...............................................................................................................................38
vii

29. Map showing simulated vertical leakage rates to and from the Upper 

 Floridan aquifer...............................................................................................................................39

30. Diagrams showing water levels in selected wells open to the surficial aquifer, 

 intermediate aquifer system, and Upper Floridan aquifer.......................................................41

31. Diagrams showing water levels during drilling of monitoring wells ......................................42

32. Plot showing limiting concentrations of chloride recommended for plants, 

 animals, public-supply, and industrial use.................................................................................44

33. Graph showing relation between specific conductance and total dissolved-solids 

 concentration..................................................................................................................................44

34. Graph showing relation between chloride concentration and specific conductance.......45

35. Trilinear diagram showing chemical composition of water from the surficial aquifer.......47

36–39. Maps showing generalized distribution of: 

36. Specific conductance in water from the surficial aquifer ............................................ 48

37. Chloride concentrations in water from the surficial aquifer........................................ 49

38. Sulfate concentrations in water from the surficial aquifer .......................................... 50

39. Nitrate concentrations in water from the surficial aquifer .......................................... 51

40. Trilinear diagram showing chemical composition of water from the intermediate 

 aquifer system.................................................................................................................................52

41. Map showing generalized distribution of specific conductance in water from 

 the intermediate aquifer system..................................................................................................53

42. Map showing generalized distribution of chloride concentrations in water from 

 the intermediate aquifer system..................................................................................................54

43. Trilinear diagram showing chemical composition of water from the Upper 

 Floridan aquifer...............................................................................................................................55

44–46. Maps showing generalized distribution of: 

44. Specific conductance in water from the Upper Floridan aquifer ................................ 56

45. Chloride concentrations in water from the Upper Floridan aquifer............................ 57

46. Sulfate concentrations in water from the Upper Floridan aquifer.............................. 58

47. Graph showing relation between sulfate-chloride equivalent ratio and sulfate 

 concentration in water from the Upper Floridan aquifer.........................................................59

48. Map showing generalized distribution of hardness concentrations in water from 

 the Upper Floridan aquifer............................................................................................................60

49. Graphs showing chloride and sulfate concentrations in water samples obtained 

 during drilling of monitoring wells...............................................................................................61

Tables

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

 Highlands County ...................................................................................................................................11

2. Analytical methods and drinking-water standards for inorganic analytes collected 

 by the U.S. Geological Survey.............................................................................................................15

3. Summary statistics of groundwater quality of the surficial aquifer and intermediate 

 aquifer system in Highlands County ...................................................................................................45

4. Summary statistics of groundwater quality of the Upper Floridan aquifer in 

 Highlands County ...................................................................................................................................46
viii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch per year (in/yr) 2.54 centimeter per year (cm/yr)

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 meters 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 (m/d)/m

Temperature

Fahrenheit (°F) °C = (°F-32)/1.8 Celsius (°C)

*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.

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.

Additional Abbreviations

μ = micron

μS/cm = microsiemen per centimeter

mL = milliliter

mg/L = milligrams per liter
Abstract

Groundwater is the main source of water supply in 

Highlands County, Florida. As the demand for water in the 

county increases, additional information about local groundwater resources is needed to manage and develop the water 

supply effectively. To address the need for additional data, 

a study was conducted to evaluate the hydrogeology and 

groundwater quality of Highlands County. 

Total groundwater use in Highlands County has increased 

steadily since 1965. Total groundwater withdrawals increased 

from about 37 million gallons per day in 1965 to about 107 

million gallons per day in 2005. Much of this increase in 

water use is related to agricultural activities, especially citrus 

cultivation, which increased more than 300 percent from 1965 

to 2005

Highlands County is underlain by three principal 

hydrogeologic units. The uppermost water-bearing unit is 

the surficial aquifer, which is underlain by the intermediate 

aquifer system/intermediate confining unit. The lowermost 

hydrogeologic unit is the Floridan aquifer system, which 

consists of the Upper Floridan aquifer, as many as three 

middle confining units, and the Lower Floridan aquifer. 

The surficial aquifer consists primarily of fine-tomedium grained quartz sand with varying amounts of clay 

and silt. The aquifer system is unconfined and underlies the 

entire county. The thickness of the surficial aquifer is highly 

variable, ranging from less than 50 to more than 300 feet. 

Groundwater in the surficial aquifer is recharged primarily 

by precipitation, but also by septic tanks, irrigation from wells, 

seepage from lakes and streams, and the lateral groundwater 

inflow from adjacent areas.

The intermediate aquifer system/intermediate confining 

unit acts as a confining layer (except where breached by sinkholes) that restricts the vertical movement of water between 

the surficial aquifer and the underlying Upper Floridan 

aquifer. The sediments have varying degrees of permeability 

and consist of permeable limestone, dolostone, or sand, or 

relatively impermeable layers of clay, clayey sand, or clayey 

carbonates. The thickness of the intermediate aquifer system/

intermediate confining unit ranges from about 200 feet in 

northwestern Highlands County to more than 600 feet in the 

southwestern part. Although the intermediate aquifer system 

is present in the county, it is unclear where the aquifer system 

grades into a confining unit in the eastern part of the county. 

Up to two water-bearing units are present in the intermediate 

aquifer system within the county. The lateral continuity and 

water-bearing potential of the various aquifers within the 

intermediate aquifer system are highly variable. 

The Floridan aquifer system is composed of a thick 

sequence of limestone and dolostone of Upper Paleocene to 

Oligocene age. The top of the aquifer system ranges from 

less than 200 feet below NGVD 29 in extreme northwestern 

Highlands County to more than 600 feet below NGVD 29 in 

the southwestern part. The principal source of groundwater 

supply in the county is the Upper Floridan aquifer. As of 2005, 

about 89 percent of the groundwater withdrawn from the 

county was obtained from this aquifer, mostly for agricultural 

irrigation and public supply. Over most of Highlands County, 

the Upper Floridan aquifer generally contains freshwater, 

and the Lower Floridan aquifer contains more mineralized 

water. The potentiometric surface of the Upper Floridan 

aquifer is constantly fluctuating, mainly in response to 

seasonal variations in rainfall and groundwater withdrawals. 

Hydrogeology and Groundwater Quality of 

Highlands County, Florida

By Rick M. Spechler
2 Hydrogeology and Groundwater Quality of Highlands County, Florida

The potentiometric surface of the Upper Floridan aquifer in 

May 2007, which represents the hydrologic conditions near 

the end of the dry season when water levels generally are 

near their lowest, ranged from about 79 feet above NGVD 29 

in northwestern Highlands County to about 40 feet above 

NGVD 29 in the southeastern part of the county. The potentiometric surface of the Upper Floridan aquifer in September 2007 

was about 3 to 10 feet higher than that measured in May 2007. 

Groundwater samples collected from 129 wells by the 

U.S. Geological Survey, State, and County agencies between 

2000 and 2008 were used to characterize groundwater 

quality in Highlands County. Water-quality samples from 

58 wells were collected specifically for this study by the 

U.S. Geological Survey and analyzed for common inorganic 

constituents and nutrients. 

Water quality in the surficial aquifer can be highly 

variable. This variability results from several factors, including 

the lithology of the sediments, interaction with the Upper 

Floridan aquifer, and most importantly, effects of land use. 

Concentrations of specific conductance and major ions are 

generally low. Specific conductance ranged from 32 to 723 

microsiemens per centimeter (μS/cm), chloride concentrations 

ranged from 2.6 to 54 milligrams per liter (mg/L), sulfate 

concentrations ranged from 0.2 to 87 mg/L, and hardness 

(as CaCO3) ranged from 4.0 to 159 mg/L. Ofthe samples 

collected in the surficial aquifer, only nitrate concentrations 

exceeded the Florida primary drinking-water standard of 

10 mg/L. The application of fertilizers related to citrus farming 

is the most likely source of nitrate in groundwater in this area.

Specific conductance of water in the intermediate aquifer 

system in Highlands County ranged from 66 to 11,500 μS/cm, 

and concentrations of chloride and sulfate ranged from 3.8 

to 3,770 and 0.12 to 111 mg/L, respectively. With only a few 

exceptions, concentrations of total dissolved solids, chloride, 

sulfate, and nitrate were below State drinking-water standards.

Specific conductance of water in the Upper Floridan 

aquifer ranged from 133 to 1,900 μS/cm, and concentrations of chloride and sulfate ranged from 4.4 to 403 and less 

than 0.18 to 255 mg/L, respectively. Water from the Upper 

Floridan aquifer in most of the county is hard, ranging from 

64 to 410 mg/L. Nitrate concentrations ranged from less 

than 0.04 to 0.22 mg/L; however, most of the water samples 

collected from the Upper Floridan aquifer had concentrations 

less than 0.04 mg/L.

Concentrations of chemical constituents in the Upper 

Floridan aquifer vary both areally and with depth. Inorganic 

constituent concentrations in water from the Upper Floridan 

aquifer generally were below State and Federal drinking-water 

standards, except in the southeastern and southwestern parts of 

the county where the water is more mineralized. The sources 

of the mineralized water are from relict seawater that entered 

the aquifer during a higher stand of sea level in the geologic 

past and has not been completely flushed from the aquifer, and 

from the dissolution of sulfur-bearing minerals in the aquifer.

Introduction

Groundwater use in central Florida has increased 

substantially over the past several decades. In Highlands 

County, groundwater withdrawals have increased from 

about 37 Mgal/d in 1965 to 107 Mgal/d in 2005. Some of 

this increase is due to an expanding population, which has 

increased in the county from about 21,000 in 1960 to about 

99,000 in 2007. Much of this increase in water use, however, 

is related to agricultural activities, especially citrus cultivation, 

which increased more than 300 percent from 1965 to 2005. 

The expansion of development and agriculture has placed 

increased demands on limited water resources in the area.

As the demand for water in Highlands County increases, 

additional information about the underlying aquifers is needed 

to manage and develop the water supply effectively. With the 

exception of the Lake Wales Ridge area, the hydrogeologic 

framework, groundwater flow system, and water-quality 

conditions are not well defined. The last comprehensive 

countywide hydrogeologic investigation of Highlands County 

was completed in 1956 (Bishop, 1956). Existing maps that 

depict the tops, thicknesses, and lithologic characteristics 

of the various hydrogeologic units are generally regional in 

scope, are based on sparse data, and generally end at the water 

management district boundaries. Similarly, existing maps 

that show the areal distribution of water-quality characteristics are based on limited data points. To address the need 

for additional data, the U.S. Geological Survey (USGS), in 

cooperation with Highlands County, the South Florida Water 

Management District (SFWMD), and the Southwest Florida 

Water Management District (SWFWMD), began a study in 

2006 to evaluate the hydrogeology and groundwater quality 

of the county. The study provides information useful for the 

conservation, development, and management of the water 

resources of Highlands County.

Purpose and Scope

The purpose of this report is to document a comprehensive 

study of hydrogeology, hydrologic characteristics, and water 

quality in Highlands County, Florida. The report includes data 

that describe (1) the lithology, depth, thickness, and extent of 

the surficial aquifer, intermediate aquifer system, and Floridan 

aquifer system in Highlands County based on geologic, 

geophysical, and drillers’ logs; (2) water levels and water-level 

trends in the aquifer systems using maps and hydrographs; and 

(3) areal and vertical water-quality characteristics within the 

aquifer systems.

Data used in this report are derived from publications and 

files of the USGS, SWFWMD, SFWMD, Florida Department 

of Environmental Protection (FDEP), Florida Geological 

Survey (FGS), and reports prepared by private consultants. 

Additional data collected by the USGS from 2006 to 2008 

were used to supplement previously available data.
Description of Study Area 3

Previous Studies

Over the years, reports have documented the geology, 

hydrology, and groundwater resources of Highlands County. 

Discussions of Florida geology with reference to Highlands 

County are included in reports by Cooke (1945), Stringfield 

(1966), White (1970), Scott (1988), and Arthur and others 

(2008). The first comprehensive investigation of the hydrogeology and groundwater resources of Highlands County 

was done by Bishop (1956). A number of subsequent studies 

have described the hydrogeology of selected areas within 

Highlands County. Shaw and Trost (1984) evaluated the 

regional hydrogeology of the Kissimmee River basin. Miller 

(1986) described the hydrogeologic framework of the Floridan 

aquifer system. Duerr and others (1988) and Knochenmus 

(2006) described the hydrogeologic framework of the intermediate aquifer system in west-central Florida. Basso and 

Hood (2005) discussed groundwater resources of the intermediate aquifer system in the southern part of the SWFWMD. 

The hydrogeology of the Lake Wales Ridge was described by 

Barcelo and others (1990) and Yobbi (1996). Tihansky and 

others (1996) utilized continuous high-resolution seismicreflection techniques beneath four lakes along the Lake Wales 

Ridge in Polk and Highlands Counties to describe the local 

geologic structure. Groundwater flow modeling studies that 

include all or part of the study area are presented by Tibbals 

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

(2002), and Radin and others (2005).

Various water-quality studies have included all or part 

of Highlands County. Sprinkle (1989) discussed the chemical 

quality of groundwater in the Floridan aquifer system in 

Florida. 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. 

Moore and others (1986) summarized information from the 

ambient groundwater-quality monitoring program for the 

SWFWMD. Nitrate in groundwater in the vicinity of the Lake 

Wales Ridge was evaluated by Tihansky and Sacks (1997) and 

Wheaton and Graham (2000). Agricultural chemicals in the 

surficial aquifer in the Lake Wales Ridge were investigated by 

Choquette and others (2005).

The hydrology of lakes within Highlands County has 

been documented in several reports. Kohout and Meyer (1959) 

described the hydrologic features of the Lake Istokpoga and 

Lake Placid areas. The hydrology of the Lake Placid area was 

reported by Adams and Stoker (1985). The hydrology of Lake 

June in Winter was described by Belles and Martin (1985). 

Sacks and others (1998) estimated groundwater exchange with 

lakes in the ridge areas of Polk and Highlands Counties by 

using water-budget and chemical mass-balance approaches. 

A report by Choquette and Kroening (2009) summarizes the 

results of water-quality data collected at eight lakes along 

the Lake Wales Ridge in Polk and Highlands Counties, with 

emphasis on pesticides and their degradates. 

Description of Study Area

Highlands County, located in the south-central part of the 

Florida Peninsula, is the 14th largest county in Florida (fig. 1). 

The county is bordered on the north by Polk County, on the 

east by Okeechobee County, on the south by Glades County, 

and on the west by Hardee and DeSoto Counties. Highlands 

County has a total surface area of about 1,106 mi2, of which 

78 mi2 are water (http://www.city-data.com/county/Highlands_

County-FL.html). Land-surface altitudes range from about 20 

to 210 ft above NGVD 29 (fig. 2). The lowest altitudes occur 

near the Kissimmee River east of Brighton and the highest 

altitudes are found on the Lake Wales Ridge in the vicinity of 

Archbold Biological Station. The county is located within the 

jurisdiction of the SFWMD and SWFWMD―two of the five 

water management districts in Florida. The more rural part of 

the county, about two-thirds of the total area, is located within 

the SFWMD (fig. 1). The area along the Lake Wales Ridge, 

about one-third of Highlands County, is within the jurisdiction 

of the SWFWMD. All areas of Highlands County within the 

jurisdiction of the SWFWMD are part of the Southern Water 

Use Caution Area (SWUCA), which includes all or part of 

eight counties in southwestern Florida. The SWUCA was 

designated in 1992 in response to the effects that increasing 

groundwater withdrawals had on causing saltwater intrusion 

along the coast, its contributions to reduced flows in the 

upper Peace River, and the declining lake levels in the Lake 

Wales Ridge area of Polk and Highlands Counties (Southwest 

Florida Water Management District, 2006). The SFWMD has 

designated the area including Lake Istokpoga and much of the 

southeastern part of Highlands County as a Water Resource 

Caution Area (WRCA) (Florida Department of Environmental 

Protection, 2006).

Population, Industry, and Land Use

In 1960, the population of Highlands County was about 

21,000. By 2007, the population increased to about 99,000 and 

is projected to reach about 120,000 by 2020 (fig. 3). Most of the 

population is concentrated along the Lake Wales Ridge region, 

whereas the rest of the county is predominantly rural. Out of 67 

counties, Highlands population was ranked 34th largest in the 

State in 2007 (Office of Economic and Demographic Research, 

2008). Highlands County has three incorporated cities: Sebring, 

which is the county seat, Avon Park, and Lake Placid (fig. 1). 

Most of the remaining population lives in the unincorporated 

towns of Brighton, Cornwell, DeSoto City, Fort Basinger, 

Hicoria, Lorida, Spring Lake, and Venus.

Agriculture is the predominant economic activity in 

Highlands County. Various types of agriculture are a major part 

of the local economy, and many are significant water users. 

The most important type of agriculture is the growing of citrus, 

principally oranges and grapefruits. In 2005–06, Highlands 

County ranked second in the State in citrus production, yielding 
4 Hydrogeology and Groundwater Quality of Highlands County, Florida

about 14 percent of the citrus grown in Florida (U.S. Department 

of Agriculture, 2007). Cattle ranching is also a major part of 

agriculture. Ranches are typically extensive and are located 

on the plains east and west of the Lake Wales Ridge. In 2007, 

Highlands County ranked second in the State in the production 

of cattle and calves, with a total of about 111,000 head (http://

www.agcensus.usda.gov/publications/2007/online_highlights/

county_profiles/Florida/index.asp). Truck-farming and other 

agricultural categories are of less importance to the economy 

of the county. The other major economic activity in Highlands 

County is tourism, which is estimated to increase the population of the county by as much as 20 percent during the 

winter months (Highlands County Economic Development 

Commission, oral commun., 2009).

Agriculture, wetlands, urban land, forests, water, and 

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

2004 (fig. 4). Agriculture is the predominant land-use category, 

composing about 54 percent of the county area. Agricultural 

lands are scattered throughout the county, and include citrus 

groves, dairies, pasture, sod, and truck farms. As noted earlier, 

citrus is the primary agricultural product, but is mostly concentrated along the Lake Wales Ridge. Wetlands compose about 18 

percent of the county and generally are found in the eastern and 

southwestern parts of the county. Urban land composes about 

10 percent of the county, and is mostly concentrated around the 

cities of Avon Park, Sebring, and Lake Placid. Water covers 

about 7 percent of the county. Numerous lakes and sinkholes 

are concentrated along the Lake Wales Ridge, although the C-41

C-41A

C-41A

Josephine

Creek

River

Kissimmee

Arbuckle Creek

Istokpoga Cr.

Lake

Istokpoga

Lake

Placid

Lake June

in Winter

Lake

Jackson

Lake Lotela

SW FWMD

S FWMD

S FWMD

SW FWMD

SWFWMD

SFWMD

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

98

98

27

17

70

27

Fort Kissimmee

De Soto

City

Kuhlman

Sebring

Avon

Park

Venus

Brighton

Lake

Placid

Hicoria

Parker

Island

Fort Basinger

Lorida

Cornwell

Spring Lake

Avon Park

Rainfall

Station

0 5 10MILES

27°00’ 0 5 10KILOMETERS

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

WATER MANAGEMENT DISTRICT BOUNDARY

Southwest Florida Water Management District

South Florida Water Management District

EXPLANATION

27°15’

81°15’

ROMP 13

ROMP

14

ROMP

29A

ROMP 43

ROMP 28

ROMP 15

ROMP 43xx

ROMP 28x

Archbold

Biological

Station

STUDY AREA

Figure 1. Location of study area in south-central Florida.
Description of Study Area 5

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

27°15’

81°15’

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

Albers NAD projection 1983

LAND-SURFACE ALTITUDE,

IN FEET ABOVE NGVD 29

HIGH–210

LOW–20

Archbold EXPLANATION

Biological

Station

River

Kissimmee

Brighton

Figure 2. Topography of Highlands County.

Figure 3. Historical and projected population growth 

for Highlands County. From 

U.S. Bureau of the Census 

(1995) and Office of Economic and Demographic 

Research (2008).

60,000

80,000

100,000

120,000

140,000

POPULATION

0

20,000

40,000

1960

YEAR

1970 1980 1990 2000 2010 2020
6 Hydrogeology and Groundwater Quality of Highlands County, Florida

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Sebring

Avon

Park

Lake

Placid

27°00’

27°30’

81°30’ 81°00’

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

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

Albers NAD projection 1983

LAND-USE TYPES

URBAN

WETLAND

WATER

UPLAND FOREST

RANGELAND

AGRICULTURE

MINING

EXPLANATION

Lake

Istokpoga

Lake June

in Winter

Figure 4. Generalized land use in Highlands County, 2004.

largest lake in the county, Lake Istokpoga, is located just 

east of the ridge. Forest covers about 6 percent of the county, 

primarily in the northeastern and western areas. Rangelands 

compose about 5 percent of the county. Unlike Polk County to 

the north, mining areas are nearly nonexistent, composing about 

0.1 percent of the county.

Physiography

Highlands County lies entirely in the mid-peninsular 

physiographic zone described by White (1970). The major 

physiographic features that compose the county are the 

Lake Wales Ridge, Osceola Plain, Bombing Range Ridge, 

DeSoto Plain, Okeechobee Plain, Intra Ridge Valley, and the 

Caloosahatchee Incline (fig. 5). The shape and character of 

these landforms have all been influenced by interactions of 

sea-level changes and karst processes. 

The most prominent topographic feature of the Florida 

Peninsula is the Lake Wales Ridge. This long, narrow ridge 

extends from Lake County south past the Glades-Highlands 

County line. The configuration of the ridge, with wave-cut 

terraces and parallel alignment with present shorelines, 

suggests that these features were developed by wave action 

during periods when sea level was higher (Geraghty and 

Miller, 1980). The morphology of the eastern flank of the Lake 

Wales Ridge was probably controlled by high-energy shoreline 

currents throughout the Pleistocene (and possibly the late 
Description of Study Area 7

Pliocene), as indicated by the sharp topographic relief on the 

eastern side of the ridge (Arthur and others, 2008). In contrast, 

the western side of the ridge is more irregular and slopes off 

more gradually.

Land-surface altitudes on the Lake Wales Ridge are the 

highest in the county and range from about 60 to 210 ft above 

NGVD 29 (fig. 2). In much of the county, the Lake Wales 

Ridge is composed of two secondary ridges separated by the 

Intra Ridge Valley, where altitudes range from about 50 to 

100 ft above NGVD 29 (Choquette and Sepúlveda, 2000). 

Generally maintaining a width of about 2 miles, this valley 

was formed by the dissolution of the underlying limestone 

and contains numerous karst features (White, 1970).

The Lake Wales Ridge forms the surface-water divide 

between the Kissimmee River basin to the east, the Peace River 

basin to the west, and the tributaries to the south that flow into 

Lake Okeechobee. Surface stream drainage is poorly developed 

or absent in most areas (Choquette and Kroening, 2009). 

The Lake Wales Ridge is characterized by numerous surface 

depressions and closed basin lakes. Although many of the lakes 

are in closed depressions and have no surface outlets, some 

surface-water flow occurs between interconnected lakes and 

along the flanks of the ridge (Choquette and Sepúlveda, 2000). 

The Osceola Plain is a broad marine terrace that lies east 

of the Lake Wales Ridge. It is characterized by little relief 

change and generally varies in altitude from about 40 to 80 ft 

above NGVD 29 in Highlands County. A distinctive feature 

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY 27°00’

27°30’

81°30’ 81°00’

27°15’

81°15’

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

Albers NAD projection 1983

0 5 10MILES

0 5 10KILOMETERS

OSCEOLA PLAIN

BOMBING RANGE RIDGE

LAKE

WALES RIDGE

LAKE

WALES

RIDGE

INTRA RIDGE

VALLEY

DESOTO PLAIN

OKEECHOBEE PLAIN

Figure 5. Generalized physiography of Highlands County. From White (1970).
8 Hydrogeology and Groundwater Quality of Highlands County, Florida

within the Osceola Plain is the Bombing Range Ridge. Present 

in southeastern Polk County and extending into northeastern 

Highlands County, this north/south trending sand ridge has a 

maximum altitude of 146 ft near its crest in Highlands County. 

This ridge was probably a marine sand bar when sea level was 

higher (White, 1970).

The Okeechobee Plain occupies southeastern Highlands 

County and has land altitudes that dip gradually to the south 

and generally range from about 20 to 50 ft above NGVD 29. 

The Caloosahatchee Incline in Highlands County borders the 

extreme southeastern part of the Lake Wales Ridge and the 

western part of the Okeechobee Plain. This area is characterized by a long, narrow incline that gently slopes eastward 

and has altitudes that generally range from 30 to 60 ft above 

NGVD 29. White (1970) suggested that the Caloosahatchee 

Incline was the steeper slope at the distal or down-current end 

of a submarine shoal and was preserved during emergence 

because of a low energy environment. The DeSoto Plain is 

a broad, gently sloping area west of the Lake Wales Ridge. 

Land-surface altitudes decrease gradually toward the south and 

range from about 95 ft above NGVD 29 in the northern part of 

the county to about 55 ft above NGVD 29 in the southern part. 

The DeSoto Plain contains many shallow depressions that fill 

with water during the rainy season (Bishop, 1956). 

Surface-Water Features

The study area is divided into three major surface-water 

drainage basins and numerous minor surface-water drainage 

basins. The major surface-water drainage basins are the 

Kissimmee River basin, Peace River basin, and the Fisheating 

Creek basin. These drainage basins, streams, canals, and lakes 

are shown in figure 6.

The Kissimmee River basin is typically subdivided into 

the upper and lower basins. The lower Kissimmee River basin 

includes much of the northern and eastern parts of Highlands 

County. The basin is partially drained by the Kissimmee 

River, the most prominent surface-water feature in the study 

area. The relatively low, flat prairie land lying in the lower 

Kissimmee River basin in Highlands County is characterized 

by relatively shallow lakes (mostly along the Lake Wales 

Ridge) and Lake Istokpoga to the east. Part of the basin also 

drains into Lake Istokpoga, which eventually drains into Lake 

Okeechobee. 

Principal water bodies within the lower Kissimmee River 

basin include Arbuckle Creek, Josephine Creek, Carter Creek, 

Lake Istokpoga, and the lakes along the Lake Wales Ridge. 

Waters from Arbuckle Creek, Josephine Creek, and Carter 

Creek all discharge into Lake Istokpoga. Lake Istokpoga 

drains into the Kissimmee River and the C-41A canal, which 

then drains into Lake Okeechobee. At 44 mi2, Lake Istokpoga 

is the fifth largest lake in Florida (Radin and others, 2005). 

Of the many lakes along the Lake Wales Ridge, some of the 

largest include Lake Lotela, Lake Jackson, Lake Placid, and 

Lake June in Winter.

Most of the Kissimmee River basin is regulated for 

flood-control purposes. To expedite the movement of water 

and provide flood protection for central Florida, channelization of the Kissimmee River began in 1962 and ended in 

1971. The 103-mile-long meandering river was replaced by a 

56-mile-long canal, referred to as C-38 (Florida Department 

of Environmental Protection, 2006). The channelized river 

is about 30 ft deep (U.S. Army Corps of Engineers, 1991). 

The Kissimmee River (C-38) is divided into five pools (pools 

A–E) by a series of combined locks and spillways (Radin and 

others, 2005).

Regulation of the Kissimmee River basin has adversely 

affected the ecology of the watershed. The construction of the 

C-38 canal drained much of the floodplain, stabilized water 

levels, and greatly modified flow characteristics. As a result, 

44 percent of these wetlands were drained and replaced with 

improved and unimproved pasture (Toth and others, 1995). 

This change resulted in a substantial loss of habitat for wading 

birds and plant communities of the river channel and floodplains (Bousquin and others, 2005). Drainage also eliminated 

the natural nutrient-filtering effects of these wetlands, and 

stimulated agricultural development in floodplains and 

adjacent wetlands, all of which contributed to an increase in 

nutrient loading to Lake Okeechobee (Florida Department of 

Environmental Protection, 2006). 

The environmental effects of channelization were quickly 

recognized and calls for restoration of the river began—even 

during the canal construction. Restoration of the Kissimmee 

River began in 1999 with the intent to backfill about 22 

miles of the C-38 canal, remove two water-control structures 

and floodplain levees, and recarve about 9 miles of the river 

channel (Radin and others, 2005). The plan also was to redirect 

flows through the historic river channel and restore the floodplain river ecosystem that was disrupted by channelization.

The Fisheating Creek basin encompasses much of 

southern Highlands County and extends southward into 

northern Glades County, then eastward toward Lake 

Okeechobee. Principal water bodies include Fisheating Creek 

and the C-41 and C-41A canals. Fisheating Creek, which is 

56 miles long, originates in western Highlands County and 

flows south into Glades County where the stream turns east 

and flows into Lake Okeechobee. 

Only a small area in western Highlands County lies 

within the Peace River basin. In this area, water drains into 

Little Charley Bowlegs Creek and eventually into the Peace 

River, which generally flows southward for about 75 miles 

and discharges into the northeastern part of Charlotte Harbor 

in Charlotte County.

Climate, Rainfall, and Evapotranspiration

The climate of Highlands County is classified as humid 

subtropical and is characterized by hot, wet summers and 

mild, relatively dry winters. During the summer months, 

daily maximum air temperatures usually exceed 90 °F. 
Description of Study Area 9

Winter daily minimum air temperatures may occasionally 

drop below freezing. Mean annual temperature for Avon 

Park is 72.0 °F. Minimum and maximum monthly average 

temperatures are 60.6 and 81.2 °F, occurring in January and 

July, respectively. 

Although annual rainfall in Highlands County has averaged 

about 51 inches over the past 30 years, wide variations in 

rainfall occur between years and locations. Rainfall occurs in 

southern Florida during two distinct periods—the wet season 

and the dry season. In most years, about 55 to 60 percent of the 

average annual rainfall occurs from June through September. 

Average monthly rainfall during this period generally ranges 

from about 6 to 8 inches, with June being the wettest month. 

Thunderstorms account for most of the summer rainfall, which 

is usually unevenly distributed throughout the county. These 

storms can produce heavy but localized rainfall, often resulting 

in several inches of precipitation. During the summer and early 

fall, tropical storms and hurricanes can cause widespread excessive rainfall and associated flooding. For example, Hurricanes 

Charley, Frances, and Jeanne, passing through Florida in August 

and September 2004, produced about 13 inches of rainfall in 

Highlands County, and Tropical Storm Fay, passing through 

Florida in September 2008, produced about 6 inches. Winter 

rains are generally associated with large-scale frontal weather 

systems, which are usually of longer duration and greater areal 

uniformity than summer convectional precipitation. However, 

December and January typically are the driest months, with an 

average monthly rainfall of about 2 inches.

River

Kissimmee

Lake

Istokpoga

C-41A

C-41A

Carter Creek

Istokpoga Cr.

Lake

Placid

Lake

June in

Winter

Lake

Jackson

Josephine

Creek

Lake

Lotela

Arbu r ckle C eek

Harney Pond

Canal (C-41)

S65A

S65E

S70

S84

S75

Peace

River

Basin

Fisheating Creek Basin

Kissimmee River Basin

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

0 5 10MILES

27°00’ 0 5 10KILOMETERS

27°30’

81°30’ 81°00’

27°15’

81°15’

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

Albers NAD projection 1983

Figure 6. Major surface-water drainage basins, streams, canals, and lakes in Highlands County.
10 Hydrogeology and Groundwater Quality of Highlands County, Florida

Long-term rainfall data are available for the Avon Park and 

Archbold Biological rainfall stations in Highlands County (figs. 1 

and 7). Mean annual rainfall at the Avon Park station, obtained 

from National Oceanic and Atmospheric Administration 

records (1931–2007), is 52.28 inches. Mean annual rainfall 

at the Archbold Biological Station (Hilary Swain, Archbold 

Biological Station, written commun., 2009) from 1932 to 2007 

is 53.37 inches (excluding 1 year for which data are unavailable). Thirty-year mean annual rainfall totals from 1978 to 

2007 at the Avon Park and Archbold Biological rainfall stations 

were 50.43 and 52.19 inches, respectively. Although a considerable amount of variation in annual rainfall occurs from year 

to year, cycles of wet and dry periods are present, as indicated 

by a 5-year moving average shown in figure 7. No consistent 

linear trends in annual rainfall rates are present for the period 

of record at the two rainfall stations. Statistical analysis 

(Kendall’s tau) also indicates that no long-term trend in rainfall 

has resulted at the Avon Park or Archbold Biological rainfall 

stations for the period of record (table 1).

Even with abundant rainfall, Florida is not immune to 

drought, and extended periods of deficient rainfall do occur. 

The lowest annual rainfall totals recorded at the Avon Park 

and Archbold Biological rainfall stations occurred in 2000, 

and were 26.10 and 27.31 inches, respectively. Average 

rainfall for the 2-year period (2006–07) was 35.64 inches at 

Avon Park and 40.86 inches at Archbold Biological Station. 

The highest annual rainfall totals occurred in 1953 and were 

80.08 and 76.73 inches at Avon Park and Archbold Biological 

Station, respectively. 

Much of the precipitation in Florida is recycled directly 

back into the atmosphere by evapotranspiration. The largest 

percentage of water lost annually from the area is through 

1930 1940 1950 1960 1970 1980 1990 2000 2010

60

70

80

90

0

20

30

40

60

70

80

90

RAINFALL, IN INCHES

10

50

YEAR

AVON PARK, 1931–2007

Mean Rainfall = 52.28 inches per year

Minimum Rainfall = 26.10 inches

Maximum Rainfall = 80.08 inches

5-YEAR

MOVING AVERAGE

1930 1940 1950 1960 1970 1980 1990 2000 2010

60

70

80

90

0

10

20

30

40

60

70

80

90

RAINFALL, IN INCHES 50

YEAR

ARCHBOLD BIOLOGICAL STATION, 1932–2007

Mean Rainfall = 53.37 inches per year

Minimum Rainfall = 27.31 inches

Maximum Rainfall = 76.73 inches

5-YEAR

MOVING AVERAGE

Figure 7. Annual rainfall at Archbold Biological Station and Avon Park, Florida. Rainfall data from the 

Archbold Biological Station obtained from Hilary Swain (Archbold Biological Station, written commun., 

2009). Rainfall data from the Avon Park station obtained from National Oceanic and Atmospheric 

Administration records. 
Description of Study Area 11

evapotranspiration, defined as the combined processes of 

evaporation of water from land and water surfaces and 

transpiration by plants. The rate of evapotranspiration is 

controlled by several factors, primarily net solar radiation, 

wind speed, relative humidity, surface area of open water 

bodies, density and type of vegetation cover, available 

soil moisture, root depth, water-table depth, and season. 

The term potential evapotranspiration is a measure of the 

ability of the atmosphere to remove water from the surface 

through the processes of evaporation and transpiration 

assuming no limit on water supply. Actual evapotranspiration is the quantity of water that is actually removed from 

a surface due to the processes of evaporation and transpiration. Actual evapotranspiration is always less than or equal 

to potential evapotranspiration.

Estimated average monthly potential evapotranspiration 

from 1996 to 2007 for Highlands County is shown in figure 8 

(Michael Holmes, U.S. Geological Survey, written commun., 

2009). The methods used to create these values are described 

in Jacobs and others (2008). Average monthly potential 

evapotranspiration is lowest in December (1.8 inches) and 

is followed by rapidly increasing rates with increasing solar 

radiation and temperatures during the spring. The highest 

monthly evapotranspiration (greater than 6 inches) occurs from 

May to August, and then decreases steadily into December. 

Although difficult to quantify, the upper and lower limits 

of annual evapotranspiration can be estimated. The upper 

limit of evapotranspiration is approximately equal to the rate 

at which water can evaporate from a free-water surface and 

is highest in the lakes, swamps, and marshes where water is 

near or above land surface much of the time (Tibbals, 1990). 

Actual lake evaporation measured at Lake Starr in Polk County 

during August 1996 to July 1998 was 57.08 and 55.88 in/yr, 

respectively (Swancar and others, 2000). Also defining the 

generalized upper limits of evapotranspiration is the estimated 

potential evapotranspiration for the county from 1996 to 2007

(fig. 8). Average total potential evapotranspiration for this 

period was 53.17 in/yr (Michael Holmes, U.S. Geological 

Survey, written commun., 2009). 

Table 1. Results of trend anaysis for rainfall stations and long-term observation wells in Highlands County.

[Locations of wells and rainfall stations shown in figure 11. USGS, U.S. Geological Survey; SA, surficial aquifer; IAS, intermediate aquifer system; 

UFA, Upper Floridan aquifer; NA, not applicable]

Rainfall 

station 

(RS) or well 

number

USGS site 

identification 

number

Station name Aquifer

Bottom of casing

(feet below land 

surface)

Depth of well

(feet below land 

surface)

Period of 

record 

analyzed

p-value Kendall’s 

tau

RS Not applicable Archbold Biological Station NA NA NA 1932-2007 0.7212 -0.0285

RS Not applicable Avon Park NA NA NA 1931-2007 .2952 -.0817

1 270157081203101 H-15A SA 19 23 1975-2008 .1494 .0129

43 271226081194301 Bairs Den SA 28 35 1977-2008 .0000 .0906

53 271330081113401 HIF-37 Sun Ray Farms UFA 619 1,450 1982-2008 .0074 -.2880

67 271559081242501 Lake Grove Rd. SA 13 23 1972-2008 .0000 -.0629

88 272207081260402 ROMP 28 Intermediate IAS 370 420 1996-2008 .0009 .0963

89 272207081260404 ROMP 28 Suwannee UFA 485 600 1996-2008 .0000 .1194

103 272504081120101 H-11A SA 13 16 1975-2008 .0092 -.0226

105 272512081122901 HIF-13 Meztger UFA NA 1,106 1982-2008 .6376 -.0509

126 272835081251701 Maranatha Village UFA NA 841 1979-2008 .8061 -.0239

166 273704081245501 Richards IAS 140 260 1986-2008 .0687 -.1889

J F M A M J J A S O N D

Average annual potential evapotranspiration

1996-2007 = 53.17 inches

0

1

2

3

4

5

6

7

POTENTIAL EVAPOTRANSPIRATION, IN INCHES

MONTH

Figure 8. Average monthly potential evapotranspiration for 

Highlands County, 1996-2007. From U.S. Geological Survey (2009).
12 Hydrogeology and Groundwater Quality of Highlands County, Florida

The lower limits of evapotranspiration occur in areas 

that have well drained soils and deep water tables. Tibbals 

(1990) related evapotranspiration to water-table depth in 

east-central Florida and estimated that the minimum rate 

of evapotranspiration occurred where the water table was 

greater than 13 ft below land surface. At a Bahia grass and 

palmetto site in eastern Polk County where the water table 

is shallow, actual annual evapotranspiration ranged from 

30.2 to 40.2 in/yr during 2001–07 (D.M. Sumner, U.S. 

Geological Survey, written commun., 2009). In a deforested 

area along the Lake Wales Ridge in Orange County, Sumner 

(1996) determined that annual evapotranspiration was 

about 27 inches. This site probably represents a minimum 

evapotranspiration value for central Florida because of the 

presence of shallow-rooted plants, rapidly drained soil, and a 

relatively deep water table.

Water Use

Highlands County relies heavily on groundwater for its 

water supply, and groundwater use has increased substantially 

over the past several decades. In 1965, groundwater withdrawals in the county were about 37 Mgal/d (fig. 9). In 2000, 

withdrawals totaled about 157 Mgal/d, an increase of more 

than 300 percent (Marella, 2009). In 2005, total groundwater 

use declined to about 107 Mgal/d, largely as a result of above 

average rainfall of about 60 inches. The dominant factor causing 

this increase in water use over the past 40 years has been the 

expansion of agriculture or, more specifically, the expansion of 

the citrus industry. Water use from agricultural irrigation has 

increased dramatically, from 32 Mgal/d in 1965 to 95 Mgal/d 

in 2005 (fig. 9). Water use for public supply, the second largest 

water-use category for Highlands County, increased from 4 to 

about 9 Mgal/d from 1965 to 2005 (Marella, 2009).

Of the six water-use categories, agricultural irrigation 

accounted for the largest percentage of groundwater withdrawn 

in 2005 (fig. 10). Of the total groundwater withdrawn, about 89 

percent was used for agriculture, 8 percent for public supply, 

2 percent for recreational irrigation, 1 percent for domestic, 

and less than 0.1 percent for both commercial/industrial and 

thermoelectric power generation. The Upper Floridan aquifer is 

the primary source of water supply, but the surficial aquifer and, 

locally, the intermediate aquifer system provide drinking water 

for rural domestic wells and some irrigation and public supply.

Figure 9. Historical groundwater use in Highlands County, 1965-2005. From Marella (2009).

COMMERCIAL/INDUSTRIAL

THERMOELECTRIC

RECREATIONAL IRRIGATION

DOMESTIC

PUBLIC SUPPLY

AGRICULTURE

TOTAL GROUNDWATER USE

120

140

160

0

40

60

80

GROUND-WATER USE, IN MILLION GALLONS PER DAY

20

100

YEAR

160

180

0

20

40

60

80

120

140

100

1960 1970 1980 1990 2000 2010

1.5

2.0

2.5

0

3.0

GROUND-WATER USE, IN MILLION GALLONS PER DAY

0.5

1.0

YEAR

6

7

8

10

0

1

2

3

4

5

1960 1970 1980 1990 2000 2010

9
Methods of Data Evaluation and Collection 13

The principal source of groundwater supply in Highlands 

County is the Upper Floridan aquifer. As of 2005, about 89 

percent of the groundwater withdrawn from the county was 

obtained from this aquifer. The surficial aquifer was the source 

for about 9 percent of groundwater (M. Beach, Southwest 

Florida Water Management District, written commun., 2009). 

Most of the water from the surficial aquifer is obtained from 

wells along the Lake Wales Ridge. The intermediate aquifer 

system is only a minor source of water supply, contributing about 2 percent of the total groundwater withdrawn 

(M. Beach, Southwest Florida Water Management District, 

written commun., 2009). 

Although poorly documented, little groundwater is 

withdrawn from the Lower Floridan aquifer for water supply 

in Highlands County. In the northern part of the county 

where the top of this aquifer is closer to land surface, some 

wells may be open to both the Upper Floridan and Lower 

Floridan aquifers to increase well yields. In much of the 

county, however, the increased mineralization of water from 

the Lower Floridan aquifer has prevented it from becoming a 

source of water supply. 

Moderate amounts of water are being withdrawn from 

surface-water sources, which are primarily used for agricultural irrigation. Surface-water withdrawals in the study area 

are largely from a network of canals augmented by groundwater and rainfall. Of the 153.93 Mgal/d of surface water 

withdrawn in 1975, 58.7 Mgal/d was used for agricultural 

irrigation with most of the remainder used for power generation. In 2005, a total of only 11.45 Mgal/d of surface water 

was withdrawn, of which 10.94 Mgal/d was used for agricultural irrigation (Marella, 2009).

Methods of Data Evaluation 

and Collection

This section describes the types of well records and the 

site numbering used in this report. In addition, the collection 

and analyses of geologic and geophysical-log, water-level, 

and water-quality data are discussed. Finally, the collection of 

quality-assurance samples is described. 

A network of monitoring wells was established for the 

collection of groundwater samples from the surficial aquifer, 

intermediate aquifer system/intermediate confining unit, and 

Upper Floridan aquifer. Data-collection sites were inventoried 

based on a review of wells and available water-quality data in 

the study area. Additional wells added to the inventory were 

obtained from well permits, well construction reports, and the 

files of the USGS. The locations of wells used for data collection, including wells used for the collection of water-quality 

data, are shown in figure 11.

Well Records and Site Identification

Well records in Highlands County are maintained by 

several government agencies. The USGS, SWFWMD, and 

SFWMD have computerized databases and paper files on 

wells that contain water-quality, water-level, geologic, hydrologic, geophysical-log, and water-use data. The USGS assigns 

a unique 15-digit number based on latitude and longitude that 

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 (using three digits beginning with 0), minutes, 

and seconds of longitude; and the last two digits denote a 

sequential number to identify wells within a 1-second grid. 

For example, well 271114081122401 is the first well inventoried at latitude 27°11′ 14′′N, longitude 081°12′24′′W. Once 

assigned, a site identification number does not change even 

though the locations determined by latitude and longitude may 

be revised later. 

The FGS keeps records of geologic data throughout the 

State, including more than 100 wells in Highlands County. 

Well data from the files of the FGS are identified using their 

“W” prefix followed by a number. 

Information from selected wells used in this study is 

given in appendix 1. Wells included are completed in the 

surficial aquifer, intermediate aquifer system/intermediate 

confining unit, and Floridan aquifer system. Included in this 

appendix are the types of data collected during this study, well 

construction data, and general information about the wells. 

A map reference well number up to three digits is used to 

identify wells throughout this report.

Figure 10. Total groundwater use, by category, for 2005. 

From Marella (2009).

RECREATIONAL

IRRIGATION

2 %

PUBLIC

SUPPLY

8 %

DOMESTIC

1 %

THERMOELECTRIC and

COMMERCIAL / INDUSTRIAL

less than 0.1 %

AGRICULTURE

89 %

HIGHLANDS COUNTY

107 million gallons per day
14 Hydrogeology and Groundwater Quality of Highlands County, Florida

Geologic and Geophysical-Log Data Collection

Geologic and geophysical log data from about 240 

wells were used to construct various hydrogeologic maps 

and sections of the surficial aquifer, the intermediate aquifer 

system/intermediate confining unit, and the Upper Floridan 

aquifer in the study area. This information was obtained from 

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

published reports, including geophysical logs and lithologic 

descriptions of well cuttings by geologists and drillers. 

Because of the scarcity of geologists’ logs and geophysical log 

data in some parts of the county, in some instances, drillers’ 

logs were used to help construct the hydrogeologic maps. 

Caution was taken when using these data, and only drillers’ 

logs with supporting geologic data were assumed to be reliable 

and were used.

Water-Level Data Collection

Water-level data from a network of wells distributed 

across Highlands and adjacent counties were used to construct 

generalized potentiometric surface maps of the Upper Floridan 

aquifer. Water-level data were collected semiannually from 

the monitoring well network in May and September 2007 to 

Figure 11. Location of wells used for data collection. Well numbers and information shown in appendix 1.

98

98

27

17

70

27

River

Kissimmee

Lake

Istokpoga

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

27°00’ 0 5 10KILOMETERS

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

WELL LOCATION

AND NUMBER

EXPLANATION

14

11 13

32

17 18

12 14

27

25

41

33

29

26

24

20

15 9

8

7 6

5

4

3

2

50

43

66

65

1

49

36

28

23

21

19

39 38 35 31

58 56

55 47

52

37 34

30

22

16

94

84

71

70

69

61 60 59

53

97

83

112

105

103 98

96

121

118 114

125 124

111

108

120

115

109

122

119

117

78 74

73

64

99

95

81 80

79

76

104

100

86

82

75 77

72 68

63 67

51 48

141

131

130 129

144 145

137

146 147

136

85

127

123

113 110

107

106

126

139 133

134

135

140

132

156

148

149

142

158

138

116

163

161 164

157

171

170 168 169

167 166 165

172

150

143

44

45

46

173

174

175

159

160

162

101 102

40

42

57

10

152 155

153 154

87, 88, 89,

90, 91, 92, 93

151

128

62

54
Methods of Data Evaluation and Collection 15

depict the seasonal changes in water-level distribution and 

groundwater-flow patterns in the Upper Floridan aquifer. 

Potentiometric surface maps of the Upper Floridan aquifer 

in northern and central Florida are published semiannually 

by the USGS in cooperation with the SFWMD, SJRWMD, 

SWFWMD, and other local agencies.

Water-Quality Data Collection and Analysis

Water samples were collected by the USGS and 

State agencies from 129 wells between 2000 and 2008 to 

characterize groundwater quality in the Highlands County 

area (apps. 2 and 3). Water-quality samples from 58 wells 

were collected specifically for this study by the USGS and 

analyzed for common inorganic constituents and nutrients, 

primarily during 2006–08. Additionally, water-quality data 

from 71 wells collected by the FDEP, SFWMD, SWFWMD, 

and Highlands County during 2000–08 were also used and 

presented in this report. Although most of the groundwater 

samples were collected in Highlands County, a few samples 

were also collected in adjacent DeSoto, Hardee, Glades, 

Okeechobee, and Polk Counties.

Water samples collected for this study were obtained 

from irrigation wells, public-supply wells, domestic wells, 

dedicated monitoring wells, and free-flowing wells. Most 

of the wells sampled were regularly used and equipped with 

permanently installed pumps. These wells were sampled after 

allowing the pump to run for about 10 minutes and after field 

properties had stabilized. Wells that had not been used recently 

were purged until at least three casing volumes of water were 

removed, and temperature, specific conductance, and pH had 

stabilized. 

Water samples were collected following standard USGS 

protocol (Wilde, 2008). Field measurements of specific 

conductance, temperature, and pH were recorded at all well 

sites using a multiparameter sonde in a flow-through chamber.

The flow-through chamber, which is closed to ambient air, 

prevents the exchange of carbon dioxide and oxygen between 

the collected water and the atmosphere. The loss of carbon 

dioxide from or the gain of oxygen to groundwater during 

field measurements can affect the pH and specific conductance 

values. Alkalinity was determined by titration with sulfuric 

acid using the incremental titration method.

Water samples were collected for laboratory analysis of 

major inorganic constituents and physical characteristics, trace 

metals, and nutrients. Major ions and other physical characteristics include calcium, magnesium, potassium, sodium, 

chloride, fluoride, sulfate, alkalinity, silica, water temperature, 

specific conductance, total dissolved solids, pH, and hardness 

(app. 2). Trace metals and nutrients include strontium, iron, 

ammonia as nitrogen (ammonia), nitrite as nitrogen (nitrite), 

nitrate plus nitrite as nitrogen (nitrate), total nitrogen, phosphorus, and orthophosphate as phosphorus (app. 3). In this 

report, the combined concentration of nitrite plus nitrate 

reported by the laboratory is referred to as “nitrate,” because 

nitrite generally was below the detection limits. A list of the 

constituents analyzed in groundwater in Highlands County and 

the analytical methods used are given in table 2.

Samples collected to determine analyses of major inorganic constituents and nutrients were filtered through a 0.45-μ 

pore-size disposable encapsulated filter. Cation and trace 

metal samples were collected in acid-washed polyethylene 

bottles and acidified with 2 mL of 4.5N nitric acid to adjust 

the sample pH to less than 2. Nutrient samples were collected 

in a brown polyethylene bottle and packed in ice. All water 

samples were shipped to the USGS National Water-Quality 

Laboratory in Denver, Colorado.

Table 2. Analytical methods and drinking-water standards for 

inorganic analytes collected by the U.S. Geological Survey.

[Concentrations shown in milligrams per liter, except for iron and stronium 

which are in micrograms per liter. Method of analysis: C, colorimetry; 

G, residue evaporation at 180 degrees Celsius; °C, ion-exchange 

chromatography; ICP, induction-coupled argon plasma atomic emission 

spectrometry; ISE, ion-selective electrode; T, inflection-point titration. 

Drinking-water standards: MCL, maximum contaminant limit (Florida 

Primary Drinking Water Standards); SS, Florida Secondary Drinking Water 

Standards.

Constituent Method of 

analysis 1

Reporting 

limit 1,2

Drinking water 

standards 3

Alkalinity T 5.0 None

Ammonia, as nitrogen C .02 None

Calcium ICP .04 None

Chloride IC .12 250 (SS)

Fluoride ISE .12 4.0 (MCL), 2.0 (SS)

Iron ICP 8.0 300 (SS)

Magnesium ICP .02 None

Nitrate C .04 10 (MCL)

Nitrite C .002 1 (MCL)

Phosphorus C .006 None

Phosphorus, ortho, as

 phosphorus C .006 None

Potassium ICP .02 None

Silica ICP .02 None

Sodium ICP .12 160 (MCL)

Strontium ICP .4 None

Sulfate IC .18 250 (SS)

Total dissolved solids G 10 500 (SS)

1Fishman and Friedman (1985) and U.S. Geological Survey (USGS) 

National Water Quality Laboratory, Denver, Colorado.

2Analytical reporting limits are for USGS National Water Quality 

Quality Laboratory, Denver, Colorado. Reporting limits for other laboratories 

may differ.

3Florida Department of Environmental Protection (2008).
16 Hydrogeology and Groundwater Quality of Highlands County, Florida

Quality-Assurance Samples 

 Quality-assurance samples were collected to ensure 

the integrity of water-quality samples. Analysis of qualityassurance samples provides information about the potential 

for sample contamination during collection, processing, and 

laboratory analysis. Quality assurance for water samples 

included replicate groundwater samples and field equipment 

blank samples. Replicate samples consist of two or more sets 

of samples collected concurrently so that both samples are 

assumed to have identical chemical compositions. Replicate 

samples were used to measure variability and precision characteristics associated with sampling and analytical procedures. 

Field equipment blanks provide information on possible 

contamination introduced to the sample during cleaning, 

collection, and processing of the sample in the field (Francy 

and others, 2005). About 10 percent of the water samples 

collected during this study was quality-assurance samples 

consisting of both equipment blanks and replicate samples.

Geologic Framework 

Highlands County is underlain by sediments of 

Cenozoic age to a depth of about 5,000 ft below land surface 

(Bishop, 1956; Chen, 1965). These sediments consist 

primarily of sand, clay, phosphate grains, carbonates (limestone and dolostone), and evaporites (gypsum and anhydrite). 

Geologic units corresponding to these sediments, 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. 12). All of the geologic 

units that are exposed (crop out) at the surface are composed 

of unconsolidated siliciclastic sediments of Pliocene to 

Holocene age (fig. 13).

Figure 12. Relation of stratigraphic 

and hydrogeologic units. Modified 

from Spechler and Kroening (2007).

GEOLOGY

AND LITHOLOGY SERIES STRATIGRAPHIC UNIT HYDROGEOLOGIC UNIT

Undifferentiated Sand

surficial deposits

Holocene and

Pleistocene Surficial aquifer

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Suwannee

Limestone

Ocala

Limestone

Avon Park

Formation

Oldsmar

Formation

Cedar Keys

Formation

Cypresshead

Formation

Peace River

Formation

Arcadia

Formation

Nocatee

Member

Sand, clay

Phosphate,

clay, sand,

limestone,

and

dolostone

Limestone

and

dolostone

Limestone and

dolostone with some

intervals containing

inclusions of gypsum

and anhydrite

Limestone and

dolostone with

beds of gypsum

and anhydrite

Sub-Floridan

confining unit

Confining unit

upper Arcadia aquifer

(Zone 2)

Confining unit

lower Arcadia aquifer

(Zone 3)

Confining unit

Upper permeable

zone

Semi-confining

unit

Lower permeable zone (Avon Park

permeable zone)

Middle confining units

I, II, and/or VI

Lower

Floridan

aquifer

Floridan aquifer system

Upper Floridan aquifer

Intermediate aquifer system or

Intermediate confining unit

Hawthorn

Group

Boulder

Zone
Geologic Framework 17

Some differences are present between the geologic 

nomenclature used in earlier water-resource assessments 

of Highlands (Bishop, 1956) and adjacent counties (Pride 

and others, 1966; Stewart, 1966; Wilson, 1977) and those 

used in this report. 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, the term Lake City Limestone was 

abandoned, and all of the lithologic units within the Lake 

City Limestone were reclassified as Avon Park Limestone. 

Miller (1986) also renamed the unit the Avon Park Formation, 

because it contained appreciable amounts of rock types other 

than limestone. The Ocala Group, which included the Inglis, 

Williston, and Crystal River Formations, is 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). Two formations were introduced to the 

Hawthorn Group (Scott, 1988)—the Arcadia Formation and 

the Peace River Formation. Two members were named in the 

Arcadia Formation—the Tampa Member and Nocatee Member. 

Qu

TQuc

Tc

TQd

TQsu

TQd

TQsu

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

0 5 10MILES

27°00’ 0 5 10KILOMETERS

27°30’

81°30’ 81°00’

27°15’

81°15’

PLEISTOCENE / HOLOCENE

Qu Undifferentiated sediments

PLIOCENE

Tc Cypresshead Formation

TQsu

TQd

TQuc

PLIOCENE / PLEISTOCENE

Shelly sediments of

Plio-Pleistocene age

Dunes

Reworked Cypresshead

Formation

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

Albers NAD projection 1983

EXPLANATION

Figure 13. Geologic map of Highlands County. From Scott and others (2001).
18 Hydrogeology and Groundwater Quality of Highlands County, Florida

Stratigraphy

The basal Tertiary unit within the study area is the Cedar 

Keys Formation of late Paleocene age (fig. 12). It consists 

primarily of dolomite and evaporites with minor amounts of 

limestone (Chen, 1965). The evaporites are present as thick 

massive beds in the lower part of the formation and generally 

decrease toward the top of the formation. The Cedar Keys 

Formation has very low permeability and, thus, functions as 

the sub-Floridan confining unit at the base of the Floridan 

aquifer system. The top of the Cedar Keys Formation is about 

2,900 to 3,550 ft below NGVD 29 in Highlands County 

(Miller, 1986) and has a thickness of about 1,600 ft (Chen, 

1965). Conformably overlying the Cedar Keys Formation 

is the Oldsmar Formation of Eocene age. The Oldsmar 

Formation consists of a sequence of white to gray, micritic 

limestone and interbedded tan to light-brown crystalline 

dolomite. Thin beds of chert and evaporites are present 

within the unit (Miller, 1986). The top of the Oldsmar 

Formation is about 1,800 to 2,200 ft below NGVD 29 in 

Highlands County (Miller, 1986). 

The middle Eocene Avon Park Formation, a thick 

sequence of marine limestone and dolostone, conformably 

overlies the Oldsmar Formation. The limestone is generally 

tan to light brown, poorly to well indurated, fossiliferous, 

skeletal wackestone, grainstone, or packstone with minor 

mudstone. Porosity is primarily intergranular (Arthur and 

others, 2008). The limestone can be interbedded with 

dark-brown to tan, very fine- to coarse-grained, vuggy, 

fossiliferous dolostone. Thick intervals containing primarily 

dolostone, but in some places interbedded with limestone, 

are commonly present in the middle to lower Avon Park 

Formation. The Avon Park Formation typically contains a 

zone that is highly fractured, particularly in the dolomitic 

units. This zone is highly transmissive and produces some 

of the highest volumes of water from the Upper Floridan 

aquifer. Gypsum and anhydrite also are present in the 

lower parts of the formation, either as bedded deposits or 

as nodules, intergranular or pore-filling material in the 

carbonate rocks. Foraminifera characteristic of the Avon Park 

Formation are the cone-shaped Dictyoconus sp. The top of 

the Avon Park Formation ranges from about 450 ft below 

NGVD 29 in the northeastern part of the county to about 

950 ft below NGVD 29 in the southern part (Arthur and 

others, 2008). The thickness of the formation ranges from 

about 1,200 to 1,400 ft (Miller, 1986).

An erosional unconformity separates the Avon Park 

Formation from the overlying Ocala Limestone of late 

Eocene age (Stewart, 1966). The Ocala Limestone consists 

primarily of white to cream, soft, poorly consolidated, 

fossiliferous, carbonate mud-rich limestone. Two principal 

lithofacies are present within the Ocala Limestone, as 

described by Ward and others (2003): (1) large benthic 

foraminiferal (Nummulities and Lepidocyclina) wackestone 

with a soft micritic matrix; and (2) poorly indurated, large 

benthic-foraminiferal, mud-dominated packstone. Other 

fossils in these lithofacies include planktic foraminifera, 

small benthic foraminifera, bivalves, echinoids, bryozoans, 

ostracodes, and planktic crinoids (Ward and others, 2003). 

The top of the Ocala Limestone ranges from about 300 ft 

below NGVD 29 in the northwestern part of the county to 

about 675 ft below NGVD 29 in the extreme southwestern 

part (Arthur and others, 2008). The thickness of the formation is relatively uniform, ranging from 300 to 400 ft (Arthur 

and others, 2008).

Unconformably overlying the Ocala Limestone is the 

Suwannee Limestone of early Oligocene age. The limestone 

is white to tan, poorly to well indurated, mostly soft, fossiliferous grainstone, packstone, and wackestone. The formation 

locally contains dolomitized or silicified zones and may 

contain small amounts of fine-grained quartz sand (Stewart, 

1966). Porosity is variably moldic and intergranular. 

The Suwannee Limestone has undergone extensive erosion 

and is absent in much of the eastern part of the county. 

Where present, the thickness of the formation ranges from 

less than 50 ft to about 150 ft (Arthur and others, 2008). 

The top of the Suwannee Limestone ranges from about 200 ft 

below NGVD 29 in the northwestern part of the county 

to about 600 ft below NGVD 29 in the southwestern part 

(Arthur and others, 2008). 

Unconformably overlying the Suwannee Limestone 

is the Hawthorn Group of late Oligocene to Miocene age 

(Scott and others, 2001). The Hawthorn Group generally 

consists of phosphatic siliciclastics and carbonates that range 

in thickness from about 150 to 600 ft across the study area 

(Arthur and others, 2008). The high phosphate and clay 

content results in intervals of high activity on natural gamma 

ray logs that are characteristic of the Hawthorn Group. 

In Highlands County, the Hawthorn Group consists of two 

formations—the Arcadia Formation, which includes the 

Nocatee Member, and the overlying Peace River Formation. 

The Tampa Member of the Arcadia Formation and the Bone 

Valley Member of the Peace River Formation are absent 

in Highlands County, but present in adjacent Polk and 

Hardee Counties.

The Arcadia Formation is composed of limestone 

and dolostone containing varying amounts of quartz sand, 

clay, and phosphate grains. Although limestone is present, 

dolostones are most common. Thin beds of quartz sand 

and clay are scattered throughout the section. Phosphate 

concentrations are highly variable, ranging from 10 to 25 

percent (Scott, 1988). The porosity of this unit is generally 

intergranular and moldic. The top of the Arcadia Formation 

ranges from about 50 ft to 270 ft below NGVD 29, and the 

thickness of this unit ranges from about 150 to 450 ft (Scott, 

1988; Arthur and others, 2008).

The lowermost sediments of the Arcadia Formation 

form the Nocatee Member. The Nocatee Member is a 

predominantly siliciclastic unit containing an interbedded 

sequence of quartz sands, clays, and carbonates all containing 
Geologic Framework 19

variable amounts of phosphate (Scott, 1988). Phosphate 

concentrations are variable, ranging from about 1 to 10 

percent (Scott, 1988). Clay beds are common. The unit is 

absent in parts of eastern Highland County. Where present, 

the top of the Nocatee Member ranges from about 150 ft to 

more than 525 ft below NGVD 29 (Arthur and others, 2008). 

The thickness of the unit ranges from about 50 ft to more than 

100 ft. 

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 are 

the predominant lithology in this unit, composing more 

than two-thirds of the formation (Scott, 1988); however, 

carbonate bed occurrence increases with depth. The Peace 

River Formation is present throughout all of Highlands 

County. The top of the unit generally ranges from about 

25 ft above to 200 ft below NGVD 29 (Arthur and others, 

2008). The thickness of the unit ranges from about 60 to 

120 ft (Arthur and others, 2008).

Overlying the Hawthorn Group are the undifferentiated 

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

include the Cypresshead Formation (fig. 12). The undifferentiated surficial deposits consist of varying percentages of 

sand, clay, and shell. The upper part of this unit is composed 

of unconsolidated, fine to medium-grained quartz sand with 

minor organic material. The lower unit contains sand and 

some shell fragments intermixed with clay layers. These 

deposits are present throughout all of Highlands County and 

reach their maximum thickness of more than 300 ft under the 

Lake Wales Ridge.

Sinkholes 

Sinkholes are a common topographic feature in the study 

area and exist as closed depressions in the land surface formed 

by dissolution of underlying rocks or by the collapse of the 

roofs of underground caverns. Sinkholes typically develop in 

areas where groundwater recharge rates are relatively high and 

where the overlying siliciclastic sediments are relatively thin 

or permeable. Although sinkholes in all stages of development are present in Highlands County, most occur along 

the Lake Wales Ridge, and range from small depressions to 

large lakes. The locations of sinkholes and depressions in 

Highlands County are shown in figure 14. These features, 

which were delineated from USGS topographic maps, 

include lakes, ponds, and topographic depressions, as well as 

manmade features.

Along much of the Lake Wales Ridge, lakes commonly 

occupy the depressions created by sinkhole collapse. Some 

of the smaller lakes are the result of a single sinkhole, 

whereas others are a coalescent group of smaller sinks. 

Continuous high-resolution seismic-reflection surveys of 

lakes on the Lake Wales Ridge indicate that many of these 

lakes probably were formed by subsidence (Lee and others, 

1991; Evans and others, 1994; Tihansky and others, 1996; 

Sacks and others, 1998).

Sinkholes can form a direct connection from land 

surface to the underlying aquifers, allowing surface water 

to move directly into the aquifers. Although the bottoms of 

some of these sinkhole lakes have accumulated substantial 

organic-rich deposits with relatively low permeability 

(Geraghty and Miller, 1980; Tihansky and others, 1996), 

most of the lakes have sandy bottoms with relatively high 

permeability and provide a good hydraulic connection to the 

underlying aquifers (Geraghty and Miller, 1980).

The dissolution of carbonate rocks by acidic water 

is the cause of the collapse or subsidence that creates 

sinkholes. As rain falls through the atmosphere, it absorbs 

some carbon dioxide and other gases and becomes slightly 

acidic. Additional carbon dioxide is absorbed as rainwater 

percolates through the soil and reacts with decaying vegetation, becoming a weak carbonic acid. This water passes 

through insoluble sediments until it reaches the underlying 

carbonate rocks. Dissolution of rocks is enhanced where the 

flow of water is concentrated. The most common features 

that concentrate the downward flow of water are along 

fractures or joints. These small solution openings slowly 

become larger as more of the acidic water moves through 

the aquifer. Over a long period of time, the enlarged spaces 

eventually form a network of caves, pipes, and other types 

of conduits, all of which collect and channel large volumes 

of groundwater. As solution caverns enlarge, their roofs 

in some instances cannot support the overlying sediment 

and collapse, forming a sinkhole. Sinkholes form slowly 

and expand gradually under natural conditions; however, 

sinkholes can expand more rapidly in areas of heavy 

groundwater withdrawals.

The type and frequency of sinkhole subsidence activity 

depend on the composition and thickness of overburden 

materials, the degree of solution within the underlying 

carbonate rocks, and local hydrologic conditions (Tihansky, 

1999). Three general types of sinkholes occur:

• Dissolution sinkhole depressions in the limestone 

surface caused by chemical erosion of limestone;

• Cover subsidence sinkholes formed as overburden 

materials gradually infill subsurface cavities; and

• Cover-collapse sinkholes, also formed by movement 

of cover material into subsurface voids, but characteristically forming abruptly (Tihansky, 1999).

The latter two types, according to Sinclair and Stewart (1985), 

generally are present in Highlands County where there is a 

thick clastic unit overlying the limestone.
20 Hydrogeology and Groundwater Quality of Highlands County, Florida

Hydrogeology

The hydrogeologic system in Highlands County consists 

of a thick sequence of sedimentary rocks that include sands, 

clays, and carbonates. These lithostratigraphic units form a 

multilayered sequence of aquifers and confining units. Three 

hydrogeologic units present in Highlands County, in order of 

increasing depth, are the surficial aquifer, the intermediate 

aquifer system/intermediate confining unit (IAS/ICU), and the 

Floridan aquifer system. The surficial aquifer is the uppermost 

water-bearing unit and underlies all of Highlands County. 

The IAS/ICU, which contains sediments of lower permeability, restricts the movement of water between the overlying 

and underlying aquifers. The Floridan aquifer system consists 

of the Upper Floridan aquifer and Lower Floridan aquifer, 

which are separated by less-permeable middle confining 

units I, II, and/or VI (Miller, 1986). The base of the Floridan 

aquifer system is marked by low-permeability limestone and 

dolostone that contain considerable gypsum and anhydrite of 

the upper Cedar Keys Formation. Variations in the distribution, thickness, and dip of the hydrogeologic units based on 

geophysical and geologic logs (locations shown in fig. 15) are 

depicted in three generalized hydrogeologic sections shown 

in figures 16 and 17. Stratigraphic units, general lithology, 

and corresponding hydrogeologic units underlying Highlands 

County are shown in figure 12.

Figure 14. Location of sinkholes and depressions in Highlands County.

River

Kissimmee

Lake

Istokpoga

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

HARDEE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

EXPLANATION

SINKHOLE OR DEPRESSION

FEATURE–Features were

delineated from 1:24,000

U.S. Geological Survey

topographic maps

LAKE

STREAM
Hydrogeology 21

Surficial Aquifer

The sediments that compose the surficial aquifer range 

from Pliocene to Holocene in age and are contiguous with 

land surface. Groundwater in the surficial aquifer is under 

unconfined or water-table conditions. The surficial aquifer is 

composed primarily of fine-to-medium grained quartz sand 

that grades with depth to silty and clayey sands. In this study, 

the base of the surficial aquifer is defined as the first persistent bed of Pliocene-age sediments containing a substantial 

increase in clay or silt. The hydrogeologic term, “surficial 

aquifer system” is generally used in referring to this aquifer in 

Florida (Southeastern Geological Society Ad Hoc Committee 

on Hydrostratigraphic Unit Definition, 1986). However, 

because in Highlands County there is just one permeable unit 

and no confining unit present, the term “surficial aquifer” is 

used here. This aquifer has also been referred to as “water 

table aquifer” or “nonartesian aquifer” in earlier reports.

A generalized contour map of the thickness of the 

surficial aquifer in Highlands County is shown in figure 18, 

which includes both saturated and unsaturated undifferentiated 

sediments. The thickness of the surficial aquifer is highly variable, ranging from less than 50 to more than 300 ft. In much 

of eastern, west-central, and extreme southwestern Highlands 

County, the thickness of the surficial aquifer generally ranges 

from about 50 to 100 ft. At a few locations within the county, 

however, the thicknesses of these sediments are less than 50 ft. 

Figure 15. Location of hydrogeologic sections.

98

98

27

17

70

27

River

Kissimmee

Lake

Istokpoga

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

WELL LOCATION AND NAME

LINE OF HYDROGEOLOGIC SECTION

EXPLANATION

ROMP 43

A A’ ROMP 13 W-5132

ROMP 28

W-2859

HIF-42

W-11421

W-9298

W-9285

Smoak

Groves

ROMP 14

ROMP 28x

ROMP 29A

W-2397 ROMP 43

ROMP 43xx

SFWMD S-2

A

A’

C

B’

B

C’
22 Hydrogeology and Groundwater Quality of Highlands County, Florida DeSoto Co. Highlands Co.

SURFICIAL

AQUIFER

FLORIDAN

UPPER

1,800

200

1,600

1,400

1,200

1,000

800

600

400

200

2,000

B B′

WEST

FEET

ROMP 13

W-9285

W-9298

ROMP 14

Section C-C’

Smoak

Groves

W-11421

HIF-42

?

?

?

?

AQUIFER

1,800

200

1,600

1,400

1,200

1,000

800

600

400

200

2,000

EAST

FEET

NGVD 29 NGVD 29

?

Estimated thickness of

upper permeable zone

Estimated thickness

of Avon Park

permeable zone

MIDDLE CONFINING UNIT II OR VI

MIDDLE CONFINING UNIT I

LOWER FLORIDAN AQUIFER ?

? ?

?

? ?

?

?

?

? ?

?

?

Hardee Co.

Highlands Co.

0 5 MILES

0 5 KILOMETERS

1,600

200

1,400

1,200

1,000

800

600

400

200

NGVD 29

A A′

WEST

FEET

ROMP 43

ROMP 43xx

Section C-C’

W-2397

SFWMD S-2

Vertical scale greatly exaggerated

1,600

200

1,400

1,200

1,000

800

600

400

200

NGVD 29

EAST

FEET

MIDDLE CONFINING UNIT II

AQUIFER

Estimated thickness of

upper permeable zone

UPPER

FLORIDAN Estimated thickness

of Avon Park

permeable zone

MIDDLE

CONFINING UNIT I

LOWER

FLORIDAN AQUIFER

SURFICIAL AQUIFER

INTERMEDIATE

AQUIFER SYSTEM / INTERMEDIATE CONFINING UNIT

INTERMEDIATE AQUIFER SYSTEM / INTERMEDIATE CONFINING UNIT

Figure 16. Generalized hydrogeologic sections A–A’ and B–B’. Section lines shown in figure 15.
Hydrogeology 23

The surficial aquifer is thickest along the Lake Wales Ridge, 

especially near the southernmost part of the county. At well 

ROMP 14, located near Hicoria, the surficial aquifer is about 

350 ft thick (Clayton, 1998).

The hydraulic properties of the surficial aquifer vary 

considerably and are largely dependent upon aquifer thickness, 

physical characteristics (such as grain-size and sorting), and 

the types of material that compose the aquifer. Few data are 

available on the hydraulic characteristics of the surficial aquifer 

in Highlands County. Transmissivity estimates from four 

wells in the county range from 2,400 to 16,300 ft2/d (Clayton, 

1998; DeWitt, 1998; Baldini and Ruppuhn, 1999; Southwest 

Florida Water Management District, 2000; and Mallams and 

Lee, 2005) (fig. 19). However, all four wells are located on 

the Lake Wales Ridge where the aquifer is thick and transmissivities are generally high. Transmissivity values range from 8 

to 2,400 ft2/d in Polk County (Spechler and Kroening, 2007) 

and from 14 to 5,300 ft2/d in Hardee and DeSoto Counties 

(Seaburn and Robertson, 1979; Southwest Florida Water 

Management District, 2000; LaRoche, 2007). Horizontal 

hydraulic conductivity values from three ROMP (Regional 

Observation and Monitoring-Well Program) wells in Highlands 

County range from 35 to 58 ft/d (Clayton, 1998; DeWitt, 1998; 

Mallams and Lee, 2005). Horizontal hydraulic conductivities determined for 20 wells along the Kissimmee River in 

both Highlands and Okeechobee Counties range from 0.8 to 

27 ft/d (Jose Valdes, South Florida Water Management District, 

written commun., 2007). Horizontal hydraulic conductivity 

values from six wells in Polk County range from 0.3 to 55 ft/d 

(Southwest Florida Water Management District, 2000). 

Additional horizontal hydraulic conductivity values reported 

for wells in adjacent Hardee and DeSoto Counties range from 

about 1 to 102 ft/d (Southwest Florida Water Management 

District, 2000; LaRoche, 2007). 

The altitude of the water levels in wells open to the 

surficial aquifer represents the water-table level. The water 

table is not a flat surface, but instead, a sloping surface 

that may resemble hills and valleys similar to land surface. 

The depth below land surface to the water table in the surficial 

aquifer varies from one physiographic region to another. 

In upland areas, the water table generally is a subdued reflection 

of land-surface topography. Depths ranging from 10 to 40 ft 

Figure 17. Generalized hydrogeologic section C–C’. Section line shown in figure 15.

?

?

?

? ?

?

?

?

0 5 MILES

0 5 KILOMETERS

SURFICIAL

AQUIFER

1,800

200

1,600

1,400

1,200

1,000

800

600

400

200

2,000

C C′

NGVD 29

NORTH

FEET

ROMP 43xx

Section A-A’

W-2859

ROMP 29A

ROMP 28

ROMP 28x

W-5132

Vertical scale greatly exaggerated

AQUIFER

ROMP 14

Section B-B’

1,800

200

1,600

1,400

1,200

1,000

800

600

400

200

2,000

NGVD 29

SOUTH

FEET

MIDDLE CONFINING UNIT II OR VI?

LOWER

FLORIDAN AQUIFER

Estimated thickness

of Avon Park

permeable zone FLORIDAN

UPPER

INTERMEDIATE AQUIFER SYSTEM / INTERMEDIATE CONFINING UNIT

Estimated thickness

of upper

permeable zone

MIDDLE

CONFINING UNIT II

?

?
24 Hydrogeology and Groundwater Quality of Highlands County, Florida

are common, but can exceed 50 ft below land surface along 

some parts of the Lake Wales Ridge in Highlands County. 

In the low-lying, poorly drained areas, the water table generally 

is at or within a few feet of the land surface. 

The altitude of the water table fluctuates in response to 

the net rate at which water in the surficial aquifer is recharged 

or discharged. The principal factors controlling the rate 

and magnitude of fluctuations in water levels are related to 

changes in precipitation, evapotranspiration, and local and 

regional pumping from the surficial aquifer, and to a lesser 

degree, groundwater withdrawals from the intermediate and 

Floridan aquifer systems. Groundwater levels in the surficial 

aquifer fluctuate seasonally and generally reach an annual 

maximum in September or October (near the end of the wet 

season) and decline to a minimum in April or May (near the 

end of the dry season). Spring water levels usually are lower 

than fall water levels because only about 30 percent of the 

total yearly rainfall occurs from November through April. 

Seasonal recharge by infiltration of precipitation causes water 

levels to rise in the summer months when rainfall totals are 

normal or above normal. Drier climatic conditions cause 

water levels to decline within a relatively short period of time 

following seasonal-high water levels in the summer. Although 

the magnitude of the water-level fluctuation in wells varies 

across the county, hydrographs show seasonal fluctuations of 

water levels ranging from about 1 to 5 ft (fig. 20).

Figure 18. Generalized thickness of the surficial aquifer.

River

Kissimmee

Lake

Istokpoga

100

100

50

100

200

100

50

50

100

200

200

250

250

300

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Hicoria

Archbold

Biological

Station

ROMP 14

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

LINE OF EQUAL THICKNESS–Shows

thickness of surficial aquifer. Dashed

where approximate. Contour intervals

are variable, in feet.

WELL CONTROL POINT

50

EXPLANATION
Hydrogeology    25

Figure 19. Transmissivity of the surficial aquifer and intermediate aquifer system. From Clayton (1998), 

DeWitt (1998), Baldini and Ruppuhn (1999), Southwest Florida Water Management District (2000), and 

Mallams and Lee (2005).

River

Kissimmee

Lake

Istokpoga

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

2,400

– –

162

50

6,900

160

1,750

– –

260

135

770

135

8,300

170

16,300

270

31

61

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

TOP NUMBER IS TRANSMISSIVITY – In feet squared per day.

BOTTOM NUMBER IS OPEN HOLE OR SCREEN INTERVAL OF

WELL – In feet.

DATA NOT AVAILABLE.

WELL LOCATION.

SURFICIAL

AQUIFER

UPPER ARCADIA

AQUIFER OF THE

INTERMEDIATE

AQUIFER SYSTEM

LOWER ARCADIA

AQUIFER OF THE

INTERMEDIATE

AQUIFER SYSTEM

– –

770

135

31

61

6,900

160

EXPLANATION

27°15’

81°15’

0 5 10 MILES

27°00’ 0 5 10 KILOMETERS

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983
26 Hydrogeology and Groundwater Quality of Highlands County, Florida

The water level fluctuations shown in figure 20 include 

rising and declining trends over short periods of time; 

however, as indicated by the LOWESS smoothing curves, no 

substantial long-term declining trends are evident. This lack of 

trends indicates that, at least over the periods of record shown 

in figure 20, precipitation received during the summer rains 

has been able to replenish the water being discharged from 

the surficial aquifer in drier months, resulting in negligible 

changes in aquifer storage.

The surficial aquifer is an important component of the 

groundwater system because it provides temporary storage 

for infiltrating water that eventually percolates down to the 

underlying aquifers or moves laterally to discharge areas. 

In Highlands County, the area of highest recharge is along the 

Lake Wales Ridge, which is characterized by poorly developed 

stream drainage and many closed depressions. The thick 

permeable deposits of sand along the Lake Wales Ridge 

provide rapid infiltration and absorb much of the rainfall not 

110

115

120

125

130

Site: Bairs Den

Well Number: 43

Depth: 35 feet

WATER LEVEL, IN FEET ABOVE NGVD 29

Site: Lake Groves Road

Well Number: 67

Depth: 23 feet

Site: H-15A

Well Number: 1

Depth: 23 feet

Site: H-11A

Well Number: 103

Depth: 16 feet

106

108

110

112

114

116

54

56

58

60

62

42

44

46

48

50

1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

LOWESS CURVE (Helsel and Hirsch, 1992)

EXPLANATION

Figure 20. Water levels in selected wells completed in the surficial aquifer. Well locations shown in figure 11.
Hydrogeology 27

lost to evapotranspiration. Recharge to the underlying Upper 

Floridan aquifer takes place where the confining beds are thin 

or permeable or where they have been breached by sinkholes. 

The rate of leakage is dependent on the hydraulic gradient 

between the surficial and Upper Floridan aquifers, as well as on 

the vertical hydraulic conductivity and thickness of the IAS/ICU. 

Recharge to the surficial aquifer occurs primarily through 

the infiltration of rainfall. Other sources of recharge include 

septic-tank effluent, irrigation of agricultural land or residential 

areas, seepage from lakes and streams, and the lateral groundwater inflow from adjacent areas. Recharge can also occur by 

upward leakage of water from the underlying Upper Floridan 

aquifer where water levels are higher than in the surficial 

aquifer. However, in the eastern part of the county where 

these conditions are present, the actual rate of recharge to the 

surficial aquifer may be low because the IAS/ICU that separates the surficial aquifer and Upper Floridan aquifer is thick 

and generally has low permeability, thereby limiting upward 

leakage. In such areas, rainfall can still recharge the surficial 

aquifer as long as the surficial sediments are unsaturated.

Water is discharged from the surficial aquifer primarily 

by evapotranspiration in areas where the water table is 

relatively shallow. Some discharge also occurs by: (1) withdrawals from wells; (2) lateral flow to lakes, streams, canals, 

and marshes; and (3) downward leakage through sinkholes 

and the confining layer to the Upper Floridan aquifer in areas 

where the potentiometric surface of this aquifer is below the 

water table.

The surficial aquifer is not a substantial source of water 

supply in the study area. In 2005, about 9.6 Mgal/d, or 

about 9 percent of the total groundwater used in Highlands 

County, was withdrawn from the surficial aquifer (M. Beach, 

Southwest Florida Water Management District, written 

commun., 2009). In areas where there are citrus groves, or in 

areas where septic tanks are common, water in the surficial 

aquifer can have elevated concentrations above background 

levels of nutrients, pesticides, or bacteria. In addition, the 

water can contain high concentrations of dissolved iron, which 

is an undesirable impurity in domestic and industrial supplies. 

Lawn irrigation and, in some areas, domestic supply are the 

main uses of water from the surficial aquifer. Water from the 

surficial aquifer is also used to irrigate citrus groves (Adams 

and Stoker, 1985; Barcelo and others, 1990; Yobbi, 1996). 

However, to obtain larger yields, irrigation wells are often 

drilled into the deeper parts of the Upper Floridan aquifer.

Well yields depend on the thickness and permeability 

of the surficial aquifer and generally range from about 10 to 

several hundred gallons per minute. The lower yields are from 

small diameter wells or from wells that are open to fine sand 

or clayey layers. The higher yields are from larger diameter 

wells that are open to thick layers of permeable coarse sand, 

such as present along the Lake Wales Ridge. A yield of about 

900 gal/min was obtained from a 300-ft deep surficial aquifer 

well during an aquifer performance test at the ROMP 14 well 

near Hicoria (Clayton, 1998). The 12-inch monitoring well 

was screened from 30 to 300 ft below land surface.

Intermediate Aquifer System/Intermediate 

Confining Unit 

The intermediate aquifer system/intermediate confining 

unit (IAS/ICU) includes all of the rock units that lie between 

the overlying surficial aquifer and the underlying Floridan 

aquifer system (Southeastern Geological Society Ad Hoc 

Committee on Hydrostratigraphic Unit Definition, 1986). 

The IAS/ICU generally coincides with the stratigraphic units 

designated as the Hawthorn Group, although the top of the 

unit can also include the clayey sediments of early Pliocene 

age (fig. 12). Throughout Highlands County, IAS/ICU acts 

as a confining layer (except where breached by sinkholes) 

that restricts the vertical movement of water between the 

surficial aquifer and Upper Floridan aquifer. The sediments 

have varying degrees of permeability, consisting of permeable 

limestone, dolostone, or sand or relatively impermeable layers 

of clay, clayey sand, or clayey carbonates. 

Presently (2010), it is not clear where in Highlands 

County the transitional boundary of the sediments change 

from an aquifer system to a confining unit. Previous studies 

have identified the approximate extent of the intermediate 

aquifer system in adjacent Polk, Hardee, and DeSoto Counties. 

Duerr and others (1988), Basso and Hood (2005), and 

Knochenmus (2006) indicated that the intermediate aquifer 

system is present in parts of western Highlands County; 

however, these studies ended at the SWFWMD boundary 

(fig. 1). Information available at some ROMP wells also 

indicates the intermediate aquifer system is present along 

parts of the Lake Wales Ridge (Clayton, 1998; DeWitt, 

1998). Arthur and others (2008) suggest that the transitional 

boundary may extend into central Highlands County. Although 

little hydrogeologic information about the aquifer system is 

available east of the Lake Wales Ridge, water-use permits, 

well completion reports, and wells inventoried for this study 

indicate that permeable units may extend into parts of eastern 

Highlands County. 

Hydrogeologic sections showing the relative position and 

thickness of the IAS/ICU over the county are shown in figures 

16 and 17. A generalized structure contour map of the altitude 

of the top of the IAS/ICU is shown in figure 21. The top of 

the unit is defined as the first persistent clays of Pliocene or 

Miocene age. The altitude of the top of the IAS/ICU is highest 

in the western part of the county where it is more than 50 ft 

above NGVD 29 (fig. 21). Altitudes of more than 150 ft below 

NGVD 29 occur along the southern part of the Lake Wales 

Ridge. In much of the eastern part of the county, altitudes 

range from about 0 to 50 ft below NGVD 29. The thickness 

of the IAS/ICU ranges from about 200 ft in northwestern 

Highlands County to more than 600 ft in the southwestern part 

of the county (fig. 22).

As previously mentioned, it is not clear where the 

predominantly Miocene sediments of the intermediate 

aquifer system grade into the intermediate confining unit. 

The intermediate confining unit, where present in eastern 

Highlands County, acts as a confining layer that restricts the 
28 Hydrogeology and Groundwater Quality of Highlands County, Florida

vertical movement of water between the surficial aquifer and 

the Upper Floridan aquifer. The intermediate confining unit 

consists primarily of Hawthorn Group sediments of Miocene 

age, and in some areas, low permeability beds of early 

Pliocene age. The unit consists of interbedded clay, silt, sand, 

phosphate, limestone, and dolostone.

The intermediate aquifer system, believed to be present 

in parts of Highlands County, consists of the more permeable sediments of the Peace River and Arcadia Formations. 

The intermediate aquifer system in Highlands County consists 

of three hydrogeologic units: a sandy clay or clay confining 

unit that separates the water-bearing units from the surficial 

aquifer; one or two water-producing units composed primarily 

of sand and carbonate rocks; and a sandy clay to clayey sand 

lower confining unit that overlies the Upper Floridan aquifer. 

The confining units are highly variable both areally and 

vertically. In addition, the water-producing units are separated 

by less-permeable units that restrict the vertical movement 

of groundwater between these zones. As a whole, however, 

the entire system, including the water-producing units, has 

substantially lower permeability than the Upper Floridan 

aquifer and is classified as a confining unit. The hydrogeologic 

term “intermediate aquifer system” is equivalent with the term 

"secondary artesian aquifer" as used by Stewart (1966) and the 

term "upper unit of the Floridan aquifer system" as used by 

Wilson (1977) and Hutchinson (1978).

Figure 21. Generalized altitude of the top of the intermediate aquifer system/intermediate confining unit. 

River

Kissimmee

Lake

Istokpoga

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Archbold

Biological

Station

-50

0

0

-50

-100

50

50

0

0

-50

-100

-100

-50

-50

0

-150

-150

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

STRUCTURE CONTOUR–Shows altitude

of the top of the intermediate aquifer

system/intermediate confining unit.

Dashed where approximate. Datum

is NGVD 29. Contour interval is 50 feet.

WELL CONTROL POINT

50

EXPLANATION
Hydrogeology 29

Various names have been used to describe the permeable 

units within the intermediate aquifer system in southwestern 

Florida. Recent reports have used zone numbers (PZ1, PZ2, 

and PZ3) to designate the permeable units identified in the intermediate aquifer system (Barr, 1992; Torres and others, 2001; 

Basso, 2003; Basso and Hood, 2005). The zones are distinguished as separate units by intervening confining units and 

by differences in water quality and water levels. Knochenmus 

(2006) renamed these permeable units (in order of increasing 

depth) as Zone 1, Zone 2, and Zone 3. More recently, DeWitt 

and Mallams (2007) and Mallams and DeWitt (2007) proposed 

that Zone 2 and Zone 3 of the intermediate aquifer system be 

renamed the upper Arcadia aquifer and lower Arcadia aquifer, 

respectively. This report uses the nomenclature of DeWitt 

and Mallams (2007) and Mallams and DeWitt (2007). 

The lateral continuity and water-bearing potential of the 

various units within the intermediate aquifer system are highly 

variable due to the heterogeneity that is typical of Hawthorn 

Group sediments. Where multiple water-producing units are 

present, they generally are laterally discontinuous and difficult 

to map (Basso and Hood, 2005). Up to two water-producing 

units within the intermediate aquifer system are believed to 

extend into Highlands County. Earlier studies indicate that 

these units are limited in vertical extent and present at various 

depths (Knochenmus, 2006). The uppermost water-producing 

units in Highlands County, the upper Arcadia aquifer (Zone 2), 

consists of discontinuous thin beds of limestone, dolostone, 

Figure 22. Generalized thickness of the intermediate aquifer system/intermediate confining unit.

River

Kissimmee

Lake

Istokpoga

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

Archbold

Biological

Station

200

400

500

300

400

600

400

300

400

500

600

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

LINE OF EQUAL THICKNESS–Shows

thickness of the intermediate aquifer

system/intermediate confining unit.

Contour interval 100 feet.

WELL CONTROL POINT

300

EXPLANATION
30 Hydrogeology and Groundwater Quality of Highlands County, Florida

sand, and shell within the lower Peace River and/or the upper 

Arcadia Formations (Basso and Hood, 2005; LaRoche, 2007). 

According to Knochenmus (2006), the aquifer extends into 

west-central Highlands County. The upper Arcadia aquifer 

appears to be the most geographically extensive waterproducing unit within the intermediate aquifer system, and can 

be mapped in much of southwestern Florida (Basso and Hood, 

2005). The lowermost water-producing unit, the lower Arcadia 

aquifer (Zone 3), consists primarily of limestone, with varying 

amounts of interbedded siliciclastics in the lower part of the 

Arcadia Formation (Clayton, 1998; DeWitt, 1998; Basso, 2003; 

Basso and Hood, 2005; LaRoche, 2007). The lower Arcadia 

aquifer is generally the most productive aquifer within the 

intermediate aquifer system in southwestern Florida (Basso, 

2003). Based on limited data, the lower Arcadia aquifer may 

not be present in Highlands County. However, this aquifer is 

present at well ROMP 13 in DeSoto County (fig. 1), which is 

located about 5 miles from the Highlands County line.

Data on the hydraulic properties of the intermediate 

aquifer system in Highlands County are limited, and estimates are primarily available from regional flow-model 

simulations. Transmissivity estimates for the upper Arcadia 

aquifer (Zone 2) at two sites in Highlands County (fig. 19) 

ranged from 31 to 162 ft2/d (Clayton, 1998; DeWitt, 1998). 

Model-derived transmissivity values ranged from about 100 

to 3,000 ft2/d in the intermediate aquifer system in Highlands 

County (Sepúlveda, 2002). In comparison, reported transmissivity values ranged from 1 to 8,800 ft2/d at 43 sites in 

the upper Arcadia aquifer (Zone 2) in southwestern Florida 

(Knochenmus, 2006). Reported transmissivity values ranged 

from 20 to 43,000 ft2/d at 36 sites in the lower Arcadia aquifer 

(Zone 3) in southwestern Florida (Knochenmus, 2006). 

The confining units present within the intermediate 

aquifer system have low hydraulic conductivity and restrict 

the vertical movement of water. The confining units consist 

primarily of clays and sands that hydraulically separate 

the intermediate aquifer system from the adjacent aquifers. 

However, depending on the hydraulic gradients and the permeability of the units, these confining units may transmit water 

or allow water to leak from one water-bearing unit to another. 

Leakance values calibrated in a regional flow model ranged 

from 1 × 10-6 to 6 × 10-4 (ft/d)/ft in the upper confining unit 

of the intermediate aquifer system and from 1 × 10-6 to 1 × 

10-3 (ft/d)/ft in the lower confining unit (Sepúlveda, 2002). 

In another model, calibrated leakance ranged from 5 × 10-6

to 1 × 10-3 (ft/d)/ft in the upper confining unit along the 

Lake Wales Ridge in Highlands County and from 1 × 10-6 to 

5 × 10-4 (ft/d)/ft in the lower confining unit (Yobbi, 1996). 

Leakance values are highest along the Lake Wales Ridge 

where aquifer recharge is highest and the confining beds 

are relatively thin, permeable, or breached by karst features. 

The lowest leakance values occur along the flanks of the 

Lake Wales Ridge where karst features are less numerous, the 

confining units are relatively thick or have lower permeability, 

and aquifer recharge rates are low (Yobbi, 1996).

Water levels in the intermediate aquifer system respond 

seasonally to rainfall and pumping. Seasonal water-level 

fluctuations in two wells completed in the intermediate aquifer 

system are shown in figure 23. Water levels generally are at, 

or near, their minimum levels during May, then begin to rise 

through September or October in response to the summer rains 

and the reduction of irrigation pumping. Seasonal fluctuations 

in water levels in the intermediate aquifer system range from 

about 1 to 20 ft. 

The IAS/ICU is recharged primarily by downward 

leakage from the overlying surficial aquifer, and more directly, 

through sinkholes. Recharge can also occur by upward leakage 

from the underlying Upper Floridan aquifer. Discharge from 

the IAS/ICU occurs as pumpage, by downward leakage into 

the Upper Floridan aquifer, upward leakage to the surficial 

aquifer, and lateral outflow from the county. 

The intermediate aquifer system is a minor source of 

water supply in Highlands County. About 2.1 Mgal/d, totaling 

2 percent of the total groundwater used in Highlands County, 

was withdrawn from the intermediate aquifer system in 

2005 for domestic, irrigation, or public supply (M. Beach, 

Southwest Florida Water Management District, written 

commun., 2009). 

45

50

55

60

65

WATER LEVEL, IN FEET ABOVE NGVD 29

1985 1990 1995 2000 2005 2010

YEAR

70

75

70

72

74

76

78

80

Site: Richards

Well Number: 166

Depth: 260 feet

Site: ROMP 28 IAS

Well Number: 88

Depth: 420 feet

LOWESS CURVE (Helsel and Hirsch, 1992)

EXPLANATION

Figure 23. Water levels in selected wells completed in 

the intermediate aquifer system. Well locations shown in 

figure 11.
Hydrogeology 31

Floridan Aquifer System

The Floridan aquifer system underlies the entire Florida 

Peninsula, as well as parts of Alabama, Georgia, and South 

Carolina. As previously mentioned, this aquifer system is 

the principal source of municipal, agricultural, and industrial 

water supply in Highlands County. It is composed of a thick 

sequence of limestone and dolostone of late Paleocene to 

Oligocene age that is generally high in permeability and 

hydraulically connected in varying degrees. The Floridan 

aquifer system ranges from about 2,800 to 3,400 ft in thickness in Highlands County (Miller, 1986) and includes the 

following stratigraphic units in ascending order—the upper 

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

Avon Park Formation, the Ocala Limestone, and the Suwannee 

Limestone (fig. 12). The base of the Floridan aquifer system 

is defined by the first occurrence of vertically persistent beds 

of gypsum or anhydrite found in the upper part of the Cedar 

Keys Formation. The top of the Floridan aquifer system in 

Highlands County generally coincides with the top of the 

Suwannee Limestone where it is present. If the Suwannee 

Limestone is absent, the top of the Floridan aquifer system 

coincides with the top of the Ocala Limestone.

The Floridan aquifer system is divided into aquifers of 

relatively high permeability—the Upper Floridan aquifer and 

Lower Floridan aquifer. Both aquifers are separated by lesspermeable units (where present) called the middle confining 

unit I, II, or VI. The aquifer layers are delineated on the basis 

of rock permeability characteristics, rather than formation 

or time-stratigraphic boundaries (Miller, 1986). Over most 

of Highlands County, the Upper Floridan aquifer generally 

contains freshwater, and the Lower Floridan aquifer contains 

more mineralized water.

Upper Floridan Aquifer

The Upper Floridan aquifer underlies all of Highlands 

County and is composed of a thick sequence of carbonate 

rocks that include the upper half of the Avon Park Formation, 

the Ocala Limestone, and the Suwannee Limestone where 

present. 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 24. The altitude of the 

top of the Upper Floridan aquifer is highest in the extreme 

northwestern part of the county just north of Avon Park, where 

it is less than 200 ft below NGVD 29. The top of the aquifer 

dips toward the south, to more than 600 ft below NGVD 29 

in the southwestern part of the county. The thickness of the 

Upper Floridan aquifer ranges from about 1,150 to 1,500 ft in 

Highlands County (Clayton, 1998; DeWitt, 1998; Mallams and 

Lee, 2005; Arthur and others, 2008). The base of the Upper 

Floridan aquifer is defined by the first occurrence of vertically 

persistent beds of gypsum or anhydrite found in the Avon Park 

Formation (middle confining unit II). If the middle confining 

unit I is present, then the base of the aquifer is considered to 

be the top of the middle confining unit I.

In Highlands County, the Upper Floridan aquifer consists 

of three hydrogeologic units: (1) the moderately permeable 

Suwannee Limestone, referred to as the upper permeable zone; 

(2) the semiconfining Ocala Limestone; and (3) the highly 

permeable fractured crystalline dolostone in the Avon Park 

Formation, referred to as the lower permeable zone or Avon 

Park permeable zone. 

The Suwannee Limestone is the uppermost permeable 

zone of the Upper Floridan aquifer. The permeability of the 

Suwannee Limestone appears to be primarily intergranular, 

with some minor parts attributed to moldic porosity (Basso, 

2003). In the eastern part of Highlands County, the Suwannee 

Limestone has been removed by erosion and the Ocala 

Limestone generally is the uppermost permeable zone of 

the Upper Floridan aquifer. Although the Ocala Limestone 

generally does not contain intervals that are highly productive, 

at ROMP 14 and ROMP 28 (Clayton, 1998; DeWitt, 1998) 

the uppermost parts of the formation were included in the 

uppermost permeable zone. Bishop (1956) noted that yields 

from the Ocala Limestone were not as large as yields from 

deeper Eocene formations; however, in some parts of southeastern Highlands County, the Ocala Limestone was capable 

of producing relatively large volumes of water. Stewart (1966) 

stated that in some areas in Polk County, where the Suwannee 

Limestone is missing, the lower part of the Ocala Limestone 

can also produce moderate amounts of water to wells. Wells 

completed in the Suwannee Limestone generally yield more 

water than wells completed in the Ocala Limestone.

Underlying the Suwannee Limestone is a semiconfining 

unit that generally corresponds stratigraphically to the Ocala 

Limestone. The unit is composed primarily of a soft, poorly 

consolidated, fossiliferous, carbonate mud-rich limestone. 

In much of the study area, this semiconfining unit generally 

includes all or part of the Ocala Limestone, but in some areas, 

also may include the upper part of the Avon Park Formation 

(Basso, 2003). Data collected from ROMP 29A (fig. 15) in 

Highlands County show that the semiconfining unit included 

all of the Ocala Limestone, and all but about the uppermost 

25 ft of the Ocala Limestone at ROMP 14 and ROMP 28 

(fig. 15). At ROMP 14, however, the semiconfining bed also 

included 199 ft of the upper Avon Park Formation.

The carbonate section of the upper Avon Park Formation, 

which consist of grainstones and grain-dominated packstones, 

can be moderately productive. Visual examination of core 

samples and thin sections suggests these grainy lithofacies 

have relatively high intergranular porosity and relatively 

high matrix permeability (Ward and others, 2003). Thus, 

these carbonate rocks are a heterogeneous interlayering of 

thin conduit flow and carbonate rock diffuse flow zones. 

However, the lowermost permeable zone and the most 

productive interval of the Upper Floridan aquifer occur in the 

hard fractured dolostone within the Avon Park Formation. 

This highly permeable zone, also referred to as the Avon Park 

permeable zone (Reese and Richardson, 2008), is the most 

important water-producing zone of the Upper Floridan aquifer 

and is utilized whenever large quantities of groundwater 
32 Hydrogeology and Groundwater Quality of Highlands County, Florida

are needed for municipal or irrigation supplies. Yields from 

large diameter wells completed in this zone can range from 

2,000 to 3,000 gal/min (Basso, 2003). The thickness of this 

zone ranges from about 200 to 350 ft in Highlands County 

(Clayton, 1998; DeWitt, 1998; Mallams and Lee, 2005; Reese 

and Richardson, 2008). 

The top of the Avon Park permeable zone generally is 

marked by an increase in formation resistivity (as seen in 

geophysical logs) because of the increasing presence of dolostone. The high transmissivity and fractured rock in this zone 

commonly results in a change in the borehole from a size that 

is similar to the drill bit to a borehole with numerous, abrupt, 

large hole enlargements (O’Reilly and others, 2002; Reese and 

Richardson, 2008). Borehole flowmeter logs can also indicate 

large flow zones, marked by large temperature or fluid resistivity curve deflections (Reese and Richardson, 2008).

The transmissivity of the Upper Floridan aquifer varies 

throughout the area. Transmissivity, or the capacity of an 

aquifer to transmit water, is one way of measuring the ease 

with which groundwater flows through an aquifer. Variations 

in transmissivity of the rock strata within the Upper Floridan 

aquifer are complex and are related to the areal differences in 

Figure 24. Altitude of the top of the Floridan aquifer system.

Archbold

Biological

Station

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

River

Kissimmee

Lake

Istokpoga

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

-600

-500

-400

-300

-250

-200

-500

-500

-400

-600

STRUCTURE CONTOUR–Shows altitude

of the top of the Floridan aquifer system.

Datum is NGVD of 29. Contour intervals

are variable, in feet.

WELL CONTROL POINT

-500

EXPLANATION

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983
Hydrogeology 33

primary and secondary porosity of the aquifer, with the latter 

being more important to the flow of groundwater. Primary 

porosity refers to the porosity remaining after sediments have 

been compacted, but without considering changes resulting 

from subsequent chemical action or flow of water through the 

sediments. Secondary porosity develops from fracturing and 

dissolution of carbonate rocks. As a result, transmissivity can 

be high with a wide range in values.

Transmissivity values of the Upper Floridan aquifer 

determined from aquifer and specific capacity tests in 

Highlands County range from less than 1,000 to about 

410,000 ft2/d (fig. 25), and model-derived transmissivity 

values for the Upper Floridan aquifer range from about 10,000 

to 500,000 ft2/d (Sepúlveda, 2002). Transmissivity data from 

the upper permeable zone of the Upper Floridan aquifer are 

limited in Highlands County, with values generally less than 

7,000 ft2/d (fig. 25). Most of the transmissivity values available in Highlands County are the result of wells that penetrate 

multiple geologic units including the Suwannee Limestone, 

Ocala Limestone, and various parts of the Avon Park Formation (including the Avon Park permeable zone), which 

generally results in considerably higher transmissivity values.

Figure 25. Transmissivity of the Upper Floridan aquifer. From Shaw and Trost (1984), Bradner (1994), Clayton 

(1998), DeWitt (1998), Baldini and Rappuhn (1999), Southwest Florida Water Management District (2000), and 

Mallams and Lee (2005).

98

98

27

17

70

27

River

Kissimmee

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

GLADES

COUNTY

6,300

380 132,000

508

2,400

115

301,000

911

112,000

894

6,600

80

3,600

304

267,100

1,165

922,000

920

56,000

1,000

330

115

5,500

785

3,600

760

40,000

1,162

8,300

936

70,000

1,067

6,800

867

2,800

782

6,900

679

410,000

935

4,300

1,225

320,000

14,700 902

962

370

210

3,100

190

27,000

840

79,000

272 *

11,400

220

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

EXPLANATION

WELL LOCATION – Open interval includes

the lower Hawthorn Group and the

Ocala Limestone.

WELL LOCATION – Open interval includes

primarily the Suwannee Limestone and/or

the Ocala Limestone.

WELL LOCATION – Open interval includes

primarily the Suwannee Limestone and/or

the Ocala Limestone and parts of the

Avon Park Formation.

370

210

Top number is transmissivity from aquifer or

specific capacity test, in feet squared per day.

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

Open-hole interval is in the Avon Park permeable zone. *

27,000

840

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983
34 Hydrogeology and Groundwater Quality of Highlands County, Florida

Middle Confining Units 

Miller (1986) mapped three low-permeability units of 

subregional extent and thickness that separate the Upper 

Floridan aquifer from the Lower Floridan aquifer in Highlands 

County. These units (middle confining units I, II, and VI) 

are present at different altitudes within Highlands County 

and contain rock types that are different from one another. 

According to Miller (1986), any of these low permeability units 

may locally contain thin zones of moderate to high permeability; however, overall the units act as a single confining unit.

Middle confining unit I (Miller, 1986), equivalent to the 

term “middle semiconfining unit” as used in other reports, 

is a sequence of softer, relatively less-permeable limestone 

and dolomitic limestone of variable thickness. Miller (1986) 

noted that contrast in permeability between the rocks of this 

unit and the permeable rocks above or below it was less than 

that for any other middle confining unit that was mapped. 

Data points for estimating the extent and thickness of middle 

confining unit I are nearly nonexistent in Highlands County, 

so it is unclear where the unit pinches out. According to Miller 

(1986), middle confining unit I is absent in the western part of 

the county. The estimated thickness of the unit in Highlands 

County ranges from 0 to 600 ft (Miller, 1986).

Underlying middle confining unit I is a separate and 

distinct second confining unit. The unit, which consists 

primarily of low-permeability gypsiferous dolostone and dolomitic limestone in the middle to lower part of the Avon Park 

Formation, is referred to herein as middle confining unit II 

(Miller, 1986). The unit is equivalent to the term “middle 

confining unit” as used in other reports in central Florida. 

Middle confining unit II, which is considerably less permeable than middle confining unit I, forms a virtually nonleaky 

confining bed that separates freshwater in the Upper Floridan 

aquifer from the more mineralized water in the underlying 

rocks. The top of middle confining unit II, generally defined as 

the first occurrence of evaporites, ranges (where present) from 

about 1,250 ft below NGVD 29 in northeastern Highlands 

County to more than 1,600 ft below NGVD 29 in the southwestern part of the county (Miller, 1986). Based on limited 

data, the unit may not be present in parts of eastern Highlands 

County. The thickness of middle confining unit II ranges from 

0 to 300 ft over most of the county (Miller, 1986). 

In southwestern Highlands County is another confining 

unit called middle confining unit VI, which underlies middle 

confining unit II (Miller, 1986). The rocks of middle confining 

unit VI form a sequence of interbedded finely to coarsely 

crystalline dolomite and finely pelletal, micritic limestone that 

is commonly argillaceous (Miller, 1986). In much of the unit, 

the intergranular pore space of the carbonate rocks is filled 

with gypsum. The top of middle confining unit VI (where 

present) ranges from about 1,900 ft below NGVD 29 in central 

Highlands County to about 2,000 ft below NGVD 29 in the 

southwestern part of the county (Miller, 1986). The thickness of 

middle confining unit VI ranges from 0 to 200 ft (Miller, 1986). 

Little information is available on the hydraulic properties 

of the middle confining units in Highlands County. Horizontal 

hydraulic conductivity values of middle confining unit II 

based on packer tests at ROMP 14 and ROMP 28 ranged 

from 0.003 to 0.125 ft/d (Clayton, 1998; DeWitt, 1998). 

Horizontal hydraulic conductivity values based on slug tests 

at ROMP 29A ranged from 0.05 to 0.3 ft/d (Mallams and Lee, 

2005). Horizontal hydraulic conductivity values of middle 

confining unit II based on packer tests in Hillsborough, 

Manatee, and Sarasota Counties ranged from 0.002 to 

0.04 ft/d (Basso, 2003). Horizontal hydraulic conductivities 

determined from cores taken at different depths within middle 

confining unit II at the Polk City test well in Polk County 

generally ranged from about 0.000024 to 0.90 ft/d, although 

two samples yielded hydraulic conductivities values of 6.6 

and 19.0 ft/d (Navoy, 1986). 

Lower Floridan Aquifer and Sub-Floridan 

Confining Unit

The geologic characteristics and hydraulic properties of 

the Lower Floridan aquifer in Highlands County are not well 

known. Because of its greater depths, the likelihood that the 

Lower Floridan aquifer contains more mineralized water, and 

sufficient water generally can be obtained from the Upper 

Floridan aquifer, few wells have been drilled into this aquifer. 

The Lower Floridan aquifer is present throughout Highlands 

County and underlies middle confining units I, II, and VI. 

Altitudes of the top of the Lower Floridan aquifer are estimated to range from about 1,050 to 1,850 ft below NGVD 29 

(Miller, 1986). Much of the variation observed in the top of 

the aquifer is the result of discontinuities in the configuration 

of the middle confining units caused by variations in their 

altitudes and thicknesses over the county. 

The Lower Floridan aquifer consists of the upper part of 

the Cedar Keys Formation, the Oldsmar Formation, and the 

lower part of the Avon Park Formation (fig. 12). In much of 

Highlands County, the Lower Floridan aquifer is composed of 

a thick sequence of mostly low-permeability rocks separated 

by relatively thin permeable zones (Miller, 1986). In contrast, 

the Lower Floridan aquifer is considerably more permeable in 

east-central and northeastern Florida.

A highly permeable zone present within the lower part 

of the Lower Floridan aquifer is the “Boulder Zone.” Present 

in much of southern Florida, this zone is believed to extend 

into the southeastern part of Highlands County (Miller, 1986; 

Reese and Richardson, 2008). Rocks in this zone consist 

primarily of massively bedded dolostone having extensively 

developed secondary (cavernous) porosity. Borehole televiewer surveys show that this zone consists of a series of thin 

to moderately thick horizontal openings connected vertically 

by fractures, some of which have been opened and enlarged 

into vertical tubes by dissolution (Miller, 1986). The Boulder 

Zone contains saline water and is commonly used in parts of 
Hydrogeology 35

southern Florida for the disposal of treated wastewater through 

injection wells (Reese and Richardson, 2008). The zone is 

overlain in most places by confining units that prevent the 

upward movement of injected wastewater. The cavernous 

nature of the Boulder Zone was created by the vigorous 

circulation of groundwater through the carbonate rocks in 

geologic past, and was not created by the present groundwaterflow system (Miller, 1990). Estimated altitudes to the top of 

the Boulder Zone in Highlands County range from 3,000 to 

3,400 ft below NGVD 29 (Miller, 1986). 

No data are available to describe the hydraulic properties 

of the Lower Floridan aquifer in Highlands County. In southcentral Florida, the unit is of relatively low permeability 

because of the presence of intergranular gypsum. Where the 

Boulder Zone is present, however, transmissivities can be 

high because of its cavernous nature. Transmissivity for the 

Boulder Zone in southeastern Florida is estimated to exceed 

3,000,000 ft2/d (Meyer, 1974).

A base of low-permeability dolostone and massive 

evaporite beds of Paleocene age forms the sub-Floridan 

confining unit, or the base of the Floridan aquifer system. 

The base is defined as the first occurrence of vertically persistent beds of evaporites in the upper part of the Cedar Keys 

Formation (Miller, 1986). These beds have very low permeability and range in depth from about 3,150 ft below NGVD 29 

in the northern part of Highlands County to more than 3,900 ft 

below NGVD 29 in the southern part (Miller, 1986).

Groundwater System and Characteristics

An understanding of the groundwater system in Highlands 

County is needed to efficiently manage the water resources of 

this area. This section discusses (1) the potentiometric surface 

of the Upper Floridan aquifer; (2) groundwater withdrawals, 

recharge, and discharge in the aquifers; (3) long-term trends in 

groundwater levels; (4) water-level comparisons; and (5) waterbudget components. 

Potentiometric Surface of the Upper 

Floridan Aquifer

The potentiometric maps shown in figures 26 and 27 

represent the hydraulic head in the Upper Floridan aquifer 

and depict the level to which water will rise in tightly cased 

wells. The slope of the potentiometric surface determines the 

general direction of groundwater movement. Groundwater in 

the Upper Floridan aquifer flows downgradient from potentiometric highs to potentiometric lows. The arrows superimposed 

on the maps show the direction of groundwater movement, 

which is perpendicular to the potentiometric contours.

The potentiometric surface of the Upper Floridan aquifer 

in May 2007 (Kinnaman and Dixon, 2007) and September 

2007 (Kinnaman and Dixon, 2008) is highest in northwestern 

Highlands County, and a groundwater divide is present along 

the Lake Wales Ridge (figs. 26 and 27). West of the Lake 

Wales Ridge, the direction of groundwater flow is to the 

southwest. East of the ridge, the direction of flow is toward 

the Kissimmee River.

The May 2007 potentiometric surface map (fig. 26) 

represents hydrologic conditions near the end of the dry 

season, when groundwater withdrawals from the aquifer for 

agricultural irrigation and public supply are near their annual 

maximums and water levels generally are near their annual 

minimums (fig. 26). The potentiometric surface ranges from 

about 79 ft above NGVD 29 in northwestern Highlands 

County to about 40 ft above NGVD 29 in the southeastern 

part of the county. In much of the southern and eastern parts 

of the county, water levels generally are less than 45 ft above 

NGVD 29. 

The September 2007 potentiometric surface map 

(fig. 27) represents hydrologic conditions near the end of 

the wet season, when withdrawals from the aquifer for 

agricultural irrigation and public supply are near minimum 

levels, and water levels generally are near their annual 

highs. The potentiometric surface ranges from about 85 ft 

above NGVD 29 in northwestern Highlands County to about 

43 ft above NGVD 29 in the southeastern part of the county. 

Differences in water levels of the Upper Floridan aquifer 

ranged from about 3 to 10 ft higher in September 2007 

compared to May 2007. However, the potentiometric surface 

configuration and general direction of groundwater flow did 

not change substantially between September and May 2007.

Groundwater Withdrawals, Recharge, and 

Discharge

Groundwater levels in the Upper Floridan aquifer 

respond seasonally, and over the long term, to climatic 

effects (rainfall and drought) and groundwater withdrawals. 

The extent to which these hydrologic factors affect groundwater levels can vary throughout the county. The spatial and 

temporal distribution of pumpage, as well as the proximity and 

degree of the hydraulic connection of the aquifer to overlying 

and underlying hydrologic units, all affect groundwater levels. 

Seasonal water-level fluctuations in four wells open to the 

Upper Floridan aquifer in Highlands County are shown in 

figure 28. Groundwater levels in the Upper Floridan aquifer 

usually reach their maximum levels in September or October 

in response to summer rains and a decline in agricultural 

irrigation. During the winter and spring, water levels gradually 

decline in response to reduced precipitation and increased 

agricultural water use. Seasonal water-level fluctuations in the 

Upper Floridan aquifer range from about 1 to 20 ft (fig. 28). 

Generally, fluctuations are largest in areas where the aquifer is 

confined and is heavily pumped for irrigation or public supply. 

Fluctuations are considerably smaller in areas where the overlying confining beds are thin or leaky and where groundwater 

withdrawals from the Upper Floridan aquifer are minimal. 
36 Hydrogeology and Groundwater Quality of Highlands County, Florida

In Highlands County, the Upper Floridan aquifer is 

recharged by the downward leakage of water through the 

surficial aquifer and IAS/ICU and by lateral inflow from 

adjacent counties. The rate of recharge varies with the 

vertical hydraulic conductivity, thickness of the surficial 

aquifer and underlying units, and magnitude of the downward 

head gradient. Flow simulations show that vertical leakage 

rates (recharge rates) from the surficial aquifer to the Upper 

Floridan aquifer range from about 0 to 25 in/yr in Highlands 

County (fig. 29), and at a few locations, exceeding 25 in/yr 

(Sepúlveda, 2002). The highest rates of recharge occur 

along the Lake Wales Ridge, the Intra Ridge Valley, and the 

Bombing Range Ridge in northeastern Highlands County 

(fig. 5). Lower rates of recharge from the surficial aquifer 

to the Upper Floridan aquifer occur adjacent to the ridges 

and in the southwestern part of the county. The areas of high 

recharge are characterized by numerous closed basins or lakes 

where sinkholes have breached the IAS/ICU, by overlying 

confining beds that are relatively thin or permeable, and by a 

downward hydraulic gradient. Very low to moderate recharge 

rates occur in areas where a downward gradient is present, 

but the permeability and thickness of the confining bed and 

the magnitude of the downward gradient are less favorable 

for recharge as compared to the most effective recharge areas 

(Phelps, 1985).

Discharge from the Upper Floridan aquifer in Highlands 

County occurs by diffuse upward leakage in discharge areas 

where the potentiometric surface is above the water table 

Figure 26. Potentiometric surface of the Upper Floridan aquifer, May 2007. Modified from Kinnaman 

and Dixon (2007).

River

Kissimmee

Lake

Istokpoga

50

70

50

60

60

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

68

79

47e

44

41

43 44

44

44

44

44

44

36

43

51

64

40

40

42

42

65

45

76

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

POTENTIOMETRIC CONTOUR–Shows altitude

at which water level would have stood in

tightly cased wells. Datum is NGVD 29.

Contour interval is 10 feet.

50

EXPLANATION

44 WELL–Number is altitude of water level in

feet above NGVD 29. “e” indicates estimated.

DIRECTION OF GROUNDWATER FLOW

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983
Hydrogeology 37

(fig. 29). Discharge also occurs by pumping, free-flowing 

wells, and lateral outflow to adjacent counties. Wells open to 

the aquifer will flow in areas where the potentiometric surface 

of the Upper Floridan aquifer lies above land surface. Areas of 

artesian flow from the Upper Floridan aquifer for September 

2007 in Highlands County are shown in figure 27. During 

September 2007, areas of artesian flow occurred primarily 

east of the Lake Wales Ridge. Though not shown on figure 

26, areas of artesian flow from the Upper Floridan aquifer for 

May 2007 did not change substantially from September 2007. 

Sepúlveda (2002) indicated that model-derived leakage rates 

from the Upper Floridan aquifer to the surficial aquifer ranged 

from 0 to less than 10 in/yr in the discharge area of eastern 

Highlands County (fig. 29).

Long-Term Trends in Groundwater Levels

Long-term water-level data from monitoring wells 

completed in the surficial and intermediate aquifer systems 

and the Upper Floridan aquifer were analyzed statistically 

for significant trends (table 1) using the nonparametric 

Kendall’s tau analysis (Helsel and Hirsch, 1992). A probability 

level of 5 percent was chosen as the criterion for statistical 

significance. LOWESS curves, a robust smoothing technique 

described by Helsel and Hirsch (1992), were used to provide 

visual indications of possible trends in groundwater levels.

Long-term water-level data in Highlands County are 

available for only a few wells. For the surficial aquifer, three 

monitoring wells have water-level data that began in the early 

Figure 27. Potentiometric surface of the Upper Floridan aquifer, September 2007. Modified from 

Kinnaman and Dixon (2008).

River

Kissimmee

Lake

Istokpoga

50

50

60

60

70

80

Venus

Kuhlman

Sebring

Brighton

Avon Park

Lake

Placid

Lorida

Cornwell

81

71

85

51e

47

45

45 46

47

50

49

48

49

47

50

61

68

48

43

46

49

78

48

49

75

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

EXPLANATION

50

49 WELL–Number is altitude of water level in

feet above NGVD 29. “e” indicates estimated.

POTENTIOMETRIC CONTOUR–Shows altitude

at which water level would have stood in

tightly cased wells. Datum is NGVD 29.

Contour interval is 10 feet.

APPROXIMATE AREA OF ARTESIAN FLOW

DIRECTION OF GROUNDWATER FLOW
38 Hydrogeology and Groundwater Quality of Highlands County, Florida

Site: HIF-37 Sun-Ray Farms

Well Number: 53

Depth: 1,450 feet

Site: HIF-13 Metzger

Well Number: 105

Depth: 1,106 feet

Site: ROMP 28 UFA (SUW)

Well Number: 89

Depth: 600 feet

Site: Maranatha Village

Well Number: 126

Depth: 841 feet

40

45

50

55

60

35

40

45

50

55

50

55

60

65

70

40

45

80

85

90

95

100

70

75

1980 1985 1990 1995 2000 2005 2010

YEAR

WATER LEVEL, IN FEET ABOVE NGVD 29

LOWESS CURVE (Helsel and Hirsch, 1992)

EXPLANATION

35

Figure 28. Water levels in selected wells completed in the Upper Floridan 

aquifer. Well locations shown in figure 11.
Hydrogeology 39

or mid 1970s (sites 1, 67, and 103), and one that began in 

the late 1970s (site 43). Results of the Kendall’s tau analyses 

indicate that water levels in three of the four surficial aquifer 

wells showed significant trends over respective periods of 

record (p < 0.05, table 1). One well (site 43) showed a slight 

rise in water levels while two wells (sites 67 and 103) showed 

slight declines.

Long-term water-level data from two monitoring wells 

completed in the intermediate aquifer system (sites 88 and 

166) and four monitoring wells completed in the Upper 

Floridan aquifer (sites 53, 89, 105, and 126) also were 

analyzed for trends (table 1). One of the intermediate aquifer 

system monitoring wells had water levels that began in the 

mid 1980s and another in the mid 1990s. Three of the Upper 

Floridan aquifer monitoring wells had water-level data that 

began in the early 1980s and one that began in the mid 1990s. 

Water-level altitudes in one intermediate aquifer system well 

(site 88) showed a significant but small rise in water levels 

(table 1). One Upper Floridan aquifer well showed a significant decline in water levels (site 53), whereas another showed 

a significant but small rise in water levels (site 89). Water 

levels in the remaining three wells (sites 105, 126, and 166) 

showed no significant trends.

Although the Kendall’s tau revealed water-level trends 

for the entire period of record for some wells, these trends 

may not be continuous and may vary over time. The use 

of LOWESS for trend analysis for the period of record 

shows these short-term rises and declines in water levels 

Figure 29. Simulated vertical leakage rates to and from the Upper Floridan aquifer. From Sepulveda (2002).

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Lorida

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

EXPLANATION

-9.99

0.01

3.01

-

-

-

0

3.00

10.00

VERTICAL LEAKAGE RATE, IN INCHES PER YEAR

Negative leakage rates indicate upward leakage and

positive leakage rates indicate downward leakage

10.01

25.01

-

-

25.00

30.00
40 Hydrogeology and Groundwater Quality of Highlands County, Florida

(figs. 20, 23, and 28). For example, although Kendall’s tau 

trend indicated a rise in water levels at site 43 for the period of 

record (fig. 20), the LOWESS line indicates that the rise was 

not constant. Specifically, water levels in the well decreased 

from the beginning of the record until the late 1980s, and then 

gradually increased after that period. The LOWESS lines for 

some of the other wells also indicate changing water-level 

trends over time. These oscillations probably are the result of 

cyclic variations in rainfall and related pumping over time. 

In addition, changes in the distribution of pumping also could 

account for some of the observed water-level trends.

Water-Level Comparisons

Comparisons of water levels in wells completed in the 

surficial aquifer, intermediate aquifer system, and Upper 

Floridan aquifer can be used to qualitatively evaluate the 

degree of hydraulic connection between these units and the 

direction of the vertical hydraulic gradient. The magnitude 

of the water-level difference at a particular site reflects the 

degree of confinement between aquifers, and is related to the 

lithology and thickness of the confining units. Thicker and 

hydraulically tighter confining units typically result in greater 

water-level differences and a reduced hydraulic connection 

between aquifers whereas smaller water-level differences 

between hydrologic units typically indicate a better hydraulic 

connection.

Water-level data comparisons for ROMP well pairs in 

Highlands and eastern DeSoto Counties show a wide variation in the magnitude of water-level differences between the 

surficial, intermediate, and Floridan aquifer systems (fig. 30). 

Hydrographs for wells 93 and 89 (ROMP 28) and wells 164 

and 163 (ROMP 43XX) in northern Highlands County show 

a water-level difference of about 10 to 20 ft between the surficial aquifer and Upper Floridan aquifer. Hydrographs at wells 

26 and 27 (ROMP 14) in southern Highlands County show 

large water-level differences between the surficial aquifer and 

Upper Floridan aquifer. Water levels at the site are about 85 

to 95 ft higher in the surficial aquifer than in the underlying 

Upper Floridan aquifer. At ROMP 14, a thick sequence of 

clays in the intermediate aquifer system separates the surficial 

aquifer from the Upper Floridan aquifer. These clays tend to 

restrict the downward movement of water to the underlying 

Upper Floridan aquifer.

Hydrographs of wells at ROMP 15 (wells 46 and 44) and 

ROMP 28 (wells 88 and 89) show relatively small waterlevel differences between the intermediate aquifer system 

and Upper Floridan aquifer. Water-level fluctuations in the 

intermediate aquifer system also mimic those observed in the 

Upper Floridan aquifer at these sites. This similarity in water 

level fluctuations indicates that leaky, relatively permeable or 

thin confining beds at these locations result in relatively good 

connection between the aquifers. 

Variations in water levels with depth can be illustrated 

by data collected during the drilling of four ROMP test wells 

(fig. 31). Three of the ROMP sites were located on the Lake 

Wales Ridge in Highlands County (ROMP 14, 28, and 29A), 

and one site was located in extreme southeastern DeSoto 

County (ROMP 13). Water-level data collected at the sites 

were not adjusted for changes in water levels with time or 

for density differences in the water that may have occurred 

between the various zones within each well. 

Water levels at all four of the ROMP sites show a 

general decrease in water levels with depth until penetration of the Upper Floridan aquifer (fig. 31) where the water 

levels become relatively steady. This indicates the potential 

for recharge from the surficial aquifer to the Upper Floridan 

aquifer. Water levels within the Upper Floridan aquifer at 

ROMP sites 14, 28, and 29A changed little as the drilling 

progressed. However, a substantial decrease in head was 

observed from about 1,100 to 1,300 ft below land surface at 

ROMP 28, where water levels averaged about 22 ft below 

land surface. This decline, however, was related to a regional 

potentiometric surface decline caused by dry conditions 

that typically prevail in May (DeWitt, 1998). Water levels 

also declined to about 27 ft below land surface as drilling 

progressed into middle confining unit II. According to 

DeWitt (1998), some of the observed decline in water levels 

can be attributed to an increase in fluid density due to an 

increase in mineralization of the groundwater.

Water-Budget Components

A water budget is an accounting of flow of water into 

and out of an area during a specific period of time. A generalized water budget for Highlands County was made by using 

measured or estimated values of rainfall, net lateral subsurface outflow, and net surface-water outflow. An estimate of 

evapotranspiration was calculated from the water-budget 

equation. A generalized water budget can be described by 

the following equation:

ET = P- Q0 - QR - ΔS (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 net surface-water outflow, in inches per year; and 

ΔS is the change in storage over time period. 

A generalized water budget was computed for Highlands 

County over a 10-year period from 1998 to 2007. A budget 

averaged over this length of time is more likely to be more 

representative of long-term conditions than a budget averaged 

over a shorter timeframe. When long-term average annual 

values of the various water-budget components are used, 

water released from or accumulated as storage (ΔS ) within 
Hydrogeology 41

WELL NUMBER 26 – Surficial aquifer

WELL NUMBER 25 – Intermediate aquifer system

WELL NUMBER 27 – Upper Floridan aquifer

(Suwannee Limestone)

WELL NUMBER 93 – Surficial aquifer

WELL NUMBER 88 – Intermediate aquifer system

WELL NUMBER 89 – Upper Floridan aquifer

(Suwannee Limestone)

WELL NUMBER 91 – Lower evaporite

WELL NUMBER 164 – Surficial aquifer

WELL NUMBER 163 – Upper Floridan aquifer

(Avon Park Formation)

WELL NUMBER 45 – Surficial aquifer

WELL NUMBER 46 – Intermediate aquifer system

WELL NUMBER 44 – Upper Floridan aquifer

YEAR

EXPLANATION

EXPLANATION

EXPLANATION

EXPLANATION

40

50

60

70

80

30

80

90

100

110

120

70

50

70

90

110

130

150

40

50

60

70

80

30

SITE: ROMP 14

SITE: ROMP 28

SITE: ROMP 43XX

SITE: ROMP 15

1990 1995 2000 2005 2010

WATER LEVEL, IN FEET ABOVE NGVD 29

the surficial aquifer can assume to be negligible. Therefore, 

assuming there is no change in storage, inputs are balanced by 

outputs. It was also assumed that all groundwater pumped out 

was returned to the system as wastewater or irrigation return 

flow and that no groundwater was being imported into or 

exported out of the county.

The largest input component in the water budget was 

precipitation, which averaged 51.9 in/yr from 1998 to 2007 

at three rainfall stations (Archbold Biological Station, Avon 

Park, and DeSoto). Ten-year rainfall averages varied across 

Highlands County during this period, ranging from 50.5 in/yr 

at Avon Park to 53.6 in/yr at Archbold Biological Station.

Figure 30. Water levels in selected wells open to the surficial aquifer, intermediate aquifer system, and Upper 

Floridan aquifer. Well locations shown in figures 1 and 11.
42 Hydrogeology and Groundwater Quality of Highlands County, Florida

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

ROMP 13

DeSoto County

Land surface altitude = 62 feet above NGVD 29

Drilling: started January, 1994; terminated June, 1994

0 5 10 15 20

Top of middle confining units II or VI?

Top of Upper Floridan aquifer

Top of Intermediate

aquifer system

EXPLANATION

DRILL STEM

0 40 120

WATER LEVEL, IN FEET

BELOW LAND SURFACE

20 60 80 100

Top of Upper Floridan aquifer

Top of Intermediate

aquifer system

EXPLANATION

DRILL STEM

ROMP 14

Highlands County

Land surface altitude = 145 feet above NGVD 29

Drilling: started January, 1992; terminated April, 1995

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

ROMP 28

Highlands County

Land surface altitude = 82 feet above NGVD 29

Drilling: started December, 1991; terminated June, 1994

ROMP 29A

Highlands County

Land surface altitude = 128 feet above NGVD 29

Drilling: started December, 2000; terminated April, 2001

Top of Upper

Floridan aquifer

Top of Intermediate

aquifer system

Top of

Upper Floridan aquifer

Top of intermediate

confining unit

0 10 20 30 40 0 10 20 30 40 50 60 70

EXPLANATION

DRILL STEM

EXPLANATION

DRILL STEM

PACKER TEST

WELL DEPTH, IN FEET BELOW LAND SURFACEWELL DEPTH, IN FEET BELOW LAND SURFACE

WELL DEPTH, IN FEET BELOW LAND SURFACEWELL DEPTH, IN FEET BELOW LAND SURFACE

WATER LEVEL, IN FEET

BELOW LAND SURFACE

WATER LEVEL, IN FEET

BELOW LAND SURFACE

WATER LEVEL, IN FEET

BELOW LAND SURFACE

Top of middle confining unit II

Top of Upper Floridan aquifer

Top of Avon Park

permeable zone

Top of Avon Park

permeable zone Top of Avon Park

permeable zone

Top of Avon Park

permeable zone

Top of middle confining units II or VI?

Top of middle confining

units II or VI?

Figure 31. Water levels during drilling of monitoring wells. Modified from Peterman and Rappuhn (1997), 

Clayton (1998), DeWitt (1998), and Mallams and Lee (2005). Site numbers refer to figure 1.
Assessment of Groundwater Quality 43

Net lateral subsurface outflow (Q0) from Highlands 

County was determined by using a USGS modular groundwater flow model (Nicasio Sepúlveda, U.S. Geological Survey, 

written commun., 2009). Net lateral outflow was determined 

for the surficial aquifer (0.02 in/yr), the intermediate aquifer 

system (0.06 in/yr), the Upper Floridan aquifer (0.69 in/yr), and 

the Lower Floridan aquifer (0.23 in/yr). Net lateral subsurface 

outflow from the four aquifers was 1.00 in/yr. 

Water leaving the county as streamflow (QR) averaged 

about 9.7 in/yr from 1998 to 2007, based on the analysis of 

streamflow records at 12 USGS and SFWMD gaging sites 

located within or just outside Highlands County. These gaged 

surface-water sites include Arbuckle Creek near DeSoto 

City (station number-02270500), Arbuckle Creek near Avon 

Park (02269600), Carter Creek near Sebring (02270000), 

Fisheating Creek near Lake Placid (02255600), Fisheating 

Creek at Palmdale (02256500), Fisheating Creek near Venus 

(02256000-discontinued site), Little Charley Bowlegs Creek 

near Sebring (02296222 and 02296223), Kissimmee River at 

S65A, Kissimmee River at S65E, S70 (Harney Pond Canal), 

S75 (C-40 Canal), and S84 (C-41A Canal). At Little Charlie 

Bowlegs Creek, discharge measurements were not available 

from 1998 to 2007. Instead, historical discharge measurements 

from 1953 to 1982 and 2005 were averaged in lieu of current 

discharge measurements. Flows entering or exiting the county 

from Arbuckle Creek and Fisheating Creek, respectively, were 

estimated based on the ratios of drainage areas and measured 

at stations upstream and downstream from the county line. 

It was assumed in the water budget that one-half of the 

streamflow from the Lower Kissimmee River basin originated 

in Highlands County and the other half in Okeechobee County.

Evapotranspiration is the largest output component in the 

water budget. Evapotranspiration was calculated from equation 1 and accounted for 41.0 in/yr of water removed from 

the hydrologic system. This back-calculated value of evapotranspiration is a reasonable estimate for Highlands County, 

because it falls within the range of evapotranspiration values 

determined for the area—27 in/yr reported for a well-drained, 

deep, water-table site along the Lake Wales Ridge in southwestern Orange County (Sumner, 1996), and about 56.5 in/yr 

reported for a 2-year period at Lake Starr in east-central Polk 

County (Swancar and others, 2000). This latter value is likely 

indicative of a potential evapotranspiration rate.

Assessment of Groundwater 

Quality

The quality of groundwater is controlled by the chemical 

reactions that occur as groundwater moves through an 

aquifer. When rainfall enters the soil, it absorbs additional 

carbon dioxide to produce a weak carbonic acid. As water 

moves through the sediments, it is chemically altered 

through mineral dissolution, precipitation, cation exchange, 

oxidation-reduction anion exchange, and sorption of organic 

molecules (Crandall, 2000). The effects on water chemistry 

are also determined by aquifer and overburden geology, rates 

of groundwater flow, the residence time of water in contact 

with the aquifer matrix, and the impact of human influence. 

Additionally, in parts of Highlands County, the effects of periodic Pleistocene inundations of the sea are present in the form 

of residual diluted seawater. The resultant products of these 

various reactions determine whether the groundwater will be 

of suitable quality for a particular purpose. For example, water 

containing high total dissolved-solids or chloride concentrations may be too mineralized for public supply, industrial, 

or agricultural use. The limiting concentrations of chloride 

recommended for plants, animals, and industrial use are shown 

in figure 32.

Knowledge about variations in water quality within an 

aquifer is important in assessing the availability of water 

for public, agricultural, industrial, or other uses. For many 

uses, water-quality standards have been established that 

set acceptable concentration limits on constituents in water 

used for a particular purpose. For water that is being distributed by public-supply systems, the Florida Department of 

Environmental Protection (2008) has established primary 

and secondary standards for drinking water. The primary 

drinking-water standards establish maximum limits that apply 

to the physical and chemical characteristics of water that may 

affect the health of the consumer. The secondary drinkingwater standards establish recommended limits on certain 

chemical constituents that cause offensive taste, odor, color, 

corrosivity, foaming, or staining. Secondary standards are not 

enforceable and are intended only as guidelines. The principal 

chemical constituents in groundwater that can affect potability 

of groundwater in the area are nitrate, chloride, sodium, 

sulfate, and the amount of total dissolved solids in the water. 

Concentrations of nitrate as nitrogen greater than 10 mg/L 

exceed State primary drinking-water standards, as do sodium 

concentrations exceeding 160 mg/L. Secondary drinking-water 

standards specify maximum limits of 250 mg/L for chloride 

and sulfate concentrations, and 500 mg/L for total dissolvedsolids concentrations (Florida Department of Environmental 

Protection, 2008).

Total dissolved-solids concentrations are often not 

included in the chemical analyses of groundwater. Estimates 

of dissolved-solids concentrations, however, can easily be 

obtained by measuring specific conductance. Specific conductance is the ability of water to conduct an electrical current and 

is related to the presence of charged ionic species in the water. 

As ion concentrations increase, the conductance of the solution increases; therefore, the specific conductance provides an 

indication of ion concentration (Hem, 1985). Figure 33 shows 

a plot of the total dissolved-solids concentration with the 

specific conductance for all of the wells sampled in the study 

area. Although most of the values plotted in the graph are from 

Highlands County, some of the data are from adjacent counties. For the range of specific conductance values measured, 

multiplication of the specific conductance by 0.59 gives a 

reasonable approximation of dissolved-solids concentrations. 
44 Hydrogeology and Groundwater Quality of Highlands County, Florida

10

100

1,000

10,000

100,000

250

19,000

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

LIMITING CONCENTRATIONS

FOR PLANTS

(modified from Campbell

and others, 1984)

Injures some orchids.

Kills azaleas, causes injury

to some tender plants,

vegetables, flowers, and

citrus foliage.

Damages a number of

succulent plants.

Damages bahia grass,

sweetgum, tibouchina, and

many foliage plants.

Injures many wood plants

including citrus (root area).

Not recommended for plant

use except St. Augustine

grass. May damage or kill

plants when watering lawn.

Trout

Various fish

Cattle, sheep,

swine, chickens

All livestock and

bass, pike, perch

Carp eggs

Small bluegills

LIMITING CONCENTRATIONS

FOR ANIMALS

(McKee and Wolf, 1963)

Sugar

manufacturing

Photographic

process

Dairy industry

(cleanup)

Textile

manufacturing

Carbonated

beverages and

food-equipment

washing

Brewing (beer)

Irrigation water

Paper mills

(process water)

Food canning

and freezing

4.5

LIMITING CONCENTRATIONS

FOR INDUSTRIAL USES

(McKee and Wolf, 1963)

SEAWATER

RECOMMENDED UPPER LIMIT

FOR PUBLIC SUPPLY

(U.S. Environmental Protection

Agency, 2009)

RANGE OF VALUES

POINT VALUE

EXPLANATION

Figure 32. Limiting concentrations of chloride recommended for plants, animals, public-supply, and industrial use. 

Modified from Schiner (1993).

Figure 33. Relation between specific conductance and total dissolved-solids concentration.

10

100

1,000

10,000

10 100 1,000 10,000 100,000

TOTAL DISSOLVED-SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

SPECIFIC CONDUCTANCE, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS

1

1
Assessment of Groundwater Quality 45

When chloride concentrations are not available, chloride 

concentrations can also be estimated by measuring specific 

conductance. The relation between chloride concentration and 

specific conductance is shown in figure 34. The plot shows 

that the relation between specific conductance and chloride 

concentration is not as strong as between specific conductance 

and total dissolved-solids concentration, particularly at specific 

conductance values below about 800 μS/cm. Reasonable 

estimates of chloride can be provided at conductance values 

above this threshold value. In some less-mineralized waters, 

chloride may not be the major constituent and specific conductance instead may be more closely related to other constituents.

Water-chemistry data collected by the USGS and State 

agencies were compiled for this study (apps. 2 and 3). During 

this study, additional water samples from 58 wells were 

collected and analyzed by the USGS for major chemical 

constituents from 2006 to 2008. Samples were collected from 

6 wells completed in the surficial aquifer, 15 wells completed 

in the intermediate aquifer system, and 37 wells completed in 

the Upper Floridan aquifer. In addition, water-quality samples 

from 71 wells were collected by the SFWMD, SWFWMD, 

FDEP, and Highlands County during 2000–08 and are 

also included in appendixes 2 and 3. These data include 

40 samples from the surficial aquifer, 10 samples from the 

intermediate aquifer system, and 21 samples from the Upper 

Floridan aquifer. Listed for comparison in tables 3 and 4 are 

the minimum, maximum, and median values for all of the 

groundwater-quality constituents used in this report. 

Figure 34. Relation between chloride 

concentration and specific conductance.

10

100

1,000

10,000

1 10 100 1,000 10,000

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

100,000

1

SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

Table 3. Summary statistics of groundwater quality of the surficial aquifer and intermediate aquifer system in Highlands County.

[Concentrations shown in milligrams per liter, except for pH, in standard units; specific conductance, in microsiemens per centimeter; strontium, in 

micrograms per liter; and temperature, in degrees Celsius. <, less than the value]

Constituent

Surficial aquifer Intermediate aquifer system

Number of 

samples Minimum Median Maximum Number of samples Minimum Median Maximum

Alkalinity, as CaCO3 35 0.50 13 300 15 21 154 290

Calcium 41 .27 19 120 16 5.5 36 160

Chloride 43 2.6 13 54 19 3.8 13 3,770

Fluoride 37 <.02 .10 1.2 17 <.12 .44 1.9

Hardness, as CaCO3 7 4.0 13 159 12 17 175 1,200

Magnesium 41 .03 5.2 20 16 .87 14 186

Nitrate plus nitrite, as N 37 .004 .79 22 13 .004 <.04 <.04

Orthophosphate, as P 20 .004 .027 4.5 13 .004 .007 1.5

pH 40 4.1 5.2 7.3 19 6.4 7.5 8.7

Phosphorus 36 .004 .016 5.2 13 .003 <.006 1.6

Potassium 42 .06 1.9 23 16 1.2 2.4 37

Silica 26 .29 6.3 20 14 11 29 47

Sodium 43 1.1 5.5 58 16 3.9 15 1,940

Specific conductance 40 32 217 723 19 66 424 11,500

Strontium 24 6.8 <250 2,190 15 28 720 26,900

Sulfate 38 .20 23 87 19 .12 2.5 111

Temperature 40 21.5 25.9 29.5 19 19.7 24.1 25.2

Total dissolved solids 22 15 109 443 15 58 265 6,810
46 Hydrogeology and Groundwater Quality of Highlands County, Florida

Surficial Aquifer

Concentrations of major ions and nutrients in groundwater 

in the surficial aquifer are variable and distinct patterns are 

evident. Several factors are responsible for this variability, 

including the lithology of the sediments, the interaction with 

the underlying aquifer, and most importantly, the effects 

of land use. Along the Lake Wales Ridge, citrus production has been prominent in the area since the early 1900s 

because of its sandy well-drained soils (Southwest Florida 

Water Management District, 2004a). Fertilizers, insecticides, 

fungicides, and herbicides are often applied to the groves 

to help increase crop yields and control pests and disease. 

These sandy soils, however, often have a low organic content 

and a limited capacity for filtering contaminants from water 

recharging the aquifer, thus increasing the vulnerability of the 

surficial aquifer to chemical contamination (Choquette and 

Sepúlveda, 2000).

Groundwater in the surficial aquifer in Highlands County 

generally has low concentrations of major ions and total 

dissolved-solids. The water types of the surficial aquifer are 

variable, and as indicated in the trilinear diagram on figure 35, 

can be a calcium bicarbonate, calcium sulfate, sodium 

chloride, or mixed cation and anion water type. Mixed water 

types associated with water in the surficial aquifer may reflect 

contributions of irrigation water as well as the addition of 

fertilizers to soil in citrus groves (Crandall, 2000). The results 

of chemical analyses of water from the surficial aquifer in 

Highlands and adjacent counties are presented in appendixes 

2 and 3. Of the constituents analyzed for this study, with the 

exception of nitrate, water quality of the surficial aquifer in 

Highlands County is within the FDEP primary and secondary 

drinking-water standards.

Major Ions and Physical Characteristics

The generalized distributions of specific conductance, 

chloride, and sulfate in water from the surficial aquifer are 

shown in figures 36 to 38. As evident, water-quality data in 

the surficial aquifer are sparse in western and parts of eastern 

Highlands County. In Highlands County, specific conductance 

ranged from 32 to 723 μS/cm (fig. 36, app. 2, and table 3), 

with a median value of 217 μS/cm. Although data are lacking 

in parts of the county, the lowest specific conductance values 

(less than 200 μS/cm) generally occur just east and west of 

the Lake Wales Ridge, and the highest values (greater than 

350 μS/cm) occur in a few areas along the Lake Wales Ridge 

and in the eastern part of the county. Total dissolved-solids 

Table 4. Summary statistics of groundwater quality of the Upper Floridan aquifer in 

Highlands County.

[Concentrations shown in milligrams per liter, except for pH, in standard units; specific conductance, in 

microsiemens per centimeter; strontium, in micrograms per liter; and temperature, in degrees Celsius. 

<, less than the value]

Constituent Number of 

samples Minimum Median Maximum

Alkalinity, as CaCO3 28 55 100 205

Calcium 28 4.4 28 71

Chloride 34 4.4 12 403

Fluoride 26 .09 .28 3.6

Hardness, as CaCO3 23 64 130 410

Magnesium 28 4.3 13 57

Nitrate plus nitrite, as N 22 <.04 <.04 .22

Orthophosphate, as P 22 .005 .010 .251

pH 30 7.0 8.0 9.6

Phosphorus 22 <.006 .011 .272

Potassium 29 .63 1.8 9.3

Silica 28 9.7 17 35

Sodium 29 3.8 12 208

Specific conductance 34 133 307 1,900

Strontium 28 725 5,150 20,730

Sulfate 33 <.18 23 255

Temperature 30 22.4 25.3 28.4

Total dissolved solids 28 96 199 1,050
Assessment of Groundwater Quality 47

concentrations in the surficial aquifer, determined from 

actual measured values and calculated values, are below the 

500-mg/L recommended FDEP limits. 

Chloride in groundwater from the surficial aquifer may 

be derived from several sources including the upward leakage 

of water from the Upper Floridan aquifer (in the eastern part 

of the County), septic-tank effluent, industrial waste, and small 

amounts contributed by rainfall. However, the most likely 

source of increased chloride and other inorganic constituents 

measured in groundwater from the surficial aquifer is through 

the use of agricultural chemicals in citrus areas and by the 

application of irrigated water from the Upper Floridan aquifer. 

Along the Lake Wales Ridge, fertilizers are the most likely 

source of increased chloride as well as potassium, sodium, 

and sulfate concentrations to groundwater, because fertilizers 

have been applied as potassium nitrate, potassium chloride, or 

sulfate salts (Choquette and Kroening, 2009).

Chloride concentrations in water from the surficial 

aquifer in Highlands County ranged from 2.6 to 54 mg/L, with 

a median value of 13 mg/L (fig. 37, app. 2, table 3). Chloride 

concentrations less than 10 mg/L occurred over much of the 

central and western parts of the county. Over parts of the Lake 

Wales Ridge and eastern Highlands County, concentrations 

ranged from 10 to 25 mg/L. Highest concentrations (exceeding 

25 mg/L) occurred primarily in the southeastern part of the 

county and in a small area along the southern part of the Lake 

Wales Ridge. 

Sulfate concentrations in water sampled from the surficial 

aquifer ranged from 0.20 to 87 mg/L (fig. 38, app. 2), with 

a median value of 23 mg/L (table 3). Sulfate concentrations were generally less than 10 mg/L throughout much of 

the eastern and western parts of Highlands County. Sulfate 

concentrations greater than 30 mg/L occurred primarily along 

the Lake Wales Ridge and in a small area in the southeastern 

part of the county. Small amounts of sulfate are obtained from 

oceanic sulfate aerosols and from the atmospheric oxidation of 

sulfides (Rye and others, 1981). In Highlands County, sulfate 

in the surficial aquifer 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). In areas where the Upper Floridan aquifer is used for 

irrigation and contains higher sulfate concentrations, additional sulfate may be added to surficial aquifer groundwater.

100

80

60

40

20

0

0

20

40

60

80

100 0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0 100

80

60

40

20

0

Calcium

Magnesium

Sodium plus Potassium

Chloride, Fluoride, Nitrate plus Nitrite

Carbonate plus Bicarbonate

Sulfate

Sulfate plus Chloride

Calcium plus Magnesium

PERCENT

PERCENT

0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0

100

80

60

40

20

0

PERCENT

Figure 35. Chemical composition of water from the surficial aquifer.
48 Hydrogeology and Groundwater Quality of Highlands County, Florida

Nutrients

 Nutrient analyses are an important component of 

a groundwater-quality assessment, because the surficial 

aquifer can be contaminated with nitrogen and phosphorus 

compounds. Nitrogen occurs in a number of chemical forms, 

is part of many biological processes, and is required for the 

production of food (Wheaton and Graham, 2000). Nitrogen 

and phosphorus compounds in groundwater generally are the 

result of human activities, such as the application of fertilizers or because of the presence of human or animal waste. 

In surface water, high nutrient concentrations accelerate 

eutrophication. Dense vegetation growth can result in oxygen 

depletion in water due to plant death and subsequent decay. 

In groundwater, nitrate concentrations are an important 

limiting factor for potable water supply. High concentrations 

of nitrate in drinking water may cause methemoglobinemia in 

small children (Hem, 1985).

Most of the Lake Wales Ridge is underlain by soils that 

have been classified as vulnerable to leaching of agrichemicals 

(Choquette and Kroening, 2009). A group of soils common 

to the ridge areas that has been classified as vulnerable to 

leaching includes the Candler, Astatula, and Paola Soil Series 

(Choquette and Kroening, 2009). These soils exhibit minimal 

soil development, contain little organic matter, consist of 

Figure 36. Generalized distribution of specific conductance in water from the surficial aquifer.

200 - 350

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

175 WELL – Number indicates

specific conductance

< 200

> 350

SPECIFIC CONDUCTANCE IN

MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

EXPLANATION

86

88

53

44 61

51

91

32

41

97 66

46

60

525

429

280

218

369 197 458

271

179

368

640

224 399

335

314

216

313

214

418

516 685

723 234

150

137 175

384

331

320

210

287
Assessment of Groundwater Quality 49

about 97 to 99 percent sand-sized particles, and have a high 

hydraulic conductivity (Choquette and Kroening, 2009). 

Nitrates are not retained by these soils, and nitrate not taken 

up by plants readily moves into the groundwater with rainfall 

or excessive irrigation.

Nitrate concentrations in water from the surficial aquifer 

ranged from 0.004 to 22 mg/L (fig. 39 and app. 3), with a 

median value of 0.79 mg/L (table 3). About half of the samples 

had nitrate concentrations less than or equal to the USGS 

reporting limit of 0.04 mg/L as nitrogen. The lowest concentrations generally were found east and west of the Lake Wales 

Ridge. Nitrate concentrations above the maximum contaminant level (MCL) are often found in the surficial aquifer 

along the Lake Wales Ridge. Water samples from seven wells 

along the Lake Wales Ridge had nitrate concentrations greater 

than 10 mg/L. Data obtained from the Florida Department 

of Environmental Protection (Rick Hicks, written commun., 

2007) also show a number of water samples from wells along 

the Lake Wales Ridge with nitrate concentrations exceeding 

10 mg/L (fig. 39) and a maximum concentration of 52 mg/L. 

Tihansky and Sacks (1997) reported nitrate concentrations 

in groundwater samples ranging from 4.9 to 57 mg/L in the 

citrus land-use areas of Polk and Highlands Counties. Nitrate 

concentrations greater than 10 mg/L as nitrogen exceed State 

primary drinking-water standards (Florida Department of 

Environmental Protection, 2008). 

Figure 37. Generalized distribution of chloride concentrations in water from the surficial aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

41

29

19 13

15

23

19 36

20 14

23

11

16

51

12

22

29 51

48

10

30

52

38

30

54 11

10 11

5.1

8.3

8.2

7.7

5.5 6.5

3.3

3.9

8.3

2.6

8.5

7.8

2.9

4.8

4.2

6.0

7.2

21

Lorida

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

30

EXPLANATION

< 10

> 25

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

WELL – Number indicates

chloride concentration

10 - 25
50 Hydrogeology and Groundwater Quality of Highlands County, Florida

Concentrations of nitrate in groundwater underlying 

undeveloped areas generally are low, indicating that natural 

sources of nitrate do not contribute substantially to concentrations in groundwater. Nitrate concentrations of water samples 

underlying the Ocala National Forest in Lake and Marion 

Counties were less than 1.0 mg/L (Adamski and Knowles, 

2001). Water samples collected from the surficial aquifer 

beneath undeveloped land at two sites in Polk and Highlands 

Counties had concentrations of less than 0.002 mg/L (Tihansky 

and Sacks, 1997). Likely sources of nitrate in these undeveloped 

areas are usually organic matter in soils and atmospheric deposition. In central Florida, the concentration of nitrate in rainwater 

generally is less than 1.0 mg/L (Adamski and German, 2004). 

Other nutrients of interest in the study area are 

orthophosphate and phosphorus. Concentrations of dissolved 

orthophosphate in water from the surficial aquifer in Highlands County ranged from 0.004 to 4.5 mg/L, with a median 

value of 0.027 mg/L. Phosphorous concentrations ranged from 

0.004 to 5.2 mg/L, with a median value of 0.016 mg/L (app. 3 

and table 3). 

Orthophosphate concentrations are typically low in the 

surficial aquifer because phosphate-bearing minerals are generally uncommon in the surficial aquifer (at least in the upper 

part). In addition, because of the ability of phosphate ions to 

sorb onto metal oxides, especially ferric and manganese oxyhydroxides, background concentrations in water greater than a 

Figure 38. Generalized distribution of sulfate concentrations in water from the surficial aquifer.

30 WELL – Number indicates

sulfate concentration

< 10

30 or greater

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

68

54

30

30

54

63

76

21

87

39

40

45

30

69

36

30 17

16

29

51

51

44

1.0

1.9

9.8

5.3

7.4

7.1

1.8

2.0

2.8

2.0

3.9 7.0 2.1

0.20

0.87

0.20

0.20

0.20

0.23

Lorida

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

10 - 29

EXPLANATION

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER
Assessment of Groundwater Quality 51

few tenths or hundredths of a milligram per liter are rare (Hem, 

1985). Sources of orthophosphates in the surficial aquifer can 

be mineral (primarily apatite), sewage effluent, animal waste, 

or fertilizers. The maximum concentration of phosphorus is not 

regulated in drinking water; however, elevated concentrations 

of phosphorus in surface water can cause excessive growth of 

algae and cyanobacteria (Adamski and German, 2004).

Intermediate Aquifer System

The chemical composition of most of the groundwater 

sampled from the intermediate aquifer system is dominated 

by calcium and bicarbonate. Major cation and anion equivalent concentrations are illustrated on a trilinear diagram in 

figure 40. Analytical data of water from the intermediate 

aquifer system in Highlands and adjacent counties are given 

in appendixes 2 and 3. The water producing units were not 

differentiated because geologic or hydrologic information 

was not available for many of the sites. In general, most 

constituent concentrations were less than the FDEP primary 

and secondary drinking-water standards. Specific conductance 

Figure 39. Generalized distribution of nitrate concentrations in water from the surficial aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

#

# #

#

#

#

#

#

#

#

#

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##

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#

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#

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#

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< 10 10 or greater

20

19

17

13

11

22

11

8.9

7.7

8.1

1.6

9.4

8.4

1.4

3.2

9.6

9.6

<0.04

<0.04

<0.02

0.02

<.02

0.31 0.79

<0.06

<0.04

0.004

0.006

0.017

0.022 0.004 0.005

0.004

0.024

0.005

0.005

#

<0.04

Lorida

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Cornwell

Archbold

Biological

Station

Approximate extent of

nitrate concentrations

> 10 mg/L

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

11

EXPLANATION

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

WELL – Where nitrate concentration

is equal to or greater than 10 milligrams

per liter have been reported by the

Florida Department of Environmental

Protection (1990-2006).

WELL – Number indicates nitrate

concentration in

(2000-2008).

milligrams per liter
52 Hydrogeology and Groundwater Quality of Highlands County, Florida

and chloride concentrations in water from the intermediate 

aquifer system are shown in figures 41 and 42. Specific 

conductance values for Highlands County ranged from 66 to 

11,500 μS/cm, with a median value of 424 μS/cm. Chloride 

concentrations in water ranged from 3.8 to 3,770 mg/L, with a 

median value of 13 mg/L. Specific conductance and chloride 

concentrations were lowest primarily in the northwestern and 

south-central parts of the county and highest in the southwestern and southeastern parts. Sulfate concentrations ranged 

from 0.12 to 111 mg/L, and hardness as CaCO3 (calcium 

carbonate) concentrations ranged from 17 to 1,200 mg/L. 

The median values for sulfate and hardness were 2.5 and 

175 mg/L, respectively. Nitrate, orthophosphate, and phosphorus concentrations ranged, respectively, from 0.004 to less 

than 0.04 mg/L, 0.004 to 1.5 mg/L, and 0.003 to 1.6 mg/L.

The highest values for specific conductance, chloride 

concentration, and water hardness (as CaCO3) in the intermediate aquifer system were obtained from a 500-ft deep 

well (well 22) in southern Highlands County. These values 

also were the highest values reported from any aquifer in the 

county. The specific conductance of water from this well was 

11,500 μS/cm. Hardness and chloride concentrations were 

1,200 and 3,770 mg/L, respectively. Sulfate concentration, 

although not anomalously high, was 111 mg/L. The source of 

this highly mineralized water is probably relict seawater that 

entered the intermediate aquifer system during Pleistocene 

age. This zone of mineralized water, probably trapped in strata 

of low permeability, has not been removed by the modern-day 

freshwater flow system.

Upper Floridan Aquifer

The Upper Floridan aquifer is the most productive and 

widely used aquifer in Highlands County. In much of the 

county, water in the Upper Floridan aquifer generally meets 

FDEP primary and secondary drinking-water standards. 

However, more mineralized water is present at depth beneath 

the entire county. Chemical analyses of groundwater samples 

from wells completed in the Upper Floridan aquifer indicate 

differences in the ionic composition of water, and several 

chemical types of groundwater occur in the study area. 

100

80

60

40

20

0

0

20

40

60

80

100 0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0 100

80

60

40

20

0

Calcium

Magnesium

Sodium plus Potassium

Chloride, Fluoride, Nitrate plus Nitrite

Carbonate plus Bicarbonate

Sulfate

Sulfate plus Chloride

Calcium plus Magnesium

PERCENT

PERCENT

0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0

100

80

60

40

20

0

PERCENT

Figure 40. Chemical composition of water from the intermediate aquifer system.
Assessment of Groundwater Quality 53

The first chemical type, dominated by calcium, 

magnesium, and bicarbonate ions, generally occurs in the 

recharge area along the Lake Wales Ridge. This water type 

results from the dissolution of carbonate rocks that form 

the aquifer. The relatively large percentage of magnesium 

in the water samples is probably related to the dissolution 

of dolomite in the carbonate sequence of the aquifer. This 

first water type, which is generally low in dissolved solids, 

is represented by the data just above the left apex of the 

diamond-shaped area in figure 43. The second groundwater 

type contains calcium, magnesium, and sulfate. This water 

type, represented by samples from wells that plot toward 

the upper apex of the diamond, is often more mineralized 

than the calcium bicarbonate type and is primarily due to the 

dissolution of sulfate-bearing minerals. The third groundwater 

type, dominated by sodium and chloride, occurs primarily in 

the eastern part of Highlands County. The sodium chloride 

water type represents the mixing of freshwater with relict 

seawater. Analyses of sodium chloride water are plotted above 

the right apex of the diamond (fig. 43).

Major Ions and Physical Characteristics

Maps of specific conductance, chloride, sulfate, and 

water hardness (as CaCO3) for the Upper Floridan aquifer 

were constructed to delineate water-quality differences across 

Figure 41. Generalized distribution of specific conductance in water from the intermediate aquifer system.

< 250

501 - 1,000

250 - 500

> 1,000

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

Archbold

Biological

Station

66

181

184

304

159

394

374

390

424 361

783

501

343 655

678

459

468 672

543

222

589

510e

1,280

11,500

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

543

EXPLANATION

SPECIFIC CONDUCTANCE IN

MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

Dashed where approximate

WELL – Number indicates

specific conductance.

“e” indicates estimated value.

?

?
54 Hydrogeology and Groundwater Quality of Highlands County, Florida

Highlands County (figs. 44–47). Concentrations of these 

constituents varied areally and with depth in the study area. 

The majority of water samples collected from wells completed 

in the Upper Floridan aquifer came from wellhead samples. 

In Highlands County, wells are commonly constructed with 

tens to hundreds of feet of open-hole section. Water pumped 

from these wells consists of water derived from the openhole section of the borehole, and the water may come from 

more than one producing zone. Because each zone can have 

distinctive water-quality characteristics, the quality of water 

pumped from a well depends on which zones are tapped and 

the proportion of water derived from each zone. In cases 

where a well is completed in both the upper and lower parts of 

the Upper Floridan aquifer, the quality of the pumped water is 

likely to be more representative of the lower part of the Upper 

Floridan aquifer (Avon Park permeable zone) because of its 

higher transmissivity.

Specific conductance in the Upper Floridan aquifer in 

Highlands County ranged from 133 to 1,900 μS/cm, with a 

median value of 307 μS/cm (fig. 44, table 4). The areas of 

lowest specific conductance (less than 250 μS/cm) generally 

occurred in the northwestern and west-central parts of the 

county. In the area roughly adjacent to and including parts 

of the Lake Wales Ridge, specific conductance ranged from 

about 250 to 500 μS/cm. Specific conductance values were 

greatest (more than 1,000 μS/cm) in the extreme southwestern 

and eastern parts of the county, with the latter being a 

discharge area.

Figure 42. Generalized distribution of chloride concentrations in water from the intermediate aquifer 

system.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

32

10

12 23

54

43

13 63

43

45

38

13

30

6.6

6.1

6.1

4.1

9.6

7.3 6.9

7.9 3.8

5.4

272

3,770

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Archbold

Biological

Station

?

?

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

EXPLANATION

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

Dashed where approximate

13 WELL – Number indicates

chloride concentration

10 - 25

> 250

< 10

26 - 250
Assessment of Groundwater Quality 55

Measured total dissolved-solids values (app. 2, table 4) 

indicate that total dissolved solids in water in the Upper 

Floridan aquifer in Highlands County ranged from 96 to 

1,050 mg/L, with a median value of 199 mg/L. Most calculated total dissolved-solids values determined from specific 

conductance (fig. 33) also fell within this range. With the 

exception of the areas in the extreme southwestern and 

extreme eastern Highlands County, total dissolved-solids 

concentrations were below the 500-mg/L recommended 

FDEP limits. 

Chloride concentrations in the Upper Floridan aquifer 

in Highlands County ranged from 4.4 to 403 mg/L (fig. 45, 

app. 2), with a median value of 12 mg/L (table 4). The lowest 

concentrations, less than 10 mg/L, generally occurred along 

the recharge area of the Lake Wales Ridge. Concentrations 

ranging from 26 to 250 mg/L occurred in the southwestern 

and eastern parts of the county. Chloride concentrations were 

below the 250-mg/L recommended limit for drinking water 

throughout most of the county, with the exception of the 

extreme southwestern and extreme eastern parts of the county. 

Bradner (1994) reported chloride concentrations greater than 

400 mg/L in Okeechobee County just east of Brighton, and 

Klein and others (1964) reported chloride concentrations 

exceeding 1,000 mg/L in the extreme northeastern part of 

Glades County. 

Chloride concentration often is used as an indicator to 

delineate the extent of saltwater intrusion within an area. 

Most of the mineralized water in the Upper Floridan aquifer 

in southeastern Highlands County (and into Glades County) 

probably is a mixture of freshwater and relict seawater that 

entered the aquifer during a higher stand of sea level in the 

geologic past and has not been completely flushed from the 

aquifer. Natural salts of chloride (halite) are not present in the 

Upper Floridan aquifer (Sprinkle, 1989).

Sulfate concentrations in the Upper Floridan aquifer in 

Highlands County ranged from less than 0.18 to 255 mg/L 

(fig. 46, app. 2), with a median value of 23 mg/L (table 4). 

Concentrations of less than 10 mg/L generally occurred in the 

northwestern and west-central parts of the county and from 

30 to 250 mg/L in much of the western and eastern parts of 

the county. Sulfate concentrations exceeded 250 mg/L in the 

extreme southeastern part of the county near the Kissimmee 

River, and possibly in the extreme western part of the county 

near the DeSoto/Hardee County line.

100

80

60

40

20

0

0

20

40

60

80

100 0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0 100

80

60

40

20

0

Calcium

Magnesium

Sodium plus Potassium

Chloride, Fluoride, Nitrate plus Nitrite

Carbonate plus Bicarbonate

Sulfate

Sulfate plus Chloride

Calcium plus Magnesium

PERCENT

PERCENT

0

20

40

60

80

100

0

20

40

60

80

100

100

80

60

40

20

0

100

80

60

40

20

0

PERCENT

Figure 43. Chemical composition of water from the Upper Floridan aquifer.
56 Hydrogeology and Groundwater Quality of Highlands County, Florida

The principal processes responsible for the presence of 

sulfate in water from the Upper Floridan aquifer are the dissolution 

of sulfur-bearing minerals in the aquifer and the mixing of freshwater with water having a chemical composition similar to that 

of seawater. The dissolution of gypsum and dilution of seawater 

have distinct trends on a plot of the relation of the mass ratio of 

sulfate to chloride and the sulfate concentration of water samples 

(Rightmire and others, 1974). Figure 47 shows that groundwater 

having a low sulfate-chloride ratio and a high sulfate concentration is represented by points plotting near the seawater-mixing 

trend line. Groundwater having a high sulfate-chloride ratio is 

represented by points plotting near the dissolution of the gypsummixing trend line, indicating that gypsum is the major source of 

sulfate in water in the Upper Floridan aquifer. Most samples plot 

Figure 44. Generalized distribution of specific conductance in water from the Upper Floridan aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake Placid

Lorida

Cornwell

Archbold

Biological Station

391

936

684

479

498

170

341

243

453 154

180

192

188 348

242

299

711

140

223

356

573 314 133

278

187

189

264

821

733

249

145

645

238 212

812

274

732 383

766

1,073

1,481

1,220 1,662

1,062

4,280 3,190

3,585

1,900

1,102

1,920

11,100

226

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

?

EXPLANATION

SPECIFIC CONDUCTANCE IN

MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

Dashed where approximate

250 - 500

> 1,000

< 250

501 - 1,000

383

274

684 WELL LOCATION Open interval includes the lower

Hawthorn Group and the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily

the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily

the Suwannee Limestone and/or the Ocala Limestone and parts of the

Avon Park Formation.

AND SPECIFIC CONDUCTANCE –

WELL LOCATION AND SPECIFIC CONDUCTANCE –

WELL LOCATION AND SPECIFIC CONDUCTANCE –
Assessment of Groundwater Quality 57

somewhere between these trend lines, indicating varying degrees 

of freshwater-seawater mixing and gypsum dissolution.

Hardness is used to describe the resistance of water to 

produce lather from soap. Hardness results from the presence 

of dissolved calcium and magnesium ions, and is expressed in 

terms of equivalent milligrams per liter of calcium carbonate 

(Hem, 1985). Hardness is classified as soft (0–60 mg/L), 

moderately hard (61–120 mg/L), hard (121–180 mg/L), and 

very hard (greater than 180 mg/L) (Hem, 1985). Currently, the 

U.S. Environmental Protection Agency (2009) has not established a recommended limit for hardness. Hard water causes 

scaling, which is the formation of mineral deposits that remain 

after the water evaporates. Scaling can clog pipes and damage 

water heaters. 

Figure 45. Generalized distribution of chloride concentrations in water from the Upper Floridan aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

13

49

68

11

19

13

47

22

13

52

35 13

11

18

19

67

29

29

92

5.4

7.3

4.5

5.6 7.0

6.1

6.6

5.1

6.5

6.3

6.1

9.0

9.0

8.5

108

8.3 8.4

266

301 189

4.4 6.4

119 816 152

8.2

846

101 403

182

419

3,480

1,160

5.5

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

?

EXPLANATION

CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER.

Dashed where approximate

10 - 25

> 250

< 10

26 - 250

Archbold

Biological

Station

29

8.2

68 WELL LOCATION AND CHLORIDE CONCENTRATION Open interval includes the

lower Hawthorn Group and the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily

the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily the

Suwannee Limestone and/or the Ocala Limestone and parts of the Avon Park Formation.

–

–

–

WELL LOCATION AND CHLORIDE CONCENTRATION

WELL LOCATION AND CHLORIDE CONCENTRATION
58 Hydrogeology and Groundwater Quality of Highlands County, Florida

Hardness in water sampled from the Upper Floridan 

aquifer in Highlands County ranged from 64 to 410 mg/L 

(fig. 48, app. 2), with a median value of 130 mg/L (table 4). 

Lowest concentrations (less than 120 mg/L) occurred in the 

recharge area, primarily along or adjacent to the Lake Wales 

Ridge. The highest concentrations (greater than 180 mg/L) 

occurred primarily in the eastern and southwestern parts 

of the county. The principal processes responsible for the 

hardness in water from the Upper Floridan aquifer are the 

dissolution of limestone, dolomite, and gypsum, and the 

mixing of freshwater with relict seawater. The hardness of 

groundwater in the Upper Floridan aquifer generally increases 

with the amount of time water is in contact with calcium or 

magnesium-rich rocks.

Figure 46. Generalized distribution of sulfate concentrations in water from the Upper Floridan aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

10

36

58

23

19

36

96

27

18 41 43

37

14

32

19

14

75 26

220

102

6.9

7.2

9.2

6.0

6.7

9.4

7.8 2.4

482

274 109

4.8

1.7

243

255

131 230

385

7.0 148 713 366

295

204

381

130

140 198

115

0.57

0.20

<0.18

13

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Archbold

Biological Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

?

EXPLANATION

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER

Dashed where approximate

10 - 29

> 250

< 10

30 - 250 26

WELL LOCATION AND SULFATE CONCENTRATION Open interval includes the

lower Hawthorn Group and the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes

primarily the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily the

Suwannee Limestone and/or the Ocala Limestone and parts of the Avon Park Formation.

–

–

–

WELL LOCATION AND SULFATE CONCENTRATION

WELL LOCATION AND SULFATE CONCENTRATION

14

102
Assessment of Groundwater Quality 59

Nitrate Concentration

Unlike the surficial aquifer, nitrate concentrations in 

groundwater from the Upper Floridan aquifer in Highlands 

County generally were very low. Nitrate concentrations in 

water ranged from less than 0.04 to 0.22 mg/L (app. 3), and 

were less than the detection limit in 21 of 22 samples from the 

Upper Floridan aquifer.

Processes that may be responsible for the low nitrate 

concentrations in groundwater in the Upper Floridan aquifer 

underlying Highlands County are denitrification and dilution. 

Where sinkholes are absent, nitrate concentrations typically 

decrease with depth below land surface. Denitrification is the 

primary process likely responsible for the reduction in nitrate 

concentration with depth. Nitrate accumulates in groundwater 

under aerobic conditions (nitrification) and is converted 

to reduced species of nitrogen under anaerobic conditions 

(denitrification). Geochemical factors required for denitrification to occur include: (1) the presence of nitrogen oxides 

as terminal electron acceptors; (2) the presence of bacteria 

capable of reducing nitrate; (3) suitable electron donors, such 

as organic carbon and iron; and (4) anaerobic conditions or 

restricted availability of dissolved oxygen (Tihansky and 

Sacks, 1997).

Low nitrate concentrations in the Upper Floridan aquifer 

can also result from the dilution of high nitrate water from the 

surficial aquifer with low nitrate water naturally present in the 

Upper Floridan aquifer. However, the occurrence of somewhat 

elevated chloride and sulfate concentrations (two indicators 

of agricultural activity) and elevated specific conductance 

above background levels from wells completed in the Upper 

Floridan aquifer indicate that dilution is probably not the 

dominant process responsible for the decrease in nitrate with 

depth. Where sinkholes are present, breaches in the IAS/ICU 

can allow nitrate from the surficial aquifer to directly enter the 

Upper Floridan aquifer, which may explain locally elevated 

nitrate concentrations in groundwater from the aquifer.

Vertical Distribution of Chloride and Sulfate 

Concentrations

Data from deep wells drilled throughout Florida indicate 

that mineralized water underlies the entire State. The depth 

to the mineralized water varies considerably and is controlled 

by the subsurface stratigraphy, land-surface altitude, and 

the altitude of the freshwater head (Franks, 1982). Several 

monitoring wells have been drilled into the middle confining 

units in Highlands and adjacent counties to acquire information 

about variations in water quality within the intermediate aquifer 

system and Upper Floridan aquifer. Profiles of chloride and 

sulfate concentrations of four monitoring wells drilled to nearly 

2,000 ft are illustrated in figure 49. Water samples from these 

wells were either collected through the drill stem as the wells 

were drilled or collected using bailer or packer test methods. 

In general, limited well data indicate that in much of the study 

area, groundwater having chloride and sulfate concentrations of 

less than 100 mg/L extends to considerable depths in the Upper 

Floridan aquifer, and chloride and sulfate concentrations generally increase with depth. Sulfate concentrations increase rapidly 

with depth just above the top of middle confining unit II at 

ROMP 13, 14, and 29A. Chloride concentrations increase in a 

similar manner in ROMP 13 and ROMP 14.

At ROMP 13 (figs. 1 and 49), chloride concentrations 

are less than 100 mg/L in the intermediate aquifer system 

and the upper part of the Upper Floridan aquifer (Baldini and 

Rappuhn, 1998). Chloride concentrations in the intermediate 

aquifer system ranged from about 30 to 90 mg/L. Chloride 

concentrations in much of the Upper Floridan aquifer were 

slightly higher, ranging from about 50 to 100 mg/L between 

699 and 1,579 ft below land surface. Chloride concentrations 

increased rapidly from 107 to 1,981 mg/L between 1,579 ft 

and 1,610 ft below land surface. Chloride concentrations 

further increased from 1,981 to 4,804 mg/L at depths of 

between 1,610 and 2,075 ft below land surface.

Sulfate concentrations in ROMP 13 increased slightly with 

depth in the intermediate aquifer system, ranging from about 2 

to 64 mg/L. In the Upper Floridan aquifer, sulfate concentrations changed little with depth, ranging from 42 to 91 mg/L 

in the interval from 699 and 1,579 ft. Sulfate concentrations 

increased sharply to 745 mg/L at about 1,610 ft and eventually 

leveled off at about 1,700 mg/L. This sharp increase in the 

mineralization of the groundwater, which was also observed at 

ROMP 14 and to a lesser degree at ROMP 28, indicates a less 

Figure 47. Relation between sulfate-chloride equivalent 

ratio and sulfate concentration in water from the Upper 

Floridan aquifer.

Well 68

SEAWATER MIXING TREND

GYPSUM DISSOLUTION LINE

UPPER FLORIDAN

AQUIFER

EXPLANATION

1

10

100

1,000

0.01

0.10

1 10 100 1,000 10,000

SULFATE CONCENTRATION,

IN MILLIGRAMS PER LITER

SULFATE TO CHLORIDE EQUIVALENT RATIO
60 Hydrogeology and Groundwater Quality of Highlands County, Florida

active flow system below the base of the Avon Park permeable 

zone (DeWitt, 1998). In the interval from 1,641 to 2,075 ft, 

sulfate concentrations ranged from 923 to 2,563 mg/L.

Chloride concentrations in water from ROMP 14 

increased gradually with depth between 400 and 1,730 ft 

below land surface, ranging from about 3 to 73 mg/L 

(Clayton, 1998). Chloride concentrations increased sharply 

to 2,180 mg/L from 1,730 to 1,755 ft below land surface. 

From 1,776 ft to the bottom of the hole (1,995 ft below 

land surface), chloride concentrations ranged from 2,313 to 

2,780 mg/L. Sulfate concentrations also increased gradually 

with depth, ranging from 3 to 111 mg/L to a depth of 1,730 ft. 

At about 1,735 ft below land surface, sulfate concentrations 

increased sharply to 1,093 mg/L. In the interval from 1,755 to 

1,995 ft below land surface, concentrations varied from 1,495 

to 2,100 mg/L. 

Figure 48. Generalized distribution of hardness concentrations in water from the Upper Floridan aquifer.

98

98

27

17

70

27

HIGHLANDS

COUNTY

OKEECHOBEE

COUNTY

GLADES

COUNTY

POLK

COUNTY

OSCEOLA

COUNTY

HARDEE

COUNTY

DESOTO

COUNTY

CHARLOTTE

COUNTY

86

70

85

99

77

95

64 88

230

220

166

140

120 130

276

130 220 130

210

220

110

386 220

270 599

410 100

Venus

Kuhlman

Sebring

Brighton

Avon

Park

Lake

Placid

Lorida

Cornwell

Archbold

Biological

Station

27°15’

81°15’

0 5 10MILES

0 5 10KILOMETERS

27°00’

27°30’

81°30’ 81°00’

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

Albers NAD projection 1983

?

EXPLANATION

HARDNESS CONCENTRATION,

IN MILLIGRAMS PER LITER

Dashed where approximate

< 120 120 - 180

> 180

100

210

220

WELL LOCATION AND HARDNESS CONCENTRATION Open interval includes the

lower Hawthorn Group and the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily

the Suwannee Limestone and/or the Ocala Limestone.

Open interval includes primarily

the Suwannee Limestone and/or the Ocala Limestone and parts of the

Avon Park Formation.

–

–

–

WELL LOCATION AND HARDNESS CONCENTRATION

WELL LOCATION AND HARDNESS CONCENTRATION
Assessment of Groundwater Quality 61

Figure 49. Chloride and sulfate concentrations in water samples obtained during drilling of monitoring 

wells. Modified from Peterman and Rappuhn (1997), Clayton (1998), DeWitt (1998), and Mallams and Lee 

(2005). Site numbers refer to figure 1.

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

ROMP 13

DeSoto County

1 10 1,000 10,000

CONCENTRATION, IN

MILLIGRAMS PER LITER

Top of middle confining units II or VI?

Top of Upper

Floridan aquifer

Top of intermediate

aquifer system

1 10 10,000

Top of Upper Floridan aquifer

Top of intermediate aquifer system

Top of middle confining units II or VI?

ROMP 14

Highlands County

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

ROMP 28

Highlands County

ROMP 29A

Highlands County

Top of middle

confining units

II or VI?

Top of Upper

Floridan aquifer

Top of intermediate aquifer system

Top of Upper

Floridan aquifer

intermediate confining unit

DEPTH, IN FEET BELOW LAND SURFACEDEPTH, IN FEET BELOW LAND SURFACE

CONCENTRATION, IN

MILLIGRAMS PER LITER

CONCENTRATION, IN

MILLIGRAMS PER LITER

CONCENTRATION, IN

MILLIGRAMS PER LITER

100

EXPLANATION

Sulfate

Chloride

100 1,000

Top of middle

confining unit II

DEPTH, IN FEET BELOW LAND SURFACEDEPTH, IN FEET BELOW LAND SURFACE

1 10 100 1,000 10,000 1 10 100 1,000 10,000

EXPLANATION

Sulfate

Chloride

EXPLANATION

Sulfate

Chloride

EXPLANATION

Sulfate

Chloride

Top of

Top of Avon Park

permeable zone

Top of Avon Park

permeable zone

Top of Avon Park

permeable zone

Top of Avon Park

permeable zone

Water-quality data collected at ROMP 28 show that 

chloride concentrations changed little during drilling and 

remained below 25 mg/L to the bottom of the hole (2,085 ft 

below land surface). Sulfate concentrations were more variable 

and gradually increased from about 2 to 102 mg/L from 200 

to 1,765 ft below land surface. Concentrations increased more 

rapidly, from 102 to 2,356 mg/L, in the interval from 1,765 to 

2,085 ft below land surface (DeWitt, 1998).

At ROMP 29A, chloride concentrations changed little 

during drilling and generally remained below 25 mg/L to 

a depth of about 1,800 ft below land surface (Mallams and 

Lee, 2005). In the interval from 1,800 ft to the bottom of the 

hole (1,875 ft below land surface), chloride concentrations 

increased slightly from about 10 to 40 mg/L. Sulfate concentrations also varied little with depth, remaining below 30 mg/L 

to a depth of 1,537 ft below land surface. From 1,537 ft 
62 Hydrogeology and Groundwater Quality of Highlands County, Florida

to the bottom of the hole, sulfate concentrations increased 

sharply from about 5 mg/L to a maximum concentration of 

2,320 mg/L. This increase in sulfate concentrations roughly 

corresponds with the top of middle confining unit II, which 

is estimated to be at 1,650 below land surface.

Summary and Conclusions

Highlands County, which encompasses about 1,823 mi2

in the south-central part of the Florida Peninsula, is the 14th

largest county in the State. The county is predominantly rural, 

with most of the population concentrated along the Lake 

Wales Ridge. Continued population growth in Highlands 

County is expected to increase the demand for potable water. 

The population of Highlands County has increased from about 

21,000 in 1960, to 99,000 in 2007, and is projected to reach 

about 120,000 by 2020. In 2007, the county population was 

the 34th largest in the State.

Total groundwater use increased steadily in Highlands 

County from about 37 Mgal/d in 1965 to about 107 Mgal/d 

in 2005. Much of this increase in water use is related to 

agricultural activities, especially citrus cultivation, which 

increased more than 300 percent from 1965 to 2005. 

The principal source of groundwater supply for the county is 

the Upper Floridan aquifer, which provides about 89 percent 

of the groundwater withdrawn. Of the total groundwater 

withdrawn in 2005, about 89 percent was used for agriculture, 8 percent for public supply, 2 percent for recreational 

irrigation, 1 percent for domestic, and less than 0.1 percent 

for both commercial/industrial and thermoelectric power 

generation.

The principal hydrogeologic units underlying the study 

area include the surficial aquifer, the intermediate aquifer 

system/intermediate confining unit (IAS/ICU), and the 

Floridan aquifer system. The surficial aquifer is the uppermost 

water-bearing unit and underlies the entire county. The sediments range from Pliocene to Holocene in age and consist 

mostly of fine-to-medium grained quartz sand with varying 

amounts of clay and silt. The aquifer is unconfined, and 

the base is defined as the first persistent unit of sediments 

containing a substantial increase in clay or silt. The thickness 

of the surficial aquifer is highly variable, ranging from less 

than 50 to more than 300 ft. The water table in the surficial 

aquifer fluctuates about 1 to 5 ft seasonally. The hydraulic 

properties of the surficial aquifer vary considerably across the 

county and depend largely upon aquifer thickness, physical 

characteristics such as grain size and sorting, and types of 

material that compose the aquifer. Groundwater in the surficial 

aquifer is recharged primarily by precipitation, but also by 

septic tanks, irrigation by wells, seepage from lakes and 

streams, and lateral groundwater inflow from adjacent areas. 

About 9 percent of the total groundwater used in Highlands 

County is withdrawn from the surficial aquifer and is used for 

domestic and irrigation purposes.

The IAS/ICU includes all of the rock units that lie 

between the overlying surficial aquifer and the underlying 

Floridan aquifer system. These rock units generally coincide 

with the stratigraphic units designated as the Hawthorn Group, 

although the top of the units can also include the clayey 

sediments of early Pliocene age. Throughout Highlands 

County, the units act as a confining layer (except where 

breached by sinkholes) that restricts the vertical movement of 

water between the surficial aquifer and the underlying Upper 

Floridan aquifer. The sediments have varying degrees of 

permeability and consist of permeable limestone, dolostone, 

or sand, or relatively impermeable layers of clay, clayey sand, 

or clayey carbonates. The altitude of the top of the IAS/ICU 

ranges from more than 50 ft above NGVD 29 in the western 

part of the county to more than 150 ft below NGVD 29 along 

the southern part of the Lake Wales Ridge. The thickness 

of the IAS/ICU ranges from about 200 ft in northwestern 

Highlands County to more than 600 ft in the southwestern part 

of the county.

The intermediate confining unit is present in the eastern 

part of the county, although it is unclear where the confining 

unit grades into an aquifer system. In Highlands County, up 

to two aquifers are present in the intermediate aquifer system. 

The lateral continuity and water-bearing potential of the 

various aquifers within the intermediate aquifer system are 

highly variable due to the heterogeneity of the Hawthorn Group 

sediments. About 2 percent of the total groundwater used in 

Highlands County is withdrawn from the intermediate aquifer 

system and is used for public supply and irrigation purposes.

The Floridan aquifer system is composed of a thick 

sequence of limestone and dolostone of Upper Paleocene to 

Oligocene age. The principal formations of the aquifer system 

are the Suwannee Limestone, Ocala Limestone, Avon Park 

Formation, Oldsmar Formation, and upper part of the Cedar 

Keys Formation. The top of the aquifer system ranges from 

less than 200 ft below NGVD 29 in the extreme northwestern 

part of the county to more than 600 ft below NGVD 29 in the 

southwestern part. The thickness of the aquifer system ranges 

from about 2,800 to 3,400 ft. 

The Floridan aquifer system is divided into two aquifers 

of relatively high permeability, referred to as the Upper 

Floridan aquifer and the Lower Floridan aquifer. These 

aquifers are separated by less-permeable middle confining 

units. The Upper Floridan aquifer is further divided by another 

semiconfining unit into two water-bearing zones within 

the study area―the upper water-bearing zone of the Upper 

Floridan aquifer and the Avon Park permeable zone.

The transmissivity of the Upper Floridan aquifer varies 

throughout the study area. Transmissivity determined from 

aquifer and specific capacity tests in Highlands County range 

from less than 1,000 to about 410,000 ft2/d. Model-derived 

transmissivity values for the Upper Floridan aquifer range 

from about 10,000 to 500,000 ft2/d. Groundwater in the Upper 

Floridan aquifer flows downgradient from potentiometric 

highs to potentiometric lows. West of the Lake Wales Ridge, 

the direction of groundwater flow is southwest, toward the 
Summary and Conclusions 63

Peace River. East of the ridge, the direction of flow is toward 

the Kissimmee River. The potentiometric surface of the Upper 

Floridan aquifer is constantly fluctuating, mainly in response 

to seasonal variations in rainfall and groundwater withdrawals. 

In May 2007, the potentiometric surface ranged from about 

79 ft above NGVD 29 in northwestern Highlands County to 

about 40 ft above NGVD 29 in the southeastern part of the 

county. In September 2007, the potentiometric surface ranged 

from about 85 ft above NGVD in northwestern Highlands 

County to about 43 ft above NGVD 29 in the southeastern 

part of the county. Potentiometric surface altitudes in 

September 2007 were about 3 to 10 ft higher than those 

measured in May 2007.

Groundwater quality was assessed by sampling 58 wells 

and by compiling data collected from 71 additional wells by 

State and County agencies. Inorganic constituents were the 

focus of water-quality analyses.

Water quality in the surficial aquifer can be highly 

variable. This variability results from several factors, 

including the lithology of the sediments, interaction with 

the Upper Floridan aquifer, but most importantly, the effects 

of land use. The water types within the surficial aquifer are 

diverse and include calcium bicarbonate, calcium sulfate, 

sodium chloride, or mixed cation and mixed anion types. 

Concentrations of major ions and specific conductance 

are generally low: specific conductance ranged from 32 to 

723 μS/cm, and none of the samples had concentrations of 

total dissolved-solids, chloride or sulfate that exceeded State 

or Federal drinking-water standards. However, nitrate concentrations in water from the surficial aquifer ranged from 0.004 

to 22 mg/L, and often exceeded the State primary drinkingwater standard of 10 mg/L along the Lake Wales Ridge. Water 

from seven wells along the Lake Wales Ridge had nitrate 

concentrations greater than 10 mg/L. Data obtained from 

the Florida Department of Environmental Protection also 

showed a number of wells along the Lake Wales ridge with 

nitrate concentrations exceeding 10 mg/L. Fertilizers applied 

for citrus farming are the most likely source of nitrate to the 

groundwater in this area.

Water in the intermediate aquifer system was primarily a 

calcium bicarbonate water type. Specific conductance ranged 

from 66 to 11,500 μS/cm, and concentrations of chloride 

and sulfate ranged from 3.8 to 3,770 and 0.12 to 111 mg/L, 

respectively. Nitrate concentrations ranged from 0.004 to less 

than 0.04 mg/L. One well tapping the intermediate aquifer 

system in southern Highlands County had some of the highest 

inorganic constituents reported for any aquifer in the county. 

The source of this highly mineralized water is probably 

relict seawater that entered the aquifer system during the 

Pleistocene. This zone of mineralized water, probably trapped 

in strata of low permeability, has not been removed by the 

modern-day freshwater flow system.

Water in most of the Upper Floridan aquifer in Highlands 

County is typically a calcium magnesium bicarbonate, a 

calcium magnesium sulfate, or a sodium chloride water type. 

Concentrations of chemical constituents vary both areally 

and with depth. Inorganic constituent concentrations generally were below State and Federal drinking-water standards, 

except in the extreme southeastern and southwestern parts of 

the county. Specific conductance in water ranged from 133 

to 1,900 μS/cm. Chloride concentrations ranged from 4.4 to 

403 mg/L, and sulfate concentrations ranged from less than 

0.18 to 255 mg/L. Water from the Upper Floridan aquifer 

in most of the county is hard, ranging from 64 to 410 mg/L. 

Nitrate concentrations in water from the Upper Floridan 

aquifer ranged from less than 0.04 to 0.22 mg/L. Nitrate 

concentrations were less than the detection limit in 21 of 

22 samples from the Upper Floridan aquifer. Lower nitrate 

concentrations in the Upper Floridan aquifer indicate that 

denitrification may be occurring as groundwater moves downward, but lower concentrations also may be due to dilution.

Most of the mineralized water in the Upper Floridan 

aquifer in the southeastern and southwestern parts of 

Highlands County probably is a mixture of freshwater and 

relict seawater that entered the aquifer during a higher stand 

of sea level in the geologic past and has not been completely 

flushed from the aquifer. In addition, the principal source of 

sulfate in water from the Upper Floridan aquifer is dissolved 

sulfur-bearing minerals in the aquifer.

Highlands County appears to have sufficient groundwater resources of good chemical quality for present and 

future needs. The expected continued growth in population 

and agriculture in Highlands County and adjacent counties 

warrants the need for additional information on the quantity 

and quality of groundwater resources in Highlands County. 

Continuing to monitor groundwater levels would provide a 

basis for detecting changes in the potentiometric surface of 

the Upper Floridan aquifer. An expansion of deep monitoring 

wells in eastern and southwestern Highlands County would 

provide water managers a more accurate evaluation about 

the effects of withdrawals on the occurrence and quality of 

the groundwater resources. Additional monitoring wells also 

could be used to characterize the geology, hydrology, and 

water quality of the subsurface. The additional information 

would increase knowledge of the spatial distribution and 

hydraulic relation of the aquifers and their confining units in 

Highlands County.
64 Hydrogeology and Groundwater Quality of Highlands County, Florida

Selected References

Adams, D.B., and Stoker, Y.E., 1985, Hydrology of Lake 

Placid and adjacent area, Highlands County, Florida: U.S. 

Geological Survey Water-Resources Investigations Report 

84–4149, 1 sheet.

Adamski, J.C., and German, E.R., 2004, Hydrology and 

quality of ground water in Orange County, Florida: U.S. 

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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.
70 Hydrogeology and Groundwater Quality of Highlands County, Florida

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, 

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U.S. Bureau of Census, 1995, Accessed at www.agcensus.

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chaps. A1–A9, 2 v., variously paged. (Also available at 

http://water.usgs.gov/owq/FieldManual/ )

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Florida Potential and Reference Evapotranspiration 1995–

2008. Accessed at http://hdwp.er.usgs.gov/

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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.

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and Carlson, J.I., 2003, Sequence-stratigraphic analysis of 

the Regional Observation Monitoring Program (ROMP) 

29A test corehole and its relation to carbonate porosity and 

regional transmissivity in the Floridan Aquifer System, 

Highlands County, Florida: U.S. Geological Survey OpenFile Report 03–201, 34 p., plus apps. 

Wheaton, T.A., and Graham, Wendy, 2000, Spatial and temporal distribution of groundwater nitrate in relation to citrus 

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Peninsula: Florida Bureau of Geology Bulletin 51, 164 p.

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Generalized configuration of the bottom of the Floridan 

aquifer, Southwest Florida Water Management District: 

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Open-File Report 79–1490, 1 sheet.

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west-central Florida, 1952–76: U.S. Geological Survey 

Water-Resources Investigations Report 84–4044, 127 p.

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flow in Lake Wales Ridge and adjacent areas of central Florida: U.S. Geological Survey Water-Resources Investigations 

Report 94–4254, 82 p.

Illustrator, Ronald S. Spencer

Design and layout, Twila Darden Wilson
 

 Appendixes
72    Hydrogeology and Groundwater Quality of Highlands County, Florida

Appendix 1. Inventory of wells used in this study.

[Well locations shown in figure 11. Hydrogeologic unit: SA, surficial aquifer; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Primary data type: QW, waterquality sample; WL, groundwater level. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management 

District; SWFWMD, Southwest Florida Water Management District; USGS, U.S. Geological Survey; —, no data]

Well No. USGS site ID No. Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Bottom of casing

(feet below

land surface)

Well depth

(feet below

land surface)

Hydrogeologic

unit County Primary datatype Source of data

1 270157081203101 H-15A 270158 812032 19 23 SA Highlands WL USGS, SWFWMD

2 270208081341201 VC Hollingsworth #8 270209 813413 673 1,100 UFA DeSoto QW SWFWMD

3 270242081335701 4 N 1 Groves P-4 (DID #4) 270242 813357 601 1,225 UFA DeSoto QW SWFWMD

4 270302081255501 270302081255501 270302 812555 25 35 SA Highlands QW FDEP, SFWMD

5 270313081391001 Emerald Island (DID #5) 270331 813925 610 1,300 UFA DeSoto QW SWFWMD

6 270344081241601 Sherley Deep 270344 812416 650 1,500 UFA Highlands QW USGS

7 270348081261201 270348081261201 270320 812611 20 30 SA Highlands QW FDEP, SFWMD

8 270348081312101 Southern Farms 270348 813121 700 1,400 UFA Highlands QW USGS

9 270415081243401 Sherley Shallow 270415 812434 45 55 SA Highlands QW USGS

10 270418081365801 ROMP 13 Avon Park 270419 813659 1,550 1,600 UFA DeSoto WL, QW SWFWMD

11 270418081365802 ROMP 13 Suwannee (MW-4) 270419 813658 671 786 UFA DeSoto QW, WL SWFWMD, USGS

12 270418081365803 ROMP 13 Lower Arcadia 270419 813658 510 592 IAS DeSoto WL, QW SWFWMD, USGS

13 270418081365804 ROMP 13 Upper Arcadian 270419 813658 282 417 IAS DeSoto QW, WL SWFWMD, USGS

14 270418081365805 ROMP 13 Surficial 270419 813659 7.5 24 SA DeSoto QW, WL SWFWMD, USGS

15 270437081231601 270437081231601 270439 812315 40 45 SA Highlands QW FDEP, SFWMD

16 — BREX-1 270441 810706 640 1,216 UFA Glades QW Consult

17 270531081354401 Sunpure LTD #304 (DID #4) 270531 813545 638 1,308 UFA DeSoto QW SWFWMD

18 270540081335101 Nafco Groves 270540 813349 100 300 IAS DeSoto QW SWFWMD

19 270556081204701 HIF-26 Hendrie Dairy 270556 812047 — 1,610 UFA Highlands WL USGS

20 270627081313101 HIF-23 Graham Dairy 270627 813131 — 1,560 UFA Highlands WL USGS

21 270717081185701 Gould Road Surficial 270714 811903 22 32 SA Highlands QW SWFWMD

22 270743081115401 Center South 270743 811154 360 500 IAS Highlands QW USGS

23 270835081194201 Hickory Branch Road Surficial 270835 811942 80 90 SA Highlands QW SWFWMD

24 270858081211101 ROMP 14 AVPK 270859 812114 1,003 1,670 UFA Highlands WL, QW SWFWMD, USGS

25 270858081211102 ROMP 14 Low Htrn 270859 812112 460 521 IAS Highlands QW, WL SWFWMD

26 270858081211103 ROMP 14 Surficial 270859 812112 30 300 SA Highlands QW, WL SWFWMD, USGS

27 270858081211104 ROMP 14 Suwannee 270859 812112 650 730 UFA Highlands QW, WL SWFWMD, USGS

28 270952081183101 Womble Road Surficial 270953 811855 40 50 SA Highlands QW SWFWMD

29 — Perry Brothers (well 225) 271029 812936 680 990 UFA Highlands QW SWFWMD

30 271052081121901 Lower Tropical East 271052 811219 40 45 SA Highlands QW USGS

31 271114081122401 Tropical East 271114 811224 100 110 IAS Highlands QW USGS

32 271132081371801 Bright Hour Ranch 271132 813718 — 1,485 UFA DeSoto QW SWFWMD

33 271134081234301 HIF-05 Stidham 271134 812343 602 1,510 UFA Highlands WL USGS

34 271147080573601 Stratton-Slough Pasture 271147 805736 — — UFA Glades QW USGS

35 271147080580801 Stratton-100 acre 271147 805808 — — UFA Glades QW USGS

36 271148081194201 Rozier Road Surficial 271148 811942 40 50 SA Highlands QW SWFWMD

37 271150081054401 GL-155 271150 810544 — 600 UFA Glades WL USGS
Appendix 1    73

Well No. USGS site ID No. Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Bottom of casing

(feet below

land surface)

Well depth

(feet below

land surface)

Hydrogeologic

unit County Primary datatype Source of data

38 271207081122901 Sun Ray A2 271207 811229 525 1,530 UFA Highlands QW USGS

39 271214080572601 Stratton-Coon Hammock 271214 805726 — — UFA Glades QW USGS

40 271217081192501 Sunshine 1,200 ft 271217 811925 615 1,200 UFA Highlands QW USGS

41 271223081202601 Lake Placid Groves 12” UFA 271223 812026 900 1,200 UFA Highlands QW, WL USGS

42 271225081192201 Sunshine 271225 811922 200 400? SA Highlands QW USGS

43 271226081194301 Bairs Den Well 271223 811942 28 35 SA Highlands QW, WL FDEP, SWFWMD

44 271232081392201 ROMP 15 10” UFA 271232 813922 577 1,360 UFA DeSoto QW, WL SWFWMD, USGS

45 271232081392202 ROMP 15 SAS 271232 813922 45 55 SA DeSoto WL SWFWMD, USGS

46 271232081392203 ROMP 15 Arcadia well 271232 813922 260 330 IAS DeSoto WL SWFWMD, USGS

47 — HIF-42 Paradise Run Upper 271305 805715 560 1,050 UFA Highlands QW Consult

48 271306081284801 HIF-08 Box Ranch 271306 812848 — 1,450 UFA Highlands WL USGS

49 271310081175501 Rothman 271310 811755 180 200 IAS Highlands QW USGS

50 271313081194401 SR 70 Surficial 271313 811944 25 35 SA Highlands QW SWFWMD

51 271315081250601 Westby Shallow 271315 812506 — 120 IAS Highlands QW USGS

52 271321081040401 C41A-So 271321 810404 — 43 SA Highlands QW FDEP, SFWMD

53 271330081113401 HIF-37 Sun Ray Farms 271330 811134 619 1,450 UFA Highlands QW, WL USGS

54 271340080504001 OKF-31 271340 805040 — 1,079 UFA Okeechobee QW, WL USGS

55 271359081024301 Coco Sod Farm #3 271359 810243 — — UFA Highlands QW USGS

56 271403081022401 Coco Sod Farm #2 271403 810224 — — UFA Highlands QW USGS

57 271409081014901 Coco Sod Farm #1 271409 810149 — — UFA Highlands QW USGS

58 271412080591901 Kissimmee River FR 271412 805919 110 — IAS Highlands QW USGS

59 271430081003201 HIG2-01 271430 810032 60 70 SA Highlands QW FDEP, SFWMD

60 271456081073901 C41A-No 271456 810739 — 36 SA Highlands QW FDEP, SFWMD

61 271456081074701 HIF-06, 4-in 271456 810747 310 520 UFA, IAS Highlands QW, WL USGS

62 271514080511601 OKF-23 Okeechobee 271514 805116 — 925 UFA Okeechobee QW, WL USGS

63 271522081285301 Carlton Ranch 271522 812853 550 1,450 UFA Highlands QW USGS

64 271529081210701 Old State Road 8 Surficial 271529 812107 50 60 SA Highlands QW SWFWMD

65 271559081202301 ROMP 28X Deep 271559 812023 585 1,385 UFA Highlands QW, WL SWFWMD, USGS

66 271559081202302 ROMP 28X Surficial 271600 812022 50 60 SA Highlands QW, WL SWFWMD, FDEP

67 271559081242501 Lake Groves Road 271602 812427 13 23 SA Highlands WL SWFWMD

68 271614081240901 Placid Lakes #2 271614 812409 596 1,340 UFA Highlands QW USGS

69 271618081120701 HIH-1 271618 811207 320 360 IAS Highlands QW USGS

70 271618081120801 HIF-40 271618 811208 460 540 UFA Highlands QW USGS

71 — Larson Dairy Barn #2 271645 810128 — 16 SA Highlands QW FDEP, SFWMD

72 271707081341801 Rutland Ranch #1 (DID #1) 271708 813418 550 1,500 UFA DeSoto QW SWFWMD

73 271726081163901 HIF-14 P G Phypers 271726 811639 — 1,500 UFA Highlands QW, WL USGS

74 271728081254301 Westby Deep 271728 812543 600 1,200 UFA Highlands QW USGS

Appendix 1. Inventory of wells used in this study.—Continued

[Well locations shown in figure 11. Hydrogeologic unit: SA, surficial aquifer; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Primary data type: QW, waterquality sample; WL, groundwater level. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management 

District; SWFWMD, Southwest Florida Water Management District; USGS, U.S. Geological Survey; —, no data]
74    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well No. USGS site ID No. Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Bottom of casing

(feet below

land surface)

Well depth

(feet below

land surface)

Hydrogeologic

unit County Primary datatype Source of data

75 271743081374601 Tropical River Grove 271745 813745 137 698 UFA, IAS DeSoto QW, WL SWFWMD, USGS

76 — RIDGE WRAP H-8 Surficial 271748 811906 45 65 SA Highlands WL SWFWMD

77 271748081345101 Trg J36 12” UFA 271748 813451 352 1,360 UFA DeSoto WL USGS

78 271753081224201 Jackson Road 2 Surficial 271752 812244 33 43 SA Highlands QW SWFWMD

79 271828081185501 Windy Point Park 271828 811855 470 600 UFA Highlands QW USGS

80 271918081211001 Tropical Harbor 271918 812110 510 1,284 UFA Highlands QW USGS

81 271947081213501 Walker Road Surficial 271945 812135 23 33 SA Highlands QW SWFWMD

82 — RIDGE WRAP H-7 Surficial 272029 812757 20 40 SA Highlands WL SWFWMD

83 272104081023901 Hidden Acres Estates 272104 810239 190 267 IAS Highlands QW USGS

84 272115081134901 Mossy Cove FC 272115 811349 — — IAS Highlands QW USGS

85 272154081354901 Bentley Grove 28 (DID #28) 272154 813549 475 1,494 UFA Hardee QW SWFWMD

86 272158081232101 Dinner Lake Rd Surficial 272158 812321 20 30 SA Highlands QW SWFWMD

87 272207081260401 ROMP 28 AP 272208 812607 960 1,642 UFA Highlands WL SWFWMD, USGS

88 272207081260402 ROMP 28 Intermediate 272208 812607 370 420 IAS Highlands QW, WL SWFWMD

89 272207081260404 ROMP 28 Suwannee 272208 812607 485 600 UFA Highlands QW, WL SWFWMD

90 272207081260405 ROMP 28 L Avon Park 272208 812607 1,913 1,933 UFA Highlands WL, QW SWFWMD

91 272207081260406 ROMP 28 Evaporite 272208 812607 2,083 2,112 UFA Highlands WL, QW SWFWMD

92 272207081260407 ROMP 28 Up. Avon Park 272208 812607 973 1,650 UFA Highlands WL, QW SWFWMD

93 272207081260408 ROMP 28 Surficial 272208 812607 40 200 SA Highlands QW, WL SWFWMD

94 272314081135701 Trails End FR 272314 811357 135 155 IAS Highlands QW USGS

95 — Latt Maxcy Corp (well 224) 272317 812413 253 1,494 UFA, IAS Highlands QW SWFWMD

96 272341081070401 SFWMD Cornwell Marsh W. 272341 810704 — — IAS? Highlands QW USGS

97 272403081065801 OKF-42 SFWMD, S65C 272403 810634 372 1,152 UFA Okeechobee QW, WL USGS

98 — OKF-105 272407 810651 370 1,400 UFA Okeechobee QW USGS, SFWMD

99 — Yonce 272422 812322 100 125 SA Highlands QW SWFWMD

100 — Ben Griffin (well 227) 272448 812403 740 1,384 UFA Highlands QW SWFWMD

101 272459081240401 17th St. South Surficial 272459 812404 70 80 SA Highlands QW SWFWMD

102 272500081232301 272500081232301 272500 812323 247 510 IAS Highlands QW FDEP, SFWMD

103 272504081120101 H-11A Surficial 272505 811200 — 7 SA Highlands WL USGS

104 272510081235001 Desoto Tower well 272514 812400 500 — UFA Highlands QW FDEP, SWFWMD

105 272512081122901 HIF-13 Metzger 272512 811229 — 1,106 UFA Highlands WL USGS

106 272538081350801 Crewsville Sh-AGW 272545 813523 6 26 SA Hardee QW SWFWMD

107 272538081350802 Crewsville UP INT-AG 272545 813523 96 116 IAS Hardee QW SWFWMD

108 272614081153201 Palm Estates 272614 811532 258 480 IAS/UFA Highlands QW USGS

109 272625081185301 Spring Lake 1,000 ft 272625 811853 350 1,000 UFA Highlands QW USGS

110 — RIDGE WRAP H-4 Surficial 272634 812860 30 50 SA Highlands WL SWFWMD

111 272638081171301 Lake Istokpoga Park 272638 811713 — 60 SA Highlands QW USGS

Appendix 1. Inventory of wells used in this study.—Continued

[Well locations shown in figure 11. Hydrogeologic unit: SA, surficial aquifer; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Primary data type: QW, waterquality sample; WL, groundwater level. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management 

District; SWFWMD, Southwest Florida Water Management District; USGS, U.S. Geological Survey; —, no data]
Appendix 1    75 

Well No. USGS site ID No. Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Bottom of casing

(feet below

land surface)

Well depth

(feet below

land surface)

Hydrogeologic

unit County Primary datatype Source of data

112 272652081103101 HIF-43 Hickory Hammock 272652 811031 405 835 UFA Highlands QW USGS

113 272702081311201 Country Club #1 272702 813112 450 1,180 UFA Highlands QW USGS

114 272704081053501 OKF-56 Micco Road 272704 810535 — — UFA Okeechobee WL USGS

115 — MR-0158 272713 812045 — 10 SA Highlands QW FDEP, SFWMD

116 272702081383001 Johnson-HRS 272719 813831 58 70 IAS Hardee QW SWFWMD

117 272731081211601 Sebring Airport #2 272731 812116 380 1,060 UFA Highlands QW USGS

118 — KRBFFM 272738 811021 — 38 SA Highlands QW SFWMD 

119 272745081232601 Sebring 412 surf (replacement) 272748 812326 40 66 SA Highlands QW, WL SWFWMD, FDEP

120 272746081232701 Sebring well 412 (destroyed) 272746 812327 41 45 SA Highlands WL SWFWMD

121 — KRAFFM 272753 810952 — 34 SA Highlands QW SFWMD 

122 272801081242301 Paradise Drive Surficial 272801 812414 22 32 SA Highlands QW SWFWMD

123 272811081315501 Highlands Hammock 230 ft 272811 813155 — 230 IAS Highlands QW USGS

124 272825081135901 Donley-Myers #4 272825 811359 452 1,642 UFA/LFA? Highlands QW USGS

125 272826081142201 Donley-Myers #1 272826 811422 451 1,642 UFA/LFA? Highlands QW USGS

126 272835081251701 Maranatha Village 6” UFA 273135 812517 — 841 UFA Highlands QW USGS

127 272842081315501 Highlands Hammock Park 272841 813153 — 260 IAS Highlands QW FDEP, SWFWMD

128 272855081400701 Peace River Ranch 10” UFA 272855 814007 141 1,160 UFA Hardee WL USGS

129 272902081115101 KRDFFM 272902 811151 — 46 SA Highlands QW, WL SFWMD 

130 272906081142001 HIF-04 Yucan Ranch 272906 811420 — 1,300 UFA Highlands WL USGS

131 272945081142001 Donley-Myers #3 272945 811420 470 1,642 UFA/LFA? Highlands QW USGS

132 — Highlands Co. Landfill 7207 273005 812540 — 25 SA Highlands QW FDEP

133 — ROMP 29A shallow 273010 812511 34 203 SA Highlands QW, WL SWFWMD

134 273009081251001 ROMP 29A Intermediate 273010 812510 310 414 IAS Highlands QW, WL SWFWMD

135 273010081251301 ROMP 29A UFA 273010 812511 478 1,640 UFA Highlands QW, WL SWFWMD

136 — Highlands Co. Landfill MW-1 Sh 273053 811913 — 17.5 SA Highlands QW HC

137 273055081185901 Highlands County Landfill 273055 811859 300 1,000 UFA Highlands QW USGS

138 273103081363701 Smith Deep 273104 813636 66 849 UFA/IAS Hardee QW, WL SWFWMD

139 273122081271201 Arbuckle Creek Rd Surficial 273122 812713 40 50 SA Highlands QW SWFWMD

140 273125081264601 Dees Dinner Lake 273125 812646 — — IAS? Highlands QW USGS

141 273138081154201 HIF-03 Howerton 273138 811542 — 1,280 UFA Highlands WL USGS

142 273212081311401 Sun and Lakes 273212 813114 190 1,220 UFA Highlands QW USGS

143 273217081012601 OKF-34 273217 810126 — 1,143 UFA Okeechobee WL USGS

144 273249081164201 AP Air Force Range SS5 273249 811642 30 48 SA Highlands -- SFWMD

145 273249081164202 AP Air Force Range SI4 273249 811642 180 193 IAS Highlands QW USGS

146 273249081164203 AP Air Force Range SF3 273249 811642 320 906 UFA Highlands QW USGS

147 273249081164204 AP Air Force Range S2 273249 811642 1,010 1,183 UFA Highlands -- SFWMD

148 273252081264101 Bonnet Lake 6” UFA 273252 812641 462 1,029 UFA Highlands QW, WL USGS

Appendix 1. Inventory of wells used in this study.—Continued

[Well locations shown in figure 11. Hydrogeologic unit: SA, surficial aquifer; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Primary data type: QW, waterquality sample; WL, groundwater level. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management 

District; SWFWMD, Southwest Florida Water Management District; USGS, U.S. Geological Survey; —, no data]
76    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well No. USGS site ID No. Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Bottom of casing

(feet below

land surface)

Well depth

(feet below

land surface)

Hydrogeologic

unit County Primary datatype Source of data

149 273333081264301 Altvater Road Surf 273333 812638 9 19 SA Highlands QW SWFWMD

150 273450081170201 AP Air Force Range MW10 273450 811702 2 12 SA Highlands QW USGS

151 — ROMP 43 MW1 Surficial 273500 813519 2 12 SA Hardee WL, QW SWFWMD

152 — ROMP 43 MW2 Up Arcadia 273500 813519 52 116 IAS Hardee WL, QW SWFWMD

153 — ROMP 43 MW3 Low Arcadia 273500 813519 196 233 IAS Hardee QW, WL SWFWMD

154 — ROMP 43 MW4 Suwannee 273500 813519 306 464 UFA Hardee QW, WL SWFWMD

155 — ROMP 43 MW5 Avon Park 273500 813519 720 1,210 UFA Hardee WL, QW SWFWMD

156 273517081282801 Sears Rd Surficial 273517 812828 25 35 SA Highlands QW SWFWMD

157 273520081253201 273520081253201 273528 812525 170 190 SA Highlands QW FDEP, SFWMD

158 273525081352101 Thomas Watkins 273526 813522 450 1,200 UFA Hardee QW SWFWMD

159 273528081260901 Lotela_G (MR-0156) 273529 812607 — 10 SA Highlands WL SFWMD, FDEP

160 273603081270501 Wabasso (Dressler) Dairy D 273603 812705 200 350 IAS Highlands WL USGS

161 — RIDGE WRAP H-2 Surficial 273611 813143 65 85 SA Highlands WL SWFWMD

162 — LC Dairy 273612 812720 — 20 SA Highlands QW FDEP, SFWMD

163 273615081284901 ROMP 43XX 8”UFA 273616 812848 409 1,363 UFA Highlands QW, WL SWFWMD, USGS

164 273615081284902 ROMP 43XX Surficial 273616 812848 32 83 SA Highlands WL SWFWMD

165 273656081210901 AP Air Force Range MW4 273656 812109 2 12 SA Highlands QW USGS

166 273704081245501 Richards 273704 812456 140 260 IAS Highlands QW, WL USGS

167 273705081290901 CR 627 Surficial 273705 812909 50 60 SA Highlands QW SWFWMD

168 273754081290401 Alpine Road Surficial 273755 812904 66 76 SA Highlands QW SWFWMD

169 273755081253401 HRWRAP H-10 273756 812535 30 50 SA Highlands WL SWFWMD

170 — RIDGE WRAP H-1 Surficial 273816 813125 40 60 SA Highlands WL SWFWMD

171 273845081321901 Clenny UFA 273845 813219 227 1,050 UFA Highlands WL USGS

172 273903081185201 Avon Park Prison #1 (POF-9) 273911 812108 — 1,035 UFA Polk WL,QW USGS

173 — POS-3 273933 810758 75 90 SA Polk QW, WL SFWMD

174 — POH-1 273933 810759 180 200 IAS Polk QW, WL SFWMD

175 273929081080601 S-65A (POF-20R; 397 ft) 273933 810759 287 397 UFA Polk QW, WL USGS, SFWMD

Appendix 1. Inventory of wells used in this study.—Continued

[Well locations shown in figure 11. Hydrogeologic unit: SA, surficial aquifer; IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Primary data type: QW, waterquality sample; WL, groundwater level. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management 

District; SWFWMD, Southwest Florida Water Management District; USGS, U.S. Geological Survey; —, no data]
Appendix 2    77

Appendix 2. Summary of major inorganic constituents and physical characteristics in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County 

and parts of adjacent counties.

[Well locations shown in figure 11. U.S. Geological Survey (USGS) site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for water 

temperature, in degrees Celsius; specific conductance, in microsiemens per centimeter; and pH, in standard units. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water 

Management District; SWFWMD, Southwest Florida Water Management District; —, not analyzed; <, less than the value, E, estimated value]

Well

No.

Hydrogeologic

unit

Source of data Sampling

date Calcium Magnesium Potassium Sodium Chloride Fluoride Sulfate Silica

Water

temperature

Specific

conductance

Total

dissolved

solids

pH

Hardness

as

CaCO3

Alkalinity

as

CaCO3

2 UFA SWFWMD 10/01/04 17 12 4.3 113 92 — 115 13 28.8 766 437 8.3 — —

3 UFA SWFWMD 02/13/03 76 48 5.6 203 419 — 198 15 28.3 1,920 1,079 7.7 — —

4 SA FDEP, SFWMD 04/17/01 0.27 0.58 0.29 6.0 11 0.02 — 0.29 25.1 60 15 4.4 — 0.5

5 UFA SWFWMD 05/25/07 70 33 3.5 93 182 — 140 19 28.6 1,102 684 7.4 — 130

6 UFA USGS 11/07/07 17 13 3.2 39 29 3.6 26 14 26.0 383 227 8.2 100 112

7 SA FDEP, SFWMD 04/17/01 0.63 0.92 0.17 3.2 7.2 — 0.20 — 25.9 46 18 4.5 — 1.7

8 UFA USGS 12/05/07 71 57 9.3 208 403 1.4 130 35 24.6 1,900 1,050 7.6 410 180

9 SA USGS 11/07/07 2.5 1.7 1.2 3.9 10 <0.12 2.1 12 24.7 66 38 5.0 13 8

11 UFA SWFWMD 09/07/07 41 23 2.7 57 101 0.48 75 17 26.9 732 — 7.5 — 118

13 IAS SWFWMD 09/07/07 33 32 6.4 37 30 2.2 13 53 25.6 589 — 7.2 — 243

14 SA SWFWMD 09/07/07 6.1 1.5 2.5 7.0 11 — 7.0 8.0 26.3 97 75 5.1 — 18

15 SA FDEP, SFWMD 04/17/01 4.2 6.0 0.47 17 54 0.06 3.9 — 24.1 210 89 4.6 — 2.1

16 UFA Consult 06/27/07 164 74 — 364 655 — 376 — — 2,720 1,750 — 696 86

17 UFA SWFWMD 03/13/03 155 93 10 484 846 — 381 17 29.9 3,585 2,044 7.5 — —

18 IAS SWFWMD 09/10/07 112 30 4.3 89 272 0.72 13 48 26.0 1,280 — 7.0 — 226

21 SA SWFWMD 11/08/07 15 7.8 13 12 30 0.08 44 7.7 26.9 320 — 4.2 — —

22 IAS USGS 09/25/07 160 186 37 1,940 3,770 1.9 111 11 25.0 11,500 6,810 7.5 1,200 77

23 SA SWFWMD 11/08/07 20 12 10 14 38 0.06 51 4.0 25.9 331 — 4.9 — 2.9

25 IAS SWFWMD 06/21/07 16 12 4.3 11 5.4 0.87 2.8 19 25.2 222 — 8.7 — 108

26 SA SWFWMD 06/30/05 2.4 0.58 0.21 3.2 6.0 <0.02 2.0 3.3 24.8 41 — 5.0 — 3.7

27 UFA SWFWMD 06/21/07 4.4 4.3 3.9 48 8.2 2.5 14 11 25.7 274 — 8.7 — 117

28 SA SWFWMD 08/16/07 23 9.3 14 19 52 <0.02 51 7.1 26.1 384 — 4.6 — 1.8

29 UFA SWFWMD 09/06/00 — — 2.7 22 7.3 — 9.2 16 — 243 138 — 86 94

30 SA USGS 09/25/07 11 2.4 0.80 14 30 0.10 2.8 10 24.6 175 107 5.4 37 23

31 IAS USGS 09/25/07 — — — — 13 — <0.18 — 24.4 543 — 6.9 — —

32 UFA SWFWMD 10/27/01 — — — — 152 — 204 — — — — — — —

34 UFA USGS 03/19/08 105 76 12 392 816 0.52 295 13 27.8 3,190 1,820 7.6 599 83

35 UFA USGS 03/19/08 — — — — 1,160 — 366 — 28.6 4,280 — 7.7 — —

36 SA SWFWMD 08/15/07 19 1.0 2.0 1.2 4.2 <0.02 29 6.8 27.4 137 — 5.5 — 9.9

38 UFA USGS 11/07/07 59 25 1.6 49 119 0.20 148 11 27.4 812 474 7.8 270 63

39 UFA USGS 03/19/08 — — — — 3,480 — 713 — 29.6 11,100 — 7.4 — —

40 UFA USGS 12/05/07 15 10 2.0 7.8 6.4 0.63 19 13 — 212 127 — 88 —

41 UFA USGS 09/26/07 15 5.7 2.1 25 4.4 3.3 7.0 10 24.4 238 141 7.9 64 —

42 SA USGS 12/05/07 0.47 0.63 0.85 2.7 4.8 <0.12 2.0 12 24.3 32 26 4.9 4 0.50
78    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well

No.

Hydrogeologic

unit

Source of data Sampling

date Calcium Magnesium Potassium Sodium Chloride Fluoride Sulfate Silica

Water

temperature

Specific

conductance

Total

dissolved

solids

pH

Hardness

as

CaCO3

Alkalinity

as

CaCO3

43 SA FDEP, SWFWMD 04/30/01 21 0.71 1.6 1.1 10 0.02 16 — 29.5 150 84 6.6 — 130

44 UFA SWFWMD 11/15/07 106 61 3.7 22 29 1.0 385 23 28.7 1,062 — 7.3 — 112

47 UFA Consult — — 1.7

49 IAS USGS 12/05/07 5.5 0.87 2.8 3.9 3.8 0.22 1.3 30 23.8 66 58 6.4 17 180

50 SA SWFWMD 11/06/07 37 1.6 9.7 2.1 2.9 0.04 17 4.0 27.5 234 — 6.9 — 8.0

51 IAS USGS 03/18/08 46 22 2.0 23 7.9 0.21 0.20 43 24.9 468 287 7.5 210 118

52 SA FDEP, SFWMD 04/18/01 76 9.2 2.0 58 48 0.36 30 — 24.5 723 443 7.1 — 243

53 UFA USGS 09/25/07 47 21 1.5 32 67 0.28 131 11 27.4 645 390 7.8 220 18

55 UFA USGS 06/12/08 — — — — 189 — 230 — 27.7 1,220 — 7.8 — 2.1

56 UFA USGS 06/12/08 — — — — 301 — 255 — 28.4 1,662 — 7.7 — 86

57 UFA USGS 06/12/08 69 46 5.7 139 266 0.53 243 13 27.7 1,481 905 7.8 386 —

58 IAS USGS 11/06/07 94 7.9 1.9 43 38 0.31 3.0 29 25.1 672 339 7.3 270 226

59 SA FDEP, SFWMD 04/06/00 90 11 1.5 40 51 0.25 0.20 — 24.2 685 424 7.1 — —

60 SA FDEP, SFWMD 04/18/01 69 8.3 2.7 22 29 0.17 36 — 23.9 516 389 7.0 — 77

61 UFA, IAS USGS 09/25/07 43 23 4.3 51 68 0.60 102 24 24.7 684 424 7.6 210 2.9

62 UFA USGS 09/25/07 64 44 6.6 169 295 0.65 202 17 26.1 1,550 909 7.7 358 108

63 UFA USGS 03/18/08 53 19 1.6 14 19 0.27 58 20 28.4 498 314 7.5 220 3.7

64 SA SWFWMD 11/06/07 35 13 23 3.1 22 0.55 69 7.7 27.2 418 — 4.8 — 117

65 UFA SWFWMD 08/24/00 — — — — 8.4 — 1.7 — 24.6 145 — 8.4 — 1.8

66 SA SWFWMD 04/27/00 7.4 0.85 0.24 6.6 12 0.11 0.20 — 25.8 91 56 5.6 — 94

68 UFA USGS 12/05/07 29 9.0 0.84 6.1 8.3 0.17 4.8 17 25.6 249 158 7.8 110 23

69 IAS USGS 01/24/08 24 21 3.9 34 45 1.2 18 25 23.2 459 275 8.3 160 —

70 UFA USGS 01/24/08 46 22 3.5 62 108 0.42 109 12 22.4 733 437 8.2 220 —

71 SA FDEP, SFWMD 04/06/00 4.9 3.5 0.57 21 51 0.17 0.87 — 21.5 214 153 5.3 — 83

72 UFA SWFWMD 03/09/04 91 41 2.3 14 19 — 274 18 — 821 616 7.6 — —

73 UFA USGS 09/25/07 22 8.1 0.84 9.5 18 0.16 32 10 25.0 264 146 8.2 95 9.9

74 UFA USGS 03/18/08 64 17 1.7 9.1 11 0.20 36 23 27.4 479 298 7.2 230 63

75 UFA, IAS SWFWMD 11/14/07 87 41 3.1 41 49 1.0 220 30 26.2 936 — 7.2 — —

78 SA SWFWMD 11/05/07 38 6.1 12 2.3 16 0.09 30 2.0 26.8 313 — 6.3 — —

79 UFA USGS 01/17/08 — — — — 8.5 — <0.18 — 24.0 189 141 8.2 — —

80 UFA USGS 12/04/07 19 5.9 0.63 5.3 9.0 0.14 14 9.7 25.2 187 117 8.3 77 0.5

81 SA SWFWMD 08/13/07 29 1.7 5.7 2.2 7.8 <0.02 45 2.3 26.2 216 — 4.9 — 130

83 IAS USGS 11/06/07 93 8.1 1.3 46 43 0.29 0.72 25 23.9 678 373 7.2 270 112

84 IAS USGS 01/16/08 — — — — 63 — 1.2 — 23.9 655 398 7.5 — 1.7

Appendix 2. Summary of major inorganic constituents and physical characteristics in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County 

and parts of adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey (USGS) site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for water 

temperature, in degrees Celsius; specific conductance, in microsiemens per centimeter; and pH, in standard units. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water 

Management District; SWFWMD, Southwest Florida Water Management District; —, not analyzed; <, less than the value, E, estimated value]
Appendix 2    79

Well

No.

Hydrogeologic

unit

Source of data Sampling

date Calcium Magnesium Potassium Sodium Chloride Fluoride Sulfate Silica

Water

temperature

Specific

conductance

Total

dissolved

solids

pH

Hardness

as

CaCO3

Alkalinity

as

CaCO3

85 UFA SWFWMD 04/15/02 128 62 2.5 8.9 11 — 482 16 — 1,073 848 7.6 — 180

86 SA SWFWMD 10/31/07 43 5.3 8.0 3.9 8.5 0.05 40 4.5 27.2 314 — 6.3 — 8.0

88 IAS SWFWMD 03/16/04 24 22 4.4 15 13 0.50 4.8 31 24.1 343 — 8.0 — —

89 UFA SWFWMD 03/16/04 35 10 4.1 9.4 9.0 0.19 37 18 24.5 278 — 9.6 — —

93 SA SWFWMD 06/29/05 5.2 0.44 0.87 1.7 2.6 1.2 1.8 8.7 25.9 51 — 5.5 — 161

94 IAS USGS 11/07/07 54 17 2.6 23 43 0.55 E.12 47 22.4 501 316 7.7 210 186

95 UFA, IAS SWFWMD 01/09/02 30 17 2.5 15 13 — 10 31 — 391 243 — — 161

96 IAS? USGS 03/19/08 — — — — 54 0.44 22 — 23.4 783 — 7.2 — —

97 UFA USGS 01/24/08 36 40 5.1 41 52 0.60 96 26 24.0 711 444 7.6 276 199

99 SA SWFWMD 04/12/00 — — 1.5 8.5 11 — 39 20 — 335 233 — 159 120

100 UFA SWFWMD 12/06/01 38 16 1.8 12 13 — 7.2 17 — 341 194 — — 143

101 SA SWFWMD 10/31/05 36 14 12 5.8 23 0.06 87 7.5 27.9 399 — 4.7 — 1.0

102 IAS FDEP, SFWMD 02/24/00 26 20 4.0 15 6.9 1.3 1.8 — 24.8 361 225 7.4 — 176

104 UFA FDEP, SWFWMD 03/13/00 12 4.7 2.2 6.8 6.1 0.18 0.2 — 22.5 133 96 7.0 — 55

106 SA SWFWMD 04/29/02 32 3.0 1.4 4.0 8.3 0.09 21 — 24.6 224 135 5.9 — 71

107 IAS SWFWMD 09/24/07 0.70 0.65 1.3 4.1 7.3 0.06 0.23 11 24.8 — — 5.0 — 7.5

108 IAS/UFA USGS 11/07/07 39 18 2.1 16 23 0.37 27 30 24.2 424 265 7.6 180 150

109 UFA USGS 11/07/07 25 14 1.5 9.1 13 0.28 43 17 25.2 314 204 8.0 130 88

111 SA USGS 01/15/08 32 7.2 1.5 16 21 0.24 0.23 17 23.2 287 184 6.3 110 109

112 UFA USGS 03/19/08 26 34 5.0 36 35 0.75 41 23 25.3 573 332 7.7 220 205

113 UFA USGS 12/03/07 33 9.6 1.8 5.4 6.3 0.26 18 18 27.8 356 206 7.5 130 114

115 SA FDEP, SFWMD 04/05/00 9.1 0.03 0.10 2.3 3.9 0.10 7.1 — 23.2 61 53 5.5 — 13

116 IAS SWFWMD 02/07/02 37 19 1.3 13 12 0.49 24 — 23.9 390 218 7.6 — 161

117 UFA USGS 03/19/08 21 9.7 1.5 5.6 6.5 0.30 27 17 25.1 223 136 8.1 99 76

118 SA SFWMD 10/25/00 120 7.6 2.5 18 14 — — — 23.7 640 — 7.3 — 300

119 SA SWFWMD, FDEP 05/01/00 44 16 15 5.6 20 0.10 76 — 26.1 368 277 6.9 — 37

121 SA SFWMD 01/30/01 100 8.4 1.9 31 36 — — — — — 330 — — 280

122 SA SWFWMD 10/31/07 4.3 0.33 0.58 1.8 3.3 <0.02 7.4 3.3 27.1 44 — 4.6 — 1.5

123 IAS USGS 12/03/07 32 19 3.0 14 9.6 1.1 1.3 37 23.7 374 247 7.6 170 184

124 UFA/LFA? USGS 03/19/08 103 54 4.2 129 258 0.25 300 20 27.1 1,590 980 7.6 480 95

125 UFA/LFA? USGS 03/19/08 — — — — 253 — 293 — — 1,570 — — — —

126 UFA USGS 01/16/08 — — — — 5.1 — 2.4 — 24.9 140 98 8.1 — —

127 IAS FDEP, SWFWMD 02/27/02 52 9.4 2.3 14 10 0.10 <0.20 — 24.2 394 234 7.4 — 192

129 SA SFWMD 01/31/01 110 5.1 1.9 25 19 — — — — — 350 — — —

Appendix 2. Summary of major inorganic constituents and physical characteristics in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County 

and parts of adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey (USGS) site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for water 

temperature, in degrees Celsius; specific conductance, in microsiemens per centimeter; and pH, in standard units. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water 

Management District; SWFWMD, Southwest Florida Water Management District; —, not analyzed; <, less than the value, E, estimated value]
80    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well

No.

Hydrogeologic

unit

Source of data Sampling

date Calcium Magnesium Potassium Sodium Chloride Fluoride Sulfate Silica

Water

temperature

Specific

conductance

Total

dissolved

solids

pH

Hardness

as

CaCO3

Alkalinity

as

CaCO3

131 UFA/LFA? USGS 03/19/08 — — — — 80 — 110 — — 684 — — — —

132 SA FDEP 05/16/00 0.86 0.46 0.11 2.2 5.5 0.10 5.3 23.6 53 40 4.2 — 1.0

136 SA HC 12/06/07 — — — 3.8 6.5 — — — 25.6 179 90 4.4 — —

137 UFA USGS 01/16/08 25 13 1.4 8.1 13 0.20 36 19 26.3 299 194 7.8 130 92

138 IAS/UFA SWFWMD 03/05/02 20 10 1.2 5.1 5.5 0.44 13 — 24.2 226 133 8.0 — 92

139 SA SWFWMD 10/30/07 17 6.2 14 2.7 7.7 0.22 63 6.7 27.3 271 — 4.1 — —

140 IAS? USGS 12/04/07 20 3.3 1.8 6.4 4.1 <0.12 E.17 26 24.3 159 106 7.3 63 73

142 UFA USGS 12/04/07 30 8.9 0.65 3.8 6.6 0.13 7.8 12 25.7 242 141 8.0 120 107

145 IAS USGS 01/25/08 48 1.9 1.5 15 6.1 0.12 <0.18 36 20.2 304 212 8.4 130 154

146 UFA USGS 01/25/08 26 15 2.5 17 22 0.31 9.4 33 23.4 348 221 8.7 140 143

148 UFA USGS 11/08/07 21 7.9 1.2 4.6 6.1 0.09 0.57 20 24.9 188 109 8.1 85 84

149 SA SWFWMD 10/30/07 47 14 15 5.1 23 0.16 54 5.5 — 458 — 6.7 — 43

150 SA USGS 01/15/08 3.8 0.81 0.06 6.6 8.2 <0.12 9.8 5.9 23.9 88 122 4.1 13 —

153 IAS SWFWMD 04/13/07 15 9.2 1.8 7.4 6.1 — 6.8 12 24.4 184 104 8.4 — 79

154 UFA SWFWMD 04/13/07 18 7.9 1.1 4.5 5.4 — 6.9 12 25.2 170 121 8.1 — 71

156 SA SWFWMD 08/06/07 17 5.2 7.3 2.1 8.3 0.04 30 3.6 26.6 197 — 5.4 — 11

157 SA FDEP, SFWMD 02/23/00 60 7.0 3.7 4.7 5.1 0.10 0.20 — 24.0 369 224 6.9 — 190

158 UFA SWFWMD 09/05/01 — — — — 5.6 — 19 — — 192 — 8.3 — —

162 SA FDEP, SFWMD 04/13/00 13 4.7 5.5 5.5 15 0.10 30 — 24.0 218 110 4.1 — 1.0

163 UFA SWFWMD 10/18/07 19 6.5 0.71 4.5 7.0 0.15 6.7 11 25.7 180 — 8.1 — 71

165 SA USGS 01/15/08 2.7 0.77 0.29 9.9 13 <0.12 1.9 9.6 23.2 86 92 5.3 10 9.0

166 IAS USGS 01/15/08 16 9.4 1.2 4.9 6.6 1.1 2.2 14 19.7 181 113 8.0 81 77

167 SA SWFWMD 04/26/07 18 9.1 8.1 9.9 19 0.09 54 4.2 27.3 280 — 4.5 — —

168 SA SWFWMD 10/29/07 26 20 14 5.4 29 0.03 68 5.4 26.2 429 — 4.4 — —

172 UFA USGS 07/15/03 17 6.1 0.50 3.0 4.5 0.10 6.0 11 25.7 154 104 8.2 70 65

173 SA SFWMD 06/04/07 58 6.5 1.8 32 41 — 1.0 — 23.3 525 330 7.6 — 200

174 IAS SFWMD 06/04/07 42 9.9 1.5 24 32 — 0.17 — 24.5 510E 310 7.5 — 170

175 UFA USGS 01/23/08 35 18 1.7 26 47 0.63 23 31 25.0 453 262 7.7 166 132

Appendix 2. Summary of major inorganic constituents and physical characteristics in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County 

and parts of adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey (USGS) site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for water 

temperature, in degrees Celsius; specific conductance, in microsiemens per centimeter; and pH, in standard units. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper 

Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water 

Management District; SWFWMD, Southwest Florida Water Management District; —, not analyzed; <, less than the value, E, estimated value]
Appendix 3    81

Appendix 3. Summary of selected trace metals and nutrients in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County and parts of 

adjacent counties.

[Well locations shown in figure 11. U.S. Geological Survey site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for strontium and iron 

which are in micrograms per liter. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant 

report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management District; SWFWMD, Southwest Florida Water Management District; 

USGS, U.S. Geological Survey. —, not analyzed; <, less than the value, E, estimated value.]

Well No. Hydrogeologic

unit” Source of data Sampling date Strontium Iron Ammonia as N,dissolved

Nitrite as N,

dissolved

Nitrate + nitrite as

N, dissolved

Total nitrogen,

dissolved

Ortho-phosphate

as P, dissolved

Phosphorus,

dissolved

2 UFA SWFWMD 10/01/04 9,440 19.3 — — — — — —

3 UFA SWFWMD 02/13/03 37,700 40 — — — — — —

4 SA FDEP, SFWMD 04/17/01 — — 0.46 — 0.005 0.004 0.006

5 UFA SWFWMD 05/25/07 23,700 <12.5 — — — — — —

6 UFA USGS 11/07/07 5,210 29 0.136 <0.002 <0.04 0.15 0.013 0.014

7 SA FDEP, SFWMD 04/17/01 — — 0.20 — 0.005 — 0.024 0.037

8 UFA USGS 12/05/07 999 263 0.388 <0.002 <0.04 0.44 0.01 <0.006

9 SA USGS 11/07/07 31 1,100 0.175 <0.002 <0.04 0.37 0.047 0.059

11 UFA SWFWMD 09/07/07 15,400 <12.5 — — — — — —

13 IAS SWFWMD 09/07/07 8,490 <12.5 — — — — — —

14 SA SWFWMD 09/07/07 <250 880 — — — — — —

15 SA FDEP, SFWMD 04/17/01 — — 0.16 — 0.024 0.041 0.034

16 UFA Consult 06/27/07 — — — — — — — —

17 UFA SWFWMD 03/13/03 62,700 13 — — — — — —

18 IAS SWFWMD 09/10/07 3,320 88.2 — — — — — —

21 SA SWFWMD 11/08/07 2,050 42.4 — <0.005 9.6 — — 0.015

22 IAS USGS 09/25/07 26,900 <90 1.1 <0.002 <0.06 1.2 E.006 <0.006

23 SA SWFWMD 11/08/07 1,470 <12.5 — 0.0097 11 — — 0.005

25 IAS SWFWMD 06/21/07 720 <12.5 — — — — — —

26 SA SWFWMD 06/30/05 <250 102 — — — — — —

27 UFA SWFWMD 06/21/07 1,550 <12.5 — — — — — —

28 SA SWFWMD 08/16/07 2,190 24.9 — <0.005 9.6 — — <0.005

29 UFA SWFWMD 09/06/00 1,980 60 — — — — — —

30 SA USGS 09/25/07 76 2,270 0.494 <0.002 <0.06 1.8 0.105 0.101

31 IAS USGS 09/25/07 — — — — — — — —

32 UFA SWFWMD 10/27/01 — — — — — — — —

34 UFA USGS 03/19/08 23,200 E24 0.241 <0.002 <0.04 0.28 E.006 <0.006

35 UFA USGS 03/19/08 — — — — — — — —

36 SA SWFWMD 08/15/07 <250 <12.5 — <0.005 3.2 — — <0.005

38 UFA USGS 11/07/07 17,100 27 0.195 <0.002 <0.04 0.18 0.009 0.008

39 UFA USGS 03/19/08 — — — — — — — —

40 UFA USGS 12/05/07 6,370 8.0 0.115 <0.002 <0.04 0.41 E.006 0.01

41 UFA USGS 09/26/07 2,600 10 0.291 <0.002 <0.06 0.33 0.016 0.014

42 SA USGS 12/05/07 6.8 15 <0.020 <0.002 0.79 0.85 0.006 0.006
82    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well No. Hydrogeologic

unit” Source of data Sampling date Strontium Iron Ammonia as N,dissolved

Nitrite as N,

dissolved

Nitrate + nitrite as

N, dissolved

Total nitrogen,

dissolved

Ortho-phosphate

as P, dissolved

Phosphorus,

dissolved

43 SA FDEP, SWFWMD 04/30/01 — — 0.068 — 0.31 — 0.004 0.004

44 UFA SWFWMD 11/15/07 18,700 <12.5 — — — — — —

47 UFA Consult — —

49 IAS USGS 12/05/07 28 <8.0 <0.020 <0.002 <0.04 <0.06 1.5 1.6

50 SA SWFWMD 11/06/07 <250 <12.5 — <0.005 1.4 — — 0.103

51 IAS USGS 03/18/08 451 <8.0 0.303 <0.002 <0.04 0.36 0.012 E.004

52 SA FDEP, SFWMD 04/18/01 — — 0.51 — 0.004 — 0.052 0.054

53 UFA USGS 09/25/07 15,600 23 0.184 <0.002 <0.06 0.21 0.01 0.008

55 UFA USGS 06/12/08 — — — — — — — —

56 UFA USGS 06/12/08 — — — — — — — —

57 UFA USGS 06/12/08 20,730 10 0.183 <0.002 <0.04 0.16 0.006 <0.006

58 IAS USGS 11/06/07 631 9.0 0.342 <0.002 <0.04 0.52 0.006 <0.006

59 SA FDEP, SFWMD 04/06/00 — — 0.39 — 0.005 — 0.005 0.043

60 SA FDEP, SFWMD 04/18/01 — — 0.76 — 0.004 — 0.035 0.032

61 UFA, IAS USGS 09/25/07 9,140 <6.0 0.307 <0.002 <0.06 0.41 0.008 <0.006

62 UFA USGS 09/25/07 16,700 22 0.261 <0.002 <0.06 0.29 0.01 E.004

63 UFA USGS 03/18/08 11,400 23 0.541 <0.002 <0.04 0.61 0.041 0.043

64 SA SWFWMD 11/06/07 640 15.9 — <0.005 22 — — 0.006

65 UFA SWFWMD 08/24/00 — — — — — — — —

66 SA SWFWMD 04/27/00 — — 0.42 — 0.022 — — 0.14

68 UFA USGS 12/05/07 2,050 82 0.214 <0.002 <0.04 0.27 0.022 0.023

69 IAS USGS 01/24/08 9,840 <8.0 0.274 <0.002 <0.04 0.33 0.007 <0.006

70 UFA USGS 01/24/08 14,000 <8.0 0.211 <0.002 <0.04 0.23 E.005 <0.006

71 SA FDEP, SFWMD 04/06/00 — — 1.3 — 0.017 — 0.034 0.052

72 UFA SWFWMD 03/09/04 23,800 16.4 — — — — — —

73 UFA USGS 09/25/07 6,350 28 0.183 <0.002 <0.06 0.98 0.018 0.015

74 UFA USGS 03/18/08 5,090 46 0.516 <0.002 <0.04 0.59 0.097 0.101

75 UFA, IAS SWFWMD 11/14/07 12,400 62.2 — — — — — —

78 SA SWFWMD 11/05/07 360 <12.5 <0.005 11 — — 0.009

79 UFA USGS 01/17/08 — — — — — — — —

80 UFA USGS 12/04/07 4,240 E6 0.148 <0.002 <0.04 0.16 0.014 0.014

81 SA SWFWMD 08/13/07 <250 <12.5 <0.005 8.4 0.007

83 IAS USGS 11/06/07 500 E5 0.58 <0.002 <0.04 0.90 0.006 <0.006

84 IAS USGS 01/16/08 — — — — — — — —

Appendix 3. Summary of selected trace metals and nutrients in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County and parts of 

adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for strontium and iron 

which are in micrograms per liter. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant 

report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management District; SWFWMD, Southwest Florida Water Management District; 

USGS, U.S. Geological Survey. —, not analyzed; <, less than the value, E, estimated value.]
Appendix 3    83

Well No. Hydrogeologic

unit” Source of data Sampling date Strontium Iron Ammonia as N,dissolved

Nitrite as N,

dissolved

Nitrate + nitrite as

N, dissolved

Total nitrogen,

dissolved

Ortho-phosphate

as P, dissolved

Phosphorus,

dissolved

85 UFA SWFWMD 04/15/02 18,900 <30 — — — — — —

86 SA SWFWMD 10/31/07 460 <12.5 — <0.005 9.4 — — 0.017

88 IAS SWFWMD 03/16/04 1,870 <12.5 — — — — — —

89 UFA SWFWMD 03/16/04 2,560 <12.5 — — — — — —

93 SA SWFWMD 06/29/05 <250 413 — — — — — —

94 IAS USGS 11/07/07 4,690 <8.0 0.456 <0.002 <0.04 0.59 0.01 <0.006

95 UFA, IAS SWFWMD 01/09/02 1,640 60 — — — — — —

96 IAS? USGS 03/19/08 615 — — — — — — —

97 UFA USGS 01/24/08 17,800 16 — — — — — —

99 SA SWFWMD 04/12/00 — 50 — — — — — —

100 UFA SWFWMD 12/06/01 4,380 50 — — — — — —

101 SA SWFWMD 10/31/05 930 <12.5 0.012 0.006 13 — 0.01 0.01

102 IAS FDEP, SFWMD 02/24/00 — — 0.26 — 0.004 — 0.004 0.004

104 UFA FDEP, SWFWMD 03/13/00 — — 0.071 — 0.22 — 0.051 0.043

106 SA SWFWMD 04/29/02 — — 0.19 — <0.02 — 0.14 0.15

107 IAS SWFWMD 09/24/07 <250 644 — — — — — —

108 IAS/UFA USGS 11/07/07 9,910 <8.0 0.329 <0.002 <0.04 0.42 0.007 E.004

109 UFA USGS 11/07/07 11,200 14 0.115 <0.002 <0.04 0.12 E.006 <0.006

111 SA USGS 01/15/08 801 410 0.337 <0.002 <0.04 0.51 0.40 0.43

112 UFA USGS 03/19/08 11,500 34 0.355 <0.002 <0.04 0.40 0.009 E.006

113 UFA USGS 12/03/07 7,110 460 0.254 <0.002 <0.04 0.32 0.251 0.272

115 SA FDEP, SFWMD 04/05/00 — — 0.062 — 0.02 — 0.004 0.005

116 IAS SWFWMD 02/07/02 — — 0.16 — 0.004 — 0.021 0.018

117 UFA USGS 03/19/08 5,010 15 0.122 <0.002 <0.04 0.12 0.009 0.007

118 SA SFWMD 10/25/00 — 220 — —

119 SA SWFWMD, FDEP 05/01/00 — — 0.01 — 17 — 4.5 5.2

121 SA SFWMD 01/30/01 — 890 — — — — —

122 SA SWFWMD 10/31/07 <250 <12.5 — <0.005 1.6 — — <0.005

123 IAS USGS 12/03/07 6,620 <8.0 0.297 <0.002 <0.04 0.32 0.009 E.003

124 UFA/LFA? USGS 03/19/08 999 27 0.254 <0.002 <0.04 0.27 0.009 0.006

125 UFA/LFA? USGS 03/19/08 — — — — — — — —

126 UFA USGS 01/16/08 — — — — — — — —

127 IAS FDEP, SWFWMD 02/27/02 — — <0.01 — 0.011 — 0.006 <0.004

129 SA SFWMD 01/31/01 — 420 — — — — — —

Appendix 3. Summary of selected trace metals and nutrients in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County and parts of 

adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for strontium and iron 

which are in micrograms per liter. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant 

report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management District; SWFWMD, Southwest Florida Water Management District; 

USGS, U.S. Geological Survey. —, not analyzed; <, less than the value, E, estimated value.]
84    Hydrogeology and Groundwater Quality of Highlands County, Florida

Well No. Hydrogeologic

unit” Source of data Sampling date Strontium Iron Ammonia as N,dissolved

Nitrite as N,

dissolved

Nitrate + nitrite as

N, dissolved

Total nitrogen,

dissolved

Ortho-phosphate

as P, dissolved

Phosphorus,

dissolved

131 UFA/LFA? USGS 03/19/08 — — — — — — — —

132 SA FDEP 05/16/00 — — 0.071 — 0.006 — 0.005 0.01

136 SA HC 12/06/07 — 0.39 — — <0.02 — — —

137 UFA USGS 01/16/08 10,500 32 0.137 <0.002 <0.04 0.15 0.015 0.012

138 IAS/UFA SWFWMD 03/05/02 — — 0.18 — <0.004 — 0.006 0.006

139 SA SWFWMD 10/30/07 360 19.3 — <0.005 8.1 — — 0.011

140 IAS? USGS 12/04/07 70 775 0.193 <0.002 <0.04 0.19 0.221 0.108

142 UFA USGS 12/04/07 3,500 21 0.187 <0.002 <0.04 0.18 0.031 0.03

145 IAS USGS 01/25/08 302 9.4 — — — — — —

146 UFA USGS 01/25/08 11,200 <8.0 — — — — — —

148 UFA USGS 11/08/07 725 57 0.133 <0.002 <0.04 0.15 0.006 0.006

149 SA SWFWMD 10/30/07 <250 <12.5 — <0.005 19 — — 0.392

150 SA USGS 01/15/08 35 432 0.041 0.004 <0.04 1.4 0.05 0.062

153 IAS SWFWMD 04/13/07 3,230 12.5 — — — — — —

154 UFA SWFWMD 04/13/07 2,510 12.5 — — — — — —

156 SA SWFWMD 08/06/07 <250 <12.5 — <0.005 7.7 — — <0.005

157 SA FDEP, SFWMD 02/23/00 — — 0.27 — 0.004 — 0.026 0.036

158 UFA SWFWMD 09/05/01 — — — — — — — —

162 SA FDEP, SFWMD 04/13/00 — — 0.01 — 8.9 — 0.012 0.022

163 UFA SWFWMD 10/18/07 1,490 <12.5 — — — — — —

165 SA USGS 01/15/08 24 5,200 0.225 <0.002 <0.04 0.92 0.027 0.031

166 IAS USGS 01/15/08 2,270 14 0.059 <0.002 <0.04 0.06 E.006 <0.006

167 SA SWFWMD 04/26/07 <250 <12.5 — <0.005 7.1 — — 0.006

168 SA SWFWMD 10/29/07 <250 <12.5 — <0.005 20 — — <0.005

172 UFA USGS 07/15/03 1,910 5.0 0.02 <0.010 <0.02 — 0.01 —

173 SA SFWMD 06/04/07 — — — — — — — —

174 IAS SFWMD 06/04/07 — — — — — — — —

175 UFA USGS 01/23/08 4,069 26 — — — — — —

Appendix 3. Summary of selected trace metals and nutrients in the surficial aquifer and intermediate and Floridan aquifer systems in Highlands County and parts of 

adjacent counties.—Continued

[Well locations shown in figure 11. U.S. Geological Survey site identification numbers and station names are given in appendix 1. Concentrations shown in milligrams per liter, except for strontium and iron 

which are in micrograms per liter. Hydrogeologic unit: SA, surficial aquifer, IAS, intermediate aquifer system; UFA, Upper Floridan aquifer; LFA, Lower Floridan aquifer. Source of data: Consult, consultant 

report; FDEP, Florida Department of Environmental Protection; HC, Highlands County; SFWMD, South Florida Water Management District; SWFWMD, Southwest Florida Water Management District; 

USGS, U.S. Geological Survey. —, not analyzed; <, less than the value, E, estimated value.]
Author—Spine Title—Report Series Name 0000

ISBN

Printed on recycled paper

Printed on recycled paper

Rick M. Spechler – – USGS/SIR 2010–5097 Hydrogeology and Groundwater Quality of Highlands County, Florida